Adsorption of uranium ions on nano-hydroxyapatite modified by silver (Ag-HAP) and calcium (Ca-HAP) ions was examined. Composites or studied adsorbents were studied by means of XRD, ASAP and DLS molecules sizes. The Langmuir, Freundlich, and Dubinin-Radushkevich models were applied to describe the adsorption isotherms. The maximum adsorption capacity (q m) was found to be 8.1 mmol/g for Ca-HAP and 7.2 mmol/g for Ag-HAP at 293 K. The mean free energy values evaluated from the D-R model indicated that the adsorption of U(VI) ions on the adsorbents proceeds as the chemisorption mechanism. The adsorption equilibrium was reached for both sorbents after 120 min. The adsorption kinetics followed the pseudo-second-order model. There were determined basic parameters characterizing the double electrical layer at the nano-HAP/electrolyte and Ag-HAP/electrolyte, Ca-HAP/electrolyte inters faces: density of the surface charge and zeta potential.

Uranium is more and more extensively applied as a source of energy and can be potentially used for nuclear weapon production. Owing to that fact, the problem of uranium expansion in the environment is the object of research and draw attention many scientists. One of the most effective methods of uranium removal from the wastewater (where uranium is present in a low concentration and occurs mainly in the form of uranyl ion, UO22+) is the adsorbent usage. It is important to discover an adsorbent which will be effective, widely available and cheap. The paper discusses properties and the ability of U (VI) adsorption on a clay and nanocomposite clay/Hap (hydroxyapatite) obtained by wet method. The adsorbents were characterized by the mentioned below tests: XRD, XRF, the porosity (nitrogen adsorption–desorption method), zeta potential, surface charge density and sorption of U (VI). It was shown that nanocrystalline composites Hap/white clay can be appropriate adsorbent for removal of uranyl ions. The adsorption depends on the temperature and pH of the solution.

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