#boron nitride Came across an article based on a studies by...

#boron nitride

Came across an article based on a studies by chemical engineers at Rice University. A composite ofboron nitride and titanium dioxide, the same type of boron nitride often used in cosmetics, can destroy 99% of PFOA in water over a few hours when exposed to UV.

JULY 25, 2022 https://phys.org/news/2022-07-catalyst-chemicals-sunlight.html
Researchers improve catalyst that destroys 'forever chemicals' with sunlight

Rice University chemical engineers have improved their design for a light-powered catalyst that rapidly breaks down PFOA, one of the world's most problematic "forever chemical" pollutants.

Michael Wong and his students 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," said Wong, corresponding author of a study about the redesigned catalyst in Chemical Engineering Journal. "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."

Long-wave UV, or UV-A, has wavelengths ranging from about 315-400 nanometers. It's what causes suntans and sunburns, and it's plentiful in sunlight that reaches Earth. Boron nitride is a semiconductor, and it isn't activated by UV-A. Titanium dioxide, a common ingredient in sunscreen, is a semiconductor that is activated by UV-A, and it had even been shown to catalyze the breakdown of PFOA, albeit very slowly, when exposed to UV-A.

So Wong and study co-lead authors Bo Wang, Lijie Duan and Kimberly Heck decided to create 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.