Emulsion synthesis and transformations of electrokinetic potential of amorphous and crystal TiO2 particles in water, chloroform, n-decane, and n-decane–chloroform mixture

Sols of TiO2 nanoparticles are promising both as the liquid-phase materials in the electrophoretic display (e-book) technology and as the precursors for the formation of various surface films and bulk porous composites with advanced optical, catalytic, photovoltaic and sorption properties. In this work, the synthesis of ultradispersed amorphous TiO2 powders in reverse emulsions stabilized by АОТ is proposed. Sols were obtained from the powders by ultrasonic dispergation in water, n-decane and n-decane–chloroform mixtures. In distinction to commercial nanoparticles, the synthesized amorphous particles in n-decane exhibited a high negative (–55 ± 7 mV) ζ-potential, while in chloroform – a positive (32 ± 3 mV) one. Thermolysis (300–900 °С) of amorphous powders led to the formation of known individual and mixed polymorphous modifications. Surface recharging of amorphous particles was achieved by different methods: by varying the pH of the hydrosol, by dilution of n-decane organosols with chloroform, addition of АОТ, and variation of thermolysis temperature. A wide spectrum of surface charge states and sizes of TiO2 particles in hydro- and organosols was obtained, which makes the produced systems promising for the sorption of both the water-soluble and solvent dyes of different types.