Efficient removal of estradiol using MnFe₂O₄ microsphere and potassium persulfate complex salt

In this study, MnFe₂O₄ microspheres were synthesized to activate potassium persulfate complex salt (Oxone) for the degradation of 17β-estradiol (17β-E2) in aqueous solutions. The characteristic of MnFe₂O₄ was detected by XRD, XPS and SEM-EDS. The experimental results indicated that the degradation of 17β-E2 followed pseudo-first-order kinetics. At 25 °C, 17β-E2 concentration of 0.5 mg/L, MnFe₂O₄ dosage of 100 mg/L, Oxone dosage of 0.5 mmol/L, and initial pH value of 6.5, the decomposition efficiency of 17β-E2 reached 82.9% after 30 min of reaction. Additionally, free radical quenching experiments and electron paramagnetic resonance analysis demonstrated that SO₄^-• and •OH participated in the reaction process of the whole reaction system, with SO₄^-• being the main reactive oxygen species (ROS). The activation mechanism of the MnFe₂O₄/Oxone/17β-E2 system is proposed as follows: MnFe₂O₄ initially reacts with O₂ and H₂O in solution to generate active Fe³⁺-OH and Mn²⁺-OH species. Subsequently, Fe³⁺-OH and Mn²⁺-OH react with Oxone in a heterogeneous phase activation process, producing highly reactive free radicals. After four cycles of MnFe₂O₄ material, the removal rate of 17β-E2 decreased by 24.1%.