The solubility of CO2 in a 30 mass % monoethanolamine (MEA) solution has been measured at eight temperatures between 0 and 150°C at partial pressures of CO2 ranging from 0.001 to 20,000 kPa. The data have been correlated using the Deshmukh‐Mather (1981) model.
The optical absorption spectra of solvated electrons in H20 and D20 have been measured at 274, 298, 340, and 380 K. All the spectra were fitted very well with the Gaussian and Lorentzian shape functions at the lowand high-energy sides of the absorption maximum, respectively, excluding the high-energy tail. The spectrum does not shift uniformly with temperature. The temperature coefficient of absorption decreases rapidly with increasing energy on the low-energy side of the absorption maximum, while it changes only slightly on the high-energy side. When the temperature increases the Lorentzian width remains constant, the Gaussian width varies proportionally to T1/2, and the spectrum becomes more symmetrical. On going from H20 to D20 we found that the spectrum at a given A/Amax shows a shift of +0.05 eV in the low-energy wing. The shift decreases with increasing energy, reaching 0.03 eV at the absorption maximum. On the high-energy side of the band the shift becomes negative at hv > 2.2 eV. The shift on the low-energy side seems to be related to the difference of the zero-point energies of the interand intramolecular vibrations. The wavelength dependence of the temperature and isotope effects is consistent with the model that different types of excitation occur on the lowand high-energy sides of the absorption band. The temperature and isotopic dependence of the low-energy side are consistent with its width being due to phonon interactions.
The width of the band at half-height, W\¡2, was divided into two portions, Wr and Wb, representing the parts on the red and blue sides of the absorption maximum EAmax. The average energy on the low-energy side of the band, represented by (EAmax -W,), is nearly the same in water (1.36 eV at 1 bar) as in the alcohols (1.34-1.49 eV at 1 bar). By contrast the average energy on the high-energy side of the band, represented by (EAmax + Wb), is ~0.7 eV higher in alcohols (2.8-3.0 eV at 1 bar) than in water (2.2 eV at 1 bar). The results are consistent with the following model. The low-energy side of the band represents the transition between the ground state and the first excited state, both of which are determined mainly by the potential well created by the OH groups. In alcohols the higher excited states are greatly affected by the (more weakly scattering) alkyl groups. The model is qualitatively similar to that of Delahay, but we find that the overlapping Gaussian shaped lines are not all of the same width and that the high-energy tail does not have the form (A/Amax) « £~8/3, but varies from one type of liquid to another. The relative increase in EAmax with pressure is greater in the alcohols than in water; it correlates with the relative increase in liquid density rather than with that in dielectric constant. The smaller change in EAmax in water is balanced by a relatively larger increase in the width parameters. Oscillator strengths estimated from the present more complete spectra have similar values in the alcohols (0.69-0.75) and water (0.76).
The optical absorption spectrum of the solvated electron has been determined by pulse radiolysis in the pure liquid ethers: tetrahydrofuran, methyltetrahydrofuran, diethyl ether, dimethoxyethane, diglyme, triglyme, and tetraglyme. The absorption maxima are at 4720, 4650, 4350, 4880, 5220, 5440, and 5580 cm−1, respectively. The half-widths of the bands have also been measured. The oscillator strength, determined for the first four ethers is approximately unity. The absorption bands have been determined in binary solutions with ethylenediamine and for tetrahydrofuran-water over the entire concentration range. Calculations using a recent form of a cavity-continuum model have been compared with the experimental results. The model shows agreement with the experimental values for the transition energy for an effective cavity radius of about 4 Å and a coordination number of 6 or 8. Kinetics for the attachment of solvated electrons to pyrene and for the reaction of the solvated electron with the solvent counterion have been investigated in several ethers and absolute rate constants determined.
New experimental data are presented for the solubility of hydrogen sulfide in the ionic liquid 1-N -butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF 6 ]) at five temperatures in the range (298-403) K at pressures up to 9.6 MPa. The ionic liquid [bmim] [PF 6 ] is a good solvent for hydrogen sulfide. At 9 MPa the mole fraction H 2 S in the liquid is about 0.7. The solubility is a strong function of temperature; at 2 MPa the solubility (mole fraction H 2 S) decreases from about 0.84 at 298 K to about 0.2 at 403 K. The Krichevsky-Kasarnovsky equation was used to correlate the experimental data, and Henry's constants were obtained. The solution thermodynamic properties at standard temperature and pressure were calculated.
The solubility of hydrogen sulfide and carbon dioxide in an aqueous solution containing 35 wt% methyldiethanolamine (MDEA) (3.04 kmol/m3, 4.52 mol/kg) has been measured at 40° and 100°C at partial pressures of the acid gas up to 530 kPa. Some data for hydrogen sulfide in a 50 wt% solution of MDEA (4.38 kmol/m3, 8.39 mol/kg) were also obtained. Also, densities of CO2‐aqueous MDEA solutions were measured at 40°C.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.