Degradation of bisphenol F by activated of peroxymonosulfate using sludge biochar loaded with cobalt iron bimetallic catalyst

In recent years, the large-scale construction of wastewater treatment plants has led to an increase in the production of sludge year after year, and the treatment of sludge is facing a serious challenge. Bisphenol F (BPF), which is widely used as a chemical additive in the industry, has been frequently detected in surface water, soil and sludge. By using municipal sludge loaded with cobalt-iron bimetal, cobalt-iron bimetallic@biochar composites (CoFeO@SBC) were prepared, and the catalytic performance was assessed by activating peroxymonosulfate (PMS) to degrade BPF. Scanning electron microscopy (SEM), specific surface area determination (BET), infrared spectroscopy (IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterise and analyse the physicochemical properties of the prepared materials. The effects of the dosage of the materials, the dosage of the PMS, the initial pH, and the inorganic anions on the degradation of the BPF by the CoFeO@SBC/PMS system were investigated. The results showed that the pore structure of CoFeO was significantly improved after compounding with SBC, and the specific surface area was increased by 6.0 times. Moreover, CoFeO@SBC composites showed richer oxygen vacancies and —OH functional groups, which led to higher production of Fe(II) and Co(II). Therefore, CoFeO@SBC composites had excellent catalytic activity, which could almost completely degrade BPF (5 mg/L) within 10 min at the dosage of 0.04 g/L, and the degradation rate was 62% higher than that of CoFeO; Cl⁻ and NO³⁻ showed less influence on the degradation effect of the system, while HCO₃⁻ had a significant inhibitory effect; EPR analysis shows that there are hydroxyl (·OH) and sulfate ($\mathrm{SO}_4 ^{\cdot-} $) free radicals as well as singlet oxygen (¹O₂) and superoxide ($\mathrm{O}_2 ^{\cdot-} $) free radicals in the CoFeO@SBC/PMS system. At the same time, the free radical quenching experiment, it is proved that $\mathrm{SO}_4 ^{\cdot-} $ is the key reactive oxygen species for the degradation of BPF in the system. Finally, the degradation products of BPF were identified by liquid chromatography-mass spectrometry (LC-MS), which could elucidate the primary degradation pathways and mechanisms in CoFeO@SBC/PMS system.