Mechanism of de-aggregation and stability of rutile dispersion in organic liquids

Abstract

The objective of this research was to determine the mechanism whereby trace water affects the dispersion characteristics of rutile in organic liquids. Removal of trace water caused a ten-fold linear increase in electrophoretic mobility of rutile in heptanol over the range 0.30–0.03 water coverage, and a distinct decrease at lower coverage. Aggregate size, as revealed by ultramicroscopic examination, decreased slightly between 0.30 and 0.08 coverage and then increased. Based on the relative intensities of the infra-red band for CH₂ bending, the residual concentration of heptanol on the rutile surface was found to be a maximum at a water coverage of 0.08. The results suggest that at water coverages below 0.08, dispersibility of the rutile is not related directly with surface potential, but that agglomerates form due to chemical bonding between particles as well as decreased interaction of heptanol with the rutile surface.