According to film model when a gas component is subject to an mth or pseudomth order reaction, the absorption rate is expressed by

As an example, the oxygen takes part in a second-order reaction in the sulphite oxidation system which is often used for comparing gas-liquid interfacial area in various reactors. A more detailed information of mth order reactions can be found from article published by Hikita and Asai (1964).

Absorption accompanied by irreversible second order reactions:

The gas-liquid reactions are found in many chemical industries where a gas component A reacts with a liquid component B as: