WO2025169811A1 - Method for recovering organic fluorine compound - Google Patents

Abstract

The present invention addresses the problem of how to effectively and efficiently extract, separate, and recover high-concentration PFAS contained in water regardless of the type of PFAS. An organic fluorine compound is converted to a chemical species having a negative charge on the basis of ionization by acid dissociation of the organic fluorine compound, molecularization of protonation-type hydrophobic cations, or both of these items, the distribution of the organic fluorine compound to an aqueous phase is promoted, and the organic fluorine compound is recovered.

Description

Method for recovering organic fluorine compounds

The present invention relates to a method for recovering organic fluorine compounds, in which the pH of the aqueous phase is changed during solvent extraction to extract the organic fluorine compounds from the aqueous phase into the organic phase (forward extraction), and then the organic fluorine compounds are back-extracted from the organic phase into the aqueous phase to recover the organic fluorine compounds in the aqueous phase.

A group of organic fluorine compounds known as PFAS (perfluoroalkyl compounds) possess excellent chemical properties, including heat resistance, chemical resistance, light resistance, biodegradability, water and oil repellency, and insulating properties. They are used in many industrial fields, including textiles and clothing, cookware, semiconductors, medicine, automobiles, home appliances, construction, aviation, and food, as surfactants, emulsifiers, fire extinguishing agents, coating agents, antifouling agents, food packaging agents, etching agents, photoresists, anti-reflective agents, refrigerants, lubricants, and lithium-ion battery separator materials.

On the other hand, PFAS are substances that are persistent and easily accumulate in living organisms, traveling long distances without breaking down in the environment. There are concerns about the various health effects of some PFAS, including carcinogenicity, reproductive toxicity, thyroid hormone disruption, liver dysfunction, and effects on the immune system and blood cholesterol levels. Of these, the most widely used PFAS, PFOS (perfluorooctanesulfonic acid) and PFOA (perfluorooctanoic acid), both of which have eight carbon atoms, are already banned or restricted in use internationally.

Technologies have been developed to remove PFAS, primarily through adsorption, from raw water at water sources, river water, tap water, etc. Activated carbon is often used as the adsorbent (see, for example, Patent Document 1), but desorbing PFAS from activated carbon is difficult. Therefore, a method has been proposed in which PFAS is removed using an alcohol-containing solution and a base-containing solution to regenerate activated carbon (Patent Document 2).

In addition to activated carbon, methods that use polymers as adsorbents (for example, Patent Documents 3 and 4), methods that use metal-organic frameworks (Patent Document 5), and methods that use metal inorganic compounds, etc. (Patent Document 6) have also been proposed.

In addition to methods using adsorbents, methods that have been proposed include methods using ion exchange resins (anion exchangers) (Patent Document 7), methods using membranes or membrane-like filters (Patent Document 8), methods using microgels (Patent Document 9), and methods using aquatic algae (Patent Document 10).

However, while conventional methods such as the adsorption mentioned above are suitable for removing low concentrations of PFAS, they are not suitable for quickly and effectively treating wastewater containing high concentrations of PFAS. When it is necessary to quickly and effectively treat high concentrations of target substances in wet separation, liquid-liquid extraction (also known as solvent extraction) is generally chosen. In solvent extraction, the target substance dissolved in water is extracted into a solvent that is immiscible with water (a solvent that forms a two-liquid phase system with water).

Adsorption and absorption onto solids such as adsorbents and ion exchange resins have a smaller recovery and removal capacity and are less rapid than extraction into a liquid (solvent extraction). The same is true for membrane separation. Furthermore, when the target substance is in high concentration, adsorbents and membranes can be reused far less frequently than the extractants used in solvent extraction, resulting in high consumable costs.

However, solvent extraction places a heavy burden on the environment due to the contamination of wastewater with oil, and is therefore rarely used for wastewater treatment. Furthermore, PFAS, which are highly polar, are difficult to extract with saturated hydrocarbons (alkanes such as octane and hexane), which are non-polar, chemically inert, and have little biological impact; therefore, the solvents (extraction solvents) chosen for solvent extraction are often harmful solvents such as ethyl acetate and toluene. In fact, while solvent extraction is sometimes used for pretreatment aimed at rapid PFAS analysis, there are no known examples of it being used to purify PFAS-containing wastewater (recover and remove PFAS). In other words, the use of solvent extraction for PFAS is currently limited to analytical applications.

Japanese Patent Application Laid-Open No. 2022-93398 Special Publication No. 2022-526919 JP 2011-25102 A JP 2012-101159 A Japanese Patent Application Laid-Open No. 2021-137805 Special Publication No. 2022-526606 Special table 2019-511363 publication Special Publication No. 2023-521446 Japanese Patent Application Laid-Open No. 2014-231056 JP 2009-22887 A

Compared to adsorption/absorption onto solids (such as adsorbents or ion exchange resins) or membrane separation, solvent extraction has a significantly larger capacity for recovering and removing PFAS and enables rapid processing. Furthermore, the extractants used in solvent extraction can be reused far more frequently than adsorbents or membranes, resulting in lower consumable costs. On the other hand, solvent extraction poses a significant environmental burden, such as polluting the aquatic environment due to the inclusion of oil in the wastewater. Therefore, the use of solvent extraction for PFAS is currently limited to analytical applications, rather than wastewater purification. Furthermore, saturated hydrocarbons, which have little biological impact, are considered unsuitable as extraction solvents for PFAS, so harmful solvents such as ethyl acetate and toluene are often chosen as extraction solvents. Furthermore, distillation, which requires a high energy load, has traditionally been used to recover PFAS from extraction solvents.

The inventors conducted extensive research to solve the above problems by taking advantage of the advantages of solvent extraction (large capacity for PFAS, rapid processing, low consumable costs). As a result, they discovered that even when using saturated hydrocarbons as the extraction solvent, PFAS can be effectively and efficiently extracted (forward extracted) from the aqueous phase into the organic phase (extraction solvent phase) by lowering the pH of the PFAS-containing aqueous solution (aqueous phase) and converting PFAS into an electrically neutral chemical species (molecule or ion pair). Saturated hydrocarbons that can be used are chain-chain, cyclic, or contain both. Note that chain-chain here includes both straight-chain and branched-chain.

Conversely, they also discovered that by increasing the pH of the PFAS-containing aqueous solution and converting PFAS into an electrically negative (negatively charged) chemical species (dissociated anion), PFAS can be effectively and efficiently stripped from the organic phase into the aqueous phase. This discovery eliminates the need for the conventional energy-intensive distillation method.

The method for recovering organic fluorine compounds according to the present invention is characterized in that, for example, in a two-liquid phase system consisting of an aqueous phase, which is an aqueous solution containing organic fluorine compounds, and an organic phase, the pH of the aqueous phase is lowered to convert the organic fluorine compounds to electrically neutral chemical species, the organic fluorine compounds are solvent-extracted from the aqueous phase into the organic phase, and then the organic phase from which the organic fluorine compounds have been extracted is contacted with an aqueous phase whose pH is higher than the pH at which the organic fluorine compounds were solvent-extracted from the aqueous phase into the organic phase, converting the organic fluorine compounds solvent-extracted into the organic phase into electrically negative chemical species, and the organic fluorine compounds are stripped back into the aqueous phase.

Furthermore, by using an emulsion flow system, such as that shown in Figure 6 of JP 2023-142775 A, as a solvent extraction system (apparatus), it is possible to significantly reduce or eliminate the environmental impact of solvent extraction. In emulsion flow, there are simultaneously two regions: one where the aqueous and organic phases are mixed to an emulsion state (known as an emulsion) and another where the two phases are separated into a clear phase. Therefore, unlike mixer-settler systems (typical of industrial solvent extraction), there is no need to wait for phase separation due to gravity, and no settling section (settler section) is required. Because phase separation occurs from the start without waiting for settling, no oil is mixed into the wastewater. While solvent extraction is considered an environmentally unfriendly method that pollutes the aquatic environment due to the oil contamination of wastewater, emulsion flow is, on the other hand, extremely effective as a system for effectively and efficiently purifying oil-contaminated wastewater.

In the present invention, PFAS can be extracted into an organic phase under specific pH conditions, and then the organic phase is brought into contact with an aqueous phase having a pH higher than the pH conditions, thereby recovering the PFAS in the aqueous phase. Furthermore, by controlling the amount or flow rate (flow rate) of the aqueous phase relative to the organic phase, the PFAS can be concentrated in the aqueous phase and recovered.

More specifically, the method of the present invention makes it possible to effectively and efficiently recover high concentrations of PFAS contained in water, regardless of the type of PFAS. Note that "high concentration" here refers to a concentration that is difficult to achieve in terms of efficiency and cost using conventional methods such as adsorption, in terms of PFAS capacity, speed of treatment, and reusability of consumables. Furthermore, the type of PFAS envisioned is one that has a carboxyl group, a sulfonic acid group, or both.

The present invention will be explained in more detail below. Details will be given for each of the following cases: when carboxylic acid-based PFAS is to be recovered; when sulfonic acid-based PFAS is to be recovered; when PFAS having both carboxyl groups and sulfonic acid groups is to be recovered; when PFAS having multiple carboxyl groups is to be recovered; when PFAS having multiple sulfonic acid groups is to be recovered; and when a mixture of carboxylic acid-based PFAS and sulfonic acid-based PFAS is to be recovered.

If the PFAS to be recovered is a carboxylic acid, the PFAS can be extracted (forward extraction) and back-extracted based on the following chemical reaction formula.

Here, F- ^Org- represents the dissociated anion of PFAS, F-Org-H represents the associated molecule of PFAS, the subscript (aq) represents the aqueous phase, and the subscript (org) represents the organic phase.

Carboxylic acid PFAS exist as dissociated anions when the pH is high (hydrogen ion concentration is low), but as the pH decreases (hydrogen ion concentration increases), they associate with hydrogen ions and change into molecules (associated molecules). Electrically neutral, bulky associated molecules are more likely to distribute into the organic phase than into the aqueous phase, so lowering the pH promotes the extraction of carboxylic acid PFAS into the organic phase (forward extraction). Conversely, as the pH increases (hydrogen ion concentration decreases), the associated molecules change into the form of dissociated anions that have released hydrogen ions. Negatively charged dissociated anions are more likely to distribute into the aqueous phase than into the organic phase, so increasing the pH promotes the back-extraction of carboxylic acid PFAS from the organic phase into the aqueous phase.

That is, by adding an acid to an aqueous solution containing carboxylic acid-based PFAS (for example, industrial wastewater), the pH can be lowered and the PFAS can be extracted into a saturated hydrocarbon phase (organic phase), and the PFAS can then be stripped from the organic phase using water or a dilute alkaline aqueous solution. Furthermore, because the amount of acid added to molecularize the carboxylic acid-based PFAS is not large, this method is thought to be more economical and produce less carbon dioxide (reducing the environmental burden) than methods that involve evaporating (distilling or refluxing) the saturated hydrocarbon solvent to recover the carboxylic acid-based PFAS.

When the PFAS to be recovered is sulfonic acid-based, the presence of protonated cations in the organic phase allows for ion-pair extraction of the sulfonic acid-based PFAS, which exists in the form of dissociated anions. Furthermore, if the protonation of the protonated cations is eliminated and they return to molecules, ion-pair extraction does not occur and the dissociated anions are back-extracted. Protonated cations are, in a broad sense, extractants for sulfonic acid-based PFAS.

Examples of substances that are prone to protonation include, but are not limited to, amines. Essentially, any Bronsted base (a molecule that acts as a hydrogen ion acceptor) can be used. More specifically, amines can be aliphatic amines, aromatic amines, heterocyclic amines, or mixtures thereof. The non-amine backbone structure of these amines is optional.

Sulfonic acid-based PFAS are extracted (forward extraction) and back-extracted based on the following chemical reaction formula:

Here, N-Org is a Bronsted base, such as amines. N-Org becomes a protonation-type hydrophobic cation (N-Org-H ⁺ ) as the hydrogen ion concentration increases, and returns to a deprotonated molecule (N-Org) as the hydrogen ion concentration decreases. Sulfonic acid-based PFAS exists as a dissociated anion (F-Org ^- ) even under conditions of high hydrogen ion concentration, and the protonation-type hydrophobic cation (N-Org-H ⁺ ) acts as a counter ion, forming an electrically neutral ion pair (F-Org ^- N-Org-H ⁺ ).

Furthermore, by selecting a substance that is as prone to protonation as possible (a substance that protonates even at low hydrogen ion concentrations), the amount of acid added to extract the dissociated anions of sulfonic acid-based PFAS as ion pairs can be reduced.

Furthermore, if you want to extract and separate sulfonic acid-based PFAS under low acid concentration conditions, you can use compounds that are prone to protonation, and if you want to extract and separate under high acid concentration conditions, you can use compounds that are difficult to protonate.

Since electrically neutral and bulky ion pairs are more likely to distribute into the organic phase than into the aqueous phase, lowering the pH promotes the extraction of sulfonic acid-based PFAS into the organic phase (forward extraction). Conversely, as the pH increases (hydrogen ion concentration decreases), protonation-type hydrophobic cations become molecular, the ion pairs are dissolved, and dissociated anions are liberated. Since negatively charged dissociated anions are more likely to distribute into the aqueous phase than into the organic phase, increasing the pH promotes the back-extraction of sulfonic acid-based PFAS from the organic phase into the aqueous phase.

PFAS containing both carboxyl and sulfonic acid groups can also be recovered using a similar method by controlling the extraction (forward extraction) and back-extraction by changing the pH. Taking PFAS containing one carboxyl group and one sulfonic acid group as an example, the chemical reaction formula can be shown as follows:

Here, F-Org ^2- is the dissociated anion formed when both the carboxyl group and the sulfonic acid group release hydrogen ions. Furthermore, F-Org-H ^- and N-Org-H ⁺ represent an ion pair consisting of an anion and a protonation cation, in which a carboxyl group that has accepted a hydrogen ion coexists with a sulfonic acid group that has retained its dissociated hydrogen ion.

The electrically neutral and bulky ion pair (F-Org-H ^- N-Org-H ⁺ ) is more likely to partition into the organic phase than into the aqueous phase, and the free dissociated anion (F-Org ^2- ) is more likely to partition into the aqueous phase than into the organic phase. Therefore, the extraction (forward extraction) and back-extraction of PFAS, which has both carboxyl and sulfonic acid groups, can also be controlled by changing the pH.

PFAS with multiple carboxyl groups can also be recovered using a similar method. Taking PFAS with two carboxyl groups as an example, the chemical reaction formula can be shown as follows:

Here, F-Org ^2- is the dissociated anion formed when both carboxyl groups release hydrogen ions, and F-Org-H ₂ is the molecule formed when both carboxyl groups accept hydrogen ions.

PFAS with multiple sulfonic acid groups can also be recovered using a similar method. Taking PFAS with two sulfonic acid groups as an example, the chemical reaction formula can be shown as follows:

Here, F-Org ^2- is the dissociated anion formed when both sulfonic acid groups release hydrogen ions, and F-Org ^2- .(N-Org-H ⁺ ) ₂ is the electrically neutral ion pair formed when the dissociated anion associates with two protonation cations.

The present invention can also be used as a method for separating and selectively recovering multiple PFAS. For example, it is possible to highly selectively recover carboxylic acid PFAS and sulfonic acid PFAS. First, the carboxylic acid PFAS is recovered using an organic phase (which can be a single solvent or a mixed solvent) that does not contain protonation cations or their unprotonated molecules, and then the sulfonic acid PFAS is recovered using an organic phase that contains protonation cations or their unprotonated molecules.

Furthermore, when multiple carboxylic acid-based PFAS are contained, it is possible to selectively recover each one by changing the pH. This is because the acid strength (pKa value) differs depending on factors such as chain length. Furthermore, the size and shape of the associated molecules and the strength of hydration also affect the ease of distribution into the organic phase. The latter also applies when multiple sulfonic acid-based PFAS are contained.

The above describes the embodiments of the present invention, showing several examples of PFAS types and combinations. However, the system used in these applications is preferably not a conventional industrial solvent extraction system, such as a mixer-settler, but rather an emulsion flow system, which is simple and highly efficient while preventing oil from being mixed into the wastewater. This significantly reduces or eliminates the environmental impact of conventional solvent extraction.

Next, examples of the present invention will be shown, but the present invention is not limited to these examples.

Example 1 (Batch Distribution Test of Carboxylic Acid-Based PFAS)
Perfluorooctanoic acid (PFOA) was selected as a carboxylic acid-based PFAS, and a batch test was conducted in a test tube to examine the distribution of PFOA between two liquid phases. A sulfuric acid aqueous solution containing PFOA at a concentration of 169 mg/L and a pH of 1.01 was prepared, and this was placed in a centrifuge tube (polypropylene, 50 mL) together with the same volume of dodecane, and then shaken for 10 minutes using a vertical shaker. The solution was then centrifuged at 3,000 rpm for 5 minutes using a centrifuge. After centrifugation, the aqueous phase (sulfuric acid aqueous solution) was collected, and the PFOA concentration was measured, resulting in a value of 14 mg/L. The pH remained unchanged.

From these results, it can be seen that of the 169 mg/L of PFOA, 155 mg/L was distributed to the organic phase, so the extraction rate of PFOA into dodecane in the batch test was calculated to be 91.7%.

Example 2 (Partition test of carboxylic acid-based PFAS in emulsion flow)
A continuous flow test was conducted to examine the distribution of PFOA between two liquid phases using a benchtop (1 L container) single-stage mechanically stirred emulsion flow apparatus. The same aqueous phase (aqueous sulfuric acid solution containing PFOA at 169 mg/L and pH 1.01) and organic phase (dodecane) were used as in the batch test. The flow rates of the aqueous and organic phases were the same, and the reaction time was set to 10 minutes. As a result, the concentration of PFOA in the discharged aqueous phase was 15 mg/L.

In other words, of the 169 mg/L of PFOA, 154 mg/L was distributed to the organic phase, so the extraction rate of PFOA into dodecane in the emulsion flow test was calculated to be 91.1%.

In the emulsion flow test, back-extraction using a dilute alkaline aqueous solution was also investigated. In this experiment, a dilute aqueous sodium hydroxide solution was used as the aqueous phase for back-extraction, in contrast to the organic phase (containing 154 mg/L of PFOA) used in the direct extraction experiment. The flow rates of the aqueous and organic phases were the same, and the reaction time was set to 10 minutes. As a result, the concentration of PFOA in the discharged aqueous phase was 148 mg/L.

From these results, it can be seen that of the 154 mg/L of PFOA in the organic phase, 148 mg/L was back-extracted into the dilute alkaline aqueous solution, so the back-extraction rate of PFOA into the dilute alkaline aqueous solution in the emulsion flow test was calculated to be 96.1%.

The results of the above batch tests and emulsion flow tests were obtained using a single operation or a single-stage (single-stage) device, and it is easy to imagine that the desired extraction and back-extraction rates can be obtained by using multiple operations or a multi-stage device.

Example 3 (Batch distribution test of sulfonic acid-based PFAS)
Perfluorooctane sulfonic acid (PFOS) was selected as the sulfonic acid-based PFAS, and an alkyldiamidoamine with five ethylhexyl groups was selected as an amine, a substance that is prone to protonation. A test tube batch test was conducted to examine the partitioning of PFOS between two liquid phases. A hydrochloric acid solution containing PFOS at a concentration of 3000 mg/L and a pH of 1.00 was prepared. This solution was then placed in a centrifuge tube (polypropylene, 50 mL) along with an equal volume of a dodecane solution containing the alkyldiamidoamine at a concentration of 0.05 mol/L. The tube was then shaken for 10 minutes using a vertical shaker. The tube was then centrifuged at 3000 rpm for 5 minutes. After centrifugation, the aqueous phase (hydrochloric acid solution) was collected and the PFOS concentration was measured, resulting in a value of 240 mg/L. The pH remained unchanged.

From these results, it was determined that 2760 mg/L of the 3000 mg/L of PFOS was distributed to the organic phase, and the extraction rate of PFOS into the dodecane solution in the batch test was calculated to be 92.0%.

Batch tests were also conducted to investigate the stripping of PFOS using a dilute alkaline aqueous solution. A dilute aqueous sodium hydroxide solution was used as the aqueous phase for stripping, in contrast to the organic phase used in the forward extraction experiment (containing 2760 mg/L of PFOS). In the batch stripping test, as in the forward extraction, equal volumes of the aqueous and organic phases were placed in a centrifuge tube, shaken for 10 minutes using a vertical shaker, and then centrifuged for 5 minutes at 3000 rpm using a centrifuge. After centrifugation, the aqueous phase (dilute aqueous sodium hydroxide solution) was collected and the PFOS concentration was measured, resulting in a concentration of 2620 mg/L.

From these results, it can be seen that of the 2760 mg/L of PFOS in the organic phase, 2620 mg/L was back-extracted into the dilute alkaline aqueous solution, so the back-extraction rate of PFOS into the dilute alkaline aqueous solution in the batch test was calculated to be 94.9%.

The present invention relates to a method for effectively and efficiently separating, recovering, extracting, and isolating organofluorine compounds having carboxyl groups, sulfonic acid groups, or both, from industrial wastewater and other wastewater containing high concentrations of such compounds. "High concentrations" here refer to concentrations that are difficult to achieve in terms of efficiency and cost using conventional methods such as adsorption, ion exchange, and membrane separation, in terms of the capacity for organofluorine compounds, speed of treatment, and reusability of consumables.

These organic fluorine compounds are widely used in various industries, but their significant impact on health and ecosystems has raised concerns. While organic fluorine compounds are persistent and some are toxic, they remain stable in the environment for long periods and tend to disperse over long distances. Therefore, in recent years, there has been a rapid, global trend to gradually restrict or phase out their use unless they are proven to be socially essential. Meanwhile, in many cases, alternatives are difficult to find for industrial or consumer use. For so-called essential uses, even if their use is not abolished, strict restrictions are imposed on factory emissions. This means that technology capable of handling aqueous solutions containing high concentrations of organic fluorine compounds, such as industrial wastewater, is essential. Furthermore, not only from the perspective of health and ecosystem impacts, but also from the perspectives of resource circulation and carbon dioxide reduction, consideration must be given to recycling organic fluorine compounds for essential uses in a completely closed system without discharge. The present invention addresses these urgent industrial needs.

Claims (10)

In a two-liquid phase system consisting of an aqueous phase, which is an aqueous solution containing an organic fluorine compound, and an organic phase, the pH of the aqueous phase is reduced to convert the organic fluorine compound into an electrically neutral chemical species, and the organic fluorine compound is extracted from the aqueous phase into the organic phase with a solvent;
and then contacting the organic phase from which the organic fluorine compounds have been extracted with an aqueous phase having a pH higher than that at which the organic fluorine compounds were solvent-extracted from the aqueous phase into the organic phase, thereby converting the organic fluorine compounds solvent-extracted into the organic phase into electronegative chemical species, and stripping the organic fluorine compounds into the aqueous phase. The method for recovering organic fluorine compounds according to claim 1, characterized in that the amount or flow rate of the aqueous phase relative to the organic phase is controlled to concentrate the organic fluorine compounds in the aqueous phase and recover them. A method for recovering organic fluorine compounds according to claim 1 or 2, characterized in that an organic phase containing no protonation-type hydrophobic cations is used to selectively extract and separate organic fluorine compounds whose charge is easily changed by pH, and then the organic phase containing the protonation-type hydrophobic cations is used to selectively recover organic fluorine compounds whose charge is not easily changed by pH. A method for recovering organic fluorine compounds according to any one of claims 1 to 3, wherein the recovery of the organic fluorine compounds is carried out using an emulsion flow mechanism. A method for recovering an organic fluorine compound according to any one of claims 1 to 3, wherein the organic fluorine compound has a carboxyl group, a sulfonic acid group, or both. A method for recovering organic fluorine compounds, characterized in that in a two-liquid-phase system consisting of an aqueous phase, which is an aqueous solution containing organic fluorine compounds, and an organic phase, the pH of the aqueous phase is lowered to convert the organic fluorine compounds to electrically neutral chemical species based on either acid molecularization of the organic fluorine compounds or ion pair formation with protonation-type hydrophobic cations, or both, thereby promoting partitioning of the organic fluorine compounds into the organic phase, thereby directly extracting the organic fluorine compounds into the organic phase; then, by contacting the organic phase with an aqueous phase whose pH is higher than that used to promote partitioning into the organic phase, the organic fluorine compounds are converted to negatively charged chemical species based on either ionization due to acid dissociation of the organic fluorine compounds or molecularization of the protonation-type hydrophobic cations, or both, thereby promoting partitioning of the organic fluorine compounds into the aqueous phase, thereby back-extracting and recovering the organic fluorine compounds from the organic phase into the aqueous phase. The method for recovering organic fluorine compounds according to claim 6, characterized in that the amount or flow rate of the aqueous phase relative to the organic phase is controlled to concentrate the organic fluorine compounds in the aqueous phase and recover them. A method for recovering organic fluorine compounds according to claim 6 or 7, characterized in that an organic phase containing no protonation-type hydrophobic cations is used to selectively extract and separate organic fluorine compounds whose charge is easily changed by pH, and then the organic phase containing the protonation-type hydrophobic cations is used to selectively recover organic fluorine compounds whose charge is not easily changed by pH. A method for recovering organic fluorine compounds according to any one of claims 6 to 8, wherein the recovery of the organic fluorine compounds is carried out using an emulsion flow mechanism. A method for recovering an organic fluorine compound according to any one of claims 6 to 8, wherein the organic fluorine compound has a carboxyl group, a sulfonic acid group, or both.