Adsorption of Fe(II), Co(II), Ni(II) and Cu(II) ions onto a low cost activated carbon: Equilibrium, kinetic and thermodynamic studies

Abstract

Batch sorption system using activated carbon from Aegle marmelos fruits source as an adsorbent was investigated to remove Fe(II), Co(II), Ni(II) and Cu(II) ions from aqueous solutions. The system variables studied include initial concentration of the sorbate, agitation time, adsorbent dose, pH, co-ions and temperature. The experimental data fitted well to the Langmuir and Freundlich isotherms. The values of thermodynamic parameters such as ΔHº, ΔSº and ΔGº indicated that the adsorption was a spontaneous, endothermic and a physical process. Kinetic studies revealed that the adsorption is of first order. A two staged mechanism has been proposed for the adsorption of metal ions onto the adsorbent. FT-IR and SEM patterns of the adsorbent were used to understand the mechanism of the adsorption process. The order of adsorption of the metal ions was found to be Fe(II) > Cu(II) > Ni(II) > Co(II) which is in agreement with the intra-particle diffusion studies.