Elevated degradation of di-n‑butyl phthalate by activating peroxymonosulfate over GO[sbnd]CoFe₂O₄ composites: Synergistic effects and mechanisms

Rational design of heterogeneous catalysts with high activity and stability is crucial in peroxymonosulfate (PMS)-based oxidation treatment of wastewater. Herein, the graphite oxide-cobalt ferrite (GO-CoFe₂O₄) composite was constructed, and its morphological, component and structural characteristics were thoroughly examined, respectively. GO-CoFe₂O₄ obviously boosted PMS catalytic performance on di-n‑butyl phthalate removal (DBP, R_DBP = 90%, R_TOC = 37%), which indicated by the first-order kinetic constant (k_DBP = 0.060 min⁻¹) being roughly 4 times than pure CoFe₂O₄ (k_DBP = 0.015 min⁻¹). The fabrication of GO-CoFe₂O₄ brought the favorable stability and repeatability up to six cycles. Moreover, the method of batch dosing catalyst was creatively proposed to improve the PMS utilization efficiency. The coupling of GO enhanced the dispersion of CoFe₂O₄ particles to obtain sufficient active sites, additionally, the plentiful C=O groups and free-flowing electrons on GO promoted GO-CoFe₂O₄ to coordinate a redox process during PMS activation. With the aid of theoretical calculations, GO-CoFe₂O₄ was revealed to exhibit a strong affinity toward PMS adsorption, where PMS spontaneously dissociated into sulfate radical (SO₄^•−), hydroxyl radical (^•OH) and singlet oxygen (¹O₂), acting as the reactive oxygen species (ROSs). Electrons cycling between Co, Fe and O species ensured continuous ROSs generation and excellent catalytic performance.