The Influence of Preparation Conditions on Porous SiO2 Structure Studied by FTIR Spectroscopy
a Department of Chemistry and Technology of Inorganic Materials, Faculty of Industrial Technologies, Alexander Dubček University, Trenčín, b Department of Chemistry, Pedagogical Faculty, Technical University, Liberec
Surface area, porosity, pore structure and ability to bind to other substances are very important properties in various applications of porous SiO2. The properties are largely dependent on SiO2 structure, which is influenced by its preparation. Porous SiO2 was prepared by coagulation of solutions of an alkali metal silicate. The influence of temperature and pH on the structure of porous SiO2 was studied by FTIR. It was found that the siloxane four-membered rings along with the expected six-membered rings occurred as basic structural units in all the prepared materials. An increase in pH leads to a significant decrease in the content of the four-membered rings and a decrease in the Si-OH/Si-O− ratio in the silica network. However, the relative amount of Si-OH groups increases. Temperature has no significant influence on the amount of different structural units.
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