Heterogeneous activation of peroxymonosulfate by CoMgFe-LDO for degradation of carbamazepine: Efficiency, mechanism and degradation pathways

In this study, composite CoMgFe-LDO catalyst was synthesized from layered double hydroxides precursor and tested as a heterogeneous catalyst to activate peroxymonosulfate (PMS) for carbamazepine (CBZ) degradation. X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were used to characterize CoMgFe-LDO. CoMgFe-LDO exhibited much better catalytic performance than the control catalysts. Operational parameters of CoMgFe-LDO dosage, PMS dosage, initial solution pH and initial CBZ concentration on the degradation efficiency were investigated. Complete removal of 5 mg/L CBZ was achieved with 20 mg/L CoMgFe-LDO and 0.2 mM PMS at pH 5.8 in 20 min reaction time. Meanwhile, the inorganic anions effects in the CoMgFe-LDO/PMS system for CBZ removal and the catalytic stability were also studied. The radical scavenging experiments confirmed that both SO4− and HO were involved and SO4− played a dominant role on the CBZ degradation. In addition, the possible reaction mechanism of CoMgFe-LDO/PMS system for CBZ removal was proposed. Finally, the degradation pathways of CBZ were proposed by the CBZ degradation intermediates identified by Ultra Performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry technologies (UPLC-QTOF-MS/MS).