Separation of multi-component mixtures by the use of the anomalous regime in the diffusivity

Abstract

The dependence of the self-diffusivity D on the reciprocal of the square of the Lennard-Jones sorbate parameter 1/δ ² is known to exhibit two distinct regimes: (i) the linear regime, where D α 1/δ ², and (ii) the anomalous regime, in which this proportionality does not hold. The existence of the anomalous regime has been attributed to what is termed the levitation effect. In the present work, the possibility of using the levitation effect to advantage in the separation of a multi-component mixture has been explored. The computer experiment is designed to mimic experimental conditions as far as possible. Two mixtures have been studied, one in which all three components belong to the linear regime, and another in which one of the three components belongs to the anomalous regime. Results suggest that good separation may be achieved at low temperatures, especially when one of the components of the mixture belongs to the anomalous regime in the dependence of self-diffusivity on the reciprocal of the squares of the sorbate size.