低温等离子体对复合CVOCs的降解特性

Degradation Characteristics of Composite CVOCs by Non-thermal Plasma

以难生物降解的氯苯和二氯乙烷为目标污染物,以低温等离子体作为VOCs处理技术,考察了不同频率电源条件下工艺参数对混合气体降解过程的影响,并对降解产物进行了分析,为后期与生物技术耦合提供理论依据.结果表明,高低频电源条件下等离子体中的能量效率均随着SIE的增大先升高后降低.在低频电源的等离子体中,SIE=7 167 J·L^(-1)时,能量效率最大;而在高频电源的等离子体中,SIE=6 111 J·L^(-1),能量效率达到最大.在两种频率电源的等离子体中,各组分的去除率都随着SIE的升高先增大后逐渐减小;去除率随着停留时间的延长而增大,但去除负荷却会出现降低,当停留时为5s时,高频和低频电源的等离子体中气体的去除负荷都达到最大,本实验选取5 s的停留时间进行后续的产物分析.经产物分析发现,CO_2的生成量和选择性随着SIE的升高而增大;臭氧浓度随SIE的升高而增大,高频电源的等离子体中O3生成量较大;TOC浓度随SIE的增大先增大后迅速减小,能量效率最大时产物水溶性最佳.

Non-thermal plasma was used as a pretreatment technology for bio-trickling filter, employing chlorobenzene and dichloroethane as target pollutants. This experiment was conducted to study the purification effect and degradation product in NTP under different frequency power supply,to provide a theoretical basis for coupling with biotechnology. The results showed that the removal efficiency for mixed waste gas in the plasma first increased and then decreased with the increase of the SIE. The maximum energy efficiency was obtained at 6111 J·L^-1 under high frequency power and 7167 J·L^-1 under low frequency condition, respectively. Extending residence time caused a rise in mixed gas removal efficiency, but the removal load didn＇t always increase and the highest removal load was observed with the residence time of 5 s, so 5 s was regarded as the optimal reaction condition for the subsequent analysis in this study. The degradation products were analyzed under the specific conditions. Experimental results showed that the amount and the selectivity of carbon dioxide both increased with the increase of SIE in the plasma reactor. The amount of ozone increased to a maximum value and then decreased with the increase of SIE in the plasma reactor, and the amount of ozone produced in low-frequency power plasma was lower than that in high-frequency power. The trend of TOC values was similar to the trend of ozone generation, indicating that the best water solubility was obtained at the highest energy efficiency.