Preparation Of Hydrophilized Polyvinylidene Fluoride Membrane-supported NZVI For Cr(?) Removal

In this study,the PVDF·Al₂O₃ blend films were doped with doubine by adding nano-alumina during the preparation of PVDF films and and using dopamine to form polydopamine by self-polymerization.PDA/PVDF·Al₂O₃ films were prepared by surface coating and successfully loaded with NZ? on the films to obtain PDA/PVDF·Al₂O₃-Fe⁰ composites.In the process of polydopamine oxidation,dopamine can show adhesion on the membrane substrate and have hydrophilic functional groups on the surface.Afterwards,a series of characterizations and tests were performed on the prepared PDA/PVDF·Al₂O₃-Fe⁰ composites,and the PDA/PVDF·Al₂O₃-Fe⁰ composites were subjected to Cr???removal experiments.PDA/PVDF·Al₂O₃ was analyzed.Cr???removal kinetics and removal mechanism of Fe⁰ composites.The details are as follows:?1?Scanning electron microscopy?SEM?,Fourier transform infrared spectroscopy?FT-IR?and X-ray photoelectron spectroscopy?XPS?detection of PDA/PVDF·Al₂O₃-Fe⁰ composites showed that nano-Al₂O₃ was successfully added on the PVDF film,dopamine was successfully applied to the PVDF·Al₂O₃ blend membrane to form a coating.The modified PDA/PVDF·Al₂O₃ film has the advantages of large film pores and uniform distribution,and the NZ? was successfully fixed on PDA/PVDF·Al₂O₃ film to make a PDA/PVDF·Al₂O₃-Fe⁰composite.The NZ? has good dispersibility on the film surface,which solves the problem that NZ? is prone to agglomeration,and it can be seen that the amount of iron on the film in the PDA/PVDF·Al₂O₃-Fe⁰ composite material is more.?2?Optimize the time and temperature required for surface coating of the doped amine buffer solution on the PVDF·Al₂O₃ blend membrane by experiments.The results show that the optimal conditions for the doping of the dopamine surface with the PVDF·Al₂O₃ blend membrane are 12 h and 308 K.The mechanism of NZ? loading and immobilization by PVDF·Al₂O₃ blend membrane modified by dopamine was studied.?3?Removal experiments of Cr???in water by PDA/PVDF·Al₂O₃-Fe⁰composites and regeneration experiments were test.The results showed that the removal efficiency of Cr???was 99%by PDA/PVDF·Al₂O₃-Fe⁰ composites.The removal efficiency of Cr???by PDA/PVDF·Al₂O₃-Fe⁰ composites after regenerations was still high.The initial conditions of Cr???concentration,solution pH and solution temperature were investigated to optimize the removal of Cr???by PDA/PVDF·Al₂O₃-Fe⁰ composites.The results showed that the lower initial concentration of Cr???,solution pH and higher solution temperature are beneficial to the removal of Cr???by PDA/PVDF·Al₂O₃-Fe⁰ composites.?4?The reaction kinetics of Cr???removal from PDA/PVDF·Al₂O₃-Fe⁰composites was studied.The first-order kinetic model was used to fit the experimental data and the matching degree was high.The mechanism of Cr???removal by PDA/PVDF·Al₂O₃-Fe⁰ composites was discussed.The NZ? on the membrane activates water molecules and oxygen molecules.The molecule produces active species and further reduces Cr???.