The effect of two critical operating factors on the enhanced catalytic conversion of aqueous NO3– to NH4+ by Pt-Co@NC and theoretical verification of its surface reaction mechanism


Nurlan N. Jeong J. Nurmyrza M. Kim H. Shin H. Lee W.
15 January 2025Elsevier B.V.

Chemical Engineering Journal
2025#506

Elevated nitrate (NO3−) levels in water sources, primarily due to agricultural activities, landfills, and inadequate wastewater treatment, pose significant health risks. Traditional nitrate removal technologies face challenges like high costs and byproduct formation. This study aims to explore the catalytic reduction of NO3− to green ammonia (NH3) and ammonium (NH4+) using a Pt-Co@NC (Pt-impregnated core–shell Cobalt N-doped Carbon Nanocage (acid-washed) catalyst), offering a sustainable alternative to the Haber-Bosch process. To elucidate the underlying mechanisms contributing to the superior reactivity of Pt-Co@NC, density functional theory (DFT) calculations were performed, aiming to provide an in-depth understanding of the nitrate reduction process that facilitates the selective conversion of NO3– to NH4+. We proved that the Pt cluster can provide a favorable environment for hydrogenation steps in nitrate reduction. Based on calculation results, with experiments and kinetic modeling, we optimized conditions such as hydrogen flow rate (200 mL⋅min−1) and NO3− concentration (5 m g⋅L-1) to maximize efficiency and selectivity. In following synthetic wastewater tests, the Pt-Co@NC catalyst maintained high NH4+ selectivity and efficient NO3− reduction despite the presence of competing ions, demonstrating robust performance with a kinetic rate constant of 6.67 × 10-2 min−1. These results advance our understanding of NO3− reduction mechanisms and provide a viable solution for sustainable nitrate removal and ammonia production. The Pt-Co@NC catalysts effectiveness in controlled and synthetic wastewater conditions highlights its potential applicability in real-world water treatment scenarios. The insights on the catalyst design and its operational optimization could lead to the development of advanced catalytic materials and green technologies for efficient treatment and remediation of contaminated water environments.

Ammonium selectivity , Catalysts , Density functional theory , Green ammonia production , Nitrate reduction , Zeolite-imidazole framework

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Department of Mathematical and Physical Sciences, University College London, London, WC1E 6BT, United Kingdom
Laboratory of Environmental Systems, National Laboratory Astana, Nazarbayev University, Astana, 010000, Kazakhstan
Department of Chemistry, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea
Department of Civil and Environmental Engineering, Nazarbayev University, Astana, 010000, Kazakhstan
of Energy Science and Technology, Chungnam National University, Daejeon, 34134, South Korea

Department of Mathematical and Physical Sciences
Laboratory of Environmental Systems
Department of Chemistry
Department of Civil and Environmental Engineering
of Energy Science and Technology

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