Liquid–Liquid Extraction

Abstract

Liquid–liquid extraction is an effective contacting method for mass transfer operations in a wide range of industrial processing operations. Evaluated using green chemistry criteria there is potential to reduce the environmental impact and energy cost of current and emerging manufacturing processes through selection of solvent systems that are non-toxic and are efficient and selective at fractionating target compounds. This chapter describes the key elements of liquid–liquid extraction processes and the criteria against which they should be evaluated. Current trends in process design and solvent selection are described, including the use of novel supercritical, ionic liquid and two-phase aqueous solvents. Examples are given of research in the extraction of organic compounds from microbiological systems which exemplify many green chemistry drivers towards low energy use, low environmental impact, and products that do not contain hazardous or undesirable artefacts of processing.