Method for recovering and purifying terephthalic acid in alkali-minimization waste liquor

A technology for terephthalic acid and alkali reduction waste liquid, which is applied in the preparation of carboxylate, separation/purification of carboxylic acid compounds, etc. Good social and economic benefits, small equipment investment scale, and the effect of reducing COD content

Inactive Publication Date: 2011-11-09
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Anaerobic biochemical treatment mainly adopts upflow anaerobic biological sludge bed, backflow anaerobic biological filter bed, and composite anaerobic reactor. Terephthalic acid is finally anaerobic biodegraded, but the removal rate is generally only about 40%, and the start-up It takes a long time, and at the same time, this method degrades terephthalic acid to achieve environmental benefits, but fails to recycle terephthalic acid, resulting in waste of raw materials
Aerobic biochemical treatment of alkali reduction wastewater usually uses aerobic sludge activation method, but due to the unstable water quality and quantity of alkali reduction wastewater, high concentration of organic matter, wide range of pH value, and many organic matters that are not easy to degrade, some ordinary activated sewage Sludge swelling, weak impact resistance, and large amount of excess sludge occurred during the operation of the sludge. Later, although the above shortcomings were improved by replacing the activated sludge pool with a contact oxidation tank, the energy consumption was still high, and the output of excess sludge was large. Increase the investment and operating costs of sludge treatment equipment, in addition to the higher nutritional requirements for some industrial wastewater

Method used

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  • Method for recovering and purifying terephthalic acid in alkali-minimization waste liquor
  • Method for recovering and purifying terephthalic acid in alkali-minimization waste liquor
  • Method for recovering and purifying terephthalic acid in alkali-minimization waste liquor

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Add activated carbon to the alkali reduction waste liquid and stir at room temperature for 3-5 hours, add 1 g of activated carbon to 1 L of waste liquid, absorb organic matter in the solution, and initially remove colored pigments and most of the organic impurities. Then, the activated carbon and small particles in the waste liquid are filtered through a microporous filter, and the filtrate is a sodium terephthalate solution. The filtrate is neutralized with 5~20% dilute acid (one or more of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid mixed acid solution), stirring constantly, the solution slowly becomes a white suspension, add acid to the solution pH When the value is lower than 3, the white solid is filtered out, and the filtrate has no obvious change after adding dilute acid, and the acid precipitation is complete. Acid-analyzed solids were washed with water, filtered, dried, and ground to obtain crude terephthalic acid.

[0040] Add 10 g of crude...

Embodiment 2

[0042] Treat the alkali reduction waste liquid in a manner similar to Example 1, except that no activated carbon adsorbent is added in this example, and the relevant analysis data results are compared in Table 1.

Embodiment 3

[0044] The alkali reduction waste liquid was treated in a manner similar to Example 1, except that 2 g of activated carbon was added to 1 L of waste liquid in this example, and the relevant analysis data results were compared in Table 1.

[0045] Table 1 The effect of the amount of decolorizing agent added on the color of the product

[0046]

[0047] As can be seen from the results of comparative examples 1 to 3, without adding decolorizer, the product color is dark, but the same 1 L waste liquid plus 1 g decolorizer is compared with adding 2 g decolorizer, the color of the product obtained is not significantly improved, and the reclaimed The color index of terephthalic acid is very good, so it is more appropriate to decolorize 1 L of waste liquid with 1 g of activated carbon.

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Abstract

The invention relates to a method for purifying terephthalic acid in alkali-minimization waste liquor through acidolysis and crystallization, which comprises the following steps of: adsorbing to remove organic impurities and colored substances from the alkali-minimization waste liquor by using active carbon; adding a dilute acid solution into filtrate for acidolysis, and extracting the terephthalic acid from the waste liquor; drying and grinding a filter cake to obtain coarse terephthalic acid; dissolving and crystallizing the terephthalic acid by using a strong polar organic solvent, and performing recrystallization for multiple times to more effectively improve the purity of the terephthalic acid; and washing with water, filtering, drying, and refining the terephthalic acid to make the purity more than 99.8 percent, so that the terephthalic acid can be polymerized with glycol to produce polyester. By the method, the chemical oxygen demand (COD) of discharged wastewater can be effectively reduced, high-purity terephthalic acid can be obtained through recovery and purification, and waste materials can be reutilized.

Description

technical field [0001] The present invention relates to a recycling method of alkali reduction waste liquid, in particular to a technology for obtaining high-purity terephthalic acid from waste liquid, which mainly consists of regenerating crude terephthalic acid obtained after acid analysis of waste liquid Crystallization purification techniques. Background technique [0002] Alkali weight reduction waste liquid is a waste liquid produced during the process of hydrolyzing polyester fibers with alkali in order to make the produced polyester fabric more silky and imitative. In caustic soda solvent, polyester fibers are hydrolyzed under high temperature conditions to generate sodium terephthalate and ethylene glycol, and the degraded terephthalic acid and ethylene glycol monomers in polyester fabrics exist in water to form alkali weight reduction waste liquid, process principle : [0003] [0004] [0003] This processing technology produces organic wastewater with high ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C63/26C07C51/02C07C51/43
Inventor 吴思操王世栋程振民于敬
Owner EAST CHINA UNIV OF SCI & TECH
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