Preparation method of MGDA biodegradable chelating agent

Abstract

The invention discloses a preparation method of an MGDA biodegradable chelating agent, which comprises the following steps: step 1, firstly weighing chloroacetic acid and water, then slowly dropwise adding liquid caustic soda while controlling the temperature not to exceed 45 DEG C, and reacting to prepare sodium chloroacetate; 2, preparing an L-sodium alanine solution by reaction of measured deionized water, L-alanine and caustic soda liquid, adding a catalyst, and heating to 85 DEG C; 3, simultaneously adding the material in the step 1 and the prepared liquid caustic soda into the material in the step 2, controlling the dripping speed of the material and the prepared liquid caustic soda and the pH value of a reaction system, and controlling the pH value to be 9.5-10.5; 4, after dropwise adding, reacting for 1 hour, heating to 95 DEG C, continuously reacting for 3 hours, and performing cooling to room temperature after the reaction is finished, so as to directly obtain a finished product of the MGDA green chelating agent solution. The method is simple to operate, stable in process, high in product quality and good in performance, and has huge application prospects and market economic benefits.

Description

technical field [0001] The invention relates to the technical field of polymer preparation, in particular to a preparation method of MGDA biodegradable chelating agent. Background technique [0002] Chelating agents mainly include phosphates, hydroxycarboxylic acids, aminocarboxylic acids and polymers containing carboxylic acids. The chelating effect of phosphate is better, but the phosphorus content causes great pollution to the environment. Sodium tripolyphosphate (STPP) is mainly used more, but the market gradually fades in the global call for phosphorus restriction and phosphorus prohibition. Hydroxycarboxylic acids mainly include sodium gluconate, sodium citrate, etc. Generally, the chelating performance of metal ions is poor, and the cost performance is not high. Acrylic polymers belong to polymer chelating agents. In addition to their chelating ability, they also have thickening and flocculating effects. Generally, they will settle in water after chelating and are al...

AI Technical Summary

Problems solved by technology

In addition, some companies currently use chloroacetic acid to synthesize MGDA, but the acid-binding agent triethylamine or pyridine is added in the reaction process, and the amount is relatively large, which leads to the coexistence of triethylamine hydrochloride and MGDA in the later products, and these two salts It is difficult to dispose of triethylamine hydrochloride after mixing, so that its MGDA is a mixture, and its effect may be affected. In addition, it will increase the pollution to the environment

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