JP2000317467A - Method for removing fluorine ion and removing agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing the dissolved fluorine ion contained in water effectively and with a low sludge generating quantity and to provide a fluorine ion removing agent used for the method. SOLUTION: In the method for removing the fluorine ion contained in the water, the dissolved fluorine ion contained in the water is insolubilized by charging and dispersing the removing agent consisting of the mixture of an anion group-containing hydrophilic polymeric material and a calcium compd. and/or a magnesium compd. into the water in the form like powder or slurry.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, 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 most commonly performed. However, in this method,
Requires a large excess of calcium over fluorine. In particular, when sulfate ions or phosphate ions that form insoluble salts with calcium are present, there is a problem that the consumption of calcium increases and the amount of sludge increases accordingly. There is also a method of adding an aluminum salt to remove fluorine by adsorption to aluminum hydroxide precipitate. However, this method has a problem that the amount of the aluminum salt used is large and it is difficult to dehydrate the formed precipitate. including.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently removing dissolved fluoride ions contained in water with a reduced amount of sludge generated, and a fluoride ion remover used therefor. And

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in the method for removing fluorine ions contained in water, the water-containing removing agent comprising a mixture of a hydrophilic polymer material having an anionic group and a calcium compound and / or a magnesium compound is powdered. Alternatively, there is provided a method for removing fluorine ions, characterized by insolubilizing dissolved fluorine ions contained in the water by adding and dispersing the fluorine ions in an aqueous slurry liquid. Further, according to the present invention, a removing agent for removing dissolved fluorine ions contained in water, comprising a mixture of an anionic group-containing hydrophilic polymer substance and a calcium compound and / or a magnesium compound. And a fluorine ion remover.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The fluoride ion remover (hereinafter simply referred to as a remover) of the present invention comprises a mixture of an anionic group-containing hydrophilic polymer substance and a calcium compound and / or a magnesium compound. Carboxyl groups, sulfonic acid groups,
Various water-soluble polymer substances containing an anion group such as a phosphate group are included, and both natural products and synthetic products can be used. However, those having biodegradability are preferable from the viewpoint of environmental protection. Such polymeric substances include alginic acid, dielan gum, xanthan gum, tragacanth gum, pectin, pectic acid, pectinic acid, carrageenan, gelatin, agar, anionized starch, propylene glycol alginate, carboxymethyl cellulose, starch glycolic acid, cellulose glycol. acid,
Polysaccharides such as starch phosphoric acid and galactomannan and their alkali metal salts; polyacrylic acid, copolymers of acrylamide and acrylic acid and their metal salts; superabsorbent polymers (for example, Sumitomo Chemical Co., Ltd .; , Sanyo Kasei Co., Ltd., "Sunwet", Showa Denko KK, "Pre-Apr", Nisseki Chemical Co., Ltd., "WAS", etc.).

In the present invention, it is particularly preferable to use sodium alginate or calcium alginate. In the case of using these, the content ratio (molar ratio) of mannumaric acid (M) and guluronic acid (G) constituting alginic acid is preferably used. ratio)
[M] / [G] is 0.1 to 4.0, preferably 0.1
It is preferable to use those in the range of ~ 3. The higher the content 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 have an average particle size of 10 to 500 μm, preferably 20 to 200 μm.
m, more preferably 50 to 150 μm.

In the present invention, the above-mentioned anionic group-containing hydrophilic polymer substance used as a removing agent component can be used alone or in the form of a mixture.

[0008] The removing agent of the present invention contains a calcium compound and / or a magnesium compound. Calcium and magnesium form an ionic bond or a chelate bond with a hydrophilic polymer substance containing an anion group, and exhibit an action of controlling the solubility of the polymer substance. The use ratio of the calcium compound and the magnesium compound is not particularly limited, and is appropriately selected depending on the type and amount of the fluorine ion or the polyvalent metal ion dissolved in the water, the pH of the water to be treated, and the like. 1 to 10000 parts by weight, preferably 10 to 10 parts by weight, per 1 part by weight of the hydrophilic polymer substance
000 parts by weight, more preferably 200 to 5000 parts by weight.

The calcium and magnesium compounds include hydroxides (calcium hydroxide and magnesium hydroxide), carbonates (calcium carbonate and magnesium carbonate), sulfates (calcium sulfate), and phosphates (calcium phosphate and phosphate). Magnesium) and the like.

The removing agent of the present invention is charged and dispersed in water in the form of a powder or an aqueous slurry. When the removing agent is charged and dispersed in water in this way, the anion group-containing hydrophilic substance contained therein is dispersed. It exists in an insoluble (insoluble) state without being dissolved. One of preferred embodiments of the removing agent according to the present invention contains a hydrophilic polymer material containing an anionic group and a calcium compound and / or a magnesium compound,
An aqueous slurry liquid having a high concentration of the calcium compound and / or the magnesium compound. In this aqueous slurry, 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 0.5% by weight. The calcium compound and the magnesium compound are preferably hydroxides.

In the removing agent of the present invention, a coagulant is preferably used in combination. The flocculant in this case is used for floc flocculation.
In addition to inorganic coagulants such as chitosan, calcium chloride, bis (dihydrogen phosphate) calcium, ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate, aluminum sulfate, polyaluminum chloride, etc. Cationically modified acrylamide, dimethylaminoethyl polyacrylate, dimethylaminoethyl polymethacrylate, polyethylene imine, cationic organic coagulants such as chitosan,
Nonionic organic coagulants such as polyacrylamide, and anionic organic coagulants such as polyacrylic acid, a copolymer of acrylamide and acrylic acid, and salts thereof are included.

The wastewater to which the present invention is applied includes, in addition to wastewater containing dissolved fluorine ions alone, dissolved polyvalent ions such as copper ions, zinc ions, nickel ions, lead ions, chromium ions, and iron ions together with the fluorine ions. Wastewater containing one or more metal ions or the like may be used. There is no particular limitation on the concentration of fluorine ions or polyvalent metal ions in the wastewater, and there is no limitation 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 introduced into the water and dispersed to insolubilize the fluorine ions. In this case, the amount of the calcium compound and / or the magnesium compound contained in the removing agent introduced into the water is necessary for precipitating dissolved fluoride ions contained in the water as insoluble fluoride (calcium fluoride, magnesium fluoride). More than the theoretical amount, usually 1 to 1
It is added in a 1.5-fold amount, preferably 1-1.2-fold amount. Calcium compound in the remover to be introduced into water and / or
Alternatively, when the amount of the magnesium compound is insufficient, a calcium compound and / or a magnesium compound may be added after the removal agent is added, and the dissolved fluoride ions may be precipitated as insoluble fluoride. In order to complete the removal of fluorine ions, the pH of the water to be treated is adjusted to 4 to 12, preferably 6 to 11 after the addition of the removing agent.
It is preferable to adjust the range.

When polyvalent metal ions such as heavy metal ions are contained together with fluorine ions in water, the polyvalent metal ions are insolubilized by adding the removing agent of the present invention, and precipitated together with insoluble calcium salts and magnesium salts. Removed. To make the removal of polyvalent metal ions more complete, after adding the remover, the pH of the water to be treated is adjusted by using an alkali hydroxide such as sodium hydroxide to make the polyvalent metal ion a hydroxide. It is preferable to make adjustments so as to produce a precipitate. Its pH is generally between 4 and 12, preferably between 6 and 11.

When removing the fluorine ions dissolved in the waste water using the removing agent of the present invention, the waste water is preferably acidic waste water. However, when the waste water is neutral or alkaline, the waste water is previously removed. PH in the acidic region, usually
It is preferable to adjust the pH to a range of 1 to 6, preferably 2 to 4. However, such a prior pH adjustment is not always necessary, and in the case of the present invention, the neutral or alkaline wastewater is added with the remover of the present invention, and if necessary, its pH is adjusted to It can be adjusted in the range of 6 to 12, preferably in 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 adjuster is used. Examples of such a pH adjuster include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, and the like. An alkaline substance such as calcium hydroxide or an acidic substance such as hydrochloric acid, sulfuric acid or nitric acid is used.

The gel formed by adsorbing or taking in the insolubilized fluorine ions as described above is usually a floc capable of solid-liquid separation. If the floc is not sufficient, a flocculant is added to the gel to add a larger and stronger floc. Can be flocked. In the present invention, the floc generated as described above is separated from water by a solid-liquid separation method. As the solid-liquid separation method in this case, a conventional method such as a filtration method, a centrifugal separation method, or a sedimentation method can be employed. The treatment time for removing dissolved fluoride ions from water according to the invention is very short, usually within one hour, in particular less than 30 hours.
Within minutes, preferably 3 to 10 minutes.

In the practice of the present invention, a water-soluble substance such as alginic acid or an alkali metal salt thereof is used as the hydrophilic polymer containing an anion group. In the present invention, such a water-soluble substance is used. Even a polymer substance can be used smoothly. That is, even if the anionic group-containing hydrophilic polymer substance shows water solubility, it can be prevented from dissolving the polymer substance by dispersing it in water as a mixture with a calcium compound or a magnesium compound. it can. Further, by using calcium alginate having low solubility, its dissolution can be more effectively prevented. Therefore, in the case of the present invention, the insolubilization of the fluorine ions and the solid-liquid separation may be performed under the condition that the powder of the polymer substance is not completely dissolved. When practicing the present invention, a flocculant can be added as necessary. The addition of the flocculant has the effect of aggregating insolubles of fluoride ions and other harmful ions, in addition to anionic group-containing hydrophilic polymer substances dispersed in water, to form a giant floc.

In the present invention, when removing fluorine ions contained in acidic water, first, a remover is added to the acidic water, and if necessary, an alkali is added and the whole is stirred. Thereby, the fluorine ions contained in the water are insolubilized. At this time, some of the fluorine ions contained in the water,
Reacts with the calcium salt or magnesium salt of an anionic group-containing hydrophilic polymer substance to form an insoluble salt of the polymer and precipitates. In addition, when polyvalent metal ions are contained in water, some of the polyvalent heavy metal ions react with the anion groups of the hydrophilic polymer substance containing an anion group to form an insoluble salt of the polymer and precipitate. Occurs. At this time, the presence of the anionic group-containing hydrophilic polymer substance allows the floc of calcium fluoride and / or magnesium fluoride or metal hydroxide to grow larger, thereby increasing the conventional slaked lime or the like. Compared to lime alone, the amount of calcium and magnesium used can be significantly reduced, and as a result, sludge can be significantly reduced. further,
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 a semiconductor manufacturing industry, a steel / non-ferrous metal industry, an electric equipment manufacturing industry, a machine / equipment manufacturing industry, and a plating factory. Wastewater, wastewater from various laboratories, etc. are included. Most of these wastewaters contain polyvalent metals such as heavy metals. In this case, polyvalent metals include C
u, Zn, Cd, Pd, Ag, Al, Cr, Pb, M
n, Fe, Ni, and the like.

[0021]

Next, the present invention will be described in more detail with reference to examples. Although the following examples further illustrate the invention,
In no way is it intended to limit the scope of the invention as claimed.

Treatment Example 1 5 g of sodium alginate was added to 100 g of a 1000 mg / l suspension of calcium hydroxide, and the mixture was stirred and mixed. To this, 40 g of calcium hydroxide was added and crushed for 1 hour. To a suspension of 35% by weight of calcium hydroxide, 1% by weight of the above crushed liquid was added and mixed to prepare a remover [I]. To a sodium fluoride aqueous solution containing 300 ppm of fluorine so as to have a theoretical amount of 584 ppm of Ca (OH) ₂ necessary for removing the above-mentioned remover [I] as calcium fluoride, and after stirring for 5 minutes, The pH was adjusted to 8 with sodium, stirred for 10 minutes, and then separated into solid and liquid. The residual fluorine ion concentration of the treated water was measured and found to be 33 ppm. In the above treatment, when pH adjustment with sodium hydroxide was not performed, the fluorine ion concentration was 27%.
4 ppm.

Treatment Example 2 (Comparative Example) In treatment example 1, 584 ppm of the theoretical amount of Ca (OH) ₂ necessary for removing calcium fluoride instead of the removing agent [I] was added to the water to be treated. The experiment was performed in the same manner except for the above. 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 from water to be treated containing 500 ppm of fluorine ions, 533 ppm of copper ions, 100 ppm of iron ions, and 86.7 ppm of zinc ions. Na (Ca) ₂ was added to a theoretical amount of 974 ppm, stirred for 5 minutes, adjusted to pH 9 with sodium hydroxide, stirred for 10 minutes, and then separated into solid and liquid. The residual concentration of the treated water is 14.5 pp of fluorine.
m, 0.043 ppm of copper, 0.008 ppm of iron and 0.025 ppm of zinc gave good results. Also, Ca (OH) necessary for removal as calcium fluoride
_{When a} remover was added so as to be 1.2 times the theoretical amount of ₂ and the same treatment was performed, the residual fluorine concentration of the treated water was 12.
It was 1 ppm.

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

Treatment Example 5 100 g of water was added to a mixture of 40 g of calcium hydroxide and 5 g of sodium alginate, and the mixture was ground for 1 hour. To a suspension of 35% by weight of calcium hydroxide, 1% by weight of the above crushed liquid was added and mixed to obtain a remover [II]. Said,
An experiment was performed in the same manner as in Treatment Example 3 except that the above-mentioned remover [III] was used. The result was the same as that of Treatment Example 3.

Processing Example 6 (Comparative Example) In processing example 3, a hydrophilic polymer material containing an anion group was used.
Contains no Ca (OH) _TwoAs calcium fluoride
Except that 974 ppm of the theoretical amount necessary for
The experiment was performed as described above. As a result, the residual concentration of treated water
Is fluorine 47.9 ppm, copper 0.055 ppm, iron
0.010 ppm and 0.026 ppm of zinc. Ma
In addition, Ca necessary for removal as calcium fluoride
(OH)_Two1.2 times the theoretical amount of
As a result, the residual fluorine concentration of the treated water was 19.2 ppm.
there were.

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 pressure to not more than pm, stirred for 5 minutes, adjusted to pH 7 with sodium hydroxide, stirred for 10 minutes, and then separated into solid and liquid. The residual fluorine concentration of 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 further converted to polyaluminum chloride as Al ₂ O ₃ to reduce the fluorine concentration to 8 ppm or less.
After adding 8 ppm and stirring for 5 minutes, p was added with sodium hydroxide.
The mixture was adjusted to H7, stirred for 10 minutes, and then subjected to solid-liquid separation. The residual fluorine concentration of 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 ions, 427 ppm of copper ions, 80 ppm of iron ions, and 69 ppm of zinc ions, the removing agent [I] of Treatment Example 1 becomes 780 ppm of the theoretical amount of Ca (OH) _2. After stirring for 5 minutes, the mixture was adjusted to pH 9 with sodium hydroxide, stirred for 10 minutes, and then subjected to solid-liquid separation. The residual concentration of the treated water is fluorine 19.
9 ppm, copper 0.030 ppm, iron 0.006 ppm,
Good results were obtained with 0.019 ppm of zinc.

Processing Example 10 (Comparative Example) In processing example 9, the hydrophilic polymer substance containing an anion group was used.
Contains no Ca (OH) _TwoAs calcium fluoride
The same except that 780 ppm of theoretical amount required for
The experiment was performed. As a result, the residual concentration of the treated water is
41.7 ppm of fluorine, 0.043 ppm of copper, 0.0 of iron
06 ppm and zinc were 0.027 ppm.

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

[0033]

[Table 1]

Treatment Example 12 0 wt%, 0.042 wt%, 0.084 wt sodium alginate was added to a 35 wt% suspension of calcium hydroxide.
%, 0.126wt%, 0.168wt%, 0.35w
Six kinds of suspensions as a removing agent were prepared by mixing so as to obtain t%. The water to be treated containing fluorine ions 520 ppm, the suspension six Ca (OH) ₂ of theory 101
The mixture was added to a concentration of 0 ppm, stirred for 5 minutes, adjusted to pH 8.5 with sodium hydroxide, stirred for 10 minutes, and then subjected to solid-liquid separation. 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 at pH 8 using the remover [I] or calcium hydroxide of Treatment Example 1 together with 50 ppm of aluminum sulfate.

[0037]

[Table 3]

Treatment Example 14 5 g of sodium alginate was added to 1000 mg of magnesium hydroxide / 100 g of a suspension, followed by stirring and mixing. To this, 40 g of magnesium hydroxide was added and crushed for 1 hour. 1 wt% of the above crushed liquid was added to a 35 wt% suspension of magnesium hydroxide and mixed to obtain a remover [IV].
An experiment was conducted in the same manner as in Treatment Example 1 except for using this remover [IV], and the residual fluorine ion concentration in the treated water was 54 ppm. In the above treatment, when pH adjustment with sodium hydroxide was not performed, 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 with a reduced amount of sludge generated. Moreover, in this case, when polyvalent metal ions are dissolved in the water, the metal ions can also be effectively insolubilized and removed.

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 000005979 Mitsubishi Corporation 2-6-3 Marunouchi, Chiyoda-ku, Tokyo (74) The above three agents 100074505 Patent Attorney Toshiaki Ikeura (72) Inventor Kenji Tatsumi Ibaraki 5-518-304, Matsushiro, Tsukuba, Japan (72) Inventor Shinji Wada 4-15-18-302, Togami, Toride, Ibaraki (72) Inventor Yasuhiro Yukawa 5-16-14, Sakasedai, Takarazuka, Hyogo F-term (reference) 4D038 AA08 AB40 AB41 AB66 AB68 AB69 BB13 BB18

Claims (14)

[Claims] 1. A method for removing dissolved fluorine ions contained in water, comprising: removing a removing agent comprising a mixture of an anionic group-containing hydrophilic polymer substance and a calcium compound and / or a magnesium compound into the water in the form of powder or A method for removing fluorine ions, comprising dissolving and dissolving dissolved fluorine ions contained in the water by introducing and dispersing the aqueous slurry liquid. 2. The method according to claim 1, wherein said calcium compound and / or magnesium compound is a hydroxide. 3. The pH of the water is adjusted to 5 after the addition of the removing agent.
The method according to claim 1 or 2, wherein the adjustment is performed in the range of 11. 4. The method according to claim 1, wherein a coagulant is added to said water.
Either way. 5. The method according to claim 1, wherein a polyvalent metal ion is present in the water. 6. The anionic group-containing hydrophilic polymer substance,
The method according to any one of claims 1 to 5, comprising (i) alginic acid or a salt thereof or (ii) a mixture of alginic acid or a salt thereof and another hydrophilic polymer containing an anion group. 7. The method according to claim 1, wherein the hydrophilic polymer containing an anion group is
The method according to any one of claims 1 to 6, comprising (i) pectin, pectic acid or a salt thereof, or (ii) a mixture of pectin, pectic acid or a salt thereof and another hydrophilic polymer containing an anion group. 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, a copolymer of acrylamide and acrylic acid or a salt thereof, and another anionic group-containing hydrophilic polymer substance The method according to any one of claims 1 to 7, comprising a mixture with 9. A removing agent for removing dissolved fluoride ions contained in water, comprising a mixture of an anionic group-containing hydrophilic polymer substance and a calcium compound and / or a magnesium compound. Ion remover. 10. The fluoride ion remover according to claim 9, wherein said calcium compound and / or magnesium compound is a hydroxide. 11. The fluorine ion remover according to claim 9, wherein a coagulant is used in combination. 12. The anionic group-containing hydrophilic polymer substance comprises (i) alginic acid or a salt thereof or (ii) a mixture of alginic acid or a salt thereof and another anion group-containing hydrophilic polymer substance. The fluorine ion-removing agent of any one of to 11; 13. The hydrophilic macromolecular substance containing an anion group, wherein (i) pectin, pectic acid or a salt thereof, or (ii) pectin, pectic acid or a salt thereof and another hydrophilic macromolecule containing an anion group. The fluorine ion remover according to any one of claims 9 to 12, comprising a mixture of 14. The anionic group-containing hydrophilic polymer substance may be (i) a copolymer of polyacrylic acid, acrylamide and acrylic acid or a salt thereof, or (ii) a copolymer of polyacrylic acid, acrylamide and acrylic acid. The fluorine ion remover according to any one of claims 9 to 13, comprising a mixture of a polymer or a salt thereof and another hydrophilic polymer containing an anion group.