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
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
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Journal ArticleDOI
Stimuli-Responsive Nanolatexes: Porating Films
TL;DR: In this paper, a new class of very stable and stimuli-responsive nanolatexes based on copolymers of reactive and stimuli responsive ionic liquid surfactants is synthesized by microemulsion polymerization to yield dispersions of 22-30 nm diameter particles.
Journal ArticleDOI
A promising application of chitosan quaternary ammonium salt to removal of Microcystis aeruginosa cells from drinking water
TL;DR: Results showed that all cells were removed without damage under optimum coagulation conditions and the large size and compact structure of flocs formed by HTCC, which readily settled, could protect cells from cellular oxidative damage caused by ROS, thus keeping the cells intact for a longer time.
Journal ArticleDOI
Effect of PEG on rheology and stability of nanocrystalline titania hydrosols.
TL;DR: Addition of polyethylene glycol (PEG 2000) induced a marked decrease of the sol viscosity down to a minimum, explained by assuming that PEG adsorbs on the surface of TiO(2) particles producing stabilization by steric effects and leading to formation of more compact aggregates.
Journal ArticleDOI
Effect of nanomaterial and media physicochemical properties on nanomaterial aggregation kinetics
TL;DR: In this paper, the dependence of NM aggregation kinetic parameters (e.g., critical coagulation concentration, CCC; and attachment efficiency, α) for environmental fate models, and for comparison among different studies, is investigated.
Journal ArticleDOI
Effect of preformed and non-preformed Al13 species on evolution of floc size, strength and fractal nature of humic acid flocs in coagulation process
TL;DR: In this article, the performance of pre-hydrolyzed Al13 and in situ formed Al13 in humic acid (HA) coagulation was comparatively investigated in a laser diffraction particle sizing device.
References
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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.