Preparation of re-entrant and anti-fouling PVDF composite membrane with omniphobicity for membrane distillation

Publication date: Available online 19 October 2019Source: Journal of Membrane ScienceAuthor(s): Wei Zhang, Yubing Lu, Jun Liu, Xipeng Li, Baoan Li, Shichang WangAbstractSuperhydrophobic and oleophobic membrane applied in membrane distillation was fabricated by constructing a re-entrant composite structure via immobilizing silica nanoparticles (NPs) on the polyvinylidene fluoride (PVDF) membrane. The silica coated membrane with the assistance of polydopamine (PDA) was then fluorosilanized by means of a silane coupling agent 1H,1H,2H,2H-perfluorooctyltrichlorosilane. A series of characterizations were implemented to investigate the effects of modification process on the structure and performance of the PVDF composite membranes. The fouling and wetting behaviors of original and modified membranes were explored by direct contact membrane distillation (DCMD) tests using a mixed solution of inorganic salts, organic matter and surfactant as the feed. The results indicated that silica NPs and fluorinated silane were presented on the PVDF membrane substrate. After surface modification, the liquid entry pressure (LEP) increased by 120%, in addition, the water contact angle (WCA) increased from 127.0° to 169.0°, and the oil contact angle (OCA) increased from 2.8° to 112.1°. The modification process showed no effect on the pore size and pore structure. Furthermore, the composite membrane exhibited excellent chemical stability and prominent mechanical stability. The re-entrant structu...
Source: Journal of Membrane Science - Category: Materials Science Source Type: research