EVOLUTION OF DISPERSED SYSTEMS OF METAL OXIDES NANOPARTICLES OBTAINED IN A PLASMA DISCHARGE IN LIQUIDS UNDER THE EFFECT OF ULTRASOUND

Abstract

In this work, nanoparticles of aluminum, copper and titanium oxides have been obtained in a plasma discharge in the liquid phase (ethylene glycol, water) under the influence of intense ultrasound. Particular procedures have been developed for creating sedimentation-stable aqueous dispersed systems of nanoparticles of copper(II), aluminum, and titanium(IV) oxides. Nanoparticles are stabilized by the nonionic surfactant Tween 85 at its optimal concentration of 3 mmol/L and with a metal oxide content up to 0.2 g/L. It has been shown that stable dispersed systems of particles are obtained by adding a surfactant to the initial system, followed by diluting it with distilled water and ultrasonic dispersion. Scanning electron microscopy has shown that nanoparticles of copper, aluminum and titanium oxides have a spherical shape. Highly stable dispersed systems with a narrow particle size distribution have been obtained: 20 nm for Al₂O₃, 40 nm for CuO, and 30 nm for TiO₂ after membrane filtration of the initial dispersed systems. Electrokinetic studies have shown that the surface of nanoparticles of copper, aluminum and titanium oxides becomes negatively charged when stabilized by Tween-85. The average ξ-potential value is –(20 ± 5) mV. The study of the kinetics of growth and stability of nanoparticles has showed that titanium oxide nanoparticles have higher aggregation stability compared to copper and aluminum oxides under the same conditions. The stability time of the obtained samples is approximately 1.5 months.