MIT
Engineers from the Massachusetts Institute of Technology (MIT) in the United States have created a device that can collect drinking water from the air anywhere, even in the desert.
About 2.2 billion people in the world currently lack access to safe drinking water. In the United States, more than 46 million people suffer from a lack of drinking water, lack of water pipes, or poor quality water supplies. To solve this problem, MIT researchers have begun to explore the possibility of obtaining drinking water from the air, as the atmosphere contains trillions of liters of water in the form of vapor. The ability to efficiently capture and condense this vapor will provide clean drinking water to areas that do not have traditional sources.
MIT has created innovative device, which efficiently captures water vapor and produces drinking water under various humidity conditions, including extremely arid desert air. The device looks like a black vertical panel about the size of a window and consists of a water-absorbing hydrogel placed in a glass chamber covered with a cooling material.
The hydrogel in the form of a black the bubble film, has small dome-shaped cells that swell to absorb water vapor. The steam condenses on the glass surface and flows through the tube as pure drinking water. Unlike similar devices powered by batteries or solar panels, this device is able to work completely autonomously.
Developers tested it in a desert climate Death Valley in California, where they spent more than a week. Even in extremely low humidity conditions, the device produced 160 milliliters of drinking water per day.
According to MIT researchers, several vertical panels installed together could provide drinking water for an entire household, even in arid desert conditions. At the same time, water production should increase as humidity increases.
«We have created a meter-scale device that we hope to use in regions with limited resources, where even solar panels are not very accessible. This is a test of the scalability of this water harvesting technology. Now people can build it even bigger or combine it into parallel panels to provide people with drinking water and achieve a real effect», — says Professor of Mechanical and Civil Engineering and Environmental Protection at MIT Xuanhe Zhao.
Researchers from MIT, led by Professor Xuanhe Zhao, has long been researching hydrogels — soft porous materials mainly composed of water and a microscopic lace of interconnected polymeric fibers. Scientists have studied the use of hydrogels in biomedical applications, including adhesive coatings for implants, soft, flexible electrodes, and non-invasive stickers for biomedical imaging.
Among the most effective devices for collecting drinking water from the air at present are developments made of metal-organic frames or super-porous materials that capture water vapor even from arid desert air. The new drinking water collection device avoids a number of problems that arise when using similar designs.
Similar projects the first designs included structures made of micro- and nano-porous hydrogels, but the water obtained with their help remained salty and additional filtration was required. Salt is a natural absorbent, and researchers embed salts — usually lithium chloride — into hydrogels to increase the material’s water absorption. The downside, however, is that this salt can leak out with the water when it is eventually collected.
The new device by MIT engineers significantly limits salt leakage. In addition, glycerin was added to the hydrogel, which naturally stabilizes the salt, keeping it inside the hydrogel. The hydrogel itself has a microstructure that lacks nanoscale pores, which further prevents salt from leaving the material. The salt level in the collected water was below the standard threshold for safe drinking water and significantly lower than the levels produced by many other hydrogel-based designs.
In addition, the scientists improved the shape of the hydrogel itself. Instead of keeping it in the form of a flat sheet, they formed it in the form of a pattern of small dome-shaped structures that resembled bubble film, increasing the surface area of the hydrogel and, accordingly, the amount of water vapor it can absorb.
The researchers made a half-square hydrogel and enclosed the material in a glass chamber similar to a window. They coated the outside of the chamber with a special polymer film that helps cool the glass and stimulates the evaporation and condensation of water vapor in the hydrogel on the glass. They installed a simple system of tubes to collect the water running down the glass.
In November 2023, the researchers traveled to Death Valley to install their device. During the week, they took measurements while the hydrogel sucked the vapor out of the air at night. During the day, with the help of the sun, the collected water evaporated from the hydrogel and condensed on the glass.
During the week, the device operated in humidity conditions from 21 to 88%, producing 57 to 161.5 milliliters of drinking water per day. Even in the driest conditions, the device collected more water than other passive and some active structures.
«This is just a concept, and there are many things we can optimize. For example, we may have a multi-panel project. And we are working on the next generation of the material to further improve its internal properties. We imagine that one day you could deploy an array of such panels, and the area they occupy would be very small, since they are all vertical. Then you could have many panels together, collecting water all the time, on a household scale», — Xuanhe Zhao emphasizes.
The results of the study are published in the journal Nature
Source: SciTechDaily