Preparation method and application of biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material

Abstract

The invention relates to the technical field of comprehensive development and utilization of lignosulfonate and development of novel anti-electromagnetic radiation materials, and discloses a preparation method and application of a biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material. Firstly, iron ions and cobalt ions are adsorbed in a molecular structure of sodium lignosulfonate through electrostatic attraction; then, the biochar / CoFe2O4 composite material is prepared through a high-temperature carbonization treatment one-step method. The anti-electromagnetic radiation material prepared by the invention has both electrical loss and magnetic loss, and has better anti-electromagnetic radiation performance. Lignosulfonate used in the preparation method is low in price and easy to obtain, complex processes and use of a large amount of solvents are avoided in the material preparation process, and the method is economical and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of comprehensive development and utilization of lignin sulfonate and the technical field of development of new anti-electromagnetic radiation materials, and in particular to a biochar / CoFe 2 O 4 Preparation method and application of double-loss anti-electromagnetic radiation material. Background Art

[0002] Electromagnetic radiation pollution has become one of the pollutions in contemporary society. The electromagnetic radiation that affects the human living environment is mainly divided into natural electromagnetic radiation pollution sources and man-made electromagnetic radiation pollution sources. Long-term exposure to electromagnetic radiation will affect the human immune system, reproductive system, cardiovascular system, etc. through thermal effects, non-thermal effects and cumulative effects, induce diseases such as decreased immunity and hearing loss, and electromagnetic radiation will affect aircraft navigation systems, television and network signals, etc. Therefore, the demand for anti-electromagnetic radiation materials with light weight, wide absorption bandwidth and high absorption efficiency is becoming more and more urgent.

[0003] Traditional absorbing materials mainly include iron-based absorbing materials, carbon-based absorbing materials, ceramic-based absorbing materials, etc., which can absorb and lose electromagnetic waves and electromagnetic radiation through dielectric loss, resistance loss and magnetic loss. 2 O 4 Ferrite has a wide range of application prospects in the field of microwave absorption due to its excellent magnetic properties, chemical stability, unique structure and other advantages. However, the dielectric loss of ferrite material is small, its absorption band is narrow, and the specific gravity of ferrite material is large, which limits its practical application. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention provides a biochar / CoFe 2 O 4 Preparation method and application of double-loss anti-electromagnetic radiation material, by mixing sodium lignin sulfonate with CoFe 2 O 4 Precursor composite, one-step carbonization method to prepare biochar / CoFe 2 O 4 Double-loss anti-electromagnetic radiation material. On the one hand, the present invention realizes the recycling of sodium lignin sulfonate, a waste of papermaking, and the low-cost green and environmentally friendly preparation of new anti-electromagnetic radiation materials; on the other hand, it can broaden the absorption bandwidth of ferrite materials and reduce the specific gravity of composite materials, thereby broadening the application range of ferrites.

[0005] Technical solution: On the one hand, the present invention provides a biochar / CoFe 2 O 4 The method for preparing a double-loss anti-electromagnetic radiation material is characterized by comprising the following steps: S1. Electrostatic adsorption of metal ions on sodium lignin sulfonate: Sodium lignin sulfonate was dissolved in deionized water, and then cobalt chloride hexahydrate and ferric chloride hexahydrate were added for electrostatic adsorption; then, tartaric acid was added and the pH value of the solution was adjusted to 5-7. After being placed in a constant temperature water bath and stirred for evaporation to form a gel, it was dried to obtain a honeycomb dry gel, which is sodium lignin sulfonate / CoFe 2 O 4 Precursor; S2. Sodium lignin sulfonate / CoFe 2 O 4 Carbonization heat treatment of the precursor: the sodium lignin sulfonate / CoFe 2 O 4 The precursor is carbonized and heat treated in a nitrogen atmosphere and cooled naturally to obtain biochar / CoFe 2 O 4 Double loss anti-electromagnetic radiation material.

[0006] Furthermore, in S1, the mass ratio of the sodium lignin sulfonate, cobalt chloride hexahydrate and ferric chloride hexahydrate is 3:1-10:2-20.

[0007] Furthermore, in S1, the adsorption time of the electrostatic adsorption is 0.5 to 3 h.

[0008] Furthermore, in S1, the amount of tartaric acid added is 25% to 75% of the total amount of the metal ions.

[0009] Furthermore, in S1, the temperature of the constant temperature water bath is 70-80°C.

[0010] Furthermore, in S1, the specific conditions of the drying are: drying temperature: 80-120° C.; drying time: 20-30 hours.

[0011] Furthermore, in S2, the specific conditions of the carbonization heat treatment are: a heating rate of 5 to 20°C / min, a maximum temperature of 600 to 900°C, and a holding time of 1 to 4h.

[0012] Preferably, in S1, the sodium lignin sulfonate is sodium lignin sulfonate washed with deionized water and dried.

[0013] In another aspect, the present invention provides a biochar / CoFe 2 O 4 Application of double-loss anti-electromagnetic radiation materials in anti-electromagnetic radiation.

[0014] The preparation principle of the present invention is as follows: The present invention adopts a one-step carbonization method to realize biochar / CoFe 2 O4 Preparation of dual-loss anti-electromagnetic radiation material: First, iron ions and cobalt ions are adsorbed into the molecular structure of sodium lignin sulfonate through electrostatic attraction; then, biochar / CoFe is prepared in one step by high-temperature carbonization treatment. 2 O 4 Composite material. Sodium lignin sulfonate is an anionic surfactant. Its aqueous solution is negatively charged and has a strong ability to adsorb metal ions. Therefore, cobalt ions and iron ions can be adsorbed by it. Then, it is subjected to high-temperature carbonization treatment. In a nitrogen atmosphere, lignin sulfonate is converted into biochar, and cobalt ions and iron ions react with the chelating agent to generate CoFe 2 O 4 Ferrites, dispersed in the biochar structure, form biochar / CoFe 2 O 4 Anti-electromagnetic radiation material.

[0015] In the present invention, lignin sulfonate is carbonized and composited with ferrite, so that the composite anti-electromagnetic radiation material has both dielectric loss and magnetic loss, increases the loss form, broadens the absorption band of the ferrite material, and enhances its absorption efficiency. Furthermore, after carbonization of lignin sulfonate, biochar is formed, and ferrite nanoparticles are evenly distributed in the biochar structure. The composite material finally formed has the advantage of light weight, which expands the scope of use of ferrite materials. The anti-electromagnetic radiation material can be used in the fields of stealth coating, electronic communications, new energy vehicles, etc.

[0016] Beneficial effect: Compared with the prior art, the present invention adopts a one-step carbonization method to prepare biochar / CoFe 2 O 4 Double loss anti-electromagnetic radiation material has the following advantages: 1) The sodium lignin sulfonate used in the present invention is an extract of papermaking waste liquid, the raw material is easily available, the ingredients are safe and environmentally friendly, and the preparation cost is low. In addition, the preparation process does not involve the use of a large amount of solvents, is economical and environmentally friendly, the technology is simple, and it is easy to operate, and can achieve low-cost, green and environmentally friendly preparation of anti-electromagnetic radiation materials.

[0017] 2) The present invention adopts a one-step carbonization method to prepare the anti-electromagnetic radiation material. The sodium lignin sulfonate is carbonized while the ferrite is crystallized, which saves energy and has a simple process.

[0018] 3) Ferrite nanoparticles are evenly distributed in the microspheres formed after the carbonization of sodium lignin sulfonate, forming a multiphase interface and increasing the interfacial polarization of the composite material, thereby increasing the dielectric loss of the composite material, improving its wave absorbing performance, and further improving its anti-electromagnetic radiation performance.

[0019] 4) Ferrite is combined with biochar to prepare composite materials, which can reduce the specific gravity of the composite materials.

[0020] 5) In the current domestic and foreign papers, patents and other documents, no one has carbonized sodium lignin sulfonate and combined it with ferrite to prepare anti-electromagnetic radiation materials. The applicant uses green and environmentally friendly sodium lignin sulfonate as a biocarbon source, which not only solves the problem of recycling sodium lignin sulfonate, but also can prepare new anti-electromagnetic radiation materials with high absorption efficiency and low specific gravity. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 Biochar / CoFe in Implementation Example 1 2 O 4 XRD pattern of Figure 2 Biochar / CoFe in Implementation Example 1 2 O 4 The curve of reflectivity changing with frequency. DETAILED DESCRIPTION

[0022] The present invention is described in detail below in conjunction with the embodiments.

[0023] Implementation 1: (1) Pretreatment of sodium lignin sulfonate: First, 3 g of sodium lignin sulfonate was dissolved in 150 mL of deionized water, filtered after 2 h to remove impurities and suspended matter, and dried for later use.

[0024] (2) Electrostatic adsorption of metal ions on sodium lignin sulfonate: 3 g of sodium lignin sulfonate was dissolved in 150 mL of deionized water. After it was fully dissolved, 1.0135 g of cobalt chloride hexahydrate and 2.3059 g of ferric chloride hexahydrate were added in sequence. The reaction time of metal ions and sodium lignin sulfonate was 1 h. The solution was then heated to 50 °C, and tartaric acid (0.9596 g) was added as a complexing agent so that the ratio of the amount of tartaric acid to the total amount of metal cations in the solution was 1:2. After adjusting the pH value to about 5 with ammonia water, the solution was placed in a constant temperature water bath at 70-80 °C, heated and evaporated under constant stirring to form a gel, and then placed in a drying oven at 110 °C for 24 h to transform into a honeycomb dry gel.

[0025] (3) Sodium lignin sulfonate / CoFe 2 O 4 Carbonization heat treatment of precursor: Sodium lignin sulfonate / CoFe 2 O 4 The precursor was loaded into an alumina ark and placed in a tube furnace. In a nitrogen atmosphere, the temperature was raised to 700 °C at a heating rate of 5 °C / min and kept at this temperature for 1 h. After the carbonization reaction was completed, it was naturally cooled to room temperature to obtain biochar / CoFe 2 O 4 Anti-electromagnetic radiation material.

[0026] Implementation 2: (1) Pretreatment of sodium lignin sulfonate: First, 1 g of sodium lignin sulfonate was dissolved in 50 mL of deionized water, filtered after 2 h to remove impurities and suspended matter, and dried for later use.

[0027] (2) Electrostatic adsorption of metal ions on the surface of sodium lignin sulfonate: 1g of sodium lignin sulfonate was dissolved in 150mL of deionized water. After it was fully dissolved, 1.0135g of cobalt chloride hexahydrate and 2.3059g of ferric chloride hexahydrate were added in sequence. The reaction time of metal ions and sodium lignin sulfonate was 1h. Then the solution was heated to 50℃, and tartaric acid (0.9596g) was added as a complexing agent so that the ratio of the amount of tartaric acid to the total amount of metal cations in the solution was 1:2. After adjusting the pH value to about 5 with ammonia water, the solution was placed in a constant temperature water bath at 70-80℃, heated and evaporated under constant stirring to form a gel, and then placed in a drying oven at 110℃ for 24 hours to transform into a honeycomb dry gel.

[0028] (3) Sodium lignin sulfonate / CoFe 2 O 4 Carbonization heat treatment of precursor: Sodium lignin sulfonate / CoFe 2 O 4 The precursor was loaded into an alumina ark and placed in a tube furnace. In a nitrogen atmosphere, the temperature was raised to 700 °C at a heating rate of 5 °C / min and kept at this temperature for 1 h. After the carbonization reaction was completed, it was naturally cooled to room temperature to obtain biochar / CoFe 2 O 4 Anti-electromagnetic radiation material.

[0029] Implementation 3: (1) Pretreatment of sodium lignin sulfonate: First, 1 g of sodium lignin sulfonate was dissolved in 50 mL of deionized water, filtered after 2 h to remove impurities and suspended matter, and dried for later use.

[0030] (2) Electrostatic adsorption of metal ions on the surface of sodium lignin sulfonate: 1g of sodium lignin sulfonate was dissolved in 150mL of deionized water. After it was fully dissolved, 3.0405g of cobalt chloride hexahydrate and 6.9177g of ferric chloride hexahydrate were added in sequence. The reaction time of metal ions and sodium lignin sulfonate was 1h. Then the solution was heated to 50℃, and tartaric acid (2.8788g) was added as a complexing agent so that the ratio of the amount of tartaric acid to the total amount of metal cations in the solution was 1:2. After adjusting the pH value to about 5 with ammonia water, the solution was placed in a constant temperature water bath at 70-80℃, heated and evaporated under constant stirring to form a gel, and then placed in a drying oven at 110℃ for 24 hours to transform into a honeycomb dry gel.

[0031] (3) Sodium lignin sulfonate / CoFe 2 O 4Carbonization heat treatment of precursor: Sodium lignin sulfonate / CoFe 2 O 4 The precursor was loaded into an alumina ark and placed in a tube furnace. In a nitrogen atmosphere, the temperature was raised to 700 °C at a heating rate of 5 °C / min and kept at this temperature for 1 h. After the carbonization reaction was completed, it was naturally cooled to room temperature to obtain biochar / CoFe 2 O 4 Anti-electromagnetic radiation material.

[0032] The material prepared in Embodiment 1 of the present invention was characterized, and the results are as follows: Figure 1 Biochar / CoFe in Implementation Example 1 2 O 4 XRD spectrum. As can be seen from the figure, CoFe appears in the XRD spectrum. 2 O 4 The characteristic diffraction peaks of CoFe 2 O 4 In addition, a small amount of diffraction peaks of biochar appeared in the XRD spectrum, indicating that at this carbonization temperature, a small amount of biochar crystallized. This shows that the present invention successfully synthesized biochar / CoFe 2 O 4 Composite materials.

[0033] Biochar / CoFe 2 O 4 The anti-electromagnetic radiation performance can be evaluated by the reflectivity of the material to electromagnetic waves. Figure 2 Biochar / CoFe in Implementation Example 1 2 O 4 The curve of reflectivity of anti-electromagnetic radiation material changing with frequency. As can be seen from the figure, biochar / CoFe 2 O 4 When the thickness is 3.0mm and 4.0mm, the minimum reflectivity value reaches -25dB. 2 O 4 The bandwidth less than -5dB reaches 7GHz, showing a large bandwidth. It is worth pointing out that when the thickness is 2.0mm, the biocarbon / CoFe 2 O 4 The reflectivity at 13-18 GHz is less than -5 dB, showing a strong ability to absorb electromagnetic waves, indicating that the biochar / CoFe 2 O 4 It can be used in the absorption of high-frequency electromagnetic radiation. 2 O 4 The composite material exhibits good electromagnetic wave absorption ability and has great application potential as an anti-electromagnetic radiation material.

[0034] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material, characterized in that: The following steps are involved: S1. Electrostatic adsorption of metal ions on sodium lignin sulfonate: Sodium lignin sulfonate is dissolved in deionized water, and then cobalt chloride hexahydrate and ferric chloride hexahydrate are added for electrostatic adsorption; subsequently, tartaric acid is added, and the pH value of the solution is adjusted to 5-7, and the solution is placed in a constant temperature water bath, stirred and evaporated to form a gel, and then dried to obtain a honeycomb dry gel, which is a sodium lignin sulfonate / CoFe2O4 precursor; S2. Carbonization heat treatment of sodium lignin sulfonate / CoFe2O4 precursor: The sodium lignin sulfonate / CoFe2O4 precursor is carbonized and heat treated in a nitrogen atmosphere, and naturally cooled to obtain a biochar / CoFe2O4 double-loss anti-electromagnetic radiation material.

2. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S1, the mass ratio of the sodium lignin sulfonate, cobalt chloride hexahydrate and ferric chloride hexahydrate is 3:1-10:2-20.

3. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S1, the adsorption time of the electrostatic adsorption is 0.5 to 3 hours.

4. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S1, the added amount of the tartaric acid is 25% to 75% of the total amount of the metal ions.

5. The method for preparing the biochar / CoFe2O4 double-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S1, the temperature of the constant temperature water bath is 70-80°C.

6. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S1, the specific conditions of the drying are: drying temperature: 80-120°C; drying time: 20-30h.

7. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to claim 1, characterized in that: In S2, the specific conditions of the carbonization heat treatment are: a heating rate of 5 to 20°C / min, a maximum temperature of 600 to 900°C, and a holding time of 1 to 4 hours.

8. The method for preparing the biochar / CoFe2O4 dual-loss anti-electromagnetic radiation material according to any one of claims 1 to 7, characterized in that: In S1, the sodium lignin sulfonate is the sodium lignin sulfonate that has been washed with deionized water and dried.

9. Use of the biochar / CoFe2O4 double-loss anti-electromagnetic radiation material according to the method as described in any one of claims 1 to 8 in anti-electromagnetic radiation.

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