Analysis of Clays Reacted with Simulated Hanford Tank Waste
EMSL Project ID
3101
Abstract
As part of an EMSP-funded study, we have reacted clay minerals (illite, vermiculite, montmorillonite and kaolinite) in batch systems with synthetic solutions characteristic of tank waste leachate at the Hanford Site, WA (0.05 M AlT, 2 M Na+, 1 M NO3-, pH ~14, Cs+ and Sr2+ present as co-contaminants). Experiments were conducted for periods ranging from 1 to 369 days, with initial Cs+/Sr2+ concentrations of 10-5, 10-4 and 10-3 M. To elucidate secondary Si phases, acid ammonium oxalate (0.2 M, pH=3) extractions were performed on reacted samples. Solution chemistry was analyzed as a function of reaction time with ICP/AES and AAS. Dissolution of Si was found to result in incipient precipitation of short-range-ordered Al and Si phases that transform to crystalline zeolites, with concurrent impacts on Cs and Sr uptake kinetics. The coupling of Cs/Sr uptake to mineral transformation rates (monitored using solid-state NMR, XRD, FTIR, SEM-EDX, TGA and wet chemical methods) show strong dependence on (i) the type of clay mineral and (ii) contaminant concentrations (e.g., Choi et al., submitted). The rate of Si release and secondary phase formation was greatest for kaolinite, followed by montmorillonite, vermiculite and illite. We propose to use FTIR, Mossbauer spectroscopy, EPR, HRTEM, EELS, SEM, Auger, and TGA-MS as described in the following sections to improve our overall understanding of clay weathering under the caustic conditions typical of Hanford tank waste leachate.
Project Details
Project type
Exploratory Research
Start Date
2002-11-13
End Date
2004-11-15
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Choi S, GS Crosson, KT Mueller, s seraphin, and J Chorover. 2005. "Clay mineral weathering and contaminant dynamics in a casutic aqueous sytem II. Mineral transformation and microscale partitioning." Geochimica et Cosmochimica Acta 69(18):4437-4451.
Choi S, MK Amistadi, and J Chorover. 2005. "Clay mineral weathering and contaminant dynamics in a caustic aqueous system I. Wet chemistry and aging effects." Geochimica et Cosmochimica Acta 69(18):4425-4436.
Choi, S., P. A. O'Day, N. A. Rivera, K. T. Mueller, M. A. Vairavamurthy, S. Seraphin and J. Chorover. 2006. Strontium speciation during reaction of kaolinite with simulated tank-waste leachate: Bulk and microfocused EXAFS analysis. Environ. Sci. Technol. 40: 2608-2614.
Chorover J, S Choi, P Rotenberg, RJ Serne, N Rivera, CR Strepka, A Thompson, KT Mueller, and PA O'Day. 2008. "Silicon Control of Strontium and Cesium Partitioning in Hydroxide-Weathered Sediments." Geochimica et Cosmochimica Acta 72(8):2024-2047.
Crosson, G. S., S. Y. Choi, J. Chorover, M. K. Amistadi, P. A. O'Day and K. T. Mueller. 2006. Solid-state NMR identification and quantification of newly formed aluminosilicate phases in weathered kaolinite systems. J. Phys. Chem. B 110: 723-732.
Linking Cesium and Strontium Uptake to Kaolinite Weathering in Simulated Tank Waste Leachate
Strontium Speciation during Reaction of Kaolinite with Simulated Tank-Waste Leachate: Bulk and Microfocused EXAFS Analysis