Empirical time dependence of liquid self-diffusion coefficient in porous media

• Published in: Journal of magnetic resonance (1997) 2012-03, Vol.216, p.192-196
• Main Author: Loskutov, V.V.
• Format: Article
• Language: English
• Subjects: Algorithms; Beads; Diffusion; Electrophoresis, Gel, Pulsed-Field; Fourier Analysis; Glass; Magnetic Resonance Spectroscopy; Microspheres; NMR; Porosity; Porous media; Self-diffusion coefficient; Time Factors
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2012.01.020

[Display omitted] ► We investigate the self-diffusion of liquids in a porous media formed by glass beads. ► We describe the time dependence of the self-diffusion. ► Choosing appropriate coordinates can reduce the time dependence to linear. ► Slope determined by the porous media geometry and the bulk self-diffusion coefficient. A new method of finding experimental time dependence of the self-diffusion coefficient D(t) for fluid in the porous media is proposed. We investigate the time-dependent self-diffusion coefficient D(t) of random walkers in permeable porous media. D(t) is measured in pulse field gradient (PFG) experiments with fluid-saturated porous media of randomly packed spherical glass beads. In absence of the specific interactions between pore walls and a fluid we show that D(t)=(D0-D∞)exp(-FD0t/d)+D∞, where D0 is the diffusion constant in a bulk fluid, D∞ is the asymptotical value of the diffusion coefficient for long diffusion times (t→∞), d is the bead diameter and F is the constant characterizing the geometry (the size and shape) pores.