Preparation Of Modified Lead Dioxide Electrode And Its Application In Water Treatment

Electrochemical treatment technology as a green and efficient physical and chemical treatment technology,obtained a lot of scientific research workers continue research and development in recent years.The traditional titanium-based lead dioxide electrode has good electrocatalytic performance,but the lead dioxide easily fall off from the matrix,and make the electrode exists some disadvantages in the stability,catalytic and service life.Therefore,it is necessary to modify the titanium-based lead dioxide electrode on the basis of the original advantages to further optimize and improve the electrochemical performance,so that it can be better applied in electrochemical water treatment technology.In this paper,the titanium-based lead dioxide electrode is modified in both ways,which are the middle layer and the surface layer.The middle layer coating solution uniformly coated on the titanium plate to prepare middle layer by the thermal deposition method,and the surface layer is electroplated by electrodeposition to obtain a modified titanium-based lead dioxide electrode.In this study,Ti/RuO2-SnO2-CeO2/PbO2,Ti/RuO2-SnO2/PbO2-CeO2 and Ti/RuO2-SnO2/PbO2-nano-TiO2 electrodes were prepared,respectively.The morphology and structure of the electrodes were characterized by scanning electron microscopy(SEM),X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).The results show that the best molar ratio of Ru,Sn and Ce in the ternary mediate layer is 0.3: 0.4: 0.3;the best binary mediate layer to Ru,Sn molar ratio is 3: 2 At this point the middle layer showed uniform density and form a solid solution.CeO2 or nano-TiO2 added to the surface was dispersed on the surface of PbO2 in granular form.The electrochemical properties of the electrode were tested by cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)with Ti/RuO2-SnO2/PbO2 electrode containing ternary intermediate layer.The results show that the oxygen evolution potential is about 1.0 V higher than that unmodified Ti/ PbO2 electrode.The lifetime of the electrode was 136 hours,is 6.5 times than that of Ti/PbO2 electrode,which indicated that the addition of the middle layer increased the adhesion ability of the surface PbO2,and enhance the stability of the electrode.With the stainless steel mesh as the cathode,the self-made electrode as the anode,after degradation of 100 mg/L 4-chlorophenol(4-CP,100 mg·L-1)for 120 minutes,the degradation efficiency was more than 99% and the electrode was intact.The degradation rate of Ti/PbO2 was about 95%,but the surface of the electrode was damaged and destroyed.The Ti/RuO2-SnO2/PbO2-CeO2 electrode prepared by adding the binary intermediate layer and the surface doped with cerium was tested by cyclic voltammetry curve(CV)and electrochemical impedance spectroscopy(EIS).It can be observed that the optimum concentration of Ce(NO3)3 is 5 mmol·L-1,the oxygen evolution potential is about 1.71 V,the electrode has the smallest electrochemical reaction resistance(Rct)and the lowest oxide resistance(Rf),accelerated test time reached 215 h.The electrocatalytic degradation of 100 mg·L-1 4-CP showed that the removal rate of 4-CP was more than 99% and the COD removal rate was above 95% when the current density was 30 mA·cm-2 for 80 min.Ti/RuO2-PbO2-nano-TiO2 electrode was prepared by doping the surface layer with nano-TiO2 with photocatalytic performance.The cyclic voltammetry curve(CV)test and electrochemical impedance spectroscopy(EIS)test showed that the electrode has a high oxygen evolution potential and a small charge transfer resistance.The electrode degraded 4-CP for 80 min under UV irradiation,the removal rate of 4-CP was over 99%,and the current efficiency was 10.81%.