Titanium dioxide mixed carbon capacitive deionization electrode, preparation method thereof and capacitive deionization device

Abstract

This invention provides a capacitive deionization electrode composed of titanium dioxide and carbon, its preparation method, and a capacitive deionization device. The electrode includes a current collector and an active material layer, wherein the active material layer comprises activated carbon, titanium dioxide, a conductive agent, and a binder, and the mass ratio of activated carbon to titanium dioxide is (5~1):1. Devices prepared using the electrode of this application can effectively remove heavy metal ions from water while retaining beneficial ions needed by the human body, meeting the needs of household water purification.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a titanium dioxide mixed with carbon capacitive deionization electrode, its preparation method, and a capacitive deionization device. Background Technology

[0002] In household water use, the mainstream solutions for filtering out charged ions in water currently include ultrafiltration, nanofiltration, and reverse osmosis. Among them, reverse osmosis technology has become the market choice due to its excellent filtration effect (99%). However, this also brings a problem: with people's increasing awareness of drinking water and their focus on health, reverse osmosis water is too pure and does not retain beneficial mineral ions. Therefore, capacitive deionization technology, which retains ions, is receiving increasing research attention in water purification scenarios. Capacitive deionization technology can achieve different water qualities under different voltages, while retaining beneficial ions and removing heavy metal ions. However, conventional electrodes are less effective at removing heavy metals and cannot meet the actual needs of household water purification. Summary of the Invention

[0003] This invention aims to at least partially solve one of the technical problems in the prior art. Therefore, one object of this invention is to provide a titanium dioxide mixed with carbon capacitive deionization electrode, its preparation method, and a capacitive deionization device.

[0004] In a first aspect, the present invention provides a capacitive deionization electrode composed of titanium dioxide and carbon. According to an embodiment of the invention, the electrode comprises a current collector and an active material layer, the active material layer comprising activated carbon, titanium dioxide, a conductive agent, and a binder, wherein the mass ratio of activated carbon to titanium dioxide is (5~1):1.

[0005] The capacitive deionization electrode of titanium dioxide mixed with carbon according to the above embodiments of the present invention includes a current collector and an active material layer. The active material layer includes activated carbon, titanium dioxide, a conductive agent, and a binder. Activated carbon has excellent adsorption properties and can adsorb ions in solution. The surface of titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.), which can undergo complexation reactions with heavy metal ions, thereby removing heavy metals from water through surface complexation. Specifically, in activated carbon, heavy metal removal is mainly achieved through pore size adsorption, while the surface of titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.) that can undergo complexation reactions with heavy metal ions, thereby removing heavy metals from water through surface complexation. The combined effect of complexation and adsorption achieves the removal effect. However, titanium dioxide cannot remove other beneficial ions in water; they can only be removed through the double electric layer of activated carbon and adsorption. Therefore, the retention of beneficial ions can be achieved through the regulation of the electric field. The inventors have found that controlling the mass ratio of activated carbon to titanium dioxide to be (5~1):1 can not only effectively remove heavy metals from water but also retain beneficial ions, achieving the purpose of water purification. Therefore, by adding titanium dioxide to the electrode material and controlling the mass ratio of activated carbon to titanium dioxide within the above-mentioned range, this application can effectively remove heavy metal ions from water while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification.

[0006] In addition, the titanium dioxide mixed carbon capacitive deionization electrode according to the above embodiments of the present invention also has the following technical features:

[0007] In some embodiments of the present invention, the activated carbon has a particle size of 5 μm to 15 μm and a surface area of ​​1500 m². 2 / g~2200m 2 / g, the average pore size of the activated carbon is 1nm~5nm. This improves the adsorption performance of the activated carbon and allows it to work more effectively with titanium dioxide to remove heavy metal ions while retaining a certain amount of beneficial ions.

[0008] In some embodiments of the present invention, the titanium dioxide has a particle size of 0.25 mm to 1.5 mm and a surface area of ​​200 m². 2 / g~240m 2 The titanium dioxide has an average pore size of 6 nm to 9 nm per g. This improves the removal rate of heavy metals from water while retaining beneficial ions needed by the human body.

[0009] In some embodiments of the present invention, the conductive agent accounts for 2% to 5% of the total mass of the active material layer. This improves the conductivity and electron transport capability of the electrode.

[0010] In some embodiments of the present invention, the binder accounts for 5% to 10% of the total mass of the active material layer. This improves the contact performance of the various materials within the active material layer.

[0011] In some embodiments of the present invention, the thickness of the active material layer is 60 μm to 95 μm. This improves the removal rate of heavy metals from water while retaining beneficial ions needed by the human body.

[0012] In some embodiments of the present invention, the active material layer comprises a first active material layer and a second active material layer stacked together. The first active material layer is adjacent to the current collector. The first active material layer comprises activated carbon, a conductive agent, and a binder. The second active material layer comprises activated carbon, titanium dioxide, a conductive agent, and a binder. This improves the removal rate of heavy metals from water by the electrode while retaining beneficial ions needed by the human body.

[0013] In some embodiments of the present invention, the thickness of the first active material layer is 60um to 95um, and the total thickness of the first active material layer and the second active material layer is not greater than 150um.

[0014] In some embodiments of the present invention, the active material layer includes a stacked third active material layer and a fourth active material layer, the third active material layer being adjacent to the current collector, the third active material layer including activated carbon, a conductive agent, and a binder, and the fourth active material layer including activated carbon, a binder, and titanium dioxide.

[0015] In some embodiments of the present invention, the thickness of the third active material layer is 60um to 95um, and the total thickness of the third active material layer and the fourth active material layer is not greater than 150um.

[0016] In some embodiments of the present invention, the active material layer includes a fifth active material layer and a sixth active material layer stacked together, the fifth active material layer being adjacent to the current collector, the fifth active material layer including activated carbon, a conductive agent, and a binder, and the sixth active material layer including a conductive agent, a binder, and titanium dioxide.

[0017] In some embodiments of the present invention, the thickness of the fifth active material layer is 60um to 95um, and the total thickness of the fifth active material layer and the sixth active material layer is not greater than 150um.

[0018] In a second aspect, the present invention provides a method for preparing the above-mentioned titanium dioxide mixed carbon capacitive deionization electrode. According to an embodiment of the present invention, the method includes:

[0019] Activated carbon, titanium dioxide, conductive agent, and binder are mixed in a solvent and applied to at least one side of the current collector. After drying and rolling, a titanium dioxide mixed carbon capacitor deion electrode is obtained.

[0020] Therefore, the above method can be used to prepare electrodes with high heavy metal removal rate and retention of beneficial ions needed by the human body. Moreover, the method is simple, easy to operate, has high electrode production efficiency, and low electrode production cost.

[0021] In a third aspect, the present invention provides a capacitive deionization device. According to an embodiment of the present invention, the capacitive deionization device includes a capacitive deionization electrode of titanium dioxide mixed with carbon. Therefore, the capacitive deionization device can effectively adsorb and remove heavy metals from water, achieving heavy metal purification, while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a capacitive deionization electrode structure of titanium dioxide mixed with carbon according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of a capacitive deionization electrode structure of titanium dioxide mixed with carbon according to another embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] In a first aspect, the present invention provides a capacitive deionization electrode composed of titanium dioxide and carbon. According to an embodiment of the invention, reference is made to... Figure 1 The electrode includes a current collector 100 and an active material layer 200. The active material layer 200 includes activated carbon, titanium dioxide, a conductive agent, and a binder. The mass ratio of activated carbon to titanium dioxide is (5~1):1.

[0027] The capacitive deionization electrode of titanium dioxide mixed with carbon according to the above embodiments of the present invention includes a current collector and an active material layer. The active material layer includes activated carbon, titanium dioxide, a conductive agent, and a binder. Activated carbon has excellent adsorption properties and can adsorb ions in solution. The surface of titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.), which can undergo complexation reactions with heavy metal ions, thereby removing heavy metals from water through surface complexation. Specifically, in activated carbon, the removal of heavy metals is mainly achieved through pore size adsorption, while the surface of titanium dioxide has many functional groups (carboxyl groups, hydroxyl groups, etc.) that can undergo complexation reactions with heavy metal ions, thereby removing heavy metals from water through surface complexation. The combined effect of complexation and adsorption achieves the removal effect. However, titanium dioxide cannot remove other beneficial ions in water; they can only be removed through the double layer of activated carbon and adsorption. Therefore, the retention of beneficial ions can be achieved through the regulation of the electric field. In particular, the inventors have found that controlling the mass ratio of activated carbon to titanium dioxide to be (5~1):1 can effectively remove heavy metals from water while retaining beneficial ions, thus achieving the purpose of water purification. For example, the mass ratio of activated carbon to titanium dioxide can be 5:1, 4.5:1, 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1, etc. Other mass ratios greater than or equal to 1, 1.5, 2, 2.5, etc., and less than or equal to 3, 3.5, 4, 4.5, 5, etc. Therefore, this application, by adding titanium dioxide to the electrode material and controlling the mass ratio of activated carbon to titanium dioxide within the range of (5~1):1, can effectively remove heavy metal ions from water while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification.

[0028] It should be noted that the current collector, conductive agent, and binder are conventional materials in this field, and those skilled in the art can select them according to actual needs. For example, the current collector includes, but is not limited to, copper foil, aluminum foil, stainless steel foil, titanium foil, nickel foil, etc. The conductive agent includes, but is not limited to, acetylene black, conductive carbon black, graphite powder, etc. The binder includes, but is not limited to, polyurethane, polyvinylidene fluoride, polystyrene, polyacrylate, polytetrafluoroethylene, etc.

[0029] According to embodiments of the present invention, heavy metals include, but are not limited to, Pb, As, Fe, Cr, and Cu.

[0030] According to an embodiment of the present invention, the particle size of the activated carbon is 5 μm to 15 μm, and the surface area of ​​the activated carbon is 1500 m². 2 / g~2200m 2 / g, the average pore size of activated carbon is 1nm~5nm. For example, the particle size of activated carbon is 5um, 7um, 9um, 11um, 13um, 15um, etc., and the particle size is greater than or equal to 5um, 7um, 9um, etc., and less than or equal to 11um, 13um, 15um, etc.; for example, the surface area of ​​activated carbon is 1500m².2 / g, 1600m 2 / g, 1700m 2 / g, 1800m 2 / g, 1900m 2 / g, 2000m 2 / g, 2100m 2 / g, 2200m 2 / g, etc., and for example, a surface area greater than or equal to 1500m² 2 / g, 1600m 2 / g, 1700m 2 / g, 1800m 2 / g, etc., less than or equal to 1900m 2 / g, 2000m 2 / g, 2100m 2 / g, 2200m 2 / g, etc.; for example, the average pore size of activated carbon is 1nm, 2nm, 3nm, 4nm, 5nm, etc., and the average pore size is greater than or equal to 1nm, 2nm, etc., and less than or equal to 3nm, 4nm, 5nm, etc. The inventors discovered that controlling the particle size of activated carbon to 5um~15um and the specific surface area to 1500m² is effective. 2 / g~2200m 2 With an average pore size of 1 nm to 5 nm, activated carbon can provide more active sites and has a larger adsorption capacity, thus exhibiting excellent ion adsorption performance and heavy metal removal ability. Furthermore, activated carbon can work synergistically with titanium dioxide to remove heavy metal ions while retaining a certain amount of beneficial ions.

[0031] According to an embodiment of the present invention, the titanium dioxide has a particle size of 0.25 mm to 1.5 mm and a surface area of ​​200 m². 2 / g~240m 2 / g, the average pore size of the titanium dioxide is 6nm~9nm. For example, the particle size of titanium dioxide is 0.25mm, 0.5mm, 0.7mm, 0.9mm, 1.3mm, 1.5mm, etc., and the particle size is greater than or equal to 0.25mm, 0.5mm, 0.7mm, less than or equal to 0.9mm, 1.3mm, 1.5mm, etc.; for example, the surface area of ​​titanium dioxide is 200m². 2 / g, 210m 2 / g, 220m 2 / g, 230m 2 / g, 240m 2 / g, etc., for example, a surface area greater than or equal to 200m² 2 / g, 210m 2 / g, etc., less than or equal to 220m 2 / g, 230m 2 / g, 240m 2 / g, etc.; for example, the average pore size of titanium dioxide is 6nm, 7nm, 8nm, 9nm, etc., and the average pore size is greater than or equal to 6nm, 7nm, etc., and less than or equal to 8nm, 9nm, etc. The inventors discovered that by controlling the particle size of titanium dioxide to be 0.25mm~1.5mm, the surface area is 200m². 2 / g~240m 2 / g, with an average pore size of 6nm~9nm, can provide more active functional groups and has better ion complexing ability, thereby improving the removal rate of heavy metals and better synergistic effect with activated carbon. While removing heavy metals, it retains a certain amount of beneficial ions needed by the human body.

[0032] According to embodiments of the present invention, the conductive agent comprises 2% to 5% of the total mass of the active material layer. For example, the mass percentage can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc., or a mass percentage greater than or equal to 2%, 2.5%, or 3%, etc., and less than or equal to 3.5%, 4%, 4.5%, or 5%, etc. This improves the conductivity and electron transport capability of the electrode.

[0033] According to embodiments of the present invention, the adhesive accounts for 5% to 10% of the total mass of the active material layer. For example, the mass percentage can be 5%, 6%, 7%, 8%, 9%, 10%, etc., or greater than or equal to 5%, 6%, 7%, etc., and less than or equal to 8%, 9%, 10%, etc. This improves the contact performance of the various materials in the active material layer.

[0034] According to embodiments of the present invention, the thickness of the active material layer is 60µm to 95µm. For example, thicknesses of 60µm, 65µm, 70µm, 75µm, 80µm, 85µm, 90µm, and 95µm are possible; further examples include thicknesses greater than or equal to 60µm, 65µm, 70µm, and 75µm, and less than or equal to 80µm, 85µm, 90µm, and 95µm. The inventors have discovered that controlling the thickness of the active material layer within the range of 60µm to 95µm can improve the removal rate of heavy metals from water by the electrode, while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification.

[0035] According to an embodiment of the present invention, reference Figure 2The active material layer 200 includes a first active material layer 210 and a second active material layer 220 stacked together. The first active material layer 210 is adjacent to the current collector 100. The first active material layer 210 includes activated carbon, a conductive agent, and a binder. The second active material layer 220 includes activated carbon, titanium dioxide, a conductive agent, and a binder. The inventors have discovered that, compared to an electrode with a single active material layer, the electrode using the above-mentioned first active material layer 210 and second active material layer 220 allows the outermost second active material layer 220 to capture heavy metal ions, while the inner first active material layer 210 adsorbs and stores the captured ions, synergistically increasing the overall adsorption capacity. Furthermore, due to the protective effect of the second active material layer 220, the activated carbon in the first active material layer 210 is less likely to be oxidized and its pore size to collapse, thus extending the overall electrode lifespan.

[0036] According to an embodiment of the present invention, the thickness of the first active material layer 210 is 60um to 95um, for example, a thickness greater than or equal to 60um, 65um, 70um, 75um, etc., and less than or equal to 80um, 85um, 90um, 95um, etc. The total thickness of the first active material layer 210 and the second active material layer 220 is not greater than 150um.

[0037] According to an embodiment of the present invention, based on the total mass of the active material layer 200, the mass percentage of the conductive agent is 3% to 10%, and the mass percentage of the binder is 5% to 15%. For example, the mass percentage of the conductive agent is greater than or equal to 3%, 4%, 5%, etc., and less than or equal to 6%, 8%, 10%, etc.; the mass percentage of the binder is greater than or equal to 5%, 6%, 7%, etc., and less than or equal to 8%, 10%, 12%, 15%, etc.

[0038] According to an embodiment of the present invention, the active material layer comprises a stacked third active material layer and a fourth active material layer, the third active material layer being adjacent to the current collector, the third active material layer comprising activated carbon, a conductive agent, and a binder, and the fourth active material layer comprising activated carbon, a binder, and titanium dioxide. This improves the removal rate of heavy metals from water by the electrode, while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification.

[0039] According to an embodiment of the present invention, the thickness of the third active material layer is 60um to 95um, and the total thickness of the third active material layer and the fourth active material layer is not greater than 150um. For example, the thickness is greater than or equal to 60um, 65um, 70um, 75um, etc., and less than or equal to 80um, 85um, 90um, 95um, etc.

[0040] According to an embodiment of the present invention, based on the total mass of the third active material layer, the mass percentage of the conductive agent is 3% to 10%, and the mass percentage of the binder is 5% to 15%. For example, the mass percentage of the conductive agent is greater than or equal to 3%, 4%, 5%, etc., and less than or equal to 6%, 8%, 10%, etc.; the mass percentage of the binder is greater than or equal to 5%, 6%, 7%, etc., and less than or equal to 8%, 10%, 12%, 15%, etc.

[0041] According to an embodiment of the present invention, in the fourth active material layer, the mass ratio of activated carbon to titanium dioxide is (5~1):1. For example, the mass ratio is greater than or equal to 1, 1.5, 2, etc., and less than or equal to 2.5, 3, 4, 5, etc.

[0042] According to an embodiment of the present invention, the mass percentage of the adhesive is 10% to 15% based on the total mass of the fourth active material layer. For example, the mass percentage is greater than or equal to 10%, 11%, 12%, etc., and less than or equal to 13%, 14%, 15%, etc.

[0043] According to an embodiment of the present invention, the active material layer comprises a fifth active material layer and a sixth active material layer stacked together. The fifth active material layer is adjacent to the current collector. The fifth active material layer comprises activated carbon, a conductive agent, and a binder. The sixth active material layer comprises a conductive agent, a binder, and titanium dioxide. This improves the removal rate of heavy metals from water by the electrode while retaining beneficial ions needed by the human body, thus meeting the needs of household water purification.

[0044] According to an embodiment of the present invention, the thickness of the fifth active material layer is 60um to 95um, and the total thickness of the fifth active material layer and the sixth active material layer is not greater than 150um. For example, the thickness is greater than or equal to 60um, 65um, 70um, 75um, etc., and less than or equal to 80um, 85um, 90um, 95um, etc.

[0045] According to an embodiment of the present invention, in the sixth active material layer, the mass ratio of the conductive agent to titanium dioxide is 1:(1~20). For example, the mass ratio is greater than or equal to 1:20, 1:15, 1:10, etc., and less than or equal to 1:1, 1:2, 1:5, 1:8, etc.

[0046] According to an embodiment of the present invention, the mass percentage of the adhesive is 10% to 15% based on the total mass of the sixth active material layer. For example, the mass percentage is greater than or equal to 10%, 11%, 12%, etc., and less than or equal to 13%, 14%, 15%, etc.

[0047] In a second aspect, the present invention provides a method for preparing the above-mentioned titanium dioxide mixed carbon capacitive deionization electrode. According to an embodiment of the present invention, the method includes:

[0048] Activated carbon, titanium dioxide, conductive agent, and binder are mixed in a solvent and applied to at least one side of the current collector. After drying and rolling, a titanium dioxide mixed carbon capacitor deion electrode is obtained.

[0049] Therefore, the above method can be used to prepare electrodes with high heavy metal removal rates while retaining beneficial ions needed by the human body. Furthermore, the method is simple, easy to operate, has high electrode production efficiency, and low production costs. It should be noted that the characteristics and advantages described above for the capacitive deionization electrode made of titanium dioxide mixed with carbon also apply to this method, and will not be repeated here.

[0050] According to embodiments of the present invention, the solid content of the mixture obtained after mixing activated carbon, titanium dioxide, conductive agent, and binder in a solvent is 25% to 35%. For example, the solid content is greater than or equal to 25%, 27%, 29%, etc., and less than or equal to 30%, 31%, 33%, 35%, etc. It should be noted that the solvent is an unconventional reagent in the art, and those skilled in the art can select it according to actual needs. For example, the solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0051] According to an embodiment of the present invention, the drying temperature is 70℃~90℃, and the drying time is 3h~5h. For example, the drying temperature is greater than or equal to 70℃, 75℃, 80℃, etc., and less than or equal to 85℃, 88℃, 90℃, etc.; the drying time is greater than or equal to 3h, 3.5h, 4h, etc., and less than or equal to 4.5h, 4.8h, 5h, etc.

[0052] According to an embodiment of the present invention, the pressure of the roller pressing is 80T to 100T. For example, the pressure is greater than or equal to 80T, 82T, 85T, 90T, etc., and less than or equal to 92T, 95T, 98T, 100T, etc.

[0053] According to an embodiment of the present invention, another method for preparing the above-mentioned titanium dioxide mixed carbon capacitive deionization electrode includes: mixing activated carbon, a conductive agent, and a binder in a first solvent and applying the mixture to at least one side of a current collector, followed by drying and rolling to obtain a first active material layer; mixing activated carbon, titanium dioxide, a conductive agent, and a binder in a second solvent and applying the mixture to the side of the first active material layer away from the current collector, followed by drying and rolling to obtain the titanium dioxide mixed carbon capacitive deionization electrode. Thus, using the above method, an electrode comprising a first active material layer and a second active material layer can be prepared. This electrode has a high heavy metal removal rate and retains beneficial ions required by the human body. Furthermore, the method is simple and easy to implement.

[0054] According to embodiments of the present invention, the solid content of the mixture of activated carbon, conductive agent, and binder in the first solvent is 25% to 35%. For example, the solid content is greater than or equal to 25%, 26%, 28%, etc., and less than or equal to 29%, 30%, 33%, 35%, etc. It should be noted that the first and second solvents are unconventional reagents in the art, and those skilled in the art can select them according to actual needs. For example, the first solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc., and the second solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, etc.

[0055] According to an embodiment of the present invention, the drying temperature is 70℃~90℃, and the drying time is 3h~5h. For example, the drying temperature is greater than or equal to 70℃, 75℃, 80℃, etc., and less than or equal to 85℃, 88℃, 90℃, etc.; the drying time is greater than or equal to 3h, 3.5h, 4h, etc., and less than or equal to 4.5h, 4.8h, 5h, etc.

[0056] According to an embodiment of the present invention, the rolling pressure used to prepare the first active material layer is 80T~100T. For example, the pressure is greater than or equal to 80T, 82T, 85T, 90T, etc., and less than or equal to 92T, 95T, 98T, 100T, etc.

[0057] According to an embodiment of the present invention, the rolling pressure used to prepare the second active material layer is 55T to 65T. For example, the pressure is greater than or equal to 55T, 56T, 57T, 59T, etc., and less than or equal to 60T, 61T, 63T, 65T, etc.

[0058] According to an embodiment of the present invention, another method for preparing the above-mentioned titanium dioxide mixed carbon capacitive deionization electrode includes: mixing activated carbon, a conductive agent, and a binder in a third solvent and applying the mixture to at least one side of a current collector, followed by drying and rolling to obtain a third active material layer; mixing activated carbon, titanium dioxide, and a binder in a fourth solvent and applying the mixture to the side of the third active material layer away from the current collector, followed by drying and rolling to obtain the titanium dioxide mixed carbon capacitive deionization electrode. The third solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide, and the fourth solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0059] According to an embodiment of the present invention, another method for preparing the above-mentioned titanium dioxide mixed carbon capacitive deionization electrode includes: mixing activated carbon, a conductive agent, and a binder in a fifth solvent and applying the mixture to at least one side of a current collector, followed by drying and rolling to obtain a fifth active material layer; mixing the conductive agent, titanium dioxide, and a binder in a sixth solvent and applying the mixture to the side of the fifth active material layer away from the current collector, followed by drying and rolling to obtain the titanium dioxide mixed carbon capacitive deionization electrode. The fifth solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide, and the sixth solvent includes, but is not limited to, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0060] In a third aspect, the present invention provides a capacitive deionization device. According to an embodiment of the present invention, the capacitive deionization device includes the aforementioned titanium dioxide mixed carbon capacitive deionization electrode. Therefore, the capacitive deionization device can effectively adsorb and remove heavy metals from water, achieving heavy metal purification while retaining beneficial ions needed by the human body. It should be noted that the features and advantages described above for the titanium dioxide mixed carbon capacitive deionization electrode also apply to this capacitive deionization device, and will not be repeated here.

[0061] According to an embodiment of the present invention, the capacitive deionization electrode of titanium dioxide mixed with carbon is used as the anode and / or cathode, and preferably the capacitive deionization electrode of titanium dioxide mixed with carbon is used as the cathode.

[0062] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0063] Example 1

[0064] (1) Preparation of cathode electrode: The corresponding mass of activated carbon: conductive carbon black: binder (polyvinylidene fluoride, the binder used in the examples and comparative examples is polyvinylidene fluoride): titanium dioxide = 70:4:6:20 was weighed and mixed into powder. The activated carbon particle size was 7 μm and the surface area of ​​the activated carbon was 1900 m². 2 / g, the average pore size of activated carbon is 3nm, the particle size of titanium dioxide is 0.5mm, and the surface area of ​​titanium dioxide is 220m². 2 / g, the average pore size of titanium dioxide is 7nm. After mixing, the solid powder is added to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. After stirring with a mixer for 4 hours, a uniform slurry is formed. Then, it is coated onto the current collector using a scraper and dried at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um is formed.

[0065] (2) Preparation of anode electrode: Weigh the corresponding mass of activated carbon: conductive carbon black: binder in the ratio of 88:5:7 and mix the powder. After mixing, add the solid powder to the solvent to form a solution with a solid content of 30%. Stir for 4 hours using a mixer to form a uniform slurry. Then use a scraping device to scrape it onto the current collector. Dry at 80°C for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85μm is formed.

[0066] (3) Preparation of capacitor deionization device: The cathode electrode-spacer-anode electrode-spacer are arranged alternately to prepare a spiral-wound capacitor deionization device.

[0067] Example 2

[0068] The difference between Example 2 and Example 1 is as follows:

[0069] (1) Preparation of cathode electrode: Weigh the corresponding mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:14 and mix the powder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours using a stirrer to form a uniform slurry. Then use a scraper to scrape it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um is formed.

[0070] Example 3

[0071] The difference between Example 3 and Example 1 is as follows:

[0072] (1) Preparation of cathode electrode: Weigh the corresponding mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:35 and mix the powder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours using a stirrer to form a uniform slurry. Then use a scraper to scrape it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um is formed.

[0073] Example 4

[0074] The difference between Example 4 and Example 1 is as follows:

[0075] Preparation of cathode electrode: Weigh the appropriate mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:70 and mix the powders. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours to form a uniform slurry. Then, use a scraper to coat it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85μm is formed.

[0076] Example 5

[0077] The difference between Example 5 and Example 1:

[0078] (1) Preparation of cathode electrode:

[0079] Weigh out the corresponding mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:20. The mass of each powder weighed is the same as in Example 1. First, mix 50wt% of activated carbon, conductive carbon black and binder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours to form a uniform slurry. Then, use a scraping device to scrape it onto the current collector. Dry at 80°C for 4 hours. After rolling with a 90T roller press, a first active material layer with a thickness of 85um is formed on the current collector. Then, the remaining 50wt% of activated carbon, conductive carbon black, binder and titanium dioxide are mixed. After mixing, the solid powder is added to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. After stirring with a mixer for 4 hours, a uniform slurry is formed. Then, it is coated onto the current collector with a scraping device and dried at 80℃ for 4 hours. After rolling with a 60T roller press, a second active material layer with a thickness of 50µm is formed on the first active material layer, thus preparing a double-layer electrode.

[0080] Example 6

[0081] The difference between Example 6 and Example 1:

[0082] (1) Preparation of cathode electrode:

[0083] Weigh out the appropriate mass of activated carbon, conductive carbon black, and binder in a ratio of 88:5:7 and mix them into powder. Add the solid powder to N-methylpyrrolidone solvent to form a 30% solid content mixed solution. Stir for 4 hours to form a uniform slurry, then coat it onto the current collector using a scraper. Dry at 80°C for 4 hours, and then roll it using a 90T roller press to form an 85µm thick first active material layer. Subsequently, weigh out the appropriate mass of conductive carbon black, titanium dioxide, and binder in a ratio of 44:44:12 and mix them. Add the solid powder to N-methylpyrrolidone solvent to form a 30% solid content slurry. Apply the slurry to the previously prepared electrode to form a new coating, dry at 80°C for 4 hours, and then roll it using a 60T roller press to form an electrode with a total coating thickness of 145µm on one side of the current collector.

[0084] Example 7

[0085] The difference between Example 7 and Example 1:

[0086] (1) Preparation of cathode electrode:

[0087] Weigh out the appropriate mass of activated carbon, conductive carbon black, and binder in a ratio of 88:5:7 and mix them into powder. Add the solid powder to N-methylpyrrolidone solvent to form a 30% solid content mixed solution. Stir for 4 hours to form a uniform slurry, then coat it onto the current collector using a scraper. Dry at 80°C for 4 hours, and then roll it using a 90T roller press to form an 85µm thick first active material layer. Subsequently, weigh out the appropriate mass of activated carbon, titanium dioxide, and binder in a ratio of 44:44:12 and mix them. Add the solid powder to N-methylpyrrolidone solvent to form a 30% solid content slurry. Apply the slurry to the previously prepared electrode to form a new coating, dry at 80°C for 4 hours, and then roll it using a 60T roller press to form an electrode with a total coating thickness of 145µm on one side of the current collector.

[0088] Comparative Example 1

[0089] Differences between Comparative Example 1 and Example 1:

[0090] (1) Preparation of cathode electrode:

[0091] Weigh out the appropriate mass of activated carbon, conductive carbon black and binder in a ratio of 88:5:7 and mix them into powder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours to form a uniform slurry. Then, use a scraping device to scrape it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um on one side of the current collector is formed.

[0092] Comparative Example 2

[0093] Differences between Comparative Example 2 and Example 1:

[0094] (1) Preparation of cathode electrode: Weigh the corresponding mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:10 and mix the powder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours using a stirrer to form a uniform slurry. Then use a scraper to scrape it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um is formed.

[0095] Comparative Example 3

[0096] Differences between Comparative Example 3 and Example 1:

[0097] (1) Preparation of cathode electrode: Weigh the corresponding mass according to the mass ratio of activated carbon: conductive carbon black: binder: titanium dioxide = 70:4:6:80 and mix the powder. After mixing, add the solid powder to the solvent N-methylpyrrolidone to form a 30% solid content mixed solution. Stir for 4 hours using a stirrer to form a uniform slurry. Then use a scraper to scrape it onto the current collector. Dry at 80℃ for 4 hours. After rolling with a 90T roller press, an electrode with a coating thickness of 85um is formed.

[0098] The performance of the capacitor deionization devices prepared in Examples 1-7 and Comparative Examples 1-3 was measured using the following methods:

[0099] Heavy metal removal rate (Pb, As, Fe, Cr, Cu): Record the initial heavy metal content T1 and the heavy metal ion content T2 after flowing through the capacitor deionization module. Then the heavy metal removal rate = (1-T2 / T1)*100%.

[0100] Beneficial ion retention rate (Ca, Mg): Record the initial beneficial ion content N1 and the beneficial ion content N2 after flowing through the capacitor deionization module. Then the beneficial ion retention rate = N2 / N1*100%.

[0101] The test results of the capacitor deionization devices prepared in Examples 1-7 and Comparative Examples 1-3 are shown in Table 1.

[0102] Table 1

[0103]

[0104] As can be seen from Table 1, the devices in Examples 1-7 achieved the purification of heavy metals while retaining the beneficial ions needed by the human body. In particular, within the range of activated carbon and titanium dioxide addition, the devices with a double-layer structure of the active material layer are more effective than the single-layer devices.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A capacitive deionization electrode of titanium dioxide mixed carbon, characterized by, The electrode includes a current collector and an active material layer. The active material layer includes activated carbon, titanium dioxide, a conductive agent, and a binder. The mass ratio of activated carbon to titanium dioxide is (2.5~1):

1. The titanium dioxide undergoes a complexation reaction with heavy metal ions, thereby removing heavy metals from the water through surface complexation. The active material layer comprises a first active material layer and a second active material layer stacked together. The first active material layer is adjacent to the current collector. The first active material layer comprises activated carbon, a conductive agent, and a binder. The second active material layer comprises activated carbon, titanium dioxide, a conductive agent, and a binder. The thickness of the first active material layer is 60 μm to 95 μm, and the total thickness of the first active material layer and the second active material layer is not greater than 150 μm. Alternatively, the active material layer comprises a stacked third active material layer and a fourth active material layer, the third active material layer being adjacent to the current collector, the third active material layer comprising activated carbon, a conductive agent, and a binder, and the fourth active material layer comprising activated carbon, a binder, and titanium dioxide; the thickness of the third active material layer is 60 μm to 95 μm, and the total thickness of the third and fourth active material layers is not greater than 150 μm; In the fourth active material layer, the mass ratio of activated carbon to titanium dioxide is (5~1):1; Alternatively, the active material layer comprises a stacked fifth active material layer and a sixth active material layer, the fifth active material layer being adjacent to the current collector, the fifth active material layer comprising activated carbon, a conductive agent, and a binder, and the sixth active material layer comprising a conductive agent, a binder, and titanium dioxide; the thickness of the fifth active material layer is 60μm~95μm, and the total thickness of the fifth and sixth active material layers is not greater than 150μm; In the sixth active material layer, the mass ratio of the conductive agent to titanium dioxide is 1:(1~20).

2. The electrode of claim 1, wherein The activated carbon has a particle size of 5μm to 15μm and a surface area of ​​1500m². 2 / g~2200m 2 / g, wherein the average pore size of the activated carbon is 1nm~5nm.

3. The electrode of claim 1, wherein The titanium dioxide has a particle size of 0.25 mm to 1.5 mm and a surface area of ​​200 m². 2 / g~240m 2 / g, the average pore size of the titanium dioxide is 6nm~9nm.

4. The electrode according to any one of claims 1-3, characterized in that, Based on the total mass of the active material layer, the mass percentage of the conductive agent is 2% to 5%. And / or, based on the total mass of the active material layer, the adhesive accounts for 5% to 10% of the total mass.

5. A capacitor deionization device, characterized in that, The capacitive deionization electrode comprising the titanium dioxide mixed carbon as described in any one of claims 1-4.

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