Partitioning and Particle Size of Dye Dispersions

Abstract

Aqueous dye dispersions stabilized with sodium lignosulfonate were extracted with water immiscible solvents in which the dye but not the dispersant is soluble. The amount of dye extracted depends on extraction conditions and the stability of the dispersion. When the extraction conditions and the composition of the dispersion are constant, the nonequilibrium partition ratio of the dye between the aqueous phase and the solvent phase is correlated with the particle size of the dispersion. The partition ratio (water/solvent) increases exponentially with the decreasing particle size and correlates with particle size values obtained by a centrifugation method. The partition method was used to estimate the particle size of sand milled dye dispersions. Within the range of variables studied, the fineness of the dye dispersion increased with the increasing milling time, fineness of sand, sand/dye weight ratio, and dispersant con centration. The efficiency of the milling process decreased with the increasing dilution of the dye slurry with water.