Method for preparing biomass carbon aerogel based on waste leather scrap hydrolysate
By treating waste leather chips twice and using PVA and glucose for coated carbonization, biomass carbon aerogel was prepared by low-temperature hydrothermal method, which solved the problem of skeleton collapse caused by high-temperature carbonization, and achieved efficient utilization of resources and excellent performance of materials.
Patent Information
- Application Number
- CN202510268290.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-07
- Publication Date
- 2025-06-27
AI Technical Summary
The existing biomass carbon aerogels are prone to collapse of the skeleton structure during high-temperature carbonization, and traditional treatment methods cannot effectively utilize waste leather chip resources, resulting in waste of resources and environmental pollution.
By treating waste leather chips twice, hydrolysates CFs were obtained, and PVA assisted crosslinking and glucose coated carbonization was used to prepare biomass carbon aerogels by low-temperature hydrothermal method to avoid structural collapse caused by high-temperature carbonization.
This method successfully retains the three-strand helical structure and functional groups of waste leather chips. The prepared biomass carbon aerogel has excellent mechanical properties and electromagnetic absorption properties, avoiding resource waste and environmental pollution.
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Figure CN120208190A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of the preparation of biomass-based carbon aerogel materials, and particularly relates to a method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate. Background Art
[0002] Biomass carbon aerogel is a porous carbon material with a three-dimensional network structure derived from biomass materials. Due to its wide source, good biocompatibility, biodegradability and other advantages, biomass carbon aerogel has become a major research direction in the fields of electromagnetic shielding and electromagnetic wave absorption of carbon aerogel. Researchers mainly optimize the performance of biomass carbon aerogel in two ways: one is to construct a conductive path in its internal network structure to enhance the conductive loss of electromagnetic waves; the other is to improve the impedance matching by carbonization, so as to realize the light weight of the absorbing material and endow it with the advantages of low density, high specific surface area and porosity, high conductivity, low thermal conductivity, etc. In addition, the porous structure inside the carbon aerogel causes multiple reflections of the incident electromagnetic waves between the pore walls, thus effectively dissipating the electromagnetic waves.
[0003] The most common preparation method of biomass carbon aerogel is the high-temperature carbonization method. The high-temperature carbonization method calcines the aerogel under a high-temperature and high-pressure environment above 700 °C to carbonize it; the carbon aerogel prepared by this method has the advantages of high specific surface area, excellent conductivity, high thermal stability, low thermal conductivity, etc., but also has the disadvantages of too high graphitization degree and easy collapse of the skeleton structure. When preparing biomass carbon aerogel (HTC) by the low-temperature hydrothermal method, the reaction temperature is usually 130 - 250 °C. At this temperature, the biomass fibers after hydrothermal carbonization can retain part of the fiber structure and the functional groups on the fiber surface, so they have excellent mechanical properties. In addition, the retained functional groups can provide reaction sites for subsequent chemical reactions. By adjusting the precursor, template or reaction conditions, the pore diameter of the obtained nano-microstructure can be accurately controlled. The hydrogel prepared by the low-temperature hydrothermal method can obtain biomass carbon aerogel with excellent mechanical properties after freeze-drying.
[0004] A large amount of waste leather shavings will be generated during the leather production process. The traditional treatment method is to incinerate or landfill the waste leather shavings, which not only causes waste of collagen resources, but also causes environmental pollution. Waste leather shavings are mainly composed of CFs, and the triple helix structure inside it endows it with excellent mechanical properties. In addition, there are a large number of active groups (such as amino groups, carboxyl groups, etc.) on the surface of CFs, which can not only provide reaction active sites, but also form dipoles to generate polarization loss to electromagnetic waves, making it a good matrix material in the electromagnetic field. Summary of the Invention
[0005] The object of the present invention is to provide a method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate, and the biomass carbon aerogel has good mechanical properties and high electromagnetic absorption properties.
[0006] The technical solution adopted by the present invention is a method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate, which is specifically implemented according to the following steps: Step 1, subject the waste leather scraps to two hydrolyses to obtain waste leather scraps hydrolyzate; Step 2, use PVA for auxiliary cross-linking, and at the same time use glucose to coat and carbonize the waste leather scraps hydrolyzate to obtain biomass carbon aerogel.
[0007] The characteristics of the present invention also lie in that In Step 1, specifically: Add the waste leather scraps and H2SO4 into deionized water, stir for the first hydrolysis, filter by suction, and refrigerate the obtained primary hydrolysis product; add the primary hydrolysis product and H2SO4 into deionized water, stir, add ammonia water to adjust the pH of the hydrolyzate after mixing evenly to 7, filter by suction, and refrigerate the obtained product to obtain waste leather scraps hydrolyzate CFs.
[0008] The stirring time is 3 - 6 h for both times.
[0009] The mass ratio of the waste leather scraps, the H2SO4 added in the first hydrolysis, the deionized water added in the first hydrolysis, the H2SO4 added in the second hydrolysis, and the deionized water added in the second hydrolysis is 10 - 25:10 - 20:200 - 300:10 - 20:200 - 300.
[0010] In Step 2, specifically: Step 2.1, dissolve the waste leather scraps hydrolyzate CFs in a PVA solution, mix evenly to obtain a CFs solution uniformly coated with PVA; Step 2.2, dissolve glucose in the CFs solution, stir to obtain a uniformly dispersed modified CFs blend dispersion; Step 2.3, place the modified CFs blend dispersion in a high-pressure reaction kettle for hydrothermal reaction to obtain waste leather scraps hydrolyzate CFs / Glc gel. Then, pre-freeze the waste leather scraps hydrolyzate CFs / Glc gel at -18~-40 °C for 12 - 24 h, and finally place it in a freeze dryer for freeze drying to obtain biomass carbon aerogel.
[0011] In Step 2.3, the hydrothermal reaction temperature is 180 °C, and the hydrothermal reaction time is 3 - 24 h.
[0012] In Step 2.3, the freeze-drying time is 48 - 72 h, and the freeze-drying temperature is -50~-80 °C.
[0013] The beneficial effects of the present invention are as follows: In the method of the present invention, waste leather shavings hydrolyzate CFs are selected as the biomass raw material, and biomass materials such as Glc and PVA are introduced to coat CFs, and a green and environmentally friendly biomass carbon aerogel is prepared by a low-temperature hydrothermal method. Among them, the low-temperature hydrothermal method can retain the triple helix structure inside the collagen fiber, avoiding the problem of framework collapse caused by high-temperature carbonization. This enables the carbon aerogel to have excellent mechanical properties and wave absorption stability. At the same time, this method also retains some functional groups on the surface of the collagen fiber, which is beneficial to subsequent further modification. In addition, the carbon shell layer formed by glucose has a loose porous structure and excellent structural stability. This structure can improve the impedance matching ability of the carbon aerogel and endow it with certain electromagnetic absorption properties. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a test result diagram of the electromagnetic shielding performance of the carbon aerogel prepared in Example 1; Figure 2 It is an electromagnetic shielding parameter diagram of the carbon aerogel prepared in Example 1; Figure 3 It is an SEM diagram of the carbon aerogel prepared in Example 1; Figure 4 It is a stress-strain curve diagram of the carbon aerogel prepared in Example 1. DETAILED DESCRIPTION OF THE INVENTION
[0015] The present invention will be described in detail below with reference to the drawings and specific embodiments.
[0016] The method for preparing a biomass carbon aerogel based on waste leather shavings hydrolyzate of the present invention involves subjecting CFs to low-temperature hydrothermal treatment, introducing PVA for auxiliary cross-linking, and simultaneously using Glc to coat and carbonize CFs, ultimately obtaining a biomass carbon aerogel that retains the triple helix structure of CFs and some functional groups are not destroyed; this method avoids problems such as the easy collapse of the framework after high-temperature carbonization of the biomass aerogel, enabling it to have excellent mechanical properties and wave absorption stability.
[0017] Specifically, it is implemented according to the following steps: Step 1, prepare waste leather shavings hydrolyzate; specifically: Add waste leather shavings and H2SO4 into deionized water, stir for 3 - 6 h for the first hydrolysis, perform suction filtration, and refrigerate the obtained primary hydrolysis product; add the primary hydrolysis product and H2SO4 into deionized water, stir for 3 - 6 h, add ammonia water to adjust the pH of the hydrolyzate after mixing evenly to 7, perform suction filtration, and refrigerate the obtained product to obtain waste leather shavings hydrolyzate CFs; The mass ratio of waste leather scraps, H2SO4 added during the first hydrolysis, deionized water added during the first hydrolysis, H2SO4 added during the second hydrolysis, and deionized water added during the second hydrolysis is 10 - 25:10 - 20:200 - 300:10 - 20:200 - 300; The waste leather scraps are hydrolyzed twice to ensure complete hydrolysis; Step 2: Prepare the biomass carbon aerogel from the waste leather scrap hydrolysate, specifically: Step 2.1: Dissolve the waste leather scrap hydrolysate CFs in the PVA solution and mix evenly to obtain a CFs solution uniformly coated with PVA; The mass - to - volume ratio of the waste leather scrap hydrolysate CFs to the PVA solution is 1 - 5 g:30 - 35 mL; Step 2.2: Dissolve glucose (Glc) in the CFs solution and obtain a uniformly dispersed modified CFs blend dispersion through magnetic stirring; The mass - to - volume ratio of glucose to the CFs solution is 1 - 5 g:35 mL; Step 2.3: Place the modified CFs blend dispersion in a high - pressure reactor for hydrothermal reaction. The hydrothermal reaction temperature is 180 °C, and the hydrothermal reaction time is 3 - 24 h to obtain the waste leather scrap hydrolysate CFs / Glc gel. Then, pre - freeze the waste leather scrap hydrolysate CFs / Glc gel at - 18~ - 40 °C for 12 - 24 h, and finally place it in a freeze - dryer for freeze - drying for 48 - 72 h at a freeze - drying temperature of - 50~ - 80 °C to obtain the biomass carbon aerogel.
[0018] The present invention first uses waste leather scraps and sulfuric acid (H2SO4) as raw materials to prepare CFs through acid hydrolysis reaction; then introduces raw materials such as PVA and Glc, and through a simple hydrothermal reaction, pre - cross - links and coats them on the surface of CFs to obtain a blend dispersion; then carbonizes through low - temperature hydrothermal carbonization method to obtain a hydrogel; finally, prepares the biomass carbon aerogel through freeze - drying. This method not only realizes the resource utilization of leather waste leather scraps but also provides a new idea for the preparation of carbon aerogels.
[0019] Example 1 The method for preparing the biomass carbon aerogel based on the waste leather scrap hydrolysate of the present invention is specifically as follows: Step 1: Prepare the waste leather scrap hydrolysate; The preparation of waste leather scraps hydrolyzate fibers requires two hydrolysis steps: Add 15 g of waste leather scraps and 10 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 4 h, filter the first hydrolyzate after mixing evenly, and refrigerate the obtained product; For the second hydrolysis, add the product obtained from the first hydrolysis and 8 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 4 h, adjust the pH of the hydrolyzate after mixing evenly to 7, filter, and refrigerate the obtained product; It is the waste leather scraps hydrolyzate CFs; Step 2: Preparation of biomass carbon aerogel from waste leather scraps hydrolyzate: Dissolve 1 g of waste leather scraps hydrolyzate CFs in 35 ml of PVA solution, and mix evenly to obtain a CFs solution; Dissolve 1 g of Glc in 36 ml of the CFs solution, stir strongly with a magnetic stirrer to obtain a uniformly dispersed CFs blend dispersion, add the CFs blend dispersion using a 50 ml high-pressure reactor, place it in an oven for hydrothermal treatment at 180 °C for 3 h to obtain a waste leather scraps hydrolyzate CFs / Glc gel, pre-freeze it at -18 °C for 24 h, and then freeze-dry it in a freeze dryer for 72 h to obtain a biomass carbon aerogel.
[0020] Example 2 The method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate in the present invention is specifically as follows: Step 1: Preparation of waste leather scraps hydrolyzate: The preparation of waste leather scraps hydrolyzate fibers requires two hydrolysis steps: For the first hydrolysis, add 20 g of waste leather scraps and 12 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 5 h, filter the first hydrolyzate after mixing evenly, and refrigerate the obtained product; For the second hydrolysis, add the product obtained from the first hydrolysis and 10 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 5 h, adjust the pH of the hydrolyzate after mixing evenly to 7, filter, and refrigerate the obtained product; It is the waste leather scraps hydrolyzate CFs; Step 2: Preparation of biomass carbon aerogel from waste leather scraps hydrolyzate: Dissolve 2 g of waste leather scraps hydrolyzate CFs in 35 ml of PVA solution, and mix evenly to obtain a CFs solution; Dissolve 1 g of Glc in 36 ml of the CFs solution, stir strongly with a magnetic stirrer to obtain a uniformly dispersed CFs blend dispersion, add the CFs blend dispersion using a 50 ml high-pressure reactor, place it in an oven for hydrothermal treatment at 180 °C for 6 h to obtain a waste leather scraps hydrolyzate CFs / Glc gel, pre-freeze it at -18 °C for 24 h, and then freeze-dry it in a freeze dryer for 72 h to obtain a biomass carbon aerogel.
[0021] Example 3 The method for preparing biomass carbon aerogel based on waste leather shaving hydrolyzate in the present invention is specifically as follows: Step 1: Preparation of waste leather shaving hydrolyzate; The preparation of waste leather shaving hydrolyzate fibers requires two hydrolyses: For the first hydrolysis, 20 g of waste leather shavings and 15 g of H2SO4 are added to 250 ml of deionized water, and stirred in a 500 ml three-necked flask for 5 h. The first hydrolyzate after being mixed evenly is filtered by suction, and the obtained product is refrigerated; For the second hydrolysis, the product obtained from the first hydrolysis and 10 g of H2SO4 are added to 250 ml of deionized water, and stirred in a 500 ml three-necked flask for 5 h. The pH of the hydrolyzate after being mixed evenly is adjusted to 7, and then filtered by suction. The obtained product is refrigerated; This is the waste leather shaving hydrolyzate CFs; Step 2: Preparation of waste leather shaving hydrolyzate biomass carbon aerogel: Dissolve 2 g of waste leather shaving hydrolyzate CFs in 35 ml of PVA solution, and mix evenly to obtain a CFs solution; Dissolve 2 g of Glc in 36 ml of the CFs solution, and stir strongly with a magnetic stirrer to obtain a uniformly dispersed CFs blend dispersion. Add the CFs blend dispersion into a 50 ml high-pressure reactor, place it in an oven at 180 °C, and perform hydrothermal treatment for 6 h to obtain a waste leather shaving hydrolyzate CFs / Glc gel. Pre-freeze it at -18 °C for 24 h, and then freeze-dry it in a freeze dryer for 72 h to obtain biomass carbon aerogel.
[0022] Example 4 The method for preparing biomass carbon aerogel based on waste leather shaving hydrolyzate in the present invention is specifically as follows: Step 1: Preparation of waste leather shaving hydrolyzate: The preparation of waste leather shaving hydrolyzate fibers requires two hydrolyses: For the first hydrolysis, 25 g of waste leather shavings and 16 g of H2SO4 are added to 250 ml of deionized water, and stirred in a 500 ml three-necked flask for 6 h. The first hydrolyzate after being mixed evenly is filtered by suction, and the obtained product is refrigerated; For the second hydrolysis, the product obtained from the first hydrolysis and 10 g of H2SO4 are added to 250 ml of deionized water, and stirred in a 500 ml three-necked flask for 6 h. The pH of the hydrolyzate after being mixed evenly is adjusted to 7, and then filtered by suction. The obtained product is refrigerated; This is the waste leather shaving hydrolyzate CFs; Step 2: Preparation of waste leather shaving hydrolyzate biomass carbon aerogel: Dissolve 5 g of waste leather shavings hydrolyzate CFs in 35 ml of PVA solution, and mix evenly to obtain a CFs solution; dissolve 1 g of Glc in 36 ml of the CFs solution, and stir vigorously with a strong magnetic force to obtain a uniformly dispersed CFs blend dispersion. Add the CFs blend dispersion to a high-pressure reactor with a volume of 50 ml, place it in an oven at 180 °C, and perform hydrothermal treatment for 12 h to obtain a waste leather shavings hydrolyzate CFs / Glc gel. Pre-freeze it at -18 °C for 24 h, and then freeze-dry it in a freeze dryer for 72 h to obtain a biomass carbon aerogel.
[0023] Example 5 The method for preparing a biomass carbon aerogel based on waste leather shavings hydrolyzate in the present invention is specifically as follows: Step 1: Preparation of waste leather shavings hydrolyzate: The preparation of waste leather shavings hydrolyzate fibers requires two hydrolyses; for the first hydrolysis, add 30 g of waste leather shavings and 18 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 6 h, filter the first hydrolyzate after mixing evenly, and refrigerate the obtained product; for the second hydrolysis, add the product obtained from the first hydrolysis and 12 g of H2SO4 to 250 ml of deionized water, stir with a 500 ml three-necked flask for 6 h, adjust the pH of the hydrolyzate after mixing evenly to 7, filter, and refrigerate the obtained product; this is the waste leather shavings hydrolyzate CFs. Step 2: Preparation of waste leather shavings hydrolyzate CFs / PVA solution / Glc biomass carbon aerogel: Dissolve 1 g of waste leather shavings hydrolyzate CFs in 35 ml of PVA, and mix evenly to obtain a CFs dispersion; dissolve 5 g of Glc in 36 ml of the CFs dispersion, stir vigorously with a strong magnetic force to obtain a uniformly dispersed solution, add the CFs blend dispersion to a high-pressure reactor with a volume of 50 ml, place it in an oven at 180 °C, and perform hydrothermal treatment for 12 h to obtain a waste leather shavings hydrolyzate CFs / Glc gel. Pre-freeze it at -18 °C for 24 h, and then freeze-dry it in a freeze dryer for 72 h to obtain a biomass carbon aerogel.
[0024] The biomass carbon aerogel prepared by the above method can be used as an excellent substrate material in the electromagnetic wave field, effectively alleviating the environmental pollution caused by electromagnetic radiation. At the same time, this method not only provides a new idea for the development and utilization of carbon aerogels in the electromagnetic wave field, but also promotes the resource utilization of chromium-containing waste leather shavings.
[0025] Example 6 Figure 1Test results of the electromagnetic shielding performance of the carbon aerogel prepared in Example 1. As shown in the figure, the shielding effectiveness (SET) of the carbon aerogel in the frequency range of 8.2 - 12.4 GHz (X-band) is ≥9, indicating its excellent electromagnetic wave absorption ability in the X-band. Figure 2 Electromagnetic shielding parameters of the carbon aerogel prepared in Example 1. Combining its absorption / reflection ratio (A / R > 1) characteristics, it can be seen that the carbon aerogel is an absorption-type electromagnetic shielding material and is suitable for the field of electromagnetic pollution control.
[0026] Figure 3 Scanning electron microscope (SEM) image of the carbon aerogel prepared in Example 1, showing that its microstructure is a three-dimensional fiber network with porous and uniform distribution, the pore size is uniform, and a tightly cross-linked skeleton is formed between the fibers, indicating that the low-temperature hydrothermal method effectively retains the triple helix structure of the waste leather shavings hydrolyzate (CFs) and avoids the skeleton collapse caused by high-temperature carbonization. Figure 4 Is the stress-strain curve of the carbon aerogel of Example 1, further revealing its excellent mechanical properties. It shows elastic deformation in the initial strain (<15%) stage. When the strain increases to 15% - 50%, the pores are gradually compressed and the stress rises gently. After exceeding 50%, the pore structure enters the densification stage and the stress increases sharply, but the material can still withstand a compressive strain of 80% without rupture, and the compressive strength reaches 190 kPa. This porous and uniform fiber network ( Figure 3 ) provides a supporting skeleton for the material, enabling the energy to be effectively dispersed during the deformation process and avoiding local stress concentration, thus endowing it with high compressive strength and anti-rupture property ( Figure 4 ). At the same time, the uniform pore structure not only enhances the multiple reflections and absorptions of electromagnetic waves ( Figure 1 , Figure 2 ), but also verifies the structural stability of the material in practical applications through dynamic compression, indicating that the synergistic effect of the low-temperature hydrothermal method combined with glucose (Glc) and PVA successfully constructs a carbon aerogel with both high porosity and high toughness. Based on the above analysis, it can be concluded that the carbon aerogel has excellent porous structure, mechanical properties and electromagnetic wave absorption stability, and is suitable for applications in the field of electromagnetic wave absorption.
Claims
1. A method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate, characterized in that: Follow the steps below to implement it: Step 1, hydrolyzing the waste leather scraps twice to obtain a waste leather scraps hydrolyzate; Step 2, using PVA to assist cross-linking, and using glucose to coat and carbonize the waste leather shavings hydrolyzate to obtain biomass carbon aerogel.
2. The method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate according to claim 1, characterized in that: In the step 1, specifically: Add waste leather scraps and H2SO4 into deionized water, stir for the first hydrolysis, filter and refrigerate the obtained primary hydrolysis product; add the primary hydrolysis product and H2SO4 into deionized water, stir, add ammonia water to adjust the pH of the hydrolyzate to 7 after mixing evenly, filter and refrigerate the obtained product to obtain waste leather scraps hydrolyzate CFs.
3. The method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate according to claim 2, characterized in that: The stirring time is 3-6h.
4. The method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate according to claim 2, characterized in that: The mass ratio of the waste leather scraps, H2SO4 added during the first hydrolysis, deionized water added during the first hydrolysis, H2SO4 added during the second hydrolysis, and deionized water added during the second hydrolysis is 10-25:10-20:200-300:10-20:200-300.
5. The method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate according to claim 1, characterized in that: In the step 2, specifically: Step 2.1, dissolving the waste leather scraps hydrolyzate CFs in the PVA solution, mixing evenly, and obtaining a CFs solution evenly coated with PVA; Step 2.2, dissolving glucose in the CFs solution and stirring to obtain a uniformly dispersed modified CFs blended dispersion; Step 2.3, placing the modified CFs blended dispersion in a high-pressure reactor for hydrothermal reaction to obtain the waste leather shavings hydrolyzate CFs / Glc gel, then pre-freezing the waste leather shavings hydrolyzate CFs / Glc gel at -18~-40°C for 12-24h, and finally placing it in a freeze dryer for freeze drying to obtain biomass carbon aerogel.
6. The method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate according to claim 5, characterized in that: In the step 2.3, the hydrothermal reaction temperature is 180° C., and the hydrothermal reaction time is 3-24 hours.
7. The method for preparing biomass carbon aerogel based on waste leather shavings hydrolyzate according to claim 5, characterized in that: In the step 2.3, the freeze-drying time is 48-72 hours, and the freeze-drying temperature is -50~-80°C.
8. The biomass carbon aerogel prepared by the method for preparing biomass carbon aerogel based on waste leather scraps hydrolyzate as described in any one of claims 1 to 7.