Modeling and Simulation of Isotachophoresis for Chemical Separation of Charged Species

Numerical simulation results are obtained for isotachophoresis (ITP) in two-dimensional straight michrochannel. This 2D ITP model is formulated based on finite volume schemes using 5 ionic components: one leader (LE), one terminator (TE), two samples (Sample A and B), and a counter ion electrolyte (C). Distinct net mobilities and diffusion coefficients are assigned to all ionic components, and an electric field is maintained along the channel to carry out the electrophoretic separation in microchannel. The computer model is developed to solve mass and charge conservation equations and to satisfy electro-neutrality condition in the system. Three different finite volume schemes, e.g. power-law, hybrid and upwind, are tested to obtain the best numerical solution of this electrophoretic problem. Numerical results show that power law scheme performs better; grid Peclet number up to 20 is acceptable for this nonlinear isotachophoresis. The effects of applied electric potential, ionic mobilities and initial distribution of samples on the separation behavior are also presented.