Carbon Nitride Photocatalysis And Coupled Fuel Cell Degradation Of VOCs

The emission of volatile organic compounds（VOCs）will have an adverse effect on biological survival and the environment.In order to effectively control VOCs,a variety of air purification technologies have been developed.Among them,photocatalysis is a potential technology,but there are problems such as easy recombination of photogenerated carriers,low quantum efficiency and no energy recovery.Therefore,it is possible to find new catalysts and catalyst modification methods to inhibit electron-hole recombination and improve photocatalytic efficiency.At the same time,coupling with other technologies is also an important way to improve the photocatalytic effect.The research in this article includes two parts:synthesis of g-C₃N₄-TiO₂ nanocomposite materials,construction of photoelectric catalysis（PEC）and microbial fuel cell（MFC）coupling system（PEC-MFC）,on this basis,the activation of persulfate technology（PS）Coupled with bio-photocatalytic system（PEC-MFC-PS）,used to degrade gaseous VOCs and recover energy;synthesis of Cu-CN single-atom catalyst,coupled with photocatalytic activation of hydrogen peroxide to efficiently catalyze the oxidation of liquid VOCs.（1）The g-C₃N₄-TiO₂ composite catalyst prepared by the calcination method is used as the photocathode,which works in synergy with the biological anode to construct an efficient bio-photoelectrochemical system to continuously remove VOCs.Different reaction conditions were investigated in the single-cathode system,and the PEC-MFC system was found to have the highest efficiency,indicating that the coupling of MFC and g-C₃N₄/TiO₂ heterojunction can help improve the separation and final removal efficiency of photogenerated carriers.Based on the single-cathode experiment,the removal rate of trimethylamine was evaluated by expanding the cathode area and increasing the flow rate in the double-cathode system(the removal rate was 1.3 g·m^-3·h^-1 at an initial concentration of 1.53 g·m^-3).Combined with activated persulfate technology,an activated potassium persulfate（PS）coupled bio-photocatalytic system（PEC-MFC-PS）was designed to obtain high-efficiency removal of trimethylamine.In the PEC-MFC-PS system,the TMA removal efficiency is the highest.(The removal rate is 1.9 g·m^-3·h^-1 when the initial concentration is 1.53 g·m^-3).At the same time,in the PEC-MFC system,the catalytic electrode substrate was changed to carbon fiber felt,and ethyl acetate was tested.Under the condition of 100 m L·min^-1,initial concentration of 910 mg·m^-3,and catalyst amount of 0.2 g,the removal rate was 98%.（2）Preparation of Cu-CN deformed corrugated layer structure catalyst,confirmed the existence of single atoms by HFAAD-STEM.The Cu-CN activated H₂O₂ system is constructed,and the soluble oxidant can quickly generate free radicals to degrade pollutants under the activation of the catalyst Cu-CN.In the experiment,the best experimental conditions for the activation reaction（different doping ratio,different reaction system,different light source intensity,etc.）were explored by degrading rhodamine.The results showed that the catalyst showed good activity at p H=7.0.The activation of H₂O₂ has good stability.The Cu-CN activated H₂O₂ system is combined with photocatalysis to enhance the pollutant treatment effect.The Cu-CN/H₂O₂+PC system degrades 99%of 1g·L^-1 Rh B,with the best efficiency,and the corresponding k value reaches the maximum value of 0.236 min^-1.On this basis,ethyl acetate was used as a model pollutant to explore the degradation effect of Cu-CN activated H₂O₂ system,and the effects of different systems,different concentrations of H₂O₂,and different Cu states on the degradation of ethyl acetate were investigated respectively.When the ethyl acetate concentration is 702.33 mg·L^-1,the effect of ethyl acetate reaches 77.54%.