Carboxylated polyarylene ether nitrile modified polysulfone membrane with enhanced anti-fouling for oily water separation and hexavalent chromium removal

Design of hydrophilic surface-modified polysulfone (PSF) non-solvent induced phase separation (NIPS) ultrafiltration membranes through introducing appropriate additives for oil/water separation has long been expected to address notorious fouling concerns caused by adhesion of oil droplets, thereby improving separation performance. However, most reported hydrophilic PSF membranes suffer from tedious preparation processes, limited stability and durability, and lack versatility in treating other industrial pollutants like poisonous Cr (VI) ions. Herein, we have delicately designed a type of polyarylene ether copolymers containing pendent groups of carboxyl and nitrile (abbreviated as bcPEN) that have good compatibility with PSF but showing improved hydrophilicity. Due to their unique features, the synthesized bcPEN have been employed as the regulator to modulate the NIPS behaviors of PSF, which obviously enhances the separation and anti-fouling performance of PSF ultrafiltration membrane. Specifically, the oil-in-water emulsion flux of PSF membrane can be improved from 9.44 to 184.58 L·m⁻²·h⁻¹ after modification with bcPEN, and remains stable after repeated oily water separation. More interestingly, the modified membrane allows adsorption removal of hazardous Cr(VI) via its surface active carboxyl and cyano groups, and reaches a maximum adsorption capacity of 97.75 mg/g. Basically, the current work opens a new way for design of multifunctional anti-fouling PSF ultrafiltration membranes for oily water separation.