Continuous Isotope Separation in Systems with Solid Phase. II. Separation of Nitrogen Isotopes with Use of Ion-Exchange Resin

Abstract

Abstract This work deals with the separation of nitrogen isotopes by chemical exchange between ammonia in an aqueous solution and a cation-exchange resin in the NH± 4 form. Using this system, a continuous process in a simulated moving bed (SMB) is developed. Two operations, the column under total reflux and a continuous feed operation, have been studied. In the latter, the product enriched in heavy nitrogen 15N was removed from the unit. The operating conditions (2.1–30.5 cm/s superficial liquid velocity, 0.7 mm average resin granules size, and 0.98 N solution of a displacement agent) were close to those used in industrial applications. By studying the separation of nitrogen isotopes, it was shown that displacement ion-exchange chromatography in a practically standard liquid-phase SMB unit provides the opportunity for the flexible production of a number of isotopes of light elements. We found that flow converting is robust, and the operation and control are simple. It appears that the process design propo...