Sugars are common by-products of plant and microbial activities in soils. Secreted sugars are implicated in the retention of hydrated soil nanopores near plant roots and microbial cells despite severe dryness in the bulk soil. Smectite clay minerals are known to swell to accommodate the trapping of organic compounds in soil nanopores. Here we combine theoretical simulations and experimental spectroscopies to shed light on the diffusion and retention of water molecules and solutes in glucose-enriched montmorillonite nanopores. Molecular dynamics simulations revealed re-structuring of the interlayer organization of water-water interactions, which were disrupted by glucose-water H-bonding interactions. We also found that glucose-populated nanopores accumulated Na-ions and their hydrated water molecules at the mineral surface. This led to a decrease in the diffusion of both Na and water molecules in the presence of glucose. Glucose mobility is also reduced due to aggregation of glucose into organic clusters H-bonded to both walls of the mineral nanopore. The theoretical findings were corroborated by nuclear magnetic resonance and X-ray diffraction measurements.

Sugar-influenced hydrodynamics in mineral nanopores revealed by molecular dynamics simulations coupled with spectroscopic experiments

255th National Meeting (2018)

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