JP2003285076A - Recovery method for fluorine-containing emulsifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recovery method for recovering a fluorine-containing emulsifier economically by simple operation. <P>SOLUTION: In the recovery method for recovering the fluorine-containing emulsifier from wastewater after the polymerization of a fluorine-containing polymer containing the fluorine-containing emulsifier using a laminar composite hydroxide, the laminar composite hydroxide containing the fluorine-containing emulsifier between the layers thereof is produced to be separated from flocculated wastewater and this separated laminar composite hydroxide is dissolved in a mineral acid. Then, the fluorine-containing emulsifier is extracted from the obtained solution using a fluorohydrocarbon. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for recovering a fluorinated emulsifier using a layered double hydroxide.

[0002]

2. Description of the Related Art Conventionally, as a method for recovering a fluorine-containing emulsifier used in emulsion polymerization of a fluorine-containing polymer, a technique using an anion exchange resin (hereinafter referred to as IER) is known. Patent Document 1 describes a method of aggregating and washing emulsion-polymerized latex, collecting an emulsifier as an aqueous solution, and collecting the fluorinated emulsifier with an organic solvent after concentration,
A method for recovering the fluorinated emulsifier using IER is also described in the text. Patent Document 2 describes a method in which a dilute aqueous emulsifier solution is brought into contact with a weakly basic IER in a pH range of 0 to 7, the emulsifier is adsorbed and desorbed with aqueous ammonia. In Patent Document 3, a nonionic or cationic surfactant is added to the coagulation wastewater of the fluoropolymer to stabilize polytetrafluoroethylene (hereinafter referred to as PTFE) fine particles in the coagulation wastewater, and the polytetrafluoroethylene (hereinafter referred to as "PTFE") fine particles in the coagulation wastewater of the IER. A method of preventing blockage is described. Patent Documents 4, 5, and 6
Describes a method in which the coagulated waste water of PTFE is concentrated by an ultrafiltration method, a part of the fluorinated emulsifier used in the production of PTFE is recovered, and then the fluorinated emulsifier is adsorbed and recovered by IER. Patent Document 2 and Patent Documents 7 and 8 disclose a method of adsorbing a fluorinated emulsifier on an IER and then desorbing and recovering perfluorooctanoic acid using a mixture of an acid and an organic solvent. In Patent Document 9, lime water is added in advance to the aggregated wastewater of a tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymer (hereinafter referred to as PFA) to adjust the pH to 6
After adjusting to ~ 7.5, metal salts such as aluminum chloride and iron chloride are added to agglomerate unaggregated PFA, and then the aggregates are mechanically separated and removed. The method of adsorbing and recovering the fluorinated emulsifier using a strongly basic IER is described. Patent Document 10 describes a method of desorbing a fluorine-containing emulsifier adsorbed on an ion exchange resin using a mixed solution of water, an alkali and an organic solvent. Further, Non-Patent Document 1 and Non-Patent Document 2 report a technique of inserting and fixing perfluorooctanoic acid and its ammonium salt using a layered double hydroxide of aluminum and zinc.

[0003]

[Patent Document 1] Japanese Patent Publication No. 47-51233

[Patent Document 2] US Pat. No. 4,282,162 (U)
S3882153)

[Patent Document 3] International Publication No. 99/62830 pamphlet (WO99 / 62830)

[Patent Document 4] JP-A-55-120630

[Patent Document 5] US Pat. No. 5,321,935 (U)
S4369266)

[Patent Document 6] German Patent Invention No. 2908001 (DE2908001)

[Patent Document 7] JP-A-55-104651

[Patent Document 8] German Patent No. 2903981 (D
E2903981)

[Patent Document 9] International Publication No. 99/62858 pamphlet (WO99 / 62858)

[Patent Document 10] Japanese Patent Laid-Open No. 2001-62313

[Non-Patent Document 1] Proceedings of the 76th Annual Meeting of the Chemical Society of Japan, published March 15, 1999, page 600

[Non-Patent Document 2] Proceedings of the 80th Autumn Annual Meeting of the Chemical Society of Japan, published September 7, 2001, page 41.

[0004]

However, in the method using the IER, it is necessary to remove the floating solid components (hereinafter, referred to as SS content) including the non-aggregated fluoropolymer before contacting with the IER, This removal of SS not only has a great influence on the recovery efficiency of the fluorinated emulsifier, but a simple and highly efficient method for removing SS has not been found, such as problems in actual operation. Many are left. In addition, the insertion and fixation method using the layered double hydroxide reported in Non-Patent Documents 1 and 2 only shows insertion and fixation in an aqueous solution in which only perfluorooctanoic acid and its ammonium salt are dissolved. There is no known report showing the actual insertion and fixation by using the coagulated drainage of the actual fluoropolymer containing other contaminants.

The present invention has been made in view of the above circumstances, and provides a method for easily recovering a fluorinated emulsifier using a layered double hydroxide from aggregated wastewater of a fluorinated polymer containing a fluorinated emulsifier. Has an aim.

[0006]

In order to achieve the above object, the present invention comprises a mixed aqueous solution containing a divalent metal ion and a trivalent metal ion, a fluorine-containing emulsifier, and a floating solid content and a floating solid content. The wastewater after the polymerization of the fluoropolymer having a content of the substance that can be 1% by mass or less,
Mixing while maintaining the pH at which the layered double hydroxide of the valent metal and the trivalent metal is formed to form a layered double hydroxide containing a fluorine-containing emulsifier between the layers, and subsequently, the layered separated from the waste water. Provided is a method for recovering a fluorinated emulsifier, which comprises dissolving a double hydroxide in a mineral acid and extracting the fluorinated emulsifier from the solution using a fluorinated hydrocarbon.

In the present invention, a mixed aqueous solution containing divalent metal ions and trivalent metal ions is added to an aqueous solution maintained at a pH at which a layered double hydroxide of the divalent metal and the trivalent metal is formed. Layered double hydroxide is generated in advance, and this is added to the waste water after polymerization of the fluoropolymer, which contains a fluorine-containing emulsifier and contains 1% by mass or less of suspended solids and substances capable of becoming suspended solids. To produce a layered double hydroxide containing a fluorine-containing emulsifier between the layers, subsequently dissolve the layered double hydroxide separated from the wastewater in mineral acid, and use a fluorine-containing hydrocarbon from the solution. A method for recovering a fluorinated emulsifier for extracting the fluorinated emulsifier is provided.

Furthermore, the present invention adds a mixed aqueous solution containing a divalent metal ion and a trivalent metal ion to an aqueous solution maintained at a pH at which a layered double hydroxide of the divalent metal and the trivalent metal is formed. By calcining the layered double hydroxide generated by the above, a layered double hydroxide in which an anion to be encapsulated is desorbed is generated, and this contains a fluorine emulsifier, and thus a suspended solid content and a substance capable of becoming a suspended solid content Content of 1 mass% or less,
The fluorinated polymer is added to the waste water after polymerization to form a layered double hydroxide containing a fluorinated emulsifier between layers, and subsequently, the layered double hydroxide separated from the waste water is dissolved in a mineral acid, and the dissolution is performed. Provided is a method for recovering a fluorinated emulsifier by extracting the fluorinated emulsifier from a liquid using the fluorinated hydrocarbon.

In the present invention, the divalent metal ion is preferably one or two selected from magnesium ion and zinc ion, and the trivalent metal ion is preferably aluminum ion. In the method for recovering a fluorinated emulsifier of the present invention, the mineral acid is preferably one or more selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid.
The above-mentioned fluoropolymer is polytetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene / propylene copolymer, tetrafluoroethylene / propylene / vinylidene fluoride copolymer, tetrafluoride. Ethylene / hexafluoropropylene copolymer, tetrafluoroethylene / C
_{F 2 = CFO (CF 2)} 2 CF 3 copolymer, it is preferable that one or two or more selected from polyvinylidene fluoride. Further, the fluorinated emulsifier is preferably ammonium perfluorooctanoate. Further, it is preferable to recover the fluorinated emulsifier from wastewater after polymerization of the fluorinated polymer having a concentration of the fluorinated emulsifier of 1 mass ppm or more and 10 mass% or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the fluorinated emulsifier is a salt of 5 to 13 carbon atoms such as perfluoroalkanoic acid, ω-hydroperfluoroalkanoic acid, ω-chloroperfluoroalkanoic acid and perfluoroalkanesulfonic acid. Are preferred, and these may have a linear structure or a branched structure, or a mixture thereof. Further, an etheric oxygen atom may be contained in the molecule. Within the range of this number of carbon atoms, the action and effect as an emulsifier is excellent. The acid salt is preferably an alkali metal salt such as a lithium salt, a sodium salt, or a potassium salt, or an ammonium salt,
The ammonium salt or sodium salt is more preferable, and the ammonium salt is most preferable.

Specific examples of the above-mentioned acid include perfluoropepide.
Acid, perfluorohexanoic acid, perfluorohep
Tanoic acid, perfluorooctanoic acid, perfluorononane
Acid, perfluorodecanoic acid, perfluorododecanoic acid,
ω-hydroperfluoroheptanoic acid, ω-hydroperf
Luorooctanoic acid, ω-hydroperfluorononanoic acid,
ω-chloroperfluoroheptanoic acid, ω-chloroperf
Luorooctanoic acid, ω-chloroperfluorononanoic acid
Etc., CF_ThreeCF_TwoCF_TwoOCF (CF_Three) COOH, C
F_ThreeCF_TwoCF_TwoOCF (CF_Three) CF_TwoOCF (CF
_Three) COOH, CF_ThreeCF_TwoCF_TwoO [CF (CF _Three)
CF_TwoO]_TwoCF (CF_Three) COOH, CF_ThreeCF_TwoC
F_TwoO [CF (CF _Three) CF_TwoO]_ThreeCF (CF_Three) C
OOH, CF_ThreeCF_TwoCF_TwoCF_TwoCF_TwoOCF (CF
_Three) COOH, perfluorohexane sulfonic acid,
Lefluoroheptane sulfonic acid, perfluorooctane
Sulfonic acid, perfluorononanesulfonic acid, perflu
Examples thereof include orodecane sulfonic acid and the like.

Specific examples of ammonium salts include perf
Ammonium uropentanoate, perfluorohexane
Ammonium acid, Ammonium perfluoroheptanoate
Ammonium perfluorooctanoate (hereinafter referred to as AP
It is written as FO. ), Ammonium perfluorononanoate,
Ammonium perfluorodecanoate, perfluorodode
Ammonium citrate, ω-hydroperfluoroheptane
Ammonium acid, ω-hydroperfluorooctanoic acid
Ammonium, ω-hydroperfluorononanoic acid
Um, ω-chloroperfluoroheptanoic acid ammoniu
Ω, ammonium ω-chloroperfluorooctanoate,
ω-chloroperfluorononanoic acid ammonium, CF
_ThreeCF_TwoCF_TwoOCF (CF_Three) COONH_Four, CF_Three
CF_TwoCF_TwoOCF (CF_Three) CF_TwoOCF (CF_Three)
COONH_Four, CF_ThreeCF_TwoCF_TwoO [CF (CF_Three)
CF_TwoO]_TwoCF (CF_Three) COONH_Four, CF_ThreeCF
_TwoCF_TwoO [CF (CF_Three) CF_TwoO]_ThreeCF (C
F_Three) COONH_Four, CF_ThreeCF_TwoCF _TwoCF_TwoCF_Two
OCF (CF_Three) COONH_FourEtc., perfluorohexa
Ammonium sulfonate, perfluoroheptane sulphate
Ammonium phonate, perfluorooctane sulfonic acid
Ammonium ammonium, perfluorononane sulfonate
Um, ammonium perfluorodecane sulfonate, etc.
Is mentioned.

Specific examples of lithium salts include lithium perfluoropentanoate, lithium perfluorohexanoate, lithium perfluoroheptanoate, lithium perfluorooctanoate, lithium perfluorononanoate, lithium perfluorodecanoate, lithium perfluorododecanoate, and ω-hydroperfluoro. Lithium heptanoate, ω-lithium hydroperfluorooctanoate, ω-
Lithium hydroperfluorononanoate, lithium ω-chloroperfluoroheptanoate, lithium ω-chloroperfluorooctanoate, lithium ω-chloroperfluorononanoate, etc., CF ₃ CF ₂ CF ₂ OCF (CF ₃ ) CO
_{OLi, CF 3 CF 2 CF 2} OCF (CF 3) CF 2 O
CF (CF ₃ ) COOLi, CF ₃ CF ₂ CF ₂ O [C
F (CF ₃ ) CF ₂ O] ₂ CF (CF ₃ ) COOLi,
CF ₃ CF ₂ CF ₂ O [CF (CF ₃ ) CF ₂ O] ₃ C
F (CF ₃ ) COOLi, CF ₃ CF ₂ CF ₂ CF ₂ C
Examples include F ₂ OCF (CF ₃ ) COOLi, lithium perfluorohexane sulfonate, lithium perfluoroheptane sulfonate, lithium perfluorooctane sulfonate, lithium perfluorononane sulfonate, lithium perfluorodecane sulfonate, and the like.

Specific examples of the sodium salt include sodium perfluoropentanoate, sodium perfluorohexanoate, sodium perfluoroheptanate, sodium perfluorooctanoate, sodium perfluorononanoate, sodium perfluorodecanoate, sodium perfluorododecanoate, and ω-hydroperfluoro. Sodium heptanoate, sodium ω-hydroperfluorooctanoate, sodium ω-hydroperfluorononanoate, sodium ω-chloroperfluoroheptanoate,
Sodium ω-chloroperfluorooctanoate, sodium ω-chloroperfluorononanoate, etc., CF ₃ CF ₂
CF ₂ OCF (CF ₃ ) COONa, CF ₃ CF ₂ CF
₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COON
a, CF ₃ CF ₂ CF ₂ O [CF (CF ₃ ) CF ₂ O]
₂ CF (CF ₃ ) COONa, CF ₃ CF ₂ CF ₂ O
[CF (CF ₃ ) CF ₂ O] ₃ CF (CF ₃ ) COON
_{a, CF 3 CF 2 CF 2} CF 2 CF 2 OCF (CF 3)
COONa and the like, sodium perfluorohexane sulfonate, sodium perfluoroheptane sulfonate, sodium perfluorooctane sulfonate, sodium perfluorononane sulfonate, sodium perfluorodecane sulfonate and the like can be mentioned.

Specific examples of the potassium salt include perfluor.
Potassium lopentate, potassium perfluorohexanoate
System, potassium perfluoroheptanoate, perfluoro
Potassium citrate, potassium perfluorononanoate,
Potassium rufluorodecanoate, perfluorododecanoic acid
Potassium, ω-hydroperfluoroheptanoic acid potassium
Ω-potassium hydroperfluorooctanoate, ω-
Potassium hydroperfluorononanoate, ω-chloroperone
Potassium fluoroheptanoate, ω-chloroperfluoro
Potassium octanoate, ω-chloroperfluorononanoic acid
CF such as potassium_ThreeCF_TwoCF_TwoOCF (CF_Three) CO
OK, CF_ThreeCF_TwoCF_TwoOCF (CF_Three) CF_TwoOC
F (CF_Three) COOK, CF_ThreeCF_TwoCF_TwoO [CF
(CF _Three) CF_TwoO]_TwoCF (CF_Three) COOK, CF
_ThreeCF_TwoCF_TwoO [CF (CF _Three) CF_TwoO]_ThreeCF
(CF_Three) COOK, CF_ThreeCF_TwoCF_TwoCF_TwoCF_Two
OCF (CF_Three) COOK, etc., perfluorohexanes
Potassium ruphonate, perfluoroheptane sulfonic acid
Lithium, potassium perfluorooctane sulfonate,
Rufluorononane sulfonate potassium, perfluorode
Examples thereof include potassium cansulfonate.

As the fluorine-containing emulsifier in the present invention,
Particularly, ammonium salts of perfluoroalkanoic acid having 6 to 12 carbon atoms are preferable, ammonium perfluoroheptanate, APFO, ammonium perfluorononanoate or ammonium perfluorodecanoate are more preferable, and APFO is most preferable.

In the present invention, the wastewater after the polymerization of the fluoropolymer means the wastewater after separating the fluoropolymer obtained by polymerizing at least one fluorine-containing monomer in an aqueous medium containing a fluoroemulsifier. In general, coagulation drainage of a fluoropolymer after emulsion polymerization is preferable, and coagulation drainage from a process of producing a polymer of a fluoromonomer or a copolymer of a fluoromonomer and a monomer other than the fluoromonomer is particularly preferable. Specifically, the coagulated wastewater from the production step is obtained by subjecting a fluorinated monomer or a fluorinated monomer and a monomer other than the fluorinated monomer to emulsion polymerization or aqueous dispersion polymerization in an aqueous medium containing a fluorinated emulsifier. The wastewater after the fluoropolymer is separated from the fluoropolymer aqueous dispersion by coagulating the fluoropolymer by salting out or the like. The wastewater contains the fluorine-containing emulsifier used at the time of polymerization of the fluorine-containing monomer, and also contains SS components such as unaggregated fluorine-containing polymer. Hereinafter, the coagulated waste water will be described as a typical example.

As the fluorine-containing monomer, tetrafluoroethylene (hereinafter referred to as TFE), CF ₂ ═CFC
_{l, CFH = CF 2, CFH} = CH 2, CF 2 = CH 2
(Hereinafter referred to as VdF), such as fluoroethylene, hexafluoropropylene (hereinafter referred to as HEP), CF
₂ = fluoropropylene such as CHCF ₃ , CF ₂ = CF
OCF ₃ , CF ₂ = CFO (CF ₂ ) ₂ CF ₃ (hereinafter,
It is called PPVE. ), CF ₂ = CFO (CF ₂ ) ₄ CF
Perfluorovinyl ether having 3 to 10 carbon atoms such as ₃ and 4 carbon atoms such as CH ₂ ═CH (CF ₂ ) ₃ CF ₃
Examples include (perfluoroalkyl) ethylene of 10 to 10 and the like. These fluorine-containing monomers may be used alone or in combination of two or more.

As the monomers other than the fluorine-containing monomer, vinyl acetate such as vinyl acetate, vinyl ether such as ethyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, norbornene,
Monomers having a cyclic structure such as norbornadiene, allyl ethers such as methyl allyl ether, ethylene (hereinafter referred to as E
Say. ), Propylene (hereinafter referred to as P), olefins such as isobutylene, and the like. Monomers other than the fluorine-containing monomer may be used alone or in combination of two or more kinds.

In the present invention, the fluoropolymer includes PTFE, TFE / P copolymer, TFE / P / Vd.
F copolymer, TFE / HFP copolymer, PFA / PPV
Examples thereof include E copolymers, E / TFE copolymers, and polyvinylidene fluoride. More preferably, PTFE or TFE
/ P copolymer, TFE / P / VdF copolymer or PFA
/ PPVE copolymer, most preferably PTFE
Is.

In producing a layered double hydroxide containing a fluorine-containing emulsifier between layers, a method of adding divalent and trivalent metal ions to the aggregated wastewater of the fluoropolymer (hereinafter referred to as coprecipitation method), Method of adding layered double hydroxide produced in a solution containing no fluorinated emulsifier to coagulated wastewater of fluoropolymer (hereinafter referred to as ion exchange method), and layered produced in solution containing no fluorinated emulsifier A method in which the double hydroxide is calcined and then added to the aggregated wastewater of the fluoropolymer (hereinafter referred to as a reconstitution method) can be used.

In the present invention, potassium hydroxide and / or sodium hydroxide is added in advance to the aggregated wastewater of the fluoropolymer and the solution containing no fluorine-containing emulsifier in the ion exchange method and the reconstitution method. p
H is adjusted to 6 or more and 9 or less when using aluminum ions and zinc ions, and 9 or more and 11 or less when using aluminum ions and magnesium ions. When the pH is out of the above range, in the method of adding a salt of aluminum and zinc or a salt of aluminum and magnesium to the waste water, each of these metals individually forms a hydroxide, and aluminum hydroxide and hydroxide are added. Since zinc and magnesium hydroxide are formed, it becomes difficult to form a layered double hydroxide, and as a result, the recovery efficiency of the fluorinated emulsifier is significantly reduced. Further, in the method of adding the layered double hydroxide to the waste water, these metals are eluted from the layered double hydroxide, resulting in a marked decrease in the efficiency of recovering the fluorine-containing emulsifier.

In the present invention, the concentration of the fluorine-containing emulsifier as the recovery target is preferably 1 ppm (mass basis, the same applies below) or more and 10% by mass or less, more preferably 10 ppm or more and 1% by mass or less, and particularly 50 ppm or more and 0.5% or more. It is preferably not more than mass%. When the concentration of the fluorinated emulsifier is 1 ppm or more, there is no problem that the efficiency of capturing the fluorinated emulsifier by the layered double hydroxide in the recovered liquid is lowered. If the concentration of the fluorinated emulsifier is higher than 10% by mass, a simpler and more efficient method can be used, such as changing the pH to precipitate the fluorinated emulsifier.

[0024] Floating solids such as uncoagulated fluoropolymer fine particles contained in the coagulated waste water and substances that can become floating solids (hereinafter, these are collectively referred to as SS components).
Does not adversely affect the recovery and the recovery rate of the fluorinated emulsifier, but may interfere with the regeneration of the fluorinated emulsifier from the generated layered double hydroxide, so that before the formation of the layered double hydroxide. It is important to remove up to 1 mass% or less. The SS component in the coagulated waste water is more preferably removed up to 0.3% by mass, and especially 0.0
It is preferable to remove up to 5% by mass. In addition, as the substance which can be a floating solid content, the metal salt used for salting out and coagulating the fluoropolymer and / or p of the coagulation wastewater is used.
A substance that precipitates due to a change in H may be used. As a method for removing the SS component such as the non-aggregated fluoropolymer, SS is prepared by adding a metal salt containing a polyvalent metal cation.
Salting out to agglomerate the components is effective. Specific examples of the metal salt include aluminum chloride, polyaluminum chloride,
Examples include metal chlorides such as ferrous chloride and ferric chloride.
In addition, the aggregate formed by salting out may precipitate in a state where APFO is contained. Therefore, by adding sodium hydroxide and / or potassium hydroxide to adjust the pH to 7 or more, the APFO is aggregated. It is preferable to redissolve the product in water. A general solid-liquid separation method can be adopted as a method for removing the aggregate of the SS component that has been aggregated by adding the metal chloride to the aggregated wastewater, and in particular, it comprises filtration, decantation, centrifugation and thickener. It is more preferable to use one or more methods selected from the group. Filtration is also preferably carried out under pressure. Further, it is preferable to remove the aggregates by allowing the wastewater containing the aggregates to stand, allowing the aggregates to settle, and filtering the supernatant. Also, from the viewpoint of ease of equipment maintenance,
Most preferred are thickeners or screw decanters.

In the present invention, the trivalent metal (3 when ionized is used to form the layered double hydroxide).
The metal which becomes a valent ion) and the divalent metal (a metal which becomes a divalent ion when ionized) have a pH range in which the ion of the trivalent metal forms a hydroxide and an ion of the divalent metal. Form overlapping hydroxides, or layered double hydroxides can be formed if these pH ranges are close to each other. Examples of the divalent metal include beryllium, cadmium, cobalt, chromic (II) acid, copper (II), iron (I
I), magnesium, manganese (II), nickel, lead,
Platinum, palladium, zinc, tin, calcium and the like can be exemplified, and examples of the trivalent metal include aluminum, bismuth, cerium, chromium (III), iron (III), gallium,
Indium, manganese (III), titanium, thallium and the like can be exemplified, but in consideration of the influence on the environment and the availability, in the present invention, one or two selected from magnesium and zinc are used as the divalent metal. It is preferable to use aluminum as the trivalent metal. Less than,
The case of using the preferred divalent metal and trivalent metal will be described.

In the present invention, as described above, the p of the drainage is
When H is a layered double hydroxide of aluminum and magnesium, H is adjusted to 9 or more and 11 or less. Then, the molar ratio of aluminum ion to magnesium ion is 1 :.
2, and the concentration of aluminum ion and magnesium ion is 0.01 mol / L or more and 2 mol / L, respectively.
An aqueous solution of L or less is added with stirring. Aluminum ion and magnesium ion, no matter which raw material is used, from the ease of availability, aluminum ion is preferably aluminum chloride, aluminum chloride hexahydrate, aluminum sulfate, aluminum nitrate,
Aluminum chloride and aluminum chloride hexahydrate are more preferable. As a raw material of magnesium ion, it is preferable to use magnesium chloride, magnesium chloride hexahydrate, magnesium nitrate hexahydrate, magnesium nitrate, magnesium oxide, magnesium sulfate, magnesium sulfate heptahydrate, magnesium carbonate, and especially magnesium chloride. , Magnesium chloride hexahydrate is preferred.

In the present invention, as described above, the p of the drainage is
When H is a layered double hydroxide of aluminum and zinc, H is adjusted to 6 or more and 9 or less. Then, the molar ratio of aluminum ion to zinc ion is 1: 2, and the concentration of aluminum ion and zinc ion is 0.01 mo, respectively.
An aqueous solution of 1 / L or more and 2 mol / L or less is added with stirring. Aluminum ion and zinc ion can be used with any raw material, but due to their easy availability,
The aluminum ion is preferably aluminum chloride, aluminum chloride hexahydrate, aluminum sulfate or aluminum nitrate, more preferably aluminum chloride or aluminum chloride hexahydrate. As the zinc ion raw material, zinc chloride, zinc nitrate hexahydrate, zinc oxide, zinc sulfate, zinc sulfate heptahydrate are preferably used, and zinc chloride is more preferable.

A mixed aqueous solution containing divalent and trivalent metal ions (hereinafter referred to as a metal ion aqueous solution) is 0.01 mol / L.
It is preferably used in an aqueous solution of 2 mol / L or less.
If the metal ion concentration is lower than this, the amount of water increases when the necessary metal is added, and the total amount of the layered double hydroxide dissolved in the aqueous solution increases, which is not preferable. When the metal ion concentration is higher than this, the aqueous metal ion solution is acidic, and therefore when the layered double hydroxide is formed, a part of the aqueous solution is locally added by the addition of the metal ion aqueous solution. If the pH is out of the optimum range for forming the metal, the metal ions will not be effectively used for forming the layered double hydroxide. However, even if a metal ion aqueous solution having a concentration outside the above range is added, the layered double hydroxide can be synthesized by adding a metal ion aqueous solution having an appropriate concentration range again.

The amount of the layered double hydroxide added to the aggregated wastewater of the fluorine-containing polymer is such that the trivalent ions in the layered double hydroxide are 1 mol times or more and 30 mol times or less with respect to the fluorine-containing emulsifier, Moreover, it is preferable that the divalent ion is 1 mol times or more and 60 mol times or less with respect to the fluorine-containing emulsifier. The molar ratio of trivalent ions to divalent ions in the layered double hydroxide is 3:
1 to 1: 3 is preferable, and 1: 1 to 1: 3 is more preferable. By setting the addition amount of the layered double hydroxide calcined to 1 mol times or more, the recovery rate of the fluorinated emulsifier becomes good, and by controlling the addition amount of the layered double hydroxide to the above range or less, Since the ratio of the fluorinated emulsifier to the layered double hydroxide becomes too small, it is possible to eliminate the problem that the final regeneration efficiency of the fluorinated emulsifier is lowered. Further, the excessive use of the layered double hydroxide is not preferable from the viewpoint of increasing the load of the final wastewater treatment process due to the contained metal component.

In the present invention, it is preferable to stir the fluorine-containing emulsifier-containing wastewater or water when adding the metal ion aqueous solution to the fluorine-containing emulsifier-containing wastewater or water. The stirring method is not particularly limited, but a method that does not mechanically break the aggregate particles generated by stirring is preferable. The stirring blade of such a stirring device is preferably a stirring blade capable of uniformly mixing the entire drainage at low speed rotation, and one kind selected from the group consisting of a full zone blade, a Maxblend blade or an anchor blade is preferable. The G value at the time of stirring by the stirring blade is preferably ¹ to 300 s ⁻¹ , and 5 to 250
s ⁻¹ is more preferable, and 10 to 200 s ⁻¹ is most preferable. Here, the G value means a value derived by the following formula.

[0031]

[Equation 1]

[Wherein, P is a stirring power (W), V is a liquid volume (m ³ ), and η is a liquid viscosity coefficient (Pa · s). ]

In the coprecipitation method and the ion exchange method, in order to remove carbonate ions and / or carbon dioxide gas existing in the system during dropping of the metal ion aqueous solution, bubbling with an inert gas such as nitrogen gas or argon gas, or After expelling carbonate ions and / or carbon dioxide with an inert gas, it is preferable to seal the reaction vessel. This is because the layered double hydroxide reacts with carbonate ions and hinders the recovery of the fluorinated emulsifier. The flow rate of the inert gas when carrying out the bubbling 0.1Nm ³ / h~10Nm ³ / h
^Preferably, 0.1Nm ³ / ^h~5Nm 3 / h is more preferable. By setting the gas flow rate to 0.1 Nm ³ / m ³ · h or more, the carbonate ions in the system can be sufficiently removed, and by setting it to 10 Nm ³ / m ³ · h or less, the heat of vaporization causes The problem that the temperature of the aqueous solution is lowered can be prevented.

In the reconstructing method, the firing of the layered double hydroxide is preferably performed at 300 ° C. or higher and lower than 600 ° C. 4
It is more preferable that the temperature is 00 ° C or higher and lower than 500 ° C. If the temperature is lower than this, the entrapped carbonate ions are not sufficiently desorbed, or a long time is required for sufficient desorption. Further, at a temperature higher than this, the crystal structure of the layered double hydroxide collapses, which causes a decrease in the recovery efficiency of the fluorinated emulsifier.

The water temperature during the reaction is preferably 10 ° C. or higher and 50 ° C. or lower. If the water temperature is lower or higher than this, the recovery rate of the fluorinated emulsifier by the layered double hydroxide will be reduced. In particular, since the recovery rate at water temperatures below this is markedly reduced, it is preferable to equip the reactor with a heating device. In this way, in the coagulated waste water, since the layered double hydroxide containing the fluorine-containing emulsifier between the layers is generated,
The fluorinated emulsifier can be recovered by separating the produced layered double hydroxide from the coagulated waste water. As a method for separating the layered double hydroxide from the aggregated wastewater, a well-known solid-liquid separation method can be appropriately used, in particular, filtration,
It is more preferable to use one or more methods selected from the group consisting of decantation, centrifugation and thickener. Filtration is also preferably carried out under pressure. Further, the fluorinated emulsifier recovered in the form of being encapsulated in the layered double hydroxide is, for example, redissolved layered double hydroxide with a strong acid such as hydrochloric acid and / or sulfuric acid and / or nitric acid, It can be regenerated by a method such as extraction with a non-water-soluble organic solvent.

The mineral acid used in the present invention includes
_HCl, include H ₂ SO 4, HNO _3. Especially, H
Cl is preferred. HCl is an acid with a boiling point of -85 ° C,
HCl mixed in the extract can be easily removed from the extract by a subsequent concentration operation.

The fluorine-containing hydrocarbon in the present invention is preferably one having 2 or 3 carbon atoms and containing at least one hydrogen atom and at least one fluorine atom. The boiling point of the fluorine-containing hydrocarbon is preferably 5 to 120 ° C., and 1
0-80 degreeC is more preferable. Within this range, the fluorine-containing hydrocarbon is easily distilled off and recovered, which is preferable.

As a specific example thereof, one or more selected from the group consisting of C ₃ HCl ₂ F ₅ and C ₃ H ₃ F ₅ is more preferable. As C ₃ HCl ₂ F ₅ , CF
₃ CF ₂ CHCl ₂ , CClF ₂ CF ₂ CHClF, C
ClF ₂ CHFCClF ₂ , CF ₃ CHFCCl ₂ F,
CF ₃ CHClCClF ₂ and CF ₃ CF ₂ C
Most preferred are HCl ₂ , CClF ₂ CF ₂ CHClF. C ₃ H ₃ F ₅ includes CF ₃ CH ₂ CHF ₂ , C
_{F 3 CHFCH 2 F, CHF 2} CHFCHF 2 and the _like, and most preferably CF ₃ CH ₂ CHF 2. That is,
As the fluorine-containing hydrocarbon, CF ₃ CF ₂ CHCl ₂ ,
CClF ₂ CF ₂ CHClF and CF ₃ CH ₂ CHF ₂
Most preferably, it is at least one selected from the group consisting of

The solubility of the fluorine-containing emulsifier in C ₃ HCl ₂ F ₅ and C ₃ H ₃ F ₅ is higher than that of dichloromethane and chloroform, and the fluorine-containing emulsifier can be extracted with a smaller amount of medium. Further, all of them are nonflammable, have low toxicity as compared with conventional chlorinated hydrocarbons, and their boiling points and latent heats of vaporization are suitable for concentration and recovery operations, which is preferable. Further, it is chemically stable as compared with conventional chlorinated hydrocarbons, and can be repeatedly used for concentration and recovery many times. Furthermore, when chlorinated hydrocarbons are used to extract the fluorinated emulsifier, it is necessary to treat chlorinated hydrocarbons that dissolve in the aqueous phase, whereas the solubility of fluorinated hydrocarbons in water is greater than that of chlorinated hydrocarbons. Since it is low, such processing is unnecessary. Further, there is an advantage that a clear liquid-liquid interface is formed between the aqueous phase and the fluorine-containing hydrocarbon phase more quickly after the extraction operation than in the case of chlorinated hydrocarbon.

In the present invention, conventionally used apparatus and equipment can be used for the extraction operation of the above-mentioned fluorine-containing emulsifier. Examples of the extraction device include a batch type extraction device, a parallel flow multiple extraction device, a countercurrent multistage extraction device, and a continuous countercurrent extraction device. As the extraction conditions, an acid solution of a layered double hydroxide containing a fluorinated emulsifier between layers and an extraction solvent are mixed at a temperature lower than the boiling point of the solvent. Usually, 20 to 100% by mass, preferably 30 to 50% by mass of the extraction solvent is added to the acid solution. By using a larger amount of extraction solvent, the extraction rate of the fluorinated emulsifier is improved, but the amount of solvent treated in the steps such as concentration is increased. Stir when mixing,
The extraction medium is dispersed in the acid solution by flowing, shaking or the like. When dispersion is performed so that the diameter of the droplets of the extraction medium is 0.1 mm or less, the extraction is completed in a mixing time of less than 10 minutes. After the extraction is completed, the mixture is left to stand to separate the aqueous phase and the medium phase. Separation is required until the interface between the two phases is clear, which is usually achieved with a rest time of less than 10 minutes.

[0041]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto. In addition, APF
The concentrations of O, perfluorooctanoic acid (hereinafter referred to as PFOA) or sodium perfluorooctanoate were measured by a high performance liquid chromatography-mass spectrometry method using a mixed solution of methanol and water as a solvent.
Species to be detected by this method is perfluorooctanoate ^- a _{(C 7} F 15 COO).

[Example 1] The concentration of APFO in the waste water after aggregation after the emulsion polymerization of PTFE was measured to find 14
It was 8 ppm. A 0.2N sodium hydroxide aqueous solution was added to this aqueous solution to adjust the pH to 10.0. The liquid temperature was 26 ° C. Next, 10 L of this solution (APFO content 1.48 g, 3.43 mmol) was added to a mixed aqueous solution of aluminum chloride and magnesium chloride [Al ³⁺ ion concentration 0.075 mol / L, Mg ²⁺ ion 0.15 mo.
1 / L] Approx. 229 mL [Al ³⁺ total ion amount 17.2 m
mol, total amount of Mg ²⁺ ions 34.3 mmol] was added dropwise over 2 hours. During the dropping, stirring was continued using an anchor blade so that the G value was 100 s ⁻¹ . Further, during the dropping of the metal ion aqueous solution, nitrogen gas was bubbled through the coagulated waste water at a constant flow rate of 1 Nm ³ / m ³ · h to remove dissolved carbonate ions and carbon dioxide gas in the aqueous solution. 0 during the drip.
A 2N sodium hydroxide aqueous solution is appropriately added dropwise to adjust the pH to 9.
It was adjusted to 8 or more and 10.2 or less. Immediately after the addition of the mixed aqueous solution of aluminum chloride and magnesium chloride, an extremely thin milky white liquid started to aggregate and started to form a white precipitate. The generation of the precipitate was completed 2 hours after the start of the dropwise addition of the mixed aqueous solution. When the stirring was stopped, the generated precipitate rapidly settled, and completely settled in about 10 minutes. The supernatant was colorless and transparent. The precipitate was filtered with a 3 μm membrane filter. This precipitate was dried together with filter paper at 70 ° C. for 15 hours. The dry weight of the precipitate was 25.0 g. When the dried precipitate was analyzed by differential thermogravimetric analysis (DTA), infrared absorption spectrum (IR) and XRD, peaks attributed to PTFE, peaks attributed to PFOA and peaks attributed to layered double hydroxide were detected. Was done. From this,
It was confirmed that this precipitate was a precipitate of PTFE and PFOA together with the layered double hydroxide. When the supernatant was analyzed, the concentration of APFO was 2 ppm,
Fixing rate of PFOA contained in layered double hydroxide is 98.6.
%Met. The precipitate is then added with 100% by mass of hydrochloric acid of 100%.
g, and after stirring at room temperature for 3 hours, CF ₂ ClCF
₂ CHClF / CF ₃ CF ₂ CHCl ₂ mixed medium (molar ratio 55/45, Asahi Kulin 225 manufactured by Asahi Glass Co., Ltd., hereinafter,
It is called AK225. ) Was added and shaken vigorously for 10 minutes. After the liquid was allowed to stand and separated into two phases, 0.14% by mass of PFOA was added to the upper aqueous phase and AK225 of the lower layer.
The phase contained 4.03 wt.% PFOA. The recovery rate from the original coagulated waste water was 85.1%.

Example 2 As for the same waste water after aggregation after the emulsion polymerization of PTFE as in Example 1, 0.2N was added to this aqueous solution.
The sodium hydroxide aqueous solution of was added to adjust the pH to 7.0. The liquid temperature was 26 ° C. Then 10 L of this solution
(APFO content 1.48 g, 3.43 mmol) mixed aqueous solution of aluminum chloride and zinc chloride [Al ³⁺ ion concentration 0.075 mol / L, Zn ²⁺ ion 0.15
mol / L] about 45.8 mL [total amount of Al ^{3 +} ions 3.
43 mmol, total amount of Zn ²⁺ ions 6.86 mmol]
Was added dropwise over 2 hours. During the dropping, stirring was continued using an anchor blade so that the G value was 100 s ⁻¹ . Also,
Nitrogen gas was added at 1 Nm ³ / m ³ during the dropping of the metal ion aqueous solution
The bubbling of the aggregated wastewater was carried out at a constant flow rate of h to remove dissolved carbonate ions and carbon dioxide gas in the aqueous solution. During the dropping, 0.2N aqueous sodium hydroxide solution is added dropwise to adjust the pH.
Was adjusted to 6.5 or more and 7.5 or less. Immediately after the addition of the mixed aqueous solution of aluminum chloride and zinc chloride, an extremely thin milky white liquid began to aggregate and started to form a white precipitate. The generation of the precipitate was completed 2 hours after the start of the dropwise addition of the mixed aqueous solution. When the stirring is stopped, the generated precipitate quickly settles,
Complete sedimentation occurred in about 10 minutes. The supernatant was colorless and transparent. The precipitate was filtered with a 3 μm membrane filter. When the supernatant was analyzed, the concentration of APFO was 2 ppm
Therefore, the fixing ratio of PFOA contained in the layered double hydroxide was 98.9%. Then, 100 g of 10% by mass hydrochloric acid was added to the precipitate, the mixture was stirred at room temperature for 3 hours, 30 g of AK225 was added, and the mixture was vigorously shaken for 10 minutes. After the liquid was allowed to stand and separated into two phases, the upper aqueous phase contained 0.14 mass% PFOA, and the lower AK225 phase contained 4.06 mass% PFOA. The recovery rate from the original coagulated waste water was 85.8%.

Example 3 The same as in Example 1 except that the pH of the drainage after coagulation after the emulsion polymerization of PTFE was adjusted to 10.0 by using potassium hydroxide instead of sodium hydroxide. The same operation was performed. The fixing rate of PFOA contained in the layered double hydroxide was 97.5%, and when AK225 extraction was performed by the same method as in Example 1, the recovery rate from the original wastewater was 84.1%.

Example 4 The same as in Example 2, except that the pH of the waste water after coagulation after the emulsion polymerization of PTFE was adjusted to 7.0 by using potassium hydroxide instead of sodium hydroxide. The same operation was performed. The fixing rate of PFOA contained in the layered double hydroxide is 98.6%,
When AK225 extraction was performed by the same method as in Example 1, the recovery rate from the original waste water was 84.9%.

Comparative Example 1 The same operation as in Example 1 was carried out for the same coagulated waste water after emulsion polymerization of PTFE as in Example 1, except that 30 g of trichloromethane was used as the extraction medium. The fixing rate of PFOA contained in the layered double hydroxide was 98.1%, and when trichloromethane extraction was performed, the recovery rate from the original wastewater was 76.7%.

Comparative Example 2 The same operation as in Example 1 was carried out for the same coagulated waste water after emulsion polymerization of PTFE as in Example 1 except that 30 g of dichloromethane was used as the extraction medium. The fixing rate of PFOA contained in the layered double hydroxide was 97.8%, and when the dichloromethane extraction was performed, the recovery rate from the original wastewater was 70.2%.

[Example 5] The same fixing operation as in Example 1 was carried out for the same coagulated waste water after emulsion polymerization of PTFE as in Example 1. The fixing rate of PFOA contained in the layered double hydroxide was 97.8%. AK225 extraction was carried out in the same manner as in Example 1 except that 100 g of 3% by mass sulfuric acid was used instead of 100 g of 10% by mass hydrochloric acid as the mineral acid used for dissolving the layered double hydroxide. The recovery rate was 83.7%.

Example 6 The same fixing operation as in Example 1 was carried out for the same coagulated waste water after emulsion polymerization of PTFE as in Example 1. The fixing rate of PFOA contained in the layered double hydroxide was 98.1%. As a mineral acid used for dissolving the layered double hydroxide, 10 g of hydrochloric acid of 10% by mass is used instead of 100 g.
When AK225 extraction was performed by the same method as in Example 1 except that 100 g of nitric acid with a mass% was used, the recovery rate from the original waste water was 84.5%.

Example 7 The pH was adjusted to 10.0 by adding 0.2N aqueous sodium hydroxide solution to distilled water.
The liquid temperature was 26 ° C. Next, 1 L of this solution was mixed with an aqueous solution of aluminum chloride and magnesium chloride [Al ³⁺ ion concentration 0.075 mol / L, Mg ²⁺ ion 0.15
mol / L] about 229 mL [Al ³⁺ total ion amount 17.
2 mmol, total amount of Mg ²⁺ ions 34.3 mmol] was added dropwise over 2 hours. While dropping, use the anchor blade to
Stirring was continued until the value was 100 s ⁻¹ . Further, nitrogen gas was added at 1 Nm ³ / m ³ ·
The coagulated waste water was bubbled at a constant flow rate of h to remove dissolved carbonate ions and carbon dioxide gas in the aqueous solution. During the dropping, a 0.2N sodium hydroxide aqueous solution was appropriately dropped to adjust the pH to 9.8 or more and 10.2 or less. Immediately after the addition of the mixed aqueous solution of aluminum chloride and magnesium chloride, an extremely thin milky white liquid started to aggregate and started to form a white precipitate. The generation of the precipitate was completed 2 hours after the start of the dropwise addition of the mixed aqueous solution. When the stirring was stopped, the generated precipitate slowly settled. The precipitate was filtered with a 3 μm membrane filter. Then, using APFO as an emulsifier, T
PTFE from an aqueous dispersion of PTFE obtained by polymerizing FE
Coagulation wastewater after coagulation / separation (SS component is 400pp
m, APFO concentration is 148 ppm, pH 4.5) 10
A precipitate of the layered double hydroxide collected by filtration was added to L and stirred at room temperature for 1 hour. When the stirring was stopped, the precipitate slowly settled. The precipitate was filtered with a 3 μm membrane filter. When the supernatant was analyzed, the concentration of APFO was 63 ppm, and thus the fixing rate of PFOA contained in the layered double hydroxide was 57.4%. Then, 100 g of 10 mass% hydrochloric acid was added to the precipitate, and the mixture was stirred at room temperature for 3 hours.
After stirring for 30 hours, 30 g of AK225 was added and shaken vigorously for 10 minutes. After the liquid was allowed to stand and separated into two phases, 0.05% by mass of PFOA was added to the upper aqueous phase and AK of the lower layer.
The 225 phase contained 2.58 wt% PFOA.
The recovery rate from the original coagulated waste water was 53.7%.

Example 8 A 0.2N aqueous sodium hydroxide solution was added to distilled water to adjust the pH to 10.0.
The liquid temperature was 26 ° C. Sodium carbonate 1.82 there
g (17.2 mmol) was dissolved. Next, to 1 L of this diluted sodium carbonate aqueous solution, a mixed aqueous solution of aluminum chloride and magnesium chloride [Al ³⁺ ion concentration 0.07
5 mol / L, Mg ²⁺ ion 0.15 mol / L] about 229 mL [Al ³⁺ ion total amount 17.2 mmol, M
g ²⁺ ion total amount 34.3 mmol] was added dropwise over 2 hours. Further, during the dropping of the metal ion aqueous solution, nitrogen gas was bubbled through the coagulated waste water at a constant flow rate of 1 Nm ³ / m ³ · h to remove dissolved carbonate ions and carbon dioxide gas in the aqueous solution. G value is 100s using the anchor blade during dripping
Stirring was continued until it became ^-1 . During the dropping, 0.2N aqueous sodium hydroxide solution is appropriately dropped to adjust the pH to 9.8 or more 1.
It was adjusted to 0.2 or less. Immediately after the addition of the mixed aqueous solution of aluminum chloride and magnesium chloride, an extremely thin milky white liquid started to aggregate and started to form a white precipitate. The generation of the precipitate was completed 2 hours after the start of the dropwise addition of the mixed aqueous solution.
When the stirring was stopped, the generated precipitate slowly settled.
The precipitate was filtered with a 3 μm membrane filter. The precipitate was baked together with the filter paper in an electric furnace at 400 ° C. for 3 hours. The weight of the precipitate after baking was 1.4 g. On the other hand, P obtained by polymerizing TFE using APFO as an emulsifier
Aggregated waste water after coagulating and separating PTFE from an aqueous dispersion of TFE (SS component is 400 ppm, APFO concentration is 1
The precipitate of the layered double hydroxide baked above was added to 10 L of 48 ppm, pH 4.5) and stirred at room temperature for 1 hour. When the stirring was stopped, the precipitate slowly settled. The precipitate was filtered with a 3 μm membrane filter. When the supernatant was analyzed, the concentration of APFO was 121 ppm, so that the fixing rate of PFOA contained in the layered double hydroxide was 18.2%. Then 10% by mass of the precipitate
100 g of hydrochloric acid was added and stirred at room temperature for 3 hours.
30 g of K225 was added and shaken vigorously for 10 minutes. After the liquid was allowed to stand and separated into two phases, the upper aqueous phase had a pH of 0.
01% by mass PFOA, 0.8 in the lower AK225 phase
It contained 5% by weight of PFOA. The recovery rate from the original coagulated waste water was 17.4%.

Example 9 The same procedure as in Example 1 was carried out on the layered double hydroxide to fix APFO to the drainage after coagulation after the same emulsion polymerization of PTFE as in Example 1.
The fixing rate of PFOA contained in the layered double hydroxide is 97.8.
%, Then CHF ₂ CH ₂ instead of AK225
An extraction operation was performed in the same manner as in Example 1 except that 30 g of CF ₃ was used, and the recovery rate from the original waste water was 7
It was 9.4%.

[0053]

According to the recovery method of the present invention, the fluorine-containing emulsifier can be economically recovered by a simple operation.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoichi Amase             Asahi Glass Co., Ltd. 10 Goi Coast, Ichihara City, Chiba Prefecture             In the company (72) Inventor Masataka Eda             Asahi Glass Co., Ltd. 10 Goi Coast, Ichihara City, Chiba Prefecture             In the company (72) Inventor Hiroki Kamiya             Asahi Glass Co., Ltd. 10 Goi Coast, Ichihara City, Chiba Prefecture             In the company (72) Inventor Kota Omori             3-1-6 Ibaraki, Akita City, Akita Prefecture             Within Emco (72) Inventor Takeshi Kamiya             3-1-6 Ibaraki, Akita City, Akita Prefecture             Within Emco F-term (reference) 4D038 AA08 AB02 AB14 BB05 BB13                 4D056 AB17 AC04 BA03 CA01 CA31                       CA39                 4D077 AB14 AC01 DC02X DC38X                       DC72X

Claims (8)

[Claims] 1. A fluorine-containing solution containing a mixed aqueous solution containing divalent metal ions and trivalent metal ions, a fluorine-containing emulsifier, and a content of suspended solids and substances capable of becoming suspended solids of 1% by mass or less. The wastewater after polymerization of the polymer is
Mixing while maintaining the pH at which the layered double hydroxide of the valent metal and the trivalent metal is formed to form a layered double hydroxide containing a fluorine-containing emulsifier between the layers, and subsequently, the layered separated from the waste water. A method for recovering a fluorinated emulsifier, which comprises dissolving a double hydroxide in mineral acid and extracting the fluorinated emulsifier from the solution using a fluorinated hydrocarbon. 2. A layered complex is prepared by adding a mixed aqueous solution containing a divalent metal ion and a trivalent metal ion to an aqueous solution kept at a pH at which a layered double hydroxide of the divalent metal and the trivalent metal is formed. Hydroxide is generated in advance, and this is added to the wastewater after polymerization of the fluoropolymer, containing a fluorine-containing emulsifier, and having a content of suspended solids and substances capable of becoming suspended solids of 1% by mass or less, A layered double hydroxide containing a fluorinated emulsifier between layers is produced, and then the layered double hydroxide separated from the waste water is dissolved in a mineral acid, and the fluorine-containing hydrocarbon is used from the solution. A method for recovering a fluorine-containing emulsifier for extracting an emulsifier. 3. A mixed aqueous solution containing a divalent metal ion and a trivalent metal ion is added to an aqueous solution maintained at a pH at which a layered double hydroxide of the divalent metal and the trivalent metal is formed. By firing the layered double hydroxide, to produce a layered double hydroxide desorbing the encapsulating anion, containing a fluorine emulsifier, the content of substances that can be floating solids and floating solids is 1% by mass or less of fluorinated polymer is added to wastewater after polymerization to form a layered double hydroxide containing a fluorinated emulsifier between layers, and subsequently, the layered double hydroxide separated from the wastewater is treated with a mineral acid. A method for recovering a fluorinated emulsifier, which comprises dissolving the fluorinated emulsifier in a solvent and extracting the fluorinated emulsifier from the solution using a fluorinated hydrocarbon. 4. The fluorine-containing compound according to claim 1, wherein the divalent metal ion is one or two selected from magnesium ion and zinc ion, and the trivalent metal ion is aluminum ion. Emulsifier recovery method. 5. The method for recovering a fluorinated emulsifier according to claim 1, wherein the mineral acid is one or more selected from the group consisting of hydrochloric acid, nitric acid and sulfuric acid. 6. The fluoropolymer is polytetrafluoride.
Ethylene, tetrafluoroethylene / ethylene copolymer, tetrafluoroethylene
Ethylene fluoride / propylene copolymer, ethylene tetrafluoride
/ Propylene / Vinylidene Fluoride Copolymer, Tetrafluoride
Tylene / hexafluoropropylene copolymer, tetrafluoroethylene
/ CF_Two= CFO (CF_Two)_TwoCF _ThreeCopolymer, poly
One or more selected from vinylidene fluoride
The fluorinated emulsifier according to any one of claims 1 to 5
Collection method. 7. The fluorinated emulsifying agent is ammonium perfluorooctanoate.
7. The method for recovering a fluorinated emulsifier according to any one of 1 to 6. 8. The concentration of the fluorinated emulsifier is 1 mass pp.
The method for recovering a fluorine-containing emulsifier according to any one of claims 1 to 7, wherein the fluorine-containing emulsifier is recovered from wastewater after the polymerization of the fluorine-containing polymer which is m or more and 10 mass% or less.