Enhanced antifouling durability of zwitterionic polymer brush grafted ceramic membrane for sustainable oil/water separation applications

The development of superior antifouling membranes with high-flux and durable oil/water separation performance is an urgent need for the treatment of massive oily wastewater. This work reports a novel strategy and mechanism of enhancing the antifouling durability of poly(sulfobetaine methacrylate) (pSB) brush grafted commercial alumina ceramic membrane (CM/pSB). The grafting density is controlled by the surface content of ester bonded alpha-bromoisobutyryl bromide (BiBB) and the pSB is grafted by a facile surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (SI-ARGET-ATRP). High-density of the pSB brushes forms a closely covered hydration layer barrier on the membrane surface to suppress the acid/base catalyzed hydrolysis of the ester linkage anchored pSB brushes, as well as effectively prevent the adhesion of oil droplets during long-term oil/water filtration separation. The superior antifouling property of the optimized CM/ pSB membrane was demonstrated by a nearly zero decline in filtration flux for separating a 30 % crude oil/water mixture, as well as over 98 % resistance to protein adsorption and bacterial adhesion. Furthermore, the membrane filtration flux reached over 700 L & sdot;m- 2 & sdot;h- 1 & sdot;bar- 1 for separating of surfactant-stabilized oil-in-water emulsions with flux recovery ratio high to 99.8 % and oil rejection ratio over 98 %. More importantly, the brush stability in pH 2 and pH 12 solutions was increased by 15 and 8 times, respectively, which enables high flux separation of various oily wastewater for 8 years. These significant advances pave a way for highly efficient and sustainable treatment of massive oily wastewater.