More Than a Love Gesture: Roses Inspire Water Purification System

Most people think of roses as something you give someone as a romantic gesture, but they may also have some energy-saving value. Researchers at the University Of Texas (UT) at Austin say a new device for collecting and purifying water was inspired by a rose and significant improves on current water recovery techniques. The flower-like structure costs less than 2 cents and can produce more than half a gallon of water per hour per square meter.

The research team, led by Donglei (Emma) Fan, associate professor in UT at Austin’s Cockrell School of Engineering’s Walker Department of Mechanical Engineering, developed the origami rose-inspired approach to solar steaming for water production, using solar energy to separate salt and other impurities from water through evaporation. In a paper published in the journal Advanced Materials, the authors explain development of the solar-steaming system made from layered, black paper sheets shaped into petals. The system is attached to a stem-like tube that effectively collects and retains untreated water from any water source.

Unlike current solar-steaming technologies that are costly, bulky, and produce limited results, the research team’s method uses inexpensive, portable, and lightweight materials that happen to look just like a black-petaled rose in a glass jar.

“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 says.

Polypyrrole is a material known for its photothermal properties. Its strength is converting solar light into thermal heat.

Fan says the flower idea was inspired by a book she read in high school called The Black Tulip by Alexandre Dumas. She found the rose ideal because its structure allowed more direct sunlight to hit the photothermic material—with more internal reflections— than other floral shapes and enlarged the surface area for water vapor 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 rain drops coming from above. Water flows to the petals where the polypyrrole material coating the flower turns the water into steam. Impurities naturally separate from water when condensed in this way.

“We designed the purification-collection unisystem to include a connection point for a low-pressure pump to help condense the water more effectively,” says Weigu Li, a Ph.D. candidate in Fan’s lab and lead author on the paper. “Once it is condensed, the glass jar is designed to be compact, sturdy and secure for storing clean water.”

The device removes any contamination from heavy metals and bacteria, and it removes salt from seawater, producing clean water that meets drinking standard requirements set by the World Health Organization.

“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,” says Li. “This could inspire new paradigms of solar-steaming technologies in clean water production for individuals and homes.”