Research On Preparation Of TiO₂Powders And Its Photocatalytic Performance Under Sunlight Irradiation

In recent years, nano-TiO₂is widely used in the area of dyes wastewater treatmentdue to its good photocatalytic activity, nontoxicity, innocuousness, high chemical stabilityand so on. The TiO₂nanoparticles are prepared via sol-gel method, with tetrabutyl titanate[Ti（OBu）4] as the precusor, absolute ethanol as solvent and HCl as hydrolysis inhibitor.The experiments show that the optimized sol-gel conditions should be as follows: thetetrabutyl titanate dosage is15mL, the anhydrous ethanol dosage is150mL, thechlorhydric acid dosage is3mL, the drying temperature is80oC, and the calcinedcondition including the calcined temperature of400oC and the calcined time of about2h.According to the XRD and UV-Vis analysis, the nanoparticle titanium dioxide is anatasein process, and the photocatalyst can absorb some visible light. The result of BET showsthat the particles diameter is12.09nm, the surface area is40.497m2/g.The TiO₂powder is mono-doped with Ce, Zn, Cr as dopant in order to enhance theTiO₂nanoparticles’ photocatalytic activity. The degradation of alizarin red S undersunlight irradiation with the doped and pure TiO₂as catalyst is investigated respectively.The results shows that the mono-doped TiO₂powders have higher photocatalytic activitythan the pure TiO₂, especially, the photocatalytic activity of Ce doped TiO₂is the highestamong the mono-doped TiO₂powders prepared in this study. In this case the degradationrate of alizarin red S is95.68%after illuminated for2.5h，which improves by20.47%than that of the pure one in sunlight.The best doping amount and the effect of the threemetal ions on photocatalytic activity of mono-doped TiO₂is in an order of Ce（2.0%）>Zn（1.5%）>Cr（1.5%）.The degradation efficiency of dye wastewater is discussed with alizarin red S solutionas a simulated pollution and then the degradation mechanism is investigated undersunlight irradiation, considering the TiO₂photocatalyst dosage, initial pH and dyesoriginal concentration as the different controlled paraments.