Activated carbon (AC) materials with micro- and nano-porous structures are commonly used in the solid phase extraction of nitrosamine contaminants in water, and for the removal of micropollutants in water treatment. Our research found that many commercial AC materials can catalyze transformation of secondary amines and certain tertiary amines to yield trace levels of carcinogenic N-nitrosamines under ambient aerobic conditions. The AC-catalyzed nitrosamine formation is highly influenced by the AC material properties and the amine precursor structures. Mechanistic investigation reveals that the reaction involves both atmospheric oxygen and nitrogen. AC's surface reactive sites react with molecular oxygen to form reactive oxygen species (ROS), which facilitate fixation of molecular nitrogen on the carbon surfaces to generate reactive nitrogen species (RNS) likely nitrous oxide and hydroxylamine that can react with adsorbed amines to form nitrosamines. AC's properties play a crucial role as more nitrosamine formation is associated with carbon surfaces with higher surface area, more surface defects, reduced surface properties, higher O2 uptake capacity, and higher carbonyl group content. The chemical phenomena identified by this study are not only critical for minimization of nitrosamine formation in AC-based analytical procedures and water treatment, but may also be relevant for a wide range of processes involving synthetic and naturally-occurring activated carbons materials.

Interactions of amines with activated carbons and potential catalyzed nitrosamine formation

244th National Meeting (2012)

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