Cd(ii) ion was used as template ion, and N,N'-pyridine-2,6-di(2-methacrylamide) was used as the functional monomer. The experimental conditions for the synthesis of Cd(ii) ion-imprinted composite membranes (Cd(ii)-IICMs) were optimized by the surface-imprinting method, and 25 Cd(ii)-IICM1–25 and their corresponding non-imprinted composite membranes (NICM1–25) were prepared. Then, the structures of the optimal membranes Cd(ii)-IICM17 and NICM17 were characterized by scanning electron microscopy, Brunner–Emmett–Teller, thermogravimetric analysis, contact angle analysis, and the effects of different adsorption conditions were studied. The adsorption behavior was analyzed by isothermal adsorption models and kinetic models. The permeation selectivity of Cd(ii)-IICM17 towards Cd(ii) ions was studied. Results of the experiment indicate that Cd(ii)-IICM17 had excellent adsorption properties for Cd(ii) ions with an imprinting factor of 2.15. The adsorption of Cd(ii) ions in solution by Cd(ii)-IICM17 and NICM17 was in accordance with the Freundlich isothermal adsorption model and the pseudo-second-order kinetic model. In addition, in the presence of the competing ions Co(ii), Ni(ii), and Cu(ii), Cd(ii)-IICM17 showed good permeation selectivity for Cd(ii) ions, and the permeation process followed a facilitated permeation mass-transfer mechanism. In summary, the Cd(ii)-IICM17 prepared in this study has good application prospects for the separation and removal of Cd(ii) ions from wastewater.
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