Post-vulcanization combined with magnetic modification of sulfonated biochar as heterogeneous fenton catalyst for tetracycline degradation

Although the Fenton reaction has shown remarkable effectiveness in degrading antibiotic contamination in water bodies, its strict pH dependence has limited its wide practical application. In this study, a novel magnetic biochar material with dual functions of adsorption and catalysis was successfully synthesized by carbonization of the shell of blue flower blue with concentrated sulfuric acid through sulfide and magnetic modification. The innovation of this material is its ability to overcome the recycling limitations of traditional catalysts while achieving efficient reactions in the pH range of 3–11. In particular, the introduction of sulfur promotes a stable cycle of Fe(II)/Fe(III) in the material, thereby enhancing its catalytic properties. The porous structure of the sulphonated jacaranda hull and its successful loading of sulfur and iron were revealed by SEM, FTIR, XRD, and XPS analysis. The experimental results showed that under the conditions of S-Fe₃O₄@JSS dosage of 0.2 g/L, hydrogen peroxide concentration of 10 mM, initial pH value of 5, and initial tetracycline concentration of 50 mg/L, the optimal degradation rate of tetracycline was as high as 85.85 %. The mechanism analysis shows that hydroxyl radical plays a key role in this reaction system because S-Fe₃O₄@JSS not only releases Fe(II) but also catalyzes hydrogen peroxide with the introduction of surface acidic sites and sulfur elements, which increases the free radical yield and accelerates the tetracycline degradation process. This study provides a new efficient and stable method to solve the problem of antibiotic pollution treatment in water.