Preparation of ion-imprinted mesoporous silica SBA-15 functionalized with triglycine for selective adsorption of Co(II)

Abstract

A novel Co(II)-imprinted polymer (Co(II)-IIP) aimed at the selective adsorption and separation of Co(II) was prepared by modifying the surface of ordered mesoporous silica SBA-15 with triglycine (Gly–Gly–Gly) in the presence of Co(II). The prepared polymer was characterized by FT-IR, SEM, TEM and N2 adsorption–desorption techniques. The results showed that the synthesized polymer maintained high ordered mesoporous structure. The factors affecting the separation and preconcentration of the target Co(II), including solution pH, temperature, time for adsorption equilibrium, and conditions of elution were investigated in detail. The kinetics adsorption and adsorption capacity of Co(II)-IIP were estimated using batch mode experiments. The mechanism for static adsorption of Co(II) onto Co(II)-IIP was found to follow pseudo-second-order and Freundlich isotherm model. Compared with the non-imprinted polymer (NIP), the Co(II)-IIP exhibited faster adsorption rate and higher adsorption capacity. The adsorption equilibrium for Co(II)-IIP could be reached in 50min, and the maximum static adsorption capacity obtained at 25°C was 181.67mgg−1. Furthermore, the Co(II)-IIP showed excellent recognition and binding affinity toward the target cobalt ions, and the relative selectivity coefficient (k′) values of Co(II)/Fe(II), Co(II)/Cu(II), Co(II)/Zn(II) and Co(II)/Ni(II) were 19.64, 18.29, 22.03 and 27.43, respectively. Desorption and regeneration studies suggested that the prepared Co(II)-IIP could be reused five times without an obvious decrease in adsorption capacity. The results showed that this novel adsorbent could be employed as an effective material for the selective removal of Co(II) from aqueous solutions.