Super-critical fluids: technologies and industrial applications
■ Hidden away for almost a century in the depths of thermodynamics, the super-critical state only came to light around forty years ago when progress (relatively speaking) in high pressure physical chemistry revealed some attractive properties. Progress was modest for a long time because understanding, and therefore command of the phenomena was more laborious than was originally thought. Super-critical fluids were reserved to a happy few (who knows about their role in the preparation of "tasteless" decaffeinated coffee?) before breaking into a very high number of fields: the latest success is the launch by DuPont of Teflon produced in a super-critical environment.
The particular characteristics of super-critical processes enable developers to foresee genuine innovations. The mixing facility is due to the absence of superficial and interfacial tension and the rapidity of thermal balance comes from high molecular mobility and thermal conductivity. The fluidity is similar to that of gas and the density can be compared to that of a liquid. The quick return to usual conditions by depression means that any solute returns to solid form without having the time to form large crystals; in fact the opposite is true: with a little care, it is possible to obtain particles, often spherical, measuring several dozen nm, with close-knit distribution around the median: the solvent quality is controlled by the density, and separation of the product and the solvent is particularly easy and clean.
After presenting the physical-chemical bases of the use of super-critical fluids and corresponding equipment, the survey describes a number of applications from diverse sectors, such as the pharmaceutical industry (extraction of principal active ingredients; phyto-chemistry, etc.), the field of hygiene, health and dietetics (nutraceutical, extract of algae, cosmetics, perfumes), food (texture agents, flavours, colorants, enzymes, natural extracts, etc.), materials (micro-cellular foams, nano-materials, catalytic converters, tones, wood protection treatment, etc.), fine chemistry (synthesis, polymerisation, chromatographic separation, extraction and fractioning of polymers, lubricants and extension to fine bio-chemistry), chemical engineering (drying, extraction, purification, filtration, pasteurisation, micro-encapsulation, spinning, cleaning, de-greasing, stripping, depollution) and mechanical engineering.
- Publication: March 2003
- ISBN: 2-906024-28-7
- Price for single work station: 350 euros, ex. tax
- Price for several work stations: 950 euros, ex. tax
