Selective Capture of Cesium and Thallium from Natural Waters and Simulated Wastes with Copper Ferrocyanide Functionalized Mesoporous Silica
Copper(II) ferrocyanide immobilized inside mesoporous silica MCM-41 supports (Cu-FC-EDA-SAMMSTM) has been evaluated against iron(III) hexacyanoferrate(II) (insoluble Prussian blue) for the sorption of cesium (Cs+) and thallium (Tl+) from natural waters and simulated wastes. The affinities (in term of distribution coefficients, Kd) of both sorbents for Cs and Tl were measured as a function of solution pH, competing cations, and matrices. For the entire pH studied (pH 0.1 to 7.3), Cu-FC-EDA-SAMMS had higher affinities for Cs and Tl (one to two orders of magnitude higher Kd) than Prussian blue and was less negatively impacted by the solution pH, competing cations, and matrices. The adsorption isotherms and kinetics of the two sorbents for Cs and/or Tl were also determined in seawater and simulated acid and alkaline wastes. SAMMS outperformed Prussian blue in terms of maximum adsorption capacity (e.g., 21.7 versus 2.6 mg Cs/g in acid waste stimulant, pH 1.1), and rate (e.g., over 95 wt% of Cs was removed after 2 minutes with SAMMS, while only 75 wt% was removed with Prussian blue). The lower affinity, capacity, and rate of Cs and Tl sorption on Prussian blue than those on Cu-FC-EDA-SAMMS were attributed to the molecular pore sizes, which restrict mass transport, and the insoluble Cs abducts of the Prussian blue, which restrict the ability of neighboring binding sites to further bind Cs ions. On the other hand, the large pores of SAMMS not only enable faster diffusion and faster binding chemistry, but they also allow isolation of binding sites so that one Cs binding event does not impact further Cs binding. In addition, iron (Fe) dissolved from insoluble Prussian blue over 10-fold of that from Cu-FC-EDA-SAMMS after 24 hours of contact time, indicating poorer material stability of Prussian blue.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1000609
- Report Number(s):
- PNNL-SA-66353; JHMAD9; 30400; 400412000; TRN: US1100130
- Journal Information:
- Journal of Hazardous Materials, 182(1-3):225-231, Vol. 182, Issue 1-3; ISSN 0304-3894
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CESIUM
THALLIUM
ADSORPTION
COPPER COMPOUNDS
FERROCYANIDES
SILICA
MATERIALS TESTING
ADSORPTION ISOTHERMS
KINETICS
WATER
SEAWATER
LIQUID WASTES
POTASSIUM COMPOUNDS
COMPARATIVE EVALUATIONS
ferrocyanide
mesoporous silica
cesium
thallium
Prussian blue
adsorption
removal
Environmental Molecular Sciences Laboratory