Adsorption of 241Am and 226Ra from natural water by wood charcoal

The adsorption of 241Am and 226Ra from natural water by a granulated wood charcoal was investigated as a function of the solution pH, in the range 4–10, and of the water flow, in the range 3.5–42 cm3/min. The percentage adsorption of 241Am (fairly constant at >80% for all pHs) was greater than that of 226Ra (which increased with increasing pH from ∼40% up to >80%). The results are explained by considering the different species of each radionuclide present at the pH values of the solution at the end of the adsorbent column, and the pH of the point of zero charge of the adsorbent. At pH 6, the elimination of 241Am from natural water was independent of the water flow, while the elimination of 226Ra declined linearly as the flow rate was increased.