UNDERSTANDING VARIATION IN PARTITION COEFFICIENT, Kd ...

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2- 2- - competing anions such as SO4 , and CO3 /HCO3 . The adsorption data developed by these investigators was used to calculate the Kd values (Appendix E). These Kd values were used as the basis to develop the look-up Table 5.7. 5.4.6.2.1 Limits of K d Values with Respect to pH Natural soil pH typically ranges from about 4 to 11 (Richards, 1954). The 2 most common methods of measuring soil pH are either using a soil paste or a saturation extract. The standard procedure for obtaining saturation extracts from soils has been described by Rhoades (1996). The saturation extracts are obtained by saturating and equilibrating the soil with distilled water followed by collection using vacuum filtration. Saturation extracts are usually used to determine the pH, the electrical conductivity, and dissolved salts in soils. The narrow pH ranges in the look-up table (Table 5.7) were selected from the observed rate of change of K d with pH. The K d values for all 4 soils were observed to decline with increasing pH and at pH values beyond about 9, K d values for Cr(VI) are #1 ml/g (see Appendix E). 5.4.6.2.2 Limits of K d Values with Respect to Extractable Iron Content The soil characterization data provided by Rai et al. (1988) indicate the soils with DCB extractable iron contents above ~0.3 mmol/g can reduce Cr(VI) to Cr(III). Therefore the measured K d values for such soils reflect both redox-mediated precipitation and adsorption phenomena. The data also show that soils with DCB extractable iron contents of about 0.25 mmol/g or less do not appear to reduce Cr(VI). Therefore, 3 ranges of DCB extractable iron contents were selected which represent the categories of soils that definitely reduce ($0.3 mmol/g), probably reduce (0.26 - 0.29 mmol/g), and do not reduce (#0.25 mmol/g) Cr(VI) to Cr(III) form. 5.4.6.2.3 Limits of K d Values with Respect to Competing Anion Concentrations The adsorption data (Rai et al., 1988) show that when total sulfate concentration in solution is about 2 x 10 -3 M (191.5 mg/l), the chromium K d values are reduced by about an order of magnitude as compared to a noncompetitive condition. Therefore, a sulfate concentration of about 2 x 10 -3 M (191.5 mg/l) has been used as a limit at which an order of magnitude reduction in K d values are expected. Four ranges of soluble sulfate concentrations (0 - 1.9, 2 -18.9, 19 - 189, and $190 mg/l) have been used to develop the look-up table. The soluble sulfate concentrations in soils can be assessed from saturation extracts (Richards, 1954). 5.23
Table 5.7. Estimated range of Kd values for chromium (VI) as a function of soil pH, extractable iron content, and soluble sulfate. (Data analysis and generation of the table of Kd values are described in Appendix E.) pH 4.1 - 5.0 5.1 - 6.0 6.1 - 7.0 $7.1 DCB Extractable Fe (mmol/g) DCB Extractable Fe (mmol/g) DCB Extractable Fe (mmol/g) DCB Extractable Fe (mmol/g) #0.25 0.26 - 0.29 $0.30 #0.25 0.26 - 0.29 $0.30 ##0.25 0.26 - 0.29 $$0.30 ##0.25 0.26 - 0.29 $$0.30 Kd (ml/g) Soluble Sulfate Conc (mg/l) Min 25 400 990 20 190 390 8 70 80 0 0 1 0 - 1.9 Max 35 700 1770 34 380 920 22 180 350 7 30 60 5.24 Min 12 190 460 10 90 180 4 30 40 0 0 1 2 - 18.9 Max 15 330 820 15 180 430 10 80 160 3 14 30 Min 5 90 210 4 40 80 2 15 20 0 0 0 19 - 189 Max 8 150 380 7 80 200 5 40 75 2 7 13 Min 3 40 100 2 20 40 1 7 8 0 0 0 $190 Max 4 70 180 3 40 90 2 20 35 1 3 6
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United States Office of Air and Rad
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NOTICE The following two-volume rep
Page 5 and 6: This publication is the result of a
Page 7 and 8: TO COMMENT ON THIS GUIDE OR PROVIDE
Page 9 and 10: CONTENTS NOTICE ...................
Page 11 and 12: Concentrations Extractable Iron Con
Page 13 and 14: Appendix A - Acronyms and Abbreviat
Page 15 and 16: Figure E.1. Variation of K d for Cr
Page 17 and 18: Table 5.16. Uranium(VI) aqueous spe
Page 19 and 20: Table H.3. Simple and multiple regr
Page 21 and 22: 1.0 Introduction The objective of t
Page 23 and 24: discussed. The geochemical modeling
Page 25 and 26: 2.0 The K d Model The simplest and
Page 27 and 28: track many more parameters and some
Page 29 and 30: of interest. The retardation factor
Page 31 and 32: (e.g., soil). An increasing body of
Page 33 and 34: complexation constants for the cont
Page 35 and 36: the soil column. Additionally, the
Page 37 and 38: Element Table 5.2. Concentrations o
Page 39 and 40: 5.2.3 Aqueous Speciation Cadmium fo
Page 41 and 42: 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 49 and 50: organic chelates (e.g., EDTA). Init
Page 53 and 54: (tarapacaite) in chromium sludge fr
Page 55: K d). Soils containing Mn oxides ox
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
Page 69 and 70: (Choppin, 1983). Plutonium hydrolyt
Page 71 and 72: Table 5.10. Plutonium aqueous speci
Page 73 and 74: 5.6.5 Sorption/Desorption Plutonium
Page 75 and 76: content in the system. Additionally
Page 81 and 82: much greater concentrations. Thus,
Page 83 and 84: exchanged which they attributed to
Page 85 and 86: up tables was based in part on thei
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 and 94: from about 10 -8.5 mol/l (0.0007 mg
Page 95 and 96: Based on the assumptions and limita
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
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5.11.6 Partition Coefficient, K d ,
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No attempt was made to statisticall
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Table 5.18. Selected chemical and t
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Another objective of this report is
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6.0 REFERENCES Adriano, D. C. 1992.
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Bensen, D. W. 1960. Review of Soil
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Metals by Geomedia. Variables, Mech
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EPA (U.S. Environmental Protection
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Griffin, R. A., A. K. Au, and R. R.
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+ Keeney-Kennicutt, W. L., and J. W
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Mattigod, S. V., A. L. Page, and I.
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Oscarson, D. W., and H. B. Hume. 19
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Relyea, J. F. and D. A. Brown. 1978
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Schultz, R. K., R. Overstreet, and
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Szalay, A. 1964. “Cation Exchange
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Yariv, S., and H. Cross. 1979. Geoc
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APPENDIX A Acronyms, Abbreviations,
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PC Personal computers operating und
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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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