WO2026012765A1 - Grafted sulfoxide mediated mineralization of perfluoroalkyl acids (pfaas) and of perfluoroalkyl acid derivatives - Google Patents

Abstract

The present invention relates to a process for the mineralization of perfluoroalkyl acids (PFAA) and/or perfluoroalkyl acid derivatives comprising the following steps: a) obtaining a water solution (S0) comprising the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative, optionally in the presence of a base; b) heating the solution (S0) up to a temperature T1; c) passing the solution (S0) at temperature T1 through a column packed with a non- water-soluble sulfoxide containing resin, to obtain a solution (S1) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are at least partially mineralized; wherein the non-water-soluble sulfoxide containing resin comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups.

Description

Grafted sulfoxide mediated mineralization of perfluoroalkyl acids (PFAAs) and of perfluoroalkyl acid derivatives

Cross-reference to related application

[0001] This application claims priority to European application No. 24187598.8 filed on July 10, 2024, the whole content of this application being incorporated herein by reference for all purposes.

Technical field

[0002] The present invention relates to a process for the mineralization of at least one perfluoroalkyl acid (PFAA) and/or at least one perfluoroalkyl acid derivative comprising the following steps: a) obtaining a water solution (SO) comprising the at least one perfluoroalkyl acid (PFAA) and/or the at least one perfluoroalkyl acid derivative, optionally in the presence of a base; b) heating the solution (SO) up to a temperature T1 ranging from 40°C to 120 °C; c) passing the solution (SO) at temperature T1 of step b) through a least one column, thermostated at a temperature T2 ranging from 40°C to 120°C which can be different or equal to T1 , packed with a non-water-soluble sulfoxide containing resin, to obtain a solution (S1) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are completely, substantially completely or at least partially mineralized; d) optionally reproducing step c) up to n-1 times, wherein n is an integer > 1 , until obtaining a solution (Sn), wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized; wherein the non-water-soluble sulfoxide containing resin comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups.

Background [0003] Perfluoroalkyl acids (PFAAs) are chemical compounds which have been used in many industrial or commercial products. As such or as derivatives like salts, esters or amides, they have been used as surfactants in different applications.

[0004] The designation of perfluoroalkyl acids (PFAAs) encompasses perfluorocarboxylic acids (PFCAs) of formula CnF2n+i-COOH; perfluorosulfonic acids (PFSAs) of formula CnF2n+i-SO3H; perfluorophosphonic acids (PFPAs) of formula CnF2n+i-PO3H2; perfluorophosphinic acids (PFPiAs) of formula CnF2n+i-PO2H-CmF2m+i; perfluoroether carboxylic acids (PFECAs) of formula CnF2n+i-O-CmF2m-COOH; perfluoroether sulfonic acids (PFESAs) of formula CnF2n+i-CmF2m-SO3H, difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1 ,3- dioxolan-4-yl]oxy}acetic acid (cC6O4).

[0005] Generally, PFFAs degradation methods require harsh chemical conditions, large amounts of degrading chemicals, and large amounts of energy or combinations thereof.

[0006] However, Trang et al., in Science 377, 839-845 (2022) discloses a process for mineralization of perfluorocarboxylic acids through a sodium hydroxide- mediated defluorination pathway in dipolar aprotic solvents such as dimethylsulfoxide (DMSO) operating at low-temperature. The authors also highlight that degradation does not proceed in pure water.

[0007] Perfluoroalkyl acids (PFAAs) and perfluoroalkyl acid derivatives like salts, esters and amides are generally soluble in water to some extent. Accordingly, there is a need for a process for the mineralization of perfluoroalkyl acids and/or perfluoroalkyl acid derivatives that can be performed in water, optionally in the presence of a base.

[0008] There is also a need for a process suitable to degrade perfluoroalkyl acids (PFAAs) and perfluoroalkyl acid derivatives that can be conducted at moderate temperature.

[0009] There is still a need for a process suitable to degrade perfluoroalkyl acids (PFAAs) and perfluoroalkyl acid derivatives that can be conducted without using large amounts of degrading chemicals. [0010] Finally, there is a need for a process suitable to degrade perfluoroalkyl acids (PFAAs) and perfluoroalkyl acid derivatives that can be conducted in simple equipment like a column packed with a catalytically active substrate.

Summary of the invention

[0011] With the aim of fulfilling the above needs, the Applicant faced the problem of providing a new process suitable for complete or substantially complete mineralization of perfluoroalkyl acids (PFAAs) and/or perfluoroalkyl acid derivatives in mild operating conditions.

[0012] Thus, in a first aspect, the present application relates to a process for the mineralization of at least one perfluoroalkyl acid (PFAA) and/or at least one perfluoroalkyl acid derivative comprising the following steps: a) obtaining a water solution (SO) comprising the at least one perfluoroalkyl acid (PFAA) and/or the at least one perfluoroalkyl acid derivative, optionally in the presence of a base; b) heating the solution (SO) up to a temperature T1 ranging from 40°C to 120 °C; c) passing the solution (SO) at temperature T1 of step b) through a least one column, thermostated at a temperature T2 ranging from 40°C to 120°C which can be different or equal to T1 , packed with a non-water-soluble sulfoxide containing resin, to obtain a solution (S1) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are completely, substantially completely or at least partially mineralized; d) optionally reproducing step c) up to n-1 times, wherein n is an integer > 1 , until obtaining a solution (Sn), wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized; wherein the non-water-soluble sulfoxide containing resin comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups.

[0013] Without being bound to any theory, sulfoxide groups grafted onto the non- water-soluble resin are considered to act as catalyst for the mineralization of perfluoroalkyl acids and of perfluoroalkyl acid derivatives present in a water solution in the process according to the invention. [0014] In another aspect the present invention relates to the use of a column packed with a non-water-soluble sulfoxide containing resin for conducting mineralization of perfluoroalkyl acids (PFAA) or perfluoroalkyl acid derivatives.

[0015] Still in another aspect, the present application relates to an experimental or an industrial set up comprising a column packed with a non-water-soluble sulfoxide containing resin suitable for conducting the process according to the invention, wherein perfluoroalkyl acid (PFAA) or perfluoroalkyl acid derivatives are completely, substantially completely or at least partially mineralized.

Detailed description

[0016] The object of the invention is a process for the mineralization of at least one perfluoroalkyl acid (PFAA) and/or at least one perfluoroalkyl acid derivative comprising the following steps: a) obtaining a water solution (SO) comprising the at least one perfluoroalkyl acid (PFAA) and/or the at least one perfluoroalkyl acid derivative, optionally in the presence of a base; b) heating the solution (SO) up to a temperature T1 ranging from 40°C to 120 °C; c) passing the solution (SO) at temperature T1 of step b) through a least one column, thermostated at a temperature T2 ranging from 40°C to 120°C which can be different or equal to T1 , packed with a non-water-soluble sulfoxide containing resin, to obtain a solution (S1) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are completely, substantially completely or at least partially mineralized; d) optionally reproducing step c) up to n-1 times, wherein n is an integer > 1 , until obtaining a solution (Sn), wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized; wherein the non-water-soluble sulfoxide containing resin comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups.

[0017] Perfluoroalkyl acid (PFAAs) subjected to mineralization can be selected from the list consisting of perfluorocarboxylic acids (PFCAs) of formula CnF2n+i- COOH; perfluorosulfonic acids (PFSAs) of formula CnF2n+i-SO3H; perfluorophosphonic acids (PFPAs) of formula CnF2n+i-PO3H2; perfluorophosphinic acids (PFPiAs) of formula CnF2n+i-PO2H-CmF2_m+i ; perfluoroether carboxylic acids (PFECAs) of formula CnF2n+i-O-CmF2m-COOH; perfluoroether sulfonic acids (PFESAs) of formula CnF2n+1 -O-CmF2m-SO3H, difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1 ,3-dioxolan-4-yl]oxy}acetic acid (cCeCM) and mixtures thereof, wherein n and m which can be the same or different are integers ranging from 1 to 13.

[0018] Perfluoroalkyl acid (PFAAs) derivative can be selected from perfluoroalkyl acids salts, perfluoroalkyl acids esters, perfluoroalkyl acids amides and mixtures thereof.

[0019] Perfluoroalkyl acid (PFAAs) salt can be selected from ammonium salts, sodium salts, potassium salts and mixtures thereof.

[0020] In some embodiments, the perfluoroalkyl acid is selected from the list consisting of perfluorocarboxylic acids (PFCAs) of formula CnF2n+i-COOH; perfluoroether carboxylic acids (PFECAs) of formula CnF2n+i-O-CmF2m-COOH, difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1 ,3-dioxolan-4-yl]oxy}acetic acid (cC6O4) and mixtures thereof.

[0021] In some other embodiments, the perfluoroalkyl acid derivative is selected from the list consisting of salts, esters and amides of perfluorocarboxylic acids (PFCAs) of formula CnF2n+i-COOH, of perfluoroether carboxylic acids (PFECAs) of formula CnF2n+i-O-CmF2m-COOH, and of difluoro{[2, 2,4,5- tetrafluoro-5-(trifluoromethoxy)-1 ,3-dioxolan-4-yl]oxy}acetic acid (cCeCM) and mixtures thereof.

[0022] Still in some other embodiments, the perfluoroalkyl acid is perfluorocarboxylic acid selected from the list consisting of difluoro{[2,2,4,5-tetrafluoro-5- (trifluoromethoxy)-l ,3-dioxolan-4-yl]oxy}acetic acid (cCeCM), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and mixtures thereof. [0023] Still in some other embodiments, the perfluoroalkyl acid derivative is perfluorocarboxylic acid derivative selected from the list consisting of salts, esters and amides of difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1 ,3- dioxolan-4-yl]oxy}acetic acid (cCeO₄), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and of perfluorodecanoic acid (PFDA) and mixtures thereof.

[0024] The process according to the invention comprises the step a) of providing a water solution (SO) of at least one perfluoroalkyl acid (PFAA) and/or at least one perfluoroalkyl acid derivative.

[0025] Step a) is generally performed in a vessel such as a tank equipped with a stirring system and optionally a heating system.

[0026] The concentration of perfluoroalkyl acid (PFAA) and/or of perfluoroalkyl acid derivative in the water solution (SO) generally ranges from 0.0001 to 50 mmol./L at 25°C; often from 0.001 to 35 mmol/L at 25°C; sometimes from 0.01 to 20 mmol/L at 25°C. The concentration of perfluoroalkyl acid (PFAA) and/or of perfluoroalkyl acid derivative in the water solution (SO) can be more than 50 mmol./L if it is prepared and maintained at a temperature higher than 25°C.

[0027] In some embodiments, a base is added in step a).

[0028] The base can be inorganic and, generally selected from the list consisting of NaOH, KOH, NH₄OH, LiOH, Ca(OH)₂, Ba(OH)₂, CaCO₃, Na₂CO₃, NaHCO₃ and mixtures thereof. Often, the base is selected from NaOH, KOH, Ca(OH)₂, CaCO₃, and NH₄OH.

[0029] The base can be organic and generally selected from bases containing at least one nitrogen atom and mixtures thereof.

[0030] For example, suitable organic base can be selected from the list consisting of guanidine bases like 1 ,5,7-Triazabicyclo 4.4.0 dec-5-ene (TBD) and 1 , 1 ,3,3- tetramethylguanidine (TMG), amidine bases like 1 ,8- Diazabicyclo(5.4.0)undec-7-ene (DBU) and 1 ,5-Diazabicyclo(4.3.0)non-5-ene (DBN), 1 ,4-diazabicyclo[2.2.2]octane (DABCO), hexamethylenetetramine (HMTA), ethylenediamine (EDA), diethylenediamine (DEDA), triethylenediamine (TEDA), pyridine, imidazole, benzimidazole and mixtures thereof.

[0031] When a base is used in solution (SO), the molar ratio of base to fluorine atom present in perfluoroalkyl acid (PFAA) and/or of perfluoroalkyl acid derivative generally ranges from 0.1 to 5; often from 0.5 to 3; sometimes from 1 to 2.

[0032] For example, if (SO) contains perfluorooctanoic acid (PFOA) of formula C8HF15O2 in a concentration of 10 mmol/L, then it contains 150 mmol/L of fluorine atom. Accordingly, the concentration of the base in the solution (SO) should be 750 mmol/L to have a molar ratio of base to fluorine atom equal to 5.

[0033] In the step b) of the process according to the invention, the solution (SO) obtained in a) is generally heated at a temperature T1 ranging from 40°C to 120°C and maintained at this temperature.

[0034] In some embodiments, the mixture obtained in a) is heated at a temperature T1 ranging from 60°C to 100°C; sometimes at a temperature T1 ranging from 80°C to 100°C.

[0035] Step b) can be conducted in a vessel equipped with stirring and heating systems and which can serve as a reservoir of the solution (SO) at the temperature T1 . The vessel of step b) can be the same as the vessel of step a).

[0036] Step c) of the present invention is generally conducted in a column, packed with a non-water-soluble sulfoxide containing resin, equipped with a heating system or enclosed in a heating device such as an oven.

[0037] Generally the column used in step c) is thermostated at a temperature T2 ranging from 40°C to 120°C.

[0038] In some embodiments, the column used in step c) is thermostated at a temperature T2 ranging from 60°C to 100°C; sometimes at a temperature T2 ranging from 80°C to 100°C.

[0039] In step c), the heated solution (SO) at temperature T1 is passed through a column, packed with a non-water-soluble sulfoxide containing resin, to obtain a solution (S1 ). This is generally performed by injecting the solution (SO) in an inlet at one end of the column, using any means well known by the skilled person to inject a liquid in a column, and recovery of a solution (S1 ) in an outlet at the other end of the column.

[0040] For example, injection of heated solution (SO) of step b) through the column can be performed using a peristaltic pump.

[0041] Generally, step c) of the process according to the invention is conducted at a pressure ranging from 1 bar to 100 bars; often ranging from 1 bar to 50 bars; sometimes ranging from 1 bar to 20 bars.

[0042] Generally, the residence time of the solution (SO) in the column during step c) ranges from 5 seconds to 1 hour. Often, the residence time of the solution (SO) in the column during step c) ranges from 1 minute to 30 minutes; sometimes from 5 minutes to 15 minutes.

[0043] The solution (S1 ) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are completely, substantially completely or at least partially mineralized is recovered at the outlet of the column.

[0044] By mineralization is meant that the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative i.e. alkyl chain and functional groups is defluorinated and converted into hydrogen fluoride, fluoride salts, small hydrocarbons and mixtures thereof.

[0045] Mineralization is complete when the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative is completely defluorinated and completely converted into hydrogen fluoride, fluoride salts, small hydrocarbons and mixtures thereof.

[0046] Mineralization is substantially complete when at least 95 mol %, preferably at least 98 mol %, more preferably at least 99.9 mol % of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative is defluorinated and converted into hydrogen fluoride, fluoride salts, small hydrocarbons and mixtures thereof.

[0047] Mineralization can be assessed by any technique well known by the person of ordinary skill in the art. [0048] For example, mineralization of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative can be assessed by following the disappearance of signals characteristic of fluorine atoms corresponding to perfluorinated carbons in ¹⁹F NMR spectroscopy.

[0049] Still for example, mineralization of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative can be assessed by continuously monitoring the pH since mineralization will generate HF.

[0050] Besides, mineralization of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative can be assessed by monitoring CO2 generation in the off-gases by connecting a GC line to the head of the reactor.

[0051] When partial mineralization of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative is observed in (S1 ), the process comprises a step d) reproducing step c) up to n-1 times, wherein n is an integer > 1 , until obtaining a solution (Sn), wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized as above defined.

[0052] Reproducing step c) up to n-1 times, means reinjecting successively solutions (S1 ) to (Sn-1 ), at the temperature T1 , in the inlet of the column, packed with a non-water-soluble sulfoxide containing resin thermostated at the temperature T2, until recovering at the outlet of the column the solution (Sn) wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized as above defined.

[0053] The nature of the materials composing the vessels and the column used in the present invention is not limited. However, the steps of the process according to the invention are advantageously carried out in equipment capable of withstanding the conditions, especially due to the presence of HF at the temperature range required. This also applies for e.g. the peristaltic pump and other equipment.

[0054] For this purpose, materials are selected for the part in contact with the reaction mixture that are corrosion-resistant, such as the alloys based on molybdenum, chromium, cobalt, copper, manganese, titanium, zirconium, aluminium, carbon and tungsten, sold under the Hastelloy® brands or the alloys of nickel, chromium, iron and manganese to which copper and/or molybdenum are added, sold under the name Inconel® or MonelTM, and more particularly the Hastelloy C276 or Inconel 600, 625 or 718 alloys. Use may also be made of equipment consisting of or coated with a polymeric compound resistant to the corrosion of the reaction medium. Mention may in particular be made of materials such as PTFE (polytetrafluoroethylene or Teflon) or PFA (perfluoroalkyl resins).

[0055] Without being bonded to any theory, in the process according to the invention, the mineralization, which occurs at low temperature and under mild conditions, is deemed to be catalysed by the sulfoxide groups grafted onto the resin packed into the column. It is assumed that sulfoxide groups form some complexes with the polar groups of the perfluoroalkyl acid (PFAA) and/or of the perfluoroalkyl acid derivative that trigger the degradation of these perfluorinated compounds at relatively low temperature.

[0056] Any resin comprising sulfoxide groups is suitable for the process according to the invention. However, it is preferred that the resin is selected from polymers stable towards hydrolysis. Therefore generally a resin suitable for the present invention is free of hydrolysable groups such as ester, thioester, carbonate, thiocarbonate, amide, thioamide, imide, carbamate, thiocarbamate, urea and thiourea groups.

[0057] The non-water-soluble sulfoxide containing resin generally comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups such as those above described.

[0058] The non-water-soluble sulfoxide containing resin can be selected from polymers bearing sulfoxide groups in the polymer backbone, polymers bearing pending sulfoxide groups and mixtures thereof.

[0059] In some embodiments, the non-water-soluble sulfoxide containing resin is selected from crosslinked polymers bearing sulfoxide groups in the polymer backbone, crosslinked polymers bearing pending sulfoxide groups and mixtures thereof. [0060] Polymers bearing sulfoxide groups in the polymer backbone, or main chain polysulfoxides, are for example polyethylene sulfoxide (PESO) or polypropylene sulfoxide (PPSO) as represented below.

[0061] polyethylene sulfoxide (PESO) polypropylene sulfoxide (PPSO)

[0062] Polyethylene sulfoxide (PESO) and polypropylene sulfoxide (PPSO) can be prepared by selective oxidation of the corresponding polyethylene sulfide or polypropylene sulfide obtained by anionic ring-opening polymerization of ethylene sulfide or propylene sulfide respectively. Copolymers can be obtained starting from mixtures of ethylene sulfide and propylene sulfide.

[0063] In some embodiments, the polymers bearing sulfoxide groups in the polymer backbone are polymers or copolymers comprising a plurality of at least one of the repeat units of formulae (A) and (B) below:

[0064]

[0065] In some embodiments, polymers bearing pending sulfoxide groups, or side group polysulfoxides, can be selected from the group consisting of homopolymers and copolymers comprising a plurality of at least one repeat unit of formulae (C) to (E) below: wherein R, R’ and R”, which can be the same or different, are C1 -C6 alkyl groups.

[0066] For example, suitable copolymers bearing pending sulfoxide can be the copolymer (I) and the copolymer (II) below. These copolymers can be synthesized via a first step of free radical polymerization of ethylene or propylene, styrene and chlorobenzyl styrene to obtain a copolymer bearing chlorobenzyl groups. Then the sulfidation of the chlorobenzyl is performed followed by oxidation of the resulting sulfide to give copolymers bearing pending sulfoxide. A detailed example will be explained in the experimental copolymer (I) copolymer (II)

[0067] Crosslinked copolymer can be obtained e.g. by performing a first step of free radical polymerization of ethylene and/or propylene, styrene and chloromethyl styrene in the presence of divinylbenzene to obtain a crosslinked copolymer bearing chlorobenzyl groups that can be further modified to sulfide then to sulfoxide groups.

[0068] Still suitable copolymers bearing pending sulfoxide can be synthesized via a first step of free radical polymerization of styrene and chloromethyl styrene optionally in the presence of divinylbenzene.

[0069] In another aspect the present invention relates to the use of a column packed with a non-water-soluble sulfoxide containing resin for conducting mineralization of perfluoroalkyl acids (PFAA) or perfluoroalkyl acid derivatives.

[0070] The non-water-soluble sulfoxide containing resin as previously described is suitable for conducting mineralization of perfluoroalkyl acid (PFAA) or perfluoroalkyl acid derivatives in columns packed therewith.

[0071] Still in another aspect, the present application relates to an industrial set up comprising a column packed with a non-water-soluble sulfoxide containing resin for conducting mineralization of perfluoroalkyl acids (PFAA) or perfluoroalkyl acid derivatives.

[0072] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

[0073] The invention will be now described with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.

Experimental section

[0074] Raw materials

[0075] Propylene and nitrobenzene were obtained from Sigma Aldrich.

[0076] Chloromethylstyrene and styrene were obtained from Merck Millipore.

[0077] Di-tert-butylperoxide (DTBP) free radical initiator was obtained from Reagenti Carlo Erba.

[0078] All these materials were used without further purification.

[0079] Difluoro{[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1 ,3-dioxolan-4-yl]oxy}acetic acid (cC6O4) was synthesized internally according WO 2010/003929 A1.

[0080] Synthesis of copolymer bearing pending sulfoxide groups

[0081] Propylene (2 g) was condensed from a glass vacuum manifold rack into an AISI-316 high pressure reactor cooled in liquid nitrogen and equipped with inlet and outlet valves, a magnetic stir bar, an internal thermocouple, a pressure transducer connected to a Nanodac temperature and pressure digital multifunction reader. Following propylene filling, four vacuum/N2 cycles were run to ensure an O2 free atmosphere. The pressure reactor was left under vacuum and cooled in liquid nitrogen. A solution of 4-chloromethylstyrene (20 mol % vs propylene) and a solution of DTBP (5 mol% vs 4-chloromethylstyrene) in 10 mL nitrobenzene were then siphoned into the reactor and the reactor was warmed to room temperature.

[0082] The reactor was then fit into a steel heating mantle connected to temperature control equipped with 2 thermocouples connected to the Nanodac digital multifunction reader. The reactor was heated to 140°C for 8 hrs, then cooled to room temperature and the contents poured into a round-bottomed flask. The solvent was removed by distillation under vacuum and a white waxy substance was obtained. The wax was washed several times in diethyl ether in order to remove unreacted monomers.

[0083] After vacuum rotary evaporation at 50°C, the plastic-like wax was analysed by by semi-quantitative X-ray fluorescence elemental analysis (Cl as analyte) in order to determine the Cl content by comparison with a matrix of a known concentration of 4-chloromethylstyrene. Approximately 5 mol% of grafted 1 - ethyl-4-chlorobenzyl derivative was found to be incorporated.

[0084] A reaction pathway involving styrene is represented in scheme 1 below:

[0085] The chlorobenzyl derivative was suspended in toluene (50 mL) and approximately an equimolar amount of sodium methyl thiolate in a 20 wt % solution of NaOH in water was added along with tetrabutylammonium hydroxide (4 mol % vs chlorobenzyl group) as phase transfer catalyst and the biphasic mixture was stirred at 60°C for 4 days. After cooling to room temperature the toluene suspension phase was separated and washed with distilled water until neutral pH was reached. The waxy plastic was then washed with diethyether to remove all left-over organics and dried under vacuum with a rotary evaporator. Semi-quantitative X-ray fluorescence elemental analysis (S as analyte) was used to check that the SN2 had occurred.

[0086] Conversion to the sulfoxide was achieved by using an excess of H2O2 (15% w/w) at 30°C in CH2CI2 overnight to ensure only partial oxidation avoiding the following oxidation to sulfoxide. The oxidation mixture was then washed with an excess of distilled water, followed by a washing with diethylether and rotavapor evaporation at 60°C under vacuum. FT-IR (KBr) of the resulting plastic-like wax showed the sulfoxide band at 1030 - 1040 cm^-1 and disappearance of the 1240 cm^-1 band of C-S-C band (thio-ether). Thioether conversion = 100% and the final isolated yield was approximatively 10 mol%.

[0087] Example 1

[0088] The efficiency of grafted sulfoxide (grafted DMSO) was tested by performing a known reaction carried out with free DMSO and namely the oxidation of ethanol to acetaldehyde by the Swern Oxidation. Although grafted DMSO is not intended to be used for such a reaction, it was selected solely for the purpose of demonstrating that the DMSO synthon was actually bound to the resin and available as catalytic site. Oxalyl chloride (100 mg, 0.788 mmoles = 1 .58 meq) was placed in a round-bottom flask containing 5 mL of dry diethyl ether as the inert solvent. The reactor was equipped with a reflux condenser, a magnetic stirrer and an internal thermocouple attached to a Nanodac temperature reader. The grafted DMSO (1 g = approximately 1 mmol grafted DMSO) was placed in contact with the oxalyl chloride/diethyl ether solution and the mixture was cooled to -78°C with stirring in a Dewar containing a dry ice/acetone bath. Once the mixture turned pink, dry ethanol (23 mg = 27 pL = 0.5 mmol) was added with a micro-syringe and the mixture was kept at -78°C with stirring for 10 min. Once the solution turned a pale yellow, dry triethylamine (50 mg = 72 pL = 0.5 mmol) was added employing a micro-syringe. A slight exothermicity (+5°C) was observed at this time. One the internal T returned to -78°C the solution was warmed to -30°C and then an aliquot was injected in a GC equipped with a 25 m wide boar (0.54 mm) CP-Sil 8CB column. The acetaldehyde yield was calculated to be 35 %.

[0089] Example 2 (comparative example).

[0090] The same reaction described in Example 1 was carried out employing free DMSO (1 mmol = 39 mg = 35 pL). The calculated acetaldehyde yield was 50 %.

[0091] Example 3 (comparative example).

[0092] The same reaction described in Example 1 was repeated substituting grafted DMSO with the polystyrene/polypropylene polymer matrix. No acetaldehyde was observed. [0093] Table 1 : evaluation of grafted DMSO as catalyst for Swern Oxidation

Claims

Claims

Claim 1 . A process for the mineralization of at least one perfluoroalkyl acid (PFAA) and/or at least one perfluoroalkyl acid derivative comprising the following steps: a) obtaining a water solution (SO) comprising the at least one perfluoroalkyl acid (PFAA) and/or the at least one perfluoroalkyl acid derivative, optionally in the presence of a base; b) heating the solution (SO) up to a temperature T1 ranging from 40°C to 120 °C; c) passing the solution (SO) at temperature T1 through a least one column, thermostated at a temperature T2 ranging from 40°C to 120°C which can be different or equal to T1 , packed with a non-water-soluble sulfoxide containing resin, to obtain a solution (S1 ) wherein the perfluoroalkyl acid (PFAA) and/or the perfluoroalkyl acid derivative are completely, substantially completely or at least partially mineralized; d) optionally reproducing step c) up to n-1 times, wherein n is an integer > 1 , until obtaining a solution (Sn), wherein perfluoroalkyl acid (PFAA) and/or its derivatives are completely or substantially completely mineralized; wherein the non-water-soluble sulfoxide containing resin comprises a plurality of grafted sulfoxide groups and is free of hydrolysable groups.

Claim 2. The process according to claim 1 wherein the perfluoroalkyl acid (PFAA) is selected from the list consisting of perfluorocarboxylic acids (PFCAs) of formula CnF2n+i-COOH; perfluorosulfonic acids (PFSAs) of formula CnF2n+i-SO3H; perfluorophosphonic acids (PFPAs) of formula CnF2n+i-PO3H2; perfluorophosphinic acids (PFPiAs) of formula CnF2n+i-PO2H-CmF2m+i; perfluoroether carboxylic acids (PFECAs) of formula CnF2n+i-O-CmF2m-COOH; perfluoroether sulfonic acids (PFESAs) of formula CnF2n+i-O-CmF2m-SO3H, difluoro{[2,2,4,5-tetrafluoro-5- (trifluoromethoxy)-l ,3-dioxolan-4-yl]oxy}acetic acid (cC6O4) and mixtures thereof and wherein the perfluoroalkyl acid derivative is selected from salts, esters, amides and mixtures thereof.

Claim 3. The process according to claim 1 or 2, wherein the perfluoroalkyl acid (PFAA) derivative is a salt selected from ammonium salts, sodium salts, potassium salts and mixtures thereof.

Claim 4. The process according to any one of claims 1 to 3 wherein perfluoroalkyl acid (PFAA) is selected from the list consisting of perfluorobutanesulfonic acid (PFBS), perfluorooctanesulfonic acid (PFOS), perfluorobutanoic acid (PFBA), perfluoropentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), difluoro{[2, 2,4,5- tetrafluoro-5-(trifluoromethoxy)-1 ,3-dioxolan-4-yl]oxy}acetic acid (cC6O4) and mixtures thereof.

Claim 5. The process according to claims 1 to 5 wherein the non-water-soluble sulfoxide containing resin is selected from polymers bearing sulfoxide groups in the polymer backbone, polymers bearing pending sulfoxide groups and mixtures thereof.

Claim 6. The process according to claim 5 wherein polymer bearing sulfoxide groups in the polymer backbone is selected from the group consisting of polymers and copolymers comprising a plurality of at least one of the repeat units of formulae (A) and (B) below:

Claim 7. The process according to claim 5 wherein polymer bearing pending sulfoxide groups is selected from the group consisting of polymers and copolymers comprising a plurality of at least one of the repetitive unit of formulae (C) to (E) below: wherein R, R’ and R”, which can be the same or different, are C1 -C6 alkyl groups.

Claim 8. The process according to any one of the preceding claims, wherein the non-water-soluble sulfoxide containing resin is selected from crosslinked polymers.

Claim 9. The process according to any one the preceding claims, wherein step c) is conducted at a pressure ranging from 1 to 100 bars.

Claim 10. The process according to any one the preceding claims, wherein residence time of solution (SO) in the column during step c) ranges from 5 seconds to 1 hour.

Claim 11 . The process according to any one the preceding claims, wherein the base is selected from the list consisting of NaOH, KOH, NH4OH, LiOH, Ca(OH)2, Ba(OH)2, CaCOs, Na2CO3, NaHCOs and mixtures thereof.

Claim 12. The process according to any one the preceding claims, wherein the base is selected from organic bases containing at least one nitrogen atom and mixtures thereof.

Claim 13. The process according to claim 12, wherein the base is selected from the list consisting of guanidine bases like 1 ,5,7-Triazabicyclo 4.4.0 dec-5-ene (TBD) and 1 ,1 ,3,3-tetramethylguanidine (TMG), amidine bases like 1 ,8- Diazabicyclo(5.4.0)undec-7-ene (DBU) and 1 ,5-Diazabicyclo(4.3.0)non-5-ene (DBN), 1 ,4-diazabicyclo[2.2.2]octane (DABCO), hexamethylenetetramine (HMTA), ethylenediamine (EDA), diethylenediamine (DEDA), triethylenediamine (TEDA), pyridine, imidazole, benzimidazole and mixtures thereof.

Claim 14. Use of a column packed with a non-water-soluble sulfoxide containing resin for conducting mineralization of perfluoroalkyl acids (PFAA) and/or perfluoroalkyl acid derivatives.

Claim 15. Industrial set up comprising a column packed with a non-water-soluble sulfoxide containing resin wherein the non-water-soluble sulfoxide containing resin is selected from polymers bearing sulfoxide groups in the polymer backbone, polymers bearing pending sulfoxide groups and mixtures thereof, wherein polymer bearing sulfoxide groups in the polymer backbone is selected from the group consisting of polymers and copolymers comprising a plurality of at least one of the repeat units of formulae (A) and (B), wherein polymer bearing pending sulfoxide groups is selected from the group consisting of polymers and copolymers comprising a plurality of at least one of the repetitive unit of formulae (C) to (E) for conducting mineralization of perfluoroalkyl acids (PFAA) and/or perfluoroalkyl acid derivative