engleski

Removal/preconcentration of Cs and Pb ions by natural clinoptilolite and synthetic Zeolite 4A

Zeolites are widely explored and used as ion- exchange agents for the removal of radionuclides present in the liquid effluents of low and intermediate activity level. The aim of the study was to determine sorption properties of natural clinoptilolite-rich zeolite (ZZ) and synthetic zeolite 4A (Z4A), in order to screen and compare their applicability for interventions in accidental pollution by Cs and Pb and for analytical purposes. The equilibrium sorption data were collected in batch mode, using stable Cs and Pb nitrate salts in a wide range of concentrations. The affinities and the maximum sorption capacities of both materials were higher for Pb ions, whereas Z4A exhibited a higher capacity to remove both cations in respect to ZZ. Additionally, the performance of Z4A in radionuclide separation was tested using tap water and seawater samples spiked with 137Cs and 210Pb. Recovery of 137Cs and 210Pb was 84.8 % and 95.6 % from tap water and 10.9 % and 95.6 % from seawater. High-efficiency separation of 210Pb from water samples with a quite different background composition can be utilized for analytical purposes, as a fast preconcentration step. Comparative study of Cs and Pb removal by ZZ and Z4A confirms general ability of zeolites to sequester cationic pollutants and highlights particularly high capacity of the synthetic product. Although both materials can find use in the prevention of pollution and remediation of contaminated water, higher capacity of Z4A provides less solid waste for further treatment and storage. Furthermore, observed selectivity of Z4A towards radionuclide cations present in the samples of tap water or even seawater, suggests that the further research should be focused on its use in radioanalytical chemistry.

cesium ; lead ; radioactivity ; zeolites

Hrvatsko-srpski bilateralni projekt: Istraživanje sorpcije radionuklida na umjetne i prirodne materijale sa naglaskom na potencijalne primjene u analitici i /ili sigurnom uklanjanju radionuklida