Ultrafast Chemical Separations (1993) / Chapter Skim
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4. Autobatch Techniques
4. Autobatch Techniques
Pages 37-48
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From page 37... ...
For a nuclide with a half-life of ~ s, the low value of 0.185 is reached even when the sample changing time is 4 s. The time required for chemical separation win essentially be Me deciding factor as to whether Me autobatch technique win be acceptable for studying nuclides with half-lives on Me order of a second or less.
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From page 38... ...
The entire operation was performed with the use of syringes, valves, and stopcocks that were operated automatically by an electronic programmer. The entire sequence of operation was Initiated by a signal received from photodiodes placed in the reactor, and was triggered by the Cerenkov radiation accompanying the neutron burst of the TRIGA reactor.
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From page 39... ...
Germanium Vocalization ~5 s Ge-l,2 Hafnium Ion exchange I~20 s Hf-3 Lan~an'4es Extraction, ion exchange <3 min Ln-1 Lan~anides Gas chromatography Few min En-3 Lawrencium Cation exchange (HPLC) 160 s Er4 Lawrencium (from Md)
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From page 40... ...
The chemical steps consisted of removing the halogens from the fission-product solution by exchange with preformed silver chloride, oxidizing technetium to pertechnetate by ammonium persulfate in the presence of Ag+, and extraction of technetium with tetraphenylarsonium chloride in chloroform on Chromosorb. The technetium was then eluted from the Chromosorb layer.
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From page 41... ...
Filtration was accomplished by applying vacuum at position 2 and opening stopcock 2. The Chromosorb layer was washed with 15 mL of O.1N HNO3 costarring tartaric acid; the wash solution was transferred by opening stopcock 3 and applying pressure at position 2.
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From page 42... ...
is a good example of the adaptation of conventional solvent extraction technique for fast separation with the use of miniature centrifugal contactors. Figure 15 shows a schematic of the palladium chemical separation system they used.
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From page 43... ...
Isolation of silver daughter activities from short-lived palladium isotopes was also achieved using this system. The NH4OH strip from the Gird centrifugal contactor was acidified with SM HNO3 and passed through a column of preformed silver chloride (replacing the glass woo!
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From page 44... ...
The rabbit was caught and moved to a second position, where the fission-product solution was extracted and transferred to a reaction chamber containing carrier solutions. The solution was purged with nitrogen gas for 600 me to remove fission krypton and xenon.
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From page 45... ...
The nuns performed during the course of 10 days accumulated 25 minion coincidence events. The fact that such chemical separations could be performed using highly automat systems indicates Me reliability and usefulness of autobatch techniques for uluafast chemistry.
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From page 46... ...
and by Elchuk and Cassidy [Elc791. The nuclear chemistry group at Idaho National Engineering Laboratory developed an automatic chemistry system using high-pressure liquid chromatography for the separation of lanthanides [Bak8O, BakS1, BakS21.
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From page 47... ...
~ ~: -- -- Vacuum seal (rubber) : i~ Mylar tape supply reels \~Mylar tape | take-up reels , ~ - L,Issolullon acid jets _/ · ~[~ I , - Air actuated ~ 3 way valve Funnel Dissolved fission NH4OH inlet products outlet Fission product dissolution chamber Figure 19.
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From page 48... ...
Schematic of autobatch lanthanide chemistry. [BakS2; reprinted w~th perm~ssion from-~.
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