Adsorption isotherms, kinetic and thermodynamic studies on cadmium and lead ions from water solutions using Amberlyst 15 resin

Abstract

Adsorption isotherms, kinetic and thermodynamic parameters for Cd(II) and Pb(II) ions in water solutions by using Amberlyst 15 resin were performed and evaluated by utilizing solid phase extraction method with the batch system at 298, 308, and 318 K. Flame atomic absorption spectrometry was utilized for absorbance measurements of Cd and Pb in solutions. The Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models, respectively were implemented to equilibrium results obtained. Experimental and theoretical monolayer adsorption capacities of resin for adsorptions of Cd(II) and Pb(II) by the Langmuir isotherm model were approximately the same and they were 120 and 116 mg/g for Cd(II) and Pb(II) ions, respectively at 318 K. Most appropriate kinetic model for adsorption of Cd(II) and Pb(II) on the resin was found as pseudo-second-order. Contact time and temperature for adsorption of analytes on the resin were optimized at 45 min and 298 K. Activation energies (Ea) and thermodynamic values (ΔG°, ΔH° and ΔS°) were determined and assessed. Results showed that adsorptions of Cd(II) and Pb(II) on Amberlyst 15 were spontaneous, exothermic, and chemical ion-exchange processes.