Degradation and Mineralization of Gallic Acid Using Fenton's Reagents

Abstract

Performance of Fenton oxidation in the degradation of gallic acid (GA), one of the most representative phenolic compounds in wastewater, was studied. Factorial experimental design was used to study the main variables affecting the Fenton process as well as their interactions. Eight 22 factorial designs were performed to estimate the effects of the H2O2/GA and Fe2+/GA molar ratios on the degradation of GA and on its mineralization as percentage of initial carbon converted in carbon dioxide. H2O2/GA and Fe2+/GA ratios ranged from 0.3 to 32.3 and from 0.15 to 1.15, respectively. Experiments were conducted in batch mode and in an apparatus designed to directly measure carbon dioxide production. Results from the statistical processing of experimental data enlightened the oxidation mechanism and indicated that GA degradation is strongly influenced from both Fenton's reagents doses at low concentrations, whereas for mineralization efficiency only H2O2/GA molar ratio was statistically significant. The optimal H2O2/GA ratio resulting in the maximum phenolic compound degradation (95.5% ± 1.3%) and mineralization efficiency (41.6% ± 2.8%) was found to be 24.3 independently of the Fe2+/GA ratio.