WO2015076438A1

WO2015076438A1 - Cdi electrode using permeable hybrid activated carbon fiber

Info

Publication number: WO2015076438A1
Application number: PCT/KR2013/010684
Authority: WO
Inventors: 김창수
Original assignee: (주)청연
Priority date: 2013-11-21
Filing date: 2013-11-22
Publication date: 2015-05-28
Also published as: KR20150059202A

Abstract

The present invention increases an effective adsorption area by the activation of carbon fiber in order to improve ion adsorption/desorption efficiency, is configured as a hybrid electrode by doping the surface of the electrode in order to improve adsorptivity and easily remove polyvalent ions, and prevents adsorptivity deterioration due to a voltage drop in the electrode by reducing volume resistivity in each part of the electrode. The present invention relates to the manufacture of a CDI hybrid activated carbon fiber electrode module configured such that residual static electricity is minimized by increasing electrostatic force of the electrode through mechanical compression of electrode spacing in order to reduce ion adsorption/desorption reaction time and then widening the electrode spacing through relaxing during ion desorption, and all components of the electrode module have permeability and thus many ions in water come into contact with the electrode within a short time.

Description

Electrode for CDI using permeable hybrid activated carbon fiber

The present invention relates to a CDI electrode using a coated permeable hybrid activated carbon fiber according to the electrode polarity, to uniformly compress the electrode during the adsorption of water ions to narrow the distance between the electrodes to increase the capacitance of the electrode and remove Graphite with high elastic fiber woven cover that promotes deionization by widening electrode spacing and permeable pores to prevent short circuit between electrodes and reduce volume resistance of electrodes Foil, coated activated carbon fiber electrode and spacers for insulation between electrodes are stacked in parallel and adsorbed on the surface of activated carbon fiber by electrostatic force generated by supplying external DC power to this electrode, After removing the adsorption force by static electricity by short circuit, supply backwash water to discharge the high concentration of ions released to the outside It relates to electrodes for CDI using the pitcher castle-coated permeability hybrid (Hybrid) activated carbon fibers for group.

In general, all water, including seawater, contains water-insoluble suspensions and water-soluble ions. Due to the asymmetric molecular structure of the water molecules, the material does not have free polarity in the presence of water, but in the presence of ions in the water. According to the polarity of ions, the water molecules are arranged in a radial arrangement around the ions and have a polarity, which is called a hydration ion. The electrodes also have polarity, so they are surrounded by water molecules to form a polarized, hydratable interface whereby cations adsorb to the cathode of the external electrode and anions to the anode of the external electrode. The water-insoluble fine suspension material also has a negative electrode and is adsorbed to the positive electrode of the external electrode.

Conventional osmotic membrane or nano membrane is used to remove water ion.

The removal method is mainly used, but it is a method of filtration with fixed filter pores smaller than the size of ions. Therefore, the permeability is low and it is operated at high pressure, which consumes a large amount of power and consumes pores due to micropores under high pressure. And there is a drawback of the long life of the foreign matter (Plugging) occurs because of this.

In addition, to overcome the above disadvantages, CDI was developed with nanoporous (Micro-Pore) foamed carbon (Carbon Aerogel) as the electrode material, but the effective adsorption part of ions is limited to the surface area of the electrode, so the mm unit electrode The effective adsorption area is much lower than the total pore area, and the closed pores inside the electrode are very large compared to the thickness of the electrode, so that the volume resistance is increased, so that the potential supplied to the electrode is lowered, and the amount of adsorption of ions decreases accordingly. .

In addition, the specific surface area due to the closed pores inside the electrode is 1/3 lower than that of the activated carbon fiber, resulting in an increase in the specific surface area (BET) per electrode weight but decreasing the BET per unit volume of the electrode.

In addition, the opening porosity of the electrode surface is small, so that the adsorbed ions are difficult to escape from the electrode during the deionization process, and since the electrode itself is an impermeable electrode, the raw water to be treated should be diffused and flowed between the small electrode intervals. As the depletion layer is generated to generate a site that depends on ion diffusion, the regeneration time for adsorption and deionization is prolonged, and the overall ion removal efficiency is reduced. Therefore, CDI using the carbon aerogel as an electrode is only at the pilot plant level.

The present invention is applied to the laminated electrode portion of the electrode module by narrowing the interval of the electrode when adsorbed to increase the electrostatic force and relaxes during deionization (regeneration) to reduce the residual electrostatic force and high flow rate (High Flow Rate) In order to reduce the volume resistance of the electrode and to prevent short circuit between the electrodes, which may occur due to uneven electrode surface state due to the characteristics of the high permeability and high elasticity of the textile fabric to ensure the washing water, the electrode compression part, and the activated carbon fiber electrode Permeable permeable doped with SiO2 on the anode and Al₂O₃ on the cathode to increase Zeta-Potential of the electrode for stable adsorption of ions and to remove polyions such as calcium and magnesium. The adsorption pores of activated carbon fiber yarns are concentrated on the surface of the fiber yarns, so the distribution of large meso-pore is large. Due to the extremely small distribution of closed pores in the quasi-inner, activated carbon fiber electrode having a low specific volume resistance and a low potential drop of the electrode, and a fast ion adsorption / desorption cycle, and an insulator composed of woven fibers for insulating each electrode. By alternately stacking them in parallel, the electrolysis voltage of water (power of 3.5V or less is supplied to each electrode to adsorb underwater ions due to electrostatic force generated between the electrodes, and then the power supply is cut off or short-circuited to reverse the water supply. It is to provide an electrode for CDI using a permeable hybrid activated carbon fiber to increase the total amount of water ions removed by the quick discharge / desorption cycle by discharging.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above.

Electrode for CDI using the water-permeable hybrid activated carbon fiber of the present invention for achieving the above object, 290 ~ 310 ℃ by phosphate impregnated Rayon-based fabric woven with insulation for insulating between the anode and cathode After carbonization at a relatively low temperature, the + 'electrode is impregnated with SiO₂ solution, and the'-'electrode with Al₂O ₃ solution, depending on the polarity of the electrode to be used. By injecting steam into the kiln at a temperature of can be produced a hybrid (Hybrid) activated carbon fiber. Both sides of the hybrid activated carbon fiber are covered by two sheets of flexible graphite foil having a plurality of pores to constitute a unit electrode part, and are arranged in a lengthwise direction on one side of the insulator part, but the types of negative and positive electrodes Arranged to be inclined in the opposite direction according to the alternately stacked according to the cathode and anode. Coupling of the unit electrode part and the insulating part is fixed to the insulating part by the electrode coupling pin penetrating the electrode on one side and by epoxy bonding on the other.

The unit electrode part of the stacked top electrode layer is exposed to the flexible graphite foil, and thus, it is covered with an insulating part and then covered with a high permeability and a highly elastic fiber fabric cover thereon to form an electrode module in which a plurality of unit electrodes are stacked. Will be constructed.

Electrodes of the same polarity among the stacked electrode modules are electrically connected in parallel by electrode coupling pins in a state in which they are stacked in parallel in the same direction and are connected to an external DC power source. Mechanical coupling of the electrode module is coupled by the electrode module fixing portion by a fixing pin penetrating the insulation and the fiber fabric cover, the electrode is excluded.

The electrode module fixing part is fixed to the wall surface of the CDI body and the electrode module is in contact with one surface of the filtration unit having a plurality of bends on the surface, and pressing the electrode portion of the electrode module according to the curved surface of the filtration unit and the filtration unit; The electrode compression unit may be in close contact with the electrode module while mechanically compressing the electrodes of the electrode module to reduce the distance between the electrodes.

As described above, the present invention improves the stable ion adsorption power of the electrode by increasing the Zeta Potential by doping the electrode, and can remove polyvalent ions such as Ca / Mg, which are difficult to remove ions, which is applicable to the removal of ions from groundwater. ,

The unit electrode part, which consists of activated carbon and flexible flexible graphite foil, has a total effective surface area of the ion adsorption pores less than carbon aerogels, so the amount of ions adsorbed per unit electrode weight (u-mol / g) is 1/3 or higher. This is three times larger than this, so it cancels out based on the volume of the electrode,

On the other hand, due to the small internal porosity, the lower the volume resistance, the lower the voltage drop at the electrode,

Since there are many meso pores that are advantageous for ion adsorption / desorption, the movement of ions is free and the electrode interval is mechanically adjusted, which increases electrostatic capacity during adsorption and decreases residual capacity during regeneration.

Because of the permeability of the electrode module, there is no ion depletion layer, so there is no need to wait for ion diffusion, so it is evenly adsorbed on the entire electrode surface area, which improves the utilization efficiency of the electrode surface area and enables rapid regeneration

Due to the above characteristics, a short adsorption / desorption cycle is performed to improve the overall ion removal efficiency. This means less power consumption.

It can replace the Membrane as a precision filter for sewage wastewater treatment of 1,000ppm unit from the desalination of seawater with a high concentration of 30,000ppm or more, and it will be positioned as the best technology according to the optimal technology or future research or material development. Could be

1 is a view showing a unit electrode using a hybrid activated carbon fiber according to an embodiment of the present invention.

2 is a view showing a CDI electrode using a water-permeable hybrid activated carbon fiber according to an embodiment of the present invention in the shape.

Figure 3 is a Zeta Potential diagram according to the Doping material of the activated carbon electrode according to the present invention.

Figure 4 is a functional diagram of the adsorption pores of activated carbon according to the present invention.

5 is a process chart for manufacturing a hybrid activated carbon electrode according to the present invention

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention. Like elements in the figures are denoted by the same reference numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is a view showing a unit electrode using a hybrid activated carbon fiber according to an embodiment of the present invention, each of two sheets of porous stretchable carbon film around the hybrid activated carbon fiber electrode 2 (Flexible graphite) cover the both sides of the electrode with foil (1) to form the unit electrode part, and arrange it in the longitudinal direction on one side of the insulating part 3, but arrange it so that the bias direction depends on the type of negative and positive electrode Laminate alternately. Coupling of the unit electrode portion and the insulating portion is fixed to the insulating portion by the electrode coupling pins penetrating the electrode on one side and by the epoxy on the other side.

2 is a view showing a CDI electrode using a water-permeable hybrid activated carbon fiber according to an embodiment of the present invention in the shape. The unit electrode part of the top layer of the stacked electrode bundles is exposed to the flexible graphite foil 2 so that it is covered with the insulating part 3 again and then covered with the high permeability and high elastic fiber fabric cover 11 thereon. The unit electrodes of are stacked.

Electrodes of the same polarity among the stacked electrode modules are electrically connected in parallel by electrode coupling pins 15 in a state in which they are stacked in parallel in the same direction and are connected to an external DC power source. The mechanical coupling of the electrode module is coupled by the electrode module fixing part 13 by the fixing pin 18 penetrating through the insulation and the fiber fabric cover, the electrode is excluded. That is, the stacked electrodes are stacked in the insulator 3, the positive electrode, the insulator 3, and the negative electrode in the order of being stacked, and the unit electrodes are oriented in one of the longitudinal directions on the insulator, so that both ends of the stacked electrodes are stacked. Since the silver is biased along one side of the electrode, penetrating both ends of the electrode through the metallic electrode coupling pin 15 causes the same electrodes to be electrically coupled in parallel.

The electrode module fixing part 13 is fixed to the wall surface of the CDI body and the electrode module is in contact with one surface of the filtering part 16 having a plurality of bends formed on the surface thereof, and according to the curved surface of the filtering part of the electrode module. Pressing an electrode portion to be in close contact with the filtration unit 16 and the electrode module 14, and the electrode compression unit 10 that can reduce the distance of the electrode by mechanically pressing the electrodes of the electrode module.

Figure 3 is a diagram showing the Zeta Potential according to the Doping material of the activated carbon electrode according to an embodiment of the present invention.

4 is a diagram showing the function of the adsorption pore size of the activated carbon of the present invention,

Table 1 below summarizes the functions of the pores by size based on FIG. 4, and it is advantageous that the specific surface area (BET) distribution of Meso-Pore is large for removing water ions.

Table 1

Type of pore	size ()	function	Remarks
Micro-pore	2-4	Manure	Provide high capacitance for ion adsorption but increase specific volume resistance
	6	Start gas adsorption
	10	Liquid ion adsorption
	20	Charge depletion layer	Overlap of electric double layer
Meso-pore	20-500	Adsorption of Hydration Ions	Hydration Ion 7-8
Macro-pore	500		Rise in specific volume resistance

FIG. 5 is a diagram illustrating a process of manufacturing a hybrid activated carbon fiber electrode, and the hybrid activated carbon fiber electrode 1 is 290-310 ° C. after impregnating a rayon-based fabric fabric with phosphate. Carbonize the hybrid activated carbon fiber electrode at a temperature of, and impregnate the carbonized fabric fabric with SiO ₃ solution and '-' electrode with AlO ₃ solution according to the polarity of the electrode. It is produced by active firing by injecting steam into the kiln at a temperature of 850 ~ 950 ℃.

The electrode module 14 of the present invention configured as described above is fixed in plural according to the capacity to be treated on the wall of the CID main body, and the electrode module is compressed through the electrode compression unit 10 to narrow the gap between the electrodes to increase the capacitance of the electrode. After supplying the raw water to remove the ions to the CID main body and then applying DC power to the electrode coupling pin 15 of the gig electrode module, the ions are adsorbed by the electrostatic force on the electrode surface and the electric conductivity in the water starts to fall. If the decrease in the electrical conductivity after this time is stagnant, the power supply is cut off or the electrode is shorted and then the compression unit 10 is relaxed to reduce the residual capacity of the electrode while adsorbing backwash water through the filter unit 16. It is fed in the opposite direction of the flow so that the released ions are discharged to the outside. Once the initial conductivity of the adsorption is equal to the electrical conductivity of the raw water back to the adsorption process is repeated.

The present invention configured as described above allows the adsorption / desorption of ions like the non-water permeable electrode to reduce residual static electricity by widening the electrode intervals without depending on ion diffusion, while simultaneously flowing the raw water and the backwash water directly to the electrode. By reducing the desorption time there is an advantage that can dramatically increase the amount of ion removal per hour. The material can be finely filtered, and when backwashing, there is an advantage that the filtered foreign matter can be easily released without being attached to the filter cloth.

In addition, this permeable hybrid activated carbon electrode is used to determine the current consumption in proportion to the electrical conductivity of raw water and is supplied at a low pressure of 3.5V or less. Therefore, it is possible to precisely filter wastewater including seawater desalination with lower power consumption than Membrane. It has the advantage of wide application range, and the adsorption pores of Meso-pore with large openings are concentrated on the surface of the electrode, so the amount of ions accumulated and remaining in the pores of the electrode is very small, so the adsorption / desorption reaction is fast and due to the doped catalyst material In addition to chemical treatment, since it can easily remove multivalent Ca / Mg ions that are not easy to remove, there is an advantage that it can be applied to groundwater and mine wastewater.

The electrode for CDI using such a permeable hybrid activated carbon fiber is not limited to the configuration and operation of the embodiments described above. The above embodiments may be configured such that various modifications may be made by selectively combining all or part of the embodiments.

[Description of the code]

1: Flexible graphite foil

2: hybrid activated carbon fiber electrode

3: insulation of woven fiber

1-1: Flexible graphite foil of opposite polarity

2-1: Hybrid activated carbon fiber electrode of opposite polarity

3-1: Insulation of woven fiber of opposite polarity

10: electrode compression unit

11: cover

12: unit electrode part (Hybrid activated carbon fiber electrode + flexible graphite foil)

13: electrode module fixing part

14: electrode module

15: electrode coupling pin

16: filtration unit

17: insulation

18: fixed pin

Claims

A unit electrode unit having a structure in which a porous flexible graphite foil surrounds both surfaces of a hybrid activated carbon fiber electrode;

Electrodes of the same polarity in combination with the insulating portion of the woven fiber to insulate the same are stacked in parallel in the same direction to pass through the electrode coupling pin in a stacked state as a laminated electrode structure in which electrical bonding is made for each of the same electrode A main body portion having a high permeability and high elastic fiber woven cover on an upper surface of the cover;

An electrode module coupled to the electrode module fixing part by penetrating both ends of the insulating part having no unit electrode with a fixing pin;

Filtration portion formed with a plurality of curved cross-section on the surface of the electrode module:

Contacting one surface of the filtration unit, pressing the electrode part of the electrode module according to the curved surface of the filtration unit to be in close contact with the filtration unit and the electrode module, and mechanically compressing the electrodes of the electrode module to space the electrode. An electrode for a capacitive deionization (CDI) using a permeable hybrid activated carbon fiber comprising an electrode compression unit to reduce the.
The method according to claim 1,

The activated carbon fiber electrode is a permeable hybrid in which unit electrodes are alternately stacked according to polarity in a state where unit electrodes are laminated with an insulator, and '+' power and '-' power are electrically coupled to each other and in parallel through the electrode coupling pins. (Hybrid) Electrode for CDI using activated carbon fiber.
The method according to claim 1,

The pressing part is inserted into a groove formed along the curvature of the filter part having a plurality of bent cross sections on the front surface so as to correspond to the outer shape of the electrode module. CDI electrode using carbon fiber.
The method according to claim 1,

The hybrid activated carbon fiber electrode is carbonized at a temperature of 290 ~ 310 ℃ after impregnating the rayon-based fabric fabric in phosphate, the electrode is connected to the + + power according to the polarity of the carbon fabric fabric Is impregnated with SiO 3 solution, the electrode connected to the '-' power is impregnated with Al₂O 3 solution, and the impregnated carbon fiber fabric is put into a kiln and steam is injected into the kiln at a temperature of 850 to 950 ° C. Electrode for CDI using a permeable hybrid activated carbon fiber prepared by active firing.