Use of bagasse fly ash as an adsorbent for the removal of brilliant green dye from aqueous solution

The present study deals with the adsorption of brilliant green (BG) on carbon rich bagasse fly ash (BFA). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse-fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH0), contact time, adsorbent dose and initial concentration (C0) on the removal of BG. Optimum conditions for BG removal were found to be pH0 ≈ 3.0, adsorbent dose ≈ 3 g/l of solution and equilibrium time ≈ 5 h. 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 BFA were analyzed by Freundlich, Langmuir, Redlich–Peterson, Dubnin–Radushkevich, and Temkin isotherm models using non-linear regression technique. Redlich–Peterson and Langmuir isotherms were found to best represent the data for BG adsorption onto BFA. Adsorption of BG on BFA is favourably influenced by an increase in the temperature of the operation. Values of the change in entropy (ΔS0ΔS0) and heat of adsorption (ΔH0ΔH0) for BG adsorption on BFA were positive. The high negative value of change in Gibbs free energy (ΔG0ΔG0) indicates the feasible and spontaneous adsorption of BG on BFA.