Adsorption kinetics of removal of a toxic dye, Malachite Green, from wastewater by using hen feathers

The paper includes meticulous utilization of hen feather as potential adsorbent to remove a hazardous triphenylmethane dye, Malachite Green from wastewater. The adsorption studies were carried out at 30, 40 and 50 degrees C and effects of pH, temperature, amount of adsorbent, contact time, concentration of adsorbate, etc. on the adsorption were measured. On the basis of adsorption data Langmuir and Freundlich adsorption isotherm models were also confirmed. The adsorption isotherm constants thus obtained were employed to calculate thermodynamic parameters like Gibb's free energy, change in enthalpy and entropy. The paper also incorporates systematic kinetic studies of the ongoing adsorption process and a first order adsorption kinetics was found to be operative during the adsorption. The specific rate constants at different temperatures were found to be dependent upon the concentration of the dye. The adsorption was found to operate via film and particle diffusion process in the higher and lower concentration ranges, respectively. (c) 2005 Elsevier B.V. All rights reserved.