Electrocatalytic Degradation Of Dyes Wastewater On Metal-oxide Electrodes

Nowdays,the widespread disposal of dyes wastewaters caused serious health risks on environment and human life.Therefore,looking for some environment-friendly methods with high removal efficiency of dyes wastewater is a crucial and glamorous task.Recently,electrocatalytic oxidation method has attracted great interest because of its high efficiency,easy operation and environmental compatibility.Electrode materials are crucial for electrocatalytic process and have great influence on electrocatalytic degradation efficiency.In this paper,four kinds of electrode materials with high electrocatalytic activity were prepared via electrodeposition,pres sing-sintering or thermal decomposition methods.And these electrodes were applied in electrocatalytic degradation of dyes wastewaters including alizarin red,methylene blue,methyl orange and bromocresol green.The optimal degradation conditions were evaluated under different parameters.The main contents of this thesis were as follows:(1)Carbon quantum dots(CQDs)and sodium dodecylbenzene sulfonate(SDBS)modified Ti/CQDs-SDBS-PbO2 electrode was fabricated via electrodeposition method.The result showed that,compared with Ti/PbO2 and Ti/CQDs-PbO2 electrodes,Ti/CQDs-SDBS-PbO2 electrode had loose and porous structure.Moveover,the oxygen evolution overpotential of Ti/CQDs-SDBS-PbO2 electrode reached up to 2.25 V,and that of Ti/PbO2 and Ti/CQDs-PbO2 electrodes was 1.73 V and 1.84 V,respectively.As-prepared Ti/CQDs-SDBS-PbO2 electrode was used as anode in electrocatalytic degradation of alizarin red(AR)wastewater.The electrocatalytic degradation of AR was evaluated under different parameters,including initial pH,temperature,current density and electrolysis time.Under the optimal parameters of initial pH 5,temperature of 30?,current density of 15 mA cm-2 and electrolysis time of 150 min,the degradation efficiency of AR on Ti/CQDs-SDBS-PbO2 electrode reached up to 95.29%.(2)Ti/PbO2,Ti/Pr-Pb0O2 and Ti/Sm-PbO2 electrodes were fabricated via electrodeposition method.The results showed that,compared with Ti/PbO2 and Ti/Pr-PbO2 electrodes,Ti/Sm-PbO2 electrode had uniform size of pyramid and many pores.Moveover,the oxygen evolution overpotential of Ti/Sm-PbO2 electrode reached up to 2.40 V,and that of Ti/PbO2 and Ti/Pr-PbO2 electrodes was 1.75 V and 2.25 V,respectively.As-prepared Ti/Sm-PbO2 electrode was used as anode in electrocatalytic degradation of methylene blue(MB)wastewater.The electrocatalytic degradation of MB was evaluated under different parameters including temperature,current density,initial pH and electrolysis time.Under the optimal parameters of temperature of 30?,current density of 15 mA cm-2,initial pH 5 and electrolysis time of 120 min,the degradation efficiency of MB on Ti/Sm-PbO2 electrode reached up to 96.38%.(3)Magneli phase titanium electrode(MPT)and Sc2O3-MPT composite electrode were fabricated via pres sing-sintering method.The results showed that,compared with MPT electrode,Sc2O3-MPT composite electrode had less spherical particles and more pores.Moveover,the oxygen evolution overpotential of Sc2O3-MPT composite electrode reached up to 1.33 V,and that of MPT electrode was 1.16 V.As-prepared Sc2O3-MPT composite electrode was used as anode in electrocatalytic degradation of methyl orange(MO)wastewater.The electrocatalytic degradation of MO was evaluated under different parameters including current density,temperature,initial pH and electrolysis time.Under the optimal parameters of current density of 10 mA cm-2,temperature of 25?,initial pH3 and electrolysis time of 120 min),the degradation efficiency of MO on SC2O3-MPT composite electrode reached up to 90.16%.(4)Ti/SnO2-RuO2 electrode was prepared via thermal decomposition method.The results showed that Ti/SnO2-RuO2 electrode had "cracked-mud" structure and its oxygen evolution overpotential was up to 1.45 V.As-prepared Ti/SnO2-RuO2 electrode was used as anode in electrocatalytic degradation of bromocresol green(BCG)wastewater.The electrocatalytic degradation of BCG was evaluated under different parameters including initial pH,temperature,current density and electrolysis time.The result of batch experiment indicated that the removal efficiency of bromocresol green was influenced by the following factors in descending order:initial pH0,reaction temperature,current density and electrolysis time.Under the optimal parameters of initial pH0 7,reaction temperature of 30?,current density of 12 mA cm-2 and electrolysis time of 150 min,the degradation efficiency of BCG on Ti/SnO2-RuO2 electrode reached up to 91%.Results of this thesis demonstrated that Ti/CQDs-SDBS-PbO2,Ti/Sm-PbO2,Sc2O3-MPT and Ti/SnO2-RuO2 electrodes possessed excellent electrocatalytic property and showed great potential application in dyes wastewater treatment.