A study on independently using static and dynamic light scattering methods to determine the coagulation rate

Abstract

A first-passage scheme for determination of overall rate constants for non-diffusion-limited suspensions J. Chem. Phys. 116, 3128 (2002); 10.1063/1.1436119 This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation. Absolute coagulation rate constants were determined by independently, instead of simultaneously, using static and dynamic light scattering with the requested optical factors calculated by T-matrix method. The aggregating suspensions of latex particles with diameters of 500, 700, and 900 nm, that are all beyond validity limit of the traditional Rayleigh-Debye-Gans approximation, were adopted. The results from independent static and dynamic light scattering measurements were compared with those by simultaneously using static and dynamic light scattering; and three of them show good consistency. We found, theoretically and experimentally, that for independent static light scattering measurements there are blind scattering angles at that the scattering measurements become impossible and the number of blind angles increases rapidly with particle size. For independent dynamic light scattering measurements, however, there is no such a blind angle at all. A possible explanation of the observed phenomena is also presented. © 2014 AIP Publishing LLC.

Orders of Magnitude Reduction of Rapid Coagulation Rate with Decreasing Size of Silica Nanoparticles

“…To examine the applicability of Smoluchowski theory, many attempts have been made to obtain the experimental values of the rapid coagulation rate, K R E , with various kinds of apparatus, such as the Coulter counter, , low-angle light-scattering apparatus, − and other light-scattering devices. − Most of the K R E values obtained are scattering around the half of the magnitude of K R S . However, this discrepancy between K R S and K R E has been successfully explained by introducing the hydrodynamic squeezing flow between colliding particles and properly adjusting the magnitude of Hamaker constant A in the van der Waals attractive potential for equal spheres V A sph , which is expressed by eq where h̅ is a nondimensional separation distance, h / a , where h is the separation distance between particle surfaces and a is the particle radius.…”

Extraordinary Destabilization of Silica Nanocolloids by Filtration

“…When the viscosity of water is used for μ and the value of A is taken to be 8.3 × 10 –21 J for silica particles in water, K R S and K R SM at T = 25 °C are equal to 6.16 × 10 –18 and 3.49 × 10 –18 m 3 /s (=0.566 K R S ), respectively. Equation has been supported for a long time, because many experimental values of the rapid coagulation rate constant for colloids of micrometer size, K R E , are consistent with the prediction by this equation, − although the recent extensive studies derived a little smaller value of K R E = 0.24 K R S ∼ 0.34 K R S . , Here, it is important to note that both K R S and K R SM are independent of the particle size.…”

“…Equation 4 has been supported for a long time, because many experimental values of the rapid coagulation rate constant for colloids of micrometer size, K R E , are consistent with the prediction by this equation, 18−28 although the recent extensive studies derived a little smaller value of K R E = 0.24K R S ∼ 0.34K R S . 29,30 Here, it is important to note that both K R S and K R SM are independent of the particle size.…”

Ionic Specificity in Rapid Coagulation of Silica Nanoparticles

“…Numerous attempts have been made to check the adequacy of eq , and the experimental values of rapid coagulation rate K R E were found to be scattering mostly around the value predicted by eq , − although the recent extensive studies derived a little smaller value of K R E : 0.24 K R S ∼ 0.34 K R S . , Hence, eq has been widely accepted for a long time, but a few studies, including our previous one, reported that the value of K R E reduces by several orders of magnitude with a decreasing particle size. − …”