Micellization and Interaction of Cationic Surfactants with Different Hydrophobic Group in Polar Organic Solvent
Osundiya Medinat Olubunmi,
Olowu Rasaq Adewale,
Olaseni Segun Esan,
Aboluwoye Christopher Olumuyiwa
Issue:
Volume 9, Issue 4, December 2020
Pages:
86-92
Received:
7 September 2020
Accepted:
24 September 2020
Published:
14 October 2020
Abstract: Surfactants are amphiphilic compounds that are widely used in various technological fields and biological systems. In many of these applications, mixtures of amphiphiles in organic solvents are employed for better performance The work aims at establishing the extent of ideality or otherwise in the mixed micelles of n-alkyl trimethylammonium bromide, (n = 14 and 16 for TTABr and CTABr respectively), in water (AQ) and water-monoethanolamine (AQ-MEA) at different mole fractions (0.1 to 0.6) and temperatures by Conductance measurement.: The values of the critical micelle concentration (Cmx) obtained in AQ, and AQ-MEA were lower than that obtained assuming an ideal mixing system. Substantial deviation from ideality was observed in the presence of AQ-MEA at all temperatures, suggestive of more favourable association of the surfactants in MEA solvent. The composition (χ1) of the mixed micelles obtained in the context of Rubingh’s model showed that the micelles of CTABr were dominant, and the values of the interaction parameters (βmx) were negative in AQ and AQ-MEA media with more synergistic interaction in the latter case at 0.1:0.9 mole fraction ratio at a particular temperature. The values of the activity coefficients (fTTABr, fCTABr) were below unity, and the evaluation of the energetics of micellization showed that the process was spontaneous and feasible.
Abstract: Surfactants are amphiphilic compounds that are widely used in various technological fields and biological systems. In many of these applications, mixtures of amphiphiles in organic solvents are employed for better performance The work aims at establishing the extent of ideality or otherwise in the mixed micelles of n-alkyl trimethylammonium bromide...
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A Theoretical Study of the Solid Solution Phases of LixFePO4
Issue:
Volume 9, Issue 4, December 2020
Pages:
93-100
Received:
2 November 2020
Accepted:
16 November 2020
Published:
24 November 2020
Abstract: For the next generation Li-battery anode materials LiFePO4, the forming of the solid solution phase LixFePO4 and the related charge/discharge mechanism are the high light topics recently. In the paper, ab-initio calculation was applied to study the formation and electronic structure of the solid solution of LixFePO4, and a Charge/Discharge model of LiFePO4 was set up based on the calculation results. Due to the high formation energy, LixFePO4 separates into FePO4 and LiFePO4 in bulk system under room temperature. The single solid solution phase LixFePO4 could exists in the nanoscale particle, and it is due to that the relative larger lattice mismatch energy. The nanoscale particle materials should have a good rating performance due to the forming of LixFePO4 in solid solution phase, of which the partially occupied state and the small energy gap between the VBM and the defect state could improve the intrinsic electronic conductivity. In bulk materials, the medium region, which is composed of LixFePO4, is very narrow between the two phases FePO4 and LiFePO4. There is a electron potential well in the region, of which the bottom is at the side of LixFePO4 (x<0.5). The number of electron in the well highly affects the lithium insertion and extraction. In order to efficiently transfer the electron between the potential well and the out circuit, an electron conductor network or layer should be coated on the LiFePO4 particle.
Abstract: For the next generation Li-battery anode materials LiFePO4, the forming of the solid solution phase LixFePO4 and the related charge/discharge mechanism are the high light topics recently. In the paper, ab-initio calculation was applied to study the formation and electronic structure of the solid solution of LixFePO4, and a Charge/Discharge model of...
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Gaussian M-062x/6-31+g (d,p) Calculation of Standard Enthalpy, Entropy and Heat Capacity of Some Fluorinated Alcohol’s and Its Radicals at Different Temperatures
Hebah Abdel-Wahab,
Joseph Bozzelli
Issue:
Volume 9, Issue 4, December 2020
Pages:
101-111
Received:
20 October 2020
Accepted:
8 December 2020
Published:
28 December 2020
Abstract: Thermochemical properties of fluorinated alcohols are needed for understanding their stability and reactions in the environment and in thermal process. Structures and thermochemical properties of these species were determined by the Gaussian M-062x/6-31+g (d,p) calculation. Contributions of entropy, S°298, and heat capacities, Cp(T) due to vibration, translation, and external rotation of the molecules were calculated based on the vibration frequencies and structures obtained from the M-062x/6-31+g (d,p) density functional method. Potential barriers are calculated using M-062x/6-31+g (d,p) density functional method and are used to calculate rotor contributions to entropy and heat capacity using integration over energy levels of rotational potential. Enthalpies of formation for 19 fluorinated ethanol and some radicals were calculated with a popular ab initio and density functional theory methods: the Gaussian M-062x/6-31+g (d,p) via several series of isodesmic reactions. The recommended ideal gas phase ΔHf298 ° (kcal mol−1) values calculated in this study are the following: -101.74 ± 0.72 for CH2FCH2OH; -113.51 ±1.39 for CH3CHFOH; -50.66 ± 0.75 for C•HFCH2OH; -56.05±0.62 for CH2FCH•OH; -45.00±1.31 for CH2FCH2O•; -59.61±1.20 for CH2•CHFOH; -67.99± 1.29 for CH3CF•OH; -58.76±1.20 for CH3CHFO•; -154.12±1.72 for CH2FCHFOH; -155.26±1.67 for CF2HCH2OH; -174.53±1.54 for CH3CF2OH; -104.07 ± 1.45 for CH2FC•FOH; -105.63±1.74 for C•HFCFHOH; -99.08±1.57 for CH2FCHFO•; -102.34±1.74 for CHF2C•HOH; -102.23±1.57 for C•F2CH2OH; -98.86±1.57 for CHF2CH2O•; -119.41±1.74 for CH2•CF2OH; -110.56±1.62 for CH3CF2O•. Entropies (S298° in cal mol−1 K−1) were estimated using the M-062x/6-31+g (d,p) computed frequencies and geometries. Rotational barriers were determined and hindered internal rotational contributions for S298°- 1500°, and Cp(T) were calculated using the rigid rotor harmonic oscillator approximation, with direct integration over energy levels of the intramolecular rotation potential energy curves.
Abstract: Thermochemical properties of fluorinated alcohols are needed for understanding their stability and reactions in the environment and in thermal process. Structures and thermochemical properties of these species were determined by the Gaussian M-062x/6-31+g (d,p) calculation. Contributions of entropy, S°298, and heat capacities, Cp(T) due to vibratio...
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