Heteroaggregation of Titanium Dioxide Nanoparticles with Model Natural Colloids under Environmentally Relevant Conditions

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• 作者：Antonia Praetorius ; J茅r么me Labille ; Martin Scheringer ; Antoine Thill ; Konrad Hungerb眉hler ; Jean-Yves Bottero
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：September 16, 2014
• 年：2014
• 卷：48
• 期：18
• 页码：10690-10698
• 全文大小：438K
• ISSN：1520-5851

文摘

The heteroaggregation of engineered nanoparticles (ENPs) with natural colloids (NCs), which are ubiquitous in natural surface waters, is a crucial process affecting the environmental transport and fate of ENPs. Attachment efficiencies for heteroaggregation, 伪_hetero, are required as input parameters in environmental fate models to predict ENP concentrations and contribute to ENP risk assessment. Here, we present a novel method for determining 伪_hetero values by using a combination of laser diffraction measurements and aggregation modeling based on the Smoluchowski equation. Titanium dioxide nanoparticles (TiO₂ NPs, 15 nm) were used to demonstrate this new approach together with larger silicon dioxide particles (SiO₂, 0.5 渭m) representing NCs. Heteroaggregation experiments were performed at different environmentally relevant solution conditions. At pH 5 the TiO₂ NPs and the SiO₂ particles are of opposite charge, resulting in 伪_hetero values close to 1. At pH 8, where all particles are negatively charged, 伪_hetero was strongly affected by the solution conditions, with 伪_hetero ranging from <0.001 at low ionic strength to 1 at conditions with high NaCl or CaCl₂ concentrations. The presence of humic acid stabilized the system against heteroaggregation.