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Mechanisms limiting the release of TiO2 nanomaterials during photocatalytic cement alteration: the role of surface charge and porous network morphology

Abstract

Nanomaterials have been widely used in a wide range of manufactured products in order to improve / add new properties. Photocatalytic cement maintains clean and white wall fronts and also provide interesting air pollution-reducing properties due to photocatalytic activity of incorporated TiO2-NMs. However, despite these environmental benefits, there is evidence of the release of TiO2-NMs during cement use. Therefore, it is crucial to understand the parameters controlling TiO2-NMs release. Zêta potentials of TiO2-NMs were investigated from the unaltered core to the cement altered surface using simulated cement pore waters. The mineralogy and chemical composition of the altered layer were investigated using X-ray Diffraction (XRD) and micro X-ray fluorescence spectroscopy (micro-XRF). Finally, pore network morphology was fully analyzed using X-ray computed tomography at both micro and nano-scales (micro and nano-CT) and quantified using 3D morphological software (i-Morph). This study provides evidence that the TiO2-NMs release comes from a very thin “active surface layer” (thickness less than 20 µm) where both cement surface chemistry and the pore network appears to be favorable for the TiO2-NMs diffusion. The pore volume connected to the surface with a throat size ≥1016 nm appears to control and be used as a predictor for TiO2-NMs release.

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Publication details

The article was received on 28 Jun 2018, accepted on 10 Jan 2019 and first published on 11 Jan 2019


Article type: Paper
DOI: 10.1039/C8EN00700D
Citation: Environ. Sci.: Nano, 2019, Accepted Manuscript
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    Mechanisms limiting the release of TiO2 nanomaterials during photocatalytic cement alteration: the role of surface charge and porous network morphology

    N. bossa, P. Chaurand, C. Levard, J. Vicente, D. Borschneck, C. GEANTET, O. Aguerre-Chariol and J. Rose, Environ. Sci.: Nano, 2019, Accepted Manuscript , DOI: 10.1039/C8EN00700D

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