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Preparation of Macroporous Epitaxial Quartz Films on Silicon by Chemical Solution Deposition
Published on: December 21, 2015
Diffusion within ultrathin, dense nanoporous silica films
Thomas C McDermott1, Taslima Akter, J M Don MacElroy
1UCD School of Chemical and Bioprocess Engineering, the SEC Strategic Research Cluster and the Centre for Synthesis and Chemical Biology, the Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 2, 2011
Summary
A new dual-mode transport model explains gas separation in dense silica films. This model, validated by simulations, reveals fast and slow diffusion pathways crucial for membrane performance.
Area of Science:
- Materials Science
- Chemical Engineering
- Physical Chemistry
Background:
- Dense silica films are key in membrane separations.
- Existing models for gas transport in these films are often oversimplified.
- Anomalies in gas transport suggest a more complex mechanism than simple activated diffusion.
Purpose of the Study:
- To investigate the origin of permselectivity in dense silica films.
- To develop a new model explaining gas transport in thin selective coatings.
- To understand the dual-mode transport phenomenon in membrane systems.
Main Methods:
- Development of a novel dual-mode transport model.
- Molecular dynamics simulations for gas diffusion (He, N2, CO2) in silica.
- Construction of 3D periodic atomistic silica structures with controlled density.
Main Results:
- The proposed model successfully explains permselectivity in dense silica films.
- Simulations confirm the existence of two distinct transport domains: fast non-Fickian and slow Fickian.
- Results align qualitatively with experimental observations of gas transport.
Conclusions:
- Dual-mode transport is central to understanding permselectivity in composite membranes.
- The new model provides a more accurate framework for designing advanced membrane separation processes.
- This research advances the fundamental understanding of gas diffusion in dense materials.
