Membrane technology developments

The abUity to control pore sizes is an important topic for membrane technology development. Membranes with controlled morphology can be used not only in separation process but also in chemical conversion supplying highly ordered and confined geometries for chemical reactions. 

Since membrane lungs as extracorporeal devices are in wide use, thoughts have turned to an implantable artificial lung prosthesis based on membrane technology. Developing such a device with the adequate characteristics and long-term reliability is a much more difficult task than encountered with the extracorporeal device developed for intermittent use. However, a small prototype device made of porous Teflon has been fabricated and tested by Richardson and Galletti. ... 

Membrane Technology Developments. The three major membrane suppliers are DuPont, Asahi Glass, and Asahi Kasei. All these manufacturers are constantly striving to improve membranes to achieve low energy consumption, long life, and insensitivity to impurities and upsets in operation. 

In order to maintain a definite contact area, soHd supports for the solvent membrane can be introduced (85). Those typically consist of hydrophobic polymeric films having pore sizes between 0.02 and 1 p.m. Figure 9c illustrates a hoUow fiber membrane where the feed solution flows around the fiber, the solvent—extractant phase is supported on the fiber wall, and the strip solution flows within the fiber. Supported membranes can also be used in conventional extraction where the supported phase is continuously fed and removed. This technique is known as dispersion-free solvent extraction (86,87). The level of research interest in membrane extraction is reflected by the fact that the 1990 International Solvent Extraction Conference (20) featured over 50 papers on this area, mainly as appHed to metals extraction. Pilot-scale studies of treatment of metal waste streams by Hquid membrane extraction have been reported (88). The developments in membrane technology have been reviewed (89). Despite the research interest and potential, membranes have yet to be appHed at an industrial production scale (90). 

S. Torrey, ed.. Membrane and Ultrafiltration Technology, Developments Since 1981, Noyes Data Corp., Park Ridge, N.J., 1984. 

One unique appHcation area for PSF is in membrane separation uses. Asymmetric PSF membranes are used in ultrafiltration, reverse osmosis, and ambulatory hemodialysis (artificial kidney) units. Gas-separation membrane technology was developed in the 1970s based on a polysulfone coating appHed to a hoUow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

Another example of the high-temperature membrane technologies is a dual-phase membrane developed at Columbia University, which consists of solid oxide and molten carbonate. This membrane technology takes advantage of oxide and carbonate ionic transport. At the face of the membrane exposed to the high concentration of COz, carbonation dioxide... 

VaporSep A family of separation processes, based on membranes which are selectively permeable to organic vapors. Developed by Membrane Technology Research, CA, in the... 

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