Chapter 1.6 - Phase behaviour of organic solid solutes and supercritical fluids with respect to particle formation processes

Abstract

This chapter elaborates phase behavior of organic solid solutes and supercritical fluids with respect to particle formation processes. Naphthalene melting points in the presence of pure CO2, pure CHF3, and a mixture composed of 70 mol% CO2 and 30 mol% CHF3 were determined visually. In case of the two former systems, the experimental UCEP was estimated by locating the intersection of the SLG-line with the apparent critical mixture curve. In the CHF3/naphthalene system, the pressure was too high to observe an UCEP because of experimental limitations. All SLG lines of the mixtures investigated exhibit a slight temperature minimum, which is more distinct with an increasing amount of CHF3. The experimental SLG line is represented by the Redlich–Kwong–Soave–EoS and the Peng–Robinson–EoS using two binary interaction parameters fitted exclusively to the UCEP. From an engineering point of view, these EoS are able to predict the solubility and the partial molar volume of a solute in a supercritical solvent, as well as the liquid and vapor composition along the SLG line reasonably well; although, neither solubility nor partial molar volume data were used to fit the binary interaction parameters. The importance of the knowledge of the SLG line and of the phase behavior of the systems involved for the production of nanoscale particles is also clarified in this chapter.