Preparation And Characterization Of Er Doped Ti/SnO₂-Sb Electrode And Study On Its Electrocatalytic Degradation Of Acetamiprid Synthetic Wastewater

The removal of pesticides wastewater has become an urgent and important problem of environmental pollution. This thesis explored the electro-catalytic treatment of acetamiprid pesticide wastewater. Citric acid chelating precursor method was used to prepare the rare earth Er doping Ti/SnO2-Sb electrode with high performance. The appropriate preparation conditions:the calcination temperature was650℃and the mole ration of Sn:Sb:Er was100:6:0.5. SEM, XRD, EDS, spectroscopy, potentiodynamic scanning were studied to analyzed the mechanism of Er doping on the Ti/SnO2-Sb electrode. The results showed that:Er doping is conducive to better electrode morphology and crystalline structure. Er doping can improve the rehydration of the electrode surface coating. Er doping in SnO2thin films introduces an acceptor impurity to reduce the oxygen vacancy concentration and the semiconductor bandgap. Er doping also raises the oxygen evolution potential of the electrode to improve the current efficiency and reduce energy loss. The doped electrode prepared under the appropriate process, shown good performance on the removal of acetamiprid wastewater. After180min electrolysis,87.45%and69.31%of acetamiprid and TOC was removed, respectively. Both acetamiprid and TOC degradation process were in line with the first-order kinetics. Acetamiprid degradation rate was not only influenced by the mass transfer rate of acetamiprid, but also the reaction bewtten the acetamiprid and hydroxyl radical (HO·). The classification of acetamiprid degradation reaction was determined as indirect electrolysis after cyclic voltammetry tests. Acetamiprid degradation products was detected by mass spectrometry, combined with the mass spectrometry analysis of the electrocatalysis of6-chloronicotinic acid. Possible degradation pathway was propsed. HO· and H2O2played the dominant role in the degradation of Acetamiprid. The situ generated H2O2was ascribed to the special structure of acetamiprid. The acetamiprid degradation process produced some pyridine-containing intermediates.6-chloronicotinic acid was one of them.6-chloronicotinic acid was confirmed to be further attacked by HO· or H2O2, the pyridine ring was then destroyed, forming the organics of cyclopentane carboxylic acids or the piperidine derivative, respectively. After the pyridine ring opening, the organic biodegradable of the acetamiprid wasterwater was improved, and was eventually mineralized. The results of this research enrich the theoretical content of Ti/SnO2-Sb electrode preparation. It also provides a new choose for the treatment of pesticides wastewater, especially pyridine-containing contaminant.