Temporal and spatial structure of the concentration boundary layers in a membrane system

This paper deals with the spatio-temporal structure of the concentration boundary layers at a membrane system. This structure is studied experimentally by means of the laser interferometric technique. Concentration profiles obtained on the basis of computer analysis of interferometric pictures were subsequently used for the determination of the spatial and time structure of concentration boundary layers. Besides experimental results we also report numerical calculations of the time dependence of the thickness concentration boundary layers for two model membranes. The obtained results illustrate the influence of the parameters: D(f)-the solute diffusion coefficient in the solvent, D-the solute diffusion coefficient in the membrane, K-the solute partition coefficient and l-the thickness of the membrane on the evolution of the concentration boundary layer. Results have shown that these layers develop diffusively and their spatial structure is fully established. (C) 2003 Elsevier B.V. All rights reserved.