Characterization of uranium(VI) sorption by organobentonite

The U(VI) sorption on the bentonite modified by hexadecyltrimethylammonium bromide (HDTMA) was studied in the concentration range: 0.0001-0.001 mol/dm(3) in the aqueous phase and in the pH range: 3-10. The experiments concerning the pH influence on the molar absorption coefficient c(b) of U(VI) in the bentonite phase showed that the species: UO(2)(2+), UO(2)(OH)(+), UO(2)(OH)(2) UO(2)(OH)(3), UO(2)(OH)(4)(2), (UO(2))(3)(OH)(5)(+), (UO(2))(3)(OH)(7), present in the aqueous phase, are responsible for uranium sorption. Their sorption parameters K were determined and it is evident that for higher concentrations of HDTMA(+) cations in the bentonite phase, i.e. for b96-b157 bentonite, the presence of anionic species: UO(2)(OH)(3), UO(2)(OH)(4)(2), and (UO(2))(3)(OH)(7) in the aqueous phase results in the increase of U(VI) molar absorption coefficient cb in the sorbent phase. (C) 2009 Elsevier B.V. All rights reserved.