System for producing DSD acid with membrane method

Abstract

The invention discloses a system for producing DSD acid with a membrane method. The system comprises an oxidizing bath, a nano-filtration unit, a salting-out bath and a reduction bath, wherein the oxidation bath, the nano-filtration unit, the salting-out bath and the reduction bath are sequentially arranged. A liquor inlet and a concentrated liquor outlet of the nano-filtration unit are connected with an outlet of the oxidation bath and the inlet end of the salting-out bath respectively, and the outlet end of the salting-out bath is connected with an inlet of the reduction bath. Oxidation liquor is subjected to nano-filtration through the nano-filtration unit, water, unreacted NaOH and part of NTS in the oxidation liquor jointly flow through a membrane unit of the nano-filtration unit, and DNS generated through a reaction in the oxidation liquor is intercepted in nano-filtration membrane concentrated liquor of the nano-filtration unit and enters the salting-out bath; in this way, the volume of the oxidation liquor entering the salting-out bath after being subjected to nano-filtration is greatly reduced, the unreacted NaOH in the oxidation liquor can be filtered out, acid liquor which is added into the salting-out bath and used for neutralizing the liquid and sodium sulfate added into the salting-out bath and used for carrying out salting-out treatment can be effectively reduced accordingly, the cost of production raw materials is reduced, and subsequently-generated waste sodium sulfate dregs are greatly reduced.

Description

technical field [0001] The invention relates to the technical field of chemical industry, in particular to a system for producing DSD acid by a membrane method. Background technique [0002] DSD acid (4,4'-diaminostilbene-2,2'-disulfonic acid) is an important chemical dye intermediate, and hundreds of varieties of stilbenes can be synthesized from it as the main raw material Fluorescent brighteners, direct dyes, reactive dyes, and acid dyes, etc., along with the rapid development of textile printing and dyeing, papermaking, and washing industries, have also increased the market demand for DSD acid. [0003] At present, the steps of most domestic industrialized production of DSD acid are: (1) step, use oleum to sulfonate PNT (p-nitrotoluene) to obtain PNT acid (abbreviated as NTS, Chinese name p-nitrotoluene o-sulfonic acid); In step (2), in a strong alkaline aqueous medium (commonly used NaOH solution), catalyzed by a transition metal salt, PNT acid is oxidatively condensed...

AI Technical Summary

Problems solved by technology

[0005] The technical defect of adopting the above-mentioned method to produce DSD acid is that the amount of waste water and waste residue produced are large. Specifically, every ton of DSD acid produced will produce 30-40 tons of waste water in the oxidation section of (2), and the reaction in the oxidation section is completed. After entering the step (3) reduction section, in the reduction section, add about 4.5% sulfuric acid (or waste acid) to neutralize the unreacted sodium hydroxide in the feed liquid in the feed liquid that the oxidation reaction has completed, and add 10% in addition. % sodium sulfate for salting out, and then add iron powder for reduction treatment, but this will result in 5-7 tons of sodium sulfate waste residue for every 1 ton of DSD acid produced

[0006] This shows that adopting above-mentioned traditional method to prepare the waste water and the amount of waste residue produced in the DSD acid process is large, and the treatment cost is high, which undoubtedly increases the production cost of the enterprise. Therefore, how to reduce the generation amount of waste water and waste residue in the DSD acid production process, In order to improve the economic benefits of the enterprise and reduce the pollution to the environment, this is one of the important topics that relevant technical personnel are committed to researching.

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