Potential application of graphene oxide membranes in high-level liquid waste treatment

The drawbacks of current high-level liquid waste (HLLW) separation processes would bring some adverse effects on the sustainable and clean utilization of nuclear power. In this work, a novel separation method for HLLW treatment based on graphene oxide membranes (GOMs) was investigated. Effects of nitric acid concentration and membrane thickness on the permeation behaviors of typical ions through GOMs were systematically investigated. On the whole, the permeation rates were in the order: hydrogen ion, cesium ion > sodium ion > strontium ion > europium ion, uranyl ion > thorium ion, which could be well explained by size exclusion and chemical interaction. As the nitric acid concentration decreased, strong coordination cations were generally restrained from migrating through GOMs due to cations hydrolysis and deprotonation of graphene oxide sheets. Ions permeation was supposed to be a two-step process which included entrance to the membrane and intramembrane migration. Based on the favorable rejection of f-block elements, GOMs separation showed promising potential in HLLW treatment. Furthermore, a new technical route for HLLW separation was proposed which showed superiority of simplified process, low running cost, less secondary radioactive waste production.