XPS determination of the oxidation state of <sup>99</sup>Тс isotope absorbed on the surface of pirrhotite Fe<sub>n</sub>S<sub>n+1</sub> and stibnite Sb<sub>2</sub>S<sub>3</sub>

Sorption of pertechnetate on pyrrhotite FenSn+1 (I) and stibnite Sb2S3 (II) from distilled water was evaluated. The distribution coefficients were found to be 185 and 223 cm3/g, respectively. The XPS study of the chemical state of 99Tc absorbed on the surface of pyrrhotite and stibnite from aqueous solution of potassium pertechnetate (KTcO4) was carried out. It was found that Tc(IV) ions are present mostly on the surface of the studied samples, their concentration was 5.7 times higher on the surface of pyrrhotite compared to that on the surface of stibnite. A 13% admixture of Tc(VII) ions on the surface of pyrrhotite was observed.