Method of extracting lignins different in molecular weight from bamboo pulping black liquor

A technology for pulping black liquor and lignin, which is applied in the field of lignin extraction with different molecular weights, can solve the problems of low separation efficiency and complex lignin fractionation process, and achieve large membrane flux, strong industrial applicability, and slow attenuation speed Effect

Active Publication Date: 2015-09-23
NANJING FORESTRY UNIV
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  • Summary
  • Abstract
  • Description
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  • Application Information

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Problems solved by technology

As a result, the fractionation and separation process of lignin in black liquor is complicated and the separation efficiency is low

Method used

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  • Method of extracting lignins different in molecular weight from bamboo pulping black liquor
  • Method of extracting lignins different in molecular weight from bamboo pulping black liquor
  • Method of extracting lignins different in molecular weight from bamboo pulping black liquor

Examples

Experimental program
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Effect test

Embodiment 1

[0022] Put 1000g of dry bamboo (sliced ​​to 10×20mm) into a 15L vertical electric heating cooking pot, add NaOH and Na 2 S, the degree of sulfide is 20%, the amount of alkali is 10% (referring to NaOH+Na 2 S content, as Na 2 O meter) cooking liquor. After idling at 80 °C for 20 min, the temperature was raised to 160 °C at a rate of 2 °C / min and kept for 1 h. After the reaction is finished, filter the cooking material with a cloth bag to obtain the black liquor of bamboo pulping. The main components of the black liquor are partially degraded lignin, monosaccharides and chemicals, with a solid content of 12.34% and a viscosity of 12.48cps.

Embodiment 2

[0024] A method for fractionating different molecular weight lignin from bamboo pulping black liquor, the steps are as follows

[0025] 1) Bamboo pulping black liquor (prepared in Example 1) was filtered with a Buchner funnel to remove fine fibers and impurities, and hydrochloric acid was added to the filtrate to adjust the pH value to 1.5-2.0 to precipitate lignin;

[0026] 2) The precipitated lignin was dried in an oven at 60°C, and 5 g of the precipitated lignin was dissolved in 40 mL of 90 % (v / v) acetic acid solution to form a lignin acetic acid solution. The lignin in the solution The solids concentration was 12.50 % (w / v).

[0027] 3) Use an ultrafiltration centrifuge tube with a molecular weight cut-off of 5000 Da to ultrafilter the lignin acetic acid solution at 4000 rpm for 30 minutes to obtain the retentate F1 and ultrafiltrate;

[0028] 4) The above ultrafiltrate was ultrafiltered with an ultrafiltration centrifuge tube with a molecular weight cut-off of 3000 Da a...

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Abstract

The invention discloses a method of extracting lignins different in molecular weight from bamboo pulping black liquor. The method includes: filtering the bamboo pulping black liquor, adjusting pH to 1.5 to 2.0, and acquiring lignin by settling; drying the lignin, dissolving the lignin with 90% acetic acid to obtain lignin acetic acid solution of low viscosity, and subjecting the lignin acetic acid solution to ultrafiltration and grading with ultrafiltration membranes having different cut-off molecular weights; and subjecting ultrafiltrate and cut-off liquid to precipitating with distillate according to the ratio being 1:10 and purifying with dichloroethane / water, diethyl ether and petroleum ether solvents to obtain lignins different in molecular weight distribution range. The pH value of the bamboo pulping black liquor of high viscosity is adjusted with hydrochloric acid to precipitate the lignin therein, the lignin is dissolved with the 90% acetic acid, and the lignin acetic acid solution is of low viscosity and is directly graded with the ultrafiltration membranes to separate the lignins; the method has the advantages that stock liquor needs no dilution, membrane flux is great, attenuating speed is low, a membrane component is simple to maintain, and the industrial applicability is high.

Description

technical field [0001] The invention belongs to the technical field of lignin separation and purification, and relates to a method for extracting different molecular weight lignins from bamboo pulping black liquor. Background technique [0002] According to statistics, the wastewater discharge of China's paper industry accounts for 18.6% of the total industrial wastewater discharge in the country, and the chemical oxygen demand (COD) in the discharged wastewater accounts for about 44.0% of the total industrial COD discharge in the country. 90% of industrial wastewater discharge. Pulping black liquor mainly contains lignin, cellulose and hemicellulose degradation products, pigments, residual alkali, etc., which is a complex pollution source with high alkalinity and high COD. According to incomplete statistics, the pulping black liquor of my country's paper industry contains more than 30 million tons of lignin. The rational use of lignin in black liquor can achieve the win-wi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08H7/00C08L97/00
Inventor 勇强黄曹兴何娟闵斗勇李鑫赖晨欢徐勇欧阳嘉余世袁
Owner NANJING FORESTRY UNIV
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