The Study Of Organic Polluants's Degradation And Electricity Generation By Photoelectrocatalytic Process

With the population increase and industrial development in the recent decades,the large amounts of domestic sewage and industrial wastewater discharged into water bodies have caused serious environmental pollution and ecological destruction,and posed great threats to human survival and health,also exacerbated the problem of energy crisis.However,the optimal efficiency of traditional wastewater treatment technologies has been difficult to achieve.Therefore,more economic and effective methods have to be developed.As one of the common Advanced oxidation technologies?AOTs?,the photocatalytic oxidation technology is promising in organic pollutant treatment.Compared with conventional treatment processes,it has several advantages of environmental friendliness,energy-saving property,high efficiency,non-secondary pollution,and complete mineralization of organic pollutants.The photocatalytic fuel cells?PFCs?has attracted wide attention as an advanced wastewater treatment technology during the several years,which can utilize the chemical energy of the organic pollutants released during the degradation process.The single-photon PFC,one of the PFCs,is promising in pratical use due to its excellent discharge performance.To overcome the defects of existing single-photon PFC?high cost,Operation process complex?and enhance the pollutants removal efficiency.In this study,two kinds of modified PFC systems with different structures were designed,based on the primary cell principle and applied in organic pollutants degradation.Firstly,we designed the Pt/C type PFC by using the TiO₂ thin film electrode as anode and a proton exchange membrane/Pt-C catalysis/air diffusion layer compound electrode as cathode,besides,the anode-cathode distance of PFC was also optimized.Various model compounds were used as substrate for the PFC system.The results showed that the cell performance was obviously promoted after the PFC optimized,for example,when methanol(lmol L^-1)as the substrate of the PFC,produced open-circuit voltage 1.02V,short-circuit current density 3.75mA cm^-2 and maximum power density 1.4mW cm^-2.The factors that affect the PFC performance,such as initial concentration of organic matter,the anode-cathode distance,initial solution pH value,and species of organic matter have been investigated.Besides,the photocatalytic degradation rate of methyl-orange using PFC system was also discussed.The results demonstrate that the proposed PFC can achieve organic pollutant degradation and simultaneously recover the released chemical energy of pollutants.To optimize the structure of cell and reduce the use-cost,the Pt/C type PFC was redesigned by using MnO₂ catalyst as oxygen reduction catalyst instead of Pt-black/Pt.The performance of MnO₂ type PFC and the related influenceing factors were studied using methanol(1 mol L^-1)as substrate,the influenceing factors including organic matter and electrolyte concentration,initial solution pH value.The results showed that the optimized PFC structure can improve the discharge performance.To overcome the deficiencies of the conventional TiO₂ nano-particles which has high electrons/holes recombination rate and low light absorptivity,TiO₂ nano-tube array material and CdS/TiO₂ composite material were prepared to sever as photoelectrode of PFC.It turned out that the modified electrode materials can effectively raise the cell performance.