The effect of humic acid and competing cations Na+ and Ca2+ on the sorption of uranium and europium, onto bentonite from Kimolos Island (Greece)

The effect of humic acid (HA) and competing cations Na+ and Ca2+ on the sorption of uranium and europium onto bentonite was studied by batch experiments in aqueous solutions. Sorption isotherms were obtained and simulated satisfactorily by Langmuir and Freundlich models and thermodynamic parameters (ΔH0, ΔS0 and ΔG0) were calculated. The results showed that the sorption was significantly depended on pH, initial concentration, sorbent mass, presence of HA and competing cations and temperature and found to increase in the presence of HA. Several techniques such as Fourier Transform Infrared spectroscopy, X-ray powder diffraction, Scanning Electron Microscopy as well as determination of BET-surface area were applied to support the investigation.