Acceleration of Fenton-like Reaction by Bimetal-Mediated Sludge Biochar for Tetracycline Removal

The production of sludge biochar (SBC) from residual sludge offers a solution to the challenges associated with sludge disposal and facilitates the reutilization of resources. In the present research, a bimetallic-modified sludge biochar, designated as FeCu-SBC, was synthesized by varying the doping ratios of FeSO₄ and CuSO₄. This material was intended for the effective degradation of tetracycline (TC) in aqueous environments via the activation of peroxydisulfate. The FeCu2-SBC (90% degradation rate) composite, synthesized through the incorporation of Fe and Cu in a 1:2 ratio with SBC, exhibited a degradation rate of TC, which was 2.7 times higher than that of SBC (32.85% degradation rate) and 1.8 times higher than that of FeCu (50% degradation rate). Research examining the mechanisms involved revealed that FeCu underwent degradation solely through the radical (^•OH) pathway, whereas FeCu2-SBC was subject to degradation through both radical (SO₄^•-) and nonradical (¹O₂) pathways. This phenomenon was attributed to the distinct π-π, C═O, and defect structures in FeCu2-SBC compared to FeCu, which facilitated the activation process leading to the production of reactive species. This investigation presented a cost-effective approach for producing bimetallic-modified sludge biochar, offering perspectives on determining the crucial elements influencing the streamlined TC degradation pathway.