A cationic polythiophene derivative for detecting and removing an anionic surfactant and a method

Abstract

The present application relates to the technical field of pollutant detection, in particular to a cationic polythiophene derivative for detecting and removing anionic surfactant and a method thereof. The probe molecule made of the cationic polythiophene derivative provided by the present application can be combined with anionic surfactant to cause the change of solution color and optical property, and can directly perform specific and sensitive colorimetric and fluorescent sensing on anionic surfactant. Meanwhile, the removal of anionic surfactant in water can be realized by using the aggregation of molecular structure after the combination of the probe molecule and anionic surfactant. The probe molecule developed by the present application has the advantages of stable structure, good water solubility, rapid response and the like, and can realize the synchronous dual-mode detection and removal of anions in water.

Description

Technical Field

[0001] This invention relates to the field of pollutant detection technology, specifically to a method for detecting and removing cationic polythiophene derivatives of anionic surfactants. Background Technology

[0002] Anionic surfactants possess strong detergency, foaming, dispersing, and emulsifying abilities, and are widely used in the production of industrial detergents. However, anionic surfactants pose significant hazards. When indiscriminately discharged into natural water bodies, they are difficult to degrade naturally in the environment, adversely affecting aquatic life. The toxicity of anionic surfactants can also enter the human body through the food chain, affecting the activity of various enzymes and reducing the body's resistance. Furthermore, anionic surfactants can synergistically interact with other toxic chemicals in wastewater, and when ingested through drinking water, they can stimulate weight gain and accelerate cholesterol synthesis in the liver. Therefore, detecting anionic surfactants in environmental water samples has become a fundamental task of environmental monitoring. The national standard GB5479—2022, "Standards for Drinking Water Quality," implemented on April 1, 2023, stipulates a residual limit of 0.3 mg / L for anionic synthetic detergents in water to ensure the safety of drinking water resources and food.

[0003] Currently, methods developed for detecting anionic surfactants include flow injection, two-phase titration, and high-performance liquid chromatography. However, these methods are generally cumbersome to operate, use highly toxic reagents, and require large quantities, which can cause harm to human health and the environment. They are not suitable for the current demand for rapid, green, and environmentally friendly detection.

[0004] Water-soluble polythiophene (PTA) is sensitive to external stimuli such as thermal or optical treatment, changes in solvent composition, and the introduction of chemical and biochemical targets due to its chain conformation and photophysical properties. It also exhibits good thermal stability and biocompatibility, making it suitable for use in optical devices. Researchers have applied PTA to the detection of anionic surfactants. Yao et al. (Chem. Commun., 2010, 46, 8639) induced the aggregation of PTA-NS in HEPES buffer using aromatic 2-naphthalenesulfonate (NS). Upon addition of anionic surfactant, the aggregates dissociated, and this complex can serve as a promising colorimetric probe for anionic surfactant detection. An et al. (Soft Matter 2011, 7, 6873-6877) prepared anionic dyes (HPTS), which were then introduced into an aqueous solution of PTA to form a complex. This complex was then used as a colorimetric and fluorescent dual-mode probe for detecting anionic surfactants, demonstrating good selectivity and sensitivity.

[0005] In the above method, after preparing water-soluble polythiophene, other components need to be introduced to aggregate into a complex before it can be used for the detection of anionic surfactants. The steps are cumbersome and inconvenient to use. Summary of the Invention

[0006] This invention aims to address the lack of highly sensitive selective recognition materials for anionic surfactants, and provides a method for detecting and removing cationic polythiophene derivatives of anionic surfactants.

[0007] The technical solution of the present invention is as follows:

[0008] A cationic polythiophene derivative for detecting and removing anionic surfactants, with structures shown in formulas (I) and (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 anionic surfactants detected and removed include alkyl carboxylic acids: sodium dodecyl carboxylate SDC, alkyl sulfonic acids: sodium octyl sulfonate OS, alkyl benzene sulfonic acids: sodium dodecyl benzene sulfonate SDBS, and alkyl sulfuric acids: sodium octyl sulfate SOS and sodium dodecyl sulfate SDS.

[0015] A method for detecting anionic surfactants using the 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 anionic surfactant 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 the concentration of specific anionic surfactant and the relationship between fluorescence intensity and the concentration of specific anionic surfactant to perform quantitative and specific detection of anionic surfactant 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 anionic surfactants 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 anionic surfactant to carry out the 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 corresponding anionic surfactant.

[0025] Furthermore, when the concentration of the anionic surfactant 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.

[0026] The beneficial effects of this invention are reflected in:

[0027] The probe molecules made from cationic polythiophene derivatives provided by this invention can bind to anionic surfactants, causing changes in the color and optical properties of the solution. This allows for direct, specific, and sensitive colorimetric and fluorescence sensing of anionic surfactants. Simultaneously, the molecular aggregation of the probe molecules after binding with the anionic surfactants achieves the removal of anionic surfactants from water. The probe molecules developed in this invention possess advantages such as structural stability, good water solubility, and rapid response, enabling simultaneous dual-mode detection and removal of anions in water. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the principle of cationic polythiophene detection of anionic surfactants in Example 1 of the present invention.

[0029] Figure 2 The image shows the effect of the probe molecule (Ⅰ) detecting SDS when R1 of the depolymerization probe in Example 1 of the present invention is CH3 or H. Column A) shows the different PT names and the differences of different R1; column B) shows the schematic diagram of colorimetric and absorption spectral sensing; column C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0030] Figure 3 The image shows the effect of the depolymerization probe of Formula (Ⅰ) in Example 1 of the present invention on the detection of SDS by changing the length of different carbon chain m. Column A) shows the differences between different PT names and the length of different carbon chain m; column B) shows the schematic diagram of colorimetric and absorption spectral sensing; column C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0031] Figure 4 The different R values ​​of the depolymerization probe in Embodiment 2 of the present invention # The effect diagram of the detection of SDS by the substituent formula (Ⅰ) probe molecule, A) shows the different PT names and different R # A) Differences in the length of substituents; B) Schematic diagram of colorimetric and absorption spectroscopy sensing; C) Schematic diagram of fluorescence colorimetric and fluorescence spectroscopy sensing.

[0032] Figure 5 The following is a diagram showing the effect of detecting SDS using depolymerization probes of different structures (II) in Example 2 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 6The following are the dual-mode sensing effects of the depolymerized probe molecule and SDS in Example 2 of this invention: A) Relationship between changes in SDS concentration and changes in the absorption spectrum of the probe molecule; B) Linear relationship between SDS concentration and the ratio of absorbance of the probe molecule; C) Colorimetric visualization of the probe molecule and SDS at different concentrations; D) Changes in G value of the probe molecule and SDS at different concentrations under fluorescent light irradiation; E) Relationship between changes in SDS concentration and changes in the emission spectrum of the probe molecule; F) Relationship between fluorescence intensity and increase in SDS concentration (where I0 is the initial fluorescence intensity of the probe molecule at 600 nm, and I is the fluorescence intensity at 600 nm after the addition of SDS).

[0034] Figure 7 In Example 2 of this invention, the effect of depolymerization probe molecules specifically recognizing anionic surfactants is shown in Figure A). Figure A) shows the color changes after different ions react with the depolymerization probe molecules (numbers in the figure: 1PT, 2Cl). - 3ClO3 - 4CO3 2- 5HCO3 - 6NO3 - 7SO4 2- 8F - 9PO4 3- 10HPO4 2- 11H2PO4 - 12Tween-20, 13Triton X-100, 14CTAB, 15SDS, 16SDBS (the same below); B) The ratio of absorbance after different ions react with depolymerized probe molecules. 392nm / A 535nm A) The fluorescence color change graph after different ions react with depolymerized probe molecules under 470nm blue light excitation; C) The fluorescence intensity ratio I after different ions react with depolymerized probe molecules. 550nm / I 610nm The change graph.

[0035] Figure 8 The image shows the effect of the aggregation probe of formula (Ⅰ) with different R3 substituents in Example 3 of the present invention on the detection of SDS. A) shows the different PT names and the differences of different R3s; B) shows the schematic diagram of colorimetric and absorption spectral sensing; C) shows the schematic diagram of fluorescence colorimetric and fluorescence spectral sensing.

[0036] Figure 9 The following is a diagram showing the effect of detecting SDS using aggregated probes of different structures (II) in Example 3 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.

[0037] Figure 10 The following are the dual-mode sensing effects of aggregated probe molecules and SDS UV-Vis absorption and fluorescence in Example 3 of this invention: A) Relationship between changes in SDS concentration and changes in the absorption spectrum of probe molecules; B) Linear relationship between SDS concentration and the absorbance ratio of probe molecules; C) Colorimetric visualization of probe molecules and SDS at different concentrations; D) Changes in R / (G+B) values ​​of probe molecules at different concentrations under fluorescent light irradiation; E) Relationship between changes in SDS concentration and changes in the emission spectrum of probe molecules; F) Relationship between fluorescence intensity and increasing SDS concentration.

[0038] Figure 11 In Example 3 of this invention, the effect of aggregated probe molecules specifically recognizing anionic surfactants is shown in Figure A). Figure A) shows the color changes after different ions react with aggregated probe molecules (numbers in the figure: 1PT, 2Cl). - 3ClO3 - 4CO3 2- 5HCO3 - 6NO3 - 7SO4 2- 8F - 9PO4 3- 10HPO4 2- 11H2PO4 - 12Tween-20, 13Triton X-100, 14CTAB, 15SDS, 16SDBS (the same below); B) The ratio of absorbance after different ions react with aggregated probe molecules A 525nm / A 405nm A) Fluorescence color changes after different ions react with aggregated probe molecules under 470nm blue light excitation; B) Fluorescence intensity ratio I after different ions react with aggregated probe molecules. 655nm / I 520nm The change graph.

[0039] Figure 12 In Example 4 of this invention, the detection effect of probe molecules on different anionic surfactants is shown in the following diagrams: A) is the absorption spectrum of different anionic surfactants reacting with probe molecules; B) is the absorbance ratio of different anionic surfactants reacting with probe molecules. 525nm / A 405nm The change graph (numbered as follows: 1PT, 2OS, 3SOS, 4SDC, 5SDBS, 6SDS)

[0040] Figure 13 The effect of probe molecules on the removal of anionic surfactants by ultrafiltration (UF) in Example 5 of this invention is shown in the figure. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0042] First, the structure of the cationic polythiophene derivative provided by the present invention is shown in the figure:

[0043]

[0044] 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.

[0045] Equation (II) consists of thiophene units connected at positions 2 and 5 to form a conjugated main chain, the structure of which is shown below:

[0046]

[0047] 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 (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.

[0048] The cationic polythiophene derivatives with structures shown in formulas (I) and (II) exhibit good water solubility and show significant specificity in detection, enabling sensitive detection of anionic surfactants. Based on their conformation and aggregation state in solution, the polythiophene derivatives with the structures shown above can be classified into two types: depolymerized and aggregated.

[0049] Figure 1 This is a schematic diagram illustrating the detection of anionic surfactants by probe molecules. Figure 1As shown in Figure A, the depolymerized polythiophene probe is purplish-red and exhibits red fluorescence. Upon addition of an anionic surfactant, the aggregates formed by the probe molecules in water are dispersed, and the solution color correspondingly changes from purplish-red to yellow. Figure 1 As shown in Figure B, the aggregated polythiophene probe is pale yellow with yellow fluorescence and is uniformly dispersed in aqueous solution. Upon addition of an anionic surfactant, a cationic polythiophene-anionic surfactant complex is formed, and the solution color changes from yellow to purplish-red. Both types of probe molecules exhibit significant fluorescence changes in the presence of anionic surfactants. Highly sensitive and specific qualitative and quantitative detection of anionic surfactants can be achieved by analyzing changes in absorption and fluorescence spectra and their intensities.

[0050] Second, this invention provides a visual dual-mode detection probe molecule for anionic surfactants, which can be used for rapid, quantitative, and specific detection of anionic surfactants; in order to achieve the purpose of detecting anionic surfactants;

[0051] The steps for rapid detection of anionic surfactants using probe molecules as described in this invention (taking SDS as an example):

[0052] (1) Dissolve 5 μmol of probe in 100 mL of ultrapure water to obtain a probe molecule solution;

[0053] (2) Add the probe obtained in step (1) into a cuvette with uniform volume to obtain the detection reagent;

[0054] (3) After reacting the SDS standard solution with the reagent obtained in step (2), measure the changes in its ultraviolet-visible absorption spectrum and fluorescence spectrum. The linear relationship between the peak changes and the SDS concentration values ​​can be used for quantitative analysis.

[0055] (4) After adding SDS to the detection reagent in step (2), the absorbance of the depolymerized probe molecules gradually decreases at 537 nm and gradually increases at 395 nm. At the same time, the fluorescence of the probe molecules is enhanced and the characteristic absorption peak undergoes a blue shift. The absorbance of the aggregated probe molecules gradually decreases at 405 nm and gradually increases at 535 nm. At the same time, the fluorescence of the probe molecules is quenched and the characteristic absorption peak undergoes a red shift. The overall detection time is less than 10 s.

[0056] The probe molecule described in this invention can detect SDS 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.

[0057] The reaction conditions include: (1) the volume of the reaction system is 200-3000 μL, and the reaction volume is more preferably 2000 μL; (2) the reaction temperature of the reaction system is 4-40℃, and the reaction temperature is more preferably 25℃; (3) the pH value of the reaction system is 4-14, and the pH value is more preferably pH=7.

[0058] Third, the present invention provides a probe molecule for removing anionic surfactants from water, in order to achieve the purpose of removing anionic surfactants;

[0059] The steps for removing anionic surfactants using probe molecules as described in this invention (taking SDBS as an example):

[0060] (1) Dissolve Formula I / Formula II in ultrapure water to obtain a probe molecule solution;

[0061] (2) The probe molecules prepared in step (1) are added to water containing SDBS for reaction;

[0062] (3) After the reaction is complete, the solution is added to the ultrafiltration removal system for separation and removal. The removed sample is analyzed to obtain the efficiency of the probe molecules in removing SDBS.

[0063] The pore size of the ultrafiltration system includes, but is not limited to, 3-300 kDa; preferably, the ultrafiltration system can be used for separation and removal when the SDBS concentration is 0.1-20 μM.

[0064] Probe stock solution preparation: Weigh the solid and prepare a stock solution with a concentration of 5 μmol using ultrapure water. Dilute the stock solution with ultrapure water to a certain concentration for testing.

[0065] Preparation of standard solution of anionic surfactant: Prepare a 10mM solution from the purchased standard solution and powder of anionic surfactant, dispense the solution into small bottles of the same volume for later use, and store in a refrigerator at 4℃.

[0066] Preparation of interfering substances: Prepare a 10mM solution from the purchased standard solution and powder, dispense it into small bottles of the same volume for later use, and store it in a refrigerator at 4℃.

[0067] Fourth, the types of anionic surfactants to be detected and removed include, but are not limited to, alkyl carboxylic acids (sodium dodecyl carboxylate SDC), alkyl sulfonic acids (sodium octyl sulfonate OS), alkyl benzene sulfonic acids (sodium dodecyl benzene sulfonate SDBS), and alkyl sulfuric acids (sodium octyl sulfate SOS, sodium dodecyl sulfate SDS).

[0068] Example 1: Detection effect of cationic polythiophene on anionic surfactants

[0069] 1. Principle of cationic polythiophene probe for detecting anionic surfactants

[0070] Homopolymers PT1-PT17 and PT29, and copolymers PT18-20 and PTC-PTF were synthesized according to the literature (Chinese Patent: CN118480172A). Based on their conformation and aggregation state in solution, cationic polythiophene probes can be divided into two categories: depolymerization type and aggregation type.

[0071] Figure 1 This is a schematic diagram illustrating the principle of cationic polythiophene probe detection of anionic surfactants. Figure 1 As shown in Figure A, the depolymerized polythiophene probe is purplish-red and exhibits red fluorescence. Upon addition of an anionic surfactant, the aggregates formed by the probe molecules in water are dispersed, and the solution color correspondingly changes from purplish-red to yellow. Figure 1 As shown in Figure B, the aggregated polythiophene probe is pale yellow with yellow fluorescence and is uniformly dispersed in aqueous solution. When an anionic surfactant is added, a cationic polythiophene-anionic surfactant complex is formed, and the color of the solution changes from yellow to purplish-red accordingly.

[0072] 2. Identifying the structural features of cationic polythiophene probes for anionic surfactants

[0073] Different structural probe molecules were added to a uniformly sized colorimetric cell to obtain a detection reagent for detecting anionic surfactants (SDS).

[0074] Add SDS standard solution to the colorimetric cell and measure changes in ultraviolet-visible absorption spectrum, fluorescence spectrum, visual color change, and fluorescence color change;

[0075] like Figure 2 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 anionic surfactants, specifically manifested as changes in the UV-Vis absorption spectrum and color, and fluorescence quenching accompanied by changes in fluorescence color. This indicates that when the R1 structure at the 4-position of the thiophene in the synthesized probe molecule (Ⅰ) is CH3 or H, it can be used for UV / fluorescence dual-mode detection of anionic surfactants.

[0076] like Figure 3 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 anionic surfactants, indicating that the synthesized probe molecules with m carbon chain lengths of 1-15 in the (Ⅰ) molecule can be used for UV / fluorescence dual-mode detection of anionic surfactants.

[0077] Example 2: Visualized dual-mode detection of depolymerized cationic polythiophene on anionic surfactants

[0078] 1. Identifying the structural features of depolymerized cationic polythiophene probes for anionic surfactants

[0079] By adjusting R in the molecule of the above formula (Ⅰ) # Substituents can be used to prepare depolymerized cationic polythiophene probes with different structures. These depolymerized probe molecules are then added to a uniformly sized colorimetric cell to obtain a detection reagent for anionic surfactants (SDS).

[0080] Add SDS standard solution to the colorimetric cell and measure changes in ultraviolet-visible absorption spectrum, fluorescence spectrum, visual color change, and fluorescence color change;

[0081] like Figure 4 As shown, in the regulatory formula (Ⅰ) molecule, R # After the substituents were added, the depolymerization probe molecules all showed good signal output responses to anionic surfactants, indicating that the synthesized depolymerization probe molecules with the formula (Ⅰ)R # Substituents such as quaternary ammonium salt substituents (methyl, ethyl), 1-methylimidazole, and 1,2-dimethylimidazole structures can all be used for UV / fluorescence dual-mode detection of anionic surfactants.

[0082] like Figure 5 As shown, after adjusting the structure and polymerization ratio of the monomer in formula (II), the depolymerization probe molecules all showed good signal output response to anionic surfactants, indicating that the synthesized depolymerization probe molecule (II) can be used for UV / fluorescence dual-mode detection of anionic surfactants after adjusting the structure and polymerization ratio of the monomer.

[0083] 2. Depolymerization-type cationic polythiophene probes for ultraviolet spectroscopy sensing of anionic surfactants

[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 SDS.

[0085] The UV-Vis absorption spectrum of the probe molecule was scanned, and then a certain concentration of SDS standard solution was gradually added to the colorimetric cell. After mixing evenly, the UV-Vis absorption spectrum was measured, and the peak values ​​at 395 nm and 537 nm were read.

[0086] The results are as follows Figure 6 show, Figure 6 A indicates that the absorbance of the aforementioned depolymerization probe molecule at 537 nm gradually decreases with the addition of SDS, while the absorbance at 395 nm gradually increases. Figure 6 B shows the relationship between the absorbance ratio and the change in SDS concentration; as the SDS concentration increases, the absorbance ratio A... 395nm / A 537nmGradual increase allows for quantitative detection within the 0-10 μM range with good linearity (R0). 2 =0.97198). According to the method for calculating the detection limit, the detection limit of the probe molecule for SDS is 0.209 μmol / L.

[0087] 3. Depolymerization-type cationic polythiophene probes are used for colorimetric sensing of anionic surfactants.

[0088] The probe stock solution was dissolved in ultrapure water to obtain the probe molecule solution. 1 mL of the obtained probe molecule solution was added to a glass vial as a reagent for detecting SDS.

[0089] Add SDS standard solutions of different concentrations to a vial, mix well, and then take photos under natural indoor light. Figure 6 C) Use the software Color Grab to extract the RGB values ​​of each vial. Figure 6 D);

[0090] Figure 6 Results C and D indicate that the solution color of the probe molecules gradually changes from purple to yellow with increasing SDS concentration. The detection limit is 5 μmol / L. The G value obtained by software reading shows a linear relationship with the SDS concentration, with a correlation coefficient R. 2 The value was 0.99148, and the detection limit was 2.5 μmol / L.

[0091] 4. Depolymerization-type cationic polythiophene probes are used for fluorescence sensing detection of anionic surfactants.

[0092] 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 uniformly sized fluorescence cell as a reagent for detecting SDS.

[0093] The fluorescence spectrum of the depolymerization probe molecule was measured, and the fluorescence intensity at a wavelength of 590 nm was recorded as I0. Subsequently, a certain concentration of SDS standard solution was gradually added to the fluorescence cell, and after thorough mixing, the corresponding fluorescence spectrum was measured, and the fluorescence intensity at a wavelength of 590 nm was recorded as I.

[0094] The results are as follows Figure 6 As shown in Figure E, the probe molecule is excited at a wavelength of 420 nm, exhibits a maximum absorption peak at 590 nm, and emits strong yellow fluorescence in aqueous solution. With the addition of SDS, the fluorescence intensity of the probe molecule gradually increases. Figure 6 F indicates the relationship between fluorescence enhancement and SDS concentration; as the SDS concentration increases, the fluorescence intensity ratio I / I0 gradually rises. Based on the method for calculating the detection limit, the detection limit of the depolymerized probe molecule for SDS is 0.026 μmol / L.

[0095] 5. Depolymerization-type cationic polythiophene probes are used for colorimetric and ultraviolet spectroscopy sensing to detect the specificity of anionic surfactants.

[0096] Common anions selected from water include (Cl) - ClO3 - CO3 2- HCO3 - NO3 - SO4 2- F - PO4 3- HPO4 2- H2PO4 - Nonionic surfactants (Tween-20, Triton X-100) and cationic surfactants (CTAB) are used as interfering substances in the detection of anionic surfactants (SDS, SDBS).

[0097] To more intuitively observe the effect of the interaction between the probe molecules and the anionic surfactant, the color change of the solution was observed under fluorescent light and photographed.

[0098] like Figure 7 As shown in Figure A, when interfering substances are added to the depolymerization probe molecules, the color of the solution does not change or turns purple-red, while when SDS and SDBS are added, the color of the solution turns yellow.

[0099] 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 volumeed colorimetric cell as the reagent for detecting anionic surfactants. Under the same conditions, UV-Vis absorption spectroscopy was performed, and the ratio of the absorbance at 392 nm to the absorbance at 535 nm was calculated. A 392nm / A 535nm As a parameter to measure the degree of response of probe molecules to the analyte;

[0100] The results are as follows Figure 7 As shown in B, the A of the interfering substances other than SDS and SDBS 392nm / A 535nm The ratio is <0.82, while the A ratio of anionic surfactants SDS and SDBS is <0.82. 392nm / A 537nm A ratio > 5.8 indicates that the depolymerization probe molecules have good selectivity when using UV-Vis absorption spectroscopy to detect anionic surfactants;

[0101] 6. Depolymerization-type cationic polythiophene probes are used for fluorescence colorimetry and fluorescence spectroscopy sensing to detect the specificity of anionic surfactants.

[0102] Common anions selected from water include (Cl) -ClO3 - CO3 2- HCO3 - NO3 - SO4 2- F - PO4 3- HPO4 2- H2PO4 - Nonionic surfactants (Tween-20, Triton X-100) and cationic surfactants (CTAB) are used as interfering substances in the detection of anionic surfactants (SDS, SDBS).

[0103] To more intuitively observe the effects of the interaction between the probe molecules and anionic surfactants and other interfering substances, the changes in solution fluorescence during the selective study of the probe molecules' response to anionic surfactants were observed under blue light (470 nm).

[0104] like Figure 7 As shown in C, when interfering substances are added to the depolymerization probe molecules, the fluorescence color does not change or the fluorescence is quenched. However, when SDS and SDBS are added, the fluorescence color turns yellow and undergoes a certain degree of fluorescence enhancement and blue shift.

[0105] 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 uniformly sized fluorescence cell as a reagent for detecting anionic surfactants (SDS, SDBS).

[0106] Fluorescence spectroscopy was performed under the same conditions, and the fluorescence intensity value at 550 nm was compared with the fluorescence intensity value at 610 nm. 550nm / I 610nm As a parameter to measure the degree of response of probe molecules to the analyte;

[0107] The results are as follows Figure 7 As shown in D, the I of the substances other than SDS and SDBS 550nm / I 610nm The ratio is <0.8, while the I ratio of anionic surfactants SDS and SDBS is <0.8. 655nm / I 520nm A ratio >1.5 indicates that the depolymerization probe molecule can specifically detect anionic surfactants.

[0108] Example 3: Visualized dual-mode detection of aggregated cationic polythiophene on anionic surfactants

[0109] 1. Structural characteristics of aggregated cationic polythiophene probes for identifying anionic surfactants

[0110] By adjusting R in the molecule of the above formula (Ⅰ) # Substituents can be used to prepare aggregated cationic polythiophene probes with different structures. These aggregated probe molecules are then added to a uniformly sized colorimetric cell to obtain a detection reagent for anionic surfactants (SDS).

[0111] Add SDS standard solution to the colorimetric cell and measure changes in ultraviolet-visible absorption spectrum, fluorescence spectrum, visual color change, and fluorescence color change;

[0112] like Figure 8 As shown, after adjusting the structure of the R3 substituent in the (I) molecule, the aggregated probe molecules all showed good signal output response to anionic surfactants, indicating that the synthesized aggregated probe molecule (I) with the R3 substituent being a quaternary ammonium salt substituent (propyl, butyl, hexyl) structure can be used for UV / fluorescence dual-mode detection of anionic surfactants.

[0113] like Figure 9 As shown, after adjusting the structure and polymerization ratio of the monomer in formula (II), the aggregated probe molecules all showed good signal output response to anionic surfactants, indicating that the synthesized aggregated probe molecule (II) can be used for UV / fluorescence dual-mode detection of anionic surfactants after adjusting the structure and polymerization ratio of the monomer.

[0114] 2. Aggregated cationic polythiophene probes for ultraviolet spectroscopy sensing of anionic surfactants

[0115] 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 SDS.

[0116] The UV-Vis absorption spectrum of the probe molecule was scanned, and then a certain concentration of SDS standard solution was gradually added to the colorimetric cell. After mixing evenly, the UV-Vis absorption spectra were measured, and the peak values ​​at 535 nm and 405 nm were read.

[0117] The results are as follows Figure 10 show, Figure 10 A indicates that the absorbance of the aforementioned aggregated probe molecule at 405 nm gradually decreases with the addition of SDS, while the absorbance at 535 nm gradually increases. Figure 10 B shows the relationship between the absorbance ratio and the change in SDS concentration; as the SDS concentration increases, the absorbance ratio A... 535nm / A 405nm Gradual increase allows for quantitative detection within the 0-20 μM range with good linearity (R0). 2 =0.99888). According to the method for calculating the detection limit, the detection limit of the probe molecule for SDS is 0.0896 μmol / L.

[0118] 3. Aggregated cationic polythiophene probes are used for colorimetric sensing of anionic surfactants.

[0119] The probe stock solution was dissolved in ultrapure water to obtain the probe molecule solution. 1 mL of the obtained probe molecule solution was added to a glass vial as a reagent for detecting SDS.

[0120] Add SDS standard solutions of different concentrations to a vial, mix well, and then take photos under natural indoor light. Figure 10 C) Use the software Color Grab to extract the RGB values ​​of each vial. Figure 10 D);

[0121] Figure 10 Results C and D indicate that the solution color of the probe molecules gradually changes from yellow to red with increasing SDS concentration, with a visual detection limit of 5 μmol / L. The R / (G+B) value obtained by software reading shows a linear relationship with the SDS concentration, and the correlation coefficient R0 is [value missing]. 2 The value was 0.99554, and the detection limit was 1.90 μmol / L.

[0122] 4. Aggregated cationic polythiophene probes are used for fluorescence sensing detection of anionic surfactants.

[0123] 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 uniformly sized fluorescence cell as a reagent for detecting SDS.

[0124] The fluorescence spectrum of the aggregated probe molecule was measured, and the fluorescence intensity at a wavelength of 525 nm was recorded as I. 525nm Subsequently, a certain concentration of SDS standard solution was gradually added to the fluorescence cell, mixed thoroughly, and the corresponding fluorescence spectrum was measured. The fluorescence intensity at a wavelength of 650 nm was recorded as I. 650nm ;

[0125] The results are as follows Figure 10 As shown in Figure E, the probe molecule is excited at a wavelength of 420 nm, exhibits a maximum absorption peak at 525 nm, and emits strong yellow fluorescence in aqueous solution. With the addition of SDS, the fluorescence intensity of the probe molecule gradually quenches, and a redshift of the maximum fluorescence absorption peak occurs. Figure 10 F indicates the relationship between the redshift of the maximum absorption peak and the SDS concentration; as the SDS concentration increases, I... 650nm / I 525nm The fluorescence intensity ratio gradually increases. Based on the calculation method for the detection limit, the detection limit of the probe molecule for SDS is 0.2 μmol / L.

[0126] 5. Aggregated cationic polythiophene probes are used for colorimetric and ultraviolet spectroscopy sensing to detect the specificity of anionic surfactants.

[0127] Common anions selected from water include (Cl) - ClO3 - CO3 2- HCO3 - NO3 - SO4 2- F - PO4 3- HPO4 2- H2PO4 - Nonionic surfactants (Tween-20, Triton X-100) and cationic surfactants (CTAB) are used as interfering substances in the detection of anionic surfactants (SDS, SDBS).

[0128] To more intuitively observe the effect of the interaction between the probe molecules and the anionic surfactant, the color change of the solution was observed under fluorescent light and photographed.

[0129] like Figure 11 As shown in Figure A, the color of the solution did not change after adding interfering substances to the aggregated probe molecules, but the solution turned red after adding SDS and SDBS.

[0130] 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 anionic surfactants. 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;

[0131] The results are as follows Figure 11 As shown in B, the A of the interfering substances other than SDS and SDBS 525nm / A 405nm The ratio is <0.3, while the A ratio of anionic surfactants SDS and SDBS is <0.3. 525nm / A 405nm A ratio >1.7 indicates that aggregated probe molecules also exhibit good selectivity when using UV-Vis absorption spectroscopy to detect anionic surfactants.

[0132] 6. Aggregated cationic polythiophene probes are used for fluorescence colorimetry and fluorescence spectroscopy sensing to detect the specificity of anionic surfactants.

[0133] Common anions in water, including (Cl, ClO3, CO32-, HCO3-, NO3-, SO42-, F-, PO43-, HPO42-, H2PO4), nonionic surfactants (Tween-20, Triton X-100), and cationic surfactant CTAB, were selected as interfering substances in the detection of anionic surfactants (SDS, SDBS).

[0134] To more intuitively observe the effects of the interaction between the probe molecules and anionic surfactants and other interfering substances, the changes in solution fluorescence during the selective study of the probe molecules' response to anionic surfactants were observed under blue light (470 nm).

[0135] like Figure 11 As shown in C, the fluorescence color did not change after adding interfering substances to the aggregated probe molecule, but the fluorescence color turned red and underwent a certain degree of fluorescence quenching after adding SDS and SDBS.

[0136] 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 uniformly sized fluorescence cell as a reagent for detecting anionic surfactants (SDS, SDBS). Fluorescence spectroscopy was performed under the same conditions, and the ratio of the fluorescence value at 655 nm to the fluorescence value at 520 nm was calculated. 655nm / I 520nm As a parameter to measure the degree of response of probe molecules to the analyte;

[0137] The results are as follows Figure 11 As shown in D, the I of the substances other than SDS and SDBS 655nm / I 520nm The ratio is <2, while the I of anionic surfactants SDS and SDBS is <2. 655nm / I 520nm A ratio >38 indicates that aggregated probe molecules can also specifically detect anionic surfactants.

[0138] Example 4: Detection of various anionic surfactants using a polythiophene probe

[0139] To demonstrate the general applicability of the SDS detection method for anionic surfactants with different alkyl chain lengths and functional groups, we selected anionic surfactants with different carbon chain lengths (C8: OS, SOS; C12: SDC, SDS, SDBS) and different head groups (carboxylic acid group: SDC; sulfonic acid group: OS; benzenesulfonic acid group: SDBS; sulfate group: SOS, SDS) to investigate the detection effect of the polythiophene probe on different anionic surfactants.

[0140] 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 anionic surfactants. 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;

[0141] The results are as follows Figure 12 show, Figure 12 A indicates that after the addition of anionic surfactant, the absorbance of the probe molecule decreased at 405 nm, while the absorbance increased at 525 nm. Figure 12 B displays the absorbance ratio of A. 525nm / A 405nm The relationship with different anionic surfactants was investigated. It was shown that when the head groups of anionic surfactants were the same, the detection effect was better with a 12-carbon chain length than with an 8-carbon chain length; and among different head groups of anionic surfactants, the detection effect was in the order of sulfuric acid group > benzenesulfonic acid group > sulfonic acid group > carboxylic acid group.

[0142] Example 5: Removal of anionic surfactants by cationic polythiophene probe molecules

[0143] The probe molecules were mixed with a trace amount of anionic surfactant and added to an ultrafiltration tube. The tube was centrifuged at 5000g for 10 minutes. The permeate layer was taken and concentrated to 2mL by evaporation. After concentration, the probe molecules were added again and the UV-Vis absorption spectrum was scanned. The absorbance value at 535nm was read and the absorbance value at 405nm was compared as an important parameter to measure the removal effect.

[0144] The results are as follows Figure 12 As shown, the absorbance ratio of anionic surfactants in the permeate decreased significantly after the addition of probe solution (PT). This method can effectively remove low concentrations of anionic surfactants in water. The range of anionic surfactants removed by ultrafiltration is 0.1-20 μM, and the removal rate can reach 97%.

[0145] 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 an anionic surfactant with a cationic polythiophene derivative, characterized by: The cationic polythiophene derivative structure is shown as formula (I) or formula (II): Formula (I) Formula (I) is a homopolymer structure, R1 is CH3; R2 is O; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl; R4 is H or CH3; m is an integer between 2 and 15; M is Cl or Br; n is a positive integer, and the weight average molecular weight of the polythiophene derivative is 0.3 to 5 million; Formula (II) is composed of each thiophene unit connected by 2,5 positions to form a conjugated main chain, and the structural formula is as follows: Formula (II) Formula (II) is a copolymer structure, R1 is CH3; R2 is O; m is an integer between 2 and 15; M is Cl or Br; R 1# , R 2# , R 3# ,R 4# , are selected from R # substituents in the above formula (I), wherein R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl; R4 is H or CH3; and R 1# ≠ R 2# ≠ R 3# ≠ R 4# ; n1, n2, n3, n4 are integers between 1 and 500, and the weight average molecular weight of the polythiophene derivative is 0.3 to 100,000; The detection method comprises the following steps: (1) Dissolve the cationic polythiophene derivative shown as formula (I) or formula (II) in water to prepare a probe molecule; (2) Add the probe molecule obtained in step (1) to a quartz cuvette to obtain a detection reagent; (3) Gradually add an anionic surfactant standard solution to the cuvette, and measure the change of the ultraviolet-visible absorption spectrum and the fluorescence spectrum; (4) Analyze the relationship between the absorbance ratio and the concentration of the specific anionic surfactant and the relationship between the fluorescence intensity and the concentration of the specific anionic surfactant to quantitatively and specifically detect the anionic surfactant in the solution; 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; The anionic surfactant detected is selected from sodium dodecyl benzene sulfonate SDBS and sodium dodecyl sulfate SDS.

2. A method for removing an anionic surfactant from a cationic polythiophene derivative, characterized by: The cationic polythiophene derivative structure is shown as formula (I) or formula (II): Formula (I) Formula (I) is a homopolymer structure, R1 is CH3; R2 is O; R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl; R4 is H or CH3; m is an integer between 2 and 15; M is Cl or Br; n is a positive integer, and the weight average molecular weight of the polythiophene derivative is 0.3 to 5 million; Formula (II) is composed of each thiophene unit connected by 2,5 positions to form a conjugated main chain, and the structural formula is as follows: Formula (II) Formula (II) is a copolymer structure, R1 is CH3; R2 is O; m is an integer between 2 and 15; M is Cl or Br; R 1# , R 2# , R 3# , R 4# , is selected from R # substituents in the above formula (I), wherein R3 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl; R4 is H or CH3; and R 1# ≠ R 2# ≠ R 3# ≠ R 4# ; n1, n2, n3, n4 are integers between 1 and 500, and the weight average molecular weight of the polythiophene derivative is 0.3 to 100,000; The removal method comprises the following steps: (1) Dissolve the cationic polythiophene derivative shown as formula (I) or formula (II) in ultrapure water to obtain a probe molecule solution; (2) Add the probe molecule prepared in step (1) to water containing an anionic surfactant to react; (3) After the reaction is completed, the solution is added to a removal system for separation and removal, and the removed sample is analyzed to obtain the efficiency of the probe molecule in removing the corresponding anionic surfactant; When the concentration of the anionic surfactant is 0.1-20 μM, an ultrafiltration system is used for separation and removal, and the pore size of the ultrafiltration system is 3-300 kDa; The anionic surfactant removed is selected from sodium dodecyl benzene sulfonate SDBS and sodium dodecyl sulfate SDS.

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