JP2003190941A - Adsorbent for water cleaner, method for manufacturing the same and water cleaner using the adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent for a water cleaner excellent in the adsorpability of heavy metals, especially lead, to provide a method for manufacturing the same and the water cleaner using the adsorbent. <P>SOLUTION: Since the adsorbent with a lead adsorption quantity of 200 mg/g or more and a compression strength of above 1.0 N/mm<SP>2</SP>develops high lead removing capacity at the time of passage of water and not collapsed during the passage of water, it is preferable as the adsorbent for the water cleaner. The adsorbent for the water cleaner excellent in lead removing capacity and strength can be obtained by heating a powder of a synthetic calcium phosphate compound to 200-500°C to solidify the same. The water cleaner using this adsorbent can develop excellent heavy metal removing capacity over a long period of time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adsorbent for a water purifier capable of removing heavy metals, particularly lead, which impairs safety and taste, a method for producing the same, and a water purifier using the same.

[0002]

2. Description of the Related Art There is a water purifier that uses activated carbon to remove residual chlorine, trihalomethane, etc. contained in tap water. If you don't use this type of water purifier for a long time,
It is not preferable because various bacteria are generated in the activated carbon. Therefore, a water purifier using membrane filtration such as a porous membrane has been developed to prevent outflow of various bacteria generated in activated carbon, and this type has recently become the mainstream.

On the other hand, as a substance which may be eluted from the ground or a water distribution pipe and contained in well water or tap water in the form of ions, harmful substances such as lead, iron, copper, nickel and zinc, There are heavy metals such as chromium and cadmium, and various studies have been made on methods for removing them.

[0004]

Among the heavy metals, hydroxyapatite is known as an adsorbent having a particularly excellent lead adsorption performance. Although hydroxyapatite has a higher heavy metal ion adsorption performance when the particle size is smaller, because it is brittle, it is possible that fine powder may be generated due to water flow and block the adsorbent movement suppression member etc. to increase water flow pressure. .

Japanese Patent Laid-Open No. 2001-47038 describes a method of forming hydroxyapatite together with fibrous activated carbon using a binder to prevent the outflow of fine powder. However, when a binder is used, the surface of activated carbon or hydroxyapatite is covered with the binder, so that there is a problem that the removal performance of residual chlorine and heavy metal ions deteriorates.

In view of the above situation, the present inventors have diligently studied an adsorbent for a water purifier which solves the above-mentioned problems and does not contain heavy metals, especially lead, and which can obtain safe and delicious water in the long term. As a result of repeating, the present invention was completed.

[0007]

That is, the first gist of the present invention is an adsorbent for a water purifier having an adsorbed amount of lead of 200 mg / g or more and a compressive strength of more than 1.0 N / mm ² .

The average particle size of the adsorbent for water purifier is 20 to 7
When it is 50 μm, the adsorption performance is excellent and water is easily passed, which is preferable. Further, it is preferable that the adsorbent for a water purifier is made of a calcium phosphate-based compound, because the adsorption performance is excellent. Furthermore, the calcium phosphate-based compound is at least one selected from hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate,
It is more preferable because each has excellent adsorption performance.

The second aspect of the present invention is a method for producing an adsorbent for a water purifier, which comprises heating and solidifying a powder of a synthetic calcium phosphate compound at 200 to 500 ° C.

Further, after drying the mixed slurry of the synthetic calcium phosphate compound powder and water, the mixture is heated to 200 ° C. to 500 ° C.
It is preferable to heat and solidify at ℃ because the yield is improved. At this time, the drying temperature is preferably 80 to 150 ° C. The synthetic calcium phosphate-based compound is preferably at least one selected from hydroxyapatite, tricalcium phosphate, and tetracalcium phosphate because each has excellent adsorption performance.

The third gist of the present invention is a water purifier using the adsorbent for a water purifier described above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The adsorbent for water purifiers of the present invention has a lead adsorption amount of 200 mg /
A material having a compression strength of g or more and a compression strength of more than 1.0 N / mm ² is used.

Here, the amount of lead adsorbed (mg / g) means the amount of lead adsorbed by 1 g of the adsorbent for water purifier when the adsorbent for water purifier is immersed in an aqueous solution containing lead for 24 hours. Say. Specifically, for example, a lead nitrate aqueous solution is used to obtain a lead concentration of 200 m.
200 ml in Erlenmeyer flask prepared to be g / L
The amount of adsorbed lead can be determined by collecting 50 mg of the adsorbent for a water purifier, shaking the mixture, and filtering after 24 hours with a filter, and measuring the residual lead concentration in the filtrate water.

The compressive strength (N / mm ² ) means Hiramatsu, Oka, Kiyama: Journal of the Japan Mining Industry Association, 81, 10, 24 (19).
It is obtained from the weight applied to the adsorbent for a water purifier when the adsorbent for a water purifier is compressed with a flat plate by referring to the method of 65), and the compressive strength: St (N / mm ² ), P; load (N) , D; St = 2.8 when the particle diameter (mm) is used.
It is calculated from the equation P / πd ² .

A water purifier is usually required to have a flow rate of about 1 to 5 L / min as a water flow rate by water pressure. When flowing water at such a flow rate, the lead adsorption amount is 200 mg / g
If it is smaller than this, it becomes difficult to sufficiently remove lead. The lead adsorption amount is more preferably 220 mg / g or more, still more preferably 250 mg / g or more.

Further, in order to prevent the adsorbent for a water purifier from collapsing with time when passing water through the water purifier,
A compressive strength of greater than 1.0 N / mm ² is required.
The compressive strength is more preferably 1.3 N / mm ² or more,
It is more preferably 1.5 N / mm ² or more.

The size of the adsorbent for the water purifier has an average particle size of 20.
~ 750 μm granular form is preferred, 150-500 μm
Is more preferable. When the particle size is smaller than 20 μm, filtration resistance increases and water permeability deteriorates. On the other hand, when it is larger than 750 μm, the voids between particles become large, and the removal performance tends to be low.

In order to obtain an adsorbent for a water purifier having a lead adsorption amount of 200 mg / g or more and a compressive strength of more than 1.0 N / mm ^2, it is preferable to use a calcium phosphate compound, which is a synthetic calcium phosphate compound. By heating and solidifying the powder at 200 ° C. to 500 ° C., an adsorbent for a water purifier that satisfies both strength and lead adsorption performance can be obtained.

When the heating and solidifying temperature of the synthetic calcium phosphate-based compound is lower than 200 ° C., the solidification becomes insufficient and the water is broken when water is passed through the water purifier to generate fine powder.
On the other hand, when the heating and solidifying temperature is higher than 500 ° C., the strength of the obtained particles becomes strong, but the density of the adsorbent increases, and the specific surface area decreases, so that the adsorption performance decreases. The heating time may be 30 minutes to 5 hours, more preferably 1 hour to 2 hours.

The specific surface area of the adsorbent for the water purifier is 50 m ² /
It is preferably at least g, and more preferably at least 60 m ² / g.

The synthetic calcium phosphate-based compound is preferably at least one kind of hydroxyapatite, tricalcium phosphate and tetracalcium phosphate. Among them, hydroxyapatite is most preferable because of its excellent adsorption performance. The synthetic calcium phosphate-based compound can be synthesized by reacting a phosphate aqueous solution with a calcium salt aqueous solution. In particular, hydroxyapatite can be obtained as a slurry on the market.

The particle size of the adsorbent for a water purifier is preferably 20 μm to 750 μm as an average particle size as described above, but sieving may be performed to adjust to this range. Here, in the case of using a mixed slurry of the synthetic calcium phosphate compound and water, the mixed slurry may be directly heated and solidified, but before being heated and solidified, after drying at a temperature of about 80 ° C to 150 ° C, By sieving to adjust the particle size and then heating and solidifying, it is possible to re-slurry the particles having a deviated particle size, so that the yield can be improved. Drying temperature is 100 ° C-13
0 degreeC is preferable and about 110 degreeC is the most preferable.

The water purifier using the water purifier adsorbent of the present invention described above can efficiently remove heavy metals.
Further, in order to efficiently remove residual chlorine, trihalomethane, etc., it is preferable to use activated carbon in addition to the adsorbent for a water purifier of the present invention. Although activated carbon has a low removal ability, it also adsorbs heavy metals and contributes to prolonging the adsorption performance of the adsorbent, so it is more preferably used in combination with activated carbon.

The activated carbon is not particularly limited as long as it has a performance meeting the purpose of removing residual chlorine, trihalomethane, etc., and its shape is powdery, fibrous,
Alternatively, a granular material or the like can be used. Further, the type of activated carbon is not necessarily limited, and natural activated carbon such as coconut shell activated carbon, bone charcoal, charcoal, pitch type, petroleum coke type,
A burning activator such as resin or rubber or a chemical activator can be used, but the substances to be removed are often those having a relatively small molecular weight such as trihalomethane, and when considering the economical efficiency, steam activated coconut shell activated carbon is also considered. Is most practically used. Furthermore, in order to impart antibacterial properties,
You may attach silver etc.

In addition to the adsorbent for water purifier and activated carbon of the present invention,
It is more preferable to use a porous film because solid substances such as iron rust and bacteria can be removed. As the porous membrane, a flat membrane, a hollow fiber membrane, a tubular membrane or the like can be used, but it is more preferable to use a hollow fiber membrane having high volume efficiency.

Examples of the hollow fiber membrane include cellulose type, polyolefin type (polyethylene, polypropylene), polyvinyl alcohol type, ethylene / vinyl alcohol copolymer, polyether type, polymethylmethacrylate (PMMA) type, polysulfone type. Materials made of various materials such as polyacrylonitrile-based, polyfluorinated ethylene (Teflon (registered trademark))-based, polycarbonate-based, polyester-based, polyamide-based, and aromatic polyamide-based materials can be preferably used. Above all, considering the strength and elongation of the film, the bending resistance, the washability, the handleability and the high chemical resistance, etc.,
Polyoolefin-based hollow fiber membranes such as polyethylene and polypropylene are preferred. Although not particularly limited, the hollow fiber has an outer diameter of 20 to 2000 μm and a pore diameter of 0.
01 to 2 μm, porosity 20 to 90%, film thickness 5 to 30
It is preferably 0 μm.

When a porous membrane is used in the water purifier of the present invention, if another filter medium is provided at the final stage after water has passed, the risk of reverse contamination of bacteria from the water purification outlet can be minimized. preferable. The adsorbent for a water purifier and the activated carbon of the present invention may be used in any order, or may be used as a mixture of the two. Further, in addition to the activated carbon, other components such as an ion exchange resin, calcium sulfite, coral sand, barley stone, meio stone, tourmaline may be used together.

The adsorbent for a water purifier, activated carbon and porous membrane of the present invention may be contained in one container or a combination of a plurality of containers. Further, it is preferable to use a primary filter in addition to the above combination so that coarse dust can be removed in advance.

The present invention will be specifically described below based on examples. Example 1 A mixed slurry of hydroxyapatite and water was dried at 110 ° C., sieved with a 30-60 mesh sieve, and then heated at 200 ° C. for 1 hour to give a particle size of 250.
An adsorbent for a water purifier having a size of μm to 500 μm was obtained. The specific surface area of the obtained adsorbent for a water purifier was measured by the BET method using a Betasorb automatic surface area meter 4200 type manufactured by Nikkiso Co., Ltd.

Regarding the obtained adsorbent for water purifier,
An aqueous solution of lead nitrate was prepared to have a lead concentration of 200 mg / L, 200 ml was collected in an Erlenmeyer flask, 50 mg of the adsorbent for a water purifier was added, shaken, and after 24 hours, filtered with a filter to remove water in the filtrate water. The amount of lead adsorbed was determined by measuring the residual lead concentration.

Regarding the obtained adsorbent for water purifier,
Using Shimadzu Corporation micro compression tester MCTM-200 (plane indenter 500 μm diameter), load speed 7.056 × 10
^-3 N / sec is measured and the compressive strength is St =
It was calculated from the formula of 2.8 P / πd ² . Here, compressive strength: St (N / mm ² ), P: load (N), d: particle diameter (mm).

Further, using the obtained adsorbent for water purifier,
A water purifier having the structure shown in FIG. 1 was created. Here, 1 is an adsorbent for a water purifier, 2 is a porous partition plate made of 100 mesh nylon mesh, 3 is a porous hollow fiber membrane, 4 is a primary filter, 5 is a raw water inlet, 6 is a water outlet, 7 Is a container, 8 is a membrane module case, and 9 is an O-ring. 40 g of the adsorbent for the water purifier was filled. Then, 2000 L of water was passed through this water purifier at a rate of 2 L / min as a total filtration amount, and the filling amount (40 g) of the adsorbent for water purifier before water passage and the adsorbent for water purifier that remained without passing through the porous partition plate From the amount of (37.2 g), the weight% of the fine powder that passed through the porous partition plate ((40-37.2) / 40 × 100 = 7: hereinafter, referred to as the fine powder generation rate) was determined. Table 1 shows the amount of lead adsorbed, the compression strength, and the fine powder generation rate.

<Example 2> An adsorbent for a water purifier was prepared in the same manner as in Example 1 except that the heating and solidifying temperature was changed to 300 ° C, and the specific surface area, the amount of lead adsorbed, and the compression strength were obtained in the same manner as in Example 1. I asked. In addition, the same water purifier as in Example 1 was created,
The same water flow was performed to obtain the fine powder generation rate. The results are shown in Table 1.

<Example 3> An adsorbent for a water purifier was prepared in the same manner as in Example 1 except that the heating and solidifying temperature was set to 500 ° C, and the specific surface area, the amount of lead adsorbed, and the compression strength were obtained in the same manner as in Example 1. I asked. In addition, the same water purifier as in Example 1 was created,
The same water flow was performed to obtain the fine powder generation rate. The results are shown in Table 1.

<Comparative Example 1> An adsorbent for a water purifier was prepared in the same manner as in Example 1 except that the heating and solidifying temperature was 110 ° C., and the specific surface area, the amount of lead adsorbed, and the compression strength were obtained in the same manner as in Example 1. I asked. In addition, the same water purifier as in Example 1 was created,
Water was passed through in the same manner, but 2000 L could not be passed because the hollow fiber membrane was clogged in the middle, so the rate of generation of fine powder at the time when water could not be passed was determined. The results are shown in Table 1.
It was shown to.

Comparative Example 2 An adsorbent for a water purifier was prepared in the same manner as in Example 1 except that the heating and solidifying temperature was 700 ° C., and the specific surface area, the amount of lead adsorbed, and the compression strength were obtained in the same manner as in Example 1. I asked. In addition, the same water purifier as in Example 1 was created,
The same water flow was performed to obtain the fine powder generation rate. The results are shown in Table 1.

[0037]

[Table 1]

As shown in Table 1, a temperature of 200 ° C. to 500 ° C.
The adsorbent solidified by heating at ℃ has a high lead adsorption amount, a high compression strength, and a low fine powder generation rate, and thus can be suitably used in a water purifier. On the other hand, the one heated at a temperature of 110 ° C
Although the amount of lead adsorbed is high, the rate of generation of fine powder is high, and therefore it easily collapses, so it is not suitable as an adsorbent for water purifiers. Also, 70
The one heated at 0 ° C has a low fine powder generation rate, but has a low lead adsorption amount, and is not suitable as an adsorbent for a water purifier.

[0039]

The adsorbent for water purifiers of the present invention has a lead adsorption amount of 200 mg / g or more and a compressive strength of 1.0 N / mm ^2.
Since it is larger than the above, it exhibits a high lead removal ability when water is passed through it, and it does not collapse during water passage, so it is suitable as an adsorbent for water purifiers. In addition, the method for producing an adsorbent for a water purifier according to the present invention uses a powder of a synthetic calcium phosphate-based compound,
Since it is heated and solidified at 00 ° C to 500 ° C, the performance of the adsorbent is not deteriorated. Further, the water purifier of the present invention can exhibit the heavy metal removal performance such as lead over a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a water purifier of the present invention.

[Explanation of symbols]

Adsorbent for 1 water purifier 2 Porous partition plate 3 Porous hollow fiber membrane 4 primary filters 5 Raw water inlet 6 spout 7 containers 8 membrane module case 9 O-ring

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01J 20/30 B01J 20/30 F term (reference) 4D024 AA02 AB11 AB16 BA02 BA05 BA11 BB01 CA11 DB03 DB05 DB19 DB26 4G066 AA50B BA20 BA26 BA35 BA36 BA38 CA46 DA07 EA20 FA21 FA22 FA34

Claims (9)

[Claims] 1. An adsorbent for a water purifier having a lead adsorption amount of 200 mg / g or more and a compressive strength of more than 1.0 N / mm ² . 2. The adsorbent for a water purifier according to claim 1, which has an average particle size of 20 to 750 μm. 3. The adsorbent for a water purifier according to claim 1, which is composed of a calcium phosphate-based compound. 4. The adsorbent for a water purifier according to claim 1, wherein the calcium phosphate compound is at least one selected from hydroxyapatite, tricalcium phosphate and tetracalcium phosphate. 5. A method for producing an adsorbent for a water purifier, which comprises heating and solidifying a powder of a synthetic calcium phosphate-based compound at 200 ° C. to 500 ° C. 6. The method for producing an adsorbent for a water purifier according to claim 5, wherein the mixed slurry of the synthetic calcium phosphate compound powder and water is dried and then solidified by heating at 200 ° C. to 500 ° C. 7. The method for producing an adsorbent for a water purifier according to claim 6, wherein the drying temperature is 80 to 150 ° C. 8. The synthetic calcium phosphate-based compound,
The method for producing an adsorbent for a water purifier according to any one of claims 5 to 7, wherein at least one kind of hydroxyapatite, tricalcium phosphate and tetracalcium phosphate is used. 9. A water purifier using the adsorbent for a water purifier according to claim 1.