Emulsion preparation of ultralight TiO2 foams for selective oil absorption

Abstract

Ultralight TiO2 foams have been prepared by an emulsion route using mesoporous TiO2 microbeads (MTMs) as a raw material in water medium followed by mechanical frothing and calcination at elevated temperatures. The MTMs are modified by preferential adsorption of hexadecylamine in ethanol prior to the emulsion practice so that the surface became hydrophobic for facilitating formation of stable air-in-water bubbles. The TiO2 foams are featured with cellular spherical macropores with an interconnected pore structure in a pore-size range from ca. 10 to 400 μm and a porosity ranging from 85.8 to 95.6 % (corresponding to a bulk density of 0.06 to 0.24 g⋅ cm−3). The foams can float on oil/water mixtures and absorb oil selectively in short period of time without noticeable degradation under recycled use, e.g., absorption of soybean oil with up to 15 times of the foam weight has been obtained in less than 30 s after the third use.