Nanoscale zero-valent iron particles for the remediation of plutonium and uranium contaminated solutions

Abstract

In the current work the uptake of plutonium onto nanoscale zero-valent iron nanoparticles (nZVI) under anoxic conditions has been investigated. A uranyl solution was also studied under similar geochemical conditions to provide a comparative dataset. Following nZVI addition, a rapid and significant decrease in aqueous actinide concentration was recorded for both systems. The removal rate recorded for plutonium was slower, with 77% removal recorded after 1 h of reaction, compared to 99% recorded for uranium. Low aqueous contaminant concentrations (<25%) were then recorded for both systems until the end of the 7 day reaction period. XPS confirmed contaminant uptake onto the nZVI. For the plutonium system, the recorded photoelectron spectra exhibited Pu 4f lines centred at ∼439 and ∼427 eV, characteristic of Pu4+ and implying that chemical reduction of the sorbed plutonium had occurred, ascribed to the formation of PuO2. Similarly, with the U-system, the recorded U 4f photoelectron peaks were centred at energies of ∼380 and ∼391 eV, characteristic of U4+ in UO2. Results provide clear evidence that nZVI may be used as an effective material for the removal of plutonium from contaminated waters.