State Scientific Institution “Institute for Single Crystals” (SSI ISC NASU)
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Transcript of State Scientific Institution “Institute for Single Crystals” (SSI ISC NASU)
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
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AlkAlk
R
O
CH2
O
N
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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
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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
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0
0,5
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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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