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    Title: Influence of downstream pressure on the pervaporation of water—tetrahydrofuran mixtures through a regenerated cellulose membrane (Cuprophan)
    Authors: Neel, J.;Nguyen, Q. T.;Clement, R.;林達鎔;Lin, Dar-jong
    Contributors: 淡江大學化學工程與材料工程學系
    Date: 1986-07
    Issue Date: 2010-03-09 10:00:58 (UTC+8)
    Publisher: Amsterdam: Elsevier BV
    Abstract: Water—tetrahydrofuran mixtures of different compositions were fractionated by pervaporation through a hydrophilic regenerated cellulose membrane (Cuprophan). Fluxes and selectivities were measured at 20°C and 30°C under varying downstream permeate pressures, P, Two different transport modes, I and II, were successively identified when downstream pressure, P, was progressively increased. Under a low permeate pressure (mode I), the process is mainly controlled by the high resistance which the slightly swollen downstream membrane layer opposes to tetrahydrofuran transport. Under these conditions, the water flux is maintained at a high level, since water desorption is rapid at the membrane—vapour interface. These phenomena result in fairly good selectivity. Beyond a certain pressure threshold, P1, which is temperature-dependent, desorption slows down and the downstream layer of the membrane becomes more extensively swollen. Both feed components can therefore easily diffuse through it and the partial fluxes vary in such a way that the permeate stream remains saturated under the conditions (pressure and temperature) established in the downstream half-cell of the apparatus. Considering the respective saturating pressures and diffusivities of the two feed components (water and tetrahydrofuran), this requirement implies that any further pressure increase (mode II) results in a steep selectivity decline. Transition between the two distinct regimes I and II merits consideration with a view to optimizing the operating conditions of a thermopervaporation unit.
    Relation: Journal of membrane science 27(2), pp.217-232
    DOI: 10.1016/S0376-7388(00)82059-1
    Appears in Collections:[化學工程與材料工程學系暨研究所] 期刊論文

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