A method for preparing hemp fiber based on combined degumming by photocatalysis and alkali treatment

Abstract

This invention discloses a method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming, comprising the following steps: (1) adding a photocatalyst to a glass reactor to prepare a degumming solution, and immersing the hemp fiber in the degumming solution for phototreatment, and removing the hemp fiber after the phototreatment is completed; (2) placing the phototreated hemp fiber in a container, adding ethanolamine, and heating for 3-6 hours before removing it; (3) washing and drying the hemp fiber obtained in step (2) to obtain degummed hemp fiber. This invention utilizes a photocatalyst and organic alkali to remove pectin, lignin, and other non-cellulose gum components from hemp fiber. The degumming conditions are mild, causing little damage to the hemp fiber, and the organic alkali can be recycled, resulting in less waste liquid and less environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of textile processing technology, specifically to a method for preparing hemp fibers based on a combination of photocatalysis and alkali treatment for degumming. Background Technology

[0002] Hemp is a natural bast fiber. As a high-quality natural cellulose resource, hemp fiber is multifunctional. End products made from hemp can be applied in many areas, such as textiles, construction, papermaking, medicine, biofuels, food, and biocomposite materials. Hemp fiber has a bast fiber structure, consisting of individual cellulose protofibrils bound together by a gum substance, mainly composed of hemicellulose, pectin, waxes, water-soluble materials, and lignin. Because a large amount of gum substance increases the toughness and yellowing of hemp fibers, directly limiting further utilization, it is essential to extract high-quality hemp fiber from hemp without sacrificing the physical properties or chemical structure of cellulose. Therefore, hemp should be degummed before spinning and textile production to obtain soft and fine spun hemp fibers.

[0003] Currently, degumming methods for hemp mainly include physical degumming, traditional alkaline boiling degumming, biological degumming, organic solvent degumming, and combined degumming methods. Among them, physical degumming methods are often used as pretreatment because they are incomplete. Traditional alkaline boiling degumming is relatively stable and widely used, but it is energy-intensive and causes serious pollution. Biological enzymatic degumming can significantly reduce pollution emissions, but the degumming enzymes have a single function and require chemical reagents. Organic solvent degumming can recover the degumming liquid, but the solvent cost is extremely high, wastewater requires further treatment, and the degumming effect of organic solvents is limited, also suffering from incomplete degumming. Therefore, there is an urgent need to develop a degumming method that is mild, has low environmental pollution, and provides good degumming effect. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing hemp fibers based on a combination of photocatalysis and alkali treatment for degumming. This method features mild reaction conditions, minimal environmental pollution, good degumming effect, and minimal damage to the hemp fibers.

[0005] The technical solution adopted in this invention is as follows:

[0006] A method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming includes the following steps:

[0007] (1) Add the photocatalyst suspension to a glass reactor to prepare a degumming solution, and put the hemp bast fibers into the degumming solution for phototreatment. After the phototreatment is completed, take out the hemp fibers.

[0008] (2) After the light treatment, the hemp fibers are placed in a container, ethanolamine is added, and the mixture is heated for 3 to 6 hours before being removed.

[0009] (3) The hemp fibers obtained in step (2) are washed and dried to obtain degummed hemp fibers.

[0010] Furthermore, in step (1), the solid-liquid ratio of hemp bast fibers to water is 1:2 to 10.

[0011] Furthermore, the photocatalyst in step (2) is a catalyst that can be excited in the visible light wavelength range, such as composite photocatalysts containing carbon quantum dots such as TiO2-CQDs and ZnO-CQDs, and other types of composite photocatalysts such as ZnIn2S4.

[0012] In the above technical solution, the photocatalyst is a catalyst that can be excited in the visible light wavelength range, such as TiO2-CQDs, ZnO-CQDs, ZnIn2S4 and other photocatalysts. This type of photocatalyst can be excited in the visible light wavelength range, and visible light accounts for 45% of the total solar energy, so its light utilization rate is high, thereby improving the degumming effect.

[0013] Furthermore, in step (2), the amount of photocatalyst used is 3 to 10 g / kg of hemp fiber.

[0014] Furthermore, the light treatment time in step (2) is 10 to 50 hours.

[0015] Furthermore, the light source used in the illumination process in step (2) is sunlight or simulated sunlight, and simulated sunlight is a light-emitting diode or a xenon lamp.

[0016] Furthermore, in step (2), the solid bath ratio of the hemp bast fiber to the degumming solution is 1:10 to 100.

[0017] Furthermore, in step (3), the heating temperature is 80-100℃ and the heating time is 3-6h.

[0018] Furthermore, in step (3), the solid-liquid ratio of hemp fiber to ethanolamine is 1:15-20.

[0019] Furthermore, the mass concentration of ethanolamine in step (3) is 10-30%.

[0020] Furthermore, the bast fiber of the hemp is one of ramie, hemp, apocynum venetum, kenaf, or jute.

[0021] The beneficial effects of this invention are as follows:

[0022] This invention provides a method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming. The method uses photocatalysis and organic alkali to remove wax, pectin, lignin, hemicellulose and other gum components from hemp bast fibers. The operation process is simple, the degumming conditions are mild, the degumming effect is good, and the damage to hemp fibers is small. Moreover, the organic alkali can be recycled, resulting in less waste liquid and less environmental pollution. Attached Figure Description

[0023] To clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 SEM images of raw hemp before degumming and hemp fibers after degumming in Example 1. Detailed Implementation

[0025] This invention provides a method for preparing hemp fibers based on a combination of photocatalysis and alkali treatment for degumming. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0026] The present invention will now be described in detail with reference to the accompanying drawings.

[0027] Example 1

[0028] This embodiment provides a method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming, including the following steps:

[0029] (1) Add 600ml of 5g / L TiO2-CQDs suspension to a 30L glass reactor to prepare a degumming solution, and put hemp bast fiber into the degumming solution. Add water to make the solid bath ratio of hemp bast fiber to solution 1:20. Place it under sunlight for 4 days of light treatment, specifically 12 hours of light treatment followed by 12 hours of darkness treatment, and repeat for 4 days. After the light treatment is completed, take out the hemp fiber.

[0030] (2) Place the processed hemp fibers into a container and add a 30% ethanolamine solution with a solid-liquid ratio of 1:20. Heat the solution at 100°C for 4 hours and then remove it.

[0031] (3) The hemp fibers obtained in step (2) are washed and dried to obtain degummed hemp fibers.

[0032] Example 2

[0033] This embodiment provides a method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming, including the following steps:

[0034] (1) Add 500ml of 10g / L TiO2-CQDs suspension to a 30L glass reactor to prepare a degumming solution, and put hemp bast fiber into the degumming solution. Add water to make the solid bath ratio of hemp bast fiber to solution 1:50. Use LED lamps to continuously irradiate for 20h. After the irradiation treatment is completed, take out the hemp fiber.

[0035] (2) Place the processed hemp fibers into a container and add an ethanolamine solution with a mass concentration of 40% and a solid-liquid ratio of 1:15. Heat the solution at 90°C for 5 hours and then remove it.

[0036] (3) The hemp fibers obtained in step (2) are washed and dried to obtain degummed hemp fibers.

[0037] Comparative Example 1

[0038] This comparative example provides a method for degumming hemp fibers using a photocatalyst, including the following steps:

[0039] (1) Add 600ml of 5g / L TiO2-CQDs suspension to a 30L glass reactor to prepare a degumming solution, and put hemp bast fiber into the degumming solution. Add water to make the solid bath ratio of hemp bast fiber to solution 1:20, and treat in the dark for 4 days. Then take out the hemp fiber.

[0040] (2) Wash and dry the hemp fiber to obtain degummed hemp fiber.

[0041] Comparative Example 2

[0042] This comparative example provides a method for degumming hemp fibers using a photocatalyst, including the following steps:

[0043] (1) Add 600ml of 5g / L TiO2-CQDs suspension to a 30L glass reactor to prepare a degumming solution, and put hemp bast fiber into the degumming solution. Add water to make the solid bath ratio of hemp bast fiber to solution 1:20. Perform sunlight treatment for 4 days, specifically 12 hours of light treatment followed by 12 hours of darkness treatment, repeat for 4 days. After the treatment is completed, take out the hemp fiber.

[0044] (2) Wash and dry the hemp fiber to obtain degummed hemp fiber.

[0045] Comparative Example 3

[0046] This comparative example provides a method for degumming hemp fibers using alkali treatment, including the following steps:

[0047] (1) Place the hemp bast fiber into a 30L glass reactor and add water. The solid bath ratio of the hemp bast fiber to the solution is 1:20. Then, treat it in the dark for 4 days and then take out the hemp fiber.

[0048] (2) Place the hemp fibers processed in step (1) into a container and add an ethanolamine solution with a mass concentration of 30% and a solid-liquid ratio of 1:20. Heat the solution at 100°C for 4 hours and then remove it.

[0049] (3) Wash and dry the hemp fiber to obtain degummed hemp fiber.

[0050] Comparative Example 4

[0051] This comparative example provides a method for degumming hemp fibers using alkali treatment, including the following steps:

[0052] (1) Place the hemp bast fiber into a 30L glass reactor and add water. The solid bath ratio of the hemp bast fiber to the solution is 1:20. Then, treat it with sunlight for 4 days. Specifically, treat it with sunlight for 12 hours and then treat it in the dark for 12 hours. Repeat this process for 4 days and then take out the hemp fiber.

[0053] (2) Place the hemp fibers processed in step (1) into a container and add an ethanolamine solution with a mass concentration of 30% and a solid-liquid ratio of 1:20. Heat the solution at 100°C for 4 hours and then remove it.

[0054] (4) The hemp fibers are washed and dried to obtain degummed hemp fibers.

[0055] Comparative Example 5

[0056] This comparative example provides a method for preparing hemp fiber based on a combination of photocatalysis and alkali treatment for degumming, including the following steps:

[0057] (1) Add 600ml of 5g / L TiO2-CQDs suspension to a 30L glass reactor to prepare a degumming solution, and put hemp bast fiber into the degumming solution. Add water to make the solid bath ratio of hemp bast fiber to solution 1:20. Treat in the dark for 4 days. After treatment, take out the hemp fiber.

[0058] (2) Place the hemp fibers processed in step (1) into a container and add an ethanolamine solution with a mass concentration of 30% and a solid-liquid ratio of 1:20. Heat the solution at 100°C for 4 hours and then remove it.

[0059] (3) The hemp fibers obtained in step (2) are washed and dried to obtain degummed hemp fibers.

[0060] Scanning electron microscopy was used to test the hemp bast fibers before degumming treatment and the degummed hemp fibers from Example 1 above. Figure 1As shown. From Figure 1 (a) It can be seen that the surface of the raw hemp fibers before degumming is rough, covered with a thick layer of gum, and the fibers aggregate to form bundles; from Figure 1 (b) It can be seen that after TiO2-CQDs photocatalyst and alkali treatment combined with light irradiation, the hemp fiber is separated into individual fibers, and the fiber surface is relatively smooth with low gum content.

[0061] In addition, the degummed hemp fiber and hemp bast fiber prepared in Example 1 and Comparative Examples 1-5 were tested for chemical composition. The test results are shown in Table 1. The physical properties of the hemp bast fiber and the degummed hemp fiber prepared in Example 1 were tested. The test results are shown in Table 2.

[0062] The methods for testing the above chemical composition and physical properties are as follows:

[0063] Test method for chemical composition: The residual gum rate of degummed hemp fiber was tested according to GB 5889–1986 "Quantitative Analysis Method for Chemical Composition of Ramie".

[0064] Fineness test method: Refer to GB / T 6100–2007 "Test method for linear density of cotton fiber - mid-section weighing method" to test the fineness of degummed hemp fiber.

[0065] Test method for bundle fiber strength: The strength of degummed hemp fiber is tested in accordance with GB / T 5882–1986 "Test method for breaking strength of ramie bundle fiber".

[0066] Table 1

[0067]

[0068] Table 2

[0069] Fineness (dtex) Fracture strength (cN / dtex) Hemp bast fiber 12.66±0.07 3.17±0.69 Example 1 10.09±0.08 3.16±1.07

[0070] As can be seen from Table 1 above, Example 1, which uses TiO2-CQDs and organic alkali under light conditions, has the highest removal rate of pectin, lignin, wax, hemicellulose, and other gums in the prepared hemp fiber. Compared with Example 1, Comparative Example 5, which is treated under dark conditions, has a higher content of pectin, hemicellulose, and lignin. Comparative Example 1, which is treated under dark conditions using TiO2-CQDs, still has a high gum content. Comparative Example 2, which is treated under light conditions using TiO2-CQDs, still has a high content of each gum, with only a slight decrease in pectin, lignin, and hemicellulose. Comparative Examples 3 and 4, which are treated under dark or light conditions using ethanolamine, remove some of the pectin, wax, lignin, and hemicellulose, but the content of pectin, lignin, and hemicellulose is still relatively high. These gums can be further removed using the method of Example 1.

[0071] As can be seen from Table 2 above, Example 1 uses a TiO2-CQDs photocatalyst and an organic alkali combined degumming process. After degumming, the fiber fineness is 10.09 dtex and the breaking strength is 3.16 cN / dtex. The degumming effect is good, the amount of glue adhering between the single fibers is reduced, the hemp fiber fineness is finer, and the fiber has better dispersibility. In addition, the reaction conditions in Example 1 are mild, causing less damage to the hemp fiber, so that the hemp fiber has good breaking strength, and the breaking strength remains basically unchanged.

[0072] It should be noted that any parts not mentioned in this invention can be achieved by using or referencing existing technologies.

[0073] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for preparing hemp fiber based on combined degumming via photocatalysis and alkali treatment, characterized in that, Including the following steps: (1) Add the photocatalyst suspension to a glass reactor to prepare a degumming solution, and put the bast fibers of hemp into the degumming solution for phototreatment. After the phototreatment is completed, take out the hemp fibers. (2) After the light treatment, put the hemp fibers into a container, add ethanolamine solution, heat for 3-6 hours and then take them out; (3) The hemp fibers obtained in step (2) are washed and dried to obtain degummed hemp fibers; The photocatalyst in step (1) is TiO2-CQDs, ZnO-CQDs, or ZnIn2S4.

2. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, In step (1), the photocatalyst is a catalyst that can be excited in the visible light wavelength range.

3. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, In step (1), the amount of photocatalyst used is 3~10g / kg hemp fiber.

4. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, The light treatment time in step (1) is 10~50h.

5. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, The light source used in step (1) during the illumination process is sunlight or simulated sunlight, and simulated sunlight is a light-emitting diode or a xenon lamp.

6. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, In step (1), the solid bath ratio of hemp bast fibers to degumming solution is 1:10~100.

7. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, In step (2), the heating temperature is 80~100℃ and the heating time is 3~6h.

8. The method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to claim 1, characterized in that, In step (2), the solid-liquid ratio of hemp fiber to ethanolamine is 1:15~20.

9. A method for preparing hemp fiber based on photocatalysis and alkali treatment combined degumming according to any one of claims 1-8, characterized in that, The bast fiber of the bast fiber is one of ramie, hemp, apocynum venetum, kenaf, or jute.

Images