SCFs and Water

Physico-chemical Properties oTthe scCOj/HjO System 

The basic physico-chemical properties of the binary mixture carbon dioxide/water are well investigated owing to its great importance in several scientific and technological fields (see Section 6.1). For example, carbon dioxide and water are often found together in natural gas streams and also in oil reservoirs as part of enhanced oil recovery. In addition, the system plays an important role with regard 

The carbon dioxide/water biphasic system is an example of binary mixtures consisting of components with widely separated critical temperatures. The critical properties of the pure compounds are given in Table 1. The typical phase diagram for such mixtures can be complex, including the possibility for areas of three-phase coexistence (LEV). For applications in biphasic catalysis, however, the key parameters to be discussed are solubility and cross-contamination, mass transfer, and chemical changes. 

Microemulsions are thermodynamically stable dispersions of one fluid phase in a second continuous phase, stabilized by an interfacial film of surfactant (see 

Neutron scattering has been used to measure the droplet size in these water/C02 microemulsions and the droplet diameter was found to increase from 20 to 36 A for ivq values of 14 and 35, respectively [15], Droplet size and Wq depend only weakly on pressure, unless the pressure is reduced to that pressure where the phase boundary droplets aggregate. 

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