Membrane technology and supercritical fluids: chemical engineering for coupled processes

The purpose of this study is to present a review of new ideas recently proposed in the field of supercritical fluid (SCF) and membrane coupled processes. The first item concerns CO 2 recovery by membranes during a supercritical fluid extraction process. The aim is here to enhance the extraction process in lowering the energy required for the CO 2 recycling. Then, supercritical CO 2 extraction coupled with nanofiltration separation is also described, and applications are proposed in order to purify low molecular weight compounds. This new process has been proposed as an environment safeguarding solution that would normally allow a high permeate, a good control of the whole extraction/separation process and a reduced energy consumption. All these advantages have been checked on model solutions and natural products. Cross-flow filtration applied to viscous liquids fluidified with supercritical carbon dioxide constitutes another interesting example. The basic idea of SCF assisted ultrafiltration is to reduce liquid viscosity at ordinary temperature by injecting a gas (CO 2) in supercritical conditions before filtration. These works, as well as other examples involving new membrane contractor or reactor types and supercritical fluids as solvents, bear testimony of the main interest to use such hybrid techniques regarding performance and environmental constraints.