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 54–83%. 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.

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► The dissolution of olivine produces an amorphous nano-silica of high quality.
► The SSA of this nano-silica is between 100 and 300 m2/g.
► Olivine nano-silica has primary particles of 10–25 nm agglomerated in clusters.
► Olivine nano-silica is mesoporous with an average pore size around 20 nm.
► The texture of this silica depends on the olivine kinetics and the washing steps.