Optimum selective separation of Cu(<scp>ii</scp>) using 3D ordered macroporous chitosan films with different pore sizes

Although bio-materials are widely used for the adsorption of heavy metal ions, they have low specific surface area, slow adsorption rates, and poor selectivity. To overcome these limitations, in this study, we report a 3D-ordered macroporous ion-imprinted chitosan film (3DOM-IICF); the 3DOM-IICF coupled with a colloidal crystal template and ion imprinting (IIP) technology has been used to absorb copper ions (Cu(II)) present in water. Moreover, polystyrene (PS) micro-spheres and copper templates were added to form a three-dimensional ordered macroporous structure and ion-imprinted sites, respectively. Finally, the film was formed by drying. Adsorption experiments showed the removal of Cu(II) from the 3DOM-IICF in an aqueous solution. The 3DOM-IICF exhibited good adsorption performance under neutral conditions of pH = 7.0, and the adsorption efficiency was high. The maximum adsorption capacity of the 3DOM-IICF was 261.31 mg g−1. The adsorption processes were more consistent with the pseudo-second-order kinetic model and the Langmuir isotherm. The 3DOM-IICF exhibits superior selective adsorption of Cu(II). Moreover, the 3DOM-IICF could be regenerated multiple times, reused as an adsorbent and maintained high adsorption capacity. This kind of imprinted template method has important significance in the selective adsorption of pollutants in bio-materials and is worthy of in-depth research.