Preparation method of novel two-dimensional MXene membrane based on forward osmosis deposition
Two-dimensional MXene films were prepared by positive permeation deposition method, and the layer spacing was expanded by cationic intercalator, which solved the problems of high energy consumption and low mechanical strength in the prior art, and achieved a high selectivity and high mechanical strength two-dimensional MXene film, which was suitable for multiple industrial fields.
Patent Information
- Application Number
- CN202510418951.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-08-19
AI Technical Summary
The existing two-dimensional film preparation methods consume a lot of energy, and the prepared two-dimensional films have the problems of selective defects and low mechanical strength.
Using the positive permeability deposition method, a specific cationic salt solution is used as the driving liquid to reverse the cation into the MXene two-dimensional nanosheet layers through the ion selectivity of the positive permeability membrane, and a column support effect is generated as an ion intercalation agent. Combined with the F-based expansion layer spacing in the MXene material, a metal ion intercalation two-dimensional MXene film is prepared.
It realizes the preparation of two-dimensional MXene membranes with low energy consumption, high selectivity and high mechanical strength, and can precisely regulate ion permeability. It is suitable for molecular/ion sieving, bio/chemical sensing, DNA sequencing, and energy storage and conversion.
Smart Images
Figure CN120502233A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition. Background Art
[0002] Membrane separation technology, which utilizes pressure, concentration, potential, and temperature differences as driving forces to separate, concentrate, and purify different components in a liquid, has been widely used in many industrial fields. The development of novel membranes is a core topic in the application of membrane separation technology, and two-dimensional nanomaterial membranes (2D membranes) have recently attracted widespread attention from researchers. 2D membranes possess a unique layered structure with atomic-scale thickness, enabling precise regulation of the selective transmembrane transport of ions. Due to their advantages such as efficient chemical modification, high ion flux, and strong ion regulation capabilities, they have great potential for application in molecular / ion screening, biological / chemical sensing / detection, DNA sequencing, and energy storage and conversion.
[0003] Currently, two-dimensional membranes are mainly prepared by vacuum filtration and pressure filtration. By changing the pressure, deposition rate, and type of porous support layer, the stacking structure of the two-dimensional material on the support layer can be changed, thereby regulating the membrane performance. In addition, the casting method is also used to prepare two-dimensional membranes. For example, a certain amount of MXene and polymer are dissolved in a solvent through vigorous stirring or ultrasound to form a homogeneous solution and cast on a substrate. After the solvent evaporates under high temperature and / or vacuum conditions, the independent MXene / polymer membrane can be peeled off from the substrate to prepare a composite two-dimensional membrane. However, these membrane-forming methods consume a lot of energy, and the prepared two-dimensional membranes usually have non-selective defects and low mechanical strength. Summary of the Invention
[0004] The present invention aims to provide a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition to solve the problems raised in the above background technology. The present invention provides the following technical solution: a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition, comprising the following steps:
[0005] S1: Prepare a two-dimensional nanosheet MXene solution with a specific concentration;
[0006] S2: Using a specific cationic salt solution as the driving liquid, a forward osmosis membrane with specific ion selectivity is installed in the forward osmosis device;
[0007] S3: The prepared two-dimensional nanosheet MXene solution is added to the feed liquid side of the forward osmosis device to perform forward osmosis. Utilizing the specific ion selectivity of the forward osmosis membrane, cations reversely permeate into the interlayers of the MXene two-dimensional nanosheets, acting as ion intercalants to produce a pillaring effect. At the same time, the reversely permeated cations bind to the F-groups in the MXene material through strong ionic bonds, expanding the interlayer spacing to regulate the ion permeation performance of the prepared two-dimensional MXene membrane.
[0008] S4: After the forward osmosis is completed, the upper deposited metal ion intercalated MXene two-dimensional nanosheet layer is separated from the forward osmosis membrane and dried to prepare a metal ion intercalated two-dimensional MXene membrane.
[0009] In step S1, a two-dimensional nanosheet MXene solution of a specific concentration is prepared, specifically comprising the following steps:
[0010] S101: Add 1.6 g of LiF to 20 ml of 12 M HCl to prepare an etching solution, stir for 10 min to fully dissolve it, and then add 1 g of Ti3AlC2 to the etching solution in small batches at 40°C and stir at 500 rpm for 36 h;
[0011] S102: The etched suspension was centrifuged in a 50 ml centrifuge tube at 3500 rpm for 5 minutes, and the bottom precipitate was collected. 50 ml of 1 M HCl was then added and mixed evenly to remove excess LiF impurities. The suspension was centrifuged at 3500 rpm for 5 minutes, and the supernatant was skimmed off to collect the bottom precipitate. This was repeated three times.
[0012] S103: Add 50 ml of deionized water and centrifuge at 3500 rpm for 5 minutes to collect the bottom precipitate. Repeat several times until the pH of the supernatant is > 6. Collect the bottom precipitate, then add the bottom precipitate and 50 ml of deionized water to a 250 ml washing bottle, mix well, and pass argon for 3 minutes before sealing.
[0013] S104: Continuous ultrasound was performed in a 200W ice-water bath, during which the ice water was replaced every 30 minutes for a total of 1 hour. After the ultrasound was completed, a 50ml centrifuge tube was used for centrifugation at 3500 rpm for 1 hour to collect the upper liquid to prepare a MXene solution.
[0014] In step S4, the drying is specifically: placing in a 50° C. oven for drying for 5 hours to remove moisture.
[0015] The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as the driving agent solution, the forward osmosis membrane is clamped in the device and the dead-end forward osmosis device is assembled, and then a MXene solution is injected into the feed liquid side; through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the forward osmosis membrane is separated from the MXene layer on the membrane, and the MXene layer is dried to obtain a two-dimensional MXene membrane.
[0016] The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as the driving agent solution, a microfiltration membrane is placed on the forward osmosis membrane, and after the dead-end forward osmosis device is assembled, a MXene solution is injected into the feed liquid side; through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the microfiltration membrane composited with the MXene layer is separated from the forward osmosis membrane and dried to obtain a MXene composite membrane with the microfiltration membrane as the support layer.
[0017] The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as a driving agent solution, a polymer is used as an intercalant for MXene nanosheets, and a mixed solution of the polymer and MXene is used as a raw material liquid for forward osmosis membrane formation; after the forward osmosis membrane is clamped in the device and the dead-end forward osmosis device is assembled, the mixed solution of the polymer and MXene is injected into the feed liquid side; through the dead-end forward osmosis mode in which the driving liquid side is swept and the feed liquid side is not swept, water molecules in the mixed solution of the polymer and MXene enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the filter cake layer of the polymer intercalant and MXene two-dimensional nanosheet composite is separated from the forward osmosis membrane and dried to obtain a polymer intercalant composite MXene two-dimensional membrane.
[0018] The forward osmosis membrane is a flat membrane, and the device operates in a cross-flow mode: a forward osmosis mode with a driving liquid side sweep flow and a feed liquid side sweep flow. Due to the shear force generated when the MXene solution flows through the membrane surface, the forward osmosis is terminated after the MXene layer accumulated on the forward osmosis membrane reaches a certain thickness level. The two-dimensional MXene layer is separated from the forward osmosis membrane and dried to produce a MXene membrane.
[0019] Weigh 2.4106g of polysulfone into a beaker, add 7mL of dimethylformamide and 3mL of N-methylpyrrolidone, heat in a water bath at 60℃ and 300rpm and stir for 10h; put the stirred spinning solution into a 10mL syringe; turn on the electrospinning machine; set the temperature to 25℃, the humidity to 45%, and the liquid pushing speed to 0.1mm / min; fix the two-dimensional MXene membrane on the flat receiver of the electrospinning machine, and electrospinning is performed on one side of the two-dimensional MXene membrane. After the nanofibers cover the MXene membrane, remove the two-dimensional MXene membrane and fix the other side on the flat receiver, and continue electrospinning. After spinning is completed, a composite MXene membrane with high mechanical strength is obtained.
[0020] The forward osmosis membrane is a hollow membrane. During operation of the device, the MXene solution flows in the hollow membrane, and the MXene two-dimensional nanosheets are deposited on the inner wall of the hollow membrane, thereby preparing a forward osmosis membrane modified with two-dimensional nanosheets MXene.
[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention provides a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition, which has the characteristics of low energy consumption, and the novel two-dimensional MXene membrane prepared by the preparation method has the characteristics of small selectivity defects and high mechanical strength; the reverse osmotic cations act as ion intercalants to produce a pillaring effect, increase the interlayer spacing, select a suitable driving agent and its concentration, and use a forward osmosis membrane with specific ion selectivity to precisely control the ion permeability of the two-dimensional membrane; by changing the flow mode of the feed liquid on both sides of the forward osmosis membrane (sweep flow mode or dead end mode), the sweep flow rate on the driving liquid side during the forward osmosis process, the drying temperature, the drying time and other operating conditions, the nanosheet interlayer spacing, mechanical strength, charge, surface chemical properties, etc. of the two-dimensional membrane can be controlled. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 Schematic diagram of the process of preparing a two-dimensional material membrane by dead-end forward osmosis according to the present invention;
[0023] Figure 2 This is a physical picture of the two-dimensional MXene membrane prepared by dead-end forward osmosis (DEFO) in the present invention;
[0024] Figure 3 The relationship between the output power density and load resistance of the MXene membrane prepared by vacuum filtration, filter press and dead-end forward osmosis (DEFO) for reverse electrodialysis in the present invention.
[0025] Figure 4 The relationship between the permeation time (t) and the liquid volume (v) permeated per unit forward osmosis membrane area during the dead-end forward osmosis (DEFO) process of 80 ml of 1 g / L MXene solution under different driving agents in the present invention.
[0026] Figure 5 The permeability coefficient (A) and permeability impedance (R) of 80 ml 1 g / L MXene solution in the dead end forward osmosis (DEFO) process under different driving agents are shown in the present invention. DEFO ).
[0027] Figure 6 is the average water flux (J) during the dead-end forward osmosis (DEFO) process of 80 ml 1 g / L MXene solution under different driving agents in the present invention. W ).
[0028] Figure 7 The relationship between the output power density and load resistance of the MXene membrane prepared by the dead-end forward osmosis (DEFO) method under different driving agents for reverse electrodialysis power generation.
[0029] Figure 8The relationship between the permeation time (t) and the liquid volume (v) permeated per unit forward osmosis membrane area during the dead-end forward osmosis (DEFO) process of 80 ml of 1 g / L MXene solution at different NaCl driving agent concentrations in the present invention.
[0030] Figure 9 The permeability coefficient (A) and permeability resistance (R) of 80 ml 1 g / L MXene solution in the dead-end forward osmosis (DEFO) process at different NaCl driving agent concentrations are shown in the present invention. DEFO ).
[0031] Figure 10 is the average water flux (J) during the dead-end forward osmosis (DEFO) process of 80 ml 1 g / L MXene solution at different NaCl driving agent concentrations in the present invention. W ).
[0032] Figure 11 The relationship between the output power density and load resistance of the MXene membrane prepared by dead-end forward osmosis (DEFO) at different NaCl driving agent concentrations for reverse electrodialysis power generation is shown in the figure.
[0033] Figure 12 It is the relationship between the permeation time (t) and the volume of liquid permeated per unit forward osmosis membrane area (v) during the dead-end forward osmosis (DEFO) process of MXene solutions with different MXene contents (60, 80, 100 mg, 1 g / L) in the present invention.
[0034] Figure 13 The permeability coefficient (A) and permeability impedance (R) during the dead-end forward osmosis (DEFO) process of MXene solutions with different MXene contents (60, 80, 100 mg, 1 g / L) are shown in the figure. DEFO ).
[0035] Figure 14 is the average water flux (J) during the dead-end forward osmosis (DEFO) process of MXene solutions with different MXene contents (60, 80, 100 mg, 1 g / L) in the present invention. W ).
[0036] Figure 15 The relationship between the output power density and load resistance of the MXene membrane prepared by the dead-end forward osmosis (DEFO) method for reverse electrodialysis power generation in the present invention when the MXene solution has different MXene contents (60, 80, 100 mg, 1 g / L) is used.
[0037] Figure 16It is the relationship between the permeation time (t) and the volume of liquid permeated per unit forward osmosis membrane area (v) during the dead-end forward osmosis (DEFO) process of the present invention at different concentrations of MXene solution (26.7 mL, 40 mL, 80 mL).
[0038] Figure 17 The permeability coefficient (A) and permeability impedance (R) during the dead-end forward osmosis (DEFO) process of the present invention at different concentrations of MXene solution (26.7 mL, 40 mL, 80 mL) are shown in Figure 2. DEFO ).
[0039] Figure 18 is the average water flux (J) during the dead-end forward osmosis (DEFO) process of the present invention at different concentrations of MXene solution (26.7 mL, 40 mL, 80 mL). W ).
[0040] Figure 19 The relationship between the output power density and load resistance of the MXene membrane prepared by the dead-end forward osmosis (DEFO) method for reverse electrodialysis power generation in the present invention at different concentrations of MXene solution (26.7 mL, 40 mL, 80 mL).
[0041] Figure 20 Schematic diagram of the preparation of a MXene composite membrane with a microfiltration membrane as a support layer by dead-end forward osmosis in the present invention.
[0042] Figure 21 This is a schematic diagram of the preparation of a polymer intercalated composite two-dimensional membrane by dead-end forward osmosis in the present invention.
[0043] Figure 22 This is a schematic diagram of the composite two-dimensional membrane prepared by the present invention using an electrospinning support layer and forward osmosis to prepare a two-dimensional membrane by layer-by-layer stacking.
[0044] Figure 23 Schematic diagram of the preparation of a two-dimensional membrane by cross-flow forward osmosis in the present invention.
[0045] Figure 24 Schematic diagram of the preparation of a two-dimensional MXene nanosheet-modified forward osmosis membrane using a cylindrical forward osmosis membrane for the forward osmosis process of the present invention. DETAILED DESCRIPTION
[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0047] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0048] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.
[0049] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0050] like Figures 1 to 24 As shown, the present invention provides a technical solution: a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition, comprising the following steps:
[0051] S1: Prepare a two-dimensional nanosheet MXene solution with a specific concentration;
[0052] S2: Using a specific cationic salt solution as the driving liquid, a forward osmosis membrane with specific ion selectivity is installed in the forward osmosis device;
[0053] S3: The prepared two-dimensional nanosheet MXene solution is added to the feed liquid side of the forward osmosis device to perform forward osmosis. Utilizing the specific ion selectivity of the forward osmosis membrane, cations reversely permeate into the interlayers of the MXene two-dimensional nanosheets, acting as ion intercalants to produce a pillaring effect. At the same time, the reversely permeated cations bind to the F-groups in the MXene material through strong ionic bonds, expanding the interlayer spacing to regulate the ion permeation performance of the prepared two-dimensional MXene membrane.
[0054] S4: After the forward osmosis is completed, the upper deposited metal ion intercalated MXene two-dimensional nanosheet layer is separated from the forward osmosis membrane and dried to prepare a metal ion intercalated two-dimensional MXene membrane.
[0055] In step S1, a two-dimensional nanosheet MXene solution of a specific concentration is prepared, specifically comprising the following steps:
[0056] S101: Add 1.6 g of LiF to 20 ml of 12 M HCl to prepare an etching solution, stir for 10 min to fully dissolve it, and then add 1 g of Ti3AlC2 to the etching solution in small batches at 40°C and stir at 500 rpm for 36 h;
[0057] S102: The etched suspension was centrifuged in a 50 ml centrifuge tube at 3500 rpm for 5 minutes, and the bottom precipitate was collected. 50 ml of 1 M HCl was then added and mixed evenly to remove excess LiF impurities. The suspension was centrifuged at 3500 rpm for 5 minutes, and the supernatant was skimmed off to collect the bottom precipitate. This was repeated three times.
[0058] S103: Add 50 ml of deionized water and centrifuge at 3500 rpm for 5 minutes to collect the bottom precipitate. Repeat several times until the pH of the supernatant is > 6. Collect the bottom precipitate, then add the bottom precipitate and 50 ml of deionized water to a 250 ml washing bottle, mix well, and pass argon for 3 minutes before sealing.
[0059] S104: Continuous ultrasound was performed in a 200W ice-water bath, during which the ice water was replaced every 30 minutes for a total of 1 hour. After the ultrasound was completed, a 50ml centrifuge tube was used for centrifugation at 3500 rpm for 1 hour to collect the upper liquid to prepare a MXene solution.
[0060] In step S4, the drying is specifically: placing in a 50° C. oven for drying for 5 hours to remove moisture.
[0061] Detection of electricity generation characteristics of two-dimensional MXene membrane reverse electrodialysis (RED):
[0062] 1. The power generation characteristic detection device includes a self-made electrochemical cell, silver / silver chloride electrodes, a high-precision resistance box, an electrochemical workstation, and an electrometer;
[0063] 2. Add 0.5M NaCl to the high-concentration reaction cell and 0.01M NaCl to the low-concentration reaction cell; place a pair of silver / silver chloride electrodes in each of the two reaction cells, adjust the resistance box, and calculate the power density using an electrometer.
[0064] Example 1
[0065] A flat forward osmosis membrane is used as the base membrane, and the device operates in a dead-end mode. First, a specific cationic salt driving agent solution is configured. After the forward osmosis membrane with specific ion selectivity is clamped in the device and the dead-end forward osmosis device is assembled, the MXene solution is injected into the feed liquid side. Through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, the water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference. The real-time permeation amount of water molecules is recorded by connecting an electronic balance to the computer end, and then the relationship between 1 / J (the inverse of the filtration rate) and v (the volume of liquid permeated per unit membrane area) during the liquid phase deposition of the MXene solution is obtained. After completing the dead-end forward osmosis (DEFO) experiment, the forward osmosis membrane is separated from the MXene layer on the membrane and dried to obtain a two-dimensional MXene membrane, such as Figure 1 As shown in Figure 2, during the dead-end forward osmosis (DEFO) process, cations self-intercalate into the MXene membrane through reverse osmosis, creating a pillaring effect, expanding the interlayer spacing, and improving ion permeation performance. The reverse-permeated cations bind to the F- in the MXene material through strong ionic bonds.
[0066] The prepared MXene membrane was installed in a self-developed electrolytic cell. 0.5M NaCl was added to the high-concentration reaction cell, and 0.01M NaCl was added to the low-concentration reaction cell. A silver / silver chloride electrode was placed in the reaction cell, maintaining a constant distance of 10mm between the electrodes. The resistance box was adjusted, and the power density was measured and calculated using an electrometer.
[0067] The performance of MXene membranes prepared using vacuum filtration, filter press, and DEFO methods was compared. The MXene solution was filtered using a 0.22μm PVDF membrane at a vacuum of 0.1MPa; the MXene solution was filter press-filtered using a 0.22μm PVDF membrane at a pressure of 100kPa; and the MXene solution was DEFO-ed using a specific cation salt driver solution and the forward osmosis membrane with specific ion selectivity. Figure 2 A physical picture of the MXene film prepared by DEFO is shown. Figure 3The relationship between the output power density of MXene membranes prepared using vacuum filtration, pressure filtration, and DEFO for RED power generation and the load resistance is shown. From this, it can be seen that it is feasible to prepare MXene membranes using the DEFO method.
[0068] MXene membranes were prepared by changing the type of driving agent used in the DEFO process. The osmotic behavior curve, pure water flux, filtration impedance, and power density of RED power generation at different resistances are as Figure 4-7 shown. As Figure 5 can be seen, the coefficient of dead-end forward osmosis (A) decreases in the order of KCl > NaCl > CaCl2, and the osmotic impedance (R DEFO ) is the largest when using CaCl2; however, as Figure 6 shown, the average water flux (J w ) increases in the order of KCl < NaCl < CaCl2; when the prepared MXene two-dimensional membrane is used for reverse electrodialysis power generation, as Figure 7 shown, the output power density is the best when NaCl is used as the driving agent.
[0069] MXene membranes were prepared by changing the concentration of the driving agent in the DEFO process. The osmotic behavior curve, water flux, osmotic impedance, and power density of RED power generation at different resistances are as Figure 8-11 shown. As Figure 9 can be seen, as the concentration of the driving agent increases, A continuously decreases, and R DEFO is the smallest when using 2M NaCl; overall, as Figure 10 shown, as the concentration of the driving agent increases, J w increases; as Figure 11 shown, the output power density is the largest when using 2M NaCl as the driving agent.
[0070] The mass of MXene required in the DEFO film preparation process was changed. MXene two-dimensional membranes were prepared using 1g / L MXene solutions containing 60, 80, and 100mg of MXene two-dimensional nanosheets (i.e., 60, 80, and 100mL of 1g / L MXene solutions) as the feed solution, with a driving agent of 2M NaCl and a sweep flow rate of 3cm / s. The osmotic behavior curve, water flux, osmotic impedance, and power density of RED power generation at different resistances are as Figure 12-15 shown. As Figure 13-14 can be seen, during the forward osmosis process, A, R DEFO , and J w are less affected by the volume of the MXene solution; however, since the larger the volume of the MXene solution, the thicker the MXene nanosheet layer formed on the final forward osmosis membrane surface, that is, the thicker the prepared two-dimensional MXene membrane, which in turn affects the ion selectivity and power generation membrane impedance when applied to RED power generation. As Figure 15As shown in the figure, it can be seen that when 80 mL of 1 g / L MXene solution (containing 80 mg of MXene) is used as the DEFO membrane raw material solution, the prepared two-dimensional MXene membrane has the highest power generation power density.
[0071] By changing the MXene concentration in the DEFO membrane preparation process, MXene two-dimensional membranes were prepared using 1-3g / L MXene solution (containing 80mg MXene) as the raw material, 2M NaCl as the driving agent, and a sweep velocity of 3cm / s. The permeation behavior curve, pure water flux, permeation impedance, and power density of RED electricity generation under different resistances are shown in Figure 2. Figure 16-19 As shown. Figure 17 It can be seen that during the forward osmosis process, as the concentration of MXene solution increases, A remains almost constant, while R DEFO Continuously increasing; and, as Figure 18 As shown in Figure 2, with the increase of MXene solution concentration, J w Continuously decreasing; such as Figure 19 As shown in the figure, when 2 g / L MXene solution is used as the DEFO membrane raw material solution, the prepared two-dimensional MXene membrane has the highest power generation density.
[0072] From the above results, it can be seen that in the actual DEFO preparation of two-dimensional MXene membranes, the permeability coefficient (A) and permeation impedance (R) in the forward osmosis membrane preparation process should be balanced. DEFO ), water flux (J w ) and application areas such as RED power generation efficiency, and the optimal MXene membrane is obtained by regulating the type and concentration of the driving agent, the quality and concentration of MXene, etc.
[0073] Example 2
[0074] A flat forward osmosis membrane is used as the base membrane, and the device operates in a dead-end mode. A specific cationic salt solution is used as the driving agent solution; a flat microfiltration membrane is placed on a forward osmosis membrane with specific ion selectivity and the dead-end forward osmosis device is assembled, and then a MXene solution is injected into the feed liquid side; through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, the water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the MXene layer composite microfiltration membrane is separated from the forward osmosis membrane and dried to obtain a MXene composite membrane with the microfiltration membrane as the support layer, such as Figure 20 shown.
[0075] Example 3
[0076] A flat forward osmosis membrane is used as the base membrane, and the device operates in a dead-end mode. A specific cationic salt solution is used as the driving agent solution, and polymers such as extracellular polymers (EPS), sodium alginate (SA), bovine serum albumin (BSA), humic acid (HA), alginate-like substances (ALE), silk fibroin (SP), etc. are used as intercalants for MXene nanosheets, and their mixed solution with MXene is used as the raw material liquid for forward osmosis membrane making. After the forward osmosis membrane with specific ion selectivity is clamped in a dead-end forward osmosis device and the dead-end forward osmosis device is assembled, a mixed solution of polymer and MXene is injected on the feed liquid side. Through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, the water molecules in the mixed solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference. After completing the dead-end forward osmosis, the filter cake layer of the composite of the intercalant and the MXene two-dimensional nanosheet is separated from the forward osmosis membrane and dried to obtain a polymer intercalant composite MXene two-dimensional membrane, such as Figure 21 shown.
[0077] Example 4
[0078] A flat forward osmosis membrane is used as the base membrane, and the device operates in a cross-flow mode. By driving the forward osmosis mode with liquid side sweep flow and feed side sweep flow, due to the shear force generated when the MXene solution flows through the membrane surface, the forward osmosis is terminated when the MXene layer accumulated on the forward osmosis membrane reaches a certain thickness level, and the two-dimensional MXene layer is separated from the forward osmosis membrane and dried to obtain a MXene membrane, such as Figure 22 shown.
[0079] Example 5
[0080] A two-dimensional MXene membrane was prepared using the method of Example 1-4. 2.4106 g of polysulfone (PSf) was weighed into a beaker, and 7 mL of dimethylformamide (DMF) and 3 mL of N-methylpyrrolidone (NMP) were added and heated in a water bath at 60 ° C and 300 rpm with stirring for 10 h; the stirred spinning solution was placed into a 10 mL syringe; the electrospinning machine was turned on; the temperature was set to 25 ° C, the humidity was set to 45%, and the liquid pushing speed was set to 0.1 mm / min. The two-dimensional MXene membrane was fixed on a flat plate receiver of the electrospinning machine, and electrospinning was performed on one side of the two-dimensional MXene membrane. After the nanofibers covered the two-dimensional MXene membrane, the two-dimensional MXene membrane was removed and the other side was fixed on the flat plate receiver, and electrospinning was continued. After the spinning was completed, a composite MXene membrane with high mechanical strength was obtained, such as Figure 23 shown.
[0081] Example 6
[0082] Using a cylindrical hollow membrane as the base membrane, the MXene solution flows in the hollow membrane during device operation, and MXene two-dimensional nanosheets are deposited on the inner wall of the hollow membrane, thereby preparing a two-dimensional nanosheet MXene modified forward osmosis membrane, such as Figure 24 shown.
[0083] The present invention provides a novel two-dimensional MXene membrane preparation method based on forward osmosis deposition, which has the following advantages and effects:
[0084] (1) The preparation method of the present invention is a novel method for preparing a two-dimensional material membrane with low energy consumption, low selective defects and high mechanical strength;
[0085] (2) The reverse osmosis cations of the present invention act as ion intercalants to produce a pillaring effect, increasing the interlayer spacing. By selecting an appropriate driving agent and its concentration and using a forward osmosis membrane with specific ion selectivity, the ion permeation performance of the two-dimensional membrane can be precisely controlled;
[0086] (3) The present invention can flexibly change the flow mode (sweep flow mode or dead end mode) of the feed liquid on both sides of the forward osmosis membrane, the sweep flow velocity on the driving liquid side during the forward osmosis process, the drying temperature, the drying time and other operating conditions, and can regulate the nanosheet interlayer spacing, mechanical strength, charge, surface chemical properties, etc. of the two-dimensional membrane. A typical application is to obtain a MXene two-dimensional membrane with excellent ion permeability.
[0087] Any variation of the present invention patent falls within the scope of protection of this patent. The driving agent used in forward osmosis can be a salt solution such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, and ferric chloride; the concentration of the driving agent used is not limited to 1-3M; the MXene layer after the dead-end forward osmosis can be dehydrated by natural drying, oven drying, freeze drying, etc.; when using oven drying, the temperature is not limited to 50°C, and the drying time is not limited to 4-7h; the intercalating agent used is not limited to extracellular polymers (EPS), sodium alginate (SA), bovine serum albumin (BSA), humic acid (HA), alginate-like (ALE), and silk fibroin (SP); when using hollow fiber membranes to prepare two-dimensional material composite forward osmosis membranes, the operating mode can be external pressure; the electrospun nanofibers are not limited to polysulfone (PSf) materials; the use of the prepared MXene membrane is not limited to reverse electrodialysis power generation; in addition to MXene, the two-dimensional nanosheet material can also be other two-dimensional materials such as covalent organic frameworks (COFs) and metal organic frameworks (MOFs).
[0088] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.
Claims
1. A novel method for preparing two-dimensional MXene membranes based on forward osmosis deposition, characterized by: The following steps are involved: S1: Prepare a two-dimensional nanosheet MXene solution with a specific concentration; S2: Using a specific cationic salt solution as the driving liquid, a forward osmosis membrane with specific ion selectivity is installed in the forward osmosis device; S3: The prepared two-dimensional nanosheet MXene solution is added to the feed liquid side of the forward osmosis device to perform forward osmosis. Utilizing the specific ion selectivity of the forward osmosis membrane, cations reversely permeate into the interlayers of the MXene two-dimensional nanosheets, acting as ion intercalants to produce a pillaring effect. At the same time, the reversely permeated cations bind to the F-groups in the MXene material through strong ionic bonds, expanding the interlayer spacing to regulate the ion permeation performance of the prepared two-dimensional MXene membrane. S4: After the forward osmosis is completed, the upper deposited metal ion intercalated MXene two-dimensional nanosheet layer is separated from the forward osmosis membrane and dried to prepare a metal ion intercalated two-dimensional MXene membrane. In step S1, a two-dimensional nanosheet MXene solution of a specific concentration is prepared, which specifically includes the following steps: S101: Add 1.6 g of LiF to 20 ml of 12 M HCl to prepare an etching solution, stir for 10 min to fully dissolve it, and then add 1 g of Ti3AlC2 to the etching solution in small batches at 40°C and stir at 500 rpm for 36 h; S102: The etched suspension was centrifuged in a 50 ml centrifuge tube at 3500 rpm for 5 minutes, and the bottom precipitate was collected. 50 ml of 1 M HCl was then added and mixed evenly to remove excess LiF impurities. The suspension was centrifuged at 3500 rpm for 5 minutes, and the supernatant was skimmed off to collect the bottom precipitate. This was repeated three times. S103: Add 50 ml of deionized water and centrifuge at 3500 rpm for 5 minutes to collect the bottom precipitate. Repeat several times until the pH of the supernatant is > 6. Collect the bottom precipitate, then add the bottom precipitate and 50 ml of deionized water to a 250 ml washing bottle, mix well, and pass argon for 3 minutes before sealing. S104: Continuous ultrasound was performed in a 200W ice-water bath, during which the ice water was replaced every 30 minutes for a total of 1 hour. After the ultrasound was completed, a 50ml centrifuge tube was used for centrifugation at 3500 rpm for 1 hour to collect the upper liquid to prepare a MXene solution.
2. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The drying in step S4 is specifically: placing in a 50° C. oven for 5 hours to remove moisture.
3. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as the driving agent solution, the forward osmosis membrane is clamped in the device and the dead-end forward osmosis device is assembled, and then a MXene solution is injected into the feed liquid side; through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the forward osmosis membrane is separated from the MXene layer on the membrane, and the MXene layer is dried to obtain a two-dimensional MXene membrane.
4. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as the driving agent solution, a microfiltration membrane is placed on the forward osmosis membrane, and after the dead-end forward osmosis device is assembled, a MXene solution is injected into the feed liquid side; through the dead-end forward osmosis mode with sweep flow on the driving liquid side and no sweep flow on the feed liquid side, water molecules in the MXene solution enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the microfiltration membrane composited with the MXene layer is separated from the forward osmosis membrane and dried to obtain a MXene composite membrane with the microfiltration membrane as the support layer.
5. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The forward osmosis membrane is a flat membrane, and the device operates in a dead-end mode: a specific cationic salt solution is used as a driving agent solution, a polymer is used as an intercalant for MXene nanosheets, and a mixed solution of the polymer and MXene is used as a raw material liquid for forward osmosis membrane formation; after the forward osmosis membrane is clamped in the device and the dead-end forward osmosis device is assembled, the mixed solution of the polymer and MXene is injected into the feed liquid side; through the dead-end forward osmosis mode in which the driving liquid side is swept and the feed liquid side is not swept, water molecules in the mixed solution of the polymer and MXene enter the driving liquid side from the feed liquid side under the drive of the high osmotic pressure difference; after the dead-end forward osmosis is completed, the filter cake layer of the polymer intercalant and MXene two-dimensional nanosheet composite is separated from the forward osmosis membrane and dried to obtain a polymer intercalant composite MXene two-dimensional membrane.
6. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The forward osmosis membrane is a flat membrane, and the device operates in a cross-flow mode: a forward osmosis mode with a driving liquid side sweep flow and a feed liquid side sweep flow. Due to the shear force generated when the MXene solution flows through the membrane surface, the forward osmosis is terminated after the MXene layer accumulated on the forward osmosis membrane reaches a certain thickness level. The two-dimensional MXene layer is separated from the forward osmosis membrane and dried to produce a MXene membrane.
7. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: Weigh 2.4106g of polysulfone into a beaker, add 7mL of dimethylformamide and 3mL of N-methylpyrrolidone, heat in a water bath at 60℃ and 300rpm and stir for 10h; put the stirred spinning solution into a 10mL syringe; turn on the electrospinning machine; set the temperature to 25℃, the humidity to 45%, and the liquid pushing speed to 0.1mm / min; fix the two-dimensional MXene membrane on the flat receiver of the electrospinning machine, and electrospinning is performed on one side of the two-dimensional MXene membrane. After the nanofibers cover the MXene membrane, remove the two-dimensional MXene membrane and fix the other side on the flat receiver, and continue electrospinning. After spinning is completed, a composite MXene membrane with high mechanical strength is obtained.
8. The method for preparing a novel two-dimensional MXene membrane based on forward osmosis deposition according to claim 1, characterized in that: The forward osmosis membrane is a hollow membrane. During operation of the device, the MXene solution flows in the hollow membrane, and the MXene two-dimensional nanosheets are deposited on the inner wall of the hollow membrane, thereby preparing a forward osmosis membrane modified with two-dimensional nanosheets MXene.