气–液隔膜放电降解水中偶氮染料艳红B的研究

Study on Degradation of Azo Dye Brilliant Red B Using Gas-liquid Diaphragm Discharge in Water

为了探究气–液隔膜放电等离子体对水中偶氮染料艳红B的降解效果,用紫外–可见吸收光谱法分析了放电过程中染料结构的变化。考察了放电孔数、底物初始质量浓度、自由基清除剂Na2CO3、异丙醇的添加对艳红B降解效果的影响;研究了降解过程中溶液pH值、电导率以及化学需氧量(COD)的变化,并分析了艳红B降解的动力学特征。在输入能量一定时,艳红B降解速率随放电孔数的增加而微弱升高;在初始质量浓度分别为30、50、100mg/L的艳红B水溶液经过20min放电处理后降解率分别达到91.13%、88.92%、85.35%;羟基自由基清除剂的添加对艳红B的降解具有一定的抑制作用,表明·OH是放电反应过程中降解艳红B的重要活性物质。随着放电处理的进行,溶液的电导率升高、pH值下降,COD先升高后下降。降解过程符合拟一级动力学规律。

In order to study the degradation effect of gas-liquid diaphragm discharge plasma on aqueous azo dye brilliant red B, the change of the dye structure during the discharge was analyzed by UV-Vis absorption spectroscopy. Effects of the number of discharge holes, initial substrate concentration, and addition of radical scavengers (Na2CO3 and isopropanol alcohol) on the degradation were examined. Variations of pH, conductivity, and chemical oxygen demand(COD) in the course of discharge treatment and the characteristic kinetics of degradation were recorded and analyzed. The results show that the degradation rate of brilliant red B will increase with increasing the number of discharge holes under the constant energy input. After 20 min of discharge, the removal rates are 91.13%, 88.92% and 85.35% when the initial concentrations are 30 mg/L, 50 mg/L, and 100 mg/L, respectively. The addition of Na2CO3 and isopropanol alcohol as hydroxyl radical scavengers will decrease the degradation rate to some extent,indicating that hydroxyl radicals are important species in the degradation of brilliant red B. The conductivity of the solution will increase, pH will decrease, and the COD will increase first and then decrease during the discharge process. The degradation of brilliant red B follows the pseudo first-order kinetics.