Investigation of uranium-contaminated zeolite solidification mechanism: Experiments and molecular dynamics simulation

Abstract

The uranium (U)-contaminated zeolite waste will influence humans and related ecosystems. Therefore, the contaminated zeolite waste should be treated safely to achieve the effective immobilization of radionuclides. In this work, the U-contaminated zeolite samples were solidified into glass and glass–ceramic forms. The phase, micromorphology, chemical state, and chemical stability of zeolite waste samples were studied. When the U doping amounts were 0–50000 μg/g, the density values of sintered samples increased from 2.13 to 2.48 g·cm⁻³. With the product consistency test method, the NR (normalized leaching rate) of U remained approximately 10⁻⁶ g·m⁻²·d⁻¹ at 42nd day, suggesting that the samples have excellent chemical durability. Molecular dynamics simulation results suggested that the solidified body consisted of [AlO₄] and [SiO₄] tetrahedrons and [AlO₄] tetrahedrons were less rigid than [SiO₄] tetrahedrons. This study will offer valuable insight into the management of radioactive zeolite waste during the subsequent stage.