Outlining Key Perspectives for the Advancement of Electrocatalytic Remediation of Nitrate from Polluted Waters

Abstract

As nitrate pollution in groundwater continues to escalate, more is being discovered about the detrimental health implications associated with concentrated nitrate ingestion. Thus, there is a great necessity for the effective and sustainable remediation of nitrate from water. The electrocatalytic reduction of nitrate (ERN) has been identified as a promising technology with respect to selective product formation (N 2(g) and NH3/NH4 +), adaptable instrument configurations, and compatibility with renewable energy sources. Electrocatalysts with appreciable selectivity for nitrate reduction to nitrogen gas are of great importance for drinking water applications. On the other hand, ammonia-selective catalysts are desirable for resource recovery. Traditional catalysts for ERN applications include expensive platinum group metals, which makes the widespread utilization of this technology economically unfavorable. Alternatively, research within the last five years has shown cost-effective catalytic materials such as bimetallic systems, graphitic composites, metal oxides, and metal sulfides exhibiting substantial activity/selectivity for ERN applications. Future ERN catalysts must not only express significant activity/selectivity but also be capable of stable and consistent performance under varying water chemistries. Combating electrocatalyst aging and fouling processes will be key in material design for catalysts capable of efficient remediation of nitrate from water under continuous long-term operation.

Combined Effects of Concentration, pH, and Polycrystalline Copper Surfaces on Electrocatalytic Nitrate-to-Ammonia Activity and Selectivity

“…The state-of-the-art nitrate treatments are biological nitrification–denitrification for wastewater treatment and physical separation technologies, such as ion-exchange and reverse osmosis, for drinking water. , These approaches are effective for removing NO 3 – in the form of N 2 (biological nitrification–denitrification) or to displace NO 3 – into a more concentrated secondary waste stream (ion-exchange, reverse osmosis). Electrochemical approaches have been proposed to recover nitrogen nutrients by driving the thermodynamically favorable NO 3 – to NH 3 conversion instead of reducing it to N 2 . ,− Therefore, electrocatalytic NO 3 – reduction to NH 3 has been extensively investigated in recent work.…”

Overcoming barriers for nitrate electrochemical reduction: By-passing water hardness

“…The effect of coexisting electrolytes during ERN should be addressed (Sergi Garcia-Segura et al, 2018;Katsounaros and Kyriacou, 2008). Understanding the impact of ionic species of environmental relevance is an urgent need to assess the competitiveness of emerging technologies under real conditions (Flores et al, 2022;Werth et al, 2021).…”

“…Electrochemically-driven nitrate reduction takes place at the cathode surface mediated by direct charge transfer processes (Flores et al, 2022;S. Garcia-Segura et al, 2018).…”

“…Nitrate reduction towards ammonia following Reaction (1) can be a resourceful approach for sustainable nitrogen recovery for agriculture applications (Gabriel Antonio Cerrón-Calle et al, 2022;Katsounaros, 2021;van Langevelde et al, 2021). The nitrate reduction towards innocuous nitrogen gas by Reaction (2) is of utmost importance for drinking water purposes (Flores et al, 2022).…”

Comparing the effects of Cu-Ti/RuO2-IrO2 electrode configuration on the electro-reduction of nitrate

“…The selectivity and kinetics of nitrate electro-reduction are affected by the choice of electrocatalytic materials (Marcos-Hernández et al 2022). The fundamentals and challenges of nitrate electroreduction are reviewed by Garcia-Segura et al (2018) and Flores et al (2022).…”