In this paper a novel separation concept is presented. Application to the separation of azeotropic mixtures is discussed and is illustrated with modeling and experimental results. The proposed concept makes use of an additional gaseous component to enhance separation. In counter diffusion this enhancer will exhibit a larger friction with one of the components of the mixture than with the others; lowering the flux of this component while leaving the flux of the other components almost unaltered. Use of this concept in a shell and tube module will lead to a separation. We present modeling and experimental results for the separation of ethanol/H2O mixtures using CO2 as an enhancer and discuss that separation of the azeotrope is possible with this concept. (c) 2007 Elsevier B.V. All rights reserved.