Treatment of pyrazolone production wastewater - bipolar membrane electrodialysis process

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The production process of pyrazolone is to carry out the desalination reaction of water, hydrochloric acid, aniline and sodium nitrite, add sulfuric acid to the obtained reaction product for hydrolysis, pass the hydrolysis product into ammonia water for neutralization reaction, and the neutralization reaction product is obtained by condensation reaction with butanone amide to obtain pyrazolone product.

Due to the need to add a large amount of ammonia water for neutralization in the production process of pyrazoldone, the ammonia water was not finally introduced into the pyrazoldone products, but all dissolved in the pyrazoldone production wastewater. Therefore, the pyrazoldone wastewater has the characteristics of high salt, high ammonia nitrogen, high COD, and contains biologically toxic components, such as aniline, phenylhydrazine, etc., making its treatment difficult. At present, pyrazolone wastewater is generally treated by distillation, evaporation, Fenton advanced oxidation, biochemistry and other combined processes. However, the purity of recovered ammonium sulfate is low, it is difficult to use, the price of ammonium sulfate is low, and the comprehensive treatment cost is high, which causes great economic burden to enterprises.

Ammonium sulfate in pyrazolone wastewater can be separated into sulfuric acid and ammonia water by bipolar membrane electrodialysis process, which can be used for production or export. After ammonium sulfate separation, the main pollutant components in wastewater are pyrazolone (with low salt content), eliminating the investment in evaporation equipment and realizing an efficient and energy-saving wastewater treatment process.

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