阅读说明：本技术 一种利用农林生物质原料制备木质素纳米管的方法 (Method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials ) 是由 姜曼 胡翔洲 王峰 陆远 潘宇 于 2021-08-27 设计创作，主要内容包括：本发明提供了一种利用农林生物质原料制备木质素纳米管的方法,将粉碎的生物质原料分散在无机碱性溶液中,向其中添加助溶剂后进行球磨,然后离心,收集上清液；向上清液中滴加无机酸至溶液呈中性,然后利用半透膜进行透析,制得含有木质素纳米管的溶液。该方法可有效解决现有的方法中存在的操作过程复杂、存在环境污染的问题。(The invention provides a method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials, which comprises the steps of dispersing crushed biomass raw materials in an inorganic alkaline solution, adding a cosolvent into the inorganic alkaline solution, carrying out ball milling, then centrifuging, and collecting supernate; and (3) dropwise adding inorganic acid into the supernatant until the solution is neutral, and then dialyzing by using a semipermeable membrane to prepare the solution containing the lignin nanotubes. The method can effectively solve the problems of complex operation process and environmental pollution existing in the existing method.)

1. A method for preparing a lignin nanotube by using an agricultural and forestry biomass raw material is characterized by comprising the following steps:

(1) dispersing the crushed biomass raw material in an inorganic alkaline solution, adding a cosolvent into the inorganic alkaline solution, performing ball milling, centrifuging, and collecting a supernatant;

(2) and (2) dropwise adding inorganic acid into the supernatant obtained in the step (1) until the solution is neutral, and then dialyzing by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

2. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials according to claim 1, wherein the mass concentration of the inorganic alkaline solution in the step (1) is 0.1-4%, and the volume ratio of the alkaline solution to the cosolvent is 100: 5-50.

3. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw material according to claim 1, wherein the mass concentration of the biomass raw material in the inorganic alkaline solution in the step (1) is 0.5-10%.

4. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials according to claim 1, wherein the inorganic alkaline solution in the step (1) is a sodium hydroxide solution or a potassium hydroxide solution.

5. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials according to claim 1, wherein the cosolvent in the step (1) is tetrahydrofuran, dimethyl sulfoxide or polyethylene glycol.

6. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials as claimed in claim 1, wherein the ball milling rotation speed in step (1) is 300-600rpm, and the ball milling time is 8-12 h.

7. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials as claimed in claim 1, wherein the centrifugation rotation speed in step (1) is 10000-12000rpm, and the centrifugation time is 5-10 min.

8. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials according to claim 1, wherein the inorganic acid in the step (2) is hydrochloric acid, nitric acid or sulfuric acid, and the mass concentration of the inorganic acid is 0.1-1%.

9. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials as claimed in claim 1, wherein the dropping speed of the inorganic acid in the step (2) is 100-1000 μ L/min.

10. The method for preparing lignin nanotubes by using agricultural and forestry biomass raw materials according to claim 1, wherein the dialysis time in the step (2) is 24-48 h.

Technical Field

The invention belongs to the technical field of lignin nanotubes, and particularly relates to a method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials.

Background

The tubular structure has many advantages, such as large specific surface area, and can generate blocking and dissipation effects on sound wave heat and the like; tubular structures have many applications in social life, such as adsorption, sound insulation, protection, etc., and various materials are used to synthesize products having tubular structures, so that the obtained materials have the largest specific surface area under the same volume, resulting in quite excellent macroscopic properties.

The lignin is the only renewable natural aromatic macromolecule in the nature, the source of the lignin is wide, the lignin accounts for more than 15-30% of various agriculture and forestry biomass resources, in addition, the pulping and papermaking industry can also generate a large amount of lignin wastes, and the lignin wastes are mostly consumed as low-value fuels or fillers, so that the resource waste is caused.

The lignin has the functions of antibiosis, ageing resistance, ultraviolet absorption and the like, contains a large number of phenolic hydroxyl functional groups, and can be spontaneously assembled into a stable nano structure by virtue of pi-pi interaction and hydrogen bond interaction of benzene rings of the lignin. The lignin can be controlled by some auxiliary means to be spontaneously assembled into spherical particles with regular structures or nanospheres with hollow structures, but the existing method has the problems of complex operation process, need of using harmful preparations in the operation process and easy environmental pollution.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for preparing a lignin nanotube by using an agricultural and forestry biomass raw material, which can effectively solve the problems of complex operation process and environmental pollution in the prior method.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows:

a method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing the crushed biomass raw material in an inorganic alkaline solution, adding a cosolvent into the inorganic alkaline solution, performing ball milling, centrifuging, and collecting a supernatant;

(2) and (2) dropwise adding inorganic acid into the supernatant obtained in the step (1) until the solution is neutral, and then dialyzing by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Further, the mass concentration of the inorganic alkaline solution in the step (1) is 0.1-4%, and the volume ratio of the alkaline solution to the cosolvent is 100: 5-50.

Further, the biomass raw material in the step (1) is crop straw, wood, bamboo or commercial lignin.

Further, the mass concentration of the biomass raw material in the inorganic alkaline solution in the step (1) is 0.5-10%.

Further, the inorganic alkaline solution in the step (1) is a sodium hydroxide solution or a potassium hydroxide solution.

Further, the cosolvent in the step (1) is tetrahydrofuran, dimethyl sulfoxide or polyethylene glycol.

Further, the molecular weight of polyethylene glycol is 2000-.

Further, the ball milling rotation speed in the step (1) is 300 and 600rpm, and the ball milling time is 8-12 h.

Further, the centrifugation speed in the step (1) is 10000-12000rpm, and the centrifugation time is 5-10 min.

Further, in the step (2), the inorganic acid is hydrochloric acid, nitric acid or sulfuric acid, and the mass concentration of the inorganic acid is 0.1-1%.

Further, the dropping speed of the inorganic acid in the step (2) is 100-.

Further, the dialysis time in the step (2) is 24-48 h.

The beneficial effects produced by the invention are as follows:

according to the invention, the inorganic alkaline solution is used as a solvent, so that the dissolving amount of lignin can be increased, potassium hydroxide or sodium hydroxide is selected for alkaline dissolution, and can be neutralized with acid in the subsequent treatment process to generate harmless substances such as potassium salt or sodium salt, so that the environmental protection performance is improved, and harmless treatment is realized; tetrahydrofuran is added into the alkaline solution, and can promote the dissolution of lignin, and the formation of the lignin nanotube can be improved by using the tetrahydrofuran and the alkaline solution together; the lignin is not contained in an acidic solution, and acid liquor is dripped into the solution dissolved with the lignin, so that the lignin in the solution is separated out and self-assembled to gradually form a nano-tube-shaped structure.

The method is simple and easy to implement and convenient to operate, the used solvent basically does not pollute the environment, and the method has the advantages of environmental protection and safety, and the lignin nanotube product can be quickly prepared by adopting the method.

Drawings

FIG. 1 is a microscopic structure of a lignin nanotube in example 1;

FIG. 2 is a microscopic structure view of the lignin nanotubes of example 1;

FIG. 3 is a microscopic structure view of the lignin nanotubes of example 1;

FIG. 4 is a microstructure diagram of the lignin nanotubes of example 1.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

Example 1

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straws in a sodium hydroxide solution with the mass concentration of 0.4%, adding tetrahydrofuran into the biomass raw materials with the mass concentration of 1% in the sodium hydroxide solution, then carrying out ball milling, wherein the volume ratio of the sodium hydroxide solution to the tetrahydrofuran is 100:5, the ball milling rotation speed is 600rpm, the ball milling time is 10h, then centrifuging for 5min under the condition of 10000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 200 mu L/min until the solution is neutral, and dialyzing for 48 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Example 2

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straw in a sodium hydroxide solution with the mass concentration of 2%, adding polyethylene glycol with the molecular weight of 4000 into the biomass raw material with the mass concentration of 3% in the sodium hydroxide solution, then carrying out ball milling, wherein the volume ratio of the sodium hydroxide solution to the polyethylene glycol is 100:10, the ball milling rotation speed is 300rpm, the ball milling time is 8h, then centrifuging for 7min under the condition of 12000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 500 mu L/min until the solution is neutral, and dialyzing for 24 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Example 3

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed corn straws in a potassium hydroxide solution with the mass concentration of 3%, adding dimethyl sulfoxide into the biomass raw materials with the mass concentration of 6% in the potassium hydroxide solution, performing ball milling, wherein the volume ratio of the potassium hydroxide solution to the dimethyl sulfoxide is 100:10, the ball milling rotation speed is 500rpm, the ball milling time is 8 hours, centrifuging for 6min under the condition of 12000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.7% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 400 mu L/min until the solution is neutral, and dialyzing for 3 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Comparative example 1

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straws in a sodium hydroxide solution with the mass concentration of 0.4%, adding absolute ethyl alcohol into the biomass raw materials with the mass concentration of 1% in the sodium hydroxide solution, then carrying out ball milling, wherein the volume ratio of the sodium hydroxide solution to the absolute ethyl alcohol is 100:5, the ball milling rotation speed is 600rpm, the ball milling time is 10h, then centrifuging for 5min under the condition of 10000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 200 mu L/min until the solution is neutral, and dialyzing for 48 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Comparative example 2

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straws in a sodium hydroxide solution with the mass concentration of 0.4%, adding tetrahydrofuran into the biomass raw materials with the mass concentration of 1% in the sodium hydroxide solution, then carrying out ball milling, wherein the volume ratio of the sodium hydroxide solution to the tetrahydrofuran is 100:5, the ball milling rotation speed is 600rpm, the ball milling time is 10h, then centrifuging for 5min under the condition of 10000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% acetic acid into the supernatant obtained in the step (1) at a dropping speed of 200 mu L/min until the solution is neutral, and dialyzing for 48 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Comparative example 3

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straws in a sodium carbonate solution with the mass concentration of 0.4%, adding tetrahydrofuran into the biomass raw materials with the mass concentration of 1% in the sodium carbonate solution, performing ball milling, wherein the volume ratio of the sodium carbonate solution to the tetrahydrofuran is 100:5, the ball milling rotation speed is 600rpm, the ball milling time is 10 hours, centrifuging for 5min under the condition of 10000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 200 mu L/min until the solution is neutral, and dialyzing for 48 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Comparative example 4

A method for preparing lignin nanotubes by using agriculture and forestry biomass raw materials comprises the following steps:

(1) dispersing 100g of crushed wheat straws in a sodium hydroxide solution with the mass concentration of 0.4%, adding tetrahydrofuran into the biomass raw materials with the mass concentration of 1% in the sodium hydroxide solution, then carrying out ball milling, wherein the volume ratio of the sodium hydroxide solution to the tetrahydrofuran is 100:3, the ball milling rotation speed is 200rpm, the ball milling time is 15h, then centrifuging for 5min under the condition of 10000rpm, and collecting supernatant;

(2) and (2) dropwise adding 0.4% hydrochloric acid into the supernatant obtained in the step (1) at a dropping speed of 200 mu L/min until the solution is neutral, and dialyzing for 48 hours by using a semipermeable membrane to obtain a solution containing the lignin nanotubes.

Test examples

Respectively taking 7 parts of straw raw materials with the same quantity, preparing the lignin nanotubes according to the methods in the examples 1-3 and the comparative examples 1-4, respectively observing the prepared lignin nanotubes in the examples 1-3 and the comparative examples 1-4, and specifically referring to the attached drawings 1-4, calculating the yield of the lignin nanotubes, and specifically referring to the table 1.

Table 1: yield of lignin nanotubes

	Yield (g) of lignin nanotubes
		Example 1	75
Example 2	65
		Example 3	50
Comparative example 1	0
		Comparative example 2	40
Comparative example 3	10
		Comparative example 4	45

As can be seen from the data in the above table, the yields of lignin nanotubes obtained in examples 1-3 were all higher than those of comparative examples 1-4, especially the yield of lignin nanotubes was the highest in example 1.

As can be seen from fig. 1-4, the lignin produced is in a tubular structure.