A Brownian dynamics simulation of prolate ellipsoidal particles is developed to investigate the separation of nanotubes in flow-FFF. The particle motions are governed by stochastic forms of a linear momentum balance with orientation dependent drag and diffusion coefficients, and the Jeffrey equation with rotational diffusion. The simulation shows that nanotube scale particles would be expected to elute by a normal mode mechanism up to aspect ratios of about 1000, based on a particle diameter of 1 nm. Separation of nanotubes of different length is governed by the value of the retention variable for each component in agreement with theory. Elution profiles and average velocity through the device as a function of particle size, and throughput and cross flow flowrates are shown.
Citation: Chemical Engineering Science
Pub Type: Journals
Brownian dynamics, flow-field fractionation, Jeffrey equation, nanotubes, separations, SWNT