A transition metal ion-modified graphene oxide membrane, a method for preparing the same, and applications thereof

Abstract

This invention relates to a transition metal ion-modified graphene oxide membrane, its preparation method, and its applications. It is applied to the treatment of volatile aromatic compounds in air. The method involves mixing a graphene oxide solution with an aqueous solution of an inorganic salt containing transition metal ions, followed by vacuum filtration to form a membrane. After drying, the transition metal ion-modified graphene oxide membrane is obtained. The transition metal ion-modified graphene oxide membrane, relying on the complexation between the transition metal ions and aromatic rings, as well as the size sieving effect of the graphene oxide membrane on aromatic compounds, works synergistically to efficiently and selectively remove volatile aromatic compounds from the air. The preparation method of this invention is simple and easy to operate. The resulting transition metal ion-modified graphene oxide membrane has high mechanical strength, is not easily damaged, can be reused, and has a high gas flux, effectively removing volatile aromatic compounds from the air, showing promising application prospects.

Description

Technical Field

[0001] This invention relates to the field of treating volatile aromatic compounds in air, specifically to a transition metal ion-modified graphene oxide membrane for air purification, its preparation method, and its applications. Background Technology

[0002] Various volatile aromatic compounds, such as benzene, toluene, and ethylbenzene, are produced in industries such as petrochemicals, paints, and pharmaceuticals. These compounds are toxic and carcinogenic, not only damaging the ozone layer but also forming photochemical smog with other air pollutants, causing serious harm to the environment and human health. Currently, the main methods for treating volatile aromatic compounds include condensation, adsorption, absorption, and incineration, but most methods have certain limitations.

[0003] Membrane separation technology uses a membrane as the separation medium, applying driving forces across the membrane to selectively allow components in a gas mixture to permeate through it, thus achieving separation. It is considered a highly efficient and energy-saving separation method. Graphene oxide membranes have shown great potential in gas separation due to their ultrathinness and high flux. However, most graphene oxide membranes are used as adsorbents to remove volatile aromatic compounds from the air, exhibiting limited adsorption capacity and low removal efficiency. Therefore, developing a low-cost, high-flux, ultrathin, and highly efficient graphene oxide molecular sieve membrane is particularly important, with significant potential applications in chemical, medical, and industrial fields. Summary of the Invention

[0004] The present invention aims to provide a transition metal ion-modified graphene oxide membrane, its preparation method, and its applications. This transition metal ion-modified graphene oxide membrane, relying on the complexation between transition metal ions and aromatic rings, and the size sieving effect of the graphene oxide membrane on aromatic compounds, works synergistically to efficiently and selectively remove volatile aromatic compounds from the air. The preparation method of the present invention is simple and easy to operate, and yields an ultrathin transition metal ion-modified graphene oxide membrane. This membrane, deposited on an Al2O3 ceramic support substrate, possesses high mechanical strength, is not easily damaged, and is reusable. Simultaneously, it exhibits high gas flux, exceeding that of previous graphene oxide membranes by 1-2 orders of magnitude, effectively removing volatile aromatic compounds from the air and showing promising application prospects in chemical, medical, and industrial fields.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a transition metal ion-modified graphene oxide film includes the following steps:

[0007] A mixed solution was obtained by mixing and shaking a graphene oxide film solution with an inorganic salt aqueous solution containing transition metal ions.

[0008] A transition metal ion-modified graphene oxide membrane was prepared by vacuum filtration using Al2O3 ceramic sheets as the supporting substrate.

[0009] After drying, a graphene oxide film modified with transition metal ions is obtained.

[0010] Preferably, in the preparation process of the transition metal ion modified graphene oxide film, the transition metal ion is Ni. 2+ Fe 3+ Cu 2+ Zn 2+ Mn 2+ or Cr 3+ Ni is a better transition metal ion. 2+ .

[0011] Preferably, in the preparation process of the transition metal ion modified graphene oxide film, the concentration of transition metal ions in the mixed solution is 0.005-0.5 mmol / L, and more preferably 0.01 mmol / L.

[0012] Preferably, in the preparation process of the transition metal ion modified graphene oxide film, the oscillation mixing time is 10-30 min, and more preferably 15 min.

[0013] Preferably, in the preparation process of the transition metal ion modified graphene oxide film, the pore size of the Al2O3 ceramic sheet support substrate is 0.1-0.5 μm, and more preferably, the pore size of the Al2O3 ceramic sheet support substrate is 0.2 μm.

[0014] Preferably, in the preparation process of the transition metal ion modified graphene oxide film, the drying temperature is 50-80℃ and the drying time is 8-20h, more preferably the drying temperature is 60℃ and the drying time is 10-15h.

[0015] A transition metal ion modified graphene oxide film is prepared using the method for preparing transition metal ion modified graphene oxide film described in this invention.

[0016] An application of a transition metal ion-modified graphene oxide membrane is disclosed, which is used to treat gas mixtures for gas purification. It is preferably applied to air purification.

[0017] Preferably, during the gas purification process, the gas mixture is a mixture of nitrogen and volatile aromatic compounds, and the concentration of volatile aromatic compounds in the gas mixture is 5 to 80 ppm, more preferably 20 ppm.

[0018] Preferably, during the gas purification process, the relative humidity of the gas mixture is 40% to 80%, and more preferably, the relative humidity of the gas mixture is 59%.

[0019] Preferably, during the gas purification process, the gas mixture feed flow rate is 100–1000 mL / min, the operating temperature is 15–28 °C, and the pressure difference is 0–1.5 bar. More preferably, the gas mixture feed flow rate is 600 mL / min, the operating temperature is 25 °C, and the pressure difference is 0.9 bar.

[0020] Compared with the prior art, the present invention has the following obvious and prominent substantive features and significant advantages:

[0021] 1. The preparation process of the present invention is simple and easy to operate;

[0022] 2. This invention prepares a dry, ultrathin graphene oxide film modified with transition metal ions. The film is deposited on an Al2O3 ceramic sheet support substrate, has high mechanical strength, is not easily damaged, and ensures the reusability of the graphene oxide film.

[0023] 3. This invention relies on the complexation between transition metal ions and aromatic rings, as well as the size sieving effect of graphene oxide film on aromatic compounds. The two work synergistically to efficiently and selectively remove volatile aromatic compounds from the air.

[0024] 4. Compared with traditional graphene oxide membranes, the transition metal ion modified graphene oxide membrane prepared in this invention has a higher gas flux, which is 1 to 2 orders of magnitude higher;

[0025] 5. The transition metal ion modified graphene oxide membrane prepared in this invention has a rejection rate of more than 98% for the three volatile aromatic compounds, which exceeds the industrial emission standard, showing excellent separation performance and good application prospects. Attached Figure Description

[0026] Figure 1 The images show physical images of the transition metal ion-modified graphene oxide films prepared in Examples 1-3 of this invention.

[0027] Figure 2 The images shown are SEM images of the transition metal ion modified graphene oxide films prepared in Examples 1-3 of this invention.

[0028] Figure 3These are the XRD patterns of the transition metal ion modified graphene oxide films and pure graphene oxide films prepared in Examples 1-3 of this invention.

[0029] Figure 4 The test evaluation of the phenol retention of the transition metal ion modified graphene oxide membrane prepared in Example 1 of the present invention, and the test evaluation of the phenol retention of the pure graphene oxide membrane.

[0030] Figure 5 The test evaluation of the benzoic acid retention of the transition metal ion modified graphene oxide membrane prepared in Example 2 of the present invention, and the test evaluation of the benzoic acid retention of the pure graphene oxide membrane.

[0031] Figure 6 The present invention provides a test and evaluation of the retention of benzylamine by the transition metal ion modified graphene oxide membrane prepared in Embodiment 3, as well as a test and evaluation of the retention of benzylamine by the pure graphene oxide membrane. Detailed Implementation

[0032] The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the experimental examples described herein. Experimental methods not specifically described in the following embodiments are performed according to conventional methods and conditions, or as selected in the product instructions.

[0033] In the following examples, the graphene oxide solution used was prepared by a modified Hummer method. The absorbance of each volatile aromatic compound dissolved in water was measured using a Shanghai Meipuda UV-1600 UV spectrophotometer.

[0034] Example 1

[0035] The application of the transition metal ion-modified graphene oxide membrane in air purification includes the following steps:

[0036] Take 200 μL of a 5 mg / mL graphene oxide solution prepared using the modified Hummer method, and mix it with 15 mL of nickel chloride aqueous solution by shaking for 15 min to ensure that the concentration of nickel ions in the mixed solution is 0.01 mmol / L. Using an Al₂O₃ ceramic sheet with a pore size of 0.2 μm as the supporting substrate, the mixed solution is deposited onto the Al₂O₃ ceramic sheet by vacuum filtration. The transition metal ion-modified graphene oxide membrane deposited on the Al₂O₃ ceramic sheet is then dried in a 60 °C oven for 10–15 h to obtain a dried transition metal ion-modified graphene oxide membrane for later use.

[0037] The test conditions for the membrane prepared in this embodiment of the invention are as follows: a gas mixture containing 20 ppm phenol is fed into the membrane cell at a flow rate of 600 mL / min, the humidity of the gas mixture is 59%, the operating temperature is 25°C, aeration is carried out for 1 hour, gas separation is performed under a pressure of 0.9 bar, the gas filtered by the membrane is collected in a sealed bag and absorbed with water for 2 hours, the absorbance of phenol in the absorption liquid is measured using a UV-Vis spectrophotometer, the concentration of phenol in the absorption liquid is calculated as the emission concentration of phenol, and the phenol rejection rate is further calculated.

[0038] At the same time, a control experiment was conducted, in which the graphene oxide solution was not mixed with the nickel chloride aqueous solution, and the pure graphene oxide solution was directly used to prepare a pure graphene oxide membrane by vacuum filtration, and gas separation experiments were carried out under the test conditions described above.

[0039] Experimental test analysis:

[0040] according to Figure 1 As can be seen from the physical images, the graphene oxide film modified with transition metal ions is uniformly distributed on the Al2O3 ceramic sheet support substrate. Figure 2 The SEM images further demonstrate that the transition metal ion-modified graphene oxide film we prepared is uniformly distributed and free of in-plane defects. Figure 3 The XRD pattern shows that the interlayer spacing of the graphene oxide film modified with transition metal ions is [missing information]. The interlayer spacing of pure graphene oxide film is The interlayer spacing of both is similar. Figure 4 It can be seen that the rejection rate of phenol by the transition metal ion modified graphene oxide membrane is 99.8% within 1 hour, which is far higher than the industrial emission standard (98%). However, the rejection rate of phenol by the pure graphene oxide membrane is 98.5%, showing a slight downward trend.

[0041] Example 2

[0042] The application of the transition metal ion-modified graphene oxide membrane in air purification includes the following steps:

[0043] Take 200 μL of a 5 mg / mL graphene oxide solution prepared using the modified Hummer method, and mix it with 15 mL of nickel chloride aqueous solution by shaking for 15 min to ensure that the concentration of nickel ions in the mixed solution is 0.01 mmol / L. Using an Al₂O₃ ceramic sheet with a pore size of 0.2 μm as the supporting substrate, the mixed solution is deposited onto the Al₂O₃ ceramic sheet by vacuum filtration. The transition metal ion-modified graphene oxide membrane deposited on the Al₂O₃ ceramic sheet is then dried in a 60 °C oven for 10–15 h to obtain a dried transition metal ion-modified graphene oxide membrane for later use.

[0044] The test conditions for the membrane prepared in this embodiment of the invention are as follows: a gas mixture containing 20 ppm benzoic acid is fed into the membrane cell at a flow rate of 600 mL / min, the humidity of the gas mixture is 59%, the operating temperature is 25°C, aeration is carried out for 1 hour, gas separation is performed under a pressure of 0.9 bar, the gas filtered by the membrane is collected in a sealed bag and absorbed with water for 2 hours, the absorbance of benzoic acid in the absorption liquid is measured using a UV-Vis spectrophotometer, the concentration of benzoic acid in the absorption liquid is calculated as the emission concentration of benzoic acid, and the benzoic acid rejection rate is further calculated.

[0045] At the same time, a control experiment was conducted, in which the graphene oxide solution was not mixed with the nickel chloride aqueous solution, and the pure graphene oxide solution was directly used to prepare a pure graphene oxide membrane by vacuum filtration, and gas separation experiments were carried out under the test conditions described above.

[0046] Experimental test analysis:

[0047] Depend on Figure 5 It can be seen that the graphene oxide membrane modified with transition metal ions achieved a benzoic acid rejection rate of 98.6% within 1 hour, which is higher than the industrial emission standard (98%). However, the rejection rate of benzoic acid by the pure graphene oxide membrane was 94.9%, showing a downward trend.

[0048] Example 3

[0049] The application of the transition metal ion-modified graphene oxide membrane in air purification includes the following steps:

[0050] Take 200 μL of a 5 mg / mL graphene oxide solution prepared using the modified Hummer method, and mix it with 15 mL of nickel chloride aqueous solution by shaking for 15 min to ensure that the concentration of nickel ions in the mixed solution is 0.01 mmol / L. Using an Al₂O₃ ceramic sheet with a pore size of 0.2 μm as the supporting substrate, the mixed solution is deposited onto the Al₂O₃ ceramic sheet by vacuum filtration. The transition metal ion-modified graphene oxide membrane deposited on the Al₂O₃ ceramic sheet is then dried in a 60 °C oven for 10–15 h to obtain a dried transition metal ion-modified graphene oxide membrane for later use.

[0051] The test conditions for the membrane prepared in this embodiment of the invention are as follows: a gas mixture containing 20 ppm aniline is fed into the membrane cell at a flow rate of 600 mL / min, the humidity of the gas mixture is 59%, the operating temperature is 25°C, aeration is carried out for 1 hour, gas separation is performed under a pressure of 0.9 bar, the gas filtered by the membrane is collected in a sealed bag and absorbed with water for 2 hours, the absorbance of aniline in the absorption liquid is measured using a UV-Vis spectrophotometer, the concentration of aniline in the absorption liquid is calculated as the emission concentration of aniline, and the rejection rate of aniline is further calculated.

[0052] At the same time, a control experiment was conducted, in which the graphene oxide solution was not mixed with the nickel chloride aqueous solution, and the pure graphene oxide solution was directly used to prepare a pure graphene oxide membrane by vacuum filtration, and gas separation experiments were carried out under the test conditions described above.

[0053] Experimental test analysis:

[0054] Depend on Figure 6 It can be seen that the graphene oxide membrane modified with transition metal ions achieved a rejection rate of 99.4% for abenzamine within 1 hour, which is far higher than the industrial emission standard (98%). However, the rejection rate of pure graphene oxide membrane for abenzamine was 94%, showing a downward trend.

[0055] In summary, this invention relates to the field of treating volatile aromatic compounds in air, specifically to a method for preparing a transition metal ion-modified graphene oxide membrane for air purification. The method involves first mixing a graphene oxide solution with an aqueous solution of an inorganic salt containing transition metal ions, then forming a membrane through vacuum filtration, followed by drying to obtain the transition metal ion-modified graphene oxide membrane. This transition metal ion-modified graphene oxide membrane, relying on the complexation between transition metal ions and aromatic rings, as well as the size sieving effect of the graphene oxide membrane on aromatic compounds, works synergistically to efficiently and selectively remove volatile aromatic compounds from the air. The method of this invention is simple and easy to operate, and yields an ultrathin transition metal ion-modified graphene oxide membrane. This membrane, deposited on an Al2O3 ceramic support substrate, possesses high mechanical strength, is not easily damaged, and is reusable. It also exhibits high gas flux, exceeding that of previous graphene oxide membranes by 1-2 orders of magnitude, effectively removing volatile aromatic compounds from the air and showing promising application prospects.

[0056] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made based on the spirit and principle of the technical solution of the present invention shall be equivalent substitutions. As long as they meet the purpose of the invention and do not deviate from the technical principle and inventive concept of the present invention, they shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a transition metal ion-modified graphene oxide film, characterized in that, The graphene oxide dispersion liquid is prepared by a modified Hummer method, a graphene oxide film solution is mixed with an inorganic salt aqueous solution containing transition metal ions to obtain a mixed solution; the transition metal ions are Fe 3+ or Cr 3+ ; the concentration of the transition metal ions is 0.005-0.5 mmol / L; A transition metal ion-modified graphene oxide membrane was prepared by vacuum filtration using Al2O3 ceramic sheets as the supporting substrate. After drying, a graphene oxide film modified with transition metal ions is obtained; the graphene oxide film is used to treat volatile aromatic compounds in the air.

2. The method for preparing transition metal ion-modified graphene oxide film as described in claim 1, characterized in that, The thickness of the graphene oxide film is 10 nm-400 nm.

3. The method for preparing transition metal ion-modified graphene oxide film as described in claim 1, characterized in that, The oscillation mixing time is 10~30 min.

4. The method for preparing transition metal ion-modified graphene oxide film as described in claim 1, characterized in that, The pore size of the supporting substrate ranges from 0.1 to 0.5 μm.

5. The method for preparing transition metal ion-modified graphene oxide film as described in claim 1, characterized in that, The drying temperature is 50~80℃, and the drying time is 8~20 h.

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