Influence of surface conductivity on the apparent zeta potential of TiO2 nanoparticles: Application to the modeling of their aggregation kinetics

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:406

Article

Bouhaik, Izzeddine Sameut^1,2  Leroy, Philippe¹  Ollivier, Patrick¹  Azaroual, Mohamed¹  Mercury, Lionel^2,3 

[1] Bur Rech Geol & Minieres, ISTO UMR 7327, F-45060 Orleans 2, France

[2] Univ Orleans, ISTO UMR 7327, F-45071 Orleans, France

[3] CNRS INSU, ISTO UMR 7327, F-45071 Orleans, France

关键词: Stability ratio;    TiO2;    Nanoparticle;    Zeta potential;    Surface conductivity;    Extended Stern model;    Linear superposition approximation;    Derjaguin approximation;    Surface element integration;   

DOI  :  10.1016/j.jcis.2013.05.034

来源: Elsevier

【 摘 要 】

Titanium dioxide nanoparticles (TiO2 NPs) are extensively used in consumer products. The release of these NPs into aquatic environments raises the question of their possible risks to the environment and human health. The magnitude of the threat may depend on whether TiO2 NPs are aggregated or dispersed. Currently, limited information is available on this subject. A new approach based on DLVO theory is proposed to describe aggregation kinetics of TiO2 NPs in aqueous dispersions. It has the advantage of using zeta potentials directly calculated by an electrostatic surface complexation model whose parameters are calibrated by ab initio calculations, crystallographic studies, potentiometric titration and electrophoretic mobility experiments. Indeed, the conversion of electrophoretic mobility measurements into zeta potentials is very complex for metal oxide nanoparticles. This is due to their very high surface electrical conductivity associated with the electromigration of counter and co-ions in their electrical double layer. Our model has only three adjustable parameters (the minimum separation distance between NPs, the Hamaker constant, and the effective interaction radius of the particle), and predicts very well the stability ratios of TiO2 NPs measured at different pH values and over a broad range of ionic strengths (KCI aqueous solution). We found an effective interaction radius that is significantly smaller than the radius of the aggregate and corresponds to the radius of surface crystallites or small clusters of surface crystallites formed during synthesis of primary particles. Our results confirm that DLVO theory is relevant to predict aggregation kinetics of TiO2 NPs if the double layer interaction energy is estimated accurately. (C) 2013 Elsevier Inc. All rights reserved.

【 授权许可】

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