Efficient oxidation of ibuprofen by the Fe(III)/CaSO3 system: Assessment of key factors and elucidation of mechanism

This study employs the Fe(III)/CaSO 3 system to degrade ibuprofen (IBP) and elucidate the key factors and mechanisms. Negligible IBP degradation is observed when CaSO 3 and Fe(III) are applied individually, but their combination significantly enhances it. At initial pH 3, 40 μΜ Fe(III), and 200 μM sulfite, 92.2% of IBP was removed within 20 min. Quenching experiments indicated that SO 4 •– , •OH, and 1 O 2 collectively governed the degradation of IBP in the Fe(III)/CaSO 3 system. Additionally, dissolved oxygen is essential in the system by initiating the radical chain reactions. The degradation of IBP by the Fe(III)/CaSO 3 system is influenced by key operational parameters and the water matrix. Typically, the process exhibits optimal Fe(III) and sulfite concentrations and initial pH, an activation energy of 51.2 kJ·mol -1 , and is inhibited by common water constituents like humic acid (HA), Cl⁻, Br⁻ and Mg 2+ . Integrated LC/TOF/MS and DFT calculations identified hydroxylation and decarboxylation as the primary pathways for IBP degradation, with bioassays confirming decreased antibacterial activity due to toxic products. Overall, our finding indicate that the Fe(III)/CaSO 3 system is effective for the oxidation of IBP, but the process parameters need further optimization to enhance IBP degradation efficiency and reduce potential environmental risks. • CaSO 3 outperforms Na 2 SO 3 as a superior sulfite source in the Fe(III)/sulfite process for IBP degradation. • Quenching experiments indicate that SO 4 •– , •OH, and 1 O 2 collectively govern IBP degradation. • Process efficiency relies on optimal parameters but is hindered by water matrix components, needing further optimization. • Hydroxylation and decarboxylation are key pathways, producing toxic byproducts that decrease antibacterial activity.