A method for degumming industrial hemp fibers with periodate

Abstract

The present invention discloses a method for degumming industrial hemp fibers with periodate, comprising the following steps: placing industrial hemp in a sodium hydroxide alkaline solution for pretreatment to fully swell the fibers; then washing with water until neutral; under acidic conditions with pH = 5 - 6, a periodate and metal ions form an advanced oxidation reaction system to further degum the industrial hemp fibers, and the metal ions are Fe 2+ , Fe 3+ , Cu 2+ or Mn 2+ , the concentration of the metal ions is 1.5 - 3.5 wt%, the concentration of IO4 ‑ is 2.0 - 2.5 wt%, treating at a temperature of 50 - 60 °C for 50 - 60 minutes, and then washing with water; using an oxygen bleaching solution to conduct in-depth degumming and bleaching treatment on the industrial hemp fibers, washing with water, and drying. The process flow of the present invention has the advantages of less chemical reagent consumption, simple steps, short reaction time, less environmental pollution, and lower cost, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of degumming process methods, and in particular to a method for degumming industrial hemp fibers with periodate. Background Art

[0002] Industrial hemp, also known as cannabis sativa L., is considered to be a fiber material with excellent performance because of its excellent air permeability and antibacterial properties. The chemical composition of untreated industrial hemp fibers is complex, consisting of cellulose components and non-cellulose components such as pectin, hemicellulose, and lignin. These non-cellulose components are collectively referred to as gums. Because the content of substances such as pectin and lipid wax in industrial hemp fibers is relatively low, lignin and hemicellulose are the key points of degumming treatment. The content of gums has a great influence on the subsequent textile processing of industrial hemp. Therefore, in order to ensure the smooth progress of the subsequent textile process, it is a crucial step to remove these non-cellulose gum components to obtain relatively pure cellulose fibers.

[0003] Degumming is the process of removing gums from the phloem composite structure. At present, the methods for degumming hemp fibers are mainly divided into three types: biological degumming method, physical degumming method, and chemical degumming method. Biological degumming methods are mainly divided into microbial degumming and bioenzyme degumming. The biological degumming method has less environmental pollution, but the reaction time is generally long, and the price of bioenzymes is expensive. Physical degumming is the process of removing fiber gums only using mechanical processing equipment. The treated fibers are broken, resulting in poor separation and short fiber length. And because the degumming effect is not obvious, it is usually used as a method for fiber degumming pretreatment and is generally used together with other degumming methods. The chemical degumming method is a relatively developed degumming method at present. Traditional alkali degumming is a kind of chemical degumming method and is one of the earlier methods used for degumming, but it has a large amount of alkali consumption, a long reaction time, high energy consumption, and great environmental pollution. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the present invention provides a method for degumming industrial hemp fibers with periodate, which has the advantages of less chemical reagent consumption, simple steps, short reaction time, less environmental pollution, and lower cost.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An embodiment of the present invention provides a method for degumming industrial hemp fibers with periodate, including the following steps:

[0007] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment to fully swell the fibers; then wash with water until neutral;

[0008] S2: Under acidic conditions with pH = 5 - 6, a metal ion and periodate form an advanced oxidation reaction system to further degum industrial hemp fibers. The metal ion is Fe 2+ 、Fe 3+ 、Cu 2+ or Mn 2+ , the concentration of the metal ion is 1.5 - 3.5 wt%, the concentration of IO 4 - is 2.0 - 2.5 wt%, treat at 50 - 60 °C for 50 - 60 minutes, and then wash with water;

[0009] S3: Use an oxygen bleaching solution to deeply degum and bleach industrial hemp fibers, wash with water, and dry.

[0010] The degumming process flow of the hemp fibers in this invention: alkaline solution pretreatment - oxidation degumming treatment with periodate + metal ion system - oxygen bleaching - water washing - drying. It has the characteristics of low cost, high efficiency, and high environmental protection. Periodate can specifically oxidize C2 - C3 of the gum component to produce two adjacent aldehyde groups, and the aldehyde groups can be more easily converted into other functional groups to complete the cleavage and degradation of the macromolecular chain. The added metal ions can activate the oxidation system of the iodate and also have a good degradation effect on the degumming waste liquid.

[0011] In the embodiments of this invention, the concentration of Fe 2+ 、Fe 3+ 、Cu 2+ 、Mn 2+ is 1.5 - 3.5 wt% g / L, and the concentration of IO 4 - is 2.0 - 2.5 wt%. If the concentration of Fe 2+ 、Fe 3+ 、Cu 2+ 、Mn 2+ 、IO 4 - is too low, then the generated oxidation groups are too few and the degumming effect is not obvious. If the concentration of Fe 2+ 、Fe 3+ 、Cu 2+ 、Mn 2+ 、IO 4 - is too high, then the generated oxidation groups are too many, which will damage the fibers. In addition, a large amount of precipitation will be generated, especially Mn 2+ will generate a large amount of red precipitation, and these precipitations will adhere to the fiber surface and are difficult to wash off. The pH value needs to be maintained under acidic conditions to reduce the generation of precipitation. Therefore, this application controls the concentration of Fe 2+ 、Fe 3+ 、Cu 2+ 、Mn2+ The concentration is 1.5 - 3.5 wt% g / L, IO 4 - The concentration is 2.0 - 2.5 wt%, pH = 5 - 6.

[0012] In some embodiments, in step S1, the reagent used to create the alkaline condition is NaOH, with a concentration of 2 - 4 g / L. It is treated in a water bath at 50°C - 60°C for 60 minutes, with a liquor ratio of 1:20 - 30, and washed with water until the pH value of the washing solution is neutral. Through the pretreatment in step S1, in subsequent treatments, chemical reagents can more easily enter the fibers, facilitating the degumming treatment in step S2.

[0013] Preferably, in step S1, industrial hemp is added to water at a liquor ratio of 1:20, with a NaOH concentration of 2 g / L, treated at 60°C for 60 minutes, and washed with water until the pH value of the washing solution is neutral.

[0014] In some embodiments, in step S2, industrial hemp is added to water at a liquor ratio of 1:10 - 30, and the source of Fe 2+ is ferrous sulfate (FeSO 4 .7H 2 O), the source of Fe 3+ is ferric chloride (FeCl 3 ·6H 2 O), the source of Cu 2+ is copper sulfate (CuSO 4 ·5H 2 O), the source of Mn 2+ is manganese chloride (MnCl 2 ·4H 2 O), and the source of IO 4 - is potassium periodate (KIO 4 ).

[0015] Preferably, in step S2, the concentration of metal ions is 1.5 wt%, and the concentration of IO 4 - is 2.0 wt%.

[0016] Preferably, in step S2, the metal ion is Fe 2+ .

[0017] In some embodiments, in step S3, industrial hemp is added to the bleaching solution at a liquor ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 14 g / L, the concentration of Na 2 CO 3 is 2 g / L, the concentration of sodium silicate is 2 g / L, the concentration of sodium sulfite is 1 g / L, treated at 90°C for 100 minutes, washed with water until the pH value is neutral, and dried to the dry state of the fiber.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The degumming process flow of the hemp fiber of the present invention: pretreatment - oxidation degumming treatment with periodate + metal ion system - oxygen bleaching - water washing - drying. It has the characteristics of low cost, high efficiency, and high environmental protection. Periodate can specifically oxidize C2-C3 of the gum component to produce two adjacent aldehyde groups, and the aldehyde groups can be more easily converted into other functional groups to complete the cleavage and degradation of the macromolecular chain. The added metal ions can activate the oxidation system of the iodate and also have a good degradation effect on the degumming waste liquid.

[0020] (2) The periodate + metal ion system is an advanced oxidation reaction. The oxidation groups generated by this system are mainly O 2- and 1 O 2 . These two oxidation groups can quickly combine with the pretreated industrial hemp fiber to break the macromolecular gum chain, generate small molecular chains, and further oxidize to generate H 2 O and CO 2 . And this degumming system also has a good degradation effect on the degumming liquid. This method has a short degumming time, does not require the addition of alkali during the degumming process, the alkali concentration in the wastewater is very low, reducing environmental pollution, and the degumming only requires one step, with a simple process and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 SEM of the hemp fiber treated by the method of Example 1.

[0022] Figure 2 SEM of the hemp fiber treated by the method of Example 2.

[0023] Figure 3 SEM of the hemp fiber treated by the method of Example 3.

[0024] Figure 4 SEM of the hemp fiber treated by the method of Example 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The embodiments of the present invention will be described in detail below. The following described embodiments are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0026] In this article, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs.

[0027] In this text, where a value is described as a range, it should be understood that such disclosure includes the disclosure of all possible sub-ranges within that range, as well as the specific numerical values falling within that range, regardless of whether the specific numerical values or specific sub-ranges are explicitly indicated.

[0028] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods.

[0029] The embodiments of the present invention provide a method for degumming industrial hemp fibers with periodate, comprising the following steps:

[0030] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment to fully swell the fibers; then wash with water until neutral.

[0031] S2: Under acidic conditions with pH = 5 - 6, periodate and metal ions form an advanced oxidation reaction system to further degum industrial hemp fibers. The metal ions are Fe 2+ 、Fe 3+ 、Cu 2+ or Mn 2+ , the concentration of the metal ions is 1.5 - 3.5 wt%, the concentration of IO 4 - is 2.0 - 2.5 wt%, treat at a temperature of 50 - 60 °C for 50 - 60 minutes, and then wash with water.

[0032] S3: Use an oxygen bleaching solution to deeply degum and bleach industrial hemp fibers, wash with water, and dry.

[0033] Non-limiting examples are as follows: In step S2, the pH can be 5, 5.2, 5.4, 5.5, 5.8, 6, etc. In the advanced oxidation reaction system, the concentration of the metal ions can be 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, etc., and the concentration of IO 4 - is 2.0 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.5 wt%, etc.

[0034] In some embodiments, in step S1, the reagent used to create the alkaline condition is NaOH, with a concentration of 2 - 4 g / L, treat in a water bath at 50 °C - 60 °C for 60 minutes, the bath ratio is 1:20 - 30, and wash with water until the pH value of the washing solution is neutral. Non-limiting examples are as follows: The concentration of NaOH can be 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, etc., the water bath temperature can be 50 °C, 52 °C, 54 °C, 56 °C, 60 °C, etc. The bath ratio can be 1:20, 1:25, 1:30, etc.

[0035] In some embodiments, in step S2, industrial hemp is added to water at a bath ratio of 1:10 to 30, and the source of Fe 2+ is ferrous sulfate (FeSO 4 .7H 2 O), the source of Fe 3+ is ferric chloride (FeCl 3 ·6H 2 O), the source of Cu 2+ is copper sulfate (CuSO 4 ·5H 2 O), the source of Mn 2+ is manganese chloride (MnCl 2 ·4H 2 O), and the source of IO 4 - is potassium periodate (KIO 4 ). Non-limiting examples are that the bath ratio can be 1:10, 1:15, 1:20, 1:25, 1:30, etc.

[0036] In some embodiments, in step S3, industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 14 g / L, the concentration of Na 2 CO 3 is 2 g / L, the concentration of sodium silicate is 2 g / L, the concentration of sodium sulfite is 1 g / L, and it is treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the dry state of the fiber.

[0037] The physical properties of the hemp fiber prepared by using the degumming method of the present invention are detected as follows, and the following detection data are obtained: The breaking strength is tested by an LLY-06E type electronic single fiber strength tester, the stretching gauge is 20 mm / min, the number of stretching times is 20 times, and the average value is taken.

[0038] The detection of the residual gum rate refers to the standard GB / T18147.2-2008.

[0039] The detection of whiteness refers to the standard GB / T17644-2008.

[0040] The COD value in the degumming wastewater follows the standard GB11914-1989.

[0041] Example 1

[0042] A method for degumming industrial hemp fiber with periodate includes the following steps:

[0043] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment, and wash it with water until it is neutral;

[0044] The conditions are as follows: Industrial hemp is added to water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 2 g / L, and washed with water until the pH value of the washing solution is neutral.

[0045] S2: Chemical degumming

[0046] Industrial hemp is added to water at a bath ratio of 1:30, and FeCl 3 ·6H 2 O and KIO 4 are added to make the Fe 3+ concentration 1.5 wt%, the IO 4- concentration 2.0 wt%, the pH is adjusted to 5, treated at 60 °C for 50 minutes, and washed with water until the pH value of the washing solution is neutral.

[0047] S3: Oxygen bleaching, then washing with water and drying.

[0048] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the hydrogen peroxide concentration is 14 g / L, the Na 2 CO 3 concentration is 2 g / L, the sodium silicate concentration is 2 g / L, the sodium sulfite concentration is 1 g / L, treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the fiber dry state.

[0049] Example 2

[0050] A method for degumming industrial hemp fibers with periodate, comprising the following steps:

[0051] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment, and wash with water until neutral.

[0052] The conditions are as follows: Industrial hemp is added to water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 2 g / L, and washed with water until the pH value of the washing solution is neutral.

[0053] S2: Chemical degumming

[0054] Industrial hemp is added to water at a bath ratio of 1:30, and FeSO 4 ·7H 2 O and KIO 4 are added to make the Fe 2+ concentration 1.5 wt%, the IO 4 - concentration 2.0 wt%, the pH is adjusted to 5, treated at 60 °C for 50 minutes, and washed with water until the pH value of the washing solution is neutral.

[0055] S3: Oxygen bleaching, then washing with water and drying.

[0056] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 14 g / L, and the concentration of Na 2 CO 3 is 2 g / L, the concentration of sodium silicate is 2 g / L, the concentration of sodium sulfite is 1 g / L. It is treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the dry state of the fiber.

[0057] Example 3

[0058] A method for degumming industrial hemp fibers with periodate, comprising the following steps:

[0059] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment, and wash with water until neutral.

[0060] The conditions are as follows: Industrial hemp is added to water at a bath ratio of 1:20. Under the condition that the concentration of NaOH is 2 g / L, it is treated at 60 °C for 60 minutes, and washed with water until the pH value of the washing solution is neutral.

[0061] S2: Chemical degumming

[0062] Industrial hemp is added to water at a bath ratio of 1:30, and CuSO 4 ·5H 2 O and KIO 4 are added to make the concentration of Cu 2+ 1.5 wt%, and the concentration of IO 4 - is 2.0 wt%. Adjust the pH = 5, treat at 60 °C for 50 minutes, and wash with water until the pH value of the washing solution is neutral.

[0063] S3: Oxygen bleaching, then washing with water and drying.

[0064] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 14 g / L, and the concentration of Na 2 CO 3 is 2 g / L, the concentration of sodium silicate is 2 g / L, the concentration of sodium sulfite is 1 g / L. It is treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the dry state of the fiber.

[0065] Example 4

[0066] A method for degumming industrial hemp fibers with periodate, comprising the following steps:

[0067] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment, and wash with water until neutral.

[0068] The conditions are as follows: Industrial hemp is added to water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 2 g / L, and washed with water until the pH value of the washing solution is neutral.

[0069] S2: Chemical degumming

[0070] Industrial hemp is added to water at a bath ratio of 1:30, and MnCl 2 ·4H 2 O and KIO 4 are added to make the Mn 2+ concentration 1.5 wt%, and the IO 4- concentration 2.0 wt%. The pH is adjusted to 5, treated at 60 °C for 50 minutes, and washed with water until the pH value of the washing solution is neutral.

[0071] S3: Oxygen bleaching, then washing and drying.

[0072] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the hydrogen peroxide concentration is 14 g / L, the Na 2 CO 3 concentration is 2 g / L, the sodium silicate concentration is 2 g / L, the sodium sulfite concentration is 1 g / L, treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the fiber dry state.

[0073] Example 5

[0074] A method for degumming industrial hemp fiber with periodate, comprising the following steps:

[0075] S1: Place industrial hemp in a sodium hydroxide alkaline solution for pretreatment, and wash with water until neutral;

[0076] The conditions are as follows: Industrial hemp is added to water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 2 g / L, and washed with water until the pH value of the washing solution is neutral.

[0077] S2: Chemical degumming

[0078] Industrial hemp is added to water at a bath ratio of 1:30, and FeSO 4 ·7H 2 O and KIO 4 are added to make the Fe 2+ concentration 2.0 wt%, and the IO 4- concentration 2.5 wt%. The pH is adjusted to 5, treated at 60 °C for 50 minutes, and washed with water until the pH value of the washing solution is neutral.

[0079] S3: Oxygen bleaching, then washing and drying.

[0080] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 14 g / L, the concentration of Na 2 CO 3 is 2 g / L, the concentration of sodium silicate is 2 g / L, the concentration of sodium sulfite is 1 g / L, treated at 90 °C for 100 minutes, washed with water until the pH value is neutral, and dried to the fiber dry state.

[0081] It should be noted that: The solutions of the following comparative examples are not prior art, but are only set for comparison with the solutions of the examples and are not a limitation to the present invention.

[0082] Comparative Example 1

[0083] Different from Example 2, in Comparative Example 1, IO 4- .

[0084] Comparative Example 2

[0085] Different from Example 2, in Comparative Example 2, Fe 2+ .

[0086] Comparative Example 3

[0087] Different from Example 2, in Comparative Example 3, step S2 is:

[0088] Industrial hemp is added to water at a bath ratio of 1:30, the Cr 3+ concentration is 1.5 wt% g / L, the IO 4- concentration is 2.0 wt%, adjust pH = 5, treat at a temperature of 60 °C for 50 minutes, and wash with water until the pH value of the washing solution is neutral.

[0089] Other steps are the same as in Example 2.

[0090] Comparative Example 4

[0091] Different from Example 2, in Comparative Example 4, step S2 is:

[0092] Industrial hemp is added to water at a bath ratio of 1:30, the Ca 2+ concentration is 1.5 wt% g / L, the IO 4- concentration is 2.0 wt%, adjust pH = 5, treat at a temperature of 60 °C for 50 minutes, and wash with water until the pH value of the washing solution is neutral.

[0093] Comparative Example 5

[0094] Different from Example 2, in Comparative Example 5, in step S2: Fe 2+ concentration is 1.0 wt%, and the IO 4- concentration is 1.5 wt%.

[0095] Comparative Example 6

[0096] Different from Example 2, in Comparative Example 6, in step S2: Fe 2+ concentration is 3.0 wt%, IO 4- concentration is 1.0 wt%.

[0097] Comparative Example 7

[0098] Different from Example 2, in Comparative Example 7, in step S2: Fe 2+ concentration is 1.0 wt%, IO 4- concentration is 3.0 wt%.

[0099] Comparative Example 8

[0100] Different from Example 2, in Comparative Example 8, in step S2: adjust pH = 10.

[0101] Comparative Example 9

[0102] Different from Example 2, in Comparative Example 9, in step S1: Industrial hemp is added with water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 1 g / L, and washed with water until the pH value of the washing solution is neutral.

[0103] Comparative Example 10

[0104] Different from Example 2, in Comparative Example 10, in step S3:

[0105] In the bleaching solution, the hydrogen peroxide concentration is 7 g / L, Na 2 CO 3 concentration is 1 g / L, the sodium silicate concentration is 1 g / L, the sodium sulfite concentration is 0.5 g / L, and treated at 90 °C for 100 minutes.

[0106] Comparative Example 11

[0107] A method for degumming industrial hemp fiber with periodate, comprising the following steps:

[0108] S1: Pretreat industrial hemp under alkaline conditions and then wash with water;

[0109] The conditions are: Industrial hemp is added with water at a bath ratio of 1:20, treated at 60 °C for 60 minutes under a NaOH concentration of 4 g / L, and washed with water until the pH value of the washing solution is neutral.

[0110] S2: Chemical degumming

[0111] Industrial hemp is added with water at a bath ratio of 1:30, and FeSO 4 .7H 2 O and KIO 4 are added to make Fe 2+Concentration 2.5 wt%, IO 4- The concentration is 3.0 wt%, adjust the pH = 5, treat at 60 °C for 70 minutes, and wash with water until the pH value of the washing solution is neutral.

[0112] S3: Oxygen bleaching, then washing with water and drying.

[0113] The conditions are as follows: Industrial hemp is added to the bleaching solution at a bath ratio of 1:30. In the bleaching solution, the concentration of hydrogen peroxide is 20 g / L, Na 2 CO 3 The concentration of is 5 g / L, the concentration of sodium silicate is 6 g / L, the concentration of sodium sulfite is 4 g / L, treat at 90 °C for 100 minutes, wash with water until the pH value is neutral, and dry to the fiber dry state.

[0114] The residual gum rate (%), breaking strength (cN), whiteness (%), and COD value (mg / L) in the degumming wastewater of Examples 1-5 are shown in Table 1.

[0115] Table 1 Detection data of Examples 1-5

[0116] Detection items Example 1 Example 2 Example 3 Example 4 Example 5 Residual glue rate 9.92 8.71 9.89 8.79 9.24 Breaking strength 25.31 24.39 25.16 28.31 27.54 Whiteness 25.74 25.97 25.86 26.07 25.76 COD value 14841 15179 15115 14524 15978

[0117] It can be seen from Table 1 that for the industrial hemp fiber degumming process method of the present invention, Examples 1-5 are reaction systems composed of periodate and different metal ions. The experimental results show that the above four ions all have an activating effect on periodate and can achieve the effect of degumming. After degumming, the residual gum rate of industrial hemp is 8.71-9.92%, the breaking strength is 24.39-28.31 cN, the whiteness is 25.74-26.07%, the degumming effect is good, the COD value is 14500-16000 mg / L, especially the low COD value of its degumming solution is beneficial to environmental protection, and the COD value of Example 1 is the lowest and the effect is better. Figures 1 - 4 , which are Fe 3+ 、Fe 2+ 、Cu 2+ 、Mn 2+ Scanning electron microscope fiber diagrams after degumming treatment with the system composed of periodate, respectively. It can be seen from Figure 1 that after degumming treatment with the system composed of Fe 3+ and periodate, the gum on the surface of industrial hemp is basically removed, but there is still some residual gum on its surface. It can be seen from Figure 2 that after degumming treatment with the system composed of Fe 2+ and periodate, the gum on the surface of industrial hemp has been removed very cleanly, and the fiber surface is very smooth. It can be seen from Figure 3 that after degumming treatment with the system composed of Cu 2+After degumming with the system composed of periodate, the gum on the fiber surface is removed relatively cleanly, and the fiber is relatively smooth. However, there are still some bundle fibers that are not separated between the fibers. From Figure 4 It can be seen that after degumming with the system composed of Mn 2+ and periodate, the situation of the gum on the fiber surface is Figure 1 not much different. It can be clearly observed that the bundle fibers are separated, and the single fibers are clearly visible. Therefore, considering the residual gum rate, breaking strength, whiteness, and scanning electron micrograph, the effect of Example 2 is the best.

[0118] The residual gum rate (%), breaking strength (cN), whiteness (%), and COD value (mg / L) in the degumming wastewater of Example 2 and Comparative Examples 1-11 are shown in Table 2.

[0119] Table 2 Detection data of Example 2 and Comparative Examples 1-11

[0120]

[0121] From Example 2 and Comparative Example 1, it can be seen that when IO 4 - is not added and other conditions remain unchanged, the residual gum rate of Comparative Example 1 is 15.49%, the breaking strength is 31.47 cN, the whiteness is 24.20%, and the COD value is 16836 mg / L. By comparison, it can be seen that the degumming effect of Comparative Example 1 is poor with a high residual gum rate of the fiber after degumming, indicating that IO 4 - in the system can enhance the catalytic effect. The reason why the degumming and bleaching effect of Example 2 is better than that of Comparative Example 1 is that only Fe 2+ is added to this system, which is incomplete, and the groups capable of effective oxidation generated are limited. However, the addition of IO 4 - makes the system complete and can generate a large number of effective O 2- and 1 O 2 oxidation groups, enabling the reaction to proceed normally.

[0122] From Example 2 and Comparative Example 2, it can be seen that when Fe 2+ is not added and other conditions remain unchanged, the residual gum rate of Comparative Example 2 is 17.16%, the breaking strength is 38.19 cN, the whiteness is 24.04%, and the COD value is 17271 mg / L. By comparison, it can be seen that the degumming effect of Comparative Example 2 is not as good as that of Example 2. The reason is that the metal ion Fe 2+ plays a great role in the periodate oxidation degumming system. Fe 2+ and IO 4 -The formed oxidation system generates O with extremely strong oxidation activity 2- and 1 O 2 to oxidize and decompose hemp fibers. If Fe 2+ is not added, it is difficult to form the system, the oxidation effect weakens, the degumming effect is not ideal, and the residual gum rate increases.

[0123] It can be seen from Example 2 and Comparative Example 3 that when the metal ions are replaced with Cr 3+ ions with the same concentration and other conditions remain unchanged, the residual gum rate of Comparative Example 3 is 10.74%, the breaking strength is 28.28 cN, the whiteness is 24.04%, and the COD value is 15891 mg / L. By comparison, it can be seen that there is a certain gap in the residual gum rate and breaking strength between Comparative Example 3 and Example 2. Without considering Cr 3+ as a periodate + metal ion hemp degumming system, since Cr(III) is a class III carcinogen, in the subsequent textile production and application of fibers, if not properly treated, there may be potential safety hazards to human beings.

[0124] It can be seen from Example 2 and Comparative Example 4 that when the metal ions are replaced with Ca 2+ ions with the same concentration and other conditions remain unchanged, the residual gum rate of Comparative Example 4 is 13.82%, the breaking strength is 34.76 cN, the whiteness is 24.78%, and the COD value is 16714 mg / L. By comparison, it can be seen that the values of Comparative Example 4 are not as good as those of Example 2. The reason may be that in the periodate + metal ion degumming system, the catalytic effect of Ca 2+ ions on IO 4 - is very weak and cannot achieve a good catalytic effect. Therefore, the generated oxidation groups and the groups that can act on degumming are few, and the reduction of the residual gum rate and the increase of the breaking strength also illustrate this point.

[0125] It can be seen from Example 2 and Comparative Example 5 that Comparative Example 5 reduces the dosage of IO 4 - and Fe 2+ , and other conditions remain unchanged. The residual gum rate of Comparative Example 5 is 12.96%, the breaking strength is 36.43 cN, the whiteness is 24.48%, and the COD value is 19435 mg / L. By comparison, it can be seen that after degumming in Comparative Example 5, the residual gum rate of the fiber increases, its strength also increases greatly, and the whiteness is also poor. The reason is that the amount of IO 4 - and Fe 2+ added is too small, and the groups that can effectively act on the oxidation of industrial hemp fiber gum are too few, so that the gum cannot be effectively removed, which is also the reason for the increase of the breaking strength and the residual gum rate and affects the whiteness of the fiber.

[0126] It can be seen from Example 2 and Comparative Example 6 that in Comparative Example 6, the dosages of IO 4 - and Fe 2+ were changed, and the proportion of Fe 2+ was increased. The residual gum rate of Comparative Example 6 was 14.21%, the breaking strength was 28.72 cN, the whiteness was 21.79%, and the COD value was 17982 mg / L. It can be seen by comparison that when the proportion of Fe 2+ increases, both the residual gum rate and the breaking strength of the fiber increase significantly. This is because there is an excess of Fe 2+ in the system, there are too many side reactions in the system, and too few groups act on the gum part. At the same time, a large amount of colored precipitate will be generated, coloring the fiber and affecting the whiteness and COD value.

[0127] It can be seen from Example 2 and Comparative Example 7 that in Comparative Example 7, the dosages of IO 4 - and Fe 2+ were changed, and the proportion of IO 4 - was increased. The residual gum rate of Comparative Example 7 was 13.78%, the breaking strength was 26.93 cN, the whiteness was 23.97%, and the COD value was 16862 mg / L. It can be seen by comparison that when the proportion of IO 4 - increases, both the residual gum rate and the breaking strength of the fiber increase significantly. This is because there is an excess of IO 4 - in the system, the oxidation groups that can react with Fe 2+ and have an effective effect on the gum are limited, and the excess of IO 4 - will accelerate the reaction, and some groups are consumed before they have time to react with the gum. There are too many side reactions in the system, resulting in an increase in the residual gum rate and the breaking strength.

[0128] It can be seen from Example 2 and Comparative Example 8 that the pH was adjusted to be alkaline, and periodate + Fe 2+ was reacted under alkaline conditions, and other conditions remained unchanged. The residual gum rate of Comparative Example 8 was 12.71%, the breaking strength was 31.14 cN, the whiteness was 24.89%, and the COD value was 16897 mg / L. It can be seen by comparison that the residual gum rate and the breaking strength of Comparative Example 8 are significantly greater than those of Example 2. This shows that the oxidation effect of this system is limited under alkaline conditions. The reason may be that there are many side reactions under alkaline conditions, generating a large amount of precipitate, and the number of groups that can be applied to the degumming part becomes smaller. This is also the reason why the whiteness under alkaline conditions is less than that of Example 2.

[0129] It can be seen from Example 2 and Comparative Example 9 that when the concentration of the pretreatment alkali solution decreases and other conditions remain unchanged, the residual gum rate of Comparative Example 9 is 11.07%, the breaking strength is 34.14 cN, the whiteness is 23.66%, and the COD value is 14994 mg / L. Through comparison, it can be seen that the residual gum rate and breaking strength of Comparative Example 9 increase, while the whiteness and COD value decrease. This is because an increase in the amount of alkali will reduce the residual gum rate and breaking strength, increase the whiteness, and the decrease in the COD value is due to the decrease in the alkali consumption. However, considering the comprehensive indicators such as the residual gum rate, breaking strength, whiteness, and COD in the degumming wastewater, the effect of Example 2 is better.

[0130] It can be seen from Example 2 and Comparative Example 10 that when the concentration of the oxygen bleaching solution is reduced and other conditions remain unchanged. The residual gum rate of Comparative Example 10 is 9.24%, the breaking strength is 26.19 cN, the whiteness is 24.43%, and the COD value is 15062 mg / L. Through comparison, it can be seen that there is a large difference in whiteness between Comparative Example 10 and Example 2, which indicates that in the periodate + metal ion degumming system, the concentration of the oxygen bleaching solution has a greater impact on whiteness.

[0131] It can be seen from Example 2 and Comparative Example 11 that in Comparative Example 11, the amount of chemical reagents increases and the degumming time in Step S2 increases. The residual gum rate of Comparative Example 11 is 8.43%, the breaking strength is 22.14 cN, the whiteness is 26.42%, and the COD value is 15197 mg / L. Through comparison, it can be seen that although the residual gum rate of the fiber after degumming in Comparative Example 9 is low, the decrease in strength is more obvious. The reason is that the increase in the amount of chemical drugs and the extension of time during the degumming process cause great damage to the ramie fiber.

[0132] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0133] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for degumming industrial hemp fiber using periodate, characterized in that: The steps include: S1: placing industrial hemp in an alkaline solution of sodium hydroxide for pretreatment to fully swell the fibers; then washing with water until neutral; S2: Under the acidic condition of pH=5-6, periodate and metal ions form an advanced oxidation reaction system to further degumming industrial hemp fiber. The metal ions are Fe 2+ , Fe 3+ , Cu 2+ or Mn 2+ , the concentration of metal ions is 1.5-3.5wt%, IO4 - The concentration is 2.0-2.5wt%, the temperature is 50-60℃, the treatment time is 50-60 minutes, and then washed with water; S3: The industrial hemp fiber is subjected to in-depth degumming and bleaching treatment with oxygen bleaching liquid, followed by washing and drying.

2. A method for degumming industrial hemp fiber using periodate according to claim 1, characterized in that: In step S1, the reagent used to create alkaline conditions is NaOH, with a concentration of 2-4 g / L, treated in a water bath at 50°C-60°C for 60 minutes, with a bath ratio of 1:20-30, and washed with water until the pH value of the washing solution is neutral.

3. A method for degumming industrial hemp fiber using periodate according to claim 2, characterized in that: In step S1, industrial hemp is added with water at a bath ratio of 1:20, the NaOH concentration is 2 g / L, treated at 60° C. for 60 minutes, and washed with water until the pH value of the washing solution is neutral.

4. A method for degumming industrial hemp fiber using periodate according to claim 1, characterized in that: In step S2, industrial hemp is added with water at a bath ratio of 1:10-30, Fe 2+ The source is ferrous sulfate, Fe 3+ The source is ferric chloride, Cu 2+ The source is copper sulfate, Mn 2+ The source is manganese chloride, IO4 - The source is potassium periodate.

5. A method for degumming industrial hemp fiber using periodate according to claim 1 or 4, characterized in that: The concentration of metal ions is 1.5wt%, IO4 - The concentration is 2.0wt%.

6. A method for degumming industrial hemp fiber using periodate according to claim 5, characterized in that: The metal ion is Fe 2+ .

7. The method for degumming industrial hemp fiber using periodate according to claim 1, characterized in that: In step S3, industrial hemp is added to a bleaching solution at a bath ratio of 1:30, wherein the concentration of hydrogen peroxide is 14 g / L, the concentration of Na2CO3 is 2 g / L, the concentration of sodium silicate is 2 g / L, and the concentration of sodium sulfite is 1 g / L. The bleaching solution is treated at 90°C for 100 minutes, washed with water until the pH value is neutral, and dried to a fiber dry state.

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