Studies on Nonwoven Fabric Reinforced PVDF/GE Oil-absorptive Composite Membrane

Nonwoven fabric reinforced poly (vinylidene fluoride) (PVDF)/graphene (GE) oil-absorptive composite membrane (NR-PGM) was prepared by a coating method. NR-PGM consisted of PVDF/GE separation layer and polyethylene terephthalate-polyamide nonwoven fabric matrix layer. Nonwoven fabric was pretreated by NaOH solution for better interface bonding, and PVDF/GE separation layer was obtained by non solvent induced phase separation (NIPS) method with PVDF as the polymer matrix, hydrophobic SiO2 and GE as additives, dioctyl phthalate (DOP) as the pore-forming agent, and dimethylacetamide (DMAc) as the solvent. Membrane characterization was conducted through SEM, water contact angle and oil contact angle, pore diameter distribution, mechanical strength, water entry pressure, oil flux and flux recovery rate. The results indicated that the NR-PGM exhibited hydrophobicity and superoleophilicity. SEM images indicated that the dense microvoids were uniformly distributed on the top surface of separation layer, and the cross section of separation layer had an asymmetrical structure that consisted of finger-like pore structures on the top and sponge-like pore structures on the buttom. Moreover, the average pore diameter was about 340 nm, water contact angle was up to 95. 4 degrees and oil contact angle was nearly 0 degrees, water entery pressure was up to 0. 14 MPa, and the kerosene and diesel oil flux reached 118. 22 and 218. 25 L/m(2)h. NR-PGM was competent for continuous oil/water separation through vacuum pressure. At first, the oil/water separation efficiency was nearly 97%. After being used for 10 times, the oil/water separation efficiency remained about 95%