NMR study of the vapor phase contribution to diffusion in partially filled silica glasses with nanometer and micrometer pores |
| |
Authors: | Ardelean Ioan Farrher German Mattea Carlos Kimmich Rainer |
| |
Affiliation: | Physics Department, Technical University, 400020 Cluj-Napoca, Romania. ioan.ardelean@phys.utcluj.ro |
| |
Abstract: | The contribution of the vapor phase to molecular diffusion in porous silica glasses with nanometer (Vycor) and micrometer (VitraPor#5) pores partially filled with water (polar) or cyclohexane (nonpolar) was investigated with the aid of field-gradient NMR diffusometry. Due to the vapor phase, the effective diffusion coefficient of cyclohexane filling micrometer pores (VitraPor#5) increased up to 10 times relative to the value in bulk liquid upon reduction of the pore space filling factor. On the other hand, the effective diffusion coefficient of water first decreases and then increases when the liquid content is reduced. The dependence of the effective diffusion coefficient on the pore filling factor is strongly related to the pore dimension. A general two-phase exchange model is presented that is well accounting for all experimental diffusion features. |
| |
Keywords: | |
本文献已被 ScienceDirect PubMed 等数据库收录! |