Pore size effects on convective flow and diffusion through nanoporous silica gels
Artikel i vetenskaplig tidskrift, 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.

Nanoporous

Liquid permeability

Mass transport

Silica gel

Model material

Författare

Charlotte Hamngren Blomqvist

Chalmers, Teknisk fysik, Eva Olsson Group

SuMo Biomaterials

Christoffer Abrahamsson

Kemi och kemiteknik, Tillämpad kemi, Teknisk ytkemi

SuMo Biomaterials

Tobias Gebäck

SuMo Biomaterials

Göteborgs universitet

Chalmers, Matematiska vetenskaper, Matematik

A. Altskär

Chalmers University of Technology

Structure and Material Design

Anne-Marie Hermansson

Chalmers, Biologi och bioteknik, Livsmedelsvetenskap

SuMo Biomaterials

Magnus Nydén

University of South Australia

Chalmers University of Technology

Stefan Gustafsson

SuMo Biomaterials

Chalmers, Teknisk fysik, Eva Olsson Group

Niklas Lorén

SuMo Biomaterials

Chalmers, Teknisk fysik, Eva Olsson Group

Eva Olsson

Chalmers, Teknisk fysik, Eva Olsson Group

SuMo Biomaterials

Colloids and Surfaces A: Physicochemical and Engineering Aspects

0927-7757 (ISSN)

Vol. 484 288-296

Styrkeområden

Nanovetenskap och nanoteknik

Materialvetenskap

Ämneskategorier

Fysik

Annan materialteknik

DOI

10.1016/j.colsurfa.2015.07.032