Heterogeneous UV-Fenton photodegradation of azocarmine B over [FeEDTA]− intercalated ZnAl-LDH at circumneutral pH

Abstract

This work aimed at maintaining Fe(III) in soluble form at circumneutral pH and separating it from the treated effluent by using the heterogeneous catalyst of Fe(III)–ethylenediaminetetraacetate complex ([FeEDTA]⁻) intercalated layered double hedroxides (LDHs) in the UV-Fenton process for the degradation of azocarmine B (ACB). All samples were fully characterized by various techniques and the results indicated the successful intercalation of [FeEDTA]⁻ within the interlayer of layered double hedroxides. In the decolorization and mineralization of the ACB process, the obtained catalyst showed a high photo-catalytic activity and an excellent stability at circumneutral pH. In addition, response surface methodology (RSM) was employed to optimize operating variables, and these mathematical models produced a satisfactory fit. The optimum conditions for ACB degradation were confirmed to be 6.54 initial pH, 100 mg L⁻¹ ACB concentration and 11.5 mM H₂O₂ concentration. Under the optimum conditions, the maximum ACB decolorization efficiency and TOC removal could reach up to 97.27% and 90.36%, respectively, which closely agreed with the predicted values. Finally, the possible reaction mechanisms involved in the heterogeneous UV-Fenton system were proposed.