Sorption of Cd(II)-MGDA Complexes on Polyacrylate Anion Exchangers

The possibility of polyacrylic anion exchangers application in the removal of Cd(II) complexes with MGDA (methylglycinediacetic acid) from aqueous solutions was presented. Batch sorption experiments were performed using Amberlite IRA 458 and Amberlite IRA 958. The initial solution pH, the initial concentration of sorbed complexes in the molar ratio M(II)-MGDA = 1:1, the temperature, as well as the contact time were varied. The kinetics of Cd(II) sorption in the presence of MGDA was analyzed. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were also applied to describe the adsorption isotherm. The values of the thermodynamic parameters (ΔG°, ΔH°, and ΔS°) indicated that in the majority of cases the sorption process was spontaneous and endothermic. From the determined breakthrough curves, the distribution coefficients and the ion exchange capacities were calculated.