A method for degumming hemp fiber using ethanolamine in solid state

Abstract

The invention belongs to the technical field of textile processing, and specifically relates to a method for degumming solid hemp fibers with ethanolamine. The method comprises the following steps: mixing the hemp fibers after impurities removal with an ethanolamine solvent, and heating them for 5 to 7 hours; wherein the bath ratio of the hemp fibers to the ethanolamine solvent is 1:(2.5 to 4); washing, filtering, and drying the treated hemp fibers to obtain degummed hemp fibers, and recovering the degumming waste liquid after filtration; subjecting the degumming waste liquid to vacuum rotary evaporation to remove ethanol and water, and using the purified degumming waste liquid as the next batch of degumming solvent to achieve waste liquid recycling. The present invention uses only ethanolamine as a solvent to perform solid hemp fiber degumming with a high bath ratio, which can greatly reduce the amount of chemicals used and the volume of reaction equipment, and reduce the degumming cost; on the other hand, the ethanolamine solvent used in the present invention can be reused, further reducing the degumming cost and reducing the environmental burden.

Description

Technical Field

[0001] The invention belongs to the technical field of textile processing, and particularly relates to a method for degumming ramie fibers using ethanolamine in a solid state. Background Art

[0002] Hemp fiber refers to fibers obtained from various hemp plants, primarily ramie, jute, ramie, flax, apocynum venetum, and kenaf. Hemp plants are easy to cultivate, grow rapidly, are highly adaptable, are less susceptible to pests and diseases, are tolerant to salinity and drought, have low soil requirements, and are extremely adaptable, allowing cultivation in most regions of my country. Due to its excellent UV resistance, moisture absorption and breathability, antistatic properties, and antibacterial properties, hemp fiber is used in many fields, such as construction, papermaking, and textiles. Since hemp fiber is composed of cellulose bonded with colloids such as hemicellulose and lignin, removing these colloids is a key prerequisite for obtaining high-quality hemp fiber.

[0003] However, the current traditional alkali degumming process for producing hemp fiber suffers from long process steps, high water and energy consumption, and significant wastewater pollution from degumming, severely restricting the development and utilization of hemp fiber. Therefore, there is an urgent need to develop a clean and efficient hemp fiber degumming method. Organic solvents can effectively dissolve lignin and hydrolyze some hemicellulose, achieving efficient separation of biomass components. More importantly, the wastewater from organic solvent degumming can be recycled, reducing chemical consumption during the degumming process and the generation of post-degumming wastewater pollution.

[0004] In recent years, chemical degumming has seen some breakthroughs, with traditional organic solvents beginning to partially replace the use of acids, bases, and oxidants. For example, Chinese patent publication number CN103266358A uses a solution consisting of a high proportion of an alcoholic organic solvent, a small amount of water, and an acid-base degumming agent to degumming hemp, with a bath ratio of 1:10-30. Chinese patent CN110284200A also uses a deep eutectic solvent composed of an amide or polyol and choline chloride, with a mass ratio of 1:20-50. While organic solvents can be recycled, degumming methods using low bath or mass ratios increase solvent recovery costs. Furthermore, the large reaction volume requires significant equipment investment. Summary of the Invention

[0005] Based on the problems raised in the background art, the technical problem to be solved by the present invention is to provide a solid-state hemp degumming method based on an ethanolamine organic solvent to solve at least one of the problems in the background art. The method has a large liquor ratio, a small reaction volume, a relatively simple process, and the reagents can be reused. The technical solution adopted is:

[0006] A method for solid-state hemp fiber degumming using ethanolamine, comprising the following steps:

[0007] (1) mixing the impurity-removed hemp fiber with an ethanolamine solvent and heating the mixture for 5 to 7 hours; wherein the bath ratio of the hemp fiber to the ethanolamine solvent is 1:(2.5 to 4);

[0008] (2) washing, filtering, and drying the treated hemp fibers to obtain degummed hemp fibers, and recovering the waste liquid after filtration;

[0009] (3) The degumming waste liquid is subjected to vacuum rotary evaporation to remove ethanol and water, and the degumming waste liquid purified by vacuum rotary evaporation is used as the degumming solvent for the next batch, thereby realizing the recycling of the waste liquid.

[0010] Preferably, in step (1), the heating temperature is 90-100°C.

[0011] Preferably, in step (1), the ethanolamine solvent is anhydrous ethanolamine reagent.

[0012] Preferably, in step (2), the washing liquid is a mixture of equal volumes of ethanol and water at 50-70° C., and the washing liquid is used to rinse the hemp fibers, the waste liquid is recovered, and then the hemp fibers are rinsed with cold water.

[0013] Preferably, in step (2), the drying temperature is 50-60° C. and the drying time is 2-3 hours.

[0014] Preferably, in step (3), the vacuum rotary evaporation temperature is 60-70° C. and the vacuum degree is 50 mbar.

[0015] Compared with the prior art, the present invention is beneficial in that:

[0016] The present invention uses only ethanolamine as a solvent to carry out high-bath ratio solid-state hemp fiber degumming, which can greatly reduce the amount of chemicals used and the volume of reaction equipment, thereby lowering the degumming cost. On the other hand, the ethanolamine solvent used in the present invention can be reused, further reducing the degumming cost and alleviating the environmental burden. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The following are scanning electron microscope comparison pictures of the hemp fibers after degumming of industrial hemp used in Examples of the present invention and Comparative Example 1 and the hemp fibers after degumming obtained in Example 2.

[0018] Figure 2 This is a scanning electron microscope comparison picture of the degummed kenaf fiber obtained in Example 3 of the present invention and the traditional alkaline degummed industrial hemp fiber obtained in Comparative Example 1. DETAILED DESCRIPTION

[0019] The accompanying drawings are for illustrative purposes only. To better illustrate the present embodiment, some components in the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent the actual dimensions of the product.

[0020] For those skilled in the art, some well-known structures and their descriptions in the drawings may be omitted, and therefore, they should not be understood as limiting the present invention.

[0021] The ethanolamine used in the present invention is anhydrous monoethanolamine (C2H7NO) reagent, and there is no particular restriction on the sources of other raw materials, as long as they are commercially available.

[0022] Example 1

[0023] A method for degumming hemp fibers using ethanolamine in a solid state comprises the following steps:

[0024] (1) 1.5 g of industrial hemp fiber was mixed with 3.75 mL of ethanolamine solvent (i.e., the bath ratio of hemp fiber to ethanolamine solvent was 1:2.5), and heated in a water bath at 100 ° C for 7 h. Then, the fiber was washed with 15 ml of an equal volume of ethanol / water mixture at about 50 ° C (i.e., the volume of ethanol and water was 7.5 ml respectively). After washing, the fiber was filtered and the filtrate was collected. The hemp fiber was then washed with tap water and dried at 60 ° C for 3 h to obtain degummed hemp fiber.

[0025] (2) The collected filtrate was subjected to vacuum rotary evaporation to remove ethanol and water. The purified degumming waste liquid was used as the next batch of degumming solvent and was recycled 5 times. The vacuum rotary evaporation temperature was 70°C and the vacuum degree was 50 mbar.

[0026] Example 2:

[0027] A method for degumming hemp fibers using ethanolamine in a solid state comprises the following steps:

[0028] (1) 1.5 g of industrial hemp fiber was mixed with 5 mL of ethanolamine solvent (i.e., the bath ratio of hemp fiber to ethanolamine solvent was 1:3.33), heated in a water bath at 100 °C for 7 h, and then washed with an equal volume of 18 mL of ethanol / water mixture at about 50 °C. After washing, the mixture was filtered and the filtrate was collected. The hemp fiber was then washed with tap water and dried at 60 °C for 3 h to obtain degummed hemp fiber.

[0029] (2) The collected filtrate was subjected to vacuum rotary evaporation to remove ethanol and water. The purified degumming waste liquid was used as the next batch of degumming solvent and was recycled 5 times. The vacuum rotary evaporation temperature was 70°C and the vacuum degree was 50 mbar.

[0030] like Figure 1 As shown, Figure a on the left is a scanning electron microscope picture of the hemp fiber after the industrial hemp is removed from the impurities, and Figure b is a scanning electron microscope picture of the degummed hemp fiber obtained in Example 2. It can be seen from the comparison results that after degumming by the method of the present invention, the colloid is removed, so that the fiber is dispersed.

[0031] Example 3:

[0032] A method for degumming hemp fibers using ethanolamine in a solid state comprises the following steps:

[0033] (1) 1.5 g of kenaf fiber was mixed with 6 mL of ethanolamine solvent (i.e., the bath ratio of kenaf fiber to ethanolamine solvent was 1:4), and heated in a water bath at 90 °C for 7 h. The fiber was then washed with an equal volume of 20 mL of ethanol / water at about 50 °C. After washing, the fiber was filtered and the filtrate was collected. The kenaf fiber was then washed with tap water and dried at 60 °C for 3 h to obtain degummed kenaf fiber.

[0034] (2) The collected filtrate was subjected to vacuum rotary evaporation to remove ethanol and water. The purified degumming waste liquid was used as the next batch of degumming solvent and was recycled 5 times. The vacuum rotary evaporation temperature was 70°C and the vacuum degree was 50 mbar.

[0035] Comparative Example 1

[0036] The traditional chemical alkaline degumming process is used to degumming industrial hemp. The traditional chemical alkaline degumming process specifically includes the following steps:

[0037] 0.3 g of NaOH was added to 30 mL of deionized water to prepare an alkali boiling solution; 1.5 g of industrial hemp fiber was placed in the alkali boiling solution and heated in a water bath at 100° C. for 7 h. The hemp fiber was collected by filtration, and then washed with 15 mL of an equal volume mixture of ethanol and water, and then washed with tap water. After drying, the degummed hemp fiber was obtained.

[0038] like Figure 2 As shown, Figure c is a scanning electron microscope image of the degummed kenaf fiber obtained in Example 3, and Figure d is a scanning electron microscope image of the traditional alkaline degummed industrial hemp fiber obtained in Comparative Example 1. From the comparison results, it can be seen that the fiber obtained in Example 3 is finer.

[0039] Chemical composition and performance test:

[0040] Fineness test method: Refer to GB / T 6100-2007 "Test method for linear density of cotton fibers - Mid-section weighing method" to test the fineness of degummed industrial hemp fibers.

[0041] Test method for bundle fiber strength: Refer to GB / T 5882-1986 "Test method for breaking strength of ramie bundle fibers" to test the strength of degummed industrial hemp fibers.

[0042] Test method for residual rubber rate: Refer to GB 5889-1986 "Quantitative analysis method of chemical composition of ramie" to test the residual rubber rate of degummed industrial hemp fiber.

[0043] The chemical composition and properties of the degummed flax fibers obtained in Examples 1-3 and Comparative Example 1 were tested according to the above test methods and compared with the untreated raw flax fibers after impurity removal. The results are shown in Tables 1-2.

[0044] Table 1 is a comparison of the chemical composition of the degummed hemp fibers and the original hemp fibers obtained in Examples 1-2 and Comparative Example 1.

[0045]

[0046] Table 2 shows the performance test results comparison

[0047]

[0048] From Tables 1 and 2, we can see that:

[0049] (1) By comparing the chemical composition and fiber properties of Examples 1-3 and Comparative Example 1, it can be seen that the ethanolamine reagent in Examples 1-3 is easier to remove lignin, while the hemicellulose removal efficiency is lower than that of the alkali boiling reagent in Comparative Example 1. However, the fiber properties obtained in Example 1 (4.35 dtex and 3.52 cN / dtex), the cellulose properties obtained in Example 2 (4.21 dtex and 3.75 cN / dtex), and the fiber properties obtained in Example 3 (3.99 dtex and 5.31 cN / dtex) are better than those of the fiber in Comparative Example 1 (6.42 dtex and 2.69 cN / dtex).

[0050] (2) By comparing the raw material usage of the degumming processes of Examples 1 and 2 of the present invention and the traditional alkaline degumming process of Comparative Example 1, it can be seen that: compared with the traditional chemical alkaline degumming process which requires the use of a large amount of environmentally harmful chemicals, the method provided by the present invention can greatly reduce the amount of harmful chemicals used, thereby alleviating the environmental burden. In addition, the present invention can filter and collect the degumming waste liquid, and after vacuum rotary evaporation to remove ethanol and water, it can be reused, thereby reducing costs.

[0051] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for solid hemp fiber degumming using ethanolamine, characterized in that: The method comprises the following steps: (1) Mixing the impurity-removed hemp fiber with an ethanolamine solvent and heating it for 5 to 7 hours; wherein the bath ratio of the hemp fiber to the ethanolamine solvent is 1:2.5 to 4; wherein the heating temperature is 90 to 100° C.; wherein the ethanolamine solvent is anhydrous ethanolamine reagent; (2) washing, filtering and drying the treated hemp fibers to obtain degummed hemp fibers, and recovering the degumming waste liquid after filtration; wherein the washing liquid is a mixed liquid of equal volumes of ethanol / water at 50 to 70° C., and the hemp fibers are rinsed with the washing liquid, and the waste liquid is collected, and then the hemp fibers are rinsed with cold water; (3) The degumming waste liquid is subjected to vacuum rotary evaporation to remove ethanol and water, and the degumming waste liquid purified by vacuum rotary evaporation is used as the degumming solvent for the next batch, thereby realizing the recycling of the waste liquid.

2. The method for solid hemp fiber degumming using ethanolamine according to claim 1, characterized in that: In the step (2), the drying temperature is 50-60° C. and the drying time is 2-3 h.

3. The method for solid hemp fiber degumming using ethanolamine according to claim 1, characterized in that: In the step (3), the vacuum rotary evaporation temperature is 60-70° C. and the vacuum degree is 50 mbar.

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