Device and system for producing pure water using electric field filtration

Abstract

[Problem] To provide a device for producing pure water and a system for producing pure water. [Solution] The present invention is provided with: an anion separation part 10A which is provided with an anion separation chamber 52 for supplying raw water 11 that contains an anion component and a cation component, and separating the anion component, as a first discharge liquid 11A, from the raw water 11 by an electric field filtering action; a cation separation part 10B which is provided with a cation separation chamber 54 for introducing a cation liquid 16 containing the cation component from which the anion component has been separated, and separating the cation component, as a second discharge liquid 11B, by an electric field filtering action; and a pure water chamber 55 for discharging a pure water 11C from which the anion component and the cation component have been removed.

Description

Pure water production equipment and system using electrolytic filtration

[0001] The present invention relates to a pure water producing apparatus and a pure water producing system using electrofiltration.

[0002] Conventionally, ultrapure water used in semiconductor manufacturing processes is produced by sequentially treating raw water, such as river water, well water, or industrial water, in a pretreatment system, a primary pure water system, and a secondary pure water system. In the primary pure water system, the treated water from the pretreatment system is treated with an activated carbon adsorption device, a deionizer using ion exchange resins, or a reverse osmosis membrane device for removing ionic substances and particulate components to achieve a high level of purity. Furthermore, if necessary, a degasser is used to remove dissolved carbon dioxide and oxygen from the water, and an ultraviolet irradiation device and an ion exchange polisher are combined to remove organic matter from the water. Technologies have been proposed for the secondary pure water system, in which the pure water from the primary pure water system is treated with an ion exchange polisher or an ultrafiltration device to further increase the purity (see, for example, Patent Documents 1 and 2).

[0003] JP 2009-10681 A JP 2013-215679 A

[0004] However, the primary pure water system disclosed in Patent Document 1 requires the use of a deionization device using an activated carbon adsorption device, an ion exchange resin, or the like, to achieve high purity of treated water from the pretreatment system. This poses a problem when producing pure water over a long period of time, as it requires the use of chemicals to regenerate the ion exchange resin. Furthermore, the device treated with chemicals during regeneration must be washed with a large amount of pure water. In other words, when producing pure water, the resulting pure water is used for washing, resulting in a poor yield of pure water production.

[0005] Therefore, there is a strong demand for a technology that can separate cations and anions in raw water without using chemicals or the like.

[0006] In view of the above problems, an object of the present invention is to provide a pure water production apparatus and system that use electrofiltration, which can produce pure water by passing raw water through the electrofiltration process without using chemicals or the like in the process of producing pure water, and separating cations and anions through electrofiltration.

[0007] A first aspect of the pure water production apparatus using electrofiltration according to the present invention is characterized by comprising: an anion separation section having an anion separation chamber that supplies raw water containing anionic and cationic components and separates the anionic components in the raw water by electrofiltration to produce an anionic component discharge liquid; a cation separation section having a cation separation chamber that introduces cationic liquid containing cation components from which the anionic components have been separated and separates the cationic components by electrofiltration to produce a cationic component discharge liquid; and a pure water chamber that discharges pure water from which the anionic and cationic components have been removed.

[0008] A pure water production apparatus using electrofiltration according to a second aspect of the present invention is characterized by comprising: an anion separation section equipped with a cation separation chamber that supplies raw water containing anionic and cationic components and separates the cationic components in the raw water by electrofiltration to produce a cationic component discharge liquid; a cation separation section equipped with an anion separation chamber that introduces anionic liquid containing anionic components from which the cationic components have been separated and separates the anionic components by electrofiltration to produce a cationic component discharge liquid; and a pure water chamber that discharges pure water from which the anionic and cationic components have been removed.

[0009] A pure water producing apparatus using electrofiltration according to a third aspect of the present invention comprises: a supply chamber for supplying raw water containing anionic and cationic components; an anion separation section having an anion separation chamber that separates anionic components in the raw water by electrofiltration as an anionic component discharge liquid; a cation separation section having a cation separation chamber that receives a cationic liquid containing cation components from which the anionic components have been separated and separates cationic components by electrofiltration as a cationic component discharge liquid; and a pure water chamber that discharges pure water from which the anionic and cationic components have been removed as filtrate, wherein the anion separation section is arranged on both sides of the anion separation chamber and comprises: a flat anode electrode having through holes that is arranged on the supply chamber side; a cathode filter plate electrode having pores and a diaphragm with pores that separates the anionic components; and a cation chamber into which the separated cationic components flow together with water as a cationic liquid; and wherein the cation separation section comprises: a cation separation chamber into which the cationic liquid is introduced; The cation separation chamber is characterized by comprising an anode filter plate electrode equipped with a diaphragm for separating cation components, and a flat cathode electrode.

[0010] A fourth aspect of the present invention is the water purifying apparatus of the third aspect, characterized in that the anion separation section and the cation separation section are arranged in this order from the supply chamber side.

[0011] A fifth aspect of the present invention is directed to the water purification system of the third aspect, characterized in that the cation separation section and the anion separation section are arranged in this order from the supply chamber side.

[0012] A sixth aspect of the present invention is directed to the pure water production apparatus of the third aspect, characterized in that it further comprises a discharge section that discharges the cationic liquid in the cation chamber to the outside as cationic component wastewater.

[0013] A seventh aspect of the present invention is the pure water producing apparatus of the third aspect, characterized in that it further comprises a pH adjusting electrode provided in the pure water chamber for adjusting pH.

[0014] The pure water producing apparatus of an eighth aspect according to the present invention is the third aspect, characterized in that a surface treatment layer using fluorine gas is formed on the surface of the diaphragm.

[0015] A ninth aspect of the present invention is a pure water producing apparatus according to the third aspect, characterized in that a coating layer having a high dielectric constant is formed on the surface of each of the cathode filter plate electrode, the flat anode electrode, the anode filter plate electrode, and the flat cathode electrode.

[0016] A tenth aspect of the present invention is the pure water producing apparatus of the ninth aspect, characterized in that the high dielectric constant coating layer has been subjected to a poling treatment.

[0017] The pure water production system of an eleventh aspect of the present invention is characterized in that it uses the pure water production apparatus of any one of the first to tenth aspects as a pre-treatment device, and is equipped with a polisher filled with ion exchange resin for finishing the obtained pure water, thereby producing highly purified pure water.

[0018] A twelfth aspect of the pure water producing system according to the present invention is the pure water producing system of the eleventh aspect, characterized in that the first to tenth pure water producing apparatuses are further installed downstream of the polisher as downstream treatment devices to produce ultrapure water.

[0019] A thirteenth aspect of the pure water production system according to the present invention is the pure water production system of the eleventh aspect, characterized in that the voltage of the downstream pure water production apparatus is set higher than the voltage of the upstream pure water production apparatus.

[0020] A pure water production system according to a fourteenth aspect of the present invention is characterized in that it comprises the pure water production apparatus according to any one of the first to tenth aspects, and an electrolyte adjustment unit that adjusts the obtained pure water by adding electrolyte components, and produces drinking water.

[0021] According to the present invention, cations and anions contained in raw water can be efficiently separated, and in the process of producing pure water, no chemicals are used to regenerate the ion exchange resin, and the obtained pure water can be used to produce pure water without cleaning the equipment.

[0022] FIG. 1 is a schematic diagram of a pure water production apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of a pure water production apparatus according to a second embodiment of the present invention. FIG. 3 is a schematic diagram of a pure water production apparatus according to a third embodiment of the present invention. FIG. 4 is a schematic diagram of another pure water production apparatus according to the third embodiment of the present invention. FIG. 5 is a schematic diagram of a pure water production apparatus according to a fourth embodiment of the present invention. FIG. 6 is a schematic diagram of a pure water production apparatus according to a fifth embodiment of the present invention. FIG. 7 is a schematic diagram of a pure water production system according to a seventh embodiment of the present invention. FIG. 8 is a schematic diagram of a pure water production system according to an eighth embodiment of the present invention. FIG. 9 is a schematic diagram of a drinking water production system according to a ninth embodiment of the present invention. FIG. 10 is a schematic diagram of another electrofiltration apparatus according to the first embodiment of the present invention. FIG. 11 is a schematic diagram of a filter plate electrode of another electrofiltration apparatus according to the first embodiment of the present invention. FIG. 12 is a schematic diagram of a flat anode electrode of another electrofiltration apparatus according to the first embodiment of the present invention. FIG. 13 is a schematic diagram of a filter medium of another electrofiltration apparatus according to the first embodiment of the present invention. FIG. 14 is a schematic diagram of a poling treatment of a high dielectric constant coating layer according to the present invention.

[0023] An embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the following detailed description of the invention (hereinafter referred to as the embodiment). The components in the embodiment include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of what is known as equivalents. The components disclosed in the embodiment can be combined as appropriate. In the embodiments of this specification, identical components are designated by the same reference numerals throughout. This embodiment is merely an example that embodies the configuration of the present invention, and various design modifications can be made without departing from the scope of the claims.

[0024] 1A is a schematic diagram of a pure water production system according to Embodiment 1 of the present invention. The pure water production system 100A according to Embodiment 1 is an apparatus that separates cations and anions dissociated in a solvent (polar solvent, for example, water) that is raw water 11, which is an electrolyte solution, and produces pure water.

[0025] Here, ion dissociation is a general process in which molecules (or ionic compounds such as salts and complexes) separate or split into small particles such as atoms, ions, and radicals, usually reversibly. The lattice of an ionic crystal breaks down when dissolved in water, and dissociation refers to the separation of ions that occurs when a solid ionic compound dissolves. As an example, using the formula unit of sodium chloride (NaCl) contained in tap water, sodium chloride (NaCl) dissociates in water into one sodium ion (Na ion; cation (positive) ion) and one chloride ion (Cl ion; anion (negative) ion). That is, in water (H ２ Salt (sodium chloride) that dissolves in water dissociates into its ions and is an electrolyte. In the electrolyte chamber solution, sodium chloride (NaCl) is completely dissociated into water and becomes a cation, sodium ion (Na ＋ ) and anion chloride ion (Cl － ) exist in an ionic state. In addition to dissociated ionic components, tap water also contains positively charged particles (PtCl ＋） , negatively charged particles (Ptcl － ) is also included. In the following, sodium ions (Na ＋ ) and positively charged particles (Ptcl ＋ ) and "positively charged component / cation component", chloride ion (Cl － ) and negatively charged particles (Ptcl － ) are also referred to as "negatively charged components / anionic components."

[0026] Here, the positively charged particles are, for example, some organic substances and some inorganic substances such as alumina, and the negatively charged substances are, for example, many organic substances and many inorganic substances such as silica. Note that the total amount of organic components, including the positively and negatively charged components, can be determined by measuring the TOC (total organic carbon) in the water.

[0027] The pure water production system 100 of the first embodiment is composed of components of an anion separation unit 10A and a cation separation unit 10B. The components located at the bottom of FIG. 1A are explanatory diagrams of the anion separation unit 10A of the first embodiment. The anion separation unit 10A separates cations (Na ＋ ), anions (Cl － ), positively charged particles (Ptcl ＋ ), negatively charged particles (Ptcl － ), and an anion separation chamber 52 for supplying feed water (hereinafter referred to as "raw water") 11, which is an electrolyte solution containing cations (Na ＋ ) a cathode filter plate electrode 14 equipped with a diaphragm (filter material) 13 for separating the separated cations (Na ＋ and a cation chamber 53 into which the alkaline solution 16 flows together with water.

[0028] The cathode filter plate electrode 14 is composed of a first cathode electrode 14A and a second cathode electrode 14B, and a diaphragm (filter material) 13, which is an insulator having pores 13a, is sandwiched between the first cathode electrode 14A and the second cathode electrode 14B. The diaphragm 13 is made of an insulating material, such as polypropylene (PP), polyethylene (PE), nylon (NY), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF; a fluorine-based resin), or a nonwoven fabric made of fibers such as cellulose.

[0029] The anion separation unit 10A further includes a first power supply 41 electrically connected to the flat-plate anode electrode 15 and the first cathode electrode 14A, and a second power supply 42 electrically connected to the first cathode electrode 14A and the second cathode electrode 14B. Here, the electrode configuration is such that, when the second cathode electrode 14B is at a first potential (V1 = 10 V), the first cathode electrode 14A is at a second potential (V2 = 20 V), and the flat-plate anode electrode 15 is at a third potential (V3 = 30 V), the absolute potential difference is 20 V. The absolute value of the cathode potential supplied from the second power supply 42 increases with increasing distance from the anion separation chamber 52 (V2 (20 V) > V1 (10 V)).

[0030] The electrode configuration is not limited to the configuration of FIG. 1A , and a configuration is also possible in which the cathode first electrode 14A is earthed, the cathode first electrode 14A is used as a reference electrode, the potential (V2) of the cathode first electrode 14A is set to 0 V, the potential (V1) of the cathode second electrode 14B is set to −10 V, and the potential (V3) of the flat anode electrode 15 is set to +10 V, and the absolute value of the voltages is changed while the potential difference between them is not changed.

[0031] Here, a cathode electric field Ec is generated between the first cathode electrode 14A and the second cathode electrode 14B. The cathode electric field Ec exerts a repulsive force that inhibits negatively charged ions (Cl − ) from migrating from the supply chamber 12 to the cation chamber 17.

[0032] The cathode electric field Ec generated between the cathode first electrode 14A and the cathode second electrode 14B is a positive ion (Na ＋ ) and positively charged water molecules and positively charged particles (Ptcl ＋ ) from the anion separation chamber 5212 to the cation chamber 53. ＋ ) and positively charged water molecules and positively charged particles (Ptcl ＋) is drawn toward the cation chamber 53, generating an electroosmotic flow (see arrows F1 and F2 in FIG. 1). As a result, the water in the anion separation chamber 52 moves faster than when it moves to the cation chamber 53 simply under the filtration pressure of a pump or the like. Therefore, the amount of water moving from the anion separation chamber 52 to the cation chamber 53 per unit time increases.

[0033] The cation liquid 16A that has moved to the cation chamber 53 is discharged to the outside by filtration pressure from an outlet (not shown) of the cation chamber 53. The anion component discharge liquid 11A from which the cations have been separated in the anion separation chamber 52 has a reduced cation concentration, and is discharged to the outside by filtration pressure from an outlet (not shown) of the anion separation chamber 52.

[0034] Here, the filtration pressure is preferably set by a supply pump (not shown) so that the pressure (gauge pressure) in the supply chamber 12, which is an enclosed space, is slightly higher than atmospheric pressure, for example, 0.005 MPa or more and 0.5 MPa or less, preferably 0.02 MPa or more and 0.1 MPa or less.

[0035] Here, the cathode filter plate electrodes 14 (cathode first electrode 14A, cathode second electrode 14B) are provided with a plurality of holes 14a penetrating in the left-right direction in the figure. Water in the supply liquid 11 moves through the pores 14a of the electrodes 14. The pore diameters of the holes 14a of the cathode first electrode 14A and the cathode second electrode 14B are, for example, 0.1 μm or more and 5000 μm or less, more preferably 100 μm or more and 1000 μm or less. Note that the pore diameters of the holes 14a of the cathode first electrode 14A and the cathode second electrode 14B do not have to be the same.

[0036] Additionally, a galvanic corrosion prevention layer (not shown) is provided on the surfaces of the cathode filter plate electrode 14 (cathode first electrode 14A, cathode second electrode 14B) and the flat plate anode electrode 15. Examples of the galvanic corrosion prevention layer include an insulating coating layer and a conductive precious metal layer. Examples of materials for the galvanic corrosion prevention layer include, but are not limited to, titanium, aluminum, magnesium, and tantalum. Examples of materials for the conductive precious metal layer include, but are not limited to, platinum, gold, and palladium. In the case of an insulating coating layer, the thickness of the galvanic corrosion prevention layer is preferably, for example, approximately 5 μm to 30 μm, more preferably, approximately 5 μm to 10 μm. Furthermore, the thickness of the conductive precious metal layer, such as platinum, gold, or palladium, is preferably, for example, approximately 0.5 μm to 10 μm, more preferably, approximately 1 μm to 5 μm. This galvanic corrosion prevention layer inhibits corrosion of the surfaces of the cathode filter plate electrode 14 and the flat plate anode electrode 15. Furthermore, the cathode filter plate electrode 14 and the flat plate anode electrode 15 have an insulating coating layer and are therefore not in contact with the liquid that constitutes the feed liquid 11. As a result, even if a potential is applied to the cathode filter plate electrode 14 and the flat plate anode electrode 15, electrolysis is unlikely to occur between the liquid and the surfaces of the cathode filter plate electrode 14 and the flat plate anode electrode 15.

[0037] The cathode first electrode 14A faces the flat-plate anode electrode 15 across the anion separation chamber 52. The distance D1 between the cathode first electrode 14A and the flat-plate anode first electrode 15 is, for example, 0.1 mm or more and 100 mm or less, more preferably 0.1 mm or more and 40 mm or less.

[0038] The distance D2 between the first cathode electrode 14A and the second cathode electrode 14B is not particularly limited, but is, for example, 0.1 mm to 20 mm, more preferably 0.1 mm to 2 mm. Note that the smaller the distance D2 between the first cathode electrode 14A and the second cathode electrode 14B, the stronger the strength of the cathode electric field Ec generated between the first cathode electrode 14A and the second cathode electrode 14B.

[0039] Diaphragm 13 can be made of, for example, cellulose such as filter paper (membrane) or nanofiber, but the present invention is not limited to this. Taking filter paper as an example, the pore size is approximately 1 micron (a pore diameter 1000 times larger than 1 nanometer). Since water molecules are sub-nanometers in size, water can easily pass through diaphragm 13. As a result, the supply liquid 11 can be freely passed through diaphragm 13 by a pump that pumps the supply liquid 11 into supply chamber 12.

[0040] On the other hand, negative ions (Cl － ) approach the cathode first electrode 14A, the negative electrode and the negative ions repel each other due to the Coulomb repulsion, and therefore they cannot pass through the cathode first electrode 14A. Conversely, when positive ions (Na ＋ ) approaches, the positive electrode and the positive ions repel each other due to Coulomb's repulsive force.

[0041] As described above, the diaphragm 13 may be, for example, filter paper. However, it is more preferable to use a diaphragm having a dielectric effect. The diaphragm having a dielectric effect is made of an insulating material, such as polypropylene (PP), polyethylene (PE), nylon (NY), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF; a fluorine-based resin), or a nonwoven fabric made of fibers such as cellulose. By placing the diaphragm 13 having a dielectric effect between the first cathode electrode 14A and the second cathode electrode 14B, the strength of the cathode electric field Ec acting between the first cathode electrode 14A and the second cathode electrode 14B is increased. The diameter of the pores 13a of the diaphragm 13 is preferably, for example, 0.2 mm or less.

[0042] The constituent member located at the top of Fig. 1A is an explanatory diagram of the cation separation unit 10B of the first embodiment. As shown in Fig. 1A, the cation separation unit 10B separates cations (Na ＋ ) and positively charged particles (Ptcl ＋ ) and ions are separated.

[0043] As shown in the upper part of FIG. 1A, the cation separation unit 10B includes a cation separation chamber 54 into which the cation liquid 16A is introduced, anode filter plate electrodes 24 disposed on both sides of the cation separation chamber 54 and equipped with diaphragms 13 for separating the cation components, a flat cathode electrode 25, and a pure water chamber 55 into which pure water 10C from which the cation components have been separated flows.

[0044] The anode filter plate electrode 24 is composed of a first anode electrode 24A and a second anode electrode 24B, and a diaphragm 13, which is an insulator having fine holes, is sandwiched between the first anode electrode 24A and the second anode electrode 24B. The diaphragm 13 is made of an insulating material, and may be, for example, a nonwoven fabric made of fibers such as PP (polypropylene), PE (polyethylene), NY (nylon), or cellulose.

[0045] The ion separation unit 10B further includes a third power supply 43 electrically connected to the flat cathode electrode 25 and the anode first electrode 24A, and a fourth power supply 44 electrically connected to the anode first electrode 24A and the anode second electrode 24B.

[0046] As described above, the cationic liquid 16A containing cationic components is introduced into the cationic separation chamber 54. The cationic components (sodium ions (Na ＋ ), positively charged particles (Ptcl ＋ )) is a positive ion, and is therefore blocked by the anode first electrode 24A (in FIG. 1A, sodium ions (Na ＋ ), positively charged particles (Ptcl ＋ As a result, the cation components (sodium ions (Na ＋ ), positively charged particles (Ptcl ＋ As a result, the cation component discharge liquid 11B discharged from the cation separation chamber 54 has concentrated cation components.

[0047] The distance D3 between the first anode electrode 24A and the second anode electrode 24B is not particularly limited, but is, for example, 0.1 mm to 20 mm, more preferably 0.1 mm to 2 mm. Furthermore, the smaller the distance D3 between the first anode electrode 24A and the second anode electrode 24B, the stronger the anode electric field Ea generated between the first anode electrode 24A and the second anode electrode 24B.

[0048] The holes 24a in the first anode electrode 24A and the second anode electrode 24B communicate with the supply chamber 12 and the anion chamber 27. The diameters of the holes 24a in the first anode electrode 24A and the second anode electrode 24B are, for example, 0.1 μm or more and 5000 μm or less, and more preferably 100 μm or more and 1000 μm or less. The diameters of the holes 24a in the first anode electrode 24A and the second anode electrode 24B do not have to be the same.

[0049] An example of producing pure water using tap water as raw water 11 will be described with reference to FIG. 1A.

[0050] As described above, the ion state in the anion separation chamber 52 is determined by the cations (sodium ions: Na ＋ ) and anions (chlorine ions: Cl － ) and the positive ions (Na ＋ ) is attracted to the positive ion, sodium ion (Na ＋ ) is drawn in, resulting in water (H ２ O) while allowing sodium ions (Na ＋ ) penetrates. At the same time, positively charged particles (Ptcl) ＋ ) also moves into the cation chamber 53.

[0051] On the other hand, the anion component (chlorine ion (Cl － ), negatively charged particles (Ptcl － )) is an anion, and is therefore blocked by the negative cathode first electrode 14A (chlorine ion (Cl) in FIG. 1A). － ), negatively charged particles (Ptcl －) bounces back), and cannot pass through the cathode first electrode 14A. － ), negatively charged particles (Ptcl － As a result, the anion component discharge liquid 11A discharged from the anion separation chamber 52 contains cations (Na ＋ ) decreases, and the anion component (chlorine ion (Cl － ), negatively charged particles (Ptcl － The concentrated anion component (chlorine ion (Cl )) is in a concentrated state. － ), negatively charged particles (Ptcl － )) is discharged to the outside as an anion component discharge liquid 11A.

[0052] In the present invention, in the anion separation section 10A, the cathode filter plate electrode 14A blocks the anion component discharge liquid 11A and discharges it to the outside, and the cation component (Na ＋ , positively charged particles (Ptcl ＋ )) permeates through the diaphragm 13 that constitutes the cathode filter plate electrode 14. As a result, the permeated water contains cation components ((Na ＋ ), positively charged particles (Ptcl ＋ ) also acts as a carrier water for the

[0053] As a result, according to the anion separation unit 10A, the inside of the cation chamber 52 is filled with the cation component (Na ＋ , positively charged particles (Ptcl ＋ )) is transferred to obtain a cationic liquid (alkaline liquid) 16A.

[0054] The cations are blocked by the anode filter plate electrode 24A from the cation separation chamber 54, and the cation components (Na ＋ , positively charged particles (Ptcl ＋ )) is discharged as a cationic component discharge liquid 11B.

[0055] As a result, both ionic components (anionic components and cationic components) and organic and inorganic particulate components are removed from the supplied raw water 11, and pure water 11B is introduced into the pure water chamber 55.

[0056] The results of a tap water filtration test using the device of embodiment 1 are shown in Tables 1 and 2.

[0057]

[0058] [Table 1] shows the COD, TOC, pH, electrical conductivity (EC), ion concentration (Na) of the anion component discharge liquid 11A, the cation component discharge liquid 11B, and the filtrate (pure water 11C) after 60 minutes from the supply of tap water to the pure water production apparatus. ＋ , Ca ２＋ , NO ３ － ) results are shown.

[0059] As shown in Table 1, the tap water of raw water 11 was neutral, the anion component discharge liquid 11A was acidic, the cation component discharge liquid 11B was alkaline, and the filtrate, pure water 11C, was weakly acidic. Although the results of measurements using a simple measuring device, the COD and TOC of pure water 11C were "0.0", and the ion concentration (Na ＋ , Ca ２＋ , NO ３ － ) was also "0".

[0060]

[0061] As shown in Table 2, when purified water filtered through a commercially available water purifier was used as raw water, it was confirmed that the residual ion (electrolyte) components in the purified water could be separated with high efficiency.

[0062] In this manner, in this embodiment, pure water 11C can be obtained from raw water 11 without using an ion exchange resin as in the past. In this embodiment, pure water is not produced using an ion exchange resin as in the past, so there is no need to regenerate the ion exchange resin. As a result, no acid or alkaline chemicals, such as those used to regenerate ion exchange resins, are used. Therefore, because no chemicals are used, there is no need to use a portion of the pure water produced for cleaning the pure water production apparatus, and 100% of the pure water obtained can be used as a product.

[0063] In this embodiment, the cathode filter plate electrode 14 (first electrode 14A, second electrode 14B) and the flat anode electrode 15 can be electrodes with high-dielectric-constant coating layers 14b, 15b formed from PVDF or similar, as shown in Figures 10A, 10B, and 10C. Here, PVDF stands for polyvinylidene difluoride, a type of fluororesin. Because PVDF is an insulating layer with a high dielectric constant, an "electrostatic field model" that exhibits capacitance (capacitor) behavior can be constructed between these electrodes. The anode filter plate electrode 24 (first electrode 24A, second electrode 24B) and the flat anode electrode 25 can also be electrodes with high-dielectric-constant coating layers 24b, 25b formed from PVDF or similar.

[0064] By using the electrodes of the "electrostatic field model" as in this embodiment, the current flowing between the electrodes (between the second electrode 14B and the first electrode 14A, and between the first electrode 14A and the flat anode electrode 15) is nearly zero. As a result, no electrolysis occurs, and electrolytic corrosion of the electrodes is suppressed. In addition, there is no change in the pH of the solution, and no Joule heat is generated. As a result, there is no change in the substance to be separated or the liquid quality due to pH fluctuations or thermal denaturation.

[0065] Other examples of high-dielectric-constant materials with insulating and dielectric properties similar to those of the aforementioned PVDF include: 1) P(VDF-TrFE): poly(vinylidene fluoride-trifluoroethylene) 2) P(VDF-CTFE): poly(vinylidene fluoride-chlorotrifluoroethylene) 3) Polyamide 11 (Nylon (registered trademark) 11) 4) PTFE: polytrifluoroethylene 5) liquid crystalline ferroelectric polymer 6) MXene / PVDF composite Here, MXene is a general term for a composite atomic layer compound made of an early transition metal (such as titanium or vanadium) and a light element (carbon or nitrogen), and has a sheet-like structure similar to graphene.

[0066] Examples of methods for forming the high dielectric constant coating layers 14b, 15b include the following: 1) Forming a coating layer of a predetermined thickness on the surface of the electrode using PVDF electrostatic spraying or powder firing. 2) Forming a coating layer of a predetermined thickness on the surface of the electrode using PVDF ink screen printing or inkjet printing. 3) Forming a coating layer of a predetermined thickness on the surface of the electrode using vacuum lamination and solution casting of a PVDF film (e.g., 7-200 μm). 4) Preparing a PVDF solution and forming a coating layer of a predetermined thickness on the surface of the electrode using a dipping method.

[0067] After the coating layer is formed, the high-dielectric-constant coating layer is subjected to a poling treatment (dipole alignment treatment 9). This poling treatment involves applying an external electric field, such as corona discharge, to the coating layer to align the molecular orientation and the random orientation of electric dipoles perpendicular to the electrode plane, as shown in Figure 11. By performing the poling treatment, high dielectric polarization can be generated in the high-dielectric-constant coating layer when a voltage is applied.

[0068] Here, the electrode in which a platinum coating layer (corrosion-resistant layer) is formed on the surface of the titanium electrode is a "conductive electric field model." When using this "conductive electric field model" electrode, in the electrolyte solution, the electrolyte (cation, H ＋ , anion, OH － ) through which current flows between the electrodes.

[0069] When electrodes of the "conductive electric field model" are used, electrolysis occurs, generating hydrogen and oxygen at both electrodes. Because electrolytic corrosion of the electrodes occurs, a countermeasure, such as a platinum coating, is required on the electrode surface, as mentioned above. Furthermore, the pH of the solution changes, generating Joule heat.

[0070] The force acting on particles (electric field strength) and the particle movement speed (electrophoretic speed) are almost the same in the "conductive electric field model" composed of an electrode in which, for example, the surface of a titanium electrode is coated with platinum, and the "electrostatic electric field model" composed of an electrode in which a thin film coating layer with a high dielectric constant such as PVDF (for example, layer thickness of 1 μm to 100 μm) is applied to the surface of a conductive electrode such as stainless steel, copper, or carbon.

[0071] Here, the configuration of the electrostatic electric field model is the same not only for the electrode 14 consisting of the first electrode 14A and the second electrode 14B equipped with the filter material, but also for the flat anode electrode 15. The configuration of the electrostatic electric field model can also be applied to the anode filter plate electrode 24 equipped with the filter material 13 and the flat cathode electrode 25.

[0072] The surface treatment method for the filter medium 13 will be described.

[0073] In this embodiment, as shown in FIGS. 10A and 10D, a surface treatment layer 13b using fluorine gas (direct fluorination treatment) may be formed.

[0074] Here, the surface treatment using fluorine gas utilizes the extremely high reactivity of fluorine gas to improve the surface characteristics of the filter medium 13. In other words, fluorine gas is brought into contact with the filter medium 13, which is the base material, to chemically modify the surface of the base material.

[0075] By applying this fluorine treatment to the surface of the material of the filter medium 13, it is possible to give the material electrical surface properties similar to those of PVDF (Polyvinylidene DiFluoride) or PTFE (Polytetrafluoroethylene), etc. As a result, the material exhibits a dipole orientation effect when electricity is applied.

[0076] [Embodiment 2] A pure water production system 100B of embodiment 2 is a modified example of the pure water production system 100A of embodiment 1. Fig. 1B is a schematic diagram of a pure water production system of embodiment 2 according to the present invention. As shown in Fig. 1B, the difference from embodiment 1 is that an anion separation section 10A is provided after the cation separation section 10B. As a result, a cation component discharge liquid 11B is discharged to the outside at the upstream side, and an anion component discharge liquid 11A is discharged to the outside at the downstream side.

[0077] [Embodiment 3] In the pure water production systems 100A and 100B of embodiments 1 and 2, the anion separation section 10A and the cation separation section 10B are configured as independent sections, but in the pure water production system 200 of this embodiment, these sections are integrated.

[0078] 2A is a schematic diagram of a pure water production apparatus according to a third embodiment of the present invention. FIG. 2B is a schematic diagram of another pure water production apparatus according to the third embodiment of the present invention. As shown in FIG. 2A, the pure water production apparatus 200A-1 includes a supply chamber 51 for supplying raw water 11 containing anion components (◇-: the symbol in the figure is a "-" inside ◇) and cation components (◇+: the symbol in the figure is a "+" inside ◇), an anion separation unit 10A including an anion separation chamber 52 for separating the anion components (◇-) in the raw water 11 as anion component discharge liquid 11A by electrofiltration, a cation separation unit 10B including a cation separation chamber 54 for introducing a cation liquid 16A containing cation components (◇+) from which the anion components (◇-) have been separated and separating the cation components (◇+) as second discharge liquid 11B by electrofiltration, and a pure water chamber 55 for introducing pure water 11C from which the anion components and cation components have been removed.

[0079] The anion separation section 10A is arranged on both sides of the anion separation chamber 52, and is equipped with a flat anode electrode 61 having a through hole 61a (hole diameter: 0.2 mm to 2.0 mm) arranged on the supply chamber 51 side, a diaphragm (filter material) 13 having pores 13a (pore diameter: 0.2 mm or less) that separate the anion component (◇-), a cathode filter plate electrode 14 having pores 14a (pore diameter: 500 nm or less; 200 to 500 nm), and a cation chamber 53 into which the separated cation component (◇+) flows together with water as a cation liquid (hereinafter also referred to as "alkaline liquid") 16A.

[0080] In addition, the cation separation section 10B is arranged on the cation chamber 53 side and is equipped with an inversion electrode 62A having a through hole 62a (hole diameter: 0.2 mm to 2.0 mm), a diaphragm (filter material) 13 having pores 13a that separate the cation component (◇+), and a cathode filter plate electrode 24 having pores 14a.

[0081] The separation behavior of ionic components in the pure water production system 200A-1 of Fig. 2A will be explained using the schematic diagram of ion behavior in Fig. 3A. Raw water 11 introduced into supply chamber 51 passes through through-hole 61a. Here, the upper side of Fig. 3A represents cation components (positively charged substances) (◇+), the lower side represents anion components (negatively charged substances) (◇-), and the middle represents electrically neutral.

[0082] The flat anode electrode 61 is a positive pole (anode electrode), and the cation components (◇+) in the raw water 11 are forcibly introduced into the anion separation chamber 52 by flowing in from a supply line (not shown) through which the raw water 11 is supplied.

[0083] However, when the raw water 11 is introduced into the anion separation chamber 52, the anion components (◇-) in the raw water 11 are attracted toward the flat anode electrode 61 (positive pole (anode electrode)) while being introduced into the anion separation chamber 52. As a result, a concentration gradient is formed due to the electrophoresis phenomenon in which the concentration of the anion components (◇-) is higher near the anode electrode 61.

[0084] Thereafter, the anion components are removed by the anode filter plate electrode 14, and the cation components pass through 14 and are introduced into the cation chamber 53 as a cationic liquid 16A.

[0085] Therefore, the cationic component (◇+) in the cationic liquid 16 introduced from the cationic chamber 53 into the cationic separation chamber 54 is attracted toward the flat-plate reversal electrode 62 (negative pole (cathode electrode)) and introduced into the cationic separation chamber 54, resulting in a concentration gradient due to the electrophoresis phenomenon in which the concentration of the cationic component (◇+) is higher near the reversal electrode (cathode electrode) 62A.

[0086] The behavior of ions in Fig. 3B is the case when the reversal electrode 62A is reversed, as in the pure water production system 200A-2 in Fig. 2B. With this reversal electrode 62B, the behavior in the cation chamber 53 is different, the separation efficiency is improved, and the concentration gradient is reversed.

[0087] [Embodiment 4] In the pure water production systems 200A-1 and 200A-2B of embodiment 3, the anion separation unit 10A and the cation separation unit 10B are arranged in this order from the supply chamber 51 side, but the present invention is not limited to this. Figures 4A and 4B are schematic diagrams of a pure water production system of embodiment 4 according to the present invention.

[0088] In the pure water producing systems 200B-1 and 200A-B of the fourth embodiment, an anion separation unit 10B and a cation separation unit 10A are arranged in this order from the supply chamber 51 side.

[0089] [Embodiment 5] Figure 5 is a schematic diagram of a pure water production system of embodiment 5. The pure water production system 100C of embodiment 5 is a modified example of the pure water production system 100A of embodiment 1. As shown in Figure 5, the pure water production system 100C of embodiment 5 is provided with a discharge part that discharges the cationic liquid 16 in the cation chamber 53 to the outside as a cationic component discharge liquid 11D.

[0090] When the raw water 11 contains a large proportion of cationic components, the cationic liquid 16 in the cation chamber 53 is discharged to the outside as cationic liquid wastewater 11D. This reduces the proportion of cationic components remaining in the pure water 11C introduced into the pure water chamber 55. In other words, the separated cationic liquid 16 is actively discharged to the outside as cationic liquid wastewater 11D before being introduced into the cation separation chamber 54. This prevents cationic components from leaking into the pure water 11C introduced into the pure water chamber 55. As a result, the quality of ion separation when producing pure water 11C can be improved.

[0091] [Embodiment 6] Fig. 6 is a schematic diagram of a pure water production system of embodiment 6. As shown in Fig. 6, a pure water production system 200D of embodiment 6 is configured such that a pH adjusting electrode 63 for adjusting pH is provided in the pure water chamber 55 of the pure water production system of embodiment 2.

[0092] It is desirable that the pure water be neutral, and therefore a pH adjusting electrode 63 is provided as a monitoring electrode for monitoring this. It is desirable that the pure water does not have an imbalance in ions.

[0093] As shown in Table 1, the pH of the raw water (tap water) 11 is about 7.3, but the anion component discharge liquid 11A is acidic, with a pH of 3.0. On the other hand, the cation component discharge liquid 11B is alkaline, with a pH of about 11.2. The pure water 11C, which is the filtrate 11C, has a pH of about 5.0. For this reason, a monitoring electrode 63 is installed to monitor the pH state, thereby controlling the electrolysis of water.

[0094] This allows hydrogen ions (H ＋ ), hydroxide ion (OH － The bias in the distribution of ions (ions) can be adjusted as desired. By generating a large amount of hydrogen ions and reversing the flow, the concentration of hydroxide ions changes, and a pH meter 65 is installed to confirm this. In addition, the electrolysis zone can be freely controlled by increasing the voltage to promote electrolysis or decreasing the voltage to suppress electrolysis.

[0095] As a result, pH adjustment is possible without the use of pH-adjusting chemicals, and neutral water of any desired pH (pure water with a pH of about 7.0) can be obtained. The pH adjustment electrode 63 has the same configuration as the inlet electrode 61 and the reversal electrode 62, and is provided with holes. The hole diameter is not particularly limited as long as it does not cause filtration resistance in the raw water 11.

[0096] [Embodiment 7] Figure 7 is a schematic diagram of a pure water production system according to embodiment 7. As shown in Figure 7, the pure water production system according to embodiment 7 includes a pure water production apparatus 200 (200A-200D) according to any one of embodiments 1 to 6 as a pre-treatment device, and a mixed-bed polisher 30 filled with ion exchange resin for finishing the obtained pure water 11C, thereby producing highly purified pure water 11D. This polisher may be made of a known ion exchange resin for ultrapure water, which has extremely low initial elution and elution over time.

[0097] The analysis results of this highly purified pure water 11D are shown in Table 3. As shown in Table 3, the EC (Electrical Conductivity) was 1 μS / cm, and the TOC was 0.00 (less than 0.005 mg / L) as displayed by a simple measuring device.

[0098]

[0099] [Embodiment 8] Fig. 8 is a schematic diagram of a pure water production system according to embodiment 8. As shown in Fig. 8, a pure water production apparatus 200 (200A to 200D) may be installed as a post-treatment device downstream of a mixed-bed polisher 30 to further reduce the EC value and refine the water to produce so-called ultrapure water 11F.

[0100] In this case, when installing multiple stages of pure water production systems, the same voltage configuration may be used, but the voltage of the pure water production system 200-2 in the subsequent stage may be set higher than the voltage of the pure water production system 200-1 in the preceding stage.

[0101] This is because the downstream pure water production system 200-2 can be operated at a higher voltage (e.g., 80 V to 400 V) to compensate for the reduced number of ions in the upstream pure water production system 200-1. This is because the electrolytes are removed in the upstream stage, so electrolysis does not occur in the downstream stage.

[0102] [Embodiment 9] Figure 9 is a schematic diagram of a drinking water production system according to embodiment 9. As shown in Figure 9, an electrolyte adjustment unit 501 that adjusts the electrolyte components in the pure water 11C is installed downstream of the pure water production system 200 (200A to 200D). This electrolyte adjustment unit 501 adds various mineral components suitable for drinking water 11G.

[0103] The mineral components are mainly sodium (Na), magnesium (Mg), calcium (Ca), and potassium (K). The taste and hardness of the drinking water 11G can be adjusted by balancing the content of these four major minerals.

[0104] In addition to the essential minerals, iron and zinc may be added. Furthermore, vanadium (V), germanium (Ge), silica, etc. may be added. This allows artificial drinking water to be produced according to the intended use and needs.

[0105] In this embodiment, tap water is used as the raw water 11, but the raw water 11 is not limited to this. For example, seawater can be used as the raw water 11 and desalinated to produce pure water. In this case, by using "electrostatic field model" electrodes with a high dielectric constant such as PVDF as described above, the current flowing between the electrodes (between the second electrode 14B and the first electrode 14A, and between the first electrode 14A and the flat anode electrode 15) becomes almost zero. This prevents electrolysis from occurring, thereby suppressing electrolytic corrosion of the electrodes.

[0106] The present invention can be applied to all water purifiers and water purifier systems that can efficiently separate pure water from raw water.

[0107] 100A, 100B Pure water production apparatus 10A Anion separation section 10B Cation separation section 11 Raw water 11A Anion component discharge liquid 11B Cation component discharge liquid 11C Pure water 11D Highly purified pure water 11F Ultrapure water 13 Diaphragm 14 Cathode filter plate electrode 15 Flat plate anode electrode 24 Anode filter plate electrode 25 Flat plate cathode electrode 52 Anion separation chamber 53 Cation chamber 54 Cation separation chamber 55 Pure water chamber 61A Reversal electrode 61B Reversal electrode 61a Through hole 62 Reversal electrode

Claims

1. A pure water production system using electrofiltration, comprising: an anion separation section having an anion separation chamber which receives raw water containing anionic and cationic components and separates the anionic components in the raw water by electrofiltration to produce an anionic component discharge liquid; a cation separation section having a cation separation chamber which receives cationic liquid containing cation components from which the anionic components have been separated and separates the cationic components by electrofiltration to produce a cationic component discharge liquid; and a pure water chamber which discharges pure water from which the anionic and cationic components have been removed.

2. A pure water production system using electrofiltration, comprising: an anion separation section equipped with a cation separation chamber that receives raw water containing anionic and cationic components and separates the cationic components in the raw water by electrofiltration to produce a cationic component discharge liquid; a cation separation section equipped with an anion separation chamber that receives anionic liquid containing anionic components from which the cations have been separated and separates the anionic components by electrofiltration to produce a cationic component discharge liquid; and a pure water chamber that discharges pure water from which the anionic and cationic components have been removed.

3. A device comprising: a supply chamber for supplying raw water containing anion components and cation components; an anion separation section having an anion separation chamber that separates anion components in the raw water by electrofiltration to produce an anion component discharge liquid; a cation separation section having a cation separation chamber that introduces a cation liquid containing cation components from which the anion components have been separated and separates cation components by electrofiltration to produce a cation component discharge liquid; and a pure water chamber that discharges pure water from which the anion components and cation components have been removed as filtrate, wherein the anion separation section is arranged on both sides of the anion separation chamber and comprises: a flat anode electrode having a through hole arranged on the supply chamber side; a cathode filter plate electrode having a diaphragm with pores that separates the anion components; and a cation chamber into which the separated cation components flow together with water as a cation liquid; and wherein the cation separation section comprises: a cation separation chamber into which the cation liquid is introduced; A pure water production apparatus using electrofiltration, characterized by comprising: an anode filter plate electrode equipped with a diaphragm for separating cation components, and a flat cathode electrode, which are arranged on both sides of the cation separation chamber.

4. The pure water production system using electrolytic filtration according to claim 3, wherein the anion separation section and the cation separation section are arranged in this order from the supply chamber side.

5. The pure water production system using electrolytic filtration according to claim 3, wherein the cation separation section and the anion separation section are arranged in this order from the supply chamber side.

6. The pure water production system using electrolytic filtration according to claim 3, further comprising a discharge section for discharging the cationic liquid in the cation chamber to the outside as cationic wastewater.

7. The pure water producing apparatus by electrofiltration according to claim 3, further comprising a pH adjusting electrode provided in said pure water chamber for adjusting the pH.

8. The pure water production system by electrolytic filtration according to claim 3, wherein a surface treatment layer using fluorine gas is formed on the surface of the diaphragm.

9. The pure water production apparatus using electrolytic filtration according to claim 3, characterized in that a coating layer with a high dielectric constant is formed on the surface of each of the cathode filter plate electrode, the flat anode electrode, the anode filter plate electrode, and the flat cathode electrode.

10. The pure water production system using electrofiltration according to claim 9, wherein the high dielectric constant coating layer is subjected to a poling treatment.

11. A pure water production system characterized by using the pure water production apparatus according to any one of claims 1 to 10 as a pre-treatment device, and having a polisher filled with ion exchange resin for finishing the obtained pure water, thereby producing highly purified pure water.

12. The pure water producing system according to claim 11, further comprising a pure water producing apparatus according to any one of claims 1 to 10 installed downstream of the polisher as a downstream treatment device to produce ultrapure water.

13. The pure water production system according to claim 12, wherein the voltage of the downstream pure water production apparatus is set higher than the voltage of the upstream pure water production apparatus.

14. A pure water production system comprising the pure water production apparatus according to any one of claims 1 to 10 and an electrolyte adjustment unit that adjusts the obtained pure water by adding electrolyte components, for producing drinking water.

Images