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Application of COSMO-SAC in Complex Phase Behavior: Vapor–Liquid–Liquid Equilibria
Published in Anand Bharti, Debashis Kundu, Dharamashi Rabari, Tamal Banerjee, Phase Equilibria in Ionic Liquid Facilitated Liquid–Liquid Extractions, 2017
Anand Bharti, Debashis Kundu, Dharamashi Rabari, Tamal Banerjee
The prediction of phase equilibria involves the calculation of activity coefficients for every compound in both liquid phases. COSMO-SAC calculation was done to predict activity coefficients. The parameters for COSMO-SAC are given in Table 4.3. The representative outcome of COSMO calculation is σ-profile that is a two-dimensional representation of three-dimensional charge distribution among molecules. The representative σ-profile of water + ethanol + hexane is shown in Figure 4.4. From σ-profile, it is evident that hexane is nonpolar, that is, its peak lies between −0.0084 e/Å2 and 0.0084 e/Å2. But ethanol and water have segments lying in nonpolar as well as hydrogen bond donor and acceptor regions.
Subsurface Processes
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
where [A] is read as “the activity of the species A, raised to the power of its mole number (a),” and K is the thermodynamic equilibrium constant or stability constant. The activity of a species is the effective concentration of the species, and is about equal to the actual concentration for dilute or ideal solutions. For more concentrated solution, the ions in solution begin to interfere with each other’s ideal behavior and the activities must be corrected for these interactions.
Liquid–Liquid Extraction and Supported Liquid Membrane Transport of Neptunium(IV) Across a Flat-Sheet Supported Liquid Membrane Containing a TREN-DGA Derivative
Published in Solvent Extraction and Ion Exchange, 2022
Bholanath Mahanty, Prasanta K. Mohapatra, Andrea Leoncini, Jurriaan Huskens, Willem Verboom
where ‘a’ is the activity of the species and a=γ.c, where ‘γ’ is the activity coefficient of the respective species and ‘c’ is the concentration of the species in the solution. The details are given in the supporting information (SI)
Ionic liquid-based dispersive liquid–liquid microextraction of succinic acid from aqueous streams: COSMO-RS screening and experimental verification
Published in Environmental Technology, 2023
Huma Warsi Khan, Anis Aina Zailan, Ambavaram Vijaya Bhaskar Reddy, Masahiro Goto, Muhammad Moniruzzaman
Activity coefficient indicates the effective concentration of a specific solute in the solution, whereas the activity of a substance specifies its chemical potential in the solution. A lower activity coefficient specifies stronger interaction between the molecule under study and extracting solvent (in this case IL). Figure 3 presents the ACid values computed for 108 IL combinations using COSMO-RS to extract SA, indicating the following order for cations: [TMAm] < [Ch] < [BMPyrro] < [TBPh] < [BMPyri] < [BMIm]. This trend indicates that cations that are not characterised by electron delocalisation will be suitable for SA extraction. The results also suggest that quaternary ammonium cation possesses lower activity coefficient relative to aromatic cations [BMPyri] and [BMIm]. This is expected, due to the presence of conjugated bonds that increase their stability, resulting in weak hydrogen bonding ability. According to the results, it is also concluded that electronegative anions will be suitable for SA extraction, while their effectiveness exhibits the following trend; [OH-] > [F-] > [SO42-] > [Ac-]. Electronegativity is a measure of an atom’s attraction for electrons, meaning that the more electronegative atoms pull some electron density from other bonded atoms that are more electropositive. Hence, greater electronegativity will enhance the hydrogen bonding ability of ILs. Higher electronegative anions form rapid hydrogen bonds with OH- ions of SA. In addition, these anions possess better bonding and dissolution ability due to the absence of steric shielding. The higher activity coefficient was obtained for hydrophobic anions such as [BF4-] and [PF6-] owing to their lower dissolution power, which is attributed to their higher stability and presence of non-coordinating bonds [32]. Overall, the results revealed that [TMAm][OH], [Ch][OH], [TMAm][F], [Ch][F], [TMAm][SO4] and [TMAm][F] ILs can be used for SA extraction, which is in accordance with the findings related to lactic acid extraction [31].