Early predictions suggested that solvents would eventually be eliminated from industrial applications because of health and environmental concerns. After a short period of a small decline in solvent use in 1990s, the solvent demand is now growing steadily by 2.3% per year.
At the same time, there have been changes in the types of solvents that are being used today. The general trend is towards elimination and replacement of some of the more toxic and environmentally unfriendly species. There has been an increase in the use of high-performance solvents, as well as the application of engineering controls to prevent accidental releases of solvents. In line with these trends, it is essential for chemical engineers to understand the parameters that are important for solvent selection, enabling them to choose a high-performance solvent for a particular application.
A recent article (A Modern Approach to Solvent Selection, CE, March, pp. 30–41) focused largely on software and Internet-based selection tools; this present article focuses more on chemical and physical properties of solvents, on solvent-solute interactions, and on applications of solvents.
PROPERTIES OF SOLVENTS
The chemical and physical properties…