Porous material could pull 1.8 liters of drinking water daily from dry air - Energy & Green Tech - Hi Tech & Innovation

Using a model, Kalle Mertin demonstrates the porous structure of CAU-10-H. His arm passing through the model illustrates the material's continuous, tube-like pores, where water molecules are adsorbed and released. Credit: Christina Anders, Uni Kiel

Researchers in chemistry and materials science at Kiel University are working with partners to develop new water sources for the Mediterranean region. "Regions like these are facing rising temperatures and declining rainfall. Our goal is to develop an environmentally friendly technology that converts water molecules from the air into drinking water," says Professor Norbert Stock from CAU's Institute of Inorganic Chemistry.

"Two new studies, published in the Journal of Materials Chemistry A and Industrial & Engineering Chemistry Research, describe how large quantities of the material can be produced and the efficiency of cooling devices can be improved."

The studies also show a new approach that enables the team to make water from the air available more efficiently and quickly than previous systems.

A sponge-like material with a high-tech structure

Materials belonging to the class of metal-organic frameworks (MOFs) behave much like a sponge: They can adsorb large amounts of water within a short time and release it again just as quickly. This is made possible by their extremely porous structure, which contains countless interconnected microscopic cavities. The 2025 Nobel Prize in Chemistry was awarded for fundamental research behind these materials.

Electrically conductive MOF–carbon foam composites for atmospheric water harvesting that can be regenerated by Joule heating or sunlight. Credit: Journal of Materials Chemistry A (2026). DOI: 10.1039/d6ta00544f

In Kiel, Stock's team is optimizing the synthesis of the MOF "CAU-10-H" specifically for water adsorption and heat transformation. The material is named after the place of discovery at Kiel University, its material number and the chemical symbol for hydrogen.

CAU-10-H captures water molecules within its porous structure at room temperature and relative humidity values of ≥18% and releases them again at around 70°C (158°F). By combining the material with conductive carbon structures, the researchers can accelerate this process even further.

The resulting composite material can be heated efficiently using electricity or sunlight. As a result, it releases the adsorbed water particularly quickly and operates in short, repeatable cycles.

Under dry conditions, the system continuously produces drinking water from the air and achieves a water uptake of up to 0.17 grams of water per gram of material. The cycles take only a few hours, enabling efficient, continuous operation. Under these conditions, 1 kilogram (2.2 pounds) of the composite material can potentially produce up to 1.8 liters (0.5 gallons) of water from the air per day.

"This makes the material particularly attractive for producing drinking water, even in arid regions," says first author Lasse Wegner.

At the same time, CAU-10-H also shows considerable potential for cooling applications. In adsorption cooling systems, it delivers up to three times the cooling performance of silica gel, a widely used desiccant based on silicon dioxide.

In the future, such systems could make use of waste heat, for example from data centers or bakeries. This significantly reduces the energy consumption of air conditioning systems compared with established technology and makes cooling more sustainable.

From the lab to industrial production

"We discovered CAU-10-H around 15 years ago, and since then its potential applications have been investigated around the world," says Stock, who has been conducting research on MOFs for more than two decades.

The team has now successfully transferred production to pilot scale—the intermediate step between laboratory research and industrial manufacturing. Led by Kalle Mertin, the researchers produced around 30 kilograms (66 pounds) of the material, approximately 60 times more than had previously been manufactured in the laboratory.

At the same time, they further optimized the production process based on a techno-economic analysis to demonstrate that manufacturing costs of $12 to $14 per kilogram are achievable.

"This brings practical applications of our materials within reach," says Stock. "We have shown that they not only work in the laboratory but can also be produced on an economically viable scale." 

Provided by Kiel University 

by Kiel University

edited by Sadie Harley, reviewed by Andrew Zinin 

Source: Porous material could pull 1.8 liters of drinking water daily from dry air