Removal Of VOCs By Dielectric Barrier Discharge Combined With Ag-based Photocatalyst

VOCs are one of the main reasons for the formation of photochemical smog and aerosols,which seriously pollute the environment and endanger human health.The treatment of VOCs is imminent.This paper studies the efficient degradation of VOCs by dielectric barrier discharge combined with silver-based photocatalysts at room temperature and pressure to achieve harmless treatment of VOCs.In this study,two photocatalysts,Ag₃PO₄ and g-C₃N₄/Ag₃PO₄,were prepared.Using glass spheres andγ-Al₂O₃ as carriers,the prepared photocatalysts were combined with a wire-tube dielectric barrier discharge（DBD Plasma）reactor.In conjunction,an experimental study on the degradation of toluene was carried out.The effects of applied voltage,power frequency,gas flow,initial concentration and filler type on the degradation of toluene were discussed.The experimental results show that the order of catalytic performance of each photocatalyst is:g-C₃N₄/Ag₃PO₄/γ-Al₂O₃>g-C₃N₄/Ag₃PO₄/glass>Ag₃PO₄/γ-Al₂O₃>Ag₃PO₄/glass,DBD combined with g-C₃N₄/Ag₃PO₄/γ-Al₂O₃ photocatalyst has the best toluene degradation effect.In the experiment of DBD combined with g-C₃N₄/Ag₃PO₄/γ-Al₂O₃ photocatalyst to degrade toluene,with the increase of applied voltage from 5k V to 9k V,the degradation efficiency of toluene showed an upward trend,the discharge power and energy density also increased,and the energy efficiency showed a downward trend;As the power frequency increases from 5k Hz to 9k Hz,the degradation efficiency of toluene increases first and then decreases,the discharge power and energy density also increase first and then decrease,and the energy efficiency first decreases and then increases.When the power frequency is 7k Hz,the degradation efficiency with the increase of the initial concentration of toluene and the gas flow rate,the degradation efficiency of toluene showed a downward trend,and the combined technology could reduce the decline and play a buffering role.The photocatalysts were characterized by BET,XRD,SEM,UV-Vis DRS and XPS.The results show that there is a strong interaction between g-C₃N₄and Ag₃PO₄,which form a Z-type heterostructure and reduce the electron-hole pair The recombination rate of toluene was improved,thereby improving the degradation efficiency of toluene in the DBD reactor.By monitoring the changes in the production of CO₂ and O₃ produced by the degradation of toluene,the complete degree of toluene degradation was explored.The results showed that with the increase of the applied voltage,the concentrations of O₃and CO₂ showed an upward trend.DBD combined with g-C₃N₄/Ag₃PO₄/γ-Al₂O₃ light Compared with other reactors for the degradation of toluene,the catalyst produced the least O₃ at 2.85 mg/L,and the highest CO₂,with a selectivity of 40.2%.The reaction process was analyzed by a simplified reaction kinetic model,and the mechanism of toluene degradation by dielectric barrier discharge combined with g-C₃N₄/Ag₃PO₄ photocatalyst was explored.The degradation process mainly degrades toluene through the dielectric barrier discharge reaction and the photocatalytic reaction:first,with the increase of the applied voltage,the high-energy active substances in the reactor increase,so that the toluene degradation is more complete;at the same time,the redox cycle between O₂/·O₂^-and OH/·OH in the g-C₃N₄/Ag₃PO₄ photocatalyst promoted the redox cycle The generation of surface active substances was improved,and the degradation performance of toluene was improved.