2025 AIChE Annual Meeting

(119a) Electrochemical Ammonia Production from Nitrate Found in Groundwater

Authors

Elizabeth Corson - Presenter, University of California, Berkeley
Apoorva Ranjekar, University of Kansas
Mohammad Abazid, University of Kansas
Nitrate-contaminated water poses significant health risks to humans and adversely affects ecosystems through eutrophication. Traditional methods for nitrate removal aim to convert reactive nitrogen species into inert dinitrogen. However, we propose an alternative approach: electrochemically reducing nitrate to ammonia. Ammonia can serve as a fertilizer, chemical precursor, or alternative fuel. Electrochemical water treatment methods are versatile and can be applied in both urban and rural areas. They are modular, scalable, operable at ambient temperature and pressure, and can utilize any electricity source.

In this study, we examine the influence of common groundwater ions (e.g., calcium, chloride, etc.) on the electrochemical reduction of nitrate to ammonia. We use in situ attenuated total reflectance–surface-enhanced infrared adsorption spectroscopy (ATR–SEIRAS) to investigate the effects of water contaminants on adsorbed reactants and reaction intermediates. Additionally, in situ surface-enhanced Raman spectroscopy (SERS) is employed to uncover the surface-deactivation mechanisms caused by these contaminants. The results from in situ spectroscopy are correlated with product analysis experiments to assess the selectivity and efficiency of ammonia synthesis. Gaseous products are analyzed using gas chromatography (GC), while liquid products are quantified through nuclear magnetic resonance (NMR). Our study aims to identify strategies to prevent cathode deactivation, such as optimizing operating conditions and modifying catalyst surfaces, to enable effective electrochemical nitrate reduction to ammonia in typical groundwater compositions without requiring additional purification or chemical additives.