NMR relaxometry characterization of water adsorption in corn stover anatomical fractions

Nuclear magnetic resonance (NMR) relaxometry is applied to provide direct measurement of water adsorption in anatomical fractions of corn stover. NMR transverse T-2 relaxation time distribution measurements indicate multiple water populations, which vary with anatomical fraction and water adsorption. Measured T-2 data are used to calculate thermodynamic properties of Brunauer-Emmet-Teller adsorption theory using a model to estimate mono and bilayer relaxation. T-2 data are used directly to determine rotational diffusion correlation times indicating adsorption interaction strength. T-1-T-2 longitudinal-transverse relaxation time correlation measurements quantify differences in the molecular level structural order of the adsorbate surface water as a function of water activity, i.e. relative humidity or water vapor partial pressure. The T-1/T-2 ratio provides a measure of the surface energy related to the adsorption strength and surface diffusive mobility of the water adsorbate and differentiates the anatomical fractions. The results indicate that direct measurement of NMR relaxation times can be used to characterize corn stover biomass water adsorption, data relevant to processing and handling considerations.

Automated summary

Nuclear magnetic resonance (NMR) relaxometry is used to directly measure water adsorption in anatomical fractions of corn stover. Multiple water populations are observed and varied with anatomical fraction and water adsorption. NMR relaxation time measurements are used to calculate thermodynamic properties and determine adsorption interaction strength. The ratio of T-1/T-2 provides information about the surface energy and surface diffusive mobility of the water adsorbate.