关键词: 介质阻挡放电, 等离子体, 废水, 降解, 矿化率, 催化剂

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