Supramolecular cellulose-based heavy metal adsorbent for efficient and accurate removal of cobalt (II) for water treatment

Heavy metal ions' high toxicity, carcinogenicity, and non-degradability have been identified as the most severe environmental concerns. Therefore, in this study, a new type of cellulose-based ionic imprinting adsorbent (p-CMs@EPI@PEI@Cys-IIP) with a three-dimensional pore structure was developed to selectively adsorb cobalt (II) using a simple ion-cross-linking technique. In this experiment, p-CMs@EPI@PEI@Cys-IIP were prepared by modifying cellulose microspheres (p-CMs) with epichlorohydrin (EPI), polyethyleneimine (PEI) and L-cysteine (L-Cys).The p-CMs@EPI@PEI@Cys-IIP was found to be able to selectively adsorb Co (II), and it was well characterized with FT-IR, SEM, TGA, and XRD. The system adsorption experiment proved that the maximum adsorption capacity reached 158.93 mg g-1, below the pH 7. After five cycles, the adsorption capacity of p-CMs@EPI@-PEI@Cys-IIP still remained above 90%. The results of selectivity experiments indicated that p-CMs@EPI@PEI@Cys-IIP has preferential selectivity for Co (II). The adsorption isotherm and kinetic experiment of Co (II) conformed to the Langmuir model and pseudo-second-order kinetic, respectively. The adsorption process of Co (II) on p-CMs@EPI@PEI@Cys-IIP was also affected by the intra-particle diffusion model. Due to its simple preparation method and good adsorption performance, p-CMs@EPI@PEI@Cys-IIP would have a good application prospect in the selective removal of Co (II) for water treatment.