JP7264692B2 - Heavy metal remover, and adsorbent, compact and water purifier using same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heavy metal remover, and an adsorbent, molded article and water purifier using the same.

Activated carbon has excellent adsorption capacity for various contaminants, and has been used as an adsorbent in various fields, both domestic and industrial. In recent years, there has been a demand for delicious water free from chlorine and moldy odors, and various water purifiers have been proposed to meet this demand. However, in recent years, there has been an increasing interest in water quality safety and health, such as trihalomethanes (hereinafter abbreviated as THM), endocrine disruptors, and heavy metals. It is necessary to use other adsorbents such as inorganic compounds with unique adsorption capacity.

The present applicant has researched and developed a composite powder, in which plastic powder is adhered to an aluminosilicate-based inorganic compound, and a composite adsorbent consisting of a composite powder and an adsorptive substance, as means for efficiently removing heavy metals. (Patent Document 1).

On the other hand, especially in the field of water purification, there are strict regulations on the amount of elution of aluminum, and in the case of using an aluminosilicate-based inorganic compound, the elution of aluminum may become a problem.

Japanese Patent No. 4361489

Therefore, an object of the present invention is to provide an adsorbent material (heavy metal remover) capable of suppressing the elution of aluminum while maintaining the excellent heavy metal removal performance of the composite adsorbent as described above.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by a heavy metal removing agent having the following composition, and have completed the present invention by further research based on the findings.

A heavy metal remover according to one aspect of the present invention contains a fine particle compound (a1) made of an aluminosilicate compound and a plastic powder (a2), and contains 15% by volume or less of particles having a particle diameter of 40 μm or less in the volume particle size distribution. It is characterized by

With such a configuration, it is possible to provide a heavy metal remover capable of suppressing elution of aluminum while maintaining excellent removal performance for heavy metals and the like.

Also, the average particle size of the heavy metal removing agent is preferably 50 μm to 1 mm. As a result, the pressure loss and handleability are considered to be superior.

An adsorbent according to another aspect of the present invention is characterized by containing the above heavy metal remover and activated carbon.

In the adsorbent, the activated carbon is preferably coconut shell activated carbon. As a result, there is an advantage that THM can also be adsorbed and removed in addition to chlorine odor and musty odor.

In the adsorbent, it is preferable that the aluminum elution amount after 1 minute is less than 100 ppb when the ratio of the heavy metal removing agent to the adsorbent is 2% by mass and the filtration is performed at a space velocity (SV) of 2300 hr ⁻¹ .

Furthermore, the present invention also includes a molded body containing the adsorbent, and a water purifier comprising the adsorbent.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a heavy metal removing agent capable of suppressing elution of aluminum while maintaining excellent heavy metal removing performance, and an adsorbent, molded article and water purifier using the same.

The present inventors diligently studied the state of composite aggregate particles containing a fine particle compound (a1) made of an aluminosilicate compound and a plastic powder (a2) with respect to the ability to remove heavy metals such as lead ions and the elution of aluminum. As a result of repeated research, it was found that there is a correlation between the ratio (ratio) of composite aggregate particles with a particle size of 40 μm or less and the amount of aluminum eluted, and based on this finding, further research was conducted to reach the present invention. rice field.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to specific examples, but the present invention is not limited to these.

<Heavy metal remover>
The heavy metal removing agent of the present embodiment contains a fine particle compound (a1) made of an aluminosilicate compound and a plastic powder (a2), and is characterized in that particles having a particle diameter of 40 μm or less in the volume particle size distribution are 15% by volume or less. and

By using the heavy metal removing agent having such a structure as an adsorbent, it is possible to provide a water purifier or the like capable of suppressing elution of aluminum while maintaining excellent heavy metal removing performance.

In the present embodiment, the average particle size means the 50% particle size of the volume-based cumulative distribution, and the numerical value of this average particle size is a value measured by particle size distribution measurement by a laser diffraction/scattering method. For example, it can be measured by a wet particle size distribution analyzer (Microtrac MT3300EX II) manufactured by Microtrac Bell Co., which will be described later. Also, the volume % of particles having a particle diameter of 40 μm or less can be obtained from the volume-based cumulative distribution obtained by the particle size distribution measurement.

In the heavy metal removing agent in the present embodiment, particles having a particle diameter of 40 μm or less in the volume particle size distribution are more preferably 15% by volume or less, more preferably 10% by volume or less.

In this embodiment, the heavy metal removing agent contains a fine particle compound (a1) consisting of an aluminosilicate compound and a plastic powder (a2), which form composite aggregate particles. The composite aggregate particle is not particularly limited as long as it is a composite in which the plastic powder (a2) is attached to at least a part of the surface of the fine particle compound (a1). A2) may adhere to at least a part of the surface of the fine particle compound (a1) to adhere the fine particle compounds (a1) to each other.

The fine particle compound (a1) of the present embodiment is an aluminosilicate compound having a large ion exchange capacity and high selectivity to heavy metals.

As the aluminosilicate compound, an A-type or X-type aluminosilicate compound is suitable because of its large ion exchange capacity. Zeomic, a trade name marketed by Sinanen Zeomic Co., Ltd., and the like are known.

Examples of the plastic powder (a2) used in the present embodiment include polyesters such as polyethylene, polypropylene, polystyrene, ethylene-vinyl acetate copolymer, acrylonitrile-butadiene-styrene, polyethylene terephthalate, polybutylene terephthalate and polymethyl methacrylate, and polyamides such as nylon. powders of thermosetting resins such as various thermoplastic resins, furan resins, and phenolic resins. Among them, thermoplastic resin powder can be preferably used from the viewpoint that aggregate particles can be formed by heating. Among these thermoplastic resins, polyethylene is most preferred.

If the melt flow rate (MFR) of the thermoplastic resin powder is too small, the fine particle compound may be difficult to adhere to the surface of the thermoplastic resin. When heated, the thermoplastic resin may flow without retaining the shape of the particles. Therefore, the MFR is preferably 0.02 g/10 min or more, and preferably 40 g/10 min or less. The MFR is the outflow rate of a thermoplastic resin extruded from an orifice of specified diameter and length at constant temperature and pressure, and is specifically measured according to JIS K 7210 (2014).

For the composite aggregate particles of the present embodiment, it is first necessary to adhere the plastic powder (a2) to the fine particle compound (a1). The fine particle compound (a1) may be in the form of powder or granules. is 200 μm or less, preferably 100 μm or less. In particular, from the viewpoint of support retention, it is desirable that the particle diameter of the fine particle compound (a1) is 3 μm to 80 μm.

The particle size of the plastic powder (a2) used in the present embodiment is related to the particle size of the fine particle compound (a1). In the case of producing the fine particle compound (a1) of (1), a smaller plastic powder may be selected. From this point of view, it is desirable that the average particle size of the plastic powder is 0.1 μm to 200 μm, preferably 1 μm to 100 μm.

Adhering the plastic powder (a2) to the fine particle compound (a1) can be carried out by, for example, means such as far-infrared heating or a heat drying oven. In addition, the adhesion in the present embodiment means all states in which the fine particle compound and the plastic powder are firmly adhered, such as adhesion by an adhesive agent or the like, heat fusion by melting heating, etc., but the point is that they can be firmly adhered. Therefore, adhesion by heat sealing is preferable.

More specifically, for example, the fine particle compound (a1) is uniformly mixed with the plastic powder (a2) in an amount of 3 to 40% by weight to form a mixture, and the mixture is heated to the melting point of the plastic powder or higher, By pulverizing and sieving before the heat cools down, it is possible to obtain a heavy metal removing agent (composite aggregate particles) in which particles having a particle size of 40 µm or less in the volume particle size distribution account for 15% by volume or less.

The amount of the plastic powder (a2) in the composite aggregate particles can also be estimated by measuring the volatile content. Volatile content was measured by first weighing a sample dried at 110°C for 3 hours at room temperature, then placing the sample in a magnetic crucible with a lid and leaving it in a furnace at 930°C for 7 minutes to cool. This is done by measuring the weight of the remaining sample afterwards. Since the plastic powder decomposes and volatilizes at this temperature, the weight loss is taken as the content of the plastic powder (a2).

Particles that, as a result of sieving, are smaller than the predetermined sieving criteria can be reused. The average particle size of the heavy metal removing agent (composite aggregate particles) is preferably 50 µm or more and 1 mm or less in terms of pressure loss and handleability, and more preferably 75 µm or more and 500 µm or less.

In the present embodiment, by adjusting the ratio of particles with a particle size of 10 μm or less contained in the fine particle compound to be used, or by sieving with a sieving device of an appropriate size, the composite aggregate particles have a particle size of 40 μm or less. A heavy metal removing agent having a particle volume % of 15 or less can be obtained. Adjustment of the fine particle compound can be efficiently performed by using a cyclone device or the like.

The method for measuring the particle size distribution in this embodiment is as follows.

The particle size (average particle size, etc.) of the fine particle compound (a1), the plastic powder (a2), the heavy metal removing agent (composite aggregate particles), and the activated carbon was measured by a laser diffraction measurement method. As a method, a dispersion obtained by mixing a measurement object, a surfactant, and ion-exchanged water was measured using a laser diffraction/scattering particle size distribution analyzer (“MT3300 II” manufactured by Microtrack Bell Co., Ltd.). was measured by the transmission method. The concentration of the dispersion liquid was adjusted so as to fall within the measurement concentration range displayed by the apparatus. "Polyoxyethylene (10) octylphenyl ether" manufactured by Wako Pure Chemical Industries, Ltd. was used as the surfactant in preparing the dispersion liquid, and an appropriate amount was added so as not to generate air bubbles that would affect the measurement. Analysis conditions are shown below.

(Analysis conditions)
Number of measurements: 1 Measurement time: 30 seconds Distribution display: Volume particle size classification: Standard calculation mode: MT3000 II
Solvent name; WATER
Upper limit of measurement: 2000 μm Lower limit of measurement: 0.021 μm
Residual ratio; 0.00
Passing fraction ratio; 0.00
Residual ratio setting; Ineffective particle permeability; Transmitted particle refractive index; 1.81
Particle shape: non-spherical Solvent refractive index: 1.333
DV value; 0.0150 to 0.0700
Transmittance (TR); 0.700 to 0.950

Then, from the cumulative distribution of the particle size distribution (volume particle size distribution) obtained by the above measurement, the proportion (% by volume) of particles having a particle diameter of 40 μm or less can be obtained. The average particle size means a particle size that is 50% of the volume-based cumulative distribution.

Although the heavy metal removing agent of the present embodiment can be used as an adsorbent as it is, it is preferably mixed with activated carbon and used as an adsorbent as described later.

<Adsorbent, compact and water purifier>
The adsorbent of this embodiment is characterized by containing the above-described heavy metal removing agent and activated carbon.

As the activated carbon, any carbonaceous material can be carbonized and activated to become activated carbon, and those having a specific surface area of several hundred m ² /g or more are preferable.

Examples of the carbonaceous material include wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp production by-products, lignin, plant materials such as blackstrap molasses, peat, grass coal, lignite, lignite, Minerals such as limestone, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, and petroleum pitch, synthetic materials such as phenol, saran, and acrylic resin, and natural materials such as regenerated fiber (rayon). can. Among them, it is preferable to use plant-based coconut shell activated carbon.

When powdery or granular activated carbon is used, its size is preferably 75 μm to 2.8 mm (200 mesh to 7 mesh) from the viewpoint of workability, water contact efficiency, water flow resistance, etc., and 100 μm to 1 0.4 mm (150 mesh to 12 mesh) is more preferred. When fibrous activated carbon is used, it is preferable to cut it into pieces of about 1 to 5 mm from the viewpoint of formability, and from the viewpoint of removal of free chlorine, one with an iodine adsorption amount of 1200 to 3000 mg / g is recommended. preferably used.

The adsorbent in the present embodiment preferably has a ratio of composite aggregate particles of 1% by mass or more, preferably 50% by mass or less, and more preferably 20% by mass or less in the adsorbent. preferable. It is obtained by mixing the composite agglomerate particles described above with activated carbon. A mixing method is not particularly limited, and a known method can be adopted. This mixture (adsorbent) can be automatically filled and used as a water purification material as it is, but it is also possible to further pressurize and mold it and use it as a molded body in the form of a cartridge. When forming a molded article, a binder for molding or a non-woven fabric for maintaining the shape of the molded article may be used as appropriate. Silver-impregnated activated carbon or silver zeolite can also be added to the mixture of composite aggregate particles and activated carbon to impart antibacterial properties.

The adsorbent of the present embodiment has excellent heavy metal removal performance and can also suppress the elution of aluminum. By using the adsorbent of the present embodiment, the amount of the heavy metal removing agent in the adsorbent is set to 2% by mass, and when filtering at a space velocity (SV) of 2300 hr ^-1 , the aluminum elution amount after 1 minute is It has the great advantage of being able to go below 100 ppb. At this time, when the ratio of the heavy metal removing agent to the adsorbent is 2% by mass, the aluminum elution amount after 1 minute is less than 100 ppb when filtered at a space velocity (SV) of 2300 hr ^-1 . It is preferable to select the heavy metal removing agent and the activated carbon as described above, and in the actual usage of the adsorbent, the ratio of the heavy metal removing agent in the adsorbent can be appropriately changed.

When the adsorbent is packed in a container (column) and used as a water purifier, the water flow conditions are not particularly limited, but the space velocity (SV) is, for example, 50 to 4000 hr ^-1 so as not to increase the pressure loss too much. be done. Since the adsorbent of the present embodiment has a high adsorption speed, it exhibits performance even at flow velocities of 100 hr ^-1 or more, and even 1000 hr ^-1 or more, so that the size of the water purifier column can be greatly reduced.

The adsorbent, molded article, and water purifier of the present embodiment have excellent heavy metal removal performance and can suppress the elution amount of aluminum, and therefore are extremely useful for industrial use.

The present invention will be described in more detail below based on examples. However, the present invention is by no means limited by the following examples.

(Example 1)
As a fine particle compound, 1 kg of an aluminosilicate compound (“Zeomic” LH210N manufactured by Sinanen Zeomic Co., Ltd., average particle size 32 μm) (referred to as aluminosilicate 1), and as a plastic powder, polyethylene (PE) powder (manufactured by Sumitomo Seika Co., Ltd. “ Fluothane" UF-1.5N, MFR 1.4 g/10 minutes, melting point 110°C, average particle size 20 µm) and 75 g were uniformly mixed. This mixture was heated at a temperature of 160° C. for 1 hour using a heat dryer, and then pulverized with a pulverizer while maintaining the temperature at 60° C. or higher. Then, it was cooled to room temperature and sieved with a sieving machine. By changing the mesh size, a heavy metal removing agent having an average particle size and a particle volume % of particles having a particle size of 40 μm or less as shown in Table 1 was obtained. Volatiles (PE content) was 23%.

(Examples 2-4)
As the fine particle compound, an aluminosilicate compound ("Zeomic" LH210N manufactured by Sinanen Zeomic Co., Ltd. was pulverized with a roll mill to an average particle size of 30 μm (Example 2), 27 μm (Example 3), or 24 μm (Example 4). In the same manner as in Example 1, except that fine particle compounds (aluminosilicates 2, 3, and 4, respectively) were used, a heavy metal removing agent having an average particle size and a particle volume % of particles having a particle size of 40 μm or less as shown in Table 1 was obtained. The volatile content (PE content) was 23%.

(Comparative example 1)
As the fine particle compound, an aluminosilicate compound ("Zeomic" LH210N manufactured by Sinanen Zeomic Co., Ltd. was pulverized with a roll mill and the fine particle compound (aluminosilicate 5) having an average particle size of 17 µm (Comparative Example 1) was used. In the same manner as in Example 1, a heavy metal removing agent having an average particle size and a particle volume % of particles having a particle size of 40 μm or less was obtained as shown in Table 1. The volatile content (PE content) was 23%.

(Comparative example 2)
As the fine particle compound, an aluminosilicate compound (“Zeomic” LGK10T manufactured by Sinanen Zeomic Co., Ltd., average particle size 9 μm) (referred to as aluminosilicate 6) was used in the same manner as in Example 1, as shown in Table 1. A heavy metal removing agent having an average particle size and a proportion of particles having a particle size of 40 μm or less was obtained. The volatile content (PE content) was 23%.

<Evaluation test>
0.64 g of the heavy metal remover of each of the examples and comparative examples obtained as described above, activated carbon ("Kuraray Coal" GW60/150 manufactured by Kuraray Co., Ltd. (particle size 0.25 mm to 0.1 mm, specific surface area 800 m ² /g) and 32.3 g were uniformly mixed to obtain adsorbents for each of Examples and Comparative Examples.

The proportion (% by volume) of particles of 40 μm or less in the heavy metal removing agent was calculated from the measurement result of the above-mentioned (particle size distribution).

Regarding the lead ion removal performance, each adsorbent was packed in a 60 ml column, and 2.3 liters of raw water containing 50 ppb soluble lead (lead nitrate was added to adjust the lead ion concentration to 50 ppb) ( L)/min (SV2300hr ^-1 ), and the lead ion removal rate was calculated from the lead ion concentration. The flow rate (L) at which the lead ion removal rate is 80% and the flow rate per unit volume of the adsorbent (column) (L/ml) were evaluated as the lead ion removal performance.

Further, the aluminum elution amount was obtained from the difference between the aluminum concentration in the raw water and the aluminum concentration in the raw water after 1 minute of passing the water under the above conditions.

The results are shown in Table 1, respectively.

(Discussion)
From the results in Table 1, it was confirmed that the adsorbents using the heavy metal removers of the examples exhibited excellent lead removal performance while suppressing the elution of aluminum.

On the other hand, it was found that the adsorbent using the heavy metal removing agent of the comparative example, which did not satisfy the requirements of the present invention, could not sufficiently suppress the elution of aluminum.

From the above results, it was shown that by using the heavy metal removing agent of the present invention, it is possible to provide adsorbents, water purifying materials, etc. that can suppress the elution of aluminum while maintaining a very excellent lead removal rate.

Claims (6)

including a fine particle compound (a1) made of an aluminosilicate compound and a plastic powder (a2),
the plastic powder (a2) adheres to at least part of the surface of the fine particle compound (a1);
The content of the plastic powder (a2) is 3 to 40% by weight with respect to the total 100% by weight of the fine particle compound (a1) and the plastic powder (a2);
The fine particle compound (a1) has an average particle size of 200 μm or less,
Particles with a particle diameter of 40 μm or less in the volume particle size distribution are 15% by volume or less , and
A heavy metal removing agent having an average particle size of 50 μm to 1 mm . An adsorbent comprising the heavy metal remover according to claim 1 and activated carbon. 3. The adsorbent of claim 2 , wherein said activated carbon is coconut shell activated carbon. 4. The aluminum elution amount after 1 minute is less than 100 ppb when the ratio of the heavy metal removing agent to the adsorbent is 2 % by mass and the filtration is performed at a space velocity (SV) of 2300 hr ⁻¹ . adsorbent. A molded article containing the adsorbent according to any one of claims 2 to 4 . A water purifier comprising the adsorbent according to any one of claims 2 to 4 .