Absolute Aggregation Rate Constants in Aggregation of Kaolinite Measured by Simultaneous Static and Dynamic Light Scattering

Abstract

The aggregation rate was determined for the < 0.2 microm size fraction of kaolinite (KGa-2) using simultaneous static and dynamic light scattering at pH 9.5. It was found that method suggested by Holthoff et al. [Langmuir 1996, 12, 5541] is suitable for determination of the absolute aggregation rate constant of a clay dispersion without using the particle optical factors. The determined fast aggregation rate constant is k11,fast = (3.7 +/- 0.2) x 10(-18) m3 s(-1). Stability behavior of kaolinite colloids was studied as a function of concentration of sodium chloride by simultaneous static and dynamic scattering. The critical aggregation concentration was found to be 0.085 +/- 0.005 mol dm(-3). When calculating the relationship between the stability ratio and the electrolyte concentration using the DLVO theory, the best fit to the experimental data was achieved with a Hamaker constant of A = (4.7 +/- 0.2) x 10(-20) J.

Modeling the effects of Ca2+ and clay-associated organic carbon on the stability of colloids from topsoils

“…5, the calculated potential-energy diagrams along the distance (H) between interacting particles at various Ca 2+ concentrations are shown for the case of pristine topsoil colloids from Bad Lauchstädt (L c ). [34], goethite [14,36]; Al 2 O 3 [37]; illite [38]; kaolinite [39,40]; montmorillonite [39,41]. The ranges of corresponding A literature are bordered by horizontal bars.…”

Thermal and colloidal behavior of amine-treated clays: The role of amphiphilic organic cation concentration

“…The DLS technique has already been successfully used in several studies [31,[34][35][36][37] to determine the coagulation rates of colloidal clay suspensions. However, the influence of surfactant concentration on the stability of organically modified MMT suspensions has not been researched sufficiently.…”

Probing effects of polymer adsorption in colloidal particle suspensions by light scattering as relevant for the aquatic environment: An overview

“…The substantial advantage of this technique is that it operates entirely in situ without any sample disturbance. Moreover, the technique works equally well with non-spherical and polydisperse samples, such as the clay fraction extracted from soil samples (Grolimund et al, 2001;Berka and Rice, 2004;Saleh et al, 2008). To measure the particle aggregation rate (or stability ratio) reliably, however, the particle concentration must be adjusted such that the aggregation remains in its early-stages on a time scale of at least several minutes.…”