1、Designation: C1733 10C1733 17Standard 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 y
2、ear 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, media or contacts an engineered material,certain reactions
3、 occur that are dependent upon the chemistry of the fluid itself and upon the chemistryand geochemistry 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)
4、 travel 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
5、coprecipitation, for example Ba2+ and Ra2+ co-precipitating as thea sulfate), oxidation-reductionredox reactions, and precipitate filtration. Partitioning may be caused by processes thatinclude adsorption, precipitation, and coprecipitation that cannot be described easily by equations and,furthermor
6、e, these solute removal mechanisms may not instantaneously respond to changes inprevailing conditions and may 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 solu
7、tion per unit volume of the liquid 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). TheKd distribution coefficient is used to assess the degree to which a chemical species will be removedfrom
8、solution (permanently or temporarily) as the fluid migrates through the geologic medium; medium or contacts a solidmaterial; that is, theKd distribution coefficient is used to calculate the retardation factor that quantifies how rapidly an ion can moverelative to the rate of ground-water movement.Th
9、is test method is for the laboratory determination of the distribution coefficient (Kd), which may be used by qualified expertsfor estimating the retardation of contaminants for given underground geochemical conditions based on a knowledge andunderstanding of important site-specific factors. It is b
10、eyond the scope of this test method to define the expert qualificationsrequired, or to justify the application of laboratory data for modeling or predictive purposes. Rather, this test method is consideredas simply a measurement technique for determining the degree of partitioning between liquid and
11、 solid, under a certain set ofconditions, for the species of interest.Justification for the distributionKd coefficient concept is generally acknowledged to be based on expediency in modeling-averaging the effects of attenuation reactions. In reference to partitioning in soils, equilibrium is assumed
12、 although it is known thatthis may not be a valid assumption in many cases.The distribution coefficient (Kd) for a specific chemical species may be defined as the ratio of the mass sorbed per unit of solidphase to the mass remaining per unit of solution, as expressed in the above equation. The usual
13、 units of Kd are mL/g (obtainedby dividing g solute/g solid by g solute/mL solution, using concentrations obtained in accordance with this test method).Major difficulties exist in the interpretation, application, and meaning of laboratory-determined distributionKd coefficient valuesrelative to a rea
14、l system of aqueous fluid migrating through geologic media (1)2. The distribution coefficient or Kd concept is basedon an equilibrium condition for given reactions, which may not be attained in the natural situation because of the time-dependence1 This test method is under the jurisdiction of ASTM C
15、ommittee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.13 on Spent Fuel andHigh Level Waste.Current edition approved Oct. 1, 2010Aug. 1, 2017. Published October 2010August 2017. Originally approved in 2010. Last previous edition approved in 2010 asC1733 10. DOI: 10.1
16、520/C173310.10.1520/C1733-17.2 The boldface 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. Becaus
17、eit may not be technically possible to adequately 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 Bar
18、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1or kinetics of specific reactions involved. Also, migrating solutions always follow the more permeable paths of least resistance,such as joints and fractures, and larger sediment grain zones. This tends to allow less time f
19、or reactions to occur and less sedimentsurface exposure to the migrating solution, and may preclude the attainment of local chemical equilibrium.Sorption phenomena also can be strongly dependent upon the concentration of the species of interest in solution. Therefore,experiments performed using only
20、 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 ionic speciesanticipated to be present in a migrating solution, in order to address competing i
21、on 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 considered indeterminations of Kd. Values of pH must be determined, preferably in the field when m
22、aterials 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 effect on the Kd and need to be considered for each situation.Site-specific materials must be us
23、ed 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), and biologicalconditions (for example, bacterial growth and organic matter). Special precaut
24、ions 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 means of preservation (such as addition of acid to groundwater) will cause changes in sample c
25、hemistry 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 the porous medium.As it moves, it displaces the original ground water, withsome mixing cause
26、d 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 encountered by the contaminanthas had many pore volumes of the contaminant source water pass thro
27、ugh 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 recommended that ground water representative of the test zone (but containing added tracers) be us
28、ed as contact liquidin this test; test, or a carefully prepared simulated (site-specific) groundwater; concentrations of potential contaminants of interestused in the contact liquid should be judiciously chosen. For studies of interactions with intrusion waters, the site-specific groundwater may be
29、substituted by liquids of other compositions.The distributionKd coefficient for a given chemical species generally assumes a different value when conditions are altered.Clearly, a very thorough understanding of the site-specific conditions that determine their values is required if one is to confide
30、ntlyapply the Kd concept to 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 are in contact with one another, are measured. Other methods
31、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 (nonsorbing)(non-sorbing) tracer and one that does sorb; from the difference in travel times of the two tracers,Kd can be calculated.In s
32、ummary, 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 done judiciously by qualified experts with a know
33、ledge 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 geomediasolid surface (or geomedia) and the migrating fluid, distributionKd coefficients can be used for a
34、ssessing the rate of migration ofchemical species through a saturated 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 primarily intend
35、ed to assess sorption of dissolved ionic speciessubject to migration through pores and interstices of site specific geomedia. geomedia, or other solid material. It may also beapplied to other materials such as manufactured adsorption media and construction materials. Application of the results tolon
36、g-term field behavior is not addressed in this method. DistributionKd coefficients for radionuclides in selected geomedia or othersolid materials are commonly determined for the purpose of assessing potential migratory behavior of contaminants in thesubsurface of contaminated sites and waste out of
37、a waste form and in the surface of waste disposal facilities. This test methodis also applicable to studies for parametric studies of the variables and mechanisms which contribute to the measured distributionKdcoeffcient1.2 The values stated in SI units are to be regarded as standard. No other units
38、 of measurement are included in this standard.1.3 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 and health practices and determine the applicability of regula
39、torylimitations prior to use.C1733 1721.3 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 of
40、regulatory limitations prior to use.1.4 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 O
41、rganization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3D422 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 Soil and Rock by M
42、assD2217 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 Distribution Ratios by
43、 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 Definitions of Terms Specific to This St
44、andard:3.1.1 distribution coeffcient, Kd, nthe concentration of a species sorbed on a solid material, divided by its concentration insolution in contact with the solid, solid material, under constant concentration conditions, as follows:Kd 5Mass of solute on the solid phase per unit mass of solid ph
45、aseMass of solute in solution per unit volume of the liquid phase (1)3.1.1.1 DiscussionBy constant concentration conditions, it is meant that the Kd values obtained for samples exposed to the contact liquid for twodifferent time periods (at least one day apart), other conditions remaining constant,
46、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 geomedia.solidmaterial.3.1.2 species, nspecific form of an element defined as to isotopic composition, electronic or oxidation state, complex ormol
47、ecular structure, or combinations thereof (2).3.1.3 tracer, nan identifiable substance, such as a dye or radioactive isotope, that can be followed through the course of amechanical, chemical, or biological process.4. Significance and Use4.1 The distribution coefficient, Kd, is an experimentally dete
48、rmined ratio quantifying the distribution of a chemical speciesbetween a given fluid and geomedium solid material sample under certain conditions, including the attainment of constant aqueousconcentrations of the species of interest. The Kd concept is used in mass transport modeling, for example, to
49、 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 (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 (unitless) expressed as a decimal.3 For referencedASTM standa
