Study on sorption of Cs from aqueous solution by microcapsules enclosing natural minerals

Zeolite, a natural mineral (Na₈(AlO₂)₈(SiO₂)₄₀·20H₂O) with an exchanger having high selectivity toward Cs, was encapsulated in a biopolymer matrices (sodium alginate, NaALG). The sorption of Cs on different microcapsules was investigated using batch methods under different conditions, such as time (1–24 h), acid (0.1–6 M HNO₃), and salt concentration (0.001–1 M NaCl). Spherical and elastic granules were obtained, and the particle size of the microcapsules was about 700 μm. A relatively high sorption ratio of Cs (above 90 %) for MCs enclosing zeolite was obtained in the presence of 0.1–6 M HNO₃ and 0.001–1 M NaCl solutions, with an equilibrium being attained within 5 h. The sorption isotherm of Cs followed a Langmuir-type equation. The relatively larger K_d value, 120 and 50 cm³/g, for Cs showed a selective sorption property in the presence of various metal ions under 2.5 M HNO₃ and 1 M NaNO₃.