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Method for reducing COD (Chemical Oxygen Demand) and total salt in wastewater in azo pigment preparation

An azo pigment and wastewater technology, applied in azo dyes, monoazo dyes, chemical instruments and methods, etc., can solve the problems of secondary pollution, unrecoverable catalysts, selective oxidation, etc., and achieve good brightness. Effect

Pending Publication Date: 2022-05-13
江西隆源化工股份有限公司
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Problems solved by technology

[0002] In the preparation process of the azo pigments in the prior art, the diazotization reaction solution and the coupling reaction solution are first prepared, and then the diazotization reaction solution and the coupling reaction solution are mixed and reacted under strong acidic conditions to form an azo pigment. During the reaction process, it is necessary to continuously strengthen the acid to maintain a low pH value of the reaction solution. After the complete reaction, use a strong alkali solution to make the reaction solution neutral. After suction filtration, washing and drying, the finished organic pigment and azo Pigment preparation waste liquid, the azo pigment preparation waste liquid obtained by this traditional method has high COD and total salt inside, and the current methods of treating these waste water are mainly divided into physical methods and chemical methods, traditional physical methods such as adsorption The method, membrane separation method, etc. only transfer pollutants from one medium to another medium, and do not fundamentally degrade organic matter, and sometimes improper treatment will cause secondary pollution, while the cost of chemical oxidation treatment is too high. Moreover, the catalyst cannot be recovered, and the commonly used oxidizing agents have disadvantages such as weak oxidation ability and selective oxidation. During the treatment process, impurities are easily introduced to cause secondary pollution. However, there are few solutions on the market to solve this problem at the source. The method of reducing COD and total salt in wastewater during the preparation of azo pigments solves the above-mentioned technical problems of high COD and total salt in wastewater

Method used

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  • Method for reducing COD (Chemical Oxygen Demand) and total salt in wastewater in azo pigment preparation
  • Method for reducing COD (Chemical Oxygen Demand) and total salt in wastewater in azo pigment preparation
  • Method for reducing COD (Chemical Oxygen Demand) and total salt in wastewater in azo pigment preparation

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Embodiment 1

[0024] The present invention provides an embodiment: a method for reducing wastewater COD and total salt during the preparation of azo pigments, the preparation steps of which are as follows:

[0025] Step 1, diazotization: Add 12kg of industrial water to a 30L reaction vessel with temperature control and stirring functions, control the temperature of the industrial water to 2°C, then add 0.93kg of aniline and Stir, and when the diazotization reactant is completely dissolved, slowly add 3 kg of sodium nitrite aqueous solution with a mass concentration of 20% to the interior at 2° C., and react for 30 minutes to obtain 15.93 kg of diazotization reaction liquid;

[0026] Step 2, coupling: add 2.5kg of sodium hydroxide solution and 10kg of industrial water with a mass concentration of 10% to a reaction vessel with a volume of 30L and a temperature control and stirring function, and then add 3.07kg of color For phenol AS-VL, start stirring and heat to 60°C. After the naphthol AS-V...

Embodiment 2

[0031] The operation steps are the same as those in Example 1, except that the pH value of the buffer solution is adjusted and maintained at 4.8 in step 4, and finally 3.1 kg of organic pigments and 37.9 kg of azo pigment preparation waste liquid are obtained in step 5.

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Abstract

The invention discloses a method for reducing wastewater COD (Chemical Oxygen Demand) and total salt in azo pigment preparation, and relates to the technical field of pigment preparation. The preparation method comprises the following steps: 1, diazotization: adding industrial water into a reaction container with temperature control and stirring functions, controlling the temperature of the industrial water to be 0-5 DEG C, then adding a diazotization reactant into the reaction container, stirring, and after the diazotization reactant is completely dissolved, slowly adding a sodium nitrite aqueous solution into the reaction container at 0-5 DEG C; according to the method, the pH value of the coupling reaction in synthesis is controlled, so that more acid does not need to be added in the coupling reaction process, the content of COD (Chemical Oxygen Demand) and total salt in wastewater generated in azo pigment preparation can be effectively controlled, and meanwhile, the prepared azo pigment preparation waste liquid is still weakly acidic and can be repeatedly utilized; and by adding the polar surfactant, the surface of the prepared azo pigment still has better brightness, and the subsequent use is not influenced.

Description

technical field [0001] The invention relates to the technical field of pigment preparation, in particular to a method for reducing COD and total salt in wastewater during the preparation of azo pigments. Background technique [0002] In the preparation process of the azo pigments in the prior art, the diazotization reaction solution and the coupling reaction solution are first prepared, and then the diazotization reaction solution and the coupling reaction solution are mixed and reacted under strong acidic conditions to form an azo pigment. During the reaction process, it is necessary to continuously strengthen the acid to maintain a low pH value of the reaction solution. After the complete reaction, use a strong alkali solution to make the reaction solution neutral. After suction filtration, washing and drying, the finished organic pigment and azo Pigment preparation waste liquid, the azo pigment preparation waste liquid obtained by this traditional method has high COD and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09B29/20C09B29/01
CPCC09B29/0003C09B29/20
Inventor 黄鹏陈权弟朱小吒余江洋傅彬何江龙杨容何文武张坤武
Owner 江西隆源化工股份有限公司
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