Synthesis And Performance Evaluation Of TiO2Photocatalytic Materials

Photocatalysis of semiconductor, as an environmental friendly technology, has attracted much attention and showed potential application in environmental protection, especially in the purification of water pollution. In all kinds of semiconductor photocatalytic materials, titanium dioxide has been widely used because of manyadvantages, such as better chemical stability, higher photocatalytic efficiency, cheapness and intoxiciyt. In this paper, The preparation of TiO2photocatalyst was discussed, then the powder photocatalyst was immobilized on some relevant carrier, which was more conducive to its degradation in the field of environment.The particles of TiO2were prepared by sol-gel method at first, using tetrabutyl titanate (TBT) as precursor, absolute ethyl alcohol (EtOH) as solvent, glacial acetic acid (HAc) as complexing agent and hydrochloric acid (HCl) as catalyst. The sol-gel method was modified by microwave treatment in the formation of gel. The prepared materials were characterized by XRD, SEM, EDS, UV-Vis and FT-IR techniques. Reaction parameters, such as hydrolyzing agent, molar ratio and calcination temperature were varied during the synthesis in order to get excellent technological conditions. The result showed that the optimal molar ratio of reactant were as follow:[TBT]:[EtOH]:[H2O]=1:30:4, pH=2and calcination temperature at550℃. It was acquired better crystallized grain when coupled with microwave treatment in the sol-gel process, which enabled the absorption spectrum red-shifted.Secondly, the TiO2powder was immobilized by composite coating technology included that co-electrodepositon and electroless composite coating using foam nickel as the carrier. The co-electrodepositon was carried out in a continuous stirring Watts type bath (containing TiO2particles), using nickel sheet as the anode, foam nickel carrier as the cathode. Several different conditions that influenced the coating, such as cathodic current density (JA), dosage of TiO2in bath (p), plating time (T), pH values, and surfactant to disperse were discussed during the process of co-electrodepositon. The result shows that the best technological conditions were as follow:JA=30mA/cm2, p=10g/L, T=30min, pH=4.0, select the anion active agent (SDBS) to disperse the particles in the bath. Another composite coating of immobilization, Ni-P-TiO2coatings were successfully obtained by electroless plating technique with a continuous stirring bath also. Effect of pH value and temperature on bath stability was investigated; relationship between TiO2content in bath and on the coating was also studied. The result showed that the pH value of bath was4～5, temperature about90℃and TiO2content5～10g/L. The TiO2content was9%when the coating was prepared in this conditions.The photocatalytic activity was evaluated in the phtocatalytic oxidation of Reactive Black GR as a model reaction under the ultraviolet irradiation. The prepared TiO2powders were tested in a slurry solution. It was exhibited the best photocatalytic activity when calcinated at550℃. The decolorization rate of particles prepared by sol-gel method, sol-gel coupled with microwave, and P25were90.95%,95.94%, and96.56%respectively after2hours. As the TiO2powder was immobilized by co-electrodepositon and electroless plating techniques, the decolorization rate of these two coatings were94.53%and92.40%respectively after4hours unber the same UV light.