Effect of spacer on the mechanism of metal adsorption in EDTA supported on a polymeric resin

In this study, we prepared two materials (A2E and A6E) into Merrifield resin (MR), chanching spacing group with two and six carbons and then grafted with EDTA, and the synthesis was in two reaction steps by microwave assistant organic synthesis. The adsorbents (A2E and A6E) were characterized by FTIR, TGA, Kaiser's test and SEM. The effect of contact time, pH and dosage on adsorption of Cu2+ and Mn2+ from acid aqueous solutions were investigated with the purpose of addressing a regional problem in the state of Sonora, northwest of Mexico. Pseudo first order and pseudo second order models were employed to describe the adsorption kinetics, with R2 values between 0.9614 and 0.9996 for both adsorbents. The experimental data were fitted by Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherm models. The adsorption process for both metals was exothermic for A2E and endothermic for A6E, and non-spontaneous for both adsorbents as evidenced by positive ΔG values.