Colloidal aggregation mechanism

Femandez-Barbero A, Cabrerizo-Vilchez M, Martinez-Garcia R, Hidalgo-Alvarez R (1996) Effect of the particle surface charge density on the colloidal aggregation mechanism. Phys Rev E 53 4981 989. doi 10.1103/PhysRevE.53.4981... 

Cabane, B., Meireles, M., and Aimar, P. (2002). Cake collapse in frontal filtration of colloidal aggregates Mechanisms and consequences. Desalination 146, 155-161. 

One major question of interest is how much asphaltene will flocculate out under certain conditions. Since the system under study consist generally of a mixture of oil, aromatics, resins, and asphaltenes it may be possible to consider each of the constituents of this system as a continuous or discrete mixture (depending on the number of its components) interacting with each other as pseudo-pure-components. The theory of continuous mixtures (24), and the statistical mechanical theory of monomer/polymer solutions, and the theory of colloidal aggregations and solutions are utilized in our laboratories to analyze and predict the phase behavior and other properties of this system. 

Second, nucleation and growth of Stober silica particles is modeled by a controlled aggregation mechanism of subparticles, a few nanometers in size, as for example presented by Bogush and Zukoski (19). Colloidal stability, nuclei size, surface charge, and diffusion and aggregation characteristics are the important parameters in this model. 

In contrast, the three- or two-dimensional morphologies of colloidal aggregates via Brownian particle trajectories show a fractal-like structure. One of the most prominent features of the surface deposits formed by the diffusion-limited aggregation mechanism is the formation of isolated treelike clusters (9). In our experiments, the surface morphology of the silica-coated polyethylene composite prepared by... 

Lips, A., Campbell, I. J., and Pelan, E. G. (1991). Aggregation mechanisms in food colloids and the role of biopolymers. In Food Polymers, Gels and Colloids, Dickinson, E. (Ed.), pp. 1-21. Royal Chem. Soc., London. 

Sedimentation field-flow fractionation was used also for the kinetic study of hydroxyapatite (HAP) particles aggregation in the presence of various electrolytes to determine the rate constants for the bimol-ecular process of aggregation and to investigate the possible aggregation mechanisms describing the experimental data. The HAP sample contained polydis-perse, irregular colloidal particles with number-average diameter dys = 0.262 + 0.046 /rm. 

Solubilization is the increase in solubility of a poorly water-soluble substance with surface-active agents. The mechanism involves entrapment (adsorbed or dissolved) of molecules in micelles and the tendency of surfactants to form colloidal aggregations at critical micelle concentration levels. Thus, the critical micelle concentration is the minimum surfactant concentration that begins solubilization of the insoluble molecule. Increases in the concentration of micelles lead to increases in drug solubility. 

The second part is devoted to adsorption of polyelectrolytes at interfaces and to flocculation and stabilization of particles in adsorbing polymer solutions. A recent theory of the electrostatic adsorption barrier, some typical experimental results, and new approaches for studying the kinetics of polyelectrolyte adsorption are presented in the first chapter of this part. In the following chapters, results are collected on the electrical and hydrodynamic properties of colloid-polyelectrolyte surface layers, giving information on the structure of adsorbed layers and their influence on the interactions between colloidal particles examples and mechanisms are analyzed of polyelectrolyte-induced stabilization and fragmentation of colloidal aggregates ... 

The variation of the natural organics characteristics with changes in solution chemistry, their interaction with cations and other compounds and their interactions with inorganic colloids will also be discussed. These interactions occur in natural waters and may also influence treatability. A brief description of colloid characterisation and aggregation mechanisms is also given. 

Reaction limited (slow) aggregation occurs when repulsion between colloids is strong (thus at low to moderate salt concentrations). The colloidal aggregates have time to interpenetrate and thus compact aggregates of high mechanical strength form (see Figure 4.19B). 

The exact form of the DLVO potential, the influence of the DLVO forces on aggregation mechanisms and the stmcture of the resulting aggregates is still a major field under investigation in colloidal chemistry. It should be noted here that the DLVO validity is, in principle, limited to large particles with small curvatures and to small separation distances between the two particles. 

Ouali, L. Stoll, S. and Pefferkom, E. (1995). The mechanisms and kinetics of the fragmentation of colloidal aggregates induced by electrostatic and electrosteric repulsion. In Fragmentation Phenomena, Beysens, D., Campi, X. and Pefferkom, E. (eds). World Scientific, Singapore, pp. 64—76. 

Bottero, J.Y., Tchoubar, D., Axelos, M.A.V., Quienne, P. and Fiessinger, F. (1990). Hoc-culation of sihea colloids with hydroxy aluminum polycations. Relation between floe structure and aggregation mechanisms. Langmuir, 6, 596-602. 

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