7-1 Ion Exchange Resins General resin information Functional Groups Synthesis Types Structure Resin Data Kinetics Thermodynamics Distribution Radiation effects Ion Specific Resins

7-2 Ion Exchange Resins Resins Organic or inorganic polymer used to exchange cations or anions from a solution phase General Structure Polymer backbone not involved in bonding Functional group for complexing anion or cation

7-3 Resins Properties Capacity  Amount of exchangeable ions per unit quantity of material *Proton exchange capacity (PEC) Selectivity  Cation or anion exchange *Cations are positive ions *Anions are negative ions  Some selectivities within group *Distribution of metal ion can vary with solution

7-4 Resins Exchange proceeds on an equivalent basis Charge of the exchange ion must be neutralized  Z=3 must bind with 3 proton exchanging groups Organic Exchange Resins Backbone  Cross linked polymer chain *Divinylbenzene, polystyrene *Cross linking limits swelling, restricts cavity size

7-5 Organic Resins Functional group  Functionalize benzene *Sulfonated to produce cation exchanger *Chlorinated to produce anion exchanger

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7-8 Resin Synthesis aa a resorcinol catechol HOOH HCOH NaOH, H 2 O HOOH n HCOH NaOH, H 2 O OH n

7-9 Resins Structure Randomness in crosslinking produces disordered structure  Range of distances between sites  Environments *Near organic backbone or mainly interacting with solution Sorption based resins Organic with long carbon chains (XAD resins) Sorbs organics from aqueous solutions Can be used to make functionalized exchangers

7-10 Organic Resin groups Linkage group Cation exchange Chloride Anion exchange

7-11 Resin Structure

7-12 Inorganic Resins More formalized structures Silicates (SiO 4 ) Alumina (AlO 4 )  Both tetrahedral  Can be combined *(Ca,Na)(Si 4 Al 2 O 12 ).6H 2 O  Aluminosilicates *zeolite, montmorillonites *Cation exchangers *Can be synthesized Zirconium, Tin- phosphate

7-13 Zeolite

7-14 Inorganic Ion Exchanger Easy to synthesis Metal salt with phosphate Precipitate forms  Grind and sieve Zr can be replaced by other tetravalent metals Sn, Th, U

7-15 Kinetics Diffusion controlled Film diffusion  On surface of resin Particle diffusion  Movement into resin Rate is generally fast Increase in crosslinking decrease rate Theoretical plates used to estimate reactions Swelling Solvation increases exchange Greater swelling decreases selectivity

7-16 Selectivity Distribution Coefficient D=Ion per mass dry resin/Ion per volume The stability constants for metal ions can be found Based on molality (equivalents/kg solute) Ratio (neutralized equivalents)  Equilibrium constants related to selectivity constants Thermodynamic concentration based upon amount of sites available Constants can be evaluated for resins  Need to determine site concentration

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7-29 Radioactive considerations High selectivity Cs from Na Radiation effects Not sensitive to radiation  Inorganics tend to be better than organics High loading Need to limit resin change Limited breakthrough Ease of change Flushing with solution Good waste form Radioactive waste

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7-31 Hanford Tanks 177 Tanks Each Tank 3,800,000 Liters Three sections Salt cake Sludge Supernatant Interested in extracting Cs, Sr, Tc, and Actinides with Silicatitanates Resorcinol formaldehyde CS-100 (synthetic zeolite)

7-32 Ion Selective Resins Selected extraction of radionuclides Cs for waste reduction Am and Cm from lanthanides  Reprocessing  Transmutation Separation based on differences in radii and ligand interaction size and ligand Prefer solid-liquid extraction Metal ion used as template

7-33 Characteristics of Resins Ability to construct specific metal ion selectivity Use metal ion as template Ease of Synthesis High degree of metal ion complexation Flexibility of applications Different functional groups Phenol Catechol Resorcinol 8-Hydroxyquinoline

7-34 Resin Synthesis Catechol-formaldehyde resin (CF) Resorcinol-formaldehyde resin (RF) Phenol-8-hydroxyquinoline formaldehyde resin (PQF) Catechol-8-hydroxyquinoline formaldehyde resin (CQF) Resorcinol-8-hydroxyquinoline formaldehyde resin (RQF) Resins analyzed by IR spectroscopy, moisture regain, and ion exchange capacity

7-35 n HOOH Resorcinol Formaldehyde Resin n OH Catechol Formaldehyde Resin OH N n m x x = 0, Phenol-8-Hydroxyquinoline Formaldehyde Resin x = 1, Catechol-8-Hydroxyquinoline Formaldehyde Resin x = 1, Resorcinol-8-Hydroxyquinoline Formaldehyde Resin

7-36 Experimental IR spectroscopy Resin characterization  OH, C=C Aromatic, CH 2, CO Moisture regain 24 hour heating of 0.1 g at 100°C Ion exchange capacity Titration of 0.25g with 0.1 M NaOH

7-37 Moisture Regain and IEC ResinMoistureIECTheory IEC %meq/g% CF RF PQF CQF RQF Phenolic resins have lower IEC 8-hydroxyquinoline increase IEC

7-38 Experimental Distribution studies With H + and Na + forms 0.05 g resin 10 mL of M metal ion Metal concentration determined by ICP- AES or radiochemically Distribution coefficient C i = initial concentration C f = final solution concentration V= solution volume (mL) m = resin mass (g)

7-39 Cesium Extraction

7-40 Distribution Coefficients for Group 1 elements. All metal ions as hydroxides at 0.02 M, 5 mL solution, 25 mg resin, mixing time 5 hours D (mL/g (dry)Selectivity ResinLiNaKRbCsCs/NaCs/K PF RF CF

7-41 Cesium Column Studies with RF pH 14, Na, Cs, K, Al, V, As

7-42 Eu/La Competitive Extraction ResinLaEuEu/La CF2.38x x RF2.59x x PQF CQF RQF Distribution Coefficients, 2.5 mM Eu,La, pH 4

7-43 [Eu] = [La] = mol L-1, T(shaking) = 20h, m = 0.05g

7-44 Eu-La Separation

7-45 Studies with 243 Am Conditions similar to Eu studies 10 mL solution 0.05 g resin  RF, CF, PQF, RQF, CQF millimolar Am concentration Analysis by alpha scintillation >99% of Am removed by CF, RF, PQF ≈ 95% of Am removed by CQF, RQF 243 Am removed from resin by HNO 3

7-46 Ion Specific Resins Effective column separation possible Phenol exhibits selectivity Incorporation of 8-hydroxyquinoline leads to selectivity, but lower extraction Eu/La separation possible Possible to prepare ion specific resins for the actinides