Investigation of interaction between U(VI) and carbonaceous nanofibers by batch experiments and modeling study

Carbonaceous nanofibers (CNFs) were synthesized using tellurium nanowires as a template and using glucose as carbon source by the hydrothermal carbonization method. The sorption capacity and mechanism of U(VI) on CNFs were investigated by a combination of batch sorption experiments, the double layer model (DLM) and X-ray photoelectron spectroscopy (XPS). The sorption edges were modeled well by considering the following surface complexes: SOUO2(+), SOUO2OH, SOUO2(OH)2(-) and SOUO2(OH)3(2-) on the strong site as well as XOUO2OH and XOUO2(+) on the weak one (S and X represent surface). The sorption isotherms could be well fitted by the DLM parameters. The difference between type A (SOUO2OH and XOUO2OH) and type B (SOUO2(+) and XOUO2(+)) was observed in XPS because the former species are of low binding energy while the latter are of high one. Desorption and recycle experiments showed that CNFs had good reusability and stability in the present of common sodium salts within five rounds. When co-existing with montmorillonite, CNFs could extract the sorbed uranium onto their surface by a pseudo-second order kinetic process. As a new sort of environmental functional nanomaterials, CNFs should be paid more attention in the area of separation and wastewater remediation.