TY - JOUR

T1 - Heteroaggregation of titanium dioxide nanoparticles with model natural colloids under environmentally relevant conditions

AU - Praetorius, Antonia

AU - Labille, Jérôme

AU - Scheringer, Martin

AU - Thill, Antoine

AU - Hungerbühler, Konrad

AU - Bottero, Jean-Yves

PY - 2014/9/16

Y1 - 2014/9/16

N2 - 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, αhetero, 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 αhetero 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 μm) 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 αhetero values close to 1. At pH 8, where all particles are negatively charged, αhetero was strongly affected by the solution conditions, with αhetero 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.

AB - 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, αhetero, 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 αhetero 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 μm) 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 αhetero values close to 1. At pH 8, where all particles are negatively charged, αhetero was strongly affected by the solution conditions, with αhetero 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.

KW - Chemistry

UR - http://www.scopus.com/inward/record.url?scp=84922438708&partnerID=8YFLogxK

U2 - 10.1021/es501655v

DO - 10.1021/es501655v

M3 - Journal articles

C2 - 25127331

VL - 48

SP - 10690

EP - 10698

JO - Environmental Science & Technology

JF - Environmental Science & Technology

SN - 0013-936X

IS - 18

ER -