Ultrafast degradation of micropollutants in water via electro-periodate activation catalyzed by nanoconfined Fe2O3

Herein, we developed and evaluated an electrochemical periodate (PI) activation system for the ultrafast degradation of aqueous micropollutants (τ < 3 s). Filters constructed from carbon nanotubes (CNT) coated with Fe2O3 nanoparticles on the outer (Fe2O3-out-CNT) and inner surfaces (Fe2O3-in-CNT) were prepared to regulate the generation of reactive oxygen species (ROS) during PI activation. The activation function of the electroactive nanohybrid filters lay in their ability to facilitate the redox cycling of Fe(III)/Fe(II) assisted by an electric field. The results showed that a non-radical (i.e., 1O2) pathway dominated the degradation process in the electro/Fe2O3-in-CNT/PI system, while a contrastive radical pathway (i.e., HO• and IO3•) was identified in the electro/Fe2O3-out-CNT/PI system. The electro/Fe2O3-in-CNT/PI system exhibited enhanced catalytic activity towards the micropollutants degradation relative to its electro/Fe2O3-out-CNT/PI counterpart. Density functional theory calculations suggested that PI could be directly decomposed under the nanoconfined environment, rather than forming a stable adsorption complex in the unconfined system.