Recovery method and device for formic acid solvent during metronidazole production

Abstract

The invention discloses a recovery method and device for a formic acid solvent during metronidazole production, which solves the problems that in the prior art, the cost of waste water recovery is large, the environment is polluted due to the direct emission of the waste water, and the like, and is characterized in that the recovery device formed by an evaporator (1), a storage kettle (7), a water absorption tower (8), filling materials (9 and 19), a high position feeding tank(10), a condenser (12), a storage tank (16), a perforated pipe (17), a screw (18) and the like performs recovery treatment on industrial waste water; the particular technological processes are as follows: the hydroxylation solution is evaporated through adopting the evaporator so as to obtain dilute formic acid vapor with the mass concentration of 30-70%; the formic acid vapor firstly passes through the cold material filling layer at the upper part of the evaporator to remove entrainment substances, such as metronidazole, of the formic acid vapor; part of water in the formic acid vapor is removed through the water absorption tower of the material filling layer with sticky polyphosphoric acid and high concentration phosphoric acid both flowing downwards; water in the formic acid vapor is further removed through a pipeline with phosphorus pentoxide; the concentrated formic acid vapor is condensed into high concentration formic acid liquid. The method and the device can be widely applied to a production enterprise for recycling a great deal of produced dilute formic acid waste water in chemical engineering production enterprises.

Description

1. Technical field [0001] The invention belongs to the recovery and treatment of production wastewater in chemical enterprises, and in particular relates to a recovery method and device for formic acid solvent in the production process of metronidazole. 2. Background technology [0002] The structural formula of metronidazole is: [0003] [0004] Metronidazole is an antimicrobial agent, especially an anaerobic agent. It has been used by the World Health Organization (WHO) as the drug of choice for anti-anaerobic bacteria. The method for synthesizing metronidazole that has been reported so far is: dissolving 2-methyl-5-nitroimidazole in formic acid, adding ethylene oxide gradually at 30-40° C., and adding sulfuric acid during the addition. After addition, react for 1h to obtain hydroxylated solution. After the hydroxylation solution is cooled to 10°C, adjust the pH to 10 with sodium hydroxide solution, leave to cool, crystallize, and filter to obtain metronidazole. ...

AI Technical Summary

Problems solved by technology

However, the reaction between phosphorus pentoxide and dilute formic acid solution is too fast, a large amount of heat is released, and high temperature is generated to decompose formic acid and carbonize impurities, which affects the recovery rate of formic acid and the quality of phosphoric acid.

Therefore, some manufacturers directly discharge the metronidazole filtrate, causing great pollution to the environment

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