Fenton-Like Oxidation of Malachite Green Solutions: Kinetic and Thermodynamic Study

Saeedeh Hashemian

doi:10.1155/2013/809318

Abstract

Oxidation by Fenton-like (Fe3+/H2O2) reactions is proven to be an economically feasible process for destruction of a variety of hazardous pollutants in wastewater. In this study, the degradation and mineralization of malachite green dye are reported using Fenton-like reaction. The effects of different parameters like pH of the solution, the initial concentrations of Fe3+, H2O2, and dye, temperature, and added electrolytes (Cl− and <svg style="vertical-align:-3.27605pt;width:40.537498px;" id="M1" height="19.924999" version="1.1" viewBox="0 0 40.537498 19.924999" width="40.537498" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,15.775)"><path id="x53" d="M409 504l-29 -5q-16 60 -44.5 96t-86.5 36q-54 0 -82.5 -32t-28.5 -77q0 -51 30.5 -82.5t96.5 -65.5l35.5 -18t33 -19.5t33.5 -23.5l27 -25.5t24.5 -32t13.5 -36.5t6 -45q0 -80 -62 -134.5t-160 -54.5q-47 0 -98 15q-22 7 -50 21q-8 23 -27 155l30 7q7 -27 18 -52
t30 -51.5t49 -42.5t67 -16q56 0 88 32.5t32 87.5q0 51 -31.5 82t-98.5 67q-80 44 -110 73q-55 53 -55 124q0 75 56 126.5t150 51.5q53 0 126 -23z" /></g><g transform="matrix(.017,-0,0,-.017,8.12,15.775)"><path id="x4F" d="M381 665q131 0 226.5 -93t95.5 -239q0 -158 -96 -253t-238 -95q-137 0 -231 95t-94 238q0 142 92.5 244.5t244.5 102.5zM359 629q-89 0 -151 -74.5t-62 -208.5q0 -141 69 -233t175 -92q90 0 150.5 74t60.5 211q0 152 -69 237.5t-173 85.5z" /></g> <g transform="matrix(.012,-0,0,-.012,20.812,19.863)"><path id="x34" d="M456 178h-96v-72q0 -51 12.5 -62.5t72.5 -16.5v-27h-256v27q65 5 78 17t13 62v72h-260v28q182 271 300 426h40v-407h96v-47zM280 225v295h-2q-107 -148 -196 -295h198z" /></g> <g transform="matrix(.012,-0,0,-.012,27.15,7.613)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.012,-0,0,-.012,32.861,7.613)"><path id="x2212" d="M535 230h-483v50h483v-50z" /></g> </svg>) on the oxidation of the dye were investigated. Optimized condition was determined. The efficiency of 95.5% degradation of MAG after 15 minutes of reaction at pH 3 was obtained. TOC removal indicates partial and insignificant mineralization of malachite green dye. The results of experiments showed that degradation of malachite green dye in Fenton-like oxidation process can be described with a pseudo-second-order kinetic model. The thermodynamic constants of the Fenton oxidation process were evaluated. The results implied that the oxidation process was feasible, spontaneous, and endothermic. The results will be useful for designing the treatment systems of various dye-containing wastewaters.

Highlights

Dyes in wastewater are of particular environmental concern since they give an undesirable color to the waters and in some cases are harmful compounds and can originate dangerous by-products through oxidation, hydrolysis, or other chemical reactions taking place in the waste phase
Various Fenton processes were used for oxidation of dyes
Homogenous Fenton reaction (Fe2+/H2O2) is one of the most important processes to generate hydroxyl radicals ∙OH [14,15,16]. These processes are involved in the generation of highly reactive radicals in enough quantity to affect water purification, and their use is justified by the low organic content of the wastewaters to be treated

Summary

Introduction

Dyes in wastewater are of particular environmental concern since they give an undesirable color to the waters and in some cases are harmful compounds and can originate dangerous by-products through oxidation, hydrolysis, or other chemical reactions taking place in the waste phase. Applied treatment methods for color removal from dye-contaminated effluents consist of various processes involving biological, physical and chemical decolorization methods. Homogenous Fenton reaction (Fe2+/H2O2) is one of the most important processes to generate hydroxyl radicals ∙OH [14,15,16] These processes are involved in the generation of highly reactive radicals (especially hydroxyl radicals) in enough quantity to affect water purification, and their use is justified by the low organic content of the wastewaters to be treated. They have low reaction temperatures and require the presence of very active oxidation agents. The oxidation using Fenton’s reagent has proved to be a promising and attractive treatment method for the effective destruction of a large number of hazardous and organic pollutants [17,18,19,20,21]

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Conclusion