NITRIC ACID CONCENTRATION SYSTEM

Nitric Acid Concentration

Concentrated Nitric Acid is an important chemical for Chemical & Pharmaceutical industries in general (like polymers & plastics, dyestuff, bulk drugs, explosives, Fertilizers and other important organic nitro-compounds). This acid is frequently used as "nitrating acid".

Industrially manufactured Nitric acid is obtained as a weak acid solution, at a concentration of about 65% -67% w/w (max.), which is of no use whatsoever for the various processes stated above,

Owing to the physical behaviour of the nrtric acid / water system, it is not possible to remove excess water from this weak acid by a fractional distillation process because this solution forms an azeotrope, a constant acid / water boiling composition at about 68% w/w. acid.
To concentrate this acid further an extractive distillation process by adding concentrated sulphuric acid needs to be employed. While the water goes this sulphuric acid gets diluted, which can be again re-concentrated and reused for the concentration of dilute nitric acid again.