Optimized adsorption filtration method in combination of spring-like filter and powder adsorbent

Abstract

To provide an adsorbent of which optimization of a specific gravity and an average particle diameter can be achieved, and a synthesis method and an adsorption filtration method thereof.SOLUTION: An adsorption filtration method according to one aspect of the present invention is characterized in that an adsorbent, of which an average particle diameter falls within a range of 10 μm or more and 100 μm or less and a true specific gravity falls within a range of 1 g / cm3 or more and 3 g / cm3 or less, is directly coated on a spring-like filter. Further, an adsorption filtration method according to another aspect of the present invention is characterized in that a filtration assistant with a prescribed size has been previously coated on the spring-like filter, and further, an adsorbent, of which an average particle diameter falls within a range of 10 μm or more and 100 μm or less and a true specific gravity falls within a range of 1 g / cm3 or more and 3 g / cm3 or less, is coated thereon.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adsorptive filtration method that is optimized in the combination of a spring filter and a powder adsorbent. [Background technology]

[0002] Conventional adsorption filtration technology for water treatment involves filling a cylindrical container with granular adsorbent material, for example, 0.3 mm or larger in size, and passing the target water through it from one direction. With this method, the contact efficiency between the granular adsorbent and the adsorbed substance is low, resulting in a low dynamic adsorption amount and making it impossible to perform high-speed treatment.

[0003] In another example, a method may be used in which a powder adsorbent is mixed with the target water and then the powder adsorbent is separated from the treated water by coagulation and sedimentation, etc. This method requires even more time than the previous method to adsorb the adsorbed substances, resulting in excessively large treatment equipment and making it unsuitable for large-volume water treatment.

[0004] Various techniques have been investigated for removing radioactive materials. For example, Non-Patent Document 1 listed below describes the adsorption of radioactive cesium by ammonium phosphomolybdate.

[0005] Meanwhile, the present inventors have previously proposed a spring filter system in Patent Document 1 below, which includes a spring filter and an adsorbent that adsorbs dissolved impurities, in order to adsorb dissolved impurities. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6695542 [Non-patent literature]

[0007] [Non-Patent Document 1] https: / / unit.aist.go.jp / georesenv / information / 20150917 / TechRep_Cs_Monitoring_Water.pdf Summary of the Invention [Problem to be solved by the invention]

[0008] However, the technology described in Patent Document 1 uses a filter aid containing an adsorbent for adsorbing boron, and there is still room for improvement, such as the need to optimize the adsorbent when adsorbing radioactive substances. From the viewpoint of maximizing the efficiency of adsorption filtration, we investigated an adsorption filtration method using a combination of a spring filter and a powder adsorbent, and found the optimal conditions.

[0009] On the other hand, when using a spring filter, the specific gravity can be an important factor because the filter aid is placed around the spring filter by utilizing the flow of liquid. However, ammonium phosphomolybdate (trihydrate) has a specific gravity of 3.2 g / cm 3 , ammonium tungsten phosphate (trihydrate) has a specific gravity of 5.1 g / cm 3 Therefore, adjustment is necessary for use as a filter aid in a spring filter system that adsorbs radioactive materials. In addition, the particle size of the filter aid is also very important, and the balance of not only the specific gravity but also the average particle size is very important.

[0010] In view of the above, an object of the present invention is to provide an adsorbent capable of optimizing the specific gravity and average particle size, a method for synthesizing the same, and an adsorptive filtration method. [Means for solving the problem]

[0011] The adsorptive filtration method according to one aspect of the present invention that solves the above-mentioned problems is to adsorb particles having an average particle size of 10 μm or more and 100 μm or less and a true specific gravity of 1 g / cm on a spring-shaped filter. 3 More than 3g / cm 3The adsorbent material falling within the following range is directly coated.

[0012] In addition, an adsorptive filtration method according to another aspect of the present invention comprises coating a spring-shaped filter with a filter aid of a predetermined size in advance, and further coating the filter aid with a mean particle size of 10 μm or more and 100 μm or less and a true specific gravity of 1 g / cm 3 More than 3g / cm 3 The adsorbent material is coated in the following range.

[0013] Furthermore, an adsorbent according to another aspect of the present invention that solves the above-mentioned problems is an adsorbent having seed crystals and a coating layer that coats the seed crystals, the adsorbent having an average particle size of 10 μm or more and 100 μm or less and a specific gravity of 1 g / cm 3 More than 3g / cm 3 It is in the following range:

[0014] In addition, in this respect, although not limited thereto, it is preferable that the coating layer contains a radioactive material adsorbent.

[0015] In addition, in this respect, although not limited thereto, it is preferable that the radioactive substance adsorbent is at least one of metal ferrocyanide, heteropolyacid salt, and metal phosphate.

[0016] In addition, in this respect, although not limited thereto, the seed crystals are preferably at least one of silica, aluminum, zeolite, and diatomaceous earth.

[0017] Furthermore, in this aspect, although not limited thereto, it is preferable that the coating layer is at least one of cobalt ferrocyanide, iron ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, zinc ferrocyanide, ammonium phosphotungstate, potassium phosphotungstate, ammonium phosphomolybdate, potassium phosphomolybdate, zirconium phosphate, titanium phosphate, cerium phosphate, tin phosphate, and antimony phosphate.

[0018] In addition, in this respect, although not limited thereto, it is preferable that the specific gravity of the seed crystal is lighter than the specific gravity of the coating layer.

[0019] In addition, in this respect, although not limited thereto, it is preferable that the ratio of the average particle size of the entire adsorbent to the average particle size of the seed crystals is 1.2 or more and 5 or less. [Effects of the Invention]

[0020] As described above, the present invention can provide an adsorbent capable of optimizing the specific gravity and average particle size, a method for synthesizing the same, and an adsorptive filtration method. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing a schematic cross section of an adsorbent according to an embodiment. [Figure 2] 1 is a diagram showing an outline of an adsorbent synthesis apparatus according to an embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention can be embodied in many different forms, and is not limited to the examples specifically described in the following embodiments and examples.

[0023] Fig. 1 is a diagram showing a schematic cross section of an adsorbent B according to this embodiment (hereinafter referred to as "the present adsorbent") . Specifically, the present adsorbent B is an adsorbent having seed crystals M and a coating layer C that coats the seed crystals M, and has an average particle size of 10 µm or more and 100 µm or less and a specific gravity of 1 g / cm 3 More than 3g / cm 3 It is in the following range:

[0024] This configuration allows the present adsorbent B to be an adsorbent capable of optimizing the specific gravity and average particle size. Specifically, the present adsorbent B is useful in filtration techniques using liquids, and by adjusting the specific gravity of the adsorbent according to the specific gravity of the liquid used, its buoyancy can be adjusted and suitable adsorption performance can be maintained. Furthermore, the present adsorbent B is very important in devices such as spring-type filter devices that suction and use the adsorbent itself as a filter aid. This point will be described in more detail later.

[0025] First, the present adsorbent B contains seed crystals M therein. Here, the seed crystals M are a substance that serves as the core of the adsorbent and are used to adjust the specific gravity. The seed crystals M are substances present in the adsorbent, and the seed crystals M themselves may be composed of a material that has adsorption properties, or may not have adsorption properties. If adsorption properties are not taken into consideration, an extremely wide variety of materials can be selected, but it is preferable that the material does not react with the treatment liquid that is to be treated by the present adsorbent B.

[0026] Furthermore, in the present adsorbent B, as is clear from the above description, it is preferable that the specific gravity of the seed crystals M is lighter than the specific gravity of the coating layer C.

[0027] Furthermore, in the present adsorbent B, the material of the seed crystal M is not limited, but it is preferable that the seed crystal M is at least one of silica, aluminum, zeolite, and diatomaceous earth. Using these materials makes it possible to adjust the specific gravity of the adsorbent. More specifically, for example, if the adsorbent B described below is selected as a material capable of adsorbing radioactive substances, its specific gravity will be too heavy compared to water. If the specific gravity is too heavy compared to water, for example, when adsorbent B, such as a spring-shaped filter device, is attached to the periphery of a filter as a filter aid, it becomes difficult to successfully attach it to the periphery of the filter even when using the flow of water. However, using a material such as silica in this way allows for the use of a material that is sufficiently lighter than the specific gravity of the adsorbent, which has the advantage of reducing the specific gravity of the adsorbent as a whole compared to when it is made of a coating layer itself.

[0028] The adsorbent B also has a coating layer C around the seed crystals M. The coating layer is a material having adsorption properties, and is a substance that adsorbs impurities in the target liquid to be treated.

[0029] Furthermore, although not limited thereto, the coating layer C of the present adsorbent B preferably contains a radioactive material adsorbent. More specifically, it is preferable that the coating layer C is capable of adsorbing radioactive materials dissolved in water.

[0030] Furthermore, when the coating layer C is a radioactive material adsorbent, it is preferably at least one of, but not limited to, metal ferrocyanide, heteropolyacid salt, and metal phosphate. More specifically, in the case of metal ferrocyanide, the coating layer is preferably at least one of cobalt ferrocyanide, iron ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, and zinc ferrocyanide. In addition, in the case of a heteropolyacid salt, it is preferably at least one of ammonium phosphotungstate, potassium phosphotungstate, ammonium phosphomolybdate, and potassium phosphomolybdate. In addition, in the case of a metal phosphate, it is preferably at least one of zirconium phosphate, titanium phosphate, cerium phosphate, tin phosphate, and antimony phosphate.

[0031] Based on the above, the adsorbent B has an average particle size of 10 μm or more and 100 μm or less, and a specific gravity of 1 g / cm 3 More than 3g / cm 3 The specific gravity of the material is set to be within the range below. This has the advantage that the material can be stably arranged around the spring-shaped filter of the spring-shaped filter device, and impurities in the water (including not only dissolved impurities but also undissolved impurities) can be efficiently removed. Furthermore, as is clear from the above description, if the material becomes lighter than the specific gravity of water in the water, it will float on the water surface. Therefore, the specific gravity should be 1 g / cm 3 On the other hand, if it is too heavy, it will be difficult to attach it to the periphery of the spring-shaped filter even if a water flow is formed. Therefore, it is recommended to set the weight at 3 g / cm or more. 3It is preferable to do the following:

[0032] Furthermore, from this viewpoint, although not limited thereto, it is preferable that the ratio of the average particle size of the entire adsorbent to the average particle size of the seed crystals is 1.2 or more and 5 or less. By making the ratio 1.2 or more, it becomes possible to efficiently coat the adsorbent around the seed crystals without leaving any gaps, while by making the ratio 5 or less, it becomes possible to limit the amount of the coating layer with a heavy specific gravity and keep the specific gravity within a desired range.

[0033] As described above, it is possible to provide an adsorbent capable of optimizing the specific gravity and average particle size, and a method for synthesizing the same.

[0034] Here, a specific method for synthesizing the adsorbent will be described. The adsorbent B can be synthesized by various methods, for example, a synthesis method (hereinafter referred to as "the method") using an adsorbent synthesis apparatus (hereinafter referred to as "the apparatus") 1 shown in Figure 2.

[0035] First, as shown in the figure, the apparatus 1 comprises a first container 2 for accommodating a first stock solution L1, a second container 3 for accommodating a second stock solution L2, a third container 4 for accommodating a seed crystal M, and a reaction container 5 for mixing the first stock solution L1, the second stock solution L2, and the seed crystal M and reacting the first stock solution L1 and the second stock solution L2 in the presence of the seed crystal M to precipitate a reaction product around the seed crystal M, and is also provided with a circulating mechanism 6 for removing unreacted first stock solution L1 and second stock solution L2 from the reaction container 5 and returning them to the reaction container 5.

[0036] The present apparatus 1 also includes a recovery vessel 7 for recovering the adsorbent synthesized in the reaction vessel 5.

[0037] With the above-described configuration, the present device 1 can provide an adsorbent synthesis method and an adsorbent synthesis device that can adjust the size of an adsorbent that can only form fine crystals to be optimal for the filter to be used, even if the adsorbent can only form fine crystals. The details of this will be described in detail below.

[0038] First, the present apparatus 1 has a first container 2 that contains a first stock solution L1 as described above. Here, a "stock solution" is a liquid containing a substance used for a reaction, which can precipitate a reactant by mixing with other stock solutions. Furthermore, the term "first" here is merely an ordinal number used to distinguish it from other stock solutions, and does not itself have any technical meaning.

[0039] In the present apparatus 1, the first stock solution is not limited as long as it can achieve the effects of the present invention, but is preferably at least one of cobalt chloride, ferric chloride, nickel chloride, manganese chloride, copper chloride, zinc chloride, and phosphotungstic acid, phosphomolybdic acid, zirconium chloride oxide, titanium chloride, cerium sulfate, tin chloride, and antimony chloride. However, the first stock solution is not limited as long as it can react with the second stock solution described below, and it is also possible to replace the first stock solution with the second stock solution described below.

[0040] Furthermore, as described above, the "container" in this device 1 is not limited to a specific material, and various shapes and capacities can be used as long as it is capable of containing and retaining the concentrate. While the material is not particularly limited, metals and resins are suitable. Examples of metals include stainless steel, aluminum alloys, titanium alloys, and nickel alloys, while examples of resins include, but are not limited to, polyethylene, ABS, and polytetrafluoroethylene (PTFE). Furthermore, while the term "first" is used for the container of this device 1, this is the same as the use of the term for the concentrate described above. It is merely an ordinal number used to distinguish it from other containers and does not itself have any technical meaning.

[0041] Furthermore, as described above, the present apparatus 1 has a second container 3 that contains a second stock solution L2. Here, the "stock solution" is the same as described above, and is a liquid containing a substance used for a reaction, which can precipitate a reaction product by mixing with another stock solution (specifically, the first stock solution). Furthermore, the term "second" here is merely an ordinal number used to distinguish it from other stock solutions (specifically, the first stock solution), and does not itself have any technical meaning.

[0042] In the present apparatus 1, the second stock solution is not limited as long as it can achieve the effects of the present invention. However, when the first stock solution is used in the above example, it is preferably potassium ferrocyanide and at least one of ammonium bicarbonate, potassium chloride, phosphoric acid, and sodium dihydrogen phosphate. This allows crystals to be precipitated by reacting the first and second stock solutions. That is, the adsorbent synthesized by the present apparatus 1 is preferably at least one of metal ferrocyanide, heteropolyacid, and metal phosphate. More specifically, it is preferably at least one of cobalt ferrocyanide, iron ferrocyanide, nickel ferrocyanide, manganese ferrocyanide, copper ferrocyanide, zinc ferrocyanide, ammonium phosphotungstate, potassium phosphotungstate, ammonium phosphomolybdate, potassium phosphomolybdate, zirconium phosphate, titanium phosphate, cerium phosphate, tin phosphate, and antimony phosphate.

[0043] The apparatus 1 also includes a third container 4 that contains seed crystals M. In the apparatus 1, the "seed crystals" serve as nuclei (seeds) for the growth of the reactant synthesized by the reaction between the first and second stock solutions. Examples of seed crystals for the apparatus 1 include, but are not limited to, metal powders such as aluminum and titanium, resin powders such as cellulose, glass, ceramics, silica gel, diatomaceous earth, activated carbon, and zeolite. The shape of the seed crystals is not particularly limited, but a spherical shape is a preferred example, as a uniform and regular shape is preferable. The size of the seed crystals M is also not particularly limited, but considering that the average particle size of the adsorbent is in the range of 10 μm or more assuming a spherical shape, the average particle size is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, but is not limited thereto.

[0044] Furthermore, since the seed crystals M are a substance insoluble in liquid, it is preferable that a dispersion liquid for dispersing the seed crystals M is also contained in the third container 4. The dispersion liquid allows the seed crystals M to be introduced into the reaction container 5 described below via piping or the like. The dispersion liquid here is not particularly limited, and may be an aqueous solvent such as water, or an organic solvent such as ether. This can be adjusted appropriately according to the first stock solution and the second stock solution. In other words, hereinafter, the term "seed crystals" may also refer to seed crystals dispersed in a dispersion liquid.

[0045] Furthermore, the size of the adsorbent synthesized by the present apparatus 1 is preferably an average particle size of 10 μm or more. By using a size larger than this, it is possible to match the size and specific gravity to a level that allows it to be used as a filter aid in a spring filter system. If it is smaller than this, it is not suitable as a filter aid in a spring filter system and there is a risk that it will slip through the gaps in the spring filter.

[0046] Furthermore, the present apparatus 1 includes the reaction vessel 5 as described above. Specifically, as described above, the reaction vessel 5 is used to mix the first stock solution L1, the second stock solution L2, and the seed crystals M, and to react the first stock solution L1 and the second stock solution L2 in the presence of the seed crystals M to precipitate a reaction product around the seed crystals M.

[0047] As is clear from the above description, the reaction vessel 5 of the present apparatus 1 is connected to the first vessel 2, the second vessel 3, and the third vessel 4 via pipes 9 such as a first pipe 91, a second pipe 92, and a third pipe 93, respectively, and can receive the first stock solution, the second stock solution, and the seed crystals via these pipes.

[0048] Furthermore, the reaction vessel 5 in the present device 1 has an outer shell 51 and a circulating flow forming member 52 provided inside the outer shell 51, and a circulating flow is formed inside these, causing the adsorbent to grow large.

[0049] The outer shell 51 is a member that serves as the outer shell of the reaction vessel 5. Inside this, a circulation flow is formed as described above, while adsorbents smaller than a predetermined size are once discharged to the outside, circulated, and then taken back inside to be grown again.

[0050] The shape of the outer shell 51 is not limited as long as it has the above-mentioned function, but a preferable example is one having a substantially cylindrical portion with an upper and lower base. By making it cylindrical and installing it so that the bottom is substantially parallel to the vertical direction, it is possible to form a circulating flow using gravity, which has the advantage of making it easy to adjust to this circulating flow.

[0051] Furthermore, the reaction vessel 5 of the present apparatus 1 is provided with a circulating flow forming member 52 inside the outer shell 51. As described above, the circulating flow forming member 52 is not limited as long as it can form a circulating flow inside the outer shell 51, but it is preferable that it has a cylindrical portion 521 with upper and lower through-holes (without an upper or lower bottom). By doing so, for example, an upward flow can be formed inside the cylindrical portion, and a downward flow can be formed outside it and inside the outer shell 51. As a result, a reaction product of the first raw liquid and the second raw liquid can be precipitated around the seed crystal within the circulating flow, and this precipitate can grow.

[0052] It is also preferable that a flange portion 522 is provided at the lower part of the cylindrical portion 521 of the circulating flow forming member 52 of the reaction vessel 5. The provision of this flange portion 522 has the advantage of preventing the formation of an upward flow outside the cylindrical portion 521 and enabling the formation of a stable upward flow. It is also preferable that the upper end portion of the cylindrical portion 521 is formed with a smaller diameter than the middle or bottom portion.

[0053] In addition, it is preferable that at least one of the first stock solution and the second stock solution is supplied to the inside of the cylindrical portion 521 of the circulating flow forming member 52. The cylindrical portion 521 serves as a reaction field for the first stock solution, which has the advantage of enabling efficient adsorbent synthesis. In the example shown in the figure, the first stock solution is provided inside the cylindrical portion 521 of the circulating flow forming member 52 by the first piping 91, but the second piping 92 may also be provided inside.

[0054] The third pipe 93 may be configured to be directly connected to the reaction vessel 5, or may be configured to be connected to at least one of the first pipe 91 and the second pipe 92. The third pipe 93 is used to transport the seed crystals, but the seed crystals themselves will not react even if they come into contact with only the first stock solution or only the second stock solution. Therefore, mixing the seed crystals with the first stock solution or the second stock solution before supplying them has the advantage of enabling more efficient transport and reaction. Note that, in a configuration in which a pipe supplying the solution to the inside of the cylindrical portion 521 of the circulating flow forming member 52 is provided, it is preferable that the third pipe 93 be connected to a pipe other than the pipe supplying the solution to the inside of the cylindrical portion 521.

[0055] The present device 1 also includes a circulating mechanism 6 that removes the unreacted first stock solution L1 and second stock solution L2 from the reaction vessel 5 and returns them to the reaction vessel 5 again.

[0056] Specifically, the circulating mechanism 6 is configured with a pump 61 and a fourth pipe 94 connected to this pump 61, and the fourth pipe 94 is connected to the reaction vessel 5 at two points, with one connection port 941 being an outlet for the reaction liquid and the other connection port 941 being an inlet for returning the reaction liquid via the pump 61.

[0057] Specifically, when the present apparatus 1 is installed, it is preferable that one connection port 941 is installed at the vertical upper part of the reaction vessel 5, and the other connection port 942 is installed at the vertical lower part of the reaction vessel 5. This configuration has the advantage that the reaction liquid can be introduced again into the circulating flow formed by the circulating flow forming member 52 to cause a reaction.

[0058] Furthermore, as described above, the present apparatus 1 preferably includes a collection vessel 7 for collecting the adsorbent synthesized in the reaction vessel 5. The collection vessel 7 enables collection of fully grown adsorbent. The collection vessel 7 is preferably provided with a sieve mechanism 71. By providing the sieve mechanism 71, adsorbents of a predetermined size or larger are captured by the sieve mechanism 71, while adsorbents of a smaller size are stored in the collection vessel 7 below, specifically, in the collection vessel main body 72. The adsorbents smaller than the predetermined size stored in the collection vessel main body 72 can be used as seed crystals or nuclei in the next reaction. For this reason, the collection vessel 7 may be provided with a branch pipe 95 connected to the circulation mechanism 6.

[0059] (Method for synthesizing adsorbent) The present method includes the steps of (S1) reacting a first stock solution with a second stock solution in the presence of a seed crystal to precipitate a reaction product around the seed crystal to obtain a crystallized product (hereinafter also referred to as the "crystallization step"), and (S2) classifying the crystallized product to obtain crystallized products of a predetermined size or larger as an adsorbent (hereinafter also referred to as the "sorting step").

[0060] First, this method includes a crystallization step (S1), in which the first and second stock solutions are reacted in the presence of seed crystals to precipitate a reaction product around the seed crystals, thereby obtaining a crystallized product.

[0061] In this method, it is also preferable to use the crystallized product of a predetermined size or less as the seed crystal in the crystallization step (S1). This makes it possible to further enlarge the crystallized product of a predetermined size or less. Specifically, in the crystallization step (S1), there may be cases where the seed crystal acts as a nucleus and the crystallized product covers it, but there may also be cases where minute crystallized products are generated in the reaction solution independently of the seed crystal. In such cases, these minute crystallized products themselves can also act as nuclei, and by further enlarging them, it becomes possible to obtain crystallized products larger than the predetermined size.

[0062] This method also includes a sorting step (S2). By sorting, crystallized material of a predetermined size or larger can be obtained as an adsorbent. This sorting step (S2) is assumed to be performed primarily by the collection container 7. Specifically, the adsorbent captured by the sieve mechanism 71 of the collection container 7 is an adsorbent of a predetermined size or larger, while the adsorbent that passes through the sieve mechanism and is stored in the collection container body 72 of the collection container 7 is an adsorbent of a size smaller than the predetermined size.

[0063] As a result of the above, an adsorbent of a predetermined size or larger can be synthesized, coated by the accumulation of reactants around the seed crystal, making it easy to adjust the specific gravity of the adsorbent itself. [Industrial Applicability]

[0064] The present invention has industrial applicability as an adsorbent filtration method. [Explanation of symbols]

[0065] 1...Adsorbent synthesis equipment 2. First container 3. Second container 4. Third container 5. Reaction vessel 6...Patrol mechanism M...Seed crystal L1: First stock solution L2: Second stock solution

Claims

[Request 1] On the spring-shaped filter, a particle having an average particle size of 10 μm or more and 100 μm or less and a true specific gravity of 1 g / cm ３ 3g / cm or more ３ An adsorptive filtration method in which an adsorbent within the following range is directly coated. Request 2 A spring-shaped filter is coated with a filter aid of a predetermined size in advance, and the average particle size is 10 μm or more and 100 μm or less, and the true specific gravity is 1 g / cm ３ 3g / cm or more ３ An adsorptive filtration method in which an adsorbent within the following range is coated.

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