1. Chromatographic separations
Separation of species prior to detection
Description
Migration rates
Efficiency
Applications

2. Description Different components of chromatography column support
stationary phase
Different degree of reaction
Chemicals separate into bands
Characteristics of phase exploited to maximize separation
mobile phase
Gas, liquid, supercritical fluid

3. Description Different methods available column chromatography
paper chromatography
gas-liquid chromatography
thin layer chromatography (TLC)
high-pressure liquid chromatography
HPLC
Also called high-performance liquid chromatography

5. Column Chromatography
chromatogram
concentration versus elution time
strongly retained species elutes last
elution order
analyte is diluted during elution
dispersion
zone broadening proportional to elution time

6. Column Chromatography
Separations enhanced by varying experimental conditions
adjust migration rates for A and B
increase band separation
adjust zone broadening
decrease band spread

7. Retention Time Time for analyte to reach detector Retention time (tR)
Ideal tracer
Dead time (tM)
Migration rate
v=L/ tR
L=column length
For mobile phase
u=L/ tM

8. Retention time
Relationship between retention time and distribution constant
V (volume)
c (concentration)
M (mobile phase)
S (stationary phase)

9. Capacity Factor Retention rates on column
k'A can be used to evaluate separation
Optimal from 2-10
Poor at 1
Slow >20
Selectivity factor (a)
Larger a means better separations

10. Broadening Individual molecule undergoes "random walk"
Many thousands of adsorption/desorption processes
Average time for each step with some variations
Gaussian peak
like random errors
Breadth of band increases down column because more time
Efficient separations have minimal broadening

11. Theoretical plates Column efficiency increases with number of plates
N=L/H
N= number of plates, L = column length, H= plate height
Assume equilibrium occurs at each plate
Movement down column modeled

12. Theoretical Plates Plate number can be found experimentally
Other factors that impact efficiency
Mobile Phase Velocity
Higher mobile phase velocity
less time on column
less zone broadening
H = A + B/ u + Cu
= A + B/ u + (CS + CM)u A
multipath term B
longitudinal diffusion term C
mass transfer term

13. Efficiency Multipath Molecules move through different paths
Larger difference in path lengths for larger particles
diffusion allows particles to switch between paths quickly and reduces variation in transit time
Diffusion term
Diffusion from zone (front and tail)
Proportional to mobile phase diffusion coefficient
Inversely proportional to flow rate
high flow, less time for diffusion

14. Efficiency

16. Ion Exchange Resins General resin information Functional Groups
Synthesis
Types
Structure
Resin Data
Kinetics
Thermodynamics
Distribution
Radiation effects
Ion Specific Resins

17. 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

18. 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

19. 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

20. Organic Resins Functional group Functionalize benzene
Sulfonated to produce cation exchanger
Chlorinated to produce anion exchanger

21. Resin Synthesis HO OH HO OH NaOH, H O HCOH resorcinol n OH OH OH OH2
HCOH
resorcinol n OH OH OH OH
NaOH, H O 2
HCOH
catechol n a a a

22. 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

23. Organic Resin groups Linkage group Cation exchange Anion exchange
Chloride

24. Resin Structure

25. Inorganic Resins More formalized structures Silicates (SiO4)
Alumina (AlO4)
Both tetrahedral
Can be combined
(Ca,Na)(Si4Al2O12).6H2O
Aluminosilicates
zeolite, montmorillonites
Cation exchangers
Can be synthesized
Zirconium, Tin- phosphate

26. Zeolite

27. 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

28. 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

29. 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

31. 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

32. 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

33. Resorcinol Formaldehyde Resin Catechol Formaldehyde ResinOH
Resorcinol Formaldehyde Resin
Catechol Formaldehyde Resin N m x
x = 0, Phenol-8-Hydroxyquinoline Formaldehyde Resin
x = 1, Catechol-8-Hydroxyquinoline Formaldehyde Resin
x = 1, Resorcinol-8-Hydroxyquinoline Formaldehyde Resin

34. 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
Ci = initial concentration
Cf = final solution concentration
V= solution volume (mL)
m = resin mass (g)

35. 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
Resin Li Na K Rb Cs Cs/Na Cs/K PF RF CF

36. Cesium Column Studies with RF
pH 14, Na, Cs, K, Al, V, As

37. Eu-La Separation

38. Solvent Extraction
Based on separating aqueous phase from organic phase
Used in many separations
U, Zr, Hf, Th, Lanthanides, Ta, Nb, Co, Ni
Can be a multistage separation
Can vary aqueous phase, organic phase, ligands
Uncomplexed metal ions are not soluble in organic phase
Metals complexed by organics can be extracted into organic phase
Considered as liquid ion exchangers

39. Extraction Reaction Phases are mixed
Ligand in organic phase complexes metal ion in aqueous phase
Conditions can select specific metal ions
oxidation state
ionic radius
stability with extracting ligands
Phase are separated
Metal ion removed from organic phase
Evaporation
Back Extraction

40. (CH3CH2)2O Diethyl ether

42. Reactions Tributyl Phosphate (TBP) (C4H9O)3P=O
Resonance of double bond between P and O
UO22+(aq) + 2NO3-(aq) + 2TBP(org) <-->UO2(NO3)2.2TBP(org)
Consider Pu4+
Thenoyltrifluoroacetone (TTA)
Keto
Enol
Hydrate

43. Problems with solvent extraction
TTA
General Reaction
Mz+(aq) + zHTTA(org) <-->M(TTA)z(org) + H+(aq)
What is the equilibrium constant?
Problems with solvent extraction
Waste
Degradation of ligands
Ternary phase formation
Solubility