New water purifier inspired by a rose

Inspired by a rose, researchers at The University of Texas at Austin have developed a new device for collecting and purifying water. The device removes any contamination from heavy metals and bacteria, and removes salt from seawater, producing clean water that meets drinking standard requirements set by the World Health Organization. Each flower-like structure costs less than 2 cents and can produce more than half a gallon of water per hour per square metre.

In a paper published in the journal Advanced Materials, the authors outline how an origami rose provided the inspiration for developing a new kind of solar-steaming system made from layered, black paper sheets shaped into petals. Attached to a stem-like tube that collects untreated water from any water source, the 3D rose shape makes it easier for the structure to collect and retain more liquid.

The team, led by Associate Professor Donglei (Emma) Fan at the Cockrell School of Engineering’s Walker Department of Mechanical Engineering, developed a new approach to solar steaming for water production — a technique that uses energy from sunlight to separate salt and other impurities from water through evaporation.

The device looks like a black-petaled rose in a glass jar, and the resemblance is no coincidence.

“We were searching for more efficient ways to apply the solar-steaming technique for water production by using black filtered paper coated with a special type of polymer, known as polypyrrole,” Fan said.

Polypyrrole is a material known for its photothermal properties, meaning it’s particularly good at converting solar light into thermal heat.

The team experimented with different ways to shape the paper to achieve optimal water retention levels. Fan was inspired by a book — The Black Tulip by Alexandre Dumas — which inspired her to try a flower-like shape, and she discovered the rose to be ideal. Its structure allowed more direct sunlight to hit the photothermic material, with more internal reflections, than other floral shapes and also provided an enlarged surface area for water vapour to dissipate from the material.

The device collects water through its stem-like tube, feeding it to the flower-shaped structure on top. It can also collect raindrops coming from above. Water finds its way to the petals where the polypyrrole coating turns the water into steam. Impurities naturally separate from water when condensed.

PhD candidate and lead author Weigu Li said, “We designed the purification–collection unisystem to include a connection point for a low-pressure pump to help condense the water more effectively. Once it is condensed, the glass jar is designed to be compact, sturdy and secure for storing clean water.

“Our rational design and low-cost fabrication of 3D origami photothermal materials represents a first-of-its-kind portable low-pressure solar-steaming-collection system,” Li said. “This could inspire new paradigms of solar-steaming technologies in clean water production for individuals and homes.”

Image credit: ©stock.adobe.com/au/Nejron Photo