Reduction of Tc(VII) by Fe(II) sorbed on Al (hydr) oxides.

Journal Article · Fri Aug 01 04:00:00 EDT 2008 · Environ. Sci. Technol.

DOI:https://doi.org/10.1021/es8003156· OSTI ID:939084

Peretyazhko, T; Zachara, J M; Heald, S M; Kukkadapu, R K; Liu, C; Plymale, A E; Resch, C T; PNNL,

Under oxic conditions, Tc exists as the soluble, weakly sorbing pertechnetate [TcO{sub 4}{sup -}] anion. The reduced form of technetium, Tc(IV), is stable in anoxic environments and is sparingly soluble as TcO{sub 2} {center_dot} nH{sub 2}O{sub (S)}. Here we investigate the heterogeneous reduction of Tc(VII) by Fe(II) adsorbed on Al (hydr)oxides [diaspore ({alpha}-AlOOH) and corundum ({alpha}-Al{sub 2}O{sub 3})]. Experiments were performed to study the kinetics of Tc(VII) reduction, examine changes in Fe surface speciation during Tc(VII) reduction (Moessbauer spectroscopy), and identify the nature of Tc(IV)-containing reaction products (X-ray absorption spectroscopy). We found that Tc(VII) was completely reduced by adsorbed Fe(II) within 11 (diaspore suspension) and 4 days (corundum suspension). Moessbauer measurements revealed that the Fe(II) signal became less intense with Tc(VII) reduction and was accompanied by an increase in the intensity of the Fe(III) doublet and magnetically ordered Fe(III) sextet signals. Tc-EXAFS spectroscopy revealed that the final heterogeneous redox product on corundum was similar to Tc(IV) oxyhydroxide, TcO{sub 2} {center_dot} nH{sub 2}O.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 939084
• Report Number(s): ANL/XSD/JA-61787
• Journal Information: Environ. Sci. Technol., Journal Name: Environ. Sci. Technol. Journal Issue: 15 ; Aug. 1, 2008 Vol. 42; ISSN ESTHAG; ISSN 0013-936X
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ALUMINIUM HYDROXIDES
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHEMICAL REACTION KINETICS
CORUNDUM
IRON
PERTECHNETATES
REDUCTION
TECHNETIUM OXIDES