In:
Bulletin of the Chemical Society of Japan, Oxford University Press (OUP), Vol. 57, No. 12 ( 1984-12-01), p. 3419-3425
Abstract:
The dispersion stability of titanium dioxide particles and two kinds of iron(III) oxide particles in dioxane–water mixtures was studied as a function of the dielectric constant(ε=2.2–78). The sedimentation of dispersions, the adsorption of sodium 1,2-bis(2-ethylhexyloxycarbonyl)ethanesulfonate (Aerosol OT or AOT) on the particles, and the zeta potential were measured. In the absence of AOT, the dispersions of all the particles were rapidly flocculated over all of the region of the dielectric constant, and little effect of the dielectric constant on the dispersibility was observed. In the presence of AOT, however, the dispersions of all the kinds of particles used were stabilized at both the lower(ε=2.2) and higher(ε=60–78) regions of the dielectric constant by the adsorption of AOT on the particles. However, the flocculation was accelerated for all kinds of particles, and AOT molecules were not at all, or scarcely, adsorbed on the particles in the middle region of the dielectric constant(ε=10–50). This behavior of the dispersibility corresponded with the results of the dynamic light scattering of the AOT solution, which reveal the aggregation of AOT molecules at various dielectric constants. The zeta potential changed from a positive sign to a negative sign with the increase in the dielectric constant, and the isoelectric dielectric point (IED), which means a zero value of the zeta potential, appeared. The order of the values of IED among the three kinds of particles agrees with the order of the isoelectric points(IEP) of the particles. This result can, therefore, be explained by the concept of the acid-base interaction between a particle and a solvent in dioxane–water mixtures.
Type of Medium:
Online Resource
ISSN:
0009-2673
,
1348-0634
DOI:
10.1246/bcsj.57.3419
Language:
English
Publisher:
Oxford University Press (OUP)
Publication Date:
1984
detail.hit.zdb_id:
2041163-7
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