Influences of Thermal, Hydrothermal, and Mechanical Treatments

The morphology of nanooxides is sensitive to any treatment such as thermal, hydrothermal, and mechanical because of nonrigid binding of nanoparticles in aggregates, aggregates in agglomerates 

Characteristics of Two Samples of Nanosilica A-300 Differently Hydrated Due to Synthesis Conditions 

For one of nanosilica A-300 samples shown in Table 1.30, synthesis conditions corresponded to 30% excess of oxygen and hydrogen in comparison with their stoichiometric contents in respect to SiCl4 to provide a high degree of hydration of particles (No 1, Table 1.30). 

To produce lowly hydrated sample A-300 (No 2, Table 1.30), the flame temperature was elevated, and the amounts of oxygen and hydrogen were lower than their stoichiometric concentrations. Prepared samples were subjected to heating at different temperatures (200°C-900°C) for tj= 10-160 min and studied right away and after aging during several months by means of the adsorption methods. 

For instance, removal of interior intact and structural waters and surface hydroxyls can reduce the size of primary particles enhancing S. However, rearrangement of aggregates of primary particles 

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