Efficacious Reduction of Ferric Ions by Molybdenum Carbide in the Peroxydisulfate Fenton-Like Reaction for Dexamethasone Degradation

Abstract

The tardy Fe2+ regeneration and the limited pH range confine the practical application of Fe-based homogenous Fenton-like reaction performance. To surmount the abovementioned obstacles, we applied molybdenum carbide (β-Mo2C) as the cocatalyst to boost Fe3+ reduction in the activation of peroxydisulfate (PDS) for the efficient degradation of dexamethasone (DXM). The proposed Fe3+/PDS/β-Mo2C can remove more than 90% DXM in the wide pH range (3.4 to 9.4). Electron spin resonance analysis and probe and quenching tests comprehensively demonstrated that a series of reactive species (•OH, SO4•–, O2•–, 1O2, and Fe(IV)) were formed during the synergistic process, and SO4•– was the leading role. The circulation of Fe3+/Fe2+ was driven by the exposed sites of Mo2+/Mo4+ on the β-Mo2C, which further promoted the PDS activation. The reaction mechanism was clarified by various characterizations and density functional theory calculation, which indicated that the adsorption between Fe3+ and β-Mo2C could form Mo–Fe bonds and lengthen Fe–O and then improve the electron transport from β-Mo2C to Fe3+ and boost Fe3+ reduction. The reactivity and stability of β-Mo2C was higher than those of popular Mo-based materials. This work represents an attempt and possibility for Mo-based inorganic cocatalysis of advanced oxidation processes.