Peculiarities of coagulation of the pseudohydrophilic colloids: Aggregate stability of the positively charged -Al2O3 hydrosol in NaCl solutionsстатья
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Дата последнего поиска статьи во внешних источниках: 12 января 2022 г.
Аннотация:The results of the turbidimetric and dynamic light scattering study of colloid stability and coagulation kinetics of the polydisperse γ-Al2O3 hydrosol, prepared on the base of alumina nanopowder (Aeroxide Alu C, Evonik Degussa GmbH), in sodium chloride solutions (3×10⁻² M–2 М) at рН 4.2 are discussed within the extended Derjaguin–Landau–Verwey–Overbeek theory. We have revealed that the γ-Al2O3 dispersion possess an anomalous stability, i.e. unusually high salt concentration is required to cause coagulation, and can be viewed as a pseudohydrophilic system. The observed aggregate sol stability has been attributed to both the structural component of the particle interaction energy and the interaction of the solvate layers formed due to the secondary hydration of the surface. In order to adjust the agreement of the experimental and theoretical results, we have determined the optimal structural component parameters and the effective Hamaker constants for aggregates containing in initial sol along with primary nanoparticles. By analyzing the calculated particle interaction energy profiles and stability factor values, we have concluded that coagulation mainly proceeds via the barrierless mechanism in the long-range potential minimum.