Photoelectrocatalytic Characteristics Of Different Kinds Of Organic Compounds On TiO₂ Nanotube Arrays

TiO₂ nanotube arrays (TNAs) materials have exhibit outstanding photo-generated electron transportation performances and high efficiency in photoelectrocatalytic degradation. This thesis studied the reaction activities and mechanisms of exhausted photoelectrocatalytic oxidation of organic compounds based on self-organized and highly ordered TNAs electrode and a thin-layer reactor, and also discussed how to improve the photoelectrocatalytic degradation efficiency of organic compounds.Glucose was used as a representative easily degradable organic compound while succinic acid and phthalic acid as representative refractory compounds to investigate the effect of different reactor volume on reaction activities and mechanisms of photoelectrocatalytic degradation of organic compounds using TNAs electrode in a thin-layer cell. We found that with the increase of the reactor thickness, the photoelectrocatalytic reaction time would increase. The partial voltage, electrolyte concentration and organic compound concentration for photoelectric catalytic reaction influence were also analyzed in this thesis.The kinetics and mechanisms of photoelectrocatalytic degradation of two kinds of compounds, glucose with weak adsorption and phthalic acid with strong adsorption on TNAs were investigated by using a thin layer reactor, in which organic compounds can be exhaustive oxidized rapidly. The photo-generated currents-time(I-t) profiles were used to analyze the micro-processes of photoelectrochemical catalytic degradation on TNA electrode. As for glucose, the I-t curve, increased sharply in the initial time and then decreased rapidly, followed with a slowly decrement. This could be ascribed to the weak adsorbability of glucose molecule and it was slowly adsorbed on the surface of TNA electrode from body solution. However, the I-t curve for phthalic acid revealed a quite different changing trend- increased sharply in the initial time, then continued to increase and decreased slowly at last, which was due to the strong adsorbability and the mass existence of phthalic acid on electrode, and in addition, the low degradability of phthalic acid. The adsorption properties and the adsorption coefficient of the organic compounds, the reaction mechanism were also analyzed in this paper. It could be concluded that the exhausted photoelectrocatalytic oxidation of organic compounds in a thin-layer cell could help investigate the surface reaction process and micro-mechanism of organic compounds degraded on TNA electrode.We also studied the photoelectrochemical degration of the difficult degradable nitrogen organic compounds- amantadine in a thin layer reactor. It found that only 30% amantadine could be oxidized when the COD concentration was 50mg/L. When glucose which has abundant hydroxyl groups were mixed with amantadine could improved the degradation rate of hydrochloride. This results could be attribute to the hydroxyl radical produced by glucose which had synergistic effect on the degradation of amantadine. The mechanism of the synergistic action was preliminary discussed in the paper.