Vapour-liquid equilibria of nitric acid-water-sulphuric acid mixtures

New vapour–liquid equilibrium data have been obtained for the systems nitric acid–water and nitric acid–sulphuric acid–water and have been applied to the design of a column for the concentration of nitric acid by extractive distillation with sulphuric acid. The new data require an increase in the number of theoretical plates, and thus explain in part the present use of larger quantities of sulphuric acid than should be necessary in a column designed according to previously published data.