Dielectric Barrier Discharge Plasma Treatment Of Formaldehyde Gas And Its Mechanism

In this paper,dielectric barrier discharge?DBD?plasma was used to degrade formaldehyde gas.The degradation of formaldehyde gas by DBD plasma and by DBD plasma coupled with?-Al₂O₃ adsorbent or MnO_X/?-Al₂O₃ catalyst were studied.The effect of discharge power,gas flow rate,initial formaldehyde concentration,energy density on formaldehyde removal rate,energy efficiency and by-product were investigated,The optimum conditions for formaldehyde degradation were determined.And the reaction process was investigated by spectroscopy.The experimental results are as follows:?1?Formaldehyde can be effectively removed by dielectric barrier discharge plasma,the removal rate of formaldehyde was about 74%,but the ozone concentration was up to 14.37mg/m³.Rector filled with?-Al₂O₃ and MnO_X/?-Al₂O₃can effectively reduced the concentration of ozone,and increased the formaldehyde removal rate and the energy efficiency of the reaction at the same time,The performance of the degradation of formaldehyde under different conditions was in the following order:MnO_X/?-Al₂O₃>?-Al₂O₃>no catalyst.When the discharge power was 20W,the gas flow rate was 500mL/min,the energy density was 2.4kJ/L,and the initial concentration of formaldehyde was 1.82mg/m³,plasma reactor filled with MnO_X/?-Al₂O₃ did best during the reaction process,the removal rate of formaldehyde was 96.37%,the energy efficiency of the reactor was 0.265g/kW·h,and the ozone concentration was 0.22 mg/m³.?2?It showed that plasma produced by air dielectric barrier discharge was consist of nitrogen active group and oxygen active group by calibrating the characteristic line of the acquired emission spectroscopy.The intensity of the characteristic line increased with the increased of discharge power or filled with catalyst can also enhanced the intensity of the characteristic line.This indicated that the addition of catalyst activated more active particles and increased the number and species of active particles.In the process of degradation of formaldehyde,the oxygen active particles played an important role.?3?By diagnosis the Plasma produced by dielectric Barrier discharge,it showed that the electron excitation temperature of Oxygen atom increased first and then decreased with the increased of discharge power.Under different conditions,the electron excitation temperatures of Oxygen atom were as follows:MnOx/?-Al₂O₃>?-Al₂O₃>no catalyst...