A NEW VARIANT OF THE RAYLEIGH DISTILLATION METHOD FOR THE DETERMINATION OF LIMITING ACTIVITY-COEFFICIENTS

A new variant of the Rayleigh distillation method for the measurement of limiting activity coefficients has been developed. The method is based on the determination of changes in the concentration and amount of the dilute solution caused by saturation with the solution vapor of an inert gas bubbled through the solution. Experimental conditions needed to obtain accurate values of limiting activity coefficients have been identified by means of an error analysis. In terms of limiting relative volatility, the applicability range of the proposed method appears to be 1 < alpha-12 infinity < 70, thus complementing well those of comparative ebulliometry and inert gas stripping (exponential dilutor) methods. Limiting activity coefficients measured by the new method are presented for five hydrocarbons in three oxygenated solvents.