Functionalization of carbon nanomaterials by means of phytic acid for uranium enrichment

A promising strategy for radionuclides immobilization on the functionalized carbon-based materials is a pursuing issue. Here, we developed phosphorylated hydrothermal carbon spheres (HCSs@PO₄) through chemical-grafted method using phytic acid as a phosphorus source. When served as U(VI) scavenger from simulated environmental wastewater, the resulting HCSs@PO₄ showed excellent adsorption capacity toward U(VI) (552.49 mg·g^-1 at pH 5.0 and T = 298 K), outperforming that of HCSs (32.06 mg·g^-1) and state-of the-art materials. A weak ionic strength-dependence of U(VI) enrichment with HCSs@PO₄ was investigated by a series of pH experiments, indicating an inner-sphere surface complexation. Through thermodynamic study, high temperature promoted the adsorptive ability of HCSs@PO₄ toward U(VI), revealing the endothermic and spontaneous nature. Additional selective adsorption applications were conducted to evaluate the ability of HCSs@PO₄ to capture uranium fission byproducts and other radioactive ions. Analyses of characteristic means (FT-IR and XPS) revealed enhanced uptake performance of HCSs@PO₄ originated from grafting abundant phosphate groups, which exhibited the stronger surface complexation toward U(VI) than sluggish hydroxyl and carboxyl groups. The findings herein highlighted a facile and powerful technique for the manufacture of phosphorylated carbon-based materials of radioactive wastewater remediation.