Acetaldehyde Removal from Indoor Air through Chemical Absorption Using L-Cysteine

The irreversible removal of acetaldehyde from indoor air via a chemical reaction with amino acids was investigated. To compare effectiveness, five types of amino acid (glycine, l-lysine, l-methionine, l-cysteine, and l-cystine) were used as the reactants. First, acetaldehyde-laden air was introduced into aqueous solutions of each amino acid and the removal abilities were compared. Among the five amino acids, l-cysteine solution showed much higher removal efficiency, while the other amino acids solutions didn't show any significant differences from the removal efficiency of water used as a control. Next, as a test of the removal abilities of acetaldehyde by semi-solid l-cysteine, a gel containing l-cysteine solution was put in a fluororesin bag filled with acetaldehyde gas, and the change of acetaldehyde concentration was measured. The l-cysteine-containing gel removed 80% of the acetaldehyde in the air within 24 hours. The removal ability likely depended on the unique reaction whereby acetaldehyde and l-cysteine rapidly produce 2-methylthiazolidine-4-carboxylic acid. These results suggested that the reaction between acetaldehyde and l-cysteine has possibilities for irreversibly removing toxic acetaldehyde from indoor air.