Design of ion-imprinted amino-modified chitosan for selective chromium (Ⅲ) ion removal

Green ion-imprinting technique was applied to construct a Cr(III) ion-imprinted absorbent material from an amino functionalized chitosan derivative. First, nitrogenous organic compounds (GACS) as functional monomer is synthesized by a Schiff base reaction followed by a grafting reaction. In the end, imprinting was completed by cross-linking with epichlorohydrin (ECH) in aqueous media and eluting the coordinated ions with hydrochloric acid to obtain chromium-imprinted polymers (Cr(III)-IIP) with pores. The relevant parameters of the imprinting system were explored, and the superior polymer (Cr(III)-IIP9) has an excellent adsorption capacity 385.89 mg/g, wide pH range adsorption, good adsorption rates and equilibrium times (≤120 min) for Cr(III) ion. Additionally, the kinetic study is best defined in terms of pseudo-second order, while the Freundlich isotherm model fits the data well. Competitive adsorption of the quaternary system of Cr(III)/ Cd(II)/ Ni(II)/ Cu(II) were also investigated, it demonstrated a greater affinity for the Cr(III) ion than other ions. Hence, the imprinting materials prepared by amino functionalized chitosan enhances the adsorption of Cr(III) ions in the simulation of actual water sample. The adsorption mechanism accords with the hard and soft acid and base theory (HSAB), which is expected to be is utilized for the separation of Cr(III) ions in the environment.