Study On The Degradation Of Dye Wastewater Using Modified TiO₂ Photocatalytic Fuel Cell ?PFC?

In the process of modern industrialization,mankind ignore the protection of the environment as they pursue the rapid development of industrialization and economic.They discharge a large amount of sewage into the nature water bodies,which exceed the self-purification capacity of water bodies and cause serious water pollution.Not only does it have a negative impact on the ecological environment,but also it poses a serious threat to the survival and development of human beings,and wastes organic materials.Organic compounds in wastewater,such as carbohydrates,fatty acids,and amino acids,store large amounts of chemical energy.Dye wastewater is a typical refractory industry sewage,which is characterized with high toxicity,high chromaticity,high concentration and high alkalinity.Photocatalytic fuel cell?PFC?is a new type of energy device that produces electricity at the same time treating wastewater.It has attracted wide attention in the field of wastewater treatment and energy recovery.Due to the advantages of chemical stability,non-toxicity,high catalytic efficiency,strong corrosion resistance and low cost,TiO₂ has been studied generally as PFC photoanode.However,its application is limited since its light utilization rate is low,and the recombination rate of photo-generated electrons and holes is high.The purpose of this paper is to prepare TiO₂-based modified PFC anodes with visible light response.Through modifying of TiO₂,its light response wavelength is extended,the utilization of excitation light is increased,and the recombination rate of photogenerated electrons and holes is reduced.The cost of wastewater treatment is reduced,since electricity generated simultaneously while waste water treated by PFC.C-TiO₂/Ti,Bi-TiO₂/Ti and C,Bi-TiO₂/Ti electrodes were prepared and used as photoanode respectively,and Cu₂O/Cu was used as cathode to constitute PFCs,their electrochemical properties and performances of dye wastewater treatment were investigated.The specific contents and results are stated as follows:1.Preparation and characterization of modified TiO₂ PFC photoanodes:the C-TiO₂/Ti,Bi-TiO₂/Ti and C,Bi-TiO₂/Ti PFC photoanodes were prepared by sol-gel method,using glucose and lanthanum nitrate as doping source.The results of the photoanodes characterization show that C,Bi elements successfully doped into TiO₂.The modified TiO₂ catalyst has a stable photoelectric response.The doping of C and Bi elements effectively inhibits the transformation of TiO₂ from anatase phase to rutile phase and the growth of crystal grain,narrows the band gap of TiO_2,and reduces the gap energy.The absorption edge of modified TiO₂ has a significant red shift,and it has strong light absorption in the visible region.2.The influence factors optimization of PFC performance:Including preparation conditions optimization of modified TiO₂ PFC photoanode and optimization of PFC dye treatment conditions.The optimization conditions of PFC,such as the calcination temperature,calcining time,the molar ratio of doping,and the initial concentration and pH of Rhodamine B solution,were investigated.The best preparation conditions for PFC anodes were as follows:?1?C-TiO₂/Ti anode:calcined at 550°C for 2 h,the molar ratio of dopant atoms was n?C:Ti?=0.067;?2?Bi-TiO₂/Ti anode:calcined at 450°C for 2 h,the molar ratio of dopant atoms was n?Bi:Ti?=0.042;?3?C,Bi-TiO₂/Ti anode:calcination at 500°C for 2 h,the molar ratio of dopant atoms was n?C:Bi:Ti?=6.7:2.8:100.For three different anodes PFC treatments,the treatment conditions for Rhodamine B all were:initial concentration was 20 mg·L^-11 and initial pH was 7.0.3.Comparison of different photoanode PFCs properties:?1?C-TiO₂/Ti photoanode PFC:J_scc was 0.084 mA·cm^-2,V_oc was 0.385 V,JV_max was 5.91×10^-3 mW·cm^-2,FF was 0.18,and the decolorization efficiency of Rhodamine B was 91.7%for 90 min treatment;?2?Bi-TiO₂/Ti photoanode PFC:J_sc was 0.120 mA·cm^-2,V_oc was 0.350 V,JV_max was 2.32×10^-3 mW·cm^-2,FF was 0.06,and the decolorization efficiency of Rhodamine B was 84.3%for 90 min treatment;?3?C,Bi-TiO₂/Ti photoanode PFC:J_sc was 0.126 mA·cm^-2,V_oc was 0.540 V,JV_max was 7.40×10^-3 mW·cm^-2,FF was 0.11,and the decolorization efficiency of the Rhodamine B was 94.2%for 90 min treatment.The PFC with C and Bi co-modified TiO₂photoanode had better electricity generation performance and higher dye degradation efficiency.Due to the synergistic effect of C and Bi doping elements,the performance of the PFC with the co-doped TiO₂ photoanode is superior to that with the single element doped TiO₂ photoanode,and its stability is also improved.In this paper,TiO₂ was modified by non-metal and metal to extend its light response wavelength and enhance the utilization of excitation light.The results of this study can provide experimental data reference for PFC related research.