Membrane based separations

By 1960, the elements of modem membrane science had been developed, but membranes were used in only a few laboratory and smaU, specialized industrial appHcations. No significant membrane industry existed, and total annual sales of membranes for aU appHcations probably did not exceed 10 million in 1990 doUars. Membranes suffered from four problems that prohibited their widespread use as a separation process they were too unreHable, too slow, too unselective, and too expensive. Partial solutions to each of these problems have been developed since the 1960s, and in the 1990s membrane-based separation processes are commonplace. 

Reverse Osmosis. This was the first membrane-based separation process to be commercialized on a significant scale. The breakthrough discovery that made reverse osmosis (qv) possible was the development of the Loeb-Sourirajan asymmetric cellulose acetate membrane. This membrane made desalination by reverse osmosis practical within a few years commercial plants were installed. The total worldwide market for reverse osmosis membrane modules is about 200 million /yr, spHt approximately between 25% hoUow-ftber and 75% spiral-wound modules. The general trend of the industry is toward spiral-wound modules for this appHcation, and the market share of the hoUow-ftber products is gradually falling (72). 

Membrane-based separation techniques constitute nowadays well-established process methods for industrial treatments of fluids. Like SMB, membrane-based separations can be performed in continuous mode. In the field of preparative-scale enan-tiodiscrimination, much effort has been invested in this subject due its high potential [154, 155]. (Chapter 5 of this book is devoted to the subject, and further discusses the advantages and applications of membrane technologies.)... 

Fig. 4. a Schematic of porous membrane-based separation of immiscible liquids with different wetting characteristics, b Liquid-liquid extraction device (Kralj et al. 2007)... 

Membrane-based separation, lactic acid production and, 14 120 Membrane biocompatibility, in hemodialysis, 26 823—824 Membrane bioreactors, 16 26 Membrane-bound enzymes, 10 338 Membrane cell process, 9 620 Membrane cells... 

Soni, V., Abildskov, J., Jonsson, G., Gani, R., 2006, Structural design of polymers for membrane based separation processes using reverse simulation approach, Computer Aided Chemical Engineering, (in press). 

Mohapatra, P.K. Manchanda, V.K. Liquid membrane based separations of actinides and fission products, Ind. J. Chem. 42A (2003) 2925-2938. 

MEMBRANE-BASED SEPARATIONS APPLIED TO IN VIVO GLUCOSE SENSING— MICRODIALYSIS AND ULTRAFILTRATION SAMPLING... 

Pabby, A.K. and Sastre, A.M. (2006) Hollow-fiber membrane based separation technology performance and design perspectives, in Solvent Extraction and Liquid Membranes Fundamental and Application in New Materials (eds Cortina and Aguilar), Marcel Dekker, New York. 

My knowledge grew at Bend Research, Inc. under Harry Lonsdale, another membrane pioneer who was involved in the theoretical and practical side of membranes since the early 1960 s at Gulf General Atomic (predecessor of Fluid Systems, now Koch Membrane Systems), Alza, and later Bend Research, which he co-founded with Richard Baker. At Bend Research, I had the opportunity to develop novel membranes and membrane-based separation processes, including leading several membrane-based projects for water recovery and reuse aboard the International Space Station. 

This section describes the use of separation processes which utilize membranes. Placement in this chapter is in recognition of the recent ascendency of industrial-scale membrane-based separations, but it also reflects the view that within a decade, many of these separation processes will be mainstream unit operations. Some approach that status already. Figure 22-46 shows the relative size of things important in membrane separations. 

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