UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd ...

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increases from approximately 0 percent at pH 2.5-3.5 to 90-100 percent at pH 5-6.5. The adsorption of thorium decreased with the addition of sulfate as a result of the formation of competitive aqueous complexes with dissolved thorium. The addition of organic ligands EDTA and trans-1,2-diaminocyclohexane tetra-acetic acid (CDTA) shifted the adsorption edges for (-MnO2 to higher pH values by more than 5-6 pH units, such that 100 percent adsorption of thorium was not observed until pH 12. LaFlamme and Murray (1987) experimentally studied the effects of pH, ionic strength and carbonate alkalinity on the adsorption of thorium by goethite. The adsorption edge (i.e., range in pH where metal adsorption goes from 0 percent to approximately 90-100 percent) was measured to be in the pH range from 2 to 5. For conditions considered in their study, ionic strength was found to have no effect on the adsorption of thorium on goethite. LaFlamme and Murray did however observe a strong influence of carbonate alkalinity on thorium adsorption. In their experiments at pH 9.0±0.6, they observed a decrease of thorium adsorption with the addition of 100 meq/l carbonate alkalinity, and no measurable adsorption of thorium at carbonate alkalinity greater than 300 meq/l. At the low particle concentrations used in their experiments, LaFlamme and Murray attributed this reduction to the 2- - competition for surface sites by CO3 and HCO3 and the formation of soluble thorium-carbonate complexes with a net negative charge. 5.9.6 Partition Coefficient, K d , Values 5.9.6.1 General Availability of K d Data Two generalized, simplifying assumptions were established for the selection of thorium K d values for the look-up table. These assumptions were based on the findings of the literature review conducted on the geochemical processes affecting thorium sorption. The assumptions are as follows: C Thorium precipitates at concentrations greater than 10 -9 M. This concentration is based on the solubility of Th(OH) 4 at pH 5.5. Although (co)precipitation is usually quantified with the solubility construct, a very large K d value will be used in the look-up table to approximate thorium behavior in systems with high thorium concentrations. C Thorium adsorption occurs at concentrations less than 10 -9 M. The extent of thorium adsorption can be estimated by soil pH. These assumptions appear to be reasonable for a wide range of environmental conditions. However, these simplifying assumptions are clearly compromised in systems containing high alkaline (LaFlamme and Murray, 1987), carbonate (LaFlamme and Murray, 1987), or sulfate (Hunter et al., 1988) concentrations, and high or low pH values (pH: 3 < x > 8: Hunter et al., 1988; LaFlamme and Murray 1987; Landa et al., 1995). These assumptions will be discussed in more detail in the following sections. 5.61
Based on the assumptions and limitations described above, thorium K d values and some important ancillary parameters that influence sorption were collected from the literature and tabulated (Appendix I). Data included in this table, were from studies that reported K d values (not percent adsorbed or Freundlich or Langmuir constants) and were conducted in systems consisting of: C Low ionic strength (< 0.1 M) C pH values between 4 and 10.5 C Dissolved thorium concentrations less than 10 -9 M C Low humic material concentrations (
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United States Office of Air and Rad
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NOTICE The following two-volume rep
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This publication is the result of a
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TO COMMENT ON THIS GUIDE OR PROVIDE
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CONTENTS NOTICE ...................
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Concentrations Extractable Iron Con
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Appendix A - Acronyms and Abbreviat
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Figure E.1. Variation of K d for Cr
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Table 5.16. Uranium(VI) aqueous spe
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Table H.3. Simple and multiple regr
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1.0 Introduction The objective of t
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discussed. The geochemical modeling
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2.0 The K d Model The simplest and
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track many more parameters and some
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of interest. The retardation factor
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(e.g., soil). An increasing body of
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complexation constants for the cont
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the soil column. Additionally, the
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Element Table 5.2. Concentrations o
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5.2.3 Aqueous Speciation Cadmium fo
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5.2.4 Dissolution/Precipitation/Cop
Page 43 and 44: cadmium, indicating that cadmium an
Page 45 and 46: 5.2.6.2.2 Limits of K d Values with
Page 47 and 48: 5.3.4 Dissolution/Precipitation/Cop
Page 49 and 50: organic chelates (e.g., EDTA). Init
Page 53 and 54: (tarapacaite) in chromium sludge fr
Page 55 and 56: K d). Soils containing Mn oxides ox
Page 57 and 58: Table 5.7. Estimated range of Kd va
Page 59 and 60: most common valence state of lead e
Page 61 and 62: Table 5.8. Lead aqueous species inc
Page 63 and 64: Under reducing conditions, galena (
Page 65 and 66: C Adsorption of lead increases with
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Page 71 and 72: Table 5.10. Plutonium aqueous speci
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Page 75 and 76: content in the system. Additionally
Page 79 and 80: 5.7.4 Dissolution/Precipitation/Cop
Page 81 and 82: much greater concentrations. Thus,
Page 83 and 84: exchanged which they attributed to
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Page 87 and 88: organic complexes likely predominat
Page 89 and 90: Thorium undergoes hydrolysis in aqu
Page 91 and 92: The distribution of thorium aqueous
Page 93: from about 10 -8.5 mol/l (0.0007 mg
Page 97 and 98: 5.10 Tritium Geochemistry And K d V
Page 99 and 100: uranium. Uranium(VI) species domina
Page 101 and 102: gives 0.1 to 10 µg/l as the range
Page 103 and 104: mineral in reducing ore zones (Fron
Page 105 and 106: Percent Distribution 100 80 60 40 2
Page 107 and 108: 5.11.6 Partition Coefficient, K d ,
Page 109 and 110: No attempt was made to statisticall
Page 111 and 112: Table 5.18. Selected chemical and t
Page 113 and 114: Another objective of this report is
Page 115 and 116: 6.0 REFERENCES Adriano, D. C. 1992.
Page 117 and 118: Bensen, D. W. 1960. Review of Soil
Page 119 and 120: Metals by Geomedia. Variables, Mech
Page 121 and 122: EPA (U.S. Environmental Protection
Page 123 and 124: Griffin, R. A., A. K. Au, and R. R.
Page 125 and 126: + Keeney-Kennicutt, W. L., and J. W
Page 127 and 128: Mattigod, S. V., A. L. Page, and I.
Page 129 and 130: Oscarson, D. W., and H. B. Hume. 19
Page 131 and 132: Relyea, J. F. and D. A. Brown. 1978
Page 133 and 134: Schultz, R. K., R. Overstreet, and
Page 135 and 136: Szalay, A. 1964. “Cation Exchange
Page 137 and 138: Yariv, S., and H. Cross. 1979. Geoc
Page 139 and 140: APPENDIX A Acronyms, Abbreviations,
Page 141 and 142: PC Personal computers operating und
Page 143 and 144: A.3.0 List of Symbols and Notation
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APPENDIX B Definitions
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Clay Content - particle size fracti
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Polynuclear Species - an aqueous sp
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C.1.0 Background Appendix C Partiti
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Cadmium K d Table C.2. Correlation
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C.3.0 Data Set for Soils Table C.4
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Cd K d (ml/g) Clay Cont. (wt%) pH C
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D.1.0 Background Appendix D Partiti
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A second data set (see Section D.4)
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Table D.3. Correlation coefficients
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By transposing the CEC and cesium K
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Table D.6. Cesium K d values measur
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eported in Table D.8 are described
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a 1 b 1 Range of Solution Cs Concen
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Figure D.4. Generalized cesium Freu
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Table D.10. Estimated range of K d
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D.3.0 K d Data Set for Soils and Pu
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Cesium Kd (ml/g) Clay (wt.% ) Mica
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Cesium K d (ml/g) Clay (wt%) Mica (
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Bruggenwert, M. G. M., and A. Kamph
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Shiao, S. Y., P. Rafferty, R. E. Me
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E.1.0 Background Appendix E Partiti
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chromium-reductive soils may stem f
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E.2.0 Approach The approach used to
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Table E.3. Estimated range of K d v
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Table E.4. Data from Rai et al. (19
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E.4.0 References Davis, J. A. and J
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APPENDIX F Partition Coefficients F
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(CEC) of the soils. Such an anomaly
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Table F.1. Summary of K d values fo
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Figure F.2. Variation of K d as a f
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F.4.0 References Abd-Elfattah, A.,
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APPENDIX G Partition Coefficients F
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A number of investigators have exam
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pH value, which is typical of the m
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These significant reductions in ads
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This is typically accomplished by t
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The scatterplots are typically disp
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Table G.2. Regression models for pl
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G.4.0 References Barney, G. S. 1984
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Nelson, D. M., R. P. Larson, and W.
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APPENDIX H Partition Coefficients F
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1.6 ml/g for a measurement made on
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Figure H.1. Relation between stront
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Figure H.2. Relation between stront
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H.2.4 Approach Figure H.4. Relation
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A second look-up table (Table H.5)
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Sr K d (ml/g) Clay Content (%) pH C
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Sr K d (ml/g) Clay Content (%) pH C
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Sr K d (ml/g) Clay Conten t (%) pH
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Konishi, M., K. Yamamoto, T. Yanagi
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APPENDIX I Partition Coefficients F
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descriptive statistics of the thori
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Figure I.1. Linear regression betwe
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The look-up table (Table I.5) for t
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Thorium K d (ml/g) pH Clay (wt.%) C
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Rai, D., A. R. Felmy, D. A. Moore,
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J.1.0 Background Appendix J Partiti
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J.2.2 Uranium K d Studies on Soils
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Washington. The studies included an
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and then decreases with increasing
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Kd (ml/g) 100,000 10,000 1,000 100
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papers. Warnecke et al. (1984) indi
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Anderson et al. (1982) summarize an
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McKinley and Scholtis (1993) compar
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In a similar comparison of sorption
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J.3.1 K d Values as a Function ff p
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discussed, and one would have to ma
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al., 1992; and others). These refer
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· Manskaya et al. (1956) studied a
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concentrations of humic acid, there
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pH U Kd (ml/g) Clay Cont. (wt.%) CE
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J.6.0 References Ames, L. L., J. E.
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Erikson, R. L., C. J. Hostetler, R.
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R. C. Ewing. Materials Research Soc
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Sheppard, M. I., and D. H. Thibault
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Yamamoto, T., E. Yunoki, M. Yamakaw
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