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Gallic acid influence on azo dyes oxidation by Fenton processes
Carlos Henrique Borges Tabelini1, Juan Pablo Pereira Lima1, André Aguiar1
1Instituto de Recursos Naturais, Universidade Federal de Itajubá, Itajubá, Brazil.
Environmental Technology
|April 23, 2021
Summary
Gallic acid (GA) enhances azo dye oxidation by Fenton processes, increasing decolorization rates and lowering activation energy. This natural compound facilitates dye degradation, offering a greener approach to wastewater treatment.
Area of Science:
- Environmental Chemistry
- Green Chemistry
- Oxidation Processes
Background:
- Azo dyes are widely used synthetic colorants, posing environmental challenges due to their persistence.
- Fenton processes (Fe3+/H2O2 and Fe2+/H2O2) are effective for oxidizing organic pollutants.
- Natural plant reducers offer potential for enhancing oxidative degradation efficiency.
Purpose of the Study:
- To evaluate the impact of gallic acid (GA) on the Fenton-mediated decolorization of methyl orange and chromotrope 2R.
- To investigate the kinetics and thermodynamics of the dye oxidation process with and without GA.
- To determine if GA can reduce the activation energy for dye degradation.
Main Methods:
- Fenton oxidation experiments using Fe3+/H2O2 and Fe2+/H2O2 systems with and without gallic acid.
- Kinetic analysis using 1st-order and 2nd-order models to fit experimental decolorization data.
- Determination of apparent activation energy (Ea) at different temperatures.
Main Results:
- Gallic acid significantly increased the decolorization rates of both methyl orange and chromotrope 2R.
- Reaction rate constants increased with GA addition and elevated temperatures.
- The apparent activation energy for methyl orange decolorization decreased from 81.5 kJ/mol to 53.6 kJ/mol with GA in the Fe2+/H2O2 system.
Conclusions:
- Gallic acid acts as a natural reducer, enhancing the efficiency of Fenton processes for azo dye oxidation.
- GA lowers the energy barrier for dye degradation, leading to faster reaction rates.
- This study highlights the potential of using natural compounds like GA to improve wastewater treatment technologies.
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