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Treatment method of desalted water generated in MDA preparation process

A treatment method and technology of preparation process, applied in the field of brine drainage, can solve the problems of pale green brine, can not be removed cleanly, affect drainage and reuse, etc., and achieve the effects of reducing environmental pressure, stable operation and strong pertinence

Active Publication Date: 2021-01-29
WANHUA CHEM GRP +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in the actual production process, it is found that oxidation or catalytic oxidation cannot completely remove certain organic substances in the brine, and even the brine after oxidation may appear light green, which seriously affects the discharge and reuse.

Method used

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  • Treatment method of desalted water generated in MDA preparation process

Examples

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Comparison scheme
Effect test

preparation example Construction

[0035] The source of raw material used in the preparation example of the present invention, embodiment and comparative example is as follows:

[0036] Aniline: Wanhua self-produced aniline with a purity of 99.9%, reaching the industrial grade specified in GB2961-2014;

[0037] Hydrochloric acid: Wanhua self-produced hydrochloric acid with a concentration of 34%;

[0038] Unless otherwise specified, other raw materials are commercially available products.

[0039] The detection method and the instrument used in the preparation example of the present invention, the embodiment and the comparative example are as follows:

[0040] TOC measurement: Germany Jena 2100S TOC instrument, TOC / TN dual detector; the sample was adjusted to pH=2 with hydrochloric acid, and the sample was injected for analysis, and TOC was quantified with an external standard of sodium phthalate.

[0041] Bromophenol detection in brine (sum of the total content of monobromodichlorophenol, dibromomonochloroph...

preparation example M

[0047] The preparation of preparation example MDA

[0048] React hydrochloric acid (calculated as HCl) with a molar ratio of 0.3:1 and aniline to form aniline salt, and then add formaldehyde to undergo condensation reaction and transposition reaction. The molar ratio of formaldehyde to aniline is 0.35:1, and the reaction temperature is 50°C After the reaction is finished, a reaction mixture comprising diamine salts and polyamine salts of diaminodiphenyl is obtained. Adopt excessive 50%NaOH (the mol ratio of NaOH and hydrochloric acid is 1.10:1) to neutralize the reaction mixture, and the mixture after neutralization is sent into the stratifier to separate the organic phase and the water phase, and the organic phase passes through water (water and The volume ratio of the oil phase is 0.4:1) After washing once, water and aniline are preliminarily separated by 10kPa flash distillation, and then purified by 8barg steam distillation to obtain MDA.

Embodiment 1

[0050] MDA was prepared according to the preparation example, wherein the hydrogen bromide content in the raw hydrochloric acid was 84.8 mg / L.

[0051] Collect and combine the water phase and washing brine produced in the neutralization and washing process to obtain drain brine, add 34% hydrochloric acid to adjust the pH value to 5.1, and then use aniline as the extraction agent to extract (the phenol content in the aniline is 21.3mg / L) , the extraction temperature was 30°C, the mass ratio of aniline to brine was 0.2:1, and the content of MDA in the brine after extraction was 0.03mg / L, which achieved the purpose of extracting MDA. At the same time, it was detected that the content of phenol in the brine was 0.27 mg / L, the sodium bromide content is 3.74mg / L, and the aniline content is 3.9%. Next, the drained brine is subjected to 2barg steam stripping to remove aniline therein. Finally, sodium hypochlorite oxidant (the mass ratio of the amount added to the discharged brine is ...

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Abstract

The invention provides a method for treating desalted water generated in a MDA preparation process. According to the method, before catalytic oxidation treatment, a phenol content is controlled not toexceed 0.8 mg / L and / or a sodium bromide content is controlled not to exceed 0.2 mg / L. According to the treatment method provided by the invention, the impurity components of the desalted water are deeply analyzed, the phenol content and the sodium bromide content in the desalted water are effectively controlled, deep purification effect can be achieved, the TOC content and the bromophenol contentin the treated desalted water are relatively low, organic matters are thoroughly removed, and environmental pressure is reduced; and the treatment method provided by the invention is strong in pertinence, simple and convenient in process, convenient for industrial implementation and stable in operation, does not need a large amount of manpower and equipment investment, and has a very good application prospect.

Description

technical field [0001] The invention relates to the field of chemical wastewater treatment, in particular to a treatment method for the brine produced in the MDA preparation process. Background technique [0002] Diamines and polyamines of diphenylmethane are understood to mean compounds having the following structure and mixtures thereof (hereinafter referred to as MDA). [0003] [0004] where n is a natural number [0005] MDI is one of the main raw materials in the polyurethane industry. Utilizing aniline and formaldehyde to prepare MDA, and then utilizing MDA to react with phosgene to synthesize MDI is a well-known method in the industry. Methods for the preparation of MDA are generally well known in the art and are described in many published patent documents and publications, such as US-A 2009 / 0240077, EP-A-451442 and WO-A-99 / 40059 . MDA is prepared through a continuous, semi-continuous or discontinuous reaction process. Aniline is first reacted with hydrochlor...

Claims

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Application Information

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IPC IPC(8): C02F9/10C02F103/36
CPCC02F9/00C02F2103/36C02F1/725C02F1/26C02F1/10
Inventor 邢津铭李永锋陈良进章靓吴雪峰张宏科
Owner WANHUA CHEM GRP
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