In this paper, we develop an xpression of Fick's law to be used in the diffusion-solution model when coupling exists. To derive this relationship we have manipulated the generalised Stefan-Mawell equation to get a more convenient generalised multicomponent Fick's law in which clearly defined diffusivities and coupling coefficients appear: the two equations are wholly equivalent. In the general accepted frame of hypotheses when using the solution-diffusion model we have written Fick's equation when coupling betwwen the fluxes exists. The order of magnitude of coupling is calculated, using previously published xperimental data, leading to the conclusion that coupling, in selective pervaporation process, can be neglected.

Two-phase electrophoresis, coupling traditional solvent extraction with electrophoresis, is a novel separation technique. Being bio-compatible, aqueous two-phase electrophoresis provides a successful method for separating mixtures of biomolecules. In this work, the separation of amino acids by aqueous two-phase electrophoresis was examined with dextran-polyethylene glycol-water as a working system. The influences of separation time, field strength, initial solute concentration and two-phase contact area were studied in intermittent separation equipment. The experiment results show that aqueous two-phase electrophoresis is an effective separation technique for amino acids. With time, field strength, and contact area increasing, mass fluxes across the interface are increased quickly.

Aqueous two-phase systems (ATPSs) formed by spontaneous phase separation of different water-soluble polymers are bio-compatible. Aqueous two-phase electrophoresis, coupling traditional solvent extraction with lectrophoresis, is a novel separation technique and provides a successful method for separating mixtures of biomolecules. In this work, the selective recovery of amino acids by aqueous two-phase electrophoresis was examined with dextran-polyethylene glycol-water as a working system. The experiment results show that glutamic acid can be separated from phenylalanine and tryptophan successfully. The influences of the electrophoresis time, field strength, and phase volume ratio were studied in an intermittent separation equipment.

Sorption and pervaporation experiments were carried out with cellulose triacetate membranes for the separation of methyl tert-butyl ether and methanol mixtures. The sorption experiments show that with an increase of MeOH concentration in the feed, the membrane swelling ratio increases first until a maximum value is reached and then remains constant. On the other hand, the MeOH concentration in the sorped phase first decreases to a minimum value and then increases with the transition occurring near the azeotropic point. In the pervaporation experiments, the total and MeOH permeation fluxes were found to increase with the increase of MeOH concentration in the feed while the MTBE permeation flux first increases and then decreases. The total permeation fluxes are significantly enhanced with an increase in temperature. This temperature dependence is more pronounced at low MeOH concentration, but the extent of increase of the total permeate flux is relatively constant when MeOH concentrations are greater than 10%, and it can be described by the Arrhenius law. Selectivity decreases with the increase of MeOH concentration and becomes more or less constant at high MeOH concentrations.