Preparation method of magnetically responsive cellulose nanocrystal-ferrite hybrid materials

Abstract

This invention belongs to the field of functional nanomaterials and discloses a method for preparing a magnetically responsive cellulose nanocrystal-ferrite hybrid material, comprising the following steps: first, cellulose raw material is mixed and heated with an inorganic metal chloride solution at 60-100°C, and the resulting precipitate is collected. Then, the precipitate is dissolved in a solvent with a weakly alkaline reagent, and a reduction reaction is carried out at 150-250°C. After washing and drying, the cellulose nanocrystal-ferrite hybrid material is obtained. This invention uses microcrystalline cellulose as a raw material and prepares cellulose-based nanometal oxides using a single iron source in a one-pot process without the presence of additional additives. This effectively reduces the consumption of additional chemicals and energy, and has the advantages of simple process, short process, low cost, and environmental friendliness, which is beneficial for industrialization.

Description

Technical Field

[0001] This invention belongs to the field of functional nanomaterials, specifically relating to a method for preparing a magnetically responsive cellulose nanocrystal-ferrite hybrid material. Background Technology

[0002] Nanocellulose, derived from renewable biomass raw materials, possesses physicochemical and biological properties such as biodegradability, non-toxicity, large specific surface area, high elastic modulus, and high aspect ratio, making its functionalized materials promising for applications. Among these, nanocellulose / nanometal oxide hybrid materials have high research and development value due to their multiple functions, including antibacterial, reinforcing, catalytic, and photoelectric / magnetic properties.

[0003] Cellulose molecules have a large number of hydroxyl groups, which provide nanocellulose with numerous attachment sites, improving interfacial compatibility and preventing the aggregation of metal oxide particles. However, they are also prone to forming intermolecular or intramolecular hydrogen bonds. The unique template structure of nanocellulose is beneficial for mediating the nucleation and growth of nanoparticles, especially inhibiting aggregation, and greatly improving the dispersion uniformity and stability of nanoparticles.

[0004] Currently, there is limited research on the preparation of magnetically responsive nanomaterials using cellulose nanoparticles. CN103709422A discloses a method for preparing magnetic cellulose nanocrystals. This invention first adds cellulose raw materials to an acidic solution to obtain cellulose nanocrystals, then adds the cellulose nanocrystals to an iron salt solution and stirs, intermittently adding chitosan solution and sodium tripolyphosphate solution to adjust the pH to alkaline. After the reaction, magnetic cellulose material is obtained. In the magnetic cellulose material prepared by this patent, the cellulose nanocrystals are tightly bonded to iron oxide (Fe3O4). However, the preparation process involves many steps, which is not conducive to resource conservation, and the use of sodium tripolyphosphate solution will cause some environmental pollution.

[0005] CN110903432A discloses a method for preparing a photothermal responsive drug-releasing hydrogel based on magnetic cellulose nanocrystals. This invention first prepares a cellulose nanocrystal solution from plant materials using acid hydrolysis, and then introduces Fe into the cellulose nanocrystal solution. 2+ and Fe 3+ Magnetic nanoparticles were synthesized in situ under alkaline conditions to obtain a colloidal solution. This patent extracts cellulose nanocrystals solely from plant materials, consuming additional chemicals and energy, and using two iron sources. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one deficiency of the prior art and provide a method for preparing a magnetically responsive cellulose nanocrystal-ferrite hybrid material.

[0007] The technical solution adopted in this invention is:

[0008] In a first aspect, the present invention provides a method for preparing a magnetically responsive cellulose nanocrystal-ferrite hybrid material, comprising the following steps:

[0009] 1) Mix and heat the cellulose raw material with an inorganic metal chloride solution at 60–100°C, and collect the resulting precipitate;

[0010] 2) Dissolve the precipitate from step 1) in a weakly alkaline reagent in a solvent, and then carry out a reduction reaction at 150-250°C. Wash and dry to obtain the cellulose nanocrystal-ferrite hybrid material.

[0011] In some instances, the inorganic metal chloride in step 1) is one or more of ferric chloride, cobalt chloride, zinc chloride, lithium chloride, and magnesium chloride, wherein ferric chloride accounts for 66.7% to 100% of the total molar number of metal ions in the inorganic metal chloride.

[0012] In some instances, the concentration of the inorganic metal chloride solution is 0.1–10 mol / L.

[0013] In some instances, the solid-liquid ratio of the cellulose raw material to the inorganic metal chloride solution is 1 g: (10-100) mL.

[0014] In some instances, the mass ratio of the cellulose raw material to the weakly basic reagent is 1:1 to 1:10.

[0015] In some instances, the solid-liquid ratio of the cellulose raw material to the solvent is 1 g: (20-100) mL.

[0016] In some instances, the weakly alkaline reagent is at least one of sodium acetate, sodium tartrate, calcium acetate, or potassium acetate.

[0017] In some instances, the solvent is selected from at least one of water, ethanol, ethylene glycol, or glycerol. Preferably, the solvent is selected from at least one of water and ethanol. This results in lower costs.

[0018] In some instances, the heating temperature in step 1) is 60–100°C, and the heating time is 4–8 hours.

[0019] In some instances, the reduction reaction temperature in step 2) is 150–250°C, and the reaction time is 3–30 hours.

[0020] There are no particular requirements regarding the type of cellulose raw material. In some instances, the cellulose raw material is one or more of microcrystalline cellulose, filter paper fiber, delignified pulp, cotton, bamboo fiber, hemp fiber, and bacterial cellulose. These cellulose raw materials are widely available and inexpensive.

[0021] Secondly, the application of the cellulose nanocrystal-ferrite hybrid material prepared by the preparation method provided in the first aspect of the present invention in the preparation of magnetic catalytic materials, electromagnetic shielding materials, supercapacitor materials or gas-sensitive materials.

[0022] The beneficial effects of this invention are:

[0023] (1) Cellulose molecular chains have a large number of hydroxyl groups, which improve interfacial compatibility and prevent the aggregation of metal oxide particles.

[0024] (2) The process of this invention prepares cellulose-based nano-metal oxides by a one-pot method, which effectively reduces the consumption of additional chemicals and energy.

[0025] (3) In this invention, under conditions where no additional additives (such as precipitants, reducing agents, or catalysts) are present, iron ions (Fe) are... 3+ ) Reduce ferrous ions (Fe 2+ This achieves the goal of preparing Fe3O4 from a single iron source, as well as the organic composite of Fe3O4 and cellulose nanocrystals, without the need for high-temperature conversion or crystallization processes.

[0026] (4) The process of this invention has the advantages of simple process, short process, low cost and green environmental protection, which is conducive to industrialization. The prepared cellulose nanocrystal-ferrite hybrid material can be used in microwave absorption, magnetic catalysis, electromagnetic shielding, supercapacitor materials, gas sensitive materials and other fields. Attached Figure Description

[0027] Figure 1 The X-ray diffraction (XRD) patterns are of the cellulose nanocrystal-ferrite hybrid material (a) obtained in Comparative Example 1 and the cellulose nanocrystal-ferrite hybrid material (b) obtained in Example 1.

[0028] Figure 2 The images show the XRD patterns of the cellulose nanocrystal-ferrite hybrid material (a) obtained in Example 1, the cellulose nanocrystal-ferrite hybrid material (b) obtained in Example 2, and the cellulose nanocrystal-ferrite hybrid material (c) obtained in Example 4.

[0029] Figure 3 This is a transmission electron microscope (TEM) image of the cellulose nanocrystal-ferrite hybrid material obtained in Example 4.

[0030] Figure 4 The figures are hysteresis loop diagrams of the cellulose nanocrystal-ferrite hybrid materials obtained in Examples 1 to 4, where line a represents Example 1, line b represents Example 2, line c represents Example 3, and line d represents Example 4. Detailed Implementation

[0031] The following disclosure provides many different implementations or examples for different ways of implementing the present invention.

[0032] Example 1

[0033] (1) Mix 1g of microcrystalline cellulose with 0.5mol / L ferric chloride solution at a solid-liquid ratio of 1:25, and heat the beaker in a water bath or oil bath at 60℃ for 8 hours.

[0034] (2) Separate the precipitate from the mixture obtained after the reaction in step (1) by vacuum filtration or centrifugation. Add anhydrous ethanol with a solid-liquid ratio of 1:40 to microcrystalline cellulose and sodium acetate with a mass ratio of 1:5 to microcrystalline cellulose to the precipitate, and stir the mixture vigorously for 1 hour.

[0035] (3) The mixture obtained after the reaction in step (2) is transferred to a Teflon-lined stainless steel high-pressure reactor, and the reactor is heated to 180°C and maintained for 30 hours. Finally, the reactor is cooled to room temperature, and the product is washed with deionized water and anhydrous ethanol solution, and then freeze-dried to obtain cellulose nanocrystal-ferrite hybrid material.

[0036] Example 2

[0037] (1) Mix 1g of microcrystalline cellulose with 1 mol / L ferric chloride solution at a solid-liquid ratio of 1:50, and heat the beaker in a water bath or oil bath at 100℃ for 4 hours.

[0038] (2) Separate the precipitate from the mixture obtained after the reaction in step (1) by vacuum filtration or centrifugation. Add anhydrous ethanol with a solid-liquid ratio of 1:40 to microcrystalline cellulose and sodium acetate with a mass ratio of 1:5 to microcrystalline cellulose to the precipitate, and stir the mixture vigorously for 1 hour.

[0039] (3) The mixture obtained after the reaction in step (2) is transferred to a Teflon-lined stainless steel high-pressure reactor, and the reactor is heated to 180°C and maintained for 30 hours. Finally, the reactor is cooled to room temperature, and the product is washed with deionized water and anhydrous ethanol solution, and then freeze-dried to obtain cellulose nanocrystal-ferrite hybrid material.

[0040] Example 3

[0041] (1) Mix 1g of microcrystalline cellulose with 3mol / L ferric chloride solution at a solid-liquid ratio of 1:50, and heat the beaker in a water bath or oil bath at 60℃ for 8 hours.

[0042] (2) Separate the precipitate from the mixture obtained after the reaction in step (1) by vacuum filtration or centrifugation. Add anhydrous ethanol with a solid-liquid ratio of 1:40 to microcrystalline cellulose and sodium acetate with a mass ratio of 1:5 to microcrystalline cellulose to the precipitate, and stir the mixture vigorously for 1 hour.

[0043] (3) The mixture obtained after the reaction in step (2) was transferred to a Teflon-lined stainless steel high-pressure reactor, and the reactor was heated to 220°C and maintained for 20 hours. Finally, the reactor was cooled to room temperature, and the product was washed with deionized water and anhydrous ethanol solution, and then freeze-dried to obtain cellulose nanocrystal-ferrite hybrid material.

[0044] Example 4

[0045] (1) Mix 1g of microcrystalline cellulose with 1 mol / L ferric chloride solution at a solid-liquid ratio of 1:75, and heat the beaker in a water bath or oil bath at 100 ℃ for 4 hours.

[0046] (2) Separate the precipitate from the mixture obtained after the reaction in step (1) by vacuum filtration or centrifugation. Add anhydrous ethanol with a solid-liquid ratio of 1:70 to microcrystalline cellulose and sodium acetate with a mass ratio of 1:2 to microcrystalline cellulose to the precipitate, and stir the mixture vigorously for 2 hours.

[0047] (3) The mixture obtained after the reaction in step (2) is transferred to a Teflon-lined stainless steel high-pressure reactor, and the reactor is heated to 180°C and maintained for 30 hours. Finally, the reactor is cooled to room temperature, and the product is washed with deionized water and anhydrous ethanol solution, and then freeze-dried to obtain cellulose nanocrystal-ferrite hybrid material.

[0048] Comparative Example 1

[0049] This comparative example lacks step 1) of mixing with microcrystalline cellulose as in Example 1, while the remaining steps 2) and 3) are the same as in Example 1.

[0050] summary

[0051] from Figure 1 As can be seen from the data, in Comparative Example 1 without the participation of cellulose, the characteristic diffraction peaks at 24.2°, 33.2°, 35.6°, 40.9°, 49.5°, 50.1°, 57.5°, 62.4°, 63.9°, 71.8° and 75.4° are (012), (104), (110), (113), (024), (116), (018), (214), (113), (300), (1010) and (220) Fe2O3 crystal planes.

[0052] In Example 1, a characteristic peak at 22.4° corresponds to the cellulose type I (200) crystal plane. Characteristic diffraction peaks at 30.1°, 35.5°, 43.1°, 57.0°, and 62.5° correspond to the Fe3O4 crystal plane (JCPDS card number 88-3015), namely (220), (311), (400), (511), and (440), respectively, indicating that the sample obtained in Example 1 has a high-purity cubic spinel structure. In Comparative Example 1, without the participation of cellulose, the reducing power of the ethanol solution is very weak, and it cannot reduce the Fe... 3+ To Fe 2+ The conversion resulted in no Fe3O4 formation. However, in Example 1, a redox reaction occurred in the fibers during the reaction, causing some iron ions (Fe3O4) to be converted. 3+ ) reduced to ferrous ions (Fe 2+ ), thereby generating magnetic Fe3O4.

[0053] from Figure 2 As can be seen, the characteristic peak at 22.4° is the (200) crystal plane of cellulose type I. The characteristic diffraction peaks at 30.1°, 35.5°, 43.1°, 57.0°, and 62.5° are the (220), (311), (400), (511), and (440) Fe3O4 crystal planes (JCPDS card number 88-3015), respectively. With the increase of the solid-liquid ratio, the obtained sample is a high-purity cubic spinel structure Fe3O4, indicating that the crystal structure of Fe3O4 prepared under different solid-liquid ratios is similar.

[0054] from Figure 3 As can be seen from the above, the cellulose nanocrystal-ferrite hybrid material prepared in Example 4 of the present invention has good morphology. Using microcrystalline cellulose as a template carrier to load metal nanoparticles effectively prevents the aggregation of metal oxide particles.

[0055] from Figure 4 As can be seen, Examples 1-4 exhibit superparamagnetic behavior and low coercivity. The saturation magnetization curve increases with the increase of the external magnetic field, and its maximum saturation magnetization (Ms) value is approximately 22.1 emu·g. −1 . Figure 4 Examples 1-4 are shown to be highly sensitive to the applied magnetic field and are rapidly attracted under its influence. This phenomenon indicates that Examples 1-4 have a strong magnetic response.

[0056] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A method for preparing a magnetically responsive cellulose nanocrystal-ferrite hybrid material, characterized in that, Includes the following steps: 1) The cellulose raw material is mixed with an inorganic metal chloride solution and heated at 60-100°C, and the precipitate is collected. The inorganic metal chloride is one or more of ferric chloride, cobalt chloride, zinc chloride, lithium chloride and magnesium chloride. The concentration of the inorganic metal chloride solution is 0.1-10 mol / L. The ferric iron in the inorganic metal chloride accounts for 66.7%-100% of the total metal ions. The solid-liquid ratio of the cellulose raw material to the inorganic metal chloride solution is 1 g: (10-100) mL. The solid-liquid ratio of the cellulose raw material to the solvent is 1 g: (20-100) mL. 2) Dissolve the precipitate from step 1) in a solvent with a weakly basic reagent, and then carry out a reduction reaction at 150-250°C. Wash and dry to obtain the cellulose nanocrystal-ferrite hybrid material. The weakly basic reagent is at least one of sodium acetate, sodium tartrate, calcium acetate, or potassium acetate.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the cellulose raw material to the weakly alkaline reagent is 1:1 to 1:

10.

3. The preparation method according to claim 1 or 2, characterized in that, The solvent is selected from at least one of water, ethanol, ethylene glycol or glycerol.

4. The preparation method according to claim 1, characterized in that, The reduction reaction temperature in step 2) is 150–250°C, and the reaction time is 3–30 hours.

5. The application of the cellulose nanocrystal-ferrite hybrid material prepared by the preparation method according to any one of claims 1 to 4 in the preparation of magnetic catalytic materials, electromagnetic shielding materials, supercapacitor materials or gas-sensitive materials.

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