Method for treating wastewater from preparation of glycine by chloroacetic acid ammonolysis process

Abstract

The invention discloses a method for treating wastewater from the preparation of glycine by the chloroacetic acid ammonolysis process, comprising the following steps: throwing waste liquid into a multi-effect falling film vacuum evaporation system, preheating the waste liquid in the multi-effect falling film vacuum evaporation system, heating and evaporating the waste liquid with a multi-effect falling film evaporator, putting the waste liquid in a flashing pot, concentrating the waste liquid until achieving the ammonium chloride concentration of 35-45%, crystallizing the concentrated solution with a crystallizer at normal temperature, drying and packaging the crystalline solid, adjusting the pH value of condensate which is generated by the multi-effect falling film vacuum evaporation system to 10-11 with NaOH, stripping the condensate in a stripping tower, absorbing methanol and ammonia which are generated from stripping with water, adjusting the pH value of primary stripping solution to 2-4 with dilute sulfuric acid, catalyzing and oxidizing the primary stripping solution with Fenton reagent at 30-40 DEG C, adjusting the pH value of the catalyzed and oxidized primary stripping solution to 10-11 with dilute sulfuric acid, throwing the primary stripping solution into the stripping tower, stripping the primary stripping solution for the second time in the stripping tower, absorbing methanol and ammonia which are generated from the primary stripping solution stripping with water, and discharging secondary stripping solution.

Description

Technical field: [0001] The invention relates to a waste water treatment method for producing glycine by ammonolysis of chloroacetic acid, especially a kind of chloroacetic acid which can not only recycle the ammonium chloride contained in the waste water, but also completely achieve pollution-free discharge, save energy and reduce emission, and is beneficial to environmental protection. A waste water treatment method for preparing glycine by ammonolysis. Background technique: [0002] Glycine, also known as aminoacetic acid, is the amino acid compound with the simplest structure. It is an important raw material for the pharmaceutical industry, pesticide industry, organic synthesis and biochemical research, and is also a very important organic synthesis intermediate. At present, the ammonolysis method of chloroacetic acid is commonly used in my country to produce glycine. The basic principle is to synthesize chloroacetic acid, ammonia water or liquid ammonia in water phase o...

AI Technical Summary

Problems solved by technology

From the process of producing glycine, it can be seen that when the product glycine is obtained, ammonium chloride is a by-product, and urotropine as a catalyst cannot be recovered. In addition, after centrifugation, a small amount of glycine still enters the methanol mother liquor , these ammonium chloride, glycine, urotropine are all present in the rectification raffinate (waste liquid), and the concentration of ammonium chloride alone can reach 20% to 28%, which does not meet the emission standards, and the waste liquid must be treated

[0003] Although many waste water treatment methods for the preparation of glycine by ammonolysis of chloroacetic acid have been disclosed, there are to varying degrees the huge energy consumption of ammonium chloride recovery, strong corrosion to equipment, and the evaporative condensed water with high ammonia nitrogen content. Unable to meet the discharge standards, causing secondary pollution and other problems

Images