Effect of Ultrasonic Treatment on Aqueous Dispersion of Inorganic and Organic Pigments in Presence of Water-Soluble Polymers and Surfactants

I.Kuzkina, N.A.Bulytchev, V.P.Zubov (Moscow Academy of Fine Chemical Technology, Moscow, Russia); I.A.Arutunov (Moscow Academy of Fine Chemical Technology, Moscow); N.A.Serebryakova (Institute of Physical Chemistry, Russian Academy of Sciences, Moscow, Russia); O.V.Abramov (Institute of General and Inorganic Chemistry of RAS, Moscow, Russia)


The stability of aqueous dispersions of inorganic pigments Ti02 (rutile) and Fe203 (red) under ultrasonic treatment in the presence of ethylhydroxy(ethyl)cellulose (EHEC) was studied. The ultrasonic generator "UZDN-2" with frequency of 22 kHz and intensity of 30 W/cm2 was used for treatment of pigments dispersions. Without polymer the ultrasonic treatment of a dilute Ti02 and Fe203 aqueous dispersions results in a rapid complete coagulation of the dispersions. In the presence of EHEC a stabilizing effect was observed, which depends on the polymer concentration and the duration of the ultrasonic treatment. Ultrasonic treatment results in a reduction of particles size (from 1 mcm to 0.3 mcm) and the narrower particle size distribution. It was supposed that the ultrasonic treatment results not only in an effective deagglomeration of particles, but also initiates adsorption of polymer on freshly activated surfaces. The evidences of polymer adsorption on the pigments surface and creation of the stabilizing layer were obtained by measuring the - potential by the electrokinetic sonic amplitude (ESA) method and by the method of IR - spectroscopy. As an organic pigment we used copper phthalocyanine (CuPc). Its surface is very hydrophobic and not wettable with water. Earlier we showed that the wetting effect was observed in the presence of polyvinyl alcohol (PVA) with residual acetyl groups content of 10-20% and molecular weight of 10000-11000. Wetting of the surface of pigment results in its transfer into the aqueous phase and the latter gets bright-blue color. The increase of color intensity goes in parallel with efficiency of stabilizing action of PVA and thus it could be used as measure of stabilization action. The values of optical density of CuPc dispersions with separated solid phase becomes significantly higher in the case of ultrasonic treatment of the dispersions. Similar effects were observed for CuPc aqueous dispersions when non-polymeric and anionic surfactants in combination with ultrasonic treatment were used.


Section : 11