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Method for improving decoloring efficiency of gallic acid

A technology of gallic acid and decolorization efficiency, applied in the separation/purification of carboxylic acid compounds, preparation of carboxylic acid esters/lactones, organic chemistry, etc., can solve the problem of low color number of gallic acid and the amount of activated carbon that affect product quality and production efficiency Major problems, to achieve the effect of reduced decolorization cost, good product quality, and reduced consumption of activated carbon

Inactive Publication Date: 2017-04-05
湖南利农五倍子产业发展有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of existing decolorization methods are that the amount of activated carbon is large, the cost of decolorization is high, and the color number of gallic acid is low, which affects product quality and production efficiency

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] The method that the present invention improves gallic acid decolorization efficiency is:

[0013] a. According to the weight of gallnuts (tannin content 68-70%), add 50% sodium hydroxide with a mass ratio of 95%, add 2.5 times water, and stir at 106°C, normal pressure, 42rpm for 1.5-2 hours, get hydrolyzate;

[0014] b. Add hydrochloric acid to the above hydrolyzate to pH 3, 3.5 or 4, add 1.5kg of EDTA-2Na to every 250kg of the solution, maintain it at 80-90°C for 30 minutes, press filter, crystallize at 10°C, and centrifugally dehydrate. to obtain crude gallic acid;

[0015] c. Add 8 times the weight of pure water to the above crude gallic acid, then add 5% of the used activated carbon of the previous batch of secondary decolorization, keep warm for 30 minutes for decolorization, and vacuum filter to obtain the primary decolorization filtrate. Then press back into the decolorization tank for re-decolorization (secondary decolorization), add unused activated carbon wi...

Embodiment 2

[0017] The method that the present invention improves gallic acid decolorization efficiency is:

[0018] a. According to gallnut weight (tannin content 68-70%), add 95% sodium hydroxide 20% by weight (percentage by weight, that is, add 140kg of 95% sodium hydroxide per 700kg gallnut powder), add 2.5 times The crude mother liquor (the crude mother liquor obtained in the previous batch of step b) was stirred and reacted at 120°C, 0.1MPa, 42rpm for 1.5 hours to obtain a hydrolyzate;

[0019] b. Add hydrochloric acid to the above hydrolyzate to pH 3, 3.5 or 4, add 1.5kg of EDTA-2Na to every 250kg of the solution, keep warm at 80-90°C for 30 minutes, press filter to obtain acidified filtrate and acidified filter residue, Lower the acidified filtrate to 10°C to crystallize, centrifuge and dehydrate to obtain crude gallic acid and dehydrated liquid, put the dehydrated liquid into a tank and heat to 70°C, add 33% of the acidified filter residue and 0.17% oxalic acid by weight, and hea...

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Abstract

The invention discloses a method for improving the decoloring efficiency of gallic acid. In order to overcome the defects that an existing decoloring method is large in quantity of activated carbon, poor in decoloring and the like, the pH value of nutgall hydrolysate is improved to 3-4, and 1.5 kg of EDTA-2Na is added to per 250 kg of the nutgall hydrolysate; pure water is added to the obtained coarse gallic acid product, and the weight of the pure water is 8 times that of the coarse gallic acid product; then 5% of activated carbon used for secondary decoloring of the last batch is added, and primarily decolored filtrate is obtained; and 3-5% of new activated carbon is added in the obtained primarily decolored filtrate, decoloring, filtering, crystallization and dewatering are carried out, and the finished gallic acid product is obtained. The method is used for production of gallic acid, and can remarkably reduce the quantity of activated carbon in the production of gallic acid, reduce the decoloring cost by 50% or over and lower the chromatic number of gallic acid from existing 150-200 to 100-120, the product quality is good, and the production benefit is improved by 10% or over.

Description

technical field [0001] The invention relates to a method for producing gallic acid, in particular to a method for improving the decolorization efficiency of gallic acid. Background technique [0002] In the existing production of gallic acid, it is necessary to use activated carbon for decolorization and refining. The disadvantages of the existing decolorization method are that the amount of activated carbon is large, the cost of decolorization is high, and the color number of gallic acid is low, which affects product quality and production efficiency. Contents of the invention [0003] Purpose of the present invention is exactly at above-mentioned deficiency, provides a kind of method that improves gallic acid decolorization efficiency, and it can reduce gac consumption, reduce decolorization cost, improve gallic acid decolorization effect, improve product quality, improve production efficiency. [0004] In order to achieve the above object, the technical scheme of the p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/47C07C65/03
CPCC07C51/47C07C51/09C07C65/03
Inventor 廖亨斌银云峰
Owner 湖南利农五倍子产业发展有限公司
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