Figure 10.

(A) The preparation strategy of Co(II)-imprinted CS/zeolite cryo-composites and removal of template ions with ethylenediaminetetraacetic acid disodium salt dihydrate (Na₂EDTA). (B) Selectivity mechanism of Co(II)-imprinted CS/zeolite cryo-composites at pH 4 and pH 6 (ion-imprinted composites = IIPZH and IIPZNa, non-imprinted composites = NIPZ and NIPNa; zeolites (Z1, Z2) converted into the H⁺ or Na⁺ form; Z1 = 60–70 wt% clinoptilolite, Z2 = 82–86 wt% clinoptilolite). (C) Optical images of IIPZH1 and IIPZNa1 composites loaded with Co(II) ions at pH 4 and pH 6. (D) SEM micrographs of IIPZH1 and IIPZNa1 sorbents loaded with Co(II) ions. (E) Selective sorption of Co(II) ions from their five-component mixtures onto the composite cryo-beads. (F) The reusability performance of IIPZH1 and IIPZNa1 sorbents after five consecutive sorption–desorption cycles. (Reproduced with permission from Ref. [100]. Copyright 2020 Elsevier).