The Fe(III) uptake from aqueous solutions by natural and chemically modified zeolites was investigated using a gradual radioexchange
method and AAS technique. The leachability of Fe(III) from loaded zeolites was studied too. The Fe-uptake reached the value
of 60 mg·g−1 for the zeolite chemically treated with 6 mol·l−1 solution of NaOH and it is more than twelve times higher than that of the raw zeolite. The leachability of the loaded zeolite
samples in water and alkaline solution was up 5%. The leachability of the same zeolites in acid solution depended on the concentration
of modifying solution. The leachability at pH=2.6 in the range 2–20% at pH=1.9 was many times higher. The results of the radioexchange
and AAS methods were compared.