Preparation Of Titanium-based Coated Electrode And Treatment Of High Concentration Organic Wastewater

At present,the amount of organic matter in wastewater that is difficult to biodegrade is increasing,which has a serious impact on the environment and personal safety.Therefore,how to develop an efficient and simple method to treat this kind of wastewater has become a research hotspot.The electrocatalytic oxidation technology has a excellent effect on the treatment of organic matter in wastewater,and has a rapid reaction and no secondary pollution.It has broad application prospects in the field of wastewater treatment.Electrode materials are the core of electrocatalytic oxidation technology.Titanium-based electrodes have high stability and catalytic activity,and have been widely used in the degradation of organic substances in wastewater in recent decades.In this paper,Titanium-based composite coated electrode was used to treat high concentration organic wastewater by electrocatalytic oxidation.The specific contents are as follows:?1?This part intends to introduce a novel approach to preparing Ti/RuO₂-SnO₂-ZrO₂ and Ti/RuO₂ electrodes at the high temperature of 450?via the thermal decomposition method,in which titanium plate has been used as the support and isopropyl alcohol with RuCl₃·nH₂O,SnCl₄·5H₂O and ZrO?NO₃?₂ and that with RuCl₃·nH₂O only as the masking liquid,respectively.The electrodes have been characterized by a number of approaches,including the scanning electron microscope?SEM?,the X-ray diffractometer?XRD?and the cyclic voltammetry?CV?.Then,the above mentioned methods have been further adopted for degrading the chemical oxygen demand?COD?in the sewage purification.The corresponding results of the above mentioned experiments and researches demonstrate that the degrading rate of COD in the case for Ti/RuO₂-SnO₂-ZrO₂ tends to be higher than that in the condition of Ti/RuO₂.Furthermore,we have also investigated the effects of the current density,the NaCl concentration,the pH value and the electrode spacing distribution through a series of single-factor and orthogonal tests in detail.The afforementioned analyses indicate that the said single-factor and orthogonal tests tend to produce their main effects for degrading the COD in the sewage by using Ti/RuO₂-SnO₂-ZrO₂,the pH value and the degradation rate of COD in it at a high rate of 90.5%under the the optimum condition for degradation,that is to say,the current density of 40 mA/cm²,the concentration of NaCl of 4.0 g/L,pH value of 5.0with the electrode spacing of 10 mm.Besides,the characterization results also disclose that the formation of the solid solution of SnO₂ and RuO₂ in the Ti/RuO₂-SnO₂-ZrO₂ electrode proves to be beneficial for enhancing the bonding between coating and substrate.Besides,it can also help to improve the stability of the electrode,for ZrO₂ can refine the grain size,increase the surface roughness of the electrode and further enhance the electro-catalytic performance.In addition,the experimental data of the COD degradation has been found fitted by the pseudo-first-order model,and the reaction kinetic of COD degradation in the sewage in the condition of Ti/RuO₂-SnO₂-ZrO₂ tends to be well in accord with the model prediction.?2?Electrocatalytic Oxidation of Organic Wastewater by Ti/Sb-SnO₂-Pr/RuO₂-Pind Electrode?1?Ti/Sb-SnO₂-Pr/RuO₂-Pind and Ti/Sb-SnO₂-Pr/RuO₂ with Sb-SnO₂-Pr interlayer were prepared by coating thermal decomposition method.The intermediate layer was characterized by XRD and SEM.When n(Sn⁴⁺):n(Pr³⁺)was 100:1,the intermediate layer had higher crystallinity and the most uniform crack distribution.The composite electrode was characterized by XRD and SEM.The electrochemical properties of the electrode were studied by cyclic voltammetry?CV?,linear voltammetry?LSV?and enhanced lifetime test.The results show that the introduction of Pind in the coating effectively improves the surface morphology of the electrode,enhances the catalytic performance of the electrode,and prolongs the electrode life.?2?Ti/Sb-SnO₂-Pr/RuO₂-Pind was used in wastewater treatment.The effects of pH value,NaCl concentration,electrode spacing and current density on the degradation rate of wastewater COD were investigated.The results show that the degradation rate of COD reached 84.3%under the optimum conditions of pH 5.0,NaCl solution concentration 4.0 g/L,electrode spacing 10 mm and current density 40 mA/cm²,and the degradation process of organic matter conformed to the first-order kinetic model.?3?Electrocatalytic Oxidation of Organic Wastewater by Ti/Sb-SnO₂-Pr/IrO₂-Pind Electrode?1?Ti/Sb-SnO₂-Pr/IrO₂-Pind electrode materials containing Sb-SnO₂-Pr interlayer were prepared by coating thermal decomposition at different heat treatment temperatures.The effects of different heat treatment temperatures on the performance of the electrodes were investigated by XRD,SEM,CV,LSV and life test.The results demonstrate that the highest crystallinity of IrO₂,the most uniform distribution of surface cracks and the best electrochemical properties are obtained when the heat treatment temperature is 450?.?2?Ti/Sb-SnO₂-Pr/IrO₂-Pind prepared at 450?was used for wastewater treatment.The effects of pH value,NaCl concentration,electrode spacing and current density on COD degradation rate of wastewater were investigated.The results show that the degradation rate of COD reach 82.4%under the optimum conditions of pH 5.0,NaCl solution concentration 4.0 g/L,electrode spacing 10 mm and current density 40 mA/cm²,and the degradation process of organic matter conformed to the first-order kinetic model.