Preparation, Characterization And Application Of SnO₂ Electrodes For Pollutants Oxidation

In the past two decades, the electrochemical oxidation has been widelyinvestigated for wastewater treatment. Its good applicability, high oxidation efficiency,no secondary contamination, fast reaction rate, and easy operation make it a veryattractive alternative for degrading toxic and biologically refractory organicpollutants.It is well known that the anodes assemble is the heart of the electrochemicaloxidation process. The efficiency and mechanism of pollutants oxidation dependhighly on the properties of the anodes used. A good anode should meet the followingrequirements: good conductivity, good stability, and high current efficiency. However,industrial application of electrochemical oxidation is restricted due to lack of idealanodes. The development of active anodes is therefore a hot research topic in thisfield.This thesis systematically developed high-performance SnO₂ anodes for pollutantsdegradation. Major research works included: methological exploration for depositonof uniform oxide films on Ti substrates; preparation and characterization of novelTi/SnO₂-Sb-Ce anodes for pollutants degradation; and preparation andcharacterization of novel Ti/SnO₂-Sb-Mn anodes for pollutants conversion.A new deposition method, i.e. ultrasonic spray pyrolysis, was developed forelectrodes preparation. Experimental results showed that the ultrasonic spraypyrolysis method could not only select the precursor and control the depositioncondition easily, but also deposite films uniformly. The Ti/SnO₂-Sb electrodes weresuccessfully fabricated using ultrasonic spray pyrolysis. Under the samilar condition,the current efficiency for phenol degradation obtained on the Ti/SnO₂-Sb electrodesprepared by ultrasonic spray pyrolysis was 20-28% higher than that obtained onelectrodes prepared by the conventional methods.A novel Ti/SnO₂-Sb-Ce electrode for pollutants degradation was successfullyfabricated using ultrasonic spray pyrolysis, which could mineralized the pollutants into CO₂ and H₂O effectively. Physicochemical and electrochemical characterizationindicated the Ce doping could improve the microstructure, specific area and cyclicvoltammograms of electrodes. The orangeâ…¡degradation experiments revealed thatthe Ce doping could enhance the current efficiency by 22% and save the energyconsumption by 21%.A novel Ti/SnO₂-Sb-Mn electrode for pollutants electrochemical conversion wassuccessfully deposited using ultrasonic srpay pyrolysis, which could improve thebiodegradability of wastewater. Physicochemical and electrochemical examinationsdemonstrated that the solid-solution of Mn doping could improve the microstructureand cyclic voltammograms of electrodes effectively. The experimental resultsindicated that the biodegradability of wastewater containing orangeâ…¡/Methyl orangewere greatly enhanced after electrochemical pretreatment, and the ratios ofBOD₅/COD of wastewater were increased from 0.01 and 0.07 to 0.25 and 0.30,repectively.