Chemical exchange reactions for the concentration of nitrogen and oxygen isotopes^*

Chemistry Department, Columbia University, New York, N.Y., U.S.A., U.S.A..

Abstract

The exchange reactions of NO with IOM HNO₃ (α = 1,055) and NO with N₂O₃ (α= 1,031) have been used to prepare 09,7% nitrogen 15. The rapid exchange rate of NO with N₂O₃ resulted a short plate height (H.E.T.P. = 1,15 cm) so that the separation was achieved in a cascade of two columns with a total length of only 5,5 meters. In the exchange of NO with solutions of nitric acid, oxygen 18 concentrates in the gas phase (α = 1,02). A reflux system has been devised for this system and short columns have been successfully operated. An integrated system will result in the concentration of nitrogen 15 at one end and oxygen 18 at the other.

Experiments with a number of other exchange reactions for the concentration of oxygen 18 or nitrogen 15 are described. These include CO₂ with water; CO₂ with amine carbamates; and NO with CuCl₂ in methanol. The characteristics of the systems which could be refluxed thermally (exchange-distillation) are of particular interest because of the relative simplicy of their operation and control.