https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 The short-term reduction of uranium by nanoscale zero-valent iron (nZVI): role of oxide shell, reduction mechanism and the formation of U(v)-carbonate phases https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32238 VI) with fresh, (anoxic) aged and corroded nZVI particles was investigated under aqueous conditions conducive to the formation of thermodynamically stable U(VI)-Ca-CO₃ ternary aqueous complexes. The first stage of the reaction between U(VI) and nZVI was assigned to sorption processes with the formation of surface U(VI)-carbonate complexes. Aged nZVI removed U(VI) faster than either fresh or corroded nZVI and it is hypothesized that U reduction initially occurs through the transfer of one electron from Fe(II) in the nZVI surface oxide layer. Evidence for reduction to U(V) was obtained through X-ray photoelectron spectroscopy and by determination of U-O bond distances of ~2.05 and 2.27 Å, using U LIII -edge X-ray absorption spectroscopy, which are similar to those observed for the U(v) site in the mixed U(v)/U(VI) carbonate mineral wyartite. Scanning transmission electron microscopy also demonstrated that U was present as a nanoparticulate phase after one day of reaction, rather than a surface complex. Further reduction to U(IV), as observed in previous studies, would appear to be rate-limiting and coincident with the transformation of this meta-stable U-carbonate phase to uraninite (UO).]]> Tue 15 May 2018 16:00:13 AEST ]]> Functional chitosan-stabilized nanoscale zero-valent iron used to remove acid fuchsine with the assistance of ultrasound https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24054 Sat 24 Mar 2018 07:09:41 AEDT ]]>