Dielectric barrier discharge plasma for chlorobenzene removal: Performance optimization, process modeling, and toxicity evaluation

Abstract

Bio-purification has been recognized as an effective method of removal of volatile organic pollutants (VOCs), yet exist a technical bottleneck of low removal efficiency in the treatment of high toxicity and low water-soluble VOCs, especially chlorobenzene (CB). Herein, dielectric barrier discharge (DBD) technology was used as a pre-treatment technology, and the effect of process parameters (specific input of energy (SIE), inlet concentration of CB, humidity, and discharge length) of DBD on the removal performance of CB was analyzed, in order to investigate the feasibility of DBD as a pre-treatment approach for bio-purification. Taking energy yield, by-product analysis and exhaust evaluation as considerations, an SIE of 1,131.57 J·L-1, an inlet CB concentration of 300 ppm, a humidity of 50 %, and a discharge length of 10 cm were selected as the most suitable experimental conditions for the air DBD reactor. The temperature of gas flow was analyzed. Results suggested that DBD have no adverse thermal effect on the subsequent biotechnology (decreased by about 8 K during the discharge process). The temperature change caused by the degradation of CB (e.g., phenyl ring-opening and other processes) accounts for about 90 % of the total temperature change, where remaining part of temperature decreased caused by the large number of active substances produced by electron excitation, collision and cracking during discharge. The regulation of short-life active substances (e.g., ·NO, ·NO2,·OH, and O2–·) further reduced the toxicity of the outlet gas generated by DBD through affect the contents the long-life active substances (e.g., H2O2, and O3). This study provides a better understanding of the feasibility of DBD as a treatment for bio-purification and a new coupling technology for the effective removal of CB.