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Natural colloids are the dominant factor in the sedimentation of nanoparticles
Author(s) -
Quik Joris T.K.,
Stuart Martien Cohen,
Wouterse Marja,
Peijnenburg Willie,
Hendriks A. Jan,
van de Meent Dik
Publication year - 2012
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.1783
Subject(s) - sedimentation , nanoparticle , natural organic matter , colloid , particle (ecology) , environmental chemistry , nanomaterials , deposition (geology) , fraction (chemistry) , chemistry , chemical engineering , water treatment , mineralogy , environmental science , sediment , materials science , chromatography , nanotechnology , environmental engineering , geology , organic chemistry , paleontology , oceanography , engineering
Estimating the environmental exposure to manufactured nanomaterials is part of risk assessment. Because nanoparticles aggregate with each other (homoaggregation) and with other particles (heteroaggregation), the main route of the removal of most nanoparticles from water is aggregation, followed by sedimentation. The authors used water samples from two rivers in Europe, the Rhine and the Meuse. To distinguish between small (mainly natural organic matter [NOM]) particles and the remainder of the natural colloids present, both filtered and unfiltered river water was used to prepare the particle suspensions. The results show that the removal of nanoparticles from natural river water follows first‐order kinetics toward a residual concentration. This was measured in river water with less than 1 mg L −1 CeO 2 nanoparticles. The authors inferred that the heteroaggregation with or deposition onto the solid fraction of natural colloids was the main mechanism causing sedimentation in relation to homoaggregation. In contrast, the NOM fraction in filtered river water stabilized the residual nanoparticles against further sedimentation for up to 12 d. In 10 mg L −1 and 100 mg L −1 CeO 2 nanoparticle suspensions, homoaggregation is likely the main mechanism leading to sedimentation. The proposed model could form the basis for improved exposure assessment for nanomaterials. Environ. Toxicol. Chem. 2012; 31: 1019–1022. © 2012 SETAC