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Thursday, March 21, 2019 at 12:20pm
Smectite-type clay minerals play a critical role in the trapping of fluids within soil nanopores. The hydrodynamics of cation-saturated smectite interlayers are well documented. However, little is known about how the hydration behavior of smectite interlayer nanopores is influenced by small organic compounds. Here we applied a combination of experimental and theoretical techniques to probe the effects of carbohydrates, an important and abundant class of organic compounds in soils, on the hydration properties of montmorillonite, a prototypical smectite mineral. Fourier-transform infrared spectroscopy revealed that adsorbed glucose and cellobiose led to a greater proportion of mineral-bound waters than exchangeable waters within the hydrated mineral aggregates. Accordingly, water adsorption-desorption profiling demonstrated that, compared to montmorillonite alone, there was enhanced water retention in the carbohydrate-populated montmorillonite samples in response to dehydration. We employed quantitative analysis of X-ray diffraction profiles to determine nanopore size distributions in the mineral aggregates subjected to in situ dehydration. Collectively, our results show that carbohydrates promote moisture retention in smectite nanopores by sustaining expanded nanopore size and facilitating water trapping at the mineral interface.
Graduate student, SCS
Research Group: Dr. Ludmilla Aristilde
I'm interested in the study of how plant and microbial secretions and exudates within the rhizosphere bind to soil minerals and how this process influences overall soil properties and health.