Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy

Cédric Giraudet, Konstantinos D. Papavasileiou, Michael H. Rausch, Jiaqi Chen, Ahmad Kalantar, Gerard P. Van Der Laan, Ioannis Economou, Andreas P. Fröba

Research output: Contribution to journalArticle

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Abstract

In this study, we demonstrate the ability of polarization-difference Raman spectroscopy (PDRS) to detect dissolved free water molecules in a n-octacosane (n-C28H58) liquid-rich phase, and thus to determine its solubility, at temperatures and pressures relevant to the Fischer-Tropsch synthesis. Our results for the pure alkane reveal thermal decomposition above a temperature of 500 K as well as an increase of gauche conformers of the alkane chains with an increase in temperature. For binary homogeneous mixtures, raw spectra obtained from two different polarization scattering geometries did not show a relevant signal in the OH stretching frequency range. In contrast, isotropic spectra obtained from the PDRS technique reveal a narrow and tiny peak associated with the dangling OH bonds. Over the complete range of temperatures and pressures, no signature of hydrogen-bonded water molecules was observed in the isotropic Raman scattering intensities. A thorough investigation covering a large range of temperatures and pressures using PDRS signals showed that the higher the fraction of gauche conformers of hydrocarbon, the higher the solubility of water. The proportion of gauche and trans conformers was found to be water-concentration-independent, and the intensity of the OH-dangling peak increased linearly with increasing the vapor partial pressure of water. Therefore, we established a relation between a relevant intensity ratio and the concentration of water obtained from SAFT calculations. Contrary to the results from relevant literature, the calibration factor was found to be temperature-independent between 424 and 572 K. The isotropic Raman scattering intensities are corrected in order to provide a better representation of the vibrational density of states. The influence of correction of the isotropic scattering intensities on the solubility measurements as well as on the analysis of the molecular arrangement is discussed.

Original languageEnglish
Pages (from-to)10665-10673
Number of pages9
JournalJournal of Physical Chemistry B
Volume121
Issue number47
DOIs
Publication statusPublished - 30 Nov 2017

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Raman Spectrum Analysis
Solubility
Raman spectroscopy
solubility
Temperature
Water
Polarization
water
Alkanes
polarization
Pressure
Paraffins
alkanes
temperature
Raman scattering
Scattering
Raman spectra
Vapor Pressure
Fischer-Tropsch synthesis
Molecules

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Giraudet, C., Papavasileiou, K. D., Rausch, M. H., Chen, J., Kalantar, A., Van Der Laan, G. P., ... Fröba, A. P. (2017). Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy. Journal of Physical Chemistry B, 121(47), 10665-10673. https://doi.org/10.1021/acs.jpcb.7b07580

Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy. / Giraudet, Cédric; Papavasileiou, Konstantinos D.; Rausch, Michael H.; Chen, Jiaqi; Kalantar, Ahmad; Van Der Laan, Gerard P.; Economou, Ioannis; Fröba, Andreas P.

In: Journal of Physical Chemistry B, Vol. 121, No. 47, 30.11.2017, p. 10665-10673.

Research output: Contribution to journalArticle

Giraudet, C, Papavasileiou, KD, Rausch, MH, Chen, J, Kalantar, A, Van Der Laan, GP, Economou, I & Fröba, AP 2017, 'Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy', Journal of Physical Chemistry B, vol. 121, no. 47, pp. 10665-10673. https://doi.org/10.1021/acs.jpcb.7b07580
Giraudet C, Papavasileiou KD, Rausch MH, Chen J, Kalantar A, Van Der Laan GP et al. Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy. Journal of Physical Chemistry B. 2017 Nov 30;121(47):10665-10673. https://doi.org/10.1021/acs.jpcb.7b07580
Giraudet, Cédric ; Papavasileiou, Konstantinos D. ; Rausch, Michael H. ; Chen, Jiaqi ; Kalantar, Ahmad ; Van Der Laan, Gerard P. ; Economou, Ioannis ; Fröba, Andreas P. / Characterization of Water Solubility in n-Octacosane Using Raman Spectroscopy. In: Journal of Physical Chemistry B. 2017 ; Vol. 121, No. 47. pp. 10665-10673.
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