摘要

In this study, poly(vinylidene fluoride) (PVDF) dual-layer hollow-fiber UF membranes were prepared via phase inversion in one step. Laboratory-synthesized amphiphilic poly(vinylidene fluoride)-g-poly(ethylene glycol) methyl ether methacrylate (PVDF-g-POEM) was incorporated as a hydrophilic modifier of the outer layer by blending. The effects of the dope formulation and membrane formation conditions on membrane structure and UF performance were investigated. The parameters investigated included the PVDF-g-POEM loading in the outer layer, the PEG additive content in the outer layer, the external coagulant composition, and the polymer concentration in the inner layer. The effects of adding PVDF-g-POEM and PEG were found to depend on the external coagulant composition; when a water/ethanol mixture was used as coagulant, the fibers formed in the presence of PEG exhibited larger pores, as confirmed by both SEM characterization and a solute rejection method. The porosity of the inner layer was observed to increase with decreasing inner-layer dope concentration and upon weakening the external coagulant. A more porous inner layer led to a higher transmembrane pure water flux. An antifouling test confirmed that both membrane hydrophobicity and surface pore size affected the membrane fouling pattern and the final FRR. The highest FRR of 83.3% was obtained with the hollow fiber M5A, which was characterized by a compact surface and contained PVDF-g-POEM in its polymer matrix.