Flux and Retention Behavior of Superhydrophiliic Loose Nanofiltration Membranes

Nicole Bernstein

Agenda

Purpose Methodology

Membranes

Foulants

Results

Acknowledgements

Membrane technology offers a possibility for the economic purification of natural and industrial water sources

Membrane technology offers a possibility for the economic purification of natural and industrial water sources

The purpose of this study was to study the performance of membranes with high fouling resistance and low NaCl rejection

Sepro NF 6 Sepro NF 2A

MWCO (Da) 847 529

Permeability (L∙m-2∙h-1∙bar-1) at 25 oC 16.65 10.13

Salt rejection (NaCl, %) 7.34 21.23

pH for isoelectric point 5.06 3.78

Three foulants were chosen due to their representativeness of common contaminants from various sources

HUMIC ACID

ALGINIC ACID

BOVINE SERUM ALBUMIN66.5 kDa

10-600 kDa

5-200 kDa

The flux and retention of the membranes were tested in a lab-scale cross flow filtration unit

permeate permeate

pumpfeed

solution

NF6 NF2A

Pretentate retentate

P

6 bar25 oC

The flow rate behavior in the cross flow unit was simulated using COMSOL

The following factors were considered when testing the performance of the membranes

Minimal flux decline with changes in:• Foulant concentration• pH • Ionic strength

123

High retention of organic matter

Low salt retention of NaCl

The increase in foulant concentration resulted in a minimal flux decline

The increase in foulant concentration resulted in a minimal flux decline

Membrane as observed after humic acid trials

Decreasing pH had the most effect on the declining membrane performance

Humic Acid 50 ppm

Decreasing pH had the most effect on the declining membrane performance

The effect of ionic strength was tested with three different salts: NaCl, MgCl2, and CaCl2

Humic Acid 50 ppm

The effect of ionic strength was tested with three different salts: NaCl, MgCl2, and CaCl2

NaCl

MgCl2CaCl2

The retention of humic acid was consistantly high (above 99.3%) for all trials

The expected low NaCl rejection of the membrane was seen at high NaCl concentrations

Further data analysis and comparison with commercial membranes will allow us to better understand the membrane performance

Minimal flux decline with changes in:• Foulant concentration• pH • Ionic strength

123

High retention of organic matter

Low salt retention of NaCl

Acknowledgements

Thank you to Professor Bart Van der Bruggen for the opportunity to travel to K. U. Leuven.

Thank you to Jiuyang Lin for guidance throughout the semester.