JP5036746B2 - Chloride ion removing apparatus and chloride ion removing method - Google Patents

Description

  The present invention relates to a chloride ion removing apparatus for obtaining treated water having a reduced chloride ion concentration by removing chloride ions from water to be treated containing chloride ions, and chloride ion removal using the same. Regarding the method.

Many slaughterhouses (slaughterhouses) use natural water such as groundwater and river water to save water bills in order to use a large amount of water when washing meat. However, natural water obtained at a location close to the sea and hot springs, chloride ion (Cl ^-) may contain a high concentration, unless subjected to some processing, that it is not available, such as the cleaning of the meat was there. This is because water used for food production (hereinafter referred to as “food manufacturing water”), such as water used for washing meat at slaughterhouses, is suitable for drinking in the Food Sanitation Law. This is because it is stipulated that the concentration of chloride ions contained in it must be 200 mg / L or less, which is the water quality standard of the Waterworks Law.

Incidentally, chloride ion (Cl ^-) chloride from the treated water containing ion (Cl ^-) or by separating the water, chloride ion removal than the water to be treated to obtain a low treated water of chloride ion concentration Various methods have been proposed so far for the purpose of desalination of seawater, treatment of waste water, and the like. As a method for removing chloride ions, for example, a distillation method, a coagulation precipitation method, an electrolysis method (for example, Patent Document 1), an ion exchange membrane method (for example, Patent Documents 2 and 3), a reverse osmosis membrane method (for example, Patent Documents 4 and 5) are known.

  Among these methods for removing chloride ions, the distillation method is a method for obtaining water to be treated (distilled water) having a reduced chloride ion concentration by evaporating the water to be treated and then cooling and condensing. Distillation methods are very poor in thermal efficiency, so they are often reduced in pressure to lower the boiling point of water to be treated, but they still consume a large amount of energy, and the processing cost is very high. Had. For this reason, the distillation method has not been suitable for applications where it is desired to obtain water that satisfies the water quality standards of the Waterworks Law at the lowest possible cost, as in the case of the slaughterhouse described above.

Coagulating sedimentation method, by adding a coagulant, such as silver nitrate (AgNO ₃₎ in the treated water, treated water chloride ion ^- collected as insoluble precipitates such as silver chloride (AgCl), (Cl) This is a method of removing the supernatant as treated water. However, flocculation precipitation method, the water to be treated in a chloride ion (Cl ^-) If you try to remove to low levels, must be added a coagulant in large quantities, it has the disadvantage of also processing cost increases It was. In addition, since the treated water is colored purple by the precipitated silver chloride (AgCl), the treated water is also difficult to reuse as food production water.

The electrolysis method involves immersing a pair of electrodes in water to be treated, and connecting one (anode) of the pair of electrodes to the positive electrode of the DC power source and the other (cathode) to the negative electrode of the DC power source. In this method, chloride ions (Cl ⁻ ) in the treated water are oxidized at the anode and separated from the treated water as chlorine gas (Cl ₂ ). However, the electrolysis method has a drawback that a large amount of toxic chlorine gas (Cl ₂ ) is generated.

Ion-exchange membrane method, chloride ions without transmit water molecules (Cl ^-) and an anion exchange membrane for selectively transmitting the anions such as sodium ions without transmit water molecules (Na ^+), etc. through treatment water between the cation exchange membrane for selectively passing a cation of a DC voltage is applied from the outer surfaces of the membrane, the water to be treated of the chloride ions (Cl ^-) anion exchange membrane This is a method of obtaining treated water by lowering the chloride ion concentration of water to be treated by moving it to the anode side.

In this ion exchange membrane method, not only when the chloride ion concentration of the water to be treated is high, even if it is not as high as several hundred mg / L, tens of mg / L or less, or The chloride ion concentration can be lowered to a level of several mg / L or less, and it is very excellent in terms of the ability to remove chloride ions (Cl ⁻ ). Moreover, there is an advantage that the treated water is not colored and can be used as food production water. However, the ion exchange membrane method has the disadvantage that the cost for introducing and maintaining the equipment increases because the ion exchange membrane used for the ion exchange membrane method is expensive. In addition, the ion exchange membrane method has a drawback in that chloride ion-enriched water in which chloride ions (Cl ⁻ ) are concentrated is generated outside (an anode side) of the anion exchange membrane. Since chloride ion concentrated water may adversely affect the environment, discharge is regulated depending on the chloride ion concentration.

Reverse osmosis membrane method, chloride ion (Cl ^-) partitioning the inside of the container a reverse osmosis membrane which selectively permeates water molecules without transmit impurities such as, for convenience of the one (described "first chamber" . be referred to as chloride ion (Cl to) ^-. with add-treatment water containing) and the other (for convenience of explanation, be referred to as "second chamber") to such as tap water or pure water, chloride ion (Cl ^-) placed contain little water, by applying pressure greater than the osmotic pressure to the water to be treated, transferred to a second chamber by transmitting a reverse osmosis membrane only water molecules in the water to be treated, the second This is a method of taking out the room water as treated water. In the ion exchange membrane method described above, the water to be treated is taken out as treated water. In this reverse osmosis membrane method, the water in the second chamber is taken out as treated water, not the water to be treated in the first chamber. It will be.

The reverse osmosis membrane method, chloride ion (Cl ^-) in addition to an excellent ability to remove, since the non-ionic impurities can be removed, still cleaner than with an ion-exchange membrane process Water can be obtained. However, the reverse osmosis membrane method has a disadvantage that the cost of introducing and maintaining the equipment is increased because the reverse osmosis membrane used for the method is expensive. In addition, the reverse osmosis membrane method, chloride ion (Cl ^-) for the water to be treated was a chloride ion concentrated water concentrated from remaining in the first chamber, the water to be treated after the treatment (chloride ion In addition to being troubled with the handling of the concentrated water), there was a drawback that the total amount of treated water added could not be taken out as treated water. In the reverse osmosis membrane method, if the pressure applied to the treated water is further increased, the amount of treated water remaining in the first chamber can be reduced. The cost is further increased.

As described above, various methods for removing chloride ions have been proposed so far, but all of them have a high ability to remove chloride ions (Cl ⁻ ), but at a high cost, or in the first place, chloride ions. (Cl ^-) or low ability of removing, or is generated chloride ion concentration water, treated water to the total amount or not can be taken out as treated water, treated water or colored by adding chlorine gas ( Cl ₂ ) and other disadvantages, such as in the case of the slaughterhouse mentioned above, the chloride ion concentration is 200 mg / L or less, which is the water quality standard of the Waterworks Law, This method is not suitable for applications where it is desired to produce available treated water at the lowest possible cost.

Japanese Patent Laid-Open No. 11-099391 Japanese Patent Laid-Open No. 10-085755 JP 2002-205070 A Japanese Patent Application Laid-Open No. 09-174052 JP 2008-055317 A

The present invention has been made to solve the above-described problems, and provides a chloride ion removing apparatus that can obtain treated water that can be used as food production water or drinking water at low cost. Specifically, not only the chloride ion concentration of the treated water obtained is 200 mg / L or less, which is the water quality standard of the Waterworks Law, but also the introduction and maintenance costs can be reduced, and the total amount of treated water added Provides a chloride ion removal device that can take out the equivalent amount of water as treated water, does not discharge chloride ion concentrated water, does not generate a large amount of chlorine gas (Cl ₂ ), and does not color the treated water To do. It is also an object of the present invention to provide a chloride ion removal method that can be suitably performed using this chloride ion removal apparatus.

Above-mentioned problems, the chloride ion ^- (Cl ^-) chloride ions from the process water containing (Cl) a chloride ion removing device for removing the inner tank for containing water to be treated, A wall or bottom of the inner tank, comprising an outer tank for immersing immersion water for immersing the inner tank, an electrode disposed in the immersion water in the outer tank, and a power source for applying a DC voltage to the electrode At least a portion of the electrode is formed by a microporous film that transmits chloride ions (Cl ⁻ ) and does not transmit silver chloride (AgCl), and at least an anode of the electrodes is formed by silver (Ag), and the microporous Provided is a chloride ion removing device characterized in that chloride ions (Cl ⁻ ) that have moved out of the inner tank through a conductive film become silver chloride (AgCl) at the anode and precipitate in the immersion water. It is solved by.

The chloride ion removing apparatus of the present invention is configured to pass through chloride ions (Cl ⁻ ) but not through silver chloride (AgCl), and from inside the inner tank to outside the inner tank through a large number of fine pores formed in the microporous film. The chloride ions (Cl ⁻ ) that have moved to (in the outer tank) can be combined with silver ions (Ag ⁺ ) eluted from the anode to form silver chloride (AgCl). Silver chloride (AgCl) produced at the anode is hardly ionized in water and has a specific gravity greater than that of water, and therefore precipitates in the immersion water in the outer tank. The water to be treated in the inner tank is lowered until its chloride ion concentration becomes a predetermined value or less, and then substantially the entire amount is taken out as treated water. As will be described later, the chloride ion removing apparatus of the present invention can sufficiently reduce the chloride ion concentration of the treated water to be 200 mg / L or less, which is the water quality standard of the Waterworks Law. Further, chlorides has been moved to the inner tank out of the ion (Cl ^-) Most, because in combination with silver (Ag) to form the anode becomes silver chloride (AgCl), toxic chlorine gas (Cl ₂₎ Occurrence can also be suppressed.

Incidentally, chlorides has been moved to the inner tank out of ions ^- when accumulate in immersion water, chloride ion (Cl) (Cl ^-) is less likely to diffuse into the inner tank outside the chloride ion concentration in the water to be treated May not drop. However, in the chloride ion removing apparatus of the present invention, chloride ions (Cl ⁻ ) can be precipitated in the immersion water as silver chloride (AgCl) that is hardly soluble in water. Even after the removal of chloride ions (Cl ⁻ ), it does not increase almost, but in some cases it decreases. For this reason, the chloride ion removing apparatus of the present invention does not generate chloride ion concentrated water in which chloride ions (Cl ⁻ ) are concentrated, and even if the immersion water is reused many times, There is also an advantage that the reduction rate of the product ion concentration can be maintained. From silver chloride (AgCl) precipitated in the immersion water, silver (Ag) can be recovered by various methods known in the art. The recovered silver (Ag) can be molded and reused as an anode. You can also This not only prevents waste, but also reduces the cost of obtaining the electrodes.

In the chloride ion removing apparatus of the present invention, the immersion water is colored purple by the removal of chloride ions (Cl ⁻ ), but the immersion water and the water to be treated do not pass silver chloride (AgCl). Since the water is partitioned by the conductive film, the water to be treated is not colored, and transparent treated water can be taken out. Thus, the chloride ion removing apparatus of the present invention has various advantages, and can produce treated water that can be used as food production water or drinking water at low cost.

In the chloride ion removing apparatus of the present invention, the microporous film used to form at least a part of the wall or bottom of the inner tank permeates chloride ions (Cl ⁻ ) and transmits silver chloride (AgCl). The type is not particularly limited as long as it does not pass through. However, it is preferable to use a film (cellophane) made of viscose rayon as the microporous film in view of suppressing the introduction cost and maintenance cost of the chloride ion removing device and considering availability. The price of cellophane varies depending on the thickness of the cellophane, but even a thicker one (about 50 μm thick) is very inexpensive at 30-50 yen / m ² . The cellophane commercially available, surface treatment is not subjected ordinary cellophane (PT), there are two types of moisture cellophane proof process has been applied to the surface (MST), chloride ion ^- transmit (Cl) Any of these can be employed, but usually cheaper ordinary cellophane is used.

In the chloride ion removing apparatus of the present invention, the distance between the anode and cathode of the electrode varies depending on the dimensions of the electrode, the voltage applied thereto, the electric conductivity of the immersion water, and the like, and is not particularly limited. However, if the distance between the anode and the cathode is too narrow, the anode and the cathode are easily brought into contact with each other due to vibrations generated in the chloride ion removing device, which may make it difficult to install the electrodes. For this reason, although depending on the scale of the chloride ion removing device (anode and cathode dimensions), the distance between the anode and the cathode is usually set to 1 mm or more. The distance between the anode and the cathode is preferably 2 mm or more, and more preferably 3 mm or more. On the other hand, if the distance between the anode and the cathode is too wide, the effect of removing chloride ions (Cl ⁻ ) is expected to decrease. For this reason, the interval between the anode and the cathode is usually set to 50 mm or less. The distance between the anode and the cathode is preferably 30 mm or less, and more preferably 20 mm or less.

In the chloride ion removing apparatus of the present invention, the number of the electrodes is not particularly limited, but a plurality of sets are preferably provided. As a result, the ability to remove chloride ions (Cl ⁻ ) can be further increased, and a large amount of treated water can be produced from a large amount of treated water. The specific number of electrodes is appropriately set in consideration of the amount of water to be treated and the chloride ion concentration, the target chloride ion concentration of the treated water, the dimensions of the electrodes, and the like.

In the chloride ion removing apparatus of the present invention, the microporous film may be arranged in a single layer, but it is preferable to arrange it in multiple layers. Thereby, a microporous film can be made hard to damage. As will be described later, it has been confirmed that even if multiple microporous films are arranged, the effect of removing chloride ions (Cl ⁻ ) is hardly affected. The number of the microporous films to be stacked is appropriately set in consideration of the thickness of the microporous film, the dimensions of the inner tank, the amount of water to be treated, and the like.

As described above, according to the present invention, it is possible to provide a chloride ion removing apparatus that can obtain treated water that can be used as food production water or drinking water at low cost. In other words, not only can the chloride ion concentration of the treated water obtained be 200 mg / L or less, which is the water quality standard of the Waterworks Law, but also the introduction and maintenance costs can be reduced, corresponding to the total amount of treated water added. To provide a chloride ion removing device that can take out a large amount of water as treated water, does not discharge chloride ion concentrated water, does not generate a large amount of chlorine gas (Cl ₂ ), and does not color treated water. It becomes possible. It is also possible to provide a chloride ion removal method that can be suitably performed using this chloride ion removal apparatus.

It is explanatory drawing explaining the principle of the chloride ion removal apparatus of this invention. FIG. 3 is a view showing a chloride ion removing device used in Experiment 1. FIG. 5 is a diagram showing a chloride ion removing device used in Experiment 2. FIG. 5 is a view showing a chloride ion removing apparatus of the present invention used in Experiment 3. FIG. 6 is a view showing a chloride ion removing apparatus of the present invention used in Experiment 4. 6 is a view showing a chloride ion removing apparatus of the present invention used in Experiment 5. FIG. FIG. 6 is a view showing a chloride ion removing device used in Experiment 6. FIG. 10 is a view showing a chloride ion removing device used in Experiment 7. 10 is a view showing a chloride ion removing device used in Experiment 8. FIG. FIG. 10 is a view showing a chloride ion removing device used in Experiment 9. 6 is an exploded perspective view showing a chloride ion removing device used in Experiment 10. FIG.

Hereinafter, preferred embodiments of the chloride ion removing apparatus of the present invention will be described in more detail with reference to the drawings. FIG. 1 is an explanatory view for explaining the principle of the chloride ion removing apparatus of the present invention. FIG. 1 schematically shows the reaction that occurs in each part for easy understanding. As shown in FIG. 1, an apparatus for removing chloride ions of the present invention comprises an inner tank for containing treated water containing chloride ions (Cl ⁻ ), and an outer tank for containing immersion water for immersing the inner tank. It has a tank, an electrode arranged in the immersion water in the outer tank, and a power source for applying a DC voltage to the electrode.

The inner tank is composed of a shape-retaining material in which a mesh material is formed in a bowl shape and a microporous film attached to the shape-retaining material. The microporous film is a viscose rayon formed into a film (cellophane). The microporous film may be pasted so as to form only a part of the wall or bottom of the inner tank, but in the chloride ion removing apparatus of this embodiment, substantially the entire wall and bottom of the inner tank. It is pasted over. As a result, the chloride ion (Cl ⁻ ) in the inner tank can be easily moved out of the inner tank, and the removal effect of chloride ions (Cl ⁻ ) can be further enhanced.

  By the way, if the inner tank has a large capacity and a large amount of water to be treated is put inside, the cellophane forming the wall and bottom may be broken by water pressure. However, if the water level of the treated water and the water level of the immersion water are kept at the same level, the pressure applied from the treated water to the inner surface of the cellophane and the pressure applied from the immersion water to the outer surface of the cellophane should be approximately equal. Therefore, even if a large amount of water to be treated is put in the inner tank, the cellophane is not broken by the water pressure.

The electrode is composed of an anode connected to the positive electrode of the power source and a cathode connected to the negative electrode. As a material for forming the electrode, graphite (C) and metal are generally used. However, in the chloride ion removing apparatus of the present invention, when the anode is formed of graphite (C), a large amount of chlorine gas (Cl ₂ ) is generated from the anode, so that the graphite (C) forms the anode. It is unsuitable as a material. Thus, material for forming the anode, the chloride ion (Cl ^-) combines with to form a sparingly soluble chlorides in water a metal (thallium (Tl), copper (Cu), lead (Pb), silver ( Ag) and gold (Au)).

However, among these metals, except for silver (Ag), the chloride itself or the generated chloride is toxic or very expensive, and is not suitable for practical use. For this reason, in the chloride ion removing apparatus of the present invention, silver (Ag) is adopted as the anode material. On the other hand, the material of the cathode is not particularly limited as long as the substance itself is toxic or does not generate harmful substances by reacting with immersion water, but depending on the electrical conductivity of the material adopted for the cathode, chloride ion (Cl ^-) changes the effect of removing is observed.

The shapes of the anode and the cathode are not particularly limited and vary depending on the amount of water to be treated and the chloride ion concentration. Considering only the efficient removal of chloride ions (Cl ⁻ ) in the immersion water, it is preferable that the anode and the cathode have a complicated shape so that the surface area per unit volume is as large as possible. However, if the anode and cathode are too complex, the silver chloride (AgCl) produced at the anode will not settle but will remain attached to the anode, thereby preventing the elution of silver ions (Ag ⁺ ) from the anode. As a result, the effect of removing chloride ions (Cl ⁻ ) may be reduced, and chlorine gas (Cl ₂ ) may be easily generated at the anode. Moreover, there is a possibility that the molding cost of the electrode increases. For this reason, the shapes of the anode and the cathode are determined in consideration of the difficulty of adhesion of silver chloride (AgCl) and cost effectiveness. In the chloride ion removing apparatus of this embodiment, the anode and the cathode are both cylindrical. Adhesion of silver chloride (AgCl) can also be prevented by providing stirring means such as a stirrer (not shown) in the outer tank.

Although the distance between the anode and the cathode varies depending on the dimensions of the electrode and the voltage applied to the electrode, as will be described later in Experiment 6, if the distance between the anode and the cathode is too narrow, chloride ions (Cl ^-) which may adversely affect the removal of. For this reason, the distance between the anode and the cathode is usually 1 mm or more, preferably 2 mm or more, more preferably 3 mm or more. On the other hand, even if the distance between the anode and the cathode is too wide, the removal amount of chloride ions (Cl ⁻ ) decreases. For this reason, the distance between the anode and the cathode is usually 20 mm or less, preferably 15 mm or less, more preferably 10 mm or less. In the configuration adopted in Experiments 4 to 6 described later, about 5 mm is optimal.

Subsequently, the principle of the chloride ion removing apparatus of the present invention will be described. When chloride ions (Cl ⁻ ) are removed by the chloride ion removing apparatus of the present invention, it is considered that reaction 1 occurs on the anode side and reaction 2 occurs on the cathode side, as shown in FIG. Hereinafter, reactions 1 and 2 will be sequentially described.

[Reaction 1]
The chemical reaction formula of Reaction 1 is shown below.

In the chloride ion removing apparatus of the present invention, since the anode is formed of ionized silver (Ag), electrons (e ⁻ ) separated from anions such as chloride ions (Cl ⁻ ) in the immersion water serve as current carriers. Instead, the electrons (e ⁻ ) separated from the silver (Ag) forming the anode serve as current carriers. Silver ions (Ag ⁺ ) separated from the electrons (e ⁻ ) and eluted in the immersion water are combined with chloride ions (Cl ⁻ ) in the immersion water, and are precipitated into the immersion water as silver chloride (AgCl). This is supported by the fact that silver chloride (AgCl) precipitated in immersion water (experimented water in Experiments 2 and 6-9) in experiments 2 to 9 described later using silver (Ag) as the anode. It was. The chloride ion removing apparatus of the present invention mainly removes chloride ions (Cl ⁻ ) that have moved from the treated water in the inner tank to the immersion water outside the inner tank through cellophane, by this reaction 1. The chloride ion concentration of treated water is reduced.

  By the way, silver (Ag) can be recovered from silver chloride (AgCl) precipitated in the immersion water. There are several methods for recovering silver (AgCl) from silver chloride (AgCl). For example, by igniting silver chloride (AgCl) or by adding water and iron powder to silver chloride (AgCl). Examples include a method of filtering the obtained slurry. The recovered silver can be reused as a material for molding the anode.

[Reaction 2]
The chemical reaction formula of Reaction 2 is shown below.

This reaction 2 mainly occurs on the cathode side. There are metal ions such as sodium ions (Na ⁺ ) and magnesium ions (Mg ²⁺ ) in the immersion water, but these metal ions have a large tendency to ionize and hardly receive electrons (e ⁻ ) from the cathode. For this reason, water molecules (H ₂ O) in the immersion water receive electrons (e ⁻ ) from the cathode and generate hydrogen (H ₂ ) and hydroxide ions (OH ⁻ ).

Subsequently, the following experiments 1 to 10 were performed in order to confirm the effect of removing chloride ions (Cl ⁻ ) by the chloride ion removing apparatus of the present invention and other effects. Hereinafter, Experiments 1 to 10 will be sequentially described. FIGS. 2-11 is the figure which showed the chloride ion removal apparatus used for experiment 1-10, respectively.

[Experiment 1 (comparative example)]
First, in combination with cellophane and electrolysis treatment water of chloride ion (Cl ^-) in order to know to be cleared to what extent, as shown in FIG. 2, an anode and both cathode graphite (C When the electrode formed in step 1) was placed in immersion water and energized for 1 hour, it was investigated how the chloride ion concentration of treated water and immersion water changed (Experiment 1).

The conditions and results of Experiment 1 are shown in Tables 1 and 2 below.

In Experiment 1, the chloride ion concentration of the immersion water before the start was 185 mg / L, which was equal to the chloride ion concentration of the water to be treated. The product ion concentration decreased. This is presumably because chloride ions (Cl ⁻ ) in the immersion water passed electrons (e ⁻ ) to the anode and became chlorine gas (Cl ₂ ). This is supported by the fact that in Experiment 1 bubbles were generated from the anode and a very strong chlorine odor was felt, and no precipitate was found in the immersion water. However, in Experiment 1, the difference in the chloride ion concentration of the water to be treated before the start and when 1 hour passed was as small as 20 mg / L, which was not necessarily sufficient.

[Experiment 2 (comparative example)]
Then, when performing electrolysis to form an anode of silver (Ag), the water to be treated in the chloride ion (Cl ^-) in order to know to be cleared to what extent, the apparatus shown in FIG. 3 We investigated how the chloride ion concentration of the water to be treated changed when using the (test 2). Experiment 2 was performed for each of the case where the cathode was formed from silver (Ag) and the case where the cathode was formed from graphite (C). In Experiment 2, the treated water was put directly into the outer tank without using cellophane.

The conditions and measurement results of Experiment 2 are shown in Tables 3 to 5 below.

In Experiment 2, when both the anode and the cathode were formed of silver (Ag), as shown in Table 4 above, the chloride ion concentration of the water to be treated was reduced by about 100 mg / L, and only the anode was silver ( When formed with Ag), as shown in Table 5 above, the chloride ion concentration of the water to be treated decreased by about 111 mg / L. From this, it can be seen that the configuration adopted in Experiment 2 is superior to the configuration adopted in Experiment 1 in terms of removing chloride ions (Cl ⁻ ).

In Experiment 2, no bubbles were generated from the anode, and no chlorine odor was felt. In the water to be treated, a white and free-flowing material (at the time of drying) was precipitated. This substance was confirmed to be silver chloride (AgCl) from the fact that it was dissolved by aqueous ammonia and the results of a separate X-ray analysis experiment. From this, it is considered that in Experiment 2, chloride ions (Cl ⁻ ) in the immersion water were mainly removed by the above-described reaction 1. However, both the case where both the anode and the cathode are formed of silver (Ag) and the case where only the anode is formed of silver (Ag), the water to be treated was colored in a light purple color. It is difficult to use the treated water as food production water or drinking water.

[Experiment 3 (Example)]
Then, in addition to dialysis with cellophane, when performing electrolysis to form an anode of silver (Ag), the water to be treated in the chloride ion ^- to see if it is removed to what extent (Cl) In addition, it was investigated how the chloride ion concentration of the water to be treated and the immersion water changed when the apparatus shown in FIG. 4 was used (Experiment 3). Experiment 3 was performed for each of a case where the cathode was formed of silver (Ag) and a case where the cathode was formed of graphite (C).

The conditions and results of Experiment 3 are shown in Tables 6 to 8 below, respectively.

In Experiment 3, when both the anode and cathode were formed of silver (Ag), as shown in Table 7 above, the chloride ion concentration of the water to be treated was reduced by about 86 mg / L, and only the anode was silver ( When formed with Ag), as shown in Table 8 above, the chloride ion concentration of the water to be treated decreased by about 92 mg / L. Compared with the result of Experiment 2, the removal amount of chloride ion (Cl ⁻ ) was slightly decreased, but even in Experiment 3, a considerable amount of chloride ion (Cl ⁻ ) could be removed. In Experiment 3, the immersion water was colored in a light purple color that was cloudy, but the water to be treated was not colored and remained transparent.

[Experiment 4 (Example)]
In Experiment 3, tap water with a low chloride ion concentration was used as immersion water, but depending on the location where the chloride ion removal device is used, water with a low chloride ion concentration cannot always be obtained. Moreover, if the water to be treated can be used as immersion water, it is possible to save water bills. For this reason, in the chloride ion removing apparatus of the present invention, whether the chloride ion concentration of the water to be treated is lowered even if the chloride ion concentration of the immersion water is increased to the same level as the chloride ions of the water to be treated. In order to confirm the above, when the apparatus shown in FIG. 5 was used, it was examined how the chloride ion concentration of the water to be treated and the immersion water changed (Experiment 4).

The conditions and results of Experiment 4 are shown in Tables 9 and 10 below.

In Experiment 4, the chloride ion concentration of the water to be treated was about 80 mg / L after 1 hour, as shown in Table 10 above, even though the chloride ion concentration of the immersion water was high before the start of the experiment. Has also declined. Compared with the results of Experiment 3, the removal effect of chloride ions (Cl ⁻ ) was somewhat reduced, but an excellent removal effect was still recognized. As in Experiment 3, no bubbles were generated from the anode, no odor of chlorine was felt, silver chloride (AgCl) was precipitated in the immersion water, and no color was seen in the treated water. It is. From the results of Experiment 4, it was found that the chloride ion removing apparatus of the present invention can produce food production water and drinking water even when the chloride ion concentration of immersion water is high.

[Experiment 5 (Example)]
In Experiments 3 and 4, cellophane was placed in a single layer, but cellophane is never strong and may be damaged. As a countermeasure, cellophane can be arranged in multiple layers. In this case, it is expected that the removal amount of chloride ions (Cl ⁻ ) will be reduced. Therefore, in the chloride ion removing apparatus of the present invention, in order to check whether the removal amount of chloride ions (Cl ⁻ ) is maintained even when cellophane is arranged in multiple layers, the apparatus shown in FIG. We investigated how the chloride ion concentration of treated water and immersion water changed when used (Experiment 5).

The conditions and results of Experiment 5 are shown in Tables 11 and 12 below.

In Experiment 5, despite the fact that cellophane was doubly arranged, the chloride ion concentration of the water to be treated was reduced by about 92 mg / L as shown in Table 12 above, and cellophane was arranged in a single layer. Results similar to those in Experiment 3 were obtained. From this, it is presumed that even if cellophane is arranged in multiple layers, the removal amount of chloride ions (Cl ⁻ ) is hardly affected. Cellophane is very easy to break, and once it breaks, the water to be treated becomes colored.

[Experiment 6 (comparative example)]
In Experiments 2 to 5, the distance between the anode and the cathode was 5 mm. However, if this interval is widened, it is expected that the removal amount of chloride ions (Cl ⁻ ) will decrease because the moving distance of the electrolyte in the immersion water becomes longer. In order to confirm whether this prediction was correct, as shown in FIG. 7, the change in the chloride ion concentration of the water to be treated was examined by increasing the distance between the anode and the cathode (Experiment 6). In Experiment 6, the spacing of the anode and cathode chloride ion (Cl ^-) for it know even effect on the removal of, without using the inner tank, while putting the water to be treated in the outer tub directly, inner Even when a tank is used, it is considered that the same experimental results can be obtained except for the presence or absence of coloring of water to be treated. This also applies to the experiments 7 to 9 described later.

The conditions and results of Experiment 6 are shown in Tables 13 to 15 below.

In Experiment 6, as shown in Tables 14 and 15 above, the chloride ion concentration of the water to be treated decreased only by about 24 to 40 mg / L, and it can be said that the removal amount of chloride ion (Cl ⁻ ) is so large. Absent. In the electrolysis method, the reaction is continued by moving the electrolyte in the solution (immersion water) to neutralize between the positive charge accumulated anode and the negative charge accumulated cathode. However, if the distance between the anode and the cathode is widened, the moving distance of the electrolyte becomes long, so the removal amount of chloride ions (Cl ⁻ ) seems to have decreased. In Experiment 6, the stirrer was stirred with a stirrer placed on the inner bottom of the outer tank, but it seems that the stirring of the stirrer cannot sufficiently assist the movement of the electrolyte.

From the above results, better to reduce the distance between the anode and cathode, chloride ion when it was found that is advantageous with respect to the removal, too much narrower, (Cl ^{- -)} chloride ion (Cl) As described above, since it is difficult to install the electrode, it is expected that the construction of the chloride ion removing device will take time. Spacing of the anode and cathode, the size and the electrode, etc. but the voltage applied thereto, chloride ion (Cl ^-) Considering the ease of construction and effect of removing, about 5~10mm is optimum Seem.

[Experiment 7 (comparative example)]
In Experiments 2 to 6, the dimensions and shape of the anode and cathode were unified as a cylindrical shape having a diameter of 1 mm and a length of 15 mm. However, the size and shape of the anode and cathode are expected to affect the removal amount of chloride ions (Cl ⁻ ). In order to confirm the extent of this effect, as shown in FIG. 8, the size of the electrode was increased and the change in the chloride ion concentration of the water to be treated was examined (Experiment 7).

The conditions and results of Experiment 7 are shown in Tables 16 and 17, respectively.

In Experiment 7, as shown in Table 17 above, the chloride ion concentration of the water to be treated was reduced by 231 mg / L. From this, it was found that the removal amount of chloride ions (Cl ⁻ ) increases when the size of the electrode is increased. However, although the electrode used in Experiment 7 is approximately 30 times the surface area compared to the electrode used in Experiment 2 under the same conditions except for the dimensions and shape of the electrode, chloride ions (Cl ⁻ ) The removal amount has not increased so much. From this, it seems that the surface area and weight of the electrode and the removal amount of chloride ions (Cl ⁻ ) have a positive correlation, but do not have a proportional relation.

[Experiment 8 (comparative example)]
In Experiments 2-7, the number of anodes and cathodes was unified by one. However, the number of electrodes is also expected to affect the removal effect of chloride ions (Cl ⁻ ). In order to confirm the extent of this effect, as shown in FIG. 9, the number of electrodes was increased and the change in the chloride ion concentration of the water to be treated was examined (Experiment 8).

The conditions and results of Experiment 8 are shown in Tables 18 to 20 below.

In Experiment 8, as shown in Tables 19 and 20, the chloride ion concentration of the water to be treated is decreased by 140 to 216 mg / L. Compared with Experiment 2 under the same conditions except for the number of electrodes, the removal amount of chloride ions (Cl ⁻ ) and the number of electrodes seem to have a positive correlation, if not proportional. Further, in Experiment 8, taking into account the movement of the electrolyte in the water to be treated has been connected to the electrodes in parallel, even when connected in this way the electrodes in parallel, chloride ion (Cl ^-) removal of I also found it possible. From this, it can be inferred that the removal effect of chloride ions (Cl ⁻ ) can be further enhanced by increasing the number of electrodes without arranging chloride ion removal devices in multiple stages.

[Experiment 9 (comparative example)]
Next, as shown in FIG. 10, the change in the chloride ion concentration of the water to be treated was examined by increasing the number of electrodes and increasing the number of the electrodes (Experiment 9).

The conditions and results of Experiment 9 are shown in Tables 21 and 22 below, respectively.

In Experiment 9, as shown in Table 22, the chloride ion concentration in the water to be treated 262 mg / L is also reduced, chloride ion (Cl ^-) removal of the cases of the experimental 7,8 More than that. Incidentally, the results of experiments 7, 8, rather than a few using large electrodes, better to use many small electrodes, chloride ion (Cl ^-) removal of but is expected to be many, chloride ion Considering the time required for the construction of the removing device and the replacement of the electrodes, it is preferable to keep the number of electrodes to about several pairs.

[Experiment 10 (Example)]
In Experiments 1 to 9, the amount of water to be treated and immersion water was as small as 75 to 200 ml. However, in putting the chloride ion removing apparatus of the present invention into practical use, it is several tens of kg or more, and in some cases, several It seems that it is necessary to treat more than tons of treated water at once. For this reason, even when a large amount of water to be treated is used, it is necessary to confirm whether or not the chloride ion removing device of the present invention has an effect of removing chloride ions (Cl ⁻ ). Therefore, a large amount of water to be treated was placed in a large chloride ion removal device, and changes in the chloride ion concentration of the water to be treated were examined (Experiment 10).

  Experiment 10 was performed using the chloride ion removing apparatus shown in FIG. In the chloride ion device shown in FIG. 11, a total of four sets of electrodes are arranged near the four corners of the outer tank. The distance between the anode and the cathode of each electrode is kept constant by insulating spacers provided at the upper and lower ends thereof. In the inner tank, the front surface, the back surface, the right side surface, the left side surface and the bottom surface are formed of a microporous film (cellophane) made of viscose rayon. Near the bottom of the outer tank, there is provided a silver chloride outlet for taking out silver chloride (AgCl) precipitated in the outer tank. The inner bottom surface of the outer tub is provided with an inclination or a recess so that the vicinity of the silver chloride outlet is lowest. For this reason, silver chloride (AgCl) precipitated in the outer tank can be easily taken out.

The conditions and results of Experiment 10 are shown in Tables 23 and 24 below.

In Experiment 10, the chloride ion concentration of the water to be treated before the start of the experiment was set to a value higher than the upper limit of 250 mg / L assumed when groundwater was used as the water to be treated. As shown in 24, although the chloride ion removal time was as short as 30 minutes, it could be reduced to 200 mg / L or less, which is the water quality standard of the Waterworks Law. From this, it was found that the chloride ion removing apparatus of the present invention can sufficiently remove chloride ions (Cl ⁻ ) even when the amount of water to be treated is large.

Moreover, it turned out that the chloride ion density | concentration of immersion water hardly raises and immersion water can be reused also in the next process. Furthermore, no odor of chlorine was felt, and generation of chlorine gas (Cl ₂ ) could not be confirmed. From the above, it was found that the chloride ion removing apparatus of the present invention can be sufficiently put into practical use even in facilities that require a large amount of water, such as slaughterhouses.

Claims (7)

A chloride ion removing device for removing chloride ions from water to be treated containing chloride ions,
An inner tank for containing treated water, an outer tank for containing immersion water for immersing the inner tank, an electrode arranged in the immersion water in the outer tank, and a power source for applying a DC voltage to the electrode And at least a part of the wall or bottom of the inner tank is formed of a microporous film that transmits chloride ions and does not transmit silver chloride, and at least an anode of the electrodes is formed of silver, A chloride ion removing apparatus characterized in that chloride ions that have moved out of the inner tank through a porous film become silver chloride at the anode and precipitate in the immersion water.   The chloride ion removing apparatus according to claim 1, wherein the microporous film is a film made of viscose rayon.   The chloride ion removing apparatus according to claim 1 or 2, wherein a distance between an anode and a cathode of the electrode is 1 to 20 mm.   The chloride ion removing apparatus according to claim 1, wherein a plurality of sets of the electrodes are provided.   The chloride ion removing apparatus according to any one of claims 1 to 4, wherein the microporous film is arranged in multiple layers. A method of removing chloride ions for removing chloride ions from water to be treated containing chloride ions,
Water to be treated is put into an inner tank formed of a microporous film in which at least a part of the wall or bottom part permeates chloride ions and does not permeate silver chloride, and the inner tank is immersed in immersion water in the outer tank Then, by placing an electrode having at least an anode formed of silver in immersion water and applying a DC voltage to the electrode, chloride ions that have moved out of the inner tank through the microporous film are chlorinated at the anode. A method for removing chloride ions, characterized by precipitating as silver in immersion water.   The method for removing chloride ions according to claim 6, wherein silver is recovered from silver chloride precipitated in the immersion water, and the recovered silver is molded and reused as the anode.

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