Fundamentals, Mathematical Models, and Extraction Processes with Supercritical Fluids

Abstract

Supercritical fluid extraction of essential oils is currently a mature and well-known technology. Since its first developments it has gained increasing attention and has successfully reached industrial scale. Supercritical fluids have unique characteristics that can be exploited to extract and separate the main components of essential oils. They represent a substitute to organic solvents in many processes, and in the case of carbon dioxide it is a renewable, safe source that could yield high quality products. The main features of this technology, and comprehension of the underlying physicochemical mechanisms, have been elucidated and optimized. Nowadays this technology is being combined with other green operations like ultrasound, or membrane separation as a way towards process intensification, and the selective isolation of active principles from natural sources.In this chapter, the fundamentals of supercritical fluids are first discussed. Then, a typical extraction process and influence of its variables are described. Afterward, a summary of the mathematical models used to design and evaluate these processes is presented, followed by the advantages of this technology in the separation of the extracts. The last sections present a revision of some representative examples of laboratory, pilot, and industrial extraction processes of essential oils with supercritical fluids.