Comparative study of atrazine degradation by magnetic clay activated persulfate and H₂O₂

To effectively remove the endocrine disrupting chemicals (EDCs) in water, Fe₃O₄ was loaded on the surface of modified sepiolite clay by the method of co-precipitation to catalyze potassium persulfate (K₂S₂O₈) and hydrogen peroxide (H₂O₂) respectively to generate SO₄˙^- and ·OH for atrazine (ATZ) removal. The magnetic clay catalyst was characterized by XRD, SEM, N₂ adsorption-desorption and isoelectric point. The degradation efficiency of ATZ in the two systems was systematically compared in terms of initial pH, oxidant dosage and oxidant utilization rate. The results revealed that, after 90 minutes, systems with K₂S₂O₈ and H₂O₂ can remove 65.7% and 57.8% of the ATZ under the given conditions (30 °C, catalyst load: 1 g L^-1, initial pH: 5, [ATZ]₀: 10 mg L^-1, [H₂O₂]₀: 46 mmol L^-1, [PDS]₀: 46 mmol L^-1). The magnetic clay catalyst still maintained good catalytic activity and stability during the four consecutive runs. Based on the quenching experiments, it was demonstrated that the dominant radical species in the two systems were SO₄˙^-/·OH and ·OH, respectively. However, the degradation efficiency of the two systems presented different responses toward the condition variations; the system with K₂S₂O₈ was relatively more sensitive to solution pH, the oxidant efficiency was generally higher than that of the H₂O₂ system (except 184 mmol L^-1).