N-Nitrosamines are a class of organic compounds that are known to be mutagenic and carcinogenic and receive a lot of attention due to their toxic nature and omnipresence in the environment. In amine-based Carbon Capture and Sequestration (CCS) technologies, N-Nitrosamines garner attention as some amines, specifically secondary amines, can react with residual NO<sub>x</sub> in flue gases to form N-nitrosamines. Due to their toxic nature these compounds are a health risk to the public if they are dispersed into the surrounding air and drinking water from direct emissions from the capture facility. Waterwash systems have been applied to capture systems to help reduce emissions and trap volatile N-nitrosamines. N-Nitrosamines can then be removed from this water through a variety of treatment options including ultraviolet (UV) treatments and adsorption onto activated carbons. While UV treatments have been shown effective at controlling the N-nitrosamine levels, they cannot fully decompose the N-nitrosamines in the solution, efficiencies are impacted by the pH of system. Activated carbons have high capacities for N-nitrosamine adsorption however they need to be periodically regenerated or replaced, which can be costly. This work proposes the development and testing of a flow through process using stationary carbon electrodes inside an electrochemical cell to facilitate the electrochemical-mediated reduction reaction of the N-nitrosamines. This process can decompose these hazardous compounds without the need for additional treatment steps or the production of undesired by products. We examined the reduction of N-nitrosopyrrolidine, N-nitrosodiethylamine and N-nitrosomorpholine from waterwash solutions. The efficiency of the cell was evaluated at different operating conditions, including concentration and flow rate, where a greater than 90% removal efficiency and 20% charge efficiency were observed. The simultaneous decomposition of the 3 N-nitrosamines in solution demonstrates no preference to type of N-nitrosamine and a high reduction efficiency in varying operating conditions highlight the effectiveness of the cell for this application in carbon capture systems with potential application to broader wastewater treatment.

Electrochemical reduction of N-Nitrosamines in waterwash solutions

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