Preparation method and application of MgFe2O4 / coal gasification fine slag composite material

Abstract

The invention discloses a preparation method and application of a MgFe2O4 / coal gasification fine slag composite material, and the preparation method comprises the following steps: dissolving a divalent magnesium source and a trivalent iron source which can be dissolved in ethylene glycol according to a molar ratio of 1: 2 in ethylene glycol to obtain a solution A; taking 50-70 mL of the solution A, then adding 0.4-0.6 g of hexadecyl trimethyl ammonium bromide and 0.5-0.7 g of coal gasification fine slag, and carrying out uniform ultrasonic dispersion to obtain a solution B; and gradually dropwise adding alkali liquor into the solution B, continuously stirring in the process of dropwise adding the alkali liquor, stopping stirring when the pH value of the solution B reaches 10.5-11.5, then putting the obtained mixture into a 100mL high-pressure reaction kettle, heating to 160-190 DEG C in a closed manner, keeping the temperature for 10-15 hours, then cooling, washing and drying the obtained precipitate, thereby obtaining the MgFe2O4 / coal gasification fine slag composite material. According to the invention, the defects in the prior art are overcome, the resource utilization of the waste coal gasification fine slag is realized, and the preparation cost of the electromagnetic wave absorbing material is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of new material preparation methods, and in particular to a preparation method and application of a MgFe2O4 / coal gasification fine slag composite material. Background Art

[0002] With the advancement of science and technology and the widespread application of microwave technology, the use of electromagnetic waves in wireless communications and high-frequency circuits has become increasingly common, resulting in the ubiquity of electromagnetic waves of various intensities and frequencies. The resulting electromagnetic pollution and electromagnetic interference pose a potential threat to human health, the operation of precision instruments and information security. However, the existing technology is mostly conducive to the preparation of electromagnetic wave absorbing materials (abbreviated as: absorbing materials) with relatively high-cost raw materials (such as graphene, rare earth metals, etc.), and the entire preparation process is relatively cumbersome and costly. Summary of the invention

[0003] The purpose of the present invention is to provide a preparation method and application of a MgFe2O4 / coal gasification fine slag composite material, thereby overcoming the shortcomings of the prior art.

[0004] In order to solve the above problems, the technical scheme adopted by the method for preparing the MgFe2O4 / coal gasification fine slag composite material of the present invention is as follows:

[0005] The preparation method of the MgFe2O4 / coal gasification fine slag composite material comprises the following steps:

[0006] A divalent magnesium source and a trivalent iron source soluble in ethylene glycol are dissolved in ethylene glycol at a molar ratio of 1:2 to obtain a solution A;

[0007] Take 50mL-70mL of solution A, then add 0.4g-0.6g of hexadecyltrimethylammonium bromide and 0.5g-0.7g of coal gasification fine slag, and disperse evenly by ultrasonication to obtain solution B;

[0008] Alkali solution was gradually added dropwise to solution B, and stirring was continued during the process of adding the alkali solution. When the pH value of solution B reached 10.5-11.5, stirring was stopped, and then the obtained mixture was placed in a 100 mL high pressure reactor, sealed and heated to 160° C.-190° C., and kept warm for 10 h-15 h, and then cooled. The obtained precipitate was washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material.

[0009] Wherein, the divalent magnesium source is MgCl2·6H2O, and the trivalent iron source is FeCl3·6H2O.

[0010] Wherein, the concentration of the divalent magnesium source in solution A is 30mmol / L-70mmol / L.

[0011] Wherein, the alkali solution is a sodium hydroxide solution with a concentration of 1mmol / L-3mmol / L.

[0012] Wherein, the MgFe2O4 nanoparticles in the MgFe2O4 / coal gasification fine slag composite material are uniformly compounded on the surface of the lamellar coal gasification fine slag;

[0013] Among them, the size range of MgFe2O4 nanoparticles is 5-10nm.

[0014] The MgFe2O4 / coal gasification fine slag composite material prepared by the invention can be applied to wave absorbing materials.

[0015] Compared with the prior art, the implementation effects of the present invention are as follows:

[0016] 1. The present invention controls the particle size of MgFe2O4 in the prepared composite material by designing the preparation method of the MgFe2O4 / coal gasification fine slag composite material and selecting the raw materials, effectively avoiding the problem of MgFe2O4 agglomeration during the preparation of the MgFe2O4 / coal gasification fine slag composite material, improving the uniformity of the composite material, and simplifying the preparation process.

[0017] 2. The present invention designs a MgFe2O4 / coal gasification slag composite material, utilizes the coal gasification slag of coal gasification waste in combination with magnetic MgFe2O4 nanoparticles, so that the MgFe2O4 / coal gasification slag composite material has excellent electromagnetic wave absorption ability, realizes the resource utilization of waste coal gasification slag, and effectively reduces the preparation cost of electromagnetic wave absorption material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The X-ray diffraction pattern of the MgFe2O4 / coal gasification fine slag composite material of Example 4-6;

[0019] Figure 2 are scanning electron microscope photos of the MgFe2O4 / coal gasification fine slag composite materials of Examples 4-6, wherein a and d are scanning electron microscope photos of S1, b and e are scanning electron microscope photos of S1, and c and f are scanning electron microscope photos of S1;

[0020] Figure 3 is a transmission electron microscope picture of S2;

[0021] Figure 4 It is the electromagnetic wave loss capacity diagram of S1;

[0022] Figure 5 It is the electromagnetic wave loss capacity diagram of S2;

[0023] Figure 6 This is the electromagnetic wave loss capability diagram of S3. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The coal gasification fine slag used in the present invention has a carbon content of 53.62wt%, a volatile content of 3.33wt%, and an inorganic content of 43.05wt%, and its main inorganic components are:

[0026]

[0027] Example 1

[0028] MgCl2·6H2O and FeCl3·6H2O were dissolved in ethylene glycol at a molar ratio of 1:2 to obtain solution A, in which Mg 2+ The concentration is 30mmol / L; 50mL of solution A is taken, and then 0.4g of hexadecyltrimethylammonium bromide and 0.5g of coal gasification fine slag are added, and solution B is obtained after ultrasonic dispersion. A sodium hydroxide solution with a concentration of 1mmol / L is gradually added dropwise to solution B, and stirring is continuously performed during the addition of the sodium hydroxide solution. When the pH value of solution B reaches 9, stirring is stopped, and the obtained mixture is placed in a 100mL high-pressure reactor, sealed and heated to 160°C, and kept warm for 15h, and then cooled. The obtained precipitate is washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material.

[0029] Example 2

[0030] MgCl2·6H2O and FeCl3·6H2O were dissolved in ethylene glycol at a molar ratio of 1:2 to obtain solution A, in which Mg 2+ The concentration is 70mmol / L; 70mL of solution A is taken, and then 0.6g of hexadecyltrimethylammonium bromide and 0.7g of coal gasification fine slag are added, and solution B is obtained after ultrasonic dispersion. A sodium hydroxide solution with a concentration of 3mmol / L is gradually added dropwise to solution B, and stirring is continuously performed during the addition of the sodium hydroxide solution. When the pH value of solution B reaches 11, stirring is stopped, and the obtained mixture is placed in a 100mL high-pressure reactor, sealed and heated to 190°C, and kept warm for 10h, and then cooled. The obtained precipitate is washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material.

[0031] Example 3

[0032] MgCl2·6H2O and FeCl3·6H2O were dissolved in ethylene glycol at a molar ratio of 1:2 to obtain solution A, in which Mg 2+ The concentration is 60mmol / L; 70mL of solution A is taken, and then 0.55g of hexadecyltrimethylammonium bromide and 0.65g of coal gasification fine slag are added, and solution B is obtained after ultrasonic dispersion. A sodium hydroxide solution with a concentration of 2mmol / L is gradually added dropwise to solution B, and stirring is continuously performed during the addition of the sodium hydroxide solution. When the pH value of solution B reaches 10.5, stirring is stopped, and the obtained mixture is placed in a 100mL high-pressure reactor, sealed and heated to 170°C, and kept warm for 14h, and then cooled. The obtained precipitate is washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material.

[0033] Example 4

[0034] MgCl2·6H2O and FeCl3·6H2O were dissolved in ethylene glycol at a molar ratio of 1:2 to obtain solution A, in which Mg 2+ The concentration is 40mmol / L; 60mL of solution A is taken, and then 0.5g of hexadecyltrimethylammonium bromide and 0.6g of coal gasification fine slag are added, and solution B is obtained after ultrasonic dispersion. A sodium hydroxide solution with a concentration of 2mmol / L is gradually added to solution B, and stirring is continuously performed during the addition of the sodium hydroxide solution. When the pH value of solution B reaches 10, stirring is stopped, and the obtained mixture is placed in a 100mL high-pressure reactor, sealed and heated to 180°C, and kept warm for 12h, and then cooled. The obtained precipitate is washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material, which is marked as S1.

[0035] Example 5

[0036] The difference from Example 4 is that Mg 2+ The concentration was 50 mmol / L, and a MgFe2O4 / coal gasification fine slag composite material was obtained, marked as S2.

[0037] Example 6

[0038] The difference from Example 4 is that Mg 2+ The concentration was 67 mmol / L, and a MgFe2O4 / coal gasification fine slag composite material was obtained, marked as S3.

[0039] The crystal structure of the MgFe2O4 / coal gasification fine slag composite material of Examples 4-6 was analyzed by X-ray diffraction technology in the range of 20°-80°, with a scanning rate of 2° / min. The surface morphology, microstructure and element distribution of the composite material were studied by scanning electron microscopy and transmission electron microscopy. The elemental composition and chemical state of the composite material were determined by X-ray photoelectron spectroscopy. The MgFe2O4 / coal gasification fine slag composite material was mixed with paraffin in a mass ratio of 6:4, and pressed into a ring shape (outer diameter 7.00mm, inner diameter 3.04mm) by a mold. The electromagnetic parameters of the MgFe2O4 / coal gasification fine slag composite material were tested by a vector network analyzer, and the measurement frequency range was 2.0GHz-18.0GHz. The absorption capacity of electromagnetic waves was calculated by electromagnetic parameters, and the formula is as follows:

[0040]

[0041] Z in is the input impedance of the material, f, d and c are frequency, matching layer thickness and light speed respectively, μ r and ε r are the magnetic permeability and dielectric constant of the material respectively.

[0042] The test results of Examples 4-6 are shown in 1-6. Figure 1-2 As shown, the X-ray diffraction patterns of S1-S3 correspond to the standard card JCPDS#88-1936 of MgFe2O4, and the MgFe2O4 nanoparticles are evenly compounded on the surface of coal gasification fine slag. The present invention successfully prepares the MgFe2O4 / coal gasification fine slag composite material. Figure 3 It can be seen that the particle size range of the MgFe2O4 / coal gasification fine slag composite material prepared by the present invention is 5-10nm. Figure 4-6 It is shown in the figure that the MgFe2O4 / coal gasification fine slag composite material prepared by the present invention has excellent loss capacity for electromagnetic waves in the range of 8GHz-12GHz. Among them, when the fitting thickness of the S2 composite material is 2.1mm, the frequency band range (EAB) in which the electromagnetic wave loss exceeds 90% is 7.16GHz-10.94GHz, covering most of the X-band (8-12GHz) electromagnetic waves, showing excellent electromagnetic wave absorption capacity; in addition, when the fitting thickness of the S3 composite material is 1.6mm, the maximum reflection loss value (RL min ) reached -71.33dB.

[0043] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a MgFe2O4 / coal gasification fine slag composite material, characterized in that: The following steps are involved: A divalent magnesium source and a trivalent iron source soluble in ethylene glycol are dissolved in ethylene glycol at a molar ratio of 1:2 to obtain a solution A; Take 50mL-70mL of solution A, then add 0.4g-0.6g of hexadecyltrimethylammonium bromide and 0.5g-0.7g of coal gasification fine slag, and disperse evenly by ultrasonication to obtain solution B; Alkali solution was gradually added dropwise to solution B, and stirring was continued during the process of adding the alkali solution. When the pH value of solution B reached 10.5-11.5, stirring was stopped, and then the obtained mixture was placed in a 100 mL high pressure reactor, sealed and heated to 160° C.-190° C., and kept warm for 10 h-15 h, and then cooled. The obtained precipitate was washed and dried to obtain a MgFe2O4 / coal gasification fine slag composite material.

2. The method for preparing the MgFe2O4 / coal gasification fine slag composite material according to claim 1, characterized in that: The divalent magnesium source is MgCl2·6H2O, and the trivalent iron source is FeCl3·6H2O.

3. The method for preparing the MgFe2O4 / coal gasification fine slag composite material according to claim 1, characterized in that: The concentration of the divalent magnesium source in solution A is 30 mmol / L-70 mmol / L.

4. The method for preparing the MgFe2O4 / coal gasification fine slag composite material according to claim 1, characterized in that: The alkali solution is a sodium hydroxide solution with a concentration of 1mmol / L-3mmol / L.

5. The method for preparing the MgFe2O4 / coal gasification fine slag composite material according to claim 1, characterized in that: In the MgFe2O4 / coal gasification fine slag composite material, the MgFe2O4 nanoparticles are evenly compounded on the surface of the lamellar coal gasification fine slag.

6. The method for preparing the MgFe2O4 / coal gasification fine slag composite material according to claim 1, characterized in that: The size of MgFe2O4 nanoparticles in the MgFe2O4 / coal gasification fine slag composite material ranges from 5 to 10 nm.

7. The MgFe2O4 / coal gasification fine slag composite material prepared by the method according to any one of claims 1 to 6, characterized in that: Application in absorbing materials.

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