An X-ray photoelectron study of the interaction of uranyl group with sulfosuccinyl chitosan

Interaction of uranium with low-molecular-weight sulfosuccinyl chitosan (SSLMWC) from sulfate solutions was studied by X-ray photoelectron spectroscopy. The interaction involves formation of complexes with the uranyl group on the SSLMWC surface. The equatorial plane of these complexes can contain nitrogen atom of the amino group and oxygen atoms of the sulfato and sulfo groups SO₄²⁻ and -SO₃H, carboxy groups, and free hydroxy groups. On keeping the complex in a vacuum, two chemically nonequivalent states of U ions, U⁴⁺ and UO₂²⁺, are observed. The U⁴⁺ formation in solid U-containing samples of chitosan and SSLMWC is attributed to the radical reaction of the UO₂²⁺ reduction with the primary hydroxy group of chitosan in a vacuum of the spectrometer under the action of X-ray radiation.