Estimation of solid solubilities in supercritical carbon dioxide: Peng-Robinson adjustable binary parameters in the near critical region
The density dependence of the binary parameters of the Peng-Robinson equation of state in near the critical region was examined. Published solubility data of eight compounds in pure CO2 have been fitted to the Peng-Robinson equation in combination with one and two parameters van der Waals mixing rules and in combination with the three parameter density dependent mixing rule of Mohamed and Holder. A systematic study has been done to determine the influence of different terms in the mixing rules. In order to obtain density dependence, binary parameters were calculated for each isotherm at particular experimental point separately in the way to equalise experimental and calculated solubility data. The system was formulated as an equation-oriented model and solved by means of a nonlinear programming optimisation algorithm. For all compounds the binary interaction parameters thus obtained were found to vary strongly with pressure in the range from 75 bar to approximately 150 bar, i.e. near the critical end point (CEP) of the low temperature branch of the three phase solid-liquid-gas (SLG) curve. At higher pressures, the parameter is practically independent on pressure. In general, for the systems investigated, kij increases linearly with increasing density and reaches a constant value at higher densities in the range from 700 to 800 kg/m3, depending on the system under investigation.
2002
2012-06-01 13:06:22
1033
solid liquid equilibria, equation of state, mixing rules, binary parameters, near critical region, nonlinear programming, thermodynamic model, supercritical fluids, CO2, solubility
ravnotežje trdno tekoče, enačba stanja, mešanje, binarni parametri, kritično območje, nelinearno programiranje, termodinamični model, superkritični fluidi, CO2, topnost
Mojca
Škerget
70
Zorka
Novak-Pintarič
70
Željko
Knez
70
Zdravko
Kravanja
70
UDK
4
66-987:541.8
COBISS_ID
3
7503894
ISSN pri članku
9
0378-3812
NUK URN
18
URN:SI:UM:DK:9X8QZVMR
0
Predstavitvena datoteka
2012-06-01 13:06:30