High-Field Aluminum-27 NMR of Simulated Tank Waste Precipitates
EMSL Project ID
10292
Abstract
Our proposal is to use high-field NMR spectroscopy to resolve and quantify aluminum phases in simulated tank waste precipitate samples. It is known that clay minerals weather into zeolite-type phases when exposed to highly caustic solutions with high ionic strength and containing high concentrations of aluminum, properties characterisitic of Hanford-type nuclear waste. This proposal aims to develop a better understanding of the precipitated phases in soils exposed to leaking Hanford waste through the use of solid-state 27Al NMR. Simulated precipitate systems were formed by seeding a simulated tank waste leachate solution with varying amounts of colloidal silica, inducing the zeolite precipitation reaction without the mineral dissolution step necessary in soil systems. It is advantageous to perform NMR analyses on quadrupolar nuclei such as aluminum at the highest available field since the broadening due to second order quadrupolar interaction scales inversely with the applied magnetic field, leading to better resolution of the central transition. Prior investigations of 20:1 and 10:1 parent solution silicon to aluminum (Si/Al) ratio precipitate samples at EMSL were able to resolve multiple aluminum sites which were indistinguishable at lower fields. This proposal intends to continue the prior study by analyzing 2:1 and 1:1 parent solution Si/Al precipitates with the goals of (i) resolving multiple tetrahedral aluminum sites possibly associated with the formation of multiple zeolite phases, (ii) quantify the amount of each zeolite phase formed as a function of contaminant ion, contaminant concentration, and temperature, and (iii) facilitate the calculation of quadrupolar parameters for each phase from multiple field data.
Project Details
Project type
Capability Research
Start Date
2004-10-26
End Date
2005-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
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.