Water, Vol. 17, Pages 1708: Degradation of 1,4-Dioxane by Au/TiO2 Janus Nanoparticles Under Ultraviolet Light: Experiments and Modeling
Water doi: 10.3390/w17111708
Authors:
Yangyuan Ji
Matthew J. Tao
Lamar O. Mair
Amit Kumar Singh
Yuhang Fang
Sathish Rajendran
Thomas E. Beechem
David M. Warsinger
Jeffrey L. Moran
Advanced oxidation processes (AOPs) show significant promise to degrade recalcitrant water contaminants, such as 1,4-dioxane, but slow degradation kinetics limit the energy efficiency of this technology. We realized substantial enhancements in the degradation of 1,4-dioxane (a suspected carcinogen) using gold-coated titanium dioxide (Au/TiO2) Janus nanoparticles (JNPs) irradiated with above-bandgap ultraviolet (UV) light (peak wavelength, 254 nm). To explain this result, we combined experimental measurements quantifying 1,4-dioxane degradation at varying UV wavelengths with finite-element simulations that provided explanatory insight into the light–matter interactions at play. The enhanced photocatalytic activity at the optimal condition (254 nm light, high intensity, Au/TiO2) resulted from a larger quantity of photogenerated holes in the TiO2 capable of reacting with water to form hydroxyl radicals that degrade 1,4-dioxane. This increased production of holes resulted from two sources: (1) more viable electron–hole pairs were created under 254 nm light owing to increased light absorption by the TiO2 that was localized near the surface; (2) the metal sequestered photogenerated electrons from the TiO2, which prevented electron–hole pairs from recombining, leaving more holes available to react with water. Our results motivate the exploration of different metal coatings (especially non-precious metals) and suggest a path toward broader implementation of TiO2-based photocatalytic AOPs, which can effectively remove many water pollutants that survive conventional treatment techniques.
Source link
Yangyuan Ji www.mdpi.com