title: Effect of hydration repulsion on nanoparticle agglomeration evaluated via a constant number Monte-Carlo simulation.
abstract: The effect of hydration repulsion on the agglomeration of nanoparticles in aqueous suspensions was investigated via the description of agglomeration by the Smoluchowski coagulation equation using constant number Monte-Carlo simulation making use of the classical DLVO theory extended to include the hydration repulsion energy. Evaluation of experimental DLS measurements for TiO2, CeO2, SiO2, and α-Fe2O3 (hematite) at high IS (up to 900 mM) or low |ζ-potential| (≥1.35 mV) demonstrated that hydration repulsion energy can be above electrostatic repulsion energy such that the increased overall repulsion energy can significantly lower the agglomerate diameter relative to the classical DLVO prediction. While the classical DLVO theory, which is reasonably applicable for agglomeration of NPs of high |ζ-potential| (∼>35 mV) in suspensions of low IS (∼<1 mM), it can overpredict agglomerate sizes by up to a factor of 5 at high IS or low |ζ-potential|. Given the potential important role of hydration repulsion over a range of relevant conditions, there is merit in quantifying this repulsion energy over a wide range of conditions as part of overall characterization of NP suspensions. Such information would be of relevance to improved understanding of NP agglomeration in aqueous suspensions and its correlation with NP physicochemical and solution properties.
authors.affiliation: Center for the Environmental Implications of Nanotechnology, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA. Chemical and Biomolecular Engineering Department, University of California, Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Haoyang Haven
authors.initials: HH
authors.lastname: Liu
authors.forename: Jacob
authors.initials: J
authors.lastname: Lanphere
authors.forename: Sharon
authors.initials: S
authors.lastname: Walker
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen