Nitrogen Isotope Separation by Means of Cation Exchange Resin, ( I ). Effects of Eluent Concentration.

Abstract

In order to develop a feasible process for production of enriched 16N, nitrogen isotope separation by ion exchange has been studied. The attention has been placed on the concentration of the eluent LiOH solution introduced into the ion exchange column, packed with specially synthesized cation exchange resin. The ammonium ion adsorption band initially charged in the resin bed was eluted in a reverse breakthrough manner. The separation coefficients E have been confirmed not to be seriously affected by the eluent concentration. However a tendency of slight decrease in 5 has appeared in the high concentration region. The values of HETPs of the process have been also shown almost constant, in spite of the large difference in the migration velocity depending on the eluent concentration. The results suggest that the ion exchange rates are very fast a t high concentrations of the eluent, probably due to the large mobility of neutral ammonia in the resin.KEY WORDS: nitrogen isotope. nitrogen 15, isotope effects, isotope separation, ion exchange, cation exchange resin, chromatography, mass spectrometry, isotope ratio, HETP

Nitrogen Isotope Separation Using Porous Microreticular Cation-Exchange Resin

“…Any further chemical reactions and isotopic-exchange reactions taking place in the ammonium adsorption band were described in a previous paper (6).…”

“…5 that the HETPs obtained at a longer migration distance are almost constant (0.49 mm) for migrations up to 60 m. We have surveyed previously reported 15 N ion-exchange enrichment systems, and the HETPs reported by Spedding (3), Park (4), and Kruglov (5), and the calculated HETP based on the data in the work of Urgell (8) are summarized in Table 1 along with the HETPs obtained in the present work and in our previous work (6). Spedding (3), Park (4), and Urgell (8) used gel-type resins; Kruglov (5) used a macroreticular resin; and a highly crosslinked, highly porous microreticular resin was used in our previous work (6). The eluent concentrations were 0.12 and 0.6 M in the experiments by Spedding (3); 0.3 and 0.6 M by Park (4); 0.6 M by Urgell (8); 0.98 M by Kruglov (5); and 0.11, 0.22, 0.53, and 1.14 M in our previous work (6).…”

“…Spedding (3), Park (4), and Urgell (8) used gel-type resins; Kruglov (5) used a macroreticular resin; and a highly crosslinked, highly porous microreticular resin was used in our previous work (6). The eluent concentrations were 0.12 and 0.6 M in the experiments by Spedding (3); 0.3 and 0.6 M by Park (4); 0.6 M by Urgell (8); 0.98 M by Kruglov (5); and 0.11, 0.22, 0.53, and 1.14 M in our previous work (6).…”

“…It appears suitable to again consider the feasibility of I5 N enrichment by using porous microreticular ion-exchange resins. In previous work (6), I5 N isotope separation using porous microreticular cation-exchange resin of small particle diameter (200-400 mesh) was experimentally studied, and the influence of the eluent concentration on the separation factor and the HETP at a nonsteady state were investigated. HETPs of the process are almost constant in spite of the large difference in the migration velocity according to concentration of the eluent.…”

Nitrogen Isotope Separation with Displacement Chromatography Using Cryptand Polymer

“…2) Recently a good performance has been demonstrated for a chromatographic enrichment of 15 N using an ion exchange resin. 3) In the current paper, we studied an applicability of a resin made of cryptand polymer to the chromatographic enrichment of 15 N. Cryptands are macrobicyclic polydentate ligands that Lehn has termed, 4) e.g. R-CH 2 O-C 6 H 3 -N 2 O 5 .…”