Researchers use a metal-organic framework to capture more water from the air.

Water can be accessed in creative ways, including by being created out of thin air by chemists and engineers. Recently, researchers from the University of Chicago discovered a method to extract even more water.

2021 marks Prof. A multi-institutional team that was creating a new method to draw water out of the air included Laura Gagliardi from the Chemistry Department and the Pritzker School of Molecular Engineering. A metal-organic framework, a specially created substance with a hybrid structure made of metal ions and organic linkers that can be adjusted at the molecular level, was the main technological advancement.

MOFs have an arrangement of void pores that allows them to absorb airborne water molecules. To comprehend the behavior of the material at the atomic level, Gagliardi and her team used theoretical and computational techniques.

“It is a true breakthrough because it demonstrates how theory, modeling, and prediction can lead new experiments and new technology.”

Prof. Laura Gagliardi of the Pritzker School of Molecular Engineering and the Department of Chemistry .

Gagliardi’s team has now assisted in the design of an improved MOF that can absorb 50% more water from the air than its predecessor. In the end, the components will be used to create a device that will showcase this potentially revolutionary technology.

It is a real breakthrough, according to Gagliardi. “It demonstrates that theory, modeling, and prediction can serve as a guide for new experiments and new technologies.” ACS Central Science published the research.

Although the original MOF functioned well, the team sought to enhance it by expanding the material’s pore volume while maintaining a comparable level of water binding strength. Tiny aluminum-based rods are the building blocks of the MOF framework, and “linker” molecules connect them. By alternating hydrophilic and hydrophobic pockets, this structure produces pores that are lined with water.

These pockets are perfectly suited for the initial binding of water, as water molecules will naturally bind to the MOF when it is exposed to air. The subsequent molecules attach to the initial water molecules once they have been bound by the first water molecules.

A water-filled “sponge” is the end result. But while preserving the unique environment required to draw the initial water molecules, the researchers wanted to increase the pore volume (which would free up more space for more water to be extracted from the air). The design team also needed to find the ideal balance between water binding to the MOF and its ability to be desorbed (squeezed out of the sponge).

Gagliardi’s team used computer simulations to arrive at the solution: incorporating a special linker extension, which is essentially a long arm on the structure made of two carbon atoms, would increase the pore size while preserving the unique water-binding properties the MOF originally had.

To make sure the substance could be synthesized affordably, they worked with Berkeley experimenters at the University of California. The group, which also consists of scientists from the University of Minnesota, General Electric, and Berlin’s Humboldt University, is currently scaling up the production of this new MOF and incorporating it into their prototype water-collection device. It could collect significantly more water than before if it performs as well in the device as it does in the lab.

Gagliardi remarked that “it was a true collaboration of discussions, modeling, and experiments.”

The team is now thinking about making additional changes to the design and integrating machine learning, which can sort through the data they’ve gathered through their modeling and experiments to offer fresh suggestions for improvement. In the end, the tool might be employed to aid civilians in water-scarce areas or combatants in arid terrain.

“Hopefully, these advancements will help people capture water in arid climates,” she said.

More information: Nikita Hanikel et al, MOF Linker Extension Strategy for Enhanced Atmospheric Water Harvesting, ACS Central Science (2023). DOI: 10.1021/acscentsci.3c00018

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