JP2003126687A - Adsorbing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbing material with an excellent adsorption performance for a heavy metal and with an excellent selective adsorption performance for an organic substance. SOLUTION: The adsorbing material comprises powder or granular of a low crystalline hydroxyapatite in which Ca/P (molar ratio)=1.4 to 1.8. It is preferable that a crystal shape is plate-like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adsorbent for effectively adsorbing a heavy metal or an organic substance, and in particular, to exert an excellent adsorption performance by adjusting the form of hydroxyapatite to an appropriate one. The present invention relates to an adsorbent that can be used.

[0002]

2. Description of the Related Art An adsorbent is used as a means for removing harmful heavy metals contained in waste water, and zeolite has been generally known as a typical one.
However, since zeolite mainly adsorbs heavy metals by the action of physical adsorption, when adsorbing a plurality of heavy metal ions, it is necessary to select one having pores matching the individual ion diameters. Yes, its use is not universal. Therefore, various adsorbents have been proposed so far.

As one of such techniques, it has been proposed to use a bead-shaped chelate resin as an adsorbent. However, the chelate resin has a problem that it is difficult to efficiently adsorb and separate low-concentration dissolved metal ions, and a large amount of resin is required. In addition, the washing water for industrial waste and the like is alkaline, so that not only the adsorption performance of the chelate resin decreases in an alkaline environment, but also the resin itself deteriorates. Further, since the chelate resin is generally expensive, there is a drawback that it is uneconomical.

It has also been proposed to use an aluminosilicate type inorganic ion exchanger as a material for the adsorbent (for example, Japanese Patent Application Laid-Open No. 8-132026). However, such an ion exchanger may contain side reaction products and impurities in the manufacturing process thereof, and there is a problem that these are eluted during use.

By the way, hydroxyapatite [Ca
₁₀ (PO ₄ ) ₆ (OH) ₂ or Ca _10-z (HPO4)
_z (PO ₄ ) _6-z (OH) ₂ · nH ₂ O, which may be abbreviated as “HAP” below, has a good affinity with living organisms and is therefore used as a material for artificial bones and teeth. It is widely used, but by substitution with calcium ion, lead (Pb),
It is also known that it has excellent adsorptivity to pollutant heavy metals such as cadmium (Cd) and mercury (Hg), and it is being utilized as an adsorbent for various heavy metals by utilizing these characteristics. However, HAP used as an adsorbent
Since it is generally an agglomerate of fine crystals having needle-like or columnar crystals as primary particles, there is a disadvantage that flowing resistance increases when flowing a liquid through such HAP. For this reason, it is generally used in a state where HAP is carried on the surface of the base material (carrier) by some method.

As such a technique, for example, Japanese Patent No. 311
No. 6507 proposes a method in which an inorganic porous hard body containing calcium is immersed in a phosphoric acid aqueous solution and then cured to precipitate hydroxyapatite on the surface of the hard body and to use it as an adsorbent. In addition, JP 2000
No. -47038 proposes a purifier cartridge formed by combining fibrous activated carbon, HAP, and a binder. Further, in Japanese Patent No. 3091126, HAP which is highly crystallized by firing has a porous group having a large number of micropores from the viewpoint that calcium is not efficiently eluted and adsorption performance for heavy metals is not sufficient. Amorphous HAP for wood
An adsorbent for heavy metals that contains is proposed.

However, in these techniques, since HAP is carried on the surface of the base material, there is a problem that complicated processing steps are required. Also, the previous H
Although highly crystalline or non-crystalline AP has been used, these HAPs cannot be said to have sufficient adsorption performance, and further improvement in adsorption performance is desired.

On the other hand, organic substances such as free fatty acids and lipid peroxides, which are waste products of the skin, have an adverse effect such as rough skin. Therefore, it is required to suppress or remove the production of such organic substances. In addition, squalene, which is said to have the effect of smoothing the skin, has been recently included as a cosmetic ingredient, and it is known that this ingredient produces lipid peroxide by photooxidation.

As a drug for suppressing the production of such organic substances, organic natural compounds are generally used (for example, JP-A-6-128141 and 10-362).
No. 78, etc.), it is difficult to stably compound with organic natural drugs, and the compounding amount is limited, so that the expected effect is not obtained. Therefore, attention has been paid to HAP, which has selective adsorptivity for free fatty acids and lipid peroxides.
Is also proposed as a component of an external preparation for skin (for example, Japanese Patent Publication No. 6-92288). The HAP used in this technique is 900 to 1200 in a steam atmosphere.
It is a powder produced by a solid phase reaction at a high temperature of ℃, and it is suggested to have high crystallinity.

Although it can be said that the above-mentioned technique shows that HAP exhibits an adsorption performance even for an organic substance, it is a fact that the adsorption performance is not sufficiently exhibited depending on its use. . For example, various fatty acids are contained in foods and cosmetics, and odorous deterioration and active oxygen are generated due to the oxidative deterioration thereof. Therefore, it is desired to suppress or remove the production of free fatty acids and lipid peroxides that cause them. The effect is not obtained.

For example, a technique for removing lipid peroxide in olive oil or oleic acid by the adsorption action of HAP has been proposed (for example, "53rd Autumn Meeting of the Chemical Society of Japan Proceedings II", p. 816, Hobara, etc.), under practical experimental conditions, sufficient adsorption performance is not exhibited, and its removal effect is low.

[0012]

The present invention has been made under these circumstances, and its purpose is not only excellent in the adsorption performance for heavy metals but also excellent in selective adsorption performance for organic substances. To provide an adsorbent.

[0013]

Means for Solving the Problems The adsorbent of the present invention capable of achieving the above object is Ca / P (molar ratio) = 1.4-
The gist is that it is a powder or granules of low crystalline hydroxyapatite of 1.8. In addition, the low crystalline hydroxyapatite used as this adsorbent has a large primary particle,
Average particle size: 1-100 μm and specific surface area: 1-100 m ²
What is a plate-like crystal of / g is preferable.

On the other hand, as the substances to be adsorbed by the adsorbent of the present invention, (1) heavy metals such as Pb, Cd, and Hg, and (2) organic substances such as lipids and lipid peroxides. Among them, any one of them has excellent adsorption performance.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors examined the optimum form of an adsorbent in this HAP from various angles, assuming that HAP is used as a material. As a result, they found that a HAP having a Ca / P (molar ratio) within a predetermined range and having low crystallinity exhibits excellent adsorption performance for both heavy metals and organic substances, and completed the present invention. did. That is, as the HAP used as an adsorbent, one having a crystallinity as high as possible or an amorphous one has been used so far. It has been found that lower HAP has better adsorption performance for various substances.

The adsorbent of the present invention is made of HAP having a low crystallinity as described above. The "low crystallinity" means a state in which the degree of crystal development of apatite is low, for example, in X-ray diffraction. 2θ = 25.878 °, surface spacing (d)
= Full width at half maximum (FWHM) in the diffraction line of 3.44Å (hkl = 002) is 0.2
Say more than °. That is, when the FWHM is 0.2 ° or more, the crystallites are small and the arrangement is non-uniform. In the present invention, such a state is called “low crystallinity”. The HAP of the present invention is Ca / P (molar ratio) =
1.4 to 1.8, but Ca / P is 1.
When it is higher than 8, Ca (OH) ₂ is contained and Ca / P is 1.
When it is lower than ₄ , dibasic calcium phosphate (CaHPO ₄ ,
2H ₂ O) is mainly produced.

[0017] Such low crystalline HAP can effectively adsorb extremely low concentrations of heavy metals in the solution, or lipids and lipid peroxides under practical concentration conditions, and compared with conventional adsorbents. Therefore, the adsorption saturation becomes high. It is not possible to elucidate all of the reasons why the adsorption performance is further improved by using such low crystallinity HAP, but it is probably because the bonding force between the ions constituting the crystal is weak. It can be considered that the ion exchange reaction is likely to occur with heavy metals, the reaction activity with respect to organic substances becomes high, and the surface adsorption capacity becomes high.

Low crystalline HA used as the adsorbent of the present invention
The appearance of P may be either powdery or granular, and may be granulated. In addition, HAP having a plate-like crystal has a larger average grain size and smaller cohesiveness than conventional needle-shaped or columnar crystals, and therefore, even when such HAP is used as an adsorbent, water can flow. The water flow resistance does not increase, and the water flow rate can be maintained large, making it suitable for water purification applications.
Furthermore, HAP is a stable compound even if it is alkaline, and has the advantage that the adsorptive power does not decrease even in such an alkaline environment. In particular, plate-shaped HAP has a larger specific surface area than spherical HAP, and in this respect also, the adsorption performance can be further improved.

The plate-shaped HAP has an average particle size of 1 to 1.
It is preferable that the specific surface area is 100 μm and the specific surface area is 1 to 100 m ² / g. If this average particle size is less than 1 μm, the water pressure loss becomes large, making it unsuitable as an adsorbent used in a water purifier, and HAP exceeding 100 μm cannot be manufactured by a normal synthesis method and is industrially produced. Becomes difficult. In addition, the plate-like crystal HAP having the above physical properties is
It can be manufactured by the method described below.

The low crystallinity HAP consisting of plate-like crystals means that crystallites having a low degree of crystal growth are not merely aggregates but chemically bonded to form primary particles into a plate-like form.
Means AP. The term "plate-like" means that the crystal grain morphology is flat regardless of the overall shape of the crystal, and this plate-like structure includes flakes, thin plates, scales, leaf flakes, and mica. Shape, foil shape, etc., and the plate surface is square,
It includes a rectangle, a parallelogram, an ellipse, a circle, and an irregular shape, and the surface of this plate-like surface may have irregularities.

In producing the low-crystal HAP as described above, any method can be adopted as long as the HAP can have low crystallinity, for example, the method previously developed by the present inventors. The method disclosed in JP-A-9-40408 and the known Tiselius method can be used.

Among them, according to the method of JP-A-9-40408, the average grain size having a plate-like crystal morphology is 5 to 30 μm.
CaHPO ₄ .2H ₂ O powder with an average particle size of 5 μm
The following CaCO ₃ powder is used as a raw material, and these are suspended in water at an appropriate mixing ratio (for example, the ratio of Ca atom to phosphorus atom is in the range of 1.4 to 1.8). A water suspension liquid is prepared, and this suspension is 40 to 70
The temperature is kept at about ℃ and the reaction is carried out gently. On the other hand, in the method of Tiselius, CaHP
An aqueous alkaline solution is added to O ₄ .2H ₂ O powder to form an aqueous suspension, and the suspension is heated and held, filtered and dried.

In addition to these methods, (a) calcium nitrate [Ca (NO ₃ ) ₂ ] and ammonium hydrogen phosphate [(NH
₄ ) ₂ HPO ₄ ], and (b)
A method of mixing Ca (OH) ₂ with Mg (OH) ₂ and reacting it with phosphoric acid to replace a part of Ca in the crystal with Mg [eg, “Chemistry of apatite forming teeth and bones”, Tokai University Press], (c) Method utilizing hydration reaction of α-type tricalcium phosphate, and the like can also be adopted.

Whichever method is adopted, H of low crystallinity is obtained.
To obtain AP, the reaction rate may be increased or the reaction conditions may be such that the crystal arrangement becomes non-uniform. Specifically, the reaction rate can be increased by carrying out the reaction at a high temperature or by using a water-soluble and ionizable raw material. Further, in HAP, one having a structure in which a part of the constituent ions is replaced with a different kind of ion is easily generated (for example, PO ₄ ³⁻ ion or OH ⁻ ion is CO ₃ ²⁻ ion, Ca ²⁺ ion is When it is replaced with an alkaline earth metal ion such as Mg ²⁺ ) or with a different ion, the ionic radius is different and the crystal arrangement becomes non-uniform.

To use the adsorbent of the present invention as an adsorbent for heavy metals, HAP alone can be used.
If necessary, carriers such as activated carbon may be mixed in a predetermined ratio. When the adsorbent of the present invention is used as a pigment for cosmetics, it may be used by mixing it with various substances used as raw materials for cosmetics. The inventors of the present invention have found that HAP consisting of plate crystals is also useful as a cosmetic pigment (Japanese Patent Application Laid-Open No. 11-240819).
No.), when the HAP of the present invention is used for such an application, it exhibits a function as an adsorbent in addition to a function as a cosmetic pigment.

Hereinafter, the adsorbent of the present invention will be described in more detail with reference to Examples. The following Examples are not of a nature limiting the present invention, and the design may be changed in view of the above-mentioned and the following points. Any of these are included in the technical scope of the present invention.

[0027]

EXAMPLES Production Example 1 (Method of Tiselius) CaHPO ₄ .2H ₂ O powder (manufactured by Taihei Kagaku Sangyo Co., Ltd.) was mixed with an alkali (for example, NaOH) to form a water suspension, which was then heated, held, and filtered. -Drying to obtain the target powder.
The obtained powder has an average particle size of 17 μm and a specific surface area of 36.
It was composed of plate-like HAP having m ^{2 /} g and FWMH of 0.29 °.

Production Example 2 (Japanese Patent Laid-Open No. 9-40408)
Method) CaHPO ₄ .2H ₂ O powder (made by Taihei Chemical Industry)
CO ₃ powder (manufactured by Ube Materials) was added to make a water suspension state, followed by heating and holding, filtration and drying to obtain a target powder. The obtained powder is a plate-like H having an average particle size: 15 μm, a specific surface area: 83 m ^{2 /} g, and a FWMH: 0.27 °.
It consisted of AP.

Production Example 3 After adding water to Ca (OH) ₂ powder (manufactured by Ube Materials) to form a water suspension state, phosphoric acid (manufactured by Tosoh Corporation) was added to cause a reaction, heating and holding, and spray drying. Using a machine, a granular granule was obtained. The obtained granules have an average particle diameter of 137μ.
m (primary particles of 0.2 to 0.3 μm aggregated into a spherical shape), specific surface area: 46 m ^{2 /} g, FWMH: 0.24 °
Was made of columnar HAP.

Production Example 4 After adding water to Ca (OH) ₂ powder (manufactured by Ube Materials) to make a water suspension state, phosphoric acid (manufactured by Tosoh Corporation) was added to cause a reaction, heating, holding, filtration, Heated to obtain a powder. Using the obtained powder and a 1% CMC (carboxymethyl cellulose; Wako Pure Chemical Industries, Ltd.) aqueous solution as a raw material, a granular molding was obtained using an inclined Sara granulator. The obtained molded product had an average particle size of 1 mm (primary particles of 0.2 to 0.3 μm were aggregated into a spherical shape), specific surface area: 51 m ² / g, F
It consisted of columnar HAP with WMH: 0.25 °.

Production Example 5 CaCO ₃ powder (manufactured by Ube Materials) was added to CaHPO ₄ powder (manufactured by Taihei Kagaku Sangyo Co., Ltd.) to prepare a water suspension,
The powder was obtained by heating and holding and filtering and heating. The obtained powder has an average particle size of 10 μm (primary particles of 3 to 4 μm are aggregated in a spherical shape), specific surface area: 19 m ² / g, FWM.
It was composed of columnar HAP having H: 0.13 °.

Production Example 6 After adding water to Ca (OH) ₂ powder (manufactured by Ube Materials) to form a water suspension state, phosphoric acid (manufactured by Tosoh Corporation) was added to cause a reaction, heating and holding, and spray drying. Using a machine, it was made into granular granules, and further calcined at 500 ° C. The obtained granules had an average particle size: 132 μm (primary particles of 0.2 to 0.3 μm were aggregated into a spherical shape), specific surface area: 40 m ² /
g, FWMH: 0.17 ° columnar HAP.

Example 1 Using the HAP obtained by each of the above production methods and granular activated carbon (manufactured by Taihei Chemical Industry Co., Ltd., particle size: 300 μm), HA
Using a sample mixed with P: activated carbon = 20: 80 (mass ratio), a water flow test and an adsorption test were performed under the following conditions.

(Water flow test) Diameter: 60 mm x length: 10
Each sample was packed in a 0 mm packed tower, and the primary pressure was 0.1 MPa.
The water was made to flow through and the flow rate (flow rate) was measured when 1000 L (liter) was passed.

(Adsorption test) The above packed tower was filled with a sample,
Water containing 50 ppb lead ions was passed at a water flow rate of 1 L / min, and the residual lead ion concentration in the drained water at the time of 1000 L water flow was quantified by IPC emission spectrometry, and the adsorption performance of each sample was evaluated. did.

The results of these tests were used for the HA used for each sample.
It is shown in the following Table 1 together with the method for producing P. Those which satisfy the requirements specified in the present invention (Nos. 1 to 4) show good water permeability and are also excellent in adsorption performance. .

[0037]

[Table 1]

Example 2 Using each HAP obtained by each of the above-mentioned production methods, the adsorption performance for heavy metals by the batch method was evaluated under the following conditions.

(Test conditions) Pb: 2000 pp
1 g of each adsorbent was added to 200 mL of water containing m, Cd: 300 ppm, Hg: 250 ppm, stirred for 1 hour in a constant temperature bath at 25 ° C., and then solid-liquid separated, and the heavy metal ion concentration of the filtrate was analyzed by IPC emission spectrometry. The residual concentration was measured by the method.

The results are shown in Table 2 below together with the method for producing HAP used. Table 2 also shows the result (No. 13) of the test using the synthetic zeolite powder as the adsorbent. As is clear from these results, it is understood that those satisfying the requirements specified in the present invention (Nos. 7 to 10) exhibit good water permeability and are excellent in adsorption performance.

[0041]

[Table 2]

Example 3 Using each HAP obtained by each of the above-mentioned production methods, adsorption performance for lipid and selective removal performance of lipid peroxide were evaluated under the following conditions.

(Test conditions) Hexane: 5 g of the sample was added to 5 g of olive oil diluted with 50 mL, and 1
After stirring for an hour, the mixture was filtered and washed with 50 mL of hexane. The obtained filtered product was dried at 120 ° C. for 12 hours, and the filtrate was evaporated under reduced pressure to remove hexane at 60 ° C. and then dried at 80 ° C.

The loss on ignition of the filtrate was measured for 2 hours at 650 ° C., and the amount of adsorbed lipid was measured by subtracting from the blank (sample and hexane only). Further, the removal rate of lipid peroxide was calculated by measuring the peroxide value in the filtrate by the iodometric titration method (acetic acid-isooctane method) and subtracting it from the measured value of the sample-free blank.

The results are shown in Table 3 below together with the method for producing HAP used. As is clear from these results, those satisfying the requirements specified in the present invention (Nos. 14 to 1).
It can be seen that in 7), good adsorption performance is exhibited.

[0046]

[Table 3]

[0047]

EFFECTS OF THE INVENTION The present invention is constructed as described above, and an adsorbent excellent not only in adsorption performance for heavy metals but also in selective adsorption performance for organic substances can be realized.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuyuki Matsuda             247-1 Kujo-cho, Yamatokoriyama-shi, Nara Press             TE Ichibankan No.601 F-term (reference) 4D024 AA04 AB16 BA11 BC01 CA01                 4D038 AA08 AB63 AB71 AB73 AB74                       BB06                 4G066 AA17A AA17B AA50A AA50B                       BA20 BA22 BA26 BA33 CA46                       CA47 DA07 DA08

Claims (6)

[Claims] 1. An adsorbent comprising a powder or granules of low crystalline hydroxyapatite having a Ca / P (molar ratio) of 1.4 to 1.8. 2. The low crystalline hydroxyapatite has an average particle size of 1 to 100 μm and a specific surface area of 1 to 100 m ² / g.
The adsorbent according to claim 1, which is composed of the plate crystal of 3. A method for adsorbing heavy metals.
Or the adsorbent according to 2. 4. The adsorbent according to claim 3, wherein the heavy metal is one or more selected from the group consisting of Pb, Cd and Hg. 5. The adsorbent according to claim 1, which adsorbs an organic substance. 6. The adsorbent according to claim 5, wherein the organic substance is a lipid and / or a lipid peroxide.