Immobilization of Cyphos Ionic Liquids in Alginate Capsules for Cd(II) Sorption

Abstract

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.

Keywords:

• cadmium
• desorption
• diffusion
• immobilization
• isotherms
• sorption
• tetraalkylphosphonium ionic liquids

ACKNOWLEDGEMENTS

C.J., T.V., and E.G. acknowledge the financial funding from Carnot Institute for the research program “Encapsulation de liquides ioniques” (07AS 11 LGEI1); A.F.P. acknowledges the grant from Erasmus European Program for her training period at Ecole des Mines d'Alès. Authors thank Cytec (Canada) for supplying the IL and Jean-Marie Taulemesse (Ecole des Mines d'Alès, CMGD) for SEM-EDAX analysis.

Notes

MW: Molecular weight (g/mol); Diam.: diameter (µm, in the dry state); IL content (mmol g⁻¹, dry weight); W.C.: water content (% on wet weight).