A graphitized carbon material, a preparation method and application thereof

Abstract

The application belongs to the technical field of material application, and particularly relates to a graphitized carbon material and a preparation method and application thereof, the preparation method of the graphitized carbon material is as follows: (1) D-(+)-xylose powder and transition metal salt powder are weighed and uniformly ground; (2) after sieving, calcination is carried out under an inert gas atmosphere; (3) after grinding and sieving of the calcined product, washing is carried out with 1.0 mol / L dilute hydrochloric acid solution, then washing is carried out with distilled water and drying is carried out, to obtain the graphitized carbon material, the graphitized carbon material has high adsorption efficiency on aflatoxin B1 (AFB1) in vegetable oil, and in combination with magnetic solid phase extraction (MSPE) and high performance liquid chromatography-fluorescence detection (HPLC-FLD) technology, the detection limit is as low as 2.0 pg·g ‑1 The graphitized carbon material has excellent regeneration performance, and the material consumption and cost in the detection process are significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of materials application technology, specifically relating to a graphitized carbon material, its preparation method, and its application. Background Technology

[0002] Aflatoxins (AFs) are a class of potent carcinogenic mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus, commonly contaminating crops such as soybeans, peanuts, and sesame. Due to insufficient preventative measures during crop cultivation and storage, as well as unfavorable climatic conditions such as high humidity and excessive rainfall, the risk of AF contamination in crop oils is gradually increasing. Therefore, developing sensitive methods for the detection of aflatoxins in crop oils is of great significance. However, unlike aqueous matrices, the detection of AFs in crop oils faces complex sample pretreatment challenges due to their high fatty acid content and non-polar environment.

[0003] Magnetic solid-phase extraction (MSPE) is a pretreatment technique for oil-based samples that achieves efficient phase separation through an external magnetic field, offering significant advantages over traditional solid-phase extraction (SPE) in processing high-viscosity oil samples. However, the efficiency and reusability of existing magnetic composite materials in MSPE are limited, such as insufficient adsorption capacity and poor anti-interference properties. Therefore, developing adsorbent materials with high adsorption capacity and excellent regeneration performance to improve the detection efficiency of aerosols (AFs) in oil samples has become a critical issue that urgently needs to be addressed.

[0004] Carbon materials, due to their high electrical conductivity, excellent chemical stability, and unique microstructure, have shown great application potential in environmental treatment, energy storage, and advanced electronic devices. By introducing heteroatoms or composite matrices, the properties of carbon materials can be precisely controlled, endowing them with high specific surface area, large porosity, tunable structure, and multifunctionality; these properties make carbon materials ideal pollutant adsorbents. However, although carbon materials perform well in aqueous or polar solvent systems, their performance in non-polar environments remains limited, mainly due to the weakening of electrostatic interactions and hydrogen bonding effects. Therefore, developing carbon adsorbent materials for non-polar environments is crucial. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing graphitized carbon material (HGC). Based on the transition metal-assisted carbonization process strategy, by selecting D-(+)-xylose as a carbon source and combining it with transition metal salts such as iron, cobalt, and nickel, graphitized carbon material (HGC) with excellent adsorption performance is prepared through steps such as high-temperature calcination.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing graphitized carbon material includes the following steps:

[0008] (1) Weigh D-(+)-xylose powder and transition metal salt powder, and grind them thoroughly into a uniform mixture;

[0009] (2) After sieving the mixture from step (1), calcine it under an inert gas atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a heating rate and held for 1 hour, followed by a heating rate of 10°C / min. -1 Heat to 750℃~850℃ at a heating rate, hold at that temperature for 3h~4h, and then let it cool naturally to room temperature;

[0010] (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution, then wash it with distilled water, and dry it to obtain graphitized carbon material.

[0011] In a preferred example, in step (1), the mass ratio of D-(+)-xylose powder to transition metal salt powder is 4:1.

[0012] In a preferred example, in step (1), the transition metal salt powder is selected from one of FeCl3·6H2O, CoCl2·6H2O, and NiCl2·6H2O.

[0013] In a preferred example, in step (1), the transition metal salt powder is selected as FeCl3·6H2O.

[0014] In a preferred example, in step (2), the inert gas is argon.

[0015] Based on a general inventive concept, another object of this invention is to provide a graphitized carbon material prepared by the above method and its application in the detection of aflatoxin B1 in vegetable oils. The graphitized carbon material FeO / Fe3O4 / HGC is used for magnetic solid-phase extraction of aflatoxin B1 in vegetable oils, combined with high-performance liquid chromatography-fluorescence detection for quantitative analysis of aflatoxin B1, with a detection limit as low as 2.0 pg·g⁻¹. -1 .

[0016] While existing solid-phase extraction (SPE) methods using carbon materials have advanced application value for the detection of aflatoxin B1 (AFB1) in aqueous food matrices, they exhibit significant analytical challenges in the high fatty acid concentration and non-polar environment of the oil phase. This invention proposes a highly graphitized carbon material (HGC) with enhanced π-π interactions for AFB1 extraction from the oil phase through a simple transition metal-assisted carbonization process. Adsorption experiments show that the AFB1 adsorption capacity of FeO / Fe3O4 / HGC is 1179.99 μg·g. -1The adsorption rate was significantly higher than that of Ni / HGC and Co / HGC (nearly 4 times) and pure carbon materials (nearly 6 times). Density functional theory (DFT) calculations revealed the mechanism, indicating that the electronic defect characteristics of the graphitized carbon structure supported by FeO / Fe3O4 magnetic clusters significantly enhanced the π-π interaction with AFB1. In addition, pore filling and hydrophobic interactions also contributed to the adsorption of AFB1.

[0017] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0018] (1) High efficiency adsorption performance: The highly graphitized carbon material (HGC) prepared by the transition metal assisted carbonization process has significantly enhanced π-π interaction, excellent pore filling and hydrophobic interaction, and can achieve high efficiency adsorption of aflatoxin B1 (AFB1) in complex oil phase matrix. Its adsorption capacity is significantly higher than that of traditional carbon materials.

[0019] (2) Sensitive detection capability: The detection limit is as low as 2.0 pg·g when magnetic solid phase extraction (MSPE) and high performance liquid chromatography-fluorescence detection (HPLC-FLD) are combined. -1 The recovery rate is between 96.0% and 104.4%, which can meet the sensitivity requirements for the detection of trace pollutants and is suitable for the quantitative analysis of AFB1 in complex vegetable oil matrices.

[0020] (3) Simple and efficient preparation method: D-(+)-xylose is used as a carbon source and combined with transition metal salts. It is prepared by a simple high-temperature carbonization process. It has the characteristics of simple operation, strong scalability and environmental friendliness. The prepared carbon material has excellent regeneration performance and significantly reduces material consumption and cost in the detection process.

[0021] This invention demonstrates for the first time the crucial role of enhanced π-π chemical bond interactions between molecules in the detection of contaminants in complex oil matrices, providing important theoretical and technical support for the development of efficient and sensitive detection technologies for oil-phase matrix contaminants. Attached Figure Description

[0022] Figure 1 SEM images of FeO / Fe3O4 / HGC;

[0023] Figure 2 In the figure, (a) shows the adsorption kinetics of AFB1 on FeO / Fe3O4 / HGC, Co / HGC, Ni / HGC and D-Xyl-C; (b) shows the adsorption isotherm experiments of AFB1 on FeO / Fe3O4 / HGC, Co / HGC, Ni / HGC and D-Xyl-C.

[0024] Figure 3The linear relationship between AFB1 concentration and the integral area of ​​AFB1 chromatographic peak;

[0025] Figure 4 The included curves are: HPLC chromatograms of FeO / Fe3O4 / HGC on real rapeseed oil samples, and FeO / Fe3O4 / HGC on samples spiked with 10.0 pg·g⁻¹. -1 HPLC chromatogram of rapeseed oil sample AFB1, FeO / Fe3O4 / HGC assay for the addition of 100.0 pg·g -1 HPLC chromatogram of rapeseed oil sample AFB1, FeO / Fe3O4 / HGC assay for the addition of 250.0 pg·g -1 HPLC chromatogram of rapeseed oil sample AFB1. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is further described in conjunction with specific embodiments. However, this invention is not limited to these embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. In this invention, unless otherwise specified, all parts and percentages are units of mass, and the equipment and raw materials used are commercially available or commonly used in the art. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art.

[0027] The terms “comprising,” “including,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0028] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether such range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range.

[0029] This invention discloses a method for preparing graphitized carbon materials based on a transition metal-assisted carbonization strategy, comprising the following steps:

[0030] (1) Weigh D-(+)-xylose powder and transition metal salt powder, and grind them thoroughly into a uniform mixture;

[0031] (2) After sieving the mixture from step (1), calcine it under an inert gas atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a rising rate and held for 1 hour to remove water of crystallization and adsorbed water, followed by a heating rate of 10°C / min. -1 Heat to 750℃~850℃ at a heating rate, hold at that temperature for 3h~4h, and then let it cool naturally to room temperature;

[0032] (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution to remove free metal particles and impurities, then wash it with distilled water and dry it to obtain graphitized carbon material.

[0033] In a preferred example, the mass ratio of D-(+)-xylose powder to transition metal salt powder is 4:1.

[0034] In a preferred example, in step (1), the transition metal salt powder is selected from one of FeCl3·6H2O, CoCl2·6H2O, and NiCl2·6H2O.

[0035] In a preferred example, in step (1), the transition metal salt powder is FeCl3·6H2O.

[0036] In a preferred example, in step (2), the inert gas is argon.

[0037] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] Example 1

[0039] (1) Weigh 4.0g of D-(+)-xylose powder and 1.0g of FeCl3·6H2O powder respectively, and grind them thoroughly in a mortar into a uniform mixture;

[0040] (2) After sieving the mixture from step (1), calcine it under an argon atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a rising rate and held for 1 hour to remove water of crystallization and adsorbed water, followed by a heating rate of 10°C / min. -1 The temperature was increased to 800℃ at a certain rate, held at that temperature for 4 hours, and then allowed to cool naturally to room temperature.

[0041] (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution to remove free metal particles and impurities, then wash it with distilled water and dry it to obtain graphitized carbon material FeO / Fe3O4 / HGC.

[0042] The morphology of the graphitized carbon material FeO / Fe3O4 / HGC prepared in Example 1 was characterized. Scanning electron microscopy (SEM) images of FeO / Fe3O4 / HGC showed a quasi-spherical structure with an average diameter of approximately 5 μm, and its surface was densely covered with metal nanoparticles (such as...). Figure 1 (As shown); the interaction between transition metal ions with empty d orbitals and lone pairs of electrons on oxygen atoms in D-(+)-xylose promotes the formation of a homogeneous and thermally stable mixture, which affects the resulting structure and adsorption properties.

[0043] Example 2

[0044] (1) Weigh 4.0g of D-(+)-xylose powder and 1.0g of CoCl2·6H2O powder respectively, and grind them thoroughly in a mortar into a uniform mixture;

[0045] (2) After sieving the mixture from step (1), calcine it under an argon atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a rising rate and held for 1 hour to remove water of crystallization and adsorbed water, followed by a heating rate of 10°C / min. -1 The temperature was increased to 800℃ at a certain rate, held at that temperature for 4 hours, and then allowed to cool naturally to room temperature.

[0046] (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution to remove free metal particles and impurities, then wash it with distilled water and dry it to obtain graphitized carbon material Co / HGC.

[0047] Example 3

[0048] (1) Weigh 4.0g of D-(+)-xylose powder and 1.0g of NiCl2·6H2O powder respectively, and grind them thoroughly in a mortar into a uniform mixture;

[0049] (2) After sieving the mixture from step (1), calcine it under an argon atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a rising rate and held for 1 hour to remove water of crystallization and adsorbed water, followed by a heating rate of 10°C / min. -1 The temperature was increased to 800℃ at a certain rate, held at that temperature for 4 hours, and then allowed to cool naturally to room temperature.

[0050] (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution to remove free metal particles and impurities, then wash it with distilled water and dry it to obtain graphitized carbon material Ni / HGC.

[0051] Feasibility study of detection strategies

[0052] ① Disperse 1 mg of FeO / Fe3O4 / HGC powder in 10 mL of 120 ng·L⁻¹ −1 The samples were placed in AFB1 solution and subjected to shaking for varying times, ranging from 1 min to 120 min. After shaking, the supernatant was collected using a 0.22 μm filter membrane for high-performance liquid chromatography-fluorescence detection.

[0053] ② Disperse 1 mg of FeO / Fe3O4 / HGC powder in 10 mL of different initial concentrations (1 ng·mL). -1 ~180 ng·mL -1 The solution was added to an AFB1 solution. The solution was shaken at room temperature for 30 min, and the supernatant was collected using a 0.22 μm filter membrane for high-performance liquid chromatography-fluorescence detection.

[0054] ③ Add 4.0 mg FeO / Fe3O4 / HGC powder and 20.0 mL of AFB1 solution of different concentrations to a 50.0 mL centrifuge tube. Shake the mixture for 8 min using a vibrator, then place a magnet at the bottom of the tube to separate the supernatant. Next, add 1.0 mL of DMF solution as eluent and shake the mixture again for 5 min. Collect the eluent within 1 min under an external magnetic field. Filter the collected solution through a 0.22 μm organic phase membrane and then perform high-performance liquid chromatography-fluorescence detection.

[0055] The adsorption results of the above experiment ① are as follows Figure 2 As shown in (a), FeO / Fe3O4 / HGC exhibits high extraction efficiency, reaching adsorption equilibrium within 12–15 min. The adsorption of AFB1 by FeO / Fe3O4 / HGC follows a pseudo-second-order model, indicating that the adsorption process of AFB1 by the material is mainly controlled by chemisorption. Furthermore, the adsorption results of experiment ② above are as follows... Figure 2 As shown in (b), the adsorption isotherm of FeO / Fe3O4 / HGC is in excellent agreement with the Langmuir model, exhibiting a value of 1179.99 μg·g. -1 The maximum adsorption capacity. The high surface area, porous structure, and multivalent metal components of FeO / Fe3O4 / HGC contribute to its strong interaction with AFB1, improving its adsorption performance. Based on experiment ③, a standard curve was plotted using AFB1 concentration as the x-axis and the integrated area of ​​the AFB1 chromatographic peak as the y-axis (e.g., Figure 3 As shown in the figure, the linear detection range and detection limit of the MSPE-HPLC-FLD method established in this invention for AFB1 were calculated to be 5.0 pg·g⁻¹. -1 ~1000.0 pg·g -1 and 2.0 pg·g -1This demonstrates that this method can indeed achieve highly sensitive detection of AFB1.

[0056] Reliability verification experiment of the standard curve

[0057] To evaluate the feasibility of the MSPE-HPLC-FLD method constructed in this invention for detecting AFB1 in real samples, the spiked recovery rate of AFB1 in real vegetable oil samples was studied using this method.

[0058] The preparation method of spiked samples is as follows: First, collect rapeseed oil from two different brands and divide them into several parts; then, add different concentrations of AFB1 in sequence, and then filter them to remove insoluble impurities. The filtrate obtained is used as the spiked sample for subsequent experiments.

[0059] Table 1. Recovery and relative standard deviation of AFB1 (n=6) in spiked samples

[0060]

[0061] The results are shown in Table 1 above. This method showed good recovery rates (96.0%–104.4%) for spiked samples. The HPLC chromatogram of FeO / Fe3O4 / HGC for real rapeseed oil-2 samples is shown below. Figure 4 As shown, the MSPE-HPLC-FLD method constructed in this invention has good application prospects in the detection of AFB1.

[0062] This invention establishes a highly efficient and sensitive quantitative analysis method for trace AFB1 in vegetable oils by combining solid-phase extraction based on FeO / Fe3O4 / HGC with high-performance liquid chromatography-fluorescence detector (HPLC-FLD), with a detection limit as low as 2.0 pg·g -1 The recovery rate was 96.0%–104.4%. This invention meets the sensitivity requirements for trace contaminant detection and provides an efficient tool for the detection of AFB1 in vegetable oils, which is of great significance for ensuring food safety.

[0063] The above embodiments are merely preferred embodiments of the present invention. Any simple modifications, alterations, and substitutions made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. The application of a graphitized carbon material in the detection of aflatoxin B1 in vegetable oils, characterized in that, Aflatoxin B1 in vegetable oils was quantitatively analyzed using magnetic solid-phase extraction with graphitized carbon material FeO / Fe3O4 / HGC, combined with high-performance liquid chromatography-fluorescence detection, with a detection limit as low as 2.0 pg·g⁻¹. -1 ; The preparation method of graphitized carbon materials includes the following steps: (1) Weigh D-(+)-xylose powder and transition metal salt powder, and grind them thoroughly into a uniform mixture; the mass ratio of D-(+)-xylose powder to transition metal salt powder is 4:1, and the transition metal salt powder is FeCl3·6H2O; (2) After sieving the mixture from step (1), calcine it under an argon atmosphere: first at 2℃·min -1 The temperature was increased to 250°C at a heating rate and held for 1 hour, followed by heating at a rate of 10°C / min. -1 Heat to 750℃~850℃ at a heating rate, hold at that temperature for 3h~4h, and then let it cool naturally to room temperature; (3) Grind and sieve the magnetic black powder after calcination in step (2), then wash it with 1.0 mol / L dilute hydrochloric acid solution, then wash it with distilled water, and dry it to obtain graphitized carbon material.

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