A nanofibre device could help drought-hit communities capture clean drinking water from thin air.
Driven by the scarcity of supply, climate change and ground watershed depletion, scientists on Tuesday will present a design for a first of its kind portable harvester that mines freshwater from the atmosphere.
One of the simplest, yet vital resources on our planet is at the center of Dr. Shing-Chung “Josh” Wong’s latest research, which aims at helping populations in dry, arid parts of California, Africa and China.
For thousands of years, people in the Middle East and South America have extracted water from the air to help sustain their populations. Researchers and students from the University of Akron drew inspiration from those examples to develop a lightweight, battery-powered freshwater harvester that could someday take as much as 10 gallons per hour from the air, even in arid locations.
“I was visiting China, which has a freshwater scarcity problem. There’s investment in wastewater treatment, but I thought that effort alone was inadequate,” University of Akron professor Shing-Chung (Josh) Wong said.
Instead of relying on treated wastewater, Wong explained, it might be more prudent to develop a new type of water harvester that takes advantage of abundant water particles in the atmosphere.
Freshwater makes up less than 3 percent of the earth’s water sources, and three quarters of that is locked up as ice in the north and south poles. Most water sustainability research is directed toward water supply, purification, wastewater treatment and desalination. Little attention has been paid to water harvesting from atmospheric particles.
A mockup of the water harvester, which could be a wearable backpack - Courtesy of Dr. Josh Wong/ University of Akron
Harvesting water from the air has a long history. Thousands of years ago, the Incas of the Andean region collected dew and channeled it into cisterns. More recently, some research groups have been developing massive mist and fog catchers in the Andean mountains and in Africa.
Wong’s harvester is directed towards the most abundant atmospheric water sources and uses ground-breaking nanotechnology. If successful, it will produce an agile, lightweight, portable, freshwater harvester powered by a lithium-ion battery.
The bio-inspired approach uses a novel bead-on-string nanofiber that can be used as a high-performance water harvester. In their talk, Wong and his students will introduce their portable harvester design and report on its durability and efficiency of using electrospun polymer membranes to condensate moisture content in air into drinkable water.
Electrospinning uses electrical forces to produce polymer fibers ranging from tens of nanometers up to one micrometer. These nanoscale fiber polymers are an ideal size to condense and squeeze water droplets out of the air because they offer an incredibly high surface-area-to-volume ratio, much larger than the typical structures and membranes used in water distillers.
African beetles beat the heat in the Sahara desert by pulling water from the air - BBC wildlife
By experimenting with different combinations of polymers that attract and discharge water, Wong’s group concluded that a water harvesting system could indeed be fabricated using nanofiber technology. Their polymer membrane could harvest 91 percent more than similarly designed membranes without these nanofibers.
Unlike existing methods, Wong’s harvester could work in arid desert environments because of the membrane’s high surface-area-to-volume ratio. It also would require minimal energy.
Wong says that harvesters made with these nanofibres could yield up to 180 litres of water per square metre every day.
“We could confidently say that, with recent advances in lithium-ion batteries, we could eventually develop a smaller, backpack-sized device,” Wong said.
What’s more, Wong’s nanofiber design simultaneously grabs water and filters it. The electrospun fiber network can act as an anti-fouling surface, sloughing off microbes that collect on the harvester’s surface. So the water would be “clear and free of pollutants” and immediately drinkable once it’s collected, according to Wong.
Wong hopes to obtain additional funding to build a prototype of the freshwater harvester. He anticipates that once his team is able to produce the prototype, it will be inexpensive to manufacture.
The researchers will present their results today at the 256th National Meeting & Exposition of the American Chemical Society (ACS).