Photocatalytic Removal Of Bromate With Noble Metal-modified Titanium Dioxide

In order to improve the efficiency of photocatalytic removal of bromate with TiO₂,a DBP in drinking water, the systematic research about the photocatalytic removal ofbromate with noble metal-modified TiO₂was done. The objective was to enhance therate of photocatalytic removal of bromate and to promote wider use of thephotocatalytic technology in drinking water treatment fields.First, the catalyst screening of noble metal-modified TiO₂was studyed. TiO₂modified with noble metal, including Pt, Pd, Ru, Rh, Ir, Au and Ag, were prepared byimpregnation method. The catalysts were characterized by UV-Vis spectra and XPS.The catalytic activity was tested via the bromate removal under UV irradiation. Theresults showed that the photocatalytic activity for bromte removal was improved by Ptand Ag of high loading and inhibite by Pd, Ru, Rh, Ir, Au, Ag of low loading.Second, the photocatalytic removal of bromate with Pt/TiO₂was researched underUV irradiation. It contained the kinetics of photocatalytic reaction and the effects of Ptloading, calcination temperature, pH, dissolved oxygen, ethanol of organic matter andvisible light to the photocatalytic activity for bromate removal. Results showed that theoptimal preparation conditions of Pt/TiO₂included Pt loading of0.01%and calcinationtemperature of400℃. Low pH significantly improved the photocatalyitc activity forbromate removal. DO seriously inhibitted the photocatalytc activity for bromateremoval. Ethanol slightly inhibited the photocatalytic activity for bromate removal.1.0%Pt/TiO₂had better photocatalytic activity for bromate removal under visible light.The kinetics of photocatalytic removal of bromate followed the first-order kineticequation, the kinetic constant was0.03min^-1.Third, the photocatalytic removal of bromate with Ag/TiO₂was researched underUV irradiation. It contained the kinetics of photocatalytic reaction and the effects of Agloading, calcination temperature, pH, dissolved oxygen, ethanol of organic matter andvisible light to the photocatalytic activity for bromate removal. Results showed that theoptimal preparation conditions of Ag/TiO₂included Ag loading of6.0%and calcinationtemperature of400℃. The photocatalyitc activity for bromate removal increased firstlyand decreased later with the solution pH increase, the optimum pH was7.2. IntroducingO₂and N₂to the solution all inhibited the photocatalytc removal of bromate. Ethanolalso decreased the photocatalytic activity for bromate removal.6.0%Ag/TiO₂had finephotocatalytic activity for bromate removal under visible light. The kinetics ofphotocatalytic removal of bromate followed the first-order kinetic equation; the kineticconstant was0.01min^-1. Finally, the photocatalytic removal of bromate with Ag/TiO₂was researched underVisible light. The effects of Ag loading, calcination temperature, pH and ethanol oforganic matter to the photocatalytic activity for bromate removal were studyed. Resultsshow that the optimal Ag loading lied in6%. The best calcination was300℃. With thesolution pH increase, the photocatalyitc activity for bromate removal increased firstlyand decreased later, the optimum pH was7.2. Ethanol decreased the photocatalyticactivity for bromate removal.