MOF-templated synthesis of CoFe₂O₄ nanocrystals and its coupling with peroxymonosulfate for degradation of bisphenol A

Porous magnetic cobalt ferrite nanocrystals (CoFe₂O₄ NC) are synthesized via a one-step process by using bimetal-organic frameworks (Co/Fe bi-MOFs) as a template for the catalytic degradation of bisphenol A (BPA). The properties of the prepared catalyst are evidenced by a series of characterization techniques. Overall, the unique ferromagnetic nature (34.73 emu/g) make its efficient separation from the liquid phase possible. CoFe₂O₄ NC activates peroxymonosulfate (PMS) to degrade BPA more efficiently than hydrothermally fabricated CoFe₂O₄ nanoparticles. The difference in catalytic capacity is attributable to the larger specific surface area (60.4 m² g⁻¹) and well developed mesoporous structure (0.64 cm³ g⁻¹) of the CoFe₂O₄ NC. EPR analysis demonstrate the production of HO^[rad] and SO₄^[rad]− radicals in the CoFe₂O₄ NC/PMS system. The degradation process positively correlates with the increase of initial solution pH, catalysts dosage, and PMS dosage. The degradation rate of 0.112 min⁻¹ is achieved at [PMS]/[BPA] of 10, catalyst dosage of 0.1 g L⁻¹, temperature of 25 °C, and initial pH of 10.2 in deionized water. The existence of Cl^- and HCO₃⁻/CO₃²⁻ show significant positive synergistic effects on the catalytic process. Moreover, simple thermal treatment at 400 °C for 15 min in open air fully regenerates the catalytic capacity of CoFe₂O₄ NC for reuse. Findings from this work shed light on the rational design of bimetallic oxide catalysts and provide new insight into the development of high-performance magnetic separable catalysts.