A method for preparing a biomass-based adsorbent material

Abstract

The application discloses a preparation method of a biomass-based adsorption material, and belongs to the technical field of adsorption, and is used for solving at least one problem that gallium extraction in coal gangue acid leaching liquor introduces other metal ion impurities, needs a large amount of organic solvents, requires a high temperature, and straw pre-hydrolysis is poor, so that the biomass-based adsorption material cannot be used in the preparation of the biomass-based adsorption material. The preparation method comprises the following steps: pre-hydrolyzing straw raw materials, mixing and stirring the hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid, and then heating and reacting to obtain a biomass polyol; mixing triethanolamine, ionized water, petroleum-based polyether polyol and dimethyl silicone oil to obtain a first mixed solution, mixing the biomass polyol, polyether polyol, toluene-2,4-diisocyanate and dibutyltin dilaurate to obtain a second mixed solution; and mixing and reacting the first mixed solution and the second mixed solution to obtain the biomass-based adsorption material. The application can be used for the preparation of the biomass-based adsorption material.

Description

Technical Field

[0001] This invention belongs to the field of adsorption technology, and particularly relates to a method for preparing biomass-based adsorption materials. Background Technology

[0002] Coal gangue is an industrial solid waste generated during coal mining and processing. It is rich in various metallic elements, including not only major elements such as aluminum (Al), iron (Fe), calcium (Ca), and titanium (Ti), but also trace elements such as lithium (Li), gallium (Ga), germanium (Ge), and rare earth elements. Among them, gallium, as a strategic key metal resource with unique semiconductor properties, is widely used in industries such as semiconductors, solar cells, and medicine.

[0003] Currently, the main methods for extracting gallium from coal gangue acid leaching solutions include precipitation, extraction, and adsorption.

[0004] Among them, precipitation inevitably introduces other metal ion impurities during the process; extraction requires the use of a large amount of organic solvents, which may cause harm to the environment and human body; adsorption uses polyurethane foam, which shows good selectivity for gallium ions, but its gallium adsorption rate is 83.9% at 60℃, and the required temperature is relatively high. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a method for preparing biomass-based adsorbent materials, which solves at least one of the problems in the prior art where the extraction of gallium from coal gangue acid leaching solution introduces other metal ion impurities, requires a large amount of organic solvent, requires a high temperature, and the straw pre-hydrolysis effect is poor, making it unsuitable for the preparation of biomass-based adsorbent materials.

[0006] The objective of this invention is mainly achieved through the following technical solutions.

[0007] This invention provides a method for preparing a biomass-based adsorbent material, comprising the following steps: Step 1: Pre-hydrolyze the straw raw material to obtain pre-hydrolyzed straw; Step 2: Mix the hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid, stir and heat to react, and obtain biomass polyol; Step 3: Mix triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil to obtain the first mixture; mix biomass polyol, polyether polyol, toluene-2,4-diisocyanate and dibutyltin dilaurate to obtain the second mixture. Step 4: Mix the first mixture and the second mixture to obtain the biomass-based adsorbent material.

[0008] Further, step 1 includes the following steps: Step 11: Place 4g~6g of straw raw material in a container; Step 12: Add 45 mL to 60 mL of H2SO4 with a concentration of 0.4 mol / L to 0.6 mol / L to the container to obtain a mixture; Step 13: Heat the mixture to 85℃~92℃ and hold at that temperature for 0.5h~1.5h to hydrolyze it, obtaining a hydrolyzed mixture; Step 14: The hydrolyzed mixture is filtered, washed and dried in sequence to obtain pre-hydrolyzed straw.

[0009] Furthermore, in step 2, the mass ratio of hydrolyzed straw, glycerol, and polyethylene glycol is 2~3:4~6:15~18.

[0010] Furthermore, in step 2, concentrated sulfuric acid accounts for 10% to 25% of the mass of the hydrolyzed straw.

[0011] Furthermore, in step 2, the heating temperature is 140℃~200℃, and the reaction time is 1.5h~3.0h.

[0012] Furthermore, in step 2, the stirring speed is 350 r / min to 450 r / min.

[0013] Furthermore, the following steps are included before step 1: The stems are pretreated to obtain straw.

[0014] Furthermore, in step 4, after the first mixture and the second mixture are mixed and reacted, the following steps are also included: Post-processing of the reactants.

[0015] Furthermore, post-processing includes the following steps: The reactants were allowed to stand at 20℃~30℃ for 0.5h~1.0h and then dried at 65℃~75℃ for 0.5h~1.0h to obtain foam plastic. Furthermore, post-processing includes the following steps: Grind the foam.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: A) The preparation method of biomass-based adsorbent material provided by the present invention uses biomass material (corn stalk or rice stalk) as raw material to prepare biomass-based polyol, which replaces part of the petroleum-based polyether polyol. On the basis of reducing the amount of petroleum-based polyether polyol, toluene-2,4-diisocyanate, biomass-based polyol and polyether polyol are used as raw materials, and triethanolamine is used as catalyst to synthesize biomass-based polyurethane foam (i.e. biomass-based adsorbent material) with excellent adsorption performance. The polyurethane foam is used as adsorbent to adsorb gallium ions in the acid leaching solution of coal gangue, thereby completing the purification and separation of gallium and realizing the extraction and utilization of gallium in coal gangue.

[0017] B) The preparation method of the biomass-based adsorbent material provided by the present invention, wherein the carbamate group, after protonation, can form a gallium complex GaCl4. - Chemical adsorption occurs, while other ions, except for iron ions, do not undergo this type of reaction. Therefore, hydroxylamine hydrochloride is added beforehand to reduce iron, achieving selective adsorption and solving the problem of introducing other metal ion impurities into gallium extraction from coal gangue acid leaching solution in existing technologies.

[0018] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0020] Figure 1 The graph shows the relationship between the proportion of biomass polyols and adsorption capacity for Comparative Example 1, Example 1a, Example 1b, Example 1c and Comparative Example 2. Figure 2 The graph shows the relationship between the amount of concentrated sulfuric acid added and the adsorption force for Comparative Example 3, Example 2a, Example 2b, Example 2c and Comparative Example 4. Figure 3 The graph shows the relationship between the preparation temperature and adsorption rate of biomass polyols in Examples 3a, 3b, 3c, 3d, and 3e. Detailed Implementation

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0022] In a first aspect, the present invention provides a method for preparing a biomass-based adsorbent material, comprising the following steps: Step 1: Pre-hydrolyze the straw raw material (e.g., corn straw or rice straw) to obtain pre-hydrolyzed straw; Step 2: Mix the hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid, stir and heat to react, and obtain biomass polyol; Step 3: Mix triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil to obtain a first mixture, wherein the mass ratio of triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil is 1.0~1.2:1.9~2.2:50~56:2.0~2.5; A second mixture is prepared by mixing biomass polyol, petroleum-based polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate. The mass ratio of polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate is 120-130:50-55:2.0-2.5, and the biomass polyol accounts for 5%-15% of the total mass of the polyol (the total mass of petroleum-based polyether polyol and biomass polyol in the first and second mixtures). Step 4: Mix the first and second mixtures to obtain biomass-based adsorbent material, namely biomass-based polyurethane foam.

[0023] It should be noted that the formulas involved in the above preparation method are as follows: RN=C=O+R'-OH→R-NHCOO-R' RN=C=O+H2O→R-NH-COOH→R-NH2+CO2↑ R-NH2+RN=C=O→R-NH-CO-NH-R Where R and R' are carbon chains.

[0024] Compared with existing technologies, the preparation method of biomass-based adsorbent materials provided by this invention uses biomass materials (corn stalks or rice stalks) as raw materials to prepare biomass-based polyols, replacing part of the petroleum-based polyether polyols. On the basis of reducing the amount of petroleum-based polyether polyols, toluene-2,4-diisocyanate, biomass-based polyols and polyether polyols are used as raw materials, and triethanolamine is used as a catalyst to synthesize biomass-based polyurethane foam (i.e., biomass-based adsorbent material) with excellent adsorption performance. The polyurethane foam is used as an adsorbent to adsorb gallium ions in the acid leaching solution of coal gangue, thereby completing the purification and separation of gallium and realizing the extraction and utilization of gallium in coal gangue.

[0025] Furthermore, the urethane group, after protonation, can form a gallium complex, GaCl4. -Chemical adsorption occurs, while other ions, except for iron ions, do not undergo this type of reaction. Therefore, hydroxylamine hydrochloride is added beforehand to reduce iron, achieving selective adsorption and solving the problem of introducing other metal ion impurities into gallium extraction from coal gangue acid leaching solution in existing technologies.

[0026] In practical applications, the adsorption rate of gallium using the biomass-based adsorbent material of this invention can reach more than 85% at a temperature of 30℃~40℃, thereby solving the problems of requiring a large amount of organic solvent, high required temperature and low adsorption rate.

[0027] Furthermore, in order to improve the pre-hydrolysis effect, step 1 above includes the following steps: Step 11: Place 4g~6g (e.g. 5g) of straw raw material in a container; Step 12: Add 45 mL to 60 mL (e.g., 50 mL) of H2SO4 with a concentration of 0.4 mol / L to 0.6 mol / L (e.g., 0.5 mol / L) to the container to obtain a mixture; Step 13: Place the mixture in a constant temperature oil bath and heat it to 85℃~92℃ (e.g., 90℃) for 0.5h~1.5h (e.g., 1h) to hydrolyze it, and obtain a hydrolyzed mixture; Step 14: The hydrolyzed mixture is filtered, washed and dried in sequence to obtain pre-hydrolyzed straw.

[0028] Thus, by adopting the above-mentioned pre-hydrolysis method, impurities in straw raw materials can be removed more effectively, the pre-hydrolysis effect can be improved, and higher quality raw materials can be provided for the subsequent preparation of biomass-based polyols.

[0029] For example, in step 2 above, the mass ratio of hydrolyzed straw, glycerol, and polyethylene glycol is 2-3:4-6:15-18, and concentrated sulfuric acid accounts for 10%-25% of the mass of hydrolyzed straw. This is because by precisely controlling the mass ratio of hydrolyzed straw, glycerol, and polyethylene glycol, as well as the amount of concentrated sulfuric acid added, the preparation process of biomass polyols can be optimized. Setting this ratio and amount helps to improve the yield and quality of biomass polyols, thereby providing more ideal raw materials for the subsequent synthesis of biomass-based polyurethane foams.

[0030] Accordingly, in step 2 above, the heating temperature is 140℃~200℃ (e.g., 140℃, 160℃, 170℃, 180℃ or 200℃), the stirring speed is 350r / min~450r / min (e.g., 400r / min), and the reaction time is 1.5h~3.0h (e.g., 2h). This is because a suitable combination of heating temperature, stirring speed and reaction time can ensure that the reaction proceeds fully, resulting in a more stable molecular structure and better performance of the biomass polyol.

[0031] Furthermore, in order to further improve the yield of biomass-based adsorbent materials, the following steps are included before step 1 above: The stems are pretreated to obtain straw.

[0032] Specifically, one type of preprocessing includes the following steps: Cut the stalks into sections 4cm to 6cm long (e.g., 5cm); The straw segments are dried and crushed once to obtain straw pellets. The drying temperature for the first drying is 93℃~94℃. Straw pellets are sieved through a 35-mesh standard sieve and then dried twice to constant weight. The secondary drying temperature is 95℃~96℃ to obtain straw raw material.

[0033] Thus, pretreating the straw using the above method yields straw raw materials with uniform particle size and suitable dryness, providing a good foundation for subsequent pre-hydrolysis steps, improving the pre-hydrolysis effect, and consequently enhancing the preparation quality and performance of biomass-based adsorbent materials. Furthermore, using different temperatures for the two drying stages allows for more precise control of the straw raw material's dryness, reducing the risk of altered raw material properties due to excessively high or low temperatures, which could negatively impact subsequent preparation processes and adsorbent material performance.

[0034] Furthermore, it is worth noting that air bubbles are still unavoidably present in the straw raw material obtained from the above pretreatment process. The presence of air bubbles and the low density of the straw raw material cause some of the straw raw material to float on the surface of the sulfuric acid during the pre-hydrolysis process, with contact between the two only at the interface, affecting the pre-hydrolysis effect of the straw raw material. Therefore, the above-mentioned alternative pretreatment method includes the following steps: The stems are pretreated to obtain straw.

[0035] Specifically, one type of preprocessing includes the following steps: Cut the stalks into sections 4cm to 6cm long (e.g., 5cm); The straw segments are dried and crushed once to obtain straw pellets. The drying temperature for the first drying is 93℃~94℃. The straw pellets were soaked in a solution of calcium nitrate tetrahydrate at a temperature of 46℃~48℃. Negative pressure impregnation was applied to the calcium nitrate tetrahydrate liquid soaked with straw particles, so that the calcium nitrate tetrahydrate liquid filled the pores of the straw particles. Solid-liquid separation was performed on a liquid of calcium nitrate tetrahydrate containing straw particles after being impregnated under negative pressure, under normal pressure. The solid phase is cooled to a temperature of 25℃~35℃, causing the calcium nitrate tetrahydrate in the pores of the straw particles to solidify into a solid, resulting in high-density particles. The density of the high-density particles is greater than that of sulfuric acid. High-density particles are crushed to reduce their agglomeration, thus obtaining straw raw material.

[0036] Thus, by using the above pretreatment method to impregnate straw particles with calcium nitrate tetrahydrate liquid under negative pressure, air bubbles in the straw raw material can be effectively removed. Simultaneously, cooling causes the calcium nitrate tetrahydrate to solidify, increasing the density of the straw raw material to be greater than that of sulfuric acid. During the subsequent pre-hydrolysis process, the straw raw material can sink below the surface of the sulfuric acid, and the calcium nitrate tetrahydrate gradually dissolves in the sulfuric acid. This also increases the contact area between the straw raw material and the sulfuric acid, allowing for a more complete reaction and significantly improving the pre-hydrolysis effect of the straw raw material.

[0037] Furthermore, for the second pretreatment method, a pretreatment device with the following structure is adopted.

[0038] The pretreatment device includes a negative pressure immersion tank, a solid-liquid separation tank, an air-cooled pipeline, and a crushing tank connected in sequence.

[0039] The negative pressure impregnation tank is used to impregnate the straw pellets under negative pressure. By precisely controlling the temperature of the calcium nitrate tetrahydrate liquid and the negative pressure value during impregnation, it ensures that the straw pellets fully absorb the liquid and fill the pores. The discharge port is equipped with a discharge valve. The solid-liquid separation tank is used to separate the straw pellets from the calcium nitrate tetrahydrate liquid after negative pressure impregnation.

[0040] It should be noted that the temperature inside the solid-liquid separation tank is lower than that inside the negative pressure wetting tank, so as to appropriately increase the viscosity of the calcium nitrate tetrahydrate liquid and reduce its outflow from the pores of the straw particles. However, the temperature inside the solid-liquid separation tank is still higher than the melting temperature of the calcium nitrate tetrahydrate liquid. The air-cooling pipeline is connected after the solid-liquid separation tank, and cold air is introduced to cool the solid phase, so that the calcium nitrate tetrahydrate solidifies into a solid in the pores of the straw particles. The crushing tank is located at the end of the entire pretreatment device and is used to crush the high-density particles obtained after cooling, which can reduce the agglomeration of the high-density particles and finally obtain straw raw materials that meet the requirements.

[0041] Furthermore, in order to realize the recovery and reuse of the liquid phase of calcium nitrate tetrahydrate after solid-liquid separation, the liquid phase outlet of the solid-liquid separator is connected to the liquid inlet of the negative pressure wetting tank. In this way, the liquid phase of calcium nitrate tetrahydrate separated by the solid-liquid separator can be returned to the negative pressure wetting tank to form a recycling system.

[0042] Furthermore, it can be understood that, in order to further improve the performance of biomass-based adsorbent materials, step 4 above, after mixing and reacting the first and second mixtures, also includes the following steps: Post-processing of the reactants.

[0043] Specifically, post-processing includes the following steps: The reactants are allowed to stand at 20℃~30℃ (e.g., 25℃) for 0.5h~1.0h, and then dried at 65℃~75℃ for 0.5h~1.0h to obtain foam plastic. Grind the foam.

[0044] In this way, post-processing makes the resulting biomass-based adsorbent material (foamed plastic) more uniform in texture and more stable in performance. The ground foamed plastic has a larger specific surface area, which helps increase its contact area with gallium ions in the coal gangue acid leaching solution, thereby improving adsorption efficiency and capacity, better purifying and separating gallium, and further enhancing the extraction and utilization of gallium from coal gangue. Moreover, the post-processed foamed plastic is more convenient to store and use, less prone to clumping, thus ensuring the long-term stability and reliability of the biomass-based adsorbent material.

[0045] Example 1 This embodiment provides a method for preparing a biomass-based adsorbent material, including the following steps: Step A: Cut the stalks into 5cm lengths, dry and crush the stalks once to obtain straw pellets. The first drying temperature is 93℃. After the straw pellets are sieved through a 35-mesh standard sieve, they are dried a second time to constant weight. The second drying temperature is 95℃ to obtain the straw raw material. Step B: Place 5g of straw raw material in a container, add 50mL of 0.5mol / L H2SO4 to the container to obtain a mixture, put the mixture into a constant temperature oil bath and heat it to 90℃ for 1h to hydrolyze it, and obtain a hydrolyzed mixture. Filter, wash and dry the hydrolyzed mixture in sequence to obtain pre-hydrolyzed straw. Step C: The hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid are mixed and stirred and heated to react to obtain biomass polyol. The mass ratio of hydrolyzed straw, glycerol and polyethylene glycol is 3:5:18, the amount of concentrated sulfuric acid added is 10%, the heating temperature is 180℃, the stirring speed is 400r / min, and the reaction time is 2h. Step D: Triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil are mixed to obtain a first mixture, wherein the mass ratio of triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil is 1.0:2.0:55:2.0; A second mixture was prepared by mixing biomass polyol, polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate, wherein the mass ratio of petroleum-based polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate was 125:50:2.0, and the mass percentage of biomass polyol in the polyol (total mass of petroleum-based polyether polyol and biomass polyol in the first and second mixtures) was 5% (Example 1a), 10% (Example 1b), and 15% (Example 1c), respectively. Step E: Mix the first and second mixtures together and react them; Step F: After the reactants are allowed to stand at 25°C for 0.5 h, they are dried at 70°C for 1.0 h to obtain foam plastic; the foam plastic is then ground to obtain biomass-based adsorbent material.

[0046] Example 2 This embodiment provides a method for preparing a biomass-based adsorbent material, including the following steps: Step A: Cut the stalks into 4cm lengths, dry and crush the stalks once to obtain straw pellets. The first drying temperature is 94℃. After the straw pellets are sieved through a 35-mesh standard sieve, they are dried a second time to constant weight at a temperature of 96℃ to obtain straw raw material. Step B: Place 4g of straw raw material in a container, add 45mL of 0.6mol / L H2SO4 to the container to obtain a mixture, put the mixture into a constant temperature oil bath and heat it to 85℃ for 1.5h for hydrolysis to obtain a hydrolyzed mixture, filter, wash and dry the hydrolyzed mixture in sequence to obtain pre-hydrolyzed straw; Step C: The hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid were mixed and stirred and heated to obtain biomass polyol. The mass ratio of hydrolyzed straw, glycerol and polyethylene glycol was 2.5:6:16. The amount of concentrated sulfuric acid added was 10% (Example 2a), 20% (Example 2b) and 25% (Example 2c), respectively. The heating temperature was 180℃, the stirring speed was 450 r / min and the reaction time was 3.0 h. Step D: Triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil are mixed to obtain a first mixture, wherein the mass ratio of triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil is 1.0:2.0:55:2.0; A second mixture was prepared by mixing biomass polyol, polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate, wherein the mass ratio of petroleum-based polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate was 125:50:2.0, and the biomass polyol accounted for 10% of the total mass of the polyols (the total mass of petroleum-based polyether polyol and biomass polyol in the first and second mixtures). Step E: Mix the first and second mixtures together and react them; Step F: After the reactants are allowed to stand at 25°C for 0.5 h, they are dried at 70°C for 1.0 h to obtain foam plastic; the foam plastic is then ground to obtain biomass-based adsorbent material.

[0047] Example 3 This embodiment provides a method for preparing a biomass-based adsorbent material, including the following steps: Step A: Cut the stalks into 6cm lengths, dry and crush the stalks once to obtain straw pellets. The first drying temperature is 93℃. After the straw pellets are sieved through a 35-mesh standard sieve, they are dried a second time to constant weight. The second drying temperature is 95℃ to obtain straw raw material. Step B: Place 6g of straw raw material in a container, add 60mL of 0.4mol / L H2SO4 to the container to obtain a mixture, put the mixture into a constant temperature oil bath and heat it to 92℃ for 0.5h for hydrolysis to obtain a hydrolyzed mixture, filter, wash and dry the hydrolyzed mixture in sequence to obtain pre-hydrolyzed straw; Step C: The hydrolyzed straw, glycerol, polyethylene glycol, and concentrated sulfuric acid were mixed, stirred, and heated to react and obtain biomass polyol. The mass ratio of hydrolyzed straw, glycerol, and polyethylene glycol was 3:6:18. The amount of concentrated sulfuric acid added was 20%. The heating temperatures were 140℃ (Example 3a), 160℃ (Example 3b), 170℃ (Example 3c), 180℃ (Example 3d), and 200℃ (Example 3e). The stirring speed was 400 r / min, and the reaction time was 2 h. Step D: Triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil are mixed to obtain a first mixture, wherein the mass ratio of triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil is 1.0:2.0:55:2.0; A second mixture was prepared by mixing biomass polyol, polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate, wherein the mass ratio of petroleum-based polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate was 125:50:2.0, and the biomass polyol accounted for 10% of the total mass of the polyols (the total mass of petroleum-based polyether polyol and biomass polyol in the first and second mixtures). Step E: Mix the first and second mixtures together and react them; Step F: After the reactants are allowed to stand at 25°C for 0.5 h, they are dried at 70°C for 1.0 h to obtain foam plastic; the foam plastic is then ground to obtain biomass-based adsorbent material.

[0048] Example 4 This embodiment provides a method for preparing a biomass-based adsorbent material, including the following steps: Step A: Cut the stalks into 6cm lengths. Dry and crush the stalks once to obtain straw pellets. The drying temperature is 93℃. Soak the straw pellets in calcium nitrate tetrahydrate solution at 47℃. Impregnate the calcium nitrate tetrahydrate solution with straw pellets under negative pressure to fill the pores of the straw pellets. Separate the solid and liquid phases of the impregnated calcium nitrate tetrahydrate solution under normal pressure. Cool the solid phase to 30℃, causing the calcium nitrate tetrahydrate in the pores of the straw pellets to solidify into high-density pellets with a density greater than that of sulfuric acid. Crush the high-density pellets to reduce agglomeration and obtain the straw raw material. Step B: Place 6g of straw raw material in a container, add 60mL of 0.4mol / L H2SO4 to the container to obtain a mixture, put the mixture into a constant temperature oil bath and heat it to 92℃ for 0.5h for hydrolysis to obtain a hydrolyzed mixture, filter, wash and dry the hydrolyzed mixture in sequence to obtain pre-hydrolyzed straw; Step C: The hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid are mixed and stirred and heated to react to obtain biomass polyol. The mass ratio of hydrolyzed straw, glycerol and polyethylene glycol is 3:6:18, the amount of concentrated sulfuric acid added is 20%, the heating temperature is 180℃, the stirring speed is 400r / min and the reaction time is 2h. Step D: Triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil are mixed to obtain a first mixture, wherein the mass ratio of triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil is 1.0:2.0:55:2.0; A second mixture was prepared by mixing biomass polyol, polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate, wherein the mass ratio of petroleum-based polyether polyol, toluene-2,4-diisocyanate, and dibutyltin dilaurate was 125:50:2.0, and the biomass polyol accounted for 10% of the total mass of the polyols (the total mass of petroleum-based polyether polyol and biomass polyol in the first and second mixtures). Step E: Mix the first and second mixtures together and react them; Step F: After the reactants are allowed to stand at 25°C for 0.5 h, they are dried at 70°C for 1.0 h to obtain foam plastic; the foam plastic is then ground to obtain biomass-based adsorbent material.

[0049] Comparative Example 1 The steps and process parameters of this comparative example are basically the same as those of Example 1, with the only difference being: All polyols used are petroleum-based polyether polyols, meaning the amount of biomass polyols added is 0.

[0050] Comparative Example 2 The steps and process parameters of this comparative example are basically the same as those of Example 1, with the only difference being: The mass percentage of biomass polyols in the polyols is 20%.

[0051] Comparative Example 3 The steps and process parameters of this comparative example are basically the same as those of Example 1, with the only difference being: The amount of concentrated sulfuric acid added was 0%.

[0052] Comparative Example 4 The steps and process parameters of this comparative example are basically the same as those of Example 1, with the only difference being: The amount of concentrated sulfuric acid added is 30%.

[0053] Gallium was extracted and adsorbed using the comparative examples and embodiments described above, and the specific processes are as follows: Accurately weigh 20 mL of coal gangue leachate into a beaker, add 0.4 g of biomass-based adsorbent material, shake well, cover, and place in a constant temperature oil bath at 60°C with stirring at 400 r / min for 2 h; put the adsorbed foam into an Erlenmeyer flask, add 20 mL of 0.5 mol / L NH4Cl solution, shake well, cover, and place in a constant temperature oil bath at 70°C with stirring at 400 r / min for 2 h.

[0054] For the adsorption rates of the various embodiments and comparative examples, please refer to [link / reference]. Figures 1 to 3 .

[0055] in, Figure 1The graph shows the relationship between the proportion of biomass polyols and adsorption capacity for Comparative Example 1, Example 1a, Example 1b, Example 1c and Comparative Example 2.

[0056] from Figure 1 It can be seen that the proportion of biomass polyols has a significant impact on the preparation of biomass-based polyurethane foam. In the preparation of biomass-based polyurethane foam, when only petroleum-based polyether polyols (i.e., Comparative Example 1) are used, the adsorption efficiency is 74.96%. With the increase of the proportion of biomass polyols, the adsorption performance of the biomass-based polyurethane foam significantly improves. When the proportion reaches 10% (i.e., Example 1b), the adsorption rate reaches 85.50%. However, when the proportion reaches 15% (i.e., Example 1c), the foam becomes sticky, and the adsorption efficiency begins to decrease. When the proportion reaches 20% (i.e., Comparative Example 2), the foam adheres to the wall surface during adsorption, thus affecting the adsorption process; at this point, the foam cannot be used for adsorption experiments.

[0057] Figure 2 The graph shows the relationship between the amount of concentrated sulfuric acid added and the adsorption force for Comparative Example 3, Example 2a, Example 2b, Example 2c and Comparative Example 4.

[0058] from Figure 2 It can be seen that when concentrated sulfuric acid catalyst is not added to the reaction system (i.e., Comparative Example 3), cellulose cannot be effectively destroyed, the reaction cannot proceed smoothly, and the product cannot be used to prepare biomass-based polyols, thus subsequent adsorption experiments cannot be conducted. With the increase of concentrated sulfuric acid dosage, the adsorption performance of biomass-based polyurethane foam gradually increases. However, when the concentrated sulfuric acid dosage is too high (i.e., Example 2c), its destructive effect on cellulose is significantly enhanced, leading to a decrease in the adsorption performance of the prepared polyurethane foam. In particular, when the concentrated sulfuric acid dosage reaches 30% (i.e., Comparative Example 4), excessive destruction causes a significant increase in the viscosity of the polyurethane foam, making it unsuitable for gallium adsorption.

[0059] Figure 3 The graph shows the relationship between the preparation temperature and adsorption rate of biomass polyols in Examples 3a, 3b, 3c, 3d, and 3e.

[0060] from Figure 3It can be seen that when the preparation temperature is too low (i.e., Example 3a), the reaction is incomplete, resulting in a low solubility of straw and a large amount of organic solvent being adsorbed by the straw, thus leading to a low content of biomass-based polyols obtained by filtration. As the temperature increases, the reaction proceeds more thoroughly, and the yield of biomass-based polyols and the adsorption performance of the prepared biomass-based polyurethane foam increase significantly. When the temperature reaches 180℃~200℃ (i.e., Examples 3d and 3e), the PEG400 and glycerol system reaches its boiling point, at which point the reaction is more complete, and the adsorption performance of the biomass-based polyurethane foam increases significantly, reaching 85.50%.

[0061] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a biomass-based adsorbent material, characterized in that, Includes the following steps: Step 1: Pre-hydrolyze the straw raw material to obtain pre-hydrolyzed straw; Step 2: Mix the hydrolyzed straw, glycerol, polyethylene glycol and concentrated sulfuric acid, stir and heat to react, and obtain biomass polyol; Step 3: Mix triethanolamine, deionized water, petroleum-based polyether polyol and dimethyl silicone oil to obtain the first mixture; mix biomass polyol, polyether polyol, toluene-2,4-diisocyanate and dibutyltin dilaurate to obtain the second mixture. Step 4: Mix the first mixture and the second mixture to obtain the biomass-based adsorbent material.

2. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, Step 1 includes the following steps: Step 11: Place 4g~6g of straw raw material in a container; Step 12: Add 45 mL to 60 mL of H2SO4 with a concentration of 0.4 mol / L to 0.6 mol / L to the container to obtain a mixture; Step 13: Heat the mixture to 85℃~92℃ and hold at that temperature for 0.5h~1.5h to hydrolyze it, obtaining a hydrolyzed mixture; Step 14: The hydrolyzed mixture is filtered, washed and dried in sequence to obtain pre-hydrolyzed straw.

3. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, In step 2, the mass ratio of the hydrolyzed straw, glycerol, and polyethylene glycol is 2~3:4~6:15~18.

4. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, In step 2, concentrated sulfuric acid accounts for 10% to 25% of the mass of the hydrolyzed straw.

5. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, In step 2, the heating temperature is 140℃~200℃, and the reaction time is 1.5h~3.0h.

6. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, In step 2, the stirring speed is 350 r / min to 450 r / min.

7. The method for preparing the biomass-based adsorbent material according to any one of claims 1 to 6, characterized in that, The following steps are included before step 1: The stems are pretreated to obtain straw.

8. The method for preparing the biomass-based adsorbent material according to claim 1, characterized in that, Step 4, after the first mixture and the second mixture are mixed and reacted, also includes the following steps: Post-processing of the reactants.

9. The method for preparing the biomass-based adsorbent material according to claim 8, characterized in that, The post-processing includes the following steps: The reactants were allowed to stand at 20℃~30℃ for 0.5h~1.0h and then dried at 65℃~75℃ for 0.5h~1.0h to obtain foamed plastic.

10. The method for preparing the biomass-based adsorbent material according to claim 9, characterized in that, The post-processing also includes the following steps: Grind the foam.

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