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Rapid surface-to-volume ratio and tortuosity measurement using Difftrain
Colin J Davies1, Jonathan D Griffith, Andrew J Sederman
1Magnetic Resonance Research Centre, Department of Chemical Engineering, University of Cambridge, Pembroke Street, Cambridge, UK.
Summary
Rapid NMR diffusion measurements using the Difftrain sequence significantly reduce experiment times from hours to minutes. This technique accurately characterizes porous media, determining surface-to-volume ratios and tortuosities efficiently.
Area of Science:
- Magnetic Resonance Imaging
- Materials Science
- Physical Chemistry
Background:
- Nuclear Magnetic Resonance (NMR) diffusion measurements are crucial for characterizing porous media.
- Calculating surface-to-volume ratios (S/V) and tortuosities (kappa) requires analyzing diffusion over various observation times (Delta).
- Conventional pulsed field gradient (PFG) methods are time-consuming, often taking hours.
Purpose of the Study:
- To introduce and validate the rapid diffusion measurement pulse sequence, Difftrain, for accelerated porous media characterization.
- To demonstrate significant reductions in total experiment time compared to conventional PFG methods.
- To present novel modifications of the Difftrain sequence tailored for S/V and kappa measurements.
Main Methods:
- Utilized the Difftrain pulse sequence for rapid diffusion measurements.
- Implemented modified Difftrain sequence with variable echo delay and tip angle.
- Applied the sequence to a model glass bead pack for S/V and kappa determination.
Main Results:
- Achieved experimental data acquisition in minutes, reducing total experiment time by over an order of magnitude.
- Demonstrated excellent agreement between Difftrain-derived S/V and kappa values and those from conventional PFG measurements.
- Validated S/V results against bulk gravimetric measurements.
Conclusions:
- The Difftrain pulse sequence offers a significantly faster alternative for NMR-based characterization of porous media.
- Optimized Difftrain modifications enhance its applicability for precise S/V and kappa measurements.
- This rapid method maintains accuracy while drastically improving experimental efficiency.
