Computational Study on the Membrane Separation Mechanism of Actinide Ions by Graphene Oxide

Mastering the adsorption and diffusion behavior of actinide metal ions on graphene oxide at the molecular level is of great guiding significance for its application in the treatment of low radioactive wastewater. The highly dense oxygen-containing functional groups on the graphene oxide surface can tightly anchor metal ions and regulate a precise interlayer spacing for membrane separation. Through multiscale theoretical calculations, we found that graphene oxide does have strong adhesion to actinide metals, but this attraction does not directly come from the interaction between functional groups of graphene oxide and actinide ions but actually from the strong hydrogen bond binding effect. Taking advantage of the binding effect difference between the actinide ion's spherical coordination field and the actinyl ion's equatorial coordination field, graphene oxide can act as a molecule sieving separation membrane for these two types of ions. In addition, we found that graphene oxide has the ability to oxidize actinide metal ions and thus can serve as both an adsorbent material and a valence state regulator. Our research suggests that graphene oxide is a promising membrane material for low radioactive wastewater treatment.