Adsorption capacity

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In process engineering, the adsorption capacity , loading height or adsorption capacity describes the amount of material to be adsorbed from the fluid (adsorptive) per amount of adsorbent .

Adsorption capacities are usually given in grams per 100 grams of adsorbent. Since they are dependent on the temperature and concentration or partial pressure of the adsorptive, adsorption capacities are usually specified in such a way that the stated boundary conditions can be recognized. The adsorption capacity increases with the adsorptive concentration in the gas phase and decreases with the operating temperature. The representation of the adsorption capacity as a function of partial pressure or concentration of the adsorptive is known as an adsorption isotherm .

In technical applications, residual loads after regeneration (usually desorption by means of superheated steam or a temperature increase and subsequent drying and cooling) lead to a reduction in the adsorption capacity. This can make it necessary to reactivate or replace the adsorbent. By impregnating adsorbents, especially activated carbon , the adsorption capacity for poorly adsorbable substances can be increased. The separation mechanism is changed from physisorption to chemisorption during this process .

To compare the adsorption capacities of different adsorbents for exhaust gas cleaning, there is a standardized method for their determination. For this purpose, air mixed with pure benzene flows as test gas over the adsorbent until the adsorbent no longer increases in weight. To avoid competing adsorption , the test gas must be free of water vapor.

Individual evidence

  1. a b c Harald Menig: Air pollution control through adsorption, absorption and oxidation . Deutscher Fachschriften-Verlag, Wiesbaden 1977, ISBN 3-8078-8056-9 , p. 34 and 76 .
  2. a b c VDI 3674: 2013-04 Exhaust gas cleaning through adsorption; Process gas and waste gas cleaning (Waste gas cleaning by adsorption; Process gas and waste gas cleaning) . Beuth Verlag, Berlin 2013, p. 5, 15 and 22 .
  3. Klaus Sattler: Thermal separation processes: Basics, design, apparatus . Wiley-VCH, Weinheim 1977, ISBN 978-3-527-66078-0 .