Fluid-penetrable porous electrode and capacitive deionization device

Abstract

nm. The present disclosure also provides a capacitive deionization device comprising an electrode unit including a fluid-penetrable porous positive electrode and a fluid-penetrable porous negative electrode are spaced apart from each other. The fluid-penetrable porous positive electrode and the fluid-penetrable porous negative electrode each having a hydrophilic side and a hydrophobic side opposite to the hydrophilic side. The hydrophilic side of the fluid-penetrable positive electrode and the hydrophilic side of the fluid-penetrable porous negative electrode set face to face. Each hydrophilic side has a roughness of

Description

Technical Field

[0001] This invention relates to an electrode, and more particularly to a fluid-permeable porous electrode and a capacitive deionization device comprising the fluid-permeable porous electrode. Prior Technology

[0002] In recent years, the world has been increasingly affected by climate change, with frequent droughts and other disasters. This has led to measures such as reduced water supply, water rationing, farmland closures, and business shutdowns to maintain daily life. Currently, due to water scarcity, seawater desalination is considered a solution that is unaffected by natural rainfall, provides a stable water supply, and has a relatively low environmental impact. Most current seawater desalination methods use membrane filtration or distillation, but these methods are not only costly but also energy-intensive. Therefore, effectively removing salts (such as sodium chloride) from the water is a pressing issue that needs to be addressed.

[0003] Chinese mainland patent publication CN113149143 discloses a method for simultaneous desalination and degradation of organic matter based on hierarchical hydrophobic / hydrophilic electrodes. This method includes using a capacitive deionization device to treat a system containing oxidants and saline organic wastewater, obtaining purified fresh water. The capacitive deionization device includes a device body, a cathode disposed on the device body, and an anode disposed on the device body and spaced apart from the cathode. Each of the anode and cathode includes a hydrophilic porous carbon layer formed of hydrophilic porous carbon and a hydrophobic layer formed on the surface of the hydrophilic porous carbon layer. The hydrophobic layer includes at least one of a hydrophobic conductive polymer layer formed of a hydrophobic conductive polymer and a hydrophobically modified metal compound layer.

[0004] Although the capacitive deionization device of the method in this Chinese mainland patent application can simultaneously remove salt from wastewater and degrade organic matter in wastewater, the salt removal rate of the capacitive deionization device is still not good. Summary of the Invention

[0005] Therefore, one object of the present invention is to provide a fluid-permeable porous electrode.

[0006] Therefore, the fluid-permeable porous electrode of the present invention includes a hydrophilic side and a hydrophobic side disposed opposite to the hydrophilic side, the hydrophilic side having a roughness of 3 nm to 4 nm and the hydrophobic side having a roughness of 120 nm to 150 nm.

[0007] Another object of the present invention is to provide a capacitor deionization device.

[0008] Therefore, the capacitive deionization device of the present invention includes an electrode unit. The electrode unit includes a fluid-permeable porous positive electrode and a fluid-permeable porous negative electrode spaced apart from the positive electrode. Each of the fluid-permeable porous positive electrode and the fluid-permeable porous negative electrode has a hydrophilic side and a hydrophobic side disposed opposite to the hydrophilic side. The hydrophilic side of the fluid-permeable porous positive electrode and the hydrophilic side of the fluid-permeable porous negative electrode are arranged face-to-face. Each hydrophilic side has a roughness of 3 nm to 4 nm, and each hydrophobic side has a roughness of 120 nm to 150 nm.

[0009] The advantages of this invention are as follows: When the capacitive deionization device is used to desalinate a liquid containing salts, the design of the hydrophobic and hydrophilic sides, through the principle of unidirectional hygroscopicity, allows the flow direction of the liquid to be effectively guided and controlled unidirectionally from the hydrophobic side towards the hydrophilic side. Simultaneously, the liquid is confined and retained between the hydrophilic sides and diffuses between them, which helps the salts in the liquid to be effectively adsorbed into the electrode unit, thereby removing the salts from the liquid and increasing the desalination rate, thus improving the purification efficiency of the liquid. It is worth noting that the fluid-permeable porous positive electrode and fluid-permeable porous negative electrode of this invention have dual wetting characteristics, allowing the liquid to diffuse from one of the hydrophobic sides to the hydrophilic side and diffuse on the surface of the hydrophilic side, thereby improving the desalination rate. Simple Explanation of the Diagram

[0010] Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a schematic diagram illustrating the capacitor deionization device of the present invention. Implementation

[0011] Referring to Figure 1, the capacitor deionization device of the present invention is used to desalinate a liquid to be treated, which includes salts and water, thereby transforming the liquid to be treated into a purified liquid.

[0012] The liquid to be treated may include, but is not limited to, seawater, tap water, or wastewater. The wastewater may include, but is not limited to, domestic wastewater, industrial wastewater, or agricultural wastewater. In some embodiments, the concentration of the salt in the liquid to be treated is between 60 ppm and 150 ppm. The salt in the liquid to be treated may include, but is not limited to, sodium chloride. In some embodiments, the salt is sodium chloride.

[0013] The present invention relates to a flow-through type capacitive deionization device. Referring to Figure 1, the capacitive deionization device includes an electrode unit 1, an isolation unit 2, a current collector unit 3, and a housing unit 4.

[0014] The electrode unit 1 includes a fluid-permeable porous positive electrode 11 and a fluid-permeable porous negative electrode 12 disposed at a distance from the fluid-permeable porous positive electrode 11.

[0015] The fluid-permeable porous positive electrode 11 has a hydrophobic side 111 and a hydrophilic side 112 opposite to the hydrophobic side 111. The fluid-permeable porous negative electrode 12 has a hydrophilic side 121 and a hydrophobic side 122 opposite to the hydrophilic side 121. The hydrophilic side 112 of the fluid-permeable porous positive electrode 11 and the hydrophilic side 121 of the fluid-permeable porous negative electrode 12 are arranged face to face.

[0016] The fluid can penetrate the roughness of the hydrophilic side 112 of the porous positive electrode 11 with a roughness of 3 nm to 4 nm, and the fluid can penetrate the roughness of the hydrophobic side 111 of the porous positive electrode 11 with a roughness of 120 nm to 150 nm. The fluid can penetrate the roughness of the hydrophilic side 121 of the porous negative electrode 12 with a roughness of 3 nm to 4 nm, and the fluid can penetrate the roughness of the hydrophobic side 122 of the porous negative electrode 12 with a roughness of 120 nm to 150 nm.

[0017] In some embodiments, the fluid-permeable porous positive electrode 11 is formed by treating a hydrophobic side of a hydrophobic porous conductor with a modifier, thereby transforming the hydrophobic side of the hydrophobic porous conductor into the hydrophilic side. The hydrophobic porous conductor includes a porous conductive element and a hydrophobic material dispersed within the porous conductive element. The porous conductive element is, for example, but not limited to, a porous carbon conductive sheet or a porous conductive polymer membrane. The porous carbon conductive sheet is, for example, but not limited to, porous carbon felt or porous activated carbon cloth. The porous conductive polymer membrane is, for example, but not limited to, a porous poly(3,4-ethylenedioxythiophene) membrane. The hydrophobic material can be used alone or in combination, and the hydrophobic material is, for example, but not limited to, metal oxides, reduced graphene oxide, or polydimethylsiloxane (PDMS). The metal oxide is, for example, but not limited to, zinc oxide, aluminum oxide, or zirconium dioxide (ZrO₂). Such modifiers include, but are not limited to, atmospheric plasma, butylene, cellulose, or pectin.

[0018] In some embodiments, the fluid-permeable porous negative electrode 12 is achieved by treating one side of a hydrophobic porous conductor with a modifier, thereby making that side of the hydrophobic porous conductor hydrophilic. The hydrophobic porous conductor includes a porous conductive element and a hydrophobic material dispersed within the porous conductive element. The porous conductive element is, for example, but not limited to, a porous carbon conductive sheet or a porous conductive polymer membrane. The porous carbon conductive sheet is, for example, but not limited to, porous carbon felt or porous activated carbon cloth. The porous conductive polymer membrane is, for example, but not limited to, a porous poly(3,4-ethylenedioxythiophene) membrane. The hydrophobic material can be used alone or in combination, and the hydrophobic material is, for example, but not limited to, metal oxides, reduced graphene oxide, or polydimethylsiloxane (PDMS). The metal oxide is, for example, but not limited to, zinc oxide, aluminum oxide, or zirconium dioxide (ZrO₂). Such modifiers include, but are not limited to, atmospheric plasma, butylene, cellulose, or pectin.

[0019] In some embodiments, the water contact angle through which the fluid can penetrate the hydrophilic side 112 of the porous positive electrode 11 is 0 to 20 degrees. In some embodiments, the water contact angle through which the fluid can penetrate the hydrophobic side 111 of the porous positive electrode 11 is 130 to 140 degrees.

[0020] In some embodiments, the water contact angle through which the fluid can penetrate the hydrophilic side 121 of the porous negative electrode 12 is 0 to 10 degrees. In some embodiments, the water contact angle through which the fluid can penetrate the hydrophobic side 122 of the porous negative electrode 12 is 130 to 140 degrees.

[0021] The fluid-permeable porous negative electrode 12 and the fluid-permeable porous positive electrode 11 may be the same or different.

[0022] The isolation unit 2 includes a separator for separating the fluid-permeable porous positive electrode 11 from the fluid-permeable porous negative electrode 12. Such separators are, for example, separators conventionally used in the battery field, such as cellulose membranes or ion exchange membranes, and will not be described further.

[0023] The current collector unit 3 includes a first current collector 31 disposed on the hydrophobic side 111 of the fluid-permeable porous positive electrode 11 and a second current collector 32 disposed on the hydrophobic side 122 of the fluid-permeable porous negative electrode 12. The first current collector 31 includes a first surface 311 facing the hydrophobic side 111 of the fluid-permeable porous positive electrode 11, a second surface 312 opposite to the first surface 311, and a flow channel 310 formed on the first surface 311 for supplying the fluid to be treated. The flow channel 310 has two through-holes 313 penetrating the first surface 311 and the second surface 312 and located on the diagonal of the first surface 311. The second current collector 32 includes a first surface 321 facing the hydrophobic side 122 of the fluid-permeable porous negative electrode 12, a second surface 322 opposite to the first surface 321, and a flow channel 320 formed on the first surface 321 for supplying the purified fluid. The flow channel 320 has two perforations 323 that penetrate the first surface 321 and the second surface 322 and are located on the diagonal of the first surface 321.

[0024] The housing unit 4 includes a first housing wall 41 and a second housing wall 42. The first housing wall 41 is disposed on the second surface 312 of the first current collector 31 and has a through hole 410 that penetrates the first housing wall 41 and communicates with one of the through holes 313 of the first current collector 31. The second housing wall 42 is disposed on the second surface 322 of the second current collector 32 and has a through hole 420 that penetrates the second housing wall 42 and communicates with one of the through holes 323 of the second current collector 32.

[0025] The liquid to be treated enters through the through-hole 410 of the first shell wall 41 and one of the perforations 313 of the first current collector 31, flows in the flow channel 310 and contacts the hydrophobic side 111 of the fluid-permeable porous positive electrode 11. Then, it flows toward the hydrophilic side 112 of the fluid-permeable porous positive electrode 11, and then sequentially passes through the hydrophilic side 121 and the hydrophobic side 122 of the fluid-permeable porous negative electrode 12, thereby transforming into the purified liquid. Then, the purified liquid flows out through one of the perforations 323 of the second current collector 32 and through the through-hole 420 of the second shell wall 42. It is worth noting that the liquid to be treated can also enter through the through-hole 420 of the second shell wall 42 and one of the perforations 323 of the second current collector 32.

[0026] The present invention will be further described with reference to the following embodiments, but it should be understood that the embodiments are for illustrative purposes only and should not be construed as limiting the implementation of the present invention.

[0027] Example 1

[0028] Using an ultrasonic oscillator, a first mixture containing 150 mg of graphene oxide (prepared using the Hummers method) and 30 mL of sulfuric acid was agitated for 30 minutes to uniformly disperse the graphene oxide in the sulfuric acid, forming a second mixture. Then, 60 mg of zinc oxide (prepared using a hydrothermal method) was mixed with the second mixture to form a third mixture. Next, the third mixture was placed in an electrochemical system comprising a graphite electrode (as the counter electrode), a porous carbon felt (as the working electrode; brand: Shanghai Carbon; model: SHTS; dimensions: 25 mm long, 25 mm wide, and 2 mm thick; water contact angle: 120 degrees), and a silver chloride electrode (as the reference electrode). Then, using cyclic voltammetry, a first cyclic potential is applied to the third mixture, starting from a potential of 1 volt and increasing at a rate of 0.05 V to an end potential of -0.1 volt. The voltage is then returned to the starting potential at a rate of 0.05 V, for a total of 200 cycles. This causes the zinc oxide and graphene oxide to adhere to the interior and surface of the porous carbon felt. Next, a second cyclic potential is applied, starting from a potential of 0 volt and increasing at a rate of 0.05 V to an end potential of -1.6 volt. The voltage is then returned to the starting potential at a rate of 0.05 V, for a total of 10 cycles. This reduces the graphene oxide adhered to the interior and surface of the porous carbon felt to reduced graphene oxide, making the surface of the porous carbon felt hydrophobic, thus forming a hydrophobic porous carbon felt with two oppositely arranged hydrophobic sides. This hydrophobic porous carbon felt comprises porous carbon felt, zinc oxide, and reduced graphene oxide. The water contact angle of the hydrophobic porous carbon felt is 135 degrees on the hydrophobic side.

[0029] Next, the hydrophobic porous carbon felt was placed in a plasma treatment apparatus, and in an environment containing argon gas at a flow rate of 5 slm and helium gas at a flow rate of 5 sccm, one of the hydrophobic sides of the hydrophobic porous carbon felt was subjected to two surface treatments using atmospheric plasma at a voltage of 8000 volts, so that the hydrophobic side was transformed into a hydrophilic side, resulting in a treated carbon felt (i.e., fluid-permeable porous electrode). The water contact angle of the hydrophilic side of the treated carbon felt was 0 degrees, and the hydrophilic side had a roughness of 3.2 nm, while the hydrophobic side had a roughness of 120 nm.

[0030] Comparative Example 1

[0031] Porous carbon felt (brand: Shanghai Carbon; model: SHTS; dimensions: 25 mm long, 25 mm wide, and 2 mm thick). Both opposite sides of this porous carbon felt are hydrophobic, with a water contact angle of 120 degrees.

[0032] Comparative Example 2

[0033] An ultrasonic oscillator was used to agitate a first mixture containing 150 mg of graphene oxide (prepared using the Hummers method) and 30 mL of sulfuric acid for 30 minutes to uniformly disperse the graphene oxide in the sulfuric acid, forming a second mixture. Then, 60 mg of zinc oxide (prepared using a hydrothermal method) was mixed with the second mixture to form a third mixture. Next, the third mixture was placed in an electrochemical system comprising a platinum electrode (as the counter electrode), a porous carbon felt (as the working electrode; brand: Shanghai Carbon; model: SHTS; dimensions: 25 mm long, 25 mm wide, and 2 mm thick; water contact angle: 120 degrees), and a silver chloride electrode (as the reference electrode). Then, using cyclic voltammetry, a first cyclic potential is applied to the third mixture, which is applied from a starting potential of 1 Volt at a rate of 0.05 V to an ending potential of -0.1 Volt, and then returned from the ending potential to the starting potential at a rate of 0.05 V, for a total of 200 cycles, so that the zinc oxide and the graphene oxide are attached to the interior and surface of the porous carbon felt. Next, a second cyclic potential is applied, which is applied from a starting potential of 0 Volt at a rate of 0.05 V to an ending potential of -1.6 Volt, and then returned from the ending potential to the starting potential at a rate of 0.05 V, for a total of 10 cycles, so that the graphene oxide attached to the interior and surface of the porous carbon felt is reduced to reduced graphene oxide, making the surface of the porous carbon felt hydrophobic, forming a hydrophobic porous carbon felt with two oppositely arranged hydrophobic sides. The hydrophobic porous carbon felt component comprises porous carbon felt, zinc oxide, and reduced graphene oxide. The water contact angle of the hydrophobic sides of the hydrophobic porous carbon felt component is 135 degrees, and the hydrophobic sides have a roughness of 120 nm.

[0034] Application Example 1

[0035] A 150-liter solution containing sodium chloride and water is continuously introduced into the capacitive deionization device shown in Figure 1 at a flow rate of 4 mL / min. The sodium chloride concentration in the solution is 60 ppm. The electrode unit includes two spaced-apart treated carbon felt pieces from Example 1 (serving as a fluid-permeable porous positive electrode and a fluid-permeable porous negative electrode, respectively; dimensions: length 25 mm, width 25 mm, thickness 2 mm) and a spacer (material: silicone pad; brand: MISUMI; model: GELS3-100; dimensions: length 100 mm, width 100 mm, thickness 3 mm) located between the treated carbon felt pieces. The hydrophilic sides of the treated carbon felt pieces are arranged face to face.

[0036] The liquid to be treated enters through the hydrophobic side of one of the treated carbon felt pieces and diffuses towards the hydrophilic side of the treated carbon felt pieces. At the same time, a voltage of 1.2 Volt is applied to the capacitor deionization device. Then, the liquid to be treated is continuously allowed to flow and exit through the hydrophobic side of the other of the treated carbon felt pieces, so that sodium chloride is adsorbed by the treated carbon felt pieces and removed from the liquid to be treated, thereby transforming the liquid to be treated into a purified liquid.

[0037] Application Examples 2 to 3

[0038] Application Examples 2 and 3 are largely similar to Application Example 1, except that the sodium chloride concentration is changed, as shown in Table 1.

[0039] Comparative Application Example 1

[0040] Comparative Application Example 1 is largely similar to Application Example 1, except that in Comparative Application Example 1, the treated carbon felt pieces of Application Example 1 are replaced with the porous carbon felt of Comparative Example 1.

[0041] Comparative Application Example 2

[0042] Comparative Application Example 2 is largely similar to Application Example 1, except that in Comparative Application Example 2, the hydrophilic side of one of the treated carbon felt pieces is arranged face to face with the hydrophobic side of the other of the treated carbon felt pieces.

[0043] Comparative Application Example 3

[0044] Comparative Application Example 3 is largely similar to Application Example 1, except that in Comparative Application Example 3, the hydrophobic sides of the treated carbon felt are arranged face to face.

[0045] Evaluation Project

[0046] Sodium chloride adsorption capacity (unit: mg / g, or unit: mg / cm²) and adsorption rate (unit: %) measurement: Several standards with known sodium chloride concentrations were prepared. Then, the conductivity of these standards was measured using a benchtop water quality analyzer (brand: Yellow Springs Instrument; model: Multilab IDS 4010-3w). A coordinate graph showing the relationship between the sodium chloride concentration and conductivity was then plotted, yielding a standard curve formula. Next, the conductivity of the purified solutions from Examples 1 to 3 and Comparative Application Examples 1 to 3 was measured using the benchtop water quality analyzer. The conductivity values ​​were then substituted into the aforementioned standard curve formula to calculate the sodium chloride concentration in the purified solutions. Finally, based on the sodium chloride concentration in the purified solutions and the sodium chloride concentration in the solution awaiting treatment, the sodium chloride adsorption capacity and adsorption rate were calculated. The sodium chloride adsorption capacity (mg / g) is calculated as [sodium chloride concentration in the purified solution (ppm) x volume of the purified solution (L) - sodium chloride concentration in the solution to be treated (ppm) x volume of the solution to be treated (L)] / [weight of the porous positive electrode (g) + weight of the porous negative electrode (g)]. The sodium chloride adsorption capacity (mg / cm²) is calculated as [sodium chloride concentration in the purified solution (ppm) x volume of the purified solution (L) - sodium chloride concentration in the solution to be treated (ppm) x volume of the solution to be treated (L)] / opening area of ​​the isolation unit (cm²). The adsorption rate (%) is calculated as {[sodium chloride concentration in the purified solution (ppm) x volume of the purified solution (L) - sodium chloride concentration in the solution to be treated (ppm) x volume of the solution to be treated (L)] / [sodium chloride concentration in the solution to be treated (ppm) x volume of the solution to be treated (L)]} x 100%.

[0047] Table 1 Fluid can penetrate porous positive electrode Fluid can penetrate porous negative electrode set up Sodium chloride concentration (ppm) in the solution to be treated Sodium chloride adsorption capacity (mg / g) Sodium chloride adsorption capacity (mg / cm²) Adsorption rate (%) Application examples 1 Example 1 Example 1 These hydrophilic sides face to face 60 32.82 0.72 32 2 Example 1 Example 1 100 79.32 1.73 46.2 3 Example 1 Example 1 150 133.74 2.92 51.1 Comparison Application Examples 1 Comparative Example 1 Comparative Example 1 -- 60 6.21 0.12 0.5 2 Example 1 Example 1 Hydrophilic side and hydrophobic side face to face 60 28.02 0.57 25 3 Example 1 Example 1 These hydrophobic sides face 60 31.315 0.68 30

[0048] In summary, when this capacitive deionization device is used to desalinate a liquid containing salts, the design of the hydrophobic and hydrophilic sides, utilizing the principle of unidirectional hygroscopicity, allows the flow direction of the liquid to be effectively guided and controlled unidirectionally from the hydrophobic side towards the hydrophilic side. Simultaneously, the liquid is confined and retained between the hydrophilic sides and diffuses within them, facilitating the effective adsorption of salts in the liquid onto the electrode unit. This allows the salts to detach from the liquid, increasing the desalination rate and thus improving the purification efficiency of the liquid. It is worth noting that the fluid-permeable porous positive electrode and fluid-permeable porous negative electrode of this invention possess dual wetting characteristics, allowing the liquid to diffuse from the hydrophobic side to the hydrophilic side and onto the surface of the hydrophilic side, thereby increasing the desalination rate and effectively achieving the objectives of this invention.

[0049] However, the above description is merely an embodiment of the present invention and should not be construed as limiting the scope of the present invention. Any simple equivalent changes and modifications made in accordance with the scope of the patent application and the contents of the patent specification of the present invention shall still fall within the scope of the patent of the present invention.

[0050] 1: Electrode Unit 11: Fluid can penetrate porous positive electrode 111: Hydrophobic side 112: Hydrophilic side 12: Fluid can penetrate porous negative electrode 121: Hydrophilic side 122: Drainage side 2: Isolation Unit 3: Current collector unit 31: First collector 311: First Surface 312: Second Surface 310: Flow channel 313: Perforation 32: Second collector 321: First Surface 322: Second Surface 320: Flow channel 323: Perforation 4: Shell unit 41: First shell wall 410: Through-hole 42: Second shell wall 420: Through hole

Claims

1. A fluid-permeable porous electrode comprising: a hydrophilic side and a hydrophobic side disposed opposite to the hydrophilic side, the hydrophilic side having a roughness of 3 nm to 4 nm and the hydrophobic side having a roughness of 120 nm to 150 nm.

2. The fluid as described in claim 1 is permeable to the porous electrode, wherein, The water contact angle on the hydrophilic side is 0 to 10 degrees.

3. The fluid as described in claim 2 is permeable to the porous electrode, wherein, The water contact angle on the hydrophobic side is 130 to 140 degrees.

4. The fluid as described in claim 1 is permeable to the porous electrode, wherein, The fluid-permeable porous electrode is formed by treating the hydrophobic side of a hydrophobic porous conductor with a modifier to transform it into the hydrophilic side.

5. The fluid as described in claim 4 is permeable to the porous electrode, wherein, The hydrophobic porous conductor includes a porous conductive element and a hydrophobic material dispersed in the porous conductive element.

6. The fluid as described in claim 5 is permeable to the porous electrode, wherein, The hydrophobic material is selected from metal oxides, reduced graphene oxide, polydimethylsiloxane, or any combination thereof.

7. A capacitive deionization device, comprising: an electrode unit including a fluid-permeable porous positive electrode and a fluid-permeable porous negative electrode spaced apart from the fluid-permeable porous positive electrode, each of the fluid-permeable porous positive electrode and the fluid-permeable porous negative electrode having a hydrophilic side and a hydrophobic side disposed opposite to the hydrophilic side, the hydrophilic side of the fluid-permeable porous positive electrode and the hydrophilic side of the fluid-permeable porous negative electrode being disposed face-to-face, each hydrophilic side having a roughness of 3 nm to 4 nm, and each hydrophobic side having a roughness of 120 nm to 150 nm.

8. The capacitor deionization apparatus as claimed in claim 7, wherein, The water contact angle of the fluid that can penetrate either the hydrophilic side of the porous positive electrode or the hydrophilic side of the porous negative electrode is 0 to 10 degrees.

9. The capacitor deionization apparatus as claimed in claim 7, wherein, The water contact angle of the fluid that can penetrate either the hydrophobic side of the porous positive electrode or the hydrophobic side of the porous negative electrode is 130 to 140 degrees.

10. The capacitor deionization apparatus as claimed in claim 7, wherein, The fluid-permeable porous positive electrode and the fluid-permeable porous negative electrode may be the same or different, and each is formed by treating a hydrophobic side of a hydrophobic porous conductor with a modifier to transform it into a hydrophilic side.

11. The capacitor deionization apparatus as claimed in claim 10, wherein, The hydrophobic porous conductor includes a porous conductive element and a hydrophobic material dispersed in the porous conductive element.

12. The capacitor deionization apparatus as claimed in claim 11, wherein, The hydrophobic material is selected from metal oxides, reduced graphene oxide, polydimethylsiloxane, or any combination thereof.

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