Produção Nacional
Revisado por pares
Isotope Separation of Nitrogen by Ion Exchange Chromatography in a Cascade System
2013; Taylor & Francis; Volume: 31; Issue: 7 Linguagem: Inglês
10.1080/07366299.2013.810912
ISSN1532-2262
AutoresEveraldo Máximo, Carlos Roberto Sant Ana Filho, Paulo César Ocheuze Trivelin, José Albertino Bendassolli,
Tópico(s)Chemical Synthesis and Characterization
ResumoThe ion exchange chromatography technique in a cascade process was used to separate stable isotopes of nitrogen (14N/15N). For this purpose, three column systems (with different internal diameters, S1−14.5 cm; S2–9.5 cm; S3–5.2 cm) were used that contained the cationic resins DOWEX 50 WX8 (as H+ and equilibrated with H2O) and measured 1.7 m in height. Isotopic fractionation of nitrogen occurs during displacement band chromatography (DBC) of the NH3 (aq) solution with a 0.75 mol L−1 NaOH solution. The active sites of the resin were previously saturated to form NH4 + (RNH4) with a 0.75 mol L−1 solution of (NH4)2SO4 at a natural isotopic abundance (0.366 at. %) in 15N. The NH4 +/NH3 (aq) equilibrium was determined during the DBC, which enriched the rear portion of the band with 15N. In S1, enrichment of approximately 5 at. % of 15N in the last 10 cm was achieved. After four interactions (couplings) between S1–S2, an enrichment of approximately 50 at. % of 15N was obtained. During the interaction between S2–S3, after the second coupling, an isotopic enrichment of approximately 90 at. % of 15N was observed, which produced 70 g month−1 of (15NH4)2SO4.
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