Retention volumes and retention times in binary chromatography. Determination of Equilibrium Properties

Abstract

A change in the composition (accompanied perhaps by a change of flow rate) of a binary gas mixture flowing into a column which can adsorb both species gives rise to a chromatographic transient. Observed at the outlet, this is seen as the concentration varying sigmoidally with time; there is also a flow-rate fluctuation. A theory has been developed which relates these transients to the phase-equilibrium properties. A retention time is defined for the concentration transient and another for the flow transient; the slopes of the equilibrium curves are shown to be explicit functions of these retention times. Experiments to determine the slopes at infinite dilution of the equilibrium curves for the simultaneous adsorption of argon and nitrogen on Linde 5A molecular sieve by measuring both the retention times are reported.