Performance and degradation pathway of florfenicol antibiotic by nitrogen-doped biochar supported zero-valent iron and zero-valent copper: A combined experimental and DFT study

• Published in: Journal of hazardous materials 2023-10, Vol.459, p.132172-132172, Article 132172
• Main Authors: Tang, Zheng, Kong, Yifan, Qin, Yan, Chen, Xiaoqian, Liu, Min, Shen, Lu, Kang, Yanming, Gao, Pin
• Format: Article
• Language: English
• Subjects: Dechlorination; Defluorination; Density functional theory; Fe/Cu@NBC; β-elimination
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.132172

Fluorinated compounds are a class of organic substances resistant to degradation. Although zero-valent iron (Fe0) has a promising reducing capability, it still fails to degrade fluorine-containing antibiotics (i.e., florfenicol) efficiently. In this study, we applied a simple one-pot pyrolytic approach to synthesize nitrogen-doped biochar supported Fe0 and zero-valent copper (Cu0) composite (Fe/Cu@NBC) and investigated its performance on florfenicol removal. The results clearly showed that approximately 91.4% of florfenicol in the deionized water was removed by Fe/Cu@NBC within 8 h. As the reaction time was extended to 15 d, the total degradation rate of florfenicol reached 96.6%, in which the defluorination and dechlorination rates were 73.2% and 82.1%, respectively. Both experimental results and density functional theory calculation suggested that ∙OH and ·O2− triggered β-fluorine elimination, resulting in defluorination prior to dechlorination. This new finding was distinct from previous viewpoints that defluorination was more difficult to occur than dechlorination. Fe/Cu@NBC also had a favorable performance for removal of florfenicol in surface water. This study provides a new insight into the degradation mechanism and pathway of florfenicol removal in the Fe/Cu@NBC system, which can be a promising alternative for remediation of fluorinated organic compounds in the environment. [Display omitted] •Fe/Cu@NBC was successfully synthesized with a simple one-pot pyrolytic approach.•An efficient florfenicol removal as high as 91.4% was achieved within 8 h.•·O2− played a dominant role in the defluorination of florfenicol via β-elimination reaction.•Florfenicol degradation pathway followed firstly defluorination and subsequent dechlorination.