TRANSMISSION ELECTRON MICROSCOPY AND FOURIER-TRANSFORM INFRARED SPECTROSCOPY STUDIES OF CHRYSOTILE DISSOLUTION USING A FLOW-THROUGH METHOD

Abstract

The dissolution properties of chrysotile in vivo were investigated to reveal the changes in its morphology and structure. Dissolution experiments with a pseudo-biological fluid (pH 7.4) in the flow system revealed that erosion due to dissolution was greater on the outer surface than on the inner surface, with dissolution occurring preferentially in the brucite octahedral layer. The dissolution of chrysotile in the batch system under acidic conditions exhibited an increase in pH due to the dissolved OH⁻ ions; as the pH increased, the rate of dissolution decreased. In the dissolution of chrysotile in the flow system under acidic conditions, the dissolution reaction proceeded faster than in the batch system because of the constant pH. Preferential dissolution of Mg from the chrysotile fibers on the fiber bundle surface was observed. As the dissolution reaction proceeded, the octahedral layers of magnesium hydroxide were destroyed, and resulting in two distinct changes in the morphology of chrysotile. One was in the fibrous form of linked nanoparticles, whereas the other was in the form of sheets.