Journal ArticleDOI
Aggregation Kinetics and Fractal Structure of γ-Alumina Assemblages
Thomas D. Waite,J.K. Cleaver,James K. Beattie +2 more
- Vol. 241, Iss: 2, pp 333-339
Reads0
Chats0
TLDR
In this article, the power law behavior of scattered light intensity as a function of scattering wave vector is observed in all cases and is suggestive of fractal structure, and the fractal dimensions obtained fall within the expected range of 1.8 to 2.3 observed for colloidal aggregates.Abstract:
Suspensions of a variety of different aluminum oxides have previously been shown to require very high concentrations of chloride and nitrate anions (>0.5 M) to induce rapid aggregation. This high stability has been accredited to the presence of surface forces considered to be due to the formation of highly charged Al13 polymeric species at slightly acidic pH's and aluminum oxyhydroxide gel formation under alkaline conditions. The effect of this stability on the structure of the resulting aggregates is investigated here using well-established static light-scattering techniques. Power law behavior of scattered light intensity as a function of scattering wave vector is observed in all cases and is suggestive of fractal structure. The fractal dimensions obtained fall within the expected range of 1.8 to 2.3 observed for colloidal aggregates but do not appear to follow the typical observations for colloids destabilized by indifferent electrolytes where lower fractal dimensions are associated with rapid (diffusion-limited) aggregation and higher fractal dimensions with slower (reaction-limited) aggregation. Indeed, relatively constant fractal dimensions (2.10 to 2.25) are observed over the range of salt concentrations at which the slow to rapid aggregation rate transformation occurs with, if anything, a slightly higher fractal dimension observed for higher aggregation rates. The presence of specifically binding sulfate anions appears to negate the strong near-distance repulsive forces leading to rapid aggregation at low (1 to 2 mM) sulfate concentrations. Significantly lower fractal dimensions (1.85 to 1.91) are observed for aggregates formed by destabilization using sulfate ions than obtained when chloride or nitrate are used with, again, an apparent slight increase in fractal dimension upon increasing aggregation rate.read more
Citations
More filters
Dissertation
Physico-thermal properties of TiO2 nanoparticles using molecular dynamics simulations with relevance to thermal conductance of nanofluids
TL;DR: In this paper, the effect of particle clustering on thermal conductivity of nanofluids is analyzed for different factors, such as aggregate size, particle concentration, interfacial thermal resistance, and fractal and chemical dimensions.
Journal Article
Stochastic lattice model of aggregation in heterogeneous polydisperse media
TL;DR: A new model algorithmic approach to describing aggregation processes, which is based on mathematical tool of a random walk over mathematical lattices, which agrees as a whole with the DES paradigm is proposed.
Dissertation
Colloidal Interactions in Aquatic Environments: Effect of Charge Heterogeneity and Charge Asymmetry
Journal ArticleDOI
A novel quantitative method for evaluating floc strength under turbulent flow conditions
TL;DR: In this article, the binding and breaking forces of floc were evaluated under turbulent flow conditions, and the binding force was defined as a function of the floc diameter and fractal dimension.
Journal ArticleDOI
Development of the Stochastic Lattice Model for Describing Aggregation Processes in the Polydisperse Systems (3D Case)
Leila Musabekova,Nurlybek Zhumataev,Altynay Yunussova,Nurzhamal Dausheyeva,Aziza Zhidebayeva +4 more
TL;DR: The submitted method is an extension of the method previously developed by the authors for the case of a three-dimensional stochastic lattice, which allows reducing the problem of calculating the aggregation kernels in kinetic equations to taking into account the hierarchy of characteristic times of the various stages of the aggregation process.
References
More filters
Book
Foundations of Colloid Science
TL;DR: The structure of concentrated dispersions thin films Emulsions Microemulsions Rheology of colloidal dispersions and their properties are described in detail in this paper, with a focus on statistical mechanics of fluids.
Journal ArticleDOI
Electrophoretic mobility of a spherical colloidal particle
R.W O'Brien,Lee R. White +1 more
TL;DR: In this article, it was shown that for a colloidal particle of any shape the mobility is independent of the dielectric properties of the particle and the electrostatic boundary conditions on the particle surface.
Journal ArticleDOI
Limits of the Fractal Dimension for Irreversible Kinetic Aggregation of Gold Colloids
TL;DR: On montre qu'il existe 2 regimes d'agregation cinetique, irreversible, de colloides aqueux, determinee par le potentiel interparticulaire a courte distance, avec controle de la probabilite de collage lors de l'approche de 2 particules.