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  • Estimation of solid solubilities in supercritical carbon dioxide: exponential composition dependent mixing rule
    Škerget, Mojca ...
    The composition dependence of the binary parameters of the Peng-Robinson equation of state in near critical region was examined. Published solubility data of some nonpolar and polar solids in ... supercritical CO2 have been fitted to the Peng-Robinson equation of state in combination with one and two parameters van der Waals mixing rules. A systematic study has been performed to determine the influence of different terms in the mixing rules. In order to obtain composition dependence, binary parameters were calculated for each isotherm at particular experimental point separately in such manner to equalise experimental and calculated solubility data. The system was formulated as an equation-oriented model and solved by means of a nonlinear programming (NLP) optimisation algorithm. In general, for systems investigated, high increase of kij was observed below and in vicinity of the crossover point, i.e. in vicinity of the intersection of solubility isotherms in y-P diagram. Above this point kij remained approximately constant with further increase in solubility. Based on systematic study of variation of the Peng-Robinson binary parameters with the system conditions, the first order exponent function has been proposed and adopted for describing the composition dependency of the binary parameter kij. The literature solubility data of selected compounds in supercritical CO2 have been fitted to this empirical model with four adjustable parameters combined with classical thermodynamic model of Peng-Robinson. The results were compared to those obtained with one and two parameters van der Waals mixing rules and with the three parameter density dependent mixing ride of Mohammed and Holder. The agreement of the model with experimental solubility data has been improved which indicates good performance of proposed exponential mixing rule.
    Vir: Congress manuscripts [Elektronski vir] (11 str.)
    Vrsta gradiva - prispevek na konferenci
    Leto - 2005
    Jezik - angleški
    COBISS.SI-ID - 9728790

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