Rodney Priestley and Xiaohui Xu: Solar-driven system for water purification

Aug. 30, 2022

A temperature-sensitive gel harnesses the sun to provide fast and inexpensive clean drinking water.

Rodney Priestley and Xiaohui Xu

Rodney Priestley, Dean of the Graduate School, and Xiaohui Xu, Postdoctoral Research Associate

Most solar-powered approaches to water filtration use sunlight to evaporate water, which is a time consuming process. Other water filtration methods require electricity or another source of power to pump water through a membrane. Passive filtration via gravity, as with typical household countertop filters, requires regular replacement of filters.

Now, researchers have developed a water purification device that uses sunlight, but does not require waiting for the water to evaporate, condense and evaporate again.

At the heart of the new device is a gel that changes depending on temperature. At room temperature, the gel can act as a sponge, soaking up water. When heated to 33 degrees Celsius (91 degrees Fahrenheit), the gel does the opposite and pushes the water out of its pores.

The gel resists absorption of contaminants in the water, leaving the user with clean, filtered water. This filter delivers the highest passive solar water-purification rate of any competing technology.

The device can operate off-grid at large and small scales. One way to use the gel would be to place it in a water source in the evening and the next day place it in the sunlight to generate the day’s drinking water. The technology has the potential to work anywhere to provide low-cost, non-powered water purification.

“Sunlight is free, and the materials to make this device are low-cost and non-toxic, so this is a cost-effective and environmentally friendly way to generate pure water.” — Xiaohui Xu


Sujit Datta, Assistant Professor of Chemical and Biological Engineering; Z. Jason Ren, Professor of Civil and Environmental Engineering and the Andlinger Center for Energy and the Environment; Howard Stone, Donald R. Dixon '69 and Elizabeth W. Dixon Professor of Mechanical and Aerospace Engineering

Team members:
Graduate student Nehemie Guillomaitre; Associate Research Scholar Navid Bizmark

Development status:
Patents pending. Startup company AquaPao Inc. is developing this technology.

Princeton University: Intellectual Property Accelerator Fund, Princeton Presidential Postdoctoral Fellowship. External funding by the New Jersey Health Foundation.

Learn more:
[email protected]

Licensing contact:
Prabhpreet Gill
Technology Licensing Associate
[email protected]