The properties of amorphous nano-silica synthesized by the dissolution of olivine

This study addresses the synthesis of amorphous mesoporous nano-silica by the dissolution of olivine in sulfuric acid, showing the influence of the process conditions on the properties of nano-silica. The olivine dissolution process is a convenient alternative to the traditional methods of nano-silica production; and that is because the low energy requirement makes it possible to use this material in new fields where previously its price was prohibitive. The produced nano-silica has a specific surface area between 100 and 300 m2/g and a particle size between 10 and 25 nm. These particles are agglomerated in clusters forming a mesoporous material with an average pore diameter around 20 nm. The impurity content is below 5%, and the silica yield of the process in the range of 54 to 83 %. When the separation of the silica is carried out by filtration, the textural properties of the material have a direct influence on the separation efficiency. The texture and specific surface area of nano-silica depends on several factors of the process, the main ones being the kinetics of the dissolution of olivine and the washing steps of the nano-silica. Thus, the properties of this nano-silica can be tailored by changing the process conditions