(5f) Dynamics of Separation in An Electrical Field Flow Fractionation (EFFF) Separator with Couette Flow: Effect of Wall Velocities

Improving the separation of biomacromolecules, such as proteins, DNA, and antibiotics, to name a few, can lead to the development of novel pharmaceuticals. Electrokinetic-based methods, including electrical field flow fractionation can be used to effectively separate a variety of molecules. In electrical field flow fractionation (EFFF), an electrical field is applied perpendicular to the direction of flow in a channel, and the molecules most susceptible to the electrical field will migrate fastest to the walls, thus creating a very efficient separation (Giddings, 1993).

In this contribution, the dynamics of an EFFF separator with Couette flow is examined. In the system under study, both walls of the device move at nonzero velocities and in opposite directions to produce a Couette type of flow. Therefore, it is useful to study the effects of the wall velocities on the dynamics of separation within the device. This is accomplished by solving the transient averaged species continuity equation analytically, to obtain average concentration profiles as a function of various parameters of the system, including, the applied orthogonal electrical field, valence, electrophoretic mobility, and wall velocities. This analysis enables the determination of optimal operating conditions of the device under transient conditions.