Investigation On Polyvinylidene Fluoride Hybrid Membranes Filled With Porous Y_xFe_yZr_1-x-yO₂ Coated TiO₂ Solid Superacid

Polyvinylidene fluoride?PVDF? is an ideal membrane material and has been widely used in the further treatment of wastewater containing oil due to its stable physical and chemical properties, good flexibility and easy modification. However, PVDF membranes are not only vulnerable to be contaminated by oil, but also easy to be compacted when treating with wastewater containing oil. These defects result in a dramatic loss of membrane permeation flux and seriously hamper the widespread application of membrane technology. Therefore, it is necessary to improve the hydrophilicity, anti- fouling and anti-compaction properties of PVDF membranes by modifying them.In this paper, porous Y_xFe_yZr_1-x-yO₂ coated TiO₂ solid superacid?SYFZr- Ti? were prepared by preparation of TiO₂ core, coating of Y_xFe_yZr_1-x-yO₂ and sulfation. The diameter of SYFZr- Ti and the thickness of the ZrO₂ shell are roughly 400 nm and 50 nm, respectively. The ZrO₂ shell shows a porous structure, and the acidity of SYFZr- Ti is-16.468. Then SYFZr- Ti modified by SDBS were dopped into PVDF to prepare SYFZr-Ti/PVDF hybrid membranes with micro reaction locations?MRLs?. The appropriate mass ratio of SYFZr- Ti: PVDF is 20: 100?g: g?. SYFZr-Ti are uniformly dispersed inside SYFZr- Ti /PVDF composite membranes and interact with PVDF chains by hydrogen bonds. SYFZr- Ti/PVDF hybrid membranes show good hydrophilicity, anti- fouling and anti-compaction properties.Self-assembled membranes were prepared by assembling functional siliceous materials on surface of siliceous materials and used for pretreating wastewater containing oil. Functional siliceous materials were synthesized by silanization of siliceous materials and coating Al₂O₃. The appropriate material ratios in the preparation process of functional siliceous materials are:?KH550?: n?SiO2?=0.42: 1?mol: mol? and n?Al₂O₃?: n?SiO2?=0.36: 1?mol: mol?. When self-assembled membranes treat wastewater containing oil? COD: 298 mg/L, SS: 78 mg/L, turbidity: 2.1 NTU, oil concentration: 96 mg/L?, the appropriate thickness of functional siliceous materials is 0.20 mm, cyclic operation times is 80, and water quality of wastewater containing oil after treated is: COD: 51 mg/L, SS: 17 mg/L, turbidity: 0.38 NTU, oil concentration: 23.06 mg/L.SYFZr- Ti/PVDF hybrid membranes were used for treating wastewater containing oil pretreated by self-assembled membranes. The water quality of wastewater containing oil treated by SYFZr- Ti/PVDF hybrid membranes is: COD: 51 mg/L, SS: 17 mg/L, turbidity: 0.38 NTU, oil concentration: 23.06 mg/L under the conditions of wastewater temperature 25 °C and trans- membrane operation pressure 0.15 MPa, which meets A3 level standard of clastic rock reservoir water flooding and first level of Tianjin municipal sewage comprehensive discharge. SYFZr-Ti/PVDF hybrid mambranes can degrade part of organic pollutants and inorganic pollutants. The fluxes recovery effect of SYFZr- Ti/PVDF hybrid membranes is good after treated by physical and chemical cleaning. Finally, MRLs formation mechanism of SYFZr- Ti/PVDF composite membranes was studied in this paper.