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.
Highlights
One of the major problems faced nowadays is water pollution caused by different industrial activities, which can raise thorny environmental, economic, social, and health issues [1,2]
Among Advanced oxidative processes (AOPs), those based on Fenton reactions are considered promising for dye degradation [13]
As a matter of fact, kinetic models obtained on a Chromotrope 2R and 3-hydroxyanthranilic acid were supplied by Sigma-Aldrich Chemical Co
Summary
One of the major problems faced nowadays is water pollution caused by different industrial activities, which can raise thorny environmental, economic, social, and health issues [1,2]. In this scenario, the textile industry should be highlighted, due to the fact that it is accountable for generating massive amounts of effluent containing recalcitrant dyes and other pollutants. The biggest challenge is that many textile dyes are toxic and unable to be degraded by conventional biological treatments [3,4]. Among AOPs, those based on Fenton reactions are considered promising for dye degradation [13]
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