Post-discharge treatment of air effluents polluted by butyl-mercaptan: the role of nitrate radical

Abstract

Dry air polluted by butyl-mercaptan was treated in a Dielectric Barrier Discharge (DBD) reactor at atmospheric pressure using air as plasmagene gas in discharge and postdischarge modes. The energy density was varied between 200 to 1300 J/L. To assess the treatment efficiency, the concentrations of buty-mercaptan, total Volatile Organic Compounds (VOCs) and SO 2 were determined in the exhaust gas. Whatever the energy density was, the treatment efficiency was better in post-discharge mode. The butyl-mercaptan could be completely eliminated from 400 J/L and SO 2 selectivity was always low, below 10%. Measurements of CO, CO 2 and total VOCs indicated that 50 to 70% of the reaction products were condensed on the reactor wall in the form of micro-droplets, depending on the energy density. FTIR and XPS techniques were used to characterize the reaction products which were soluble in water. These analyses indicated that the reaction products contain oxygen, nitrogen and sulphur in an oxidized form. A reaction mechanism involving hydrogen abstraction from the-SH bond by the nitrate radical was proposed, pointing out the important role of nitrate radicals NO 3 in the reactivity of air flowing post-discharge.

The effect of ionization energy and hydrogen weight fraction on the non-thermal plasma volatile organic compounds removal efficiency

“…The O and OH are the most active species which will oxidize the original VOCs molecules into small molecule intermediates and finally convert them into CO 2 and H 2 O in ideal circumstance [37][38][39], and the quenching of the metastable state N 2 (A 3 + u ) is also an important pathway for the VOCs remediation [40][41][42]. For instance, the following reactions exist in propane plasma degradation [43]:…”

Self-cleaning, maintenance-free aerosol filter by non-thermal plasma at atmospheric pressure

“…Those mechanisms are already known and have been used for the treatment of low concentrated volatile organic compound (VOC) at ppm levels [4,6,[28][29][30][31][32][33][34][35][36]. At high frequency (60 kHz), the increase of dielectric surface temperature reaches 200 • C and assists the surface cleaning.…”