Effect of Humic Substances on Americium (III) Retention onto Silica

Abstract

ABSTRACTThe migration/retention phenomena of radionuclides in geological systems are of great interest for the safety assessment of a nuclear disposal. Interactions at solid/liquid interfaces play a significant role in the speculation and transport of radionuclides in aquifer systems. Oxide surfaces and humic substances which occur in natural waters in large concentration ranges (from few mg/1 to several hundred mg/1) may have a major influence on radionuclides behaviour. For this purpose, studies have been carried out on a ternary system: oxide-humic substances-americium (III). The influence of pH, ionic strength and humic concentration on the adsorption of americium onto silica has been investigated. The ionic strength of the solution (0.1 and 0.01) has little effect on the americium adsorption. In the presence of humic materials, the fixation of americium is enhanced at low pH (pH<5) whereas, at higher pH (pH>5), the adsorption is lowered and dependent of humic concentration.