Degradation of anti-inflammatory drug dexamethasone by pulsed corona discharge: The effect of peroxycompounds addition

Abstract

The oxidation of anti-inflammatory dexamethasone (DXM) in water was experimentally studied using a gas-phase pulsed corona discharge (PCD) with the addition of extrinsic oxidants: peroxydisulfate (PDS), peroxymonosulfate (PMS), and hydrogen peroxide (H2O2), aiming the increased energy and overall treatment efficiency. The effects of pH, the dose of supplementary oxidant, and the composition of real water matrix on the efficiency of DXM oxidation were established. For PCD and the PCD/oxidant combinations, a faster and more complete degradation of DXM was observed in acidic media. In neutral media, the PCD/PDS process showed the highest TOC removal and energy efficiency of DXM oxidation. Overall, the carefully optimized dose of extrinsic oxidant resulted in a perceptible improvement of oxidation efficiency in PCD/PDS and PCD/H2O2 combinations compared to PCD under similar treatment conditions. In the groundwater matrix, the use of PCD/PDS and PCD/H2O2 combinations demonstrated considerably faster DXM degradation and mineralization at higher efficiency. The results of this study contribute to the possible application of combined PCD/oxidant processes for efficient removal of DXM from polluted water matrices.