Supercritical carbon dioxide SCCO

Modification of polymers with supercritical carbon dioxide (scCO ) Absorption of scCO into polyvinylchloride (PVC) sheets at elevated temperatures. 

Supercritical fluids have been used as solvents for a wide variety of applications such as essential oil extraction [6], metal extraction [7], polymer synthesis [8] and particle nucleation [9]. Most applications of supercritical fluids are in combination with carbon dioxide. Among SCFs, supercritical carbon dioxide (scCO ) is especially advantageous because of its near ambient critical temperature (304.1 K) and its moderate critical pressure. Water, which is also a desirable solvent, has a higher critical... 

Other lipases have also been tested in supercritical carbon dioxide for ester synthesis. In this context, the synthesis of terpinyl acetate from a-terpineol and acetic anhydride in supercritical carbon dioxide (scCO ) was carried out using five different lipases as catalysts (Candida rugosa type Vll, Amano PS, Amano AP-6,... 

As evident from Fig. 8.4, an increase in the selectivity has been observed in IL/ scCOj biphasic systems media (>99.5%) with respect to scCO assayed alone (95%). These results could be explained by the use of water-immiscible ILs which have a specific ability to reduce water activity in the enzyme microenvironment. The synthetic activity of the immobilized lipase in IL/scCO biphasic systems is lower than that in scCO assayed alone. Similar results were found by Mori et al. [40] in IL/ hexane biphasic systems. These authors reported that the enzymatic membranes prepared by simple adsorption of CaLB onto the surface were more reactive than membranes prepared with ILs. As can be observed in Fig. 8.4, the initial reaction rate in the assayed IL/scCO biphasic systems increased in the following sequence [bdimim ][PF ]<[bmim ][PFg ]<[bmim ][NTfj ]<[omim ] [PF ], which was practically in agreement with flie activity sequence reported by these authors using free Candida antarctica lipase B in homogeneous ionic liquid systems ([bmim ] [PF ]<[bdmim+][PFg ]<[bmim+][NTfj ]<[omim ][PF ]), with the exception of [bmim [PF ] and [bdimim+][PFg ]. These results were explained taking into account that biotransformation occurs within the ionic liquid phase, so substrates have to be transported from scCOj to the ionic liquid phase. The mechanism of substrate transport between the ionic liquid and the supercritical carbon dioxide could be by three consecutive steps diffusion of the substrates through the diffusion... 

Supercritical fluids, especially supercritical carbon dioxide (scCO =... 

Reaction in Supercritical Fluids on the Example of Carbon Dioxide (scCO )... 

A Duteh eompany has imveiled what it believes to be the first commercial dyeing maehine to replaee water with supercritical carbon dioxide - a pressurized form of the gas with unusual liquid-like properties. Heated up to 31°Celsius (88 degrees Fahrenheit) and pressurized to 74 bar, CO takes on the characteristics of both a liquid and a gas, allowing for the dissolution of eompounds such as dyes. For DyeCoo Textile System s purposes, scCO is heated to 120°Celsius (248 degrees Fahrenheit) and pressurized to 250 bar. Behaving as both a solvent and a solute, the superehaiged earbon dioxide penetrates textile fibres and disperses the preloaded dyes without extra ehemical agents. 

Muljana H, Picchioni F, Heeres HJ, Janssen LPBM. 2009. Supercritical carbon dioxide (scCO ) induced gelatinization of potato starch. Carbohydr Polym 78 511-519. 

Supercritical carbon dioxide has significant safety advantage over organic solvents as it is noninflammable. Since it is a nonreactive solvent in most cases, side reactions and by-product formation are rare in ScCO mediated reactions. However, there are also instances where SCCO2 is used as a reactant. As the solubility of reactants and products in SCCO2 is a strong function of temperature and pressme, it is possible to effect in-situ product separation by suitable temperature and pressure manipulations. 

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