New water treatment technology developed by engineers may also help Mars Explorer

Destruction of perchlorate catalysts in water to clean Martian soil.

Monday, 21st June 2021

A team led by engineers from the University of California, Riverside have developed a catalyst that can remove a dangerous chemical from the earth's water. This chemical can also make Martian soil safer for agriculture and help human explorers produce oxygen.

Perchlorate, a negative ion formed by the combination of one chlorine atom and four oxygen atoms, naturally exists in some soils on the earth and is particularly abundant in Martian soil. As a strong oxidant, perchlorate is also manufactured and used in solid rocket fuel, fireworks, ammunition, automobile airbag initiators, matches, and signal flares. It is a by-product of some disinfectants and herbicides.

Because it is ubiquitous in soil and industrial products, perchlorate is a common water pollutant that can cause certain thyroid diseases. Perchlorate bioaccumulates in plant tissues, and a large amount of perchlorate found in Martian soil will make the food grown there unsafe for consumption, limiting the possibility of human settlement on Mars. The perchlorate in Martian dust can also be harmful to explorers. Current methods for removing perchlorate from water require stringent conditions or a multi-step enzymatic process to reduce the oxidation state of chlorine to harmless chloride ions.

Ph.D. student Ren Changxu and Liu Jinyong, assistant professor of chemistry and environmental engineering at the Malan and Rosemary Burns School of Engineering, University of California, Riverside, were inspired by nature to reduce perchlorate in water through a simple step to atmospheric pressure. And temperature.

Ren and Liu pointed out that anaerobic microorganisms use molybdenum in their enzymes to reduce perchlorate and harvest energy in an oxygen-deficient environment.

"Previous efforts to construct molybdenum chemical catalysts to reduce perchlorate have not been successful," Liu said. "Many other metal catalysts require harsh conditions or are incompatible with water." The researchers tried to use a simplified method to simulate the complex microbial perchlorate reduction process. They found that by simply mixing a common fertilizer called sodium molybdate, a common organic ligand called bipyridine to bind molybdenum, and a common hydrogen activation catalyst called carbon-supported palladium, they found A powerful catalyst that can decompose perchlorate in water under very high conditions. Fast and effective. Use hydrogen at room temperature without burning.

"This catalyst has a much higher activity than any other chemical catalyst reported so far. It can reduce more than 99.99% of perchlorate to chloride regardless of the initial perchlorate concentration," Ren said.

The new catalyst can reduce various concentrations of perchlorate, from less than 1 mg per liter to 10 grams per liter. This makes it suitable for a variety of scenarios, including repairing contaminated groundwater, treating heavily polluted wastewater from explosive manufacturing, and making Mars habitable.

"When the catalyst is combined with other processes, a convenient catalytic reduction system can help harvest oxygen from perchlorate washed in Martian soil," Liu said.

The article "Molybdenum biomimetic catalyst for reduction of aqueous perchlorate solution" was published in the Journal of the American Chemical Society. Ren and Liu joined the research from Ph.D. student Gao Jinyu, undergraduate student Jacob Palmer, and high school student Eric Y from the University of California at Riverside. double. Peng Yang and Mengqiang Zhu from the University of Wyoming used X-ray absorption spectroscopy to characterize the catalyst, and Jiaonan Sun and Yiying Wu from Ohio State University conducted electrochemical tests. The research was funded by the National Science Foundation.

The News Talkie Bureau

Source:

Scitechdaily.com