Combined Plasma Degradation Of Volatile Organic Compounds

Volatile Organic Compounds(VOCs) have extensive sources. Recently, it has already become one of the main atmospheric pollutants. Dielectric barrier discharge(DBD) plasma technology is a relatively mature and feasible VOCs control technology. In recent years, there are a lot of studies on the degradation of VOCs with DBD, while most of which were confined to the degradation under static or low flow rate condition, leading to unable to industrial application for waste gas treatment. This paper studied the efficiency of DBD on the degradation of VOCs under the condition of high velocity and used a new technology called combination plasma photolysis(CPP) to degrade the toluene gas. The degradation products were analyzed and the reaction mechanism was speculated. The main research results are as follows:(1) The decomposition of organic amine under high flow rate was investigated via DBD technology. Different parameters including removal efficiency, energy yield, carbon balance and CO2 selectivity, secondary products, as well as degradation mechanisms were investigated. The experimental results showed that removal efficiency of methylamine and dimethylamine increased with increasing applied voltage and and decreased with increasing gas flow rate. Removal efficiency of methylamine exhibit positive correlation with initial concentration, while dimethylamie removal efficiency has no obvious dependence on initial concentration. The energy utilization rises as the applied voltage reduces or the initial concentration rises. Under the condition of : gas flow rate=16.7m3/h, initial concentration=9600mg/m3, applied voltage=9k V, the highest removal efficiency for methylamineand dimethylamine was 86.6%,and 94.3%, respectively.(2) The removal rates of DBD to toluene, acetone, ethyl acetate rise with the applied voltage and decrease with gas flow rate and initial concentration. The removal efficiency of mixture of above three gases was higher than single gas under the same condition. In addition, removal efficiency of single gas decrease in the order: acetone>ethyl acetate>toluene. When the applied voltage is 9.0 k V and the initial concentration is500 mg/m3,the removal efficiency of toluene, acetone and ethyl acetate achieve maximum, the levels were25.5%,57.4%,51.7% for single gas, and 78.6%,88.8% and 59.8% in mixture.(3) The removal rate of CPP for toluene rises with the applied voltage and decreases with gas flow rate and initial concentration. At the same specific energy density, removal efficiency of toluene was higher with CPP than the sum of DBD and UV, demonstrating synergistic effects taking place. Under the same conditions, CPP represented higher performance than DBD alone with respect to energy yield, carbon balance and CO2 selectivity, and it can inhibit byproducts formation.