(453f) Synthesis and Characterization of Modified Titanium Dioxide Materials

Modified titanium dioxide (TiO₂) materials were synthesized in an attempt to improve the photocatalytic efficiency and cost effectiveness for application in water treatment processes. Nitrogen doping of titanium dioxide (TiON) extends the absorption band of the photocatalyst into the visible region which may render it a visible-light activated catalyst. Nitrogen doped materials were synthesized via published sol gel methods using various nitrogen doping agents. Ammonia and phenyl hydrazine proved to be the best N-doping agents and resulted in the formation of pale yellow TiON solids (TiON-1,2,3 and 4) that were stable during calcining. Enhancement of the photocatalyst surface area has been attempted by embedding TiO₂ and TiON crystals into mesoporous silicates. The final products of these procedures were characterized using a number of techniques (e.g. XRD, DRIFTS, etc) and tested for their stability (permanence of color). XRD showed more prominent Rutile peaks were in TiO₂ than the nitrogen enhanced materials. Promising materials were tested for their ability to promote the degradation of the target aquatic pollutants, trichlorophenol (TCP) and sulfamethoxazole (SMX). The TiON materials exhibited a range of reactivities toward SMX and TCP. Of note, TiON-4 facilitated the largest degradations. For TiON-2, 3, and 4, TCP degraded to a greater extent than SMX. Sorption isotherms show that TCP interacts with the surface of TiO₂, while SMX shows insignificant sorption. Taken together, these results suggest that interaction with the TiON surface, possibly through the formation of a surface complex, promotes degradation. Consistent with the isotherms, the dark TiON controls suggest an initial sorptive loss for TCP but not for SMX. Alternatively, TiO₂ completely degraded TCP and SMX within 15 minutes. Thus, while the TiON materials were not as effective as TiO₂, initial results are promising.