Hexagonal prism-like Fe1−xS@SC nanorod derived from MIL-88A (Fe) as peroxydisulfate activator for tetracycline degradation: Performance and mechanism

[Display omitted] •Magnetic Fe1−xS@SC nanorods were synthesized by sulfurizing MIL-88A (Fe).•Both radical pathway and nonradical pathway were proposed for TC degradation in Fe1−xS@SC/PDS system.•The synergistic effect of Fe1−xS and SC increased the 1O2 production.•The structure–activity relationship between graphitization and catalytic activity was built. Magnetic Fe1−xS@SC nanorods were synthesized by sulfurizing MIL-88A (Fe) and utilized to activate peroxydisulfate (PDS) for the degradation of tetracycline (TC). The superior catalytic performance of Fe1−xS@SC can be attributed to its close contact interface, high electron density, and excellent electron transfer conductivity. Both radical pathway (SO4−, OH, O2−) and nonradical pathway (1O2) were found to be responsible for the degradation of TC in Fe1−xS@SC/PDS system, with the electron transfer played a crucial role. Importantly, a high linear correlation (R2 = 0.9153) between the level of carbon defect and the reaction rate constant confirmed the structure–activity relationship between graphitization and catalytic activity. The Fe1−xS@SC/PDS system has the advantages of strong anti-interference ability (Cl−, NO3−, HA), broad applicability, recyclability, and low PDS consumption. Furthermore, possible degradation pathways of TC were proposed and the toxicity of intermediates was evaluated. This study provides novel insight into carbon materials and iron sulfide to purify antibiotic-contaminated wastewater by activating PDS.