Membrane-based extractions

The reaction in a homogeneous solution with a polar organic solvent in which the enzymes and substrates are both soluble, occurs often at the expense of the enzyme stability [4, 5]. Besides immobilised enzymes in organic solvents [6], emulsion reactors, especially enzyme-membrane-reactors coupled with a product separation by membrane based extractive processes [7-9] and two-phase membrane reactors [10-12], are already established on a production scale. 

DEVELOPMENTS IN DISPERSION-FREE MEMBRANE-BASED EXTRACTION-SEPARATION PROCESSES Anil Kumar Pabby and Ana-Maria Sastre... 

Brose, D.J., Chidlaw, M.B., Friesen, D.T., Lachapelle, E.D. and Vaneikeren, P. (1995) Fractionation of citrus oils using a membrane-based extraction process. Biotechnology Progress, 11, 214. 

Vajda, M., Kosufhova, A. and Schlosser, S. (2004) Membrane-based extraction joined with membrane-based stripping in a circulating arrangement - III. Extraction of zinc. Chemical Papers, 58, 1. 

The efficiency of membrane-based extraction is related to the diffusion and partitioning coefficients [38 0]. 

The MMLLE technique can be seen as a complement to the SLM extraction, permitting membrane-based extraction to be extended to further classes of compounds. Compared with SLM, MMLLE has the following characteristics ... 

Schlosser S, Sabolova E, and Martak J. Pertraction and membrane based extraction of carboxylic acids in hollow fibre contactors. In Cox M, Hidalgo M, and Valiente M Eds. Solvent Extraction for the 21st Century. Proceedings of ISEC 99, Barcelona, Spain, July 1999. Publisher Society of Chemical Industry, London, UK 2001 2 1041-1046. 

Solichien MS, O Brien D, Hammond EG, and Glatz CE. Membrane-based extractive fermentation to produce propionic and acetic acids Toxicity and mass transfer considerations. Enzyme Microbial Technol, 1995 17(1) 23-31. 

Gupta, SK. Actinides Recovery Using Membrane Based Extraction Technique, MSc thesis (Research), University of Mumbai, 2003. Gupta, SK. et al. Non-dispersive extraction of Am(III) using PC-88A as an extractant, at DAE Symposium on Nuclear and Radiochemistry (NUCAR-2003) BARC Trombay, Mumbai, February 10-13, p. 133, 2003. 

The term contactor systems present only membrane devices, mosdy hollow-fiber, but not processes. The membrane in a contactor acts as a passive (not selective) barrier and as a means of bringing two immiscible fluid phases (such as gas and hquid, or an aqueous hquid and an organic hquid) in contact with each other without dispersion. The phase interface is immobihzed at the membrane pore surface, with the pore volume occupied by one of the two fluid phases that are in contact. Contactor devices are used in many of the above-mentioned BLM systems (HLM, HFCLM, HFLM, FLM, pertraction, membrane-based extraction, MHS) as construction units. Sometimes, selective hydrophobic, hydrophihc, or ion-exchange membranes are used as barriers for additional selective separation in the devices similar to contactors. 

Internal (earner) driving force coefficients, Kf. and fCbex, or distribution coefficients, Ey. and fr, data [15] are determined by membrane-based extraction experiments. Membrane-based forward and backward extraction are carried out in two compartment modules, separated by the same membranes. The experiments lasted up to equffibrium conditions, when the concentration of solutes in every compartment is not changed with time. 

Application of Membrane-Based Extraction Techniques to Food and Agricultural Samples... 

Table I. Major membrane-based extraction techniques used for food and...

The supported liquid membrane extraction is generally one of the most selective membrane based extraction techniques. Selectivity is tuned by adjusting the foctors described above. However, like other membrane based extraction techniques, so far it has been applied to mostly environmental and biological samples as seen in review articles (30,31,34). 

Membrane based extractions are capable of complementing conventional techniques (liquid-liquid and solid phase extractions) in food and agricultural sample preparation. Their attractiveness in sample preparation is based on their selectivity and ability to tolerate samples with high organic content and/or dissolved solid. They can also be easily automated and interfaced to other separation techniques. However, despite these advantages, membrane based extractions especially SLM extraction and MMLLE techniques have not been applied much to food and agricultural samples as compared to PME techniques. 

The continuous production of bacterial alginate from A. vinelandii coupled to membrane-based extraction appears to be possible but more detailed investigation must still being performed in order to optimize the process. However, it should be remarked the possibility of controlling the stmcture of resultant alginates obtained by using genetically modified bacteria. 

A.K. Pabby, A.M. Sastre, State-of-the-art review on hollow fibre contactor technology and membrane-based extraction processes, Journal of Membrane Science 430 (2013) 263-303. 

This chapter reviewed the main results from the literature on HFM technology and membrane-based extraction and offers a perspective on the success of this research and its impact on membrane separations. Considerable progress has been made in a number of key areas, with some important and unanticipated developments. This type of technology assessment can play an important role in setting the directions for future research and development, both for individual scientists and engineers and for the broader membrane community. 

Jbnsson jA. Membrane-based extraction for environmental analysis. In Pawliszyn J, Le XC, Li X-F, Lee HK, eds. Comprehensive Sampling and Sample Preparation. Oxford, U.K. Elsevier Academic Press 2012 pp. 591-602. 

Zorita S, Hallgren P, Mathiasson L. Steroid hormone determination in water using an environmentally friendly membrane based extraction technique. / Chromatogr A 2008 1192 1-8. 

Kathios et al. [46] demonstrated the utility of the membrane-based extraction modules for the extraction of neodymium (a surrogate for trivalent americium) from 2 M HNO3 using dihexyl-A,A-diethylcarbamoylmethylphospho-nate (DHDECMP) and octyl(phenyl)-A,A-diisobutyl car-bamoylmethylene phosphine oxide (CMPO) as the organic... 

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