Absorption (chemistry)
Chemical absorption is the process of picking up or " loosening " of an atom, molecule or an ion in a different phase. This is not an attachment to the surface ( adsorption), but a recording in the free volume of the absorbing phase.
Chemical absorption is now used among other things for the purification of industrial waste gas, such as air galvanizing equipment or to eliminate odors. Due to the legal requirements of the limits (about TA Luft ) for certain substances, which have been repeatedly tightened, the absorption technology is becoming increasingly important.
Absorption can occur in bubble column reactors, on membrane technologies or with the regenerative falling-film technology.
Absorption of substances
The absorption of a substance by another means mixing without chemical reaction. The operation of the absorption caused by an affinity of a substance for the other - there is a certain solubility of the substances with each other. The absorption of gases can not only be in a liquid, but also in a solid. The gas is dissolved at a given temperature in the absorption means, said heat ( heat absorption or heat of solution ) is produced. This is absorbent ( or absorbent), the captured gas is called absorbate.
If it is a closed system, for example a liquid and a gas to flow (diffusion), first, the gaseous atoms or molecules in the liquid until the solubility of the gas is achieved in the liquid. In this case, a dynamic equilibrium is established, that is, the particle in the liquid is equal to the particle flow in the gas phase.
Found in the solution of the gases, no chemical reactions take place, as is true for fluids at low pressure approximately the Henry's law. At a given temperature, the concentration of a gas is proportional to its pressure on the liquid:
Here, the absorption coefficient, which depends on the temperature and the materials involved. If several gases involved in the absorption, so they are solved independently in accordance with their respective partial pressure in the gas phase:
With a gas, a plurality of immiscible liquids involved as the absorbent, the ratio of the concentration is independent of the amount of solute and the liquid and depends only on the temperature and the material; see Africans Chernobyl distribution set.