Sonoelectrochemical oxidation of sulfamethoxazole in simulated and actual wastewater on a piezo-polarizable FTO/BaZrxTi(1-x)O3 electrode: reaction kinetics, mechanism and reaction pathway studies

The sonoelectrochemical (SEC) oxidation of sulfamethoxazole (SMX) in simulated and actual wastewater on FTO/BaZr(0.1)Ti(0.9)O3, FTO/BaZr(0.05)Ti(0.95)O3 and FTO/BaTiO3 electrodes is hereby presented. Electrodes from piezo-polarizable BaZr(0.1)Ti(0.9)O3, BaZr(0.05)Ti(0.95)O3, and BaTiO3 materials were prepared by immobilizing these materials on fluorine-doped tin dioxide (FTO) glass. Electrochemical characterization performed on the electrodes using chronoamperometry and electrochemical impedance spectroscopy techniques revealed that the FTO/BaZr(0.1)Ti(0.9)O3 anode displayed the highest sonocurrent density response of 2.33 mA cm(-2) and the lowest charge transfer resistance of 57 omega. Compared to other electrodes, these responses signaled a superior mass transfer on the FTO/BaZr(0.1)Ti(0.9)O3 anode occasioned by an acoustic streaming effect. Moreover, a degradation efficiency of 86.16% (in simulated wastewater), and total organic carbon (TOC) removal efficiency of 63.16% (in simulated wastewater) and 41.47% (in actual wastewater) were obtained upon applying the FTO/BaZr(0.1)Ti(0.9)O3 electrode for SEC oxidation of SMX. The piezo-polarizable impact of the FTO/BaZr(0.1)Ti(0.9)O3 electrode was further established by the higher rate constant obtained for the FTO/BaZr(0.1)Ti(0.9)O3 electrode as compared to the other electrodes during SEC oxidation of SMX under optimum operational conditions. The piezo-potential effect displayed by the FTO/BaZr(0.1)Ti(0.9)O3 electrode can be said to have impacted the generation of reactive species, with hydroxyl radicals playing a predominant role in the degradation of SMX in the SEC system. Additionally, a positive synergistic index obtained for the electrode revealed that the piezo-polarization effect of the FTO/BaZr(0.1)Ti(0.9)O3 electrode activated during sonocatalysis combined with the electrochemical oxidation process during SEC oxidation can be advantageous for the decomposition of pharmaceuticals and other organic pollutants in water.