In this work a natural zeolite was modified with silver following two different methods to
derive Ag2O and Ag0 nanocomposites. The materials were fully characterized and the results showed
that both materials were decorated with nanoparticles of size of 5–25 nm. The natural and modified
zeolites were used for the removal of iodide from aqueous solutions of initial concentration of
30–1400 ppm. Natural zeolite showed no affinity for iodide while silver forms were very efficient
reaching a capacity of up to 132 mg/g. Post-adsorption characterizations showed that AgI was formed
on the surface of the modified zeolites and the amount of iodide removed was higher than expected
based on the silver content. A combination of experimental data and characterizations indicate that
the excess iodide is most probably related to negatively charged AgI colloids and Ag-I complexes
forming in the solution as well as on the surface of the modified zeolites.
