Nitrate-Cancrinite Precipitation on Quartz Sand in Simulated Hanford Tank Solutions

Journal Article · Sat Oct 13 00:00:00 EDT 2001 · Environmental Science and Technology

DOI:https://doi.org/10.1021/es0108234· OSTI ID:15005648

Bickmore, Barry R ^[1]; Nagy, Kathryn L ^[2]; Young, James S ^[3]; Drexler, John W ^[4]

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1. Virginia Tech
2. 1800
3. BATTELLE (PACIFIC NW LAB)
4. ROCKWELL HANFORD OPER.

High pH, high NaNO3 solutions with varying amounts of dissolved Al were reacted with quartz sand at 88.7 degrees Celcius in order to simulate possible reactions between leaked nuclear waste fluid and primary subsurface minerals at the U.S. Department of Energy's Hanford site in Washington. After 2-10 days, nitrate-cancrinite, a feldspathoid mineral with a zeolite-like crystal structure, precipitated onto the quartz surfaces, cementing the grains together. Estimates of the Keq for the precipitation reaction differ for solutions with 0.1 or 1.0 m OH- (log Keq= 30.4+/- 0.8 and 36.2+/-, respectively). It is inferred that the difference in solubility is attribute to more perfectly crystallinity (i.e., fewer stacking faults) in the higher-pH cancrinite structure. This hypothesis is supported by electron micrographs of crystal morphology and measured rates of Na volatilization under an electron beam. Precipitate crystallinity may be important for radionuclide mobility, because stacking faults in the cancrinite structure can negate its zeolitic cation exchange properties. The log of the precipitation rate depends linearly on the activity of Al(OH)4-in solution. The evolution of Si concentration in experimental solutions was successfully modeled by considering the dependence of quartz dissolution rate on Al(OH)4- activity, cancrinite precipitation, and the reduction of reactive surface area of quartz due to coverage by cancrinite.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15005648
• Report Number(s): PNNL-SA-34540; KP1301030
• Journal Information: Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 22 Vol. 35
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
36 MATERIALS SCIENCE
AL
CANCRINITE
CRYSTAL STRUCTURE
CRYSTALS
ELECTRON BEA
ELECTRON BEAMS
ELECTRON MICROGRAPHS
EVAPORATION
NANO3
NITRATE-CANCRINITE
NUCLEAR WASTE FLUID
PH
PRECIPITATION
QUARTZ
QUARTZ SAND
RADIOACTIVE WASTES
RADIOISOTOPES
SAND
STACKING FAULTS
SURFACE AREA
TANKS