Activation of peroxydisulfate by V-Fe concentrate ore for enhanced degradation of carbamazepine: Surface ≡V(III) and ≡V(IV) as electron donors promoted the regeneration of ≡Fe(II)

[Display omitted] •V-Fe/PMS system exhibits superior catalytic performance for CBZ degradation.•Surface ≡V(Ⅲ) and ≡V(Ⅳ) as electron donors promoted the regeneration of ≡Fe(Ⅱ).•The Half-lives method was used to determine the reaction orders of CBZ degradation.•EPR analysis and DFT calculation helped to explain the degradation pathways of CBZ.•Catalyst displayed excellent recyclability, reusability, and general applicability. V-Fe concentrate ore was applied to activate peroxydisulfate (PDS) for carbamazepine (CBZ) degradation. The excellent performance of V-Fe concentrate ore was mainly ascribed to the quick electron transfer from surface ≡V(III) and ≡V (IV) to ≡Fe(III) for ≡Fe(II) regeneration, which was confirmed by XPS and XAS analyses. This accelerated ≡Fe(II) regeneration could thus lead to quick formation of HO, SO4−, O2− and effective degradation of CBZ. The degradation rate of CBZ could be also expressed by a kinetic model, i.e., −d[CBZ]/dt = (0.83 mM-0.55 min-1(g/L)-0.65) [CBZ]0.29[PDS]1.26[V-Fe]0.65. Combined with the measured intermediates and the results of DFT calculation, CBZ degradation pathway was proposed systematically. Moreover, this catalyst displayed excellent recyclability and general applicability for a broad substrate scope. This study suggests low valent vanadium makes crucial contributions to the high activity of V-Fe-based catalysts, and improves the understanding of electron transfer mechanism between V and Fe in PDS activation process.