Synthesis and Adsorption Performance of Surface-Grafted Co(II)-Imprinted Polymer for Selective Removal of Cobalt

The surface-grafting ion-imprinting technology was applied to synthesis of a new Co(II)-imprinted polymer [Co(II)-IP], which could be used for selective removal of Co(II) from aqueous solutions. The prepared polymer was characterized by using the infrared spectra (IR), X-ray diffractometer (XRD), X-ray energy dispersion spectroscopy (EDS) and scanning electron microscopy (SEM). The maximum adsorption capacity values for the Co(II)-imprinted polymer and non-imprinted polymer (NIP) were 22 and 8 mg/g, respectively. The Freundlich equation fitted the adsorption isotherm data well. The applicability of two kinetic models including pseudo-first-order and pseudo-second-order models was estimated on the basis of comparative analysis of the corresponding rate parameters, equilibrium capacity, and correlation coefficients. Results suggested that chemical process could be the rate-limiting step in the adsorption process. And the adsorption of Co(11) on the Co(II)-imprinted polymer was endothermic. The relative selectivity coefficients of the Co(II)-imprinted polymer for Co(II)/Pb(II), Co(II)/Cu(II), Co(II)/Ni(II), Co(II)/Sr(II) and Co(II)/Cs(I) were respectively 11.5, 6.1, 13.8, 9.4, and 8.1 times greater than that of the non-imprinted polymer. Eventually, the desorption conditions of the adsorbed Co(II) from the Co(II)-imprinted polymer were also studied in batch experiments.