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The adsorption of hydrogen on a molecular sieve at -196{sup o}C and the observation of an isotope effect; Adsorption d'hydrogene sur un tamis moleculaire a -196{sup o}C et observation d'un effet isotopique; Absorbtsiya vodoroda na molekulyarnom fil'tre pri -196{sup o} i nablyudenie rezul'tatov dejstviya izotopov; Adsorcion de hidrogeno en un tamiz molecular a -196{sup o}C y observacion de un efecto isotopico

Conference:

Abstract

Linde Molecular Sieve 4A has been examined as a possible means of handling small volumes of hydrogen isotopes in a vacuum system, as an alternative to the slow Toepler pump method. The equilibrium pressure (P) was measured for various volumes (V) of hydrogen adsorbed by 1 g of Sieve at -196{sup o}C. Experiments with activated charcoal showed the superiority of the Sieve as a hydrogen adsorbent. 1 g of the Sieve in a system of vol. 500 ml will adsorb about 97% of a 1-ml sample of hydrogen. Adsorption is negligible at -78{sup o}C and desorption is quantitative and rapid at room temperature. The possibility of an isotope effect was investigated by adsorbing measured volumes of tritium (5 {mu}c/mole) at an equilibrium pressure of about 5 mm, pumping off the system for times up to 15 min and measuring the volume of residual hydrogen. The latter was converted quantitatively to water, thence to butane, and gas-counted. The specific activity was always higher than that of tritium which had undergone 10 cycles of adsorption and desorption without intermediate pumping off, so that there was no net loss of gas. This had the same specific activity as untreated tritium from the storage  More>>
Authors:
Duncombe, W G [1] 
  1. Wellcome Research Laboratories, Beckenham, Kent (United Kingdom)
Publication Date:
Mar 15, 1962
Product Type:
Conference
Resource Relation:
Conference: Conference on the Use of Radioisotopes in the Physical Sciences and Industry, Copenhagen (Denmark), 6-17 Sep 1960; Other Information: 2 figs, 5 refs; Related Information: In: Radioisotopes in the Physical Sciences and Industry. Proceedings of the Conference on the Use of Radioisotopes in the Physical Sciences and Industry. V. III| 652 p.
Subject:
07 ISOTOPES AND RADIATION SOURCES; ADSORPTION; BUTANE; CHARCOAL; DESORPTION; HYDROGEN; ISOTOPE EFFECTS; MOLECULAR SIEVES; TRITIUM; VACUUM SYSTEMS
OSTI ID:
22025739
Research Organizations:
International Atomic Energy Agency, Vienna (Austria); United Nations Educational, Scientific and Cultural Organization, Paris (France)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA12N1755113032
Submitting Site:
INIS
Size:
page(s) 379-385
Announcement Date:
Jan 16, 2013

Conference:

Citation Formats

Duncombe, W G. The adsorption of hydrogen on a molecular sieve at -196{sup o}C and the observation of an isotope effect; Adsorption d'hydrogene sur un tamis moleculaire a -196{sup o}C et observation d'un effet isotopique; Absorbtsiya vodoroda na molekulyarnom fil'tre pri -196{sup o} i nablyudenie rezul'tatov dejstviya izotopov; Adsorcion de hidrogeno en un tamiz molecular a -196{sup o}C y observacion de un efecto isotopico. IAEA: N. p., 1962. Web.
Duncombe, W G. The adsorption of hydrogen on a molecular sieve at -196{sup o}C and the observation of an isotope effect; Adsorption d'hydrogene sur un tamis moleculaire a -196{sup o}C et observation d'un effet isotopique; Absorbtsiya vodoroda na molekulyarnom fil'tre pri -196{sup o} i nablyudenie rezul'tatov dejstviya izotopov; Adsorcion de hidrogeno en un tamiz molecular a -196{sup o}C y observacion de un efecto isotopico. IAEA.
Duncombe, W G. 1962. "The adsorption of hydrogen on a molecular sieve at -196{sup o}C and the observation of an isotope effect; Adsorption d'hydrogene sur un tamis moleculaire a -196{sup o}C et observation d'un effet isotopique; Absorbtsiya vodoroda na molekulyarnom fil'tre pri -196{sup o} i nablyudenie rezul'tatov dejstviya izotopov; Adsorcion de hidrogeno en un tamiz molecular a -196{sup o}C y observacion de un efecto isotopico." IAEA.
@misc{etde_22025739,
title = {The adsorption of hydrogen on a molecular sieve at -196{sup o}C and the observation of an isotope effect; Adsorption d'hydrogene sur un tamis moleculaire a -196{sup o}C et observation d'un effet isotopique; Absorbtsiya vodoroda na molekulyarnom fil'tre pri -196{sup o} i nablyudenie rezul'tatov dejstviya izotopov; Adsorcion de hidrogeno en un tamiz molecular a -196{sup o}C y observacion de un efecto isotopico}
author = {Duncombe, W G}
abstractNote = {Linde Molecular Sieve 4A has been examined as a possible means of handling small volumes of hydrogen isotopes in a vacuum system, as an alternative to the slow Toepler pump method. The equilibrium pressure (P) was measured for various volumes (V) of hydrogen adsorbed by 1 g of Sieve at -196{sup o}C. Experiments with activated charcoal showed the superiority of the Sieve as a hydrogen adsorbent. 1 g of the Sieve in a system of vol. 500 ml will adsorb about 97% of a 1-ml sample of hydrogen. Adsorption is negligible at -78{sup o}C and desorption is quantitative and rapid at room temperature. The possibility of an isotope effect was investigated by adsorbing measured volumes of tritium (5 {mu}c/mole) at an equilibrium pressure of about 5 mm, pumping off the system for times up to 15 min and measuring the volume of residual hydrogen. The latter was converted quantitatively to water, thence to butane, and gas-counted. The specific activity was always higher than that of tritium which had undergone 10 cycles of adsorption and desorption without intermediate pumping off, so that there was no net loss of gas. This had the same specific activity as untreated tritium from the storage bulb. It was found that log (residual vol./ initial vol.) was proportional to 1/log (residual sp. act./ initial sp. act.) over the range investigated (0-90% of initial gas pumped off). When 90% had been removed the specific activity ratio was about 3. Isotopic fractionation during adsorption is possible, but in these experiments about 99% of the initial hydrogen was adsorbed on the Molecular Sieve before desorption by pumping off was begun. It seems likely, therefore, that the considerable fractionation observed occurs mainly during desorption. The effect is thus not likely to be important when the Sieve is used for manipulating small volumes of hydrogen isotopes, since complete desorption by warming will usually be employed. (author) [French] L'auteur a examine la possibilite d'utiliser le tamis a molecules Linde 4A au lieu de la methode de pompage Toepler, qui est assez lente, pour manipuler sous vide de petites quantites d'isotopes de l'hydrogene. La pression d'equilibre (P) a ete mesuree pour differents volumes (V) d'hydrogene adsorbe par un gramme du tamis a -196{sup o}. Les experiences faites avec du charbon de bois active ont montre la superiorite du tamis comme adsorbant d'hydrogene. Un gramme du tamis, dans im systeme de 500 ml, adsorbera environ 97 % d'un echantillon d'un millilitre d'hydrogene. L'adsorption est negligeable a -78{sup o} et la desorption est totale et rapide a la temperature ambiente. On a etudie la possibilite d'un effet isotopique en adsorbant des volumes determines de tritium (5 {mu}c/mole) a une pression d'equilibre d'environ 5 mm, en vidant le systeme par pompages allant juspqu'a 15 minutes et en mesurant le volume de l'hydrogene residuel. Ce dernier a ete converti en eau, ensuite en butane, et compte sous forme de gaz. L'activite specifique etait toujours plus elevee que celle du tritium ayant subi 10 cycles d'absorption et de desorption sans pompage intermediaire, de sorte qu'il n'y avait pas de perte nette de gaz. Cette activite specifique etait la meme que celle du tritium non traite provenant de l'ampoule de stockage. On a constate que log (volume residuel/volume initial) etait proportionnel a 1/log (activite specifique residuelle/activite specifique initiale) a tous les stades consideres (evacuation de 0 a 90% du gaz initial). Apres evacuation de 90% du gaz, le rapport des activites specifiques etait de 3 environ. Il est possible qu'il y ait fractionnement isotopique pendant l'adsorption mais, dans ces experiences, environ 99% de l'hydrogene initial etait adsorbe sur le tamis moleculaire avant le commencement de la desorption par pompage. Il semble donc vraisemblable que le fractionnement important observe se produit surtout pendant la desorption. Cet effet isotopique ne saurait par consequent etre important lorsque le tamis est utilise pour manipuler de petites quantites d'isotopes de l'hydrogene, etant donne qu'on procedera generalement a une desorption complete par chauffage. (author) [Spanish] El autor ha estudiado la posibilidad de utilizar un tamiz molecular Linde 4A como medio para manejar pequenos volumenes de isotopos del hidrogeno en un sistema de vacio, en sustitucion del lento metodo de la bomba de Toepler. Midio la presion de equilibrio (P) para varios volumenes (V) de hidrogeno adsorbido por un gramo de tamiz a -196{sup o} C. Los experimentos realizados con carbono activado demuestran la superioridad de tamiz como adsorbente de hidrogeno. En un sistema de 500 ml de volumen un gramo de tamiz adsorbe alrededor del 97 % de una muestra de hidrogeno de 1 ml. A -78{sup o} C la adsorcion es despreciable y a temperatura ambiente la desorcion es cuantitativa y rapida. El autor investigo la posibilidad de que se produzca un efecto isotopico adsorbiendo volumenes medidos de tritio (5 {mu}c/mol) a una presion de equilibrio de unos 5 mm, evacuando el sistema durante periodos de hasta 15 minutos, y midiendo el volumen de hidrogeno residual. Este ultimo se convirtio cuantitativamente en agua y despues en butano, cuya actividad se determino por recuento. La actividad especifica fue siempre superior a la del tritio que habia sufrido diez ciclos de adsorcion y desorcion sin bombeo intermedio, de forma que no hubiera perdida neta de gas. Este ultimo poseia la misma actividad especifica que el tritio no tratado procedente de la ampolla de almacenamiento. Se comprobo que el log (volumen residual/volumen inicial) era proporcional a 1/log (actividad especifica residual/actividad especifica inicial) en todo el intervalo estudiado (se extrajo por bombeo de 0 a 90 % de gas inicial). Despues de eliminar el 90 por ciento del gas, la razon de actividades especificas era del orden de 3. Es posible que se produzca un fraccionamiento isotopico durante la adsorcion, pero en estos experimentos se adsorbio en el tamiz molecular cerca del 99 % del hidrogeno inicial antes de comenzar la desorcion por bombeo. Por lo tanto, parece probable que el considerable fraccionamiento observado tenga lugar principalmente durante la desorcion y que el efecto carezca de importancia cuando el tamiz se emplea para manipular pequenos volumenes de isotopos del hidrogeno ya que, por lo general, la desorcion total se efectuara por calentamiento. (author) [Russian] Ispytyvalsya molekulyarnyj fil'tr Linde 4 A v kachestve vozmozhnogo sredstva obrashcheniya s nebol'shimi ob{sup e}mami izotopov vodoroda v vakuume, vmesto primenyayushchegosya v nastoyashchee vremya nasosa Toiplera. Davlenie ravnovesiya (P) izmeryaetsya razlichnymi ob{sup e}mami (V) vodoroda, absorbiruemogo odnim grammom fil'tra pri temperature -196{sup o}. EHksperimenty s aktivirovannym drevesnym uglem pokazyvayut preimushchestvo fil'tra kak absorbenta vodoroda. Odin gramm fil'tra v sisteme s ob{sup e}mom v 500 ml absorbiruet okolo 97 % odnogo ml obraztsa vodoroda. Absorbtsiya neznachitel'na pri temperature -78{sup o}, i desorbtsiya yavlyaetsya kolichestvennoj i b'kpro protekaet pri komnatnoj temperature. Vozmozhnost' rezul'tatov dejstviya izotopa izuchalas' putem absorbirovaniya izmeryaemykh ob{sup e}mov tritiya (5 millikyuri/mol') pri ravnomernom davlenii okolo 5 mm, pri ehtom proiskhodilo vykachivanie sistemy v periode do 15 minut i izmerenie ob{sup e}ma ostatochnogo vodoroda. Poslednij prevrashchalsya kolichestvenno v vodu, zatem v butan i gaz. Udel'naya aktivnost' byla vsegda vyshe, chem aktivnost' tritiya, kotoryj prokhodil 10 tsiklov absorbtsii i desorbtsii bez promezhutochnogo vykachivaniya s tem, chtoby ne bylo nikakikh chistykh poter' gaza. EHto imelo takuyu zhe udel'nuyu aktivnost', kak u neobrabotannogo tritiya, vzyatogo iz rezervnoj kolby. Bylo obnaruzheno, chto logarifm (ostatochnyj ob{sup e}m/nachal'nyj ob{sup e}m) proportsionalen 1/logarifm (ostatochnaya udel'naya aktivnost'/ nachal'naya udel'naya aktivnost') v issleduemom poryadke (0-90% pervonachal'nogo vykachennogo gaza). Kogda 90 % gaza vykachano, koehffitsient udel'noj aktivnosti okazalsya priblizitel'no ravnym 3. Izotopnoe fraktsionirovanie v protsesse absorbtsii vozmozhno, no pri ehtikh ehksperimentakh okolo 99% nachal'nogo ob{sup e}ma vodoroda absorbiruetsya na molekulyarnom fil'tre, prezhde chem nachnetsya desorbtsiya pri vykachivanii. Poehtomu predstavlyaetsya veroyatnym, chto nablyudaemaya znachitel'naya fraktsionnost' vstrechaetsya, glavnym obrazom, pri desorbtsii. Takim obrazom, maloveroyatno, chtoby rezul'tat imel bol'shoe znachenie v sluchae primeneniya molekulyarnogo fil'tra pri manipulyatsii s nebol'shimi ob{sup e}mami izotopa vodoroda, poskol'ku obychno budet primenyat'sya polnaya desorbtsiya pri podogreve. (author)}
place = {IAEA}
year = {1962}
month = {Mar}
}