Studies on the adsorption of furfural from aqueous solution onto low-cost bagasse fly ash

The present study deals with the sorptive removal of furfural from aqueous solution by carbon-rich bagasse fly ash (BFA). Batch studies were performed to evaluate the influence of various experimental parameters, namely, initial pH (pH(0)), adsorbent dose, contact time, initial concentration, and temperature on the removal of furfural. Optimum conditions for furfural removal were found to be pH0 approximate to 5.5, adsorbent dose approximate to 4g/L of solution, and equilibrium time approximate to 4 h. The adsorption followed pseudo-second-order kinetics. The effective diffusion coefficient of furfural is of the order of 10(-13)m(2)/s. Equilibrium adsorption data on BFA was analyzed by Freundlich, Langmuir, Dubnin-Radushkevich, Redlich-Peterson, and Temkin isotherm equations using regression and error analysis. The Redlich-Peterson isotherm was found to best represent the data for furfural adsorption onto BFA. Adsorption of furfural on BFA is favorably influenced by a decrease in the temperature of the operation. Values of the change in entropy (Delta S-0) and heat of adsorption ( Delta H-0) for furfural adsorption on BFA were negative. The high negative value of change in Gibbs free energy ( Delta G(0)) indicates the feasible and spontaneous adsorption of furfural on BFA.