Electro-Catalytic Oxidation Of P-Nitrophenol By Ti/Sb-SnO₂ Doped With Rare Earth La Electrode

With developing of modern industry and economy, water pollution already becomes an austere issue which is confronted with by a great many country. At present, it has been the difficulty and focus of the waste water treatment for the disposal of toxic and biorefractory organics that can't be treated effectively by the current ordinary waste water treatment technology. In this thesis, we have performed a fundamental study on the electrocatalytic oxidation technology for the organics waste water treatment. P-nitrophenol is selected as the simulation pollutant of toxic and biorefractory organics.The Ti/Sb-SnO₂ electrodes doped with rare earth La were prepared by sol-gel process. Degeneracy of the prepared electrodes was investigated using reactive brilliant P-NP as a model pollutant. The parameters of the electrode preparation, including temperature and La doping amount, were studied in detail. The optimal calcination temperature, La doping amount were 450℃, 0.8%, respectively. The morphology, crystal structure, and chemical composition of the electrodes were analyzed by SEM, XRD and EDS, respectively. The oxygen evolution potentials of both the blank electrode and the Ti/Sb-SnO₂ electrode doped with rare earth La were investigated by polarization curve. Electrode life was also measured by damaged checking method. The results show that the Ti/Sb-SnO₂ electrode doped rare earth La has higher oxygen evolution potential and longer electrode life than the blank electrode.The influence factors and degradation kinetics were also studied. The results showed that current density, electrolyte concentration, and initial concentration influence the removal efections. The degradation of p-NP obeys the first kinetics equation, and the total reaction kinetics equation is Ct=C0exp(-0.6606C^-0.2893J^-0.2176M^-0.1908) .Form the HPLC and ion chromatograph (IC) results, we presume that in the reaction process, the initial·OH attack can occur at the C- NO₂ bond ofρ-NP, resulting in hydroquinone following the lose of -NO₂. Further oxidation of hydroquinone produced intermediates such as benzoquinone. As the reaction proceeded, these intermediates experience several ring openings in further oxidization, forming small molecule acids, such as formic acid and acetic acid, which finally led to the production of CO₂ and H₂O.