Four phosphonium ionic liquids (Cyphos IL-101, IL-105, IL-109, and IL-111) have been immobilized in composite biopolymer capsules (alginate/gelatin). The resins were tested for Cd(II) sorption in HCl solutions. Cyphos IL-111 being solid at room temperature, the phase change contributes to the formation of large vesicles in the resin particle. Sorption isotherms were not affected by the anionic counterpart (chloride, dicyanamide, or tetrafluoroborate), except with bistriflamide (Cd(II) was not sorbed). HCl concentration (0.1–4.6 M) did not influence the Cd(II) uptake (60 mg Cd g 1). Kinetic profiles were modeled using the intraparticle diffusion equation. Highly porous foams have been developed as an alternative to resin beads in order to improve diffusion characteristics.

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