THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE

DEPARTMENT OF MATERIAL SCIENCE AND ENGINEERING

DEVELOPMENT OF KEVLAR ARAMID NANOFIBROUS MEMBRANES FOR NANOFILTRATION SEPARATION PROCESSES

NATALIE DAYRIT MAMROL

FALL 2020

A thesis submitted in partial fulfillment

of the requirements for a baccalaureate degree

in Material Science and Engineering with honors in Material Science and Engineering

Reviewed and approved* by the following:

Michael Hickner Professor of Materials Science and Engineering, Chemical Engineering

Thesis Supervisor

Robert Allen Kimel Associate Professor of Materials Science and Engineering

Associate head for Undergraduate Studies in Material Science and Engineering Honors Adviser

* Signatures are on file in the Schreyer Honors College.

i

ABSTRACT

There is a critical need for sustainable and advanced separation processes to provide access to

clean water and recover or separate hazardous materials from waste streams as the global population

skyrockets and millions of people face water shortages due to contaminated water and depletion of natural

resources.

Therefore, this thesis reports two pressure-driven nanofiltration membranes for organic solvent

nanofiltration (OSN) and desalination applications with a sustainability focus. The first membrane

reported is a thin film composite (TFC) Kevlar aramid nanofibrous (KANF) membrane synthesized via a

pressure vacuum filtration and heat treatment method. This membrane utilized a green approach to create

a controllable membrane structure through a simple deposition of Kevlar aramid nanofibers (KANFs)

onto a microfiltration support membrane and subsequent heat treatment. With this method, the water

between KANFs was removed to form a nanofiltration selective layer with adjustable thickness. Proof of

concept and potential of this membrane as a viable and sustainable fabrication method is reported,

however future work must be completed before this can be considered a viable fabrication method for

OSN membranes.

The second membrane reported is a thin film composite (TFC) KANF hydrogel membrane that

used a novel approach to perform interfacial polymerization (IP) of piperazine (PIP) (0.015, 0.0175 wt%)

and trimethyl chloride (0.01 wt%) onto a Kevlar aramid nanofibrous hydrogel membrane with thickness

of the selective layer as low as 15.5 nm. This method yields superior desalination performances with an

ultrafast permeance of 52.8 and 62.9 Lm-2h-1bar-1 and a rejection of 96.4% and 93.5% for Na2SO4. This

method utilized the hydrogel as a free water phase for IP and reduces the diffusion of PIP monomers to

the interaction surface, hence resulting in an extremely thin selective layer. Overall, this membrane

outperformed current and state-of-the-art membranes with permeability nearly 3 times higher than the

average, and it reduced the fabrication steps and simplified the scalability for a green alternative

membrane technology.

ii

TABLE OF CONTENTS

LIST OF FIGURES ..................................................................................................... iii

LIST OF TABLES ....................................................................................................... iv

ACKNOWLEDGEMENTS ......................................................................................... v

Preface.......................................................................................................................... viii

Chapter 1 Introduction ................................................................................................ 1

Motivation of this work .................................................................................................. 4

Chapter 2 Literature Review ....................................................................................... 6

Conventional Membrane Separation Technology .......................................................... 6 Membrane Structure, Properties, and Characterization........................................... 7 Membrane Synthesis .............................................................................................. 9 Membrane Driving Forces ...................................................................................... 12

Membrane Application: Organic Solvent Nanofiltration ................................................ 13 Sustainability Assessment of OSN Membranes ...................................................... 14

Membrane Application: Desalination by Nanofiltration................................................. 15 Kevlar Aramid Nanofiber Membranes ........................................................................... 16

Structure and Synthesis of KANFs ......................................................................... 16 Key Properties ........................................................................................................ 18 Tunable Structure ................................................................................................... 18 Physico-Chemical Stability .................................................................................... 19 Hydrophobicity/ Hydrophilicity ............................................................................. 19 Selectivity ............................................................................................................... 20 Design of KANF Fabricated Membranes ............................................................... 20 Applications of KANF Membranes ........................................................................ 22

Chapter 3 Engineering Considerations ....................................................................... 23

Considerations in Engineering and Design..................................................................... 23 Economic Issues ..................................................................................................... 23 Environmental Issues and Sustainability ................................................................ 26 Ethical, Social, and Political Issues ........................................................................ 27 Health and Safety ................................................................................................... 29 Code of Hammurabi ............................................................................................... 30

Chapter 4 Experimental Procedures............................................................................ 31

Materials ........................................................................................................................ 31 Methods ......................................................................................................................... 33

Preparation of KANF and DMSO Solution ............................................................ 33

iii

Membrane Characterization ........................................................................................... 34 Filtration Setup ....................................................................................................... 34 Membrane Permeation............................................................................................ 35 Membrane Selectivity and Rejection of Salts or Dyes ............................................ 36 Membrane Surface Characterization ...................................................................... 37

Chapter 5 OSN KANF Pressure Vacuum Filtration with Heat Treatment Membrane Results and Discussion ......................................................................................... 40

Membrane Design Strategy ............................................................................................ 40 Membrane Fabrication Methods .................................................................................... 42

Thickness Calculation ............................................................................................ 42 Vacuum Assisted Filtration .................................................................................... 43

Membrane Characterization Results ............................................................................... 44

Chapter 6 Hydrogel Assisted Interfacial Polymerization Results and Discussion ..... 47

Membrane Design Strategy ............................................................................................ 47 Membrane Fabrication Methods .................................................................................... 49

Synthesis of Nanofibrous Hydrogel Support Saturated with PIP Monomers .......... 50 Interfacial polymerization on nanofibrous hydrogel for TFC nanofiltration membrane 51 Interfacial polymerization on conventional PSU ultrafiltration membrane for

Comparison .................................................................................................... 51 Membrane Characterization Results ............................................................................... 51

Permeability ........................................................................................................... 52 Selectivity and Rejection of Salts and Dyes ........................................................... 55 Surface Characterizations ....................................................................................... 57

Chapter 7 Conclusions and Future Work .................................................................... 62

TFC Vacuum Filtration KANF Membrane for Organic Solvent Nanofiltration ............. 62 TFC KANF Hydrogel Membrane for Desalination ........................................................ 63

References .................................................................................................................... 66

iv

LIST OF FIGURES

Figure 1 Bar graph of increasing number of publications on OSN membranes ..................... 4

Figure 2 Diagram of membrane in a feed solution under a driving force ............................... 7

Figure 3 Schematic of symmetric and asymmetric membrane structures18 ............................ 8

Figure 4 Interfacial polymerization between PIP and TMC23 ............................................... 12

Figure 5 Strategy to develop greener membranes through the principles of green chemistry25 14

Figure 6 Energy consumption to concentrate 1 m3 of a dilute solution in methanol using (a) distillation and (b) membrane25 ...................................................................................... 15

Figure 7 a) Synthesis of aramid monomer (PPTA) from p-phenylene and diamineterephthaloyl chloride; (b) Homogenization of Kevlar into homogeneous KANF solution; c) Structural transformation of macroscopic aramid fibers into nanofibers; Dissolution of Kevlar with DSMO/water with KOH catalyst system (d) Splitting of PPTA threads into nanofibers to form KANF solution29 .................................................................................................... 18

Figure 8 Comparison of KANF Hydrogel to Conventional (PSU) Polymeric Membrane1 .... 21

Figure 9 Diagram of coating line for fabrication of support membrane41 ............................... 25

Figure 10 Diagram of reaction line for fabrication of thin-film composite RO membrane41 .. 25

Figure 11 Dissolution of PPTA into red and viscous KANF Solution1 .................................. 34

Figure 12 Dead end filtration equipment including a) filtration cell; b) 3-way valve; c) pressure regulator54 ...................................................................................................................... 35

Figure 13 Picture of Crossflow Filtration Unit Set Up54 ........................................................ 35

Figure 14 Lab assembled apparatus for vacuum assisted filtration54 ...................................... 43

Figure 15 Schematic for vacuum assisted filtration over a microporous support for KANF membranes ..................................................................................................................... 44

Figure 16 SEM images of a) Alumina microporous support membrane; b) Alumina and KANF membrane; c) Uncoated regions on alumina support; d) PTFE microfiltration support membrane e) PTFE and KANF membrane .................................................................... 46

Figure 17 Step by step process for fabrication of hydrogel-TFC membrane1 ......................... 49

Figure 18 KANF Hydrogel post drying with super critical dryer1.......................................... 50

Figure 19 Impact of Applied Pressure on TFC KANF Membrane ......................................... 52

v Figure 20 Permeability and Rejection for Varying PIP Concentrations for the TFC KANF

Hydrogel Membrane ...................................................................................................... 53

Figure 21 Permeability of TFC KANF Hydrogel membrane, TFC PSU Membrane, and Free Standing Membrane ....................................................................................................... 54

Figure 22. Rejection of MgSO4, MgCl2, NaCl, Na2SO4 salts by the TFC KANF Hydrogel Membrane ...................................................................................................................... 55

Figure 23 Na2SO4 Rejection of TFC KANF Hydrogel Membrane, TFC PSU Membrane, and Free Standing Membrane ............................................................................................... 56

Figure 24. TFC KANF Membrane Desalination Performance Over 6 Hr .............................. 57

Figure 25 Picture of TFC KANF Hydrogel Membrane .......................................................... 58

Figure 26 SEM images of a) the nanofibrous network of KANFs in the hydrogel membrane; b) the surface of the TFC PSU KANF hydrogel membrane ............................................... 59

Figure 27 TEM images of the thickness of the selective separation layer of the KANF TFC hydrogel membrane fabricated with PIP concentrations of: a) 0.015 wt%; b) 0.02 wt%; and c) 0.04 wt%, and d) the thickness of the freestanding membrane at PIP concentrations 60

Figure 28 AFM morphology of Hydrogel-TFC membranes synthesized from PIP concentration of 0.0175 wt% and 0.02 wt% ............................................................................................. 60

Figure 29 Water contact angle of dry nanofibrous hydrogel (72°) and Hydrogel-TFC membrane (PIP-0.015，54°) ........................................................................................................... 61

Figure 30 Surface morphology of Hydrogel-TFC membranes ............................................... 65

Figure 31 Surface morphology of PSU-TFC membranes ...................................................... 65

vi

LIST OF TABLES

Table 1 List of Materials for Experiments ............................................................................. 31

Table 2 List of Solutes for Membrane Characterization......................................................... 32

Table 3 Dyes Used for Rejection Tests .................................................................................. 32

Table 4 Roughness of TFC KANF Hydrogel membranes ...................................................... 61

vii

ACKNOWLEDGEMENTS

There are several people that I want to acknowledge for the completion of this thesis, mentorship

through my undergraduate experience, and for their unconditional support and love.

First, I would like to thank my supporting faculty, department, and advisers for giving me this

opportunity to conduct research and write a senior honors thesis. I am grateful for Dr. Hickner and his

support, research opportunities, and academic freedom to pursue my scientific interests. I would like to

thank Dr. Van der Bruggen for accepting me into his lab with a collaborative and supportive research

environment. Thank you to Dr. Kimel for supporting my application to enter the Schreyer Honor College

and pursue my research interests. I would like to thank Dr. Runt and Dr. Preeya Kuray for getting me

started in research through the NASA WISER Freshman Internship. Also, I want to give a shoutout to

Miss Meg Abplanalp for her superior advising and support.

To my mentors in this project, Dr. Shushan Yuan, Dr. Yan Zhao, and Dr. Zhaohuan Mai; I would

like to say I am incredibly grateful for your guidance, teachings, and support. I would have never been

able to complete this thesis without you. I learned so much about the scientific method, membrane science

and characterization, writing research papers and literature reviews, and persistence in experimentation.

Thank you for including me into your research efforts with an abundance of opportunities and into your

lives. I also want to thank the rest of Dr. Van der Bruggen’s lab for the excellent memories and

collaboration.

To my friends, thank you for listening to me and supporting me through every stressful and

exciting moment. It means the world to be able to share and grow through college with you.

Finally, to my family: Maria and Francis Mamrol, Alex and Jimmy Mamrol, and Virginia

Mamrol, thank you for everything; I love you very much.

viii

Preface

This thesis contains two novel major works that I completed during my undergraduate career

related to the development of Kevlar aramid nanofibrous (KANF) membranes for organic solvent

nanofiltration and nanofiltration for desalination separations. The two works that I have included are a

vacuum filtration technique and heat treatment method for KANF TFC membranes, and interfacial

polymerization technique for TFC KANF hydrogel membranes. These works were completed during a

study abroad research experience and continued with cooperation at my home university, Penn State

University.

Through the Euroscholars Research Abroad program, I was fortunate to work in Belgium at De

Katholieke Universiteit Leuven (KU Leuven) in the membrane science group led by Dr. Van der

Bruggen. During this experience, I contributed to two major works published in The Journal of Materials

Chemistry1 and The Journal of Membrane Science2 as the fourth and fifth coauthor, respectively, and

contributed as an editor to another published work in Chemical Society Reviews.3 I also recently

submitted a literature review on electro-driven membranes for Lithium recovery as a second co-author.

For this thesis, I draw upon my significant contributions to these projects and my own novel work on the

vacuum filtration and heat treatment method technique for KANF membranes.

My contributions to these projects are related to my material science and engineering area of

study with emphasis on polymeric synthesis and design for membranes. In these works, I led or co-led the

synthesis and modification of the polymer-based membrane; testing of permeability, selectivity, and

stability; and analysis of SEM/TEM, water contact angle, water uptake, surface roughness

characterization. Other characterization pertaining to these works will be mentioned in this thesis such as

XPS, zeta potential, and mechanical strength, however I was not the lead on those characterizations.

During my time at Penn State University, I worked in Dr. Hickner’s lab on 3D printing of

colorimetric sensing membranes and sensors. I would have liked to integrate the works from both

ix universities together. Although due to time constraints and the ramifications on research due to the

COVID-19 pandemic, I was unable to integrate the two works together to produce a solvent resistant 3D

printable membrane.

1

Chapter 1

Introduction

The current impact of global population growth and technological advancements is

unprecedented in significance and consequence on the environment and global resources.4 Rapid

consumption of goods and technological innovations in industrialization, manufacturing, and energy

production have increased human prosperity throughout the world.5,6 In effect, rates of infant mortality

decreased, human life expectancy increased, adult literacy increased, access to education improved, and

global food production increased faster than the population grew.7 However, this prosperity is at the

expense of the depletion of the world’s stock of natural resources, and ecological and development

models shows trends of the detrimental consequences leading to the developing ecological crisis and

widening social disparities on future generations.8

Therefore, a critically important challenge to sustain current global development is in the

advancement of green technology. “Green” technology refers to the field focused on the development of

materials and processes to reduce current society’s environmental impact. The goals of this field are

rooted in sustainability, source reduction, and innovation.9 Furthermore, there is a current push to find

green technologies to address the global drinking water crisis. The World Health Organization (WHO)

estimates that there are over one billion people who cannot access clean water. In addition, health

monitoring reports that everyday about 4000 children die from waterborne diseases as a result of water

pollution.10 Part of this problem lies in that the available drinking water is either brackish or polluted by

human activities and the discharge of effluents from industrialization.

Solvent losses account for a major proportion of organic pollution. In chemical and

pharmaceutical industries, organic syntheses typically use organic solvents as raw materials, cleaning

2 agents, and reactants with high value products that must be recovered or discarded by the end of the

process. These industries consume an excessive amount of solvents, and it has been estimated that the

annual industrial scale production of organic solvents is nearly 20 million MT (metric tons)11. The

treatment including separation, recovery, and disposal of these organic waste streams consume a lot of

energy that accounts for nearly 40-70% of both capital and operating costs in chemical processing

operations, and separation processes account for 10 to 15 percent of the world’s energy consumption.12

While the excessive consumption of nonrenewable and toxic solvents is unsustainable, solvation remains

a critical component for maintaining selectivity control, purity, safety, and improved handling for many

chemical processes.

Additionally, the use of water as a solvent in industrial applications produces wastewater streams

that become polluted due to the discharge of potential emerging pollutants (PEPs) such as toxic

chemicals, pharmaceutical by-products, heavy metals, fertilizers, sludge, and endocrine disruptors. These

pollutants can contribute to waterborne pathogens that have severe health consequences if they diffuse

into groundwater and pose serious threats to water ecology at large. PEPs require clear identification,

separation, and disposal, however according to the United States Environmental Protection Agency

(USEPA), these hazardous materials lack the regulatory standards.10 Likewise, a current issue is the

pollution of drinking water with an array of violate organic compounds and semi-volatile organic

compounds following the California forest fires. In the aftermath of the fire, toxins are released from the

plumbing systems, and damage can reside in the pipes for years.13

Another potential source of water is from brackish or brine water, domestic waste waters with

high total dissolved solids, and on-site treatment of water used in fracking treated within desalination

plants for potable use. For example, in 2015, the International Desalination Association reported there are

at least 18,426 desalination plants in over 150 countries that each day produce 86.8 million m3 or 22.9

billion gallons of water. Potential saltwater sources typically contain total dissolved solids of 1,000 to

3 3,000 mg/l in brackish water and 35,000 mg/l in open ocean. These sources also contain a variety of ions

such as sodium, calcium, magnesium, and sometimes even contain microbes.14

Conventional separation treatments such as adsorption, distillation, liquid-liquid extraction, media

filtration, and macro-porous polymer extraction can be used in the treatment of wastewater, organic waste

streams, and salt water, but are energy intensive and need improvements in separation efficiency.

Membrane separation-based processes are another technique to treat water and organic waste streams that

have a low initial investment, low costs of production and maintenance, are less energy intensive, and

produces high ratio of water quality to solute recovery. In fact, membrane based separation systems have

reported potential to decrease energy consumption by 90% to traditional methods.15 There are many

different membrane separation processes including microfiltration (MF), ultrafiltration (UF),

nanofiltration (NF), and reverse osmosis, and these processes separate out particle sizes ranging from

molecular weight cutoffs of 3,000 to 500,000 Dalton (Da), 2000-100,000 Da, 300-500 Da, and 100-200

Da, respectively. Based on the size of solvents and ions in water, nanofiltration membrane technology is

an excellent process for the highest purity in separation and recovery of small solvent molecules or

purification of brackish water.

For example, in the last 10 years, there have been an increasing amount of studies on OSN

membrane synthesis and fabrication (Figure 1), however it has yet to make an industrial breakthrough.

There are two reasons for this: the need to improve the chemical stability and maintain sustainable

scalability of the nanofiltration membranes.12 OSN membranes synthesized with ordered structures and

controllable chemical activity are ideal for this application.

4

Figure 1 Bar graph of increasing number of publications on OSN membranes

Furthermore, there is significant interest in increasing the efficiency of desalination plants

through the fabrication of membranes with faster permeance and high rejection.1 Higher efficiency

ultimately provides more water to regions with critical shortages and reduces the consumption of energy

leading to a more sustainable process. Lastly, the fabrication and life cycle of the membranes need to be

sustainable to offset any potential CO2 footprint.

Motivation of this work

There is a need for green technology for reducing solvent waste and pollution into wastewater

steams from industrial chemical processes and for increasing the efficiency of desalination plants. The

goal of this work is to address this challenge with the synthesis of “green” fabrication methods for KANF

membranes with improved solvent resistance for industrial applications and desalination performance.

There are several criteria for the KANF nanofiltration membranes to achieve this goal. First, the

criteria include using greener solvents and low toxicity chemicals for casting, coating, and crosslinking,

and reducing solvent waste in membrane production. The next criteria are minimizing energy usage in

preparation and synthesis and exploring the use of new solvent resistance materials in membrane

5 fabrication. Finally, in conjunction, this work aimed to improve membrane separation performance

against current competition

With these criteria, two novel solvent-limited fabrication techniques were developed with a high-

performance polymer, Kevlar aramid nanofibers (KANFS), to prepare OSN and desalination NF

membranes. KANFS are an emerging material for the synthesis of membranes with excellent physical

properties, high mechanical strength, and solvent resistance. The research objectives of this thesis are

summarized in two parts: First, a pressure vacuum filtration method for the fabrication of KANF

membranes synthesized by the regeneration of hydrogen bonds by a heat treatment for organic solvent

nanofiltration. Second, a KANF hydrogel assisted interfacial polymerization TFC nanofiltration

membrane for desalination of water.

Overall, the separation performance and economic efficiency of membrane-based technology for

advanced separations of solvent are highly dependent on the membrane fabrication and structure.

Therefore, it is critical to understand conventional and current membrane separation technology before

the development of novel techniques.

6

Chapter 2

Literature Review

Conventional Membrane Separation Technology

Membrane science and technology is the field of engineering for the selective transport of a target

component or separation of a mixture by a semi-permeable barrier. Mixtures or feed solutions pass

through these barriers or membranes by a driving force such as pressure, concentration, electrical

potential, or temperature. Permeate passes through the membrane via flux or permeation and is enriched

with the target components. Retentate is retained by the membrane via selectivity and is enriched with the

leftover components as shown in Figure 2. Membranes are designed to have high selectivity and high flux

or permeability towards the target specie, mechanical strength, chemical stability, low fouling in

operating conditions, and cost-effective production and maintenance.16

Other advantages of membrane-based separation are the operations are often compact, cheap, and

simple. For example, membrane technology generally costs less, is easier to operate, and have high

efficiency and performance than distillation processes. However, some limitations of membranes include

lack of long term established reliability, need for some pre- and post- treatment procedures, and lower

mechanical strength. Research and developments in membrane technology actively find solutions to

overcome these limitations, and state-of-the-art membrane technology has many markets in desalination,

food processing, sterilization, hemodialysis, and alcohol recovery.17

7

Figure 2 Diagram of membrane in a feed solution under a driving force

Membrane Structure, Properties, and Characterization

Membranes are homogenous or heterogenous, symmetric or asymmetric, porous or dense,

sometimes charged or neutral, or at times even a liquid as shown in Figure 3. Asymmetric membranes are

the most important commercial type of membranes compared to symmetric membranes. In symmetric

membranes, the structure and composition are homogenous and usually are limited in application by the

greater thickness of the separation layer and low flux. Asymmetric membranes have layered structures

that differ in porosity, pore size, or even composition from top to bottom of surface. The top layer

typically has a thin and selective layer for selectivity of target specie and higher flux across the

membrane. The bottom layer is the support for the top layer and is usually thicker as a microporous

substrate. The bottom layer does not contribute to the selectivity but needs to be compatible with the top

layer to ensure membrane stability and handling. The cross-section of membranes is identified through

scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. These

methods are used to identity the structural properties of the membrane and is very important in the overall

performance of the membrane.17

8

Figure 3 Schematic of symmetric and asymmetric membrane structures18

Other important structural properties of membranes include the surface roughness of the top layer

and thickness of the top selective layer. Surface roughness of the top layer contributes to the fouling

potential of the membrane, essentially the stability of the membrane flux over time. Greater surface

roughness may increase the effective surface area of the selective layer for higher permeability and

performance, but also increases effect of membrane fouling.19 Surface roughness is characterized by

scanning electron microscopy and atomic force microscopy. In addition, the thickness of the selective

layer is characterized by scanning electron microscopy. 20

Physical properties also greatly influence the performance of the membrane including

hydrophilicity or hydrophobicity and swelling. Depending on the application of the membrane in

wastewater or organic waste streams, hydrophilicity or hydrophobicity determines its interaction and

potentially its rate of transport across the membrane. This property is determined by the contact angle of

water or sometimes solvent on the membrane surface. Swelling is another important physical property

because the degree of swelling in an aqueous solution may impact the stability of the membrane. For

9 example, if the water uptake in a hydrogel membrane is too high, it may rupture or tear. Swelling is

measured using a simple swelling test.20

Furthermore, chemical properties play a critical role the performance of the membrane. Surface

chemistry affects the interaction of the membrane surface to the solutes in solution. Due to the Donnan

effect, the flux or rejection of the membrane may be greatly impacted by the membrane electronegativity.

Furthermore, the membrane may become fouled or clogged based on the chemical interaction with the

feed solution. The surface chemistry is measured by x-ray photoelectron spectroscopy and attenuated total

reflection Fourier transform infrared spectroscopy. 20

Membrane Synthesis

The most common material for membranes is polymers for their low cost, scalability, and facile

fabrication. Some examples of commonly used hydrophobic polymers for membranes are poly(vinylidene

fluoride) (PVDF), polytetrafluoroethylene, (PTFE), poly(vinylidene fluoride) (PVDF), polypropylene

(PP), and polyethylene (PE). Some commonly used hydrophilic polymers are polyamide (PA), cellulose

acetate (CA), polysulfone (PSF), polyacrylonitrile (PAN), poly(piperazine amide), polyimide (PI), and

poly(ether imide) (PEI). 17

Polymeric membranes are formed by the polymerization of a monomer via condensation,

addition, or copolymerization reactions. Polymerization results in various structures, but 3D crosslinked

structures are preferred for membranes. Crosslinking results in a more rigid structure compared to

thermoplastic polymers. For example, the three most common ways to synthesize asymmetric membranes

are phase inversion process, interfacial polymerization, and solution coated composite membranes. The

most common way to synthesize symmetric membranes is solution casting.21

10 Solution Casting

Solution casting is a commonly used technique for laboratory characterization, and in this

method, a thin film of polymeric solution is spread onto a glass plate by a casting knife. This film is left to

evaporate solvent from the solution resulting in a thin and uniform membrane. Phase inversion is a similar

technique for asymmetric membranes that precipitates a polymeric membrane from a polymer solution

through solvent evaporation, cooling, or absorption of water from the vapor phase. In precipitation by

solution casting, polymer is dissolved into a two-component system that typically contains a volatile

solvent that the polymer is more soluble in and a less violate solvent that the polymer is less soluble in.

The solution is cast, and once the violate solvent evaporates, the polymer precipitates from the nonvolatile

solvent. There are several variables that affect this technique including weight percent of the polymer

solution, type of solvent, temperature, air humidity, and additives. By adjusting these variables, controlled

evaporation is achievable, and phase inversion membranes are tailorable for the desired application.21

Immersion Precipitation

The immersion precipitation technique is the most important method for fabrication of

ultrafiltration and reverse osmosis membranes. This technique is like solution casting but differs by

immersion of the cast dope solution into a precipitation medium to initiate phase inversion of the

membrane. There are several steps to achieve the desire properties of fabricated membranes. First, the

choice of polymer affects the performance once polymerized into a membrane. An ideal polymer is tough,

amorphous, has a glass transition temperature above operating conditions, solubility in a water-miscible

solvent, and high molecular weight. Polymers with these specifications are advantageous because they

form membranes with high mechanical strength, flexibility, and facile synthesis procedures. Second, the

choice of solvent is important to the fabrication process and stability of the membrane in different

environments. Aprotic solvents are desirable for casting solutions because they precipitate rapidly when

11 immersed in water and yield highly porous asymmetric membrane structures. Some example of aprotic

solvents is dimethyl formamide, N-methyl pyrrolidone and dimethyl acetamide. Third, the precipitation

medium is the next step for membrane fabrication. Water is typically used as the precipitation medium,

but organic solvent sometimes is used for a slower rate of precipitation and denser structure. Fourth,

additives may be added to the membrane structure to improve properties such as permeance or

selectivity.21 Overall, in this method, compared to solution casting, the cast dopant layer is submerged

into the precipitation medium to form a asymmetric membrane.

Interfacial Polymerization

Interfacial polymerization is the final method relevant to this thesis and is the precipitation of a

thin selective membrane layer on top of a microporous support. In this method, a reactive monomer, m-

phenylenediamine (MPD) in aqueous solution is saturated into a microporous support membrane. Then,

the membrane is immersed in water immiscible solvent with another monomer, trimesoyl chloride

(TMC), and forms a polyamide layer. Moreover, as the MPD is consumed near the surface and interface

of the reaction, the diffusion of MPD is limited by chemical interactions with the support membrane

resulting in a thin selective layer. Piperazine (PIP) is another commonly used monomer reacted with TMC

to form IP membranes due to its low cost and film forming capabilities and is shown in Figure 4.22 TFC

membranes formed with PIP and TMC typically show high water flux and low monovalent ion rejection

12 due to its loose structure and electronegativity. Furthermore, the most common TMC concentration in

literature ranged from 0.01 to 0.15 wt%.16,21

Figure 4 Interfacial polymerization between PIP and TMC23

Based on these three important membrane fabrication techniques, organic solvent nanofiltration

and desalination membranes are made and improved.

Membrane Driving Forces

The membrane separation process functions by selective transport of a compound through the

membrane. Transport of the compound occurs when there is a difference in electrochemical potential

between the two phases separated by the membrane until equilibrium is achieved between the two phases.

The thermodynamic equation to describe the electrochemical potential for membrane separations is given

by:

𝜇𝜇𝑖𝑖 = 𝜇𝜇𝑖𝑖𝑜𝑜 + 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑎𝑎𝑖𝑖 + 𝑉𝑉𝑖𝑖𝑃𝑃 + 𝑧𝑧𝑖𝑖𝐹𝐹Ψ

Where 𝜇𝜇𝑖𝑖 is the electrochemical potential of species i, 𝜇𝜇𝑖𝑖𝑜𝑜 is the electrochemical potential in standard

conditions, R is the ideal gas constant, T is the absolute temperature, 𝑎𝑎𝑖𝑖 is the chemical activity of species

i, 𝑉𝑉𝑖𝑖 is the molar volume of species i, P is the absolute pressure, 𝑧𝑧𝑖𝑖 is the valence of the ion (0 is non-

charged), F is the Faraday’s constant, and Ψ is the electrical potential over the membrane. Some

parameters are used to control transport through the membrane including T, 𝑎𝑎𝑖𝑖, P, and Ψ, and therefore

these parameters are the several types of driving forces for transport of species through a membrane.24

13 The driving force of interest for this thesis is pressure driven nanofiltration membranes.

Membranes driven by pressure are classified into four groups: microfiltration, ultrafiltration,

nanofiltration, reverse osmosis. The preparation of the membranes depends on the desired classification.

In depth detail about the theories of pressure driven membrane are not discussed in this thesis as they are

not studied in the experimental section. However, the permeability or flux and retention of the membrane

are important feature of the separation process and are related to the driving force. Molar flux Ni is given

by:

𝑁𝑁𝑖𝑖 = �𝑃𝑃𝑀𝑀𝑖𝑖)𝑅𝑅𝑀𝑀

� × 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑅𝑅𝑑𝑑 𝑓𝑓𝑓𝑓𝑑𝑑𝑓𝑓𝑓𝑓 = 𝑃𝑃𝑀𝑀𝚤𝚤���� × 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑅𝑅𝑑𝑑 𝑓𝑓𝑓𝑓𝑑𝑑𝑓𝑓𝑓𝑓

Where 𝑃𝑃𝑀𝑀𝑖𝑖 is the permeability, 𝑃𝑃𝑀𝑀𝑖𝑖 is the permeance, and 𝑅𝑅𝑀𝑀 is the thickness of the membrane. Then for

separation or purification processes, the rejection of the species i is given by:

𝑅𝑅𝑖𝑖 = �1−𝑓𝑓𝑃𝑃𝑓𝑓𝐹𝐹� × 100

Where 𝑓𝑓𝑃𝑃 is the concentration of the permeate and 𝑓𝑓𝐹𝐹 is the concentration of the feed.24

Membrane Application: Organic Solvent Nanofiltration

Organic solvent nanofiltration (OSN) membranes are pressure driven and use a size exclusion

approach to retain particle sizes of solutes from 50 to 2000 gmol-1 in an organic medium. The stability in

solvent, selectivity based on controlled molecular weight cut-off, and permanence of solvent are the most

important properties for performance and, therefore, main focus of research in OSN membranes.25

To form OSN membranes, the most commonly used materials are polyacrylonitrile (PAN),

polyvinylidene fluoride (PDVF), polyimide (PI), polybenzimidazole (PBI), poly(ether ether ketone)

(PEEK), polyethersulfone (PES), and polydimethylsiloxane (PDMS), and polyamides (PA).26 These

polymers are solvent resistant and do not swell into solvent solutions. However, a soluble polymer

solution for membrane fabrication often uses large consumption of aggressive and often hazardous

14 solvents such as NMP, DMAC, DMF, and H2SO4. Moreover, a common way to improve polymer solvent

resistance is crosslinking. For example, OSN membranes are fabricated through an interfacial

polymerization and crosslinking process onto an ultrafiltration membrane. The process forms a highly

selective separation layer and converts the ultrafiltration into a nanofiltration membrane. However, this

process uses a large amount of solvent and crosslinking chemicals; ultimately increasing the cost and the

environmental burden in fabrication.27

Figure 5 Strategy to develop greener membranes through the principles of green chemistry25

Sustainability Assessment of OSN Membranes

The limiting factor in the application of OSN membranes is the development of a membrane that

is both stable and scalable. Research on this topic focuses on the development of novel materials,

improved membrane modules, and innovative systems.12 Meanwhile, researchers balance the scalability

and stability of OSN membranes with the sustainability of fabrication and processes, economic

competitiveness compared to downstream technology, and selectivity and productivity of solvent

recovery.25 This is achieved by using greener solvents, low toxicity materials, lower number of fabrication

steps, room temperature production, and renewable or degradable materials as shown in Figure 5.25 In

15 addition, as the advancements on the permeance of OSN membranes plateaus, more important work on

non-deal membrane module effects such as concentration polarization and pressure drop, need to be

addressed to enable bulk liquid separations in industrial settings.12 Overall, OSN membranes can have a

much lower CO2 footprint than distillation, prompting the continued research of this field. For example as

depicted in Figure 6, the energy consumption to concentrate 1 m3 of a dilute solution in methanol from

membrane filtration decreases by a factor of ten compared to distillation. 25

Figure 6 Energy consumption to concentrate 1 m3 of a dilute solution in methanol using (a) distillation and (b) membrane25

Membrane Application: Desalination by Nanofiltration

Desalination is a method used for water treatment and purification to solve the water scarcity

problem. Nanofiltration desalination is membrane separation technology that uses an applied pressure

across a semi-permeable membrane for water treatment. There is a need for faster permeance and higher

salt rejection for industrial applications of desalination membranes. One potential drawbacks of this

technology are concentration polarization of the membrane separation process and can lead to membrane

fouling. The sustainability focus of desalination membranes is aimed at reducing the energy costs and

16 increasing the water recovery. In addition, sustainable fabrication of the desalination membrane is also

important.28

Kevlar Aramid Nanofibrous Membranes

Kevlar aramid nanofibers (KANFs) are an emerging material for the fabrication of membranes

with excellent intrinsic physicochemical properties. KANFs are a class of one-dimensional organic

nanomaterials typically obtained from the dissolution of Kevlar fabric. The characteristics of this material

are high solvent resistance, high strength material, making it ideal for the synthesis of solvent resistance

membranes. This thesis is interested in adapting Kevlar membrane fabrication into a more-green route

and gain better control over the structure, and membranes of this nature were also reviewed by Y. Zhao,

Xi Li, et al.29

Structure and Synthesis of KANFs

Kevlar is the commercial name for polyparaphenylene terephthalamide (PPTA) and is a class of

synthetic polymers that form para-crystalline fibers when spun from crystalline dopes. PPTA is used for

high performance applications due to its high strength to weight ratio and gained notoriety through its

application in ballistic protective fabrics such as bulletproof vests and as a reinforcement for aerospace

components.30 This material is produced by the reaction of terephthaloyl chloride and p-

phenylenediamine in a solvent mixture of hexamethylphosphoramide and N-methylpyrroliodone to obtain

a fiber form.

Compared to traditional polymers, PPTA has a highly ordered, asymmetric chemical structure of

long molecular chains of alternating benzene rings and aramid bonds; strengthened by strong

intermolecular forces such as hydrogen bonding, π -π stacking bonds, and van der Waal forces.31 When

17 fabricated into a membrane, KANFs form strong interactions between nanofibers and matrices resulting

in high mechanical strength. KANFs differ from other nanofibers with their super intrinsic

physiochemical properties due to their ordered and asymmetric alternating nanostructure of molecular

chains and ability to hydrogen bond.29

New research on the dissolution of Kevlar (PPTA) fabric utilizes a green approach to obtain the

nanoscale version of aramid nanofibers (KANFs). This approach to dissolve Kevlar (PPTA) uses

DMSO/KOH at 70 to 90°C instead of corrosive H2SO4 in the preparation of a dope Kevlar nanofibrous

solution.27 Former methods to obtain KANFs were limited in efficiency, scalability, and controllability

due to the caustic nature of H2SO4. 32 Comparatively, the DMSO/ KOH solution breaks down PPTA in a

facile and safer manner, breaking the strong interchain bonds between fibers and deprotonation of amide

groups to form KANFs.31 In this method, the short PPTA polymer chains or nanofibers were dispersed

into the solvent with diameter of 20-30 nm, and increased the viscosity of the solution. The concentration

of KANFs in solution is adjustable from 1.0 to 6.0 wt%.The resulting KANFs membranes from phase

inversion have a large specific surface area and strong intermolecular forces due to the increase number of

functional groups such as COOH and NH2. The process for PPTA synthesis, homogenization of PPTA

into KANF solution with DMSO/KOH, structural transformation of PPTA into KANFs, and splitting of

PPTA into KANFs is shown in Figure 7.29

18

Figure 7 a) Synthesis of aramid monomer (PPTA) from p-phenylene and diamineterephthaloyl chloride; (b) Homogenization of Kevlar into homogeneous KANF solution; c) Structural transformation of macroscopic aramid fibers

into nanofibers; Dissolution of Kevlar with DSMO/water with KOH catalyst system (d) Splitting of PPTA threads into nanofibers to form KANF solution29

Key Properties

One of the main advantages of KANFs are their tunable structure that enable fabrication for

practically any application, and dense or porous membranes are attainable through a variety of techniques

that adjust the structure of the nanofibers. Furthermore, KANFs benefit from a combination of useful

properties including electrical conductivity, hydrophilicity or hydrophobicity, flexibility, mechanical

robustness, physical and chemical stability, and resistance to solvents.29

Tunable Structure

KANFs have a highly tunable structure of single PPTA polymer chains and form a dense

membrane structure with the regeneration of hydrogen bonds through a simple phase inversion and drying

process. Pore size of the resulting membranes is highly dependent on the geometry and connectivity of

19 interactions between molecules. The stronger interactions between molecules increase the strength of the

KANF membrane, but negatively decrease the flux limit. Therefore, a variety of techniques such as

physical dispersion, blending, hybridization, interpenetrating polymer networks, and MOF and COF

networks were developed to tailor the structure of KANFs to yield membranes with high separation

performance. Additionally, the characteristic NH2 and COOH groups of KANFs can be used to react with

various monomer or polymers through substitution reactions or amide condensation reactions to tune the

structure for numerous applications.29 For this thesis, the KANFs were used as dissolved without any

further modification.

Physico-Chemical Stability

The physical and chemical stability of KANFs are excellent due to their chemical structure. The

strong amide groups and hydrogen bonds between KANF molecules yield outstanding mechanical

properties and thermostability. Likewise, these intermolecular forces yield high chemical stability and

resistance to solvents. KANFs can also be prepared with physically or chemically stable polymers such as

methoxypolyethylene glycol to form uniform and stable dispersions.33

Hydrophobicity/ Hydrophilicity

KANFs can exhibit hydrophilic or hydrophobic behavior depending on chemical reactions with

other compounds on the amide bonds. For organic solvent nanofiltration membranes, hydrophobicity is

important to avoid scaling and is achieved through KANF mixtures with polyvinyl fluoride (PVDF) or

poly(dimethylsiloxane) (PDMS). 34

20 Selectivity

The size seizing effect between target molecules and ions is the most effective way for selective

separation and is crucial for resource recycling and for zero emissions targets in industry. The structure of

KANF based membranes relies on the strong and dense interactions between particles and can be tailored

for specific pore sizes and pore size distributions for selective separation of molecules or ions. Moreover,

electrostatic repulsion is another method to increase selective separation with the addition of charged

functional groups on the membrane surface.29

Design of KANF Fabricated Membranes

There are several methods for the design of KANF based membranes for precise and rapid

separations. Following the dissolution of PPTA into KANFs, additives may be added to the casting

solution before a phase inversion process to transform KANFs into KANF membranes. In the phase

inversion process, the casting solution is spread out buy a casting knife onto a glass plate in an even and

uniform manner. The glass plate is submerged into a water bath, and though an immersion phase

inversion process, the organic solvent in the membrane is rapidly replaced with water to precipitate a

dense asymmetric KANF hydrogel membrane (Figure 8). The membrane has a gel-like feel and is

removed from the water bath for drying.27 Additionally, various techniques exist such as blending,

chemical reactions, network interpenetrating, and interfacial polymerization. These techniques are

employed to adapt and modify the membrane for specific applications by selecting specific or

functionalized materials and integrating them into the membrane.29

21

Figure 8 Comparison of KANF Hydrogel to Conventional (PSU) Polymeric Membrane1

Blending is a technique that disperses compatible nanoparticles, nanosheets, nanowires, or

organic polymers and monomers into the KANF solutions. These additives can increase the flux or

selectivity of membranes and functionalize for certain applications.35–37 Chemical reactions utilize amide

hydrolysis and condensation to functionalize COOH and NH2 groups on KANFs with charged monomers

for electrochemical membrane applications. Likewise, through substitution reactions on the benzene rings

and aramid groups, the hydrophilicity or hydrophobicity of KANF based membranes is modified.38

Chemical reactions may also be initiated post phase inversion for secondary processing functionalization.

Composite KANF membranes with interpenetrating networks are formed through the addition of small

crystals, molecules, or polymers into the hydrogel. This technique is typically used for functionalization

of KANF membranes in electrolyte and fuel cells.39 Interfacial polymerization (IP) forms a thin active

layer onto a porous hydrogel support membrane, and typically uses TMC, and MPD. The latter part of

this thesis adapts KANFs hydrogels as support membranes from IP for desalination.

22 Applications of KANF Membranes

The tunable structures and adjustable composition of KANF membranes endows specific pore

size for a wide range of applications including water treatment, organic solvent nanofiltration, separation

of ions, battery separators, and proton exchange membranes.29

23

Chapter 3

Engineering Considerations

Considerations in Engineering and Design

This section evaluates the engineering considerations of this work such as economic issues,

environmental issues, sustainability, manufacturability, ethical issues, health and safety, social and

political implications, and the Code of Hammurabi.

Economic Issues

Several factors needed to be considered for the application of these membranes in industrial

settings such as the cost of materials, the cost of processing, and manufacturing technology.

Cost

To become competitive, KANF OSN and desalination membrane separation processes must be

less energetically, chemically, and operationally intensive than other traditional separation processes and

other membrane separation processes. Membrane separation technology is a continuous process that

consumes less energy and contends with conventional methods such as adsorption, absorption,

evaporation, distillation, crystallization, and chromatography. In my proposed works, the main component

of these membranes is KANFs, and unlike other technical polymers, KANFs are a lower cost material

because they are easily produced from strands of Kevlar fiber and do not need crosslinking agents or

24 additives to create 3D networks. Furthermore, the advantageous economic interest of KANF membranes

is linked to their facile fabrication. In these works, KANF membranes are processed with less solvent

intensive processes. Using less solvent reduces the costs in raw materials, additional processing steps, and

post processing steps. Furthermore, these KANF OSN and desalination membranes can be used in

existing membrane separation process technologies or adapted into a hybrid process with conventional

techniques.

There are also some hidden costs to consider such as energy costs, marketability, intellectual

property, life cycle cost, and local, state, or federal interactions. The product must yield competitive

separation performances in life cycle assessments to be implemented into industrial applications.

Likewise, the intellectual property of the membranes should be protected by patents before large scale

applications of KANF membranes at companies like Dow, Dupont, and BASF. Significant push to

implement these membranes in membranes modules at the state or private sectors must also be funded.

Start-up grants are an option to find investors.

Manufacturability and Operations

The manufacturability and implementation of these novel membranes is achievable within several

years. The deliverable products from this study has promise for economic and environmentally friendly

scalability. For example, large sheets of KANF membranes were synthesized via phase inversion as a

proof of concept.27 Furthermore, the two proposed methods for membrane fabrication can be adapted to

existing membrane fabrication module infrastructures such as the support membrane and TFC membrane

manufacturing systems. Figure 9 and 10 show schematics of a coating line membrane fabrication module

and a TFC reverse osmosis membrane fabrication module. In the support membrane module, two extra

steps of vacuum filtration and heat treatment with the novel casting solution can be added to convert the

support membrane into a nanofiltration membrane. Likewise, the TFC membrane manufacturing system

25 can be adapted with the new KANF hydrogel support. By using existing membrane manufacturing

infrastructure, the cost of manufacturing decreases. In addition, the standard module design for NF

membranes is spiral wound geometry. This module has the benefit of being compact, easy to operate, and

lower cost than other modules.40

Figure 9 Diagram of coating line for fabrication of support membrane41

Figure 10 Diagram of reaction line for fabrication of thin-film composite RO membrane41

Overall, these proposed membranes can be adapted in a profitable manner. Specifically, OSN

membranes have the potential for commercialization and have been demonstrated at a membrane unit at

ExxonMobil’s Beaumont refinery. At this refinery, approximately 11,500 m3 of lubrication oil was

processed daily and helped debottleneck existing dewaxing units resulting in reductions of 20% process

energy intensity, 20,000 tons a year in greenhouse gas emission, and four million gallons of water usage

daily, and 125 tons in violate compound emissions annually.42 The materials, fabrication of the membrane

product, or implementation of the process within different chemical separation save energy and bring

down the cost of manufacturing resulting in a higher profit margin. These membranes can be fabricated

domestically or offshore and sent to manufacturing or community locations for application.

26 Environmental Issues and Sustainability

This project is partly based in increasing the sustainability of OSN membranes for organic solvent

recovery and nanofiltration desalination membranes to decrease environmental issues and provide access

to clean water. The main material of this project is KANFs, sourced from Kevlar string from Dupont,

USA. Kevlar fiber is 100% recyclable, and can be respun into a new yarn, used as a padding for cushions

or clothing articles, pulped. However, Kevlar in its dissolved nanofiber form or as a membrane cannot be

recycled without further processing because other polymer materials are used and crosslinked networks

cannot be broken down.43 The materials and products used to fabricate these membranes do not

deteriorate for many years. Therefore, it is important to make membranes as durable as possible to

increase lifespan and avoid pollution of deteriorated membranes.

Likewise, solvent is consumed in the Kevlar dissolution and fabrication of membranes.

Therefore, leftover casting solution and solvent waste needs to be separated before disposal, and dyes

solutions for testing also need to be separated. It is important to minimize the number of materials mixed

because this post treatment separation process increases the energy consumption of the membrane

fabrication and decreases the sustainability. However, solvents that are less environmentally hazardous

are utilized such as dimethyl sulfoxide instead of the caustic sulfuric acid. In terms of chemical, thermal,

noise, particulate pollution, there are no hazardous chemical byproducts from membrane separation.

However, retentate from the membrane process needs to be recycled or disposed in a responsible manner

to avoid potential environmental issues. For example, desalination retentate disposed into the ocean

increases the salinity of the local aquatic systems resulting in significant consequences on marine life. 44

In the upcoming years, OSN and desalination membranes are increasing in public interest for

their green fabrication and separation activity. These membranes aim to reduce the population of organic

matter into water ways. The long-term goal to decrease pollution of water sources to address the grand

challenge of providing clean water globally. These membranes will most likely be used in developed

27 countries, but hopefully become more accessible to developing countries that are most at risk. As the

usage of solvent continues to increase in chemical operations, there will always be a need for sustainable

separation technology at an affordable cost. Likewise, as the global population continues to skyrocket, the

demand for water as a resources becomes more critical.

Ethical, Social, and Political Issues

Locally, based on the success of the resulting experiments, these novel membranes can be

implemented into local chemical industries to improve solvent separation and recovery and decrease

solvent pollution. Likewise, they may also be implemented into desalination plants to improve the overall

operations and production of clean water. Access to clean water has huge social implications for

communities, specifically women and girls tasked with providing clean water for their families. Obtaining

clean water from a well sourced miles away is a time consuming and often dangerous daily journey for

young girls. When communities gain access to clean water, girls can focus on education leading to huge

social change.45 Once established, these membranes can be implemented globally into different chemical

and desalination separation industries. These membranes can be effective in developed and developing

countries for organic solvent nanofiltration or desalination. However, the fabrication of these membranes

must be less environmentally detrimental than their function can negate.

Implementing these membranes into existing desalination or membrane modules should not be

difficult on a political level due to the pre-existing technology and no action of the government to

subsidize projects. However, implementation of entire desalination plants could prove more difficult.

Politically, tangible information on water costs are uncertain for communities and policy makers due to

diverse intervening economic and environmental parameters. This makes it difficult to install desalination

plants to regions of critical need. For example, there are several factors to consider when installing a

desalination plant such as technical criteria for site selection, costs of operation, time schedule, and

28 environmental influences and impacts. Sites for desalination plants are chosen based on the potable water

demand, seawater intakes and outfalls, subsoil conditions, fresh water and power availability,

accessibility, seashore line protection, local labor and infrastructure, and various regulations.46 The most

economical way for separation operations is continuous based on energy consumption and separation

efficiency, and return flows must be safely disposed of or recycled. For low income areas, the high prices

installing a desalination need to be subsidized and compared against the costs of importing fresh water to

the area.

In consideration, there are several steps to execute application of membrane separation

desalination plants to regions of critical need including information gathering, analysis, reporting, and

decision making. In a review of countries with critical water shortages, regions in China, India, Republic

of Korea, Russia, Algeria, Egypt, and Indonesia were identified, and each had unique problems.47 For

example, in China, there are 104 cities with 200 million people in northern and coastal areas that have a

critical water shortage. Freshwater sources such as the Pearl River Delta and Yangtze river are polluted

with high concentrations of Cadmium and the low-income region requires a state subsidy for separation

projects. Even in cities like Shanghai, water supply stations can charge up to US $25 per cubic meter of

water. For political consideration, it costs less money to develop water sources in these coastal cities than

build infrastructure to transport it. Likewise, in India, there is 4000 km3 of rain annually, however it is not

evenly distributed with chronic water shortages in Tamil Nadu, Andhra Pradesh, Saurashtra, and western

Rajasthan. Furthermore, ¾ of the available rainwater is lost to the sea and leaves only ¼ to be stored as

ground water. Conventional water supplies such as dams, lakes, canals, piped water need large capital

(US $1-2 x109) for water supplies of 9000-22,500 m3/d. In addition, these conventional water supplies are

contested by civilians as lands are submerged, populations uprooted, and forests destroyed. Finally,

regions in Indonesia deal with critically polluted water that cannot be used without extensive filtration.

Government funding may be somewhat challenging to secure due to corruption or opposing viewpoints,

and independent investors need to find a profitable return on clean water access.

29 It is the hope of this research projects and other research projects in this field to improve the

desalination of membrane modules to provide access to water to these critical regions. In addition, the

implementation of OSN membranes into chemical plants may improve the recovery and separation of

hazardous chemicals from waste streams and decrease the detrimental consequences of environmental

pollution and polluted water systems.

Health and Safety

Composite materials synthesized with Kevlar aramid nanofibers have potential health and safety

hazards during testing, manufacturing, and processing that may significantly affect researchers and

industrial workers. As shipped, Kevlar aramid nanofibers are chemically inert, nonhazardous in the dry

fabric form or after curing in a membrane matrix, and nonbiodegradable, but nontoxic to aquatic life.

However, machining or mechanically altering the Kevlar fibers may release airborne respirable fibrils and

dust that upon inhalation can become trapped in the deep lung and cause tissue damage.48,49 To minimize

risk of inhalation, Occupational Safety and Health Administration (OSHA) mandates the use of

respiratory protective masks with a diameter less than 3 micron in size; the size and diameter of Kevlar

aramid nanofibers is typically 8 micron.49 In this experiment, the Kevlar aramid nanofibers are dissolved

into solvent, and their dispersion and electrochemical interactions with solvent decrease the chance of

becoming airborne. Furthermore, the Kevlar aramid nanofibers must be stored properly to avoid fire and

becoming electrostatically charged. If this material catches on fire, it may release toxic or irritating gas,

and build-up of electrostatic charge may ignite nearby vapors.

Some of the chemicals and solvents used in membrane fabrication are highly or extremely

flammable. When working with membrane casting resin, precautions must be made to avoid inhalation

and skin/eye contact with the chemicals and chemical fumes. The adverse possible effects are lung

damage, fertility damage, exposure to carcinogens, and drowsiness or dizziness. To minimize risk of

30 exposure, OSHA directs the use a fume hood and proper personal protection wear. The fume hood should

be mechanically checked often to ensure proper ventilation of chemicals; glassware should be checked for

cracks; an invention kit should be on standby. At minimum, the personal protective wear should include a

lab coat, safety glasses, and cryogenic gloves when handling these solvents. Finally, chemical waste

should be selectively separated for proper and safe disposal.

Overall, the safety and health in this work and potential industrial scaling is achievable and

maintainable with workplace responsibility and engineering controls. The use of solvents and machining

of Kevlar should be minimized to reduce risk of pollution of byproducts and airborne dispersion of

nanofibers.

Code of Hammurabi

The Code of Hammurabi is effectively risk management for engineering and is an important step

to ensure to proposed technologies or projects will not negatively impact users or the community by

holding the professional accountable. Much of this assessment has already been mentioned in health and

safety. In terms of this project, membrane separation technology has facile and safe operating conditions

for users with low temperatures, relatively low pressure, and without the use of harsh chemicals such as

hydrofluoric acid.26 These novel membranes do not pose any risk of injury or death in their final inert

fabricated form. The synthesis of these membranes does use some medium risk chemicals and should be

handled with care and proper personal protection wear to avoid injury.49 Furthermore, these membranes

are rigorously tested to ensure highest separation efficiency for the greatest reduction in environmental

pollution. The retentate and permeate solution may be tested periodically to ensure the performance of the

membrane does not decrease during operation and release pollution. Overall, the risks in fabrication,

operation, and process can be effectively minimized to pose little or no danger to operators or users.

31

Chapter 4

Experimental Procedures

Materials

All materials used in the pressure vacuum filtration with heat treatment and hydrogel assisted

interfacial polymerization methods are detailed in this section in Table 1. Before use, Bulk Kevlar 69 was

dried in the oven for 12 h at 60 °C. Deionized water was used in these experiments. Solutes for membrane

characterization are listed in a separate table, Table 1. BSA was used as the solute for the OSN KANF

pressure vacuum filtration with heat treatment method. Salts and dyes were used as the solute for the

KANF hydrogel assisted interfacial polymerization TFC nanofiltration membrane for desalination of

water. The salts and dyes were tested separately with 1.0g/L of feed concentration.

Table 1 List of Materials for Experiments

Chemicals Chemical Formula Purity (%) Supplier

Bulk Kevlar 69 -(C14H10N2O2)- - Thread Exchange (USA)

Potassium hydroxide KOH 85 Sigma‐Aldrich BVBA

Dimethyl sulfoxide (DMSO) C2H6OS

99.5 Sigma‐Aldrich BVBA

Hexane C6H12 99 Sigma‐Aldrich BVBA

Ethanol C2H6O 99 Sigma-Aldrich

Methanol

CH3OH 99.9 Sigma-Aldrich

32 N-methyl-2-pyrrolidone

(NMP)

C5H9NO 99 Sigma-Aldrich

Polytetrafluoroethylene (PTFE) Microfiltration Membrane (0.2-0.8 μm Pore Size)

(C2F4)n Sigma-Aldrich

Alumina Microfiltration Membrane (0.2 μm Pore Size)

Al2O3 Sigma-Aldrich

Trimesoyl chloride (TMC); 1,3,5-Benzenetricarbonyl trichloride

C6H3(COCl)3 98 Sigma-Aldrich

Piperazine (PIP) C4H10N2 99 Sigma-Aldrich

Table 2 List of Solutes for Membrane Characterization

Solute Solute Formula Purity Supplier Bovine serum albumin (BSA)

Globular proteins 99 Sigma-Aldrich

Sodium Chloride NaCl 99 Sigma-Aldrich Sodium Sulfate Na2SO4 99 Sigma-Aldrich Magnesium Chloride

MgCl2 99 Sigma-Aldrich

Magnesium Sulfate MgSO4 99 Sigma-Aldrich

Table 3 Dyes Used for Rejection Tests

Dyes Molecular Weight (g

mol-1)

Structure Supplier

Congo Red 697

50

Sigma-Aldrich

33 Direct Red 80 1373

51

Sigma-Aldrich

Direct Red 23 814

52

Sigma-Aldrich

Reactive Blue 2 774

53

Sigma-Aldrich

Methods

Only methods relevant to all projects are listed in this section. The preparation of Kevlar aramid

nanofibers was critical for each project outlined in this thesis. Details about membrane fabrication

particular to each experiment is found in latter sections.

Preparation of KANF and DMSO Solution

The preparation Kevlar aramid nanofibers was adapted from Kotov’s method by Van der

Bruggen’s group.1 In this method, 2.0g of bulk Kevlar 69 was dissolved into 100 ml DMSO with 2.0g

KOH to obtain a 2 wt% Kevlar nanofiber solution. The solution was stirred for 5-7 days h on an oil bath

at 70 °C with a reflux condenser until it became dark red and viscous as shown in Figure 11.

34

Figure 11 Dissolution of PPTA into red and viscous KANF Solution1

Membrane Characterization

The characterization of these membranes used permeation and rejection, stability, and SEM to

determine the performance of the vacuum filtration TFC Kevlar membrane and TFC desalination

membrane.

Filtration Setup

The filtration setup for testing membrane permeance and flux included a dead-end filtration cell

(Figure 12) and high-pressure crossflow cell (Figure 13). The stainless-steel dead-end filtration cell was

composed of a 3-way valve on top of filtration cell, nitrogen gas supply (line, 50 bars max), and a

pressure regulator. In this system, the flow of water is perpendicular to the surface of the membrane and is

pushed through the surface by pressure. The water as the permeate passes through the membrane out of

the cell, but the retentate remains in the filtration cell.

35

Figure 12 Dead end filtration equipment including a) filtration cell; b) 3-way valve; c) pressure regulator54

Likewise, the high-pressure crossflow cell equipment was purchased from Evonik. In this system,

the feed solution circulates across the membrane surface in the filtration cell by a gear pump. The gear

pump builds up high gas pressure and forces the system to conduct separation through the membrane, and

the crossflow circulation of feed solution prevents the accumulation of matter on the membrane surface.

Figure 13 Picture of Crossflow Filtration Unit Set Up54

Membrane Permeation

Water permeation was measured by the dead-end apparatus (HP 4750) with effective area of 13.2

cm2. Likewise, permeation was also measured by the crossflow equipment with an effective area of 22.9

cm2. For both systems, the operating pressure is 4 bar and 25°C, and the feed solution was stirred at 600

rpm to minimize concentration polarization. The flux of the system is defined by:

36

𝐽𝐽 =𝑉𝑉

𝐴𝐴 ∗ ∆𝑡𝑡

Where J is the flux through the membrane, V is the volume of permeate through the membrane (L) , A is

the effective area of the membrane (m2), and ∆t is the change in time (h). From the flux of the membrane,

the permeation can be found and is defined as:

𝑃𝑃 =𝐽𝐽∆𝑃𝑃

Where P (L/m2 h bar) is permeation, J is the flux of the membrane (L h-1), and ∆𝑃𝑃 is the change in

pressure across the membrane surface (bar).

Membrane Selectivity and Rejection of Salts or Dyes

Selectivity and rejection were determined through the concentration of the permeate and the

retentate. Dyes as solutes for rejection tests with a range of molecular weights from (667 g/mol to 774

g/mol). BSA was used as a solvent to test for ultrafiltration range and has a molecular weight of 66430.3

g/mol. Salts were used as the solutes for the desalination membrane. Dye rejections and salt rejection

calculations between the concentration of the initial feed and final permeate, and is described by:

𝑅𝑅(%) = �1−𝐶𝐶𝑝𝑝𝐶𝐶𝑓𝑓� ∗ 100

Where R is for rejection (%), Cp is for concentration of the permeate (mg/ml), and Cf is concentration of

the feed (mg/ml).

Stability

To determine long time stability for the desalination membrane, the permeation of the Na2SO4

was measured after continuous filtration for 6 h.

37 Membrane Surface Characterization

Surface characterization such as scanning electron microscopy (SEM), atomic force microscopy

(AFM), and water contact angle were used to observe the surface morphology and properties of the

membrane. The thickness of the membrane surface was observed through SEM cross sections. The

hydrophilicity and permeation of the membrane selective layer was related to the surface roughness and

water contact angle measurements.

SEM Measurements

The surface and cross section morphology was visualized by scanning election microscopy

(SEM) at 10 kV. The SEM used was the Phillips Scanning Electron Microscope XL30 FEG (Eindhoven,

the Netherlands). In addition, to observe the macrostructure of the Kevlar hydrogel membrane samples

during thermal treatment, supercritical CO2 drying was used. The procedure for CO2 critical super-drying

is to first immerse the membrane in isopropanol for 2 h to remove the water, remove the membranes and

re-immerse them for 2 hours more. The membrane is re-immersed 3 times to slowly replace the water

with isopropanol. Then, the membranes are dried with the supercritical point dryer for 1 hr.

TEM Measurements

The surface and cross section morphology was visualized using TEM. The JEOL-1230 field

emission transmission electron microscopy was used for TEM images and samples were well dispersed

on a copper-supported carbon film.

38 Atomic Force Microscopy (AFM)

The surface roughness was measured using the Dimension 3100 Atomic Force Microscope

(Bruker, USA) under ambient conditions. The scanning area of 1 x1 μm2 and 5 x5 μm2 was used.

Supercritical CO2 drying was used tapping mode by NCSHR probes (NanoAndMore GmbH, Germany).

This tapping mode was used with a silicon tip that had a radius of < 7nm and a spring constant 40-50Nm-

1. The final values were averaged values from 3 spots, and reported the root square mean (Rrms), average

roughness (Ra), and maximum vertical distance (Rm) between highest and lowest point.

Contact Angle

Water contact angles were measured using a 2 μl deionized (DI) water droplet on membrane

surface, and the OCA 20 Contact angle goniometer (Data physics Instruments, Germany). An average of

5 measurements were average to find the final calculation.

Water content swelling rate of KANF hydrogel membranes

The water content and water swelling ratio was determined using the mass of the membrane in

the wet state and the dry state. The water content and swelling rate can be described by:

𝑊𝑊𝑎𝑎𝑡𝑡𝑓𝑓𝑑𝑑 𝐶𝐶𝑓𝑓𝑅𝑅𝑡𝑡𝑓𝑓𝑅𝑅𝑡𝑡 = 𝑚𝑚𝑤𝑤𝑤𝑤𝑤𝑤 − 𝑚𝑚𝑑𝑑𝑑𝑑𝑑𝑑

𝑚𝑚𝑤𝑤𝑤𝑤𝑤𝑤

𝑆𝑆𝑆𝑆𝑓𝑓𝑅𝑅𝑅𝑅𝑑𝑑𝑅𝑅𝑑𝑑 𝑅𝑅𝑎𝑎𝑡𝑡𝑑𝑑𝑓𝑓 = 𝑚𝑚𝑤𝑤𝑤𝑤𝑤𝑤 − 𝑚𝑚𝑑𝑑𝑑𝑑𝑑𝑑

𝑚𝑚𝑑𝑑𝑑𝑑𝑑𝑑

Where mass of membrane in wet state is mwet and dry state is mdry. The wet membrane was weighed after

water droplets were removed from the surface with filter paper. Next, the wet membrane was thermally

treated in an air-circulating oven at 60℃ for 24 h, and then the dry membrane was weighed.

39 Other Membrane Characterizations

Other characterizations that were utilized in this experiment, but not personally conducted by my

person, included X-ray photoelectron spectroscopy (XPS), surface charge, and mechanical testing. XPS

was applied to survey the chemical composition of the membrane surface by the AXIS Supra X-ray

photoelectron spectrometer (Kratos Analytical, UK) with Al Kα as the radiation source, and analyzed

with CasaXPS software. Surface charge of the membranes were found using the electro-kinetic analyzer

(SurPASS 3, Anton Parr, Austria) with a 1mM NaCl solution as an electrolyte solution.

40

Chapter 5

OSN KANF Pressure Vacuum Filtration with Heat Treatment Membrane Results and Discussion

Due to unforeseen circumstances such as the worldwide global pandemic, restricted access to

laboratories, and personal reasons, the results of this experiment are limited and are preliminary in their

exploration of this method. The goal of this project was a greener TFC membrane synthesized through a

vacuum assisted filtration and heat treatment method of KANFs onto a microporous support membrane.

Membrane Design Strategy

As previously mentioned, current OSN membrane design to improve solvent resistance utilizes

harsh and violate solvents such as H2SO4, NMP, DMAC, and DMF in the fabrication process of dope

solution for crosslinkable polymers such as polyimide (PI), poly(ether ether ketone) (PEEK),

polybenzimidazole (PBI), and poly(arylene sulfide sulfone) PASS. Another method to improve solvent

resistance is to use crosslinking agents and chemicals to create a selective separation layer on a

microporous support via interfacial polymerization. The use of harsh solvents and additional crosslinking

agents increases fabrication cost, and increases the negative environmental impact; so recently, there has

been a push to use “green” solvents and decrease solvent volume in fabrication.25

KANFS are an ideal material for the fabrication of OSN membranes with the novel method of

PPTA dissolution by Kotov’s method, latter adapted by Van der Bruggen’s group.27 In a recent study,

Yuan developed Kevlar nanofibrous membranes via the regeneration of hydrogen bonds for OSN

membranes. A DMSO/KOH solution was used to dissolve the PPTA into a KANF dope, and the hydrogel

ultrafiltration membranes were obtained from the dope solution via phase inversion. Then, a thermal

41 treatment in the oven turned the ultrafiltration membranes into nanofiltration membranes through the

elimination of water and the regeneration of hydrogen bonds without the using of harsh solvents or

crosslinking agents. However, this method was limited in its control over the thickness of the thin

selective layer; the concentration of KANFs in dope solution and knife gap thickness was adjusted to

tailor the selective separation layer, but the lowest thickness was 80nm. Compared to other TFC

membranes with a separation as separation layers as thin as 10 nm, another method to reduce the selective

layer thickness of the KANF membrane was sought to further increase the permanence and gain more

control over the structure.

Vacuum assisted filtration over a microporous support membrane is technique that can be used to

control the thickness of the resultant membrane by altering the amount of dope solution for filtration.

Research on vacuum assisted filtration for fabrication of KANF membranes has been explored for several

applications. For example, Wang et al. prepared a KANF and silica nanoparticles (POSS) hybrid organic

and inorganic nanocomposite membranes through a vacuum filtration method.55 POSS nanoparticles and

ANFS were vacuum filtrated over nylon membranes, and the incorporation of POSS acted as the

crosslinker yielded membranes with a selective layer of controllable thickness for high tensile strength

and thermal applications. Likewise, Li et al. synthesized a KANF and methoxypolyethylene glycol

(mPEG) membrane through a vacuum assisted filtration method to yield uniform thickness and smooth

surfaces for applications as a battery separator.56 The mPEG was used to increase the degree of

crosslinking between the KANFs via hydrogen bonding. Lv et al. used a vacuum assisted filtration and

hydrothermal method to create hybrid silk and KANF nanofiltration membranes with adjustable thickness

of the selective layer for potential applications as a pressure driven membrane and flexible substrate for

electronic devices.57

Therefore, the proposed structure for membrane fabrication utilizes a commercial microfiltration

membrane with vacuum assisted filtration of KANFs and consequent heat treatment to form a selective

organic solvent nanofiltration membrane. Through the initial solution casting for phase inversion after

42 deposition via vacuum filtration, the KANFs should form an ultrafiltration layer and once additional

water is removed, form a nanofiltration layer on top of a microporous support. Importantly, this selective

layer cannot swell in solvent and maintains constant reject as the OH bonds are reformed between

molecules. Overall, this method should reduce the amount of solvent used in membrane fabrication by

only using as much solvent necessary to evenly disperse the KANFs and gain better control over the

selective separation layer.

Membrane Fabrication Methods

To fabricate this membrane, KANFs were deposited into a solvent solution and dispersed over

PTFE and Alumina microfiltration membranes via vacuum assisted filtration. Initial dope solution of

KANFs dissolved by Van der Bruggen’s method was 2 wt%.

Thickness Calculation

The vacuum filtration method was used to control the thickness of the separation layer. A

calculation of Kevlar nanofibers in the solvent solution was used to gain the desired thickness, and was

found using density, surface area of the membrane, and the desired thickness of the membrane. The

diameter of the microporous membrane was 7 cm, and the total surface area was:

𝑆𝑆𝐴𝐴 =14𝜋𝜋𝐷𝐷2 =

14𝜋𝜋(72) = 38.5 𝑓𝑓𝑚𝑚2

Where SA is surface area (cm2), and D is the diameter of the support membrane(cm).

Then, to find the mass of KANFs needed to form a selective layer of a desired thickness, the

volume of a cylinder and density of the KANFs were used.

43

𝑀𝑀𝑎𝑎𝑀𝑀𝑀𝑀 = 𝜌𝜌𝐾𝐾𝐾𝐾𝐾𝐾𝐹𝐹𝐾𝐾 ∗ 𝑡𝑡 ∗ 𝑆𝑆𝐴𝐴 = 1.4 �𝑑𝑑𝑓𝑓𝑚𝑚2� ∗ 100 𝑅𝑅𝑚𝑚 ∗ �

1 𝑓𝑓𝑚𝑚10−7𝑅𝑅𝑚𝑚

� ∗ 38.5 𝑓𝑓𝑚𝑚2 ≈ 0.6 𝑚𝑚𝑑𝑑

Where ρ is the density of KANFs and t is the thickness of the membrane. For example, about 0.60 mg of

KANFs was needed for 100nm thick membrane. The dope solution of KANFs was 2 wt% or 20 mg/g, so

2 to 3 grams of dope solution is necessary to get the desired KANF loading and thickness of the selective

layer. To decrease the viscosity of the dope solution for dispersion over the microporous support

membrane, 15 g of solvent was added. Initial work synthesized three membranes for 100nm, 200nm, and

300 nm thick layers; the goal set as <80 nm thickness.

Vacuum Assisted Filtration

The amount of KANFs was calculated for desired thickness and dispersed into deionized water or

DMSO. For KANF and deionized water solution, 50 ml of water was used. Likewise, for KANF and

DMSO solutions, 15 ml of solvent was used. Solutions were stirred for 10 minutes using a stir bar at room

temperature. The color of the dispersant solution was yellow orange in the DMSO and clear in the water.

Figure 14 Lab assembled apparatus for vacuum assisted filtration54

The lab assembled apparatus used for vacuum filtration is like the set-up in Figure 14. The

microfiltration membrane of PTFE with a pore size of 0.2 to 0.8 μm or the alumina with a pore size of 0.2

μm was clamped between the glass vessels. During filtration, the KANF suspension is poured into the

44 top vessel along glass wall to avoid a turbulent mixture of KANFs and uneven dispersion onto the

microporous membrane (Figure 15). The bottom glass vessel is connected to the flask below via a rubber

cork to maintain vacuum pressure, and the secondary neck of the flask is connected to the vacuum source.

The removal of the solvent for phase inversion is driven by gravity and the vacuum pressure.

Figure 15 Schematic for vacuum assisted filtration over a microporous support for KANF membranes

After dispersion, the membrane was placed into the oven thermal treatment at 60℃ for 24 h for

10 minutes to regenerate OH bonds. Alternatively, the membrane was also left out to air-dry overnight to

avoid flaking the selective layer from the microporous support.

Membrane Characterization Results

Permeation, selectivity, and SEM characterization was done for the initial work on this project.

The initial permeance of PTFE was measured as a reference, and the value was 11275 (L/m2hbar).

Consequently, KANF selective layers of 100, 200, and 300 nm thickness were deposited on to the

microporous supports. Both the alumina and the PTFE support and KANF membranes failed to

selectively permeate BSA at any thickness. However, the permeance of the membranes decreased as the

45 thickness increased; for the PTFE support, permeance decreased from around by half from its original

value for a membrane thickness of 100nm. This suggested that there was the formation of a selective layer

onto the support membranes. For alumina support, the permeance and rejection was similar to the PTFE

support. Additionally, the permeance of the KANF membrane with the PTFE support decreases over time

due to compaction.

The data suggests that possibly a nanofiltration layer is selectively formed on top of the

microporous support. However, the presence of defects and flaking of the selective layer from the support

suggest incompatibility between the support and KANF materials decrease the selectivity. Future work to

modify the dispersion of the KANFs with PVOH to create less defective and higher compatibility with

the support membrane is the next step. Furthermore, the permeability decreased as the thickness of the

membrane increased, indicating that the thickness of the membrane is controlled by the calculated amount

of KANF in solution.

46

Figure 16 SEM images of a) Alumina microporous support membrane; b) Alumina and KANF membrane; c) Uncoated regions on alumina support; d) PTFE microfiltration support membrane e) PTFE and KANF membrane

A SEM image of the PTFE and alumina membranes before vacuum filtration were taken. In these

images, the PTFE had a microporous structure with pore sizes up to one nanometer in size. Similarly, the

alumina microstructure had much smaller pore sizes. The pore sizes were also equiaxed and more regular.

The following SEM images were taken at two magnification of the deposited Kevlar layer on top of the

support membranes. On both the alumina and the PTFE support, a KANF membrane layer was identified.

On alumina, the KANF layer was cracked, likely due to poor interactions between the polymer and

ceramic. Also, the KANF did not completely disperse over the alumina, confirming the poor bonding

interactions between the support and selectivity layer. On PTFE, the KANF layer was dense and evenly

dispersed. These SEM images are organized in Figure 16.

47 Chapter 6

Hydrogel Assisted Interfacial Polymerization Results and Discussion

As mentioned, the results of this section are available from this paper1, and additional discussions

are found there. I was responsible for the synthesis of membranes, testing permselectivity and rejection,

water contact angle, water uptake, and surface roughness; I did not do mechanical strength, zeta potential,

or XPS. In addition, a free-standing membrane was synthesized as a comparison against the TFC KANF

hydrogel membrane reported. As I was not responsible for this synthesis, I did not report it, however it

remains a useful comparison for data analysis.

Membrane Design Strategy

Current thin film reactions use two reactive monomers (organic diamines and acyl chlorides) that

polymerize at the interface of two immiscible liquids. Interfacial polymerization adapts this method to a

thin PA layer on top of porous UF membrane.24 However, to make this technology more competitive

against other separation methods, IP membranes need higher efficiency, lower energy consumption, and

higher permeability to process large volumes of wastewater.

There are two methods to increase effective membrane area and boost the permeability of TFC

membranes without sacrificing solute rejection. The first method is to develop TFC membranes with a

rougher PA layer to increase effective surface area and permeation. A rough PA layer is achieved by

controlling the diffusion of anime monomers in interfacial polymerization or adding filler into the surface.

However, some limitations of this method are fillers on support membrane increase the cost and

complexity of fabrication method and decrease the scalability.58 Another limitation is the increased

surface area may lead to membrane fouling on the surface and a decrease in the membrane permeation.

The other method to improve the permeation is to reduce the thickness of PA layer formed

through interfacial polymerization at the aqueous interface.24 To reduce the thickness of a PA layer, an

48 ideal interface of homogenously distributed free water and hexane is used in the diffusion of amine

monomers without the disturbance of a support membrane. This ideal interface yields a theoretical PA

layer of 10 nm, and this thin selective layer shortens the mass transfer resistance leading to higher flux.

The free aqueous -organic interface is an ideal medium for interfacial polymerization, but there are still

several limitations. For example, oil and water do not mix regularly and may disturb the water phase

leading to an unstable reaction interface. Furthermore, it is a sophisticated process to move the thin PA

layer onto the support membrane, and a lack of chemical interactions between PA layer and support

causes the PA layer to detach during crossflow filtration.59

There is interest in using a KANF hydrogel membrane as the free water interface for an ideal

interface to perform IP. Hydrogels are a crosslinked hydrophilic polymeric network that can hold large

amounts of water, making them suitable replacement for the water interface in a free water interface

reaction.60 Also, hydrogels have applications in membrane separations as the support membrane for TFC

membranes.

Overall, the goal of this research to make TFC NF membranes by conducting interfacial

polymerization on bottom surface of nanoporous KANF hydrogel. The water saturated KANF hydrogel is

a substitution for the free water phase in synthesizing free-standing membrane and enables homogenous

polymerization without disturbance of support membrane. The KANF support hydrogel membrane adds

additional mechanical support and robustness to the final membrane, and OH bonding between polymer

and amine chains helps to control the diffusion of amine monomers during interfacial polymerization.

49

Figure 17 Step by step process for fabrication of hydrogel-TFC membrane1

Figure 17 depicts the fabrication process for the hydrogel-TFC membrane; (a) casting of

KANF/DMSO (2 wt%) on a glass plate with knife; (b) immersion of glass plate with KANF solution in

water/PIP bath for phase inversion and preloading of PIP monomers in KANF hydrogel; (c) KANF

hydrogel preloaded with PIP monomers; (d) detail of nanofibrous PIP saturated structures; (e) Interfacial

polymerization with Hexane and TMC solution.

Membrane Fabrication Methods

This section details the fabrication of the KANF hydrogel saturated with PIP, interfacial

polymerization on the KANF hydrogel and conventional PSU support. Other membranes formed for this

study for comparison were interfacial polymerization at free hexane and water interface, and interfacial

50 polymerization onto a polyvinyl alcohol (PVA) based hydrogel. Details about the latter membranes are

found in the publication.

Synthesis of Nanofibrous Hydrogel Support Saturated with PIP Monomers

The nanofibrous support hydrogel was prepared through phase inversion of KANF and DMSO

dope solution (2 wt%) in a water bath preloaded with PIP monomers. This solution was spread onto a

glass plate at room temperature and humidity of 50-60% with a casting knife with a gap 200 μm. Then the

coated glass plated was immersed into deionized water to form KANF hydrogel membrane through

solvent exchange with DMSO. Furthermore, the concentration of PIP monomers dissolved in water bath

for phase inversion was (0.01 wt% to 0.04 wt%) and served to preload the hydrogel membrane. The

membrane was left in the water overnight to remove residual solvent, and its final appearance was

transparent and soft. The water content of this KANF hydrogel support membrane of 3D nanofibrous

networks was 96.5%. Figure 18 shows a cross section the hydrogel dried by a super critical dryer at a)

cross section; b) magnified cross section; c) bottom surface; d) top surface.

Figure 18 KANF Hydrogel post drying with super critical dryer1

51 Interfacial polymerization on nanofibrous hydrogel for TFC nanofiltration membrane

Since the hydrogel membrane was preloaded with PIP solution, there was no additional step

necessary to rinse and deposit PIP on surface for the interfacial polymerization. This preloading step

decreases the complexity of the fabrication by removing a step. Then to form the PA layer, a trimesoyl

chloride and n-hexane solution was poured on the porous bottom surface of the hydrogel membrane for 1

min. The solution contained 6 ml of TMC n-hexane solution with a concentration of 1 mg ml-1. Next,

excess TMC solution was dried in oven at 60 °C for 6 min, and the final IP membrane was stored in

stored in deionized water.

Interfacial polymerization on conventional PSU ultrafiltration membrane for Comparison

Interfacial polymerization of PIP and TMC monomers was also performed on a conventional

polysulfone (PSU) ultrafiltration support membrane as a comparison against the KANF hydrogel

membrane. In the fabrication process for the PSU IP membrane, the PSU ultrafiltration was wetted with

6ml PIP solution (0.01 wt%- 0.1wt%) for 5 min. The support membrane was dried gently with

compressed air to remove excess PIP. Then, a solution containing TMC and n-hexane (1 mg ml-1) was

poured on surface for 1 min. Finally, excess TMC solution dried in oven at 60 °C for 6 min and the final

membrane was storied in deionized water.

Membrane Characterization Results

The desalination performance of the TFC KANF membrane was measured by the water

permeability and rejection of salts in aqueous suspension. The TFC KANF membrane was compared

against the TFC PSU membrane and free-standing membrane to demonstrate its superior performance.

52 Other characterization methods such as SEM, AFM, water contact angle, water uptake, mechanical

strength, and zeta potential were used to explain and understand the desalination performance.

Permeability

The permeability of the TFC KANF membrane was initially evaluated with PIP concentrations of

0.0175 wt% and 0.0150wt%, and with TMC concentrations of 0.1w/v%. These values were selected from

other TFC monomer concentrations from literature.22 In this test, 1000 ppm Na2SO4 and water solution

was in the cross flow flat membrane filtration apparatus, and the impact of applied pressure was tested.

As shown in Figure 19, the flux of the membrane increased proportionally from 2 to 8 bar due to the

increased driving force of pressure. However, at higher pressure values, the rejection level of the

membrane decreased likely due to concentration polarization. Therefore, pressure values from 2 to 4 bar

had the highest rejection for the TFC KANF membrane with values at 97.1% and 96.4 for PIP

concentrations of 0.0175 wt % and 95.5% and 93.5% for PIP concentrations of 0.015 wt %. An applied

pressure of 4 bar ultimately gives the highest flux of 211.8 Lm-2h-1 (PIP 0.0175 wt %) and 251.6 Lm-2h-1

(PIP 0.015 wt %). At pressure values above 8 bar, the flux of the membrane levels off.

Figure 19 Impact of Applied Pressure on TFC KANF Membrane

2 4 6 80

100

200

300

400

500

600

Flux

(L. m

-2.h

-1)

Pressure (bar)

PIP-0.0175 wt% PIP-0.015 wt%

0

20

40

60

80

100

Reje

ctio

n (%

)

53 Then, the permeability and rejection of the TFC KANF hydrogel membrane were studied with

varying concentrations of PIP from 0.01 wt% to 0.04 wt% and a TMC concentration of 0.1 wt% (Figure

20). The amount of PIP was varied to adjust the thickness of the membrane, increase interactions between

the support and PA layer, and modify the electronegativity of the selective layer, and these modifications

ultimate influenced the permeability of the membrane. The permeability of the TFC KANF hydrogel

membrane increases from 18.3 to 62.9 Lm-2h-1bar-1 as the PIP concentration decreases from 0.04 wt% to

0.015 wt%. Furthermore, the Na2SO4 rejection decreases from 99.4% to 93.5% as the PIP concentration

decreases. At the ultrahigh permeation of 140 Lm-2h-1bar-1 at a PIP concentration of 0.01 wt%, the

rejection of Na2SO4 was too low at a value of 28%. At slightly higher concentrations of PIP (0.015 wt%),

the rejection increased to 92.5% and the permeability of water was 61 Lm-2h-1bar-1.

Figure 20 Permeability and Rejection for Varying PIP Concentrations for the TFC KANF Hydrogel Membrane

Next, the permeability of the TFC KANF hydrogel membrane, TFC polysulfone membrane, and

freestanding PA membrane was tested with varying concentrations of PIP from 0.01 wt% to 0.04 wt%

and a TMC concentration of 0.1 wt% (Figure 21).

Compared to the TFC KANF hydrogel membrane, the TFC PSU membrane had much higher

permeability, but much lower rejection. However, when the permeability was compared against the

rejection for Na2SO4, it was evident that a nanofiltration membrane was not formed until PIP

0.01 0.02 0.03 0.04

20

40

60

80

100

120

140

Perm

eabil

ity (L

/(m2 . h

. bar

))

PIP concentration (wt%)

0

20

40

60

80

100

Na2S

O 4 re

jectio

n (%

)

54 concentrations greater than 0.07 wt%. There are several reasons for the poor rejection and high

permeability of the TFC PSU membrane at lower PIP concentrations. For example, the interface of TMC/

n-hexane solution and wet PSU support are influenced by physiochemical properties such as the pore size,

hydrophilicity, and roughness of the PSU support membrane. These properties may lead to uneven

distribution and diffusion of amine monomers through the support membrane to the interface surface and

result in defected selective layer at the lower PIP concentrations. Ultimately, TFC membranes using a

PSU need a higher concentration of PIP than the KANF hydrogel to form a NF membrane for

desalination.

Likewise, when compared to the TFC KANF hydrogel membrane, the free-standing membrane

had lower permeability for all concentrations of PIP, but the rejection of Na2SO4 is above 90% for tested

PIP concentrations indicating a nanofiltration membrane was achieved. The lower permeability of the

free-standing membrane may be related to the greater thickness of the selective layer compared to the

TFC KANF hydrogel membrane, and the thickness is observed through TEM cross sections in a later

section. The TFC KANF hydrogel has strong bonds between the PIP monomers and the KANF hydrogel

and limits the diffusion of monomers to interface for the IP interaction result in lower consumption of

nearby monomers during polycondensation.

Figure 21 Permeability of TFC KANF Hydrogel membrane, TFC PSU Membrane, and Free Standing Membrane

0 0.01 0.02 0.03 0.04 0.05

0

50

100

150

200

250

300

Perm

eabi

lity

(L/(m

2 h b

ar))

PIP concentration (wt%)

PSU Freestanding KANF

55 Overall, the TFC KANF hydrogel membrane benefited from amide and OH groups in KANFs for

bonding with the PIP and limiting the diffusion of PIP to the interface of the membrane to create a defect-

free and thin selective separation layer for the optimal permeability and rejection in desalination

performance.

Selectivity and Rejection of Salts and Dyes

The rejection of salts in aqueous suspension is another important indicator of desalination

performance, only superficially mentioned in the previous section.

First, the rejection of the TFC KANF hydrogel membrane was tested using four salts including

MgSO4, MgCl2, NaCl, Na2SO4 (Figure 22). The rejection of MgSO4 and Na2SO4 salts was greater than

90% for PIP concentration as low as 0.015 wt%. The rejection of MgCl2 and NaCl was lower and likely

related to the smaller sulfate size of those ions compared to Na2SO4. Additionally, the membrane was

negatively charged and led to the higher rejection of MgSO4 and Na2SO4 salts due to the Donnan

exclusion effect and sulfate ions are removed to balance the surface charge of the membrane. The charge

of the membrane was later confirmed by the work of this paper when zeta potential curves were measured

to be negative for all pH values. The membrane is likely negatively charged due to the dissociation of

carboxylic acid groups from the hydrolysis of acyl chloride groups on the TMC monomer.61

Figure 22. Rejection of MgSO4, MgCl2, NaCl, Na2SO4 salts by the TFC KANF Hydrogel Membrane

0.01 0.02 0.03 0.04

0

20

40

60

80

100

Rejec

tion

(%)

PIP concentration (wt%)

Na2SO4 MgSO4 MgCl2 NaCl

56

To confirm the function of this membrane as a nanofiltration membrane for desalination

applications, several dyes solutions including congo red, direct red 80, direct red 23, and reactive blue 2

were filtered through TFC KANF hydrogel membranes at PIP concentrations of 0.0175 wt% and 0.015

wt%. For each dye in water, the rejection rate was over 98% for both membranes.

Then, the rejection of Na2SO4 of the TFC KANF hydrogel membrane, TFC polysulfone

membrane, and freestanding PA membrane was tested with varying concentrations of PIP from 0.01 wt%

to 0.04 wt% and a TMC concentration of 0.1 wt% (Figure 23). As the PIP concentration decreased, there

was a reduction in the rejection of each membrane. However, the TFC KANF hydrogel and the free

standing TFC membrane maintained sufficient nanofiltration rejection above 90% for PIP concentration

as low as 0.015 wt%. The drop off in rejection performance is likely due to the enlarged pore size of

membranes at lower concentrations of PIP. In contrast, the TFC PSU membrane was tested individually

and found that it did not form a nanofiltration membrane until concentration of PIP as high as 0.07 wt%.

At those concentrations of PIP, the permeability was much lower due to higher thickness resulting in poor

desalination performance.

Figure 23 Na2SO4 Rejection of TFC KANF Hydrogel Membrane, TFC PSU Membrane, and Free Standing Membrane

0.01 0.015 0.02 0.025 0.03 0.035 0.04

0

10

20

30

40

50

60

70

80

90

100

Na 2

SO4

reje

ctio

n (%

)

PIP concentration (wt%)

PSU Freestanding KANF

57 Lastly, continuous nanofiltration using Na2SO4 in aqueous solution in the cross flow filtration module

demonstrated no change over 6 hr in water flux and salt rejection (Figure 24). This desalination

performance is stable over long periods over and does not change due to membrane compression.

Figure 24. TFC KANF Membrane Desalination Performance Over 6 Hr

Compared to thirty state of the art desalination membranes from the past three years in literature,

these membranes had a superior desalination performance with the highest permeability of 62.9 Lm-2h-

1bar-1 and rejection of 92.5% for Na2SO4. Finally, as proof for scalability in industrial applications, large

pieces of TFC KANF hydrogel membranes were synthesized with dimensions of 19 cm x 35 cm.

Surface Characterizations

Several characterization methods were used to understand and explain the superior desalination

performance of the TFC KANF hydrogel membrane including SEM, TEM, water contact angle, and

water uptake. Figure 25 shows the final synthesized TFC KANF hydrogel membrane. The resulting

membrane was translucent with yellow and white tint.

0 100 200 3000

80

160

240

320Fl

ux (L

m-2

h-1

)

Time (min)

PIP-0.0175 wt% PIP-0.0150 wt%

40

60

80

100

Na 2

SO

4 re

ject

ion

(%)

58

Figure 25 Picture of TFC KANF Hydrogel Membrane

SEM

SEM images were taken to confirm the structure of the KANF hydrogel and the attachment of a

selective PA layer onto the hydrogel. Figure 26 shows a) the polymeric nanonetworks in the KANF

hydrogel, and b) the SEM surface image of the TFC KANF hydrogel membrane. As noted in Figure 26a,

the KANF hydrogel has a porous structure, and in Figure 26b, developed a highly dense surface due to IP

of PIP and TMC. The selective PA layer has a dense and smoother surface that is firmly attached to the

KANF hydrogel and indicates robust chemical interactions between the support and selective layer. High

compatibility between these layers yielded excellent membrane stability under long time periods. The

high compatibility was also proven with XPS results showing similar chemical groups and composition

between the layers, however that was not covered the scope of my work and can be found in the

supporting paper.

59

Figure 26 SEM images of a) the nanofibrous network of KANFs in the hydrogel membrane; b) the surface of the TFC PSU KANF hydrogel membrane

TEM

TEM images were taken to observe the cross-sectional regions of the TFC KANF hydrogel

membrane at different PIP concentrations and the free-standing membrane. The lowest possible thickness

achieved by IP on the KANF hydrogel yielded a crosslinked and defect free PA selective layer of 15.5nm.

From Figure 27, as the concentration of PIP was lowered from 0.04 wt% to 0.01 wt%, the thickness of the

PA selective layer decreased from 39nm to 15.5 nm. The lower thickness resulted in larger pore sizes as

the material was less densely packed to cover the same surface area as higher concentration. Furthermore,

the lower thickness improved the negative charge of the membrane resulting in higher rejection values for

salts. Compared to the free-standing membrane shown in Figure 27.d, the TFC KANF hydrogel

membrane had a lower thickness at the same PIP concentration. The TFC KANF hydrogel membrane

likely had a lower thickness due to the limited diffusion of PIP monomers through the KANF hydrogel

membrane to the interface surface, and the high compatibility of the PA layer to the KANF membrane

leading to a denser and tighter structure.

60

Figure 27 TEM images of the thickness of the selective separation layer of the KANF TFC hydrogel membrane fabricated with PIP concentrations of: a) 0.015 wt%; b) 0.02 wt%; and c) 0.04 wt%, and d) the thickness of the

freestanding membrane at PIP concentrations

AFM

The surface roughness measurements of the TFC KANF hydrogel membrane was observed and

found that the membrane was exceptionally smooth with an average of 8 nm for all concentrations of PIP

(Figure 28). The smooth surface provides less effective surface area for permeation but decreases the

effect of fouling on the surface. As the membrane already has excellent permeability, the lower surface

area is not a concern.

Figure 28 AFM morphology of Hydrogel-TFC membranes synthesized from PIP concentration of 0.0175 wt% and 0.02 wt%

The AFM measurements for this membrane are found in Table 4.

61 Table 4 Roughness of TFC KANF Hydrogel membranes

TFC KANF Hydrogel

PIPO Concentrations

(Wt%)

0.015 0.0175 0.02

Roughness (nm) 7.28 8.1 8.06

Water Contact Angle

The water contact angle was measured to determine the hydrophilicity of the membrane. The TFC KANF

hydrogel membrane had a water contact angle of 54 degrees, indicating hydrophilicity (Figure 29).

Hydrophilicity is recommendable to avoid fouling of the membrane surface.

Figure 29 Water contact angle of dry nanofibrous hydrogel (72°) and Hydrogel-TFC membrane (PIP-0.015，54°)

Water Uptake

The water uptake of the TFC KANF hydrogel membrane was 96.5 wt% which was similar to

free water phase in freestanding IP membranes.

62

Chapter 7

Conclusions and Future Work

TFC Vacuum Filtration KANF Membrane for Organic Solvent Nanofiltration

The vacuum filtration method deposited a KANF selective layer onto the support membranes of

alumina and PTFE, and the thickness of the membrane was controlled by the amount of KANF deposited

onto the surface. However, this membrane failed to selectively filter out dyes from solvent and needs

further work. Low rejection failed to yield nanofiltration results and was caused by microcracks and poor

interactions between the KANFs and support. It is also possible that the KANFs fall through the porous of

the support membrane, causing the defects in the membrane surface. Furthermore, there is no long-term

stability of the TFC KANF membrane, most likely caused by compression of the selective KANF layer

on the support membrane.

This work is in its infancy stages, but there are several techniques to improve its performance and

ultimately create a successful organic solvent nanofiltration membrane. For instance, dopamine can be

used to improve KANF and support interactions. However, dopamine is not readily available for purchase

in this country and does increase the costs of fabrication significantly. Furthermore, the membranes can

be left to airdry overnight to avoid potential peeling from the support membrane; while this increases the

time of fabrication, it may put less stress between the support and selective layer. Another method to

improve the membrane is to research different support membranes that are more compatible with KANF

selective layer, such as support membranes with similar chemical groups and composition. Additionally,

PVA or PEI can be added to the KANF dope solution to improve the flexibility of the selective membrane

layer and decrease the number of cracks or another molecule can be found that has computability with the

KANF and the support membrane to further improve compatibility. However, adding another molecule to

63 the dope solution and selective layer may lessen the effects of the heat treatment and formation of a

nanofiltration selective layer.

Once a viable dope solution and support membrane are established, a 100 nm selective KANF

layer may be deposited onto the support and subsequently heat treated to form a nanofiltration membrane.

At this point, the dope solution may be modified to decrease to content of material and therefore control

the thickness of the selective layer of the organic solvent nanofiltration membrane.

Overall, this idea has merit to conceive an organic solvent nanofiltration membrane with a

controllable thickness of the selective layer and therefore greater permeability and performance.

Additionally, this method reduces the amount of solvent used by utilizing a greener solvent DMSO as

opposed to more acidic solvents like H2SO4 and a facile heat treatment rather than additional chemicals

that need to be separated and recovered. Currently, this is not an optimal fabrication method for OSN

membranes. Although, the promising reduction in the CO2 footprint of this OSN membrane, and

potentially controllable structure and performance provide an excellent alternative to traditional

separation processes and perhaps other state of the art membranes in terms of sustainability and cost

effectiveness.

TFC KANF Hydrogel Membrane for Desalination

Interfacial polymerization of PIP and TMC monomers onto the porous bottom of a KANF

hydrogel membrane successfully fabricated a nanofiltration desalination membrane. The fabrication steps

of the synthesis were reduced by preloading (PIP) monomers into the KANF hydrogel as an aqueous

phase and reacted with trimethyl chloride and hexane to form a strong polyamide (PA) selective layer.

The resulting membranes with PIP concentrations of 0.0175 wt% and 0.015 wt% and TMC concentration

of 0.01 wt% yielded ultrafast permeance of 52.8 and 62.9 Lm-2h-1bar-1. This selective PA layer reached a

rejection of 96.4% and 93.5% for Na2SO4 and in comparison, superior desalination performance to other

64 PA TFC nanofiltration membranes.1 The superior performance is attributed to the decreased thickness of

the selective layer due to the strong interactions between the KANF hydrogel support membrane and PA

selective layer. The membrane and the support layer have similar chemical groups and composition such

as amide groups and hydrogen bonding. Moreover, no harsh solvents or crosslinking chemicals were

utilized in this fabrication process, and the process can be easily scaled up with the fabrication of large

membrane sheets.

The TFC KANF Hydrogel membrane has excellent desalination performance, but there is still

room for improvement. For example, the concentration of TMC may be adjusted to improve the charge of

the membrane surface to reject more salts or heavy metals.62 Additionally, other materials other than

KANFs and PVA may be synthesized and implemented as hydrogel support to perform IP for

desalination membranes. Likewise, monomer alternative to PIP may be used such as MPD to possibly

adjust the negative charge or thickness of the selective layer. Therefore, through the combination of size

exclusion and adjusting the electronegativity of the membrane surface, the performance of the membrane

may be improved. Alternatively, covalent organic framework materials may be added into the selective

layer during IP to increase the permeability and maintain the rejection of the membrane performance.

This membrane may also be adapted as an organic solvent nanofiltration membrane, depending on the

solvent resistance of the selective layer.

Overall, the TFC KANF hydrogel membrane is an excellent option for current desalination

systems with the potential to make operations 3x faster. Faster operations reduce the operating time and in

effect cost and energy usage, making this a green viable alternative. Furthermore, the CO2 footprint of this

membrane is reduced by the consolidation of fabrication steps, avoidance of harsh solvents, and the

ability to scale to size. For large scale manufacturing of IP TFC membranes, the current membrane

support may be replaced with the KANF hydrogel membrane to create superior desalination membranes

with a more sustainable and cost effective approach.

65 Appendix A

Surface Morphology of KANF and PSU-TFC membranes

Figure 30 Surface morphology of Hydrogel-TFC membranes

Figure 31 Surface morphology of PSU-TFC membranes

References

(1) Yuan, S.; Zhang, G.; Zhu, J.; Mamrol, N.; Liu, S.; Mai, Z.; Van Puyvelde, P.; Van Der

Bruggen, B. Hydrogel Assisted Interfacial Polymerization for Advanced Nanofiltration

Membranes. J. Mater. Chem. A 2020, 8 (6), 3238–3245.

https://doi.org/10.1039/c9ta12984g.

(2) Zhao, Y.; Wu, M.; Shen, P.; Uytterhoeven, C.; Mamrol, N.; Shen, J.; Gao, C.; Van der

Bruggen, B. Composite Anti-Scaling Membrane Made of Interpenetrating Networks of

Nanofibers for Selective Separation of Lithium. J. Memb. Sci. 2021, 618, 118668.

https://doi.org/10.1016/j.memsci.2020.118668.

(3) Yuan, S.; Li, X.; Zhu, J.; Zhang, G.; Van Puyvelde, P.; Van Der Bruggen, B. Covalent

Organic Frameworks for Membrane Separation. Chemical Society Reviews. Royal Society

of Chemistry May 21, 2019, pp 2665–2681. https://doi.org/10.1039/c8cs00919h.

(4) Jerneck, A.; Olsson, L.; Ness, B.; Anderberg, S.; Baier, M.; Clark, E.; Hickler, T.;

Hornborg, A.; Kronsell, A.; Lövbrand, E.; et al. Structuring Sustainability Science.

Sustain. Sci. 2011, 6 (1), 69–82. https://doi.org/10.1007/s11625-010-0117-x.

(5) Komiyama, H.; Takeuchi, K. Sustainability Science: Building a New Discipline. Sustain.

Sci. 2006, 1 (1), 1–6. https://doi.org/10.1007/s11625-006-0007-4.

(6) Chang, S. H. Utilization of Green Organic Solvents in Solvent Extraction and Liquid

Membrane for Sustainable Wastewater Treatment and Resource Recovery—a Review.

Environmental Science and Pollution Research. Springer September 1, 2020, pp 32371–

32388. https://doi.org/10.1007/s11356-020-09639-7.

(7) Keeble, B. R. The Brundtland Report: “Our Common Future.” Med. War 1988, 4 (1), 17–

25. https://doi.org/10.1080/07488008808408783.

(8) Dedeurwaerdere, T. Sustainability Science for Strong Sustainability; Edward Elgar

Publishing, 2014. https://doi.org/10.4337/9781783474561.

(9) Green Technology - What is it? - Green Technology https://www.green-

technology.org/green-technology-what-is-it/ (accessed Sep 13, 2020).

(10) Dharupaneedi, S. P.; Nataraj, S. K.; Nadagouda, M.; Reddy, K. R.; Shukla, S. S.;

Aminabhavi, T. M. Membrane-Based Separation of Potential Emerging Pollutants. Sep.

Purif. Technol. 2019, 210 (September 2018), 850–866.

https://doi.org/10.1016/j.seppur.2018.09.003.

(11) Clarke, C. J.; Tu, W. C.; Levers, O.; Bröhl, A.; Hallett, J. P. Green and Sustainable

Solvents in Chemical Processes. Chem. Rev. 2018, 118 (2), 747–800.

https://doi.org/10.1021/acs.chemrev.7b00571.

(12) Lively, R. P.; Sholl, D. S. From Water to Organics in Membrane Separations: Membrane

Materials Provide Economical Means to Achieve Various Separation Processes - And

Their Capabilities for Processing Organic Fluids Look Set to Expand Significantly. Nat.

Mater. 2017, 16 (3), 276–279. https://doi.org/10.1038/nmat4860.

(13) Proctor, C. R.; Lee, J.; Yu, D.; Shah, A. D.; Whelton, A. J. Wildfire Caused Widespread

Drinking Water Distribution Network Contamination. AWWA Water Sci. 2020, 2 (4).

https://doi.org/10.1002/aws2.1183.

(14) Desalination basics | Water Tech Online https://www.watertechonline.com/process-

water/article/15550278/desalination-basics (accessed Oct 30, 2020).

(15) Sholl, D. S.; Lively, R. P. Seven Chemical Separations to Change the World. Nature.

Nature Publishing Group April 26, 2016, pp 435–437. https://doi.org/10.1038/532435a.

(16) Seader, J. D., Henley, E. J. Separation Process Principles, Second Edi.; John Wiley &

Sons: NY.

(17) Strathmann, H. Introduction to Membrane Science and Technology; Wiley-VCH Verlag &

Co. KGaA: Weinheim, Germany, 2011.

(18) Pinnau, I.; Freeman, B. D. Formation and Modification of Polymeric Membranes:

Overview; 2000.

(19) Hobbs, C.; Hong, S.; Taylor, J. Effect of Surface Roughness on Fouling of RO and NF

Membranes during Filtration of a High Organic Surficial Groundwater. J. Water Supply

Res. Technol. - AQUA 2006, 55 (7–8), 559–570. https://doi.org/10.2166/aqua.2006.038.

(20) Marchetti, P.; Jimenez Solomon, M. F.; Szekely, G.; Livingston, A. G. Molecular

Separation with Organic Solvent Nanofiltration: A Critical Review. Chem. Rev. 2014, 114

(21), 10735–10806. https://doi.org/10.1021/cr500006j.

(21) Saljoughi, E. Methods of Polymeric Membrane Preparation. pp 1–49.

(22) Wu, D.; Yu, S.; Lawless, D.; Feng, X. Thin Film Composite Nanofiltration Membranes

Fabricated from Polymeric Amine Polyethylenimine Imbedded with Monomeric Amine

Piperazine for Enhanced Salt Separations. React. Funct. Polym. 2015, 86, 168–183.

https://doi.org/10.1016/j.reactfunctpolym.2014.08.009.

(23) Zhu, S.; Zhao, S.; Wang, Z.; Tian, X.; Shi, M.; Wang, J.; Wang, S. Improved Performance

of Polyamide Thin-Film Composite Nanofiltration Membrane by Using

Polyetersulfone/Polyaniline Membrane as the Substrate. J. Memb. Sci. 2015, 493, 263–

274. https://doi.org/10.1016/j.memsci.2015.07.013.

(24) Van Der Bruggen, B. Membrane Technology. Leuven, Belgium pp 1–50.

(25) Szekely, G.; Jimenez-Solomon, M. F.; Marchetti, P.; Kim, J. F.; Livingston, A. G.

Sustainability Assessment of Organic Solvent Nanofiltration: From Fabrication to

Application. Green Chemistry. Royal Society of Chemistry October 1, 2014, pp 4440–

4473. https://doi.org/10.1039/c4gc00701h.

(26) Davood Abadi Farahani, M. H.; Ma, D.; Nazemizadeh Ardakani, P. Nanocomposite

Membranes for Organic Solvent Nanofiltration. Sep. Purif. Rev. 2020, 49 (3), 177–206.

https://doi.org/10.1080/15422119.2018.1526805.

(27) Yuan, S.; Swartenbroekx, J.; Li, Y.; Zhu, J.; Ceyssens, F.; Zhang, R.; Volodine, A.; Li, J.;

Van Puyvelde, P.; Van der Bruggen, B. Facile Synthesis of Kevlar Nanofibrous

Membranes via Regeneration of Hydrogen Bonds for Organic Solvent Nanofiltration. J.

Memb. Sci. 2019, 573, 612–620. https://doi.org/10.1016/J.MEMSCI.2018.12.047.

(28) Gothandam, K. M. Food Security and Water Treatment; 2018.

(29) Zhao, Y.; Li, X.; Shen, J.; Gao, C.; Van Der Bruggen, B. The Potential of Kevlar Aramid

Nanofiber Composite Membranes. Journal of Materials Chemistry A. Royal Society of

Chemistry April 28, 2020, pp 7548–7568. https://doi.org/10.1039/d0ta01654c.

(30) Roberts, A. D.; Kelly, P.; Bain, J.; Morrison, J. J.; Wimpenny, I.; Barrow, M.; Woodward,

R. T.; Gresil, M.; Blanford, C.; Hay, S.; et al. Graphene-Aramid Nanocomposite Fibres:

Via Superacid Co-Processing. Chem. Commun. 2019, 55 (78), 11703–11706.

https://doi.org/10.1039/c9cc04548a.

(31) Zhao, Y.; Zhang, S.; Hu, F.; Li, J.; Chen, H.; Lin, J.; Yan, B.; Gu, Y.; Chen, S.

Electrochromic Polyaniline/Aramid Nanofiber Composites with Enhanced Cycling

Stability and Film Forming Property. J. Mater. Sci. Mater. Electron. 2019, 30 (13),

12718–12728. https://doi.org/10.1007/s10854-019-01636-y.

(32) Sulfuric Acid | NIOSH | CDC https://www.cdc.gov/niosh/topics/sulfuric-acid/default.html

(accessed Oct 5, 2020).

(33) Khodadadi, A.; Liaghat, G.; Vahid, S.; Sabet, A. R.; Hadavinia, H. Ballistic Performance

of Kevlar Fabric Impregnated with Nanosilica/PEG Shear Thickening Fluid. Compos.

Part B Eng. 2019, 162, 643–652. https://doi.org/10.1016/j.compositesb.2018.12.121.

(34) Li, D.; Gou, X.; Wu, D.; Guo, Z. A Robust and Stretchable Superhydrophobic

PDMS/PVDF@KNFs Membrane for Oil/Water Separation and Flame Retardancy.

Nanoscale 2018, 10 (14), 6695–6703. https://doi.org/10.1039/c8nr01274a.

(35) Zhang, Z.; Yang, S.; Zhang, P.; Zhang, J.; Chen, G.; Feng, X. Mechanically Strong

MXene/Kevlar Nanofiber Composite Membranes as High-Performance Nanofluidic

Osmotic Power Generators. Nat. Commun. 2019, 10 (1), 1–9.

https://doi.org/10.1038/s41467-019-10885-8.

(36) Lv, L.; Han, X.; Zong, L.; Li, M.; You, J.; Wu, X.; Li, C. 8178−8184 Downloaded via KU

LEUVEN On. ACS Nano 2017, 11, 30. https://doi.org/10.1021/acsnano.7b03119.

(37) Li, H.; Shi, W.; Zhang, Y.; Zhou, R. Preparation and Characterization of Compatible

PVDF/PPTA Blends by in Situ Polymerization for Separation Membrane Materials. J.

Polym. Res. 2015, 22 (2), 1–14. https://doi.org/10.1007/s10965-015-0666-x.

(38) Chen, Z.; Du, X. A.; Liu, Y.; Ju, Y.; Song, S.; Dong, L. A High-Efficiency Ultrafiltration

Nanofibrous Membrane with Remarkable Antifouling and Antibacterial Ability. J. Mater.

Chem. A 2018, 6 (31), 15191–15199. https://doi.org/10.1039/c8ta02649a.

(39) Xu, R.; Yue, J.; Liu, S.; Tu, J.; Han, F.; Liu, P.; Wang, C. Cathode-Supported All-Solid-

State Lithium− Sulfur Batteries with High Cell-Level Energy Density. 2019, 18, 24.

https://doi.org/10.1021/acsenergylett.9b00430.

(40) Spiral-Wound Module - an overview | ScienceDirect Topics

https://www.sciencedirect.com/topics/engineering/spiral-wound-module (accessed Oct 29,

2020).

(41) Liu, M.; Yu, S.; Qi, M.; Pan, Q.; Gao, C. Impact of Manufacture Technique on Seawater

Desalination Performance of Thin-Film Composite Polyamide-Urethane Reverse Osmosis

Membranes and Their Spiral Wound Elements. J. Memb. Sci. 2010, 348, 268–276.

https://doi.org/10.1016/j.memsci.2009.11.019.

(42) Gould, R. M.; White, L. S.; Wildemuth, C. R. Membrane Separation in Solvent Lube

Dewaxing. Environ. Prog. 2001, 20 (1), 12–16. https://doi.org/10.1002/ep.670200110.

(43) Kevlar Chemistry: Production and Recycling

https://kevlarchemistry.neocities.org/about3.html (accessed Oct 3, 2020).

(44) Missimer, T. M.; Maliva, R. G. Environmental Issues in Seawater Reverse Osmosis

Desalination: Intakes and Outfalls. Desalination. Elsevier B.V. May 15, 2018, pp 198–

215. https://doi.org/10.1016/j.desal.2017.07.012.

(45) Why Clean Water Is So Critical for Women and Girls Everywhere

https://www.globalcitizen.org/en/content/wash4women-campaign-explainer/ (accessed

Oct 29, 2020).

(46) Andrianne, J.; Alardin, F. Desalination Site Selection on North-African Coasts.

Desalination 2004, 165 (SUPPL.), 231–239. https://doi.org/10.1016/j.desal.2004.06.026.

(47) IAEA. Nuclear Desalination of Sea Water. 1997.

(48) Overview, E. Do Not Touch Moving Threadlines of KEVLAR ® Fiber . Entanglement

with This High Strength Fiber Can Severely Cut or Even Sever Fingers . No. 937.

(49) Asmatulu, E.; Alonayni, A.; Alamir, M. Safety Concerns in Composite Manufacturing and

Machining. 2018, 1059623 (March 2018), 68. https://doi.org/10.1117/12.2296707.

(50) Congo Red | Dye Reagent | MedChemExpress

https://www.medchemexpress.com/Congo_Red.html (accessed Oct 28, 2020).

(51) Direct Red 80 Dye content 25 % | 2610-10-8 | Sigma-Aldrich

https://www.sigmaaldrich.com/catalog/product/sial/365548?lang=en&region=US

(accessed Oct 28, 2020).

(52) Direct Red 23 http://www.worlddyevariety.com/direct-dyes/direct-red-23.html (accessed

Oct 28, 2020).

(53) Reactive Blue 2 http://www.worlddyevariety.com/reactive-dyes/reactive-blue-2.html

(accessed Oct 28, 2020).

(54) Yuan, S. Advanced Membrane Synthesis Methods: Exploration of 3D Printed Membranes

for Oil/Water Separation and Development of Novel Polymers for Organic Solvent

Nanofiltration - KU Leuven, KU Leuven: Leuven, 2018.

(55) Wang, F.; Wu, Y.; Huang, Y.; Liu, L. Strong, Transparent and Flexible Aramid

Nanofiber/POSS Hybrid Organic/Inorganic Nanocomposite Membranes. Compos. Sci.

Technol. 2018, 156, 269–275. https://doi.org/10.1016/j.compscitech.2018.01.016.

(56) Li, J.; Tian, W.; Yan, H.; He, L.; Tuo, X. Preparation and Performance of Aramid

Nanofiber Membrane for Separator of Lithium Ion Battery. 2016, 43623, 1–8.

https://doi.org/10.1002/app.43623.

(57) Lv, L.; Han, X.; Zong, L.; Li, M.; You, J.; Wu, X.; Li, C. Biomimetic Hybridization of

Kevlar into Silk Fibroin: Nanofibrous Strategy for Improved Mechanic Properties of

Flexible Composites and Filtration Membranes. ACS Nano 2017, 11, 54.

https://doi.org/10.1021/acsnano.7b03119.

(58) Sun, Z.; Wu, Q.; Ye, C.; Wang, W.; Zheng, L.; Dong, F.; Yi, Z.; Xue, L.; Gao, C.

Nanovoid Membranes Embedded with Hollow Zwitterionic Nanocapsules for a Superior

Desalination Performance. Nano Lett. 2019, 19 (5), 2953–2959.

https://doi.org/10.1021/acs.nanolett.9b00060.

(59) Jimenez-Solomon, M. F.; Song, Q.; Jelfs, K. E.; Munoz-Ibanez, M.; Livingston, A. G.

Polymer Nanofilms with Enhanced Microporosity by Interfacial Polymerization. Nat.

Mater. 2016, 15 (7), 760–767. https://doi.org/10.1038/nmat4638.

(60) Ahmed, E. M. Hydrogel: Preparation, Characterization, and Applications: A Review.

Journal of Advanced Research. Elsevier B.V. March 1, 2015, pp 105–121.

https://doi.org/10.1016/j.jare.2013.07.006.

(61) Park, H. M.; Takaba, H.; Lee, Y. T. Preparation and Characterization of TFC NF

Membrane with Improved Acid Resistance Behavior. J. Memb. Sci. 2020, 616, 118620.

https://doi.org/10.1016/j.memsci.2020.118620.

(62) Tian, J.; Chang, H.; Gao, S.; Zhang, R. How to Fabricate a Negatively Charged NF

Membrane for Heavy Metal Removal via the Interfacial Polymerization between PIP and

TMC? Desalination 2020, 491 (June), 114499.

https://doi.org/10.1016/j.desal.2020.114499.

Natalie Dayrit Mamrol Email: ndm5198@psu.edu; LinkedIn Profile: Natalie Mamrol

Number: (215)-527-2534

EDUCATION

The Schreyer Honors College, Penn State, University Park, PA B. S. in Material Science and Engineering, Magna Cum Laude K.U. Leuven, Leuven, Belgium Euroscholars Research Abroad Program

• Prestigious semester-long study abroad program designed for talented and highly motivated undergraduate students looking to participate in international research

London Study Tour, London and Edinburgh, U.K

• Signature travel program of Schreyer Honors College to culture politically, theoretically, ethically, religiously, socially, and philosophically through live musical theatre and drama

Graduation 2020

Spring 2019

May 2018

Pennridge High School, Perkasie, PA Salutatorian

Graduation 2016

RESEARCH EXPERIENCE

Membrane Synthesis and Fabrication Researcher in Van der Bruggen Group K.U. Leuven, Leuven, Belgium • Applied polymer synthesis, characterization, and data analysis to

develop and test membranes for organic solvent nanofiltration applications

• Won the Euroscholars Consortium Grant and Schreyer Travel Grant to perform research through Euroscholars program at K.U. Leuven

• Coauthored multiple publications on these work • Presented at Euroscholars Student Research Competition

Jan. 2019-Present

3D Printing and Membrane Synthesis Researcher in Hickner Research Group

Pennsylvania State University, University Park, PA • Employed polymer synthesis, characterization, and data analysis to

perform independent project to develop 3D-printed and color responsive ion exchange membranes for applications in heavy metal detection and filtration

• Working on a publication related to 3D polymerized colorimetric sensor for pH detection using cell phone photography

Jan. 2018- 2020

Polymer Research Assistant in Runt Research Group Pennsylvania State University, University Park, PA • Exercised polymer synthesis, characterization, and data analysis with

team of graduate students to tailor glass transition state in epoxy and polyurethane integrated networks for applications in soundproof coatings

• Won NASA WISER Freshman Grant to perform research for two semesters

Dec. 2016-2017

Natalie Dayrit Mamrol Email: ndm5198@psu.edu; LinkedIn Profile: Natalie Mamrol

Number: (215)-527-2534

• Acknowledged for my work in associated paper: Ion Transport in Pendant and Backbone Polymerized Ionic Liquids

PROFESSIONAL EXPERIENCE

Polyethylene Product Development Intern

ExxonMobil Chemical, Houston, TX • Conducted polymer research in product development of PE • Organized and prepared extrusion line operations for 7 different PE

grades and led characterization team in scientific investigation of PE thermal properties such as hot tack and sealing

• Presented findings to PE Product Development Department and intern presentations

May-Aug. 2019

Metallurgy Intern Corning Incorporated, Corning, NY • Used metallurgical engineering to complete microstructural and

surface finish study on the metals used to fabricate dies for cellular ceramic extrusion

• Optimized processing route via selected heat treatments and post-processing finishing techniques in fabrication process to increase lifespan of dies

• Presented conclusive findings to metallurgy departmental meeting and at the intern poster competition

May-Aug. 2018

Material Process and Metallurgy Engineering Intern Precision Castparts Corporation, New Hartford, NY • Practiced metallurgical sample preparation and characterization and

statistical analysis to assist senior engineers on study of the changes in mechanical properties, microstructure, and chemical composition during heat treatments for Ni-Ti alloy

• Wrote several standard operating procedures and documentation to optimize heat treatment conditions

May-Aug. 2017

PUBLICATIONS

MAJOR PUBLICATIONS: • Y. Zhao, M. Wu, P. Shen, C. Uytterhoeven, N. Mamrol, J. Shen, C. Gao, B. V. Bruggen, "Composite

anti-scaling membrane made of interpenetrating networks of nanofibers for selective separation of lithium." J. Membr. Sci., 618 (2021).

• S. Yuan, G. Zhang, J. Zhu, N. Mamrol, S. Liu, Z. Mai, P.V. Puyvelde, B.V. Bruggen, "Hydrogel assisted interfacial polymerization for advanced nanofiltration membranes." J. of Mater. Chem. A, 8[6], 3238-3245.

HONORS UNDERGRADUATE THESIS: • Mamrol, Natalie. DEVELOPMENT OF KEVLAR ARAMID NANOFIBROUS MEMBRANES FOR

NANOFILTRATION SEPARATION PROCESSES. 2020. Penn State University, Schreyer Honors Thesis.

Natalie Dayrit Mamrol Email: ndm5198@psu.edu; LinkedIn Profile: Natalie Mamrol

Number: (215)-527-2534

SUBMITTED PUBLICATIONS: • Y. Zhao, N. Mamrol, W. A. Tarpeh, Y. Guo, B.V. Bruggen, "Fundamentals, fabrication, and

application of ion-selective electro-driven membranes for aqueous separations." {Submitted} • Y. Zhao, Y. Qui, N. Mamrol, E. Ortega, X. Li, J. Shao, C. Gao, B. V. Bruggen, "Membrane

bioreactors in medical wastewater treatment for epidemic prevention." {Submitted} ACKNOWLEDGED AND ASSOCIATED PUBLICATIONS:

• S. Yuan, X. Li, J. Zhu, G. Zhang, P. V. Puyvelde, B. V. Bruggen, “Covalent organic frameworks for membrane separation.” Chem. Soc. Rev., 48 2665-2681 (2019).

• P. Kuray, T. Noda, A. Matsumoto, C. Iacob, T. Inoue, M. Hickner, J. Runt, “Ion Transport in Pendant and backbone Polymerized Ionic Liquids.” Am. Chem. Soc., 52 [17] 6438-6448 (2019).

LEADERSHIP EXPERIENCE

Team Leader of Engineering Methodology and Design Team

Pennsylvania State Material Science and Engineering Competition • Led five-member team in my proposal to implement piezo-resistive

polymer composite sensors into gloves to enhance virtual reality experiences

• Highest score on my engineering pitch, high marks on white paper, and full proposal

• Reviewed engineering considerations in economic, environmental, sustainability, manufacturability, ethics, etc.

Jan.- May 2018

Executive Secretary & Relay for Life Chairperson College of Earth and Mineral Sciences Student Council • Facilitated friendly interactions between student, faculty, and

alumni; organize college wide communication, professional events, and volunteer opportunities; maintain membership involvement to support over 150 active members with purpose of fostering a diverse, educational, and communal environment for all College of Earth and Mineral Sciences undergraduate members

• Created and implemented fundraising events, organized volunteers, and raised over $3,000 for Penn State Relay for Life event to promote awareness for the American Cancer Foundation resources and survivors

Sept. 2016- 2017

TECHNICAL AND SOFT SKILLS

• Material Preparation and Characterization: 3D Printing, Differential Scanning Calorimeter (DSC), Dynamic Mechanical Analysis (DMA), and Dielectric Spectrometry, RGB Color Analysis, Tensile Testing, Polishing/Grinding/Etching, Optical Microscopy, SEM, Surface Roughness, Abrasive Saw Machining, Membrane Synthesis and Fabrication, Metal Characterization, Polymer Characterization

• Data Analysis: Origin, JMP, MATLAB, Excel • Communication: Technical reports, Research presentations, Poster presentations, Mentoring

Natalie Dayrit Mamrol Email: ndm5198@psu.edu; LinkedIn Profile: Natalie Mamrol

Number: (215)-527-2534

EXTRACURRICULAR ACTIVITIES

Phi Sigma Rho: Sorority of Women Engineers Sept. 2016- Present EMS Ambassadors May 2018- Present Material Advantage Member Sept. 2016- Present Mathematics Grader

Aug 2018 – Dec 2018

DISTINCTIONS

AWARDS EMSAGE Laureate

• Awarded to Penn State College of Earth and Mineral Sciences Students with significant achievement across the broad categories of scholarship, experiential learning and global literacy, and service

Penn State Schreyer Honors College Medal • Just 5% of the undergraduate students enrolled at Penn State are members

of the Schreyer Honors College and can earn the distinction of graduating with honors from Penn State

Dean's List Salutatorian, Pennridge High School GRANTS Euroscholars Grant Award (€2500) Schreyer Travel Grant for Euroscholars Internship ($750) Schreyer Travel Grant for London Study Tour ($750) NASA PA Space Grant Research Internship Program ($1200) SCHOLARSHIPS Binder for Studies Scholarship, PSU College of EMS Scholarship J & E Teas Scholarship, PSU College EMS Scholarship AVX/Kyocera Foundation Scholarship, PSU MATSE Department Scholarship S & T Ross Trustee Scholarship, PSU Schreyer Honors College Scholarship R&M Munro Trustee Scholarship, PSU Schreyer Honors College Scholarship Michael M. and Mary Jane Coleman UG Award in the College of Earth and Mineral Science, PSU MATSE Department Scholarship State of the Art, Inc. Annual Scholarship, PSU MATSE Department Scholarship Dr. Peter B. Lake Endowed Scholarship, PSU MATSE Department Scholarship Matthew J Wilson Honors Scholarship, PSU College of EMS Scholarship Penn State Provost Award Verna M. Butterer Educational Trust Scholarship

• Annual award up to $14,000 to Bucks County demonstrated a financial need to achieve a post-secondary education in their chosen fields.

2020

2020

2016-2020 2016

2019 2019 2018

2016-2017

2019 2019 2019 2019 2018 2018

2017 2017

2016-2020 2016-2019 2016-2020