RESEARCH PAPER Aggregation behaviour of TiO 2 nanoparticles in natural river water Ve ´ronique Adam . Ste ´phanie Loyaux-Lawniczak . Je ´ro ˆme Labille . Catherine Galindo . Mireille del Nero . Sophie Gangloff . Tiphaine Weber . Gaetana Quaranta Received: 7 August 2015 / Accepted: 29 December 2015 Ó Springer Science+Business Media Dordrecht 2016 Abstract The purpose of this study was to determine and understand the aggregation behaviour of industrial nanoparticulate TiO 2 (NPs) in the river water near a TiO 2 production plant. The aggregation was tested in near-reality conditions with industrial NPs and the filtered river water in which they are potentially released. The initial size of TiO 2 NPs is around 5 nm. The evolution of the hydrodynamic diameters of the TiO 2 aggregates in the presence of added Suwannee River fulvic acid (SRFA) and illite in the filtered river water was measured at pH 8 for at least 30 min with dynamic light scattering and laser diffraction. The experiments performed in the filtered river water allowed the determination of the attachment efficiency coefficients, and the experiments performed under conditions facilitating aggregation (with higher Ca 2? content) were used to understand the potential aggre- gation processes. When no Ca 2? was added into the river water, the initially aggregated TiO 2 did not develop a secondary aggregation in the presence of SRFA and illite. Upon the addition of 2.75 mM Ca 2? , TiO 2 was shown to heteroaggregate with illite at all tested concentrations. Consequently, in the studied river, the fate of the TiO 2 NPs does not seem to be related to that of the clay suspended particles upstream of the plant. However, the behaviours of the TiO 2 NPs and the clays are closely linked in the water with higher salt content, which is the case downstream of one of the industrial effluent release points. Keywords Industrial TiO 2 nanoparticles Á Attachment efficiency Á Aggregation Á Natural river water Á Environmental exposure Á Health risk Introduction Engineered nanoparticles (ENPs) are present in many consumer products (e.g. biomedicine, textiles and electronics) (Piccinno et al. 2012). Research into ENPs has developed over the last decade, but the Electronic supplementary material The online version of this article (doi:10.1007/s11051-015-3319-4) contains supple- mentary material, which is available to authorized users. V. Adam Á S. Loyaux-Lawniczak Á S. Gangloff Á T. Weber Á G. Quaranta (&) Laboratoire d’Hydrologie et de Ge ´ochimie de Strasbourg/ EOST/UDS, 1 rue Blessig, 67084 Strasbourg Cedex, France e-mail: quaranta@unistra.fr V. Adam French Environment and Energy Management Agency, 20 avenue du Gre ´sille ´, BP 90406, 49004 Angers Cedex 01, France J. Labille CNRS, IRD, CEREGE, UMR 7330, Aix-Marseille Universite ´, 13545 Aix-en-Provence, France C. Galindo Á M. del Nero Institut Plurisdisciplinaire Hubert Curien, 23 rue du Loess, BP 28, 67037 Strasbourg Cedex 2, France 123 J Nanopart Res (2016)18:13 DOI 10.1007/s11051-015-3319-4