Aluminum Hydroxide Solubility in Sodium Hydroxide Solutions Containing Nitrite/Nitrate of Relevance to Hanford Tank Waste
The technical basis to support the One System River Protection Project Integrated Flowsheet assumption for diluting staged direct feed low-activity waste (DFLAW) from the Hanford waste tanks with raw river water must be assessed in light of the risk of aluminum hydroxide (gibbsite) precipitation prior to the subsequent transfer of tank contents into the low-activity waste pretreatment system (LAWPS) and/or the Tank Side Cesium Removal (TSCR) system from days to months after dilution. Aluminum solubility must be predicted as a function of the significant variables that influence gibbsite dissolution and precipitation. These variables include (i) other solution components that meaningfully affect the activity coefficient of either hydroxide or the aluminate ion, particularly nitrate and nitrite; and (ii) temperature. Based on a review of waste solubility data and the impact of dilution on solution stabilities with specific focus on aluminum hydroxide, data gaps associated with the impact of these variables on the prediction of gibbsite solubility with temperature were identified. An experimental program to aid in the prediction of gibbsite solubility in NaOH solutions containing a range of sodium nitrate and sodium nitrite concentrations up to the solubility limit at a range of temperatures has been conducted. The results of these investigations are summarized in this report.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE; Washington River Protection Solutions
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1660940
- Report Number(s):
- PNNL-27969; RPT-OSIF-003; TRN: US2202368
- Country of Publication:
- United States
- Language:
- English
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