Purificn. of waste sulphuric acid from nitration processes - by treatment esp. with urea or condensn. prods. decompose nitrous and nitric acids present

摘要

The elimination of nitrous acid and/or nitric acid from waste sulphuric acid, partic. that arising from nitration processes, involves treatment of the waste sulphuric acid with monomeric or polymeric cpds. of carbonic, formic, acetic and/or sulphuric acids contg. NH2 gps. (i.e. acid amides), and/or hydroxylamine, and/or treatment with ammonium salts. Treatment is pref. at 30-150 degrees C and 0.5-60 mn. Partic. the cpd. used to treat the waste sulphuric acid is urea or one of its condensn. prods. The cpd. can be added in an excess up to 10% above the stoichiometric amt. required.