Supported liquid membranes ionic liquids

Supported Liquid membrane (Ionic liquid phase)... 

These types of separators consist of a solid matrix and a liquid phase, which is retained in the microporous structure by capillary forces. To be effective for batteries, the liquid in the microporous separator, which generally contains an organic phase, must be insoluble in the electrolyte, chemically stable, and still provide adequate ionic conductivity. Several types of polymers, such as polypropylene, polysulfone, poly(tetrafluoroethylene), and cellulose acetate, have been used for porous substrates for supported-liquid membranes. The PVdF coated polyolefin-based microporous membranes used in gel—polymer lithium-ion battery fall into this category. Gel polymer... 

Fortunato, R. et al.. Supported liquid membranes using ionic liquids study of stability and transport mechanism, /. Membr. Sci., 242,197, 2004. 

Wang, R., Okajima, T., Kitamura, R, and Ohsaka, T., A novel amperometric O2 gas sensor based on supported room-temperature ionic liquid porous polyethylene membrane-coated electrodes, Electroanalysis, 16, 66-72, 2004. 

Miyako, E., Maruyama, T., Kamiya, N. and Goto, M. (2003) Enzyme-facilitated enantioselective transport of (S)-ibuprofen through a supported liquid membrane based on ionic liquids. Chemical Communications, 2926. 

Martak, J., Schlosser, S. and Vlckova, S. (2007) Pertraction of lactic acid through supported liquid membranes containing phosphonium ionic liquid. Submited for publication in Journal of Membrane Science. 

The ability of calixarenes to bind large metal ions with high kinetic stability is important in the search for complexants for radionuclides such as Cs (ti/2 = 30.2 yr) and Sr (ti/2 = 65 d) from the reprocessing of exhausted nuclear fuel. There has been considerable interest in caesium-complexed calix[4]-bis-crowns as selective Cs-carriers. Transport isotherms of trace level Cs through supported liquid membranes containing calix[4]-bis-crowns have been determined as a function of the ionic concentration of the aqueous feeder solutions, and l,3-calix[4]-bis-o-benzo-crown-6 appears to be much more efficient in decontamination than mixtures of crown ethers and acidic exchangers, especially in highly acidic media. " ... 

Matsumoto, M., Ueba, K., Kondo, K. (2006). Separation of benzene/cyclohexane mixture through supported liquid membranes with an ionic liquid. Solvent Extr. Res. Dev., 13, 51-59. 

M., ViUora, G. (2007). Integrated reaction/separation processes for the kinetic resolution of rac-l-phenylethanol using supported liquid membranes based on ionic liquids. Chem. Eng. Process., 46, 818-24. 

Jiao, P. If, Huang, K. L., Peng, X. H., Zhao, X. H., Yu, J. G. (2006). Hollow fiber liquid-supported membrane technology for enantioseparation of racemic salbutamol by combinatorial chiral selectors. J. Central South Univ. Technol., 13, 39-43. Miyako, E., Maruyama, T., Kamiya, N., Goto, M. (2003). Enzyme-facilitated enantioselective transport of (S)-ibuprofen through a supported liquid membrane based on ionic liquids. Chem. Commun., 2926-7. 

In the last decade, supported liquid membranes based on ionic liquids (SILMs) have been successfully applied in separation and purification of organic compounds, involved in the synthesis of pharmaceutical and fine chemicals, (alcohol, esters, organic acids and amino acids) and mixed gases [16-25],... 

Hemtindez FJ, de los Rfos AP, Rubio M, Tomas-Alonso F, G6mez D, Vfllora G (2007) A novel application of supported liquid membranes based on ionic liquids to the selective simultaneous separation of the substrates and products of a transesterification reaction. J Membr Sd 293 73-80... 

Branco LC, Crespo JG, Afonso CAM (2002) High selective transport of organic compounds by using supported liquid membranes based on ionic liquids. Angew Chem Int Ed 41 2771-2773... 

Matsumoto M, Inomoto Y, Kondo K (2(X)5) Selective separation of aromatic hydrocarbons through supported liquid membranes based on ionic liquids. J Membr Sci 246 77-81... 

Cserj si P, Nemest6thy N, Vass A, Csanadi Zs, B lafi-Bak6 K (2009) Study on gas separation by supported liquid membranes applying novel ionic liquids. Desalination 245 743-747... 

In a later work, both the CuCl/KCl molten salt Wacker oxidation system and a [Bu4N][SnCl3] system (melting point 60 °C) was applied to the electrocatalytic generation of acetaldehyde from ethanol by co-generation of electricity in a fuel cell [56]. In the cell set-up, porous carbon electrodes supported with an ionic liquid catalyst electrolyte were separated by a proton conducting membrane (Fig. 5.6-4), and current efficiency and product selectivity up to 87% and 83%, respectively, were reported at 90 °C. 

Supported liquid membranes (SLM) containing ionic liquids have been used successfully for selective transport of, e.g. alcohols, ketones, amines [115,116] and aromatic hydrocarbons [117], according to the concentration gradient of the substance and its solubility in the ionic liquid. 

A new and promising way of combining reaction and extraction are supported liquid membranes (SLM). Miyako et al. used SLMs on the basis of different water-immiscible ionic liquids and aliphatic hydrocarbons to achieve pure (S)-ibuprofen together with an enzymatic resolution step (Scheme 8-6). Only the (S)-enantiomer is esterified by the enzyme attached to the feed interface and able to enter the membrane. The ionic-liquid phase allows the selective transport of the more hydrophobic ibuprofen methyl ester from the aqueous-feed phase to the receiving phase. At the inter ce of the receiving phase, the (S)-ibuprofen methyl ester is hydrolysed to (S)-ibuprofen by another lipase. As (S)-ibuprofen is more hydrophilic it is not transported back through the supported ionic-Hquid phase. Best results were achieved with [BMIM]( (CFjSOijiN] as liquid membrane phase and the enzyme combination mentioned in Table 8-3 [85,86]. 

On the basis of this mechanism, a great number of ionophore-based ISEs were developed. It should also he noted here that polyvinyl chloride (PVC) has been used since the early 1970s to support liquid membranes, and the term plasticized liquid membrane" has been coined to describe these systems. In those days, the addition of ionic sites was not explicitly realized, but instead, impure ionic sites in the PVC (anionic sites) played virtually the same role. However, the membrane including such an impurity does not allow quantitative control of the optimized amounts of ionic sites, and therefore, it was supplemented later by deliberately added ionic sites. 

A.P. de los Rfos, F.J. Hernindez-Femandez, M. Rubio et al.. Prediction of the selectivity in the recovery of transesterification reaction products using supported liquid membranes based on ionic liquids. J. Membr Sci. 307 (2008) 225-232. 

M. Matsumoto, Y. Inomoto, K. Kondo, Comparison of solvent extraction and supported liquid membrane permeation using an ionic liquid for concentrating penicillin G. J. Membr Sci. 289 (2007) 92-96. 

Supported liquid membrane extraction (SLME) is emerging as a fast and efficient sample preparation technique. Aromatic aminophosphonate isolation from water samples based on SLME allowed the identification and study of the operational parameters (pEI and ionic strength of the aqueous phase, composition of the membrane phase, and concentration of analytes) as well as the structure-extraction efficiency relationship. 

These have the advantage of high membrane flux, which results from the very small thickness of the organic membrane. However, there are a number of operational difficulties. The first of these concerns the osmotic transport of water across the membrane as a result of different ionic concentrations in the two aqueous phases. This causes the membrane drops to swell and ultimately to break down, mixing the strip and feed solutions. Another difficulty arises with the ultimate breaking of the emulsion and separation of the two phases that can give rise to entrainment problems. In addition, the overall process is much more complex than that of the supported liquid membrane. 

Depending on their structure, symmetric membranes can be catalogued as porous and non-porous or dense (polymeric swollen-network), while asymmetric membranes for desalting applications (NF and RO, basically) consist of a dense and thin active layer and a thick porous sublayer for mechanical stability (usually an UF membrane). Moreover, supported liquid membranes (SLMs), and aetivated membranes (AMs), which basically consist in the immobilization of speeifie agents (organic solvent, carrier or ionic liquid at room temperature) in the pores/structure of a support membrane, have been developed for selective separation of valuable/contaminant compoimds [8-11]. 

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