Nano-sized FeVO4·1.1H₂O and FeVO4 for peroxymonosulfate activation towards enhanced photocatalytic activity

Abstract

Visible-light-assisted catalytic peroxymonosulfate (PMS) activation is an effective advanced oxidation technique for removing organic pollutants from water. Here, nano-sized fervanite FeVO4∙1.1 H2O (FV-H) and FeVO4 (FV-A) with regulated structures are synthesized at different pH values or annealing temperatures for photocatalytic methylene blue (MB) degradation via PMS activation. The activation mechanisms induced by FV-H and FV-A photocatalysts are examined by radical quenching, electron paramagnetic resonance (EPR) tracing methods, and (photo) electrochemical characterization. Our findings indicate that the multiple PMS activation pathways by photogenerated charge carriers from photocatalysts, as well as Fe(II)/Fe(III) and V(IV)/V(V) mixed-valence ion pairs led to the production of reactive holes (h+), hydroxyl (•OH) and sulfate radical (SO4•−) in FV-H (or FV-A)/PMS/Vis system for photodegradation, while SO4•− worked dominantly for MB degradation. The influences of PMS dosage, inorganic anions, pH value, and MB concentration on the degradation rates are also investigated. This work offers a new thought to the synthesis of high-efficiency photocatalysts for practical water treatment.