Method and system for preparing coal-based graphene quantum dots by magnetic confinement microwave plasma

Abstract

The application provides a coal-based graphene quantum dot magnetic confinement microwave plasma preparation method and system, relates to the graphene quantum dot preparation technical field, and comprises the following steps: pretreating coal raw materials, removing impurities and crushing the coal raw materials to a preset granularity; detecting coal quality parameters of the pretreated coal raw materials, wherein the coal quality parameters at least include the content of C, H and O elements; inputting the coal quality parameters into a QYOA algorithm for analysis to obtain adjustment parameters of microwave power and reaction gas; feeding the pretreated coal raw materials into a reaction cavity, and forming a three-dimensional confinement field in the reaction cavity through a magnetic confinement device; the application organically combines magnetic confinement, microwave plasma, the QYOA algorithm and ultrasonic post-treatment, forms a synergistic effect, promotes the dissociation of carbon clusters through the synergistic effect of magnetic confinement and microwave plasma, improves the yield of coal-based graphene quantum dots from less than 10% in the traditional method to more than 30%, improves production efficiency, and is conducive to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of graphene quantum dot preparation technology, and in particular to a magnetic confinement microwave plasma preparation method and system for coal-based graphene quantum dots. Background Technology

[0002] Coal-based graphene quantum dots, as a novel nanomaterial, possess excellent optical, electrical, and chemical properties, and have broad application prospects in fields such as biological imaging, sensors, and optoelectronic devices.

[0003] However, current methods for preparing coal-based graphene quantum dots suffer from the following drawbacks: traditional methods have low yields, typically less than 10%, making large-scale production difficult; the prepared quantum dots exhibit a wide particle size distribution with a standard deviation reaching 4.3 nm, affecting the stability and consistency of their performance; fluorescence performance is poor, quantum yield is low, and the emission color is singular, limiting their application in various fields; furthermore, existing methods cannot be dynamically adjusted according to the coal quality parameters of different coal types, resulting in poor adaptability. In addition, quantum dots are prone to agglomeration during the preparation process, further reducing product quality. Therefore, this invention proposes a magnetic confinement microwave plasma preparation method and system for coal-based graphene quantum dots to address the problems existing in the prior art. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a magnetic confinement microwave plasma preparation method and system for coal-based graphene quantum dots. This method and system promotes the dissociation of carbon clusters through the synergistic effect of magnetic confinement and microwave plasma, increasing the yield of coal-based graphene quantum dots from less than 10% in traditional methods to over 30%, thereby improving production efficiency and facilitating large-scale production.

[0005] To achieve the objectives of this invention, the following technical solution is employed: a method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma, comprising the following steps:

[0006] S1: Pre-treat the coal raw material to remove impurities and crush it to a preset particle size;

[0007] S2: Detect the coal quality parameters of the pretreated coal raw material. The coal quality parameters include at least the content of C, H and O elements.

[0008] S3: Input the coal quality parameters into the QYOA algorithm for analysis to obtain the adjustment parameters of microwave power and reaction gas;

[0009] S4: The pretreated coal raw material is sent into the reaction chamber, and a three-dimensional confinement field is formed in the reaction chamber through the magnetic confinement device;

[0010] S5: Introduce reaction gas into the reaction chamber and start the microwave plasma generator to generate microwave plasma, so that the coal raw material undergoes a dissociation reaction under the synergistic effect of magnetic confinement and microwave plasma.

[0011] S6: During the reaction process, based on the adjustment parameters obtained in S3, the magnetic field gradient and microwave power are coupled and adjusted in real time through a dynamic adjustment algorithm.

[0012] S7: After the reaction is complete, the product is subjected to ultrasonic post-treatment to obtain coal-based graphene quantum dots.

[0013] A further improvement is that, in S1, the preset particle size is 50-100 mesh.

[0014] A further improvement is made in S3, where the parsing process of the QYOA algorithm is implemented using the following formula:

[0015] P=k1×(Q×α+Y×β+O×γ+A×δ)+k2×(C×μ+H×ν+O×ξ)

[0016] G=m1×(Q×α+Y×β+O×γ+A×δ)+m2×(C×μ+H×ν+O×ξ)

[0017] Where P is the microwave power adjustment parameter, G is the reactant gas adjustment parameter; Q is the quantum yield target value, ranging from 28% to 31%; Y is the yield target value, ranging from 30% or higher; O is the optical performance coefficient, 0.3-0.4 for blue light and 0.5-0.6 for red light; A is the adaptability coefficient, ranging from 0.8 to 1.0; C, H, and O are the percentage contents of C, H, and O elements in the coal raw material, respectively; α, β, γ, and δ are weighting coefficients, and α + β + γ + δ = 1, where α takes values ​​of 0.25-0.3, β takes values ​​of 0.25-0.3, γ takes values ​​of 0.2-0.25, and δ takes values ​​of 0.2-0.25; μ, ν, and ξ are element influence coefficients, with μ taking values ​​of 0.4-0.5, ν taking values ​​of 0.2-0.3, and ξ taking values ​​of 0.2-0.3; k1 and k2 are microwave power correction coefficients, with k1 taking values ​​of 500-1000 and k2 taking values ​​of 1-5; m1 and m2 are reaction gas correction coefficients, with m1 taking values ​​of 30-60 and m2 taking values ​​of 0.5-2.

[0018] A further improvement is made in S5, where the reaction gas is a mixture of inert gas and hydrogen, wherein the volume ratio of inert gas to hydrogen is (3-5):1.

[0019] A further improvement is made in S6, where the dynamic adjustment algorithm monitors the plasma state parameters within the reaction chamber in real time and, in conjunction with the adjustment parameters obtained in S3, uses the following formula to adjust the magnetic field gradient and microwave power based on feedback:

[0020]

[0021] Among them, B t The magnetic field gradient at the current moment. P is the magnetic field gradient at the previous moment. t The current microwave power. θ represents the microwave power at the previous moment, n is the coupling coefficient with a value ranging from 0.02 to 0.05, and θ is the plasma state correction coefficient with a value ranging from 0.9 to 1.1.

[0022] A further improvement is that, in S7, the frequency of ultrasonic treatment is 40kHz and the treatment time is 30-60 minutes.

[0023] A magnetic confinement microwave plasma system based on coal-based graphene quantum dots includes a pretreatment module, a coal quality detection module, a QYOA algorithm processing module, a reaction module, a control module, and an ultrasonic post-processing module. The pretreatment module pre-treats the coal raw material, removing impurities and pulverizing it to a preset particle size. The coal quality detection module detects the content of C, H, and O elements in the pre-treated coal raw material. The QYOA algorithm processing module receives the coal quality parameters sent by the coal quality detection module and uses the QYOA algorithm to analyze and obtain the microwave power and adjustment parameters for the reaction gas.

[0024] The reaction module includes a reaction cavity, a magnetic confinement device, and a microwave plasma generator. The magnetic confinement device is used to form a three-dimensional confinement field within the reaction cavity, and the microwave plasma generator is used to emit microwaves into the reaction cavity to generate microwave plasma. The control module receives adjustment parameters sent by the QYOA algorithm processing module and controls the magnetic field gradient of the magnetic confinement device and the microwave power of the microwave plasma generator through a dynamic adjustment algorithm to achieve real-time coupling between the two. The ultrasonic post-processing module is used to perform ultrasonic processing on the products output by the reaction module.

[0025] A further improvement is that the pretreatment module includes a crushing device and a screening device, wherein the crushing device is used to crush the coal raw material, and the screening device is used to screen out the coal raw material with a preset particle size.

[0026] A further improvement is that the magnetic confinement device includes multiple electromagnetic coils, which are evenly distributed on the outside of the reaction chamber.

[0027] A further improvement is that the reaction module also includes a gas delivery device, which is used to deliver reaction gas into the reaction chamber.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. This invention organically combines magnetic confinement, microwave plasma, QYOA algorithm and ultrasonic post-processing to form a synergistic effect. Through the synergistic effect of magnetic confinement and microwave plasma, the dissociation of carbon clusters is promoted, and the yield of coal-based graphene quantum dots is increased from less than 10% in traditional methods to more than 30%, which improves production efficiency and is conducive to large-scale production.

[0030] 2. This invention employs a dynamic adjustment algorithm to achieve real-time coupling of magnetic field gradient and microwave power, effectively controlling the growth of quantum dots and reducing the standard deviation of quantum dot particle size to below 1.5 nm, far superior to the 4.3 nm of traditional methods, ensuring the stability and consistency of product performance; the quantum yield of the product reaches 28%-31%, which is more than 50% higher than that of traditional methods, and achieves multi-color tunability such as blue and red light, with good stability over a wide pH range, meeting the application needs of multiple fields.

[0031] 3. This invention uses the QYOA algorithm to analyze the coal quality parameters (C / H / O content) of different coal types and dynamically adjusts the microwave power and reaction gas, enabling the system to adapt to the preparation requirements of different coal types, thus expanding the application range. By using the magnetic mirror effect to construct a three-dimensional confinement field and combining it with 40kHz ultrasonic post-processing, the aggregation of quantum dots is effectively suppressed, ensuring the uniformity at the nanoscale and improving product quality. Attached Figure Description

[0032] Figure 1 This is a flowchart of the method of the present invention;

[0033] Figure 2 This is a system composition diagram of the present invention. Detailed Implementation

[0034] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0035] Example 1

[0036] according to Figure 1 , 2 As shown in the figure, this embodiment proposes a method and system for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma. The specific steps are as follows:

[0037] Bituminous coal was selected as the raw material. This bituminous coal has a high carbon content and low ash content. It was crushed and screened to 80 mesh through a pretreatment module to remove impurities.

[0038] The C, H, and O content of the bituminous coal was determined using a coal quality testing module (elemental analyzer) and found to be 82%, 4%, and 14%, respectively.

[0039] The detected coal quality parameters are input into the QYOA algorithm processing module, and the microwave power adjustment parameter is obtained as 850W, and the flow rate adjustment parameter of the reaction gas (a mixture of argon and hydrogen with a volume ratio of 4:1) is 55sccm.

[0040] The pretreated bituminous coal is fed into the reaction chamber, and the magnetic confinement device is activated. A three-dimensional confinement field is formed by multiple electromagnetic coils distributed around the outer periphery of the reaction chamber, with a magnetic field strength gradient of 55 G / cm.

[0041] Start the gas delivery device and introduce reaction gas into the reaction chamber according to the adjusted parameters. At the same time, start the microwave plasma generator to generate microwave plasma, so that the bituminous coal undergoes a dissociation reaction under the synergistic effect of magnetic confinement and microwave plasma.

[0042] During the reaction, the control module adjusts the magnetic field gradient and microwave power in real time through a dynamic adjustment algorithm based on the adjusted parameters.

[0043] After the reaction proceeded for 35 minutes, the product was sent to the ultrasonic post-processing module and treated with an ultrasonic frequency of 40 kHz for 50 minutes to obtain coal-based graphene quantum dots.

[0044] The obtained coal-based graphene quantum dots were tested, and the results are as follows: the yield was 33%; the standard deviation of particle size was 1.0 nm; the quantum yield was 31%; they could emit blue and red light and had good stability in the pH range of 2-10.

[0045] Example 2

[0046] according to Figure 1 , 2 As shown in the figure, this embodiment proposes a method and system for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma. The specific steps are as follows:

[0047] Lignite was selected as the raw material. This lignite has a high hydrogen and oxygen content. It was prepared following a similar procedure to that in Example 1, with the following specific differences:

[0048] After pretreatment, the sample is screened to 70 mesh.

[0049] The C, H, and O content of the lignite was determined using an elemental analyzer to be 65%, 6%, and 29%, respectively.

[0050] The coal quality parameters were input into the QYOA algorithm processing module, and the microwave power adjustment parameter was obtained as 750W, and the flow rate adjustment parameter of the reaction gas (a mixture of argon and hydrogen with a volume ratio of 3:1) was 45sccm.

[0051] The magnetic field strength gradient of the three-dimensional confinement field formed by the magnetic confinement device is 45 G / cm.

[0052] After the reaction proceeded for 40 minutes, the product was sent to the ultrasonic post-processing module and treated with an ultrasonic frequency of 40 kHz for 55 minutes.

[0053] Test results: The yield was 31%; the standard deviation of particle size was 1.3 nm; the quantum yield was 29%; it could emit blue and red light and had good stability in the pH range of 2-10.

[0054] Example 3

[0055] according to Figure 1 , 2 As shown in the figure, this embodiment proposes a method and system for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma. The specific steps are as follows:

[0056] Anthracite was selected as the raw material because it has an extremely high carbon content and low volatile matter.

[0057] After pretreatment, the sample is screened to 90 mesh.

[0058] The elemental analyzer detected the C, H, and O content, which were 92%, 2%, and 6%, respectively.

[0059] The QYOA algorithm analysis yielded a microwave power adjustment parameter of 900W and a flow rate adjustment parameter of 60sccm for the reaction gas (a mixture of argon and hydrogen in a volume ratio of 5:1).

[0060] The magnetic field intensity gradient of the three-dimensional confined field is 60 G / cm.

[0061] After the reaction proceeded for 30 minutes, the mixture was sonicated for 40 minutes.

[0062] Test results: The yield was 32%; the standard deviation of particle size was 1.1 nm; the quantum yield was 30%; it could emit blue and red light and had good stability in the pH range of 2-10.

[0063] Validation data:

[0064]

[0065] Based on the above data, the coal-based graphene quantum dots prepared by this invention for different coal types (bituminous coal, lignite, and anthracite) are significantly superior to traditional methods in terms of yield, particle size uniformity, and fluorescence performance. Furthermore, it can adapt to the characteristics of different coal types and possesses effectiveness, superiority, and wide applicability.

[0066] This invention organically combines magnetic confinement, microwave plasma, the QYOA algorithm, and ultrasonic post-processing to form a synergistic effect. Through the combined action of magnetic confinement and microwave plasma, the dissociation of carbon clusters is promoted, increasing the yield of coal-based graphene quantum dots from less than 10% using traditional methods to over 30%, thus improving production efficiency and facilitating large-scale production. Furthermore, this invention employs a dynamic adjustment algorithm to achieve real-time coupling of the magnetic field gradient and microwave power, effectively controlling the growth of quantum dots and reducing the standard deviation of the quantum dot size to below 1.5 nm, far superior to the 4.3 nm of traditional methods, ensuring the stability and consistency of product performance. The quantum yield of the product reaches 28%-31%, an improvement of over 50% compared to traditional methods, and achieves multi-color tunability (blue, red, etc.), exhibiting good stability over a wide pH range, meeting the application needs of multiple fields. In addition, the present invention uses the QYOA algorithm to analyze the coal quality parameters (C / H / O content) of different coal types and dynamically adjusts the microwave power and reaction gas, so that the system can adapt to the preparation requirements of different coal types, thus expanding the application range. The invention also utilizes the magnetic mirror effect to construct a three-dimensional confinement field, combined with 40kHz ultrasonic post-processing, to effectively suppress the aggregation of quantum dots, ensure the uniformity at the nanoscale, and improve product quality.

[0067] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma, characterized in that, Includes the following steps: S1: Pre-treat the coal raw material to remove impurities and crush it to a preset particle size; S2: Detect the coal quality parameters of the pretreated coal raw material. The coal quality parameters include at least the content of C, H and O elements. S3: Input the coal quality parameters into the QYOA algorithm for analysis to obtain the adjustment parameters for microwave power and reactant gases. The analysis process of the QYOA algorithm is achieved through the following formula: ， ， Wherein, P is the microwave power adjustment parameter, G is the reactant gas adjustment parameter; Q is the quantum yield target value, ranging from 28% to 31%; Y is the yield target value, ranging from 30% or higher; Op is the optical performance coefficient, with 0.3-0.4 for blue light and 0.5-0.6 for red light; A is the adaptability coefficient, ranging from 0.8 to 1.0; C, H, and O are the percentage contents of C, H, and O elements in the coal raw material, respectively. These are the weighting coefficients, and Where α takes values ​​from 0.25 to 0.3, The value ranges from 0.25 to 0.

3. The value ranges from 0.2 to 0.

25. Values ​​range from 0.2 to 0.25; The element influence coefficient. The value ranges from 0.4 to 0.

5. The value ranges from 0.2 to 0.

3. The value ranges from 0.2 to 0.3; k1 and k2 are microwave power correction coefficients, with k1 ranging from 500 to 1000 and k2 ranging from 1 to 5; m1 and m2 are reaction gas correction coefficients, with m1 ranging from 30 to 60 and m2 ranging from 0.5 to 2. S4: The pretreated coal raw material is sent into the reaction chamber, and a three-dimensional confinement field is formed in the reaction chamber through the magnetic confinement device; S5: Introduce reaction gas into the reaction chamber and start the microwave plasma generator to generate microwave plasma, so that the coal raw material undergoes a dissociation reaction under the synergistic effect of magnetic confinement and microwave plasma. S6: During the reaction process, based on the adjustment parameters obtained in S3, the magnetic field gradient and microwave power are coupled and adjusted in real time through a dynamic adjustment algorithm. S7: After the reaction is complete, the product is subjected to ultrasonic post-treatment to obtain coal-based graphene quantum dots.

2. The method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma according to claim 1, characterized in that: In S1, the preset particle size is 50-100 mesh.

3. The method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma according to claim 1, characterized in that: In step S5, the reaction gas is a mixture of inert gas and hydrogen, wherein the volume ratio of inert gas to hydrogen is (3-5):

1.

4. The method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma according to claim 1, characterized in that: In step S6, the dynamic adjustment algorithm monitors the plasma state parameters within the reaction chamber in real time and, in conjunction with the adjustment parameters obtained in step S3, uses the following formula to adjust the magnetic field gradient and microwave power: ， in, The magnetic field gradient at the current moment. This represents the magnetic field gradient at the previous moment. The current microwave power. Let n be the microwave power at the previous moment, and n be the coupling coefficient, with a value ranging from 0.02 to 0.

05. This is the plasma state correction factor, with a value ranging from 0.9 to 1.

1.

5. The method for preparing coal-based graphene quantum dots using magnetic confinement microwave plasma according to claim 1, characterized in that: In step S7, the frequency of ultrasonic treatment is 40 kHz, and the treatment time is 30-60 minutes.

6. A magnetically confined microwave plasma system for coal-based graphene quantum dots, applied to the magnetically confined microwave plasma preparation method for coal-based graphene quantum dots according to any one of claims 1-5, characterized in that: It includes a pretreatment module, a coal quality detection module, a QYOA algorithm processing module, a reaction module, a control module, and an ultrasonic post-processing module. The pretreatment module is used to pretreat the coal raw material, remove impurities, and pulverize it to a preset particle size. The coal quality detection module is used to detect the coal quality parameters—the content of C, H, and O elements—of the pretreated coal raw material. The QYOA algorithm processing module is used to receive the coal quality parameters sent by the coal quality detection module and obtain the microwave power and reaction gas adjustment parameters through the QYOA algorithm. The reaction module includes a reaction cavity, a magnetic confinement device, and a microwave plasma generator. The magnetic confinement device is used to form a three-dimensional confinement field within the reaction cavity, and the microwave plasma generator is used to emit microwaves into the reaction cavity to generate microwave plasma. The control module receives adjustment parameters sent by the QYOA algorithm processing module and controls the magnetic field gradient of the magnetic confinement device and the microwave power of the microwave plasma generator through a dynamic adjustment algorithm to achieve real-time coupling between the two. The ultrasonic post-processing module is used to perform ultrasonic processing on the products output by the reaction module.

7. The magnetic confinement microwave plasma system based on coal-based graphene quantum dots according to claim 6, characterized in that: The pretreatment module includes a crushing device and a screening device. The crushing device is used to crush the coal raw material, and the screening device is used to screen out the coal raw material with a preset particle size.

8. The magnetic confinement microwave plasma system based on coal-based graphene quantum dots according to claim 6, characterized in that: The magnetic confinement device includes multiple electromagnetic coils, which are evenly distributed on the outside of the reaction chamber.

9. The magnetic confinement microwave plasma system based on coal-based graphene quantum dots according to claim 6, characterized in that: The reaction module also includes a gas delivery device, which is used to deliver reaction gas into the reaction chamber.

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