A sulfur-modified flash graphene and its preparation method

Abstract

This application discloses a method for preparing sulfur-modified flash graphene, belonging to the field of graphene production technology. The method involves first mixing sulfate with biomass and drying it, followed by pyrolysis and carbonization to obtain sulfur-modified carbon; then subjecting the sulfur-modified carbon to Joule flash evaporation to obtain flash graphene; the mass ratio of sulfate to biomass is 1–6:10; during the Joule flash evaporation process, the voltage is 100–250V, and the flash evaporation time is 8–12s. This application achieves in-situ sulfur doping in the carbon framework through impregnation pyrolysis to form sulfur-modified carbon. The sulfur-modified carbon is then subjected to Joule flash evaporation, where instantaneous ultra-high temperature achieves carbon atom rearrangement, generating a graphene structure. A sulfur-doped precursor is constructed using "sulfate impregnation of biomass," and the "instantaneous ultra-high temperature characteristics of Joule flash evaporation" achieve highly graphitized and porous carbon structures while retaining a high sulfur doping content, thus obtaining sulfur-modified flash graphene for high-performance adsorption applications.

Description

Technical Field

[0001] This application relates to the field of graphene production technology, and in particular to a sulfur-modified flash graphene and its preparation method. Background Technology

[0002] While traditional activated carbon boasts a large specific surface area, it suffers from limited adsorption capacity, poor selectivity, and difficulty in regeneration, and its specific binding capacity for heavy metal ions is insufficient. Common sulfur-doped modified carbon materials exhibit several drawbacks: sulfur is easily lost during high-temperature processing, making precise control of the doping form and content difficult. Furthermore, sulfur-doped carbon obtained through traditional pyrolysis methods often exhibits low graphitization, poor conductivity, and underdeveloped pore structures, limiting the exposure of adsorption sites and mass transfer efficiency. Traditional graphene preparation methods (such as CVD and redox methods) are costly, have low yields, and consume significant energy, making large-scale production of adsorbents for environmental remediation challenging.

[0003] Chinese patent application 201811337328.7 discloses a method for preparing a graphene metal ion adsorbent. The method disclosed in this application includes the following steps: (1) adding graphene to a dopamine solution to obtain polydopamine-modified graphene; (2) Polydopamine-modified graphene was added to a 3-mercaptopropionic acid solution, and graphene metal ion adsorbent was obtained after separation and washing.

[0004] The scheme points out that its water-graphene material has good dispersibility and can quickly and with high capacity adsorb metal ions; however, as mentioned above, if unmodified carbon materials are used, their adsorption capacity is relatively insufficient. Therefore, compared with the above scheme, further sulfur modification can theoretically further improve the adsorption capacity of metal ions. Furthermore, Chinese patent application 202110152454.0 discloses a biomimetic fiber functional material, its preparation method, and its application. The material is rich in multiple adsorption sites (N, O, S). The material is obtained by blending polyethyleneimine polymers modified with three multifunctional groups with carboxylated nanocellulose and graphene oxide, followed by coaxial spinning using a spider-like spinning principle, and then using post-crosslinking technology. The material has a multilayer structure with nanocellulose as the skeleton, graphene oxide as the outer layer, and polyethyleneimine polymers modified with three multifunctional groups as the inner layer, and the connection between each layer is a chemical bond. However, further observation of the above scheme reveals that it uses sulfur to modify the polymer material rather than directly modifying the graphene.

[0005] The problem this solution aims to solve is: how to provide a flash graphene material with good metal ion adsorption capacity. Summary of the Invention

[0006] This application aims to provide a flash graphene material with good metal ion adsorption capacity. The graphene material is highly graphitized and porous, while retaining a high sulfur doping content, and has good metal ion adsorption capacity.

[0007] To achieve the above objectives, this application discloses a method for preparing sulfur-modified flash graphene, comprising the following steps: Step 1: Mix sulfate with biomass and dry it, then pyrolyze and carbonize it to obtain sulfur-modified char. Step 2: The sulfur-modified carbon is subjected to Joule flash evaporation to obtain flash graphene; The mass ratio of sulfate to biomass is 1 to 6:10; During the Joule flash evaporation process, the voltage is 100–250V and the flash evaporation time is 8–12s.

[0008] Preferably, the biomass is selected from at least one of bamboo powder, corn stalks, rice straw, and sugarcane bagasse.

[0009] Preferably, the sulfate is selected from at least one of ferrous sulfate, zinc sulfate, and copper sulfate.

[0010] Preferably, step 1 specifically involves mixing sulfate and biomass at a mass ratio of 1 to 6:10, drying the mixture, and then pyrolyzing and carbonizing it at 500 to 700°C for 1 to 2 hours under a nitrogen atmosphere to obtain sulfur-modified carbon.

[0011] Preferably, in step 1, the mixture of dried sulfate and biomass is heated to 500-700°C at a heating rate of 5-10°C / min to obtain sulfur-modified carbon.

[0012] Preferably, step 2 specifically involves: placing the sulfur-modified carbon obtained in step 1 in a quartz glass tube, placing graphite electrodes and copper wires on both sides, and rapidly reacting them through Joule flash evaporation to generate sulfur-modified flash graphene. The external resistance of the flash evaporation equipment is 3-8Ω, and the voltage conditions for flash graphene preparation are 100-250V, with a time of 8-12s.

[0013] Preferably, the biomass is a mixture of bamboo powder and corn stalks, and the mass ratio of bamboo powder to corn stalks is 2 to 4:1.

[0014] In addition, this application also discloses a sulfur-modified flash graphene, which is prepared by the above-described method for preparing sulfur-modified flash graphene.

[0015] The beneficial effects of this application are: This application achieves in-situ sulfur doping in the carbon framework through impregnation pyrolysis, forming sulfur-modified carbon. The sulfur-modified carbon is then subjected to Joule flash evaporation, where instantaneous ultra-high temperature causes carbon atom rearrangement, generating a graphene structure. A sulfur-doped precursor is constructed using "sulfate impregnation of biomass." Furthermore, by leveraging the "instantaneous ultra-high temperature characteristics of Joule flash evaporation," a high sulfur doping level is maintained while achieving a highly graphitized and porous carbon structure, thus producing a high-performance... , Adsorbed sulfur-modified flash graphene. Attached Figure Description

[0016] Figure 1 The Raman spectrum of the sulfur-modified flash graphene prepared in Example 8; Figure 2 The Raman spectrum of the sulfur-modified flash graphene prepared in Example 9; Figure 3 The image shows the Raman spectrum of the sulfur-modified flash graphene prepared in Example 2. Detailed Implementation

[0017] The present invention will now be clearly and completely described in conjunction with embodiments thereof. It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0018] It should be noted that the source information of the raw materials used in the following embodiments and comparative examples is shown in Table 1: Table 1: Raw Material Source Information Example 1 Step 1: Mix ferrous sulfate and bamboo powder at a mass ratio of 1:10 and dry them under nitrogen. After drying, heat the mixture to 500℃ at a heating rate of 5℃ / min for 2 hours to obtain sulfur-modified carbon. Step 2: Place the sulfur-modified carbon obtained in Step 1 in a quartz glass tube, and place graphite electrodes and copper wires on both sides. The sulfur-modified flash graphene is generated by rapid reaction through Joule flash evaporation. The external resistance of the flash evaporation equipment is 3Ω, and the voltage condition for flash graphene preparation is 100V and the time is 8s.

[0019] Example 2 Step 1: Mix ferrous sulfate and bamboo powder at a mass ratio of 3:10 and dry them under nitrogen. After drying, heat the mixture to 700℃ at a heating rate of 10℃ / min for 1 hour to obtain sulfur-modified carbon. Step 2: Place the sulfur-modified carbon obtained in Step 1 in a quartz glass tube, and place graphite electrodes and copper wires on both sides. The sulfur-modified flash graphene is generated by rapid reaction through Joule flash evaporation. The external resistance of the flash evaporation equipment is 8Ω, and the voltage conditions for flash graphene preparation are 250V and the time is 12s.

[0020] Example 3 Step 1: Mix ferrous sulfate and bamboo powder at a mass ratio of 6:10 and dry them under nitrogen. After drying, heat the mixture to 600℃ at a heating rate of 8℃ / min for 1.5h to obtain sulfur-modified carbon. Step 2: Place the sulfur-modified carbon obtained in Step 1 in a quartz glass tube, and place graphite electrodes and copper wires on both sides. The sulfur-modified flash graphene is generated by rapid reaction through Joule flash evaporation. The external resistance of the flash evaporation equipment is 5Ω, and the voltage condition for flash graphene preparation is 150V and the time is 10s.

[0021] Example 4 It is basically the same as Example 2, except that corn stalks are used instead of bamboo powder.

[0022] Example 5 It is basically the same as Example 2, except that a mixture of corn stalks and bamboo powder is used instead of bamboo powder, and the mass ratio of corn stalks to bamboo powder is 1:3.

[0023] Example 6 It is basically the same as Example 2, except that zinc sulfate is used instead of ferrous sulfate.

[0024] Example 7 It is basically the same as Example 2, except that a mixture of ferrous sulfate and zinc sulfate is used instead of ferrous sulfate, and the mass ratio of ferrous sulfate to zinc sulfate is 1:0.25.

[0025] Performance testing 1. Metal ion adsorption test The sulfur-modified flash-evaporated graphene prepared in Examples 1-7 and commercially available honeycomb activated carbon for wastewater treatment were subjected to performance tests. Each adsorbent group (100 mg of each) was placed in 250 ml of lead-containing solution. Wastewater containing chromium ( The adsorption rate of metal ions in the wastewater was tested at room temperature for 24 hours. The test results are shown in Table 1. In addition, it should be noted that lead-containing ( The wastewater has a lead ion concentration of 100 mg / L, a pH value of 6, and contains chromium ( The chromium ion concentration in the wastewater is 100 mg / L, and the pH value is 7. Table 1: Metal Ion Adsorption Test Table Therefore, it can be seen that the various embodiments of the present invention are effective against heavy metal ions. and In the adsorption treatment, all showed excellent and stable adsorption performance. Among them, Example 3, due to its relatively high sulfate addition, resulted in a greater distribution of sulfur-containing functional groups on its surface, thus leading to a higher metal ion adsorption capacity; Furthermore, observing Examples 2 and 4-7 reveals that Example 5 exhibits the most outstanding performance, demonstrating superior efficacy. and The adsorption rates reached high levels of 94.36% and 92.42%, respectively, significantly exceeding the performance indicators of similar commercially available products. Examples 2, 6, and 7 followed closely behind, demonstrating equally excellent adsorption effects, with adsorption rates for both target heavy metal ions consistently maintained above 90%. In contrast, although the adsorption performance of Example 4 was slightly lower, its adsorption efficiency was still significantly higher than that of the commercially available product used as the control group.

[0026] In summary, the material prepared in this application demonstrates outstanding heavy metal ion capture and removal capabilities, indicating broad application prospects. Further mechanistic analysis reveals that the synergistic effect of corn stalks and bamboo powder significantly increases the specific surface area of ​​the composite material and the density of sulfur-containing functional groups on its surface. Simultaneously, the doping strategy with composite sulfates successfully introduces diverse active adsorption sites into the material. The combined effect of these two factors effectively enhances the material's complexation and immobilization adsorption efficiency for heavy metal ions in water.

[0027] Examples 8-9 To verify the effects of voltage and temperature on the amount of graphene generated during flash evaporation, this application further tested the amount of graphene generated under different voltages and conditions. It should be noted that in the experimental scheme for the effect of voltage on the amount of graphene produced, the preparation method of sulfur-modified flash graphene is the same as in Example 2 above. The only difference is that the voltage condition for the preparation of flash graphene in Example 8 is 150V. In Example 9, the voltage condition for preparing flash graphene was 200V; Performance testing: Raman spectroscopy test The structure of carbon materials was characterized using Raman spectroscopy. The sample was mounted on a glass slide, which was then fixed to the sample stage. The stage position was adjusted so that the laser was focused onto the sample surface. The excitation wavelength was 532 nm, the laser intensity was 10%, and the scanning range was 50-4000 nm. ; Results analysis, reference Figure 1-3It is evident that the higher the voltage and the higher the reaction temperature, the better the degree of graphene formation.

[0028] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing sulfur-modified flash-evaporated graphene, characterized in that, Includes the following steps: Step 1: Mix sulfate with biomass and dry it, then pyrolyze and carbonize it to obtain sulfur-modified char. Step 2: The sulfur-modified carbon is subjected to Joule flash evaporation to obtain flash graphene; The mass ratio of sulfate to biomass is 1 to 6:10; During the Joule flash evaporation process, the voltage is 100–250V and the flash evaporation time is 8–12s.

2. The method for preparing sulfur-modified flash graphene according to claim 1, characterized in that, The biomass is selected from at least one of bamboo powder, corn stalks, rice straw, and sugarcane bagasse.

3. The method for preparing sulfur-modified flash graphene according to claim 1, characterized in that, The sulfate is selected from at least one of ferrous sulfate, zinc sulfate, and copper sulfate.

4. The method for preparing sulfur-modified flash graphene according to claim 1, characterized in that, Step 1 specifically involves mixing sulfate and biomass at a mass ratio of 1 to 6:10, drying the mixture, and then pyrolyzing and carbonizing it at 500 to 700°C for 1 to 2 hours under a nitrogen atmosphere to obtain sulfur-modified carbon.

5. The method for preparing sulfur-modified flash graphene according to claim 4, characterized in that, In step 1, the mixture of dried sulfate and biomass is heated to 500-700℃ at a heating rate of 5-10℃ / min to obtain sulfur-modified carbon.

6. The method for preparing sulfur-modified flash graphene according to claim 1, characterized in that, Step 2 specifically involves placing the sulfur-modified carbon obtained in step 1 into a quartz glass tube, with graphite electrodes and copper wires placed on both sides. The sulfur-modified flash graphene is rapidly generated through Joule flash evaporation. The external resistance of the flash evaporation equipment is 3–8 Ω, and the voltage conditions for flash graphene preparation are 100–250 V, with a time of 8–12 s.

7. The method for preparing sulfur-modified flash graphene according to claim 1, characterized in that, The biomass is a mixture of bamboo powder and corn stalks, and the mass ratio of bamboo powder to corn stalks is 2 to 4:

1.

8. A sulfur-modified flash-evaporated graphene, characterized in that, It is prepared by the method described in any one of claims 1-7 for preparing sulfur-modified flash graphene.

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