Thermodynamic Modeling and Sensitivity Analysis of Kd Values for Radionuclide Migration in Sedimentary Host Rocks

2003 ◽  
Vol 807 ◽  
Author(s):  
Caterina Talerico ◽  
Michael Ochs ◽  
Shinzo Ueta ◽  
Noriyuki Sasaki
Keyword(s):  
Sensitivity Analysis ◽  
Ion Exchange ◽  
Mineral Assemblage ◽  
Surface Complexation ◽  
Critical Component ◽  
Radionuclide Migration ◽  
Sorption Model ◽  
Geochemical Parameters ◽  
Kd Values ◽  
Host Rocks

ABSTRACTThe effects of key geochemical parameters on Kd values for radionuclides in the host rock (pumice, sandstone) of a LLW repository were elucidated through a sensitivity analysis, using a thermodynamic speciation/sorption model for the elements Sr and Ni. The complex mineral assemblage of the rock was approximated by a component-additivity approach. Using published ion exchange and surface complexation parameters, Kd for both Sr and Ni could be well explained by the same model mineralogy and surface chemistry. Model results suggest that pCO2 can have a significant effect on Kd, and that a correct approximation of groundwater chemistry is a critical component of sorption modeling.

Sorption of Cs, Ni, Pb, Eu(III), Am(III), Cm, Ac(III), Tc(IV), Th, Zr, and U(IV) on MX 80 bentonite: An experimental approach to assess model uncertainty

2006 ◽  
Vol 94 (9-11) ◽  
Author(s):  
Bernd Grambow ◽  
Massoud Fattahi ◽  
Gilles Montavon ◽  
C. Moisan ◽  
E. Giffaut
Keyword(s):  
Experimental Data ◽  
Ion Exchange ◽  
Model Uncertainty ◽  
Mineral Assemblage ◽  
Experimental Approach ◽  
Surface Complexation ◽  
Fission Products ◽  
Exchange Model ◽  
Dissolution Properties

A multi-site surface complexation/ion exchange model for dispersed MX 80 bentonite has been calibrated, considering the dissolution properties of the constituting mineral assemblage, for sorption of a large number of radionuclides, using experimental data from the present study together with well constrained literature data. Emphasis was on tri- and tetravalents actinides and fission products and reducing groundwater compositions.

scholarly journals Eclogite-like rocks from Southern Pirin Mountains – preliminary results about petrology and time of formation

2021 ◽  
Vol 82 (3) ◽  
pp. 61-63
Author(s):  
Lyubomirka Macheva ◽  
Philip Machev ◽  
Rossitsa Vassilevа ◽  
Yulia Plotkina
Keyword(s):  
Mineral Assemblage ◽  
Late Jurassic ◽  
Mineral Chemistry ◽  
Metasomatic Alteration ◽  
Preliminary Results ◽  
Icp Ms ◽  
Geological Map ◽  
Host Rocks ◽  
The Village

North-northeast of the village of Ilinden (Southern Pirin Mnt.) three eclogite boudins were separated on the geological map in scale 1:50 000 (Sarov, 2010). The rocks belong to the Slasten lithotectonic unit. The mineral assemblage and mineral chemistry do not allow these rocks to be classified as eclogites. They can be considered as eclogite-like ones, formed by postmagmatic-metasomatic alteration of the host rocks. Based on LA-ICP-MS sphene U-Pb dating, eclogite-like rocks yield a Late Jurassic age (160±19 Ma).

scholarly journals Sorption and mechanism studies of Cu2+, Sr2+ and Pb2+ ions on mesoporous aluminosilicates/zeolite composite sorbents

2020 ◽  
Vol 82 (5) ◽  
pp. 984-997
Author(s):  
Tatyana Kouznetsova ◽  
Andrei Ivanets ◽  
Vladimir Prozorovich ◽  
Ahmad Hosseini-Bandegharaei ◽  
Hai Nguyen Tran ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Metal Ions ◽  
Adsorption Capacity ◽  
Surface Complexation ◽  
Bet Surface Area ◽  
Precipitation Method ◽  
Maximum Adsorption Capacity ◽  
Zeolite Nay ◽  
Inner Surface ◽  
Zeolite Composite

Abstract The research aimed to develop a novel mesoporous aluminosilicate/zeolite composite by the template co-precipitation method. The effect of aluminosilicate (AlSi) and zeolite (NaY) on the basic properties and adsorption capacity of the resultant composite was conducted at different mass ratios of AlSi/NaY (i.e., 5/90, 10/80, 15/85, 20/80, and 50/50). The adsorption characteristics of such composite and its feedstock materials (i.e., aluminosilicates and zeolite) towards radioactive Sr2+ ions and toxic metals (Cu2+ and Pb2+ ions) in aqueous solutions were investigated. Results indicated that BET surface area (SBET), total pore volume (VTotal), and mesopore volume (VMeso) of prepared materials followed the decreasing order: aluminosilicate (890 m2/g, 0.680 cm3/g, and 0.644 cm3/g) > zeolite (623 m2/g, 0.352 cm3/g, and 0.111 cm3/g) > AlSi/NaY (20/80) composite (370 m2/g, 0.254 cm3/g, and 0.154 cm3/g, respectively). The Langmuir maximum adsorption capacity (Qm) of metal ions (Sr2+, Cu2+, and Pb2+) in single-component solution was 260 mg/g, 220 mg/g, and 161 mg/g (for zeolite), 153 mg/g, 37.9 mg/g, and 66.5 mg/g (for aluminosilicate), and 186 mg/g, 140 mg/g, and 77.8 mg/g for (AlSi/NaY (20/80) composite), respectively. Ion exchange was regarded as a domain adsorption mechanism of metal ions in solution by zeolite; meanwhile, inner-surface complexation was domain one for aluminosilicate. Ion exchange and inner-surface complexation might be mainly responsible for adsorbing metal ions onto the AlSi/NaY composite. Pore-filling mechanism was a less important contributor during the adsorption process. The results of competitive adsorption under binary-components (Cu2+ and Sr2+) and ternary-components (Cu2+, Pb2+, and Sr2) demonstrated that the removal efficacy of target metals by the aluminosilicate, zeolite, and their composite remarkably decreased. The synthesized AlSi/NaY composite might serve as a promising adsorbent for real water treatment.

Comparison of in situ uranium KD values with a laboratory determined surface complexation model

2004 ◽  
Vol 19 (10) ◽  
pp. 1643-1653 ◽  
Author(s):  
Gary P Curtis ◽  
Patricia Fox ◽  
Matthias Kohler ◽  
James A Davis
Keyword(s):  
Surface Complexation ◽  
Surface Complexation Model ◽  
Kd Values

scholarly journals The Tournemire industrial analogue: reactive-transport modelling of a cement–clay interface

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 167-184 ◽  
Author(s):  
C. Watson ◽  
D. Savage ◽  
J. Wilson ◽  
S. Benbow ◽  
C. Walker ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Reactive Transport ◽  
Transport Model ◽  
Surface Complexation ◽  
General Purpose ◽  
Transport Modelling ◽  
Mineralogical Characterization ◽  
Modelling Techniques ◽  
Materials Used ◽  
Set Up

AbstractIn the post-closure period of a geological disposal facility for radioactive waste, leaching of cement components is likely to give rise to an alkaline plume which will be in chemical disequilibrium with the host rock (which is clay in some concepts) and other engineered barrier system materials used in the facility, such as bentonite. An industrial analogue for cement-clay interaction can be found at Tournemire, southern France, where boreholes filled with concrete and cement remained in contact with the natural mudstone for 15–20 years. The boreholes have been overcored, extracted and mineralogical characterization has been performed. In this study, a reactive-transport model of the Tournemire system has been set up using the general-purpose modelling tool QPAC. Previous modelling work has been built upon by using the most up-to-date data and modelling techniques, and by adding both ion exchange and surface complexation processes in the mudstone. The main features observed at Tournemire were replicated by the model, including porosity variations and precipitation of carbonates, K-feldspar, ettringite and calcite. It was found that ion exchange needed to be included in order for C-S-H minerals to precipitate in the mudstone, providing a better match with the mineralogical characterization. The additional inclusion of surface complexation, however, led to limited calcite growth at the concrete-mudstone interface unlike samples taken from the Tournemire site that have a visible line of crusty carbonates along the interface.

scholarly journals Stable isotope (δD, δ18O) data on the structural water of two sericite samples from the Cu-Au high-sulphidation deposit Chelopech, Bulgaria – a tentative study

2021 ◽  
Vol 50 (3) ◽  
pp. 65-74
Author(s):  
Nikolay Piperov ◽  
Sylvina Georgieva
Keyword(s):  
Carbon Dioxide ◽  
Mineral Assemblage ◽  
Meteoric Water ◽  
Underground Mining ◽  
Alteration Zone ◽  
Structural Water ◽  
Thermal Fractionation ◽  
Ore Mineralization ◽  
Host Rocks ◽  
Isotopic Measurements

The epithermal high-sulphidation Cu-Au Chelopech deposit is characterized by a well-developed and well-traceable hydrothermal footprint manifested in the volcanic host rocks. The economic ore mineralization is embedded in the strong silicification, included among the advanced argillic zone of alteration, smoothly transitioning to quartz-sericite alteration that evolves into widespread propylitics. The quartz-sericite alteration zone is accessible for exploration only in underground mining galleries and exploration drillings. The main mineral assemblage in this zone is quartz, sericite, pyrite, minor rutile/anatase and relics of apatite and feldspar. According to XRD data from the studied samples, sericite was defined as illite and muscovite/sericite 2M1 polytype. The abundance of heavy stable isotopes (D, 18O) in the structural water of two sericite samples is the object of this study. A special attention was paid to the separation of extraneous waters from the structural one by thermal fractionation. The extracted structural water was converted to hydrogen and carbon dioxide before the isotopic measurements. The obtained results, put into a δD vs. δ18O plot, indicate that sericite structural water is “heavier” than meteoric water, within uncertainty limits.

scholarly journals Hydrotermální mineralizace s dickitem v ordovických jílovcích bohdaleckého souvrství z tunelu metra linky D v Praze na Pankráci

2020 ◽  
Vol 28 (1) ◽  
pp. 116-125
Author(s):  
Zdeněk Dolníček ◽  
Petr Stöhr ◽  
Jana Ulmanová ◽  
Luboš Vrtiška ◽  
Radana Malíková
Keyword(s):  
Mineral Assemblage ◽  
Short Hair ◽  
Lower Paleozoic ◽  
Fault Structure ◽  
Friction Heat ◽  
Prague Basin ◽  
A Value ◽  
Paleozoic Rocks ◽  
Host Rocks ◽  
Thermal Overprint

Two types of hydrothermal veins were found in the Ordovician claystones of the Bohdalec Formation (Barrandian, Prague Basin) during the excavation of tunnel of subway Line D at Prague-Pankrác site. The first type is represented by short hair-thin veinlets of various directions fulfilled by dickite. The second type comprises thicker NNW - SSE trending veins with prevailing quartz, which cut the host rocks across the whole width of the gallery. In addition to quartz, they contain also dickite, chlorite (thuringite-chamosite), carbonates of dolomite-ankerite series (Dol37.5-44.0Ank42.0-46.8Ktn10.9-16.1), calcite, fluorapatite, pyrite (with up to 0.5 wt. % Mn), galena (with ~0.6 wt. % Se) and sphalerite (with ~1 wt. % Fe and up to 0.35 wt. % Sn and 0.36 wt. % Cu). Except for calcite, which forms younger veinlets in older quartz fill, all other mentioned minerals form minute inclusions enclosed in quartz, which are arranged parallel with outer margin of the vein. Based on mineral assemblage and chemical composition of individual minerals, highly variable crystallization temperatures (<100 - 350 °C) can be interpreted in various mineralogically distinct domains of the quartz vein. We assume a polyphase, episodic origin of individual domains of the vein fill, close to the crack-seal mechanism, which was bound to successive evolution of the adjacent fault structure. The maximum formation temperatures exceeding by a value of ca. 100 °C the highest reported temperatures of Variscan thermal overprint of Lower Paleozoic rocks of the Prague Basin are explained by production of friction heat in the fault structure. It is probable that part of parent fluids originated from sedimentary iron ores occurring in the host Ordovician sedimentary sequence.

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