METHOD FOR OBTAINING ADIPINIC ACID CONCENTRATE AND SODIUM ALKALI FROM ALKALINE WASTEWATER FROM CAPROLACTAM PRODUCTION FACILITIES Russian patent published in 2019 - IPC C25B1/16 C07C55/14 C01D1/40 B01D61/44 

FIELD: technological processes; processing and recycling of wastes.

SUBSTANCE: invention relates to the recovery of industrial waste by separation using electrolysis with an ion-exchange membrane, mainly for the production of adipic acid and alkali concentrates in caprolactam manufacturing plants. Method involves pre-mixing the wastewater with a sulfate acidifying agent to obtain an organic and aqueous phase, the acidity of which is maintained not more than 30 g/l as sulfuric acid. Organic phase is then used as an adipic acid concentrate. Aqueous phase is subjected to electrolysis in a two-chamber membrane electrolyzer to produce sodium alkali in the cathode chamber, and acid anolyte in the anodic chamber. After leaving the electrolytic cell, the acid anolyte is fed to mixing with a new portion of wastewater as an acidifying agent, completing the anolyte cycle. Acidity of the resulting aqueous phase is maintained not lower than 10 g/l. Water and salt balance of the anolyte cycle is supported by partial evaporation of the aqueous phase, which is carried out before it is supplied to the electrolyzer with the release of sodium sulfate or after leaving the anode chamber of the electrolyzer with the release of sodium bisulfate.

EFFECT: efficiency is enhanced by reducing production waste while improving the environment in the production area.

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