NMR-STUDIES OF MOLECULAR MOBILITY AND DIFFUSION IN POROUS SYSTEMS

The uptake, partitioning, and release of ingredients such as water, oi l, surfactant, and ions are important factors to understand and contro l in the design acid manufacture of detergent and personal products. A lthough conventional pulse NMR (PNMR) spectroscopy continues to be use d to analyse bulk molecular mobility and phase composition, more recen tly MR imaging techniques have created unique opportunities for gainin g spatial information about these processes in ways that are noninvasi ve and potentially quantitative, This paper describes the evaluation o f MRI and associated PNMR techniques to study transport in three relev ant cases: ion diffusion (e.g., fluoride) in concentrated dispersions, oil transport through powders, and water ingress into porous powders (zeolite). Results are presented to illustrate the potential of multip le pulse and gradient echo MRI methods for dealing with the short T-2 scenarios that represent a common problem in quantitative imaging of w ater in solid-containing composites involving, for instance, zeolite, or silica. Pore-size characterisation results are also presented.