Abstract
Smectite-Type clays play a critical role in the trapping of fluids within soil and atmospheric nanoparticles. The hydrodynamics of cation-saturated smectite nanopores are well documented. However, little is known about the influence of small organic compounds. Here we investigate the effects of carbohydrates (glucose and cellobiose), representing an important class of organic compounds, on the hydration and nanopore structures of montmorillonite, a prototypical smectite. To achieve the same amount of adsorbed water, higher relative humidity was required in the presence of the adsorbed carbohydrates than with the clay alone. The decrease in the characteristic micropore water adsorption with the clay-carbohydrate aggregates implied that water adsorption was constrained within the clay nanopore regions. The presence of carbohydrates promoted water retention as a function of gradual decrease in moisture content. Moisture-dependent X-ray diffraction patterns determined that, relative to the mineral alone, greater nanopore sizes were preserved in the presence of the carbohydrates, despite severe dehydration that is expected to induce clay nanopore collapse. Fourier-Transform infrared spectroscopy captured disruption in the population of exchangeable waters within the carbohydrate-populated clay nanopores, with some agreement with the measured water-desorption profiling. These new findings demonstrate that carbohydrates can restructure smectite interlayer nanopores and water trapping dynamics.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 28816-28827 |
| Number of pages | 12 |
| Journal | Journal of Physical Chemistry C |
| Volume | 123 |
| Issue number | 47 |
| DOIs | |
| State | Published - Nov 27 2019 |
Funding
Graduate support for S.E.K. at Cornell University was provided by the NSF Graduate Research and Training (IGERT) program in Cross-Scale Biogeochemistry and Climate and a NSF grant awarded to L.A. (CHE #1646815). Travel support for S.E.K. to work at the Université Grenoble Alpes was provided by the Chateaubriand Fellowship from the Embassy of France in the United States, the Cornell Graduate School Research Travel Grant, and the Einaudi Center International Research Travel Award from the Mario Einaudi Center for International Studies at Cornell University. We are grateful to Dr. Alex Fernandez-Martinez and Valérie Magnin at the Institut des Sciences de la Terre (ISTerre) at the Université Grenoble Alpes for, respectively, assistance with the FTIR measurements and conducting the water adsorption isotherms. We thank Kim Sparks of the Cornell University Stable Isotope Laboratory and Tatyana Dokuchayeva at the Cornell Nutrient Analysis Laboratory and Dr. Eleanor Bakker for providing the molecular dynamics snapshot of MONT–glucose system used as the graphical abstract. S.E.K. acknowledges helpful discussions with members of her doctoral thesis committee, Dr. Murray McBride (Cornell University) and Dr. Taryn Bauerle (Cornell University).
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films