AU2017320329B2 - Method, composition and system for degrading a fluorinated organic compound - Google Patents

Abstract

Methods for degrading a fluorinated organic compound are described. A first method comprises the steps of: introducing at least one chemical oxidant into a medium comprising a fluorinated organic compound, the chemical oxidant being effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period, and oxidizing the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or one or more fluoride ions. According to a second method, the medium is an electrolyte medium, and a first of two electrodes introduced into said medium comprises the chemical oxidant that when polarised, as a result of applying a voltage between the two electrodes, produces one or more radical species effective for activating degradation of the fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period, which then oxidize the fluorinated organic compound to generate one or more fragments and/or one or more fluoride ions.

Description

METHOD, COMPOSITION AND SYSTEM FOR DEGRADING A FLUORINATED

ORGANIC COMPOUND

Field of the Invention

[0001 ] The present invention relates to a method, composition and system for degrading a fluorinated organic compound.

[0002] The invention has been developed primarily for use in degrading fluorinated organic compounds, and in particular, for use in degrading perfluorinated organic compounds found in aqueous film-forming foams (AFFFs) and will be described hereinafter with reference to this application.

[0003] The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge in Australia or any other country as at the priority date of any one of the claims of this specification.

Background of the Invention

[0004] Fluorinated organic compounds belong to a diverse family of organic compounds that comprise at least one carbon-fluorine (C-F) bond in their skeleton. As such, fluorinated organic compounds include compounds that are either partially or fully fluorinated. Fluorinated organic compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants and reagents in catalysis.

[0005] The carbon-fluorine bond is one of the strongest in organic chemistry, and is one of the reasons why fluorinated organic compounds have high thermal and chemical stability. It is partly because of the inertness associated with the strong C-F bond that some fluorinated organic compounds are considered as pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity.

[0006] A particular class of fluorinated organic compound of concern is the fluorinated surfactants or fluorosurfactants. Fluorosurfactants have properties that make them well suited to fire-fighting applications. For example, the anionic fluorosurfactants, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been used as aqueous film-forming foams (AFFFs) to suppress liquid fuel fires since the 1960s. However, these fluorosurfactants have been found to be particularly stubborn organic pollutants, where trace contaminations have been detected in human blood serum and the liver, as well as in ground water, soils, sediments, air, and biota samples. Indeed, these perfluorinated organic compounds have been found to be globally distributed, persistent and bioaccumulative.

[0007] The fluoro-carbon skeleton associated with fluorinated organic compounds, and in particular, the fully fluorinated or perfluorinated organic compounds such as PFOS and PFOA, is inert and resistant to biodegradation under natural environmental conditions on account of the particularly strong C-F bond (CF₃-CF₃ of 99 kcal/mol vs. CH3-CH3 of 89 kcal/mol), which has led to their global accumulation and distribution in the environment. This has in turn raised serious concerns about their impact on the environment and public health. Due to serious misgivings about their biological and environmental impact and their persistence in nature, both PFOS and PFOA were phased out in the early 2000s in favour of the fluorotelomer-based surfactants, such as 1 H, 1 H, 2H, 2H-perfluorooctanesulfonic acid-based surfactants (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid-based surfactants (8:2FTS).

[0008] Fluorotelomers are a family of fluorinated oligomers synthesised via telomerisation. These oligomers have linear structures that differ from the products of electrochemical fluorination, such as PFOS, which contain linear and branched isomers. Although fluorotelomers are reported to be environmentally safe, their fluoro-carbon skeletons still raise concerns about their biodegradability in the natural environment. For example, the half-life of 6:2FTS is estimated to be -10 years which, while shorter than the respective half-lives for PFOS (-41 years) and PFOA (-92 years), still falls far short of the biodegradability characteristics desired by many.

[0009] Previous methods used to degrade such perfluorinated organic compounds include the activation of hydrogen peroxide (H₂O₂) via the Fenton process, persulfate oxidisation, advanced electrochemical oxidisation and sonolytic conversion, to name but a few methods. However, many of these methods rely on high concentrations of the oxidant and elevated temperature in order to effect degradation of the perfluorinated organic compounds. Moreover, the degradation of these compounds was still only achieved at relatively long half-lives.

[0010] The present invention seeks to provide a method, composition and system for use in degrading a fluorinated organic compound, and in particular, for use in degrading a perfluorinated organic compounds, which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or to at least provide an alternative. Summary of the Invention

[001 1 ] According to a first aspect of the present invention, there is provided a method for degrading a fluorinated organic compound, the method comprising the steps of:

[0012] a) introducing at least one chemical oxidant into a medium comprising a fluorinated organic compound, the chemical oxidant being effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period; and

[0013] b) oxidizing the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or one or more fluoride ions.

[0014] Preferably, the chemical oxidant is selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7) , lead dioxide (PbO2) and sodium bismuthate (NaBiOa).

[0015] In one embodiment, the chemical oxidant comprises potassium permanganate (KMnO₄).

[0016] Suitably, the predetermined time period is at least 180 days.

[0017] Preferably, the medium is selected from the group consisting of an aqueous liquid, a foam, a sludge, a sediment, bedrock, run-off water, ground water, industrial effluent, process water, waste water, soil and a combination thereof.

[0018] Preferably, the chemical oxidant is used at a concentration that falls within a range of about 0.00001 mmol/l to about 1 mmol/l.

[0019] Preferably, the method further comprises, before step b), the step of introducing a catalyst into the medium, the catalyst being effective for catalysing the degradation of the fluoro-carbon skeleton of the fluorinated organic compound with the chemical oxidant.

[0020] Suitably, the catalyst is selected from the group consisting of an acid catalyst and a photocatalyst.

[0021 ] In one embodiment, the chemical oxidant is 0.1 % KMnO₄ and the acid catalyst is 0.36% HCI (w/w).

[0022] According to a second aspect of the present invention, there is provided a method for degrading a fluorinated organic compound, the method comprising the steps of: [0023] a) introducing first and second electrodes into an electrolyte medium comprising a fluorinated organic compound, the first electrode comprising a chemical oxidant that when polarised, produces one or more radical species effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period; and

[0024] b) applying a voltage between the first electrode and the second electrode to generate said one or more radical species to oxidize the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or one or more fluoride ions.

[0025] In one embodiment, the chemical oxidant is lead dioxide (PbO₂), the electrolyte medium is a 33% (w/w) aqueous solution of sulfuric acid (H₂SO₄), and the second electrode comprises lead (Pb) or at least coating of Pb thereon.

[0026] Preferably, the predetermined time period is at least 1 hour.

[0027] Suitably, the predetermined time period is at least 2 hours.

[0028] Preferably, the voltage applied between the first and second electrodes falls within a range of 1 V to 4 V.

[0029] Preferably, the method further comprises the step of:

[0030] introducing one or more additional chemical oxidants into the electrolyte medium that are effective for activating degradation of the fluoro-carbon skeleton of the fluorinated organic compound.

[0031 ] Preferably, the one or more additional chemical oxidants are selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7) , and sodium bismuthate (NaBiOa).

[0032] Preferably, the fluorinated organic compound is a perfluorinated organic compound.

[0033] In one embodiment, the fluorinated organic compound is a fluorosurfactant.

[0034] Suitably, the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

[0035] Preferably, the fluorinated organic compound is a fluoroteleomer. [0036] Suitably, the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).

[0037] According to a third aspect of the present invention, there is provided a composition for degrading a fluorinated organic compound in a medium, comprising a chemical oxidant being effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period by oxidizing the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or fluoride ions.

[0038] Preferably, the chemical oxidant is selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O₇), lead dioxide (Pb0₂) and sodium bismuthate (NaBi0₃).

[0039] In one embodiment, the chemical oxidant comprises potassium permanganate (KMnO₄).

[0040] In one embodiment, the chemical oxidant is used at a concentration that falls within a range of about 0.00001 mmol/l to about 1 mmol/l.

[0041 ] Preferably, the composition further comprises a catalyst being effective for catalysing the degradation of the fluoro-carbon skeleton of the fluorinated organic compound with the chemical oxidant.

[0042] Suitably, the catalyst is selected from the group consisting of an acid catalyst and a photocatalyst.

[0043] In one embodiment, the chemical oxidant is 0.1 % KMnO₄ and the acid catalyst is 0.36% HCI (w/w).

[0044] Preferably, the medium is selected from the group consisting of an aqueous liquid, a foam, a sludge, a sediment, bedrock, run-off water, ground water, industrial effluent, process water, waste water, soil and a combination thereof.

[0045] Preferably, the fluorinated organic compound is a perfluorinated organic compound.

[0046] In one embodiment, the fluorinated organic compound is a fluorosurfactant.

[0047] Suitably, the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

[0048] Preferably, the fluorinated organic compound is a fluoroteleomer. [0049] Suitably, the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).

[0050] According to a fourth aspect of the present invention, there is provided a system for degrading a fluorinated organic compound, the system comprising:

[0051 ] at least one electrochemical cell including first and second electrodes, and a separator for use in separating said first and second electrodes, the at least one electrochemical cell being configured to receive an electrolyte medium comprising a fluorinated organic compound, into which the first and second electrodes and the separator can at least be partially immersed,

[0052] wherein the first electrode comprises a chemical oxidant that when polarised by applying a voltage between the first electrode and the second electrode, produces said one or more radical species effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period by oxidizing the fluorinated organic compound to generate one or more fragments and/or one or more fluoride ions.

[0053] Preferably, the chemical oxidant is lead dioxide (PbO2).

[0054] Preferably, the system further comprises one or more additional chemical oxidants effective for activating degradation of the fluoro-carbon skeleton of the fluorinated organic compound, wherein the one or more additional chemical oxidants are introduced into the electrolyte medium.

[0055] Preferably, the one or more additional chemical oxidants are selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O₇), and sodium bismuthate (NaBiO₃).

[0056] Preferably, the fluorinated organic compound is a perfluorinated organic compound.

[0057] In one embodiment, the fluorinated organic compound is a fluorosurfactant.

[0058] Suitably, the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

[0059] Preferably, the fluorinated organic compound is a fluoroteleomer. [0060] Suitably, the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).

[0061 ] Other aspects of the invention are also disclosed. Brief Description of the Drawings

[0062] Notwithstanding any other forms which may fall within the scope of the present invention, preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0063] Fig. 1 shows photographic images depicting the oxidisation process when PFOA, PFOS and 6:2FTS are each subjected to oxidisation with 0.1 % KMnO₄ + 0.36% HCI (w/w) for periods of 3 months and 6 months;

[0064] Fig. 2 shows HPLC-MS data showing the breakdown of (a) PFOA, (b) PFOS and (c) 6:2FTS when subjected to oxidisation with 0.1 % KMnO₄ + 0.36% HCI (w/w) for 3 months, and (d) illustrates a comparison of the AFFF concentrations of PFOA, PFOS and 6:2FTS before and after oxidisation for 3 months;

[0065] Fig. 3 shows (a) HPLC-MS data showing the breakdown of PFOA, PFOS and 6:2FTS subjected to oxidisation with 0.1 % KMnO₄ + 0.36% HCI (w/w) for 3 to 6 months, and (b) ion chromatograph data that compares the free concentrations of F^" and SO₄ ^2" before and after oxidisation for 6 months; and

[0066] Fig. 4 shows (a) images (using an astkCARE™anionic surfactant test kit) and (b) ion chromatograph data that reveals the breakdown of PFOA when subjected to oxidisation in an Electrochemical Advanced Oxidisation Process (EAOP) cell equipped with Pb/PbO₂ electrodes in an aqueous 33% H₂SO₄ (w/w) medium for a time period of 4 to10 hours.

[0067] Detailed Description of Specific Embodiments

[0068] It is to be understood that the following description is for the purpose of describing particular embodiments only and is not intended to be limiting with respect to the above description.

[0069] The present invention is predicated on the finding of a method and system involving a chemical oxidant composition for use in activating degradation of a fluoro- carbon skeleton of fluorinated organic compounds, and in particular, fully fluorinated (pe/fluorinated) organic compounds, so as to degrade these fluorinated compounds into one or more fragments and/or fluoride ions, as confirmed by standard analytical techniques such as HPLC-MS and ion chromatography (IC). These previously undisclosed methods demonstrate that perfluorinated organic compounds such as the anionic fluorinated surfactants (fluorosurfactants), perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) and the fluorotelomers-based surfactants, 1 H, 1 H, 2H, 2H-perfluorooctanesulfonic acid (6:2FTS), and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS) employed in aqueous film-forming foams (AFFFs) for use in fire- fighting applications, can be degraded over predetermined periods of time when mixed with a chemical oxidant according to the presently claimed composition. It will be appreciated by persons of ordinary skill in the relevant art that since such perfluorinated organic compounds are generally inert and resistant to biodegradation under natural environmental conditions, the ability to degrade the fluoro-carbon skeleton of these compounds to generate one or more fragments and/or one or more fluoride ions represents a considerable advance over conventional approaches in the ongoing fight to reduce the half-lives of these compounds to limit their impact on the natural environment.

[0070] Preferred embodiments of the present invention will now be described in terms of the fluorosurfactants and fluorotelomers used in exemplary aqueous film- forming foams (AFFFs)); specifically, fluorosurfactants including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), and fluorotelomers, including 1 H, 1 H, 2H, 2H-fluorooctane sulfonic acid (6:2FTS). It will be appreciated by persons skilled in the relevant art however, that the embodiments of the presently claimed invention are not limited to degrading only the above exemplary perfluorinated organic compounds, but that other fluorinated organic compounds may also be degraded in the same manner.

[0071 ] Below is a table (Table 1 ) providing a summary of abbreviations for the various compounds that will be used in the following description of the embodiments of the present invention. [0072] Table 1 : Summary of abbreviations used in the specification

[0073] Sample Preparation

[0074] It will be appreciated that in a practical sense, samples of the perfluorinated organic compounds are likely to exist in various forms depending on the application in which they have been used. For instance, samples containing the perfluorinated organic compounds of AFFFs may include the AFFF foam itself, or where the perfluorinated organic compounds have actually seeped into the natural environment. In this respect, the sample may be an environmentally-derived sample such as a water sample, a sludge, a sediment, bedrock, run-off water, ground water, a soil dilution or the like.

[0075] The sample may also be derived from, for example, industrial sites, sites suspected of surfactant contamination, such as sites where AFFFs have been used, industrial or domestic effluents, process water, waste water, treated water, stormwater, lake water, river water or marine water or sediment samples thereof, among many others.

[0076] In the case where the perfluorinated organic compounds are derived from solids, such contaminated soils may be diluted in water or another aqueous solvent to produce a sample. Furthermore, other solids such as plant material, building material or the like may be crushed or macerated before being diluted into water or another aqueous solvent to produce a sample. [0077] Samples may be extracted into a solvent for assay purposes. In these embodiments, the solvent may be added to the sample which may be solid, semi-solid or liquid. Examples of such samples may include soils, plant material, building material or the like.

[0078] Composition

[0079] A composition for use in degrading perfluorinated organic compounds into one or more fragments and/or fluoride ions will now be described.

[0080] In its simplest form, the composition comprises a chemical oxidant that is effective for activating degradation of a fluoro-carbon skeleton of a perfluorinated organic compound over a predetermined time period. A range of suitable chemical oxidants may be used for the breakdown of perfluorinated organic compounds including, for example, potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7) , lead dioxide (PbO2), and/or sodium bismuthate (NaBiOa), amongst others.

[0081 ] Such chemical oxidants are particularly advantageous on account of their cost-effectiveness, stability, and environmentally safe (MnO₄ ^" and BiO₃ ^2", etc.), as well as being easy to handle.

[0082] The chemical oxidants listed above are typically obtained in powder form and thus, depending on the nature of the perfluorinated organic compound sample to which it will be reacted, it may be necessary to dissolve the chemical oxidant in a suitable solvent medium prior to use.

[0083] In one embodiment, therefore, the chemical oxidant is dissolved in an aqueous liquid such as water to afford a concentration that falls within a range of about 0.00001 mmol/l to about 100 mmol/l.

[0084] In an alternative embodiment, where the perfluorinated organic compound sample is already in the liquid state, the chemical oxidant may simply be added to the perfluorinated organic compound sample in its native powder form.

[0085] The composition further comprises a catalyst being effective for catalysing the degradation of the fluoro-carbon skeleton of the perfluorinated organic compound with the chemical oxidant.

[0086] Suitably, the catalyst is selected from the group consisting of an acid catalyst and a photocatalyst. [0087] As will be apparent from the description of specific examples given below, good results have been observed when the chemical oxidant used is potassium permanganate (KMnO₄) and the catalyst used is the acid catalyst, HCI.

[0088] In a preferred embodiment, and which is described in more detail below, good results have been obtained when the composition comprises 0.1 % KMnO₄ and 0.36% HCI (w/w).

[0089] Method

[0090] A method for use in degrading perfluorinated organic compounds into one or more fragments and/or fluoride ions will now be described.

[0091 ] According to a first step, step a), a chemical oxidant which is effective for activating degradation of a fluoro-carbon skeleton of a perfluorinated organic compound is introduced into a medium comprising the perfluorinated organic compound to be degraded.

[0092] According to a second step, step b), the resultant mixture is then oxidised over a predetermined period of time, and with occasional agitation, to effect degradation of the perfluorinated organic compound into one or more fragments and/or fluoride ions.

[0093] As evidenced by the examples given below, when the predetermined time period is at least 3 months, more preferably, at least 6 months, the fluoro-carbon skeleton of the fluorinated organic compound is unexpectedly degraded.

[0094] As described above, the preferred composition comprises potassium permanganate and the acid catalyst, HCI, dissolved in an aqueous medium to yield an aqueous solution of 0.1 % KMnO₄ and 0.36% HCI (w/w). In this respect, the preferred method comprises, before step b), the step of introducing a catalyst (HCI) into the medium, for use in catalysing the degradation of the fluoro-carbon skeleton of the perfluorinated organic compound with the chemical oxidant (KMnO₄).

[0095] The inventors have found that the degradation process can be accelerated by treating the chemical oxidant/perfluorinated organic compound mixture during the predetermined time period by one or more of heating, sonication, and/or stirring over the duration of the degradation process,

[0096] The inventors have unexpectedly found that the degradation process may also be accelerated by use of electrolysis, such as but not limited to the Electrochemical Advanced Oxidisation Process (EAOP), which will (i) generate one or more radical species for degradation of fluoro-carbon skeleton of the fluorinated organic compound, by directly oxidising the fluoro-carbon skeleton of the fluorinated organic compound and (ii) refresh or regenerate the chemical oxidants in-situ for continued degradation of the fluorinated organic compound.

[0097] Fig. 1 shows photographic images depicting the colour change associated with the oxidisation process when the perfluorinated organic compounds, PFOA, PFOS and 6:2FTS, were each subjected to 0.1 % KMnO₄ + 0.36% HCI (w/w) for extended periods of 3 months and 6 months.

[0098] As shown in Fig. 1 , the purple colour of each of the PFOA, PFOS and 6:2FTS solutions on the left of the image confirm the existence of KMnO₄. After 3 months, the colour had changed to brown, confirming that the oxidisation of PFOA, PFOS and 6:2FTS was in progress.

[0099] After 6 months, the PFOA, PFOS and 6:2FTS solutions were completely transparent with only some minor precipitates observed at the bottom of the containers. Analysis (not shown) of the precipitates confirmed them to be products of the oxidisation process, such as MnSO₄, MnO₂, etc. These precipitates were filtered from solution prior to HPLC and ion chromatograph (IC) analysis.

[00100] Fig. 2 shows HPLC-MS data showing the breakdown of (a) PFOA, (b) PFOS and (c) 6:2FTS when subjected to oxidisation with 0.1 % KMnO₄ + 0.36% HCI (w/w) for 3 months. In all three samples, there is a significant decrease in peak height after oxidisation (marked "after" - solid line), as compared to the same solutions (without chemical oxidant) used as controls (marked "before" - dashed line), confirming the oxidisation, and thus breakdown of the perfluorinated organic compounds into smaller fragments.

[00101 ] Fig. 2(d) shows a comparison of the concentrations of PFOA, PFOS and 6:2FTS, before and after oxidisation for 3 months, calibrated using external standards. The results clearly show a significant decrease in concentration in all three samples, with decreases ranging from 62% to 45%.

[00102] Fig. 3 (a) shows HPLC-MS data that reveals the breakdown of PFOA, PFOS and 6:2FTS subjected to the oxidisation with 0.1 % KMnO₄ + 0.36% HCI (w/w) for 3 to 6 months. It is apparent from the presented HPLC-MS data that the concentrations of each of the perfluorinated organic compounds (PFOA, PFOS and 6:2FTS) declined gradually as the oxidisation progressed from 3 months to 6 months. Despite the limited number of data points, it is still possible to estimate from the kinetics information that the half-life of each of the perfluorinated organic compounds (PFOA, PFOS and 6:2FTS) has been reduced to approximately 3 months as a result of the present method. This estimated half-life is significantly shorter than the half-lives (i.e. > 10 years) associated with the biodegradation of these perfluorinated organic compounds in the natural environment, suggesting that the present method makes a significant contribution.

[00103] Fig. 3(b) shows ion chromatograph (IC) data that compares the free concentrations of F^" ions and SO₄ ^2" ions detected in solution before and after oxidisation following oxidisation of the perfluorinated organic compounds (PFOA, PFOS and 6:2FTS) with 0.1 % KMnO₄ + 0.36% HCI (w/w) for 6 months. It is apparent from the presented IC data that the concentration of F^" ions increased significantly after 6 months' oxidisation when compared to almost zero (less than the limit of detection, 0.5 ppm) for all three samples without oxidisation. The presence of the free F^" ions in solution clearly confirms the breakdown of the fluoro-carbon skeleton of each of the perfluorinated organic compounds (PFOA, PFOS and 6:2FTS).

[00104] For PFOS and 6:2FTS, the inventors also observed an increased concentration of SO₄ ^2" ions after oxidisation, which originated from their sulfonic groups associated with these perfluorinated organic compounds. Conversely, there are no detectable SO₄ ^2" ions before or after the oxidisation of PFOA, supporting the above assumption that sulfonic-containing groups were broken down and converted into SO₄ ^2" ions.

[00105] It is noteworthy that some SO₄ ^2" ions were detected before oxidisation of PFOS and 6:2FTS commenced. Whilst not wishing to be bound by any one particular theory, the inventors believe that this may be due to an impurity associated with the original sample, or due to the partial breakdown of the sulfonic groups of these compounds by atmospheric oxygen. Support for this theory can be found in the observations that control samples, namely PFOS and 6:2FTS (without oxidant), which were studied in parallel (including dilution and storage in air for 6 months) showed similar readings.

[00106] Based on calculations, the concentrations of F^" ions detected in solution were estimated to be -1 .2 ppm (-0.6 imM) for all three samples while the concentrations of SO₄ ^2" ions detected in solution were 6.5 ppm (-0.068 imM) for each of PFOS and 6:2FTS, respectively. Considering that all three samples were diluted to 100 ppm (0.24 mM for PFOA, 0.20 mM for PFOS and 0.23 mM for 6:2FTS), the measured concentrations of free F^" ions and SO₄ ^2" ions in each sample indicates that the breakdown of the fluoro-carbon skeleton is around 17-20% in terms of free F^" ions and around 25-30% in terms of SO₄ ^2" ions (taking into consideration the amount of SO₄ ^2" ions detected before the oxidisation in respect of PFOA and 6:2FTS), respectively, which agrees well with the results in Fig. 3(a). It is expected that the remaining fluoro- containing compounds, namely fragments of the starting perfluorinated organic compound (PFOA, PFOS and 6:2FTS) will degrade to free F^" ions with further oxidisation.

[00107] It will be appreciated by those skilled in the relevant art that the present method is not limited to simply employing just one chemical oxidant for the purpose of degrading the fluoro-carbon skeleton of the fluorinated compound. Rather, it may be possible to employ one or more compatible chemical oxidants in solution at one time for said purpose.

[00108] For instance, in one embodiment, the one or more chemical oxidants are selected from the group consisting of KMnO₄, K₂Cr₂O₇, PbO₂ and NaBiO₃.

[00109] Summary

[001 10] It is evident from the obtained data (Figs. 1 to 3) above that the present method is capable of degrading the fluoro-carbon skeleton of a perfluorinated organic compound perfluorinated organic compound to generate one or more fragments and/or one or more fluoride ions. Of particular note (see Fig. 3) is the observation that the oxidisation capacity of the preferred composition, 0.1 % KMnO₄ + 0.36% HCI, faded with time and was not as strong as the fresh solution, as observed in Fig. 1. In other words, the inventors believe that the degradation of the perfluorinated organic compounds will be accelerated if the chemical oxidant solution is refreshed continuously during the degradation process. In addition, by extending the degradation process to greater than 6 months, it is expected that the concentrations of free F^" ions and SO₄ ^2" ions detected in solution should be greater.

[001 1 1 ] Electrochemical Advanced Oxidisation Process (EAOP)

[001 12] The electrochemical advanced oxidisation process (EAOP) has recently received significant attention due to its universal breakdown of organic material using extremely active radicals generated by electricity. This process represents a clean and rapid approach to the degradation of organic material. In a typical EAOP process, the electrode materials employed in the electrochemical cell include lead dioxide (PbO₂), tin oxide (SnO₂), boron-doped diamond (BDD), etc. Basically, seeking a cheap electrode material with high over-potential (oxygen emission) is desirable.

[001 13] In an attempt to realise a method of degrading a perfluorinated organic compound where there is the propensity to refresh the chemical oxidant, the inventors have employed an EAOP-type as will now be described below.

[001 14] Electrochemical System

[001 15] In this embodiment, the inventors have devised an EAOP electrochemical cell based on a lead-acid car battery.

[001 16] Briefly, the lead-acid battery employed in the electrochemical system of the present invention takes the form of a container or cell comprising at least one positive plate and at least one negative plate disposed within the cell, a separator disposed within said cell for use in separating said positive and negative plates. Both plates are immersed into an electrolytic solution of diluted sulfuric acid. In each cell, the negative plate or anode is porous metallic lead (Pb) and the positive plate or cathode is lead dioxide (PbO₂).

[001 17] As a lead-acid battery discharges, completing the circuit, electrons are released from the anode and the resulting Pb²⁺ ions immediately react with the SO₄ ^2" ions in the electrolyte medium precipitating out insoluble lead sulfate (PbSO₄) on the surface of the electrode. At the cathode, electrons from the external circuit reduce PbO₂ to water (H₂O) and Pb²⁺ ions, which also immediately react with SO₄ ^2" ions to precipitate PbSO₄ on the electrode.

[001 18] The reactions at the electrodes are as follows:

Anode:

Pb(s) + HS0₄-(aq) ► PbS0₄(s) + H⁺(aq) + 2e^"

Cathode:

Pb0₂(s) + HS0₄-(aq) +3H⁺(aq) + 2e ^► PbS0₄(s) + 2H₂0 (I)

[001 19] Thus, both the cathode and the anode are largely converted to PbSO₄(s) when the battery is fully discharged. By applying an opposite voltage to one cell, a reverse chemical reaction occurs and that cell will recharge, thereby providing a means by which a chemical oxidant and electrode material with high over-potential, in this case PbO₂, can be refreshed. [00120] Thus, the empirical reaction for a lead acid battery can be expressed as:

Discharge

Pb(s) + Pb0₂(s) + 2H₂S0₄(aq) * 2PbS0₄(s) + 2H₂0(I)

Charge

[00121 ] As a result of this lead acid battery arrangement by over-charging, the EAOP process generates extremely active radicals, including but not limited to [ΟΗ^'] radicals, as shown in the reaction steps below, that can be used in the degradation of organic materials. On the other hand, organic materials can also be directly oxidised on the anode surface.

Pb0₂ + H₂0 PbO(OH)₂ PbO(OH)₂ ► PbO(OH⁺)(OH") + e-

PbO(OH⁺)(OH-) ₊ H₂0 _PbO(OH)₂[OH-] ₊ H*

[00122] Electrochemical Method

[00123] The electrochemical method of degrading a perfluorinated organic compound according to the preferred embodiment comprises as a first step, step a), the step of introducing first and second electrodes into an electrolyte medium comprising a perfluorinated organic compound.

[00124] The first electrode of the lead acid battery cell is provided in the form of a PbO₂ electrode or an electrode with at least a coating of PbO₂ thereon. It will be appreciated that the PbO₂ (or PbO₂ coated) electrode as the chemical oxidant undergoes polarisation to produce one or more radical species including [ΟΗ^'] radicals (among other radicals) effective for activating degradation of a fluoro-carbon skeleton of a perfluorinated organic compound over a predetermined time period. The second electrode of the lead acid battery cell is provided in the form of porous metallic lead (Pb) of an electrode with a coating of Pb thereon, and the electrolyte medium is a 33% (w/w) aqueous solution of sulfuric acid (H₂SO₄), to which has been added a corresponding one of the three perfluorinated organic compounds (PFOA, PFOS and 6:2FTS) for degradation.

[00125] According to a second step, step b), a voltage of between 1 V to 4 V is then applied between the PbO₂ (or PbO₂ coated) electrode and the porous metallic lead (Pb) electrode to produce said one or more radical species including [ΟΗ^'] radicals (among other radicals including [O₂ ] (superoxide radicals) and [HO₂ ] (hydroperoxyl radicals, to name but a few) capable of oxidizing the perfluorinated organic compound to generate one or more fragments and/or one or more fluoride ions. Alternatively, perfluorinated organic compound can be directly oxidised on this electrode surface.

[00126] The inventors have surprisingly found that degradation of the perfluorinated organic compound using this electrochemical method can be achieved in as little as a few hours.

[00127] Indeed, good results have been obtained when the predetermined time period is between 1 to 4 hours, more preferably between 2 to 3 hours, when a voltage of around 3 V is applied between the electrodes.

[00128] In other embodiments, the electrolyte medium may be a solution of Na₂SO₄, NaCIO₄.

[00129] The inventors have found that PbO₂ electrodes exhibit a high overpotential for water electrolysis, which hampers the oxidisation of water to emit oxygen at high voltage. Since water cannot be oxidised (due to such high overpotential on PbO₂), this allows the one or more radical species including [ΟΗ^'] radicals to be effectively used for the oxidization of the perfluorinated organic compounds.

[00130] Whilst not wishing to be bound by any one particular theory, the inventors consider that while the generated hydroxyl [ΟΗ^'] radical is important to the degradation process, is not strong enough to directly degrade the perfluorinated organic compounds itself. Rather, the oxidisation of perfluorinated organic compounds must be initialised on the PbO₂ electrode directly with the generation of one or more perfluorinated organic compound radicals (i.e. fragments). Once perfluorinated organic compound radicals have been generated, the [ΟΗ^'], [Ο₂ ^' ], [ΗΟ₂ ^'] radicals (and other radicals) can then attack the fluoro-carbon skeleton of these perfluorinated organic compound radicals to complete the degradation process.

[00131 ] Fig. 4 shows the results of an Electrochemical Advanced Oxidisation Process (EAOP) process using a lead acid battery equipped with Pb/PbO₂ electrodes in an aqueous 33% H₂SO₄ (w/w) electrolyte medium to degrade the perfluorinated organic compound, PFOA, into one or more fragments and/or one or more fluoride ions over a predetermined period of time. [00132] Fig. 4(a) shows images (using a commercial (astkCARE™) anionic surfactant test kit) obtained before and after oxidisation of PFOA by one or more radical species including hydroxyl [ΟΗ^'] radicals produced during the EAOP process. Briefly, 10 ml of an aqueous solution of PFOA (100 ppb-3 ppm) was placed into a sample container to which was added 7.5 ml of astkCARE™ reagent. The sample-dye-solvent mixture was then shaken vigorously, before being allowed to stabilize and form two phases. If an anionic surfactant (i.e. PFOA) is present, then the cationic dye and the anionic surfactant will form an ion pair, which is extracted into the organic phase. The intensity of the dye coloration in the organic phase will be proportional to the concentration of the anionic surfactant (i.e. PFOA) in the organic phase.

[00133] Based on the observed results in Fig. 4(a), it is clear that as the oxidisation process proceeds over the period of 4 to 10 hours, the concentration of PFOA in the organic phase (top layer) of the biphasic solution decreases over time to the point that the PFOA has been degraded into one or more fragments and/or one or more fluoride ions.

[00134] Fig. 4(b) shows corresponding ion chromatograph data showing the breakdown of PFOA over time. The obtained results shown in Fig. 4(b)(i) reveal that the concentration of PFOA in solution decreased from 40 ppm to -0.1 ppm within the space of 4 hours. While in Fig. 4(b)(ii), the obtained results reveal that the concentration of PFOA in solution decreased from 5 ppm to -0.02 ppm when the operation time was prolonged for 10 hours. The inventors observed that the initial concentration of the PFOA and the duration of the degradation process at least partly influenced the difference in results. This difference aside, the overarching evidence clearly points to the successful degradation of a perfluorinated organic compound using a simple lead acid battery set up.

[00135] In one embodiment, one or more additional chemical oxidants may be added to the electrolyte medium, in the presence of the PbO₂ electrode, for the purpose of degrading the fluoro-carbon skeleton of the fluorinated organic compound.

[00136] For instance, the inventors supposed that when potassium permanganate (KMnO₄) is added to the electrolyte medium as a chemical oxidant to oxidise the fluoro- carbon skeleton of the fluorinated organic compound, as oxidisation occurs and KMnO₄ is concurrently reduced to Mn²⁺ ions, by virtue of the reversible nature of the lead acid battery system it becomes possible to regenerate the KMnO₄ chemical oxidant by oxidising the Mn²⁺ ions in-situ, thereby refreshing the chemical oxidant for use in further degradation of the fluoro-carbon skeleton of the fluorinated organic compound.

[00137] By virtue of this arrangement, it becomes possible to continually refresh the chemical oxidant in-situ thereby providing an environment whereby a fresh chemical oxidant is available for oxidisation purposes. In this respect, the efficiency of the process for degrading fluorinated organic compounds is significantly improved.

[00138] It will be appreciated by persons skilled in the relevant art that other chemical oxidants including, but not limited to sodium bismuthate (NaBiOa) and potassium dichromate (K₂Cr₂O7), may be added as the additional chemical oxidant to the electrolyte medium.

[00139] Summary

[00140] The inventors have found that by being able to recharge the lead acid battery during the process of degrading the fluoro-carbon skeleton of the perfluorinated organic compound, it becomes possible to refresh the chemical oxidant (for example, PbO₂, KMnO₄, NaBiO₃) and thus enhance the degradation of the perfluorinated organic compound to achieve a more effective breakdown of the organic compound into one or more fragments and/or fluoride ions in a predetermined time period of as little as 2 hours, as confirmed by HPLC-MS and IC analyses. By virtue of the above observations, it will be appreciated by persons of ordinary skill in the relevant art that the present electrochemical method is capable of degrading not only the non-fluoro-carbon bonds of a partially fluorinated organic compound, but also the fluoro-carbon bonds of the fluoro- carbon skeleton too.

[00141 ] In essence, this considerably shortened half-life represents a significant advance over that achieved using conventional methods to degrade organic compounds, with the added and important benefit that both partially and fully fluorinated organic compounds can be degraded using this method.

Experimental Section

[00142] Materials and Methods

[00143] All chemicals including PFOA, PFOS and 6:2FTS, potassium permanganate (KMnO₄), hydrogen chloride (HCI, 37%, w/w), methanol and ammonium acetate (NH₄Ac) were purchased from Sigma-Aldrich (Australia). Only polypropylene containers/pipette tips were used throughout to avoid any potential interference from Teflon containers/caps. Milli-Q water was used (> 18 MQ*cm) in the present study. [00144] All samples were diluted in Milli-Q water in centrifuge tubes (polypropylene) without pre-treatment. 0.1 % KMnO₄ + 0.36% HCI (w/w) was placed in the tubes for the oxidisation process. The tubes were kept at room temperature (-24 °C) and not shielded from the laboratory fluorescent lamp to mimic domestic lighting. The tubes were occasionally shaken (once per day) during oxidisation. Samples were filtered with nylon syringe filters (0.2 μιη) prior to HPLC-MS analysis HPLC-MS (Agilent 1260 + Quadrupole 6130) before and after the oxidisation.

[00145] For HPLC-MS analysis, the inventors performed the standard method (EPA/600/R-08/092). In general, a 10 μΙ_ sample solution was injected into an Agilent 1260 high-performance liquid chromatography fitted with an XDB-C18 column kept at 40 °C. Its dimensions were 2.1 mm internal diameter, 100 mm length and 5 μιη particle size. The flow rate was 0.5 mL/min for gradient mobile phase of methanol: 5 mM aqueous NH₄Ac for separation. Quadrupole 6130 detector was maintained at 70 V under negative mode for scanning. Extraction of the molecular ions was conducted at m/z 413 for PFOA, 499 for PFOS and 427 for 6:2FTS, respectively. Quantification was done by producing a calibration curve using standard solutions of PFOA, PFOS (only linear isomers) and 6:2FTS with correlation coefficients higher than 0.99 and limit of detection being -0.2 ppb (signal: noise > 3). Blank samples of Milli-Q water and methanol were run prior to each set of test to minimise any background contamination that could have originated from the Teflon components of the HPLC instrument itself. The nebuliser gas (nitrogen) pressure was set at 40 psi, drying gas flow rate was 9 L/min and temperature 325 ^QC, capillary voltage was +3500 V and skimmer voltage was -15 V.

[00146] The concentrations of free fluoride (F^") ions and sulphate (SO₄ ^2") ions were detected in solution by ion chromatography (IC) using a Reagent-Free ion chromatograph system (ICS-2000, DIONEX, Thermo Scientific) equipped with an lonPacTM AS18 (2 ^χ 250 mm) separation column maintained at 35 °C under 2230 psi pump pressure. Following 25 μΙ_ sample injection, 10 mM KOH was flowed through the column at a flowrate of 0.25 mL/min. A conductivity detector was employed with a suppressor of 43 imA.

[00147] Note that each time, at least 6 samples were run in parallel (three samples without addition of chemical oxidant as controls and the other three samples with chemical oxidant) for quality assurance and quality control (QA/QC). Other Embodiments

[00148] It will be appreciated that the choice of organic pollutants for degradation according to the embodiments of the present invention is not limited to the perfluorinated organic compounds described above. For example, the presently claimed methods can equally be extended to cover all organic pollutants, that is, organic pollutants that comprise fewer or no fluoro-carbon bonds because these organic pollutants will be much easier to degrade than perfluorinated organic compounds.

[00149] It will be appreciated that the choice of chemical oxidants is not limited to the oxidants described above. For example, suitable chemical oxidants may exist in other metal salts.

Definitions

[00150] Whenever a range is given in the specification, for example, a temperature range, a time range, or concentration range, all intermediate ranges and subranges, as well as all individual values included in the ranges given are intended to be included in the disclosure. It will be understood that any subranges or individual values in a range or subrange that are included in the description herein can be excluded from the claims herein.

[00151 ] All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

[00152] The indefinite articles "a" and "an," as used herein in the specification, unless clearly indicated to the contrary, should be understood to mean "at least one."

[00153] The phrase "and/or," as used herein in the specification, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and/or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and/or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[00154] The term "fluorinated organic compound" used herein designates organic compounds that comprise at least one carbon-fluorine bond.

[00155] The term "fluoro-carbon skeleton" used herein designates organic compounds whose chemical structure contains a carbon skeleton in which some or all of the carbon atoms have fluorine atoms bound thereto.

[00156] While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternatives, modifications and variations in light of the foregoing description are possible. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations as may fall within the spirit and scope of the invention as disclosed.

[00157] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

Claims (43)

Claims The claims defining the invention are as follows:

1 . A method for degrading a fluorinated organic compound, the method comprising the steps of: introducing at least one chemical oxidant into a medium comprising a fluorinated organic compound, the chemical oxidant being effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period; and oxidizing the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or one or more fluoride ions.

2. A method according to claim 1 , wherein the chemical oxidant is selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7) , lead dioxide (PbO2) and sodium bismuthate (NaBiOa).

3. A method according to claim 1 , wherein the chemical oxidant comprises potassium permanganate (KMnO₄).

4. A method according to claim 1 , wherein the predetermined time period is at least 180 days.

5. A method according to claim 1 , wherein the medium is selected from the group consisting of an aqueous liquid, a foam, a sludge, a sediment, bedrock, run-off water, ground water, industrial effluent, process water, waste water, soil and a combination thereof.

6. A method according to claim 1 , wherein the chemical oxidant is used at a concentration that falls within a range of about 0.00001 mmol/l to about 1 mmol/l.

7. A method according to claim 1 , further comprising, before step b), the step of introducing a catalyst into the medium, the catalyst being effective for catalysing the degradation of the fluoro-carbon skeleton of the fluorinated organic compound with the chemical oxidant.

8. A method according to claim 7, wherein the catalyst is selected from the group consisting of an acid catalyst and a photocatalyst.

9. A method according to claim 8, wherein the chemical oxidant is 0.1 % KMnO₄ and the acid catalyst is 0.36% HCI (w/w).

10. A method for degrading a fluorinated organic compound, the method comprising the steps of: introducing first and second electrodes into an electrolyte medium comprising a fluorinated organic compound, the first electrode comprising a chemical oxidant that when polarised, produces one or more radical species effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period; and applying a voltage between the first electrode and the second electrode to generate said one or more radical species to oxidize the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or one or more fluoride ions.

1 1 . A method according to claim 10, wherein the chemical oxidant is lead dioxide (PbO2), the electrolyte medium is a 33% (w/w) aqueous solution of sulfuric acid (H₂SO₄), and the second electrode comprises lead (Pb) or at least a coating of Pb thereon.

12. A method according to claim 10, wherein the predetermined time period is at least 1 hour.

13. A method according to claim 10, wherein the predetermined time period is at least 2 hours.

14. A method according to claim 10, wherein the voltage applied between the first and second electrodes falls within a range of 1 V to 4 V.

15. A method according to claim 10, further comprising the step of: introducing one or more additional chemical oxidants into the electrolyte medium that are effective for activating degradation of the fluoro-carbon skeleton of the fluorinated organic compound.

16. A method according to claim 15, wherein the one or more additional chemical oxidants are selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O₇), and sodium bismuthate (NaBiO₃).

17. A method according to claim 1 or 10, wherein the fluorinated organic compound is a perfluorinated organic compound.

18. A method according to claim 1 or 10, wherein the fluorinated organic compound is a fluorosurfactant.

19. A method according to claim 16, wherein the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

20. A method according to claim 1 or 10, wherein the fluorinated organic compound is a fluoroteleomer.

21 . A method according to claim 20, wherein the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).

22. A composition for degrading a fluorinated organic compound in a medium, comprising a chemical oxidant being effective for activating degradation of a fluoro- carbon skeleton of the perfluorinated organic compound over a predetermined time period by oxidizing the fluorinated organic compound with the chemical oxidant to generate one or more fragments and/or fluoride ions.

23. A composition according to claim 22, wherein the chemical oxidant is selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7) , lead dioxide (PbO2) and sodium bismuthate (NaBiOa).

24. A composition according to claim 22, wherein the chemical oxidant comprises potassium permanganate (KMnO₄).

25. A composition according to claim 22, further comprising a catalyst being effective for catalysing the degradation of the fluoro-carbon skeleton of the fluorinated organic compound with the chemical oxidant.

26. A composition according to claim 25, wherein the catalyst is selected from the group consisting of an acid catalyst and a photocatalyst.

27. A composition according to claim 22, wherein the chemical oxidant is used at a concentration that falls within a range of about 0.001 mmol/l to about 10 mmol/l.

28. A composition according to claim 26, wherein the chemical oxidant is 0.1 % KMnO₄ and the acid catalyst is 0.36% HCI (w/w).

29. A composition according to claim 22, wherein the medium is selected from the group consisting of an aqueous liquid, a foam, a sludge, a sediment, bedrock, run-off water, ground water, industrial effluent, process water, waste water, soil and a combination thereof.

30. A composition according to claim 22, wherein the fluorinated organic compound is a perfluorinated organic compound.

31 . A composition according to claim 22, wherein the fluorinated organic compound is a fluorosurfactant.

32. A composition according to claim 29, wherein the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

33. A composition according to claim 22, wherein the fluorinated organic compound is a fluoroteleomer.

34. A composition according to claim 33, wherein the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).

35. A system for degrading a fluorinated organic compound, the system comprising: at least one electrochemical cell including first and second electrodes, and a separator for use in separating said first and second electrodes, the at least one electrochemical cell being configured to receive an electrolyte medium comprising a fluorinated organic compound, into which the first and second electrodes and the separator can at least be partially immersed; wherein the first electrode comprises a chemical oxidant that when polarised by applying a voltage between the first electrode and the second electrode, produces said one or more radical species effective for activating degradation of a fluoro-carbon skeleton of the fluorinated organic compound over a predetermined time period by oxidizing the fluorinated organic compound to generate one or more fragments and/or one or more fluoride ions.

36. A system according to claim 35, wherein the chemical oxidant is lead dioxide (PbO₂).

37. A system according to claim 35, further comprising one or more additional chemical oxidants effective for activating degradation of the fluoro-carbon skeleton of the fluorinated organic compound, wherein the one or more additional chemical oxidants are introduced into the electrolyte medium.

38. A system according to claim 37, wherein the one or more additional chemical oxidants are selected from the group consisting of potassium permanganate (KMnO₄), potassium dichromate (K₂Cr₂O7), and sodium bismuthate (NaBiOa).

39. A system according to claim 35, wherein the fluorinated organic compound is a perfluorinated organic compound.

40. A system according to claim 5, wherein the fluorinated organic compound is a fluorosurfactant.

41 . A system according to claim 40, wherein the fluorosurfactant is selected from the group consisting of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

42. A system according to claim 35, wherein the fluorinated organic compound is a fluoroteleomer.

43. A system according to claim 42, wherein the fluoroteleomer is selected from the group consisting of 1 H, 1 H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS) and 1 H, 1 H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS).