Abstract:

A dielectric barrier discharge (DBD) plasma catalytic system was established at ambient temperature and pressure to investigate the effect of discharge parameters on the degradation of benzohydroxamic acid (BHA) by plasma. The catalysts prepared by hydrothermal synthesis were characterized, and the changes in total organic carbon (TOC), pH, and ∙OH radicals during the degradation were analyzed. LC-MS was used to determine the intermediates of the degradation reaction to investigate the reaction’s mechanism. Characteristics of the synthesized BiOI included a high specific surface area, a high pore volume, and high-purity mesoporous nanosheet microspheres. In addition, the DBD could change the crystalline shape and structure of the catalyst, rendering it better catalytic performance. The degradation performance results showed that peak voltage and the volume of blast gas had a significant influence on the degradation rate of BHA. The best result was achieved by adding 0.3g of BiOI catalyst to couple with DBD plasma at a BHA concentration of 80mg/L, a volume of 1000mL, a peak voltage of 24kV, a frequency of 7500Hz, and a blast volume of 30L/min. This increased the degradation rate of BHA from 78.8% to 88.2% compared to the DBD system alone. The degradation mechanism analysis showed that ∙OH was the main active reactant for BHA degradation. Under plasma catalysis, BHA is oxidized and opened to intermediates such as benzoic acid and 2-hydroxyacetic acid, leading to the generation of H₂O and CO{}_{\mathrm{3}}^{\mathrm{2}-}.

Key words: dielectric barrier discharge, plasma, waste water, degradation, mineralization rate, catalyst

摘要：

常温常压下，以苯甲羟肟酸（BHA）为处理对象建立了介质阻挡放电（DBD）等离子体催化体系。研究了放电参数对等离子体降解BHA的影响规律，对水热合成法制备的催化材料进行了系列表征分析，考察了各因素对BHA降解的影响，分析了DBD等离子体耦合催化剂降解BHA过程中总有机碳（TOC）、pH、∙OH自由基等的变化，通过液相色谱-质谱联用仪分析了降解反应过程的中间产物并探讨了BHA的降解机理。表征结果显示合成的BiOI具有高比表面积、高孔体积、高纯度的介孔纳米片微球，且DBD可以改变催化剂的晶型和结构，具有更高的催化性能。降解性能结果表明，峰值电压、鼓气量等对BHA降解率有很大影响；BHA浓度为80mg/L、体积1000mL，在峰值电压24kV，频率7500Hz，鼓气量30L/min条件下，添加0.3g BiOI催化剂与DBD等离子体耦合效果最好，相对于单一DBD体系，BHA降解率由78.8%提高到88.2%。降解机理分析可知，∙OH是BHA降解的重要活性物质，在等离子体催化作用下，BHA被氧化开环，转化为苯甲酸和乙醇酸等中间体，最终生成H₂O和CO{}_{\mathrm{3}}^{\mathrm{2}-}等。

关键词: 介质阻挡放电, 等离子体, 废水, 降解, 矿化率, 催化剂