Texas Tech University

Converting Wastewater Nitrates to Ammonia Through the Power of Sunlight

Amanda Bowman

September 9, 2021

Joe Gauthier

Engineering professor Joe Gauthier is part of a team researching how to turn wastewater nitrates into a usable commodity.

Joe Gauthier, an assistant professor of chemical engineering in the Edward E. Whitacre Jr. College of Engineering at Texas Tech University, partnered with a team of researchers from the University of Illinois and Dow Chemical to find a new catalyst to convert nitrates into ammonia.

“Nitrates are a common environmental pollutant found in farm runoff from applying fertilizer or in human waste treatment facilities, for instance,” Gauthier said. “We're trying to electrochemically convert that chemical to ammonia, which is used in fertilizers along with nitrate.”

Ammonia is considered a building-block chemical. It's a key component in many everyday products. Unfortunately, the way ammonia is manufactured is outdated.

“Ammonia is an essential commodity chemical used in the manufacture of fertilizers, pharmaceuticals, ammunition and plastics, and is a promising alternative fuel source and energy carrier,” Gauthier said. “Today, most ammonia is manufactured by the century-old Haber-Bosch process, which accounts for 1-2% of worldwide energy production and a substantial fraction of global greenhouse gas emissions. Solar-driven electrochemical synthesis of ammonia using nitrates presents a sustainable way to produce renewable fuels and chemicals using waste products.”

While researchers have used solar-driven processes in the past, the solar-to-fuel efficiency was limited to less than 1%. Gauthier and the team he collaborated with found a way to increase the solar-to-fuel efficiency to 11%.

The team's paper, “Solar-driven Electrochemical Synthesis of Ammonia Using Nitrate With 11% Solar-to-Fuel Efficiency at Ambient Conditions,” was recently published in Energy and Environmental Science.

“Energy and Environmental Science is among the more selective journals,” Gauthier said. “As far as the impact factor, which measures the citation rate of papers, it's up there with Nature and Science.

“I'm honored to have our work selected for recognition. I hope our study helps reduce wastewater nitrates and greenhouse gas emissions.”