Water purifying agent

Abstract

To provide a water purifying agent that exhibits superior water purifying performance and high strength.SOLUTION: Provided is a water purifying agent including a first porous structure composed of diatomaceous earth, and further including a second porous structure composed of the diatomaceous earth and having a smaller pore diameter and being denser than the first porous structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water purification agent containing diatomaceous earth. [Background technology]

[0002] Traditionally, diatomaceous earth has been molded and used for bath mats, etc. In recent years, the development of new applications for mesopore diatomaceous earth, also known as Wakkanai diatomaceous earth, has progressed, and it is now used, for example, as a building material such as a wall material.

[0003] In recent years, research has been progressing on water purification agents with even more specialized porous structures (Patent Document 1). However, few of the existing diatomaceous earth products are able to achieve both water purification performance and strength, and there are no diatomaceous earth products that are particularly excellent in both water purification performance and strength, and existing diatomaceous earth products are still not satisfactory. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-173401 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a water purifying agent having excellent water purification performance and strength. [Means for solving the problem]

[0006] As a result of extensive research into achieving the above-mentioned object, the present inventors have found that a structure including a first layer having a porous structure made of diatomaceous earth, with a second layer made of the same diatomaceous earth and having a dense porous structure formed on top of the first layer, the second layer having a porous structure with a smaller pore size and a denser structure than the first layer, not only has excellent water purification performance but also has excellent strength, and that such a structure is useful as a water purification agent and can solve all of the above-mentioned conventional problems at once. Furthermore, after obtaining the above findings, the inventors of the present invention conducted further studies and completed the present invention.

[0007] That is, the present invention relates to the following inventions. [1] A water purification agent comprising a first porous structure made of diatomaceous earth, characterized in that the water purification agent further comprises a second porous structure made of the diatomaceous earth, the second porous structure having a smaller pore size and being denser than the first porous structure. [2] The water purification agent according to [1], wherein the pore sizes of the porous structures are different and a third porous structure made of the diatomaceous earth is further formed. [3] The water purification agent according to [1], wherein the diatomaceous earth is Wakkanai diatomaceous earth. [4] The water purification agent according to [1], wherein the porosity of the first porous structure is 50% or more, and the porosity of the second porous structure is 10% or less. [5] The water purifying agent according to [1], wherein the porous structures are all made of fired bodies. [6] A method for producing a water purification agent using a slurry containing diatomaceous earth powder, characterized in that a combustible substance is used to form a first layer having a porous structure made of the diatomaceous earth and a second layer made of the diatomaceous earth and having a dense porous structure in which the pore size of the porous structure is smaller and more dense than that of the first layer. [7] The manufacturing method according to [6], wherein the combustible material is a polymer. [8] The manufacturing method according to [6], wherein the slurry is placed in a mold having a removable inner frame and then fired to form the first layer and the second layer. [Effects of the Invention]

[0008] The water purifying agent of the present invention has excellent water purifying performance and exhibits the effect of being excellent in strength. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 shows a mold having a plurality of removable inner frames used in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The water purification agent of the present invention is a structure including a first layer having a porous structure (first porous structure) made of diatomaceous earth, and is characterized in that a second layer made of the diatomaceous earth and having a dense porous structure (second porous structure) that has a smaller pore size and is denser than the first layer is provided on the first layer.

[0011] The porous structure is not particularly limited in terms of pore size, etc., and any known porous structure may be used. In the present invention, it is preferable that the pore sizes of the porous structures are different and that a third layer (third porous structure) made of diatomaceous earth is further provided. In the present invention, it is also preferable that the diatomaceous earth is Wakkanai diatomaceous earth. In the present invention, it is also preferable that the porosity of the first layer is 50% or more and the porosity of the second layer is 10% or less. Within these preferred ranges, the absorbency and strength derived from the porous structure can be improved.

[0012] In the present invention, it is preferable that the structure is a fired body, and such a preferred structure can be easily obtained by a method for manufacturing a structure using a slurry containing diatomaceous earth powder, in which a combustible substance is used to form a first layer having a porous structure made of diatomaceous earth and a second layer made of diatomaceous earth and having a dense porous structure in which the pore size of the porous structure is smaller and the second layer is denser than the first layer.

[0013] In the present invention, the combustible material is preferably a polymer. This preferred range allows for easier formation of the structure by firing. Furthermore, in the present invention, the first layer and the second layer are preferably formed by placing the slurry in a mold having a removable inner frame and firing the mixture. The slurry is not particularly limited as long as it does not impair the present invention, but it preferably contains a binder in addition to the diatomaceous earth. Suitable examples of the binder include a mixture of Kibushi clay, silicic anhydride, and an appropriate amount of water, or rhyolitic natural glass powder added to Wakkanai diatomaceous earth. When using such a preferred binder, the slurry is preferably prepared by blending and kneading, for example, 10 parts diatomaceous earth with 1 to 3 parts by weight, preferably 2 parts by weight, Kibushi clay, 1 to 3 parts by weight, preferably 1 part by weight, silicic anhydride, and an appropriate amount of water, or 1 to 3 parts by weight, preferably 1 part by weight, of rhyolitic natural glass powder.

[0014] In the present invention, the structure is used as it is or after processing as a water purifying agent. [Example]

[0015] Example 1 1. Preparation of slurry A slurry was prepared by mixing 10 parts by weight of diatomaceous earth, 2 parts by weight of Kibushi clay, 1 part by weight of silicic anhydride, an appropriate amount of water, and 1 part by weight of rhyolitic natural glass powder with combustible materials. The slurry was placed in the mold shown in Figure 1 with the following combustible material amounts, and fired.

[0016] [Combined amount of flammable materials] Area 1: Slurry containing 0% by weight of combustible material (polymer) Area 2: Slurry of 10% by weight of combustible material (polymer) Area 3: Slurry of 20% by weight of combustible material (polymer) Area 4: Slurry containing 30% by weight of combustible material (polymer) Zone 5: Slurry containing 40% by weight of combustible material (polymer)

[0017] The firing conditions were that the temperature inside the firing kiln was raised to around 1100°C and maintained for approximately 2 hours, after which the temperature increase was stopped and the product was slowly cooled in the firing kiln and removed. The porosity (air void ratio) of regions 1 to 5 of the resulting fired body (structure) was examined, and it was found to be 10% for region 1, 20% for region 2, 30% for region 3, 40% for region 4, and 50% for region 5.

[0018] (Test Example 1) The structure (specimen) obtained in Example 1 was left to stand under conditions of 20°C and 50% RH humidity until it reached a constant weight, and the bulk density was measured. Seven specimens were used for each sample, and the average of the measured values ​​was obtained. In addition, the bending strength of some of the specimens was measured by a three-point bending test. As a comparative example, the bending strength of a structure consisting of only region 1 was measured. The bending strength of the comparative example was 2.8 Nmm -2 The bending strength of the structure of Example 1 was 3.5 Nmm-2.

[0019] (Test Example 2) For the water purification performance test, a basket was placed above a water tank, and a 10cm square example or comparative example product was placed inside. A simulated wastewater solution consisting of 100ml of milk and 15L of water was then pumped through the diatomaceous earth compacts or calcined bodies. 15ml of activated sludge was added to the water tank, and the purification experiment was conducted for approximately two weeks with sufficient air supply. As a control test, a similar experiment was conducted using a system in which no activated sludge was added.

[0020] The water purification process was observed after adding 100 ml of milk as simulated wastewater to 15 liters of ultrapure water in a tank. On the first day of the purification experiment, the tank turned white with the milk. However, by the second and third days, the milk was absorbed by the Example Product, and the milk-induced cloudiness gradually disappeared. From around the sixth day, the pump installed inside the tank to suck up the water was clearly visible. This demonstrates that the wastewater is purified by forcibly circulating the water between the surface and the interior of the Example Product. On the other hand, the Comparative Example Product remained cloudy, and its water purification performance was inferior to that of the Example Product. [Industrial Applicability]

[0021] The structure of the present invention is suitable for use in a water purification agent. [Explanation of symbols]

[0022] 1 area 1 2 area 2 3 area 3 4 area 4 5 area 5

Claims

1. A water purification agent comprising a first porous structure made of diatomaceous earth, characterized in that the water purification agent further comprises a second porous structure made of the diatomaceous earth, the second porous structure having a smaller pore diameter and being denser than the first porous structure.

2. 2. The water purifying agent according to claim 1, wherein the pore sizes of the porous structures are different and a third porous structure made of the diatomaceous earth is further formed.

3. 2. The water purifying agent according to claim 1, wherein the diatomaceous earth is Wakkanai diatomaceous earth.

4. 2. The water purifying agent according to claim 1, wherein the porosity of the first porous structure is 50% or more, and the porosity of the second porous structure is 10% or less.

5. 2. The water purifying agent according to claim 1, wherein each of said porous structures is made of a fired body.

6. A method for producing a water purification agent using a slurry containing diatomaceous earth powder, characterized in that a combustible substance is used to form a first layer having a porous structure made of the diatomaceous earth and a second layer made of the diatomaceous earth and having a dense porous structure in which the pore size of the porous structure is smaller and the second layer is denser than that of the first layer.

7. 7. The method of claim 6, wherein the combustible material is a polymer.

8. 7. The method according to claim 6, wherein the slurry is placed in a mold having a removable inner frame and then fired to form the first layer and the second layer.

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