Crystal-Chemical Features and Sorption Properties of Natural and Synthetic Smectites

Abstract

Sorption of uranyl ions from uranyl nitrate UO₂(NO₃)₂ · 6H₂O solutions by natural and synthetic layered silicates was studied by X-ray diffraction, IR spectroscopy, and high-resolution inductively coupled plasma mass spectrometry. The modifications of some structural parameters of the studied species after they were reacted with uranyl ions are due to a partial incorporation of uranyls into the interlayer spaces of the smectite structure, or the rotation of the tetrahedra of a tetrahedral network and the distortion of octahedra in an octahedral layer. The natural bottom clay samples from the Pacific Ocean and the Sea of Okhotsk have the best sorption properties. This is due to structural defects and the formation of uranium complexes with the iron ions of the smectite structure. Iron present in clay minerals improves their sorption potentials.