A revolutionary new reactor has been developed that can convert wastewater contaminated with nitrate ions into both clean drinking water and ammonia gas, a highly sought-after industrial chemical. Described in the journal *Nature Catalysis*, this reactor offers a promising solution for addressing two pressing global challenges: water pollution and ammonia production.
Ammonia (NH3) is a crucial industrial chemical, playing a vital role in fertilizer production and various chemical manufacturing processes. Currently, the majority of ammonia is produced using the century-old Haber-Bosch process, which involves a high-temperature, high-pressure reaction between hydrogen and nitrogen. This process, however, consumes approximately 2% of the world’s energy.
Nitrate, a common pollutant in rivers and streams, originates from excess runoff from fertilized farmland. It poses a severe threat to aquatic ecosystems and can be detrimental to human health at elevated levels in drinking water. Existing water treatment methods typically employ bacteria to convert nitrate ions into nitrogen, but this process is expensive and generates nitrous oxide, a potent greenhouse gas.
The new reactor tackles these challenges by employing a three-chamber system. In the first chamber, nitrate is converted into ammonia gas and hydroxyl ions, which combine with sodium ions already present in the water to form sodium hydroxide. This cleaned water is then pumped into the middle chamber where the ammonia gas is bubbled out. Simultaneously, hydrogen ions produced in the third chamber through water splitting diffuse into the middle chamber and react with hydroxyl ions from the sodium hydroxide to form water. The remaining sodium ions then return to the first chamber to continue the cycle.
This innovative design effectively prevents hydrogen ions from interfering with the nitrate-to-ammonia conversion, a key hurdle faced by previous systems. In a 10-day trial, over 90% of the electric current powering the reactor was dedicated to ammonia production, compared to just 20% in earlier systems.
Despite its promising potential, this technology is still in its experimental phase. Further research is needed to ensure its effectiveness in the presence of common impurities found in water, such as magnesium and calcium ions. If successful, this breakthrough could revolutionize water treatment and significantly reduce our reliance on the energy-intensive Haber-Bosch process for ammonia production, paving the way for a more sustainable and environmentally friendly future.
