Degradation of the antiviral remdesivir by a novel, continuous-flow, helical-baffle incorporating VUV/UVC photoreactor: Performance assessment and enhancement by inorganic peroxides

Abstract

Herein, the enhanced performance of the VUV process run in a helical-baffle reactor (VUV@HBR) compared with an annular reactor in degrading the antiviral remdesivir (RDV) was scrutinized. 67.9% degradation of RDV was achieved within 10 min in the VUV@HBR system, compared to 54.1% of that in the annular reactor under similar conditions. The addition of peroxymonosulfate (PMS) or hydrogen peroxide (H2O2) to the VUV@HBR considerably improved the degradation of RDV; the rate of RDV degradation for the initial 10-min reaction period in the VUV@HBR system improved from 0.124 min−1 in the absence of oxidants to 0.350 and 0.572 min−1 in the presence of optimum level of PMS and H2O2 oxidants, respectively. Selecting the VUV/H2O2@HBR as the best performing process, over 90% of RDV was eliminated within 10 min. Scavenger studies identified HO· as the main reactive species leading to RDV degradation, with a k = 4.6 x109 M−1 s−1; a plausible RDV degradation pathway was proposed. In addition, tap water and a municipal wastewater treatment spiked with RDV were efficiently treated by VUV/H2O2@HBR (90% RDV and 45% TOC removal in 10 min and 30 min, respectively). In continuous-flow mode, >99% degradation of 1 mg/L of RDV was achieved at hydraulic retention times of 1 and 5 min, for VUV/H2O2@HBR and VUV@HBR, respectively, simultaneously with a 6-log inactivation of E. coli (3 min) or the favipiravir antiviral drug (1.5 min). In overall, the developed VUV/H2O2@HBR is considered an attractive and promising technology for water and wastewater treatment.