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Updated: Oct 21, 2025
06:34
In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging
Published on: September 2, 2016
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Evaporation-Induced Diffusion Acceleration in Liquid-Filled Porous Materials
Xuefeng Wang1,2, Pengpeng Jia1,2, Shanyouming Sun2
1The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
ACS Omega
|September 2, 2021
Summary
Surface evaporation significantly accelerates substance diffusion in liquid-filled porous materials by inducing flow. This evaporation-induced flow and diffusion (EIFD) mechanism impacts concentration distribution and is crucial even at high humidity.
Area of Science:
- Multiphase flow and transport phenomena
- Porous media physics
- Diffusion and convection dynamics
Background:
- Liquid-filled porous materials are ubiquitous in nature and engineering.
- Substance diffusion in these materials is critical for system functions.
- The impact of surface evaporation on diffusion in such materials remains underexplored.
Purpose of the Study:
- To investigate the effects of surface evaporation on diffusion in liquid-filled porous materials.
- To elucidate the underlying mechanism of evaporation-induced changes in diffusion.
- To develop and validate a model for predicting diffusion under evaporative conditions.
Main Methods:
- Noninvasive diffusion imaging experiments using erioglaucine disodium salt dye in a nitrocellulose membrane.
- Experiments conducted across a range of relative humidities (RHs).
- Development and experimental validation of a convective diffusion model based on the EIFD mechanism.
Main Results:
- Evaporation significantly accelerates diffusion rates and alters concentration distribution compared to non-evaporative conditions.
- The phenomenon is explained by evaporation-induced flow (EIFD), leading to convective diffusion.
- Evaporation-induced diffusion dominates molecular diffusion even at 95% RH; induced flow velocity is 0.4-5 μm/s.
Conclusions:
- Evaporation-induced flow and diffusion (EIFD) is a key mechanism in liquid-filled porous materials.
- The proposed model accurately predicts diffusion under evaporation, with the Peclet number quantifying the evaporation effect.
- Findings have implications for understanding biological processes (e.g., tissue perfusion) and advancing technologies like paper-based diagnostics and seawater purification.
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