Sorption of thorium from aqueous solutions onto natural and modified zeolites

A natural HEU-type zeolite from Greece was embedded with iron oxyhydroxides via a simple and fast precipitation method following acid pretreatment. The raw and modified materials were subsequently evaluated as sorbents for thorium removal from acidic aqueous solutions. Surface techniques (BET, pHpzc) and structural characterization methods such as Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) were implemented for both materials before and after metal sorption. The experimental results were used for the construction of sorption isotherms while the data were also fitted using mathematical models for a brief insight into the sorption mechanism accompanied by kinetic and thermodynamic studies. Results showed that the modification process caused changes in the characteristics of the precursor material and that thorium uptake was greatly affected by the presence of iron oxyhydroxides.