Cationic polythiophene derivatives and methods for detecting and removing perfluorinated compounds

Abstract

The application relates to the field of persistent pollutant detection and repair, in particular to a cationic polythiophene derivative for detecting and removing perfluorinated compounds and a method thereof. The provided cationic polythiophene derivative has good water solubility and presents obvious specificity in detection, can sensitively detect perfluorinated compounds, and the compounds shown in formula (I) and formula (II) exhibit different states to external stimulation in the conformation and aggregation state in solution, thereby causing the change of optical properties. The detected and removed perfluorinated compounds include short-chain perfluoroalkyl carboxylic acids (perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acids (perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acids (trifluoromethyl sulfonic acid TFMS, perfluorobutyl sulfonic acid PFBS, perfluorohexyl sulfonic acid PFHxS), and long-chain perfluoroalkyl sulfonic acids (perfluorooctyl sulfonic acid PFOS).

Description

Technical Field

[0001] This invention relates to the field of persistent contaminant detection and remediation technology, specifically to a cationic polythiophene derivative and method for detecting and removing perfluorinated compounds. Background Technology

[0002] Over the past decade, research on the environmental and health risks of perfluorinated compounds (PFCs) has intensified globally. PFCs are a class of synthetic compounds widely used in industries such as pesticide synthesis, food production, electroplating, textile finishing, and polymer production. Studies have shown that PFC pollution exists in global environmental media, as well as in wildlife and human bodies (blood, breast milk, liver), causing adverse effects on human health, including liver damage, thyroid disease, immunotoxicity, and cancer.

[0003] Therefore, efficient and sensitive detection of perfluorinated compounds is of great significance. Currently established methods for perfluorinated compound detection mainly include liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), and enzyme-linked immunosorbent assay (ELISA). These methods mostly rely on large-scale instruments and equipment. Although they offer high sensitivity, the equipment is expensive, the testing cycle is long, sample pretreatment is time-consuming and labor-intensive, and specialized testing personnel are required, making them unsuitable for large-scale sample and on-site testing.

[0004] The photochemical properties of materials are used to detect perfluorinated compounds (PFCCs) due to their speed and high sensitivity. Currently, most optical-based PFCC detection methods rely on the interaction between a fluorescent probe and the PFCC, leading to changes in fluorescence emission before and after the interaction. Our research group designed a metal polypyridine complex (Chinese patent: CN118638157A) as a fluorescent probe to achieve highly sensitive quantitative detection and removal of PFCCs. However, fluorescence sensing requires a specialized optical detection system and suffers from strong background interference, limiting its application.

[0005] Colorimetric sensing technology, as a simple analytical method, can be used as a pre-screening tool for on-site testing. When connected to a smartphone app, it provides convenient color readings, offering unique advantages such as rapid response and cost-effectiveness. Gold nanoparticles (AuNPs) are commonly used in the development of colorimetric sensors. Takayose et al. (Anal. Lett. 2012, 45, 2856) proposed a method for detecting perfluorinated compounds using gold nanoparticles. Perfluorinated compound-modified gold nanoparticles aggregate through fluorine-fluorine interactions. Finally, the solution color changes from red to purple. Despite its simplicity, the sensitivity is insufficient, with the lowest measurable concentration being only 103 ppm (250 μM). Niu et al. (Anal. Chem. 2014, 86, 4170) have also developed a gold nanoparticle-based sensor for the detection of perfluorinated compounds. In this method, two different functional groups are used to modify gold nanoparticles. Once perfluorinated compounds are adsorbed onto the surface of the gold nanoparticles, they begin to aggregate and precipitate. Quantitative detection of perfluorinated compounds is performed by measuring the absorbance in the supernatant. Therefore, incubation at room temperature for 0.5 hours is required before detection, followed by centrifugation to remove the precipitate from the reaction solution. This process is complex and time-consuming. Therefore, the development of rapid, convenient, and highly sensitive technologies for the detection and removal of perfluorinated compounds is urgently needed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for detecting and removing cationic polythiophene derivatives of perfluorinated compounds, thereby solving the problems existing in the prior art.

[0007] In order to achieve the objectives of this invention, the following technical solutions are provided:

[0008] A cationic polythiophene derivative for detecting and removing perfluorinated compounds, with the structure shown in formula (I) and formula (II):

[0009]

[0010] Formula (I) is a homopolymer structure, where R1 is H or CH3; R2 is O or CH2; R3 is an alkyl group or its isomer with an integer number of carbon atoms between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and such that the weight-average molecular weight of the polythiophene derivative is between 0.3 million and 50,000;

[0011] Equation (II) consists of a conjugated main chain formed by connecting each thiophene unit through positions 2 and 5, and its structural formula is shown below:

[0012]

[0013] Formula (II) is a copolymer structure, where R1 is H or CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R 1# ,R 2# ,R 3# ,R 4# R is selected from formula (Ⅰ) above. # Substituents, wherein R3 is an alkyl group or its isomer with an integer number of carbons between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; and satisfy R 1# ≠R 2# ≠R 3# ≠R 4# n1, n2, n3, n4 are integers between 1 and 500, and the average molecular weight of the polythiophene derivative is between 0.3 million and 100,000.

[0014] Furthermore, the types of perfluorinated compounds detected and removed include short-chain perfluoroalkyl carboxylic acids: perfluorobutyric acid (PFBA) and perfluorohexanoic acid (PFHxA); long-chain perfluoroalkyl carboxylic acids: perfluorooctanoic acid (PFOA) and perfluorododecanoic acid (PFDoA); short-chain perfluoroalkyl sulfonic acids: trifluoromethylsulfonic acid (TFMS), perfluorobutylsulfonic acid (PFBS) and perfluorohexylsulfonic acid (PFHxS); and long-chain perfluoroalkyl sulfonic acids: perfluorooctylsulfonic acid (PFOS).

[0015] A method for detecting perfluorinated compounds using the aforementioned cationic polythiophene derivative includes the following steps:

[0016] (1) The cationic polythiophene derivatives shown in formula (Ⅰ) and formula (Ⅱ) are dissolved in water to prepare probe molecules;

[0017] (2) Add the probe molecules obtained in step (1) into a quartz cuvette to obtain the detection reagent;

[0018] (3) The standard solution of perfluorinated compound was gradually added to the cuvette, and the changes in its ultraviolet-visible absorption spectrum and fluorescence spectrum were measured.

[0019] (4) Analyze the relationship between absorbance ratio and concentration of specific perfluorinated compounds and fluorescence intensity and concentration of specific perfluorinated compounds to perform quantitative and specific detection of specific perfluorinated compounds in solution.

[0020] Furthermore, the concentration of the cationic polythiophene derivative in the detection system is 0.1-100 μM, the reaction volume is 200-3000 μL, the reaction pH is 4-14, the reaction temperature is 4-40℃, and the reaction system is ultrapure water and HEPES buffer solution.

[0021] A method for removing perfluorinated compounds using the said cationic polythiophene derivative includes the following steps:

[0022] (1) Dissolve the cationic polythiophene derivatives shown in formula (Ⅰ) / formula (Ⅱ) in ultrapure water to obtain a probe molecule solution;

[0023] (2) The probe molecules prepared in step (1) are added to water containing perfluorinated compounds for reaction;

[0024] (3) After the reaction is complete, the solution is added to the removal system for separation and removal. The removed sample is analyzed to obtain the efficiency of the probe molecule in removing the specific perfluorinated compound.

[0025] Furthermore, when the concentration of the perfluorinated compound is between 20 and 200 μM, precipitation is used for separation and removal.

[0026] Furthermore, when the concentration of the perfluorinated compound is 0.1-20 μM, it is separated and removed using an ultrafiltration system, the pore size of which includes, but is not limited to, 3-300 kDa.

[0027] The beneficial effects of this invention are reflected in:

[0028] This invention provides a probe molecule for the visual dual-mode detection of perfluorinated compounds, made from a cationic polythiophene derivative. This probe enables rapid, quantitative, and specific detection of perfluorinated compounds. It detects the perfluorinated compounds by utilizing the color and fluorescence intensity changes in the solution caused by the reaction between polythiophene and the perfluorinated compounds, and removes the resulting polythiophene derivative-perfluorinated compound complex using a removal system. The detection method of this invention exhibits high specificity and sensitivity, supports visual detection, has a wide range of applications, and can achieve simultaneous dual-mode detection and removal of perfluorinated compounds in water. Attached Figure Description

[0029] Figure 1 The image shows the effect of detecting PFOS using the probe molecule of formula (Ⅰ) with different R1 substituents in Example 1 of the present invention. A) shows the structural differences between different PT names and different R1 substituents; B) shows the schematic diagram of colorimetric and absorption spectral sensing; C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0030] Figure 2 The image shows the effect of detecting PFOS using the probe molecule of formula (Ⅰ) with different carbon chain lengths m in Example 1 of the present invention. A) shows the differences between different PT names and the lengths of different carbon chains m; B) shows the schematic diagram of colorimetric and absorption spectral sensing; C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0031] Figure 3 In Embodiment 1 of the present invention, different R values ​​are changed. #The effect diagram of the detection of PFOS by the substituent formula (Ⅰ) probe molecule, A) shows the different PT names and different R # A) Structural differences of substituents; B) Schematic diagram of colorimetric and absorption spectroscopy sensing; C) Schematic diagram of fluorescence colorimetric and fluorescence spectroscopy sensing.

[0032] Figure 4 The following is a diagram showing the effect of detecting PFOS using probe molecules (II) with different structures in Example 1 of this invention. A) shows the differences between different PT names and different monomers and polymerization ratios; B) shows the schematic diagram of colorimetric and absorption spectral sensing; C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0033] Figure 5 The following is a graph showing the colorimetric sensing effect of the probe molecule and PFOS in Example 2 of the present invention: A) a graph showing the relationship between PFOS concentration and PT absorption spectrum changes; B) a graph showing the relationship between PFOS concentration and PT absorbance ratio changes; the inset shows the linear relationship between absorbance ratio and PFOS concentration; C) a colorimetric visualization of the probe molecule and different concentrations of PFOS; D) a graph showing the changes in R / (G+B) values ​​of the probe molecule with different concentrations of PFOS.

[0034] Figure 6 This is a colorimetric diagram of the specific recognition of perfluorinated compounds by the probe molecule in Example 2 of the present invention. A) Ultraviolet absorption spectra after different ions react with the probe molecule; B) Absorbance ratio A after different ions react with PT. 505nm / A 405nm Change diagram (numbers in the diagram: 1PT, 2SO4) 2- 3CO3 2- 4HCO3 - 5Cl - 6PO4 3- 7NO2 - 8BrO3 - 9F - 10K + 11Ca 2+ (12SDS, 13Tween-20, 14CTAB, 15PFOS, 16PFOA, the same below); C) Color changes of different ions after reacting with PT.

[0035] Figure 7 The following is a graph showing the fluorescence sensing effect of the probe molecule and PFOS in Example 3 of this invention: A) is a graph showing the relationship between changes in PFOS concentration and changes in PT fluorescence emission spectrum; B) is a graph showing the ratio of PFOS concentration to fluorescence intensity FI. 600nm / FI 535nmA) Relationship diagram; C) Fluorescence visualization of probe molecules and different concentrations of PFOS under blue light irradiation; D) Changes in R / (G+B) values ​​of different concentrations of PFOS and probe molecules under blue light irradiation.

[0036] Figure 8 The following are fluorescence images of the probe molecules specifically recognizing perfluorinated compounds in Example 3 of this invention: A) Fluorescence spectra of different ions after reacting with the probe molecules; B) Changes in fluorescence quenching rates of different ions after reacting with PT (in the figure: 1PT, 2SO42-, 3CO32-, 4HCO3-, 5Cl-, 6PO43-, 7NO2-, 8BrO3-, 9F-, 10K+, 11Ca2+, 12SDS, 13Tween-20, 14CTAB, 15PFOS, 16PFOA, the same below); C) Fluorescence intensity ratio FI of different ions after reacting with PT. 575nm / FI 535nm The fluorescence color change diagram (D) shows the reaction of different ions with PT under 420nm blue light excitation.

[0037] Figure 9 In Example 4 of this invention, the detection effect of probe molecules on different perfluorinated compounds is shown in the following diagrams: A) is the ultraviolet absorption spectrum of different perfluorinated compounds after reacting with probe molecules; B) is the absorbance ratio of different perfluorinated compounds after reacting with probe molecules. 525nm / A 405nm Variation diagram (numbered in the diagram: 1PT, 2PFBA, 3PFHxA, 4PFOA, 5PFDoA, 6PFMS, 7PFBS, 8PFHxS, 9PFOS).

[0038] Figure 10 The diagram shows the effect of the probe molecules on PFOS removal in Example 5 of the present invention. AB represents precipitation removal (Figure A: flowchart, Figure B: effect of PFOS removal by precipitation); CD represents ultrafiltration removal of PFOS (Figure C: flowchart, Figure D: effect of PFOS removal by ultrafiltration). Detailed Implementation

[0039] To enhance understanding of the present invention, the embodiments described below with reference to the accompanying drawings are further detailed. These embodiments are only used to illustrate the technical solutions of the present invention more clearly, and are not intended to limit the present invention.

[0040] First, the structure of the cationic polythiophene derivative provided by the present invention is shown in the figure:

[0041]

[0042] Formula (I) is a homopolymer structure, where R1 is H or CH3; R2 is O or CH2; R3 is an alkyl group or its isomers (methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl) with an integer number of carbon atoms between 1 and 6; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and the weight-average molecular weight of the polythiophene derivative is between 0.3 and 50,000.

[0043] Equation (II) can be formed by connecting each thiophene unit through positions 2 and 5 to form a conjugated main chain, the structure of which is shown below:

[0044]

[0045] Formula (II) is a copolymer structure, where R1 is H or CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R1#, R2#, R3#, R4# are selected from the R# substituents in Formula (I) above, wherein R3 is an alkyl group and its isomers (methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl); R4 is H or CH3; and satisfies R1#≠R2#≠R3#≠R4#; n1, n2, n3, n4 are integers between 1 and 500, and the average molecular weight of the polythiophene derivative is between 0.3 million and 100,000.

[0046] The cationic polythiophene derivatives with structures shown in formulas (I) and (II) exhibit good water solubility and significant specificity in detection, enabling sensitive detection of perfluorinated compounds. The compounds with structures shown in formulas (I) and (II) display different conformations and aggregation states in solution in response to external stimuli, thereby causing changes in their optical properties.

[0047] Second, the present invention provides a probe molecule for visual dual-mode detection of perfluorinated compounds, which can be used for rapid, quantitative and specific detection of perfluorinated compounds;

[0048] The types of perfluorinated compounds to be detected and removed include, but are not limited to, short-chain perfluoroalkyl carboxylic acids (perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acids (perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acids (trifluoromethylsulfonic acid TFMS, perfluorobutylsulfonic acid PFBS, perfluorohexylsulfonic acid PFHxS), and long-chain perfluoroalkyl sulfonic acids (perfluorooctylsulfonic acid PFOS).

[0049] To achieve the purpose of detecting perfluorinated compounds;

[0050] The steps for rapid detection of perfluorinated compounds using probe molecules as described in this invention (taking PFOS as an example):

[0051] (1) Dissolve the aforementioned cationic polythiophene derivative in water to prepare probe molecules;

[0052] (2) Add the probe molecules obtained in step (1) into a quartz cuvette to obtain the detection reagent;

[0053] (3) PFOS standard solution was gradually added to a cuvette, and the changes in its ultraviolet-visible absorption spectrum and fluorescence spectrum were measured.

[0054] (4) Analyze the relationship between absorbance ratio and PFOS concentration and the relationship between fluorescence intensity ratio and PFOS concentration to perform quantitative and specific detection of PFOS in solution.

[0055] The probe molecule described in this invention can detect PFOS concentrations in the range of 0.1-5 × 10⁻⁶. 5 The concentration of the probe molecule is in the range of 0.1-100 μM, preferably 50 μM.

[0056] The reaction conditions include: (1) the volume of the reaction system is 200-3000 μL, preferably 2000 μL; (2) the reaction temperature of the reaction system is 4-40℃, preferably 25℃; (3) the pH value of the reaction system is 4-12, preferably pH=7; (4) the concentration of the polythiophene derivative is 10-150 μM, preferably 50 μM; (5) the mixing reaction time is 1-10 min, preferably 5 min.

[0057] Third, the present invention provides a method for removing perfluorinated compounds from water in order to achieve the purpose of removing perfluorinated compounds;

[0058] The steps for removing perfluorinated compounds using probe molecules as described in this invention (taking PFOS as an example):

[0059] (1) Dissolve Formula I / Formula II in ultrapure water to obtain a probe molecule solution;

[0060] (2) The probe molecules prepared in step (1) are added to water containing PFOS for reaction;

[0061] (3) After the reaction is complete, the solution is added to the removal system for separation and removal. The removed sample is analyzed to obtain the efficiency of the probe molecule in removing PFOS.

[0062] The removal reaction described in this invention can be performed using different systems for separation and removal:

[0063] (1) Precipitation removal: The preferred molar ratio of probe molecules to PFOS is 1:1; precipitation is used to separate and remove PFOS when the concentration is 20-200 μM.

[0064] (2) Ultrafiltration removal, preferably using an ultrafiltration system for separation and removal when the PFOS concentration is 0.1-20 μM; the pore size of the ultrafiltration system includes, but is not limited to, 3-300 kDa;

[0065] Fourth, the types of perfluorinated compounds to be detected and removed include, but are not limited to, short-chain perfluoroalkyl carboxylic acids (perfluorobutyric acid PFBA, perfluorohexanoic acid PFHxA), long-chain perfluoroalkyl carboxylic acids (perfluorooctanoic acid PFOA, perfluorododecanoic acid PFDoA), short-chain perfluoroalkyl sulfonic acids (trifluoromethylsulfonic acid TFMS, perfluorobutylsulfonic acid PFBS, perfluorohexylsulfonic acid PFHxS), and long-chain perfluoroalkyl sulfonic acids (perfluorooctylsulfonic acid PFOS).

[0066] Example 1: Structural features of cationic polythiophene probes for identifying perfluorinated compounds

[0067] Homopolymers PT1-PT17 and PT29, and copolymers PT18-PT20 and PTC-PTF were synthesized with reference to the literature (Chinese Patent: CN118480172A).

[0068] The prepared probe molecules with different structures (Formula I and Formula II) were added into cuvettes to obtain detection reagents for detecting perfluorinated compounds (taking PFOS as an example);

[0069] The changes in UV-Vis absorption spectrum, fluorescence spectrum, visual color change, and fluorescence color change were measured by adding PFOS standard solution to a cuvette.

[0070] like Figure 1 As shown, after adjusting the structure of the R1 substituent in the molecule of formula (Ⅰ), the probe molecule has a signal output response to PFOS, specifically manifested as: changes in the UV-Vis absorption spectrum and color, fluorescence quenching accompanied by changes in fluorescence color, indicating that the synthesized probe molecule (Ⅰ) with the 4-position R1 structure of thiophene being CH3 or H can be used for UV / fluorescence dual-mode detection of PFOS.

[0071] like Figure 2 As shown, after adjusting the length of the m carbon chain in the (Ⅰ) molecule, the probe molecules all showed good signal output response to PFOS, indicating that the synthesized probe molecules of formula (Ⅰ) with m carbon chain lengths of 1-15 can be used for UV / fluorescence dual-mode detection of PFOS.

[0072] like Figure 3 As shown, in the regulatory formula (Ⅰ) molecule, R # After the substituents were added, the probe molecules all showed good signal output response to PFOS, indicating that the synthesized probe molecules with the formula (Ⅰ)R #Substituents such as quaternary ammonium salts (methyl, ethyl, propyl, butyl, hexyl), 1-methylimidazole, and 1,2-dimethylimidazole structures can all be used for UV / fluorescence dual-mode detection of PFOS.

[0073] like Figure 4 As shown, after adjusting the structure and polymerization ratio of the monomer in formula (II), the probe molecules all showed good signal output response to PFOS, indicating that the synthesized probe molecule (II) can be used for UV / fluorescence dual-mode detection of PFOS after adjusting the structure and polymerization ratio of the monomer.

[0074] Example 2: Cationic polythiophene probe for colorimetric and ultraviolet absorption spectroscopy detection of perfluorinated compounds

[0075] 1. Quantitative Detection of Perfluorinated Compounds by Colorimetric and UV-Vis Absorption Spectroscopy

[0076] The probe stock solution was dissolved in ultrapure water to obtain the probe molecule solution. 2 mL of the obtained probe molecule solution was added to a cuvette of uniform volume as a reagent for detecting PFOS.

[0077] The UV-Vis absorption spectrum of the probe molecule was scanned, and then a certain concentration of PFOS standard solution was gradually added to the colorimetric cell. After mixing thoroughly, the UV-Vis absorption spectra were measured, and the peak values ​​at 400 nm and 505 nm were read. The results are as follows: Figure 5 show, Figure 5 A indicates that the absorbance of the aforementioned probe molecule at 400 nm gradually decreases with the addition of PFOS, while the absorbance at 505 nm gradually increases. Figure 5 B shows the relationship between the absorbance ratio and the change in PFOS concentration; as the PFOS concentration increases, the absorbance ratio A... 505nm / A 400nm Gradual increase allows for quantitative detection within the 0-35 μM range with good linearity (R0). 2 =0.99712). Based on the method for calculating the detection limit, the detection limit of the probe molecule for PFOS is 75.93 nmol / L.

[0078] Different concentrations of PFOS standard solutions were added to vials, mixed well, and photographed under natural indoor light. The RGB values ​​of each vial were then extracted using the software Color Grab. Figure 5 The results showed that as the PFOS concentration increased, the solution color of the probe molecule gradually changed from yellow to red, with a visual detection limit of 2.5 μmol / L. The R / (G+B) value obtained by the software showed a linear relationship with the PFOS concentration, and the correlation coefficient Rc was [value missing]. 2 The value was 0.98977, and the detection limit was 2.49 μmol / L.

[0079] 2. Specificity of colorimetric and ultraviolet spectroscopy for detecting perfluorinated compounds

[0080] Select common ions in water (SO4) 2- CO3 2- HCO3 - Cl - PO4 3- NO2 - BrO3 - F - K + Ca 2+ Surfactants (SDS, Tween-20, CTAB) were used as interfering substances for the detection of perfluorinated compounds (PFOS, PFOA), and UV-Vis absorption spectra were measured under the same test conditions. The ratio of the absorbance of the probe before and after the addition of the interfering substances was used as a parameter to measure the degree of influence of the probe on the analyte.

[0081] like Figure 6 As shown, the results indicate that when different ions are added to the probe molecule, only the addition of perfluorinated compounds (PFOS, PFOA) causes the solution to turn orange or red, with an absorbance ratio A. 505nm / A 405nm The concentration of ions is significantly higher than that of other ions, thus the probe molecules can specifically detect perfluorinated compounds.

[0082] Example 3: Cationic polythiophene probes for fluorescence colorimetry and fluorescence spectroscopy sensing of perfluorinated compounds

[0083] 1. Quantitative Detection of Perfluorinated Compounds by Fluorescence Colorimetry and Fluorescence Spectroscopy

[0084] The probe stock solution was dissolved in ultrapure water to obtain the probe molecule solution. 2 mL of the obtained probe molecule solution was added to a colorimetric cell with uniform volume as a reagent for detecting PFOS.

[0085] PFOS was added dropwise, and the fluorescence spectra were measured separately. The results are as follows: Figure 7 As shown in Figure A, the probe molecule exhibits an emission peak at 535 nm under 420 nm excitation. With the addition of PFOS, the emission peak of the aforementioned probe molecule gradually decreases, while the peak value at 600 nm increases. Figure 7 As shown in Figure B, the addition of PFOS increases the fluorescence intensity ratio FI. 600nm / FI 535nm The detection limit is continuously increasing. Based on the calculation method for the detection limit, the detection limit of the probe molecule for PFOS is 13.69 nmol / L.

[0086] Different concentrations of PFOS standard solutions were added to vials, mixed thoroughly, and photographed under blue light excitation. The RGB values ​​of each vial were extracted using Color Grab software. Figure 7 The results showed that the fluorescence color of the probe molecule solution gradually turned red with increasing PFOS concentration, and the detection limit was 5 μmol / L. The R / (G+B) value obtained by the software showed a linear relationship with the PFOS concentration, with a correlation coefficient R. 2 =0.99166, detection limit 0.41 μmol / L.

[0087] 2. Specificity of fluorescence colorimetric and fluorescence spectral sensing for detecting perfluorinated compounds

[0088] Select common ions in water (SO4) 2- CO3 2- HCO3 - Cl - PO4 3- NO2 - BrO3 - F - K + Ca 2+ Surfactants (SDS, Tween-20, CTAB) were used as interfering substances for the detection of perfluorinated compounds (PFOS, PFOA), and fluorescence spectra were measured under the same test conditions. The fluorescence quenching rate ((I0-I) / I0) and the fluorescence intensity ratio FI before and after the addition of the interfering substances were compared. 575nm / FI 535nm As a parameter to measure the degree of influence of the probe on the analyte.

[0089] like Figure 8 As shown in D, the probe molecule exhibits yellow fluorescence under 420nm blue light irradiation. The addition of a perfluorinated compound results in significant fluorescence quenching and a gradual change in fluorescence color from yellow to red, which can be observed with the naked eye. However, the addition of other ions does not cause significant quenching or color change in the fluorescence of the probe molecule.

[0090] Fluorescence spectroscopy was performed under the same testing conditions. The fluorescence quenching rate of the added perfluorinated compound significantly increased compared to other ions. The ratio of the red-shifted emission peak after ion addition to the emission peak of the polythiophene derivative can also be used as a parameter to measure the influence of the probe on the perfluorinated compound. Results are as follows... Figure 8 As shown in BC, the aforementioned probe molecules exhibit good specificity for perfluorinated compounds after interacting with different ions.

[0091] Example 4: Detection of different perfluorinated compounds using a polythiophene probe

[0092] To demonstrate the general applicability of the PFOS detection method to the detection of perfluorinated compounds containing different perfluoroalkyl chain lengths and functional groups, the responses of the aforementioned polythiophene probe to other perfluorinated compounds were investigated, and the UV absorption spectra of each reaction solution under the same conditions were recorded. The selected perfluorinated compounds included the PFCA series (heptafluorobutyric acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorododecanoic acid (PFDoA)) and the PFSA series (trifluoromethanesulfonic acid (TFMS), perfluorobutanesulfonic acid (PFBS), perfluorohexanesulfonic acid (PFHxS), and perfluorooctanesulfonic acid (PFOS)), representing carbon chain lengths from C4 to C12 and C1 to C8, respectively.

[0093] The probe stock solution was dissolved in ultrapure water to obtain the probe molecular solution. 2 mL of the obtained probe molecular solution was added to a uniformly sized colorimetric cell as the reagent for detecting perfluorinated substances. Under the same conditions, UV-Vis absorption spectroscopy was performed, and the absorbance value at 525 nm was compared with the absorbance value at 405 nm. A 525nm / A 405nm As a parameter to measure the degree of response of probe molecules to the analyte;

[0094] The results are as follows Figure 9 As shown, Figure 9 A indicates that after the addition of a perfluorinated compound, the absorbance of the probe molecule decreased at 405 nm, while the absorbance increased at 525 nm. Figure 9 B displays the absorbance ratio of A. 525nm / A 405nm The relationship with different perfluorinated compounds was investigated. The results confirmed the general applicability of the detection of perfluorinated compounds containing different perfluoroalkyl chain lengths and functional groups. Furthermore, within the same series of perfluorinated compounds, the longer the perfluoroalkyl chain length, the better the detection effect; the detection effect of the PFSA series was significantly better than that of the PFCA series.

[0095] Example 5: Removal of perfluorinated compounds by cationic polythiophene probe molecules

[0096] 1. Precipitation to remove perfluorinated compounds

[0097] For water samples contaminated with perfluorinated compounds, precipitation can be used for removal. Probe molecules are added; due to PFOS causing probe molecule aggregation, precipitation occurs upon standing, and the precipitate is visible to the naked eye. After the precipitate has been left to stand for 30 minutes, it is centrifuged, and the supernatant is collected. The supernatant is diluted 5 times, and probe molecules are added again. A UV-Vis absorption spectrum scan is performed, and the ratio of the absorbance value at 505 nm to the absorbance value at 400 nm is used as an important parameter to measure the removal effect.

[0098] The results are as follows Figure 10As shown in Figure A, the PFOS content in the supernatant decreased significantly with the increase of probe molecule concentration. The removal rate of PFOS by the probe molecules reached 96.13% based on the absorbance ratio, and the range of PFOS removal by precipitation was 20-200 μM.

[0099] 2. Ultrafiltration for the removal of perfluorinated compounds

[0100] The probe molecules were mixed with a trace amount of PFOS (1 μM) and added to an ultrafiltration tube. The tube was centrifuged at 5000 g for 10 min. The permeate layer was taken and concentrated to 2 mL by evaporation. After concentration, the probe molecules were added again and the UV-Vis absorption spectrum was scanned. The absorbance value at 505 nm was read and the absorbance value at 400 nm was compared as an important parameter to measure the removal effect.

[0101] The results are as follows Figure 10 As shown in Figure B, the absorbance ratio of PFOS in the permeate decreased significantly after the addition of probe solution (PT). This method can effectively remove low concentrations of PFOS in water. The range of PFOS removed by ultrafiltration is 0.1-20 μM, with a removal rate of 99.9%.

[0102] The above embodiments demonstrate that the polythiophene derivative developed in this invention has the characteristics of high sensitivity and good stability. At the same time, it can be used as an adsorbent to remove perfluorinated compounds, and can be applied as a simple and rapid method for the simultaneous detection and removal of perfluorinated compounds.

[0103] Matters not covered in this invention are common knowledge. The above embodiments are only for illustrating the technical concept and features of this invention, and are intended to enable those skilled in the art to understand the content of this invention and implement it accordingly. They should not be construed as limiting the scope of protection of this invention. All equivalent changes or modifications made in accordance with the spirit and essence of this invention should be covered within the scope of protection of this invention.

Claims

1. A method for detecting perfluorinated compounds using cationic polythiophene derivatives, characterized in that: The structures of the cationic polythiophene derivatives are shown in formulas (I) and (II): Equation (I) Formula (I) is a homopolymer structure, where R1 is CH3; R2 is O or CH2; R3 is an alkyl group or its isomer with an integer number of carbon atoms between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and such that the weight-average molecular weight of the polythiophene derivative is between 0.3 million and 50,000; Equation (II) consists of a conjugated main chain formed by connecting each thiophene unit through positions 2 and 5, and its structural formula is shown below: Formula (II) Formula (II) is a copolymer structure, where R1 is CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R 1# , R 2# , R 3# ,R 4# R is selected from formula (Ⅰ) above. # Substituents, wherein R3 is an alkyl group or its isomer with an integer number of carbons between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; and satisfy R 1# ≠ R 2# ≠ R 3# ≠ R 4# n1, n2, n3, n4 are integers between 1 and 500, and the average molecular weight of the polythiophene derivative is between 0.3 million and 100,000. The detection method includes the following steps: (1) The cationic polythiophene derivatives shown in formula (Ⅰ) and formula (Ⅱ) are dissolved in water to prepare probe molecules; (2) Add the probe molecules obtained in step (1) into a quartz cuvette to obtain the detection reagent; (3) The standard solution of perfluorinated compound was gradually added to the cuvette, and the changes in its ultraviolet-visible absorption spectrum and fluorescence spectrum were measured. (4) Analyze the relationship between absorbance ratio and concentration of specific perfluorinated compounds and the relationship between fluorescence intensity and concentration of specific perfluorinated compounds, and perform quantitative and specific detection of specific perfluorinated compounds in solution; In the above detection system, the concentration of cationic polythiophene derivatives is 0.1-100 μM, the reaction volume is 200-3000 μL, the reaction pH is 4-14, the reaction temperature is 4-40 ℃, and the reaction system is ultrapure water and HEPES buffer solution.

2. A method for removing perfluorinated compounds using cationic polythiophene derivatives, characterized in that: The structures of the cationic polythiophene derivatives are shown in formulas (I) and (II): Equation (I) Formula (I) is a homopolymer structure, where R1 is CH3; R2 is O or CH2; R3 is an alkyl group or its isomer with an integer number of carbon atoms between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; m is an integer between 0 and 15; M is Cl or Br; n is a positive integer, and such that the weight-average molecular weight of the polythiophene derivative is between 0.3 million and 50,000; Equation (II) consists of a conjugated main chain formed by connecting each thiophene unit through positions 2 and 5, and its structural formula is shown below: Formula (II) Formula (II) is a copolymer structure, where R1 is CH3; R2 is O or CH2; m is an integer between 0 and 15; M is Cl or Br; R 1# , R 2# , R 3# ,R 4# R is selected from formula (Ⅰ) above. # Substituents, wherein R3 is an alkyl group or its isomer with an integer number of carbons between 1 and 6: methyl, ethyl, propyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, isohexyl; R4 is H or CH3; and satisfy R 1# ≠ R 2# ≠ R 3# ≠ R 4# n1, n2, n3, n4 are integers between 1 and 500, and the average molecular weight of the polythiophene derivative is between 0.3 million and 100,000. The removal method includes the following steps: (1) Dissolve the cationic polythiophene derivatives shown in formula (Ⅰ) / formula (Ⅱ) in ultrapure water to obtain a probe molecule solution; (2) The probe molecules prepared in step (1) are added to water containing perfluorinated compounds for reaction; (3) After the reaction is complete, the solution is added to the removal system for separation and removal. The removed sample is analyzed to obtain the efficiency of the probe molecule in removing the specific perfluorinated compound. When the concentration of perfluorinated compounds is between 20 and 200 μM, precipitation is used for separation and removal. When the concentration of perfluorinated compounds is between 0.1 and 20 μM, an ultrafiltration system is used for separation and removal, with a pore size of 3-300 kDa.

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