Benzoic Acid Degradation by Highly Active Heterogeneous Fenton-like Process using Fe3+-Al2O3 Catalyst

Abstract

This work examines oxidative degradation of benzoic acid in an aqueous solution using an eco-friendly advanced oxidation (heterogeneous Fenton) process. The degradation of benzoic acid (1,000 mgL⁻¹) with H₂O₂ was performed using Fe³⁺ immobilized within an Al₂O₃ matrix as a heterogeneous Fenton catalyst and the efficiency of the system was compared to that of the homogeneous Fe³⁺/H₂O₂ system. The influence of various operational conditions like catalyst dosage, H₂O₂ concentration, Fe³⁺ concentration, pH of the solution and initial substrate concentration on % degradation for both the processes has been studied to find out the best operating conditions for these processes. The experimental results show that the optimum conditions for homogeneous Fe³⁺/H₂O₂ process are [Fe³⁺] = 1,250  mgL⁻¹, [H₂O₂] = 2,000 mgL⁻¹, initial pH = 3 and 87.5 % degradation was obtained within 35 min. In the case of heterogeneous catalyst, degradation improved to 91.7% using 12.5 gL⁻¹ catalyst for the same duration keeping other operating conditions the same. The use of iron immobilized in alumina matrix as heterogeneous Fenton catalyst is an alternative approach for degrading organic contaminants.