A catalyst that destroys the perchlorate in water could clean the Martian soil.
A team led by engineers at the University of California Riverside has developed a catalyst to remove a dangerous chemical from water on Earth that could also make Martian soil safer for agriculture and help produce oxygen. for human Martian explorers.
Perchlorate, a negative ion made up of one chlorine atom bonded to four oxygen atoms, occurs naturally in some soils on Earth and is especially abundant in Martian soil. As a strong oxidizing agent, perchlorate is also made and used in solid rocket fuel, fireworks, ammunition, vehicle airbag igniters, matches, and flares. It is a by-product of certain disinfectants and herbicides.
Due to its ubiquity in soils and manufactured products, perchlorate is a pollution of running water that causes certain thyroid diseases. Perchlorate accumulates in plant tissue, and a large amount of perchlorate found in Martian soil could endanger the foods grown there and limit the potential for human settlement on Mars. Perchlorate in Martian dust could also be dangerous for explorers. Current methods of removing perchlorate from water require either harsh conditions or a multistep enzymatic process to lower the oxidation state of the element chlorine to the harmless chloride ion.
PhD students Changxu Ren and Jinyong Liu, assistant professor of chemical and environmental engineering at the Marlan and Rosemary Bourns College of Engineering at UC Riverside, took inspiration from nature to reduce perchlorate in water at ambient pressure and temperature in one single step.
Ren and Liu discovered that anaerobic microbes use molybdenum in their enzymes to reduce perchlorate and generate energy in low oxygen environments.
“Previous efforts to design a molybdenum chemical catalyst for perchlorate reduction have not been successful,” Liu said. “Many other metal catalysts require harsh conditions or are not compatible with water.”
The researchers attempted to recreate the complex microbial perchlorate reduction process using a simplified approach. They found that by simply mixing a common fertilizer called sodium molybdate, a common organic ligand called bipyridine that binds molybdenum, and a common hydrogen activating catalyst called palladium on carbon, they produced a powerful catalyst that quickly breaks down and effectively perchlorate in water. using hydrogen gas at room temperature without combustion.
“This catalyst is much more active than any other chemical catalyst known to date and reduces over 99.99% of perchlorate to chloride regardless of the initial perchlorate concentration,” Ren said.
The new catalyst reduces perchlorate over a wide range of concentrations, from less than 1 milligram per liter to 10 grams per liter. This makes it suitable for use in a variety of scenarios, including remediation of contaminated groundwater, treatment of heavily contaminated wastewater from explosives manufacturing, and the habitability of Mars.
“A practical catalytic reduction system can help extract gaseous oxygen from perchlorate that is scrubbed from Martian soil when the catalyst is coupled to other processes,” Liu said.
The article “A bioinspired molybdenum catalog for water perchlorate reduction” was published in the Journal of the American Chemical Society. Ren and Liu were involved in the research of UC Riverside doctoral student Jinyu Gao, Jacob Palmer, and high school student Eric Y. Bi. Peng Yang and Mengqiang Zhu from the University of Wyoming characterized the catalyst using X-ray absorption spectroscopy, and Jiaonan Sun and Yiying Wu from Ohio State University performed the electrochemical tests. The research was funded by the National Science Foundation.
Reference: “A Bioinspired Molybdenum Catalyst for Reduction of Aqueous Perchlorate” by Changxu Ren, Peng Yang, Jiaonan Sun, Eric Y. Bi, Jinyu Gao, Jacob Palmer, Mengqiang Zhu, Yiying Wu and Jinyong Liu, May 18, 2021, Journal of the American Chemical Society.
DOI: 10.1021 / jacs.1c00595