A rapid screening method for perfluorooctane sulfonate in water based on zirconium-based fluorescent MOF

Abstract

The application discloses a kind of zirconium-based fluorescent MOF-based water perfluorooctane sulfonic acid rapid screening method, comprising the following steps: S1, zirconium-based fluorescent MOF preparation;S2, perfluorooctane sulfonic acid concentration gradient screening;S3, perfluorooctane sulfonic acid fluorescence kinetics analysis;S4, residual solid powder analysis;S5, water common ion influence analysis;S5-1, high concentration ion influence analysis;S5-2, low concentration ion influence analysis;S6, real water detection.The method of the application uses zirconium-based fluorescent MOF UiO-66-NH2 as sensor, synthesizes UiO-66-NH2 sensor by solvothermal method, and through the method of gradient concentration screening, fluorescence kinetics analysis and residual solid powder analysis of PFOS, from sensing sensitivity, speed and stability, greatly improve the accuracy of UiO-66-NH2 sensor for PFOS screening in water, provide theoretical basis and premise guarantee for the applicability of UiO-66-NH2 sensor in real water.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of organic pollutant screening, in particular to a rapid screening method for perfluorooctane sulfonic acid in water based on a zirconium-based fluorescent MOF. BACKGROUND

[0002] Perfluoroalkylated substances (PFASs) are a new type of persistent organic pollutants, which have environmental persistence, long-distance migration, biological accumulation, and various potential health risks such as developmental toxicity, immunotoxicity, neurotoxicity and carcinogenicity. The Stockholm Convention on Persistent Organic Pollutants lists various PFASs including perfluorooctane sulfonic acid (PFOS) as a restricted chemical and requires its control. Due to high water solubility and low volatility, water has become one of the important sinks of PFASs in the environment. Therefore, it is of great significance to screen and monitor PFASs in water.

[0003] At present, the conventional PFASs detection mainly relies on liquid chromatography / mass spectrometry, which has problems such as expensive equipment, complicated pretreatment process and complex operation, thereby limiting its wide application. The fluorescent sensing technology is a simple and real-time chemical substance detection method, which has shown excellent application potential in the screening of various environmental pollutants.

[0004] Metal-organic framework materials (MOFs) are a kind of coordination polymers that have developed rapidly in the past two decades, have a three-dimensional pore structure, generally use metal ions as connecting points, and use organic ligands to support the spatial 3D extension. In addition to zeolites and carbon nanotubes, MOFs are another important new type of porous material, which has been widely used in catalysis, energy storage and separation. MOFs have become an important research direction in inorganic chemistry, organic chemistry and other chemical branches.

[0005] However, the application of perfluorooctane sulfonic acid in MOF fluorescent sensing technology is not perfect, and has problems such as low sensitivity. The photo-induced luminescence performance of the commonly used MOF fluorescent sensing material is poor, and it cannot be well applied to the field of fluorescent detection, especially in the screening of perfluorooctane sulfonic acid in water, the accuracy of screening and monitoring is low. SUMMARY

[0006] In view of the above problems, the application provides a rapid screening method for perfluorooctane sulfonic acid in water based on a zirconium-based fluorescent MOF.

[0007] The technical scheme of the application is as follows:

[0008] A rapid screening method for perfluorooctane sulfonic acid in water based on a zirconium-based fluorescent MOF, comprising the following steps:

[0009] S1, zirconium-based fluorescent MOF preparation: using ZrCl4 and NH2-BDC as raw materials, DMF as a base solution, and a solvothermal method to synthesize a UiO-66-NH2 fluorescent sensor, that is, a zirconium-based fluorescent MOF;

[0010] S2, perfluorooctane sulfonic acid concentration gradient screening: the UiO-66-NH2 fluorescent sensor obtained in step S1 is dissolved in deionized water to obtain a sensor mother liquor with a mass concentration of 200 mg / L, an appropriate amount of sensor mother liquor and perfluorooctane sulfonic acid solution is added to several centrifuge tubes to obtain sensor solutions, the sensor mass concentration of each centrifuge tube is 2 mg / L, and the mass concentration of perfluorooctane sulfonic acid in each centrifuge tube forms a gradient concentration difference in the range of 0-20 mg / L, the fluorescence emission intensity of the sensor solution in each centrifuge tube is detected, and a fluorescence two-dimensional map is drawn;

[0011] S3, perfluorooctane sulfonic acid fluorescence kinetics analysis: an acetic acid buffer salt solution with a molar concentration of 10 mmol / L is configured and its pH is adjusted to 3, the sensor mother liquor and the perfluorooctane sulfonic acid solution are added to obtain a mixed detection liquid, the concentration of the UiO-66-NH2 fluorescent sensor in the mixed detection liquid is 5 mg / L, and the concentration of the perfluorooctane sulfonic acid is 1 mg / L, 3-5 ml of the mixed detection liquid is taken and used to continuously collect the fluorescence intensity at an excitation wavelength of 330 nm and an emission wavelength of 438 nm by using a fluorescence spectrometer, the collection time is 1500 s, the collection frequency is 30 s / time, and fluorescence kinetics analysis is performed on the collection results;

[0012] S4, residual solid powder analysis: the solution in the cuvette in step S2 and the mixed detection liquid in step S3 are recovered, dried for 12 h, and residual solid powder after the fluorescence sensing behavior of the UiO-66-NH2 fluorescent sensor and the perfluorooctane sulfonic acid solution is obtained, and the residual solid powder is detected and analyzed;

[0013] S5, analysis of the influence of common ions in water on the fluorescence sensing behavior of perfluorooctane sulfonic acid: common ions in water are selected to analyze the influence of common ions in water on the fluorescence sensing behavior of perfluorooctane sulfonic acid;

[0014] S5-1, high-concentration ion influence analysis: the sensor mother liquor is diluted with deionized water to obtain a sensor solution with a mass concentration of 2.5 mg / L, a water common ion solution with a mass concentration of 25 mg / L is prepared, 1 part by weight of the water common ion solution is added to an enzyme-labeled plate, and 4 parts by weight of the sensor solution is added to obtain an ion mixed liquid, the fluorescence intensity of the ion mixed liquid is detected by using a multifunctional fluorescence enzyme marker, and a control group is set, the control group is a mixture of 1 part by weight of a perfluorooctane sulfonic acid solution with a mass concentration of 25 mg / L and 4 parts by weight of the sensor solution.

[0015] S5-2, low concentration ion influence analysis: take the sensor mother liquor and add deionized water to dilute to obtain a sensor solution with a mass concentration of 2.5 mg / L, then prepare a common ion solution of water with a mass concentration of 2.5 mg / L, add 1 part by weight of the common ion solution of water to the enzyme-labeled plate, then add 4 parts by weight of the sensor solution to obtain an ion mixed solution, use a multifunctional fluorescence enzyme-labeled instrument to detect the fluorescence intensity of the ion mixed solution, and set a control group, the control group is 1 part by weight of a perfluorooctane sulfonic acid solution with a mass concentration of 2.5 mg / L and 4 parts by weight of the sensor solution mixed;

[0016] S6, real water body detection: after filtering the collected real water body samples in nature, the fluorescence emission intensity of the water sample is detected after adding the UiO-66-NH2 fluorescence sensor.

[0017] Further, the step S1 of preparing the zirconium-based fluorescent MOF is: weighing 1 g of ZrCl4 solid powder into a reaction container, sequentially adding 80 mL of DMF solution and 8 mL of concentrated hydrochloric acid solution into the reaction container, stirring and mixing for 2 min, then treating the reaction container under ultrasonic conditions for 20 min, then adding 1.08 g of NH2-BDC solid powder and 40 mL of DMF solution into the reaction container, and then treating the reaction container under ultrasonic conditions for 20 min to obtain a mixed solution after uniform dissolution of the solid powder. The mixed solution is heated at a temperature of 80℃ for 12h, and then naturally cooled to room temperature to obtain a mixed powder. The mixed powder is washed with DMF solution by filtration for three times, and then washed with anhydrous ethanol for three times. Then the mixed powder is filtered for 2-4h and placed in an oven for drying at 90℃ under vacuum conditions for 24h to obtain the UiO-66-NH2 fluorescence sensor, which is the zirconium-based fluorescent MOF. The UiO-66-NH2 fluorescence sensor prepared by this method has high purity, which improves the accuracy of the experimental results.

[0018] Further, the mass fraction of the concentrated hydrochloric acid solution is 36-38%, and the room temperature is 25-28℃. By adjusting the mass fraction of the concentrated hydrochloric acid solution and the room temperature, the optimal preparation conditions are achieved.

[0019] Further, in the step S2, there are 11 centrifugal tubes in total, and the mass concentration of perfluorooctane sulfonic acid in each centrifugal tube is 0 mg / L, 0.4 mg / L, 0.8 mg / L, 1.2 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 12 mg / L, and 20 mg / L, respectively. The fluorescence response intensity of the sensor is analyzed by different PFOS mass concentrations.

[0020] Further, the instrument for detecting and analyzing the residual solid powder in step S4 is a fluorescence spectrometer, a Fourier transform infrared spectrometer and an X-ray diffractometer.

[0021] Further, the common ions in the water body in step S5 are Cl - , SO4 2- , HCO3 - , NO3 - , K + , Mg 2+ , Ca 2+ and Al 3+ .

[0022] Further, the step in the real water body detection in step S6 is: collecting the real water body in nature as a water sample, filtering the water sample by using a filter membrane to remove the suspended solids and impurities in the water sample, then adding concentrated hydrochloric acid solution to the water sample to adjust the pH value of the water sample to 3-4, then adding acetic acid buffer salt solution to adjust the pH value of the water sample to 5-5.5, dividing the water sample after adjusting the pH value into several aliquots, preparing several portions of gradient concentration perfluorooctane sulfonic acid solution, adding one portion of the perfluorooctane sulfonic acid solution to each water sample, preparing the water sample containing the gradient concentration perfluorooctane sulfonic acid solution, and then adding 1 weight portion of the water sample containing the gradient concentration perfluorooctane sulfonic acid solution into 4 weight portions of the sensor solution with a mass concentration of 2.5 mg / L to detect the fluorescence emission intensity in the water sample.

[0023] Further, there are five portions of the gradient concentration perfluorooctane sulfonic acid solution, and the mass concentrations of the perfluorooctane sulfonic acid solution are 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L and 100 mg / L respectively.

[0024] Further, the pore size of the filter membrane is 0.22 microns. By selecting a filter membrane with a suitable size, impurities in the water body can be effectively filtered.

[0025] The beneficial effects of the present application are:

[0026] (1) The water body perfluorooctane sulfonic acid rapid screening method of the present application uses zirconium-based fluorescent MOF UiO-66-NH2 as a sensor, synthesizes the UiO-66-NH2 sensor by using a solvothermal method, and through the methods of gradient concentration screening of PFOS, fluorescence kinetic analysis and residual solid powder analysis, the accuracy of the UiO-66-NH2 sensor for screening PFOS in the water body is greatly improved from the aspects of sensor sensitivity, speed and stability, which provides a theoretical basis and premise guarantee for the applicability of the UiO-66-NH2 sensor in real water bodies.

[0027] (2) The water body perfluorooctane sulfonic acid rapid screening method of the application takes ZrCl4 as a zirconium source and NH2-BDC as an organic monomer to prepare UiO-66-NH2 in a regular octahedral stacking structure, and the crystal form is good. UiO-66-NH2 contains rich amino functional groups and microporous channel structures, and the specific surface area is about 918.46 m 2 g -1 The fluorescence spectrum analysis shows that the strongest fluorescence peak of UiO-66-NH2 is located at an excitation wavelength of 330 nm and an emission wavelength of 438 nm, and the fluorescence property is stable, and the fluorescence intensity of the aqueous solution does not change obviously (<13%) within one week.

[0028] (3) The UiO-66-NH2 sensor in the water body perfluorooctane sulfonic acid rapid screening method of the application has a fluorescence opening response to PFOS, and as the PFOS concentration increases, the fluorescence intensity of the UiO-66-NH2 sensor gradually increases. Within the concentration range of 0-20 mg / L, the fluorescence intensity enhancement of the UiO-66-NH2 sensor at Ex=330 nm / Em=438 nm is positively correlated with the PFOS concentration (R 2 =0.998), and the detection limit of the fluorescence method based on the UiO-66-NH2 sensor for PFOS is 30 μg / L (0.06 μmol / L), which is lower than that of most reported PFASs fluorescence sensors (10 -5 -10 -9 mol / L), indicating that it has good sensitivity.

[0029] (3) The UiO-66-NH2 sensor in the water body perfluorooctane sulfonic acid rapid screening method of the application exhibits good selectivity to PFOS, and the fluorescence response intensity of the UiO-66-NH2 sensor to PFOS is much higher than that of Cl - , SO4 2- , HCO3 - , NO3 - , K + , Mg 2+ , Ca 2+ , Al 3+ at the same concentration, which indicates that the sensing process of the UiO-66-NH2 sensor to PFOS is basically not affected by common anions and cations in water bodies, and it also has good applicability in actual PFOS contaminated water detection. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a flow chart of the water body perfluorooctane sulfonic acid rapid screening method based on zirconium-based fluorescent MOF of the application;

[0031] Figure 2FI-IR spectra of the UiO-66-NH2 fluorescent sensor synthesized in the experimental example of the present application;

[0032] Figure 3 Effect of PFOS concentration on the fluorescence emission intensity of the UiO-66-NH2 fluorescent sensor in the experimental example of the present application;

[0033] Figure 4 Fluorescence kinetic image of PFOS and the UiO-66-NH2 fluorescent sensor in the experimental example of the present application;

[0034] Figure 5 PFOS fluorescence standard curve in the experimental example of the present application;

[0035] Figure 6 Response of the UiO-66-NH2 fluorescent sensor to PFOS and various ions at low concentration in the experimental example of the present application;

[0036] Figure 7 Response of the UiO-66-NH2 fluorescent sensor to PFOS and various ions at high concentration in the experimental example of the present application. DETAILED DESCRIPTION

[0037] Example 1

[0038] A rapid screening method for perfluorooctane sulfonate in water based on zirconium-based fluorescent MOF, as shown in formula (I), comprises the following steps: Figure 1

[0039] S1, preparation of zirconium-based fluorescent MOF: taking ZrCl4 and NH2-BDC as raw materials, DMF as base solution, and adopting solvothermal method to synthesize UiO-66-NH2 fluorescent sensor, i.e. zirconium-based fluorescent MOF;

[0040] The steps for preparing the zirconium-based fluorescent MOF are as follows: 1g of ZrCl4 solid powder is placed in a reaction container, 80mL of DMF solution and 8mL of concentrated hydrochloric acid solution are sequentially added to the reaction container, the mass fraction of the concentrated hydrochloric acid solution is 37%, the mixture is stirred for 2min, then the reaction container is treated under ultrasonic condition for 20min, then 1.08g of NH2-BDC solid powder and 40mL of DMF solution are added to the reaction container, and the reaction container is treated under ultrasonic condition for 20min to obtain a mixed solution in which the solid powder is uniformly dissolved, the mixed solution is heated at a temperature of 80℃ for 12h, and then naturally cooled to room temperature (26℃), a mixed powder is obtained, the mixed powder is washed with DMF solution by filtration for three times, then washed with anhydrous ethanol for three times, then the mixed powder is filtered for 3h and placed in an oven for drying at 90℃ under vacuum condition for 24h, and the UiO-66-NH2 fluorescent sensor, i.e. zirconium-based fluorescent MOF, is obtained; ​

[0041] S2, the concentration gradient screening of perfluorooctane sulfonic acid: the UiO-66-NH2 fluorescent sensor obtained in step S1 is dissolved in deionized water to obtain a sensor mother liquor with a sensor mass concentration of 200 mg / L, and appropriate amounts of sensor mother liquor and perfluorooctane sulfonic acid solution are added to 11 centrifuge tubes to obtain sensor solutions, so that the sensor mass concentration of the sensor solution in each centrifuge tube is 2 mg / L, and the mass concentration of perfluorooctane sulfonic acid in the sensor solution in each centrifuge tube forms a gradient concentration difference in the range of 0-20 mg / L, and the mass concentration of perfluorooctane sulfonic acid in each centrifuge tube is 0 mg / L, 0.4 mg / L, 0.8 mg / L, 1.2 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 12 mg / L, and 20 mg / L, respectively. The fluorescence emission intensity of the sensor solution in each centrifuge tube is detected, and a two-dimensional fluorescence map is drawn;

[0042] S3, fluorescence kinetics analysis of perfluorooctane sulfonic acid: a molar concentration of 10 mmol / L of acetic acid buffer salt solution is configured and its pH is adjusted to 3, the sensor mother liquor and perfluorooctane sulfonic acid solution are added to obtain a mixed detection solution, so that the concentration of UiO-66-NH2 fluorescent sensor in the mixed detection solution is 5 mg / L, and the concentration of perfluorooctane sulfonic acid is 1 mg / L, 4 ml of the mixed detection solution is taken and the fluorescence intensity at an excitation wavelength of 330 nm and an emission wavelength of 438 nm is continuously collected using a fluorescence spectrometer, the collection time is 1500 s, and the collection frequency is 30 s / time. The collected results are subjected to fluorescence kinetics analysis;

[0043] S4, residual solid powder analysis: the solution in the cuvette in step S2 and the mixed detection solution in S3 are recovered, dried for 12 h, and the residual solid powder after the fluorescence sensing behavior of UiO-66-NH2 fluorescent sensor and perfluorooctane sulfonic acid solution is obtained. The residual solid powder is detected and analyzed, and the instruments for detecting and analyzing the residual solid powder are fluorescence spectrometer, Fourier transform infrared spectrometer and X-ray diffractometer;

[0044] S5, analysis of the influence of common ions in water on the fluorescence sensing behavior of perfluorooctane sulfonic acid: common ions in water are selected, and the common ions in water are Cl - , SO4 2- , HCO3 - , NO3 - , K + , Mg 2+ , Ca 2+ , Al 3+ , and the influence of common ions in water on the fluorescence sensing behavior of perfluorooctane sulfonic acid is analyzed;

[0045] S5-1, high concentration ion influence analysis: take the sensor mother liquor and add deionized water to dilute to obtain a sensor solution with a mass concentration of 2.5 mg / L, then prepare a common ion solution of water with a mass concentration of 25 mg / L, add 1 part by weight of the common ion solution of water to the enzyme-labeled plate, then add 4 parts by weight of the sensor solution to obtain an ion mixed solution, use a multifunctional fluorescence enzyme-labeled instrument to detect the fluorescence intensity of the ion mixed solution, and set a control group, and the control group is a mixture of 1 part by weight of a perfluorooctane sulfonic acid solution with a mass concentration of 25 mg / L and 4 parts by weight of the sensor solution;

[0046] S5-2, low concentration ion influence analysis: take the sensor mother liquor and add deionized water to dilute to obtain a sensor solution with a mass concentration of 2.5 mg / L, then prepare a common ion solution of water with a mass concentration of 2.5 mg / L, add 1 part by weight of the common ion solution of water to the enzyme-labeled plate, then add 4 parts by weight of the sensor solution to obtain an ion mixed solution, use a multifunctional fluorescence enzyme-labeled instrument to detect the fluorescence intensity of the ion mixed solution, and set a control group, and the control group is a mixture of 1 part by weight of a perfluorooctane sulfonic acid solution with a mass concentration of 2.5 mg / L and 4 parts by weight of the sensor solution;

[0047] S6, real water body detection: after filtering the collected real water body in nature, the fluorescence emission intensity of the water sample in the water body is detected after adding the UiO-66-NH2 fluorescence sensor;

[0048] The steps in the real water body detection are: the real water body in nature collected is tap water or surface water, which is used as a water sample. The water sample is filtered using a filter membrane to remove suspended solids and impurities in the water sample. The pore size of the filter membrane is 0.22 μm. Then, concentrated hydrochloric acid solution is added to the water sample to adjust the pH value of the water sample to 3.5. Then, acetic acid buffer salt solution is added to adjust the pH value of the water sample to 5.2. The water sample after adjusting the pH value is divided into 5 equal parts. Five gradient concentrations of perfluorooctane sulfonic acid solutions are prepared. One part of the perfluorooctane sulfonic acid solution is added to each water sample to prepare a water sample containing a gradient concentration of perfluorooctane sulfonic acid solution. The mass concentration of the perfluorooctane sulfonic acid solution is 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L and 100 mg / L, respectively. Then, 1 part by weight of the water sample containing the gradient concentration of perfluorooctane sulfonic acid solution is taken and added to 4 parts by weight of the sensor solution with a mass concentration of 2.5 mg / L to detect the fluorescence emission intensity of the water sample.

[0049] Example 2

[0050] The difference between this embodiment and example 1 is that the method parameters for preparing the zirconium-based fluorescent MOF in step S1 are different.

[0051] S1, preparation of zirconium-based fluorescent MOF: ZrCl4 and NH2-BDC were used as raw materials, DMF was used as a base solution, and a solvent thermal method was used to synthesize a UiO-66-NH2 fluorescent sensor, that is, a zirconium-based fluorescent MOF;

[0052] The steps for preparing the zirconium-based fluorescent MOF are as follows: 1 g of ZrCl4 solid powder was placed in a reaction container, 80 mL of DMF solution and 8 mL of concentrated hydrochloric acid solution were sequentially added to the reaction container, the mass fraction of the concentrated hydrochloric acid solution was 36%, and the mixture was stirred for 2 min, then the reaction container was treated under ultrasonic conditions for 20 min, then 1.08 g of NH2-BDC solid powder and 40 mL of DMF solution were added to the reaction container, and the reaction container was treated under ultrasonic conditions for 20 min to obtain a mixed solution in which the solid powder was uniformly dissolved, the mixed solution was heated at a temperature of 80°C for 12 h, and then naturally cooled to room temperature, the room temperature was 25°C, a mixed powder was obtained, the mixed powder was washed with DMF solution by suction filtration three times, then washed with anhydrous ethanol three times, then the mixed powder was filtered for 2 h and placed in an oven for drying at 90°C under vacuum conditions for 24 h, and a UiO-66-NH2 fluorescent sensor, that is, a zirconium-based fluorescent MOF, was obtained.

[0053] Example 3

[0054] The difference between this example and Example 1 is that the method parameters for preparing the zirconium-based fluorescent MOF in step S1 are different.

[0055] S1, preparation of zirconium-based fluorescent MOF: ZrCl4 and NH2-BDC were used as raw materials, DMF was used as a base solution, and a solvent thermal method was used to synthesize a UiO-66-NH2 fluorescent sensor, that is, a zirconium-based fluorescent MOF;

[0056] The steps for preparing the zirconium-based fluorescent MOF are as follows: 1 g of ZrCl4 solid powder was placed in a reaction container, 80 mL of DMF solution and 8 mL of concentrated hydrochloric acid solution were sequentially added to the reaction container, the mass fraction of the concentrated hydrochloric acid solution was 36%, and the mixture was stirred for 2 min, then the reaction container was treated under ultrasonic conditions for 20 min, then 1.08 g of NH2-BDC solid powder and 40 mL of DMF solution were added to the reaction container, and the reaction container was treated under ultrasonic conditions for 20 min to obtain a mixed solution in which the solid powder was uniformly dissolved, the mixed solution was heated at a temperature of 80°C for 12 h, and then naturally cooled to room temperature, the room temperature was 25°C, a mixed powder was obtained, the mixed powder was washed with DMF solution by suction filtration three times, then washed with anhydrous ethanol three times, then the mixed powder was filtered for 2 h and placed in an oven for drying at 90°C under vacuum conditions for 24 h, and a UiO-66-NH2 fluorescent sensor, that is, a zirconium-based fluorescent MOF, was obtained.

[0057] Example 4

[0058] The difference between this embodiment and embodiment 1 is that the method parameters of step S3 perfluorooctane sulfonic acid fluorescence kinetics analysis are different.

[0059] S3, perfluorooctane sulfonic acid fluorescence kinetics analysis: prepare an acetic acid buffer solution with a molar concentration of 10 mmol / L and adjust the pH to 3, add the sensor mother liquor and perfluorooctane sulfonic acid solution to obtain a mixed detection solution, so that the concentration of UiO-66-NH2 fluorescence sensor in the mixed detection solution is 5 mg / L and the concentration of perfluorooctane sulfonic acid is 1 mg / L, take 3 ml of the mixed detection solution and use a fluorescence spectrometer to continuously collect the fluorescence intensity at an excitation wavelength of 330 nm and an emission wavelength of 438 nm, the collection time is 1500 s, and the collection frequency is 30 s / time, and the collection results are subjected to fluorescence kinetics analysis.

[0060] Embodiment 5

[0061] The difference between this embodiment and embodiment 1 is that the method parameters of step S3 perfluorooctane sulfonic acid fluorescence kinetics analysis are different.

[0062] S3, perfluorooctane sulfonic acid fluorescence kinetics analysis: prepare an acetic acid buffer solution with a molar concentration of 10 mmol / L and adjust the pH to 3, add the sensor mother liquor and perfluorooctane sulfonic acid solution to obtain a mixed detection solution, so that the concentration of UiO-66-NH2 fluorescence sensor in the mixed detection solution is 5 mg / L and the concentration of perfluorooctane sulfonic acid is 1 mg / L, take 3 ml of the mixed detection solution and use a fluorescence spectrometer to continuously collect the fluorescence intensity at an excitation wavelength of 330 nm and an emission wavelength of 438 nm, the collection time is 1500 s, and the collection frequency is 30 s / time, and the collection results are subjected to fluorescence kinetics analysis.

[0063] Embodiment 6

[0064] The difference between this embodiment and embodiment 1 is that the method parameters of step S6 real water body detection are different.

[0065] S6, real water body detection: after filtering the collected real water body of nature, the fluorescence emission intensity of the water sample is detected after adding the UiO-66-NH2 fluorescence sensor;

[0066] The steps in the real water body detection are: the collected natural real water body is tap water or surface water as a water sample, the water sample is filtered by a filter membrane to remove suspended solids and impurities in the water sample, the pore size of the filter membrane is 0.22 μm, then concentrated hydrochloric acid solution is added to the water sample to adjust the pH value of the water sample to 3, then acetic acid buffer salt solution is added to adjust the pH value of the water sample to 5, the water sample after adjusting the pH value is divided into 5 equal parts, 5 gradient concentrations of perfluorooctane sulfonic acid solution are prepared, one part of the perfluorooctane sulfonic acid solution is added to each water sample to prepare a water sample containing gradient concentration perfluorooctane sulfonic acid solution, the mass concentration of the perfluorooctane sulfonic acid solution is 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L and 100 mg / L respectively, then 1 weight part of the water sample containing gradient concentration perfluorooctane sulfonic acid solution is added to 4 weight parts of the sensor solution with a mass concentration of 2.5 mg / L, and the fluorescence emission intensity in the water sample is detected.

[0067] Example 7

[0068] The difference between this embodiment and example 1 is that the method parameters of step S6 real water body detection are different.

[0069] S6, real water body detection: after filtering the collected natural real water body water sample, the fluorescence emission intensity in the water sample is detected after adding the UiO-66-NH2 fluorescent sensor;

[0070] The steps in the real water body detection are: the collected natural real water body is tap water or surface water as a water sample, the water sample is filtered by a filter membrane to remove suspended solids and impurities in the water sample, the pore size of the filter membrane is 0.22 μm, then concentrated hydrochloric acid solution is added to the water sample to adjust the pH value of the water sample to 4, then acetic acid buffer salt solution is added to adjust the pH value of the water sample to 5.5, the water sample after adjusting the pH value is divided into 5 equal parts, 5 gradient concentrations of perfluorooctane sulfonic acid solution are prepared, one part of the perfluorooctane sulfonic acid solution is added to each water sample to prepare a water sample containing gradient concentration perfluorooctane sulfonic acid solution, the mass concentration of the perfluorooctane sulfonic acid solution is 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L and 100 mg / L respectively, then 1 weight part of the water sample containing gradient concentration perfluorooctane sulfonic acid solution is added to 4 weight parts of the sensor solution with a mass concentration of 2.5 mg / L, and the fluorescence emission intensity in the water sample is detected.

[0071] Experimental example

[0072] The method parameters in example 1 are taken as an example to verify the method, first, the UiO-66-NH2 fluorescent sensor synthesized by the method is detected, as shown in Figure 2 3342 cm-1 and 3452 cm -1 Typical double absorption peak for amino group, 1250 cm -1 C-N absorption peak, 1658 cm -1 Characteristic absorption peak for carbonyl group, 1574 cm -1 and 1386 cm -1 Characteristic absorption peak for carboxyl group, 1496 cm -1 Characteristic absorption peak for benzene ring—C=C—bond, 767 cm -1 and 663 cm –1 The characteristic peaks at 3420, 3300, 1658, 1574, 1496, 1250, 767 and 663 cm-1 are caused by Zr—O bond in UiO-66-NH2, the type and position of functional groups are consistent with the literature, indicating that the UiO-66-NH2 material is successfully prepared;

[0073] Subsequently, a perfluorooctane sulfonic acid concentration gradient screening was performed, such as Figure 3 It can be seen that with the increase of the concentration of PFOS solution, the degree of fluorescence response of the UiO-66-NH2 fluorescence sensor to PFOS is increasing;

[0074] Subsequently, perfluorooctane sulfonic acid fluorescence kinetics analysis was performed, such as Figure 4 It can be seen that the abscissa is time, the fluorescence intensity is measured every 30 s, and the ordinate is the ratio of the fluorescence increment after the sensing reaction with PFOS to the blank group of the UiO-66-NH2 fluorescence sensor. Around 7 min, the fluorescence increment ratio reaches a maximum of about 0.225 and remains a straight line, indicating that the kinetics reaches equilibrium.

[0075] Figure 5 The fluorescence standard curve of the sensing behavior of 2 mg / L UiO-66-NH2 fluorescence sensor with PFOS (excitation wavelength 330 nm, emission wavelength 438 nm) is shown in the figure. In the range of 0-20 mg / L, the fluorescence response intensity of the UiO-66-NH2 fluorescence sensor is linearly related to the concentration of PFOS. After linear fitting, y=0.101x+1.052 is obtained, wherein R 2 =0.998, the linear effect is good. It shows that the UiO-66-NH2 fluorescence sensor can be used as a fluorescence sensor for quantitative detection of PFOS concentration. According to the detection limit calculation formula (LOD=3σ / slope, σ is the standard deviation of the blank sample), the detection limit of the UiO-66-NH2 fluorescence sensor for PFOS is 30 μg / L (0.06 μmol / L), which is lower than most of the reported PFASs fluorescence sensors (10 -5 ~10 -9 mol / L), see Appendix 1.

[0076] Water common ion influence analysis such as Figure 6and 7 As shown in Fig. 6, it can be seen that neither low concentration ions (0.5 mg / L) nor high concentration ions (5 mg / L) significantly affect the PFOS detection by the UiO-66-NH2 fluorescent sensor. Under the same conditions, PFOS increased the fluorescence intensity of the UiO-66-NH2 fluorescent sensor by 11.6% and 81.2%, respectively, while the highest increase of other common ions was only 1.96% and 8.42%, and even showed a slight quenching effect. This result indicates the application potential of the UiO-66-NH2 fluorescent sensor in the detection of PFOS in actual water bodies.

[0077] To verify the applicability of the UiO-66-NH2 fluorescent sensor of the present application in the routine analysis of PFOS in water, further PFOS spiked detection was performed using actual water samples. We used tap water samples and Yangtze River surface water samples for analysis. The water samples had been pretreated, and different concentrations of known standard PFOS solution were added to the pretreated water samples, and then the UiO-66-NH2 fluorescent sensor was used for fluorescence detection. The test results are shown in Table 1. The recovery rate of the tap water sample was in the range of 91.8% to 102.6%, and the recovery rate of the Yangtze River surface water sample was in the range of 88.5% to 106.5%, indicating that the detection of PFOS in actual water samples by the UiO-66-NH2 fluorescent sensor was not significantly disturbed. All these results show that the fluorescent sensor detection method is accurate and reliable, and can be used to determine PFOS in water samples.

[0078] Table 1 Spiked recovery detection results of tap water and Yangtze River surface water

[0079]

[0080] Appendix 1 Reported detection limits and reaction times of PFASs fluorescent sensing methods

[0081]

Claims

1. A rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOFs, characterized in that, Includes the following steps: S1. Preparation of Zirconium-based fluorescent MOF: Using ZrCl4 and NH2-BDC as raw materials and DMF as substrate, UiO-66-NH2 fluorescent sensor was synthesized by solvothermal method, which is a zirconium-based fluorescent MOF. S2. Perfluorooctane sulfonic acid concentration gradient screening: The UiO-66-NH2 fluorescence sensor obtained in step S1 was dissolved in deionized water to obtain a sensor stock solution with a sensor mass concentration of 200 mg / L. An appropriate amount of sensor stock solution and perfluorooctane sulfonic acid solution were added to several centrifuge tubes to obtain sensor solutions, so that the sensor mass concentration of the sensor solution in each centrifuge tube was 2 mg / L. The perfluorooctane sulfonic acid mass concentration of the sensor solution in each centrifuge tube formed a gradient concentration difference in the range of 0 to 20 mg / L. A total of 11 centrifuge tubes were set up, and the perfluorooctane sulfonic acid mass concentrations of the sensor solution in each centrifuge tube were 0 mg / L, 0.4 mg / L, 0.8 mg / L, 1.2 mg / L, 2 mg / L, 3 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 12 mg / L, and 20 mg / L, respectively. The fluorescence emission intensity of the sensor solution in each centrifuge tube was detected, and a two-dimensional fluorescence spectrum was plotted. S3. Perfluorooctane sulfonic acid fluorescence kinetic analysis: Prepare an acetate buffer solution with a molar concentration of 10 mmol / L and adjust its pH to 3. Add the sensor stock solution and perfluorooctane sulfonic acid solution to obtain a mixed detection solution, so that the concentration of UiO-66-NH2 fluorescence sensor in the mixed detection solution is 5 mg / L and the concentration of perfluorooctane sulfonic acid is 1 mg / L. Take 3-5 ml of the mixed detection solution and use a fluorescence spectrometer to continuously collect its fluorescence intensity at an excitation wavelength of 330 nm and an emission wavelength of 438 nm. The collection time is 1500 s and the collection frequency is 30 s / time. Perform fluorescence kinetic analysis on the collection results. S4. Residual solid powder analysis: The solution in the cuvette in step S2 and the mixed detection solution in S3 were recovered and dried for 12 hours to obtain the residual solid powder after the UiO-66-NH2 fluorescence sensor reacted with the perfluorooctane sulfonic acid solution to undergo fluorescence sensing behavior. The residual solid powder was then detected and analyzed. S5. Analysis of the influence of common ions in water: Common ions in water are selected to analyze the influence of common ions in water on the fluorescence sensing behavior of perfluorooctane sulfonic acid. S5-1, Analysis of the impact of high concentration ions: The sensor stock solution was diluted with deionized water to obtain a sensor solution with a mass concentration of 2.5 mg / L. A common water ion solution with a mass concentration of 25 mg / L was then prepared. One part by weight of the common water ion solution was added to the ELISA plate, and then four parts by weight of the sensor solution were added to obtain an ion mixture. The fluorescence intensity of the ion mixture was detected using a multifunctional fluorescent ELISA reader. A control group was set up, which consisted of a mixture of one part by weight of perfluorooctane sulfonic acid solution with a mass concentration of 25 mg / L and four parts by weight of the sensor solution. S5-2, Analysis of the Influence of Low-Concentration Ions: The sensor stock solution was diluted with deionized water to obtain a sensor solution with a mass concentration of 2.5 mg / L. A common water ion solution with a mass concentration of 2.5 mg / L was then prepared. One part by weight of the common water ion solution was added to the ELISA plate, and then four parts by weight of the sensor solution were added to obtain an ion mixture. The fluorescence intensity of the ion mixture was detected using a multi-functional fluorescent ELISA reader. A control group was set up, which consisted of a mixture of one part by weight of perfluorooctane sulfonic acid solution with a mass concentration of 2.5 mg / L and four parts by weight of the sensor solution. S6. Real water body detection: After filtering the collected water samples from real natural water bodies, a UiO-66-NH2 fluorescence sensor is added to detect the fluorescence emission intensity in the water samples. The steps in real water body testing are as follows: The collected natural water body is tap water or surface water, used as a water sample. The water sample is filtered using a filter membrane to remove suspended solids and impurities. Then, concentrated hydrochloric acid solution is added to the water sample to adjust the pH to 3-4. Next, acetate buffer solution is added to adjust the pH to 5-5.

5. The pH-adjusted water sample is divided into several equal portions, and several portions of perfluorooctane sulfonic acid (PFOS) solutions of varying concentrations are prepared. One portion of PFOS solution is added to each water sample to prepare water samples containing PFOS solutions of varying concentrations. Then, one portion by weight of each water sample containing PFOS solutions of varying concentrations is added to four portions by weight of a sensor solution with a mass concentration of 2.5 mg / L, and the fluorescence emission intensity in the water sample is detected.

2. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOFs according to claim 1, characterized in that, The steps for preparing the zirconium-based fluorescent MOF in step S1 are as follows: Weigh 1g of ZrCl4 solid powder and place it in a reaction vessel. Add 80mL of DMF solution and 8mL of concentrated hydrochloric acid solution to the reaction vessel in sequence, stir and mix for 2min, and then treat the reaction vessel under ultrasonic conditions for 20min. Then add 1.08g of NH2-BDC solid powder and 40mL of DMF solution to the reaction vessel, and then treat the reaction vessel under ultrasonic conditions for 20min to obtain a mixed solution after the solid powder is uniformly dissolved. Heat the mixed solution at 80℃ for 12h, and then cool it naturally to room temperature to obtain a mixed powder. Filter and wash the mixed powder three times with DMF solution, and then wash it three times with anhydrous ethanol. Then filter the mixed powder for 2-4h and place it in an oven to dry under vacuum conditions at 90℃ for 24h to obtain the UiO-66-NH2 fluorescent sensor, which is the zirconium-based fluorescent MOF.

3. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOFs according to claim 2, characterized in that, The concentrated hydrochloric acid solution has a mass fraction of 36-38% and a room temperature of 25-28°C.

4. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOF according to claim 1, characterized in that, The instruments used to detect and analyze the residual solid powder in step S4 are a fluorescence spectrometer, a Fourier transform infrared spectrometer, and an X-ray diffractometer.

5. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOFs according to claim 1, characterized in that, In step S5, the common ion in the water is Cl. - SO4 2- HCO3 - NO3 - K + Mg 2+ Ca 2+ Al 3+ .

6. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOF according to claim 1, characterized in that, Five perfluorooctane sulfonic acid solutions with gradient concentrations of 5 mg / L, 10 mg / L, 25 mg / L, 50 mg / L, and 100 mg / L were prepared.

7. The rapid screening method for perfluorooctane sulfonic acid in water based on zirconium-based fluorescent MOF according to claim 1, characterized in that, The filter membrane has a pore size of 0.22 μm.

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