Solvation in Supercritical Fluids

Abstract

Supercritical fluids (SCFs) comprise an important class of solvents and reaction media which have found many applications in basic and applied chemical sciences. SCFs, especially supercritical carbon dioxide, play a key role as one of the most important environmentally benign solvents in the so-called “green” chemistry applications. In the context of practical applications, SCFs are becoming increasingly viable in economic terms as an alternative to conventional organic solvents for purification, fractionation, and extraction of valuable organic compounds from a wide range of natural matrices∗ [1,2,3,4]. Academic and commercial extraction units are available for selective extraction of organic substances based on supercritical carbon dioxide (SC-CO2). Two of the most successful and profitable large-scale SCF-based extraction processes are the extraction of caffeine from coffee beans and tea leaves and nicotine from tobacco. In the case of coffee beans, at the end of the extraction process one is left on one hand with whole tasteand aroma-preserved decaffeinated coffee, much appreciated by an important segment of the consumers market, and, on the other hand with high-purity caffeine which is a valuable commodity for pharmaceutical and food industries. The potential for supercritical fluid extraction and purification of substances of high aggregated economic value is enormous in Brazil due the overwhelming biodiversity of its forests, comprising from 55,000 to 350,000 of known species of plants in the world [5]. Studies of the economic viability of SCF extraction of several