Mechanism of N-nitrosamine formation from secondary amine on the surface of activate carbon

Abstract

Our study demonstrates that many commercial activated carbon (AC) particles may catalyze transformation of secondary amines to yield trace levels of N-nitrosamines under ambient aerobic conditions. The results show that the AC-catalyzed nitrosamine formation requires 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. This study is a first of its kind on the nitrosamine formation mechanism involving nitrogen fixation on AC surfaces and the information will be useful for minimization of nitrosamines in AC-based processes.