Sharif Digital Repository

An analytical expression for the fugacity coefficient of supercritical fluids has been derived from the equation of state. Here, the equation of state known as the linear isotherm regularity, LIR, is used to obtain this expression. We have inverted the LIR equation of state to obtain an appropriate expression for fugacity calculation. The inverted LIR (ILIR) works well at high pressures; but at high temperatures, Tr = T/Tc ≥2, ILIR is valid for the entire pressure range. ILIR is valid over a wide temperature range. Unlike LIR, ILIR is also valid at temperatures above twice the Boyle temperature. Like LIR, the inverted equation is a general equation of state which is valid for all types of... 

New treatment technologies are currently being investigated for the treatment of contaminated drilling waste mud with oil. Supercritical fluid extraction is a promising technology that could be effectively used to extract this contaminated drilling waste mud. In this work, one step extraction efficiency of supercritical carbon dioxide to drilling waste mud of South Pars gas field has been investigated at a range of temperatures (55 to 79.5 °C), and over a pressure range of 160 to 220 bar. Extraction efficiencies were calculated based on cuttings weight loss. Results show that approximately 28.45% of cuttings weight loss in one step extraction at a pressure of 200 bar and temperature of 60 °C... 

Supercritical fluid extraction is a new technology that could be effectively used to treat oil-contaminated drill cuttings generated during drilling for oil and gas. In this work, the solubility of oil-contaminated drill cuttings in supercritical carbon dioxide is obtained by an experimental flow type apparatus. The solubility was measured at 200 bar pressure, over a temperature range of 55-79.5°C. The measured solubility and experimental data for oil in drill cuttings were correlated using the PC-SAFT, PR and SRK EOS models, without any adjustable parameters. Average absolute derivations of less than 15.1 %, 98.7 %, and 99.3 % are achieved between predicted and experimental values for the... 

The Helmholtz free energy of solvation (ΔslvA) of 2-propanol and acetone in supercritical CO2 were calculated by expanded-ensemble method. For both solute molecules, ΔslvA is well represented by the polynomial equation of the third power of density and the density value correspond to the maximum stability decreases with increasing temperature. In all states under study acetone is more stable than 2-propanol. At low densities the solvation of acetone is more exothermic than 2-propanol while at high densities it come with less entropic penalty. The solvent reorganization energy is more favorable in 2-propanol case, although the role of solute-solvent interactions is dominant in both cases. ©... 

The extent of the self-association of water in supercritical CO2 has been investigated in a wide range of density and temperature by the test particle insertion technique. The results show that the association constant for water decreases with temperature and weakly depends on CO2 density. This weak density dependence provides evidence for the lack of a strong specific CO2-water interaction. Comparing calculated association constants with its gas-phase values shows that the association constant is at most ca. 38% lower than its gas-phase value in the high density-low temperature region. Inspection of the simulated radial distribution functions revealed that forming modest water-CO2 complexes... 

In this paper, a new correlation to calculate the thermal conductivity of supercritical carbon dioxide based on 668 data points from the literature is introduced. The proposed correlation is valid in temperature range from 310 to 960 K, and pressures range between 7.4 and 210 MPa. The average absolute error of the model was found to be 2.7 and 2.4% in the comparison with the literature and NIST data respectively, which demonstrates superiority of the model over other methods  

Extraction of the essential oil from a medicinal plant called Dracocephalum kotschyi Boiss was performed by green technology of supercritical carbon dioxide (SC-CO2) extraction. A Taguchi orthogonal array design with an OA16 (45) matrix was used to evaluate the effects of five extraction variables: pressure of 150-310bar, temperature of 40-60°C, average particle size of 250-1000μm, CO2 flow rate of 2-10ml/s and dynamic extraction time of 30-100min. The optimal conditions to obtain the maximum extraction yield were at 240bar, 60°C, 500μm, 10ml/s and 100min. The extraction yield under the above conditions was 2.72% (w/w) which is more than two times the maximum extraction yield that has been... 

The absolute free energy of solvation of benzene and perfluorobenzene was measured in supercritical carbon dioxide using the expanded-ensemble method in the context of Monte Carlo (MC) Simulations. The MC calculations were carried out at 12 state points on the solvent phase diagram: (ρr = 0.5, 1.0, 1.5, 2.0; Tr = 1.01, 1.10, and 1.20). These conditions were chosen to address the accurance of specific molecular interactions between CO2 and fluorine. The greater stability of perfluorobenzene observed over all states investigated in this study attributed to the greater solvent accessible surface area and 25-30% increase in the strength of the interaction of this molecule with CO2 in the... 

The absolute free energy of solvation of methane (CH4) and its fluorinated forms (CH3F, CH2F2, CHF3 and CF4) have been computed via statistical perturbation theory (SPT) in the NPT ensemble at four thermodynamical states (whitin liquid and supercritical regions), in the context of Monte Carlo Simulations. Thermodynamical interpretation of the observed trend in the absolute free energy of solvation in different states reveals an exothermic solvation with ΔSslv < 0 (entropically unfavorable solvation) that the intermolecular interactions play an important role in the solvation process. The fluorinated methanes are confirmed to control the mutual arrangement of neighboring CO2 molecules and the... 

In this work, a new two-parameter cubic equation of state is presented based on perturbation theory for predicting phase behavior of pure compounds and of hydrocarbons and non-hydrocarbons. The parameters of the new cubic equation of state are obtained as functions of reduced temperature and acentric factor. The average deviations of the predicted vapor pressure, liquid density and vapor volume for 40 pure compounds are 1.116, 5.696 and 3.083%, respectively. Also the enthalpy and entropy of vaporization are calculated by using the new equation of state. The average deviations of the predicted enthalpy and entropy of vaporization are 2.393 and 2.358%, respectively. The capability of the... 

An experimental flow-type apparatus has been tested for the separation of phenanthrene from a mixture of solids (phenanthrene, anthracene, and carbazole) and also from anthracene oil of the Isfahan Coal Tar Refining Company based on retrograde crystallization phenomena in supercritical carbon dioxide. The results show that by exploiting the crossover effect it is possible to obtain (82 and 24) mass % of phenanthrene from the solid mixture and anthracene oil, respectively, with a single temperature cycle