Highly Efficient Decomposition of N-Nitrosamines in Wastewater from CO₂ Capture Systems

As amine-based carbon capture moves toward widespread deployment, there has been an emphasis on the potential environmental and human-health impacts of the technology due to solvent degradation. N-nitrosamines are a class of documented amine degradation products with known volatility and toxicity whose emissions can be reduced by using waterwash units. However, to further reduce their secondary emissions, the destruction of N-nitrosamines within the waterwashing system is desirable. Electrochemical reduction has been successful in decomposing N-nitrosamines from amine waterwash systems; nevertheless, as with other electrochemical systems, electrode material and long-term stability are essential for practical applications. In this work, the decomposition efficiency of three N-nitrosamines was investigated by using a flow-through electrochemical cell with four different carbon-based electrode materials. The carbon xerogel, carbon cloth, ELAT, and CeTech electrodes each demonstrated the ability to decompose N-nitrosamines between 50 and 99%. In addition, the carbon cloth electrodes and ELAT electrodes exhibited extended stability up to 500 h of operation. The results highlight the benefits of this technology to address and minimize the emerging environmental impacts of CO₂ capture systems as they increase in prevalence.