Reductive immobilization of Re(VII) by graphene modified nanoscale zero-valent iron particles using a plasma technique

Technetium-99 (Tc-99), largely produced by nuclear fission of U-235 or Pu-239, is a component of radioactive waste. This study focused on a remediation strategy for the reduction of pertechnetate (TcO4-) by studying its chemical analogue rhenium (Re(VII)) to avoid the complication of directly working with radioactive elements. Nanoscale zero-valent iron particles supported on graphene (NZVI/rGOs) from GOs-bound Fe ions were prepared by using a H-2/Ar plasma technique and were applied in the reductive immobilization of perrhenate (ReO4-). The experimental results demonstrated that NZVI/rGOs could efficiently remove Re from the aqueous solution, with enhanced reactivity, improved kinetics (50 min to reach equilibrium) and excellent removal capacity (85.77 mg/g). The results of X-ray photoelectron spectroscopy analysis showed that the mechanisms of Re immobilization by NZVI/rGOs included adsorption and reduction, which are significant to the prediction and estimation of the effectiveness of reductive TcO4(-) by NZVI/rGOs in the natural environment.