Separation of non-volatile components by expansion with high-pressure gases

Abstract

Publisher Summary This chapter discusses the separation of nonvolatile components by expansion with high-pressure gases. The chapter illustrates the separation by two examples: the gas antisolvent process (GAS), also known as precipitation with a compressed fluid antisolvent (PCA), and supercritical antisolvent induced phase separation (SAS). In GAS, a compressed gas acting as antisolvent is dissolved in the solution of a nonvolatile component with gas contents in tile order of equimolar mixtures. This causes a volumetric expansion, and hence a remarkable reduction in solvent power. The chapter describes a new apparatus to examine liquid–liquid–vapor equilibria (LLVE) and solid–liquid–vapor equilibria (SLVE) of complex systems with non-volatile components, such as drugs or polymers. Main part of the experimental setup is a variable-volume autoclave of 1000 ml designed for pressures up to 200 bar and temperatures up to 250oC. This equipment is used for the separation of polymers by molecular weight with the SAS process. The concept of using pressure, temperature, and gas content is tested to fine-tune the selectivity of that process.