Enhancement of U(VI) sorption in natural soils at prospective high-level radioactive waste geological disposal sites with Fe(OH)3-humic acid composite colloids

We examined these characteristics both in the presence and absence of composite colloids composed of Fe(OH)3 and humic acid. To comprehensively understand the adsorption process, we conducted static batch experiments for varying pH, solid contents, and initial U(VI) concentrations. We analyzed the adsorption kinetics and employed microscopic characterization technology to analyze soil samples before and after adsorption, enabling detailed elucidation of the adsorption mechanism. Our findings revealed that the presence of composite colloids leads to a significant increase in the number of adsorption sites and facilitates U(VI) adsorption by the soil, with a 1.48 times increase in the adsorption percentage. The adsorption process closely follows the pseudo-second-order kinetic model. We inferred that U(VI) primarily adheres to the soil surface through surface complexation and ion exchange reactions. These results provide a robust scientific foundation for predicting the migration of uranium in underground porous media and for evaluating the safety of high-level radioactive waste repositories.
Source: Journal of Radioanalytical and Nuclear Chemistry - Category: Nuclear Medicine Source Type: research