Mass transport in porous liquid phase membranes

The mass transfer processes involved in transporting materials from the bulk feed solution through the membrane to form a permeate stream is discussed. The complex microhydrodynamics and interfacial events occurring at the membrane surface and within the membrane itself are outlined. A description of concentration polarization at the membrane surface is described and the concept of real and observed membrane rejection is introduced. The separation of solutes by a membrane is an equilibrium controlled process and this concept is explained in relation to that of a simple sieve and the controlling factors of steric and electrostatics are described. The effect of chemical potential on the transport of solutes through the membrane pore is explained and a mathematical description of this complex phenomena based on the extended Nernst–Planck equation is provided. Finally, the operating conditions and industrial applications of liquid phase membrane processes are outlined to provide the reader with a working knowledge of these high efficiency separation processes