Adsorption Characteristics of Activated Carbon for the Reclamation of Eosin Y and Indigo Carmine Colored Effluents and New Isotherm Model

Ratna Surya Alwi,Avijit Bhowal,Ramakrishnan Gopinathan,Chandrasekhar Garlapati

doi:10.3390/molecules25246014

Ratna Surya Alwi, Avijit Bhowal + Show 2 more

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https://doi.org/10.3390/molecules25246014

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Abstract

The adsorption response of eosin Y and indigo carmine acid dyes on activated carbon as a function of system temperature for a fixed concentration was investigated at various temperatures via adsorption isotherms and their thermodynamic quantities such as enthalpy, entropy, and Gibbs free energy changes. The adsorption data were exploited to develop a new adsorption isotherm. The new isotherm was developed with the spirit of solid–liquid phase equilibrium and regular solution theory. The proposed model has four adjustable constants and correlates adsorption isotherm in terms of the system temperature and melting temperature of the dye. The effect of pH on the removal of acid dyes was reported. The pH variation was observed to affect the adsorption efficiency. The removal of eosin Y and indigo carmine decreased from 99.4% to 82.6% and 92.38% to 79.48%, respectively, when the pH of the solution varied from 2 to 12. The thermodynamic analysis of the process reveals that the process of the removal of acid dyes is exothermic and spontaneous. Moreover, the kinetics parameters of the batch process are reported.

Highlights

Water pollution is the most important concern in developing and underdeveloped nations.Over the past few decades, dyes have been the major causes of water pollution [1]
The adsorption equilibrium results for eosin Y and indigo carmine acid dyes from aqueous solutions on activated carbon are reported at temperatures 303, 313, and 323 K and atmospheric pressure (p = 0.1 MPa)
It is observed that the activated carbon uptake of dye is found to increase with an increase in temperature for both the compounds

Summary

Introduction

Water pollution is the most important concern in developing and underdeveloped nations. Over the past few decades, dyes have been the major causes of water pollution [1]. The textile, paper, leather, printing, and cosmetic industries use these dyes, with the effluents released from these industries causing major contamination and resulting in the freshwater depletion. Many treatment methods have been adapted, such as osmosis, membrane separations, precipitation, adsorption, and chemical oxidation, to treat the effluents [2,3,4,5,6]. The removal of pollutants by adsorption on activated carbon is a commonly used method for treating dye effluents because of the characteristics of high surface area and developed pore structures [6,7,8,9,10,11,12,13]. Adsorption data are some of the most important information for the effective implementation of adsorption process [11,12,13]

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