JPH05146673A - Adsorbent - Google Patents

Abstract

PURPOSE:To provide an adsorbent useful in removing harmful substances such as radioactive substance and phosphate ion from domestic or industrial waste water. CONSTITUTION:A method for producing the absorbent comprises mixing together a composition containing a hydrate ferrite of a tetravalent metal such as titanium, zirconium and tin and a water-insoluble phosphate of a tetravalent metal such as titanium, zieconium and tin and a thermosetting resin in an amount (by weight) of 1/10-1 time the aforesaid composition and hardending the resulting mixture. This absorbent provides a method whereby harmful substances such as various ions and radioactive substances can efficiently be adsorbed thereon. It is also adaptable to the various kinds of devices for absorbing the harmful substances and has the advantage of being low in manufacturing costs. Moreover, recovery of the adsorbed substances is possible.

Description

Detailed Description of the Invention

[0001]

The present invention relates to domestic wastewater, industrial waste liquid,
The present invention relates to a novel adsorbent and an adsorption method useful for adsorbing harmful substances such as industrial wastes stored.

[0002]

2. Description of the Related Art With the development of the nuclear industry, low and medium level radioactive wastes are being emitted from nuclear power plants and the like. In recent years, pollution by such low and medium level radioactive waste has become an important issue as an environmental problem.

Conventionally, as a method for removing radioactive substances such as uranium, an adsorption method, a bubble separation method, a solvent extraction method and the like have been proposed. Among them, the adsorption method is considered to be the best method. There is. In this adsorption method, the performance of the adsorbent used is a problem. Examples of such adsorbents include hydrous titanium oxide, galena, manganese oxide, zirconium phosphate, and further inorganic adsorbents such as hydrous titanium oxide supported on activated carbon or alumina, acidoxime type chelate resins and hexacarboxylic acid. An organic adsorbent such as is used.

However, conventional adsorbents have a low adsorption capacity, and organic adsorbents also have a problem in heat resistance, which makes it difficult to apply them to high temperature nuclear power plant wastewater.

Japanese Unexamined Patent Publication (Kokai) No. 54-128994 proposes a magnetic adsorbent for collecting uranium, which comprises an iron oxide and a sparingly soluble hydrous oxide such as aluminum, manganese, zinc, tin or zirconium. This adsorbent is considered to be in powder form. However, when performing adsorption operation with this powdery adsorbent, even if magnetic separation is applied, solid-liquid separation is difficult. In addition, there remains a problem that the adsorption force is not sufficient.

Further, Japanese Patent Laid-Open No. 57-50543 proposes a metal hydrate adsorbent for removing phosphate ions contained in domestic wastewater.

However, at present, no technology has been developed which is satisfactory for removal of radioactive waste at a medium or low level.
Further, although an adsorbent formed of a granular or fibrous molded article has been proposed, a material having a large mechanical strength or adsorption capacity has not been obtained.

On the other hand, as for the treatment of used radioactive waste, a method of hardening it with concrete and burying it underground or in the soil is currently used. However, there is concern about radioactive contamination of the surrounding environment due to deterioration of concrete during long-term storage. The development of a highly safe and high-performance radioactive adsorbent that can be used as an immobilizing agent for preventing the leakage of radioactive substances has not yet been achieved.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides a novel adsorbent and an adsorption method having excellent adsorption ability for harmful substances. In particular, the present invention provides a novel adsorbent excellent in adsorption of radioactive substances and an adsorption method.

[0010]

Means for Solving the Problems The present inventors have found that a mixture of metal hydrous ferrite and phosphate adsorbs a radioactive substance, and further studied to complete the present invention. I arrived.

That is, the present invention is an adsorbent containing a tetravalent metal hydrous ferrite and a water-insoluble tetravalent metal phosphate, and a method for adsorbing harmful substances.

As the tetravalent metal, any tetravalent metal may be used, but Group 4 elements are preferable. Specifically, titanium,
Zirconium, thorium, hafnium, germanium,
Examples include tin and lead. Of these, titanium, zirconium and tin are preferable. Especially, titanium is preferable.

The above-mentioned hydrated ferrite salt of tetravalent metal and water-insoluble phosphate salt of tetravalent metal are usually water-insoluble, and those which form an amorphous salt are preferable. Further, the hydrous ferrite and the water-insoluble phosphate may be composed of one kind of metal, or may be composed of two or more kinds of metals. Examples of preferable hydrous ferrite of tetravalent metal include hydrous ferrous acid of titanium and hydrous ferrous acid of zirconium. Preferred water-insoluble phosphates of tetravalent metals include water-insoluble phosphates of titanium (for example, Ti
(HPO ₄ ) ₂・ nH ₂ O (n = 0, 0.5, 1, ₂ ) etc.), a water-insoluble phosphate of zirconium (for example, Zr (HPO ₄ ) ₂・ nH ₂ O (n = 0, 1, 2), Zr
_{(KPO 4) 2 · 3H 2} O , etc.), tin water-insoluble phosphate (Sn (HPO ₄₎
H ₂ O etc.) and the like.

The compounding ratio of the hydrous ferrite of tetravalent metal and the water-insoluble phosphate of tetravalent metal is 300: 1 to 1: 1, preferably 200: 1 to 1 in terms of the respective metal atomic ratios. 3:
It is 1.

The adsorbent of the present invention is manufactured by the following method.

In a solution containing a metal ion prepared by dissolving a tetravalent metal salt, at a pH of 4 or less, phosphoric acid or phosphorus corresponding to 0.01 to 0.5 times the molar amount of the tetravalent metal ion is obtained. Acid salts or mixtures thereof are added to form some of the initially contained metal ions as water insoluble phosphates. Then, after adding a ferrous salt corresponding to about 0.2 to 11 times the molar amount of the remaining metal ions, an alkali is added to adjust the pH of the solution to about 6 or more, preferably about 7 to 12. Hold. After that, if necessary, the temperature of the solution is adjusted to about 30 to 100 ° C., and then an oxidizing gas (air, oxygen gas, ozone, etc.) is blown in, or an oxidant (hydrogen peroxide, etc.) is added to the solution, whereby A mixed precipitate of hydrous ferrite of valent metal and water-insoluble phosphate of tetravalent metal is formed. Alternatively, the tetravalent metal hydrous ferrite and the tetravalent metal water-insoluble phosphate may be separately produced according to the above-mentioned production method.

The precipitate obtained as above is filtered off,
After washing with water, it is dried. Drying is performed by air drying or in a temperature range of about 100 ° C. or lower, preferably about 50 ° C. or lower for about 1 to 50 hours. When the hydrous ferrite of tetravalent metal and the water-insoluble phosphate of tetravalent metal are prepared separately, they may be mixed later as a dried product, or both may be mixed before drying, and then Alternatively, it may be subjected to a drying step. Preferably, the production method for producing a mixed precipitate is simple, and the characteristics of the obtained adsorbent are excellent.

As described above, an aqueous liquid containing ions of a tetravalent metal can be used for producing the adsorbent. Various water-soluble metal compounds are used for the preparation of this aqueous liquid. Examples of such water-soluble metal compounds include metal compounds such as various metal salts and metal alkoxides.
As the metal salt, in addition to a normal metal salt (normal salt), an acidic salt, a hydroxide salt, an oxide salt (oxy salt), and other double salts and complex salts may be used. Further, the compound may be insoluble when the pH of the aqueous solution is near neutral, or may be a compound which is soluble in an acidic solution. Specifically, the following are mentioned.

(1) Metal chloride, fluoride, iodide,
Halides such as bromide: TiCl ₄ , SnCl ₄ , Zr
Cl ₄ , Na ₂ [SnFe], K ₂ [SnF ₆ ], K ₂ [SnCl
₆ ], ThCl ₄ , PbCl ₄ , GeCl ₄ , etc.

(2) Sulfate, ammonium sulfate, and other sulfates (inorganic acid salts): Zr (SO ₄ ) ₂ , Sn (SO ₄ ) ₂ ,
Th (SO ₄ ) ₂ , Pb (SO ₄ ) ₂ , Ti (SO ₄ ) _{2 and the} like.

(3) Nitrate (inorganic acid salt): Sn (NO ₃ ) ₄ ,
Th (NO ₃ ) ₄ , Zr (NO ₃ ) ₄ , Ti (NO ₃ ) _4, etc.

(4) Organic acid salts such as acetate, formate and oxalate: (CH ₃ CO ₂ ) ₄ Zr, (C ₂ O ₄ ) ₂ Th, etc.

(5) Oxymetal salt (oxymetal salt in the form of halide, inorganic acid salt, organic acid salt): ZrOCl ₂ ,
ZrOSO, ThOCl ₂ , TiOSO ₄ , ZrO (N
_{O 3) 2, ZrOCO 3,} (NH 4) 2 ZrO (CO 3) 2, ZrO
(CH ₃ CO ₂ ) ₂ etc.

(6) Metal alkoxides: Zr (OC
Etc. _{H 3) 4, Ti (OCH} 3) 4.

These metal salts are usually about 0.05 to 2.0.
Used as a molar solution.

Among the above tetravalent metal salts, preferred are metal salt dials of titanium, zirconium and tin. Preferred specific examples thereof include titanium tetrachloride (TiCl ₄ ), titanium sulfate (Ti (SO ₄ ) ₂ ), titanyl sulfate (TiOSO ₄ ) zirconium oxychloride (ZrOCl ₂ · 8H ₂ O), zirconium tetrachloride (ZrC).
l _4), zirconium nitrate _{(Zr (NO 3) · 4H} 2 O), zirconium sulfate _{(Zr (SO 4) 2 ·} 4H 2 O), zirconium acetate (Zr (CH ₃ C
OO) ₄ ), tin tetrachloride (SnCl ₄ ), tin nitrate (Sn (N
O ₃ ) ₄ ), tin sulfate (Sn (SO ₄ ) ₂ ) and the like.

Examples of the ferrous salt include ferrous sulfate (FeSO ₄ .7H ₂ O), ferrous nitrate (Fe (NO ₃ ) ₂ .6H ₂ O), ferrous chloride (FeCl ₂ ), etc. Can be given. These ferrous salts are usually added in solid form, but they may be added in solution form.

Examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, sodium carbonate, organic amines such as triethanolamine, and the like. These are usually used in an aqueous solution of about 5 to 20% by weight.

Examples of the oxidizing gas include air, oxygen gas, ozone and the like. When this is blown, the time is usually about 1 to 3 hours, although it depends on the type of oxidizing gas.

As the oxidizing agent, for example, hydrogen peroxide, sodium hypochlorite, potassium hypochlorite, etc. are used.

The preferred phosphoric acid compound used to form the insoluble phosphate is phosphoric acid or a salt thereof. Specific examples of the salt include sodium phosphate (first, second, third),
Examples include potassium phosphate (first, second, third), ammonium phosphate (first, second, third) and the like.

The hydrated ferrite or the composition of the hydrated ferrite and the water-insoluble phosphate may be in any form, but it may be about 1
The particles having a particle size of 50 μm or less are particularly preferable in terms of the mixing operation with a resin described later and the adsorption performance. Especially 0.1-
The range of 150 μm is preferable.

In the present invention, the adsorbent composition of hydrous ferrite and water-insoluble phosphate obtained in this way may be used as it is, or 1/10 to 1 times that. An adsorbent excellent in handling can be obtained by mixing an amount, preferably about 1/5 to 1 times (weight) of the thermosetting resin and the adsorbent composition. When the amount of this resin exceeds about 1 time, the mechanical strength of the adsorbent increases, but the adsorption performance decreases. On the other hand, when the ratio of the resin is small and less than about 1/10 of the above amount, the adsorption performance is excellent, but the mechanical strength may decrease, so it is not suitable for industrial use. There is.

Examples of the thermosetting resin used for producing such an adsorbent include unsaturated polyester resin, polyurethane resin, phenol resin, urea resin, melamine resin and the like. Preferred are unsaturated polyester resins and polyurethane resins.

The unsaturated polyester resin may be any known unsaturated polyester resin. Specifically, a dicarboxylic acid having a double bond in the molecule (maleic acid or its anhydride, fumaric acid, etc.) and a divalent alcohol (ethylene glycol, propylene glycol, etc.)
An unsaturated cotton-like polyester obtained by condensing and with a known method is a vinyl type monomer (styrene, chlorostyrene, methyl methacrylate, diallyl phthalate, etc.)
It can be dissolved in. The dicarboxylic acid is
It may be modified with an unsaturated dicarboxylic acid or a saturated dicarboxylic acid such as fumaric acid, itaconic acid, phthalic anhydride, adipic acid, het acid, sebacic acid, isophthalic acid, and terephthalic acid. The dihydric alcohol may also be modified with a glycol such as bisphenol A, hydrogenated bisphenol A, butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, trimethylene glycol, hexanediol or pentanediol.

As the polyurethane resin, any known polyurethane resin can be used. Specifically, a polyol having two or more hydroxyl groups in the molecule (polyether polyol, polyester polyol, polymer polyol, butadiene-based polyol, polycarbonate diol, castor oil, etc.) and polyisocyanate having two or more isocyanate groups in the molecule (Tolylene diisocyanate (TDI), diphenylmethane diisocyanate (pure MDI), naphthalene diisocyanate (NPI), dimethyldiphenyl diisocyanate (T
ODI), polymethylene polyphenyl polyisocyanate (crude MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMD)
I), isophorone diisocyanate (IPDI), etc.)
Examples thereof include those obtained by reacting and with a known method.

In this polyurethane resin, the isocyanate groups contained in the resin are usually reacted with each other by heat or a crosslinking agent, or the isocyanate groups are reacted with, for example, ethylene glycol, propylene glycol, butanediol, glycerin, hexanetriol, trimethylol. Reacts with propane and water to form thermosetting resin.

When the above-mentioned unsaturated polyester resin or polyurethane resin is liquid at room temperature, it can be used as it is.

On the other hand, when it is in a solid state, hydrocarbons (butane, hexane, cyclohexane, benzene,
Toluene), halogenated hydrocarbons (methylene chloride, chloroform, trichloroethane, chlorobenzene, etc.), alcohols (methanol, ethanol, propanol, etc.), ketones (acetone, methyl ethyl ketone, etc.), esters (methyl acetate, ethyl acetate, etc.) , An organic solvent such as ether (ethyl ether, dioxane, tetrahydrofuran, etc.) or a mixture thereof, or heating at a temperature of about 90 ° C. or lower to liquefy.

As a concrete method of mixing with the above-mentioned thermosetting resin, for example, hydrous ferrite or a mixture thereof and water-insoluble phosphate and resin are stirred at a high speed in a container with a stirrer. Examples thereof include a mixing method, a batch-type or continuous mixing method using a kneader, and a batch-type or continuous mixing method using an apparatus used for mixing solid-liquid.

Upon mixing, if necessary, for unsaturated polyester resins, for example, benzoyl peroxide (BPO), lauroyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, t-
A catalyst such as butyl peroxide isobutyrate or a curing accelerator such as cobalt naphthenate, manganese naphthenate, dimethylaniline, phenylmorpholine, diethanolaniline, panadyl acetylacetonate or phenylphosphinic acid may be added in an appropriate amount.

After mixing the resin and the adsorbent composition, the resin is cured. The curing operation is usually carried out at room temperature, but if the curing time is long, it may be heated to about 30 to 90 ° C.

If necessary, the cured product may be crushed with a hammer mill, roll crusher or the like and then granulated. In that case, the particle size is about 3-120 mesh,
It is preferably about 24 to 80 mesh.

Further, the mixture is continuously extruded in a cylindrical shape on a device such as a steel belt conveyor,
After holding the residence time until the mixture hardens on the steel belt conveyor, the hardened columnar adsorbent may be cut to an appropriate length. Using the small particles of the mixture as the core, a plate-type rolling granulator or a centrifugal fluidized coating granulator is used to simultaneously supply hydrous ferrite and liquid resin to form a spherical adsorbent by coating granulation. May be.

Further, as such an adsorbent, the above-mentioned water-insoluble phosphate of a tetravalent metal can be effectively used as an adsorbent. This production may be carried out according to the production method of the composition described above. For example, in a solution containing a metal ion prepared by dissolving a tetravalent metal salt such as titanium, zirconium and tin, phosphoric acid, phosphate corresponding to 2 equivalents or more at pH 4 or less with respect to the metal ion, or These mixtures may be added so that a part of the initially contained metal ions may be produced as water-insoluble phosphoric acid crystals. Further, similarly to the above-mentioned composition, it can be mixed and cured with a thermosetting resin so as to have excellent mechanical strength.

The adsorbent of the present invention obtained as described above can be used as an adsorbent for various radioactive substances.

Such radioactive substances are the following radioactive nuclides themselves or substances containing the nuclides, and these nuclides are present as ions in solution or dissolved as compounds, and are included in gas. It is possible to apply to what has been. In particular, it is effective for those existing in the liquid as ions such as uranyl ion (UO ₂ ⁺⁺ ). It is also useful for recovery and reuse of ¹⁴⁷ Pm.

Radionuclides: (medical / natural science fields) ³ H, ¹⁴ C, ²² Na, ²⁴ Na,
³² P, ³⁵ S, ³⁶ Cl, ⁴² K, ⁴⁵ Ca, ⁵¹ Cr, ⁵⁴ Mn,
⁵⁵ Fe, ⁵⁹ Fe, ⁵⁷ Co, ⁵⁸ Co, ⁶⁰ Co, ⁶⁴ Cu, ⁶⁵
Zn, ⁶⁷ Ga, ⁸⁶ Rb, ⁸⁵ Sr, ⁸⁹ Sr, ⁹⁰ Sr, ⁹⁵ Z
r, ⁹⁹ Mo, ^99m Te, ¹⁰⁶ Ru, ¹¹⁰ Ag, ¹¹¹ In,
¹²³ I, ¹²⁵ I, ¹³¹ I, ¹³³ Xe, ¹³⁴ Cs, ¹³⁷ Cs,
²⁰¹ Tl, ¹⁴⁰ La, ¹⁴⁴ Ce, etc. (nuclear fuel) U, Th, Pu, etc. (α radiator) ²⁴¹ Am, ²¹⁰ Po, ²²⁶ Ra, ²⁵² Cf, etc. (luminescent coating) ¹⁴⁷ Pm, etc. The method for adsorbing a radioactive substance is carried out by bringing the adsorbent into contact with a substance containing a radioactive substance. For example, in the batch adsorption method, a predetermined amount of the adsorbent of the present invention is added to a solution containing a radioactive substance, and the mixture is stirred at room temperature or while heating, and the adsorbent and the solution are sufficiently contacted for a certain period of time. After the adsorption is completed, the solid (adsorbent) -liquid (solution) is separated. As the method, an ordinary filtration method or magnetic separation method can be applied. Further, if necessary, the adsorbent and the desorbed liquid may be contacted with each other to desorb and collect the adsorbed radioactive substance.

In the continuous adsorption method, an adsorbent can be packed in an adsorption column and the radioactive substance can be adsorbed through a solution containing the radioactive substance.

In particular, since the adsorbent of the present invention mixed with resin is excellent in mechanical strength, the adsorbing operation should be performed by a moving bed type or fluidized bed type adsorbing device other than the fixed bed type adsorbing device. Is also possible.

In the case of the continuous adsorption method, when the radioactive substance breaks through, water flow is stopped and the adsorbed radioactive substance is desorbed and recovered by an appropriate desorbing liquid, and the adsorbent is regenerated and then passed through again. The operation of starting the water is taken.

In this case, various kinds of desorbed liquid are used depending on the nature and type of the adsorbed radioactive substance. For example,
An acid (diluted hydrochloric acid or the like in the case of ¹⁴⁷ Pm), alkaline, salts (sodium carbonate, ammonia carbonate, sodium hydrogencarbonate or the like in the case of uranium), and an organic solvent (methanol, acetone, etc.) are used. Such desorption / recovery operation is particularly effective when about 3 ppb uranium present in seawater is adsorbed / desorbed / recovered and used as a yellow cake for nuclear fuel. It is also effective in recovering and recycling ¹⁴⁷ Pm used in luminous paints. As described above, it is effective for recovery and reuse of radionuclides such as uranium, sodium, cobalt, strontium, cesium, cerium, and promesium.

Further, by adding 5 to 50% by weight of the present adsorbent to the mortar used for enclosing the used radioactive waste in the container, the container accompanying mortar deterioration during long-term storage is added. It is possible to prevent leakage of radioactive material to the outside.

The adsorbent of the present invention may be used by adding another adsorbent. Examples thereof include silica gel, zeolite, sepiolite, aluminosilicate compounds, activated alumina, activated carbon and the like. In particular, when a large amount of alkaline earth metal is present, the addition of zeolite is effective.

[0055]

The adsorbent of the present invention can be used for adsorbing various anions and cations. It can also be used for phosphate ion adsorption as a eutrophication measure for lakes and the like.

It can also be used as an adsorbent for radioactive substances. Especially, ¹⁴⁷ Pm and uranyl ion (UO ₂
⁺⁺ ) is excellent in the adsorption capacity for radioactive substances, etc., and can be used as an adsorption treatment agent in radioactive waste or an adsorbent for recovering uranium in seawater. Furthermore, the adsorbent of the present invention can be magnetically separated, and the adsorbent can be easily solid-liquid separated.

Further, since it has excellent resistance to chemicals such as acids and alkalis, it does not deteriorate even if it is repeatedly desorbed or adsorbed, and it can be repeatedly used for a long time. In particular, hydrated lead ferrate forms a crystal lattice of a stable compound, and titanium, zirconium or tin atoms enter the position where the iron atom of the lattice composed of the added ferrous salt should occupy, Since it is presumed that a solid solution is formed, these metals have the advantage that they are stable and difficult to elute.

The adsorbent mixed with the resin of the present invention is a simple composition in which a composition containing a hydrous ferrite and a water-insoluble phosphate is simply mixed with a thermosetting resin to cure the composition. Since it is manufactured by operation, it has an advantage of low manufacturing cost. Since this adsorbent has excellent mechanical strength, it withstands industrial use conditions, and especially when performing adsorption operations, it can be applied not only to fixed bed adsorption equipment but also to moving bed and fluidized bed adsorption equipment. not useable.

[0059]

EXAMPLES The present invention will be described more concretely with reference to the following examples.

Example 1 Zr Oxychloride 0.055 m
1 liter of ol aqueous solution is prepared. This solution contains 5.005 gr of metal ions as Zr. A 15% aqueous phosphoric acid solution corresponding to 0.49 gr (0.005 mol) of phosphoric acid is added to this aqueous solution with stirring.
This amount of phosphoric acid corresponds to about 0.09 times the molar amount of Zr. At this time, white zirconium phosphate crystals are formed with the addition of the phosphoric acid aqueous solution. After adding the phosphoric acid aqueous solution, the mixture is stirred at room temperature for 60 minutes. The pH at this time was 1.0 or less.

Next, 27.8 gr of ferrous sulfate crystals (FeSO ₄ .7H ₂ O) are added to this solution and dissolved with stirring. This amount corresponds to 0.1 mol as iron ion. Subsequently, a 15% by weight sodium hydroxide solution is added dropwise to this aqueous solution until the pH of the solution reaches 11, and a blue-green precipitate is formed.

Next, air is blown at a flow rate of 10 l / Hr while heating the aqueous solution at 50 to 80 ° C. Since the pH of the aqueous solution decreases as the blowing of air continues, in this case, a 15 wt% sodium hydroxide solution is added dropwise, and p
Hold H at 10. Continued blowing of air until no decrease in pH is observed to obtain a blackish brown precipitate. This precipitate is considered to be an inorganic polymeric material consisting of zirconium phosphate and zirconium ferrite.

Next, this precipitate is filtered by suction, washed with deionized water until the filtrate becomes neutral, and then dried at 50 ° C. or lower. Grind this to 120 μm or less in a mortar,
It was used as an adsorption substrate.

Next, 10 gr of the adsorption substrate (containing zirconium phosphate and zirconium ferrite powder) was placed in a beaker, and 6 gr of an isophthalic acid-based unsaturated polyester resin (manufactured by Takeda Pharmaceutical Co., Ltd .; Polymer 670).
Add 9) and mix thoroughly with a stir bar. Next is 0.1 gr
Cobalt naphthenate and 0.2 gr of methyl ethyl ketone peroxide are added, mixed well and cured.
The curing time is about 30-60 minutes. Next, the solid substance was taken out from the beaker and crushed into an appropriate size to obtain an adsorbent.

[Example 2] The adsorbent powder prepared in Example 1 was pulverized to 32 mesh or less.

Next, the reagent uranyl nitrate {UO ₂ (N
O _{3) 2} · 6H ₂ O aqueous solution of} was prepared by adding a predetermined amount of the adsorbent powder to this solution, pH 7.5 at contacting 10 hours was measured uranium adsorption. The measurement results are shown in [Table 1].

[0067]

[Table 1]

[Uranium analysis method] Arsenazo III photometric method:
A fixed amount of the test solution is collected in a 25 ml volumetric flask, 13 ml of perchloric acid solution and 1 ml of hydrazine hydrochloride solution are added thereto, diluted to about 20 ml with water, shaken well, and allowed to cool to room temperature. Next, exactly 2 ml of the Arsenazo III solution was added to this solution, and then a scalpel was cut to 25 ml with water. Using the blank containing no test solution as a control, the absorbance at 655 nm is measured, and the U content is determined from the calibration curve previously determined.

Example 3 Zr Oxychloride 0.055 m
1 liter of ol aqueous solution is prepared. This solution contains 5.005 gr of metal ions as Zr. A 15% aqueous phosphoric acid solution corresponding to 10.78 gr (0.11 mol) of phosphoric acid is added to this aqueous solution with stirring.
White zirconium phosphate crystals are formed with the addition of the phosphoric acid aqueous solution.

Next, the precipitate is filtered by suction, washed with deionized water until the filtrate becomes neutral, and then dried at 50 ° C. or lower. Grind this to 120 μm or less in a mortar,
It was made into powder.

Separately, 20 ml of a solution of promesium hydrochloride was adjusted to pH 2. with diluted hydrochloric acid or diluted sodium hydroxide.
Adjusted to 0. This solution was 1,913 dpm.

100 mg of the powder obtained above was added to this solution and stirred at room temperature. 1 hour after stirring,
Sampled after 2.5 and 4 hours respectively,
¹⁴⁷ Pm remaining in the solution was measured. The results are shown in [Table 2].

[0073]

[Table 2]

Example 4 1 l of a 0.167 M titanium sulfate aqueous solution was prepared. 8 gr as Ti in the solution
Contains metal ions. 3.3 gr into this solution
A 15% phosphoric acid aqueous solution corresponding to a phosphoric acid amount of (0.034 mol) was added with stirring. This amount of phosphoric acid corresponds to 0.2 mol with respect to Ti. A white titanium phosphate precipitate formed with the addition of the aqueous phosphoric acid solution. After adding the phosphoric acid aqueous solution,
The mixture was stirred at room temperature for 60 minutes. The pH at this time was 1.0 or less.

To this solution, 83.4 gr of ferrous sulfate crystals (FeSO ₄ .7H ₂ O) were added and dissolved with stirring. This amount corresponds to 0.3 mol of ferrous ions.

Next, a 15% by weight sodium hydroxide solution was added dropwise to this aqueous solution with stirring until the pH of the solution reached 10. A black-blue-green precipitate was produced.

Subsequently, air was blown in at a flow rate of 10 1 / hour while heating the aqueous solution at 60 to 70 ° C. Since the pH of the aqueous solution decreases as air is blown in continuously, in this case, a 15 wt% sodium hydroxide aqueous solution was added dropwise to maintain the pH at 10. Blow air for about 2 hours,
A blackish brown precipitate was obtained. This precipitate is considered to be an inorganic polymer substance composed of titanium phosphate and titanium ferrite.

Next, the black-brown precipitate is filtered off with suction,
After washing with deionized water until the filtrate becomes neutral, 40 ℃
To dry. Grind this to 120 μm or less in a mortar,
An adsorbent powder was obtained.

10 mg of this adsorbent powder was added to 1 ml of the adsorption test solution (Na-22, 479,000 cpm solution). IUCHI LAB ・ MIXER ・ HM-
Shake 10 for 2 minutes. After shaking, centrifugation was performed at 3,000 rpm for 10 minutes, and the Na-22 concentration in the supernatant was measured with a gamma counter (Aloka, ARC-2000 type). From this measured value, the Na-22 adsorption rate by the adsorbent was obtained. The results are shown in [Table 3].

[Examples 5 to 11] In the same manner as in Example 4, Cr-51, Fe-55, Co-60, Ni-63, S.
The adsorption rates of the seven radiometal nuclides of r-85, Cs-134, and Ce-141 were also calculated. In addition,
The initial concentration of radionuclide in the test solution is as shown in [Table 3].

The concentrations of Co-60 and Sr-85 were measured by a gamma counter, and Cr-51, Fe-55, Ni-
The concentrations of 63, Cs-134 and Ce-141 were measured with a liquid scintillation counter (Aloka, LSC-1000 type). The results are shown in [Table 3].

[0082]

[Table 3]

Example 12 Co-6 was added to 10 mg of the adsorbent powder prepared in Example 4 in the same manner as in Example 4.
0 was adsorbed and centrifugation was performed. 1 ml of distilled water was added to the whole amount of the adsorbent residue after centrifugation, and IUCHI L
Shake for 2 minutes using AB ・ MIXER ・ HM-10
Washed. After shaking, centrifugation was performed at 3,000 rpm for 10 minutes, the Co-60 concentration of the supernatant was measured with a gamma counter, and the amount of Co-60 desorbed by the main washing operation was determined. The results are shown in [Table 4].

Next, 1 ml of 0.1N hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to the washed and centrifuged adsorbent (residue), and the mixture was shaken for 2 minutes, and then hyperopic separation was performed. Measure the Co-60 concentration of the supernatant with a gamma counter,
The desorption rate of Co-60 from the adsorbent was determined. The results are shown in [Table 4].

[Examples 13 and 14] In the same manner as in Example 12, the desorption amount of two radioactive metal nuclides Sr-85 and Cs-134 by washing and the desorption rate with 0.1N hydrochloric acid were determined. It was The results are shown in [Table 4].

The concentration of Sr-85 was measured by a gamma counter, and the concentration of Cs-134 was measured by a liquid scintillation counter.

[0087]

[Table 4]

[Example 15] 316 mg of cesium chloride (CsCl) and 919 mg of calcium chloride (Ca
Cl ₂ .2H ₂ O) was dissolved in 500 ml of distilled water. This solution contains 500 Cs ions and 500 Ca ions, respectively.
ppm is included.

Next, 1 g of the adsorbent powder prepared in Example 4 and 2 g of zeolite (Silton B ^™ : Mizusawa Science Co., Ltd.)
(Manufactured by K.K.) is added to this solution, and the mixture is shaken at 28 °
It was shaken for 18 hours under the condition of 100 rpm. After shaking,
The concentration of Cs ions in the supernatant was measured by ion chromatography (Yokogawa Seisakusho: IC-500 type) to determine the Cs adsorption rate of the adsorbent. The results are shown in [Table 5]. C
It was found that Cs ions are well adsorbed even in the presence of a ions.

Example 16 Instead of cesium chloride,
759mg of strontium chloride (SrCl ₂ · 6H
The adsorption rate of Sr was determined in the same manner as in Example 7 except that ₂ O) was used. The results are shown in [Table 5]. Sr ions were well adsorbed even in the presence of Ca.

[0091]

[Table 5]

Claims (8)

[Claims] 1. An adsorbent containing a hydrous ferrite of tetravalent metal and a water-insoluble phosphate of tetravalent metal. 2. The adsorbent according to claim 1, wherein the tetravalent metal is titanium, zirconium or tin. 3. The tetravalent metal is titanium, as claimed in claim 1 or 2.
Adsorbent as described. 4. The adsorbent according to claim 1, 2 or 3 is mixed with 1/10 to 1 times (weight) of the thermosetting resin,
An adsorbent that is hardened. 5. The adsorbent according to claim 1, which adsorbs a radioactive substance. 6. A method for adsorbing a harmful substance, which comprises contacting the adsorbent according to claim 1 with a harmful substance. 7. The adsorption method according to claim 6, wherein the harmful substance is a radioactive substance. 8. A method for recovering a radioactive substance, which comprises contacting the adsorbent according to claim 1 with a radioactive substance to adsorb the radioactive substance, and then desorbing and recovering the radioactive substance.