Recovery method of benzene series nitration waste acid

The invention provides a recovery method of benzene series nitration waste acid. The recovery method includes: mixing waste acid from a benzene series nitration reaction process with activated carbon for decolorizing, adding decolorized waste acid and solid potassium nitrate into an intermittent reactive distillation column bottom sequentially, heating to 60-70 DEG C with stirring for 0.5-3 hours, performing rectification operation while reaction is conducted, collecting overhead distillate, namely recovery liquid, adding water into the intermittent reactive distillation column bottom, heating with stirring to dissolve residues in the bottom, regulating a pH value of 1.4-2.1 by a potassium hydroxide water solution, filtering immediately, naturally cooling filtrate to separate out solids, filtering to obtain potassium bisulfate and recycling mother liquor. The recovery method of the benzene series nitration waste acid has the advantages that the waste acid is utilized effectively to obtain nitric acid required by the reaction and the high-added-value potassium bisulfate, so that the whole technological process is more environment friendly.