Study On Channels Regulation Of Porous Zr-SVT （Zr-doped SiO₂Shell/void/TiO₂Core Particles）/PVDF Photocatalytic Films

In order to solve the problem of immobilizing TiO2without decreasing of itsphotocatalytic rate obviously, the paper research content is shown as follows: firstly,the nanoscale spherical TiO2particles were prepared under the effect of NaCl aqueoussolution controlling the the hydrolysis rate of TBT in the absolute ethanol. Secondly,the hydrophobic TiO2/OA particles were obtained through the dehydrationcondensation between COOH-of oleic acid and OH-of TiO2particles. And then, withthe non-ionic surfactant P123((EO)20(PO)70(EO)20) as the template agent andxylene as expansion agent, Zr-doped porous SiO2core were formed on the surface ofTiO2with void through the cohydrolysis of TEOS and ZrOCl28H2O, namely porousZr-SiO2/void/TiO2particles (Zr-SVT). Last, With acetone as solvent, dimethylcarbonate as a pore agent, PVDF as polymer, Zr-SVT for adding inorganic particles,the highly transparent composite photocatalytic membrane (CPFS) were obtained by aspecific method of membrane, which can strengthen the mass and light transmission.The TiO2and Zr-SVT particles were characterized by FT-IR, SEM、TEM and BET.The results show that TiO2and Zr-SVT particles are spherical, and the shells ofZr-SVT are porous structure with Zr element doped, which can improve thetransmission of light and mass. The characterization of CPFs was got by FT-IR andSEM. The results show that Zr-SVT were successfully embedded in the polymer films,and the surface and cross-section of CPFs have many channels which can guaranteethe organic pollutant diffuse to the surface of TiO2, ensuring a better performance forCPFs to photograding organic pollutant. And at the same time, CPFs were used andrecycled to degrade and purify the methyl orange solution (15mgL-1). The degradationrate of the first, fifthth and tenth time is50.66%,47.48%and44.87%, respectivelyafter120min of photodegradating the methyl orange. Compared to the first time, thedegradation rate of the fifth and tenth time decreases by3.18%and5.79%,respectively, indicating that the photocatalytic rate of CPFs declines slightly with therecycle numbers increase. The reason that the photocatalytic rate of CPFs declinesslightly with the recycle numbers increase is that there are a few impurities and oilresidues in the channels of CPFs, which block the transmission of oil in the channelsof CPFs. Therefore, the used CPFs should be cleaned many times with oxalic acid,sodium hydroxide solution or with ultrasound to remove oil residues and impurities in CPFs to recover the photocatalytic performance of CPFs. The cleaning method whichcombined the alkali solution and the ultrasonic is the best. Therefore, CPFs as a novelTiO2-immobilized structure will have a promising application in the recovery of TiO2catalyst with better photacatalytic performance for sewage treatment.In addition, the preparation process of particles and CPFs was discussed andanalyzed. The theory of adding xylene, Zr element and mass transmission were alsoresearched, which is helpful to prepare a novel material to immobilize and recover theTiO2photocatalyst with better photocatalytic performance.