Surface modification of porous polyvinylidene fluoride hollow fiber membrane by sulfonated poly(ether ether ketone) coating for membrane distillation of oily wastewater

Abstract

AbstractHighly porous polyvinylidene fluoride hollow fiber membranes were fabricated by a non‐solvent induced phase separation process. The membranes were modified by coating an ultra‐thin hydrophilic layer of sulfonated poly(ether ether ketone) (sPEEK) onto the inner surface. An industrial oily wastewater treatment was performed through an air gap membrane distillation (AGMD) process. From field emission scanning electron microscopy, the modified membrane showed an open structure with a large finger‐like outer layer and sponge‐like inner layer. The thickness of the coated sPEEK layer on the inner surface was about 0.5 μm. The coated membrane presented mean pore size of 36 nm and overall porosity of 73%. The inner surface water contact angle decreased from about 82° to 57°. Using Langmuir adsorption experiment, minor oil adsorption on the modified membrane surface was confirmed. A stable water flux of about 12 kg m−2 h−1 and oil rejection of 99% were found during 72 h of the AGMD process for treating the oily wastewater of NGL‐900 (Gachsaran, Iran) plant. The high flux recovery ratio of about 98% was related to the improved anti‐oil‐fouling property. The modified membrane can be a potential candidate for oily wastewater treatment through the MD processes.