Stability High Salt Content Waste Using Sol Gel Process. Mixed Waste Focus Area. OST Reference Number 0236
Mixed waste sludges, soils, and homogeneous solids containing high levels of salt ( ~ greater than 15% by weight ) have proven to be difficult to stabilize due to the soluble nature of the salts. The current stabilization technique for high salt waste, grouting with Portland cement, is limited to low waste loadings. The presence of salts interfere with the hydration and curing of the cement, cause waste form deteriorating mineral expansions, or result in an undesirable separate phase altogether. Improved technologies for the stabilization of salt waste must be able to accommodate higher salt loadings, while maintaining structural integrity, chemical durability, and leach resistance. In a joint collaboration supported by the Department of Energy’s (DOE’s) Mixed Waste Focus Area (MWFA), the Pacific Northwest National Laboratory (PNNL) and the Arizona Materials Laboratory (AML) at the University of Arizona have developed a sol-gel (wet-chemical) based, low-temperature-processing route for the stabilization of salt-containing mixed wastes. By blending and reacting liquid precursors at room temperature with salt waste, strong, impermeable “polyceram” matrices have been formed that encapsulate the environmentally hazardous waste components. As depicted by Figure 1, polycerams are hybrid organic/inorganic materials with unique properties derived from the chemical combination of polymer (organic) and ceramic (inorganic) components. For this application, the stabilizing polyceram matrices contain polybutadiene-based polymer components and silicon dioxide (SiO2) as the inorganic component. Polybutadiene (PBD) is a strong, tough, waterresistant plastic and its use in the polyceram promotes these same characteristics in the waste form. The PBD polymer component is modified to increase its reactivity with the SiO2 precursor during sol-gel processing. When combined, the polymer and SiO2 precursors react, gel, solidify, and encapsulate the salt waste components. The toxicity characterization leaching procedure (TCLP), Compressive Strength (ASTM C 39-94) and leachability tests (ANSI/ANS 16.1) confirm the efficacy of this approach, indicating that polyceram-based salt waste forms have the potential to provide end users with unique capabilities for disposing of salt-containing mixed wastes.
- Research Organization:
- USDOE Office of Environmental Management (EM), Washington, DC (United States). Office of Science and Technology
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM)
- OSTI ID:
- 1246966
- Report Number(s):
- DOE/EM-0473
- Country of Publication:
- United States
- Language:
- English
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