CN101372815B - Method for separating lignose and cellulose in licorice waste slag by means of ultrasonic technology - Google Patents

Abstract

The invention relates to a method for separating lignin and cellulose from the wastes generated during the processes of extracting flavone, glycyrrhizic acid or polyoses from the traditional Chinese herb of liquorice. The method includes the following steps: (1) the waste residue of liquorice is added into the mixed solvent of methyl isopropyl ketone-ethanol-water and is manufactured into a turbid liquid; (2) the turbid liquid is treated by ultrasonic and then is stood for a certain period of time and filtered to obtain the filtrate and filter residues; (3) after the filtrate is condensed in vacuum and the solvent is recycled, a crystal is obtained; then the obtained filtrate is filtered and dried to obtain the lignin; the filter residues are directly dried to obtain the cellulose. The method for separating lignin and cellulose from the waste residue of the liquorice by utilizing the ultrasonic technology can overcome the defects of environment pollution and resource wasting caused bya soda boiling method and sulphite as well as the defect of high energy consumption caused by a high-boiling alcohol solvent method. The method creates a new approach for the comprehensive utilization of the waste residues of the liquorice.

Description

Method for Separating Lignin and Cellulose in Licorice Waste Residue Using Ultrasonic Technology

1. Technical field

The invention relates to a method for separating lignin and cellulose from waste produced in the process of extracting flavonoids, glycyrrhizic acid or polysaccharides from traditional Chinese herbal medicine licorice.

2. Background technology

Licorice is the root and rhizome of the leguminous Glycyrrhiza plant, and it is a commonly used species in traditional Chinese medicine. At present, there are many manufacturers in the central and western regions of my country related to the extraction and production of active ingredients in licorice, and a large amount of licorice waste residue remaining after extraction is thrown away or burned as waste. China consumes 6×10 ⁴ tons of hay every year, and can recycle 1.2×10 ⁴ to 1.5×10 ⁴ tons of pure lignin and 1.8×10 ⁴ to 2.0×10 ⁴ tons of cellulose, which is a huge fortune. Therefore, the utilization of licorice residue should attract people's attention. Licorice residue is rich in lignin and cellulose. If it can be used to replace wood to produce lignin and cellulose with higher added value, it will not only provide a new way for the systematic utilization of licorice residue, but also create higher economic benefits .

In licorice residue, cellulose forms a supramolecular system together with lignin and hemicellulose, and lignin and hemicellulose form a firm bonded layer surrounding cellulose. Therefore, in order to separate the cellulose in the licorice residue, the first consideration should be to dissolve the lignin and hemicellulose associated with the cellulose.

On February 19, 1997, the China Patent Office announced a "extraction process of flavonoids, lignin _and cellulose in licorice", the application number is 95109065.8, which is characterized in that Ca(OH) lignin to generate calcium lignin precipitate, and then use Na ₂ CO ₃ to convert lignin calcium precipitate to obtain alkali lignin or pure lignin separated by acid precipitation. This method uses strong alkali to precipitate and dissolve lignin, and a large amount of strong alkali Ca(OH) ₂ and Na ₂ CO ₃ are used in the reaction process, which has a strong corrosion effect on the equipment, and produces waste residue and waste lye, which is easy to cause secondary environmental pollution.

Using the organic solvent method to dissolve lignin, because the solvent used has good solubility and volatility, the waste liquid generated can be concentrated under reduced pressure to recover the organic solvent to achieve the purpose of recycling, which is an ideal separation of lignin and fiber prime method. A kind of " method for preparing cellulose and lignin with high boiling alcohol solvent " was announced by the Chinese Patent Office on June 18, 2003, and the application number is 02157689.0. Its disadvantages are that the reaction process requires high temperature and high pressure, high energy consumption, and the purity of the obtained cellulose is not high after only using organic solvents for delignification.

According to the literature report of "Research on Extracting Alkali Lignin from Luo Han Guo Pomace by Ultrasonic Method" ("Forest Products Chemistry and Industry" magazine, 2004, Volume 24, No. 4, Page 73), the ultrasonic-assisted alkaline method extracts lignin, and the extraction rate will be obtained. Significant improvement. However, there is no relevant report on the use of ultrasonic-assisted organic solvent delignification. Aiming at the problems of environmental pollution and resource waste caused by the traditional lignin and cellulose separation process using alkali cooking method and sulfite method, and energy consumption of high boiling alcohol solvent method, a low energy consumption, mild and efficient separation method is invented. The method of licorice waste residue lignin and cellulose is the main direction of research in this field.

3. Contents of the invention

The present invention selects organic medium and water, and utilizes the special effects of ultrasonic waves (cavitation, mechanical and thermal effects) to assist in the separation of lignin and cellulose in licorice waste residue. The β-O-4 bond between lignin and hemicellulose and the α-O-4 ether bond between lignin and hemicellulose are broken, and the lignin molecules dissolve in the organic phase to separate from the cellulose.

Concrete technical scheme of the present invention is as follows:

(1) Add a certain amount of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 into licorice waste residue A to make a turbid liquid, and the ratio of solid to liquid is 1:10g/mL ;

(2) process the turbid liquid with ultrasonic waves, the ultrasonic wave action device used is an ultrasonic cleaner, the ultrasonic action time is 30～120min, the temperature is 20～50°C, the power of the ultrasonic waves used is 100～950W, and the frequency of the ultrasonic waves is 20～60kHz;

(3) Insulate and stand at 40°C for 2 to 5 hours, and centrifuge to obtain supernatant B and filter residue C after the precipitation is complete;

(4) Add water to the supernatant B, the ratio of the supernatant B to the amount of water added is 1: 1.4 (volume ratio), so that the insoluble MIPK produces two-phase stratification: the upper layer is separated into the MIPK phase, and the MIPK is recovered by vacuum concentration to obtain Crystallization, lignin is obtained after filtration, washing and drying; the lower layer is the hydrated phase, which is concentrated and crystallized to obtain hemicellulose and soluble sugar;

(5) The filter residue C is dried at a temperature of 80°C for 3-5 hours to obtain cellulose D.

Beneficial effect: in the mixed solvent system of methyl isopropyl ketone-ethanol-water, ultrasonic wave preferentially breaks the bond between lignin and cellulose; due to the mild condition and short action time of ultrasonic wave, it can avoid degradation of cellulose. After the lignin is degraded into fragments under the action of ultrasonic waves, it is dissolved in the phase of methyl isopropyl ketone to separate from the cellulose, and the cellulose with higher yield and purity can be obtained than that extracted with organic solvent alone.

4. Specific implementation

The present invention will be further described below in conjunction with the examples, but the present invention is not limited to the contents of the examples.

Example 1

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 30° C., the ultrasonic treatment time is 60 min, the ultrasonic power used is 950 W, and the ultrasonic frequency is 20 kHz. After the ultrasonic treatment, transfer the container containing the treatment solution to a constant temperature water bath at 40°C for 2 hours, and suction filter after the precipitation is complete. Add 280 mL of water to the filtrate, separate the MIPK phase, recover MIPK by rotary evaporation, and dry the extract to obtain 3.1 g of lignin. The filter cake was vacuum dried at 80°C for 4 hours to obtain 7.6 g of cellulose.

Example 2

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 40° C., the ultrasonic treatment time is 90 minutes, the ultrasonic power used is 700 W, and the ultrasonic frequency is 20 kHz. After the ultrasonic treatment, transfer the container containing the treatment solution to a constant temperature water bath at 40°C for 5 hours, and suction filter after the precipitation is complete. Add 280 mL of water to the filtrate, separate the MIPK phase, recover the MIPK by rotary evaporation, and dry the extract to obtain 3.5 g of lignin. The filter cake was vacuum-dried at 80° C. for 5 hours to obtain 7.8 g of cellulose.

Example 3

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 50° C., the ultrasonic treatment time is 120 min, the ultrasonic power used is 600 W, and the ultrasonic frequency is 40 kHz. After the ultrasonic treatment, transfer the treatment liquid to a constant temperature water bath at 40°C for 3 hours. After the precipitation is complete, filter with suction, add 280 mL of water to the filtrate, separate the MIPK phase, recover MIPK by rotary evaporation, and dry the extract to obtain 4.0 g of lignin. The filter cake was vacuum dried at 80°C for 3 hours to obtain 7.9 g of cellulose.

Example 4

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 40° C., the ultrasonic treatment time is 50 minutes, the ultrasonic power used is 500 W, and the ultrasonic frequency is 40 kHz. After the ultrasonic treatment, transfer the treatment solution to a constant temperature water bath at 40°C for 4 hours. After the precipitation is complete, filter with suction, add 280 mL of water to the filtrate, separate the MIPK phase, recover MIPK by rotary evaporation, and dry the extract to obtain 3.7 g of lignin. The filter cake was vacuum dried at 80°C for 3 hours to obtain 7.2 g of cellulose.

Example 5

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 50° C., the ultrasonic treatment time is 50 minutes, the ultrasonic power used is 350 W, and the ultrasonic frequency is 60 kHz. After the ultrasonic treatment, the treatment solution was transferred to a constant temperature water bath at 40°C for 2.5 hours, and then suction filtered after the precipitation was complete. Add 280 mL of water to the filtrate, separate the MIPK phase, recover MIPK by rotary evaporation, and dry the extract to obtain 3.2 g of lignin. The filter cake was vacuum dried at 80°C for 4 hours to obtain 6.7 g of cellulose.

Example 6

Accurately weigh 20.0 g of licorice waste residue, add 200 mL of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 to make a cloudy solution. At a temperature of 20° C., the ultrasonic treatment time is 30 minutes, the ultrasonic power used is 100 W, and the ultrasonic frequency is 60 kHz. After the ultrasonic treatment, the treatment solution was transferred to a constant temperature water bath at 40°C for 2 hours, and then suction filtered after the precipitation was complete. Add 280 mL of water to the filtrate, separate the MIPK phase, recover MIPK by rotary evaporation, and dry the extract to obtain 2.5 g of lignin. The filter cake was vacuum dried at 80°C for 5 hours to obtain 5.9 g of cellulose.

Claims (3)

1. a method utilizing ultrasonic technology to separate lignin and cellulose in Radix Glycyrrhizae waste residue, is characterized in that, comprises the following steps: (1) Add a certain amount of methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent MIPK:ethanol:water=50:30:20 into licorice waste residue A to make a turbid liquid, and the ratio of solid to liquid is 1:10g/mL ; (2) process the turbid liquid with ultrasonic waves, the ultrasonic wave action device used is an ultrasonic cleaner, the ultrasonic action time is 30～120min, the temperature is 20～50°C, the power of the ultrasonic waves used is 100～950W, and the frequency of the ultrasonic waves is 20～60kHz; (3) Insulate and stand at 40°C for 2 to 5 hours, and centrifuge to obtain supernatant B and filter residue C after the precipitation is complete; (4) Add water to the supernatant B, the ratio of the supernatant B to the amount of water added is 1: 1.4 (volume ratio), so that the insoluble MIPK produces two-phase stratification: the upper layer is separated into the MIPK phase, and the MIPK is recovered by vacuum concentration to obtain Crystallization, lignin is obtained after filtration, washing and drying; the lower layer is the hydrated phase, which is concentrated and crystallized to obtain hemicellulose and soluble sugar; (5) The filter residue C is dried at a temperature of 80°C for 3-5 hours to obtain cellulose D. 2. according to the method for claim 1 utilizing ultrasonic technology to separate lignin and cellulose in licorice waste residue, it is characterized in that the licorice waste residue of step (1) is the licorice waste residue after extracting licorice flavonoids, the licorice waste residue after extracting glycyrrhizic acid, Any of licorice waste residue after extraction of glycyrrhetinic acid and licorice waste residue after extraction of licorice polysaccharide. 3. according to claim 1, utilize ultrasonic technology to separate the method for lignin and cellulose in Radix Glycyrrhizae waste residue, it is characterized in that step (2) is separating lignin and fiber in using methyl isopropyl ketone (MIPK)-ethanol-water mixed solvent During the lignin process, an ultrasonic field was applied to enhance the dissolution of lignin.