Nuclear Magnetic Resonance Methods for Characterization of Mass Transport in Porous Materials

Abstract

Spatially resolved Nuclear Magnetic Resonance (NMR) techniques can measure the mass transport processes in opaque porous materials, and thus may play an important role in better understanding the mechanisms underlying the corresponding dynamic processes. This might help improving the designs of heterogeneous systems. However, these applications are challenging due to the non-negligible magnetic field inhomogeneities in porous structures, the significant signal decay by transversal relaxation of magnetization, the demand for high spatial resolution and adequate temporal resolution, as well as additional drawbacks in specific applications like low NMR sensitivity in gas measurements. In this work, spatially resolved NMR methods were improved and optimized to mitigate these limitations for studies on drying, slow liquid flow, and gas flow in porous materials. The proposed methods, by which NMR images with a desired image contrast like spin density or velocity can be obtained, will support quantitative research on mass transport in porous materials and are also of interest for further applications.