The phase behaviour of isopropanol/water/NaCl mixtures at atmospheric pressure

Abstract

Alcohol-based biofuels will play a key role in substituting the fossil fuels used in transportation and power generation. Compared to fossil fuels, alcohol-based biofuels have a lower carbon footprint and can be produced from the fermentation of biomass. Moreover, some branched alcohols have similar properties to those of gasoline which makes them suitable chemicals to produce gasoline-like biofuels. To produce high-purity fuel-grade alcohols, the produced alcohol must be separated from the aqueous fermentation broth usually through distillation. However, distillation is an energy-intensive operation with a high carbon footprint; and the presence of azeotropes of alcohol/water makes distillation very expensive and technically challenging. The addition of some salts to the fermentation broth triggers a liquid-liquid phase splitting. One of the liquid phases is rich in alcohol and the other is rich in water. Therefore, understanding the phase behaviour of alcohol/water/salt mixtures is very important in the design of liquid-liquid operations for alcohol production. [...]