Development of New Catalysts for Nitrite and Nitrate Reduction to Ammonia

The nitrogen cycle is one of the most important biogeochemical cycles on Earth, as nitrogen is an essential nutrient for all forms of life, from bacteria to humans. This cycle comprises several processes, including nitrogen fixation, which may occur either industrially or biologically by nitrogen-fixing bacteria, where molecular nitrogen (N₂) is reduced to ammonia (NH₃).  However, the excessive use of fertilizers has caused serious environmental and health problems due to the formation of nitrite, nitrate, and nitrogen oxides, which contribute to the greenhouse effect. This work reports the synthesis and characterization of the salen ligand and the Co(salen) complex for their potential application as catalysts for the reduction of nitrite and nitrate to ammonia.