1、Designation: C1733 17C1733 17aStandard Test Method forDistribution Coefficients of Inorganic Species by the BatchMethod1This standard is issued under the fixed designation C1733; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONAs an aqueous fluid migrates through geologic media or contacts an engineered material, certainreactions occur
3、 that are dependent upon the chemistry of the fluid itself and upon the chemistry andgeochemistry of other fluids and solid phases with which it comes in contact. These chemical andgeochemical interactions affect the relative rates at which chemical species in the migrating fluid (suchas ions) trave
4、l with respect to the advancing front of water. Processes of potential importance inretarding the transport of chemical species in the migrating fluid (movement of species at velocitiesless than the ground-water velocity) include ion exchange, adsorption, complex formation, precipi-tation (or coprec
5、ipitation, for example Ba2+ and Ra2+ co-precipitating as a sulfate), redox reactions,and precipitate filtration. Partitioning may be caused by processes that include adsorption,precipitation, and coprecipitation that cannot be described easily by equations and, furthermore, thesesolute removal mecha
6、nisms may not instantaneously respond to changes in prevailing conditions andmay not be entirely reversible.An empirical ratio known as the distribution coeffcient (Kd) is defined as:Kd 5Mass of solute on the solid phase per unit mass of solid phaseMass of solute in solution per unit volume of the l
7、iquid phaseand has been used to quantify the collective effects of these processes for the purpose of modeling (usually, but not solely,applied to ionic species). Kd is used to assess the degree to which a chemical species will be removed from solution (permanentlyor temporarily) as the fluid migrat
8、es through the geologic medium or contacts a solid material; that is, Kd is used to calculate theretardation factor that quantifies how rapidly an ion can move relative to the rate of ground-water movement.This test method is for the laboratory determination of the Kd, which may be used by qualified
9、 experts for estimating theretardation of contaminants for given underground geochemical conditions based on a knowledge and understanding of importantsite-specific factors. It is beyond the scope of this test method to define the expert qualifications required, or to justify theapplication of labor
10、atory data for modeling or predictive purposes. Rather, this test method is considered as simply a measurementtechnique for determining the degree of partitioning between liquid and solid, under a certain set of conditions, for the species ofinterest.Justification for the Kd concept is generally ack
11、nowledged to be based on expediency in modeling-averaging the effects ofattenuation reactions. In reference to partitioning in soils, equilibrium is assumed although it is known that this may not be a validassumption in many cases.The Kd for a specific chemical species may be defined as the ratio of
12、 the mass sorbed per unit of solid phase to the massremaining per unit of solution, as expressed in the above equation. The usual units of Kd are mL/g (obtained by dividing g solute/gsolid by g solute/mL solution, using concentrations obtained in accordance with this test method).Major difficulties
13、exist in the interpretation, application, and meaning of laboratory-determined Kd values relative to a realsystem of aqueous fluid migrating through geologic media (1)2. The Kd concept is based on an equilibrium condition for givenreactions, which may not be attained in the natural situation because
14、 of the time-dependence or kinetics of specific reactionsinvolved. Also, migrating solutions always follow the more permeable paths of least resistance, such as joints and fractures, and1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct respons
15、ibility of Subcommittee C26.13 on Spent Fuel andHigh Level Waste.Current edition approved Aug. 1, 2017Nov. 1, 2017. Published August 2017November 2017. Originally approved in 2010. Last previous edition approved in 20102017as C1733 10.C1733 17. DOI: 10.1520/C1733-17.10.1520/C1733-17A.2 The boldface
16、numbers in parentheses refer to a list of references at the end of this standard.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequ
17、ately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
18、en, PA 19428-2959. United States1larger sediment grain zones.This tends to allow less time for reactions to occur and less sediment surface exposure to the migratingsolution, and may preclude the attainment of local chemical equilibrium.Sorption phenomena also can be strongly dependent upon the conc
19、entration of the species of interest in solution. Therefore,experiments performed using only one concentration of a particular chemical species may not be representative of actual in situconditions or of other conditions of primary interest. Similarly, experimental techniques should consider all ion
20、ic speciesanticipated to be present in a migrating solution, in order to address competing ion and ion complexation effects, which maystrongly influence the sorption of a particular species.Sorption can be strongly controlled, by pH. Therefore, in situ pH, especially of groundwater, should be consid
21、ered indeterminations of Kd. Values of pH must be determined, preferably in the field when materials are sampled and must be carefullydetermined in the laboratory procedure. Other in situ conditions (for example, ionic strength, anoxic conditions, or temperature)could likewise have considerable effe
22、ct on the Kd and need to be considered for each situation.Site-specific materials must be used in the measurement of Kd. This is because the determined Kd values are dependent uponrock and soil properties such as the mineralogy (surface charge and energy), particle size distribution (surface area),
23、and biologicalconditions (for example, bacterial growth and organic matter). Special precautions may be necessary to assure that the site-specificmaterials are not significantly changed prior to laboratory testing. This may require refrigeration or freezing of both soil and watersamples. Chemical me
24、ans of preservation (such as addition of acid to groundwater) will cause changes in sample chemistry andmust be avoided.The choice of fluid composition for the test may be difficult for certain contaminant transport studies. In field situations, thecontaminant solution moves from the source through
25、the porous medium.As it moves, it displaces the original ground water, withsome mixing caused by dispersion. If the contaminant of interest has a Kd of any significant magnitude, the front of the zonecontaining this contaminant will be considerably retarded. This means that the granular medium encou
26、ntered by the contaminanthas had many pore volumes of the contaminant source water pass through it. The exchange sites achieve a different populationstatus and this new population status can control the partitioning that occurs when the retarded contaminant reaches the point ofinterest. It is recomm
27、ended that ground water representative of the test zone (but containing added tracers) be used as contact liquidin this test, or a carefully prepared simulated (site-specific) groundwater; concentrations of potential contaminants of interest usedin the contact liquid should be judiciously chosen. Fo
28、r studies of interactions with intrusion waters, the site-specific ground watermay be substituted by liquids of other compositions.The Kd for a given chemical species generally assumes a different value when conditions are altered. Clearly, a very thoroughunderstanding of the site-specific condition
29、s that determine their values is required if one is to confidently apply the Kd conceptto migration evaluation and prediction.The most convenient method of determining Kd is probably the batch method (this test method), in which concentrations of thechemical species in solid and liquid phases, which
30、 are in contact with one another, are measured. Other methods include dynamiccolumn flow-through methods using continuous input of tracer or pulsed input. In the field, a dual tracer test can be conductedusing a conservative (non-sorbing) tracer and one that does sorb; from the difference in travel
31、times of the two tracers, Kd can becalculated.In summary, the distribution coefficient, Kd, is affected by many variables, some of which may not be adequately controlled ormeasured by the batch method determination.The application of experimentally determined Kd values for predictive purposes mustbe
32、 done judiciously by qualified experts with a knowledge and understanding of the important site-specific factors. However, whenproperly combined with knowledge of the behavior of chemical species under varying physicochemical conditions of the solidsurface (or geomedia) and the migrating fluid, Kd c
33、an be used for assessing the rate of migration of chemical species through asaturated geomedium.1. Scope1.1 This test method covers the determination of distribution coefficients, Kd, of chemical species to quantify uptake onto solidmaterials by a batch sorption technique. It is a laboratory method
34、primarily intended to assess sorption of dissolved ionic speciessubject to migration through pores and interstices of site specific geomedia, or other solid material. It may also be applied to othermaterials such as manufactured adsorption media and construction materials.Application of the results
35、to long-term field behavioris not addressed in this method. Kd for radionuclides in selected geomedia or other solid materials are commonly determined forthe purpose of assessing potential migratory behavior of contaminants in the subsurface of contaminated sites and out of a wasteform and in the su
36、rface of waste disposal facilities. This test method is also applicable to studies for parametric studies of thevariables and mechanisms which contribute to the measured Kd.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1
37、.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.
38、4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trad
39、e (TBT) Committee.C1733 17a22. Referenced Documents2.1 ASTM Standards:3C859 Terminology Relating to Nuclear MaterialsD422 Test Method for Particle-Size Analysis of Soils (Withdrawn 2016)4D1293 Test Methods for pH of WaterD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of
40、Soil and Rock by MassD2217 Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and Determination of Soil ConstantsD2488 Practice for Description and Identification of Soils (Visual-Manual Procedures)D3370 Practices for Sampling Water from Closed ConduitsD4319 Test Method for Dist
41、ribution Ratios by the Short-Term Batch Method (Withdrawn 2007)4D4448 Guide for Sampling Ground-Water Monitoring WellsD5730 Guide for Site Characterization for Environmental Purposes With Emphasis on Soil, Rock, the Vadose Zone andGroundwater (Withdrawn 2013)43. Terminology3.1 Please refer to Termin
42、ology C859 for additional terminology which may not be listed below.3.2 Definitions of Terms Specific to This Standard:3.2.1 distribution coeffcient, Kd, nthe concentration of a species sorbed on a solid material, divided by its concentration insolution in contact with the solid material, under cons
43、tant concentration conditions, as follows:Kd 5Mass of solute on the solid phase per unit mass of solid phaseMass of solute in solution per unit volume of the liquid phase (1)3.2.1.1 DiscussionBy constant concentration conditions, it is meant that the Kd values obtained for samples exposed to the con
44、tact liquid for twodifferent time periods (at least one day apart), other conditions remaining constant, shall differ by not more than the expectedprecision for this test method. It is convenient to express Kd in units of mL (or cm3) of solution per gram of solid material.3.2.2 species, nspecific fo
45、rm of an element defined as to isotopic composition, electronic or oxidation state, complex ormolecular structure, or combinations thereof (2).3.2.3 tracer, nan identifiable substance, such as a dye or radioactive isotope, that can be followed through the course of amechanical, chemical, or biologic
46、al process.4. Significance and Use4.1 The distribution coefficient, Kd, is an experimentally determined ratio quantifying the distribution of a chemical speciesbetween a given fluid and solid material sample under certain conditions, including the attainment of constant aqueousconcentrations of the
47、species of interest. The Kd concept is used in mass transport modeling, for example, to assess the degree towhich the movement of a species will be delayed by interactions with the local geomedium as the solution migrates through thegeosphere under a given set of underground geochemical conditions (
48、pH, temperature, ionic strength, etc.). The retardation factor(Rf) is the ratio of the velocity of the groundwater divided by the velocity of the contaminant, which can be expressed as:Rf 511b/e! Kd (2)where:b = bulk density of the porous medium (mass/length3) ande = effective porosity of the medium
49、 (unitless) expressed as a decimal.4.2 Because of the sensitivity of Kd to site specific conditions and materials, the use of literature derived Kd values is stronglydiscouraged. For applications other than transport modeling, batch Kd measurements also may be used, for example, for parametricstudies of the effects of changing chemical conditions and of mechanisms related to the interactions of fluids with solid material.5. Apparatus5.1 Laboratory Ware, (plastic bottles, centrifuge tubes, open dishes, pipettes) cleaned in a manner consistent with the analysesto be perfo
