Pyrolysis of hydrothermally dewatering sewage sludge: Highly efficient peroxydisulfate activation of derived biochar to degrade diclofenac
2022
Wang, Teng | Zhou, Yi | Xue, Yongjie | Sang, Tianmeng | Ren, Lu | Chen, Si | Liu, Jingxin | Mei, Meng | Li, Jinping
The resource utilization of sewage sludge can solve its disposal issue essentially. Meanwhile the removal of diclofenac (DCF) in wastewater is an emerging environmental problem. In this study, a novel strategy of sludge utilizing via hydrothermal - peroxydisulfate (PDS) dewatering coupled pyrolysis process was proposed. The obtained sludge-derived biochar (HSC) could be as candidate to activate PDS to degrade DCF. Results indicated that exceed 90% of DCF was eliminated within 30 min in HSC-PDS/DCF ternary system under the optimized condition (0.6 mmol/L PDS and 0.5 mg/L HSC, without temperature and pH pre-adjusting). The inner mechanism of HSC-PDS/DCF system was revealed as follows: (1) Major: CO in quinones and ketone structure in HSC accelerated the degradation of DCF via non-radical pathway (electron transfer and ¹O₂). (2) Minor: Graphitic N structure accelerated the electron transfer and O₂•⁻ originated from defective sites involved into the redox. Several by-products were identified and two tentative degradation pathways of DCF (eg. dechlorination and C–N cleavage) were proposed.
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