JP3433202B2 - Method and remover for removing fluorine ions - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method and a removing agent for removing dissolved fluorine ions contained in water.

[0002]

2. Description of the Related Art Heretofore, as a method for removing dissolved fluorine ions contained in water, a method of adding lime or slaked lime to water and precipitating it as calcium fluoride has been generally used. However, with this method,
Requires a large excess of calcium over fluorine. In particular, the presence of sulfate ions and phosphate ions that form an insoluble salt with calcium causes a problem that the amount of calcium consumed increases and the amount of sludge increases correspondingly. There is also a method of adding an aluminum salt and removing fluorine by adsorbing aluminum hydroxide to the precipitate, but this method requires a large amount of the aluminum salt and it is difficult to dehydrate the formed precipitate. including.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for efficiently removing dissolved fluorine ions contained in water with a reduced sludge generation amount, and a fluorine ion removing agent used therefor. And

[0004]

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, according to the present invention, in the method for removing fluorine ions contained in water, the calcium ion is added to the water.
The proportion of the magnesium compound and / or the magnesium compound is anio
1 to 1000 per 1 part by weight of hydrophilic polymer containing group
It is an aqueous slurry liquid consisting of a mixture of 0 parts by weight.
And the anionic group-containing hydrophilic polymer substance is added to the aqueous slurry.
It is contained in the water by adding a removing agent which is not dissolved in the Ree liquid and is dispersed in an aqueous slurry liquid, and holding the anionic group-containing hydrophilic polymer substance in a non-dissolved state and dispersing it. There is provided a method for removing fluoride ions, which comprises insolubilizing dissolved fluoride ions. Further, according to the present invention, a removing agent for removing dissolved fluorine ions contained in water, which comprises a calcium compound and / or
Shows that the proportion of magnesium compound is high in anion group-containing hydrophilicity.
1 to 10000 parts by weight per 1 part by weight of molecular substance
An aqueous slurry comprising a mixture, the anionic group
The contained hydrophilic polymer substance is not dissolved in the aqueous slurry liquid.
There is provided a fluoride ion scavenger characterized by being dispersed without being used.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The fluorine ion removing agent of the present invention (hereinafter also simply referred to as a removing agent) is a calcium compound and / or
Or the proportion of magnesium compound is anionic group-containing hydrophilic
Ratio of 1 to 10000 parts by weight per 1 part by weight of polymer substance
An aqueous slurry liquid comprising a mixture of
The group-containing hydrophilic polymer substance is dissolved in the aqueous slurry liquid.
Not dispersed . The anionic group-containing hydrophilic polymer substance includes various water-soluble polymer substances containing anion groups such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and both natural products and synthetic products can be used. From the viewpoint of environmental protection, it is preferable to use biodegradable ones.
Such polymeric substances include alginic acid, dielan gum, xanthan gum, tragacanth gum, pectin,
Pectic acid, pectinic acid, carrageenan, gelatin,
Polysaccharides such as agar, anionized starch, propylene glycol alginate, carboxymethyl cellulose, starch glycolic acid, fibrin glycolic acid, starch phosphoric acid, galactomannan and their alkali metal salts; polyacrylic acid, acrylamide and acrylic acid Copolymers and metal salts thereof; super absorbent polymers (for example, Sumitomo Chemical Co., Ltd., “Sumika Gel”, Sanyo Chemical Co., Ltd.,
"Sunwet", Showa Denko KK, "Pre-Apple", Nitto Kagaku KK, "WAS", etc.) and the like.

In the present invention, it is particularly preferable to use sodium alginate or calcium alginate. When this is used, the content ratio of mannumamaronic acid (M) and guluronic acid (G) constituting alginic acid (mol ratio)
[M] / [G] is 0.1 to 4.0, preferably 0.1.
It is preferable to use those in the range of 3 to 3. The higher the content ratio of guluronic acid, the better the floc forming property. These anionic group-containing hydrophilic polymer substances are usually used in powder form (including short fiber form), and the average particle size thereof is 10 to 500 μm, preferably 20 to 200 μm.
m, more preferably 50 to 150 μm.

The anionic group-containing hydrophilic polymer substance used as the remover component in the present invention can be used alone or in the form of a mixture.

The removing agent of the present invention contains a calcium compound and / or a magnesium compound. Calcium and magnesium show an action of forming an ionic bond or a chelate bond with respect to the hydrophilic polymer substance containing an anion group and controlling the solubility of the polymer substance. calcium
The ratio of the compound or magnesium compound used depends on the anion group.
1 to 1000 with respect to 1 part by weight of the hydrophilic polymer substance contained
0 parts by weight, preferably 10 to 10,000 parts by weight, more preferably
It is preferably 200 to 5000 parts by weight.

Examples of the calcium compound and magnesium compound include hydroxide (calcium hydroxide, magnesium hydroxide), carbonate (calcium carbonate, magnesium carbonate), sulfate (calcium sulfate), phosphate (calcium phosphate, phosphoric acid). Magnesium) and the like.

The removing agent of the present invention is dispersed in water in the form of an aqueous slurry liquid. When the removing agent is added and dispersed in water in this manner, the anionic group-containing hydrophilic property contained therein is contained. The substance exists in a state in which it is not dissolved in water, that is, in a non-dissolved state. A preferred embodiment of the removing agent according to the present invention is an aqueous slurry liquid containing an anionic group-containing hydrophilic polymer and a calcium compound and / or a magnesium compound, and the concentration of the calcium compound and / or the magnesium compound is high. . In this aqueous slurry liquid, the concentration of the calcium compound and / or magnesium compound is 10 to 70% by weight, preferably 20 to 60%.
% By weight. The concentration of the anionic group-containing hydrophilic polymer substance is 0.001 to 1% by weight, preferably 0.01 to
It is 0.5% by weight. The calcium compound and magnesium compound are preferably hydroxides.

In the removing agent of the present invention, it is preferable to use a coagulant together. The aggregating agent in this case is used for floc aggregating, and in such a thing,
In addition to inorganic flocculants such as chitosan, calcium chloride, calcium bis (dihydrogen phosphate), ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, aluminum sulfate, polyaluminum chloride, poly Cationic organic flocculants such as cation-modified acrylamide, polyacrylic acid dimethylaminoethyl ester, polymethacrylic acid dimethylaminoethyl ester, polyethyleneimine, chitosan, etc.,
Nonionic organic flocculants such as polyacrylamide, anionic organic flocculants such as polyacrylic acid, copolymers of acrylamide and acrylic acid, and salts thereof are included.

The waste water to which the present invention is applied includes, in addition to waste water containing dissolved fluorine ions alone, dissolved polyvalent water such as copper ions, zinc ions, nickel ions, lead ions, chromium ions and iron ions together with fluorine ions. Effluents containing one or more metal ions and the like can be mentioned. There are no particular restrictions on the concentration of fluorine ions or polyvalent metal ions in this wastewater, and there is no restriction on other coexisting ions.

In order to remove dissolved fluorine ions contained in water using the removing agent of the present invention, the removing agent is put into the water and dispersed to insolubilize the fluorine ions. In this case, the amount of the calcium compound and / or magnesium compound contained in the remover to be added to the water is necessary for precipitating the dissolved fluoride ion contained in the water as an insoluble fluoride (calcium fluoride, magnesium fluoride). More than the theoretical amount, usually 1 to 1 of the theoretical amount
The amount is 1.5 times, preferably 1 to 1.2 times. Calcium compound in the remover and //
Alternatively, when the amount of the magnesium compound is insufficient, the calcium compound and / or the magnesium compound may be added after the removal agent is added, and the dissolved fluorine ion may be precipitated as an insoluble fluoride. Further, in order to make the removal of fluorine ions more complete, the pH of the water to be treated should be 4 to 12, preferably 6 to 11 after the addition of the removing agent.
It is preferable to adjust to the range.

When polyvalent metal ions such as heavy metal ions are contained in water together with fluorine ions, the polyvalent metal ion is insolubilized by adding the removing agent of the present invention, and the polyvalent metal ion is precipitated together with insoluble calcium salt and magnesium salt. To be removed. To make the removal of polyvalent metal ions more complete, after adding the removing agent, the pH of the water to be treated is adjusted by using an alkali hydroxide such as sodium hydroxide to convert the polyvalent metal ions into hydroxide. It is preferable to adjust so as to cause precipitation. Its pH is generally 4-12, preferably 6-11.

When the fluorine ion dissolved in the wastewater is removed by using the removing agent of the present invention, the wastewater is preferably acidic wastewater, but when the wastewater is neutral or alkaline, the wastewater is previously discharged. The pH of the acidic range, usually
It is preferable to adjust the pH to a range of 1 to 6, preferably 2 to 4. However, such pre-adjustment of pH is not always necessary, and in the case of the present invention, the neutral or alkaline waste water is added with the removing agent of the present invention, and then its pH is adjusted as necessary. It can be adjusted within the range of 6 to 12, preferably within the range of 6 to 10.

When the pH of the water to be treated is adjusted to an alkaline range or an acidic range, a pH adjusting agent is used. Examples of such a pH adjusting agent include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, An alkaline substance such as calcium hydroxide or an acidic substance such as hydrochloric acid, sulfuric acid or nitric acid is used.

The gel adsorbing or incorporating the insolubilized fluorine ions produced as described above is usually a floc capable of solid-liquid separation, but when the floc is not sufficient, a flocculant is added to make the gel larger and stronger. Can be flock. In the present invention, the flocs produced as described above are separated from water by the solid-liquid separation method. As the solid-liquid separation method in this case, a conventional method such as a filtration method, a centrifugation method, or a precipitation method can be adopted. The treatment time for removing dissolved fluorine ions from the water according to the invention is very short, usually within 1 hour, in particular 30.
Within minutes, preferably 3 to 10 minutes.

In carrying out the present invention, as the anionic group-containing hydrophilic polymer substance, a water-soluble substance such as alginic acid or an alkali metal salt thereof is used. In the present invention, such a water-soluble substance is used. It is possible to smoothly use even polymer materials. That is, even if the anionic group-containing hydrophilic polymeric substance exhibits water solubility, it can prevent dissolution of the polymeric substance by adding and dispersing it in water as a mixture with a calcium compound or a magnesium compound. it can. Further, the use of calcium alginate, which has low solubility, can prevent the dissolution more effectively. Therefore, in the case of the present invention, insolubilization of the fluorine ions and solid-liquid separation may be carried out under the condition that the powder of the polymer substance is not completely dissolved. When practicing the present invention, an aggregating agent can be added if necessary. The addition of this aggregating agent has the effect of aggregating the insoluble matter of fluorine ions and other harmful ions in addition to the anionic group-containing hydrophilic polymer substance dispersed in water to form giant flocs.

In the present invention, when the fluorine ion contained in the acidic water is removed, first, a removing agent is added to the acidic water, and if necessary, an alkali is added and the whole is stirred. As a result, the fluorine ions contained in the water are insolubilized. At this time, some of the fluorine ions contained in the water,
It reacts with a calcium salt or a magnesium salt of an anionic group-containing hydrophilic polymer substance in a non-dissolved state to form an insoluble salt of the polymer to cause precipitation. When polyvalent metal ions are contained in water, some of the polyvalent heavy metal ions are insoluble.
It reacts with the anion group of the hydrophilic polymer substance containing the anion group in the unsolved state to form an insoluble salt of the polymer, resulting in precipitation. At this time, the presence of the non-dissolved anion group-containing hydrophilic polymer substance allows the flocs of calcium fluoride and / or magnesium fluoride and the metal hydroxide to grow larger. Compared with conventional slaked lime and lime alone treatment, the amount of calcium and magnesium used can be significantly reduced, and as a result, sludge can be significantly reduced. Furthermore, by adding a flocculant, larger and stronger flocs can be precipitated.

In the present invention, fluorine-containing wastewater used as raw water to be treated includes wastewater from various factories such as semiconductor manufacturing industry, steel / non-ferrous metal industry, electrical equipment manufacturing industry, machinery / equipment manufacturing industry, and plating factory. Drainage, drainage from various laboratories, etc. are included. Most of these wastewater contains polyvalent metals such as heavy metals. In this case, the polyvalent metals include C
u, Zn, Cd, Pd, Ag, Al, Cr, Pb, M
n, Fe, Ni, etc. are included.

[0021]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Although the following examples further illustrate the invention,
It is in no way intended to limit the scope of the claimed invention.

Treatment Example 1 To 100 g of calcium hydroxide 1000 mg / l suspension, 5 g of sodium alginate was added, and the mixture was stirred and mixed. To this, 40 g of calcium hydroxide was added and crushed for 1 hour. To the 35 wt% suspension of calcium hydroxide, 1 wt% of the above-mentioned crushed liquid was added and mixed to obtain a removing agent [I]. Excluding this
In the removal agent [I], sodium alginate was not dissolved
Exist in a state. Theoretical amount of Ca (OH) ₂ required to remove the above-mentioned removing agent [I] as calcium fluoride in a sodium fluoride aqueous solution containing 300 ppm of fluorine 584
It was added so as to be ppm, stirred for 5 minutes, adjusted to pH 8 with sodium hydroxide, stirred for 10 minutes, and then solid-liquid separated. When the residual fluorine ion concentration of the treated water was measured,
It was 33 ppm. In this case, sodium alginate
Was not dissolved in water and was present in a non-dissolved state. In the above treatment, when pH adjustment with sodium hydroxide is not carried out, the fluorine ion concentration is 274 pp.
m.

Treatment Example 2 (Comparative Example) In Treatment Example 1, 584 ppm of the theoretical amount of Ca (OH) ₂ necessary for removing calcium fluoride as the removing agent [I] was added to the water to be treated. Other than that, the experiment was conducted in the same manner. As a result, the residual fluorine ion concentration of the treated water was 57.8 ppm.

Treatment Example 3 Necessary for removing the remover [I] of Treatment Example 1 as calcium fluoride in water to be treated containing 500 ppm of fluorine ion, 533 ppm of copper ion, 100 ppm of iron ion, and 86.7 ppm of zinc ion. Ca (OH) ₂ was added at a theoretical amount of 974 ppm, stirred for 5 minutes, adjusted to pH 9 with sodium hydroxide, stirred for 10 minutes, and then solid-liquid separated. Residual concentration of treated water is 14.5pp fluorine
Good results were obtained with m, copper 0.043 ppm, iron 0.008 ppm and zinc 0.025 ppm. In addition, Ca (OH) necessary to remove as calcium fluoride
_{When a} scavenger was added in an amount of 1.2 times the theoretical amount of ₂ and treated in the same manner, the residual fluorine concentration in the treated water was 12.
It was 1 ppm.

Treatment Example 4 To a suspension obtained by mixing 40 g of calcium hydroxide with 100 g of water, 5 g of sodium alginate was added and crushed for 1 hour. 1 wt% of the above-mentioned crushed liquid was added to a 35 wt% suspension of calcium hydroxide and mixed to obtain a removing agent [II]. An experiment was conducted in the same manner as in Treatment Example 3 except that the removing agent [II] was used, and the result was the same as that in Treatment Example 3.

Treatment Example 5 To a mixture of 40 g of calcium hydroxide and 5 g of sodium alginate, 100 g of water was added and crushed for 1 hour. To the 35 wt% suspension of calcium hydroxide, 1 wt% of the above-mentioned crushed liquid was added and mixed to obtain a removing agent [III] . The same experiment as in Treatment Example 3 was conducted except that the removing agent [III] was used, and the result was the same as that in Treatment Example 3.

Treatment Example 6 (Comparative Example) In Treatment Example 3, except that the theoretical amount of 974 ppm necessary for removing Ca (OH) ₂ containing no anionic group-containing hydrophilic polymer as calcium fluoride was added. The experiment was conducted in the same manner. As a result, the residual concentration of treated water was 47.9 ppm of fluorine, 0.055 ppm of copper, 0.010 ppm of iron, and 0.026 ppm of zinc. In addition, Ca required for removal as calcium fluoride
When 1.2 times the theoretical amount of (OH) ₂ was added and treated in the same manner, the residual fluorine concentration in the treated water was 19.2 ppm.

Treatment Example 7 The treated water obtained in Treatment Example 3 was further treated with a fluorine concentration of 8 p.
35.6 ppm of polyaluminum chloride as Al ₂ O ₃ was added to adjust the pH to pm or less, pH was adjusted to 7 with sodium hydroxide after stirring for 5 minutes, and solid-liquid separation was performed after stirring for 10 minutes. The residual fluorine concentration in the treated water was 6.2 ppm, and the absolute dry weight of the precipitate was 65 ppm.

Treatment Example 8 (Comparative Example) The treated water of Treatment Example 6 was treated with polyaluminum chloride as Al ₂ O ₃ in order to further reduce the fluorine concentration to 8 ppm or less.
Add 8 ppm, stir for 5 minutes, and p with sodium hydroxide.
After adjusting to H7 and stirring for 10 minutes, solid-liquid separation was performed. The residual fluorine concentration in the treated water was 7.1 ppm, and the absolute dry weight of the precipitate was 390 ppm.

Treatment Example 9 In the water to be treated containing 400 ppm of fluorine ion, 427 ppm of copper ion, 80 ppm of iron ion and 69 ppm of zinc ion, the removing agent [I] of Treatment Example 1 was changed to a theoretical amount of Ca (OH) ₂ of 780 ppm. The mixture was added as above, stirred for 5 minutes, adjusted to pH 9 with sodium hydroxide, stirred for 10 minutes, and then solid-liquid separated. The residual concentration of treated water is fluorine 19.
9 ppm, copper 0.030 ppm, iron 0.006 ppm,
Good results were obtained with 0.019 ppm zinc.

Treatment Example 10 (Comparative Example) The same as in Treatment Example 9 except that the theoretical amount of 780 ppm required for removing Ca (OH) ₂ containing no anionic group-containing hydrophilic polymer as calcium fluoride was added. I conducted an experiment. As a result, the residual concentration of treated water is
Fluorine 41.7ppm, copper 0.043ppm, iron 0.0
It was 06 ppm and zinc 0.027 ppm.

Treatment Example 11 Fluorine ion 300 ppm, sulfate ion 290 ppm,
To the water to be treated containing 215 ppm of nitrate ions and 180 ppm of chloride ions, the removing agent [I] of Treatment Example 1 or calcium hydroxide was added as Ca (OH) ₂ to 800 respectively.
ppm, 1000 ppm, 1200 ppm, 1400p
The mixture was added to be pm, stirred for 5 minutes, adjusted to pH 8 with sodium hydroxide, stirred for 10 minutes, and then solid-liquid separated.
Table 1 shows the residual fluorine concentration of the treated water.

[0033]

[Table 1]

Treatment Example 12 Sodium alginate was added to a 35 wt% suspension of calcium hydroxide at 0 wt%, 0.042 wt% and 0.084 wt.
%, 0.126wt%, 0.168wt%, 0.35w
6 kinds of suspensions as a removing agent were prepared by mixing so as to be t%. To the water to be treated containing 520 ppm of fluorine ions, 6 kinds of the above suspensions were added, and the theoretical amount of Ca (OH) ₂ was 101
The mixture was added to 0 ppm, stirred for 5 minutes, adjusted to pH 8.5 with sodium hydroxide, stirred for 10 minutes, and then solid-liquid separated. Table 2 shows the residual fluorine concentration of the treated water.

[0035]

[Table 2]

Treatment Example 13 Table 3 shows the results of treating the actual wastewater containing fluorine with the remover [I] of Treatment Example 1 or calcium hydroxide in combination with 50 ppm of aluminum sulfate at pH 8.

[0037]

[Table 3]

Treatment Example 14 5 g of sodium alginate was added to 1000 g of magnesium hydroxide 1000 mg / 1 suspension and mixed with stirring. To this, 40 g of magnesium hydroxide was added and crushed for 1 hour. To the 35 wt% suspension of magnesium hydroxide, 1 wt% of the above-mentioned crushed liquid was added and mixed to obtain a removing agent [IV].
When an experiment was conducted in the same manner as in Treatment Example 1 except that this removing agent [IV] was used, the residual fluorine ion concentration in the treated water was 54 ppm. In the above treatment, when the pH adjustment with sodium hydroxide was not carried out, the fluorine ion concentration was 286 ppm.

[0039]

According to the present invention, fluorine ions, which are harmful ions contained in water, can be efficiently removed at a reduced sludge generation amount. Moreover, in this case, when the polyvalent metal ion is dissolved in the water, the metal ion can also be effectively insolubilized and removed.

─────────────────────────────────────────────────── ─── Continuation of the front page (73) Patent holder 000005979 Mitsubishi Corporation 2-3-6 Marunouchi, Chiyoda-ku, Tokyo (74) Above three agents 100059959 Attorney Minoru Nakamura (9 outside) (72) ) Inventor Kenji Tatsumi 5-518-304 Matsushiro Tsukuba City, Ibaraki Prefecture (518) Inventor Shinji Wada 4-15-18-302 Togashira, Toride City, Ibaraki Prefecture (72) Inventor Yasushi Kei Yukawa 5-16 Sakasedai, Takarazuka City, Hyogo Prefecture -14 (56) Reference JP 56-70893 (JP, A) JP 50-105578 (JP, A) JP 50-15357 (JP, A) JP 50-15356 (JP, A) ) JP-A-10-34163 (JP, A) JP-A-4-90888 (JP, A) JP-A-49-90273 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/58 C02F 1/52

Claims (13)

(57) [Claims] 1. Removal of dissolved fluorine ions contained in water
In the water, a calcium compound and / or
Or the proportion of magnesium compound is anionic group-containing hydrophilic
Ratio of 1 to 10000 parts by weight per 1 part by weight of polymer substance
An aqueous slurry liquid comprising a mixture of
The group-containing hydrophilic polymer substance is dissolved in the aqueous slurry liquid.
Add the dispersant without dispersion in the state of aqueous slurry
The anionic group-containing hydrophilic polymer substance in a non-dissolved state
Dissolved in the water by holding and dispersing
Fluorine ion characterized by making fluorine ions insoluble
On removal method. 2. The method according to claim 1, wherein the calcium compound and / or magnesium compound is a hydroxide. 3. The pH of the water is adjusted to 5 after addition of the remover.
The method according to claim 1 or 2, wherein the range is adjusted to 11. 4. The method according to claim 1 , wherein a flocculant having a floc forming ability is added to the water. 5. The method according to claim 1, wherein polyvalent metal ions are present in the water. 6. The hydrophilic polymer substance containing an anion group,
The method according to claim 1, which comprises (i) alginic acid or a salt thereof, or (ii) a mixture of alginic acid or a salt thereof and another anionic group-containing hydrophilic polymer substance. 7. The hydrophilic polymer substance containing an anion group,
7. The method according to claim 1, which comprises (i) pectin, pectic acid or a salt thereof or (ii) a mixture of pectin, pectic acid or a salt thereof and another anionic group-containing hydrophilic polymer substance. 8. The hydrophilic polymer substance containing an anion group,
(I) polyacrylic acid, a copolymer of acrylamide and acrylic acid or a salt thereof, or (ii) polyacrylic acid,
The method according to any one of claims 1 to 7, which comprises a copolymer of acrylamide and acrylic acid or a salt thereof and a mixture of another anionic group-containing hydrophilic polymer substance. 9. Removal of dissolved fluorine ions contained in water
And a calcium compound and / or
Shows that the proportion of magnesium compound is high in anion group-containing hydrophilicity.
1 to 10000 parts by weight per 1 part by weight of molecular substance
An aqueous slurry comprising a mixture, the anionic group
The contained hydrophilic polymer substance is not dissolved in the aqueous slurry liquid.
Fluoride ion removal characterized by being dispersed without
Agent . 10. The fluoride ion removing agent according to claim 9, wherein the calcium compound and / or magnesium compound is a hydroxide. 11. A hydrophilic polymer substance containing the anion group
Is (i) alginic acid or a salt thereof or (ii) algi
Acid or salt thereof and other anion group-containing hydrophilic polymer
A flux according to any one of claims 9 to 10 consisting of a mixture with a substance.
Fluoride removal agent. 12. A hydrophilic polymer substance containing the anion group
Is (i) pectin, pectic acid or their salts or
Is (ii) pectin, pectic acid or their salts and others
Consisting of a mixture of anionic group-containing hydrophilic polymeric substances
The fluoride ion removing agent according to any one of claims 9 to 11. 13. A hydrophilic polymer substance containing the anion group
However, (i) polyacrylic acid, acrylamide and acrylic
Copolymer with acid or its salt or (ii) polyacrylic
Acid, a copolymer of acrylamide and acrylic acid, or
Mixing the salt with other hydrophilic polymer containing anion groups
The fluorine ion removal according to any one of claims 9 to 12
Remover.