title: Analysis of nanoparticle agglomeration in aqueous suspensions via constant-number Monte Carlo simulation.
abstract: A constant-number direct simulation Monte Carlo (DSMC) model was developed for the analysis of nanoparticle (NP) agglomeration in aqueous suspensions. The modeling approach, based on the "particles in a box" simulation method, considered both particle agglomeration and gravitational settling. Particle-particle agglomeration probability was determined based on the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and considerations of the collision frequency as impacted by Brownian motion. Model predictions were in reasonable agreement with respect to the particle size distribution and average agglomerate size when compared with dynamic light scattering (DLS) measurements for aqueous TiO(2), CeO(2), and C(60) nanoparticle suspensions over a wide range of pH (3-10) and ionic strength (0.01-156 mM). Simulations also demonstrated, in quantitative agreement with DLS measurements, that nanoparticle agglomerate size increased both with ionic strength and as the solution pH approached the isoelectric point (IEP). The present work suggests that the DSMC modeling approach, along with future use of an extended DLVO theory, has the potential for becoming a practical environmental analysis tool for predicting the agglomeration behavior of aqueous nanoparticle suspensions.
authors.affiliation: Center for the Environmental Implications of Nanotechnology, California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States.
authors.forename: Haoyang Haven
authors.initials: HH
authors.lastname: Liu
authors.forename: Sirikarn
authors.initials: S
authors.lastname: Surawanvijit
authors.forename: Robert
authors.initials: R
authors.lastname: Rallo
authors.forename: Gerassimos
authors.initials: G
authors.lastname: Orkoulas
authors.forename: Yoram
authors.initials: Y
authors.lastname: Cohen
mesh_terms: D002563:Cerium / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D009010:Monte Carlo Method; D053758:Nanoparticles / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry
chemical_list: C009495:titanium dioxide; D002563:Cerium; C030583:ceric oxide; D014025:Titanium