A kind of multi-step acid analysis reclaims the method for 5-chlorosalicylic acid in the mother liquor waste water that produces 5-chlorosalicylic acid

Abstract

The invention discloses a method for recovering 5-chlorosalicylic acid from 5-chlorosalicylic acid production mother solution wastewater through multi-step acid precipitation, belonging to the technical field of chemical wastewater treatment. The method comprises the recovery steps: (1) mixing a mother solution of 5-chlorosalicylic acid, pumping the mother solution into an acidizing stirred tank I, dropwise adding concentrated hydrochloric acid or concentrated sulfuric acid, and uniformly stirring to obtain an acidizing liquid A; (2) centrifuging the acidizing liquid A to obtain a clear centrifugal liquid B and a granular centrifugal sediment; (3) dropwise adding concentrated hydrochloric acid or concentrated sulfuric acid into the clear centrifugal liquid B, and uniformly stirring to obtain an acidizing liquid C; (4) centrifuging the acidizing liquid C to obtain a clear centrifugal liquid D and a granular centrifugal sediment; and (5) sequentially repeating the acid precipitation operation in the step (3) and the centrifuging operation in the step (4) until the end of the recovery operation. The method is used for realizing the effective recovery of the 5-chlorosalicylic acid, also greatly reducing the COD (Chemical Oxygen Demand) in the mother solution wastewater and reducing the wastewater treatment difficulty and is strong in practicability.

Description

technical field [0001] The invention relates to the technical field of chemical wastewater treatment, more specifically, relates to a multi-step acid analysis method for recovering 5-chlorosalicylic acid in mother liquor wastewater produced from 5-chlorosalicylic acid. Background technique [0002] With the acceleration of urbanization and industrialization in my country, the ever-growing urban population has an increasing demand for chemical products, leading to an increase in the production scale and quantity of various chemical companies. The chemical sewage discharged by chemical enterprises in the production process has caused serious pollution to the urban water environment and its surrounding ecological environment. The difficulty of chemical wastewater treatment poses a severe challenge to environmental workers. During the "Twelfth Five-Year Plan" period, my country once again proposed the policy of chemical enterprises to upgrade their production processes and elimi...

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Problems solved by technology

[0004] In the prior art, the mother liquor waste water of producing 5-chlorosalicylic acid is usually processed by the complex extraction method, using EPT-1 as the complexing agent, kerosene as the diluent, and reclaiming the extractant with sodium hydroxide. This method section is loaded down with trivial details, to The actual operation requirements of workers are relatively high, and the treatment cost is also high; more importantly, this method cannot recycle 5-chlorosalicylic acid in the mother liquor wastewater, and its purpose is only to remove COD in the wastewater, failing to achieve clean production the goal of

[0005] After searching, the Chinese patent application number 201310168591.9, the application date is May 9, 2013, the name of the invention is: a method for recycling waste liquid from the production of 2-hydroxybenzoic acid-2-ethylhexyl ester, the application is open A method for recycling salicylic acid was developed. The wastewater produced in the esterification synthesis process was adjusted to a pH value of 2 with hydrochloric acid with a mass concentration of 30%, and the wastewater was fully stirred for half an hour. White crystals were precipitated in the wastewater, which were centrifuged and dehydrated to obtain salicylic acid. Acid crystals, the obtained salicylic acid crystals can be used as raw materials for the production of 2-hydroxybenzoic acid-2-ethylhexyl, this application reduces the consumption of salicylic acid raw materials, saves production costs, and reduces sewage treatment costs , but the application still needs to be strengthened in the recovery effect of salicylic acid

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