Enhancement of nano titanium dioxide coatings by fullerene and polyhydroxy fullerene in the photocatalytic degradation of the herbicide mesotrione

Abstract

The surface modification of commercial TiO₂ Hombikat (TiO₂) using nanoparticles of fullerene C₆₀ with tetrahydrofuran (THF-nC₆₀), as well as fullerenol C₆₀(OH)₂₄ nanoparticles (FNP) was investigated in this study. Characterization of THF-nC₆₀, FNP, TiO₂, TiO₂/THF-nC₆₀, and TiO₂/FNP was studied by using DES, ELS, TEM, SEM, DRS and BET measurements and their photoactivity has been examined on the mesotrione degradation under simulated sunlight. It was found that FNP in self-assembled nanocomposite TiO₂/FNP increased negatively charge, as well as catalytic surface of TiO₂. In addition, TiO₂/FNP exhibits a shift of band gap energy to lower values compared to TiO₂ and TiO₂/THF-nC₆₀. BET surface area has not showed significant differences among catalysts. Furthermore, it was found that the highest photoactivity was obtained for TiO₂/FNP system. Besides, influence of different concentrations of electron acceptors (H₂O₂ and KBrO₃), as well as scavengers on the kinetics of mesotrione removal in aqueous solution with/without TiO₂ and FNP under simulated sunlight was investigated. Namely, addition of mentioned electron acceptors has resulted in higher mesotrione degradation efficiency compared to O₂ alone. Besides, in the first period substrate degradation probably takes place via hydroxyl radicals and after 60 min of irradiation the reaction mechanism proceeds mainly via holes. The most efficient system for mesotrione degradation and mineralization were TiO₂/7 mM KBrO₃ and TiO₂/7 mM KBrO₃/40 μl FNP, respectively.

Keywords: Characterization; Electron acceptors; Photocatalysis; Scavengers; TiO(2)/FNP; TiO(2)/THF-nC(60).