Supported liquid membranes pertraction

Partitioning of components between two immiscible or partially miscible phases is the basis of classical solvent extraction widely used in numerous separations of industrial interest. Extraction is mostly realized in systems with dispergation of one phase into the second phase. Dispergation could be one origin of problems in many systems of interest, like entrainment of organic solvent into aqueous raffinate, formation of stable, difficult-to-separate emulsions, and so on. To solve these problems new ways of contacting of liquids have been developed. An idea to perform separations in three-phase systems with a liquid membrane is relatively new. The first papers on supported liquid membranes (SLM) appeared in 1967 [1, 2] and the first patent on emulsion liquid membrane was issued in 1968 [3], If two miscible fluids are separated by a liquid, which is immiscible with them, but enables a mass transport between the fluids, a liquid membrane (LM) is formed. A liquid membrane enables transport of components between two fluids at different rates and in this way to perform separation. When all three phases are liquid this process is called pertraction (PT). In most processes with liquids membrane contact of phases is realized without dispergation of phases. 

A simulation of the hybrid fermentation-pertraction process for production of butyric acid shows that the pH of fermentation and pertraction should be optimized independently [198]. It is advantageous to have the pH of the feed into pertraction at about 4.0 for both IL and TOA carriers. Choosing a proper carrier in the supported liquid membrane between IL and TOA should be made according to actual operation conditions, because of the different transport properties of these carriers in respect to the concentration of undisociated form of BA. While at lower BA concentrations the IL is better, at higher concentrations of above 20kgm 3 and pH equal to 4.0, the membrane area needed is lower for TOA. An important factor will be the toxicity of the carrier to biomass. TOA is not very good in this respect and data for IL used are not available, but it is hoped that IL will be less toxic. 

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. 

Di Luccio M, Smith BD, Kida T, Alves TLM, and Borges CP. Evaluation of flat sheet and hollow fiber supported liquid membranes for fructose pertraction from a mixture of sugars. Desalination, 2002 148(1-3) 213-220. 

Panja, S., Mohapatra, P.K., Tripathi, S.C., Manchanda, V.K. (2009). Studies on uranium(Vl) pertraction across a N,N,N N -tetraoct ldiglycolamide (TODGA) supported liquid membrane. Journal of Membrane Science 337 274-281. 

Promising results are shown by recently developed integrated SLM-ELM [84, 85] systems. These techniques are known as supported liquid membrane with strip dispersion (SLMSD), pseudo-emulsion-based hollow fiber strip dispersion (PEHFSD), emulsion pertraction technology (EPP), and strip dispersion hybrid Hquid membrane (SDHLM). AH techniques are the same the organic phase (carrier, dissolved in diluent) and back extraction aqueous phase are emulsified before injection into the module and can be separated at the module outlet. The difference is only in the type of the SLM contactors hoUow fiber or flat sheet and in the Hquid membrane (carrier) composition. These techniques have been successfuUy demonstrated for the removal and recovery of metals from wastewaters. Nevertheless, the techniques stiU need to be tested in specific apphcations to evaluate the suitabUity of the technology for commercial use. 

In the framework of the EU Life project Empereur, two full-scale emulsion pertraction installations have been built and are demonstrated at the site of the galvanic firms Loko Gramsbergen and Galvano Techniek Veenendaal (GTV), both in the Netherlands. In this technique, however, the dispersion of one liquid phase in another is not created via a membrane but rather externally in a mixer/dispersion device. This technique has also been identified as a supported liquid membrane with a strip dispersion and has been employed in a large-scale installation (Figure 4.12). More details are provided in [103,107],... 

Lakshmi, D.S., Mohapatra, P.K., Mohan, D. Manchanda, VK. (2005) Uranium(VI) pertraction through a supported liquid membrane containing Aliquat 336 and other amines in chloroform as the carrier. Proceedings of Nuclear and Radiochemistry Symposium (NUCAR-2005), 15-18 March, Amritsar, India. Paper No. CA-75. 

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