Catalytic oxidation of gallic: mechanisms, kinetics, and byproduct analysis [Articol]

Abstract

This paper investigates the catalytic oxidation of gallic acid utilizing Fenton and Fenton/UV reactions, focusing on elucidating the mechanisms, kinetics, and byproducts of the oxidation processes. Gallic acid, a naturally occurring phenolic compound, presents both health benefits and environmental challenges due to its persistence and potential toxicity. The Fenton and Fenton/UV reactions generate highly reactive hydroxyl radicals, initiating the oxidation of GA. The study explores the pseudo- first-order kinetics of GA degradation (1.47•10⁻⁴ M), examining variables such as [Fe²⁺], [H₂O₂], pH, and temperature. Results indicate 50% degradation and 30% mineralization after 5 min, with improved COD removal over 60 min. Optimal conditions were identified as [H₂O₂] = 5•10⁻⁴ M, [Fe²⁺] = 1•10⁻⁵ M, pH=3.0. The average rate constant (kₐᵥg) was 5.7•10⁻³ s⁻¹. Intermediate byproducts include hydroxylated derivatives and carboxylic acids. These findings highlight the relevance of advanced oxidation for environmental biotechnology.