Supercritical fluid based technologies

Supercritical fluid- based technologies and its variations such as FormulDisp ... 

Processing of natural products with supercritical fluids-based technologies has been an extensive area of research during the past two decades. In fact, since many valuable products occurring in natural compounds, such as vitamins, aromas, natural pigments or essential oils, are soluble in supercritical fluids, their extraction from natural materials is one of the most widely studied applications of supercritical fluids. To date, SFE technology is used at industrial levels in economically relevant processes such as decaffeination of both colTee and tea and extraction of hop constituents and spices [19]. 

Ribeiro D S I, Richard J, Thies C, et al. (2003). A supercritical fluid-based coating technology. 3 Preparation and characterization of bovine serum albumin particles coated with lipids. J. Microencap. 20 110-128. 

A number of techniques are based on supercritical fluid technology. Three are of particular pharmaceutical interest, namely the supercritical antisolvent (SAS) system, the rapid expansion of supercritical solution (RESS) method, and the gas antisolvent (GAS) technique [126]. 

Over the past decade, much progress in supercritical fluid technology has occurred. For example, supercritical fluids have found widespread use in extractions (2-5), chromatography (6-9), chemical reaction processes (10,11), and oil recovery (12). Most recently, they have even been used as a solvent for carrying out enzyme-based reactions (14). Unfortunately, although supercritical fluids are used effectively in a myriad of areas, there is still a lack of a detailed understanding of fundamental processes that govern these peculiar solvents. 

The last two decades have seen an increased interest in the use of supercritical fluids in separation science. Supercritical C02 has often been employed as a naturally occurring medium for the separation, purification, and determination of organic substances in environmental samples. However, there are only limited reports on the use of supercritical fluid as solvent in the separation of metal ions from solutions as well as various solid matrices. The supercritical fluid extraction (SFE) technology offers several advantages over conventional solvent-based methods, including the ability to extract radionuclides directly from solids, easy separation of solutes from C02, and minimization of waste generation. It can easily be removed from the extracted substances by degasification under atmospheric pressure and temperature. 

SCF technology has spread quickly from molecules such as naphthalene to more complex substances such as polymers, biomolecules, and surfactants. Supercritical fluids can be used to reduce the lower critical solution temperature of polymer solutions in order to remove polymers from liquid solvents(6.26 The technology has been extended to induce crystallization of other substances besides polymers from liquids, and has been named gas recrystallization(4). In other important applications, SCF carbon dioxide has been used to accomplish challenging fractionations of poly(ethylene glycols) selectively based on molecular weight as discussed in this symposium, and of other polymers(. ... 

The rapid expansion of supercritical solution (RESS) process consists of dissolving the product in a supercritical fluid (usually carbon dioxide) and then rapidly depressurizing the solution through a spray nozzle thus causing extremely rapid nucleation of the product into a highly dispersed material. Various technologies based on supercritical fluids are given in Table 5.5. 

The most important limitation of RESS is the low solubility of compounds in supercritical fluids and the use of co-solvent to improve solubility is usually costly and not economically feasible. As an alternative a supercritical fluid anti-solvent (SAS) process was introduced where a supercritical fluid is used to cause substrate precipitation or recrystallization from a polar liquid solvent (Subramaniam et ah, 1999). Zhong et ah (2008) successfully used SAS to produce alcohol soluble zein micro- and nanoparticles. A number of other technologies based on manipulating supercritical fluids have been successfully used to produce nanoparticles (Della Porta and Reverchon, 2008 Matsuyama et ah, 2003 Meziani and Sun, 2003 Shariah and Peters, 2003 Subramaniam et ah, 1999). 

A fluid is supercritical when it is compressed beyond its critical pressure (Pc) and heated beyond its critical temperature (r, ). Supercritical fluid technology has emerged as an important technique for supercritical fluid extraction (SFE). In many of the industrial applications, it has replaced conventional solvent-based or steam extraction processes, mainly due to the quality and the purity of the final product and environmental benefits. 

Generating surface-modified, submicrometersized particles of water-insoluble drugs with supercritical fluid technology processes IDD technology. Acquired Phasex s proprietary SCF- based processes. 

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