ABSTRACT
Absorption, stripping, and scrubbing are all processes involving the contacting of a liquid and a gas followed by separation of the two phases. Absorption is a unit operation in which a liquid solvent is contacted with a gas and the soluble components in the gas dissolve in the liquid. The liquid is called the absorption solvent. The reverse of this, i.e., the transfer of volatile components from a liquid to a gas, is called stripping. The gas is called the stripping gas. Stripping is accomplished by contacting the liquid with an inert gas such as nitrogen or steam. With aqueous waste streams the stripping gas is usually air. Absorption and stripping are frequently used together. Absorption is used to remove the soluble component(s) from the gas stream, and stripping is used to regenerate the solvent by removing the dissolved component(s) from the spent solvent. Figure 13.1 shows such a plant. Conversely, absorption in a solvent can be used to recover the gaseous product removed in a stripping operation when it cannot be condensed. It is an alternative to adsorption for the recovery of gaseous components. However, it should be remembered that adsorption uses solid surfaces <target id="page_342" target-type="page">342</target>Sketch of a typical absorption-stripping plant flow diagram. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003067481/be37ef78-a818-4c91-9295-2c56cdba16a4/content/fig13_13_1.tif"/> on which to capture the desired components, while absorption uses liquid solvents to dissolve the soluble components.
