Photon correlation spectroscopy of a coagulating suspension of illite platelets

Abstract

The self-beat intensity correlation spectra scattered from coagulating suspensions of illite platelets have been analysed to determine colloidal stability ratios. The stability ratio results as a function of KCl concentration were used to evaluate the effective Hamaker constant for the illite platelets. The effective Hamaker constant obtained by this method compares favourably with those obtained by direct measurement on crystallographically identical mica plates, either in KNO, solution or, after applying the geometric mixing rule, in a vacuum.

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.…”

Coagulation Rate Measurements of Colloidal Particles by Simultaneous Static and Dynamic Light Scattering

“…Since the beginning, coagulation experiments played an important role in discussions about intermolecular forces. Experiments were performed on a variety of different model systems with different techniques, such as direct counting of the aggregation using ultramicroscope or particle counter, − turbidity measurements, − low angle light scattering, − dynamic light scattering − or electric birefringence measurements …”

Generation of Reproducible Model Freshwater Particulate Matter Analogues to Study the Interaction with Particulate Contaminants.

“…Illite features intrinsic surface charge heterogeneity: its basal planes are permanently negatively charged due to isomorphic substitutions in the crystal lattice (Si 4+ in tetrahedral and Al 3+ in octahedral layers, are substituted by Al 3+ and Mg 2+ or Fe 2+ , respectively), and hydroxyl-groups on broken edges exhibit pH-dependent variable charge (Preocanin et al, 2016). The three materials come with different Hamaker constants (A11 in water: 0.8-1.2 × 10 -20 J for quartz; 3.3-3.9 × 10 -20 J for FeOx (Baalousha, 2016); 2.5-3.3 × 10 -20 for illite (Novich and Ring, 1985;Séquaris, 2010;Shao et al, 2020)), and different hydrophobicity, with quartz being hydrophilic and hematite slightly hydrophobic up to neutral pH, at alkaline pH hydroxylation renders it hydrophilic (Shrimali et al, 2016;Tarasevich et al, 2002). Phyllosilicates exhibit hydrophilic and hydrophobic properties (Bantignies et al, 1997;Cuadros, 2017): with a decreasing degree of isomorphic substitution (which is intermediate for illite: talc < kaolinite < S 8 illite < muscovite < montmorillonite) basal planes increase their hydrophobicity, while edge hydroxyl-groups are typically hydrophilic (Yin, 2012).…”