Effect of the nature of the crosslinking agent on the metal-ion complexation characteristics of 4 mol % DVB- and NNMBA-crosslinked polyacrylamide-supported glycines

Metal-ion complexation behavior of glycine functions supported on divinylbe nzene (DVB)- and N,N'-methylene bisacrylamide (NNMBA)-crosslinked polyacryl amide was carried out toward Co(II), Ni(II), Cu(II), and Zn(II) ions. The p olymeric ligands and the derived metal complexes were characterized by IR, UV, and EPR spectra and by SEM. The metal-ion complexation of the rigid DVB -crosslinked system is lower than that of the semirigid NNMBA-crosslinked s ystem. The glycine ligands renervated after the desorption of the metal ion s showed an unusual specificity toward the desorbed metal ion. The low degr ee of crosslinking makes the desorption process simple and shows fast rebin ding kinetics. The metal-ion-desorbed polymeric ligands would have pockets or holes characteristic of the desorbed metal ion, resulting in its specifi c rebinding. The rigidity of the crosslinking also determines the kinetics of metal-ion rebinding. The specificity and selectivity characteristics of the crosslinked polymeric ligand was found to be increased as the crosslink ing agent changes from semirigid NNMBA to rigid and hydrophobic DVB. Thus, copper-desorbed resins showed an increased specificity toward copper ions a nd selectively binds copper ions from a mixture of copper and cobalt ions. The metal-ion specificity and selectivity characteristics of the metal-ion- desorbed system is exploited for the concentration of desorbed metal ions f rom a mixture of metal ions. The resin is amenable for a continuous process and can be regenerated several times. (C) 1999 John Wiley & Sons, Inc.