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Title:
COMPOSITIONS FOR THE REMOVAL OF HEAVY METALS
Document Type and Number:
WIPO Patent Application WO/2019/147664
Kind Code:
A1
Abstract:
Disclosed herein are compositions and methods for sequestering heavy metal atoms, including hazardous atoms such as lead and radiocesium, from contaminated areas. The heavy metal atoms may be removed by contacting the contaminated area with a potassium-depleted muscovite-enriched composition. The compositions may also be incorporated into building materials to create structures to safely house nuclear reactors and other devices which may accidentally release heavy metal atoms.

Inventors:
ELLIOTT, W. Crawford (3278 Kensington Road, Avondale Estates, Georgia, 30002, US)
WAMPLER, J. Marion (4053 Commodore Drive, Chamblee, Georgia, 30341-1555, US)
KWONG-MOSES, Dominique S. (5546 Wydella Road, Lilburn, Georgia, 30047, US)
Application Number:
US2019/014742
Publication Date:
August 01, 2019
Filing Date:
January 23, 2019
Export Citation:
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Assignee:
GEORGIA STATE UNIVERSITY RESEARCH FOUNDATION, INC. (100 Auburn Avenue, Suite 532Atlanta, Georgia, 30303, US)
International Classes:
B01D21/00; B01D21/01; B09B3/00
Attorney, Agent or Firm:
CUTCHINS, William W. et al. (Meunier Carlin & Curfman LLC, 999 Peachtree Street N.E.,Suite 130, Atlanta Georgia, 30309, US)
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Claims:
CLAIMS

What is claimed is:

1. A method for sequestering heavy metal atoms from a contaminated area, comprising contacting the contaminated area with a muscovite-enriched mineral composition, wherein the muscovite is potassium-depleted.

2. The method according to claim 1, wherein the potassium-depleted muscovite contains no more than 10%, no more than 9%, no more than 8%, no more than 7%, no more than 6%, no more than 5%, or no more than 4% by mass of potassium relative to the total mass of the muscovite.

3. The method according to claim 1 or claim 2, wherein the muscovite-enriched mineral composition comprises muscovite in an amount at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% by mass relative to the total mass of the muscovite-enriched mineral.

4. The method according to any of claims 1-3, wherein the muscovite-enriched mineral has a particle size Dio that is at least greater than 5 pm, at least greater than 10 pm, at least greater than 15 pm, at least greater than 20 pm, at least greater than 25 pm, at least greater than 30 pm, at least greater than 40 pm, at least greater than 50 pm, at least greater than 75 pm, or at least greater than 100 pm.

5. The method according to any of claims 1-4, wherein the muscovite-enriched mineral has a particle size D90 that is no more than 2,000 pm, no more than 1,500 pm, no more than 1,250 pm, no more than 1,000 pm, no more than 900 pm, no more than 800 pm, no more than 700 pm, no more than 600 pm, or no more than 500 pm.

6. The method according to any of claims 1-5, wherein the muscovite-enriched mineral absorbs cesium with a Kd ([Cs] soiid/[Cs]aqueous) that is greater than 1,000 L/kg, greater than 1,200 L/kg, greater than 1,000 L/kg, greater than 1,200 L/kg, greater than 1,400 L/kg, greater than 1,600 L/kg, greater than 1,800 L/kg, or greater than 2,000 L/kg.

7. The method according to any of claims 1-6, wherein the heavy metal atoms comprise Cs, Pb, Sr, Rb, Ba, or a mixture thereof.

8. The method according to any of claims 1-7, wherein the heavy metal atoms comprise 137Cs.

9. The method according to any of claims 1-8, wherein the contaminated area comprises 137Cs in an amount of at least 500 at least kBq/m2, at least 500 at least kBq/m2, at least 750 kBq/m2, at least 1000 kBq/m2, at least 1,250 kBq/m2, at least l,500kBq/m2, at least 2,000 kBq/m2, at least 2,500 kBq/m2, or at least 3,000 kBq/m2.

10. The method according to any of claims 1-9, wherein the contaminated area comprises a soil, and the muscovite-enriched mineral composition is blended into the soil, overlaid on top of the soil, buried under the soil.

11. The method according to any of claims 1-9, comprising contacting the contaminated area with a permeable container comprising the muscovite-enriched mineral composition.

12. The method according to claim 11, wherein the contaminated area comprises a body of water, and the contaminated water is passed through a permeable container containing the muscovite-enriched mineral composition.

13. The method according to claim 10, wherein the contaminated area comprises a soil, and the permeable container is buried in the soil for a time sufficient to sequester the heavy metal atoms.

14. The method according to claim 13, wherein the heavy metal atoms comprise 137Cs.

15. A building material comprising a muscovite-enriched mineral composition, wherein the muscovite is potassium-depleted.

16. The building material according to claim 15, wherein the potassium-depleted

muscovite contains no more than 10%, no more than 9%, no more than 8%, no more than 7%, no more than 6%, no more than 5%, or no more than 4% by mass of potassium relative to the total mass of the muscovite.

17. The building material according to claim 15 or claim 16, wherein the muscovite- enriched mineral composition comprises muscovite in an amount at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% by mass relative to the total mass of the muscovite-enriched mineral.

18. The building material according to any of claims 15-17, wherein the muscovite- enriched mineral has a particle size Dio that is at least greater than 5 pm, at least greater than 10 pm, at least greater than 15 pm, at least greater than 20 pm, at least greater than 25 pm, at least greater than 30 pm, at least greater than 40 pm, at least greater than 50 pm, at least greater than 75 pm, or at least greater than 100 pm.

19. The building material according to any of claims 15-18, wherein the muscovite- enriched mineral has a particle size D90 that is no more than 2,000 pm, no more than 1,500 pm, no more than 1,250 pm, no more than 1,000 pm, no more than 900 pm, no more than 800 mih, no more than 700 mih, no more than 600 mih, or no more than 500 mih.

20. The building material according to any of claims 15-19, wherein the material is a dry concrete mix.

21. The building material according to any of claims 15-20, wherein the building material comprises the muscovite-enriched mineral composition in an amount no more than 20% by weight, no more than 15% by weight, no more than 12.5% by weight, no more than 10% by weight, no more than 7.5% by weight, no more than 5% by weight, no more than 2.5% by weight, or no more than 1% by weight.

22. The building material according to any of claims 15-21, wherein the building material is a concrete mix further comprising cement, sand, and aggregate.

Description:
COMPOSITIONS FOR THE REMOVAL OF HEAVY METALS

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application 62/620,710, filed January 23, 2018, the contents of which are hereby incorporated in its entirety.

FIELD OF THE INVENTION

The invention is directed to muscovite-enriched compositions with high affinity for heavy metal atoms. The muscovite-enriched compositions are useful for the sequestration of heavy metals.

BACKGROUND

Aqueous solutions of radioactive waste have been found percolating through soils adjacent to sites where radioactive materials have been produced, for instance, in nuclear reactors. A large constituent of this aqueous radioactive waste is radiocesium, in which 137 Cs is the predominant isotope. Concern for the fate of 137 Cs stems fourfold from its high fission yield and moderately long half-life (30.17 years) and the high mobility and high biological availability of Cs in certain regolith environments.

Radiocesium has been introduced into the environment as a direct result of nuclear accidents, nuclear weapons testing, and other nuclear development activities. For example, at the Savannah River Site (Aiken, SC, USA), approximately 1900 curies of 137 Cs were released into the environment, as reported in 1991. Another locality of high radiocesium

contamination is the area around the Fukushima Dai-ichi reactors (Fukushima Prefecture, Japan). Radiocesium and radioactive iodine were accidentally released from the Fukushima Dai-ichi reactors in 2011 in one of the largest accidental releases of radionuclides. Short-lived radioactive iodine decayed away within a matter of months, and 134 Cs has mostly decayed away; 137 Cs is by far the most abundant remaining radionuclide found in soils of Fukushima Prefecture and surrounding areas of Japan.

There remains a need for methods of eliminating heaving metals from contaminated area, including soils and drinking waters. There remains a need for eliminating lead contamination from drinking water sources. There remains a need for methods of eliminating 137 Cs from contaminated areas. There remains a need for methods of safely sequestering 137 Cs over the lifetime of its radioactivity. The remains a need for limiting the spread of inadvertently released 137 Cs. There remains a need for building materials capable of sequestering radiocesium unintentionally released from a reactor source.

SUMMARY

Disclosed herein are compositions and methods of sequestering heavy metals, including 137 Cs. In some instances, the compositions can be contacted with a contaminated area in order to remove the heavy metals, including 137 Cs. For instance, the composition can be admixed with contaminated soils and bodies of water. Contaminated waters can be passed through a sorption bed containing the composition enriched in potassium-depleted muscovite. Also disclosed here are concretes and other building materials that include a potassium- depleted muscovite. The building materials may be advantageously deployed in the construction of structures intended to house nuclear reactors and other sources of radiocesium and radioactive heavy metals.

The details of one or more embodiments are set forth in the descriptions below. Other features, objects, and advantages will be apparent from the description and from the claims.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 depicts an X-ray diffraction pattern for a randomly oriented portion of a powdered sample of the mineral composition enriched in potassium-depleted muscovite. M: muscovite, K: kaolin group minerals, Q: quartz.

Figure 2 depicts an X-ray diffraction pattern for an air-dried, oriented mount of part of a very finely powdered sample of the mineral composition enriched in potassium-depleted muscovite. (M for muscovite, Q for quartz, K for kaolinite.)

Figure 3 depicts an X-ray diffraction pattern for an ethylene glycol-solvated, oriented mount of another part of the very finely powdered sample.

Figure 4 depicts the concentration of solid phase Cs in units of mol/kg against the concentration of aqueous phase Cs in units of mol/L for the three sampling events (18 hours, 60 days and 130 days).

Figure 5 depicts the Kd value for each batch sample test suspension plotted against the initial concentration of Cs in the corresponding test suspension.

Figure 6 depicts the desorption Kd values in units of L/kg against the initial concentration of Cs in mol/L. DETAILED DESCRIPTION

Before the present methods and systems are disclosed and described, it is to be understood that the methods and systems are not limited to specific synthetic methods, specific components, or to particular compositions. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

As used in the specification and the appended claims, the singular forms“a,”“an” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from“about” one particular value, and/or to“about” another particular value. When such a range is expressed, another embodiment includes-· from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent“about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

“Optional” or“optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as“comprising” and“comprises,” means“including but not limited to,” and is not intended to exclude, for example, other additives, components, integers, or steps.“Exemplary” means“an example of’ and is not intended to convey an indication of a preferred or ideal embodiment. “Such as” is not used in a restrictive sense, but for explanatory purposes.

Disclosed are components that can be used to perform the disclosed methods and systems. These and other components are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these components are disclosed that while specific reference of each various individual and collective combinations and permutations of these may not be explicitly disclosed, each is specifically contemplated and described herein, for all methods and systems. This applies to all aspects of this application including, but not limited to, steps in disclosed methods. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods. Disclosed herein are compositions and methods for sequestering heavy metals, for instance Cs, Rb, Ba, Sr, and Pb. In some cases, the Cs is 137 Cs. In some embodiments, a composition including a muscovite-enriched mineral composition is contacted with an area contaminated with one or more heavy metals, including 137 Cs. In some embodiments, a muscovite-enriched mineral composition is included in a building material, for instance a concrete mix. The muscovite can be potassium-depleted muscovite, for instance potassium- depleted muscovite can contain no more than 10%, no more than 9%, no more than 8%, no more than 7%, no more than 6%, no more than 5%, or no more than 4% by mass of potassium relative to the total mass of the muscovite. Potassium content can be determined and reported as mass fraction K2O using conventional elemental analysis.

Although the mineral composition may contain other phyllosilicates and other minerals, it is preferred the mineral composition contains muscovite in an amount that is at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% by mass relative to the total mass of the mineral composition. Muscovite content may be assessed using X-ray diffraction and PANalyti cal’s HighScore Semi- Quantitative Analysis. Other components that may be present in the composition include kaolin minerals and quartz.

The mineral compositions useful for the sequestration of radiocesium may be characterized by the particle sizes of the minerals. For instance, the mineral composition can have an overall particle size distribution in which Dio (the value of particle size exceeded by 90% of the composition, by mass) will be at least 5 pm, at least 10 pm, at least 15 pm, at least 20 pm, at least 25 pm, at least 30 pm, at least 40 pm, at least 50 pm, at least 75 pm, or at least 100 pm. In some instances, the mineral composition can have a particle size distribution in which Dio (the value of particle size exceeded by 90% of the muscovite, by mass) will be at least 5 pm, at least 10 pm, at least 15 pm, at least 20 pm, at least 25 pm, at least 30 pm, at least 40 pm, at least 50 pm, at least 75 pm, or at least 100 pm.

In some embodiments, the mineral composition can have an overall particle size distribution in which D90 (the value of particle size exceeded by 10% of the composition, by mass) will be no more than 2,000 pm, no more than 1,500 pm, no more than 1,250 pm, no more than 1,000 pm, no more than 900 pm, no more than 800 pm, no more than 700 pm, no more than 600 pm, or no more than 500 pm. In some embodiments, the muscovite can have a particle size distribution in which D90 (the value of particle size exceeded by 10% of the muscovite, by mass) will be no more than 2,000 pm, no more than 1,500 pm, no more than 1,250 mih, no more than 1,000 mih, no more than 900 mih, no more than 800 mih, no more than 700 mih, no more than 600 mih, or no more than 500 mih.

The compositions disclosed herein have high affinity for cesium atoms (as monovalent cations). The affinity may be assessed by Kd ([Cs] S oiid/[Cs] a queous), as measured at a total electrolyte content of 1 mmol/L, that is greater than 1,000 L/kg, greater than 1,200 L/kg, greater than 1,400 L/kg, greater than 1,600 L/kg, greater than 1,800 L/kg, or greater than 2,000 L/kg. High affinities for other heavy metals, including Pb, Ba, Sr, and Rb, can also be observed.

The compositions disclosed herein may be used to sequester and remove cesium from areas contaminated with high concentrations of 137 Cs. For instance, the compositions can remove cesium from a contaminated area that can include 137 Cs in an amount of at least 500 kBq/m 2 , at least 750 kBq/m 2 , at least 1000 kBq/m 2 , at least 1,250 kBq/m 2 , at least 1,500 kBq/m 2 , at least 2,000 kBq/m 2 , at least 2,500 kBq/m 2 , or at least 3,000 kBq/m 2 .

Heavy metals, including radiocesium can be sequestered within or removed from contaminated soils and water bodies. In some embodiments, the compositions can simply be blended into the contaminated soil. Over time, the heavy metals will aggregate in the potassium-depleted muscovite, thereby effectively immobilizing it. In other embodiments, the compositions can be contacted with contaminated soils and waters for a time sufficient to sequester the heavy metal, for instance radiocesium, after which time the compositions can be removed and safely stored. The compositions can be placed within a permeable container and then buried in contaminated soils or submerged in contaminated waters. In other embodiments, a fixed bed device can be employed, in which contaminated water is passed through a tube containing the potassium-depleted muscovite. The water can be pumped or be fed through the tube under the force of gravity.

Also disclosed herein are building materials including a muscovite-enriched mineral composition, as described above. Exemplary building compositions include concretes including a muscovite-enriched mineral composition. For instance, the muscovite-enriched mineral composition is present in a dry concrete mix in an amount from 0.1-20% by weight, from 0.5-20% by weight, from 1-20% by weight, from 2.5-20% by weight, from 5-20% by weight, from 7.5-20% by weight, from 10-20% by weight, from 15-20% by weight, from 10- 15% by weight, from 5-10% by weight, from 0.5-5% by weight, from 0.5-2.5% by weight, or from 1-5% by weight. In some instances, the muscovite-enriched mineral composition is present in an amount no more than 20% by weight, no more than 15% by weight, no more than 12.5% by weight, no more than 10% by weight, no more than 7.5% by weight, no more than 5% by weight, no more than 2.5% by weight, or no more than 1% by weight.

In some aspects of the invention, the muscovite-enriched mineral composition is combined with a cement, sand, and aggregate to give a concrete mix. A preferred cement is Portland cement. Exemplary weight ratio combinations are presented in the following table:

EXAMPLES

The following examples are for the purpose of illustration of the invention only and are not intended to limit the scope of the present invention in any manner whatsoever.

A sample of a potassium-depleted muscovite-enriched mineral composition was obtained from the Georgia kaolin deposits, separated from mined kaolin by Southeast Performance Minerals. The bulk sample had the following particle size distribution:

Table 1. Particle size distribution from sieving

A small fraction (8% by mass) of the bulk sample consists of particles that have diameters between 0.25 mm and 0.84 mm. Most (79% by mass) of the bulk sample consists of particles between 0.044 mm and 0.25 mm in diameter, and 13% (by mass) of the bulk sample consists of particles smaller than 0.044 mm in diameter.

The X-ray diffraction pattern for a randomly oriented powdered portion of the bulk sample is shown in Figure 1. This test material is composed of muscovite, kaolin group minerals, and quartz. The semi-quantitative abundances of these minerals were determined as: 76% muscovite, 21% kaolin group, and 3% quartz per phase determination using PANalyticaTs HighScore Semi-Quantitative Analyses.

Each value of interlayer spacing (ri-value) in Figure 1 is paired with the single letter abbreviation for the mineral identity with which it corresponds, as determined via comparison against reference c/- values. M- muscovite, K-kaolin group minerals (kaolinite), q-quartz.

Diffraction patterns of parts of a very finely powdered portion of the bulk sample, prepared as oriented mounts on glass petrographic slides, are shown in Figures 2 and 3.

Muscovite and kaolin group minerals are the predominant minerals seen in the very fine materials. One of these oriented mounts was solvated with ethylene glycol to test for the presence of smectite, interlayer clays, and vermiculite via comparison against the other, air- dried, oriented mount. No difference between the air-dried (Figure 2) and ethylene glycol- solvated (Figure 3) materials was observed. Table 2: Annotated Aval ues from a randomly oriented powder sample diffraction scan.

Table 3. Annotated /-val ues from the air-dried oriented clav mount diffraction scan.

Table 4 Annotated ri-values from the glycol-solvated oriented clay mount diffraction scan.

With respect to experimentally determined ri-values, the HighScore software indicated that the mineral dickite is a better match than kaolinite; however, based on the sample’s original locality, the sample deductively contains kaolinite. The most intense diffraction peaks corresponding exclusively to nacrite (2.41Ά) and dickite (2.32 A) were not observed. Kaolinite is the prevalent kaolin group mineral in the sample. Since the ri- values remained unchanged in the ethylene glycol-solvated mount, the sample is unlikely to contain a significant fraction of smectite. This solvation demonstrated also that kaolinite-smectite interstratified minerals were not present in this sample. An evident asymmetric peak on the high c/- value side of the 001 peak for kaolinite was not observed. Kaolinite is not

interstratified with other phyllosilicate minerals (muscovite) in the sample.

The mass fractions of major element oxides in the muscovite-enriched mineral composition (as received and split) are shown in the central column of Table 5 (below) as percent by mass of corresponding oxides. The sum of the major element oxides including loss on ignition (LOI) is 99.22%. The chemical composition of the muscovite alone was calculated by correction for the 21% of kaolinite and the 3% of quartz in the sample, as determined by X-ray diffraction. The K2O content of the muscovite (9.98%) is less than that of pure muscovite (11.81 wt. %), which demonstrates that the muscovite is potassium- depleted. Table 5. Results of major-element analysis of the muscovite-enriched mineral composition and the calculated chemical composition of the muscovite alone

Oxide Mass fraction (%) Muscovite alone (%) j \a'() 0.52 45.20 |

[ . K 'O . j . 7.51 . j . 34.49 . |

I . Si O' . [ . 46.78 . [ . 2.09 . |

[ AI 'O ; | 34.24 0.73 j

I ' e'O ; 1 .57 [ 1.17 |

I MgO 0.55 [ 0.02 I TiO' j 0.88 j 0.03 |

. CaO . [ . 0.02 . . 9.98 . |

[ VI nO j 0.014 j 0.69 |

I . P2O5 . [ . 0.03 . [ . 5.56 . !

! LOI 1 7. 1 I { 0.04 I i Total 1 99.22 1 100.00 ]

The sorption of radioactive cesium ( 137 Cs) from aqueous solution onto the muscovite- enriched mineral composition was observed in 20 test suspensions (each a 0.1 g test portion of the sample in 10 mL of liquid) containing variable amounts of added stable cesium ( 133 Cs). The activity of radioactive cesium remaining in the liquid phase after 18 hours, 60 days, and 130 days of tumbling was determined by liquid scintillation counting (LSC). The liquid phase 137 Cs activity concentration was obtained directly from LSC measurement. Solid phase 137 Cs activity was calculated from the difference between the quantity of added 137 Cs and that of 137 Cs remaining in the aqueous phase.

Tables 6a, 6b, and 6c (below) present the aqueous and solid phase concentrations of Cs as calculated from the LSC data for the three sampling events (18 hours, 60 days, and 130 days, respectively). Tables 6a, 6b, and 6c also include the Kd values for each batch sorption test suspension at 18 hours, 60 days, and 130 days and the concentration of total Cs in each batch sorption test suspension. No data are shown for two additional test suspensions, which were blanks to which no 137 Cs and no 133 Cs were added. Table 6a: Results for batch sorption experimentation as calculated from LSC data after 18 hours of tumbling

Table 6b: Results for batch sorption experimentation as calculated from LSC data after 60 days of tumbling

Table 6c: Results for batch sorption experimentation as calculated from LSC data after 130 days of tumbling

Figure 4 plots the concentration of solid phase Cs in mol/kg against the concentration of aqueous phase Cs in mol/L for the three sampling events (18 hours, 60 days, and 130 days). In Figure 5, the Kd value for each batch test suspension is plotted against the concentration of total Cs in the corresponding test suspension. The K d values for the suspensions with smaller total Cs concentrations increased with time, resulting in an inverse relation between K d and the concentration of total Cs after 60 days and a stronger inverse relationship after 130 days.

Following 130 days of batch sorption experimentation, desorption test suspensions were created by centrifuging each suspension, decanting the supernatant liquid, and replacing the supernatant liquid with a solution of NaCl (10 mM NaCl for la-lOa; 1 mM NaCl for lb- lOb) to introduce Na + as a counterion. These desorption test suspensions were tumbled for 60 days, then centrifuged and sampled to yield the following data.

Table 7a: Results from desorption into 10 mM NaCl after 60 days

Table 7b: Results from desorption into 1 mM NaCl after 60 days

Tables 7a and 7b present data collected after 60 days of desorption for test suspensions containing 10 mM NaCl and 1 mM NaCl, respectively. The activity

concentrations of 137 Cs in the aqueous phase were measured directly by LSC. The activity of 137 Cs in the solid phase was calculated as the difference between the activity of 137 Cs on the solid at the start of the desorption period and the measured activity of aqueous 137 Cs. The fraction of 137 Cs desorbed from the mica, a measure of the reversibility of the sorption reaction, was found by subtracting from unity the ratio of 137 Cs activity on the solid at the sampling time (t) to the 137 Cs activity on the solid at the start of the desorption process.

Figure 6 plots the desorption Kd in L/kg against the concentration of total Cs in mol/L. The data are presented on logarithmic scales, allowing for differentiation of the two groups of batch desorption test suspensions— one group containing 10 mM NaCl; the other containing 1 mM NaCl. Two different concentrations (1 mM and 10 mM) of NaCl were used in the batch desorption experiment to examine the effect of counterion concentration on desorption behavior. That the Kd values are consistently smaller for the 10 mM NaCl test portions than for the 1 mM NaCl test portions is due to mass action. A larger concentration of competing sodium cations leads to more desorption of the cesium cations that had been bound to the mica. Overall, Kd values derived for desorption are very large, meaning that very little 137 Cs was desorbed from the mica. Large Kd values support practical industrial application for the muscovite.

The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less, however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated. The term“comprising” and variations thereof as used herein is used synonymously with the term“including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and“including” have been used herein to describe various embodiments, the terms“consisting essentially of’ and“consisting of’ can be used in place of“comprising” and“including” to provide for more specific embodiments of the invention and are also disclosed. Other than in the examples, or where otherwise noted, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood at the very least, and not as an ahempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches.