Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering
Abstract
Water’s behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (α{sub p}) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated α{sub p} peak was found to be quite similarmore »
- Authors:
-
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan (China)
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
- National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China)
- Publication Date:
- OSTI Identifier:
- 22493606
- Resource Type:
- Journal Article
- Journal Name:
- Journal of Chemical Physics
- Additional Journal Information:
- Journal Volume: 143; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BRAGG CURVE; CALORIMETRY; CARBON; DENSITY; NANOMATERIALS; POROUS MATERIALS; SCATTERING LENGTHS; SMALL ANGLE SCATTERING; SURFACES; TEMPERATURE DEPENDENCE; THERMAL EXPANSION; VELOCITY; WATER; X-RAY DIFFRACTION
Citation Formats
Liu, Kao-Hsiang, Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Zhang, Yang, Jeng, U-Ser, and Mou, Chung-Yuan. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering. United States: N. p., 2015.
Web. doi:10.1063/1.4929843.
Liu, Kao-Hsiang, Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Zhang, Yang, Jeng, U-Ser, & Mou, Chung-Yuan. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering. United States. https://doi.org/10.1063/1.4929843
Liu, Kao-Hsiang, Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, Zhang, Yang, Jeng, U-Ser, and Mou, Chung-Yuan. Mon .
"Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering". United States. https://doi.org/10.1063/1.4929843.
@article{osti_22493606,
title = {Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering},
author = {Liu, Kao-Hsiang and Joint Institute for Neutron Science, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 and Zhang, Yang and Jeng, U-Ser and Mou, Chung-Yuan},
abstractNote = {Water’s behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (α{sub p}) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated α{sub p} peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.},
doi = {10.1063/1.4929843},
url = {https://www.osti.gov/biblio/22493606},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 9,
volume = 143,
place = {United States},
year = {2015},
month = {9}
}