Novel cow dung-doped sludge biochar as an efficient ozone catalyst: Synergy between graphitic structure and defects induces free radical pathways

Yuxuan Yang; Kedong Ma; Yubo Cui; Ke Zhao; Yuning Lu; Wanjun Zhang; Peijing Kuang; Xuejun Zou

doi:10.1016/j.envres.2024.118747

Novel cow dung-doped sludge biochar as an efficient ozone catalyst: Synergy between graphitic structure and defects induces free radical pathways

Environ Res. 2024 Mar 25;251(Pt 2):118747. doi: 10.1016/j.envres.2024.118747. Online ahead of print.

Authors

Yuxuan Yang¹, Kedong Ma², Yubo Cui³, Ke Zhao⁴, Yuning Lu¹, Wanjun Zhang¹, Peijing Kuang¹, Xuejun Zou¹

Affiliations

¹ Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian 116600, People's Republic of China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, People's Republic of China.
² Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian 116600, People's Republic of China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, People's Republic of China. Electronic address: makedongdl@yahoo.co.jp.
³ Key Laboratory of Biotechnology and Bioresources Utilization, Ministry of Education, Dalian Minzu University, Dalian 116600, People's Republic of China; College of Environment and Resources, Dalian Minzu University, Dalian, 116600, People's Republic of China. Electronic address: cyb@dlnu.edu.cn.
⁴ Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun, 130118, People's Republic of China.

PMID: 38527717
DOI: 10.1016/j.envres.2024.118747

Abstract

A composite material, cow dung-doped sludge biochar (Zn@SBC-CD), was synthesized by one-step pyrolysis using ZnCl₂ as an activating agent and applied to a catalytic ozonation process (COP) for methylene blue (MB) removal. SEM, XRD, FTIR, XPS and BET analyses were performed to characterize the biochar (BC) catalysts. Zn@SBC-CD had high graphitization degree, abundant active sites and uniform distribution of Zn on its surface. Complete removal of MB was achieved within 10 min, with a removal rate much higher than that of ozone alone (32.4%), implying the excellent ozone activation performance of Zn@SBC-CD. The influence of experimental parameters on MB removal efficiency was examined. Under the optimum conditions in terms of ozone dose 0.04 mg/mL, catalyst dose 400 mg/L and pH 6.0, COD was completely removed after 20 min. Electron paramagnetic resonance (EPR) analysis revealed radical and non-radical pathways were involved in MB degradation. The Zn@SBC-CD/O₃ system generated superoxide anion radicals (^•O₂^-), which were the main active species for MB removal, through adsorption, transformation, and transfer, Furthermore, Zn@SBC-CD exhibited good reusability and stability in cycling experiments. This study provides a novel approach for the utilization of cow dung and sludge in synthesis of functional biocatalysts and application in organic wastewater treatment.

Keywords: Biochar; Catalytic ozonation process; Cow dung; Sewage sludge; Superoxide radical.