Aerogel Harvests Water From Thin Air

A single kilogram of this new aerogel can generate enough drinking water to meet a household’s daily needs

AsianScientist (Jan. 26, 2021) – Scientists from Singapore have devised a method to conjure water out of thin air—literally. Details of their method, which relies on a material called an aerogel, were published in the journal Science Advances.

Though water covers 70 percent of our planet, freshwater is rarer than you’d think. Only three percent of the world’s water supply is freshwater, a majority of which is frozen in glaciers and polar ice caps. With the current rates of water consumption, water scarcity is likely to get worse. By 2025, two-thirds of the world’s population—or around four billion people—are expected to face regular water shortages.

Given the urgent need for clean, potable water, researchers have long been searching for new freshwater sources. It turns out that the answer may lie in the air that we breathe. In fact, water within the Earth’s atmosphere can fill almost half a trillion Olympic swimming pools.

To extract water from this under-utilized source, a team led by Professor Ho Ghim Wei from the National University of Singapore created a new type of aerogel—solid materials derived from gel that weigh almost nothing. The new aerogel created by Ho’s team relies on a method called desiccant-based atmospheric water extraction.

Just like the silica gel packets found in the products we buy, the method uses liquid or solid desiccants to capture and subsequently release water from humid air. However, traditional dessicant-based methods are often slow and typically require additional condensers and evaporators. In contrast, the team’s new aerogel consists of a dessicant paired with polymers with a unique, snakelike structure that can spontaneously switch between attracting and repelling water.

Without needing a battery, the ‘smart’ aerogel autonomously gathers water molecules from the air and condenses them into a liquid it then releases as water. Under humid conditions, a single kilogram of the aerogel can produce 17 liters of water per day—enough to meet a household’s daily water requirement. Meanwhile, during sunny conditions, the aerogel can transition into a structure that favors water release.

According to the authors, the aerogel transforms 95 percent of the water vapor it absorbs into water, with the aerogel even capable of producing water non-stop for several months. When the resulting water was tested by the researchers, they found that it met the World Health Organization’s standards for drinking water.

Moving forward, Ho and her colleagues are looking for industry partners to scale up the aerogel’s production for domestic or industrial use. Someday, their smart aerogel may even be used in survival kits for long-haul expeditions or endurance sports.

“Given that atmospheric water is continuously replenished by the global hydrological cycle, our invention offers a promising solution for achieving sustainable freshwater production in a variety of climatic conditions, at minimal energy cost,” said Ho.

The article can be found at: Yilmaz et al. (2020) Autonomous atmospheric water seeping MOF matrix.


Source: National University of Singapore; Photo: National University of Singapore.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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