Carbon dioxide in the atmosphere dissolves in oceans, lakes and ponds, forming bicarbonate ions and other compounds that alter aquatic chemistry and can have harmful effects on aquatic organisms. In addition, bicarbonate can later re-enter the atmosphere as carbon dioxide, contributing to climate change. Researchers are now developing small “nanojars” that break down bicarbonate into carbonates and capture them, as well as certain toxic anions. This may remove the ions and reuse them.
Researchers will present their results today at the American Chemical Society (ACS) Autumn Conference.
“We originally developed nanojars to extract harmful negatively charged ions such as chromate and arsenate from water,” said Dr. Gelert Mezei, who is presenting his research at the conference. increase. “But they also found to bind strongly to carbonates.” He said that the carbonates or other ions captured in the nanojar could be discarded later or recycled into useful products. say.
Nanojars are small containers made up of multiple repeating units of copper ions, pyrazole groups, and hydroxides. Jar is formed only in the presence of ions with a -2 charge, such as chromate, arsenate, phosphate, carbonate.When the appropriate ingredients are added to Organic solvent, Repeat units are formed and assembled into nanojars, with -2 charged anions firmly bonded in the center.
To remove anions from the water, researchers added a solvent containing nanojar components. Organic layer On the water. “Solvents are immiscible with water, but anions from water can enter this organic layer,” explains Mezei of Western Michigan University. “Then, nanojars are formed to wrap the ions and confine them in the organic phase.” The aqueous and organic layers are immiscible and easy to separate. Treating the organic layer with a weak acid breaks the nanojars apart, releasing anions that are discarded or recycled.
Researchers have used nanojars to remove toxic anions from water. “We have shown that chromate and arsenate can be extracted below the drinking water levels permitted by the US Environmental Protection Agency, which is actually very low,” says Mezei. Nanojars have an even higher affinity for carbonates, and adding a molecule called 1,10-phenanthroline to the mixture produces nanojars that combine two carbonate ions instead of one.
The team also created nanojars that are selective for specific anions. “The original pyrazole building block creates nanojars that are completely selective for the -2 charged ions, but these ions are indistinguishable,” says Mezei. Researchers have created nanojars that preferentially bind to carbonate by using two pyrazoles linked by an ethylene linker as components. Recently, they have shown that the use of two pyrazoles with a propylene linker produces sulfate-selective nanojars.They are Anion-Selective nanojars are important for applications where only certain –2 charged ions need to be removed.
Researchers have also worked to make the process more suitable for real-world applications. For example, they exchanged the weak base trioctylamine for a strong base. Sodium hydroxide, Originally used to make nano jars. “Unlike sodium hydroxide, trioctylamine is soluble in the organic phase, making nanojar formation much more efficient,” says Mezei. Interestingly, trioctylamines form nanojars with slightly different structures. This is what he calls a “capped” nanojar, but it looks like it’s bound as tightly as carbonate.
So far, all experiments have been carried out on a laboratory scale. Developing a system that treats large amounts of water, such as lakes, requires collaboration with engineers, says Mesey. However, he believes that contaminated lake water could be pumped to the station for treatment and then returned to the lake. Some ions, such as phosphate, can be recycled for useful purposes such as fertilizer. Carbonates can be recycled to make “green” solvents. Carbonate Ester for the nanojar extraction itself. “Whether this process to remove carbon dioxide from water -And indirectly, the atmosphere-will compete with other technologies I don’t know yet. There are many aspects to consider, it’s a tricky business, “says Mesey.
For more information:
Atmospheric CO2 Isolation by combining one or two COs32- The ion in the nanojar, ACS, is in the fall of 2021.
American Chemical Society
Quote: “Nanojars” captures dissolved carbon dioxide, toxic ions from water (2021, August 25). Obtained from https: //phys.org/news/2021-08-nanojars-capture-dissolved-carbon-dioxide.html on August 25, 2021.
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“Nanojar” captures dissolved carbon dioxide and toxic ions from water
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