Chromatomembrane methods: Novel automatization possibilities of substances’ separation processes

Abstract

The processes of substances’ separation are a basis of numerous chemical technologies applied in various spheres of human activity. The majority of methods for separation of homogenous mixtures (liquid, gas, and fluid extraction; static and dynamic sorption; and chromatographic methods) are based upon differences in the interphase distribution of the substances. Presently, all possible phase combinations have been implemented in these methods. But the conceptual schemes for the realization of interphase distribution process are invariable: mixing and separation of phases or creation of one phase flow in regard to another, stationary phase. Regardless of the phase system used, any of those schemes allows the realization of the separation process with periodical injection of initial mixture and periodical extraction of final products. In those rare cases when continuous separation is possible—in countercurrent extraction for example—separation of phases in the flow causes serious problems. Hence, one encounters objective difficulties while automizing the processes of substances’ separation based on the differences in their interphase distribution. The first attempt to extend the boundaries of traditional schemes for the realization of the interphase distribution process was made by Martin in 1949 [1]. He proposed an idea of continuous two-dimensional chromatography. But numerous attempts to apply the idea in practice were not successful [2]. The novel possibilities to solve the problem of continuous substances’ separation in liquid–liquid and liquid–gas systems were opened up by the chromatomembrane methods based on the capillary effects in the hydrophobic porous media [3, 4]. In these methods, a chromatographic mechanism of exchange between phases is combined with the principle of separate passage of the two phases through the mass-exchange zone. The latter is realized by using hydrophobic porous membranes. Such an approach provides efficient mass exchange inherent in chromatographic methods under the conditions of continuous substances’ separation characteristic to membrane processes—most easily automated ones. © 1998 John Wiley & Sons, Inc. Lab Robotics and Automation 10: 3–13, 1998