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Advanced concrete technology for submerged floating tunnels
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
H.Y. Kim, H.N. Yoon, H.M. Son, J.S. Kim, D.W. Jin, H.J. Kim, S. Park, H.K. Lee
The present research team is currently undertaking studies for identifying a durable cementitious binder that consists of Portland cement, blast furnace slag, and calcium sulfoaluminate cement, and possesses a high chloride uptake capacity (Yoon et al., 2019). Preliminary studies have been conducted by calculating the phase assemblage using the Gibbs free energy minimization software GEM-Selektor v.3.5 (http://gems.web.psi.ch/) (Kulik et al., 2013; Wagner et al., 2012), coupled with CEMDATA18 which contains thermodynamic data of aqueous species, solids, and solid-solutions of hydrated cements (Barbara et al., 2019). The extended Debye-Hückel equation was used to calculate the activity coefficients (Helgeson et al., 1981). A common ion-size parameter, and the parameter for common short-range interactions of charged species were 3.67 Å, and 0.123 kg/mol, respectively, to model KOH-dominated electrolyte pore solution.
Basic Chemical Thermodynamics and Kinetics
Published in Kalliat T. Valsaraj, Elizabeth M. Melvin, Principles of Environmental Thermodynamics and Kinetics, 2018
Kalliat T. Valsaraj, Elizabeth M. Melvin
Mixtures of real fluids (gases or liquids) do not form ideal solutions, although similar fluids approach ideal behavior. All nonelectrolytes at their “infinite dilution limit” (lim)xi→0 in solution follow “ideal” behavior. As mentioned in the previous sections, the activity coefficient γi represents the nonideal behavior in aqueous systems. The activity coefficient can be obtained experimentally, and where it cannot be determined directly, chemical engineers have devised theoretical models to compute the activity coefficients from correlations with other solute parameters (e.g., surface area, volume, octanol-water partition constants) or group-interaction parameters (e.g., UNIFAC, NRTL).
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.
On nonlinear Onsager symmetry and mass-action kinetics
Published in Combustion Science and Technology, 2022
where is total molar density and is mole fraction. Hence, the generalized force defined in Eq (6) is given by where the equilibrium mole fractions are function of . To avoid implicit restrictions on or as independent variables, we may assume the existence of a fictitious or real inert diluent (such as nitrogen in certain combustion reactions and interstitial fluid or plasma for biochemical reactions). We further note that non-ideal solutions could be treated by means of activity coefficients.
Incubation media modify silver nanoparticle toxicity for whitefish (Coregonus lavaretus) and roach (Rutilus rutilus) embryos
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Roland Vogt, Benedikt Steinhoff, Darya Mozhayeva, Eva Vogt, George Metreveli, Holger Schönherr, Carsten Engelhard, Josef Wanzenböck, Dunja Katharina Lamatsch
In order to estimate the distribution of thermodynamically expected Ag(I) species in media applied in this study, the speciation calculation was done for Ag using Visual MINTEQ software version 3.0 (Gustafsson 2017). The calculations were performed for Ag(I) concentration range of 0.5–1000 µg/L considering the CO2 equilibrium between air and aqueous phase. The presence of NM-300 K DIS in solutions was not considered. The calculations were conducted for input solutions containing only dissolved species without AgNPs (Table A 5). The activity coefficients were calculated by extended Debye-Hückel equation (Gustafsson 2017). The number of iterations for model calculations was set to 5000. The kinetics of Ag(I) species formation was not considered by model calculations. Interactions of silver species with organic metabolites, nitrogenous compounds, or potentially remaining NOM in the water of Lake Mondsee water after filtration were not incorporated into the model, as no measurements were done to determine their presence.
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].