Graphene oxide layered film, method for preparing the same, and use thereof
By preparing graphene oxide layered membranes, the problem of selective separation of rare earth ions in existing technologies has been solved, achieving efficient, simple and environmentally friendly scandium ion adsorption and improving the extraction efficiency of rare earth elements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2024-07-08
- Publication Date
- 2026-07-28
AI Technical Summary
Existing technologies for the selective separation of rare earth ions face challenges such as difficulty in adsorbent selection and preparation, limited adsorption capacity and rate, regeneration and lifespan issues, high operation and maintenance costs, and economic and sustainability challenges, resulting in low efficiency of membrane adsorption separation technology in practical applications.
A method for preparing graphene oxide layered membranes was adopted, in which GO nanosheets were uniformly dispersed in water and then propylenediamine was added. Subsequently, the mixture was heated and sodium hydroxide and amino acids were added. After stirring and centrifugation, the modified nanosheets were obtained by vacuum filtration to form a graphene oxide layered membrane for adsorbing rare earth metal scandium.
It achieves the selective separation of low-concentration scandium ions in water through efficient adsorption. The operation is simple, the conditions are mild, and it is environmentally friendly, thus improving the extraction efficiency and separation effect of rare earth elements.
Smart Images
Figure CN118790986B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of layered membrane preparation technology, and in particular to a graphene oxide layered membrane, its preparation method, and its application. Background Technology
[0002] Scandium and its compounds, with their outstanding physical and chemical properties in aerospace, transportation, nuclear energy, fuel cells, and as highly efficient catalysts, have become indispensable elements in technological development. These high-end applications have extremely high requirements for material performance, and the introduction of scandium can greatly improve the temperature resistance, corrosion resistance, and structural strength of materials, driving technological innovation. Scandium's unique role is also reflected in environmental governance and energy conversion efficiency improvement, demonstrating its broad application potential. The rapid development in these fields has driven the continuous growth in demand for Sc(III). However, the current scandium extraction process faces technical challenges and complexities, which not only keeps the extraction cost high but also leads to a supply shortage in the market. Although solvent extraction technology is widely recognized for its high production efficiency, excellent separation performance, and fast mass transfer rate, its adverse environmental impact cannot be ignored.
[0003] Thapa et al. prepared a novel hybrid adsorbent, BP-TCPSi, by functionalizing bisphosphate and grafting it onto the surface of thermally carbonized mesoporous silica. This material exhibited a separation coefficient of 13 for Sc(III), three times that of the commercial ion exchange resin Dowex 50WX8, demonstrating significant selectivity. Furthermore, BP-TCPSi exhibited high stability, maintaining good performance even after 50 cycles of adsorption-desorption experiments. Zhong et al. synthesized a series of adsorbents with different functional extractants and supports using a vacuum impregnation method. Among them, the trialkylphosphine oxide-modified TRPO / SiO2-P showed excellent selective adsorption, achieving an adsorption efficiency of 99.3% for Sc(III) in adsorption column experiments. Characterization and DFT analysis showed that the P=O group was crucial for selective separation. These researchers have provided some reference and theoretical basis for the research of adsorption materials, but problems such as difficult material preparation, complex processes, low success rates, and high costs still exist, restricting the industrial application of adsorption methods.
[0004] In the field of adsorption, membrane adsorbents are a promising solid-phase technology. Membrane adsorbents consist of a microporous substrate coated with a separation layer at the micrometer or even nanometer scale, containing binding sites for molecules or ions. The selectivity of the membrane adsorbent can be tuned by altering its chemical properties. Therefore, membrane adsorbent materials can replace traditional ion exchange resins, achieving the high flux of nanofiltration membranes and the selectivity of ion exchange resins.
[0005] Membrane adsorption separation has become an ideal choice for water treatment systems due to its advantages such as no phase change required, low energy consumption, environmental friendliness, simple operation, high separation efficiency, and mild operating conditions. However, achieving selective separation of rare earth ions at the sub-nanometer scale has always been a significant challenge for traditional membrane separation technologies. The emergence of layered membranes has compensated for this deficiency, providing a good approach for the selective separation of single-type ions in mixed systems. However, existing technologies face many practical technical problems in application, including the difficulty of adsorbent selection and preparation, limited adsorption capacity and rate, regeneration and lifespan issues, difficulty in selective adsorption, high operation and maintenance costs, economic and sustainability challenges, and application-specific issues. These problems collectively affect the efficiency, cost, and sustainable development of adsorption technology, requiring efforts in multiple aspects such as material optimization, regeneration technology improvement, system design innovation, and economic enhancement.
[0006] Therefore, there is an urgent need to develop a graphene oxide layered film with high efficiency and high stability, as well as its preparation method and application, to solve the above-mentioned technical problems. Summary of the Invention
[0007] The purpose of this invention is to solve the existing technical problems and provide a graphene oxide layered film, its preparation method and application.
[0008] To achieve the above objectives, the present invention is implemented according to the following technical solution:
[0009] A method for preparing a graphene oxide layered film includes the following steps:
[0010] S1, After uniformly dispersing GO nanosheets in water, propylenediamine is added to obtain a GO suspension;
[0011] The S2,GO suspension was heated and then cooled. Sodium hydroxide and amino acids were added and stirred. Then, solid-liquid separation was performed to obtain a precipitate. The precipitate was washed to obtain modified nanosheets.
[0012] S3, modified nanosheets were used to prepare graphene oxide layered films by vacuum filtration.
[0013] Specifically, it includes the following steps:
[0014] S1, GO nanosheets were ultrasonically dispersed in water to obtain a uniform dispersion, and then propylenediamine was added and mixed to obtain a GO suspension;
[0015] S2, the GO suspension was heated, cooled, and then a small amount of sodium hydroxide and phosphoserine were added and stirred at room temperature. The resulting precipitate was centrifuged, washed, and dried to obtain modified nanosheets.
[0016] S3. Finally, an appropriate amount of modified nanosheets was taken and a graphene oxide layered film was prepared by vacuum filtration.
[0017] Preferably, in step S1, the concentration of GO nanosheets in the GO suspension is 0.4 g / L. -1 .
[0018] Specifically, GO suspension refers to a mixed solution of GO nanosheets, water, and propylenediamine; since the amount of propylenediamine added is small, the volume of propylenediamine was not included in the calculation of the concentration of GO suspension here.
[0019] Preferably, in step S1, the ratio of GO suspension to propylenediamine is 50:0.1, and the unit of comparison is ml:mol.
[0020] Preferably, in step S2, the heating temperature of the GO suspension is 60-100℃, and the heating time is 1-3h.
[0021] Preferably, in step S2, the ratio of GO suspension, sodium hydroxide, and amino acids is 50:0.0015:0.1, with the comparison unit being ml:mol:mol; and the stirring time is 24h.
[0022] Specifically, since the amount of propylenediamine added is small, the volume of propylenediamine was not included in the above-mentioned data concerning the volume of the GO suspension.
[0023] Preferably, in step S2, the amino acid is one of lysine, glutamic acid, and phosphoserine.
[0024] Preferably, in step S3, the modified nanosheets are filtered in the form of an aqueous solution; the concentration of the aqueous solution of the modified nanosheets is 0.4 g / L. -1 .
[0025] Preferably, in step S3, the vacuum filtration pressure is -0.1 MPa and the time is 12 hours.
[0026] Preferably, in step S3, the thickness of the obtained graphene oxide layered film is 1 μm.
[0027] The present invention also includes a graphene oxide layered film prepared by the above method.
[0028] An application of a graphene oxide layered membrane, wherein the graphene oxide layered membrane is used to adsorb the rare earth metal scandium.
[0029] Preferably, the graphene oxide layered film serves as an adsorbent to selectively adsorb scandium ions in the liquid;
[0030] The adsorption method is dynamic adsorption: the modified graphene oxide layered membrane is placed in the membrane pool, and scandium ions in the liquid are adsorbed by the graphene oxide layered membrane through pressure driving.
[0031] Specifically, it includes the following steps:
[0032] The graphene oxide layered membrane described above acts as an adsorbent to selectively adsorb scandium ions in water.
[0033] The adsorption method is dynamic adsorption: a graphene oxide layered membrane is placed in a membrane tank, and an aqueous solution containing scandium ions of a certain concentration is added to adjust the pH to 5. The scandium ions in the water are adsorbed by the layered membrane through a pressure-driven method using a dead-end device. Specifically, the concentration of scandium ions in the aforementioned aqueous solution is 10 ppm. The graphene oxide layered membrane can also be directly placed in an aqueous solution containing scandium ions for direct adsorption.
[0034] Mechanism of action:
[0035] This invention places a modified graphene oxide layered membrane in a membrane bath, prepares an aqueous solution containing scandium ions of a certain concentration and adjusts the pH to 5, and adsorbs scandium ions in the water using a pressure-driven method via a dead-end device. The preparation method of the modified graphene oxide layered membrane of this invention is as follows: GO nanosheets are ultrasonically dispersed in water, propylenediamine is added and mixed, the suspension is heated, cooled, and then a small amount of sodium hydroxide and phosphoserine are added and stirred at room temperature. The resulting precipitate is centrifuged and washed, and finally, an appropriate amount of modified nanosheets is taken and vacuum filtered to obtain the layered membrane.
[0036] GO, as an important graphene derivative, is essentially a single layer of graphene oxide with a large number of oxygen-containing functional groups introduced. It can serve as a reaction site for chemical reactions and as an adsorption site for metal ions.
[0037] The epoxy groups on the surface of GO membranes readily react with alcohols, amines, or alkoxides, allowing for the easy addition of binding groups. This functionalization strategy enables the immobilization of amino acids, peptides, and proteins, achieving modification of the GO membrane surface. Amino acids, peptides, and proteins are highly promising ligands for adsorbing rare earth elements; peptides with customized amino acid sequences and secondary structures can exhibit diverse functions and highly specific binding capabilities.
[0038] Layered membranes possess the characteristics of nanoscale confinement, long-range confinement, and ease of modification. When a feed solution passes through the membrane material, the unique interlayer channel structure of the layered membrane can remove hydrated ions at the nanoscale through size sieving, exposing metal ions in a bare ion state within the long-range channels, increasing the probability and duration of contact with active sites. Furthermore, by modifying the membrane surface and grafting specific functional groups, the channel microenvironment can be improved, further enhancing adsorption performance and achieving rapid selective separation. By adjusting the interlayer spacing, surface functionalization, and structural customization, the membrane's recognition and separation performance for specific ions can be further enhanced, providing efficient separation solutions for fields such as fine chemicals, resource recovery, and environmental remediation.
[0039] Layered membranes possess the characteristics of nanoscale confinement, long-range confinement, and ease of modification. When a feed solution passes through the membrane material, the unique interlayer channel structure of the layered membrane can remove hydrated ions at the nanoscale through size sieving, exposing metal ions in a bare ion state within the long-range channels, increasing the probability and duration of contact with active sites. Furthermore, by modifying the membrane surface and grafting specific functional groups to improve the channel microenvironment, adsorption performance can be further enhanced, enabling rapid selective separation. Layered membranes demonstrate significant potential for metal ion adsorption in terms of both physical structure and chemisorption. This invention delves into the channel structure of layered membranes and their mass transfer behavior and adsorption mechanism for metal ions, as well as how to design and optimize the function of layered membranes based on these mechanisms. This is crucial for improving the selective capture and separation of specific metal ions. By adjusting the interlayer spacing, surface functionalization, and structural customization, the membrane's recognition and separation performance for specific ions can be further enhanced, providing efficient separation solutions for fields such as fine chemicals, resource recovery, and environmental remediation.
[0040] This invention successfully prepared modified graphene oxide layered membranes by precisely controlling the interlayer spacing and the introduction of adsorption sites using inorganic small-molecule diamines and organic small-molecule amino acids. These layered membranes exhibit excellent performance in the selective adsorption and separation of scandium, providing a feasible new strategy for the efficient extraction of rare earth elements.
[0041] Beneficial effects:
[0042] This invention can efficiently adsorb scandium ions at low concentrations in water, and the entire adsorption process has the advantages of simple operation, mild conditions, high selectivity and environmental friendliness. Attached Figure Description
[0043] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention;
[0044] Figure 2 These are performance diagrams of different layered membranes obtained in the embodiments and comparative examples of the present invention;
[0045] Figure 3 The images are XRD images of the graphene oxide layered films obtained in Examples 1 to 3 of the present invention and the GO layered film obtained in Comparative Example 1 in a dry state.
[0046] Figure 4 The images show the XRD patterns of the graphene oxide layered film obtained in Example 1 and the GO layered film obtained in Comparative Example 1 in the dry state.
[0047] Figure 5 This is a dynamic performance diagram of the graphene oxide layered membrane prepared in Example 1 of the present invention for adsorbing scandium ions in water. Detailed Implementation
[0048] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.
[0049] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.
[0050] There are no particular restrictions on the purity of any raw materials used in this invention. However, it is preferred to use industrial-grade or conventionally pure materials used in this field.
[0051] Unless otherwise specified, the apparatus used in this invention employs commonly used devices in the field.
[0052] Example 1
[0053] A method for preparing a graphene oxide layered film:
[0054] S1, GO nanosheets were ultrasonically dispersed in water to obtain a concentration of 0.4 g / L in 50 ml of water. -1 A GO nanosheet aqueous solution was mixed with 0.1 mol of propylenediamine to obtain a GO suspension; the concentration of GO nanosheets in the GO suspension was 0.4 g / L. -1 (The volume of propylenediamine is not included in the concentration calculation); the ratio of GO suspension to propylenediamine is 50:0.1, and the unit of comparison is ml:mol.
[0055] S2, the GO suspension was heated, cooled, and then sodium hydroxide and amino acids were added and stirred at room temperature. The resulting precipitate was centrifuged, washed, and dried to obtain modified nanosheets. The heating temperature of the GO suspension was 80℃, and the heating time was 1h. The ratio of GO suspension (excluding the volume of propylenediamine in the volume calculation), sodium hydroxide, and amino acids was 50:0.0015:0.1, and the unit of comparison was ml:mol:mol. The stirring time was 24h.
[0056] S3, mix the modified nanosheets obtained in step S2 with water to obtain a concentration of 0.4 g / L. -1 Modified nanosheet solution; take 5 ml of 0.4 g L -1 A modified nanosheet solution was used to prepare a graphene oxide layered film via vacuum filtration; the obtained graphene oxide layered film had a thickness of 1 μm and an area of 12.56 cm². 2 The vacuum filtration pressure was -0.1 MPa, and the time was 12 hours.
[0057] In this embodiment, the amino acid is phosphoserine; the obtained graphene oxide layered film is denoted as GO-PDA@P.
[0058] like Figure 1 The diagram shown is a process flow chart of Embodiment 1 of the present invention.
[0059] Example 2
[0060] The difference between this embodiment and Example 1 is that the amino acid used is lysine, and the resulting graphene oxide layered film is denoted as GO-PDA@L.
[0061] Example 3
[0062] The difference between this embodiment and Example 1 is that the amino acid used is glutamic acid, and the resulting graphene oxide layered film is denoted as GO-PDA@G.
[0063] Example 4
[0064] The difference between this embodiment and Embodiment 1 is that the heating time in step S2 is 2 hours, and the resulting layered membrane is denoted as Pho-2h.
[0065] Example 5
[0066] The difference between this embodiment and Embodiment 1 is that the heating time in step S2 is 3 hours, and the resulting layered membrane is denoted as Pho-3h.
[0067] Example 6
[0068] The difference between this embodiment and Embodiment 1 is that the heating temperature in step S2 is 60°C, and the resulting layered membrane is denoted as Pho-60°C.
[0069] Example 7
[0070] The difference between this embodiment and Embodiment 1 is that the heating temperature in step S2 is 100°C, and the resulting layered membrane is denoted as Pho-100°C.
[0071] Comparative Example 1
[0072] S1, GO nanosheets were ultrasonically dispersed in water to obtain a concentration of 0.4 g / L. -1GO nanosheet aqueous solution.
[0073] S2, take 5ml of 0.4g L -1 The layered membrane prepared by vacuum filtration of GO nanosheet aqueous solution is denoted as GO; the vacuum filtration pressure is -0.1 MPa and the time is 12 h.
[0074] Comparative Example 2
[0075] S1, GO nanosheets were ultrasonically dispersed in water to obtain an aqueous solution of GO nanosheets with a concentration of 0.4 g / L. -1 .
[0076] S2, the GO nanosheet aqueous solution from S1 was heated, cooled, and then sodium hydroxide and amino acids were added and stirred at room temperature. The resulting precipitate was centrifuged, washed, and dried to obtain modified nanosheets. The heating temperature of the GO nanosheet suspension was 80℃, and the heating time was 1h. The ratio of GO nanosheet aqueous solution, sodium hydroxide, and amino acids was 50:0.0015:0.1, and the comparison unit was ml:mol:mol. The stirring time was 24h.
[0077] S3, mix the modified nanosheets obtained in step S2 with water to obtain a concentration of 0.4 g / L. -1 A modified nanosheet solution was prepared by vacuum filtration. 5 ml of the modified nanosheet solution was taken and a layered membrane was prepared by vacuum filtration. The vacuum filtration pressure was -0.1 MPa and the time was 12 h.
[0078] In this comparative example, the amino acid is phosphoserine.
[0079] The resulting graphene oxide layered film is denoted as GO-Pho.
[0080] Comparative Example 3
[0081] S1, a GO suspension was prepared according to step S1 of Example 1. The GO suspension was filtered and dried to obtain GO-PDA modified nanosheets.
[0082] S2, following steps S1 and S2 of Comparative Example 2, modified nanosheets were prepared, which are GO-Pho modified nanosheets.
[0083] S3, mix the GO-PDA modified nanosheets and GO-Pho modified nanosheets obtained in steps S1 and S2 with water, wherein the mass ratio of GO-PDA modified nanosheets to GO-Pho modified nanosheets is 1:1; to obtain a concentration of 0.4 g / L. -1 A mixed modified nanosheet solution was prepared by taking 5 ml of the mixed modified nanosheet solution and preparing a layered membrane by vacuum filtration. The vacuum filtration pressure was -0.1 MPa and the time was 12 h.
[0084] The resulting graphene oxide layered film is denoted as GO-PDA / Pho.
[0085] like Figure 2 The figure shows the performance of different layered membranes obtained in the embodiments and comparative examples of the present invention.
[0086] Adsorption tests were conducted on the graphene oxide layered membranes obtained in Examples 1 to 3 and the layered membrane obtained in Comparative Example 1 using a sample solution. The sample solution used in the tests was a scandium single-ion solution with a scandium ion concentration of 100 ppm and a volume of 100 mL. The test conditions were as follows: at pH = 5, 0.15 g of the layered membrane was placed in 100 mL of the scandium single-ion solution, and stirred at room temperature for 24 h at a stirring speed of 130 rpm. The data obtained are as follows: Figure 2 As shown in Figure a, the adsorption capacity and removal rate of Sc by GO materials were significantly improved after introducing three different amino acids. Specifically, the adsorption capacity of GO-PDA@P was 44.64 mg g⁻¹, slightly lower than that of GO-PDA@L (48.78 mg g⁻¹). -1 However, the removal rate of GO-PDA@P was 99.87%, which was higher than the removal rate of GO-PDA@L (99.72%).
[0087] The graphene oxide layered membrane obtained in Example 1, as well as the layered membranes obtained in Comparative Examples 2 and 3, were subjected to adsorption tests using a scandium-aluminum mixed ion solution. The solution used in the tests was a scandium-aluminum mixed ion solution with a Sc ion concentration of 100 ppm and an Al ion concentration of 100 ppm; the volume of the scandium-aluminum mixed ion solution was 100 mL. The test conditions were as follows: at pH = 5, 0.15 g of the layered membrane was placed in 100 mL of the scandium-aluminum mixed ion solution, and stirred at room temperature for 24 h at a stirring speed of 130 rpm. The data obtained are as follows. Figure 2 As shown in b, the adsorption capacity and separation factor of GO-PDA@P are greatly improved, which is the result of the combined effect of amino and phosphate groups.
[0088] The graphene oxide layered membranes obtained in Example 1, and the layered membranes obtained in Examples 4 and 5, were subjected to adsorption tests using a scandium-aluminum mixed ion solution. The solution used in the tests was a scandium-aluminum mixed ion solution with a Sc ion concentration of 100 ppm and an Al ion concentration of 100 ppm; the volume of the scandium-aluminum mixed ion solution was 100 mL. The test conditions were as follows: at pH = 5, 0.15 g of the layered membrane was placed in 100 mL of the scandium-aluminum mixed ion solution, and stirred at room temperature for 24 h at a stirring speed of 130 rpm. The data obtained are as follows: Figure 2Figure c shows the membrane performance at different heating times. As the heating time increases, both the adsorption capacity and the separation factor decrease, with the separation factor significantly decreasing after 3 hours. This is mainly because amino acid molecules are deactivated at high temperatures for extended periods, failing to fully exert their coordination effect in the interlayer channels, thus weakening membrane selectivity.
[0089] The graphene oxide layered membranes obtained in Example 1, and the layered membranes obtained in Examples 6 and 7, were subjected to adsorption tests using a scandium-aluminum mixed ion solution. The solution used in the tests was a scandium-aluminum mixed ion solution with a Sc ion concentration of 100 ppm and an Al ion concentration of 100 ppm; the volume of the scandium-aluminum mixed ion solution was 100 mL. The test conditions were as follows: at pH = 5, 0.15 g of the layered membrane was placed in 100 mL of the scandium-aluminum mixed ion solution, and stirred at room temperature for 24 h at a stirring speed of 130 rpm. The data obtained are as follows. Figure 2 Figure d shows the membrane performance at different temperatures. When the modification temperature is 60℃, the adsorption capacity is the highest, but the separation factor is low. This is mainly because the amino acid molecules are not fully grafted. When the modification temperature is 100℃, both the adsorption capacity and the separation factor are the lowest. This is mainly because the grafted amino acid molecules are deactivated at high temperatures, resulting in a decrease in performance.
[0090] like Figure 3 The image shows the XRD images of the graphene oxide layered film obtained in the embodiments of the present invention and the GO layered film obtained in Comparative Example 1 in the dry state.
[0091] To investigate the structural differences between different layered films, XRD characterization techniques were used to test the changes in XRD images of the graphene oxide layered films obtained in Examples 1 to 3 and the GO layered film obtained in Comparative Example 1 under dry conditions, and the interlayer spacing d was calculated using the Bragg equation.
[0092] Depend on Figure 3 , Figure 4It can be seen that the characteristic peak positions of the GO(001) layer of the GO, GO-PDA@G, GO-PDA@P, and GO-PDA@L layered membranes are 11.48°, 10.13°, 10.48°, and 11.8°, respectively, with corresponding interlayer spacings d of 0.77 nm, 0.88 nm, 0.84 nm, and 0.75 nm. The relative atomic masses of the three different amino acids, from smallest to largest, are lysine, glutamic acid, and phosphoserine, but the measured interlayer spacings do not match. This is mainly because the interlayer spacing of the phosphoserine-modified GO membrane is between the other two. This is primarily due to the strong electronegativity of the four oxygen atoms in the phosphate group, which causes the atoms in the phosphate group to be arranged more closely together by electrostatic forces, resulting in a relatively smaller overall size. At the same time, there are no other impurity peaks in the XRD images, indicating that the membrane material has high regularity and still retains the structure of the GO layered membrane, which is conducive to the adsorption of the membrane adsorbent when metal ions are transported in the interlayer channels.
[0093] like Figure 5 The figure shown is a dynamic performance diagram of the graphene oxide layered membrane prepared in Example 1 of the present invention for adsorbing scandium ions in water.
[0094] The graphene oxide layered membrane obtained in Example 1 was used as an adsorbent to selectively adsorb scandium ions from water. The adsorption method was dynamic adsorption: the graphene oxide layered membrane was placed in a membrane tank, and the pH of the aqueous solution containing scandium ions (concentration of scandium ions was 10 ppm) was adjusted to 5. Scandium ions in the water were adsorbed by the layered membrane using different pressure-driven methods through a dead-end device. Different pressure drives in the dead-end device resulted in different feed flow rates, and relevant data were measured under different feed flow rate conditions.
[0095] Depend on Figure 5 It can be determined that the feed flow rate is 50 L / m. -2 h -1 At that time, the C-curve breaks through. v The CO increase started early, meaning the concentration of Sc(III) in the filtrate rose significantly when the filtration volume exceeded 5 mL. During this process, the membrane exhibited an adsorption capacity of 48.97 mg g for Sc(III). -1 This reflects that the removal of Sc(III) mainly depends on adsorption, while the contribution of size sieving is almost negligible. Furthermore, the feed flux is 10 L / m³. -2 h -1 and 30L m -2 h -1 The breakthrough curves are slightly different, with a flow rate of 30 L / m. -2 h -1The breakthrough curves show that when the membrane treated 30 mL of solution, the permeate concentration just reached 5% of the initial concentration. Subsequently, as the treated filtrate volume increased, the breakthrough curve became suddenly steeper, eventually reaching the feed concentration. At dynamic adsorption equilibrium, their adsorption capacities were essentially the same, both at 62.68 mg g. -1 This indicates that GO-PDA@P has a high affinity for Sc(III) and exhibits strong affinity at a flow rate of 30 L / m³. -2 h -1 The flow rate does not affect its adsorption capacity, but when the flow rate is 50 L / m³, it does not affect its adsorption capacity. -2 h -1 The decrease in adsorption capacity is mainly due to the high feed flow rate creating dead zones in the interlayer channels, or the adsorption sites being located within the topological structure and unable to achieve rapid adsorption. Therefore, the initial feed flow rate in the dynamic operation experiment was 30 L / m³. -2 h -1 .
[0096] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.
Claims
1. A method for preparing a graphene oxide layered film, characterized in that: Includes the following steps: S1, After uniformly dispersing GO nanosheets in water, propylenediamine is added to obtain a GO suspension; The S2,GO suspension was heated and then cooled. Sodium hydroxide and amino acids were added and stirred. Then, solid-liquid separation was performed to obtain a precipitate. The precipitate was washed to obtain modified nanosheets. S3, modified nanosheets were used to prepare graphene oxide layered films by vacuum filtration.
2. The method for preparing a graphene oxide layered film according to claim 1, characterized in that: In step S1, the concentration of GO nanosheets in the GO suspension is 0.4 g / L. -1 .
3. The method for preparing a graphene oxide layered film according to claim 2, characterized in that: In step S1, the ratio of GO suspension to propylenediamine is 50:0.1, and the unit of comparison is ml:mol.
4. The method for preparing a graphene oxide layered film according to claim 1, characterized in that: In step S2, the heating temperature of the GO suspension is 60-100℃, and the heating time is 1-3h.
5. The method for preparing a graphene oxide layered film according to claim 1, characterized in that: In step S2, the ratio of GO suspension, sodium hydroxide, and amino acids is 50:0.0015:0.1, with the comparison unit being ml:mol:mol.
6. The method for preparing a graphene oxide layered film according to claim 1, characterized in that: In step S2, the amino acid is one of lysine, glutamic acid, or phosphoserine.
7. A graphene oxide layered film prepared by the method according to any one of claims 1-6.
8. The application of the graphene oxide layered film according to claim 7, characterized in that: The graphene oxide layered film is used to adsorb the rare earth metal scandium.
9. The application of the graphene oxide layered film according to claim 8, characterized in that: The graphene oxide layered film acts as an adsorbent, selectively adsorbing scandium ions in the liquid.
10. The application of the graphene oxide layered film according to claim 9, characterized in that: The adsorption method is dynamic adsorption: the modified graphene oxide layered membrane is placed in the membrane pool, and scandium ions in the liquid are adsorbed by the graphene oxide layered membrane through pressure driving.