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.
Post about "degradate"
In recent years,electro-catalytic oxidation is an effective method for organic compounds degradation.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 Fe doped Sb-SnO2/Ti electrodes were prepared by a sol-gel process.The electro-catalytic performances of the electrodes were evaluated based on the disposal efficiency.And the results showed that the electrodes which prepared by the turnplate method were better than the one prepared by impregnation method.The effects of the calcination temperature and doping amount of Fe on the performances of the electrodes were also investigated.The results showed that the suitable calcination temperature was 600℃and the best doping amount of Fe was determined with the molar ratio of Sn:Sb:Fe being 1:0.02:0.0001. Then the surface morphology,chemical compostion and the crystal structure of the electrodes were analyzed by SEM,EDS and XRD.Those electrodes were also evaluated through the anode polarization curve and voltammetry curve.The results indicated that the Fe doped Sb-SnO2/Ti electrodes was better than Fe undoped Sb-SnO2/Ti electrodes.We use the Fe doped Sb-SnO2/Ti electrode as anode and the titanium plate as cathode to degrade stimulant p-nitrophenol waste water in a glass trough.The effects of reaction time,initial concentration of p-NP,current density,electrolyte concentration and pH on degradation were systematically investigated.The results indicated that the degradation efficiency increased with the reation time and the tends became smooth when the raction time reached to certain degree.The degradation efficiency reached 97.2%when the reaction time was 90 min. The higher initial concetration of p-NP,the lower degradation efficiency. And the degradation efficiency also increased with the increasing of incurrent density.But after the current density reached 20 mA/cm2,the degradation efficiency would lower with the occurrence of negative effect. The higher electrolyte concentration of p-NP,the higher degradation efficiency.And after the electrolyte concentration reached 0.03 mol/L Na2SO4,the degradation efficiency would not increase.The degradation efficiency of p-NP was higher in the acidic conditions when compared to alkaline and neutral conditions.The results indicated that the optimum time was 90min,the optimum electrolyte concentration was 0.03 mol/L Na2SO4,and the optimum current density was 20 mA/cm2.It also showed that the degradation of the p-NP conformed to the first order kinetics.From the HPLC and ion chromatograph（IC） results,we presumed that in the reaction process,with the·OH attacking,the-NO2 could removed from p-NP,which result in the hydroquinone produced.Further oxidation of hydroquinone produced intermediates.As the reaction proceeded,these intermediates experienced several ring openings through further oxidization,and formed small molecule acids such as formic acid and acetic acid,which finally led to the production of CO2 and H2O.