Redlich-Kwong Equation of State Used For Prediction phase Data.

: The solubility of CO 2 in the non-volatile compounds of n -Hexadecane, Diphenylmetnane, Diphenyl ethane, Ethyl benzene and of Nitrogen in n - Hexadecane, at temperature range 298.15-358.15 K are measured at partial pressure of one atmosphere, Falling-film flow technique was used in the present experimental work. It is seen that in most cases the solubility is decreased at the temperature increased, though in the case of the Nitrogen/n-Hexadecane system the reverse is true. The effect is probably related to the decrease in solvent density which occurs as the temperature raises. For systems of low Solubility ,this effect tends to counter balance the increase tendency for solute molecules to "escape" from the solvent, arising from their increase kinetic energy . In addition ,the binary interaction constant ( L AB ) was calculated by fitting the mole fraction solubility of solute gases CO 2 and N 2 by using Redlich-Kwong equation of state for predicting phase data. The interaction constant L AB was calculated from the following expression:

The Redlich-Kwong equation of state gives reasnable description of the volumetric properties not only of pure components but also of mixtures, particularly hydrocarbons mixtures.The following rules are frequently used to obtain the parameters a and b for binary systems: where : is the fugacity of component (A) in the given phase.
A X : is the mole fraction of component (A) in the given phase at temperature T(ºK) and pressure P atm., V is the molar volume.

Experimental
Solubilities were predicted as functions of temperature using The Redlich-Kwong equation with a constant value for the interaction parameter L AB .The value of A and B for the components were calculated from equations ( 3) and ( 4), and were taken to be independent of temperature.The values used are given in table (1).
The values of (A) and (B) for the mixtures were calculated from equation (4).
The value for L AB was chosen to give an exact fit to the solubility at the temperature shown with on asterisk in table (2).This temperature at 298.15 k except for solvents which were solid at this temperature .
The mole fraction solubility of CO 2 in ethyl benzene was measured by King et al (1983), at normal pressure and over temperature range 296.15-333.15K.
The interaction constant L AB Was determined by fitting the mole fraction of solubility of CO 2 in the solvents and of N 2 In n-Hexadecane by using Redlich-Kwong equation of state.The relationship of interaction constant is used in the calculations of phase behavior.The results obtained were compared with experimental data .itgives good representation of phase equilibrium.These data are summarized in table (2).It is seen the solubility of CO 2 decrease as temperature increase in most cases, thought in case of N 2 /n-Hexadecane the reverse is true.The effect is probably related to the decrease in solvent density which occurs as the temperature rises.In case the system N 2 /n-Hexadecane of law solubility this effect due to counter balance the increase tendency for solute molecules to "escape" from the solvent arising from their increase Kinetic energy.
The values of L AB are evaluated by fitting equation ( 5) against the mole fraction solubility of CO 2 in each solvents and of N 2 in n-Hexadecane also, as presented in table (2).The (*) L AB fitted at temperature shown with asterisk, using a suitable computer program at each temperature.

Table(1)
The value of A and B for the components were calculated from equations ( 3) and (4), and were taken to be independent of temperature.

Solvents, Gases
A (atm)(dm 3 /mol) The parameters a and b were originally taken to be independent of temperature and pressure, being given for pure components by the following expressions: constant of the two component A and B.
Eng. & Tech., Vol. 26, No. 7 , 2008 Redlich-Kwong Equation of State Used For Prediction phase Data.Directorate of Chemistry & Petrochemical Industry, Ministry of Science & Tech.747 Results & Discussion: The Solubility of CO 2 in the nonvolatile Solvents of n-Hexadecane, Diphenyl methane, Diphenyl ethane, Ethyl benzene and of N 2 in n-Hexadecane, at temperature range 298.15-358.15ºK at a partial pressure of one atmosphere were experimentally measured by fallingfilm flow technique Kassim, D. M. (1981) .