Construction method and application of MOFs-based nanoscale enzyme activated persulfate PFASs colorimetric sensor

Abstract

The application discloses a MOFs-based nanoscale enzyme activated persulfate PFASs colorimetric sensor construction method and application, and two MOFs-based nanoscale enzymes including PCN-222(Fe) powder precursors and modified PCN-222(Fe)-3F powder are prepared in sequence. The PCN-222(Fe)-3F with enzyme-like activity activates persulfate to catalyze TMB to present blue color. When PFOS exists, the catalytic activity of PCN-222(Fe)-3F is inhibited, thereby inhibiting the color development process. A rapid visual detection system of PFOS is established according to the linear relationship between the absorbance attenuation and the PFOS concentration. The method is low in cost, simple in operation, reasonable and efficient, high in sensitivity, and has a lower detection limit, and fills the blank of the colorimetric sensor technology in the prior art for rapidly detecting and screening PFASs in environmental media.

Description

Technical Field

[0001] This invention relates to the field of sensor fabrication and PFASs detection technology in environmental water, specifically to a method for constructing and applying a colorimetric sensor for PFASs activated by MOFs-based nanozymes. Background Technology

[0002] Colorimetric sensing technology is a high-throughput compound screening technology that uses enzymes / nanozymes to catalyze chromogenic substrates such as TMB, ABTS, and OPD to produce color changes, and then performs rapid visual detection by the naked eye or low-cost portable instruments. It has the advantages of high sensitivity, simple operation, and real-time on-site detection, and has been widely studied in food safety testing, environmental monitoring, clinical diagnosis, biotechnology, and public safety control.

[0003] Perfluorinated and polyfluoroalkyl substances (PFASs) are heat-resistant and difficult to degrade. They possess various toxicities, including carcinogenicity, reproductive toxicity, developmental toxicity, and neurotoxicity. Furthermore, these carcinogenic PFASs can persist in the body for years. Common PFAS components include perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). Traditional PFAS detection techniques primarily utilize large-scale instruments such as high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS / MS) and gas chromatography-mass spectrometry (GC-MS / MS). While these techniques achieve extremely low limits of detection (nanograms or even picograms), they suffer from drawbacks such as complex sample pretreatment, the need for specialized personnel for operation and maintenance, high equipment costs, and the inability to perform in-situ analysis. Therefore, developing a highly sensitive and cost-effective rapid screening technology for PFASs is essential.

[0004] Metal-organic frameworks (MOFs) are a wide range of ultraporous nanomaterials, commonly used in detection applications. Recent research on sensors for PFAS detection includes the following: Cheng et al. combined a MOF-based acceptor (MIL-101(Cr)) with PFOS affinity and a nanoporous ultrasensitive capacitive electrode within a microfluidic platform to develop a highly sensitive PFOS electrochemical sensor with a detection limit as low as 0.5 ng / L; Takayose et al. modified AuNPs with mercapto-polystyrene, and when PFOA was added to the AuNPs solution, polymerization occurred through fluorine-fluorine interactions, changing the solution color from red to purple, thus developing a simple probe for PFOA detection; Niu... Some researchers modified gold nanoparticles with terminal polyethylene glycol and terminal perfluoroalkyl thiols as probes, which exhibited good stability and a detection limit of 10 μg / L. Liu et al. synthesized MoS2-Fe3O4 nanomaterials for quantitative detection of PFOS. Li et al. synthesized cobalt-nitrogen-doped carbon nanosheets using ZIF-L as a precursor by doping with Co and N atoms, exhibiting enhanced enzyme-like activity for colorimetric detection of PFOS. Liu et al. loaded Cu atoms onto CN to form nanomaterials with single-atom dispersion, exhibiting peroxidase activity for PFOS detection, achieving a LOD of 14.9 nM. It can be seen that research on PFOS sensors has been increasing in recent years.

[0005] However, there are currently no reports on the use of MOF-based nanozyme materials to activate persulfate for colorimetric detection of PFASs, and research on the rapid screening of PFASs in environmental media using colorimetric sensor technology remains lacking. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a method for constructing and applying a colorimetric sensor for PFASs activated by MOFs-based nanozymes.

[0007] The technical solution of this invention is:

[0008] A method for constructing a colorimetric sensor for persulfate activated by MOF-based nanozymes includes the following steps:

[0009] S1. Preparation of MOFs-based nanozyme PCN-222(Fe): 60-80 mg of ZrCl2 powder, 40-60 mg of TCIPP(Fe) powder and 2.5-3 g of benzoic acid powder were dissolved in 6-10 mL of N,N-diethylformamide. After ultrasonic mixing and dispersion, the mixture was placed at 110-130℃ and allowed to react for 40-50 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone, and then dried under vacuum to obtain MOFs-based nanozyme PCN-222(Fe) powder.

[0010] S2. Preparation of MOFs-based nanozyme PCN-222(Fe)-3F: 50-70 mg of MOFs-based nanozyme PCN-222(Fe) powder obtained in step S1 was dissolved in 2-3 mL of N,N-diethylformamide, and 0.2-0.3 mmol of trifluoroacetic acid solution was added simultaneously. After stirring and mixing, the mixture was allowed to stand at 60-80℃ for 20-30 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone, and then dried under vacuum to obtain MOFs-based nanozyme PCN-222(Fe)-3F powder.

[0011] S3. Construction of a colorimetric sensor system for PFOS detection using MOF-based nanozyme-activated persulfate: 800–900 μL of 0.2 mol / L acetate buffer was added, followed by 40–80 μL of an aqueous solution of 400 mg / L MOF-based nanozyme PCN-222(Fe)-3F powder obtained in step S2. Then, 40–80 μL of 2 mmol / L 3,3',5,5'-tetramethylbenzidine solution was added as the reaction base solution. Several portions of the reaction base solution were then added to corresponding solutions at gradient concentrations of 50 mg / L. μL of PFOS solution was vortexed for 30–60 s, and then 40–80 μL of 0.5 mmol / L persulfate solution was added to each system to form several reaction systems, which were used as PFOS colorimetric sensors. The reaction was carried out at room temperature for 20–40 min. After filtering each reaction system, the absorbance of the reaction solution was measured at a wavelength of 652 nm. The gradient concentration range of PFOS solution was 0–25 μmol / L. A PFOS concentration-absorbance standard curve was constructed with the concentration of PFOS solution as the x-axis and the absorbance as the y-axis.

[0012] S4. Actual Water Body Detection: Take 40–80 μL of actual natural water body and prepare 1 mL of reaction base solution according to the method in step S3. Add the actual water body to the reaction base solution and vortex for 30–60 s. Then add 40–80 μL of persulfate solution with a molar concentration of 0.5 mmol / L to form a reaction system. React at room temperature for 20–40 min. After filtering the reaction system, take the reaction solution for absorbance detection at a wavelength of 652 nm. Compare the detected absorbance of the actual water body with the standard absorbance to obtain the difference in absorbance of the actual water body. Compare the difference in absorbance of the actual water body with the PFOS concentration-absorbance standard curve to obtain the concentration of PFOS solution in the actual water body.

[0013] Furthermore, the concentrations of N,N-dimethylformamide and N,N-diethylformamide in steps S1 and S2 are ≥99.5%.

[0014] Furthermore, in steps S1 and S2, the centrifugation speed is 9000-10000 rpm, and the solid product separated by centrifugation is washed 2-3 times with N,N-dimethylformamide and then washed 2-3 times with acetone.

[0015] Note: Pure MOFs-based nanozyme PCN-222(Fe) powder and MOFs-based nanozyme PCN-222(Fe)-3F powder were obtained by washing with N,N-dimethylformamide and acetone.

[0016] Furthermore, the ultrasonic mixing and dispersion treatment time in step S1 is 30 minutes.

[0017] Furthermore, in step S3, the acetate buffer is an acetate-sodium acetate buffer with a pH of 3.5.

[0018] Note: The pH value of the acetate buffer solution needs to be strictly controlled.

[0019] Furthermore, the filter head selected for filtering the reaction system in step S3 is a 0.22μm filter head.

[0020] Note: By optimizing the filter head size, the detection results of the filtered reaction solution can be made more accurate.

[0021] Further, in step S3, the molar concentrations of the PFOS solutions with gradient concentrations are successively 0 μmol / L, 0.1 μmol / L, 0.2 μmol / L, 0.4 μmol / L, 0.6 μmol / L, 0.8 μmol / L, 1 μmol / L, 1.5 μmol / L, 2 μmol / L, 4 μmol / L, 6 μmol / L, 8 μmol / L, 10 μmol / L, 15 μmol / L, 20 μmol / L, and 25 μmol / L, thus constructing the PFOS concentration... The specific method for the absorbance standard curve is as follows: the absorbance of the reaction system without PFOS solution at a wavelength of 652 nm is used as the standard absorbance. At the same time, the absorbance of each gradient concentration of PFOS solution obtained in step S3 at a wavelength of 652 nm is compared with the standard absorbance to obtain the difference in absorbance of the reaction system under each gradient concentration of PFOS solution. The PFOS concentration-absorbance standard curve is constructed with the concentration of PFOS solution as the abscissa and the difference in absorbance of the reaction system under each gradient concentration of PFOS solution as the ordinate.

[0022] Note: By optimizing the PFOS content in each of the above PFOS solutions, the final PFOS concentration-absorbance standard curve is made more accurate and reliable.

[0023] Furthermore, the room temperature is 20–30°C.

[0024] The application of the MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor constructed by any of the above methods is to apply the PFASs colorimetric sensor to the on-site detection of actual water bodies in nature.

[0025] Furthermore, 1 mL of the reaction base solution from step S3 and 50 μL of a 0.5 mmol / L persulfate solution are evenly spread on the surface of the test strip. 50 μL of actual water is then added to the surface of the test strip using a pipette, causing a change in absorbance. The change in absorbance of the actual water on the test strip is then measured colorimetrically using a portable UV spectrophotometer to obtain the absorbance of the actual water. The absorbance of the actual water is compared with the standard absorbance to obtain the difference in absorbance. The difference in absorbance of the actual water is then compared with the PFOS concentration-absorbance standard curve to obtain the concentration of PFOS solution in the actual water.

[0026] The beneficial effects of this invention are:

[0027] (1) The method for constructing a colorimetric sensor for PFASs activated by MOFs-based nanozymes of the present invention successively prepared MOFs-based nanozyme PCN-222(Fe) powder and MOFs-based nanozyme PCN-222(Fe)-3F powder. Then, the MOFs-based nanozyme activated the persulfate PCN-222(Fe)-3F powder to finally obtain a colorimetric sensor reaction system that can rapidly detect PFASs in environmental media. This reaction system can be used to rapidly detect PFASs in natural water bodies. The method is reasonable and efficient, filling the gap in the existing technology of colorimetric sensor technology for rapid detection of PFASs in environmental media. It also has high sensitivity and a low detection limit, which can be as low as 30.1 nM. The specific principle is as follows: The MOFs-based nanozyme PCN-222(Fe)-3F, which has enzyme-like activity, activates persulfate and catalyzes TMB to turn blue. When PFOS is present, it inhibits the catalytic activity of the MOFs-based nanozyme PCN-222(Fe)-3F, thereby inhibiting the color development process. A rapid visualization detection system for PFOS is established based on the linear relationship between the decrease in absorbance and the concentration of PFOS.

[0028] (2) The MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor construction method of the present invention is based on the method of the present invention and further proposes on-site detection application in actual water bodies. By applying the reaction system we prepared onto the surface of the test paper, the PFAS detection needs of rapid, portable, low-cost and user-friendly can be met at a suitable temperature. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the method for constructing a MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor according to the present invention.

[0030] Figure 2 This is the absorbance of PFOS solutions with gradient concentrations at various wavelengths in Experimental Example 1 of the method for constructing and applying the MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor of the present invention.

[0031] Figure 3 This is a standard curve of PFOS concentration-absorbance between the concentration of PFOS solution at 652 nm and the difference in absorbance of the reaction system at various gradient concentrations of PFOS solution in Experimental Example 1 of the construction method and application of the MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor of the present invention.

[0032] Figure 4 This is a comparison of the absorbance of several different inorganic ions in Experimental Example 2 of the construction method and application of the MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor of the present invention. Detailed Implementation

[0033] Example 1

[0034] A method for constructing a colorimetric sensor for persulfate activated by MOF-based nanozymes includes the following steps:

[0035] S1. Preparation of MOFs-based nanozyme PCN-222(Fe): 70 mg of ZrCl2 powder, 50 mg of TCIPP(Fe) powder and 2.7 g of benzoic acid powder were dissolved in 8 mL of N,N-diethylformamide. After ultrasonic mixing and dispersion for 30 min, the mixture was placed at 120 °C and allowed to stand for 48 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 9500 rpm. The centrifuged solid product was washed twice with N,N-dimethylformamide and twice with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe) powder was obtained.

[0036] S2. Preparation of MOFs-based nanozyme PCN-222(Fe)-3F: 60 mg of MOFs-based nanozyme PCN-222(Fe) powder obtained in step S1 was dissolved in 2.4 mL of N,N-diethylformamide, and 0.24 mmol of trifluoroacetic acid solution was added simultaneously. After stirring and mixing, the mixture was allowed to stand at 70 °C for 24 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 9500 rpm. The centrifuged solid product was washed three times with N,N-dimethylformamide and then three times with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe)-3F powder was obtained.

[0037] The concentrations of N,N-dimethylformamide and N,N-diethylformamide were 99.8%.

[0038] S3. Construction of a colorimetric sensor system for PFOS detection using MOF-based nanozyme-activated persulfate: 850 μL of 0.2 mol / L acetate buffer (acetate-sodium acetate buffer, pH 3.5) was added, followed by 50 μL of an aqueous solution of 400 mg / L MOF-based nanozyme PCN-222(Fe)-3F powder obtained in step S2. Then, 50 μL of a 2 mmol / L solution of 3,3',5,5'-tetramethylbenzidine was added as the reaction mixture. For the base solution, several portions of the reaction base solution were added one-to-one with 50 μL of PFOS solution of varying concentrations. The mixture was vortexed for 45 s, and then one-to-one with 50 μL of 0.5 mmol / L persulfate solution was added to each, forming several reaction systems. These systems served as PFASs colorimetric sensors. The reactions were carried out at room temperature for 30 min. After filtering each reaction system, the absorbance of the reaction solution was measured at a wavelength of 652 nm. The molar concentrations of the PFOS solutions in the gradient were 0 μmol / L, 0.1 μmol / L, and 0.2 μmol / L, respectively. The concentrations of PFOS were 0.4 μmol / L, 0.6 μmol / L, 0.8 μmol / L, 1 μmol / L, 1.5 μmol / L, 2 μmol / L, 4 μmol / L, 6 μmol / L, 8 μmol / L, 10 μmol / L, 15 μmol / L, 20 μmol / L, and 25 μmol / L. A 0.22 μm filter was used to filter the reaction system. A PFOS concentration-absorbance standard curve was constructed with the concentration of the PFOS solution on the x-axis and absorbance on the y-axis. The specific method is as follows: the absorbance of the reaction system without PFOS solution at a wavelength of 652 nm is used as the standard absorbance. At the same time, the absorbance of each gradient concentration of PFOS solution obtained in step S3 at a wavelength of 652 nm is compared with the standard absorbance to obtain the difference in absorbance of the reaction system under each gradient concentration of PFOS solution. The concentration of PFOS solution is used as the abscissa and the difference in absorbance of the reaction system under each gradient concentration of PFOS solution is used as the ordinate to construct a PFOS concentration-absorbance standard curve, and the detection limit of PFOS is calculated to be 30.1 nM.

[0039] S4. Actual Water Body Detection: Take 50 μL of actual natural water body, prepare 1 mL of reaction base solution according to the method in step S3, add the actual water body to the reaction base solution, vortex for 45 s, then add 50 μL of persulfate solution with a molar concentration of 0.5 mmol / L to form a reaction system. React at room temperature for 30 min. After filtering the reaction system, take the reaction solution for absorbance detection at a wavelength of 652 nm. Compare the detected absorbance of the actual water body with the standard absorbance to obtain the difference in absorbance of the actual water body. Compare the difference in absorbance of the actual water body with the PFOS concentration-absorbance standard curve to obtain the concentration of PFOS solution in the actual water body.

[0040] Example 2

[0041] The difference between this embodiment and Embodiment 1 is that:

[0042] S1. Preparation of MOFs-based nanozyme PCN-222(Fe): 60 mg of ZrCl2 powder, 40 mg of TCIPP(Fe) powder and 2.5 g of benzoic acid powder were dissolved in 6 mL of N,N-diethylformamide. After ultrasonic mixing and dispersion for 30 min, the mixture was allowed to stand at 110 °C for 40 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 9000 rpm. The centrifuged solid product was washed three times with N,N-dimethylformamide and then three times with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe) powder was obtained.

[0043] S2. Preparation of MOFs-based nanozyme PCN-222(Fe)-3F: 50 mg of MOFs-based nanozyme PCN-222(Fe) powder obtained in step S1 was dissolved in 2 mL of N,N-diethylformamide, and 0.2 mmol of trifluoroacetic acid solution was added. After stirring and mixing, the mixture was allowed to stand at 60 °C for 20 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 9000 rpm. The centrifuged solid product was washed 3 times with N,N-dimethylformamide and then 3 times with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe)-3F powder was obtained.

[0044] S3. Construction of a colorimetric sensor system for PFOS detection using MOFs-based nanozyme-activated persulfate: 800 μL of 0.2 mol / L acetate buffer (acetic acid-sodium acetate buffer, pH 3.5) was added, followed by 40 μL of an aqueous solution of the MOFs-based nanozyme PCN-222(Fe)-3F powder obtained in step S2 (400 mg / L). Then, 40 μL of 2 mmol / L 3,3',5,5'-tetramethylbenzidine solution was added as the reaction base solution. Several portions of the reaction base solution were then added to 50 μL of PFOS solution at gradient concentrations, vortexed for 30 s, and then 40 μL of 0.5 mmol / L persulfate solution was added to each, forming several reaction systems as PFOS colorimetric sensors. The reaction was carried out at room temperature for 20 min. After filtering each reaction system, the absorbance of the reaction solution was measured.

[0045] S4. Actual water body detection: Take 40 μL of actual water body in nature, prepare 1 mL of reaction base solution according to the method in step S3, add actual water body to the reaction base solution, vortex for 30 s, then add 40 μL of persulfate solution with a molar concentration of 0.5 mmol / L to form a reaction system, and react for 20 min at room temperature.

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is that:

[0048] S1. Preparation of MOFs-based nanozyme PCN-222(Fe): 80 mg of ZrCl2 powder, 60 mg of TCIPP(Fe) powder and 3 g of benzoic acid powder were dissolved in 10 mL of N,N-diethylformamide. After ultrasonic mixing and dispersion for 30 min, the mixture was placed at 130 °C and allowed to stand for 50 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 10,000 rpm. The centrifuged solid product was washed twice with N,N-dimethylformamide and twice with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe) powder was obtained.

[0049] S2. Preparation of MOFs-based nanozyme PCN-222(Fe)-3F: 70 mg of MOFs-based nanozyme PCN-222(Fe) powder obtained in step S1 was dissolved in 3 mL of N,N-diethylformamide, and 0.3 mmol of trifluoroacetic acid solution was added. After stirring and mixing, the mixture was allowed to stand at 80 °C for 30 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone. The centrifugation speed was 10,000 rpm. The centrifuged solid product was washed twice with N,N-dimethylformamide and twice with acetone. After vacuum drying, MOFs-based nanozyme PCN-222(Fe)-3F powder was obtained.

[0050] S3. Construction of a colorimetric sensor system for PFOS detection using MOFs-based nanozyme-activated persulfate: 900 μL of 0.2 mol / L acetate buffer (acetic acid-sodium acetate buffer, pH 3.5) was added, followed by 80 μL of an aqueous solution of the MOFs-based nanozyme PCN-222(Fe)-3F powder obtained in step S2 (400 mg / L). Then, 80 μL of 2 mmol / L 3,3',5,5'-tetramethylbenzidine solution was added as the reaction base solution. Several portions of the reaction base solution were then added to 50 μL of PFOS solution at gradient concentrations, vortexed for 60 s, and then 80 μL of 0.5 mmol / L persulfate solution was added to each, forming several reaction systems as PFOS colorimetric sensors. The reaction was carried out at room temperature for 40 min. After filtering each reaction system, the absorbance of the reaction solution was measured.

[0051] S4. Actual water body detection: Take 80 μL of actual water body in nature, prepare 1 mL of reaction base solution according to the method in step S3, add actual water body to reaction base solution, vortex for 60 s, then add 80 μL of persulfate solution with a molar concentration of 0.5 mmol / L to form a reaction system, and react for 40 min at room temperature.

[0052] Example 4

[0053] The MOF-based nanozyme-activated persulfate PFASs colorimetric sensor constructed using the method described in Example 1 is applied to the on-site detection of actual water bodies in nature. 1 mL of the reaction base solution from step S3 and 50 μL of a 0.5 mmol / L persulfate solution are evenly spread on the surface of a test strip. 50 μL of actual water is added to the test strip using a pipette, causing a change in absorbance. This change in absorbance is measured colorimetrically using a portable UV spectrophotometer. The absorbance of the actual water is then compared with a standard absorbance to obtain the difference. This difference is then compared with a PFOS concentration-absorbance standard curve to determine the concentration of PFOS solution in the actual water.

[0054] Experimental Example 1

[0055] To verify the feasibility of the method of the present invention, a spiking experiment was conducted to verify the method in Example 1 of the present invention. First, based on the method parameters in step S3 of Example 1, we obtained the absorbance of the PFOS solutions with gradient concentrations at various wavelengths, such as... Figure 2 As shown, a PFOS concentration-absorbance standard curve was subsequently obtained based on the method parameters in step S4 of Example 1, relating the PFOS solution concentration at 652 nm wavelength to the difference in absorbance of the reaction system at various gradient concentrations of PFOS solutions. Figure 3 As shown, Figure 2 and 3 As can be seen, the MOFs-based nanozyme-activated persulfate PCN-222(Fe)-3F powder of this invention exhibits different absorbance responses to different PFOS concentrations, and the absorbance at 652 nm increases linearly with increasing PFOS concentration. Therefore, quantitative analysis of PFOS concentration in actual water bodies can be achieved based on absorbance changes.

[0056] Subsequently, we conducted spiked experiments using real water samples. Samples from the Yangtze River, Xiaguan Bridge, Qinhuai River, and tap water were tested, with PFOS solution added to achieve concentrations of 2.5 μmol / L and 5 μmol / L in the different water samples, respectively. The results, as shown in Table 1, indicate that the recoveries of PFOS in natural water bodies at concentrations of 2.5 μmol / L and 5 μmol / L remained between 90% and 119%. A recovery rate between 80% and 120% indicates good detection results. This demonstrates the ability to detect and analyze PFOS in real water bodies, with a detection limit as low as 30.1 nM.

[0057] Table 1. Application of the sensor in Example 1 for detecting actual water bodies.

[0058] N＝3 2.5μM Recovery rate 5μM Recovery rate Yangtze 2.49-2.53 99.9％-101％ 4.95-5.69 98.9％-114％ Xiaguan Bridge 2.70-2.75 108％-110％ 5.24-5.88 104％-117％ Qinhuai River 2.74-2.92 108％-116％ 5.24-5.88 104％-117％ tap water 2.24-2.98 89.7％-119％ 4.94-5.43 98.8％-108％

[0059] Experiment Example 2

[0060] To verify the feasibility of the method of the present invention, experiments with different ion absorbances were conducted on the method in Example 1 of the present invention, and as follows... Figure 4 Several different inorganic ion substitutions for PFOS solution were added to the reaction system in Example 1, and the absorbance values ​​of each reaction system were measured according to the steps in Example 1. The concentration of the PFOS solution was 5 μM, and the concentration of the other inorganic ion solutions was 50 μM. It can be observed that... Figure 4 The different inorganic ions shown did not cause significant changes in the absorbance of the colorimetric sensor. This demonstrates that the colorimetric sensor system in Example 1 exhibits good selectivity for PFOS.

Claims

1. A method for constructing a MOF-based nanozyme-activated persulfate PFAS colorimetric sensor, characterized in that, Includes the following steps: S1. Preparation of MOFs-based nanozyme PCN-222(Fe): 60-80 mg of ZrCl2 powder, 40-60 mg of TCIPP(Fe) powder and 2.5-3 g of benzoic acid powder were dissolved in 6-10 mL of N,N-diethylformamide. After ultrasonic mixing and dispersion, the mixture was placed at 110-130℃ and allowed to react for 40-50 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone, and then dried under vacuum to obtain MOFs-based nanozyme PCN-222(Fe) powder. S2. Preparation of MOFs-based nanozyme PCN-222(Fe)-3F: 50-70 mg of MOFs-based nanozyme PCN-222(Fe) powder obtained in step S1 was dissolved in 2-3 mL of N,N-diethylformamide, and 0.2-0.3 mmol of trifluoroacetic acid solution was added simultaneously. After stirring and mixing, the mixture was allowed to stand at 60-80℃ for 20-30 h. After centrifugation, the solid product was washed with N,N-dimethylformamide and acetone, and then dried under vacuum to obtain MOFs-based nanozyme PCN-222(Fe)-3F powder. S3. Construction of a colorimetric sensor system for PFOS detection using MOF-based nanozyme-activated persulfate: 800–900 μL of 0.2 mol / L acetate buffer was added, followed by 40–80 μL of an aqueous solution of 400 mg / L MOF-based nanozyme PCN-222(Fe)-3F powder obtained in step S2. Then, 40–80 μL of 2 mmol / L 3,3',5,5'-tetramethylbenzidine solution was added as the reaction base solution. Several portions of the reaction base solution were then added to corresponding solutions at gradient concentrations of 50 mg / L. μL of PFOS solution was vortexed for 30–60 s, and then 40–80 μL of 0.5 mmol / L persulfate solution was added to each system to form several reaction systems, which were used as PFOS colorimetric sensors. The reaction was carried out at room temperature for 20–40 min. After filtering each reaction system, the absorbance of the reaction solution was measured at a wavelength of 652 nm. The gradient concentration range of PFOS solution was 0–25 μmol / L. A PFOS concentration-absorbance standard curve was constructed with the concentration of PFOS solution as the x-axis and the absorbance as the y-axis. S4. Actual Water Body Detection: Take 40–80 μL of actual natural water body and prepare 1 mL of reaction base solution according to the method in step S3. Add the actual water body to the reaction base solution and vortex for 30–60 s. Then add 40–80 μL of persulfate solution with a molar concentration of 0.5 mmol / L to form a reaction system. React at room temperature for 20–40 min. After filtering the reaction system, take the reaction solution for absorbance detection at a wavelength of 652 nm. Compare the detected absorbance of the actual water body with the standard absorbance to obtain the difference in absorbance of the actual water body. Compare the difference in absorbance of the actual water body with the PFOS concentration-absorbance standard curve to obtain the concentration of PFOS solution in the actual water body.

2. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, The concentrations of N,N-dimethylformamide and N,N-diethylformamide in steps S1 and S2 are ≥99.5%.

3. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, In steps S1 and S2, the centrifugation speed is 9000-10000 rpm. The solid product separated by centrifugation is washed 2-3 times with N,N-dimethylformamide and then 2-3 times with acetone.

4. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, The ultrasonic mixing and dispersion treatment time in step S1 is 30 minutes.

5. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, In step S3, the acetate buffer is an acetate-sodium acetate buffer with a pH of 3.

5.

6. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, The filter used for filtering the reaction system in step S3 is a 0.22 μm filter.

7. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, In step S3, the molar concentrations of the PFOS solutions with gradient concentrations are 0 μmol / L, 0.1 μmol / L, 0.2 μmol / L, 0.4 μmol / L, 0.6 μmol / L, 0.8 μmol / L, 1 μmol / L, 1.5 μmol / L, 2 μmol / L, 4 μmol / L, 6 μmol / L, 8 μmol / L, 10 μmol / L, 15 μmol / L, 20 μmol / L, and 25 μmol / L, respectively, constructing a PFOS concentration-absorption... The specific method for obtaining the photometric standard curve is as follows: the absorbance of the reaction system without PFOS solution at a wavelength of 652 nm is used as the standard absorbance. At the same time, the absorbance of each gradient concentration of PFOS solution obtained in step S3 at a wavelength of 652 nm is compared with the standard absorbance to obtain the difference in absorbance of the reaction system under each gradient concentration of PFOS solution. The PFOS concentration-absorbance standard curve is constructed with the concentration of PFOS solution as the abscissa and the difference in absorbance of the reaction system under each gradient concentration of PFOS solution as the ordinate.

8. The method for constructing a MOF-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 1, characterized in that, The room temperature is 20–30°C.

9. The application of the MOF-based nanozyme-activated persulfate PFASs colorimetric sensor constructed according to any one of claims 1 to 8, characterized in that, The PFASs colorimetric sensors are applied to the on-site detection of actual water bodies in nature.

10. The application of the MOFs-based nanozyme-activated persulfate PFASs colorimetric sensor according to claim 9, characterized in that, The application method is as follows: Take 1 mL of the reaction base solution from step S3 and 50 μL of 0.5 mmol / L persulfate solution and spread them evenly on the surface of the test strip. Use a pipette to take 50 μL of actual water and add it to the surface of the test strip, so that the surface of the test strip shows a change in absorbance. The change in absorbance of the actual water on the surface of the test strip is measured colorimetrically using a portable ultraviolet spectrophotometer to obtain the absorbance of the actual water. Compare the absorbance of the actual water with the standard absorbance to obtain the difference in absorbance of the actual water. Compare the detected difference in absorbance of the actual water with the PFOS concentration-absorbance standard curve to obtain the concentration of PFOS solution in the actual water.

Images