PVDF Microfiltration Membrane Surface Modified By PVP/Ag/TiO₂ And Study Of PVA/Ag/AgCl Photocatalysis

In this paperthe, PVDF business microfiltration membrane surface was hydrophilic modificated by ammonium persulfate(APS) and povidone(PVP-K30), and then Ag and TiO2 particles are sedimented on it. Then performances and structures of PVDF/PVP/Ag, PVDF/APS/Ag and PVDF/PVP/TiO2 are characterized. Besides, PVA/Ag/AgCl catalyst was preparaed to optimized the Mo degradation, and it was analysed by structure characterization.Firstly, PVDF/PVP modified membrane was prepared by immersing PVDF microfiltration membrane in PVP solution with hydrochloric acid, and PVDF/APS modified membrane was prepared by immersing PVDF membrane in APS solution after defluorization. The water flux of PVDF/PVP modified membrane increases, and antifouling property was discussed through BSA solution filtration tests, where the flux recovery ratio was significantly increased from 70.0% for PVDF membrane to 93% for PVDF/PVP modified membrane. Water contact angle of membrane surface was decreased from 130° for PVDF membrane to 57° for PVDF/PVP modified membrane, which results in the improvement of surface hydrophilicity. The pore size and distribution of PVDF/PVP modified membrane become small. Besides, the property of PVDF/APS modified membrane has been improved too, but the mechanical property decreases dramatically.Secondly, IR analysis shows that C=O group generated on the PVDF/PVP and PVDF/APS modified membrane, and it can help to combine with Ag particle through heating treatment. The research has found that The water flux of PVDF/PVP/Ag modified membrane increases, and antifouling property was discussed through BSA solution filtration tests, where the flux recovery ratio was significantly increased from 70% for PVDF membrane to 96% for PVDF/PVP/Ag modified membrane. Water contact angle of membrane surface was decreased from 130° for PVDF membrane to 0° for PVDF/PVP/Ag modified membrane, which results in the improvement of surface hydrophilicity. SEM result proves that Ag particles are on the surface of PVDF/PVP/Ag modified membrane.Thirdly, it has been found the aging time of TiO2 hydrosol can be decreased rapidly through heating treatment. As the increasing of heating time, TiO2 particle size and photocatalytic performance increase. PVDF/PVP/TiO2 modified membrane was made by immersing PVDF/PVP modified membrane in TiO2 hydrosol with heating treatment. With the increase of TiO2 sol ratio, there are more TiO2 particles on the surface of PVDF/PVP/TiO2 modified membrane. The water flux of PVDF/PVP/TiO2 modified membrane increases, and antifouling property was discussed through BSA solution filtration tests, where the flux recovery ratio was significantly increased from 70% for PVDF membrane to 89% for PVDF/PVP/TiO2 modified membrane. Water contact angle of membrane surface was decreased from 130° for PVDF membrane to 26° for PVDF/PVP/TiO2 modified membrane, which results in the improvement of surface hydrophilicity. SEM results prove that TiO2 particles are on the surface of PVDF/PVP/Ag modified membrane. PVDF/PVP/TiO2 modified membrane has a good photocatalytic degradation of MO, and the repeatability is very good. SEM result shows that there are a layer of TiO2 nanoparticles on the surface of PVDF/PVP/Ag modified membrane.Finally, the PVA/Ag/AgC1 photocatalysis was prepared by suspension polymerization, and the photocatalytic degradation repeatability of MO has been improved. As the increasing of the HC1 content, its photocatalytic degradation of methyl orange increases and then decreases by changing the HC1 content in crosslinking agent. In the photocatalytic reaction process, the existence of H+ and Cl- can make the PVA/Ag/AgCl spheres have high MO degradation. XPS and EDX images revealed that AgCl NPs were mainly buried inside PVA matrix and their sizes were about 50-90nm.