POLYELECTROLYTE MULTILAYER MEMBRANES FOR MICROPOLLUTANT/SALT SEPARATIONS

Date

2026-1-20

Author

GERTANI, RAFID SALAH JASIM

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Polyelectrolyte multilayer membranes (PEMMs) are increasingly recognized as promising technologies for micropollutant removal from water. This study examines their capacity to concentrate micropollutants from the trace concentrations they occur in water. Flat-sheet and hollow fiber supports were fabricated from polyethersulfone (PES) and sulfonated PES using phase inversion. These supports were subsequently coated via layer-by-layer assembly of oppositely charged polyelectrolytes, Poly-(diallyldimethylammonium chloride) (PDADMAC)/ poly(4-styrene sulfonate) (PSS) (L1) and poly(allylamine hydrochloride) (PAH)/PSS (L2), with additional modifications including a branched polyethyleneimine (BPEI) primer layer and glutaraldehyde cross-linking. The influence of support type, polyelectrolyte pair, and multilayer modification on their performance was systematically evaluated. Hollow fiber PEMMs formed denser selective layers than flat-sheets, resulting in lower molecular weight cut-off (MWCO) and improved nanofiltration performance. L2 multilayer membranes exhibited higher resistance and lower MWCO values (440-580 Da for flat-sheets; 390-400 Da for hollow fibers) than L1 multilayer membranes due to the higher charge density of PAH. BPEI and cross-linking modifications further enhanced layer density. Among the tested micropollutants, indomethacin sodium (INDO) had the highest rejection primarily due to its higher molecular weight. Flat-sheet L2 membranes had 98% INDO rejection without any modification, while hollow fiber L2 membranes had 98% INDO rejection after the BPEI and cross-linking modifications. INDO concentrating tests were done with a selected membrane with high INDO rejection (98%), acceptable salts rejections (Na2SO4: 50%, MgCl2: 86%, MgSO4: 83%), and reproducible production, where 84-fold INDO concentration factor was achieved, demonstrating the strong potential of PEMM membranes for micropollutant concentration.

Subject Keywords

Polyelectrolyte, Multi-layer, Membrane, Micropollutants, Salts

URI

https://hdl.handle.net/11511/118465

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Graduate School of Natural and Applied Sciences, Thesis