JP2010234250A - Method for decomposing fluorine-containing organic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of efficiently decomposing a fluorine-containing organic compound included in an aqueous medium. <P>SOLUTION: The fluorine-containing organic compound is decomposed by electrolyzing a liquid substance in which the fluorine-containing organic compound is contained in the aqueous medium at a current density of 0.1 to 200 A/dm<SP>2</SP>using an electrode having an oxygen overvoltage and also chemically stable as an anode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for decomposing a fluorine-containing organic compound.

  The fluorine-containing organic compound is used as an emulsifier for emulsion polymerization to obtain a fluorine-containing polymer. Among the fluorine-containing organic compounds, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have been pointed out to be difficult to decompose and accumulate in the body. It is desirable to remove as much as possible.

  Conventionally, adsorption removal by activated carbon has been used as a method for removing fluorine-containing organic compounds in an aqueous medium. However, such adsorption removal is not always satisfactory because the adsorption efficiency is not so high, the cost of activated carbon is high, and the adsorbed activated carbon needs to be appropriately treated as industrial waste.

  Therefore, it has been proposed that the fluorine-containing organic compound is decomposed and removed by shortening the chain instead of adsorbing and removing (see Patent Document 1). In this method, a fluorine-containing organic (acid) compound contained in an aqueous medium is decomposed in the presence of hydrogen peroxide and / or ozone.

JP 2006-169146 A JP-A-11-269686

  According to the method disclosed in Patent Document 1, it is said that a fluorine-containing organic (acid) compound can be decomposed (short chain). However, the decomposition rate (the amount of decomposed compound / the amount of compound before decomposition × 100 (%)) is low even when a reducing agent is used in addition to hydrogen peroxide, and is not efficient (hydrogen peroxide and reduction). In Examples 1 and 2 to which an agent was added, 28.15% and 6.4% are described, respectively, and in Example 3 where UV irradiation was performed, 38.5% is described). Further, a relatively long treatment time is required (in Examples 1 and 2 to which hydrogen peroxide and a reducing agent are added, 3 hours are described, and in Example 3 in which UV irradiation is performed, 8 hours is described). For this reason, there also exists a difficulty that a processing facility becomes large-scale.

  In general, hydrogen peroxide water, ozone water, a chlorine-based oxidant, or the like is used for processing organic substances contained in industrial wastewater. However, hydrogen peroxide water and ozone water are expensive and have a drawback that long-term storage is impossible. In addition, chlorinated oxidants may produce environmental hormones and carcinogenic substances after treatment. For example, they produce harmful substances such as trihalomethanes in the process of reaction between chlorinated oxidants themselves and organic substances. there is a possibility. Furthermore, there are concerns about problems such as safety and possible contamination during transportation.

  On the other hand, as a method for producing hydrogen peroxide, there is a method of generating oxygen, ozone and hydrogen peroxide by electrolyzing water using an anode including a conductive diamond structure (see Patent Document 2). ) However, this method is only known as a method for producing hydrogen peroxide (and oxygen and ozone).

  An object of the present invention is to provide a method capable of efficiently decomposing a fluorine-containing organic compound contained in an aqueous medium.

According to one aspect of the present invention, a liquid material containing a fluorine-containing organic compound in an aqueous medium using an electrode having an oxygen overvoltage and a chemically stable electrode as an anode, and having a current density of 0.1 to 200 A. A method for decomposing a fluorine-containing organic compound by electrolysis at / dm ² is provided.

  In the present invention, “electrolytic treatment” means that an electrode forming a pair of an anode and a cathode is immersed in an object to be treated (in the present invention, “a liquid material containing a fluorine-containing organic compound in an aqueous medium”). This refers to the operation of passing current from an external power supply. In addition, “decomposition” of the fluorine-containing organic compound means that a chemical bond in the fluorine-containing organic compound is broken to produce a compound different from the original fluorine-containing organic compound.

In this method for decomposing a fluorine-containing organic compound, an oxygen overvoltage and chemically stable electrode is used as an anode, and a liquid substance containing the fluorine-containing organic compound in an aqueous medium is converted to a current density of 0.1 to 200 A. / Dm ² to electrolyze water in the aqueous medium, avoiding oxygen generation at the anode due to oxygen overvoltage, and consumption of the anode by hydrogen peroxide and ozone (or Corrosion) can be prevented or reduced by its chemical stability, and OH radicals can be efficiently generated with a predetermined current density, which makes it possible to effectively decompose fluorine-containing organic compounds. .

  The present invention can be understood as decomposing a fluorine-containing organic compound by the action of OH radicals generated in the electrolysis treatment on the fluorine-containing organic compound. However, the present invention is not limited to this, and in the above electrolysis treatment, hydrogen peroxide and ozone are usually generated in addition to OH radicals, and fluorine-containing organic matter originates from these OH radicals, hydrogen peroxide and ozone. The compound may be decomposed. In the present invention, “because of OH radical, hydrogen peroxide and ozone” is not only directly caused by OH radical, hydrogen peroxide and ozone, but may be present in a liquid material during, for example, electrolysis treatment. It is meant to include cases due to radical species that may be generated by the reaction of components with OH radicals (or those that can function as an oxidant that can be generated by such reactions).

  Although this invention is not limited, decomposition | disassembly of a fluorine-containing organic compound can cut | disconnect the CC bond in a fluorine-containing organic compound, Preferably it can also cut | disconnect a C-F bond. The C—F bond is a very strong bond and is usually difficult to break, but according to the present invention, OH radicals can be generated efficiently (or in a large amount or at a high concentration). It is considered that the cutting of this is possible.

  The electrode used for the anode in the present invention is only required to have an oxygen overvoltage and be chemically stable. When water is electrolyzed, oxygen generation may occur at the anode. However, an electrode has “oxygen overvoltage” means that the electrode (anode) is subjected to an oxygen generation reaction equilibrium potential under the applicable electrolysis treatment conditions. If a high voltage (the difference corresponding to the oxygen overvoltage) is not applied, oxygen generation does not substantially occur. Further, the phrase “chemically stable” means that the electrode material does not chemically react (or hardly react) with the components in the liquid under the electrolysis treatment conditions to be applied.

  For example, an electrode comprising a material having a conductive diamond structure (hereinafter, also simply referred to as “conductive diamond structure electrode”) can be suitably used as such an electrode. The conductive diamond structure electrode has a large oxygen overvoltage and is suitable for generating OH radicals. Furthermore, the conductive diamond structure electrode is chemically extremely stable and hardly eluted (in an aqueous medium), and the electrode is less consumed (or corroded) even when exposed to hydrogen peroxide or ozone.

（式中、ＹはＨまたはＦを示す。ｘ１は４以上の整数を示し、ｙ１は０〜３の整数を示す。Ａは−ＳＯ_３Ｍまたは−ＣＯＯＭを示し、ＭはＨ、ＮＨ_４、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、ＫまたはＣａを示す。）で表される化合物、および
以下の一般式（ＩＩ）：

（式中、ｘ２は１以上の整数を示し、ｙ２は０〜１０の整数を示す。ＸはＦまたはＣＦ_３を示す。Ａは−ＳＯ_３Ｍ’または−ＣＯＯＭ’を示し、Ｍ’はＨ、ＮＨ_４、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、ＫまたはＣａを示す。）で表される化合物
からなる群から選択される少なくとも１種の含フッ素有機酸化合物であってよい。 In one embodiment of the present invention, the fluorine-containing organic compound is
The following general formula (I):

(In the formula, Y represents H or F. x1 represents an integer of 4 or more, y1 represents an integer of 0 to _3. A represents —SO ₃ M or —COOM, and M represents H, NH ₄ , A compound represented by Li, Na, Mg, Al, K or Ca), and the following general formula (II):

(In the formula, x2 represents an integer of 1 or more, y2 represents an integer of 0 to 10. X represents F or CF ₃ , A represents —SO ₃ M ′ or —COOM ′, and M ′ represents H. , NH ₄ , Li, Na, Mg, Al, K, or Ca.) may be at least one fluorine-containing organic acid compound selected from the group consisting of compounds represented by:

More specifically, the fluorine-containing organic acid compound represented by the above general formula (I) is perfluorocarboxylic acid and salts thereof, such as perfluorooctanoic acid and salts thereof (collectively referred to as “PFOA”). It may be. Examples of the salts include ammonium salts and sodium salts, preferably ammonium salts such as ammonium perfluorooctanoic acid (particularly referred to as “APFO”).
The fluorine-containing organic acid compound represented by the general formula (I) is perfluorosulfonic acid and salts thereof, for example, perfluorooctanesulfonic acid and salts thereof (collectively also referred to as “PFOS”). Good. Examples of salts include ammonium salts and sodium salts.
The fluorine-containing organic acid compound represented by the general formula (II) is 2,3,3,3-tetrafluoro-2- [1,1,2,3,3-hexafluoro-2- (trifluoromethoxy)]. It may be propanoic acid.

  According to the present invention, by using an electrode having oxygen overvoltage and a chemically stable electrode as an anode, a liquid material containing a fluorine-containing organic compound in an aqueous medium is electrolyzed at a predetermined current density. OH radicals can be generated by electrolysis of water to efficiently decompose a fluorine-containing organic compound (particularly PFOA or PFOS) contained in an aqueous medium.

  The method of the present invention is a very simple method that does not require the use of hydrogen peroxide water or ozone water, or the use of a chlorine-based oxidant, and only requires electrolysis. This method does not require a large-scale device.

It is the schematic of the electrolysis apparatus used in Example 1 and 2 of this invention.

  First, a liquid material containing a fluorine-containing organic compound in an aqueous medium is prepared.

  The fluorine-containing organic compound is not particularly limited as long as it has a C—C bond and a C—F bond, and may have any number of carbon atoms, and may have a substituent other than fluorine. Also good.

（式中、ＹはＨまたはＦを示す。ｘ１は４以上の整数を示し、好ましくは６以上であり、また、ｘ１の上限は特になく、フッ素系高重合体（ポリマー）であってよいが、フッ素系高重合体でない場合には、例えば１３以下、特に１０以下の整数であり得る。ｙ１は０〜３の整数を示し、好ましくは０〜２の整数、より好ましくは０である。Ａは−ＳＯ_３Ｍまたは−ＣＯＯＭを示し、好ましくは−ＣＯＯＭ’を示し、ＭはＨ、ＮＨ_４、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、ＫまたはＣａを示し、好ましくはＨおよびＮａを示す。）で表される化合物（エーテル酸素を有しないアニオン性化合物）、および
以下の一般式（ＩＩ）：

（式中、ｘ２は１以上の整数を示し、好ましくは６以上であり、また、ｘ２の上限は特になく、フッ素系高重合体（ポリマー）であってよいが、フッ素系高重合体でない場合には、例えば５以下、特に３以下の整数であり得る。ｙ２は０〜１０の整数を示し、好ましくは０〜３の整数である。ＸはＦまたはＣＦ_３、好ましくはＣＦ_３を示す。Ａは−ＳＯ_３Ｍ’または−ＣＯＯＭ’、好ましくは−ＣＯＯＭ’を示し、Ｍ’はＨ、ＮＨ_４、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、ＫまたはＣａを示し、好ましくはＨおよびＮａを示す。）で表される化合物（エーテル酸素を有するアニオン性化合物）
からなる群から選択される少なくとも１種の含フッ素有機酸化合物であってよい。 For example, the fluorine-containing organic compound is
The following general formula (I):

(In the formula, Y represents H or F. x1 represents an integer of 4 or more, preferably 6 or more, and there is no particular upper limit for x1, which may be a fluorine-based high polymer (polymer)). In the case where it is not a fluorine-based high polymer, it may be an integer of, for example, 13 or less, in particular, 10 or less, y1 represents an integer of 0 to 3, preferably an integer of 0 to 2, more preferably 0. Represents —SO ₃ M or —COOM, preferably —COOM ′, and M represents H, NH ₄ , Li, Na, Mg, Al, K, or Ca, and preferably represents H and Na. The compounds represented (anionic compounds without ether oxygen), and the following general formula (II):

(Wherein x2 represents an integer of 1 or more, preferably 6 or more, and there is no particular upper limit for x2, which may be a fluorine-based high polymer (polymer), but is not a fluorine-based high polymer) May be an integer of, for example, 5 or less, particularly 3 or less, y2 represents an integer of 0 to 10, and preferably an integer of 0 to _3. X represents F or CF ₃ , preferably CF ₃ . A represents —SO ₃ M ′ or —COOM ′, preferably —COOM ′, and M ′ represents H, NH ₄ , Li, Na, Mg, Al, K or Ca, and preferably represents H and Na. ) (Anionic compound having ether oxygen)
It may be at least one fluorine-containing organic acid compound selected from the group consisting of

  Among the fluorine-containing organic compounds represented by the general formula (I), PFOA and PFOS are desirably decomposed and are particularly suitable for the practice of the present invention. However, the present invention is not limited thereto, and the fluorine-containing organic compound represented by the general formula (I) or (II) can be decomposed even if it is a fluorine-based high polymer.

  The aqueous medium is not particularly limited as long as it is a liquid containing water, and for example, water itself or a mixture of water and an organic liquid compatible with water may be used. Examples of the “water-compatible organic liquid” include organic solvents (preferably containing no fluorine) such as alcohol, ether, ketone, and paraffin wax.

  In performing the electrolysis treatment, the fluorine-containing organic compound is contained in an aqueous medium to form a liquid material. The fluorine-containing organic compound may be dissolved in an aqueous medium or may be dispersed in an aqueous medium. In other words, the liquid material may be a solution or a dispersion. From the viewpoint of current efficiency and the like, the fluorine-containing organic compound is, for example, about 1 wt ppm to 25 wt%, preferably about 1000 wt ppm to 5 wt%, but is not limited thereto.

  In addition to the fluorinated organic compound and the aqueous medium, the liquid material includes a fluorinated polymer other than the fluorinated organic compound, an additive (for example, a surfactant, a chain transfer agent, a radical scavenger, etc.) and / or a by-product (for example, (Potassium iodide) may be further included.

Although not limited to this embodiment, the liquid material may be process water or waste water generated in the production of the fluorine-containing polymer, and as an emulsifier, as represented by the above-described general formula (I) or (II) Fluorine-containing organic compounds such as perfluorocarboxylic acid, more specifically perfluorooctanoic acid (PFOA) or ammonium perfluorooctanoic acid (APFO) may be included. Perfluorocarboxylic acid is an ionic surfactant and can be dissolved in an aqueous medium and exist in the form of ions. This liquid material may contain a fluorine-containing polymer remaining without being separated. The fluorine-containing polymer generally has a particle form and can be present, for example, in an amount of about 5% by weight or less of the entire liquid. Examples of fluoropolymers include the following:
VdF-based fluororubbers such as PVdF (polyvinylidene fluoride), VdF (vinylidene fluoride) / HFP (hexafluoropropylene) copolymer, and VdF / TFE (tetrafluoroethylene) / HFP copolymer;
TFE / Pr (propylene) copolymer [TFE-P] (trade name “Aphras” manufactured by Asahi Glass Co., Ltd.);
Non-perfluoro fluororesins such as Et (ethylene) / TFE copolymer [ETFE], Et / TFE / HFP copolymer [EFEP] and PCTFE (polychlorotrifluoroethylene); and TFE / PAVE which is a perfluoroelastomer (Perfluoroalkyl vinyl ether) copolymers (for example, TFE / PMVE (perfluoromethyl vinyl ether) copolymers [MFA] and TFE / PPVE (perfluoropropyl vinyl ether) copolymers [PFA]), low molecular weight PTFE (polytetrafluoroethylene) Fluoroethylene) (trade name “Lublon”, manufactured by Daikin Industries, Ltd.) and perfluororesin such as TFE / HFP copolymer [FEP].

  As the anode for the electrolysis treatment, an electrode having an oxygen overvoltage and chemically stable is used.

  Whether or not the electrode has an oxygen overvoltage can be determined by whether or not a voltage exceeding the standard electrode potential for oxygen generation (overvoltage) can be applied without substantially causing oxygen generation. Table 1 shows the standard oxidation-reduction potential (vs NHE (normal hydrogen electrode), pH = 7) of the reaction related to the electrolysis of water.

  As understood from Table 1, the standard oxidation-reduction potential of the oxygen generation reaction (in Table 1, Formula No. 1-7) is 1230 mV, and the OH radical generation reaction (in Table 1, Formula No. 1-1). The standard oxidation-reduction potential is 2850 mV (however, OH radicals generated from hydrogen peroxide and ozone, which will be described later, are different). If there is no oxygen overvoltage, oxygen generation occurs at the anode and OH radical generation occurs. It does n’t come. Therefore, the electrode used for the anode preferably has an oxygen overvoltage that can generate OH radicals. The potential of OH radical generation and other reactions can also be shifted from the equilibrium potential, but as a guide, the standard redox potential of the OH radical generation reaction of Table 1 (formula No. 1-1 in Table 1) can be used. .

  It is practically difficult to quantitatively measure OH radical generation. As can be seen from Table 1, under conditions where an OH radical generation reaction (formula No. 1-1 in Table 1) occurs at the anode, a hydrogen peroxide generation reaction (in Table 1) with a lower standard oxidation-reduction potential. , Formulas Nos. 1-4) and ozone generation reactions (in Table 1, Formulas Nos. 1-3 and 1-5) can also occur. Generally, it is considered that when the amount of hydrogen peroxide and ozone generated is large, the amount of OH radicals generated is also large. Therefore, the electrode used for the anode may be any electrode that can generate hydrogen peroxide and ozone more efficiently than oxygen under the applied electrolysis treatment conditions.

  Alternatively, when the potential window of the electrode is known, the fact that the standard oxidation-reduction potential of the OH radical generation reaction (formula No. 1-1 in Table 1) exists within the range of the potential window is used for the anode. It may be an index for selecting an electrode to be used. It should be noted that the potential window depends not only on the electrode material but also on the type and concentration of the supporting electrolyte (generally, a 1 mol / liter sulfuric acid aqueous solution is used).

  Further, whether or not the electrode is chemically stable can be determined based on whether or not it is corroded by an aqueous solution of hydrogen peroxide and ozone. This is because an aqueous solution of hydrogen peroxide and ozone is highly oxidative and forms an environment in which corrosion is likely to occur. Therefore, it is necessary to be at least chemically stable (not corroded) with respect to these aqueous solutions.

A conductive diamond structure electrode can be used for such an anode. Since the conductive diamond structure electrode has an sp ³ structure, it is chemically very stable, has both a large oxygen overvoltage and a hydrogen overvoltage and a wide potential window, and has a current efficiency for hydrogen peroxide and ozone generation. It is very high and is therefore suitable for generating OH radicals while avoiding oxygen generation at the anode. For example, electrodes made of noble metals such as platinum and iridium and carbon-based materials are also used to generate OH radicals, which corrode by an aqueous solution of hydrogen peroxide or ozone, and contamination due to electrode consumption and elution can be a problem. For structured electrodes, such problems are negligible. In addition, compared to electrodes made of noble metals such as platinum and iridium and carbon-based materials, the conductive diamond structure electrode has about twice the potential window, and the current efficiency of hydrogen peroxide and ozone generation is about 10 to 30 times. Also reach.

  More specifically, the material of the conductive diamond structure electrode is a composite material of diamond, which is doped with impurities such as boron (boron), phosphorus and / or graphite and imparted conductivity, amorphous boron oxide, and the like. , Silicon carbide, titanium carbide, tungsten carbide and the like, which are commercially available. Of these, boron-doped diamond has higher radical generation efficiency than an electrode such as nitrogen-doped.

  However, the electrode used for the anode is not limited to the conductive diamond structure electrode. For example, an electrode using a noble metal such as platinum or iridium, a carbon-based material, or the like may be used. However, compared with the conductive diamond structure electrode, the noble metal such as platinum and iridium and the electrode made of carbon-based material are not so chemically stable, and the noble metal electrode such as platinum and iridium is expensive.

  The electrode used for the cathode may be the same as or different from the electrode used for the anode. In the latter case, the cathode may be, for example, DSE (Dimensionally Stable Electrode), specifically, for example, a metal surface such as titanium coated with a metal oxide such as ruthenium oxide.

  These anode and cathode are immersed in the liquid material described above. The anode and the cathode are used in pairs, but their number, arrangement, area, etc. can be arbitrarily selected. The configuration of the entire electrolysis apparatus is not particularly limited, and may be a diaphragm or a diaphragm (for example, a two-chamber type or a three-chamber type). Or, it can be reversed irregularly.

Then, an electric current is passed from the external power source to the anode and the cathode to perform the electrolysis process. In this electrolysis treatment, the current density is, for example, 0.1 to 200 A / dm ² , preferably 1 to 50 A / dm ² . Other electrolysis treatment conditions such as temperature, pressure, pH, treatment time and the like can be set as appropriate. Most simply, a liquid material that is not pH-adjusted at normal temperature and normal pressure may be subjected to electrolysis. The processing time can be set so as to obtain a desired decomposition rate. Although it does not limit this invention, it may be 0-100 degreeC, pH1-14, for example, Preferably pH1-7.

  It is considered that hydrogen peroxide and ozone are generated at the anode and OH radicals are generated in the electrolysis treatment, particularly in the current density range. As described above, it is difficult to quantitatively analyze OH radicals directly, but generally, it is considered that when the amount of hydrogen peroxide and ozone generated is large, the amount of OH radicals generated is also large. By quantitatively analyzing hydrogen peroxide and ozone, the amount of OH radicals generated can be roughly estimated.

式（１）の水の電気分解の陽極反応でＯＨラジカルが発生し得るが、式（２）のように過酸化水素およびオゾンの共存下では促進酸化が進行してＯＨラジカルが速やかに生成し得、また、式（３）のように過酸化水素の電気分解の陰極反応（還元反応）も起こり得るであろう。 In addition, it is not always clear what reaction the OH radical (OH.) Is actually generated, and it may be generated by any reaction. For example, (1) when generated by an anodic reaction of water electrolysis (same as formula No. 1-1 in Table 1 above), (2) when generated from hydrogen peroxide and ozone, (3) peroxidation The case where it generate | occur | produces by the cathode reaction of the electrolysis of hydrogen can be considered (it shows below as Formula (1)-(3), respectively).

Although OH radicals can be generated by the anodic reaction of water electrolysis in formula (1), accelerated oxidation proceeds in the presence of hydrogen peroxide and ozone as shown in formula (2), and OH radicals are rapidly generated. In addition, the cathodic reaction (reduction reaction) of the electrolysis of hydrogen peroxide may occur as shown in the formula (3).

  OH radicals have higher oxidizing power than hydrogen peroxide and ozone, and can oxidize other substances indiscriminately. This is because the standard oxidation-reduction potential of OH radical generation reaction from water (formula No. 1-1 in Table 1) is equivalent to the hydrogen peroxide generation reaction from water (formula No. 1-4 in Table 1). It can also be understood from the fact that it is higher than the standard redox potential of ozone generation reaction from water (in Table 1, formulas No. 1-3 and 1-5). Therefore, when OH radicals are generated by electrolysis, the C—C bond and C—F bond of the fluorine-containing organic compound can be cleaved. Conventionally, the C—F bond is stronger than the C—C bond and cannot be cleaved. However, according to the present embodiment, the C—F bond can also be cleaved. Although the present invention is not bound by any theory, the OH radical originally has an energy higher than the binding energy of the C—F bond, and by generating a large amount of the OH radical as in the present embodiment, the C—F is obtained. It is inferred that the bond can be broken.

  Also, OH radicals have a very short lifetime (typically 1 μM and a lifetime of about 0.2 ms. For example, when generated by the anodic reaction of water electrolysis of formula (1), it can only exist near the anode surface. ) However, OH radicals decompose fluorine-containing organic compounds (and other components that may exist) to generate radical species, and the radical species react with water or the like to generate OH radicals (or new radical species). It is understood that it is possible to move into the liquid by a chain reaction.

  As described above, the fluorine-containing organic compound is decomposed by the electrolysis treatment. In addition, when an organic compound having a C—C bond and / or a C—F bond other than the fluorine-containing organic compound is present in the liquid, it is considered that these are similarly decomposed.

  According to the present embodiment, it is not necessary to use hydrogen peroxide water or ozone water, or to use chlorine or a chlorine-based oxidant. The compound can be decomposed efficiently. The disassembling method of this embodiment can be carried out in a relatively short processing time and with a processing apparatus that is smaller than conventional ones.

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

Example 1
A schematic diagram of the electrolyzer used is shown in FIG. For the anode electrode 2 and the cathode electrode 5, a boron-doped diamond electrode (manufactured by Sumitomo Electric Hardmetal Co., Ltd., a boron-doped diamond film formed on a silicon substrate with a film thickness of 10 to 50 μm by a CVD method) is used. In both cases, the dimensions were 5 × 1 m ² , the electrode surface area (the film formation area of boron-doped diamond) was defined as 10 cm ² , and the distance between both electrodes was maintained at 1 cm using the PTFE spacer 3. In addition, a potentiostat (manufactured by Hokuto Denko) was used as an external power source (power supply source) 1, and a PTFE stirrer 4 was used for stirring the liquid material.
Liquid substances to be subjected to electrolysis treatment include perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHA), 2,3,3,3-tetrafluoro-2- [1,1,2, 300 ml of pure water. , 3,3,3-hexafluoro-2- (trifluoromethoxy) propoxy] -propanoic acid (hereinafter simply referred to as “PA”) was used. These PFOA, PFHA, and PA can be used as emulsifiers, and the amount of these added was PFOA 370 mg, PFHA 300 mg, and PA 400 mg.

The experimental condition was constant at a current value of 800 mA. Therefore, the current density was determined to be 80 mA / cm ² from this current value and the electrode area. The liquid temperature was 25 ° C. (left at room temperature without temperature control) and the electrolysis time was 30 minutes.

  When the cell voltage (voltage between the anode electrode and the cathode electrode during the electrolysis treatment) was measured during the electrolysis treatment, it was about 40 V (average measured value).

  Moreover, the emulsifier (PFOA, PFHA, PA) density | concentration in a liquid substance was measured on HPLC under the following conditions before and behind the electrolysis process. The results are shown in Table 2.

HPLC measurement conditions Column: ODS-120T (4.6φ × 250 mm, manufactured by Tosoh Corporation)
Developing solution: acetonitrile / 0.6 mass% perchloric acid aqueous solution = 1/1 (vol / vol%)
Sample volume: 20 μL
Flow rate: 1.0 ml / min Detection wavelength: UV 210 nm
Column temperature: 40 ° C
In calculating the PFOA concentration, a calibration curve obtained by HPLC measurement of a PFOA aqueous solution having a known concentration under the above eluate and conditions was used.

  In this example, the decomposition amount of the emulsifier (PFOA + PFHA + PA) per unit electricity consumption was determined by calculating the decomposition amount from the temperature difference before and after the treatment, and dividing by the amount of electricity consumed (Wh) at 30 minutes. 0.7 mg / Wh.

(Example 2)
In addition to emulsifiers (PFOA, PFHA, PA) as pure liquid, sodium sulfate (Na ₂ SO ₄ ) was added as a supporting electrolyte to 5 wt% (based on the liquid substance) as a liquid substance to be subjected to electrolysis treatment. The sample was subjected to electrolysis under the same conditions as in Example 1 except that those were used. (Also in this example, the current value was set to 800 mA, and the current density was set to 80 mA / cm ^2. )

  In this example, the cell voltage (the voltage between the anode electrode and the cathode electrode during the electrolysis process) during the electrolysis process was measured and found to be about 10 V (average measurement value).

  Further, the emulsifier (PFOA, PFHA, PA) concentration in the liquid was measured in the same manner as in Example 1 before and after the electrolysis treatment. The results are shown in Table 3.

  In this example, the decomposition amount of the emulsifier (PFOA + PFHA + PA) per unit electricity consumption was determined in the same manner as in Example 1, and was found to be 71.9 mg / Wh.

  INDUSTRIAL APPLICABILITY The method of the present invention can be used for decomposing PFOA, PFOS, etc., which can efficiently decompose fluorine-containing organic compounds by simple treatment and have been pointed out that they are difficult to decompose and accumulate in the body. It is. In particular, according to the method of the present invention, waste water that may be generated by fluoropolymer polymerization or subsequent processes can be treated efficiently and easily, and work safety can be improved and the burden on the environment can be reduced.

1 Power supply 2 Anode electrode 3 Spacer 4 Stirrer 5 Cathode electrode

Claims (5)

Electrolytic treatment of a liquid material containing a fluorine-containing organic compound in an aqueous medium at an electric current density of 0.1 to 200 A / dm ² using an oxygen overvoltage and chemically stable electrode as an anode. The method of decomposing | disassembling a fluorine-containing organic compound by this.   The method according to claim 1, wherein in the electrolysis treatment, OH radicals, hydrogen peroxide and ozone are generated, and the fluorine-containing organic compound is decomposed due to these.   The method according to claim 1 or 2, wherein the decomposition of the fluorinated organic compound comprises breaking a C-F bond in the fluorinated organic compound.   The method according to claim 1, wherein the electrode having an oxygen overvoltage and chemically stable comprises a material having a conductive diamond structure. Fluorine-containing organic compounds
The following general formula (I):

(In the formula, Y represents H or F. x1 represents an integer of 4 or more, y1 represents an integer of 0 to _3. A represents —SO ₃ M or —COOM, and M represents H, NH ₄ , A compound represented by Li, Na, Mg, Al, K or Ca), and the following general formula (II):

(Wherein, x2 is an integer of 1 or more, y2 .X represents an integer of 0 is .A showing the F or CF ₃ shows a -SO ₃ M 'or -COOM', M 'is H , NH ₄ , Li, Na, Mg, Al, K or Ca.), which is at least one fluorine-containing organic acid compound selected from the group consisting of compounds represented by: The method of crab.

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