Ion exchange resin-carbon-based composite material, preparation method, mixed electrode and application thereof

Abstract

The invention relates to the field of water purification, and particularly discloses the field of capacitive deionization water purification. According to the preparation method of the ion exchange resin-carbon-based composite material, porous carbon substrate preparation comprises the following steps: step 1, mixing porous carbon, a conductive agent and an adhesive to obtain slurry 1; step 2, coating a current collector with the slurry 1 to obtain a porous carbon electrode; step 3, compressing the porous carbon electrode to obtain a porous carbon substrate; the preparation method of the conductive ion exchange layer comprises the following steps: step 4, mixing nanocarbon with a solvent to obtain nanocarbon dispersion liquid; step 5, mixing the nanocarbon dispersion liquid, ion exchange resin, a conductive agent and an adhesive to obtain slurry 2; and step 6, coating a porous carbon substrate with the slurry 2 to obtain the composite assembly. The problems that a carbon-based material is insufficient in desalination rate and short in service life, and energy consumption is high and a coating falls off seriously due to poor resin conductivity and water swelling are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water purification, in particular to the field of capacitive deionization water purification. BACKGROUND

[0002] Capacitive deionization (CDI) is a new water treatment technology based on the principle of electric double layer. The cations, anions or charged particles in the solution migrate to the two poles under the action of electric field force and concentration gradient, and are adsorbed on the electrode surface to form an electric double layer, so as to achieve the purpose of desalination or purification. Compared with desalination technologies such as reverse osmosis, nanofiltration, electrodialysis and reverse electrodialysis, capacitive deionization technology has the advantages of low energy consumption, low cost, high efficiency and reusability.

[0003] The core of capacitive deionization technology is the electrode. After applying voltage, the electric double layer formed at the electrode / water interface stores ions electrostatically, and produces fresh water. When the voltage is reversed or removed, the ions are released into the solution, and the electrode is regenerated. The traditional capacitive deionization technology uses porous carbon electrodes, which use porous carbon with high specific surface area for ion adsorption. Compared with Faraday-type materials such as transition metal oxides, transition metal sulfides and polymers, it has the advantages of low price, easy availability, stable performance and no impurities in the effluent, and is a material with broad prospects in the field of water treatment. However, carbon-based materials have the disadvantages of low adsorption capacity and easy oxidation, which leads to problems such as insufficient desalination rate and short service life. SUMMARY

[0004] The present application aims to provide an ion exchange resin-carbon-based composite material, a preparation method, a mixed electrode and its application, in order to solve the problems of insufficient desalination rate and short service life of carbon-based materials, and the problems of poor conductivity of resin, high energy consumption and serious coating peeling caused by water swelling.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a preparation method of an ion exchange resin-carbon-based composite material, comprising porous carbon substrate preparation and conductive ion exchange layer preparation, the porous carbon substrate preparation comprising the following steps: Step 1, mixing porous carbon, conductive agent and adhesive to obtain slurry 1; Step 2, coating the slurry 1 on the current collector, and then drying until the slurry 1 solidifies to obtain a porous carbon electrode; Step 3, compacting the porous carbon electrode to obtain a porous carbon substrate; The conductive ion exchange layer preparation comprises the following steps: Step 4, mixing nano-carbon with a solvent to obtain a nano-carbon dispersion, the solvent comprising one or more of deionized water, N-methyl pyrrolidone (NMP), ethanol, methanol and dimethyl sulfoxide (DMSO); Step 5, mixing the nano-carbon dispersion liquid, ion exchange resin, conductive agent and adhesive to obtain slurry 2; Step 6, coating the slurry 2 on the porous carbon substrate, and then drying until the slurry 2 solidifies to obtain a composite assembly.

[0006] Further, it further comprises step 7, pressing the composite assembly to obtain a composite electrode; It further comprises step 8, repeating steps 4-6 at least once to obtain a multi-layer composite electrode.

[0007] Further, the ion exchange resin of step 5 comprises anion exchange resin and cation exchange resin, the anion exchange resin comprises one or more of D301 macroporous weak base anion exchange resin, Amberlite IRA402 strong base type chloride type anion exchange resin, 201x7DQ chloride type powder anion exchange resin; the cation exchange resin comprises one or more of TapTec SR1L Na cation exchange resin, 732 strong acid styrene cation exchange resin Na type, Amberlite SR1LNa cation exchange resin, 001x8DQ sodium type powder cation exchange resin.

[0008] Further, the thickness of the porous carbon substrate in step 3 is 1-1000 μm.

[0009] The application discloses an ion exchange resin-carbon-based composite material, which comprises a porous carbon substrate and a conductive ion exchange layer, the porous carbon substrate comprises a current collector and a porous carbon layer, raw materials of the porous carbon layer comprise 50-90 parts by weight of porous carbon and 1-50 parts by weight of a conductive agent; the conductive ion exchange layer comprises 10-50 parts by weight of a nano-carbon dispersion liquid and 50-90 parts by weight of an ion exchange resin, and the concentration of nano-carbon in the nano-carbon dispersion liquid is 0.1-15 wt%.

[0010] Further, the porous carbon is one or more of activated carbon and mesoporous carbon.

[0011] Further, the current collector is titanium foil, carbon-coated titanium foil, titanium mesh, stainless steel foil, stainless steel mesh, carbon felt, graphite paper or carbon cloth.

[0012] Further, the conductive agent comprises one or more of SuperP, conductive carbon black, Ketjen black, graphite powder.

[0013] The application discloses an ion exchange resin-carbon-based hybrid electrode, which is prepared from any one of the composite materials and comprises a current collector, a porous carbon layer and a conductive ion exchange layer arranged in sequence, and the number of the conductive ion exchange layer is greater than or equal to 1.

[0014] Further, the hybrid electrode is applied to the field of water purification.

[0015] The beneficial effects of the present scheme are: 1. Although the traditional ion exchange material can exchange and adsorb ions, it needs to be washed with inorganic acid and alkali for reuse, which consumes a large amount of chemical agents and produces a large amount of secondary wastewater, and there is a risk of environmental pollution. Treating the wastewater will increase the cost, especially when it is applied to water purification. If there are acid, alkali or other harmful substances remaining in the ion exchange material, it will undoubtedly pollute the water.

[0016] Therefore, at present, the ion exchange material is usually prepared into an ion exchange membrane, and then the ion exchange membrane is arranged between the electrode and the water flow channel, and the ion exchange membrane is used to improve the desalination efficiency and stability by allowing only the corresponding ions to pass. This application utilizes the ion selective permeation characteristics of the ion exchange membrane. In theory, it does not need to be cleaned and regenerated, but in actual use, the ion exchange membrane is complex to make, has low mechanical strength and is expensive, which greatly limits the above-mentioned application. Secondly, the ion exchange membrane is physically isolated from the electrode, which significantly increases the resistance of the CDI work, thereby reducing the power efficiency.

[0017] In the present scheme, the granular ion exchange material is combined with nanocarbon to form a conductive ion exchange layer. The nanocarbon is interpenetrated and wound between the ion exchange materials. The flexibility and winding of the nanocarbon form a mechanical locking effect on the ion exchange material, which buffers the serious volume expansion of the ion exchange material during water absorption or ion adsorption, and prevents the ion exchange material from peeling off or even peeling off together with the porous carbon layer. Secondly, nanocarbon has excellent electronic conductivity, which makes the ion exchange material also have good conductivity, and solves the problem of slow charge transfer and interface charge accumulation caused by the mismatch of the conductivity of the ion exchange material and the porous carbon layer. The prepared composite material has high adsorption capacity, low resistance and long cycle stability.

[0018] 2. In the present scheme, the capacitance can be obtained by increasing the number of conductive ion exchange layers and using different ion exchange resins to form conductive ion exchange layers. The capacitance has multiple different types of conductive ion exchange layers, and the different conductive ion exchange layers can realize different functions, so that the capacitance can be applied in different fields. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The microstructure diagram of the conductive ion exchange layer prepared for Examples 1-3 and Comparative Example 1 of the present application; Figure 2 The microstructure diagram of the conductive ion exchange layer prepared for Examples 4-6 and Comparative Example 2 of the present application; Figure 3The conductivity test results are for the electrodes prepared in Examples 1-6 and Comparative Examples 1-2 of this invention. Figure 4 The energy dispersive spectra of Examples 1-3 and the SEM image of Comparative Example 1 are shown below. Figure 5 The energy dispersive spectra of Examples 4-6 of the present invention and the SEM images of Comparative Example 2 are shown. Figure 6 Cyclic voltammetry curves of the capacitor deionization devices assembled with electrodes in Examples 1 and 4 and Comparative Examples 1 to 3 of the present invention; Figure 7 The cyclic charge-discharge curves of the capacitor deionization devices corresponding to Embodiments 1 and 4 of the present invention are shown below. Figure 8 The adsorption capacity test results are for Examples 1-6 and Comparative Examples 1-3 of this invention; Figure 9 The cycle life test results are for the capacitor deionization devices corresponding to Embodiment 1 and Comparative Example 3 of the present invention. Figure 10 The thickness change rate curves of the electrodes in comparative examples 4-9 of this invention during operation; Figure 11 This is a schematic diagram of the structure of the ion exchange resin-carbon-based hybrid electrode in an embodiment of the present invention. Detailed Implementation

[0020] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: 1. Current collector; 2. Porous carbon layer; 3. Conductive ion exchange layer. Examples This invention discloses an ion exchange resin-carbon-based composite material, comprising a porous carbon substrate and a conductive ion exchange layer. The porous carbon substrate includes a current collector and a porous carbon layer. The raw materials of the porous carbon layer include 50-90 parts by weight of porous carbon, 1-50 parts by weight of conductive agent, and 1-50 parts by weight of dry binder. The porous carbon is one or more of activated carbon and mesoporous carbon. Specifically, in this embodiment, the activated carbon is any one of YP-50F, YP-80, YEC-8A, and YL-DR90. The current collector is any one of titanium foil, carbon-coated titanium foil, titanium mesh, stainless steel foil, stainless steel mesh, carbon felt, graphite paper, and carbon cloth; the conductive agent includes one or more of SuperP, conductive carbon black, Ketjen black, and graphite powder. The adhesive contains one or more of styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF); in this embodiment, an oil-based adhesive is used, and the ion exchange resin used does not require acid or alkali cleaning. The conductive ion exchange layer comprises 10-50 parts by weight of nano-carbon dispersion and 50-90 parts by weight of ion exchange resin. The concentration of nano-carbon in the nano-carbon dispersion is 0.1-15 wt%, and the nano-carbon is one or more of carbon nanotubes and graphene. This invention also discloses a method for preparing an ion exchange resin-carbon-based composite material, used to prepare the above-mentioned ion exchange resin-carbon-based composite material, including the preparation of a porous carbon substrate and the preparation of a conductive ion exchange layer, wherein the preparation of the porous carbon substrate includes the following steps: Step 1: Mix porous carbon, conductive agent and binder and stir at a speed of 300~6000 rpm for 1~24 hours to obtain slurry 1, which has a solid content of 10%~50%. Step 2: Coat the slurry 1 onto the current collector, and then dry it at 50~200℃ until the slurry 1 solidifies to obtain a porous carbon electrode; Step 3: Roll the porous carbon electrode with a rolling pressure of 10~200 MPa and a rolling temperature of room temperature to 300℃ to obtain a porous carbon substrate, and control the thickness of the porous carbon substrate to 1μm~1000μm. The preparation of the conductive ion exchange layer includes the following steps: Step 4: Mix the nano-carbon with a solvent to obtain a nano-carbon dispersion. The solvent includes one or more of deionized water, N-methylpyrrolidone (NMP), ethanol, methanol, and dimethyl sulfoxide (DMSO). Step 5: Use ion exchange resin with a particle size of 0.1~50μm. When the particle size of the ion exchange resin is greater than 50μm, pretreat the ion exchange resin: dry the ion exchange resin at a temperature of 40~150℃ and ball mill for 0.5~24h at a ball milling speed of 100~600rpm; mix the nano carbon dispersion, ion exchange resin, conductive agent and binder to obtain slurry 2. The ion exchange resins include anion exchange resins and cation exchange resins. In actual implementation, the ion exchange resin of any conductive ion exchange layer is either anion or cation. Specifically, the anion exchange resin includes one or more of the following: D301 macroporous weakly basic anion exchange resin, Amberlite IRA402 strong basic chloride anion exchange resin, and 201×7DQ chloride powder anion exchange resin. The cation exchange resin includes one or more of TapTec SR1L Na cation exchange resin, 732 strong acid styrene cation exchange resin (Na type), Amberlite SR1L Na cation exchange resin, and 001×8DQ sodium type powdered cation exchange resin. Step 6: Coat slurry 2 onto a porous carbon substrate and then dry until slurry 2 solidifies to obtain a composite component; Step 7: Press the composite component to obtain the composite electrode; Step 8: Repeat steps 4-6 at least once to obtain a multilayer composite electrode.

[0021] This invention discloses an ion exchange resin-carbon-based hybrid electrode, prepared using the aforementioned composite material, combined with... Figure 11 The hybrid electrode comprises a current collector 1, a porous carbon layer 2, and a conductive ion exchange layer 3, which are sequentially distributed, wherein the number of conductive ion exchange layers 3 is greater than one. The hybrid electrode prepared by this invention is applied in the field of water purification.

[0022] The difference between this composite electrode and conventional capacitive electroadsorption electrodes lies in its highly conductive and swelling-buffered resin layer. On the one hand, charge can be transferred rapidly, reducing the overall resistance of the electrode, thereby reducing side reactions and energy consumption. On the other hand, the flexible structure formed by its nano-carbon greatly buffers the volume expansion of the resin due to water absorption, thus significantly improving adsorption capacity and service life.

[0023] This invention discloses Examples 1-3, in which the types and amounts of nano-carbon differ, as detailed in the table below:

[0024] The present invention also discloses Comparative Examples 1 to 4, the solutions of which are shown below compared with the embodiments: Comparative Example 1: Based on Example 1, Comparative Example 1 did not use nano-carbon and the ion exchange resin only included cation exchange resin to prepare a porous carbon-cation exchange resin bilayer electrode. Comparative Example 2: Based on Example 1, Comparative Example 2 did not use nano-carbon, and the ion exchange resin only included anion exchange resin, thus preparing a porous carbon-anion exchange resin bilayer electrode. The present invention also discloses Comparative Example 3, wherein Comparative Example 3 uses an existing porous carbon electrode, wherein the type of porous carbon and the thickness of the porous carbon electrode are the same as those of the multilayer composite electrode of Example 1.

[0025] The present invention tested the above-mentioned electrodes, and the test results are shown below: 1. The microstructure of the conductive ion exchange layers prepared in Examples 1-3 and Comparative Example 1 was examined, and combined with... Figure 1 The microstructure of Comparative Example 1 is as follows: Figure 1 a, Examples 1-3 are respectively as follows Figure 1 b~ Figure 1d. It can be seen that in the double-layer electrode prepared by this scheme, the nano-carbon in the conductive ion exchange layer is uniformly dispersed with the ion exchange resin, and it is wrapped between the ion exchange resin particles to form a mechanical locking effect.

[0026] The microstructure of the conductive ion exchange layers prepared in Examples 4-6 and Comparative Example 2 was examined, and combined with... Figure 2 The microstructure of Comparative Example 2 is as follows Figure 2 a. The microstructures of Examples 4-6 are as follows: Figure 2 b~ Figure 2 d. It can be seen that in the bilayer electrode prepared by anion exchange resin, in the conductive ion exchange layer of Examples 4 to 6, the nano carbon is still uniformly dispersed together with the ion exchange resin, and it is wrapped between the ion exchange resin particles.

[0027] 2. The conductivity of the electrodes in Examples 1-6 and Comparative Examples 1-2 was tested, and the results are as follows: Figure 3 It can be seen that the conductive ion exchange layer formed by combining nano-carbon with ion exchange resin effectively increases the conductivity of the electrode.

[0028] 3. The cross-sections of the porous carbon substrate and the conductive ion exchange layer in the electrodes prepared in Examples 1-3 and Comparative Example 1 were analyzed. The energy dispersive spectroscopy spectra of Examples 1-3 and the SEM image of Comparative Example 1 are shown below. Figure 4 The cross-sections of the porous carbon substrate and the conductive ion exchange layer in the electrodes prepared in Examples 4-5 and Comparative Example 2 were analyzed. The energy dispersive spectroscopy (EDS) spectra of Examples 4-6 and the SEM image of Comparative Example 2 are shown below. Figure 5 The porous carbon substrate and the conductive ion exchange layer form a distinct bilayer structure, which allows the functions of each conductive ion exchange layer to be performed separately, without affecting efficiency due to mutual interference.

[0029] 4. The electrodes from Examples 1, 4, and Comparative Examples 1-3 were assembled into a capacitive deionization device using components of the same specifications. The cyclic voltammetry curves of the capacitive deionization device were then measured, and the results are as follows: Figure 6 It was found that the cyclic voltammetry curves of the capacitor deionization devices assembled in Examples 1 and 4 had larger areas, indicating that they had greater adsorption capacity. Simultaneously, the cyclic charge-discharge curves of the capacitor deionization devices corresponding to Examples 1 and 4 were detected, such as... Figure 7 It was found that the adsorption capacity of capacitive deionization devices with different conductive ion exchange layers varied significantly.

[0030] 5. The adsorption capacity of Examples 1-6 and Comparative Examples 1-3 was tested, and the results were as follows: Figure 8 It was found that electrodes made of nano-carbon had a larger adsorption capacity for the corresponding capacitive deionization devices.

[0031] 6. The cycle life of the capacitor deionization devices corresponding to Example 1 and Comparative Example 3 was tested, such as... Figure 9 It can be seen that the cycle life retention rate of Example 1 is significantly improved.

[0032] 7. This invention also discloses Comparative Examples 4-9. Compared with Example 1, the amount of nano-carbon used in Comparative Examples 4 and 5 is 1 part and 15 parts, respectively; compared with Example 2, the amount of nano-carbon used in Comparative Examples 6 and 7 is 1 part and 15 parts, respectively; compared with Example 3, the amount of nano-carbon used in Comparative Examples 8 and 9 is 1 part and 15 parts, respectively. The thickness change rate of the electrodes of Examples 1 and 2, and Comparative Examples 4-9 during operation was tested, and a thickness change comparison graph was obtained, as shown in the figure. Figure 10 It can be seen that graphene is more effective at slowing down vertical expansion.

[0033] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing an ion exchange resin-carbon-based composite material, characterized in that: This includes the preparation of a porous carbon substrate and the preparation of a conductive ion exchange layer. The preparation of the porous carbon substrate includes the following steps: Step 1: Mix porous carbon, conductive agent and binder to obtain slurry 1; Step 2: Coat the slurry 1 onto the current collector, and then dry it until the slurry 1 solidifies to obtain a porous carbon electrode. Step 3: Press the porous carbon electrode to obtain a porous carbon substrate; The preparation of the conductive ion exchange layer includes the following steps: Step 4: Mix the nano-carbon with a solvent to obtain a nano-carbon dispersion. The solvent includes one or more of deionized water, N-methylpyrrolidone (NMP), ethanol, methanol, and dimethyl sulfoxide (DMSO). Step 5: Mix the nano-carbon dispersion, ion exchange resin, conductive agent and binder to obtain slurry 2; Step 6: Coat slurry 2 onto a porous carbon substrate and then dry it until slurry 2 solidifies to obtain a composite component.

2. The method for preparing an ion exchange resin-carbon-based composite material according to claim 1, characterized in that: It also includes step 7, which involves pressing the composite component to obtain the composite electrode; It also includes step 8, repeating steps 4-6 at least once to obtain a multilayer composite electrode.

3. The method for preparing an ion exchange resin-carbon-based composite material according to claim 2, characterized in that: The ion exchange resin in step 5 includes anion exchange resin and cation exchange resin. The anion exchange resin includes one or more of the following: D301 macroporous weakly basic anion exchange resin, Amberlite IRA402 strong basic chloride anion exchange resin, and 201×7DQ chloride powder anion exchange resin. The cation exchange resin includes one or more of the following: TapTec SR1L Na cation exchange resin, 732 strong acid styrene cation exchange resin (Na type), Amberlite SR1L Na cation exchange resin, and 001×8DQ sodium powder cation exchange resin.

4. The method for preparing an ion exchange resin-carbon-based composite material according to claim 3, characterized in that: The thickness of the porous carbon substrate in step 3 is 1 μm to 1000 μm.

5. An ion exchange resin-carbon-based composite material, characterized in that: The material comprises a porous carbon substrate and a conductive ion exchange layer. The porous carbon substrate includes a current collector and a porous carbon layer. The raw materials of the porous carbon layer include 50-90 parts by weight of porous carbon and 1-50 parts by weight of a conductive agent. The conductive ion exchange layer includes 10-50 parts by weight of a nano-carbon dispersion and 50-90 parts by weight of an ion exchange resin. The concentration of nano-carbon in the nano-carbon dispersion is 0.1-15 wt%.

6. The ion exchange resin-carbon-based composite material according to claim 5, characterized in that: Porous carbon is one or more of activated carbon and mesoporous carbon.

7. The ion exchange resin-carbon-based composite material according to claim 6, characterized in that: The current collector can be titanium foil, carbon-coated titanium foil, titanium mesh, stainless steel foil, stainless steel mesh, carbon felt, graphite paper, or carbon cloth.

8. The ion exchange resin-carbon-based composite material according to claim 7, characterized in that: Conductive agents include one or more of SuperP, conductive carbon black, Ketjen black, and graphite powder.

9. An ion exchange resin-carbon-based hybrid electrode, characterized in that: Prepared using any one of the composite materials in claims 5 to 8, comprising a current collector, a porous carbon layer, and a conductive ion exchange layer arranged sequentially, wherein the number of the conductive ion exchange layers is greater than or equal to 1.

10. An application of an ion exchange resin-carbon-based hybrid electrode, characterized in that: The hybrid electrode of claim 9 is applied to the field of water purification.

Images