Decoloration treatment of a hazardous triarylmethane dye, Light Green SF (Yellowish) by waste material adsorbents.

An agricultural industry waste, deoiled soya, and a waste of thermal power plants, bottom ash, have been tested for their adsorption ability to remove Light Green SF (Yellowish) dye from wastewaters. The effects of various essential experimental parameters (dye concentration, mesh size, temperature, and pH) have been investigated. A study of four isothermal models, Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich, has been made and important thermodynamic parameters have been calculated. The decreasing values of enthalpy show that the adsorption process is endothermic. Mechanistic studies reveal the involvement of a pseudo-second-order mechanism to drive the adsorption process in dye-bottom ash and dye-deoiled soya systems. It has been observed that a particle diffusion mechanism was prominent in the case of adsorption of the dye on bottom ash and deoiled soya. Column adsorption and desorption experiments further confirmed the practical application of the present research. The percentage adsorption has been obtained as 88.74% and 89.65% with percentage recovery of 99.82% and 99.08% for bottom ash and deoiled soya, respectively. The experimental results confirmed that triarylmethane dye Light Green SF (Yellowish) can be successfully removed and recovered from aqueous solutions economically and efficiently. Copyright 2009 Elsevier Inc. All rights reserved.