Fabrication of thin film composite nanofiltration membranes by coating water soluble disulfonated poly(arylene ether sulfone) and in situ crosslinking

• Water-soluble SPES-NH2-70 was used to fabricate thin film composition NF membrane by in situ crosslinking.
• The performance of PEGDGE crosslinked nanofiltration membranes was better than GA crosslinked membranes.
• PEGDGE crosslinked membrane exhibits a permeate flux of 25.5 ± 3.0 L m−2 h− 1 and Na2SO4 rejection of 96.1 ± 1.1% at 4 bars.
• In fouling study, the PEGDGE crosslinked membrane exhibited excellent antifouling ability for humic acid.

Thin film composite nanofiltration membranes were fabricated by coating a water-soluble disulfonated poly(arylene ether sulfone) which contained pendant amine groups (SPES-NH2) onto a polysulfone support in conjunction with covalent crosslinking. Two different crosslinkers, glutaric dialdehyde (GA) and poly(ethylene glycol) diglycidyl ether (PEGDGE), were utilized with various concentrations and curing temperatures to optimize the performance of the resulting membranes. Both GA and PEGDGE crosslinked membranes exhibited optimal performance with a 1 wt.% polymer concentration and 90 °C curing temperature. In particular, the optimized PEGDGE crosslinked membranes exhibited a higher permeation flux of 25.5 ± 3.0 L m−2 h− 1 while that of the GA crosslinked membranes was 8.9 ± 3.2 L m−2 h− 1; each membrane exhibited similar levels of Na2SO4 rejection at 96.1 ± 1.1% and 96.6 ± 2.1%, respectively, at 4 bars. The higher flux for the PEGDGE crosslinked membranes was attributed to higher hydrophilicity. Furthermore, the rejection of methyl orange and methyl violet was above 99.9% for both the GA and PEGDGE crosslinked membranes. A fouling study of the PEGDGE crosslinked membrane was carried out using humic acid as a model foulant, and the membranes exhibited excellent antifouling ability, attributed to their high hydrophilicities and strongly anionic characteristics.

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