DERIVATIVE-THERMOGRAVIMETRIC ESTIMATION OF KAOLIN MINERALS IN SOILS

Abstract

The estimation method of kaolin minerals with the DTG peak near 500°C and the ignition loss of the clay fraction was proposed, and was effective for estimating the minerals in soils by the following reasons. The content of kaolin minerals obtained here was almost proportional to their ratio in the artificial mixture with montmorillonite although their contents were slightly higher than the value expected from the mixed ratio, and the linearity of the XRD graph was inferior to that of DTG. The DTG peak of kaolin minerals was separated almost completely from the neighboring peaks originated in montmorillonite and chlorite. This separation was considerably difficult in the TG curve.
Kaolin minerals in six Amazon soils were estimated by this method, and their contents were from 230 to 820 g·kg^-1.