EN
Two new sorbents for americium(III) removal from an aqueous environment were studied: Volclay bentonite and red clay – both modified by a cationic surfactant (hexadecyltrimethylammonium bromide) and phosphate ions. Sorption of Am(III) was investigated using the batch method. It was concluded that the kinetics of Am(III) sorption on both sorbents can be evaluated based on the pseudo-second-order rate equation. The following two-parameter equations – Langmuir-Freundlich, Temkin, and Dubinin-Radushkevich isotherms – were examined for their ability to model equilibrium sorption data. It was shown that bentonite and red clay modified by phosphate ions exhibited better sorption properties toward Am(III) ions than sodium forms of the adsorbents. This was probably a result of the complexation of Am(III) ions by PO₄ ³⁻ ions immobilized on the adsorbent surface in the form of ionic pairs with surfactant cations. Changes in Am(III) sorption with pH were modeled based on the molar fractions of the particular complexes in the aqueous phase, and it was concluded that Am(CO₃)₃ ³⁻ and Am(OH)₃ species had a predominant influence on the overall sorption process.