The roles of oxygen and chloride in the degradation efficiency and mechanism of Basic Violet 16 by liquid glow discharge plasma

Abstract

The degradation of Basic Violet 16 (BV16) dye in the aqueous solution by a novel Liquid Glow Discharge Plasma (LGDP) combined with KCl (supporting electrolyte) and oxygen (additive) was systematically investigated. Experimental results showed that the LGDP/Cl−/O2 system significantly facilitated the degradation of BV16 due to the involvement of UV irradiation and reactive species (e.g., HO⋅ and H2O2). The decolorization rate of BV16 reached up to 96.2% in 10 min with the TOC removal being 50.6% in 120 min. Meanwhile, reactive oxygen species (ROS) and reactive chlorine species (RCS) generated in the system were detected, and results show that oxygen injection was beneficial to accelerate the production of ROS. The transformation intermediates upon the degradation of BV16 by the LGDP process were monitored. Accordingly, the decay pathway of BV16 in the LGDP system was proposed, i.e., the cleavage of the C=C double bond of BV16 led to the formation of simple aromatic compounds, while further reaction gave rise to the ring opening compounds with the production of some low molecular weightacids (e.g., formic acid, acetic acid, lactate acid, and succinic acid), some of which could eventually be mineralized to CO2, H2O, and NH4+.