Peng-Robinson cubic equation of state based on key group contribution and calculation of nitrogen gas solubility in MMA dimer

Previously authors have reported facts that nitrogen (N2) and oxygen solubilities in styrene is the same as those in benzene and divinylbenzene at 303 K. Though the three compounds have an atomic composition, (CH)n (n=6, 8 and 10), the gas solubilities are thought to depend on the number of aromatic carbons in the solution. Then, authors named it ‘a key group in solubility'. In this research, the key group was investigated for N2 solubility in methyl methacrylate (MMA) and its dimer, ethylene glycol dimethacrylate (EGDMA). Therefore, the calculations were carried out by Peng-Robinson (PR) equation of state based on group contribution methods. The experimental data employed were those of Lai et al., where N2 solubility are reported in MMA at 303 K. The N2 solubility in EGDMA was assumed to be double of that in MMA at 303 K, because EGDMA has two MMA units in the molecule. Two types of group contribution methods were proposed to calculate N2 solubility in EGDMA. One was for the critical temperature and pressure proposed by Joback and Reid. Using these properties, the attractive and excluded volume parameters in PR equation were evaluated for EGDMA. Other was similar to a method proposed by Orbey and Sandler. The excluded volume parameter in PR equation can be evaluated from those of MMA by multiplying the number of repeating units, and the attractive by multiplying the squared number

Boiling point of five new sulfur-free odorants for LPG, 1-pentyne, cyclopentene, 1-hexyne, 2-hexyne and 1,5-cyclooctadiene, and bubble point pressures of binaries with Propane5

Boiling point and bubble point pressure in binaries with propane were measured for five compounds: 1-pentyne, cyclopentene, 1-hexyne, 2-hexyne, and 1,5-cyclooctadiene, new sulfur-free odorants for LPG. The boiling point was measured with an ebulliometer under atmospheric pressure. The experimental boiling points were 313.51 K, 313.76 K, 344.53 K, 357.59 K, and 424.02 K for 1-pentyne, cyclopentene, 1-hexyne, 2-hexyne, and 1,5-cyclopentadiene, respectively. The experimental boiling points were used for estimation of critical temperature, critical pressure, and acentric factor by Lydersen’s group contribution method to evaluate the two constants in the Peng-Robinson equation-of-state. The Peng-Robinson equation could correlate the bubble point pressure to the mole fraction of propane with absolute relative deviation of less than 2.556%. The data will be useful in the development of fuel cells with reformers for LPG

CO2 absorption effect on electric conductivities for butylethanolamine and methyldiethanolamine aqueous solutions at 313 K

The CO2 absorption, density, viscosity, pH, and electric conductivity were measured for aqueous solutions of butylethanolamine (BEA) and methyldiethanolamine (MDEA) at 313.2 K under atmospheric pressure. The CO2 loading [mol-CO2/mol-amine] of aqueous BEA and MDEA solutions studied decreased with increasing BEA and MDEA concentration. The CO2 loading of an aqueous BEA solution was larger than that of an aqueous MDEA solution in the range of 10 - 40 wt% amine concentration. The electric conductivity of the aqueous BEA solution is larger than that of aqueous MDEA solutions, and the amine concentration dependence of the electric conductivities for both solutions studied showed maxima at 10 wt%. The electric conductivities of BEA and MDEA solutions after CO2 absorption increased with increasing CO2 loading. The CO2 loading dependence of the electric conductivity was correlated with a linear function. It may be suggested that the correlation coefficients predict the CO2 loading and amine concentration in solution at 313.2 K

So2 solubility in low molecular weight polyethylene glycoldimethyl ether and correlation using cubic equation of state

The solubility of sulfur dioxide (SO2) was measured in polyethelene glycol dimethyl ether (PEGDME) by use of a static type apparatus in the pressure range from 15.2 to 231.2 kPa at 308.18 K. The stated average molecular weight of PEGDME was Mw = 240 g·mol−1 and the molecular structure of the repeating unit is similar to that of dimethyl ether (DME). The bubble point pressure showed a negative deviation from Raoult law. The behavior was expected from consideration of the vapor–liquid equilibrium data of DME + SO2, reported by Noles and Zollweg (Fluid Phase Equilib 66:275–289, 1991). The ‘bridge-like structure’ will be microscopically formed between the DME unit and SO2, because the two unshared electron pairs of the oxygen atom in DME unit act as an electron donner for some molecules. The Peng–Robinson equation of state was used to correlate the experimental data. Two types of mixing rules were employed. One was a conventional model, and the other was of the excess Gibbs energy type. The latter, Wong–Sandler model combined with Flory–Huggins equation, showed a good reproducibility for the experimental data