The Preparation Of Tio2 Membrane Material And Its Photocatalytic Degradation Of Organic Pollutants

The modern industry has had a negative impact on the environment with rapiddevelopment. Three wastes （waste water, exhaust gas and solid waste） from industrygradually deteriorated our environment. The organic pollution is one of the mostimportant global environment pollution. The intermediates generated from the organicpollution in the environment have strong carcinogenic, teratogenic and mutageniceffects on human, which are accompanied by with potential environmental risks. Thephotocatalytic oxidation applied to the degradation and mineralization of organicpollutants is an important aspect of photocatalytic environmental applications. Thesemiconductor photocatalytic technology can be applied to degrade many toxicorganic compounds. Meanwhile, it has broad application for some advantages such asenvironmentally friendly, clean energy, mild reaction conditions and low cost. As themost promising photocatalyst, TiO₂is expected to play an important role in helpingsolve many serious environmental and pollution challenges. TiO₂can oxide about3000kinds of organic pollutions to CO₂, H₂O and other inorganic compounds. TiO₂has attracted lots of interests over the past decades owing to its specialphysiochemical properties such as chemical stability, nontoxicity, direct utilization ofsolar energy and cheapness. However, the main drawbacks of TiO₂photocatalysts arelow efficiency, wide band gap （can only be excited by ultraviolet light） and difficultyin reuse for powder. To solve the practical problems, we carried out the research workfor three aspects involved immobilization, modification and morphology. The effectof morphology and relationship to photocatalytic performance were explored. Thedetail works are as follows:1、 Ionic liquid-assisted synthesis of titania films consisted of flower-likemicrospheres via soft solution routeIn this study, anatase titania films consisted of flowerlike spherical aggregateswere synthesized simply through the reaction of metallic Ti plates and hydrogenperoxide solution containing1-Butyl-3-methylimidazolium tetrafluoroborate（[Bmim]BF4）. The as-prepared samples were characterized by TG, XPS, XRD, FESEM, UV-vis DRS and BET. Photocatalytic activities of titania films towardsdecomposition of rhodamine B （RhB） in water under UV light （310nm，8W） wereevaluated. We have proved that the titania film showed high activity and excellentstability.2、In-situ synthesis of ordered macroporous Bi/TiO₂film.The ordered macroporous Bi/TiO₂films were in-situ prepared by dipping thecolloidal crystal templates into Bi-Ti precursor sol. The sol precursors doped withdifferent Bi content were prepared to fabricate the films. The photocatalyticdegradation of methylene blue was selected as a probe reaction to evaluate thereaction efficiency under visible light irridiations. The effect of Bi content,morphology and thickness was explored. The as-prepared samples were characterizedby TEM, FESEM, XRD, DRS, BET and PL. The results showed that Bi-dopingordered macroporous films have good performance in the photocatalytic degradationof methylene blue under visible light irradiations. The doping of Bi led to lowerrecombination of photo-induced electrons and holes. The ordered macroporous filmshowed better photocatalytic performance than the film prepared by dip-coatingmethod without template.3、Ion-exchange route to synthesis of ordered macroporous CdS/TiO₂film.CdS was introduced to modify TiO₂and get complex substance of CdO/TiO₂film after calcinations by adding Cd2+into the sol. The ordered macropotousCdS/TiO₂film was prepared thorough ion-exchange approach. The macropous filmhad high surface area which was beneficial to the photoactivity. The introduction ofCdS extended the photoresponse to the visible-light region and the films showedbetter visible-light activities in the degradation of chlorophenol and rhodamine B.