The contribution of each functional group can be evaluated by chemical treatment. It consists in carrying out chemical reactions that selectively block different functional groups on the sorbent surface. The most common chemical modifications are esterification of carboxylic and phosphate groups, methylation of amines, and modification of mercapto groups. Carboxylic groups can be alkylated by reaction with methanol or ethanol in acidic media, while amines by reaction with formaldehyde and formic acid. Alkylation of both functional groups prevents their participation in metal biosorption, thus reducing the biosorption efficiency.

Chemical treatments were also used to selectively extract different compounds, such as fats or polyphenols, in order to improve metal sorption. A report on the application of these methods can be found in a work of Nurchi at al., 2010.