JPS62260707A - Production of high purity hydroxyapatite - Google Patents

Abstract

PURPOSE:To produce hydroxyapatite having high purity, by reacting a calcium compound with phosphoric acid ion in an aqueous solution containing phosphoric acid ion while adjusting the total carbonic acid concentration in the reaction liquid below a specific level. CONSTITUTION:A phosphoric acid salt is dissolved in pure water or distilled water and the solution is deaerated with N2 gas. The obtained aqueous solution is introduced through a pipe 1 into a closed reaction vessel 2. Separately, an aqueous solution of a calcium compound is introduced through a pipe 5 and a strongly basic ion exchange resin layer 6 into the above closed reaction vessel 2. Accordingly the total carbonic acid concentration in the reaction liquid becomes <=20mg/L. Apatite can be produced by adjusting the pH of the reaction liquid to 8-9 by supplying an alkaline solution to the reaction vessel through a pipe 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing high-purity hydroxyapatite that can be used as a raw material for bioceramics or chromatograph filling materials.

[Conventional technology and its problems]

Hydroxyapatite (hereinafter simply referred to as apatite)
Dry method and wet method are known as methods for producing apatite, but the dry method not only requires a large amount of heat, but also causes CaCO3 and other impurities contained in the raw materials to remain in the product. Removal of residual C a C03 and other impurities has become a troublesome problem as it reduces the purity of C a C03 and other impurities.

In addition, in the wet method, carbonic substances present in the reaction solution react with Ca ions during the reaction process, and Ca C03 and other impurities mixed in the raw materials mix into the product. There were problems such as lowering the purity of apatite.

[Purpose of the invention]

An object of the present invention is to provide a method for producing apatite with extremely low content of impurities, particularly CaCO3.

[M-formation of invention]

The present invention provides a method for producing apatite by reacting phosphate ions in an aqueous solution containing phosphate ions with an aqueous solution of an IVV compound at a pH of 6 or higher, in which the total carbonate concentration in the reaction solution is 20η/L or less. This is a method for producing high-purity apatite, which is characterized by carrying out the reaction under the following conditions.

As a result of intensive research on the production method of high-purity apatite with low content of CaCO3 and other impurities, the present inventors found that the total carbonate concentration in the reaction solution was reduced to 20η/ in a solution containing phosphate ions under the following conditions. We have discovered that highly pure apatite can be produced by reacting phosphoric acid ions with p-sium compounds.

To make the total carbonic acid 1 degree in the reaction solution less than 20897,
This can be reliably achieved by using an aqueous Ca compound solution that is passed through a strongly basic ion exchange resin layer.

The total carbon dioxide concentration refers to the CO□, C01 dissolved in the solution.
- or HCO3-, etc., converted into 002.

Next, the present invention will be explained in detail based on the drawings.

In Figure 1, after dissolving phosphate in pure water or distilled water, the aqueous solution degassed with N2 gas is introduced into the closed reaction vessel 2 through tube 1, while the CaC4 aqueous solution is introduced through tube 5 into a strongly basic solution. After passing through the ion exchange resin layer 6, it is introduced into a closed container 2m, and is stirred with a stirrer 3 to react.

By passing the Ca Ct2 aqueous solution through a strongly basic ion exchange resin layer, the C01-,
While HCOi, Sio, etc. are removed, the fluorine (OH-) necessary for the reaction is also supplied.

Furthermore, if necessary, an alkaline solution such as NaOH solution is supplied through the tube 4 to adjust the reaction solution to a pH of 6 or higher, preferably 8.
Adjust to ~9.

The generated apatite is discharged from the bottom of the container through the tube 8 and dried to obtain a product. The reaction waste liquid is discharged through pipe 7.

If the pH is 6 or less, apatite is not produced or CaHPO4 is likely to be produced, which is not preferable.

When providing a space above the closed reaction vessel 2, it is preferable to inject nitrogen gas.

Figure 2 shows an example using a flow reactor, in which a phosphate solution and an aqueous C a Cz2 solution fed from tube 5 through a layer of strongly basic ion exchange resin are mixed in I'ft1. Since the reaction proceeds sufficiently at the bottom of the reactor 2', there is no need to use a stirrer. In addition, the generated apatite forms a classified layer, so
By discharging the produced apatite from the product discharging pipe 8 at a predetermined height, a product with uniform particle size can be obtained.

The phosphate aqueous solution and the Ca C12 aqueous solution may each be separately introduced into the bottom of the reaction vessel 2.

In the present invention, the phosphate ion source is N3 PO4
, Na3 PO4, N2 HPO4+ NH4H2PO
4 etc. can be used, and to increase the buffering properties of the solution, NH4H
Preferably, 2PO4 is used.

As a Ca compound, CaCl2. Any water-soluble Ca compound such as Ca(OH) may be used, but CaCj.

is preferred.

The addition rate of Ca2+ and phosphate ions is
/P (molar ratio) is preferably 1.5 to 1.7, preferably 1.67.

Although pure water or distilled water can be used as water for the reaction, it is preferable to use @pure water when producing high-quality apatite free of germs and fine particles. After dissolving the phosphate ion source in these waters, the carbon dioxide concentration in the water may be reduced by degassing with N, gas, or the like.

An aqueous solution of NaOH or KOH can be used as the alkali source.

As an ion-exchange fat, commercially available gel type Dowex is used.
SBR, Davrex SAR, microporous M
Strongly basic ion exchange resins such as SA-1-2 can be used.

Furthermore, since the apatite used in the present invention is intended as a ceramic raw material, it is often required to be fine, but if coarse crystals or granules are required, the apatite manufactured by the present invention may be Crystal growth may be achieved by circulating pure apatite as a seed crystal at high temperatures.

Incidentally, instead of using the ion exchange resin to reduce the total carbonate concentration in the calcium compound, the carbonate concentration may be reduced by an aeration method or a precipitation method.

Example 1 Add ammonium phosphate to pure water at 1000η/l
After dissolving the water so as to have the following properties and degassing it with N2 gas to reduce the carbon dioxide concentration in the water to below 51 Ni/day, the water was supplied to a 4 t sealed reaction vessel at a flow rate of 1 m3/day. -Strong basic ion exchange resin (DoveXSBR, 20-45 mesh)
A 7% Ca C12 solution (solvent: pure water) was added in an amount of 100 cc into a column packed with 40 tons, and S V = 1. It was filtered at 07:00, and the effluent was also fed to the sealed reaction vessel. Then, 1% NaOH aqueous solution was injected so that the pH of the reaction solution in the sealed reaction container became a5.\80mφX40
Apatite was produced by stirring and reacting with a blade of m at 15 r, p, n. The total carbonic acid concentration in the reaction solution at this time was 5η/ or less.

Example 2 Apatite was produced in the same manner as in Example 1, except that the Ca C/= solution was used as it was without passing it through the strong basic ion exchange Tochi fat tower. The total carbon dioxide concentration in the reaction solution at this time was 12111 i/l.

Example 3 Apatite was produced in the same manner as in Example 1 except that an open reaction vessel was used instead of a closed reaction vessel. The total carbon dioxide concentration in the reaction solution at this time was 18η/l.

Comparative Example 1 Apatite was produced in the same manner as in Example 1 except that tap water was used instead of pure water. The total carbon dioxide concentration in the reaction solution at this time was 507,117/l.

Comparative Example 2 Apatite was produced in the same manner as in Example 1, except that the Ca CL2 solution was used as it was without passing it through the strongly basic ion exchange resin tower, tap water was used instead of pure water, and an open reaction vessel was used. was manufactured. The total carbon dioxide concentration in the reaction solution at this time was 4
It was 0η/l.

The reaction products produced in Examples 1 to 3 and Comparative Examples 1 and 2 were extracted and dried at 100° C. for 2 hours in the presence of N2 gas, and then their compositions were analyzed. The analysis results are shown in Table-1.

Table 1 Example 4 Table 2 shows the composition of the product obtained by changing the carbon dioxide concentration by adding sodium bicarbonate into the reaction vessel in Example 1.

Table-2 From the results shown in Table-2, the total carbon dioxide concentration in the liquid is 20 m9/
It can be seen that the purity of the apatite produced improves when the

[Effects of the Invention] According to the present invention, highly pure apatite with a low content of CaCO2 and other impurities can be produced, and therefore a material suitable as a filler for various biological materials and chromatographs can be provided.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams of a reaction apparatus for carrying out the reaction of the present invention, respectively. Figure 1 is a schematic diagram of an apparatus using a closed reaction vessel, and Figure 2 is a schematic diagram of an apparatus using a fluidized reaction vessel. A schematic diagram of the device is shown. DESCRIPTION OF SYMBOLS 1... Phosphorous lv salt solution supply pipe, 2... Sealed reaction vessel, 2'... Fluid reaction vessel, 3... Stirrer, 4...
Alkaline solution supply pipe, 5... power ~ num solution supply pipe,
6...Strong basic ion exchange resin layer, 8...Apatite discharge pipe

Claims (1)

[Claims] 1. A method for producing hydroxyapatite by reacting phosphate ions in an aqueous solution containing phosphate ions with a calcium compound at pH 6 or higher, wherein the total carbonate concentration in the reaction solution is 20 mg/l. A method for producing high-purity hydroxyapatite, which is characterized by carrying out the reaction under the following conditions. 2. The method for producing high-purity hydroxyapatite according to claim 1, which uses a calcium compound solution passed through a strongly basic ion exchange resin layer. 3. The method for producing high-purity hydroxyapatite according to claim 1 or 2, wherein the reaction is carried out in a closed container. 4. The method for producing high-purity hydroxyapatite according to claim 1, 2 or 3, wherein the reaction is carried out under the following conditions at a total carbonate concentration of 10 mg/l in the reaction solution.