Hydrophobic precipitation of carbonaceous spheres from fructose by a hydrothermal process

We report a new mechanism of hydrophobic ripening for the formation of carbonaceous spheres by the dehydration of saccharides in a hydrothermal aqueous environment using fructose as a model precursor material. We investigated the formation of carbonaceous spheres from fructose in aqueous solutions under hydrothermal conditions. The spheres were found to contain 65.7 wt.% C, 4.3 wt.% H and 30.0 wt.% O, implying incomplete dehydration of the fructose. The spheres, typically ranging between 400 nm and 10 mu m in diameter, are found to be constructed entirely of primary particles of similar to 5 nm. The chemical structure of the carbonaceous spheres and the chemical compositions of residual solutions were analysed using solid state and solution C-13 nuclear magnetic resonance and Fourier transform infrared spectroscopy. Based on these results, a four-step mechanism for the formation and growth of carbonaceous spheres has been proposed. (C) 2012 Elsevier Ltd. All rights reserved.