A Novel Cu(II) Ion-Imprinted Alginate–Chitosan Complex Adsorbent for Selective Separation of Cu(II) from Aqueous Solution

A novel Cu(II) ion-imprinted complex adsorbent [Cu(II)-IIP] from alginate and chitosan was prepared by a three-step process of beading–combining–crosslinking with Cu²⁺ as the template ion. The Cu(II)-IIP showed higher capacity and selectivity for Cu(II) than the non-imprinted polymer. The theoretical maximum adsorption capacity of Cu(II)-IIP reached 83.33 mg/g, and the separation factor (α) for Cu(II) versus Zn(II) was 2.28. The adsorption of Cu²⁺ onto the Cu(II)-IIP was perfectly described by the Langmuir isotherm model. The adsorption kinetics agreed with the pseudo-first-order model in the first 8 h and more fitted pseudo-second-order model after then. Weber–Morris model confirmed that the adsorption rate would be controlled dominantly by the intraparticle diffusion and the inner surface binding. Moreover, the Cu(II)-IIP complex adsorbent exhibited good regeneration, and the adsorption capacity was stable within the first three adsorption–desorption cycles without significant reduction.