When engineered nanoparticles (ENPs) migrate into aquatic systems, the surface chemistry of ENPs is constantly modified by their interactions with aquatic constituents. Although a significant body of knowledge has been accrued on the reactivity and toxicity of as-manufactured ENPs or those coated with organic capping agents, the effects of ubiquitous transition metal ions in natural waters, such as Fe(II) and Fe(III), on the surface properties and chemical reactivity of metal oxide ENPs have remained enigmatic. In this study, the authors investigated the origin of enhanced (photo)-catalytic activity of TiO2 nanoparticles (Degussa P25) exposed to aqueous solutions containing environmentally relevant concentrations of dissolved iron. With batch wet oxidation experiments and complementary material/surface analyses, we sought to understand the effects of the initial oxidation state of iron and the aqueous chemistry on the chemical nature of iron species immobilized onto the TiO2 surfaces. The data suggest that the enhanced catalytic activity of environmentally modified TiO2 arises from strong chemical interactions between the TiO2 surface and dissolved iron, resulting in significant surface accumulation of reactive iron species at a circumneutral pH range. It is postulated that surface alteration due to exposure to redox-active metal ions in the aqueous media is an important consideration in assessing the environmental behaviors and the safety of metal oxide NPs.

Interactions of TiO<sub>2 </sub>nanoparticles with aquatic media: Enhanced dark and photo-induced catalytic activity due to surface enrichment of Fe(III) species

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Interactions of TiO2 nanoparticles with aquatic media: Enhanced dark and photo-induced catalytic activity due to surface enrichment of Fe(III) species

Interactions of TiO₂nanoparticles with aquatic media: Enhanced dark and photo-induced catalytic activity due to surface enrichment of Fe(III) species