Simultaneous degradation of organoarsenic and immobilization of arsenate by an electroactive CuFeO-CNT/peroxymonosulfate platform: Insights into the distinct roles of the Cu and Fe sites.

Phenylarsonic acid (PAA) compounds, widely used in animal husbandry, pose a considerable environmental threat owing to their potential transformation into toxic inorganic arsenic species. To efficiently decontaminate PAA and adsorb secondary As(V), a hybrid CuFeO-modified carbon nanotube (CuFeO-CNT) filter was developed in this study. The hybrid CuFeO-CNT filter functioned as an effective catalyst, convective filtration medium, electrode, and adsorbent. Moreover, it removed 97 % PAA within 80 min in circulation mode under optimal conditions (25 °C, pH = 7, peroxymonosulfate [PMS] = 1.5 mM, and voltage = 1.0 V), with a total As removal efficiency of 94 %. Experimental and theoretical studies showed that the (100) and (211) planes of CuFeO-CNT contributed to PMS activation and As(V) adsorption, respectively. Quantum chemical calculations and high-performance liquid chromatography-mass spectrometry analysis determined the energy barriers for reactions between the transient state and SO and HO, based on which potential PAA degradation pathways were proposed. Additionally, the negligible loss of efficiency in practical water samples and acceptable leached metal ion concentrations (Cu < 0.1 mg/L and Fe < 0.15 mg/L) confirmed the reusability and stability of the filter. This study provides a promising strategy for organoarsenic decontamination by combining electrocatalytic PMS oxidation and filtration techniques.