Liquid-liquid equilibrium in the system acetonitrile-water-salt by infrared spectroscopy

This investigation was concerned with the development of an infrared analysis technique by which liquid-liquid equilibrium in the system acetonitrile-water-salt could be obtained.

The method developed utilized sample bottles which constituted a completely closed system from initiation to termination of each determination. The calibration curve procedure proved to be an effective method for obtaining binodal curve data in that each point was determined independently as contrasted to the well known cloud-point technique.

It was found that the analysis technique was usable for samples containing less than five weight per cent salt and i t was proposed that the method might be extended for any salt composition if the dilution by a known amount technique was used.

The previously hard-to-determine acetonitrile-rich end point could be easily and accurately determined, and the location of the plait point could be closely bracketed by employing this technique.