ASTM D6739 Standard test method for Silica – pH Value

Scope:

The ASTM D6739 test method determines the pH of a 5% silica/water mechanical dispersion and is indicative of the relative acidity or basicity of the silica. When the pH is less than 8.5, the production of amorphous silica is promoted.

Procedure:

Inthis ASTM D6739 test method a pH meter, mortar, and pestle are used. The silica is granulated to a fine powder and transferred into a glass beaker. Two buffer solutions with pH values of 4.0 and 7.0 are used to calibrate the pH meter. After each test, the electrode is washed with distilled water. Record the pH to the nearest 0.05 pH unit.

Video 01: Procedure to test silica

Specimen: 

In ASTM D6738, particle size ranges from 20 nm to 200 nm, by controlling the temperature of the reaction.

Data: 

The volatile material is given by the following equation:

% Volatiles = [ (W₂-W₃)/(W₂-W₁)] ×100

where,

W= weight of the pan

Conclusion:

ASTM D6738 includes determining volatile content in precipitated silica.