Volatilité du nitrate, chlorure et sulfure mercurique et préparation de sources radioactives de ²⁰³Hg

Abstract

R e p le 15 septembre 1969En utilisant le Z03Hg comme traceur, on a 6tudi6 la volatilit6 du Hg(N03)2 et HgClz en presence de HNO,, HCl, H2S, Na2S, NaHS, Na2SZ03 et NH3. Les quantitts de mercure ont variC de 1 50 pg et les autres conditions exptrimentales ont Ct C celles qu'on rencontre lors de la prkparation de sources radioactives de rCfkrence, destinCes aux mesures absolues du taux de dCsintCgration. On a trouvC que les pertes Ctaient apprCciables durant l'evaporation de solutions de Hg(N03), dans HNO,, qu'elles Ctaient nulles durant l'evaporation de solutions de HgC12 dans HCI, et qu'elles Ctaient de nouveau appreciables pour des sources solides issues de 1'Cvaporation de chacune de ces solutions. En partant d'une solution de Hg(N03), dans HNO3, on a trouv6 qu'il Ctait tres difficile d'tliminer completement les pertes d'activit6 par prkcipitation du HgS; on n'y est arrive seulement en ajoutant un grand exces d'ion sulfure sous forme de Na2S et de NaHS ou de Na2S203 en solution. La precipitation du HgS a partir d'une solution de HgC12 dans HCI est beaucoup plus facile que dans le cas prCcCdent et tlimine completement les pertes d'activitC.On peut expliquer les resultats en admettant que la formation du complexe HgC14Z-en milieu HCI stabilise I'ion mercurique et le rend non volatil, tandis que la formation de molecules volatiles de Hg(N03)Z est favoriste en milieu H N 0 3 oh it n'y a pas de formation de complexe.With 203Hg as a tracer, the volatility of Hg(N03), and HgClz in the presence of HNO,, HCI, HIS, Na,S, NaHS, NaZS2O3, and NH3 has been studied. The amounts of mercury varied between 1 and 50 pg and the other experimental conditions were those encountered in the preparation of radioactivity standards. We found that the losses of activity were large during the evaporation of solutions of Hg(NO?), in HN03, that they were nil during the evaporation of solutions of HgCI, in HCI, and that they were large again for the solid residues left after the evaporation of each one of these solutions. When using a solution of Hg(N03), in HNO3, we found it very difficult to eliminate completely the losses by a HgS precipitation; we stopped them completely only by addition of a large excess of sulfide ion as Na2S and NaHS or of Na,S203. The precipitation of HgS from a solution of HgClz in HCl is much easier and stops the losses completely.The results can be explained by saying that the formation of the HgC1,2-complex in a HCI medium greatly stabilizes the mercuric ion and renders it nonvolatile, whereas the formation of volatile Hg(N03), molecules is favored in a HNOB medium where no complex formation occurs.

Variables in the determination of mercury by cold vapor atomic absorption

“…The signal was about 20% as large as that observed in the presence of the reducing agents. These observations cannot be explained by volatility of HgCl2 as suggested by previous workers (11,12) for several reasons. Data to support these reasons are presented in Table I.…”

“…Grossoleil and Roy (11) studied the volatility of mercury using 203Hg tracer. They found that the loss was prevented by the presence of excess HC1 and attributed it to vaporization of HgCl2.…”