Heterogeneous activation of peroxymonosulfate by a biochar-supported CoO composite for efficient degradation of chloramphenicols.

Herein, a new peroxymonosulfate (PMS) activation system was established using a biochar (BC)-supported CoO composite (CoO-BC) as a catalyst to enhance chloramphenicols degradation. The effects of the amount of CoO load on the BC, CoO-BC amount, PMS dose and solution pH on the degradation of chloramphenicol (CAP) were investigated. The results showed that the BC support could well disperse CoO particles. The degradation of CAP (30 mg/L) was enhanced in the CoO-BC/PMS system with the apparent degradation rate constant increased to 5.1, 19.4 and 7.2 times of that in the CoO/PMS, BC/PMS and PMS-alone control systems, respectively. Nearly complete removal of CAP was achieved in the CoO-BC/PMS system under the optimum conditions of 10 wt% CoO loading on BC, 0.2 g/L CoO-BC, 10 mM PMS and pH 7 within 10 min. The CoO/BC composites had a synergistic effect on the catalytic activity possibly because the conducting BC promoted electron transfer between the Co species and HSO and thus accelerated the Co/Coredox cycle. Additionally, over 85.0 ± 1.5% of CAP was still removed in the 10th run. Although both SO and OH were identified as the main active species, SO played a dominant role in CAP degradation. In addition, two other chloramphenicols, i.e., florfenicol (FF) and thiamphenicol (TAP), were also effectively degraded with percentages of 86.4 ± 1.3% and 71.8 ± 1.0%, respectively. This study provides a promising catalyst CoO-BC to activate PMS for efficient and persistent antibiotics degradation.