Nickel(II) and zinc(II) removal using Amberlite IR-120 resin: Ion exchange equilibrium and kinetics

In the present work, experimental data was obtained on ion exchange equilibrium for the binary systems Ni2+/Na+ and Zn2+/Na+ and the ternary system Ni2+/Zn2+/Na+, as well as on the kinetics of ion exchange for the binary systems Ni2+/Na+ and Zn2+/Na+, using Amberlite IR 120 resin in closed batch system at 25 degrees C and starting pH of 4.5. The model used to describe equilibrium data was the law of mass action, considering both ideal and non-ideal behaviors to represent the experimental data. Bromley's and Wilson's models were used to describe non-ideality in the liquid phase and in the resin, respectively. The thermodynamic equilibrium constant and Wilson's parameters were obtained by fitting the model to experimental equilibrium data of each binary system. The non-ideal law of mass action best described the equilibrium for the binary systems. Based on these results, only the non-ideal law of mass action was used to predict the equilibrium for the ternary system, with the parameters of the binary systems being used. There was good agreement between the predicted and experimental values of the resin phase composition. Two models were used to describe the experimental data on ion exchange kinetics. The first one considered that ion exchange reaction was the limiting step of the overall mass transfer process, while the second one considered intraparticle diffusion as the limiting step. The latter was found to best describe the experimental data on ion exchange kinetics for binary systems. (C) 2013 Elsevier B.V. All rights reserved.