Heterogeneous activation of peroxymonosulfate by a biochar-supported Co3O4 composite for efficient degradation of chloramphenicols
2020
Xu, Hengduo | Zhang, Yuechao | Li, Jiajia | Hao, Qinqin | Li, Xin | Liu, Fanghua
Herein, a new peroxymonosulfate (PMS) activation system was established using a biochar (BC)-supported Co₃O₄ composite (Co₃O₄-BC) as a catalyst to enhance chloramphenicols degradation. The effects of the amount of Co₃O₄ load on the BC, Co₃O₄-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 Co₃O₄ particles. The degradation of CAP (30 mg/L) was enhanced in the Co₃O₄-BC/PMS system with the apparent degradation rate constant increased to 5.1, 19.4 and 7.2 times of that in the Co₃O₄/PMS, BC/PMS and PMS-alone control systems, respectively. Nearly complete removal of CAP was achieved in the Co₃O₄-BC/PMS system under the optimum conditions of 10 wt% Co₃O₄ loading on BC, 0.2 g/L Co₃O₄-BC, 10 mM PMS and pH 7 within 10 min. The Co₃O₄/BC composites had a synergistic effect on the catalytic activity possibly because the conducting BC promoted electron transfer between the Co species and HSO₅⁻ and thus accelerated the Co³⁺/Co²⁺redox cycle. Additionally, over 85.0 ± 1.5% of CAP was still removed in the 10th run. Although both SO₄⁻ and OH were identified as the main active species, SO₄⁻ 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 Co₃O₄-BC to activate PMS for efficient and persistent antibiotics degradation.
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