1. One of the principle causes of amine foaming is the introduction of
hydrocarbon liquids into the amine contactor. When hydrocarbon
liquids enter the contactor, they are highly soluble into the amine
solution and reduce the surface tension of the aqueous solution.
The reduced surface tension then aids in creating bubbles of gas in
the amine solution, resulting in foaming.
Please see very good article;
https://www.emerson.com/documents/automation/application-note-avoiding-amine-foaming-issues-utilizing-a-gas-chromatograph-rosemount-en-72720.pdf