Catalytic Degradation of Bisphenol A with a Magnetically Recoverable Geopolymer Composite Using Coal Gangue

The widespread presence and use of Bisphenol A (BPA) in aquatic environments has caused significant ecological damage. Coal gangue (CG), a byproduct of coal mining, poses a major environmental concern due to its vast land occupation and potential for pollution. A magnetic recyclable geopolymer (MnFe₂O₄-CGP) using coal gangue geopolymer (CGP) as the carrier was successfully synthesized and was evaluated for its ability to Fenton-like degrade BPA. The characterization techniques revealed the successful incorporation of spherical MnFe₂O₄ onto the CGP surface and that CGP serves as an excellent platform for the immobilization and dispersion of MnFe₂O₄. The degradation rate reached 100% within 60 min at pH = 5, 15 mmol/L H₂O₂, 0.6 g/L catalyst, and 50 mg/L BPA, significantly higher than MnFe₂O₄ and CGP alone. It was indicated that the degradation rate of BPA in MnFe₂O₄-CGP composites was 0.1121 min^-1, which was consistent with the first-order kinetic model. The saturation magnetization of MnFe₂O₄-CGP was measured to be 10.96 emu/g, enabling convenient recovery. MnFe₂O₄-CGP exhibited excellent stability, as the degradation rate of BPA remained above 95% even after five reaction cycles. This efficiency may be due to the MnFe₂O₄-CGP induced generation of reactive radicals. Quenching and EPR radical trapping experiments unequivocally confirmed that the reactive radical was hydroxyl radical (•OH). These results indicate that MnFe₂O₄-CGP has potential application prospects as a magnetic recyclable geopolymer composite in Fenton-like catalysis.