Distribution coefficients of americium, neptunium, and protactinium for selected rocks

Distribution coefficients (KD) were measured by a batch technique for sorption-desorption of americium (III), neptunium (V), and protactinium (V) between granite, tuff, of quartz mined in Japan, and water. Measurements were performed at room temperature. The effects of the surface area, pH, and the separation method of solid and liquid phases were studied. The KD values of americium ranged from 50 to 370000 (mL/g), depending much on the separation methods adopted due to the presence of colloidal particles of americium in solutions. The KD values of neptunium were small (0.67 - 13 mL/g), and were little affected by the experimental conditions employed. Protactinium had intermediate values of KD. The physical adsorption was suggested in the sorption experiments for americium on latex particles. (author)