The degradation of PCDD/Fs in fly ash using dielectric barrier discharge in a lab-scale reactor

Abstract

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in fly ash emitted by municipal solid waste (MSW) incinerators are harmful to human health and the environment. Based on the degradation efficiency and application potential of non-thermal plasma (NTP) for gaseous pollutants, a typical lab-scale dielectric barrier discharge (DBD) module was adopted to generate plasma and degrade the PCDD/Fs present in fly ash. In this study, the degradation characteristics of 17 kinds of PCDD/Fs congeners were studied, and the effects of input energy, discharge time and moisture content of fly ash on PCDD/Fs removal efficiency were also discussed in detail. The results indicated that the degradation efficiency of 2378-tetrachlorodibenzo-p-dioxin (2378-TCDD) was the highest among 17 kinds of PCDD/Fs congeners at the same operating condition, and the total degradation efficiency of PCDDs was higher than that of PCDFs. The highest degradation efficiencies of 2378-TCDD, PCDDs and PCDFs acquired in this study could be up to 92%, 83%, and 55%, respectively. A long time of electric discharge was not beneficial to the decomposition of PCDD/Fs, and the moisture content of fly ash affected the degradation of PCDDs more obviously than that of PCDFs. Also, the degradation mechanisms of PCDD/Fs were discussed further. It was discovered from results that the decomposition of PCDFs was mainly attributed to the dissociation of the C–Cl bond, while for that of PCDDs, the dissociation of the C–O bond played a dominant role rather than that of the C–Cl bond.