Performance of PVDF/Multi-nanoparticles composite hollow fibre ultrafiltration membranes

Polyvinylidene fluoride (PVDF)/multi-nanoparticles composite hollow fibre ultrafiltration (UF) membranes were prepared with different compositions of SiO2/TiO2/Al2O3 nanoparticles in PVDF/DMAc/NMP solution by wet-spinning method. Behaviour of nanoparticles on membrane dopes were evaluated by the viscosity and surface tension. By adding nanoparticles, obviously the membrane dope viscosity increased; however, the surface tension of each membrane dope changed inconsistently. The hollow fibre membranes were characterized by SEM, mechanical testing, TGA, permeability and rejection test, porosity measurement and pore size distribution. The test results indicate that different nanoparticles and their related compositions induce different characteristics on membrane morphology, mechanical property, thermal stability, permeation property, as well as porosity and pore size distribution, due to the different particle characteristic, the combination effect and the size effect. For membranes with PVDFM2 (18 wt% PVDF, 1 wt% TiO2 (P25), 1 wt% SiO2 and 1 wt% Al2O 3) dope and PVDFM5 (18 wt% PVDF, 2 wt% TiO2 (P25) and 1 wt% Al2O3), the pure water permeation flux and bovine serum albumin rejection reach 179 L.m-2.h-1.bar-1 and 98.9%, 352 L.m-2.h-1.bar-1 and 89.1%, respectively; while their mean efficient pore sizes are 10.1 nm and 11.0 nm, and both membranes present narrow pore size distribution and other good performances.