Oxidation of pollutants via an electro-Fenton-like process in aqueous media using iron–zeolite modified electrodes

Abstract

Preparation of new iron–zeolite modified electrodes for the oxidation of pollutants via an electro-Fenton-like process is reported in this work. Alizarin Red S (ARS) is chosen as the model dye compound for anodic oxidation in an aqueous acidic medium. A minimal metal loading ranging from 0.2 to 0.8 wt% of ferrous/ferric (Fe²⁺/Fe³⁺) ions was introduced inside the ZSM-5 zeolite (Si/Al ratio of 15.0) via an ion-exchange process and the presence of iron species in the zeolite framework was determined using several physicochemical techniques. The iron–zeolite samples obtained under different experimental conditions were employed in order to study the textural and structural properties, and electrocatalytic activity. Cyclic voltammetry measurements showed that the textural properties of zeolite do not mainly affect the electrocatalytic reaction. However, the differences observed in catalytic peaks were a consequence of different iron ions present in zeolite. The structure–catalytic activity relationship is highlighted by the identification of the degradation products like oxalic acid (C₂H₂O₄) and formic acid (HCOOH). Consequently, the degradation of ARS reached an optimum value of ca. 30% at 2 V vs. SCE for Fe(III)_TTZSM-5 with a catalyst loading of 5.0 mg cm⁻². This study shows that iron–zeolite modified electrodes are highly active for dye compound degradation without the addition of H₂O₂ and have potential application in the treatment of effluents.