Environmentally-friendly clean production method of iminodiacetic acid

Abstract

The invention discloses an environmentally-friendly clean production method of iminodiacetic acid. According to the method, the iminodiacetic acid product is prepared from iminodiacetonitrile serving as the starting raw material through the steps of performing sulfuric acid hydrolysis, performing ammonia or ammonia water neutralization, decoloring, recrystallizing and the like; ammonium sulfate is separated out by decoloring, concentrating and crystallizing mother liquid; and condensate water and the mother liquid are recycled and applied to the next time of sulfuric acid dilution. By adopting the method, a large amount of sodium sulfate generated by alkaline hydrolysis is avoided, and corrosion to equipment and pollution to operation environment caused by hydrochloric acid hydrolysis are avoided; the reaction mother liquid can be completely reused and the iminodiacetic acid which the mother liquid contains can be completely recycled, so the yield is increased, water consumption is greatly reduced, no emission of waste liquid is realized, and the method is a completely environmentally-friendly clean process; and in addition, after the iminodiacetic acid and the mother liquid are decolored by active carbon, accumulation of colored impurities is greatly reduced and the product quality is high.

Description

technical field [0001] The invention relates to the technical field of synthesis of iminodiacetic acid, in particular to a method for producing iminodiacetic acid using iminodiacetonitrile as a raw material. Background technique [0002] Iminodiacetic acid (IDA for short) is also known as bisglycine and aminodiacetic acid, and its molecular formula is NH(CH2COOH) 2 . Iminodiacetic acid is an important raw material and intermediate for pesticides, pharmaceuticals, rubber, surfactants, complexing agents, food additives, electroplating industry, synthetic metal surface treatment agents and ion exchange resins. [0003] There are three main methods for domestic industrial production of iminodiacetic acid, hydrocyanic acid method, chloroacetic acid method, and diethanolamine method. The chloroacetic acid method is mature, but it has a long process, low product purity, high cost, serious "three wastes", and can only produce water preparations, which tends to be eliminated. The...

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Problems solved by technology

The chloroacetic acid method is mature, but the process is long, the product purity is low, the cost is high, the "three wastes" are serious, and only water preparations can be produced, which tends to be eliminated

The diethanolamine method is a one-step new technology of diethanolamine developed in foreign countries in the 1990s. Our country has also carried out the development of this route and achieved success. Now it is actively promoting this technology. This method has a wide range of raw materials, short process flow, few by-products, The product has high purity and has strong industrial implementation value; another advantage of this method is that the sodium salt of iminodiacetic acid can be directly used to synthesize glyphosate without acidification process, which not only reduces the loss of iminodiacetic acid, but also Avoiding the waste water produced in the acidification process simplifies the process and is very beneficial to the synthesis of glyphosate with high content; however, the raw material price of iminodiacetic acid salt produced by this method is high, and the technical content is not high, and the profit margin is not large

But because there is no purification and decolorization treatment, the iminodiacetic acid obtained is dark brown, which affects the quality of the product, and the ammonium sulfate obtained is also dark brown, which affects the quality of the ammonium sulfate product

The circulating mother liquor is only recycled until the hydrolysis reaction is completed, resulting in too much mother liquor, and the mother liquor distills too much water when ammonium sulfate is separated, which increases the production cost

The circulating mother liquor is black, which affects the recycling of the mother liquor

[0006] No matter the above methods are hydrocyanic acid method, chloroacetic acid method or diethanolamine method, they are all faced with hydrolysis with sodium hydroxide at present. In order to obtain iminodiacetic acid, acidification must be carried out, resulting in a large amount of low-value sodium salts, resulting in inferior product quality. Partial loss of aminodiacetic acid and generation of large amounts of saline wastewater

Although there is a patent report about the acid hydrolysis of iminodiacetonitrile, there are many defects in the purification of iminodiacetic acid and the recycling process of mother liquor

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