Description:
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The most used method for production of stable isotope 15N is based on the isotopic exchange 15N/14N in the nitrogen oxides-nitric acid solution system, known as Nitrox system. At the bottom of the packed separation column, the reflux is provided by total conversion of nitric acid into nitrogen oxides by reaction with sulfur dioxide, in a packed column type refluxer. The waste of HNO3-SO2 reaction is sulfuric acid, solution of 65-70%, which is evacuated at the bottom of the nitrogen oxides refluxer. The magnitude of the nitrogen losses, as NOx and/or HNO3 in the waste sulfuric acid, were determined by analysing the effluent sulfuric acid by spectrofotometric method with Nessler reagent.
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