A NEW APPROACH TO DESCRIBING THE REGULARITIES OF STATIONARY PHASE RETENTION IN COUNTERCURRENT CHROMATOGRAPHY

Abstract

Three–dimensional surfaces, based on a large set of experi-mental data, have been built to investigate and describe the interrelations between different physico–chemical properties of two-phase liquid systems, the operating conditions of the planetary centrifuge, and the stationary phase retention. The wide range of alteration of interfacial tension, density, and viscosity differences between two phases has been provided by changing the composition of liquid systems containing an organic solvent, an extracting reagent, water and a mineral salt, the organic solvents, and extracting reagents of different nature being considered. A great body of data presents a possibility of estimating the contributions from all the enumerated physico-chemical properties of liquid systems to the stationary phase retention. It has been shown that the density difference between two phases (“the moving force” of the retention process) plays a dominant role. The range of density difference from 0.20 to 0.45 g/cm3 has been found to be favorable for stationary phase retention. It has been demonstrated that low values of interfacial tension and viscosity difference (less than 3 dyn/cm and 0.3 cP,correspondingly) have adverse effects on the stationary phase retention. The regularities evaluated enable the optimal operating conditions needed for the satisfactory retention of a certain liquid system to be chosen and offer additional insights into the hydrodynamic behavior of two immiscible iquids in a rotating coiled column.