Photoelectrocatalytic Degradation Of Acid Red B On Titanium Dioxide Photoanode

Immobilized TiO₂ thin film electrode deposited on porous nickel were prepared by sol-gel method and were characterized by XRD, SEM. The photoelectrocatalytic (PEC) system was built, using the thin film electrode as working electrode, platinum electrode as counter electrode, and saturated calomel electrode as reference electrode. A reactor was designed based on the need of research, using 9W UV lamp(253.5nm) as light source, In this reactor the photodegradation and photoelectrocatalytic degradation of Acid Red B in aqueous solution was studied. The effects of some factors such as bias, temperature, initial pH, doping Pt were researched.The degradation efficiency of the objective matter in aqueous solution were analyzed by 721-spectrophotometer via the test of its absorbency. Using the method of absorbency, the removal percentage of COD was analyzed by device of COD clear-up. The photoelectrocatalytic degradation process of the objective matter was analyzed by UV-VIS, The mechanism of photocatalytic activity of TiO₂ doped by Pt(â…£) was researched by relativistic density functional theory(DFT) and Plane Wave Pseudo Potentials(PWPP).The conclusions as follows:XRD resuRs indicate that the TiO₂ in the film electrode is anatase phase. The film electrode shows a high photo catalytic activity in degradation of the Acid Red B in aqueous solution. As a good electric conductor porous nickel can be used as the carrier of photo catalyst.The results show that under the condition of external bias potential +0.05v, pH=4.0 and 120 min irradiation at room temperature(29℃), the degradation efficiency of ARB reaches 85.5%, and the removal percentage of COD reached 84%.The photocatalytic activity of TiO₂ thin film photoelectrode can be enhanced by doped Pt, The results showed that under the conditions of doped 3% Pt, external bias potential +0.05v, pH=4.0 and 60 min irradiation, the degradation efficiency of ARB reached 98%, and the removal percentage of COD reached 94%.UV-vis spectra analysis of the aqueous solution in the process of degradation shows that the ARB was degraded into small molecule.The kinetic was studied by changing the temperature. The results show that the apparent rate constant of degradation reaction is the first order and its activation energy is 32.75kJ/mol.The crystal structure of TiO₂ doped by Pt(â…£) was researched by relativistic density functional theory(DFT) and Plane Wave Pseudo Potentials(PWPP), The calculation showed that the band gap of TiO₂ doped by Pt(â…£) became narrow, the density of states was enhanced. It illuminated that the composition of e^- and h⁺ can be decreased and the photocatalytic activity can be enhanced.