Dependence of diffusive permeation rates on upstream and downstream pressures

Pervaporation characteristics of cross-linked poly(dimethylsiloxane) membranes for removal of various volatile organic compounds from water

“…4. A high VOC/water selectivity with increasing downstream pressure is due to the more open structure of the dry layer of the membrane surface on the downstream side [28]. On the other hand, the normalized permeation rate decreased with increasing downstream pressure, due to a decrease in the driving force.…”

Pervaporation performance of unfilled and filled PDMS membranes and novel SBS membranes for the removal of toluene from diluted aqueous solutions

“…The effect on sorption of components is less clear. Greenlaw et al [52] studied the effect of the downstream pressure of hexane permeability through a rubbery membrane. The authors observed an increased hexane permeability, which was explained by an increased concentration, and hence sorption, into the membrane.…”

Concentration by pervaporation of aroma compounds fromFucus serratus

“…Also, previous works on organic solutes have shown that greater¯ux may be achieved with high¯ow-rates and low downstream pressures. 5,6,40 Experiments were performed at a¯ow-rate of 120 dm 3 h À1 and a downstream pressure of 140 Pa, using a feed volume of 0.4 dm 3 . Total¯uxes (water and aroma) of around 14 g m À2 h À1 have been obtained, which are close to values reported in the literature for this kind of membrane.…”

“…Previous works have shown that greater¯uxes were obtained when operating pressure was inferior to compound saturation pressure. 5,6 To compare with previous works regarding aroma pervaporation, an apparent selectivity, b, has been calculated for each compound, the selectivities being from 34 to 524. These selectivities are lower than those reported in the literature by up to a factor of ten-fold.…”

“…Components ®rst absorb in the organophilic top layer, then diffuse towards the other side of the membrane where they evaporate and are (Received 26 February 1999; revised version received 22 December 1999;accepted 19 January 2000) withdrawn by a vacuum system. 5,6 Finally, they are recovered by condensation. Large product volumes can be treated.…”