University of Michigan chemists report that a plant-inspired iron catalyst converted nitrate into ammonia at an 85% rate under blue LED light at room temperature in lab tests. The early-stage chemistry has not been tested in real-world wastewater.
The iron compound is surrounded by hydrogen bonds, a design inspired by proteins that capture nitrate in plants. With heat in solution, it removed one oxygen atom and produced nitric oxide; under blue light, it removed all three. Versions with hydrogen-bond donors bound nitrate up to 10 million times more strongly than versions without them. Light-driven tests recorded 5,000 nitrate molecules processed per catalyst molecule at very low catalyst loading.
Tests used small flasks, organic solvents and carefully prepared nitrate salts, not the complex conditions in wells or wastewater plants. Lead researcher Nathaniel Szymczak said compatibility with other wastewater products would make large-scale use challenging at present. Existing nitrate-removal methods include ion exchange and reverse osmosis; better fertilizer management can reduce runoff.
