Electrocatalytic Degradation Of Benzenoid Dye Wastewater By Two Anodes

With the development of modern industry and economy,benzenoid dye wastewaters with high toxicity,dark chroma and non-degradability caused serious threat to water resources which are necessary for human beings.The treatment and pollution-free emissions of benzenoid dye wastewater have become a hot issue in daily life.Recently,the electrochemical oxidation process has attracted attention due to its environmental compatibility and high oxidization.In the electrochemical oxidation process,electrode materials play an important role.In this paper,Ti/IrO2-RuO2 and Ti/Ta2O5-Pt electrodes were prepared by thermal decomposition method and also applied in electrocatalytic degradation of brilliant cresyl blue(BCB),phenol red(PR)and malachite green(MG).The main contents of this paper are as follows:(1)Ti/IrO2-RuO2 anode was prepared by thermal decomposition method through employing IrCl3·3H2O and RuCl3·3H2O as materials.The structure of Ti/IrO2-RuO2 was characterized by scanning electron microscope(SEM),energy disperse spectroscopy(EDS)and X-ray diffraction(XRD).Oxygen evolution reaction of water was observed when electrolysis potential reached to 1.24 V(vs.SCE),and the electric current increased sharply with the increment of voltage.The effect of electrolytic time,electrolytic voltage,concentration of electrolyte,electrode space and the reaction temperature on the electrocatalytic degradation of BCB(initial chemical oxygen demand CODCr.0=558.76 mg·L-1)were studied in details when Ti/IrO2-RuO2 electrode was employed as anode.According to experimental data,COD removal rate of BCB was 78.4%,and the degradation rate of BCB was 77.1%under the optimal condition(electrolytic voltage 3.0 V,concentration of electrolyte 6.0 g·L-1,electrode space 3 cm,reaction temperature 50 ? and electrolysis time 120 min).It showed that Ti/IrO2-RuO2 electrode had good catalytic activity and high degradation to phenothiazine benzenoid dye wastewater.(2)PR is a benzenoid dye wastewater,which has drak chroma,high toxicity and stability,and PR wastewater was too stable to be degraded.In this paper,Ti/IrO2-RuO2 electrode was employed as anode to degrade PR wastewater(CODCr,0= 385.97 mg·L-1).Moreover,the effect of electrolytic time,current density,concentration of electrolyte,initial pH of PR wastewater and the reaction temperature on the electrocatalytic degradation of PR was discussed carefully.It was found that the COD removal efficiency of PR was 75.4%,and the degradation rate of PR was 74.5%under the optimal conditions(current density 15 mA·cm-2,concentration of electrolyte 6.0 g-L-1,initial pH 3,reaction temperature 40 ? and electrolysis time 120 min).Ti/IrO2-RuO2 electrode had high reactivity to the degradation of PR wastewater.According to the experimental results above,Ti/IrO2-RuO2 electrode had preferable application in benzenoid dye wastewater treatment.(3)Moreover,Ti/Ta2O5-Pt anode was prepared by thermal decomposition method through employing TaCl5 and H2PtCl6 as materials.The morphology of as-prepared electrode was characterized by scanning electron microscope(SEM),energy disperse spectroscopy(EDS)and X-ray diffraction(XRD).It was found that Ti/Ta2O5-Pt had similar morphology to Ti/Ir02-RuO2.The oxygen evolution potential of Ti/Ta2O5-Pt was about 1.18 V(vs.SCE).The effect of initial pH,concentration of electrolyte,current density and reaction temperature on the electrocatalytic degradation of MG(initial chemical oxygen demand CODcr,o ?485.85 mg·L-1)was studied in details when Ti/Ta2O5-Pt electrode was employed as anode.According to experimental data,the degradation efficiency of MG was 82.2%and the COD removal efficiency was 80.5%under the optimal conditions(initial pH 4,concentration of electrolyte 6.0 g·L-1,current density 15 mA cm-2,reaction temperature 30 ? and electrolysis time 120 min).It showed that Ti/Ta2O5-Pt electrode had anticipated application in triphenylmethane benzenoid dye wastewater.The results above showed that the Ti/IrO2-RuO2 and Ti/Ta2O5-Pt anodes were efficient and eco-friendly in treat benzenoid dye wastewater,including phenothiazines,phenol red and triphenylmethane.