Pore size effects on convective flow and diffusion through nanoporous silica gels
Journal article, 2015
Material structure has great impact on mass transport properties, a relationship that needs to be understood on several length scales. Describing and controlling the properties of flow through soft materials are both challenges concerning the industrial use of gel structures. This paper reports on how the porous structure in nanoporous materials affects the water transport through them. We used three different silica gels with large differences in the pore sizes but of equal silica concentration. Particle morphology and gel structure were studied using high-resolution transmission electron microscopy and image analysis to estimate the pore size distribution and intrinsic surface area of each gel. The mass transport was studied using a flow measurement setup and nuclear magnetic resonance diffusometry. The average pore size ranged from approximately 500. nm down to approximately 40. nm. An acknowledged limit for convective flow to occur is in the pore size range between 100 and 200. nm. The results verified the existence of a non-linear relationship between pore size and liquid flow at length scales below 500. nm, experimentally. A factor of 4.3 in flow speed separated the coarser gel from the other two, which presented almost identical flow speed data despite a factor 3 in pore size difference. In the setup, the mass transport in the gel with the largest pores was flow dominated, while the mass transport in the finer gels was diffusion dominated. Besides providing new insights into mass transport as a function of pore sizes, we conclude that three-dimensional analysis of the structures is needed for a comprehensive understanding of the correlation between structure and mass transport properties.
Model material
Mass transport
Liquid permeability
Silica gel
Nanoporous
Author
Charlotte Hamngren Blomqvist
Chalmers, Applied Physics, Eva Olsson Group
SuMo Biomaterials
Christoffer Abrahamsson
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
SuMo Biomaterials
Tobias Gebäck
SuMo Biomaterials
University of Gothenburg
Chalmers, Mathematical Sciences, Mathematics
Annika Altskär
SP Food and Bioscience
SuMo Biomaterials
Anne-Marie Hermansson
Chalmers, Biology and Biological Engineering, Food and Nutrition Science
SuMo Biomaterials
Magnus Nydén
SuMo Biomaterials
University of South Australia
Stefan Gustafsson
SuMo Biomaterials
Chalmers, Applied Physics, Eva Olsson Group
Niklas Lorén
Chalmers, Applied Physics, Eva Olsson Group
SuMo Biomaterials
Eva Olsson
Chalmers, Applied Physics, Eva Olsson Group
SuMo Biomaterials
Colloids and Surfaces A: Physicochemical and Engineering Aspects
0927-7757 (ISSN) 18734359 (eISSN)
Vol. 484 288-296Enabling Science and Technology through European Electron Microscopy (ESTEEM 2)
European Commission (EC) (EC/FP7/312483), 2012-10-01 -- 2016-09-30.
Areas of Advance
Nanoscience and Nanotechnology
Materials Science
Subject Categories
Physical Sciences
Other Materials Engineering
DOI
10.1016/j.colsurfa.2015.07.032