Novel MOFs-based ion-imprinted polymer for selective separation of cobalt ions from waste battery leaching solution

A novel metal–organic framework (MOF)-based cobalt ion-imprinted polymer (MOF-IIP) was prepared by grafting 2-pyridinecarboxaldehyde (PCA) onto UiO-66-(OH)2 for the selective separation of Co(II) from waste battery leaching solution. The structure and property of MOF-IIP were characterised by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analyses. The adsorption mechanism was explored by X-ray photoelectron spectroscopy (XPS). The adsorption performance was investigated based on batch adsorption experiments, and the results indicated that the adsorption conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, and that it was a homogeneous monolayer exothermic process. Under the optimal parameters, the maximum adsorption capacity of MOF-IIP for Co(II) was 132.8 mg/g, which is higher than the values reported for most imprinted materials. In addition, the selectivity coefficients of MOF-IIP for Co(II)/Ni(II), Co(II)/Ca(II), Co(II)/Li(I), and Co(II)/K(I) were 1.20, 4.61, 78.40, and 3.71, respectively, which were significantly better than those of MOFs-based non-imprinted polymer (MOF-NIP; 0.35, 3.54, 24.9, and 3.00, respectively). In this study, MOFs were used as the matrix to prepare an imprinted adsorbent for the selective separation of cobalt ions. The outstanding adsorption capacity and excellent selectivity obtained in the experiments showed that MOFs-based imprinted materials have great potential for highly selective separation and recovery of metal ions.