Preparation Of Cobalt Compound/carbon Composite Cathode And Study On Degradation Of Organic Wastewater

Electrochemical advanced oxidation processes(EAOPs),which can in-situ produce hydrogen peroxide and other strong oxidants by the electrocatalysis interaction between electrodes have been proven to be an efficient technology for degradation and mineralization of organic contaminants.Cathode materials have been proven to be an important role in the process of EAOPs.Therefore,novel cathode materials should be investigated to improve efficiency for generation of hydrogen peroxide and other strong oxidants and solve the problem of organic waste water pollution.In this study,we reported two strategies for synthesis of Co3O4/porous carbon(Co3O4/PC)composites and Co9S8/partly-graphitized carbon(Co9S8/PGC)composites using waste pomelo skins as carbon source,CoCl2 as cobalt source and thiourea as sulfur source.These composites were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),fourier transform infrared(FT-IR),scanning electron microscopy(SEM),transmission electron microscopy(TEM),cyclic voltammetry experiments(CV)and electrochemical impedance spectroscopy(EIS)and so on.Results demonstrated that Co3O4/PC composites and Co9S8/PGC composite had a larger specific surface area,active site and the oxygen containing functional groups,contributing to the improvement of electric conductivity,electric catalytic activity and production of H2O2 and ·OH for removing pollutant.Furthermore,Co3O4 and Co9S8 with coexistence of Co2+/Co3+ was tightly embedded into the carbon skeleton,contributing to enhancement stability of these composites.In the process of electrocatalysis,we investigated the degradation of phenol and ceftazidime as the model organic and pharmaceutical wastewater using C03O4/PC composites or Co9S8/PCGC composites as cathode and Ti/IrO2/RuO2 as anode.Moreover,the possibility of electrical catalytic mechanism was assumed.Results indicated that the phenol degradation by C03O4/PC cathode reached 91.2%after 120 min,while the COD removal efficiency of ceftazidime reached 88.0%after 480 min under the the optional experimental conditions:0.1 M Na2SO4 initial electrolyte solution,100 mg L-1 initial phenol solution,50 mg L-1 ceftazidime initial solution,and 25 mA cm-2 current density.Similarly,when the current density was 30 mA cm-2,the phenol degradation by Co9S8/PGC cathode reached 89.6%after 120 min,while the COD removal efficiency of ceftazidime reached 87.1%after 480 min under the above optional experimental conditions.