Kinetic Evaluation of Dye Decolorization by Fenton Processes in the Presence of 3-Hydroxyanthranilic Acid

Abstract

The fungal metabolite 3-hydroxyanthranilic acid (3-HAA) was used as a redox mediator with the aim of increasing dye degradation by Fenton oxidative processes (Fe2+/H2O2, Fe3+/H2O2). Its Fe3+-reducing activity can enhance the generation of reactive oxygen species as HO● radicals. Initially, the influence of 3-HAA on decolorization kinetics of five dyes (methylene blue, chromotrope 2R, methyl orange, phenol red, and safranin T) was investigated using decolorization data from a previous work conducted by the present research group. Fe3+-containing reaction data were well fitted with first-order and mainly second-order kinetic models, whereas the BMG (Behnajady, Modirshahla and Ghanbary) model obtained optimal fit to Fe2+. Improvements in kinetic parameters (i.e., apparent rate constants and maximum oxidation capacity) were observed with the addition of 3-HAA. In another set of experiments, a decrease in apparent activation energy was observed due to introducing 3-HAA into reactions containing either Fe2+ or Fe3+ in order to decolorize phenol red at different temperatures. This indicates that the redox mediator decreases the energy barrier so as to allow reactions to occur. Thus, based on recent experiments and the reaction kinetics models evaluated herein, pro-oxidant properties have been observed for 3-HAA in Fenton processes.

Decreasing COD in Sugarcane Vinasse Using the Fenton Reaction: The Effect of Processing Parameters

“…The second phase is the slower reaction when t = 15 to 60 min and indicates a lower rate of generation of • OH. In previous studies related to the degradation of wastewater by the Fenton reaction, similar behavior was also observed, such as works by Zhang [20] and Santana [35]. The The results show that as the ratio of [H 2 O 2 ] to [COD] increased, most of the kinetic values for every kinetic model also increased linearly with the [H 2 O 2 ] to [COD] ratio.…”

“…The second phase is the slower reaction when t = 15 to 60 min and indicates a lower rate of generation of • OH. In previous studies related to the degradation of wastewater by the Fenton reaction, similar behavior was also observed, such as works by Zhang [20] and Santana [35]. The reaction profile of their experimental data showed a very fast reaction followed by a slower one and they suggested, based on this behavior, that degradation of organics by Fenton oxidation is not suitable to be modeled by first order or second order kinetics because the fitting of experimental data with those models would not be good.…”

Effect of Physiological Concentrations of Vitamin C on the Inhibitation of Hydroxyl Radical Induced Light Emission from Fe2+-EGTA-H2O2 and Fe3+-EGTA-H2O2 Systems In Vitro

“…Numerous reactions can occur simultaneously in an Fe 2+ -EGTA-H 2 O 2 system [ 12 , 13 , 14 , 29 , 30 ]. Those leading to the generation of • OH radicals, superoxide radicals (O 2• − ), hydroperoxyl radicals (HO 2 • ), singlet oxygen (O 2 ( 1 ∆g)), and the reduction of Fe 3+ to Fe 2+ are presented below: Fe 2+ -EGTA + H 2 O 2 → Fe 3+ -EGTA + OH − + • OH (formation of hydroxyl radicals) Fe 3+ -EGTA + H 2 O 2 → Fe 3+ OOH − -EGTA + H + Fe 3+ OOH − -EGTA + H 2 O 2 → FeO 2+ -EGTA + HO 2 • + H 2 O FeO 2+ -EGTA + H 2 O 2 → Fe 3+ -EGTA + HO 2 • + OH − HO 2 • → H + + O 2• − (formation of superoxide radicals) Fe 3+ -EGTA + O 2• − → Fe 2+ -EGTA + O 2 Fe 3+ -EGTA + H 2 O 2 → Fe 2+ -EGTA + HO 2 • Fe 3+ -EGTA + HO 2 • → Fe 2+ -EGTA + O 2 + H + .…”

“…It is well known that chemical compounds which can effectively reduce Fe 3+ to Fe 2+ added to Fenton’s reagent (aqueous solution containing Fe 2+ and H 2 O 2 ) strongly enhanced • OH radicals generation. This was noted for hydroxylamine, ascorbic acid (AA), cysteine, 3-hydroxyanthranilic acid [ 13 , 14 ], and plant phenolics such as gallic acid, phloroglucinol, 3,4-dihydroxyphenylacetic acid, and phloretin [ 15 ]. Moreover, AA can undergo autooxidation, generating additional amounts of H 2 O 2 [ 16 , 17 ].…”

“…Moreover, AA can undergo autooxidation, generating additional amounts of H 2 O 2 [ 16 , 17 ]. Application of Fe 2+ -regenerating compounds appears to be a promising approach for Fenton chemistry in order to develop the effective methods of degradation of hazardous pollutants [ 13 , 14 ]. However, in the case of ascorbic acid (AA), this activity seems to be a double-edged sword.…”