A novel multi array dielectric barrier discharge plasma gas diffuser for wastewater treatment: The role of reactive species

Abstract

Employment of efficient and economical methods for recovery of water has come into sharp focus regarding the growing demand for fresh water which has led to water crisis in a recent past. In this respect, cold atmospheric plasma technology has recently attracted scholars’ attention due to its various chemical and physical effects which can contribute to the removal of contaminations in wastewater. Although the energy efficiency and the rate of pollution elimination from water have been studied extensively, only few studies have been conducted on reactive species that play a major role in eliminating pollution. We studied the chemical reactive species involved in the decomposition of crystal violet (CV), a model organic compound, by a novel multi array dielectric barrier discharge (MADBD) plasma gas diffuser. The plasma generated gas mixture immediately contacts with the water in the form of gas bubbles to insure a good mass transfer between short and long live reactive species and water. Effects of operating parameters including electrode length, input power, flow rate, and solution volume over CV decolorization and energy efficiency were investigated. Experimental results showed that for the best operating conditions decolororization, energy efficiency, and CV decolorization rate constant were 95%, 7.8 g/kWh, and 2.83 min−1, respectively. An investigation of positive control experiments and the effect of scavengers of relevant reactive species reveal that the most key reactive species leading to the CV decolorization in MADBD plasma was ozone (O3) while short live species and reactive nitrogen species had small effect on CV degradation.