Method for producing anionic treatment agent, method for regenerating anionic treatment agent

Abstract

To provide an anionic treatment agent that removes the disadvantages of an anionic treatment agent using a layered double hydroxide as a raw material and improves the anion exchange ability, and is suitable for inventory management.SOLUTION: An anionic treatment agent A is a product produced by mixing a layered double hydroxide 1 having anion exchange ability and a feldspar clay 2 that maintains its shape even in water by drying, and subjecting the mixture to the steps of rolling and granulating, drying, and classifying. The layered double hydroxide 1 includes a chlorine type, a carbonate type, or the like depending on the anion species contained in the layer, and when an anionic treatment of an ionic fluorine, nitrogen, or phosphorus compound is intended, it is desirable to use a chlorine type layered double hydroxide having excellent anion exchange selectivity as a raw material. The feldspar clay 2 is obtained by grinding feldspar, which is a type of a tridimensional techtosilicate containing an aluminosilicate such as an alkali metal or an alkaline earth metal as a main component, to form a powder having a size of 5 μm or less.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention is used to remove anions such as fluorine, nitrogen, and phosphorus compounds contained in surface water such as river water and lake water, well water, and domestic sewage and industrial wastewater. Method for manufacturing anionic treatment agent and regeneration method after anionic treatment It relates to this.

Background Art

[0002] As an anion treatment agent, for example, an organic solvent is added to a mixture of a hydrotalcite powder, which is a layered double hydroxide, and a polymer compound such as an aminated product of polyacrylamide, which is a binder, and kneaded. After that, a molded body formed by a granulator is dried and cured. A hydrotalcite granulated product obtained by drying and curing, or a kneaded product of the hydrotalcite powder and the binder coated as a powder layer on the surface of a core material composed of zeolite particles and dried and cured has been proposed (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the anion exchange ability of the anion treatment agent is proportional to the amount of the contained layered double hydroxide, all of the anion treatment agents in Patent Document 1 described above are produced by drying and curing a mixture of a layered double hydroxide powder and a binder on the surface of a core material composed of zeolite particles. Therefore, the core material composed of zeolite particles becomes the main component of the granulated body, and there is a problem that the anion exchange ability is limited.

[0005] In addition, in the anion treatment agent of Patent Document 1 described above, since a polymer compound such as polyacrylamide is used as a binder, it is necessary to dilute the polymer compound itself or the polymer compound as a binder with an organic solvent to a predetermined concentration. However, the organic solvent used for the dilution may elute as a permeate into the anion treatment agent. In this case, if the water treated with the anion treatment agent is used, for example, for tap water, it is highly likely to correspond to harmful organic substances such as TOC (total organic carbon) in the relevant tap water quality standards, volatile organic compounds regarded as problems in the conformity standards of tap water-related equipment and materials, and acrylic acid. Therefore, it is advisable to avoid using the polymer compound and the organic solvent used for its dilution.

[0006] Therefore, the present invention has been made by paying attention to such problems, and can improve the anion exchange ability without using a polymer compound or an organic solvent used for its dilution, and can remove the above-mentioned drawbacks of the anion treatment agent using a layered double hydroxide as a raw material. Method for manufacturing anionic treatment agent and regeneration method after anionic treatment An object of the present invention is to provide such an agent.

Means for Solving the Problems

[0007] In order to solve the above problems, the anion treatment agent according to the present invention The manufacturing method is as follows A layered double hydroxide having an anion exchange ability and Grind feldspar, which is a kind of tectosilicate with a three-dimensional structure mainly composed of aluminosilicate, into a powder with a particle size of 5 μm or less feldspar clay are mixed, subjected to rolling granulation and formed, At 300°C to 600°C After drying, it is classified to produce an anion treatment agent, which is characterized in that. In addition, the method for producing an anion treatment agent according to the present invention is to mix a layered double hydroxide having an anion exchange ability and Grind feldspar, which is a kind of tectosilicate with a three-dimensional structure mainly composed of aluminosilicate, into a powder with a particle size of 5 μm or less feldspar clay, subject them to rolling granulation and forming, and after classification At 300°C to 600°C It is dried to produce an anion treatment agent, and the raw materials removed from the forming and classification are reused, which is characterized in that. In addition, the regeneration method of the anion treatment agent according to the present invention is to mix a layered double hydroxide having an anion exchange ability and Grind feldspar, which is a kind of tectosilicate with a three-dimensional structure mainly composed of aluminosilicate, into a powder with a particle size of 5 μm or less feldspar clay, subject them to rolling granulation, At 300°C to 600°CThe anionic treatment agent is regenerated by adding a regenerant containing chloride ions to the anionic treatment agent produced by classification after drying.

Advantages of the Invention

[0008] The anionic treatment agent according to the present invention is composed of a layered double hydroxide having an anion exchange ability and Grind feldspar, which is a kind of tectosilicate with a three-dimensional structure mainly composed of aluminosilicate, into a powder with a particle size of 5 μm or less feldspar clay, which are mixed, subjected to rolling granulation to form a shape, and dried. Therefore, it does not use a core material composed of zeolite particles or the like as in the prior art. As a result, it is possible to increase the proportion of the layered double hydroxide in the granulated body, and the anion exchange ability can be improved. In addition, since it does not use a core material composed of zeolite particles or the like, a polymer compound such as polyacrylamide as a binder for the layered double hydroxide and an organic solvent for diluting the polymer compound are not required, and it is possible to reliably prevent the organic solvent from dissolving into groundwater or the like and having an adverse effect on the environment. As a result, it is possible to eliminate the limitation of the anion exchange ability, which is a drawback of the anionic treatment agent using the layered double hydroxide as a raw material, and the use of the polymer compound required for the formation of the core material and the organic solvent used for its dilution. In addition, the anionic treatment agent according to the present invention also has the advantage that it can be easily regenerated by processing the layered double hydroxide from a powder form to a granular form.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, Method for manufacturing anionic treatment agent and regeneration method of anionic treatment agent embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0011] FIG. 1 is an enlarged view showing an anion treatment agent A according to an embodiment of the present invention. As shown in FIG. 1, the anion treatment agent A is a granular material obtained by granulating a kneaded product of particles of a layered double hydroxide 1 having an anion exchange capacity and feldspar clay 2, and is a product obtained by granulating a kneaded product of the layered double hydroxide 1 and the feldspar clay 2 and performing a drying and classification operation.

[0012] (Layered double hydroxide 1) In the layered double hydroxide 1, there are chlorine type, carbonate type, etc. depending on the anion species contained in the layer. When the purpose is to treat anions of ionic fluorine, nitrogen, and phosphorus compounds proposed in the embodiments according to the present invention, it is desirable to use a chlorine type layered double hydroxide having excellent anion exchange selectivity as a raw material.

[0013] (Feldspar clay 2) In the anion treatment agent A of the embodiment according to the present invention, in order to achieve granular molding, feldspar clay 2 that can maintain its shape even in water by drying is used. Feldspar clay 2 has a composition as shown in FIG. 2, for example, and is a ground feldspar, which is a kind of tectosilicate with a three-dimensional structure mainly composed of aluminosilicates such as alkali metals and alkaline earth metals, and is in the form of powder with a particle size of 5 μm or less. In the composition shown in FIG. 2, 10 kinds are listed in descending order of proportion.

[0014] ><Manufacturing method of layered double hydroxide 1 and feldspar clay 2> Next, the manufacturing method of layered double hydroxide 1 and feldspar clay 2 when manufacturing the anion treatment agent A of the embodiment according to the present invention will be described.

[0015] (Ratio at the time of kneading layered double hydroxide 1 and feldspar clay 2) First, in the anion treatment agent A of the embodiment according to the present invention, the ratio at the time of kneading layered double hydroxide 1 and feldspar clay 2 is set to form a kneaded product at a weight ratio of 10%:90% to 90%:10%.

[0016] Regarding granulation, it is carried out by tumbling granulation, which has the advantage that all raw materials can be used by using the kneaded product as it is as granules. When granulating, when the raw material is 100%, water is added at a weight ratio of 10% to 40% so that the raw material can maintain the shape of the granules.

[0017] The granules obtained by tumbling granulation are classified with two sieves having different apertures between 0.1 mm and 2.0 mm, and the granules remaining between the two sieves are transferred to the drying process.

[0018] The fines under the sieve with a small aperture and the residue on the sieve with a large aperture generated in the classification process are ground without drying and made into powder with a particle size of 5 μm or less, so that they can be used as raw materials for the next production.

[0019] The outer part of the product generated during the production of the granulated body using feldspar clay 2 loses its formability after going through the drying process and cannot be remolded. However, in this method, since it has not gone through the drying process, there is an advantage that remolding is possible.

[0020] The granulated bodies are classified using two sieves with different apertures of 0.1 mm to 2.0 mm, and the granulated bodies remaining between the two sieves are dried at 300°C to 600°C in the drying process, and the production of the anion treatment agent A according to the embodiment of the present invention is completed. Drying increases the strength of the granules, and when used for the purpose of anion treatment dissolved in water, the shape of the granules of the anion treatment agent can be maintained even in water.

[0021] <Test on the anion exchange capacity of the anion treatment agent A> One of the advantages of the anion treatment agent A according to the embodiment of the present invention is the improvement of the anion exchange capacity. The anion exchange capacity of the granulated anion treatment agent A was investigated. The granulated body of the anion treatment agent A obtained by tumbling granulation with 50% each of the chlorine-type layered double hydroxide 1 and feldspar clay 2 by weight ratio, classifying with sieves of 0.3 mm and 1.0 mm, and drying at 500°C is, for example, as shown in the photograph of FIG. 3.

[0022] Next, a test was conducted under the following conditions to compare the anion exchange capacity between the anion treatment agent A according to the embodiment of the present invention and the anion treatment agent made of a conventional granulated body obtained by drying and curing a mixture of the powder of the layered double hydroxide 1 and a binder on the surface of the core material. As a result, an improvement in the anion exchange capacity of the anion treatment agent A according to the embodiment of the present invention was confirmed.

[0023] (Test conditions) The test conditions were as follows: The column was filled with the anion treatment agent A according to the embodiment of the present invention and the anion treatment agent made of a conventional granulated body obtained by drying and curing a mixture of the powder of the layered double hydroxide 1 and a binder on the surface of the core material, respectively. Raw water containing dissolved anions was passed through at a constant filtration rate and flow rate, and the anions in the treated water were analyzed to confirm the anion exchange capacity of the anion treatment agent A according to the embodiment of the present invention and the anion treatment agent made of the conventional granulated body.

[0024] ·Treatment anion: fluoride ion ·Raw water: Sodium fluoride is added to purified water and adjusted to 9.0 - 9.5 mg / L as fluoride ions ·Filter layer thickness: 300 mm ·Filtration rate: SV (space velocity) 10 h -1 ·End point: Until the fluoride ions in the treated water show the same concentration as the raw water ·When the raw water is passed under the above conditions, the fluorine treatment amount per filler volume and the treated water fluorine concentration are shown as a graph in Fig. 4. At the same time, the fluorine treatment ability per filler volume at the end point, the conventional product, and the increase rate of the fluorine treatment amount (mg / mL) of the anion treatment agent A of the present embodiment are shown in a table in Fig. 5

[0025] As shown in Fig. 4 and Fig. 5, in the case of the conventional product, which is a conventional granule obtained by drying and curing a mixture of a binder on the surface of a core material, the fluororesin amount stops at about 5.2 mg / mL, whereas in the anion treatment agent A of the embodiment according to the present invention, the fluororesin amount is about 9.4 mg / mL. The anion treatment agent A of the embodiment according to the present invention is thus treating 180% more fluoride ions than the conventional product, proving an improvement in anion exchange ability

[0026] <Effect of the anion treatment agent A of the embodiment according to the present invention> As described above, according to the anion treatment agent A of the embodiment according to the present invention, it is possible to provide a treatment agent having superior anion exchange ability for anions such as fluorine and phosphorus compared to conventional anion treatment agents. In particular, it is a granule of a kneaded product of layered double hydroxide 1 and feldspar clay 2, and since it does not use a core material composed of zeolite particles or the like, concerns about the outflow of organic solvents into the permeate can be eliminated

[0027] Moreover, since the anion treatment agent A of the embodiment according to the present invention does not use a core material composed of zeolite particles or the like, it is possible to increase the proportion of layered double hydroxide 1 in the granule, and the anion exchange ability can be improved

[0028] In addition, by processing the layered double hydroxide 1 from powder form to granular form, it also has the advantage that regeneration can be easily carried out.

[0029] Furthermore, as will be described later, the outer parts of the product generated during production can be reused as raw materials again, so it is an economical and clean granule manufacturing method that does not generate waste. By performing a regeneration operation after anion exchange, it can have anion exchange ability repeatedly.

[0030] <Regeneration operation of anion treatment agent> Next, the regeneration operation of the anion treatment agent according to the embodiment of the present invention will be described.

[0031] The layered double hydroxide 1 generally has an anion in its structure and is known to have anion exchange ability. Anions have different degrees of ease of exchange, so-called selectivity, depending on the type. The anion that shows the lowest selectivity for the layered double hydroxide 1 is chloride ion. Therefore, when used for the purpose of anion exchange, it is used as a so-called "chloride-type layered double hydroxide". The anion to be exchanged is exchanged with the chloride ion, the chloride ion is released into the water, and the anion to be exchanged is taken into the correlation of the layered double hydroxide 1, as if it were in a removed state.

[0032] As the exchange progresses, the chloride ions in the layered double hydroxide 1 disappear, and the correlation is satisfied with the anion to be exchanged. In that state, the anion exchange ability is lost.

[0033] Therefore, an operation to return to the chloride-type layered double hydroxide 1 so as to have anion exchange ability again, so-called regeneration operation, is required.

[0034] However, the layered double hydroxide 1 is in powder form, and it is difficult to recover after treatment and regeneration. Moreover, there has been no economical method to regenerate it into the chloride ion type until now, so it has been in a situation where it has to be discarded after use. Regarding recovery, it has become easier by making it granular.

[0035] As an inexpensive regeneration method, an economical method using a substance containing chloride ions was investigated.

[0036] The outline of the investigation is as follows. That is, water containing anions (fluoride ions, sulfate ions, ionic silica, phosphate ions, hydrogen carbonate ions, carbonate ions) having higher selectivity than chloride ions is passed through a column filled with granulated bodies of the anion treatment agent A according to an embodiment of the present invention, which is composed of a chlorine-type layered double hydroxide 1 and a feldspar clay 2, to exchange the anions with chloride ions until the anions can no longer be exchanged.

[0037] In this state, a regeneration liquid containing chloride ions is passed through to perform a regeneration operation. The regeneration operation of the anion treatment agent A in the embodiment where the anion exchange is completed is carried out in the following three steps (1) to (3), that is, (1) Washing step with treated water (2) Regeneration step with regeneration liquid (3) Extrusion washing step with treated water is carried out.

[0038] (1) Washing step with treated water In the washing step with treated water, anion exchange treated water or purified water is passed through. The water passing direction can be either the forward direction or the reverse direction during the treatment. The water passing speed is 2 to 50 m / h as the linear velocity LV or 2 to 50 h -1 as the space velocity SV. In particular, a linear velocity LV of 5 to 30 m / h is suitable. The water passing time is 5 to 60 minutes, and 10 to 30 minutes is suitable.

[0039] (2) Regeneration step with regeneration liquid In the regeneration step, the following regeneration liquid is passed through. The concentration of the regeneration liquid is 10 g / L to the saturation concentration, and in particular, 20 g / L or more is suitable. The water passing direction can be either the forward direction or the reverse direction during the treatment, but the reverse direction is suitable. The water passing speed is 2 to 50 h -1 as the space velocity SV, and in particular, 2.5 to 20 h -1 is suitable. The water passing time is 0.5 h to 10 h, and 1 to 4 h is suitable.

[0040] (3) Extrusion process In the extrusion process, anion exchange treated water or purified water is passed through. The water passing direction can be either the forward direction or the reverse direction during treatment. The water passing speed is 2 - 50 h as the space velocity SV -1 and particularly 5 - 20 h -1 is suitable. The water passing time is 5 - 60 minutes, and 10 - 30 minutes is suitable.

[0041] After the extrusion process, the treated raw water is flowed and it moves back to the anion exchange process again.

[0042] The test was conducted in the following manner to confirm the regeneration of the anion exchange capacity. It was carried out under 4 conditions with the conditions of no regeneration and 3 conditions of the water passing speed SV during regeneration.

[0043] Still, the common conditions are as follows. · Inner diameter of the water passing column: 13 mm · Thickness of the granulated body layer: 300 mm · Volume of the filled granulated material: 40 mL

[0044] (1) Conditions of the anion exchange process · Raw water: Water obtained by dissolving sodium fluoride in purified water · Raw water concentration: 10 mg / L as fluorine · Flow rate: 400 mL / h · Water passing speed: SV 10 h -1 · End point: The point where the fluorine in the treated water becomes equal to or more than that of the raw water.

[0045] (2) Conditions of the washing process · Washing water: Purified water · Flow rate: 2,000 mL / h · Water passing speed: LV 15 m / h (SV 50 h -1 ) · Washing process time: 15 minutes

[0046] (3) Conditions of the regeneration process (without regeneration) · Regeneration liquid: Water obtained by dissolving sodium chloride in purified water · Regeneration liquid concentration: 180 g / L as chloride ions (300 g / L as sodium chloride) · Flow rate: 400 mL / h · Water passing rate: Run-1 SV10h -1 、Run-2 SV5h -1 、Run-3 SV2.5h -1 · Regeneration process time: Run-1 1h, Run-2 2h, Run-3 4h

[0047] (4) Conditions of the extrusion washing process · Extrusion liquid: Purified water · Flow rate: 400 mL / h · Water passing rate: SV 10h -1 · Extrusion process time: 30 minutes

[0048] (5) Conditions of the confirmation process for the regeneration of anion exchange capacity · Raw water: Water obtained by dissolving sodium fluoride in purified water · Raw water concentration: 10 mg / L as fluorine · Flow rate: 400 mL / h · Water passing rate: SV 10h -1 · End point: The point at which the fluorine in the treated water becomes equal to or higher than that in the raw water.

[0049] Figure 6 shows a graph of the results of measuring the water passing multiple and the fluorine concentration of the treated water before and after regenerating the anion exchange capacity of the anion treatment agent A of the embodiment according to the present invention by changing the water passing rate SV in three stages during regeneration and the anion treatment agent without regeneration.

[0050] In Figure 6, circles represent without regeneration, triangles represent Run-1 SV10, squares represent Run-2 SV5, and diamonds represent Run-3 SV2.5. The plots before regeneration are filled, and the plots after regeneration are shown as unfilled.

[0051] Under the condition of no regeneration indicated by circles, the fluorine concentration of the treated water after the regeneration process shows a high value. In contrast, for the three conditions (Run-1 SV10, Run-2 SV5, and Run-3 SV2.5) indicated by triangles, squares, and diamonds where regeneration was carried out, the behavior of fluorine treatment after regeneration is the same as that before regeneration. From this, it can be said that the anion treatment ability has been regenerated.

Explanation of Symbols

[0052] A Anion treatment agent 1 Layered double hydroxide 2 Feldspar clay

Claims

1. A method for producing an anion treatment agent, characterized by mixing a layered double hydroxide having an anion exchange ability and feldspar clay obtained by grinding feldspar, which is a kind of tectosilicate having a three-dimensional structure mainly composed of aluminosilicate, into a powder form of 5 μm or less, performing rolling granulation to form a shape, drying at 300°C to 600°C, and then classifying.

2. A method for producing an anion treatment agent, characterized by mixing a layered double hydroxide having an anion exchange ability and feldspar clay obtained by grinding feldspar, which is a kind of tectosilicate having a three-dimensional structure mainly composed of aluminosilicate, into a powder form of 5 μm or less, performing rolling granulation to form a shape, classifying, then drying at 300°C to 600°C to produce an anion treatment agent, and reusing the raw materials that deviate from the forming and classification selection.

3. A method for regenerating an anion treatment agent, characterized by adding a regenerant containing chloride ions to the anion treatment agent produced by mixing a layered double hydroxide having an anion exchange ability and feldspar clay obtained by grinding feldspar, which is a kind of tectosilicate having a three-dimensional structure mainly composed of aluminosilicate, into a powder form of 5 μm or less, performing rolling granulation, drying at 300°C to 600°C, and then classifying.

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