Development of RO Membrane & Its Characterization2003.ppt

Designed by:Adeel Fayyaz (12 – P.E – 01)Rehan Hasan (12 – P.E – 33)

Zohaib Siddiqui (12 – P.E – 44)

04/11/23 1

Project Presentation On:

Tables Of ContentHistoryWhat is Reverse Osmosis?Membrane & Its typesReverse Osmosis Membranes & its comparisonMembrane MaterialsMembrane ModulesMembrane FoulingWork Plan of our ProjectTestingDesalinationBenefits

04/11/23 2Plastic Technology Center, Karachi

HistoryThe first studies on osmosis were carried out as early as 1748 by the French scientist Nollet.

The early 1960's, Loeb and Sourirajan developed a method for making asymmetric Cellulose acetate membranes

In 1970, the development of new-generation membranes such as the thin-film, composite Membrane that can tolerate wide pH ranges, higher temperatures and harsh chemical environments.

An estimate indicated that sales of RO membrane products had grown to $280 million yearly in 2006


What is REVERSE OSMOSIS?Osmosis is a natural phenomenon in which a solvent (usually water) passes through a semi permeable barrier from the side with lower solute concentration to the higher solute concentration side. As shown in Figure(a).

A reverse osmosis membrane acts as the semi permeable barrier to flow in the RO process, allowing selective passage of a particular species (solvent, usually water) while partially & completely retaining other species (solutes). As shown in Figure(b).


Membrane & Its typesWater treatment processes employ several types of membranes. They include

MF membranes have the largest pore size and typically reject large particles and various microorganisms.

UF membranes have smaller pores than MF membranes and, therefore, in addition to large particles and microorganisms, they can reject bacteria and soluble macromolecules such as proteins. RO membranes are effectively non-porous and, therefore, exclude particles and even many low molar mass species such as salt ions, organics, etc.

NF membranes are relatively new and are sometimes called “loose” RO membranes


Cellulose Acetate MembraneThin Film Composite Membrane


CA MembraneThese initial RO membrane was made by the Loeb-Sourirajan

These CA membranes were asymmetric and exhibited NaCl rejection values of approximately 99.5%

The degree of acetylation describes the how many pendent OH groups are replaced acetyl groups, CH3COO.

It ranges from 0 to 3

they have excellent mechanical properties & resistant to chlorine.

CA membranes can tolerate up to 5 ppm


Thin Film Composite MembraneThe first TFC RO membrane was developed by John Cadotte at North Star Research in 1972, based on aromatic polyamides.

interfacial polymerization are use to create a polyamide coating.

Most TFC membranes are made with a porous, highly permeable support.

Nowadays, This technique can also be used to produce Commercial RO membranes


Comparison of Reverse Osmosis MembranesCA Membranes TFC Membranes

Rejection of Organic Low High

Rejection of low mol. weight organics

Low High

Water Flux Medium High

pH Tolerance 4-8 2-11

Temperature stability Max. 35c Max. 45c

Oxidant tolerance High Low

Compaction tendency High Low

Biodegradability High Low

Cost Low High

04/11/23 Plastic Technology Center, Karachi 9

RO MembranesThere are typically

cellulose acetatePolysulfone coated with aromatic polyamides


MF & UF MaterialsPoly (vinylidene fluoride)PolysulfonePoly (acrylonitrile)Poly (acrylonitrile)-poly(vinyl chloride) copolymersPoly (ether sulfone) is also commonly used for UF

membranespoly (tetrafluoroethylene).


Modules of membraneThere are four main types of modules:

plate-and-frame

Tubular

spiral wound

hollow fiber


Causes of Fauling Bio-fouling(it results from microbial contamination of feed water)

Scaling (It arises from the deposition of salts)

Organic(It comes from substances i.e. C-H which coat the surface)

Colloidal(It mainly stems from particles)


Strategy of Work PlanDevelop a CA Reverse Osmosis Membrane

selecting “p” formulations.Market Survey of chemicals & testing

equipments.Study and analyze the characteristics of RO

Membrane.Different plant surveys.Carry out the following tests:

Pressure test of WaterFlux Desalination


Major Tests of Membranes Non-Destructive Tests:1. Bubble test- test physical integrity of the membrane envelope 2. Membrane performance - flux, pressure and percent reject 3. Analysis of cleaning solution

Destructive Tests:1. Internal visual exam2. Coupon testing of membrane surface3. Metals analyses4. Digestion

Organic Analyses:1. FTIR Spectroscopy2. UV Spectroscopy


Desalination Techniques Multi-effect distillation (MED)Multi-stage flash (MSF)Reverse osmosis (RO)Electro dialysis (ED)Capacitive deionization (CDI)Mechanical vapor compression (MVC)


CA membranes will reduce the cost of RO treatment processes

RO processes are used in the production of food and beverages, pharmaceuticals, and chemical products.

a new alternative to many areas where drinking water is in short supply.

RO technologies can make use of use an almost unlimited and reliable water source, the sea.

RO has a negligible environmental impact

RO technologies can be used to remove organic and inorganic contaminants.

Most economical process for salinity reduction associated with secondary effluent (or other wastewater source) TDS levels.


Development of RO Membrane & Its Characterization2003.ppt

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