Hydrophobic Ti3C2T x and its application in membraneless capacitor deionized water treatment

Abstract

The present invention relates to the field of preparation of flow electrodes and capacitive deionization application technology, in particular to hydrophobic Ti3C2T x The present invention adopts hydrophobic Ti3C2T x The prepared flow electrode slurry is used as the negative flow electrode, and the flow electrode slurry prepared by BMIM Ac is used as the positive flow electrode. The flow electrodes are placed in a reactor, and the negative flow electrode and the positive flow electrode are directly in contact with seawater, brackish water or wastewater respectively. An electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion adsorption. x As a mobile electrode, FCDI is realized without membrane based on stratification according to density difference. The energy of ions passing through the liquid-liquid interface is less than the energy of the solid-liquid interface, which can more efficiently realize seawater desalination, brackish water desalination and wastewater treatment. The membraneless reactor improves the shortcomings of FCDI membrane pollution, membrane clogging, high cost and frequent membrane replacement.

Description

Technical Field

[0001] The present invention relates to the field of preparation of flow electrodes and capacitive deionization application technology, in particular to hydrophobic Ti3C2T x And its application in membraneless capacitive deionized water treatment. Background Art

[0002] FCDI (Flow-Electrode Capacitive Deionization) is a new water treatment technology primarily used in seawater desalination, brackish water desalination, and wastewater treatment. It is an improved version of traditional capacitive deionization (CDI) technology, using flow electrodes to improve ion removal rates. FCDI builds on traditional CDI by introducing flow electrodes, where the electrodes flow in the form of a suspension. The flow electrodes continuously renew the electrode surface, providing a continuous supply of active sites for ion adsorption, thereby improving ion removal rates. Ion exchange membranes in FCDI offer advantages such as selective transport, short-circuit prevention, improved efficiency, maintained electrical neutrality, extended electrode life, and optimized system design, ensuring efficient and stable system operation.

[0003] However, the ion exchange membranes used in FCDI suffer from disadvantages such as high cost, susceptibility to fouling, temperature limitations, limited selectivity, and a limited lifespan. Many factors must be considered in practical applications. During capacitive deionization, the large number of ions passing through the ion exchange membrane can lead to contamination and clogging, reducing its lifespan and affecting reactor efficiency. Frequent membrane replacement may be necessary, increasing process costs. Researchers have developed alternative membranes, including MOF membranes, hydrogel membranes, and bio-based membranes. While these membranes can reduce process costs to a certain extent, the membranes themselves present challenges that are difficult to overcome. Furthermore, the interfacial energy at the solid-liquid interface is typically high because the interaction between molecules on the solid surface and liquid molecules is weak. This means that ions must overcome a high energy barrier to cross the interface. At the solid-liquid interface, ion migration is often restricted by the solid surface, which can result in slow ion migration rates. Consequently, the energy required for ions to cross the interface is high. These shortcomings also limit the water treatment capabilities of FCDI to a certain extent. Typical flow electrodes use sodium salt deionized water as the electrolyte and activated carbon as the electrode material. These substances can mix with the ionic solution, so the system cannot operate stably without a membrane. However, there is currently a lack of membrane-free flow electrode capacitive deionization technology that can achieve stable operation. Summary of the Invention

[0004] In order to solve the problem of the lack of membrane-free flow electrode capacitive deionization technology that can achieve stable operation, the present invention provides a hydrophobic Ti3C2T x And its application in membraneless capacitive deionized water treatment.

[0005] In the first aspect, the present invention provides a hydrophobic Ti3C2T x The preparation method comprises the following steps:

[0006] S1. Under inert gas protection, Ti3AlC2 powder and ZnCl2 powder are uniformly mixed and then heat treated under inert gas protection;

[0007] S2. After the heat treatment reaction is completed, the residual ZnCl2 is removed by washing with deionized water; Ti3C2T is obtained by filtration. x and Zn mixture; ultrasonic dispersion in deionized water, centrifuge separation, and vacuum drying to obtain hydrophobic Ti3C2T x .

[0008] As a further improvement of the technical solution of the present invention, in step S1, the mass ratio of the Ti3AlC2 powder to the ZnCl2 powder is 1:6.

[0009] As a further improvement of the technical solution of the present invention, in step S1, the heat treatment temperature is 550° C. and the time is 5 hours.

[0010] In the second aspect, the present invention provides a hydrophobic Ti3C2T x The hydrophobic Ti3C2T obtained by the preparation method x Application as a flow electrode in capacitive deionization water treatment.

[0011] As a further disclosure of the application technical solution of the present invention, during the capacitive deionized water treatment, a membrane-free treatment is used.

[0012] As a further disclosure of the application technical solution of the present invention, hydrophobic Ti3C2T x The prepared flow electrode slurry is used as the negative flow electrode, and the flow electrode slurry prepared by BMIM Ac is used as the positive flow electrode, which are placed in a reactor. The negative flow electrode and the positive flow electrode are located at relative positions in the reactor respectively, and there is water to be treated between the negative flow electrode and the positive flow electrode. The negative flow electrode and the positive flow electrode are in direct contact with the water to be treated respectively, and an electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion adsorption.

[0013] As a further disclosure of the application technical solution of the present invention, the preparation method of the negative electrode mobile electrode is: dissolving BMIM TFSI in tetrahydrofuran solution, adding hydrophobic Ti3C2T xAfter thorough mixing, the obtained slurry is BMIM TFSI+Ti3C2T x Flow electrode slurry; the preparation method of the positive flow electrode is: dissolving BMIM Ac in tetrahydrofuran solution, adding AC and mixing thoroughly, and the obtained slurry is BMIM Ac+AC flow electrode slurry.

[0014] As a further disclosure of the application technical solution of the present invention, according to the density difference stratification, one of the negative electrode mobile electrode and the positive electrode mobile electrode floats on the upper layer of the water to be treated, and the other mobile electrode sinks to the lower layer of the water to be treated.

[0015] As a further disclosure of the application technical solution of the present invention, after the capacitive deionized water treatment is completed, a reverse electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion desorption and ion enrichment.

[0016] As a further disclosure of the application technical solution of the present invention, the reactor includes at least one FCDI device for adsorption and / or at least one FCDI device for desorption; each FCDI device includes an FCDI device and a power supply, each FCDI device has a cavity inside, and the cavity is divided into an upper cavity, a middle cavity and a lower cavity by a first partition and a second partition, the first partition has a first fluid channel connecting the upper cavity and the middle cavity, the second partition has a second fluid channel connecting the middle cavity and the lower cavity, and the two ends of the power supply are electrically connected to the interior of the upper cavity and the lower cavity respectively.

[0017] As a further disclosure of the application technical solution of the present invention, when the reactor includes at least one FCDI device for adsorption and at least one FCDI device for desorption; the FCDI device for adsorption includes a first FCDI device, a first power supply, a first pump body, a third pump body, a first slurry tank and a treatment tank, and the FCDI device for desorption includes a second FCDI device, a second power supply, a second pump body, a fourth pump body, a second slurry tank and an enrichment tank;

[0018] The liquid inlet pipe and the liquid outlet pipe of the first pump body are respectively connected to the processing tank and the liquid inlet of the middle cavity of the first FCDI device, and the liquid outlet of the middle cavity of the first FCDI device is connected to the processing tank;

[0019] The liquid inlet pipe and the liquid outlet pipe of the second pump body are respectively connected to the liquid inlet of the enrichment tank and the middle cavity of the second FCDI device, and the liquid outlet of the middle cavity of the second FCDI device is connected to the enrichment tank;

[0020] The liquid inlet pipe and liquid outlet pipe of the third pump body are respectively connected to the first slurry pool and the liquid inlet of the upper cavity of the first FCDI device, and the upper cavity of the second FCDI device is connected to the first slurry pool; the liquid inlet pipe and liquid outlet pipe of the fourth pump body are respectively connected to the second slurry pool and the liquid inlet of the lower cavity of the first FCDI device, and the lower cavity of the second FCDI device is connected to the second slurry pool; and the upper cavity of the first FCDI device and the upper cavity of the second FCDI device are connected by a pipe, and the upper cavity of the first FCDI device and the lower cavity of the second FCDI device are connected by a pipe.

[0021] The present invention provides a hydrophobic Ti3C2T x Its application in membraneless capacitor deionized water treatment has the following advantages compared with existing technologies:

[0022] The present invention prepares hydrophobic Ti3C2T x As a mobile electrode, FCDI achieves membrane-free stratification based on density differences. The energy of ions passing through the liquid-liquid interface is lower than the energy of ions passing through the solid-liquid interface, enabling more efficient desalination of seawater, brackish water, and wastewater treatment. The membraneless reactor overcomes the shortcomings of FCDI, such as membrane fouling, clogging, high costs, and frequent membrane replacement. Furthermore, the recycling of electrode materials and ionic liquids significantly reduces the cost of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 The hydrophobic Ti3C2T obtained in Example 1 of the present invention x Scanning electron microscope image of .

[0026] Figure 2 The hydrophobic Ti3C2T obtained in Example 1 of the present invention x X-ray diffraction pattern of .

[0027] Figure 3 The hydrophobic Ti3C2T obtained in Example 1 of the present invention x The contact angle test results.

[0028] Figure 4 The hydrophobic Ti3C2T obtained in Example 1 of the present inventionx Electrochemical characterization.

[0029] Figure 5 This is a schematic diagram of the connection between the FCDI device and the power supply.

[0030] Figure 6 Schematic diagram of dynamic desalination of brine to be treated.

[0031] Figure 7 It is a structural schematic diagram of the push-pull plate of the present invention.

[0032] Figure 8 This is a connection diagram of the adsorption process and the desorption process in the reactor in Example 4 of the present invention.

[0033] Figure 9 This is a schematic diagram of the results of the desalination test of the brine to be treated in Example 4 of the present invention.

[0034] Figure 10 is the recovery rate of electrode material, ionic liquid and tetrahydrofuran in the flow electrode slurry of the present invention.

[0035] In the figure: 11-first FCDI device, 12-first power supply, 13-first pump body, 14-second FCDI device, 15-second power supply, 16-second pump body, 17-third pump body, 18-fourth pump body, 19-treatment tank, 20-enrichment tank, 21-first slurry tank, 22-second slurry tank, 101-upper packaging plate, 102-first partition plate, 103-second partition plate, 104-first fluid channel, 105-second fluid channel, 106-lower packaging plate, 107-first push-pull plate, 108-second push-pull plate. DETAILED DESCRIPTION

[0036] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] The present invention provides a hydrophobic Ti3C2T x A specific embodiment of the preparation method comprises the following steps:

[0039] S1. Under inert gas protection, Ti3AlC2 powder and ZnCl2 powder are uniformly mixed and then heat treated under inert gas protection;

[0040] S2. After the heat treatment reaction is completed, the residual ZnCl2 is removed by washing with deionized water; Ti3C2T is obtained by filtration. x and Zn mixture; ultrasonic dispersion in deionized water, centrifuge separation, and vacuum drying to obtain hydrophobic Ti3C2T x .

[0041] In the present invention, the hydrophobic Ti3C2T x Middle T x Represents a surface functional group, in the present invention, T x Represents -Cl.

[0042] In some examples, in step S1, the inert gas may be selected from nitrogen, helium or argon, etc. Of course, in step S1, the inert gas used in the two stages of powder mixing and heat treatment may be the same inert gas or different inert gases. When the present invention is implemented, the uniform mixing of Ti3AlC2 powder and ZnCl2 powder is carried out in a glove box with a nitrogen atmosphere; and the heat treatment is carried out under an argon atmosphere. During the heat treatment, the mixed powder of Ti3AlC2 and ZnCl2 is preferably placed in an alumina crucible for heat treatment. The present invention has no special requirements for the heat treatment container, but it is necessary to ensure that the mixed powder of Ti3AlC2 powder and ZnCl2 does not react with the heat treatment container.

[0043] In some examples, in step S2, in order to remove the residual ZnCl2, the present invention uses deionized water for washing for more than 5 times. x When the mixture of Ti3C2T and Zn was prepared, the centrifuge speed was 3000 rpm and the centrifugation time was 10 min. Zn precipitated at the bottom and the upper layer solution (containing hydrophobic Ti3C2T x ), the centrifuge speed was set to 6000 rpm again, the centrifugation time was 10 min, and the precipitate was filtered. The solid obtained by filtration was hydrophobic Ti3C2T x During vacuum drying, the drying temperature used was 40°C.

[0044] In one example, in step S1, the mass ratio of the Ti3AlC2 powder to the ZnCl2 powder is 1:6.

[0045] In another example, in step S1, the heat treatment temperature is 550° C. and the time is 5 hours.

[0046] The present invention further provides a hydrophobic Ti3C2T x The hydrophobic Ti3C2T obtained by the preparation method x Application as a flow electrode in capacitive deionization water treatment.

[0047] In the present invention, the capacitive deionized water treatment can be performed using a membrane. Preferably, the capacitive deionized water treatment is performed without a membrane. The membrane herein includes any one of an ion exchange membrane, a MOF membrane, a hydrogel membrane, and a bio-based membrane.

[0048] In the specific implementation, hydrophobic Ti3C2T x The prepared flow electrode slurry is used as the negative flow electrode, and the flow electrode slurry prepared by BMIM Ac is used as the positive flow electrode, which are placed in a reactor. The negative flow electrode and the positive flow electrode are located at relative positions in the reactor respectively, and there is water to be treated between the negative flow electrode and the positive flow electrode. The negative flow electrode and the positive flow electrode are in direct contact with the water to be treated respectively, and an electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion adsorption.

[0049] Furthermore, after the capacitive deionized water treatment is completed, a reverse electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion desorption and ion enrichment.

[0050] The water to be treated in the present invention includes seawater, brackish water, wastewater and the like.

[0051] In the present invention, the relative position can be up and down, left and right. In some examples, based on the density difference, one of the negative and positive flow electrodes floats on the upper layer of the water to be treated, while the other flow electrode sinks to the lower layer of the water to be treated.

[0052] Specifically, the preparation method of the negative electrode flow electrode is as follows: dissolving BMIM TFSI (Chinese name: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl imide)) in tetrahydrofuran solution, adding hydrophobic Ti3C2T x After thorough mixing, the obtained slurry is BMIM TFSI+Ti3C2T x Flow electrode slurry.

[0053] In some examples, when BMIM TFSI is dissolved in tetrahydrofuran solution, the volume ratio of BMIM TFSI to tetrahydrofuran solution is 8:15. The mass fraction of BMIM TFSI in the mixture of BMIM TFSI and tetrahydrofuran solution is 46%. x The amount of addition must ensure that the obtained TFSI+Ti3C2T x The density of the electrode slurry is greater than the density of the water to be treated (seawater, brackish water or wastewater). In the following example, the present invention is to dissolve 8 mL of BMIM TFSI in 15 mL of tetrahydrofuran solution and add 500 mg of hydrophobic Ti3C2T xThe slurry density obtained by ultrasonic mixing is 1.1 g / cm 3 .

[0054] Specifically, the preparation method of the positive electrode flow electrode is as follows: BMIM Ac (Chinese name: 1-butyl-3-methylimidazolium acetate) is dissolved in tetrahydrofuran solution, AC (Chinese name: activated carbon) is added and mixed thoroughly, and the obtained slurry is BMIM Ac+AC flow electrode slurry.

[0055] In some examples, the volume ratio of BMIM Ac to tetrahydrofuran solution is 8:15. The mass fraction of BMIM Ac in the mixture of BMIM Ac and tetrahydrofuran solution is 40%. The amount of AC added must ensure that the density of the resulting BMIM Ac+AC flow electrode slurry is less than the density of the water to be treated (seawater, brackish water, or wastewater). In the examples provided below, the present invention is to dissolve 8 mL of BMIM Ac in 15 mL of tetrahydrofuran solution and add 500 mg of AC. The slurry density obtained by ultrasonic mixing is 0.9 g / cm 3 .

[0056] To explain the application in more detail, the present invention provides a reactor comprising at least one FCDI device for adsorption and / or at least one FCDI device for desorption; each FCDI device comprises an FCDI component and a power supply, each FCDI component having a cavity therein, the cavity being divided into an upper cavity, a middle cavity, and a lower cavity by a first partition 102 and a second partition 103; the first partition 102 having a first fluid channel 104 connecting the upper cavity and the middle cavity; the second partition 103 having a second fluid channel 105 connecting the middle cavity and the lower cavity; and the two ends of the power supply being electrically connected to the interior of the upper cavity and the lower cavity, respectively.

[0057] In some examples, the FCDI device for adsorption and the FCDI device for desorption can be the same FCDI device. During specific operation, the two ends of the power supply can be connected positively or negatively (an electric field or a reverse electric field is applied between the negative flow electrode and the positive flow electrode).

[0058] In some cases, to maintain a stable boundary between the fluids in the upper, middle, and lower cavities, a first push-pull plate 107 is provided at the first fluid channel 104 of the first baffle 102, and a second push-pull plate 108 is provided at the second fluid channel 105 of the second baffle 103. Before the application of an electric field (or a reverse electric field), when the fluids in the upper, middle, and lower cavities enter their respective cavities, the first push-pull plate 107 and the second push-pull plate 108 are closed. When the fluids fill their respective cavities, the first push-pull plate 107 and the second push-pull plate 108 are opened, and the electric field (or reverse electric field) is applied. In some examples, after closing the first push-pull plate 107 and the second push-pull plate 108, the first push-pull plate 107, the second push-pull plate 108 and the corresponding partition can be sealed together; in some examples, after closing the first push-pull plate 107 and the second push-pull plate 108, the first push-pull plate 107, the second push-pull plate 108 and the corresponding partition have a clearance fit (non-sealed state).

[0059] In the following embodiment, when the first and second push-pull plates 107 and 108 are opened, the first and second fluid channels 104 and 105 are fully connected to the adjacent cavity spaces. The opening and closing of the push-pull plates can be adjusted to suit specific circumstances, allowing for full or partial communication between adjacent cavities. To facilitate opening and closing the push-pull plates, the push-pull plates are preferably provided with push-pull rods.

[0060] The reactor provided by the present invention includes at least the following three situations, specifically:

[0061] (i) When the reactor only performs capacitive deionized water treatment (ion adsorption), the reactor includes at least one FCDI device for adsorption, the FCDI device for adsorption includes a first FCDI device 11 and a first power supply 12, the upper cavity of the first FCDI device 11 is filled with BMIM Ac+AC flow electrode slurry, the middle cavity is filled with water to be treated, and the lower cavity is filled with BMIM TFSI+Ti3C2T x The electrode slurry flows through the reactor; the first power source 12 is connected to the interior of the upper and lower cavities of the first FCDI device 11 via wires. In some cases, to improve water treatment efficiency and throughput, the reactor further includes a first pump 13 and a treatment tank 19. The central cavity of the first FCDI device 11 has a liquid inlet and a liquid outlet. The liquid inlet and outlet pipes of the first pump 13 are connected to the liquid inlet of the treatment tank 19 and the central cavity of the first FCDI device 11, respectively. The liquid outlet of the central cavity of the first FCDI device 11 is connected to the treatment tank 19.

[0062] (ii) When the reactor is only used for ion enrichment (ion desorption), the reactor includes at least one FCDI device for desorption, which includes a second FCDI device 14 and a second power supply 15. The upper cavity of the second FCDI device 14 is filled with BMIM Ac+AC current electrode slurry adsorbed with positive ions, the middle cavity is filled with deionized water, and the lower cavity is filled with BMIM TFSI+Ti3C2T x The electrode slurry flows through the second power supply 15, which is connected to the interior of the upper and lower cavities of the second FCDI device 14 via wires. In some cases, to increase the enrichment rate, the reactor further includes a second pump 16 and an enrichment tank 20. The middle cavity of the second FCDI device 14 has a liquid inlet and a liquid outlet. The liquid inlet and liquid outlet of the second pump 16 are connected to the liquid inlet of the enrichment tank 20 and the liquid outlet of the middle cavity of the second FCDI device 14, respectively. The liquid outlet of the middle cavity of the second FCDI device 14 is connected to the enrichment tank 20.

[0063] (iii) If the reactor needs to achieve capacitive deionized water treatment and ion enrichment, the reactor includes at least one FCDI device for adsorption and at least one FCDI device for desorption; the FCDI device for adsorption includes a first FCDI device 11, a first power supply 12, a first pump body 13, a third pump body 17, a first slurry tank 21 and a treatment tank 19, and the FCDI device for desorption includes a second FCDI device 14, a second power supply 15, a second pump body 16, a fourth pump body 18, a second slurry tank 22 and an enrichment tank 20;

[0064] The upper cavity of the first FCDI device 11 is filled with BMIM Ac+AC current electrode slurry, the upper cavity of the second FCDI device 14 is filled with BMIM Ac+AC current electrode slurry adsorbed with positive ions, and the lower cavity of the first FCDI device 11 is filled with BMIM TFSI+Ti3C2T x The electrode slurry is flowed, and the lower cavity of the second FCDI device 14 is filled with BMIMTFSI+Ti3C2T adsorbed with negative ions. x The electrode slurry is flowed in the middle cavity of the first FCDI device 11 and the middle cavity of the second FCDI device 14 is filled with deionized water.

[0065] The first power source 12 is connected to the upper cavity and the lower cavity of the first FCDI device 11 through wires, and the second power source 15 is connected to the upper cavity and the lower cavity of the second FCDI device 14 through wires.

[0066] The liquid inlet and outlet pipes of the first pump body 13 are respectively connected to the treatment tank 19 and the liquid inlet of the middle cavity of the first FCDI device 11. The liquid outlet of the middle cavity of the first FCDI device 11 is connected to the treatment tank 19. The liquid inlet and outlet pipes of the second pump body 16 are respectively connected to the liquid inlet of the middle cavity of the enrichment tank 20 and the second FCDI device 14. The liquid outlet of the middle cavity of the second FCDI device 14 is connected to the enrichment tank 20.

[0067] The inlet and outlet pipes of the third pump body 17 are connected to the first slurry pool 21 and the liquid inlet of the upper cavity of the first FCDI device 11, respectively. The upper cavity of the second FCDI device 14 is connected to the first slurry pool 21. The inlet and outlet pipes of the fourth pump body 18 are connected to the second slurry pool 22 and the liquid inlet of the lower cavity of the first FCDI device 11, respectively. The lower cavity of the second FCDI device 14 is connected to the second slurry pool 22. Furthermore, the upper cavity of the first FCDI device 11 and the upper cavity of the second FCDI device 14 are connected by a pipe, and the upper cavity of the first FCDI device 11 and the lower cavity of the second FCDI device 14 are connected by a pipe.

[0068] It should be noted that when the reactor described in the present invention needs to achieve capacitive deionized water treatment and ion enrichment, the capacitive deionized water treatment and ion enrichment can be carried out simultaneously, or the capacitive deionized water treatment can be carried out first and then the ion enrichment. When the capacitive deionized water treatment and ion enrichment are carried out simultaneously, it is necessary to provide insulation measures between the FCDI device used for adsorption and the FCDI device used for desorption. Furthermore, the FCDI device has an upper packaging plate 101 and a lower packaging plate 106. Specifically, the upper packaging plate 101 and the lower packaging plate 106 are located at the top and bottom, respectively. Each packaging plate is made of insulating material.

[0069] In some cases, independent valves may be provided on each pipe or pipeline of the present invention according to actual conditions.

[0070] The specific embodiments of the present invention are described in detail below.

[0071] Example 1:

[0072] The preparation method of the mobile electrode comprises the following steps:

[0073] In a glove box under nitrogen protection, 1g of Ti3AlC2 powder and 6g of ZnCl2 powder were thoroughly ground and mixed. Under argon protection, the alumina crucible containing the mixed powder was placed in a tube furnace and heated to 550℃ at a rate of 5℃ / min and kept at this temperature for 5h to react. After the reaction was completed, the temperature was cooled to room temperature at a rate of 5℃ / min. The reaction products were obtained, including hydrophobic Ti3C2T x、ZnCl2、Zn。

[0074] The product after the reaction was washed with deionized water and filtered to obtain hydrophobic Ti3C2T x and Zn mixture. Add deionized water for ultrasonic dispersion, add the dispersion into the centrifuge tube and centrifuge at 3000rpm for 10min. Zn will precipitate at the bottom, and take the upper liquid (containing hydrophobic Ti3C2T x ), the centrifuge speed is 6000 rpm, the centrifugal time is 10 min, the precipitate is filtered, and the solid obtained by filtration is hydrophobic Ti3C2T x , vacuum drying, drying temperature is 40℃.

[0075] The hydrophobic Ti3C2T x Elemental analysis (results see Table 1) and scanning electron microscopy, X-ray diffraction, and contact angle tests (see Figure 1 、 2 , 3).

[0076] Table 1

[0077]

[0078] 8 mL of BMIM TFSI was dissolved in 15 mL of tetrahydrofuran solution, and the hydrophobic Ti3C2T x The mass is 500 mg, and the uniform BMIM TFSI+Ti3C2T x The flow electrode slurry is used as the negative flow electrode, and its density is 1.1g / cm 3 .

[0079] 8 mL of BMIM Ac was dissolved in 15 mL of tetrahydrofuran solution, 500 mg of AC was added, and ultrasonication was performed to form a uniform BMIM Ac + AC flow electrode slurry as the positive flow electrode with a density of 0.9 g / cm 3 .

[0080] Example 2:

[0081] The hydrophobic Ti3C2T x The slurry was mixed with polyvinylidene fluoride in N-methylpyrrolidone at a mass ratio of 9:1 and stirred evenly. The slurry was evenly coated on high-purity graphite paper with a coater, dried in a vacuum oven at 80°C overnight, and then sliced ​​to obtain an electrode.

[0082] Example 3:

[0083] The electrochemical performance of the electrode prepared in Example 2 was tested. The specific method was as follows: the prepared electrode was used as the working electrode, the Ag / AgCl electrode and the platinum electrode were used as the reference electrode and the counter electrode respectively, and BMIM TFSI with a mass fraction of 46% was used as the electrolyte. The electrochemical performance was tested in a three-electrode system (GCD test, i.e., constant current charge-discharge test). The results are shown in Figure 4 .

[0084] The calculation formula of electrode specific capacitance is: ,in Indicates constant current charge and discharge current (A), is the discharge time (s), is the mass of active material on the electrode (g), is the voltage window (V).

[0085] Example 4:

[0086] 4.1 Using Example 1 to prepare the negative electrode mobile electrode as a Na storage + Electrode, positive flow electrode as Cl storage - Electrode, conduct capacitive deionization and desalination performance test. Specifically:

[0087] Close the first push-pull plate 107 and the second push-pull plate 108 of the first FCDI device 11, and use the first pump body 13 to transport the untreated brine in the treatment tank 19 to the middle cavity of the first FCDI device 11. The third pump body 17 transports the BMIM Ac+AC flow electrode slurry in the first slurry tank 21 to the upper cavity of the first FCDI device 11. The fourth pump body 18 transports the BMIM TFSI+Ti3C2T in the second slurry tank 22 to the upper cavity of the first FCDI device 11. x The flow electrode slurry is transported to the lower cavity of the first FCDI device 11 , and after the slurry and the brine to be treated fill the corresponding cavity, the first push-pull plate 107 and the second push-pull plate 108 of the first FCDI device 11 are opened.

[0088] The first power supply 12 is used to provide a voltage (1.6V) to the first FCDI device 11 for desalination (applying an electric field), and the slurry and the brine to be treated are kept in a dynamic flow state. The BMIM Ac+AC flow electrode slurry, the brine to be treated (concentration 1.1 mg / L), TFSI+Ti3C2T x The flow rates of the electrode slurry were 24 mL / min, 22 mL / min, and 20 mL / min, respectively.

[0089] like Figure 6 As shown, the Na in the brine to be treated + Adsorbed by BMIM Ac+AC flow electrode slurry, Cl -BMIM TFSI+Ti3C2T x The electrolyte is adsorbed by the flow electrode slurry, and the desalinated brine returns to the treatment tank 19.

[0090] 4.2 The ion enrichment process in this embodiment uses a constant voltage power supply to provide a reverse voltage to the reactor to enrich the ions. Specifically:

[0091] Close the first push-pull plate 107 and the second push-pull plate 108 of the second FCDI device 14, and transport the deionized water in the enrichment tank 20 to the middle cavity of the second FCDI device 14 through the second pump body 16. Under the pressure of the third pump body 17, the Na adsorbed in the upper cavity of the first FCDI device 11 is + The BMIM Ac+AC flow electrode slurry is transported to the upper cavity of the second FCDI device 14; under the pressure of the fourth pump body 18, the adsorbed Cl in the lower cavity of the first FCDI device 11 - BMIM TFSI+Ti3C2T x The flow electrode slurry is transported to the lower cavity of the second FCDI device 14; after the slurry and deionized water fill the corresponding cavity, the first push-pull plate 107 and the second push-pull plate 108 of the second FCDI device 14 are opened.

[0092] A second power supply 15 supplies a voltage (1.6V) to the second FCDI device 14 for ion enrichment. This ion enrichment is performed in a reverse direction (applying a reverse electric field). The slurry and deionized water maintain a dynamic flow state, with the flow rate within each chamber of the second FCDI device 14 matching that of the first FCDI device 11.

[0093] Adsorbed Na + The BMIM Ac+AC flow electrode slurry is subjected to the electric field, Na + Desorbed into deionized water; adsorbed Cl - BMIM TFSI+Ti3C2T x Under the action of electric field, the electrode slurry - Desorption into deionized water. The ion concentration in the enrichment tank 20 increases.

[0094] In this embodiment, the adsorption process and the desorption process are performed simultaneously. Of course, in some cases, the adsorption process and the desorption process can be performed independently.

[0095] In this embodiment, a conductivity meter is used to monitor the conductivity changes in the treatment tank 19 and the enrichment tank 20 in real time, and the brine concentration is calculated based on the conductivity changes.

[0096] The calculation formula for salt ion removal rate is: ,in and are the initial and final concentrations of NaCl solution (mg / L), respectively.

[0097] The calculation formula for salt ion adsorption rate is: , V is the volume of NaCl solution (L), is the desalting time ( ), is the contact surface area, in this embodiment 25 (0.0025 ).

[0098] Example 5:

[0099] According to Table 1 and Figure 1 It can be seen that the prepared hydrophobic Ti3C2T x The main elements are Ti, C, and Cl. The low Al content is due to the vaporization and separation of AlCl₃ generated during the reaction. The low Zn content indicates a low level of impurities. The structure exhibits a two-dimensional accordion structure, indicating successful etching of the hydrophobic Ti₃AlC₂.

[0100] From the XRD spectrum ( Figure 2 ) can be seen in the prepared hydrophobic Ti3C2T x It has obvious characteristics of MXene (two-dimensional transition metal carbide), in which the 002 peak shifts to the left, indicating that Al is etched and the interlayer spacing is opened to form a layered two-dimensional structure.

[0101] The contact angle was measured ( Figure 3 ), hydrophobic Ti3C2T x The hydrophobicity is good, and the surface functional group -Cl has an anti-wetting effect, which makes the electrode material as a mobile electrode have better stability.

[0102] Example 6:

[0103] like Figure 4 As shown, through the GCD test of the material, it is calculated that the hydrophobic Ti3C2T x The specific capacitance of Ti3C2T is 109F / g, indicating excellent charge storage capacity. x The energy density of Ti3C2T is 139.52Wh / kg, showing that the hydrophobic Ti3C2T x Potential in high energy storage applications. The obvious platform region appears in the charge-discharge curve, indicating the existence of pseudocapacitive behavior in the material. The charge-discharge curve shows good symmetry, indicating that the electrode material has ideal capacitive behavior and low internal resistance.

[0104] Example 7:

[0105] Figure 5 The schematic diagram of the connection between the FCDI device and the power supply is shown. During the feeding process, the first push-pull plate 107 or the second push-pull plate 108 (for specific structure, see Figure 7 ) is closed, and the system is in a disconnected state, ensuring more stable feeding. After feeding is completed, the first push-pull plate 107 or the second push-pull plate 108 is opened (i.e., pulled out), allowing the flow electrode slurry to contact the brine to be treated, forming a path, and voltage is applied to begin desalination.

[0106] like Figure 5 As shown, in this embodiment, the contact surface of the first fluid channel 104 and the second fluid channel 105 is a plane, and the contact surface (reaction area) is 5 5 .

[0107] Through the desalination test of 1.1g / L brine to be treated, Figure 9 The salt in the brine to be treated is almost desorbed in 30 minutes. The salt ion removal rate of this desalination method can be obtained by calculation. As high as 86.7%, salt ion adsorption rate 2.4 This shows that the present invention has good desalination ability and broad application prospects.

[0108] After the enrichment of ions, BMIM TFSI+Ti3C2T were separated by 0.2μm nylon membrane. x Electrode materials in flow electrode slurry, BMIM Ac+AC flow electrode slurry (hydrophobic Ti3C2T x , AC) and ionic liquids (BMIM TFSI, BMIM Ac), washed with tetrahydrofuran, and the obtained electrode materials can be washed with a large amount of deionized water and dried and recovered under a vacuum environment at 40°C.

[0109] The results showed that hydrophobic Ti3C2T x The recovery rate for BMIM TFSI and BMIM Ac reached 80.6%, and the recovery rate for AC was 82.4%, with low losses. Ionic liquids (BMIM TFSI and BMIM Ac) can be recovered and separated from tetrahydrofuran by rotary evaporation. Due to the high stability of the ionic liquids, the recovery rates for BMIM TFSI and BMIM Ac were 85.8%, and 83.2%, respectively. This demonstrates that the flow electrode slurry provided in this embodiment not only has excellent saltwater treatment capabilities but also exhibits stable properties and good recovery rates. This significantly reduces process costs and achieves better economic benefits.

[0110] The above description is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be included in the scope of protection of the claims.

Claims

1. Hydrophobic Ti3C2T x As a mobile electrode in capacitive deionized water treatment, it is characterized by: In the capacitive deionized water treatment, hydrophobic Ti3C2T x The prepared flow electrode slurry is used as the negative flow electrode, and the flow electrode slurry prepared by BMIM Ac is used as the positive flow electrode, which are placed in a reactor. The negative flow electrode and the positive flow electrode are respectively located at opposite positions in the reactor, with water to be treated between the negative flow electrode and the positive flow electrode. The negative flow electrode and the positive flow electrode are respectively in direct contact with the water to be treated, and an electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion adsorption; The hydrophobic Ti3C2T x The preparation method comprises the following steps: S1. Under inert gas protection, Ti3AlC2 powder and ZnCl2 powder are uniformly mixed and then heat treated under inert gas protection; S2. After the heat treatment reaction is completed, the residual ZnCl2 is removed by washing with deionized water; Ti3C2T is obtained by filtration. x and Zn mixture; ultrasonic dispersion in deionized water, centrifuge separation, and vacuum drying to obtain hydrophobic Ti3C2T x .

2. The application according to claim 1, characterized in that In step S1, the mass ratio of the Ti3AlC2 powder to the ZnCl2 powder is 1:6; the heat treatment temperature is 550°C and the time is 5 hours.

3. The application according to claim 1 or 2, wherein the capacitive deionized water treatment is a membrane-less treatment.

4. The use according to claim 1 or 2, characterized in that: The preparation method of the negative electrode mobile electrode is as follows: dissolving BMIMTFSI in tetrahydrofuran solution, adding hydrophobic Ti3C2T x After thorough mixing, the obtained slurry is BMIM TFSI+Ti3C2T x Flow electrode slurry; the preparation method of the positive flow electrode is: dissolving BMIM Ac in tetrahydrofuran solution, adding AC and mixing thoroughly, and the obtained slurry is BMIM Ac+AC flow electrode slurry.

5. The use according to claim 1 or 2, characterized in that: According to the density difference, one of the negative electrode mobile electrode and the positive electrode mobile electrode floats on the upper layer of the water to be treated, and the other mobile electrode sinks to the lower layer of the water to be treated.

6. The use according to claim 1 or 2, characterized in that: After the capacitive deionized water treatment is completed, a reverse electric field is applied between the negative flow electrode and the positive flow electrode to achieve ion desorption and ion enrichment.

7. The use according to claim 1 or 2, characterized in that: The reactor includes at least one FCDI device for adsorption and / or at least one FCDI device for desorption; each FCDI device includes an FCDI component and a power supply, each FCDI device has a cavity inside, and the cavity is divided into an upper cavity, a middle cavity and a lower cavity by a first partition and a second partition. The first partition has a first fluid channel connecting the upper cavity and the middle cavity, and the second partition has a second fluid channel connecting the middle cavity and the lower cavity. The two ends of the power supply are electrically connected to the interior of the upper cavity and the lower cavity respectively.

8. The application according to claim 7, characterized in that: When the reactor includes at least one FCDI device for adsorption and at least one FCDI device for desorption; the FCDI device for adsorption includes a first FCDI device, a first power supply, a first pump body, a third pump body, a first slurry tank and a treatment tank, and the FCDI device for desorption includes a second FCDI device, a second power supply, a second pump body, a fourth pump body, a second slurry tank and an enrichment tank; The liquid inlet pipe and the liquid outlet pipe of the first pump body are respectively connected to the processing tank and the liquid inlet of the middle cavity of the first FCDI device, and the liquid outlet of the middle cavity of the first FCDI device is connected to the processing tank; The liquid inlet pipe and the liquid outlet pipe of the second pump body are respectively connected to the liquid inlet of the enrichment tank and the middle cavity of the second FCDI device, and the liquid outlet of the middle cavity of the second FCDI device is connected to the enrichment tank; The liquid inlet pipe and liquid outlet pipe of the third pump body are respectively connected to the first slurry pool and the liquid inlet of the upper cavity of the first FCDI device, and the upper cavity of the second FCDI device is connected to the first slurry pool; the liquid inlet pipe and liquid outlet pipe of the fourth pump body are respectively connected to the second slurry pool and the liquid inlet of the lower cavity of the first FCDI device, and the lower cavity of the second FCDI device is connected to the second slurry pool; and the upper cavity of the first FCDI device and the upper cavity of the second FCDI device are connected by a pipe, and the upper cavity of the first FCDI device and the lower cavity of the second FCDI device are connected by a pipe.

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