National Academy of Sciences of UkraineNational Academy of Sciences of Ukraine

Sr and Cs selective calixarene-based sorbents: analytical application in environmental

chemistry

Radionuclides normalized in water of economical and drinking water supply sources*

Radionuclide Т1/2, years MCL, Bk/L

Natural radionuclides

222Rn 3,82 days 100

226Ra 1620 1

228Ra 5,75 1

U, isotope sum 1

Artificial nuclides, falling out as a result of an accidents

90Sr 29 2137Cs 33 2239Pu 24065

1 (total activity)240Pu 6537

241Pu 14,4

210Po 139 days

241Am 232

*Норми радіаційної безпеки України (НРБУ-97); Державні гігієнічні нормативи. – Київ: Відділ поліграфії українського центру держсанепіднагляду МОЗ України, 1997. – 125с.

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Composite materials for α- and β- emitting nuclides determination in water

The existing methods for radionuclide determination in natural waters are not sufficiently sensitive and precise

Goal of the work: - Obtaining materials, combining radionuclide concentration

and detection processes for utilization in radiation monitoring

- Development of their application methods for selective determination of radionuclide content in natural waters

Ways of accuracy improvement

Preliminary concentration of small

amounts of radionuclides from

large volume of investigated solution

Use of 4π-geometry emission

registration

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Methods Drawbacks

Flow detectors in combination with extraction or chromatography

Short counting time; poor resolution;detection limits for α-emitters -500 Bk/L, for β-emitters – 350 Bk/L

Liquid scintillating detectors in combination with extraction or chromatography

Deterioration of scintillation characteristics when large volume of water is used; high detection limits.

Porous scintillators with branchy surface

2-π registration geometry; clogging up of surface with radionuclides.

Radiochemical methods 21 stage of a sample preparation;activity measurement directly after separation stage and in 2-4 weeks, that is after equilibrium between Sr-90 and Y-90 is achieved.

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Aim of the work –creating material with the specified properties: selectivity towards radionuclide or radionuclide family; presence of through pores of desired size and

location; high light output and registration efficiency; analysis performance and low cost.

Analyzed solution

Pore forming agent

Sorbent

Radionuclide

Scintillator

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Material composition

Optimal scintillating matrix

p- Terphenyl(PTF) activated 1,3-diphenylbutadiene-1,4

PTF characteristics:λmax= 420nmtf = 3-5 nsZef = 5.8

PTF Advantages:Short luminiscence time;Stability in characteristics under influence if atmosphere and radiation;

Light output stability in broad temperature range (-60º…+140ºС);

Absence of scintillation characteristics anisotropy throughout volume;

Possibility of growing crystals with the diameter up to 80 mm.

Optimal pore forming agent

NH4HCO3.Tdec.= 36ºC.

Optimal sorbent

Sorbent characteristics:

high exchange capacity; mechanical durability; color absence; absence of own

luminescence; thermo- and radiation

stability.

For the determination of Sr and Cs we have used calixarene-impregnated

polymer matrix and zeolite. 6

OO

OO

OO

OO

LG LG

O

Alk Alk

OO

OO

OO

O

LG

OO

OO

OO

OO

AlkAlk

R

O

CH2

O

N

6

Alk

Alk

The structures of calixarenes with different functionality used in the present work as highly selective chelating agents

Compounds were given by V.I. Kalchenko, Corresponding Member of the National Academy of Sciences of Ukraine, Professor, Vice-director of the Institute of Organic Chemistry, Kyiv, Ukraine

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SEM images of polymerspheres cross-section in back-scattered electron mode

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Investigation methods

Inductively coupled plasma atomic emission spectrometry(ICP-AES), Thermo Jarrell Ash, USA

Operating conditions

λ (Sr) 421.55 /407.77 nmRF Power 1150 Wt

Plasma gas flow 14 L/minAuxiliary gas flow 1 L/minNebulizer gas flow 36 psi (2,5 atm)

Pump rate 100 rpmSolution uptake rate 1,85 mL/min

Integration time 2s

Flame atomic emission spectrometrySaturn, USSR

λ (Cs) 852.1 nmFlame Acetylene-Air

Integration time 1sSlit width 0.2 nm

Grating density 1200 nm-1

Operating conditions

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9

pH

Sr (a) and Cs (b) extraction rate dependencies on pH

3 6 9

0,0

0,3

0,6

pH

(a)

(b)

Divinyl bezene-styrene co-polymer impregnated with calix

[6]-areneamide

Divinyl bezene-styrene co-polymer impregnated with calix

[4]-arene-crown-6

10

0

0,5

1

1,5

2

2,5

3

3,5

4

4,5

0 2 4 6 8 10 12 14

C, мg/l

А, m

g/g

А

С

АL

КА

С 1(a)

CnF

KA log1

loglog (b),

Langmuir model (eq. a)

Metal cation

КL, l/мg А ∞, мg/g R2

Sr2+ 8.25 5.34 0,992

Cs+ 0.99 0.32 0.933

Freindlich model (eq. b)

Metal cation

КF, мg/g n R2

Sr2+ 1.11 1.35 0.982

Cs+ 9.11 1.64 0.997

C – ion equilibrium concentration, mg/l;A – equilibrium sorption capacity, mg/g;A∞ - maximum sorption capacity, mg/g;КL - Langmuir constant, l/mgКF – Freindlich constant, mg/g;n – Freindlich isotherm constant, indicating sorption intensity

where

Absorption isotherm of Sr2+ on the calix[6]areneamide impregnated polymer

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Absorption isotherm of Cs+on the calix[4]crown[6]arene impregnated polymer

Absorption isotherms

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Mordenitein -Na form

d < 0.125 mm

Removing diluent at 100ºCDrying at 120ºC

1g of calix[6]arene dissolved in

10 ml of CH2Cl2

Mordenite soaked in NaCl solution during 24 hours at ambient temperature

Washing with distilled water

Washing with distilled water

Washing with methanolTreated actively during 60 min

Drying at 50ºC during 3 hours

Impregnationtri-n-butyl phosphate

dissolved in CH2Cl2

Scheme of mordenite impregnation with calix[6]arene

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IR spectra of mordenite before and after impregnation with calix[6]arene

Distilled water 40%Model solution 4%

Without calixarene,model solution

8%

Sr recovery rates in systems containing calixarene-impregnated mordenite

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Prospective work

•Design of highly selective scintillating sorbent with the use of materials investigated

•Investigation and optimization of physicochemical parameters of the composite materials obtained

•Developing the experimental technique for measuring the radionuclide concentration in water samples with the use of porous scintillator obtained

The work is supported by STCU Grant No 4955 “Composite materials on the basis of highly selective calixarene sorbents for determination of radionuclides in environments”

Thank you very much for your kind attention!

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