Silica Impurities Removal on Bentonite Sample for Nanoclay Production

Removal of silica impurities on Reshm bentonite sample of Semnan province in Iran was investigated .
Two processes of hydrocyclone and sedimentation treatment with sodium hexametaphosphate were used aiming for nanoclay production. Mineralogical studies indicated that the treated sample was a low grade Na-bentonite. The dominant impurities were cristobalite and quartz with low amounts of feldspar, gypsum, dolomite, calcite and zeolite. The Purification of the sample was processed by two methods of hydrocyclone and sedimentation treatment with sodium hexametaphosphate as depressant. The purified product was intercalated with octadecylamine. The evaluation of products was performed by XRD analysis. The purification results showed that hydrocyclone process failed to produce a purified montmorillonite product suitable for nanoclay application. Using sedimentation treatment with sodium hexametaphosphate as a depressant, a product with impurities of less than 5 percent, suitable for nanocaly application, can be produced. Intercalation of purified montmorillonite by octadecylamine showed that the application of sodium hexametaphosphate increase the basal spacing up to 36 °A.