Membranes steam .sterilizable

Although steam sterilizable and chemically and biologically inert, porous glass membranes generally have a maximum working temperature of 500 to 700X. They are usuaUy unstable above that temperature range. 

As shown in the right side of Fig. 9, a quadrupole mass spectrometer, MSG 300, with a gas-tight ion source, secondary electron multiplier, direction detector, and a turbo-molecular pump (TURBOVAC 150) is equipped with a membrane inlet (all from Nippon Shinku, Tokyo). The resolution scale is 300. Mass spectrometry can also be used for the measurement of dissolved gases in a liquid phase using a steam sterilizable membrane probe. Recently, the application of the mass spectrometer to fermentation processes has increased markedly. 

Sterilizability is of essential importance when the pol5mier is used in medical applications. Steam sterilization is preferred over chemical sterilization and radiation sterilization. Steam sterilization consists of a treatment of the membrane with superheated steam of >110°C for 30 min. Steam sterilizable membranes include poly(ether imide), PES and poly-(vinylidene fluoride). 

Inorganic membranes, usually appUed when high temperatures or chemically active mixtures are involved, are made of ceramics [171,172], zirconia-coated graphite [173],silica-zirconia [174],zeolites [168], or porous glass [175] among others [176]. Ceramic membranes are steam sterilizable and offer a higher mechanical stability [134], thus they may be preferably used in aseptic fermentations, since some hollow fibers are only chemically sterilizable and not very suitable for reuse. Composite materials, in which glass fiber filters are used as support for the polymerization of acrylamide monomers, were developed for the hydrolysis of penicillin G in an electrically immobilized enzyme reactor. By careful adjustment of the isoelectric point of amphoteric membranes, the product of interest (6-aminopenicillanic acid) was retained in an adequate chamber, adjacent to the reaction chamber, while the main contaminant (phenyl acetic acid), was collected in a third chamber [120]. 

The volumetric productivity (g of lactic acid/l-h) is usually greater than ten-fold that of batch or continuous processes. Ceramic tubular membranes have been used which are both steam sterilizable and resistant to mechanical stress (Xavier et al. 1995). Fermentation production of lactic acid directly from starch was optimized in an MRB using I. amylovorus (O Table 1.12). No saccharification or preliquefaction of starch... 

MAJOR APPLICATIONS Medical and household appliances that cire sterilizable by hot air and steam such as corrosion-resistant piping. Also used in electric and electronic applications such as television components. Used as membranes for reverse gas streams and gas separation. 

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