Preparation And Characterization Of The Modified DSA Electrodes On Ti Base

This paper focused on the preparation of rare earth doped Ti/Sn-Sb and Ti/Sn-Sb/PbO₂ electrode, and investigation on its characteristics. Taking self-made washing sewage as model substrate, and studied the optimization of degradation processes.The temperature of thermal treatment and the doping amount of rare earth were studied in detail, which are the main influence factors on the characteristics of electrodes. On the basis of analysis of the O₂ evolution potential and the degradation of washing sewage, the preparation conditions of the three kinds of electrodes were determined. The best temperature and the proportion of doping amount of Nd-doped Ti/Sn-Sb electrode were about 550℃and Sn:Sb:Nd=100:6:2.5. The optimal temperature and the proportion of doping amount of Nd-doped Ti/Sn-Sb electrode were 500℃and 100:6:5. The best temperature and the proportion of doping amount of La/Ce mischmetal-doped Ti/Sn-Sb electrode were 500℃and 100:6:2.The micrograph of the electrode surface, the structure of the electrode surface and the element composition of surface layers were analyzed by SEM, EDX and XRD. Experimental results showed that doping of rare earth was in favor of grain refining, could increased the specific surface area of the coating and help to enhance the electrical conductivity and electro-catalytic ability of electrodes. Rare earth doping with right amount could promote the replace of Sn in the lattice of SnO₂ by Sb. But excessive doping would damage the lattice of SnO₂. It could decrease the ability of electrode, even lower than non-doped.The degradation processes of self-made washing sewage were studied. The result indicates that the best effect was obtained when La/Ce mischmetal-doped Ti/Sn-Sb electrode was anode. When electrode interval was 2cm, electrolytic concentration of NaCl was 0.2mol·L-1, pH was 10, the electrolysis voltage was 10V and the electrolysis time was 50min, the best treatment process was obtained. The removal efficiency of DBS and COD_Cr were 98.22% and 83.20%. Under the best treatment process. DBS was directly mineralized to CO₂ and H2O without other intermediate substances.Ti/Sn-Sb/PbO₂ modification by doping nonmetal was also studied in this paper. The interlayer of SnO₂ doped La or Nd were prepared by sol-gel method, the surface layer of PbO₂ were prepared by electrochemical deposition. It shows that the interlayer prepared by sol-gel method fully covered on Ti base and closely arranged. The rutile type nanometer grains were well-stacked and the layer had a large specific surface area. This kind of interlayer is in favor of the combination of the surface layer and interlayer and enhances the electro-catalytic ability and the service life of electrodes. For the interlayer of La doping electrodes, the proportion is Sn:Sb:La=100:6:1. For the interlayer of Nd doping electrodes, the proportion is Sn:Sb:Nd=100:6:2 . At above proportion, the removal rate of COD_Cr of model substrate was 91.90%and 90.93% , respectively.