37 / 2023-04-30 00:32:25

Resource utilization of steel mill sludge to prepare biochar as peroxysulfate activator for highly efficient degradation of tetracycline in water

Biochar; Iron-rich sludge; Peroxysulfate; Tetracycline degradation; Mechanism

 Iron-rich sludge, an inevitable byproduct of wastewater treatment in the steel industry, is posing challenges in terms of disposal, high treatment costs, and significant environmental hazards. In this study, we utilized iron-rich sludge as the raw material to prepare iron-enriched biochar (FSB) and investigated the high catalytic activity of FSB as a catalyst for the activation of peroxysulfate (PS) to degrade tetracycline (TC). Batch experimental results showed that under optimal conditions, including FSB dosage of 0.4 g L^-1, initial solution pH 3, and PS dosage of 8 mM, the FSB/PS system exhibited the highest removal efficiency for TC, reaching 85.44%. Mechanistic studies revealed that active oxygen species, such as SO₄˙ˉ, ·OH, and O₂˙ˉ, played crucial roles in the TC degradation. Further analysis indicated that the functional groups and defect structures with high redox potentials on the surface of FSB450 facilitated electron transfer from the FSB to PS, thereby reducing the chemical bond energy of O-O bond (SO₄-SO₄) in PS, making it more susceptible to breakage and generating radicals. Moreover, the metal oxides could also activate PS to produce SO₄˙ˉ. Finally, the degradation pathway and products of TC were elucidated through LC-MS analysis. This study offers a novel and feasible approach for utilizing iron-rich sludge and exploiting the catalytic properties of derived biochar.