Adsorption hysteresis in porous solids
- Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Chemical Engineering
Hysteresis has been observed in adsorption isotherms for a number of gas-solid systems and, generally, is attributed to adsorption in mesoporous materials with capillary condensation. This behavior is classified as Type IV or Type V in the IUPAC classification scheme. Here, lattice theory is used to predict adsorption behavior in pores. The Ono-Kondo theory is used with appropriate boundary conditions for fluid adsorption in infinite and semi-finite slit-like pores. It is shown that there can be phase transitions in the adsorbed phase which lead to hysteresis in kinetically controlled experiments. However, hysteresis in equilibrium behavior is exhibited only in pores of finite length. For finite-length pores, the interface geometry is predicted to be different during the processes of adsorption and desorption and this difference in interface shape leads to hysteresis. This simple molecular model is able to predict the change in the interface geometry without invoking the Kelvin equation or the macroscopic concept of surface tension.
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- FG02-87ER13777
- OSTI ID:
- 659098
- Journal Information:
- Journal of Colloid and Interface Science, Journal Name: Journal of Colloid and Interface Science Journal Issue: 1 Vol. 205; ISSN 0021-9797; ISSN JCISA5
- Country of Publication:
- United States
- Language:
- English
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