JPH09241019A - Method of synthesis of carbonated hydrocarmite - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a synthesis method capable of efficiently synthesizing a useful high purity carbonated hydrocarmite for a short time. SOLUTION: The synthesis method of the carbonated hydrocarmite is by mixing calcium hydroxide with a suspension prepared by mixing an alkali altuninate or aluminum hydroxide with a carbonate or a suspension prepared by mixing aluminum hydroxide or aluminum oxide, an alkali metal hydroxide with the carbonate to allow to react with each other. And an adsorbent consists essentially of the carbonated hydrocamite or a heat treated material of the carbonated hyddrocarmite or the precursor at 100-500 deg.C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for synthesizing carbonic acid hydrocalumite useful as an antacid agent for neutralizing or inactivating an acid, a rubber additive, an anion adsorbent, a resin additive, and the like. The present invention relates to the carbonic acid type hydrocalumite and an adsorbent using the same.

[0002]

2. Description of the Related Art Currently, antacids, rubber additives,
Hydrotalcites have been put to practical use as inorganic compounds useful as anion adsorbents and resin additives. Hydrotalcites have the chemical formula Mg ₆ Al ₁₂ (OH) ₁₆ (CO ₃ ) ・ 4H ₂
It is an inorganic layered compound represented by O 2 and is known to have excellent acid and anion adsorption capacities (Shigeo Miyata; Gypsum and lime; No.187, p333-33).
9,1983, JP-B-48-8394, and JP-A-61-115089.
No.). However, hydrotalcites are extremely expensive materials, and at present, the development of inexpensive materials to replace them is awaited.

On the other hand, as the inorganic layered compound similar to hydrotalcite, formula _{3CaO · Al 2 O 3 · CaX} 2 / m · nH
Hydrocalumites represented by ₂ O (where X is a monovalent or divalent anion, m is the valence of the anion, and n is an integer of 20 or less) are known (BUTTLER
FGet al ； Journal of The American Ceramic Societ
y; Vol.42, No.3, p121-126,1959). Hydrocalumites include nitric acid type, nitrite type, carbonic acid type, etc., depending on the type of X, and at present the industrial benefits have not been found as widely as hydrotalcites. . Among them, various methods for synthesizing nitric acid type or nitrite type hydrocalumite have been proposed (Japanese Patent Laid-Open No. 4-312058).
-154648, JP-A-7-33430, and JP-A-7-33430
7-33431, etc.). And, the industrial benefit of hydrocalumites is that these nitric acid type and nitrite type hydrocalumites have only been proposed as chloride ion scavengers for the purpose of preventing rust of the reinforcing bars in the reinforcing bar concrete. (Japanese Patent Laid-Open No. 4-154648).

On the other hand, as a method for synthesizing carbonate type hydrocalumite, a method of hydrating calcium aluminate and calcium carbonate or a method of reacting a calcium aluminate solution with a calcium hydroxide solution and sodium carbonate Have been proposed (Cement Technology Annual Report 15-54
And Turriziani, R. and Schippa, G.; Ricerca Sci; 27,3654,
1957). However, the method of hydrating calcium aluminate and calcium carbonate has a problem that it takes as long as 8 weeks to obtain a reaction product. In addition, the method of reacting a calcium hydroxide solution with a calcium hydroxide solution and sodium carbonate has a problem that the amount of the reaction product is very small.

As a result of earnest efforts, the inventors of the present invention have been able to produce carbonic acid-type hydrocalumite at a relatively low cost by a specific synthesis method, and have not seen industrial benefits until now. The inventors have found that the heat-treated product has an acid adsorbing action and an anion adsorbing action similar to hydrotalcite, and have completed the present invention.

[0006]

Means for Solving the Problems That is, the present invention relates to a suspension of aluminic acid alkali salt or aluminum hydroxide and a carbonate, and aluminum hydroxide or aluminum oxide, an alkali metal hydroxide, A method for synthesizing carbonic acid-type hydrocalumite, which comprises reacting calcium hydroxide with a suspension prepared by mixing calcium carbonate and calcium carbonate. Carbonic acid hydrocalumite, which is an adsorbent containing the carbonic acid hydrocalumite as an active ingredient,
The carbonate-type hydrocalumite or its precursor is added in an amount of 100 to 50
It is an adsorbent containing a heat-treated product obtained by heating at 0 ° C as an active ingredient.

The present invention will be described in detail below.

Hydrocalumite has the chemical formula 3CaO.Al.
₂ O ₃ · CaX _{2 / m} · nH ₂ O (where X is a monovalent or divalent anion, m is the valence of the anion, and n is an integer of 20)
The anions of X are limited to CO ₃ ²⁻ in the present invention, and the chemical formula is 3CaO · Al ₂ O ₃ · CaCO ₃ · 11H. ₂
It is represented by O and is sometimes referred to as calcium aluminate monocarbonate (hydrate) or calcium carboaluminate. In the present invention, the presence of impurities produced when synthesizing carbonic acid hydrocalumite (hereinafter referred to as HCC) is not particularly limited. For example, some calcium carbonate, calcium hydroxide, aluminum hydroxide, and calcium. It can be used even if an aluminate hydrate is produced as a by-product.

The alkali aluminate salt used in the present invention is represented by the chemical formula Al ₂ O ₃ .mR ₂ O (R is an alkali metal, and m is usually about 0.5 to 2). Include sodium aluminate, potassium aluminate, lithium aluminate, and the like, and in the present invention, one or more of these can be used.
In addition, some aluminate aluminates have water of crystallization in a range of 10 mol or less, and any of them can be used in the present invention. The amount of the alkali aluminate salt used is not particularly limited, and it is preferable to use it in the range of the CO ₃ / Al molar ratio in the suspension obtained by mixing the alkali aluminate salt and the carbonate. Aluminic acid alkali salt is usually
Use at a concentration of 0.1-2 mol / liter. If it is less than 0.1 mol / l, the amount of HCC synthesized will be small, and it will not necessarily be industrially beneficial. If it is more than 2 mol / l, the reaction liquid will be extremely viscous, making stirring and mixing difficult. There are cases.

The aluminum hydroxide used in the present invention is a general term for compounds represented by Al (OH) ₃ and Al ₂ O ₃ .H ₂ O, and either crystalline or amorphous can be used. . The amount of aluminum hydroxide used is not particularly limited, and may be used in a suspension prepared by mixing aluminum hydroxide and a carbonate, or in a suspension prepared by mixing aluminum hydroxide, an alkali metal hydroxide and a carbonate. It is preferably used in the range of CO ₃ / Al molar ratio in the suspension. Aluminum hydroxide is usually used at a concentration of 0.1 to 2 mol / liter.
If it is less than 0.1 mol / liter, the amount of HCC synthesized will be small, which is not necessarily industrially beneficial. At concentrations higher than 2 mol / liter, the reaction liquid will become extremely viscous, making stirring and mixing difficult. May be.

In the present invention, the combined use of aluminum hydroxide and alkali metal hydroxide is preferable from the viewpoint of accelerating the synthesis of HCC, and since the synthesis rate of HCC is increased, the time spent for synthesis can be reduced. In particular, it is preferable to use aluminum hydroxide by previously immersing it in an aqueous solution of an alkali metal hydroxide at 30 to 80 ° C, and immersing it in an aqueous solution of an alkali metal hydroxide at 40 to 60 ° C. It is more preferable to use it afterwards.

Aluminum oxide used in the present invention is Al
Compounds represented by ₂ O ₃ are collectively referred to, and either crystalline or amorphous can be used, and industrially, bauxite,
Clay materials and residual aluminum ash can be used.

In the present invention, the combined use of aluminum oxide and an alkali metal hydroxide is necessary from the viewpoint of accelerating the synthesis of HCC, and since the synthesis rate of HCC is increased, the time spent for synthesis is reduced. You can In the present invention, it is preferable to immerse aluminum oxide in an aqueous solution of alkali metal hydroxide in advance. Unless aluminum oxide is immersed in an aqueous solution of an alkali metal hydroxide, the rate of HCC synthesis may be extremely slow.
The temperature of the alkali metal hydroxide aqueous solution in which the aluminum oxide is immersed is not particularly limited, but is usually 30 to
80 degreeC is preferable and 40-60 degreeC is more preferable.

Here, the alkali metal hydroxide is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like, and one or more of these are used. Is possible. The amount of alkali metal hydroxide used in combination with aluminum hydroxide or aluminum oxide is not particularly limited, but usually 10 to 200 parts by weight relative to 100 parts by weight of aluminum hydroxide or aluminum oxide. Preferably 50-
More preferably 150 parts by weight. If it is less than 10 parts by weight, the amount of HCC synthesized may be small, or unreacted aluminum oxide may remain. Even if it is used in excess of 200 parts by weight, further increase in effect cannot be expected.

The carbonates used in the present invention include alkali metal carbonates such as sodium carbonate, potassium carbonate, lithium carbonate and potassium sodium carbonate, and alkali metal bicarbonates such as sodium bicarbonate, potassium bicarbonate and lithium bicarbonate. Examples thereof include carbonates and ammonium salts such as ammonium carbonate and ammonium bicarbonate, and one or more of these can be used. Further, among these carbonates, there are anhydrous salts and hydrated salts, but any of them can be used in the present invention. The amount of the carbonate used is not particularly limited, and in a suspension prepared by mixing an aluminate alkali salt or aluminum hydroxide with a carbonate, aluminum hydroxide or aluminum oxide, an alkali metal hydroxide, And CO _{3 in} suspension mixed with carbonate
It is preferably used in the range of / Al molar ratio. Carbonate is usually used at a concentration of 0.1 to 2 mol / liter. 0.
If it is less than 1 mol / liter, the amount of HCC synthesized will decrease,
It is not necessarily industrially useful, and at a high concentration exceeding 2 mol / liter, the viscosity of the reaction solution becomes extremely strong, and stirring and mixing may become difficult.

The calcium hydroxide used in the present invention is not particularly limited, and all reagents and industrial raw materials can be used, and it can be used in powder form or slurry form, and is an industrially inexpensive material. In the present invention, it is preferable to use a slurry of calcium hydroxide in terms of dispersibility. Also,
Although calcium oxide can be used in the present invention, it is preferable to use calcium hydroxide in terms of safety. The amount of calcium hydroxide used is not particularly limited, and a suspension of aluminic acid alkali salt or aluminum hydroxide and carbonate mixed, also, aluminum hydroxide or aluminum oxide, an alkali metal hydroxide, It is preferable to use it in the range of the Ca / Al molar ratio in the reaction system in which calcium carbonate and a suspension mixed with and carbonate are mixed. Calcium hydroxide is usually used at a concentration of 0.1 to 2 mol / liter. If it is less than 0.1 mol / l, the amount of HCC synthesized will be small, and it will not necessarily be industrially beneficial. If it is more than 2 mol / l, the reaction liquid will be extremely viscous, making stirring and mixing difficult. There are cases.

In the method for synthesizing HCC according to the present invention, a suspension of alkali metal aluminate or aluminum hydroxide and carbonate, and aluminum hydroxide or aluminum oxide, alkali metal hydroxide, and carbonate are used. It is possible to mix and react with a suspension obtained by mixing with calcium hydroxide, or to disperse calcium hydroxide in water in advance and mix them in the form of slurry to react.
Alkali aluminate or aluminum hydroxide and carbonate, and aluminum hydroxide or aluminum oxide, alkali metal hydroxide, and carbonate are mixed first to prepare a suspension, and then calcium hydroxide is added. It is preferable to mix and react. When alkali metal aluminate or aluminum hydroxide and calcium hydroxide are mixed and then carbonate is mixed and reacted, aluminum hydroxide or aluminum oxide, alkali metal hydroxide, and calcium hydroxide are mixed. If a carbonate is then mixed and allowed to react, one type of calcium aluminate hydrate called hydrogarnet or calcium carbonate is likely to be produced.Also, after mixing carbonate and calcium hydroxide, an aluminate alkali salt is used. Or with aluminum hydroxide,
Alternatively, when aluminum hydroxide, aluminum oxide, or an alkali metal hydroxide is mixed and reacted, calcium carbonate is likely to be generated, and the purity of HCC may be deteriorated.

In the present invention, the reaction temperature is preferably maintained at about 30 to 80 ° C, more preferably 40 to 70 ° C. If the reaction temperature is less than 30 ° C, the reaction rate is extremely slow, which is not beneficial, and the residual amount of calcium hydroxide is remarkably large, and the crystallinity of the resulting HCC is remarkably low. If it exceeds 80 ° C, the risk of bumping tends to occur There is.

Further, in the present invention, after the reaction, it is preferable that the reaction be left for 1 hour or more to be aged, and more preferably 4 hours or more. When the aging is not performed, the crystallinity of the obtained HCC is low, and unreacted calcium hydroxide may remain.

In the present invention, a mixed suspension of alkali aluminate or aluminum hydroxide and carbonate, and a mixed suspension of aluminum hydroxide or aluminum oxide, alkali metal hydroxide and carbonate are used. The CO ₃ / Al molar ratio is preferably 0.7 or less, more preferably 0.5 or less. If it exceeds 0.7, the amount of by-produced calcium carbonate may increase.

On the other hand, a suspension prepared by mixing an alkali aluminate salt or aluminum hydroxide with a carbonate, and a suspension prepared by mixing aluminum hydroxide or aluminum oxide, an alkali metal hydroxide and a carbonate. The Ca / Al molar ratio in the reaction system in which calcium hydroxide is mixed is preferably 4 or less, more preferably 2 or less. If the Ca / Al molar ratio exceeds 4, unreacted calcium hydroxide may remain.

Although the HCC synthesized in the present invention can be used as an adsorbent as it is, 100% of HCC or a precursor of HCC which is a gel-like precipitate before crystallization of HCC is used.
The heat-treated product obtained by heating at ~ 500 ° C is effective as an adsorbent. HCC is crystalline and can be easily identified by X-ray diffractometry, but the structure of this heat-treated product changes with temperature and retains crystallinity even after dehydration up to about 100 to 200 ° C. But 200
It becomes amorphous at ˜500 ° C. and cannot be specified by the X-ray diffraction method. In the present invention, any of these can be used as an adsorbent, but an amorphous heat-treated product heated in the range of 200 to 500 ° C. is preferable because it has the best adsorption ability.

[0023]

EXAMPLES The present invention will be described in more detail by way of examples.

Example 1 A suspension prepared by dissolving an alkali aluminate salt and a carbonate shown in Table 1 in 1 liter of water and a suspension prepared by dispersing calcium hydroxide shown in Table 1 in 1 liter of water were prepared. After mixing with the slurry, warm to 60 ° C and age for 4 hours, then age
The precipitate was filtered, washed with water, and dried at 60 ° C to obtain a synthetic product. The obtained synthetic product was identified by the powder X-ray diffraction method (XRD). The results are also shown in Table 1. For comparison, the results of simultaneously mixing each material of alkali aluminate, carbonate, and calcium hydroxide with water are also shown.

<Materials used> Alkali aluminate α: sodium aluminate, first-grade reagent, Al ₂ O ₃ · 1.5Na ₂ O · 4.7H ₂ O Alkali acid aluminate β: potassium aluminate, reagent 1
Grade, Al ₂ O ₃ · 1.2Na ₂ O · 3H ₂ O hydrate Carbonate a: sodium carbonate, first grade reagent Carbonate b: sodium carbonate, first grade reagent, 10 hydrate Carbonate c: sodium hydrogen carbonate , Reagent first grade carbonate d: potassium carbonate, reagent first grade carbonate e: lithium carbonate, reagent first grade carbonate f: ammonium hydrogen carbonate, reagent first grade calcium hydroxide: reagent first grade water: tap water

[0026]

[Table 1]

Example 2 A suspension prepared by dissolving aluminum hydroxide and carbonate shown in Table 2 in 1 liter of water, and a slurry prepared by dispersing calcium hydroxide shown in Table 2 in 1 liter of water. After stirring for 30 minutes each and mixing, warming to 60 ℃, aging for 24 hours with stirring, after aging, precipitates are filtered, washed with water, dried at 60 ℃ Obtained. The resulting compound was identified by XRD. The results are also shown in Table 2. In addition,
For comparison, the results of simultaneously mixing each material of aluminum hydroxide, carbonate, and calcium hydroxide with water are also shown.

<Materials used> Aluminum hydroxide: first-grade reagent

[0029]

[Table 2]

Example 3 A suspension prepared by dissolving 1 mol of aluminum hydroxide, 0.5 mol of alkali metal hydroxide shown in Table 3 and 0.5 mol of carbonate a in 1 liter of water and 2 mol of calcium hydroxide. The slurry prepared by dispersing in 1 liter of water was stirred for 30 minutes and then mixed, heated to 60 ° C. and aged for 3 hours with stirring. After aging, the precipitate was filtered and washed with water. , Dried at 60 ° C. to obtain a synthetic product. The obtained compound was identified by XRD. The results are also shown in Table 3. For comparison,
Aluminum hydroxide, alkali metal hydroxide, carbonate,
Also, the results when each material of calcium hydroxide and water are simultaneously mixed are shown.

<Materials used> Alkali metal hydroxide a: sodium hydroxide, first grade reagent Alkali metal hydroxide b: potassium hydroxide, first grade reagent alkali metal hydroxide c: lithium hydroxide, first grade reagent

[0032]

[Table 3]

Example 4 A suspension prepared by dissolving 0.5 mol of aluminum oxide, an alkali metal hydroxide shown in Table 4 and a carbonate in 1 liter of water, and calcium hydroxide shown in Table 4 in 1 liter of water. And the slurry prepared by dispersing in 30 minutes each, and then mixed, heated to 60 ℃, aged for 24 hours while stirring,
After aging, the precipitate was filtered, washed with water and dried at 60 ° C to obtain a synthetic product. The resulting compound was identified by XRD. The results are also shown in Table 4. For comparison, the results of simultaneously mixing the materials of aluminum oxide, alkali metal hydroxide, carbonate, and calcium hydroxide with water are also shown.

<Materials used> Aluminum oxide: Reagent first grade

[0035]

[Table 4]

Example 5 A suspension prepared by dissolving 0.5 mol of alkali aluminate α and 0.7 mol of carbonate a in 1 liter of water and 2 mol of calcium hydroxide in 1 liter of water Using HCC synthesized in the same manner as in Example 1 except that the prepared slurry was mixed, various adsorbents shown in Table 5 were prepared,
A confirmation test of the adsorption capacity was carried out. 1 g of prepared adsorbent
Was immersed in a 0.5 mol / liter saline solution, left standing for 24 hours while stirring with a magnetic stirrer, and then filtered to perform solid-liquid separation. The solid phase was thoroughly washed with pure water to remove the attached chloride ions. The chloride ion concentration of the separated liquid phase and the solid phase were identified. The results are also shown in Table 5.

<Material used> Adsorbent A: HCC Adsorbent B: HCC heat treated product at 100 ° C Adsorbent C: HCC 200 ° C heat treated product Adsorbent D: HCC 300 ° C heat treated product Adsorbent E: HCC 500 ° C Heat treated product Adsorbent F: Commercial hydrotalcite Adsorbent G: Commercial hydrotalcite heat treated product at 300 ° C

<Measurement method> Liquid phase analysis: Chloride ion concentration, ammonium thiocyanate titration, Forhardt's method Solid phase analysis: Identification of compounds by XRD, elemental analysis of chlorine by SEM-EDS

[0039]

[Table 5]

Example 6 1 g of the various adsorbents prepared in Example 5 was added to 100 ml of an acetic acid aqueous solution prepared by adding 0.1 N acetic acid dropwise to 1 liter of pure water to adjust the pH to 4, and stirring for 30 minutes. Was measured. Table 6 shows the results.

<Materials used> Acetic acid: Reagent first grade

[Table 6]

Example 7 1 g of each adsorbent prepared in Example 5 was put in 100 ml of pure water, stirred for 30 minutes, solid-liquid separated, and the solid was dried at 40 ° C. to measure the weight increase amount. In addition, the solid identification
It was done by RD. Table 7 shows the results.

[0043]

[Table 7]

[0044]

INDUSTRIAL APPLICABILITY The synthetic method of the present invention is industrially useful, the time spent for the synthesis is short, the efficiency is high, and the obtained H
It has effects such as high purity of CC. In addition, H of the present invention
CC and its heat-treated products are excellent as an adsorbent for acids, anions, water, etc., and are industrially useful because they are cheaper than conventional adsorbents.

Claims (7)

[Claims] 1. A method for synthesizing carbonate-type hydrocalumite, which comprises mixing a suspension prepared by mixing an aluminate alkali salt and a carbonate with calcium hydroxide to react them. 2. A method for synthesizing carbonate-type hydrocalumite, which comprises mixing a suspension prepared by mixing aluminum hydroxide and a carbonate with calcium hydroxide and reacting them. 3. A method for synthesizing carbonate-type hydrocalumite, which comprises mixing a suspension prepared by mixing aluminum hydroxide, an alkali metal hydroxide and a carbonate with calcium hydroxide to react them. 4. A method for synthesizing carbonic acid hydrocalumite, which comprises mixing a suspension prepared by mixing aluminum oxide, an alkali metal hydroxide, and a carbonate with calcium hydroxide to react them. 5. Carbonic acid-type hydrocalumite synthesized by the method for synthesizing carbonic acid-type hydrocalumite according to any one of claims 1 to 4. 6. An adsorbent containing the carbonic acid hydrocalumite according to claim 5 as an active ingredient. 7. An adsorbent containing a heat-treated product obtained by heating the carbonic acid hydrocalumite or its precursor according to claim 5 at 100 to 500 ° C. as an active ingredient.