Details
| Original language | English |
|---|---|
| Pages (from-to) | 1-13 |
| Number of pages | 13 |
| Journal | Applied clay science |
| Volume | 16 |
| Issue number | 1-2 |
| Publication status | Published - Jan 2000 |
| Event | The 11th International Clay Conference (ICC'97) - Ottawa, Ont, Can Duration: 15 Jun 1997 → 21 Jun 1997 |
Abstract
The retardation of radionuclides by engineered clay barriers is primarily controlled by the sorption potential of the mineral constituents. Adsorption and desorption experiments were performed with I-, TcO4-, Cs+ and Sr2+ on MX-80 Wyoming-bentonite treated with hexadecylpyridinium (HDPy+) in amounts equivalent to 20%-400% of the cation exchange capacity (CEC). Bidistilled water, synthetic ground water (SGW), and sea water with half of the ionic strength (Sea/2) were used as equilibrium solutions, and 125I, 95mTc, 134Cs and 85Sr were employed as tracers. In HDPy-bentonite, I- and TcO4- exhibited increasing adsorption (characterized by the distribution ratio, R(d)), while Cs+ and Sr2+ ions showed decreasing adsorption with increasing organophilicity. The extent of the adsorption as well as the reversibility of the binding processes was influenced by the chemical composition of the equilibrium solutions. These effects were more pronounced in the case of the cationic fission products compared to the anions investigated. Generally, sorption and desorption were linear over a wide concentration range of the carrier ions investigated, indicating that adsorption was independent from the sorbate concentrations (up to ~10-1 mmol g-1 organo-bentonite). This suggests ion exchange as the principal sorption mechanism. Adsorption capacities for the anions investigated were estimated to be ~0.5 mol(c) kg-1, for the cations to be ~0.1 mol(c) kg-1 depending on the HDPy+ loading of the samples. In case of cationic radionuclides, Cs+ was preferentially adsorbed in competition with the bivalent Sr2+ ions in both the untreated and modified samples. The results of this study may be applicable to predict the long-term behaviour of fission products in waste disposal sites equipped with clay barriers. (C) 2000 Elsevier Science B.V. All rights reserved.
Keywords
- Adsorption, Cesium, Iodide, Organophilic bentonite, Pertechnetate, Strontium
ASJC Scopus subject areas
- Earth and Planetary Sciences(all)
- Geology
- Earth and Planetary Sciences(all)
- Geochemistry and Petrology
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In: Applied clay science, Vol. 16, No. 1-2, 01.2000, p. 1-13.
Research output: Contribution to journal › Conference article › Research › peer review
}
TY - JOUR
T1 - Organophilic bentonites as adsorbents for radionuclides I. Adsorption of ionic fission products
AU - Bors, J.
AU - Dultz, S.
AU - Riebe, B.
N1 - Funding information: The studies on organophilic bentonite are funded by the Nuclear Fission Safety Programme of the European Commission under the Project No. FI4WCT950012. The skilled technical assistance of Ms. G. Erb-Bunnenberg and Mr. K.-H. Iwannek is gratefully acknowledged.
PY - 2000/1
Y1 - 2000/1
N2 - The retardation of radionuclides by engineered clay barriers is primarily controlled by the sorption potential of the mineral constituents. Adsorption and desorption experiments were performed with I-, TcO4-, Cs+ and Sr2+ on MX-80 Wyoming-bentonite treated with hexadecylpyridinium (HDPy+) in amounts equivalent to 20%-400% of the cation exchange capacity (CEC). Bidistilled water, synthetic ground water (SGW), and sea water with half of the ionic strength (Sea/2) were used as equilibrium solutions, and 125I, 95mTc, 134Cs and 85Sr were employed as tracers. In HDPy-bentonite, I- and TcO4- exhibited increasing adsorption (characterized by the distribution ratio, R(d)), while Cs+ and Sr2+ ions showed decreasing adsorption with increasing organophilicity. The extent of the adsorption as well as the reversibility of the binding processes was influenced by the chemical composition of the equilibrium solutions. These effects were more pronounced in the case of the cationic fission products compared to the anions investigated. Generally, sorption and desorption were linear over a wide concentration range of the carrier ions investigated, indicating that adsorption was independent from the sorbate concentrations (up to ~10-1 mmol g-1 organo-bentonite). This suggests ion exchange as the principal sorption mechanism. Adsorption capacities for the anions investigated were estimated to be ~0.5 mol(c) kg-1, for the cations to be ~0.1 mol(c) kg-1 depending on the HDPy+ loading of the samples. In case of cationic radionuclides, Cs+ was preferentially adsorbed in competition with the bivalent Sr2+ ions in both the untreated and modified samples. The results of this study may be applicable to predict the long-term behaviour of fission products in waste disposal sites equipped with clay barriers. (C) 2000 Elsevier Science B.V. All rights reserved.
AB - The retardation of radionuclides by engineered clay barriers is primarily controlled by the sorption potential of the mineral constituents. Adsorption and desorption experiments were performed with I-, TcO4-, Cs+ and Sr2+ on MX-80 Wyoming-bentonite treated with hexadecylpyridinium (HDPy+) in amounts equivalent to 20%-400% of the cation exchange capacity (CEC). Bidistilled water, synthetic ground water (SGW), and sea water with half of the ionic strength (Sea/2) were used as equilibrium solutions, and 125I, 95mTc, 134Cs and 85Sr were employed as tracers. In HDPy-bentonite, I- and TcO4- exhibited increasing adsorption (characterized by the distribution ratio, R(d)), while Cs+ and Sr2+ ions showed decreasing adsorption with increasing organophilicity. The extent of the adsorption as well as the reversibility of the binding processes was influenced by the chemical composition of the equilibrium solutions. These effects were more pronounced in the case of the cationic fission products compared to the anions investigated. Generally, sorption and desorption were linear over a wide concentration range of the carrier ions investigated, indicating that adsorption was independent from the sorbate concentrations (up to ~10-1 mmol g-1 organo-bentonite). This suggests ion exchange as the principal sorption mechanism. Adsorption capacities for the anions investigated were estimated to be ~0.5 mol(c) kg-1, for the cations to be ~0.1 mol(c) kg-1 depending on the HDPy+ loading of the samples. In case of cationic radionuclides, Cs+ was preferentially adsorbed in competition with the bivalent Sr2+ ions in both the untreated and modified samples. The results of this study may be applicable to predict the long-term behaviour of fission products in waste disposal sites equipped with clay barriers. (C) 2000 Elsevier Science B.V. All rights reserved.
KW - Adsorption
KW - Cesium
KW - Iodide
KW - Organophilic bentonite
KW - Pertechnetate
KW - Strontium
UR - http://www.scopus.com/inward/record.url?scp=0034013783&partnerID=8YFLogxK
U2 - 10.1016/S0169-1317(99)00041-1
DO - 10.1016/S0169-1317(99)00041-1
M3 - Conference article
AN - SCOPUS:0034013783
VL - 16
SP - 1
EP - 13
JO - Applied clay science
JF - Applied clay science
SN - 0169-1317
IS - 1-2
T2 - The 11th International Clay Conference (ICC'97)
Y2 - 15 June 1997 through 21 June 1997
ER -