Transport across polymer-supported liquid

C.Y. Zhu and R.M. Izatt, Macrocyclic-mediated separation of Eu2+ from trivalent lanthanide cations in a modified thin-sheet-supported liquid membrane system, J. Membr. Sci., 1990, 50, 319 P.R. Brown, J.L. Hallman, L.W. Whaley, D.H. Desai, M.J. Pugia and R.A. Bartsch, Competitive, proton-coupled, alkali metal cation transport across polymer-supported liquid membranes containing s>yn(decyl-dibenzo-16-crown-5-oxyacetic acid) Variation of the alkyl 2-nitrophenyl ether membrane, ibid., 1991, 56, 195. 

Actinides, in nitric acid waste, 182 Advancing-front model, ELMs, 18,68 Alkali metal cations transport across bulk liquid membranes, 89-92 transport across liquid surfactant membranes, 93-95 transport across polymer-supported liquid, 95-96... 

Transport of Alkali Metal Cations Across Polymer-Supported Liquid fembranes... 

SILP systems have proven to be interesting not only for catalysis but also in separation technologies [128]. In particular, the use of supported ionic liquids can facilitate selective transport of substrates across membranes. Supported liquid membranes (SLMs) have the advantage of liquid phase diffusivities, which are higher than those observed in polymers and grant proportionally higher permeabilities. The use of a supported ionic liquid, due to their stability and negligible vapor pressure, allow us to overcome the lack of stability caused by volatilization of the transport liquid. SLMs have been applied, for example, in the selective separation of aromatic hydrocarbons [129] and CO2 separation [130, 131]. 

In the present paper, we examine the influence of structural variation within series of crown ether carboxylic acid and crown ether phosphonic acid monoalkyl ester carriers upon the selectivity and efficiency of alkali metal transport across three types of liquid organic membranes. Structural variations within the carriers include the polyether ring size, the lipophilic group attachment site and the basicity of ethereal oxygens. The three membrane types are bulk liquid membranes, liquid surfactant (emulsion) membranes and polymer-supported liquid membranes. 

Figure 10. Competitive Alkali Metal Transport Across a Polymer-supported Liquid Membrane by an Analog of 5.

The well known complexing properties of macrocyclic compounds towards metal ions have led to their incorporation into polymeric matrices. Polymer-supported crown ethers have many advantages, such as easy handling and recoverability when used for the removal of the toxic metal ions from the environment. Crown ether-, calixarene-, calixcrown- and cyclodextrin- based polymers have been recently receiving attention as the new polymers and may be processed into materials suitable as the extractant (solvent extraction), collector (ion flotation) or the ion carrier (transport across liquid membranes or ion selective electrodes). 

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