Enhancement of HO Decomposition by the Co-catalytic Effect of WS on the Fenton Reaction for the Synchronous Reduction of Cr(VI) and Remediation of Phenol.

The greatest problem in the Fe(II)/HO Fenton reaction is the low production of ·OH owing to the inefficient Fe(III)/Fe(II) cycle and the low decomposition efficiency of HO (<30%). Herein, we report a new discovery regarding the significant co-catalytic effect of WS on the decomposition of HO in a photoassisted Fe(II)/HO Fenton system. With the help of WS co-catalytic effect, the HO decomposition efficiency can be increased from 22.9% to 60.1%, such that minimal concentrations of HO (0.4 mmol/L) and Fe (0.14 mmol/L) are necessary for the standard Fenton reaction. Interestingly, the co-catalytic Fenton strategy can be applied to the simultaneous oxidation of phenol (10 mg/L) and reduction of Cr(VI) (40 mg/L), and the corresponding degradation and reduction rates can reach up to 80.9% and 90.9%, respectively, which are much higher than the conventional Fenton reaction (52.0% and 31.0%). We found that the expose reductive W active sites on the surface of WS can greatly accelerate the rate-limiting step of Fe/Fe conversion, which plays the key role in the decomposition of HO and the reduction of Cr(VI). Our discovery represents a breakthrough in the field of inorganic catalyzing AOPs and greatly advances the practical utility of this method for environmental applications.