Preparation And Filtration Properties Of ZrO₂/PVDF And TiO₂ /PVDF Hybrid Membranes

Polyvinylidene fluoride （PVDF） is a kind of conventional organic membrane material with excellent properties, but its strong hydrophobicity limits its wide application in water treatment. To improve the hydrophilicity of PVDF membranes is challenging. In this study, a series of hybrid membranes were prepared by mixing the ZrO₂ and TiO₂ nanoparticles into PVDF polymer matrix via the phase-inversion process.The effects of preparation conditions on the strcuctures and filtration properties of PVDF hybrid membranes were studied. Besides, the stuctures and properties of PVDF hybrid membranes were characterized by several modern instrumental analysis techniques.In this thesis, the experimental results showed that H3PO4 was a good additive in PVDF/TEP system with the better dispersion for ZrO₂ and TiO₂. Removal rate of BSA（67000 Da） with PVDF was 11.5%, removal rate of BSA ZrO₂/PVDF and TiO₂/PVDF reached 60.5% and 72.2%, respectively. The anti-fouling capability also were improved by adding proper amount of ZrO₂ and TiO₂ into the PVDF matrix. Flux reduction coefficient after filtrating BSA reduced 10% compared to pure PVDF membrane.Adding TiO₂ colloidal particle into PVDF matrix could form steady casting solution .The pore size became smaller, and removal rate of BSA with hybrid membranes increased. TiO₂/PVDF hybrid membranes with 4%～5% TiO₂ colloidal particle had good BSA removal and anti-fouling capability. The removal rate of BSA greater than 98% and flux reduction coefficient less than 30%.ZrO₂ , TiO₂ and TiO₂ colloidal particles had important effect on the structures of PVDF membranes. SEM images showed that ZrO₂ and TiO₂ particles existed in hybrid membranes; X-ray diffraction showed that ZrO₂ and TiO₂ particles decreased crystallinity of PVDF mambrane; TGA analysis reflected that PVDF membrane had good thermal stability.Adding ZrO₂ , TiO₂ and TiO₂ colloidal particle could improve the hydrophilic performance and mechanical property of PVDFmembrane. The contact angle of PVDF membrenes were reduced by 4.7°,4.2°and 13.5°, respectively; and meanwhile the maximum mechanical load were increased up to 1.1, 1.3and 1.8 times respectively.The hybrid membranes were tested for removal of two typical EDCs ,i.e.,BPA and DEP. The results showed that removal rate of BPA of ZrO₂/PVDF membrane reached above 90%. PVDF and hybrid membranes were used to treat source water. TiO₂/PVDF membrene with TiO₂ colloidal particles showed the best performance of anti-fouling property, and its removal rate of TOC and UV₂₅₄ were 23.2% and 57.6%.It is found that all there PVDF membranes showed high removal rate of oil from Oil-in-Water Emulsions, i.e., 90%. The flux reduction coefficient was less than 10% after filtration running for 40 min, which indicated that anti-fouling property of the membrane was significantly improved.