Supercritical sorption applications

The sorption applications include regeneration of porous beds, preparative scale supercritical chromatography, simulated moving beds, thermal swing schemes, and adsorp-tion/desorptions cycles. Although initial applications of supercritical fluids in this domain were on regeneration of porous beds, more recent emphasis on fractionation best reflects... 

Various authors have considered the glassy state behaviour, and in particular the sorption of gases and supercritical fluids. The main dificulty is to find a thermodynamic model suitable for the description of the properties of the glassy state. Also, the normal equations of state specially developed for polymeric systems are not directly applicable to the non-equilibrium conditions of this state. 

Both adsorption from a supercritical fluid to an adsorbent and desorption from an adsorbent find applications in supercritical fluid processing.The extrapolation of classical sorption theory to supercritical conditions has merits. The supercritical conditions are believed to necessitate monolayer coverage and density dependent isotherms. Considerable success has been observed by flic authors in working with an equation of state based upon the Tofli isoterm. It is also important to note that the retrograde behavior observed for vapor-hquid phase equilibrium is experimentally observed and predicted for sorptive systems. 

Mutual solubility of polymers and volatile organic substances are of importance for many applications in polymer chemistry and polymer engineering. Polymerizations, which should be performed in homogeneous phase, require the complete miscibility of monomer, polymer, solvent (liquid or supercritical) and other additives. Subsequently, the extraction of the polymer product from the reaction mixture requires a phase split (into two liquid phases or into a vapor and a liquid phase) to obtain a polymer product of high purity on one side and the remaining monomer on the other side. In this context, the devolatilization of polymers is of particular interest. Another example is the use of polymer membranes for the separation of two volatile organic compounds. Here, besides the knowledge of diffusivity, the solubility (sorption) of the different components in the polymer membrane is also an important prerequisite for an efficient process. 

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