Improved process for the recovery of sulphuric acid from waste acid

摘要

Sulphuric acid is recovered and purified after being used in the nitration of an organic amino compound by first distilling off water, then heating to decompose impurities, oxidizing to remove dark-coloured impurities, e.g. with nitric acid, then cooling, diluting with water and treating with absolute alcohol to give a precipitate of ammonium normal and acid sulphates which are separated, distilling off the alcohol and concentrating the residual acid by heating and evaporating.