[Streaming gravity-diffusive effect for a series of two flat polymeric membranes oriented horizontally]

In this paper the results of study flux gravidiffusive effect for a double-membrane osmotic-diffusive cell, in which series of two (Ml and M(r)), microporous and symmetrical flat polymeric membranes (Nephrophane and Cellulose IMP-1). These membranes separate three compartments (l, m, r) containing the heterogeneous and binary (aqueous glucose or ethanol solutions) or ternary (glucose solutions in 0.75 mole.l-1 aqueous ethanol solution or ethanol solutions in 0.1 mole.l-1 aqueous glucose solution) non-ionic solutions. The solution concentrations fulfil the condition Ckl > Ckm > Ckr. The inter-membrane compartment (m) consists of the infinitesimal layer of solution. The volume of compartment m and external compartment (l and r) fulfill the conditions Vm-->0 and Vl = Vr-->infinity respectively. The study of flux gravidiffusive effect for configurations A and B of the double-membrane osmotic-diffusive cell were elaborated. In configuration A solution was placed in compartment below membrane M(r) and water above membrane Ml. In configuration B solution was placed in compartment above membrane Ml and water below membrane Ml. These results are interpreted in terms of the convective instability that increases the diffusive permeability coefficients of complexes: concentration boundary layers/membrane Ml or M(r)/concentration boundary layer.