Capillary Condensation

capillary condensation

[′kap·ə‚ler·ē ‚kän‚den′sā·shən]
(physical chemistry)
Condensation of an adsorbed vapor within the pores of the adsorbate.

Capillary Condensation


the condensation of vapor in the capillaries and microcracks of porous bodies or in the interstices between closely packed particles.

A necessary condition for capillary condensation is the wetting of the surface of the material (particles) by the liquid. Capillary condensation starts with the adsorption of vapor molecules by the condensation surface and the formation of liquid menisci. The pressure of the saturated vapor over concave menisci is, according to Kelvin’s equation, lower than the saturated vapor pressure p0 over a flat surface. Capillary condensation proceeds, therefore, at lower vapor pressures than the saturation pressure P0. The volume of liquid condensed in pores attains its limiting value at external vapor pressure p = p0, where the liquid-gas interface has zero curvature (plane, catenoid).

The complex capillary structure of a porous body may be the cause of capillary hysteresis, that is, the dependence of the quantity of liquid condensed in the pores not only on vapor pressure but also on the prehistory of the process, that is, how the given state was attained—by the condensation or by the evaporation of the liquid.

Capillary condensation increases the absorption (sorption) of vapors by porous bodies, particularly near the point of vapor saturation. The phenomenon of capillary condensation is used industrially in trapping liquids by finely porous materials (sorbents). Capillary condensation also has an important role in the processes of drying and moisture retention in soils, construction materials, and other porous materials.


Kurs fizicheskoi khimii, 2nd ed., vol. 1. Edited by Ia. I. Gerasimov. Moscow, 1969.


References in periodicals archive ?
The Kelvin equation shows that a reduction in vapor pressure over a curved meniscus results in capillary condensation.
At 80% relative humidity you get liquid-phase water in the pores of the paper-faced gypsum due to capillary condensation (Photo 1).
In case of a system comprised of a totality of open and closed (test-tube-shaped) capillaries, capillary condensation at every given P/[P.
In case of using the capillary condensation method, it is necessary to take into account the concurrent multimolecular adsorption process and its contribution to the total sorption process.
The mass spectrometer will consist of integrally spectrometer, heated capillary condensation control less volatile phase, vacuum unit and PC for evaluation measurements.
The Transport Membrane Humidifier (TMH) technology was developed by using a nanoporous membrane that facilitates a capillary condensation separation mechanism which transports water vapor only from furnace combustion flue gas to humidify building air.
The low-temperature, high-flow-rate room circulating air passing over the membrane surfaces provides adequate membrane cooling to facilitate the high-performance capillary condensation water vapor separation mode.
There are also chapters on topics not usually covered in tribology texts but which become important at the small scale, such as capillary condensation, disjoining pressure, contact electrification, and molecular slippage at interfaces.
The study of capillary condensation (the formation of a liquid at a solid-vapour interface in tight cracks or pores at pressures below the saturation pressure) is of great practical importance in nanotechnology applications and in oil recovery, and provides useful insight into phenomena that occur in porous materials.
With a view to understanding adhesion, friction, and wear, researchers have been using AFM force curves to study the formation or suppression of capillary condensation on hydrophilic silicon, amorphous carbon, and lubricated Si[O.
A Transport Membrane Humidifier (TMH) concept was developed by using a nanoporous membrane that facilitates a capillary condensation separation mechanism which transports water vapor only from furnace combustion flue gas to humidify building air.
For certain porous materials, water vapor will condense within the pores due to capillary condensation.