Effect of nanomaterial and media physicochemical properties on nanomaterial aggregation kinetics

Abstract

Understanding nanomaterial (NM) stability is required for an adequate interpretation of ecotoxicological test outcomes, fate and behavior studies, to generate parameters (such as critical coagulation concentration, CCC; and attachment efficiency, α) for environmental fate models, and for comparison among different studies. Numerous studies measured CCC and α for different types of NMs with a major focus on investigating the effect of ionic strength, ion valency and natural organic matter, with fewer studies investigating the effect of NM and other medium properties. Consequently, wide discrepancies can be found in the literature among the reported CCC and α values, even for NMs of the same composition and properties. In this context, the aim of this review is to investigate the dependence of NM aggregation kinetic parameters (e.g. CCC and α) on NM and medium physicochemical properties and to rationalize the differences observed among different studies, where possible.We found that various material and medium physicochemical properties need to be considered to predict NM aggregation behavior. Some trends were observed and rationalized based on theoretical studies and data available in the literature. For charge stabilized NMs with constant zeta potential, NM stability (CCC) decreases with the increase in Hamaker constant, increase in NM size, increase in buffer (carbonate and phosphate) concentration, increase in temperature, and light irradiation. The CCC increase with counterion complexation. For sterically stabilized NMs, the CCC increases with the increased surface coverage by the capping agent molecules and completely coated NMs do not aggregate even in high ions strength medium (e.g. seawater). These results highlight the significant role of NM and medium properties in influencing the environmental stability and fate of NMs, and will help refine NM fate models and improve our understanding of NM uptake and toxicity.

Interactions between nanoparticles in nanosuspension

“…Therefore, an additional mechanism of stabilization, besides the electrostatic one should be in action for silica nanoparticles, such as for example a shift of surface charges location to outside the solid/liquid interface and/or a steric repulsion of flexible protruding surface groups [74]. It was found that addition of electrolyte destabilizes silica nano-suspensions and CCC for monovalent salt (NaCl) was two orders of magnitude higher than that for divalent salts in good agreement with the Shulze-Hardy rule [75]. For the divalent salts however, ion-specific effect was observed: MgCl 2 has two times smaller CCC than CaCl 2 and BaCl 2 .…”

Behavior and Bio-Interactions of Anthropogenic Particles in Marine Environment for a More Realistic Ecological Risk Assessment

“…As a result of the NP intrinsic (e.g., size, shape, roughness, and crystallinity) and extrinsic (e.g., temperature, ionic strength and composition, NOM) properties (Petosa et al, 2010;Baalousha, 2017), NPs may undergo rapid transformations in NSW, which drive NP fate and determine the presence (or absence) of effects on the marine biota (Matranga and Corsi, 2012;Corsi et al, 2014;Blasco et al, 2015).…”

Overview of the toxic effects of titanium dioxide nanoparticles in blood, liver, muscles, and brain of a Neotropical detritivorous fish

“…Despite this wide industrial application of TiO 2 ‐NP, little attention has been given to the environmental impact of their disposal, and there is still no specific regulation for discarding nanomaterials into aquatic systems . In aqueous solutions, TiO 2 ‐NP tend to agglomerate/aggregate or interact with suspended organic matter, and then deposit on the sediment . However, some TiO 2 ‐NP remain suspended in the water column (52‐86 μgL −1 ), mostly near sewages .…”