Figure 3.
Methods used for characterisation of silica species in solution and in the solid state. A: nitrogen gas adsorption analysis of a fumed silica(small particles treated at high temperature); grey lines and a silicalite; black lines. B: ESI/MS mass spectrometric data for a solution of silica (30 mM dm-3) dissolved in a 12.5% wgt/vol solution of tetramethylammonium hydroxide after heating to 60°C for 8 hours to aid solubility. C:scanning electron microscopy images of silica extracts from Curcurbita (marrow) leaves. D: solid state 29Si nmr of silicon species in Q° to Q4 coordination environments.