Study On Composite Photocatalytic Reactors With Enhanced Transfer For Restoring Wastewater

Titanium （IV） dioxide （TiO₂） photocatalyst has been drawn much attentionbecause of its high photccatalytic activity, low cost, chemical/photocorrosion stabilityand nontoxicity. In the process of restoring wastewater, TiO₂photocatalysts typicallyface heavy aggregation, troublesome recycle and secondary pollution. These problemscan be overcome by coating inorganic layer on TiO₂surface, especially SiO₂shell, tofabricate TiO₂/SiO₂core-shell composites and then doping to polymeric supporters.However, it is ignored that the effect of the structure of SiO₂shell and the porestructure （the size, regularity and alignment） on the light transmittance, the masstransfer of organic reactants and products as well as the active sites of TiO₂.Undoubtedly, these factors not only have a vital role in the photocatalytic activity, butalso become a barrier for the development of immobilizing TiO₂by polymericsupporters. Therefore, it is important to avoid the damage of polymeric supporterstogether with enhance the mass transfer and light transmittance in the process ofsmoothly recovering TiO₂photocatalysts.In this study, the ordered SiO₂/void/TiO₂photocatalytic composites withnanovoid structure and the mesopores aligned perpendicular to inner TiO₂particles,denoted as SVT, were fabricated by the synergistic effect of nonionic surfactant（EO）20（PO）70（EO）20（P123）, oleic acid （CH3（CH2）7CH=CH（CH2）7COOH） and TEOS.Then composite photocatalytic reactors, denoted as SVTP, were obtained by dopingthe resultant SVT to apparent polycarbonate （PC）. The morphology of SVT and thepore microstructure of SiO₂shell were characterized by FT-IR, SEM, TEM, smallXRD and BET, and the results present that SVT is well-developed spherical withordered mesopore channels （approximately3nm in diameter） in SiO₂shell, and thespecific surface area of SVT is532.5m2g-1. Besides, the structure of SVTP wasanalyzed by SEM and FT-IR and the results demonstrate SVT has been successfullydoped to transparent PC. Moreover, the synthetic conditions of SVT and SVTP wereoptimized and confirmed, and the photocatalytic activities of SVT and SVTP werestudied by decomposing15mg L-1of methyl orange solution.Also, the mechanism of photocatalytic reaction, the mass transfer of reactantsand products, and the process of light transport are revealed via investigating the components, microstructure, and pore surface/interfacial properties of SVT and SVTP.These researches will provide a useful exploration for avoiding the damage of organicsupporters and guaranteeing the good mass transfer, light transmittance andphotocatalytic activity, when TiO₂photocatalysts are immobilized to polymericsupporters.