Method for environment-friendly clean production of high-purity ethylene diamine tetraacetic acid (EDTA)

Abstract

A method for the environment-friendly clean production of high-purity ethylene diamine tetraacetic acid (EDTA) is an environment-friendly clean production method which takes sodium cyanide, formaldehyde and ethylenediamine or sodium hydroxide, glycolonitrile and ethylenediamine as main raw materials to synthesize the high-purity EDTA, and is characterized in that the acidization process of the synthetic EDTA solution is carried out by two steps, the purification decoloration treatment is carried out under the condition that a solution system is weak alkaline or approaches neutral, so the optimum effect of purification decoloration can be realized; the separation after the purification decoloration is carried out by two separation steps of centrifugal separation and fine filtration, so the relatively pure EDTA synthetic solution is obtained; the method is also characterized in that the mother solution which is produced by producing EDTA and is rich in sodium sulfate is subjected to comprehensive treatment for obtaining anhydrous sodium sulphate, the zero emission clean production method is realized, and is mainly realized through the technology that sodium sulfate hydrous crystalline solid is obtained through mother solution recovery treatment, and the byproduct of the anhydrous sodium sulphate is obtained through purification dehydration and other treatments of the sodium sulfate hydrous crystalline solid; and through recovering the sodium sulfate in the mother solution, not only can resources be saved, but also the environmental conservation of the EDTA production technology can be realized, and very good economic and social benefits are obtained.

Description

technical field [0001] A kind of environment-friendly and clean production method involving high-purity EDTA refers to an environment-friendly and clean production method for synthesizing high-purity EDTA as main raw materials with sodium cyanide, formaldehyde and ethylenediamine or sodium hydroxide, hydroxyacetonitrile and ethylenediamine, fully considering The recycling of the mother liquor and the environmental protection of the production process belong to the environmental protection clean production technology method. Background technique [0002] The synthesis of EDTA using sodium cyanide, formaldehyde and ethylenediamine or sodium hydroxide, hydroxyacetonitrile and ethylenediamine as main raw materials is a well-known process, especially the production of EDTA using sodium cyanide, formaldehyde and ethylenediamine as main raw materials The technical process is more familiar to people in the industry. EDTA and its sodium salt are basic chemical raw materials with a w...

AI Technical Summary

Problems solved by technology

Due to the formation of a considerable amount of ammonia and sodium sulfate in the synthesis process, the discharge of tail gas ammonia and the generation of sodium sulfate mother liquor are formed; if the tail gas ammonia and sodium sulfate mother liquor are not recycled well, serious pollution sources will be formed

In the existing production process, the recovery of tail gas ammonia can basically be solved, but the recovery and utilization of sodium sulfate mother liquor has become a recognized problem

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