Indigo carmine degradation in water induced by a pulsed positive corona discharge in air: discharge and post-discharge effects

M FERREYRA; B. FINA; N. J. MILARDOVICH; J. C. CHAMORRO; B. SANTAMARÍA; K. BALESTRASSE; L. PREVOSTO

Plasma

MDPI

Año: 2022 vol. 5 p. 265 - 279

In recent years, one of the fastest growing technological applications in the field of nonthermalplasmas is the degradation of organic contaminants of water. In this work, the degradation ofindigo carmine (IC) in water induced by a pulsed positive corona discharge operating in ambientair is reported. Degradation levels in different volumes of IC in solution with distilled water treatedwith different plasma exposure times immediately after discharge (0 h), and in the postdischargeup to 24 h were examined. To explain the IC discoloration in the postdischarge phase, a chemicalmodel was developed. The stability of the reactive species in solution nitrate, nitrite and hydrogen peroxide (H2O2), as well as the properties of the solution (electrical conductivity, pH) were also measured. The results suggest that the hydroxyl radical as well as ozone are the main oxidizing species during the discharge phase, being primarily formed in the gas phase through plasma-mediated reactions and then transferred to the liquid by diffusion, while the OH˙ productionin the bulk liquid through the decomposition of peroxinitrous acid (O=NOOH) plays a major role inthe IC degradation during the postdischarge. These results are associated with a noticeably increase in the energy-yield values observed at 24 h post-treatment.