Pervaporation is a membrane-based separation technology and is very useful for separating the azeotropic or constant boiling mixtures. In the pervaporation, the liquid mixture to be separated (called the feed) is placed in contact with one side of membrane and the permeated (called the permeate) is removed as a low-pressure vapor from the other side. The permeate vapor can be condensed and collected or released as desired. The chemical potential gradient across the membrane is the driving force for the mass transport. Additionally, this driving force can be created by applying either a vacuum or an inert purge like air or steam on the permeate side to maintain the permeate vapor pressure lower than the partial pressure of the feed liquid.

The governing equation is diffusion through the membrane pores. Here is an excellent reference on you need to read to understand the diffusion equations.

Seader and Henley. Separation Process Principles. Second Edition, Wiley Publisher.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

Thanks Professor Yehia Khalil... sir, there are so many equations given on that.. can you please tell me the main equations..also suggest me any method to solve those equations.

@ Peter Kapusta sir. i want to learn basics . that is why i am asking for the main governing equations. as many people have done their work on modeling of this process but the equations are so complex..

Pervaporation process

In the pervaporation process a liquid feed stream is first pre-heated to operating temperature and then routed to a membrane module. The permeate transported through the membrane is vapourised on the permeate side of the membrane and heat is dissipated from the feed. As the partial pressure of the transported component, and with it the driving force for mass transportation, decreases at declining temperature, the feed mixture has to be re-heated. In most cases, re-heating takes place outside the modules in separate heat exchangers. Therefore for larger plants and high permeate rates, it may be necessary to provide for a very large number of small membrane modules with upstream heat exchangers. The vaporous permeate leaving the membrane module is condensed in an external heat exchanger. The vacuum pump is only used for the removal of the inert gases, but has no other function in the process. See also for more information: http://pervaporation-membranes.com/home/introduction-to-pervaporation-and-vapor-permeation/

@ Frans Velterop . Thanks