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Molecular weight separation technologies

Membrane Sep r tion. The separation of components ofhquid milk products can be accompHshed with semipermeable membranes by either ultrafiltration (qv) or hyperfiltration, also called reverse osmosis (qv) (30). With ultrafiltration (UF) the membrane selectively prevents the passage of large molecules such as protein. In reverse osmosis (RO) different small, low molecular weight molecules are separated. Both procedures require that pressure be maintained and that the energy needed is a cost item. The materials from which the membranes are made are similar for both processes and include cellulose acetate, poly(vinyl chloride), poly(vinyHdene diduoride), nylon, and polyamide (see AFembrane technology). Membranes are commonly used for the concentration of whey and milk for cheesemaking (31). For example, membranes with 100 and 200 p.m are used to obtain a 4 1 reduction of skimmed milk. [Pg.368]

Solution Polymerization. In this process an inert solvent is added to the reaction mass. The solvent adds its heat capacity and reduces the viscosity, faciUtating convective heat transfer. The solvent can also be refluxed to remove heat. On the other hand, the solvent wastes reactor space and reduces both rate and molecular weight as compared to bulk polymerisation. Additional technology is needed to separate the polymer product and to recover and store the solvent. Both batch and continuous processes are used. [Pg.437]

Reverse Osmosis and Ultrafiltration. Reverse osmosis (qv) (or hyperfiltration) and ultrafilttation (qv) ate pressure driven membrane processes that have become well estabUshed ia pollution control (89—94). There is no sharp distinction between the two both processes remove solutes from solution. Whereas ultrafiltration usually implies the separation of macromolecules from relatively low molecular-weight solvent, reverse osmosis normally refers to the separation of the solute and solvent molecules within the same order of magnitude in molecular weight (95) (see also Membrane technology). [Pg.382]

The column was 25 cm long, 4.6 mm I.D. and packed with Partisil 10. It is seen that linear curves were obtained for three different solutes and two different moderators in n-heptane. Scott and Beesley [14] obtained retention data for the two enantiomers, (S) and (R) 4-benzyl-2-oxazolidinone. The column chosen was 25 cm long, 4.6 mm I.D. packed with 5 mm silica particles bonded with the stationary phase Vancomycin (Chirobiotic V provided by Advanced Separations Technology Inc., Whippany, New Jersey). This stationary phase is a macrocyclic glycopeptide Vancomycin that has a molecular weight of 1449.22, and an elemental composition of 54.69% carbon. [Pg.113]

FIGURE 5.7 Phase separation in styrene-butadiene-styrene (SBS) triblock copolymer. The isolated spherical styrene domains form the hard phase, which act both as intermolecular tie points and filler. The continuous butadiene imparts the elastomeric characteristics to this polymer. MW = molecular weight. (From Grady, B.P. and Cooper, S.L., Science and Technology of Rubber, Mark, J.E., Erman, B., and Eirich, F.R. (eds.). Academic Press, San Diego, CA, 1994. With permission.)... [Pg.127]

In order to convert the raw oils into useful material, transesterification technology is used. The oil is reacted with a low molecular weight alcohol, commonly methanol, in the presence of a catalyst to form the fatty acid ester and glycerol (Scheme 6.1). The ester is subsequently separated from the glycerol and used as biodiesel, the glycerol being used as a raw material for fine chemicals production. Although the chemistry is simple, in order to make biodiesel commercially viable the process must be... [Pg.174]


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