X-ray Absorption Spectroscopy (XAS) Characterization of Thallium Adsorption in Zeolites from Contaminated Natural Waters

This project investigates adsorption and sequestration of toxic trace metals from contaminated waters using porous materials,
focusing on natural/synthetic zeolites and MOFs. Initial tests under real conditions assessed efficiency and selectivity. The study
concentrates on thallium (Tl) uptake, aiming to identify incorporation sites and clarify coordination and bonding. Adsorption experiments with
synthetic solutions (Tl(I), As(IV), Se(IV), Sb(III)) and real waters employed zeolites (LTL, ferrierite, beta-25, 13X, clinoptilolite) and ZIF-8. High
removal was achieved for Tl(I), As(IV), and Se(IV), with consistent Tl(I) uptake except in ZIF-8. PXRD Rietveld refinement revealed site-specific
Tl+ incorporation in LTL and ferrierite. Experiments on waters from Monte Amiata and Raibl confirmed Tl adsorption by ICP-MS. Due to low
concentrations and complex matrices, XAS is proposed to determine oxidation states and coordination, providing molecular-scale insight into
retention mechanisms.