Biomass pyrolysis liquid film as well as film forming liquid and preparation method thereof

Abstract

The invention relates to the technical field of biomass resource utilization, in particular to a biomass pyrolysis liquid film as well as a film forming liquid and a preparation method thereof. The film forming liquid of the biomass pyrolysis liquid film comprises chitosan, a biomass pyrolysis liquid and a nanocellulose suspension; wherein the mass ratio of the biomass pyrolysis liquid to the nano cellulose is (125 to 250): 1. According to the invention, the nanocellulose suspension is introduced into the film forming liquid of the biomass pyrolysis liquid film, and meanwhile, the dosage ratio of the nanocellulose suspension to the biomass pyrolysis liquid is controlled, so that the film material with mechanical property, water resistance and antibacterial property can be obtained. Meanwhile, the preparation process is simple and efficient, the cost is greatly saved, and the application value of the biomass pyrolysis liquid film is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass resource utilization, and in particular to a biomass pyrolysis liquid membrane, a membrane-forming liquid and a preparation method thereof. Background Art

[0002] Biomass film materials are a research direction that has attracted much attention in the fields of materials science and environmental science in recent years. With the increasing global demand for sustainable development and environmentally friendly materials, biomass film, as a new type of green material, has shown good application prospects. Traditional plastic materials have caused serious pollution to the environment during production and use, and the emergence of biomass film materials has provided a new idea for solving this problem. They can not only effectively reduce the generation of plastic waste, but also return to the ecological environment through natural degradation after use, reducing the burden on the ecosystem. Among them, chitosan film has received widespread attention due to its excellent biocompatibility, biodegradability and antibacterial properties.

[0003] However, at present, the development and utilization of chitosan films are limited due to the poor solubility of chitosan and the poor mechanical properties after film formation. In the prior art, CN 117844024 A discloses a method for preparing a chitosan-tannic acid antibacterial oxidation film, and the tensile stress of the film material obtained in the invention is up to 0.6MPa. CN 117720754 A discloses a high-strength chitosan tea polyphenol antibacterial oxidation film. The tensile stress of the film material mentioned in the invention is up to about 0.5MPa. Although these chitosan film materials have strong antibacterial and antioxidant properties, their low mechanical strength limits their application in practical processes.

[0004] Therefore, designing a suitable chitosan film preparation method, simplifying the chitosan film preparation process, and preparing a film material that takes into account mechanical strength, water resistance and functionality are issues that need to be urgently addressed in this field.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The prior patent application CN118620290A discloses a biomass pyrolysis liquid-chitosan film-forming liquid, a biomass pyrolysis liquid film and a preparation method thereof, which can greatly improve the functionality of the film material, but its mechanical strength still has room for further improvement. The present invention further introduces nanocellulose into the film-forming liquid to improve the mechanical strength of the film material, but the results show that although the introduction of nanocellulose into the film-forming liquid using the biomass pyrolysis liquid film as a solvent can improve the mechanical strength of the film material, the addition of nanocellulose will reduce the antibacterial property of the film material.

[0007] After extensive research, the present invention found that by controlling the dosage relationship between nanocellulose and biomass pyrolysis liquid, it is possible to improve both the mechanical strength and antibacterial properties of the original biomass pyrolysis liquid membrane. In addition, it is also possible to improve the water resistance of the biomass pyrolysis liquid membrane and enhance the durability of the biomass pyrolysis liquid membrane.

[0008] Based on this, the present invention has the following technical solutions: In a first aspect, the present invention provides a membrane-forming liquid for a biomass pyrolysis liquid membrane, comprising chitosan, a biomass pyrolysis liquid and a nanocellulose suspension; wherein the mass ratio of the biomass pyrolysis liquid to the nanocellulose is (125-250):1.

[0009] The present invention finds that introducing the above amount of nanocellulose into the biomass pyrolysis solution can improve the mechanical strength, water resistance and antibacterial properties of the membrane material.

[0010] In the present invention, the mass ratio of the biomass pyrolysis liquid to the nanocellulose can be 125:1, 150:1, 175:1, 200:1, 225:1 or 250:1.

[0011] Preferably, the mass ratio of the biomass pyrolysis liquid to the nanocellulose suspension is (1-2):1; and the mass concentration of the nanocellulose suspension is 0.4wt%-1.0wt%.

[0012] In the present invention, the mass concentration of the nanocellulose suspension can be 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt% or 1.0wt%.

[0013] Preferably, based on the total mass of the membrane-forming liquid of the biomass pyrolysis liquid membrane, the content of chitosan is 2wt%~9.1wt%, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% or 9.1wt%.

[0014] Further preferably, based on the total mass of the membrane-forming liquid of the biomass pyrolysis liquid membrane, the content of the chitosan is 2wt%-5wt%.

[0015] Preferably, based on the total mass of the membrane-forming liquid of the biomass pyrolysis liquid membrane, the content of the biomass pyrolysis liquid is 46-65wt%; for example, it can be 46wt%, 47wt%, 48wt%, 49wt%, 50wt%, 55wt%, 60wt%, 65wt% or any value between any two values.

[0016] Preferably, the film-forming solution is composed of the following components in parts by weight: 1~2 parts of biomass pyrolysis liquid; Chitosan 0.04~0.2 parts; 1 part of nanocellulose suspension; wherein the mass concentration of the nanocellulose suspension is 0.4wt%~1.0wt%.

[0017] Preferably, the nanocellulose includes one or more of cellulose nanocrystals, cellulose nanofibers, bacterial cellulose and TEMPO-oxidized nanocellulose.

[0018] In the present invention, the raw materials of nanocellulose can be plant fibers, algae, tunicates and bacteria; and the plant fiber raw materials include wood, bamboo, cotton, hemp, straw, wheat straw, reed, pulp, etc. These raw materials can be synthesized into the above-mentioned nanocellulose materials through different extraction techniques and methods disclosed in the prior art, such as acid hydrolysis, mechanical refining, enzymatic hydrolysis, etc., which are not limited here. For example, TEMPO-oxidized nanocellulose is a cellulose nanofiber prepared by an oxidation process mediated by TEMPO (2,2,6,6-tetramethylpiperidin-1-oxyl free radical).

[0019] Preferably, the chitosan has a deacetylation degree of ≥95% and a viscosity of 100-200 mpa∙s.

[0020] Preferably, the method for preparing the biomass pyrolysis liquid comprises: pyrolyzing a biomass raw material, collecting a fraction below 400° C., and condensing the fraction to obtain the biomass pyrolysis liquid.

[0021] In the present invention, the biomass raw material can be wood, bamboo, fruit shell, straw and other biomass raw materials, and the corresponding biomass pyrolysis liquid obtained is wood vinegar, bamboo vinegar, fruit shell wood vinegar, straw wood vinegar.

[0022] More preferably, the method for preparing the biomass pyrolysis liquid may further include refining the biomass pyrolysis liquid to remove wood tar.

[0023] In the present invention, in order to obtain refined biomass pyrolysis liquid, those skilled in the art can use any refining method disclosed in the prior art, such as sequentially performing standing, activated carbon adsorption and distillation operations to remove harmful substances such as wood tar, and the refining method is not limited herein.

[0024] In a second aspect, the present invention provides a method for preparing the membrane-forming liquid of the biomass pyrolysis liquid membrane, comprising: in order to increase the amount of chitosan used and improve the mechanical properties of the membrane material, first mixing the nanocellulose suspension with the biomass pyrolysis liquid, and then adding chitosan and mixing evenly to obtain the membrane-forming liquid of the nanocellulose-enhanced biomass pyrolysis liquid membrane.

[0025] In a third aspect, the present invention provides a method for preparing a biomass pyrolysis liquid film, which comprises: scraping the film-forming liquid of the biomass pyrolysis liquid film on a flat plate, and peeling the film off the flat plate after drying.

[0026] Preferably, the flat plate includes an acrylic plate or a glass plate.

[0027] Preferably, the film scraping is performed by a film scraper, and the thickness of the film scraper is 0.25-1 mm.

[0028] Preferably, the drying is carried out in an oven, and the drying temperature is set at 50-70°C.

[0029] In a fourth aspect, the present invention provides a biomass pyrolysis liquid membrane, which is prepared by the above-mentioned preparation method.

[0030] The biomass pyrolysis liquid membrane and its membrane-forming liquid and preparation method provided by the present invention can obtain a membrane material having both mechanical properties, water resistance and antibacterial properties by introducing a nanocellulose suspension into the membrane-forming liquid of the biomass pyrolysis liquid membrane and controlling the dosage ratio of the nanocellulose suspension to the biomass pyrolysis liquid. The preparation process is simple and efficient, which greatly saves costs and improves the application value of the biomass pyrolysis liquid membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 It is the mechanical strength of the biomass pyrolysis liquid membrane in Example 3 provided by the present invention.

[0033] Figure 2 These are the test results of the water stability of the biomass pyrolysis liquid membranes in Example 3 and Comparative Example 1 provided by the present invention; wherein, (a) is the morphology of the membrane material obtained in Comparative Example 1 soaked in water, (b) is the morphology of the membrane material obtained in Example 3 soaked in water; (c) is the morphology preservation integrity of the membrane materials obtained in Comparative Example 1 (left) and Example 3 after being taken out of water.

[0034] Figure 3These are the antibacterial test results of the biomass pyrolysis films in Comparative Example 1, Comparative Example 2 and Example 3 provided by the present invention; wherein, the left figure represents the antibacterial effect on Escherichia coli (E. coli), and the right figure represents the antibacterial effect on Staphylococcus aureus (S. aureus); in both figures, (a) represents Comparative Example 1, (b) represents Example 5, and (c) represents Example 3. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the various raw materials used in the examples and comparative examples are commercially available conventional raw materials, and the technical means used are conventional means well known to those skilled in the art.

[0037] In the following examples, the chitosan has a deacetylation degree of ≥95% and a viscosity of 100-200 mpa∙s.

[0038] In the following embodiments, the preparation method of biomass pyrolysis liquid includes: the preparation method of biomass pyrolysis liquid includes: pyrolyzing hard miscellaneous wood at 400°C, collecting the fraction below 400°C, and condensing to obtain the biomass pyrolysis liquid.

[0039] Example 1

[0040] The present embodiment provides a membrane-forming liquid of a biomass pyrolysis liquid membrane, which is composed of the following components: 50 g of biomass pyrolysis liquid, 50 g of nanocellulose suspension and 3 g of chitosan powder, wherein the mass concentration of the nanocellulose suspension is 0.8 wt %.

[0041] This embodiment further provides a biomass pyrolysis liquid membrane, the preparation method of which comprises the following steps: (1) Add an equal amount of 0.8 wt% nanocellulose fiber suspension to 50 g of biomass pyrolysis liquid, then add 3% chitosan powder by weight of the film-forming liquid, mechanically stir at 1500 rpm for 1 h, and centrifuge to defoam for 10 min to obtain a nanocellulose-enhanced biomass pyrolysis liquid film-forming liquid; (2) Take a certain amount of the above-mentioned film-forming liquid and pour it onto an acrylic plate. Use a film scraper with a specification of 1 mm to spread the film-forming liquid evenly on the plate. Then put the scraped film into a 60°C oven and dry it for 1 hour. Take it out to obtain the biomass pyrolysis liquid film.

[0042] Example 2

[0043] The present embodiment provides a membrane-forming liquid of a biomass pyrolysis liquid membrane, which is composed of the following components: 50 g of biomass pyrolysis liquid, 50 g of nanocellulose suspension and 3 g of chitosan powder, wherein the mass concentration of the nanocellulose suspension is 0.8 wt %.

[0044] This embodiment further provides a biomass pyrolysis liquid membrane, the preparation method of which comprises the following steps: (1) Add an equal amount of a nanocellulose crystal suspension with a concentration of 0.8 wt% to 50 g of biomass pyrolysis liquid, then add chitosan powder with a concentration of 3% by weight of the film-forming liquid, mechanically stir at 1500 rpm for 1 h, and centrifuge to defoam for 10 min to obtain a film-forming liquid of the biomass pyrolysis liquid enhanced with nanocellulose; (2) Take a certain amount of the above-mentioned film-forming liquid and pour it onto an acrylic plate. Use a film scraper with a specification of 1 mm to spread the film-forming liquid evenly on the plate. Then put the scraped film into a 60°C oven and dry it for 1 hour. Take it out to obtain the biomass pyrolysis liquid film.

[0045] Example 3

[0046] The present embodiment provides a membrane-forming liquid of a biomass pyrolysis liquid membrane, which is composed of the following components: 50 g of biomass pyrolysis liquid, 50 g of nanocellulose suspension and 3 g of chitosan powder, wherein the mass concentration of the nanocellulose suspension is 0.8 wt %.

[0047] This embodiment further provides a biomass pyrolysis liquid membrane, the preparation method of which comprises the following steps: (1) Add an equal amount of bacterial cellulose suspension with a concentration of 0.8 wt% to 50 g of biomass pyrolysis liquid, then add chitosan powder with a concentration of 3% by weight of the film-forming liquid, mechanically stir at 1500 rpm for 1 h, and centrifuge to defoam for 10 min to obtain a film-forming liquid of the biomass pyrolysis liquid enhanced with nanocellulose; (2) Take a certain amount of the above-mentioned film-forming liquid and pour it onto a glass plate. Use a film scraper with a specification of 1 mm to spread the film-forming liquid evenly on the plate. Then put the scraped film into a 60°C oven and dry it for 1 hour. Take it out to obtain the biomass pyrolysis liquid film.

[0048] Example 4

[0049] The present embodiment provides a membrane-forming liquid of a biomass pyrolysis liquid membrane, which is composed of the following components: 50 g of biomass pyrolysis liquid, 50 g of nanocellulose suspension and 3 g of chitosan powder, wherein the mass concentration of the nanocellulose suspension is 0.8 wt %.

[0050] This embodiment further provides a biomass pyrolysis liquid membrane, the preparation method of which comprises the following steps: (1) Adding an equal amount of 0.8 wt% TEMPO-oxidized nanocellulose suspension to 50 g of biomass pyrolysis liquid, and then adding 3% chitosan powder by weight of the film-forming liquid, mechanically stirring at 1500 rpm for 1 h, and centrifuging for defoaming for 10 min to obtain a nanocellulose-enhanced biomass pyrolysis liquid film-forming liquid; (2) Take a certain amount of the above-mentioned film-forming liquid and pour it onto a glass plate. Use a film scraper with a specification of 1 mm to spread the film-forming liquid evenly on the plate. Then put the scraped film into a 60°C oven and dry it for 1 hour. Take it out to obtain the biomass pyrolysis liquid film.

[0051] Example 5

[0052] This embodiment provides a membrane-forming liquid for a biomass pyrolysis liquid membrane, which is different from Embodiment 1 in that it is composed of the following components: 50 g of biomass pyrolysis liquid, 50 g of bacterial cellulose suspension and 3 g of chitosan powder, wherein the mass concentration of the bacterial cellulose suspension is 0.4 wt %.

[0053] Comparative Example 1

[0054] This embodiment provides a method for preparing a nanocellulose-enhanced biomass pyrolysis liquid membrane, and the preparation method thereof is different from that of Embodiment 2 only in that the nanocellulose suspension is replaced by distilled water of the same mass.

[0055] Comparative Example 2

[0056] This comparative example provides a membrane-forming liquid for a biomass pyrolysis liquid membrane, which is different from Example 1 in that it consists of the following components: 25 g of biomass pyrolysis liquid, 50 g of nanocellulose suspension and 1.5 g of chitosan powder, wherein the mass concentration of the nanocellulose suspension is 0.8 wt %.

[0057] Test example

[0058] The membrane materials obtained in the above examples and comparative examples were tested for mechanical properties, antibacterial properties and water solubility: 1. Mechanical properties

[0059] The film was cut into strips of 1 cm × 4 cm, and the thickness of 5 random points on the strip was measured with a micrometer and the average value was taken. The mechanical properties of the film were measured with a physical property analyzer (TA). The initial distance between the two ends of the instrument was 20 mm, the stretching speed was 0.5 mm / s, and three groups of parallel samples were made for each sample to take the average value; the results are shown in Table 1. The mechanical strength of the film material obtained in Example 3 is shown in Table 1. Figure 1 .

[0060] Table 1 Comparison of mechanical properties of membrane materials obtained in comparative examples and examples

[0061] It should be noted that when the biomass pyrolysis solution, the nanocellulose suspension and the chitosan powder are within the specified range of the present invention, such as 60 g of the biomass pyrolysis solution, 50 g of the nanocellulose suspension, 0.8 wt % concentration of the nanocellulose suspension, and 4 g of chitosan, the test results of the mechanical properties of the obtained membrane material are equivalent to those of Examples 1 to 4.

[0062] 2. Stability in water

[0063] Test method: Immerse the film material in water. After half an hour, observe the shape of the film in the water and take photos to record it. After taking it out of the water, observe the shape and take photos to record it.

[0064] Test results see Figure 2 , wherein (a) is the morphology of the membrane material obtained in Comparative Example 1 soaked in water, (b) is the morphology of the membrane material obtained in Example 2 soaked in water; (c) is the morphology of the membrane materials obtained in Comparative Example 1 (left) and Example 2 after being taken out of water.

[0065] 3. Antibacterial properties

[0066] Test method: The agar punch method was used to determine the antibacterial activity of the biomass pyrolysis liquid film. Specifically, a certain concentration of Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) were spread on the sterilized agar solid medium, and the medium was punched with a sterilized pipette tip. The medium in the hole was taken out, and the same volume of film-forming liquid of biomass pyrolysis liquid was injected respectively, and incubated in a constant temperature and humidity biochemical incubator at 37 °C for 12 h. The antibacterial properties of the samples were evaluated by measuring the diameter of the inhibition zone.

[0067] The test results are shown in Table 2, and the antibacterial effect diagrams of Comparative Example 1, Example 3 and Example 5 are shown in Figure 3 .

[0068] Table 2 Comparison of the diameters of the antibacterial zones of the membrane materials obtained in the comparative examples and the examples

[0069] The present invention found that the addition of nanocellulose at a lower concentration (Example 5) does not affect the antibacterial property of the biomass pyrolysis liquid film, but the addition of nanocellulose beyond the dosage range of the present invention (Comparative Example 2) will reduce the antibacterial property of the biomass pyrolysis liquid film. In this regard, the present invention found that when nanocellulose beyond the dosage range of the present invention is added to the system of the present invention, the antibacterial effect will be weakened, which may be because the addition of too much polysaccharide structure will increase the carbon source and active sites in the entire system, which is conducive to the adsorption and growth of microorganisms.

[0070] It should be noted that the diameter of the antibacterial zone of the membrane materials obtained in Examples 1 to 2 and Example 4 is equivalent to that in Example 3 and Example 5; at the same time, when the biomass pyrolysis solution, the nanocellulose suspension and the chitosan powder are within the specified range of the present invention, such as the biomass pyrolysis solution is 60 g, the nanocellulose suspension is 50 g, the concentration of the nanocellulose suspension is 0.8 wt %, and the chitosan is 4 g, the antibacterial property of the obtained membrane material is equivalent to that in Examples 1 to 4.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A membrane-forming liquid for biomass pyrolysis liquid membrane, characterized in that: It includes chitosan, biomass pyrolysis liquid and nanocellulose suspension; wherein the mass ratio of the biomass pyrolysis liquid to the nanocellulose is (125-250):

1.

2. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to claim 1, characterized in that: The mass ratio of the biomass pyrolysis liquid to the nanocellulose suspension is (1-2):1; the mass concentration of the nanocellulose suspension is 0.4wt%-1.0wt%.

3. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to claim 1 or 2, characterized in that: Based on the total mass of the membrane-forming liquid of the biomass pyrolysis liquid membrane, the content of the chitosan is 2.0wt%~9.1wt%.

4. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to any one of claims 1 to 3, characterized in that: Based on the total mass of the membrane-forming liquid of the biomass pyrolysis liquid membrane, the content of the biomass pyrolysis liquid is 46-65wt%.

5. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to any one of claims 1 to 4, characterized in that: The film-forming solution is composed of the following components in parts by weight: 1~2 parts of biomass pyrolysis liquid; Chitosan 0.04~0.2 parts; 1 part of nanocellulose suspension; wherein the mass concentration of the nanocellulose suspension is 0.4wt%~1.0wt%.

6. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to any one of claims 1 to 5, characterized in that: The nanocellulose includes one or more of cellulose nanocrystals, cellulose nanofibers, bacterial cellulose and TEMPO-oxidized nanocellulose.

7. The membrane-forming liquid of the biomass pyrolysis liquid membrane according to any one of claims 1 to 6, characterized in that: The chitosan has a deacetylation degree of ≥95% and a viscosity of 100-200 mpa∙s; And / or, the method for preparing the biomass pyrolysis liquid comprises: pyrolyzing a biomass raw material, collecting a fraction below 400° C., and condensing the fraction to obtain the biomass pyrolysis liquid; Preferably, the method for preparing the biomass pyrolysis liquid further comprises refining the biomass pyrolysis liquid to remove wood tar.

8. The method for preparing a membrane-forming liquid for a biomass pyrolysis liquid membrane according to any one of claims 1 to 7, characterized in that: include: Firstly, the nanocellulose suspension is mixed with the biomass pyrolysis liquid, and then chitosan is added and mixed evenly to obtain the film-forming liquid of the nanocellulose-enhanced biomass pyrolysis liquid membrane.

9. A method for preparing a biomass pyrolysis liquid membrane, characterized in that: include: The film-forming liquid of the biomass pyrolysis liquid film according to any one of claims 1 to 8 is scraped on a flat plate, and the film is peeled off from the flat plate after drying.

10. A biomass pyrolysis liquid membrane, characterized in that: It is prepared by the preparation method described in claim 9.

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