Modified Of Lead Dioxide Electrode And Its Application In Water Treatment

Currently,electrochemical advanced oxidation process?EAOPs?,as a new water pollution treatment technology,has shown a good promise in the treatment of a wide range of water pollutants,making it a research hotspot of decentralized water treatment system and wastewater treatment system.In addition,they have other advantages,e.g.,environmentally friendly,easily automate operation,and compact modular configuration.Therefore,the development of EAOPs has always been a hot spot of academic research.Anode material is the core of EAOPs.Compared with other electrodes,lead dioxide electrode has the advantages of high oxygen evolution potential and low cost,so it has received more attention in the field of electrochemical water treatment.However,the electrocatalytic activity and stability of unmodified lead oxide electrode are not fit to the requirements of industrial application.In view of this aspect,the catalytic layer and basal layer of PbO₂ electrode are modified in this paper to further improve the catalytic activity and service life of such electrode.Nano-diamond?ND?has strong mechanical stability,wide potential window and abundant oxygen-containing functional groups.Therefore,ND modified lead oxide electrode was successfully prepared by electro-deposition?marked as Ti/SnO₂-Sb/PbO₂-ND?.Chronoamperometric curves for PbO₂ deposition reveals that the addition of nano-diamond particles could promote the growth of ?-PbO₂ crystallites.This can be ascribed to the enhancement in the electrochemical generation of ^·OH in the presence of nano-diamond.Additionally,the presence of nano-diamond could effectively improve the electromigration of Pb²⁺ toward the anode surface by the formation of negatively charged [Pb²⁺-nano-diamond] complex.The optimum doping concentration of nano-diamond for ?-PbO₂ preparation was 1.5 g/L.As compared with blank ?-PbO₂ electrode,Ti/SnO₂-Sb/PbO₂-1.5ND electrode has smaller grain size,more compact film and higher ratio of Oad/?Oad+OL?.The electrochemical active area for Ti/SnO₂-Sb/PbO₂-1.5ND electrode was increased to 4.55 cm²,while it was only 2.73 cm² for ?-PbO₂ electrode.Notably,the oxygen evolution overpotential of Ti/SnO₂-Sb/PbO₂-1.5ND electrode was approximately 2.1 V/SCE,which was higher than blank ?-PbO₂ electrode?1.81 V/SCE?.The degradation ability of prepared electrode was also investigated using MB as a model pollutant.Effectiveness of important process parameters of current density was investigated.The results showed that the removal rate of MB reached 100% within 60 min at a current density of 30 m A cm^-2.Generally,the Ti/SnO₂-Sb/PbO₂-1.5ND shows promise as an efficient and low-cost electrode for electrochemical treatment of industrial wastewater.The above electrode has slow electron transfer efficiency and low stability.In view of these problems,PbO₂ electrode is further modified on the basis of nano-diamond modification.A new Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode was prepared by electrodeposition technique.The substrate is reduced titanium dioxide?TiO₂-NTs₂?.The mechanism of electrode catalytic performance enhancement was explained by physicochemical characterization and electrochemical characterization.Effectiveness of important process parameters of electrode type,current density,initial concentration and supported electrolyte?Cl-?on degradation of bentazon was investigated.The results showed that the Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode had a raised structure,which could effectively increase the specific surface area of the electrode,and the PbO₂ film on the electrode surface were more compact,more uniform and smaller size.The PbO₂ crystals on the electrode surface mostly are ?-PbO₂.The grain size of Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode is 17 nm,which is smaller than the size of PbO₂ electrode in the previous chapter.It is beneficial to catalytic degradation of pollutants.The electrochemical reduction of titanium oxide nanotubes had slightly effect on their morphology.Based on the TiO₂-NTs₂,the content of Pb²⁺ was increased in electrochemical deposition.Meanwhile,oxygen containing functional groups on the Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode surface were also raised.Electrochemical performance tests showed that the electrochemical reduced TiO₂ nanotubes could effectively reduce the charge transfer resistance,among which the Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode had a smaller electrode charge transfer resistance and higher oxygen evolution overpotential.Notably,the electrochemical active area of the Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode was increased to 5.2 cm²,while it was only 4.55 cm² for Ti/SnO₂-Sb/PbO₂ electrode.The catalytic performance of Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode was higher,and the average energy consumption of the electrode was lower under the same conditions by bentazon simulated wastewater degradation experiment.The best degradation conditions was confirmed.The results showed that the COD removal efficiency and average energy consumption in 0.1 mol L^-1 Na₂SO₄ + 1 mmol L^-1 NaCl solution containing 30 mg/L bentazon could achieve 92% and 0.96 k Wh for Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode,respectively,with an current density of 30 m A cm^-2 after 120 min.The degradation process of bentazon follows first order kinetics.The degradation rate of bentazon was not significantly affected after ten recycling experiment.This result shows that the Ti/TiO₂-NTs₂/SnO₂-Sb/PbO₂-1.5ND electrode had good stability and long service life.Generally,the electrocatalytic performance and service life of PbO₂ electrode were improved by simple and feasible modification method.Therefore,this study provides theoretical guidance for improving PbO₂ electrode properties and lays a foundation for the realization of industrial application of electrode in the future.