Silicon impurity release and surface transformation of TiO2 anatase and rutile nanoparticles in water environments.

Silicon impurity release and surface transformation of TiO2 anatase and rutile nanoparticles in water environments.

Environmental pollution (Barking, Essex : 1987) (2013-11-05)

Xuyang Liu, Gexin Chen, Justin G Erwin, Chunming Su

ABSTRACT

Surface transformation can affect the stability, reactivity, and toxicity of titanium dioxide (TiO2) nanoparticles (NPs) in water environments. Herein, we investigated the release kinetics of Si impurity frequently introduced during NP synthesis and the resulting effect on TiO2 NP transformation in aqueous solutions. The release of Si increased from 2 h to 19 d at three pHs with the order: pH 11.2 ≥ pH 2.4 > pH 8.2. The Si release process followed parabolic kinetics which is similar to diffusion controlled dissolution of minerals, and the release magnitude followed the order: 10 × 40 nm rutile > 50 nm anatase > 30 × 40 nm rutile. FTIR data indicated preferential dissolving of less polymerized Si species on NP surface. Surface potential and particle size of TiO2 NPs remained almost constant during the 42-day monitoring, implying the unaffected stability and transport of these NPs by the incongruent dissolution of impurities.

MATERIALS

Product Number

Brand

Product Description

204730

Sigma-Aldrich

Titanium(IV) oxide, rutile, 99.995% trace metals basis

204757

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Titanium(IV) oxide, rutile, ≥99.98% trace metals basis

224227

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343250

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215619

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Sigma-Aldrich

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647543

Sigma-Aldrich

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Sigma-Aldrich

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