Structures and Reactivity at the Water/Mineral Interface
The Helmholtz-funded Young Investigator Group "Structures and Reactivity at the Water/Mineral Interface"was a group funded by the Helmholtz Association from 2013 to 2018. The group worked on understanding the reactions of the actinides (particularly Pu, Am, and Cm) at mineral surfaces on the molecular level. The work is embedded in our institute's efforts to provide reliable information as a basis for the safety case of a potential nuclear waste repository, where the mobility of the actinides will depend on their retention by the surrounding mineral phases.
The ternary system consisiting of actinide, solution, and mineral surface may host a wide range of chemical reactions (see figure). The retention potential of these reactions will vary significantly, which is why a quantification without understanding of the underlying mechanisms of retention is insufficient. As an example, a structurally incorporated ion will only be remobilized, if the host mineral phase dissolves macroscopically, on the other hand "outer sphere" sorption complexes may become unstable by a mere change in ionic strength.
Accurate description of such a system requires the use of cutting edge techniques capable of acquiring molecular information selectively from the mineral surface. To this end, our group focuses on applying surface X-ray diffraction techniques (crystal truncation rods - CTR und resonant anomalous X-ray reflectivity - RAXR) as well as site-selective time-resolved laser-induced fluorescence spectroscopy (TRLFS). Both techniques allow us to determine the speciation of actinides at an interface in situ at environmentally relevant trace concentration levels. The techniques are complementary, in that TRLFS yields information on the local structure surrounding an adsorbate, while CTR and RAXR yield a full structural picture of the interface from bulk crystal to bulk solution. This fundamental research will help to make long-term, safe disposal of nuclear waste possible.
The group was positively evaluated and expired as scheduled on September, 30th 2018.
- Dr. Moritz Schmidt
- Sophia Hellebrandt
- Sebastian Reese
- Dr. Canrong Qiu
- Dr. Bin Xiao
- Konrad Molodtsov
- Julia Neumann
- Dr. Erik V. Johnstone
- Dr. Sascha Hofmann
- Dr. Stefan Hellebrandt
- B. Xiao, H. Lösch, N. Huittinen, M. Schmidt (2018) "Local structural effects of Eu3+ incorporation into xenotime-type solid solutions with different host cations", Chem. Eur. J., 24(50), 13368-13377.
- C. Qiu, P. J. Eng, C. Hennig, M. Schmidt (2018) "Competitive adsorption of ZrO2 nanoparticle and alkali cations (Li+ – Cs+) on muscovite (001)", Langmuir, 34(41), 12270-12278.
- C. Qiu, F. Majs, T. A. Douglas, M. Schmidt, T. P. Trainor (2018) "In situ Structural Study of Sb(V) Adsorption on Hematite (1-102) Using X-ray Surface Scattering", Environ. Sci. Technol., 52(19), 11161-11168.
- C. Qiu, F. Majs, P. J. Eng, J. E. Stubbs, T. A. Douglas, M. Schmidt, T. P. Trainor (2018) "In situ Structural Study of the Surface Complexation of Pb(II) on the Chemically Mechanically Polished Hematite (1-102)", J. Colloid Interf. Sci., 524, 65-75.
- C. Qiu, P. J. Eng, C. Hennig, M. Schmidt (2018) "Formation and aggregation of Zr(IV)-nanoparticles on Muscovite (001)", J. Phys. Chem. C, 122(7), 3865-3874.
- B. Xiao and M. Schmidt (2017) "Incorporation of Europium(III) into Scheelite-Related Host Matrixes ABO4 (A = Ca2+, Sr2+, Ba2+; B = W6+, Mo6+): Role of A and B Sites on the Dopant Site Distribution and Photoluminescence", Inorg. Chem., 56(24), 14948-14959.
- E. V. Johnstone, S. Hofmann, A. Cherkouk, M. Schmidt (2016) "Study of the Interaction of Eu3+ with Microbiologically Induced Calcium Carbonate Precipitates using TRLFS", Environ. Sci. Tech., 50(22), 12411-12420.
- S. Hellebrandt, K. E. Knope, S. S. Lee, A. J. Lussier, J. E. Stubbs, P. J. Eng, L. Soderholm, P. Fenter, M. Schmidt (2016) "A Comparison of Adsorption, Reduction, and Polymerization of the Plutonyl(VI) and Uranyl(VI) Ions from Solution onto the Muscovite Basal Plane", Langmuir, 32(41), 10473-10482.
- S. E. Hellebrandt, S. Hofmann, N. Jordan, A. Barkleit, M. Schmidt (2016) "Incorporation of Eu(III) into Calcite under Recrystallization conditions", Sci. Rep., 6, 33137.
- S. S. Lee, M. Schmidt, T. T. Fister, K. L. Nagy, N. C. Sturchio, P. Fenter (2016) "Structural Characterization of Aluminum (Oxy)hydroxide Films at the Muscovite (001)–Water Interface", Langmuir, 32(2), 477-486.
- S. Hofmann, K. Voïtchovsky, P. Spijker, M. Schmidt, T. Stumpf (2016) "Visualising the molecular alteration of the calcite (104) – water interface by sodium nitrate", Sci. Rep., 6, 21576.
- M. Schmidt, S. Hellebrandt, K. E. Knope, S. S. Lee, J. E. Stubbs, P. J. Eng, L. Soderholm, P. Fenter (2015) "Effects of the Background Electrolyte on Th(IV) Sorption to Muscovite Mica", Geochim. Chosmochim. Acta, 165, 280-293.
- S. Hofmann, K. Voitchovsky, M. Schmidt, T. Stumpf (2014) “Trace concentration - huge impact: Nitrate in the calcite/Eu(III) system”, Geochim. Cosmochim. Acta, 125, 528-538.
- M. Schmidt, S. S. Lee, R. E. Wilson, K. E. Knope, F. Bellucci, P. J. Eng, J. E. Stubbs, L. Soderholm, P.Fenter, (2013) “Surface-Mediated Formation of Pu(IV) nanoparticles at the Muscovite-Electrolyte Interface”, Environ. Sci. Technol., 47(24), 14178-14184.
- S. S. Lee, M. Schmidt, N. Laanait, N. C. Sturchio, P. Fenter (2013) “Investigation of Structure, Adsorption Free Energy, and Overcharging Behavior of Trivalent Yttrium Adsorbed at the Muscovite (001) - Water Interface”, J. Phys. Chem. C, 117(45), 23738-23749.
- H. Geckeis, J. Lützenkirchen, R. Polly, T. Rabung, M. Schmidt (2013) “Mineral–Water Interface Reactions of Actinides”, Chem. Rev., 113(2), 1016–1062.