Sorption of technetium on inorganic sorbents and natural minerals

Abstract

The sorption behavior of the pertechnetate anion in various solid-solution systems under aerobic conditions and pH 1.3–12.5 has been investigated. Batch techniques were employed. On most of natural minerals only surface adsorption occurs. R_s-values were no larger than 2.0 ml · g⁻¹. Adsorption on various natural minerals and rocks such as sandstone, basalt, granite, pyrite, peat and others are comparaed with the analogous processes on artificial inorganic sorbents: titanium oxides (thermoxide-34, thermoxide-3), crystaline cadmium sulfide, zirconium phosphate, and complex inorganic sorbents: antimony oxide — silicon oxide — phosphorus pentoxide, antimony oxide — silicon oxide — aluminium oxide, lithium oxide — manganese oxide — aluminium oxide — water, lithium oxide — titanium oxide —chromium oxide — water. For comparison the sorption of Tc on some organic sorbents was included. The solubility of Tc₂S₇ in water was measured to be 0.257 g/l. It has been shown that preliminary irradiation of sorbents such as sandstone, peat and humic acid by γ-rays with doses not less than 10⁷ rad results in the decrease of Tc(VII) sorption.