The biochar-supported iron-copper bimetallic composite activating oxygen system for simultaneous adsorption and degradation of tetracycline

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2020-12, Vol.402, p.126039, Article 126039
• Main Authors: Liu, Jiale, Luo, Kun, Li, Xiaoming, Yang, Qi, Wang, Dongbo, Wu, You, Chen, Zhuo, Huang, Xiaoding, Pi, Zhoujie, Du, Wenjie, Guan, Zhiling
• Format: Article
• Language: English
• Subjects: BC-FeCu; Biochar; Environmental persistent free radical; Iron-copper bimetals; Reactive oxygen species; Tetracycline
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.126039

[Display omitted] •TC can be removed by BC-FeCu through adsorption, direct and indirect degradation.•EPFRs and transition metals can activate O2 to generate O2•− to degrade TC.•Single-electron transfer from BC-FeCu to O2 was a possible activation mechanism.•Sp2CC, sp3C–C, C–O and CO in BC-FeCu were the active sites for TC degradation. An economical biochar-supported iron-copper bimetallic composite (BC-FeCu) was successfully prepared and used to remove tetracycline (TC) from water. The experiment results expressed that BC-FeCu exhibited higher removal (92.50%) than FeCu (67.30%) under the same condition (pH 4.50, TC concentration 10 mg/L, and catalyst dose 0.05 g/L). Moreover, the TC removal by BC-FeCu constantly increased with the pH value from 4.50 to 9.03. Desorption experiments showed that adsorption and degradation accounted for 26.09% and 73.91% of the total TC removal by BC-FeCu, respectively. N2 sparging experiments concluded that the degradation led by dissolved oxygen (DO) and the direct degradation by BC-FeCu accounted for 17.02% and 56.89% of the total TC removal, respectively. The existence of O2•−, •OH, 1O2 was testified by electron spin resonance (ESR) analysis. And O2•− was proved to be the dominating active substance for TC degradation by BC-FeCu through quenching experiments. It could be that the electron transferred from –COOH, –OH and Cu/Cu+ in BC-FeCu to O2 to form O2•−, thus realizing the activation of O2. Finally, three possible TC degradation ways were presented through the analysis of eight intermediates.