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Fractional separation method of kraft lignin

A kraft lignin and fractionation separation technology, applied in the field of lignin separation, can solve the problem of complex and uneven structure, achieve the effects of less equipment and investment, simple operation, and low overall production cost

Inactive Publication Date: 2016-11-09
BEIJING FORESTRY UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the existing problem of complex and heterogeneous lignin structure, the present invention provides a fractionation method for kraft lignin, which adopts the stepwise acid precipitation method to fractionate lignin to obtain lignin with different molecular weight distribution ranges, so that lignin The structure and properties of lignin are more uniform, and then the active group content in different fractions of lignin is used for directional transformation and utilization

Method used

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  • Fractional separation method of kraft lignin
  • Fractional separation method of kraft lignin
  • Fractional separation method of kraft lignin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] 800g of absolutely dry poplar wood is packed into a 10L vertical electric heating cooking pot, and the amount of alkali used is 24% (based on Na 2 O meter), the degree of sulfide is 25%, the solid-liquid ratio is 1:5, the temperature is raised to 165°C, the heating time is 1h, and the heat preservation time is 2-3h. After the reaction is over, use the pressure in the pot to collect the discharged black liquor, and then filter it with a Buchner funnel to remove large particles in the black liquor.

Embodiment 2

[0024] (1) Take 100ml of the filtered black liquor in Example 1, add 400ml of distilled water, add 0.7g of DTPA chelating agent for chelating treatment, stir at 25°C for 1.5h, and the stirring speed is 400rpm.

[0025] (2) Add sulfuric acid with a concentration of 2mol / L to the stirred black liquor, slowly adjust the pH value of the solution to 6, continue to stir for 1-2h, and then centrifuge to obtain the lignin component L1, and collect the centrifuged liquid .

[0026] (3) Continue to add sulfuric acid with a concentration of 2 mol / L to the liquid collected in step (2), slowly adjust the pH value of the solution to 4, and keep stirring for 1-2h, and then centrifuge to obtain the lignin component L2, Collect the centrifuged liquid.

[0027] (4) Continue to add sulfuric acid with a concentration of 2 mol / L to the liquid collected in step (3), slowly adjust the pH value of the solution to 2, and keep stirring for 1-2 hours, and then centrifuge to obtain the lignin component ...

Embodiment 3

[0030] The determination of lignin molecular weight is as follows: Weigh 4mg acetylated lignin sample and dissolve it in 2ml chromatographic grade tetrahydrofuran, dissolve and filter into PLgel Mixed-D (300×7.5mm, Agilent, USA) chromatographic column for analysis, and inject The amount is 10ul. The eluent was chromatographic grade tetrahydrofuran, and the flow rate was 1ml / min.

[0031] The gel permeation chromatograms of lignin components L1, L2 and L3 are shown in figure 1 , figure 2 and image 3 , the results show that the fractionation of kraft lignin can be realized by this method, and the average weight-average molecular weights of the three separated lignins L1, L2 and L3 are 1704g / mol, 1270g / mol and 800g / mol, respectively.

[0032] It can be seen from the above examples that the acid stepwise precipitation method can obtain lignin with different molecular weight distribution ranges, and the operation process is simple, the required equipment and investment are les...

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Abstract

The invention discloses a fractional separation method of kraft lignin. According to the method, fractional separation is conducted on the lignin by means of a step-by-step acid precipitation method, the lignin with different molecular weight distribution ranges is obtained, the structural performance of the lignin is more uniform, and oriented conversion utilization is conducted on the content of active groups in the lignin with different fractions. According to the extraction method, the pH value of black liquor is adjusted through sulfuric acid step by step to enable the lignin to be precipitated, the obtained lignin is high in purity and uniform in distribution of molecular weight sizes, operation is easy, less equipment and investment are needed, and the comprehensive production cost is low.

Description

technical field [0001] The invention belongs to the technical field of lignin separation, and relates to a fractionation method for kraft lignin. Background technique [0002] Pulping black liquor is one of the main sources of pollution in the paper industry, accounting for 70%-80% of the total pollution in the paper industry. About 30% of impurities in papermaking black liquor are inorganic compounds, mainly NaOH and SiO2; 70% are organic substances, mainly including lignin, hemicellulose and some organic acid sugars. At present, there are two main methods for black liquor treatment: one is alkali recovery, which is recovered by evaporation, concentration, causticization or electrodialysis; the other is to extract lignin, the main component of black liquor. According to incomplete statistics, the black liquor in my country's paper industry contains more than 30 million tons of lignin, but now most of the use of lignin is to burn it to generate heat, and only a small part i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C11/00C08H7/00
CPCD21C11/00C07G1/00
Inventor 许凤邵鲁鹏张奇琳张学铭马明国
Owner BEIJING FORESTRY UNIVERSITY
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