Michael Wong
Rice University chemical engineers improve their design for a light-powered catalyst that rapidly breaks down PFOA, one of the world’s most problematic “forever chemical” pollutants, according to the university. Michael Wong and his students reportedly made the surprising discovery in 2020 that boron nitride, a commercially available powder that’s commonly used in cosmetics, could destroy 99% of PFOA, or perfluorooctanoic acid, in water samples within just a few hours when it was exposed to ultraviolet light with a wavelength of 254 nanometers.
“That was great because PFOA is an increasingly problematic pollutant that’s really hard to destroy,” says Wong, corresponding author of a study about the redesigned catalyst in Chemical Engineering Journal, in a press release from the university. “But it was also less than ideal because the boron nitride was activated by short-wave UV, and the atmosphere filters out almost all of the short-wave UV from sunlight. We wanted to push as much as possible boron nitride’s ability to access energy from other wavelengths of sunlight.”
Wong and study co-lead authors Bo Wang, Lijie Duan and Kimberly Heck created a composite of boron nitride and titanium dioxide that married the best features of the individual catalysts. In their new study, they showed the UV-A powered composites destroyed PFOA about 15 times faster than plain titanium dioxide photocatalysts.
By analyzing photocurrent response measurements and other data, Wong’s team learned how its semiconductor composite harvested UV-A energy to break apart PFOA molecules in water. In outdoor experiments using plastic water bottles under natural sunlight, they found the boron nitride-titanium dioxide composites could degrade about 99% of PFOA in deionized water in less than three hours. In salty water, that process took about nine hours.
He said the boron nitride and composite catalyst technologies have already attracted attention from several industrial partners in the Rice-based Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment (NEWT), which is funded by the National Science Foundation to develop off-grid water treatment systems.
Read the press release at www.rice.edu