In 2011, Kiel University researchers began studying CAU-10-H for water harvesting, a project that lasted over a decade. 15 years later, they produced 66 pounds of the material, opening a path to harvest freshwater from air as dry as 18% humidity

As water stress grows in regions affected by higher temperatures and declining rainfall, researchers are exploring ways to obtain freshwater from sources that have traditionally been difficult to use. One promising approach is atmospheric water harvesting, which extracts moisture directly from the air.

Researchers at Kiel University in Germany have spent years developing a porous material called CAU-10-H, which can capture water vapour even when the surrounding air is relatively dry. After years of research and development, the team has currently produced the material on a much larger scale, creating fresh possibilities for testing the technology outside the laboratory.

A More Than Decade-Long Research Project

The work on CAU-10-H began in 2011, when researchers at Kiel University started investigating the material for water harvesting. The project continued for over a decade as scientists analyzed how the material could capture and release moisture.


Almost 15 years after the research began, the team has reached a production milestone of about 66 pounds of the material, equivalent to around 30 kilograms.

The larger quantity offered researchers an opportunity to move beyond small laboratory experiments and investigate how the technology could perform under practical conditions.

How CAU-10-H Captures Water From Air

CAU-10-H belongs to a family of materials called Metal-Organic Frameworks, or MOFs.

These materials have extremely small spaces that allow them to interact with molecules in their surroundings. In the case of CAU-10-H, the structure can capture water molecules from humid air and subsequently release them when heated.

The material is especially interesting because it can begin collecting moisture at room temperature when relative humidity is as low as 18%.

That feature could make it useful in environments where conventional atmospheric water-harvesting methods struggle as there is not enough moisture in the air.

Relatively Low Heat Can Release the Water

Capturing moisture is only one part of atmospheric water harvesting. The collected water must also be released from the material so it can be gathered.

Researchers discovered that CAU-10-H can release its captured water when heated to approximately 70°C.

This requirement could possibly be met using solar heat or waste heat, reducing the requirement for extra energy sources. The possibility of using heat that would otherwise be wasted could be especially relevant for applications associated with industrial facilities or other sources of excess heat.

How Much Water Can the Material Capture?

Under dry conditions, CAU-10-H can capture as much as 0.17 grams of water for every gram of material.

Researchers estimate that a composite based on the material could possibly produce approximately 1.8 litres of water per kilogram of material each day.

These figures offer an indication of the material's potential, although the researchers still need to analyze how the technology performs in real-world environments rather than only under controlled research conditions.

Potential Applications in Water-Stressed Regions

The research team is exploring whether the technology could eventually contribute to freshwater production in regions facing increasing water shortages.

Regions such as the Mediterranean are of specific interest because rising temperatures and declining rainfall are increasing pressure on available water resources.

Rather than depending exclusively on conventional freshwater sources, atmospheric water harvesting offers a different possibility: collecting small amounts of moisture that are already present in the air.

CAU-10-H's ability to function at relatively low humidity levels is therefore a significant feature of the research.

Production Has Been Scaled Up

One of the significant developments in the project is the increase in production volume.

Researchers have now produced approximately 30 kilograms of CAU-10-H, around 60 times more material than earlier laboratory batches.

Producing a substantially larger quantity is important as technologies designed for practical applications must eventually illustrate that they can be manufactured and operated beyond small-scale experiments.

The researchers' next step is to test the technology under real-world conditions.

A Potential New Way to Access Freshwater

The development of CAU-10-H demonstrates how advanced porous materials could offer new approaches to water collection. Instead of extracting freshwater from conventional sources, the material is designed to capture water molecules already present in the atmosphere.

Its ability to collect moisture at 18% relative humidity, combined with the possibility of releasing that water at almost 70°C, makes it particularly interesting for dry environments where solar or waste heat may be available.

After beginning their investigation in 2011, the Kiel University researchers have now reached a stage where significantly larger quantities of the material can be produced. The next phase, testing CAU-10-H in real-world conditions will help determine how effectively this laboratory-developed technology can perform outside controlled research settings.

Source: AsiaOne

FAQs

Q1. What is CAU-10-H?

CAU-10-H is a porous material being studied for atmospheric water harvesting. It can capture water vapour from the surrounding air.

Q2. Who developed the material?

Researchers at Kiel University in Germany have been studying CAU-10-H. The research has continued for more than a decade.