Amorphous nanoparticles in clays, soils and marine sediments analyzed with a small angle X-ray scattering (SAXS) method

Abstract

This paper describes the amounts and size distributions of amorphous nanoparticles in clays, soils and marine sediments, and the effect of amorphous nanoparticles on the properties of clays, soils and marine sediments. So far aluminum–silicate amorphous nanoparticles such as allophane were observed only in soils of volcanic origin with a transmission electron microscope, and thus most people believed that aluminum–silicate amorphous nanoparticles were present only in soils of special origin. Recently, a method has been devised to quantify amorphous nanoparticles by using small angle X-ray scattering intensity. Using the method, we have quantified amorphous nanoparticles in clays, soils and marine sediments, and have found that all clays, soils and marine sediments measured in this study contain large amounts of amorphous nanoparticles. On the basis of this result, we have concluded that large amounts of amorphous nanoparticles are ubiquitously formed from rocks when the rocks are weathered or altered. We have also found that the amorphous nanoparticles affect the properties of clays, such as adsorption properties and plasticity. These findings show that amorphous nanoparticles play an important role in clays, soils and marine sediments.