Fickian and thermal diffusion coefficients of binary mixtures of isobutylbenzene and n-alkanes at different concentrations from the optical beam deflection technique.

We report the Fickian diffusion (D), thermal diffusion (D), and Soret (S) coefficients of 4 binary mixtures of isobutylbenzene (IBB) and n-alkanes (n-hexane, n-octane, n-decane, and n-dodecane) at 298.15 K and atmospheric pressure. The concentration is varied in the whole range.

Paramagnetic relaxation enhancement (PRE) as a tool for probing diffusion in environmentally relevant porous media.

The transport diffusivity of the paramagnetic molecule 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) was measured by monitoring its influence on the NMR transverse relaxation time (T₂) on surrounding water protons - also known as paramagnetic relaxation enhancement (PRE). Due to the nature of the PRE effect, few paramagnetic molecules are able to simultaneously reduce the T₂ of many NMR active nuclei, which represents a significant gain in sensitivity. In an aqueous solution, the minimal detectable TEMPO concentration was around 70 ppm.

Guest diffusion in interpenetrating networks of micro- and mesopores.

Pulsed field gradient NMR is applied for monitoring the diffusion properties of guest molecules in hierarchical pore systems after pressure variation in the external atmosphere. Following previous studies with purely mesoporous solids, also in the material containing both micro- and mesopores (activated carbon MA2), the diffusivity of the guest molecules (cyclohexane) is found to be most decisively determined by the sample "history": at a given external pressure, diffusivities are always found to be larger if they are measured after pressure decrease (i.e.

Tracing pore-space heterogeneities in X-type zeolites by diffusion studies.

Pore-space homogeneity of zeolite NaX was probed by pulsed field gradient (PFG) NMR diffusion studies with n-butane as a guest molecule. At a loading of 0.75 molecules per supercage, a wide spectrum of diffusivities was observed.