Simultaneous removal of aniline and Sb(V) from wastewater in an integrated electrocoagulation and electro-Fenton system

Abstract

Heavy metal–organic compound complexes are commonly found in textile dye wastewater, seriously threatening human health. This work proposes a unique integrated electrocoagulation and electro-Fenton (EC-EF) system combining an Fe anode and a carbon-felt-loaded hydroxylated carbon nanotubes (CNTs-OH/CF) cathode for the simultaneous removal of aniline and Sb(V) from wastewater. Under optimal conditions of initial pH of 3.0, NaCl concentration of 0.15 mol/L, and current density of 30 A m⁻², the EC-EF system removed almost 100 % of aniline in 40 min and of Sb(V) in 10 min, with an energy consumption equal to 2.01 KWh kg⁻¹. The excellent performance derived from the usage of the CNTs-OH/CF cathode increased the number of active sites, hydrophobicity, and electrical conductivity, facilitating the oxygen reduction reaction and electron transfer, thus enhancing the in situ-produced hydrogen peroxide (H₂O₂) with a concentration of 644.53 mg L⁻¹, exceeding most reported values. Furthermore, hydroxyl radicals (•OH), the dominant active species generated through the reactions of Fe²⁺ with electro generated H₂O₂, promoted the degradation of aniline. Meanwhile, Sb(V) was adsorbed by the ferric hydroxide formed at the anode and finally co-precipitated. The excellent reusability after five cycles and outstanding catalytic activity towards real wastewater demonstrate the superiority of the developed system for treating wastewater in practical applications. This study presents a unique integrated technology and a theoretical foundation for the simultaneous removal of heavy metal–organic compound complexes from wastewater.