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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2006.06.024 Byline: Venkat S. Mane, Indra Deo Mall, Vimal Chandra Srivastava Keywords: Dye removal; Rice husk ash; Adsorption kinetics; Isotherms; Thermodynamics; Error analyses Abstract: The present study deals with the adsorption of Brilliant Green (BG) on rice husk ash (RHA). RHA is a solid waste obtained from the particulate collection equipment attached to the flue gas lines of rice husk fired boilers. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH.sub.0), contact time, adsorbent dose and initial concentration (C.sub.0) on the removal of BG. Optimum conditions for BG removal were found to be pH.sub.0[approximately equal to]3.0, adsorbent dose [approximately equal to]6gL.sup.-1 of solution and equilibrium time [approximately equal to]5h for the C.sub.0 range of 50-300mgL.sup.-1. Adsorption of BG followed pseudo-second-order kinetics. Intra-particle diffusion does not seem to control the BG removal process. Equilibrium isotherms for the adsorption of BG on RHA were analyzed by Freundlich, Langmuir, Redlich-Peterson (R-P), Dubnin-Radushkevich (D-R), and Temkin isotherm models using a non-linear regression technique. Langmuir and R-P isotherms were found to best represent the data for BG adsorption onto RHA. Adsorption of BG on RHA is favourably influenced by an increase in the temperature of the operation. Values of the change in entropy ([DELTA]S.sup.0) and heat of adsorption ([DELTA]H.sup.0) for BG adsorption on RHA were positive. The high negative value of change in Gibbs free energy ([DELTA]G.sup.0) indicates the feasible and spontaneous adsorption of BG on RHA. Author Affiliation: Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee 247 667, India Article History: Received 30 September 2005; Revised 14 June 2006; Accepted 20 June 2006