Adsorption study on orange peel: Removal of Ni(II) ions from aqueous solution

Abstract

Adsorption of Nickel(II) ions from aqueous solution onto a low cost adsorbent-orange peel was investigated to evaluate the effects of pH, initial nickel ion concentration and adsorbent dose on the removal of Ni(II) systematically. The optimal pH value for Ni(II) adsorption onto the orange peel was found to be 5.0. Greater percentage of metal ion was removed with decrease in the initial concentration of metal ion and increase in amount of adsorbent used. Adsorption data was modeled using the Langmuir and Freundlich adsorption. The adsorption kinetics was found to follow pseudo-second-order rate kinetic model, with a good correlation (r² > 0.99) and intra-particle diffusion as one of the rate determining steps. Thermodynamic parameters (ΔG°, ΔS° and ΔH°) for sorption system was determined at five different temperatures.

Key words: Orange peel, heavy metal ion, adsorption, isotherms, kinetics.