Research Information System
Journal of Dispersion Science and Technology, vol.34, no.9, pp.1248-1256, 2013 (SCI-Expanded, Scopus)
First, activated carbon was prepared by various ammonium compounds such as NH4NO3, NH4Cl, NH4Br, NH4I, NH4HCO3, and (NH4)2HPO4. The pore properties such as surface areas, pore volumes and pore sizes of them were compared under same activation conditions (600°C, 5 g of rice hull, 20 g of ammonium compound, within a half-hour activation time). The highest surface area by Brunauer-Emmett-Teller (BET) method was obtained as 456.7667 m2 g-1 by ammonium nitrate compared to other ammonium compounds, and then the kinetics and thermodynamics of Cr(VI), Cu(II), and Ni(II) ions removal from aqueous solutions on this activated carbon were studied. The adsorption data was found to follow second order kinetic model to explan the kinetics of Cr(VI), Cu(II), and Ni(II) ions adsorption, and rate constants were evaluated with the help of this kinetic model. Activation energy and other activation thermodynamic parameters (ΔS≠, ΔH≠, and ΔG≠) were determined by means of the rate constants at different temperatures. Equilibrium data were fitted to the Langmuir and Freundlich adsorption isotherms. Freundlich isotherm best fits the experimental results. Thermodynamic parameters such as KC, ΔG, ΔH, and ΔS were also calculated. The positive value of ΔS and negative values of ΔG showed the spontaneous of this adsorption system, while the positive value of ΔH pointed out this is an endothermic process. © 2013 Copyright Taylor and Francis Group, LLC.