During CO2 absorption by soda lime, which reactant is regenerated?

During CO2 absorption by soda lime, the primary reactant that is involved is calcium hydroxide. Soda lime consists mainly of a mixture of sodium hydroxide and calcium hydroxide, which effectively absorbs carbon dioxide from the air or gas flow.

When CO2 interacts with calcium hydroxide, a reaction occurs where calcium carbonate is produced. However, in a continuous process, the calcium carbonate can decompose when heated, regenerating calcium hydroxide and releasing CO2 back into the environment, allowing it to be reused in the absorption process.

This means that while sodium hydroxide is present in the mixture, it does not participate in the regeneration of a reactant after the absorption of CO2. Therefore, the key substance that undergoes a cycle between reacting to form products and being regenerated for further CO2 absorption is calcium hydroxide. This detailed understanding emphasizes the role of calcium hydroxide in the overall process of CO2 absorption using soda lime.