Green Preparation of a Carboxymethyl Cellulose-Coated Membrane for Highly Efficient Separation of Crude Oil-In-Water Emulsions

Developing high-performance membranes is anextremely significant strategy to combat increasing severe oilpollution. However, most of the previously reported superwettablemembranes have been inevitably involved with the use of toxicsolvents and complicated preparation processes. In addition, mostof them lacked the capacity of separating crude oil-in-wateremulsions. Herein, a facile and green strategy is employed tofabricate a polytetrafluoroethylene (PTFE) membrane with amixed suspension of PDA@ZIF-8 and carboxymethyl cellulose(CMC) using water as a solvent via the vacuumfiltration method.Combining hydrophilic property with micro-nano-roughness, theCMC-PDA@ZIF-8-coated PTFE membrane (CPZP membrane)exhibits excellent underwater superoleophobicity. More importantly, the separation efficiency of various surfactant-stabilized oil-in-water emulsions including crude oil/water emulsion is higher than 99.2% with aflux up to 1306.5 L m-2h-1, and the separationperformance remains nearly the same after 10 cycles. Moreover, outstanding underwater superoleophobic and self-cleaningproperties are maintained after long-distance sandpaper abrasion and multiple bending tests. Meanwhile, its exceptional separationperformance is still maintained in harsh environments (3.5 wt % NaCl, 1 M HCl, 60 degrees C hot water) even after immersing it for 24 h.Therefore, this green-prepared and high-performance membrane has tremendous application prospects in treating oily wastewater.