{"id":97879,"date":"2021-09-29T07:23:00","date_gmt":"2021-09-29T05:23:00","guid":{"rendered":"https:\/\/renewable-carbon.eu\/news\/?p=97879"},"modified":"2021-09-27T14:31:19","modified_gmt":"2021-09-27T12:31:19","slug":"combining-sunlight-and-wastewater-nitrate-to-make-the-worlds-no-2-chemical","status":"publish","type":"post","link":"https:\/\/renewable-carbon.eu\/news\/combining-sunlight-and-wastewater-nitrate-to-make-the-worlds-no-2-chemical\/","title":{"rendered":"Combining sunlight and wastewater nitrate to make the world\u2019s No. 2 chemical"},"content":{"rendered":"\n\n\n
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A scientists holds an electrochemical circuit in which a solar cell is attached to a well holding a liquid solution. When charged, nitrates from wastewater in the liquid solution are converted to ammonia. (Photo: Meenesh Singh\/University of Illinois at Chicago)<\/figcaption><\/figure><\/div>\n\n\n\n

Engineers at the University of Illinois Chicago have created a solar-powered electrochemical reaction that not only uses wastewater to make ammonia \u2014 the second most-produced chemical in the world \u2014 but also achieves a solar-to-fuel efficiency that is 10 times better than any other comparable technology.<\/strong>  <\/p>\n\n\n\n

Their findings are published in Energy & Environmental Science<\/em><\/a>, a top journal for research at the intersection of energy delivery and environmental protections. <\/p>\n\n\n\n

\u201cThis technology and our method have great potential for allowing on-demand synthesis of fertilizers and could have an immense impact on the agricultural and energy sectors in developed and developing countries, and on efforts to reduce greenhouse gases from fossil fuels,\u201d said lead researcher Meenesh Singh, assistant professor of chemical engineering at the UIC College of Engineering.  <\/p>\n\n\n\n

Ammonia, a combination of one nitrogen atom and three hydrogen atoms, is a key compound of fertilizers and many manufactured products, like plastics and pharmaceuticals. Current methods to make ammonia from nitrogen require enormous amounts of heat, generated by burning fossil fuels, to break the strong bonds between nitrogen atoms so they can bind to hydrogen. This century-old process produces a substantial fraction of global greenhouse gas emissions, which are a driving force of climate change.  <\/p>\n\n\n\n

Previously, Singh and his colleagues developed an environmentally friendly method to make ammonia<\/a> by filtering pure nitrogen gas through an electrically charged, catalyst-covered mesh screen in a water-based solution. This reaction used only a tiny amount of fossil fuel energy to electrify the screen, which breaks apart nitrogen atoms, but it produced more hydrogen gas (80%) than ammonia (20%).  <\/p>\n\n\n\n

Now, the researchers have improved this concept and developed a new method that uses nitrate, one of the most common groundwater contaminants, to supply nitrogen and sunlight to electrify the reaction. The system produces nearly 100% ammonia with nearly zero hydrogen gas side reactions. The reaction needs no fossil fuels and produces no carbon dioxide or other greenhouse gases, and its use of solar power yields an unprecedented solar-to-fuel efficiency, or STF, of 11%, which is 10 times better than any other state-of-the-art system to produce ammonia (about 1% STF).  <\/p>\n\n\n\n

The new method hinges on a cobalt catalyst, which the researchers describe along with the new process in their paper, \u201cSolar-Driven Electrochemical Synthesis of Ammonia using Nitrate with 11% Solar-to-Fuel Efficiency at Ambient Conditions<\/a>.\u201d <\/p>\n\n\n\n

To identify the catalyst, the researchers first applied computational theory to predict which metal would work best. After identifying cobalt through these models, the team experimented with the metal, trying different ways to optimize its activity in the reaction. The researchers found that a rough cobalt surface derived from oxidation worked best to create a reaction that was selective, meaning it converted nearly all the nitrate molecules to ammonia. <\/p>\n\n\n\n

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