Supercritical water solvent, usage

With an increased interest and awareness of the impact of society and industry on the environment, there has been a significant attempt in recent years to reduce or replace the usage of organic solvents. Much early work in this area concentrated on the application of supercritical and subcritical carbon dioxide, but in recent years superheated (or subcritical/pressurized hot) water (SHW) has become of interest for both chromatography and extraction [43,54], The earliest work was reported by GuUlemin et al. [55], who used the term thermal aqueous liquid chromatography. As well as using SHW for the separation of... 

SEE is today not the only hyphenated extraction technique available. Both microwave-assisted solvent extraction (MAE) and pressurized fluid extraction (PEE) have evolved in parallel with SFE during the last decade. A thorough comparison of the different techniques can be found in the analytical literature, and will assist in choosing an appropriate technique for a specific application. These newer techniques offer both speed and simplicity, while some of the main benefits of SFE are still inherent to the usage of supercritical fluids as MAE and PFE utilize liquid solvents. More recently, subcritical water extraction has also been introduced as an environmental friendly alternative but the reader is referred to the analytical literature on this research topic. 

An interesting new approach appears the usage of supercritical fluids for the preparation of SLN aqueous dispersions or SLN dry powders. The preparation method described by Chattopadhyay et al. is basically a solvent evaporation process based on an o/w emulsion with the lipid and drug dissolved in an organic, water-immiscible solvent (chloroform). The organic solvent is then removed by the application of supercritical... 

The various use of these terms is influenced by the customs of different research communities for example, chemists and material scientists working in the super-crihcal region prefer exphcitly to use the term supercritical fltiid to characterize their approach. As a consequence, in this section we have maintained a distinction among purely hydrothermal (e.g. water-based), solvothermal (e.g. based on other solvents) and SCF processes, although in some cases this classification might be found controversial, or based on terminological and/or usage rather than substantial differences. 

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