TY - JOUR
TI - Strategies for determining heteroaggregation attachment efficiencies of engineered nanoparticles in aquatic environments
AU - Praetorius, A.
AU - Badetti, E.
AU - Brunelli, A.
AU - Clavier, A.
AU - Gallego-Urrea, J.A.
AU - Gondikas, A.
AU - Hassellöv, M.
AU - Hofmann, T.
AU - Mackevica, A.
AU - Marcomini, A.
AU - Peijnenburg, W.
AU - Quik, J.T.K.
AU - Seijo, M.
AU - Stoll, S.
AU - Tepe, N.
AU - Walch, H.
AU - Von Der Kammer, F.
JO - Environmental Science: Nano
PY - 2020
VL - 7
TODO - 2
SP - 351-367
PB - Royal Society of Chemistry
SN - 2051-8153, 2051-8161
TODO - 10.1039/c9en01016e
TODO - Efficiency;  Nanoparticles;  Particle size analysis;  Risk assessment, Aquatic environments;  Attachment efficiency;  Designed experiments;  Engineered nanoparticles;  Experimental approaches;  Experimental determination;  Quantitative information;  Suspended particulate matters, Agglomeration, aggregation;  aquatic environment;  complexity;  efficiency measurement;  environmental fate;  experimental study;  nanoparticle;  suspended particulate matter
TODO - Heteroaggregation of engineered nanoparticles (ENPs) with suspended particulate matter (SPM) ubiquitous in natural waters often dominates the transport behaviour and overall fate of ENPs in aquatic environments. In order to provide meaningful exposure predictions and support risk assessment for ENPs, environmental fate and transport models require quantitative information about this process, typically in the form of the so-called attachment efficiency for heteroaggregation αhetero. The inherent complexity of heteroaggregation-encompassing at least two different particle populations, various aggregation pathways and several possible attachment efficiencies (α values)-makes its theoretical and experimental determination challenging. In this frontier review we assess the current state of knowledge on heteroaggregation of ENPs with a focus on natural surface waters. A theoretical analysis presents relevant equations, outlines the possible aggregation pathways and highlights different types of α. In a second part, experimental approaches to study heteroaggregation and derive α values are reviewed and three possible strategies are identified: I) monitoring changes in size, ii) monitoring number or mass distribution and iii) studying indirect effects, such as sedimentation. It becomes apparent that the complexity of heteroaggregation creates various challenges and no single best method for its assessment has been developed yet. Nevertheless, many promising strategies have been identified and meaningful data can be derived from carefully designed experiments when accounting for the different concurrent aggregation pathways and clearly stating the type of α reported. For future method development a closer connection between experiments and models is encouraged. © 2020 The Royal Society of Chemistry.
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