Coumarin-based fluorescent compounds, fluorescent-sensitive membranes, their preparation methods and applications

Abstract

This application relates to a coumarin-based fluorescent compound, a fluorescence-sensitive membrane, its preparation method, and its application. The coumarin-based fluorescent compound provided in this application has the structure shown in Formula I. The fluorescence-sensitive membrane provided in this application comprises a chitosan-based membrane and the aforementioned coumarin-based fluorescent compound. The fluorescence-sensitive membrane provided in this application is sensitive to heavy metal ions in water, especially Pb. 2+ It has an enrichment effect, eliminating the need for sample preparation during detection and adsorption, and can effectively improve detection and adsorption efficiency.

Description

Technical Field

[0001] This application belongs to the field of thin-film sensitive materials and the technology of heavy metal detection and removal, and particularly relates to a coumarin-based fluorescent compound and a fluorescent sensitive membrane for detecting and removing lead ions in water. This application also relates to a method for preparing the fluorescent sensitive membrane. Background Technology

[0002] Lead ions (Pb) 2+ Groundwater pollution is one of the major problems. Non-degradable phosphorus (Pb) in water... 2+ Not only does it harm ecosystems, but it can also accumulate in water and enter the human body, posing a serious threat to human health. Its accumulation can cause nerve damage, kidney damage, and muscle paralysis. Therefore, there is an urgent need to develop a suitable technology for the treatment of Pb in groundwater. 2+ To conduct sensitive on-site monitoring and efficient removal to protect human health.

[0003] Traditional Pb 2+ Detection methods include atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), and capillary electrophoresis (CE). These methods offer advantages such as high specificity and mature instrumentation, but their cumbersome operation, complex instrumentation, and difficult pretreatment processes limit their ability to achieve rapid and sensitive detection. Fluorescence methods have become a very powerful technique, enabling rapid and sensitive detection of analytes based on changes in fluorescence signals. Furthermore, fluorescence sensors offer advantages such as low cost, small size, easy integration, and real-time monitoring, making them the most widely used and researched sensors. However, most small organic molecule fluorescence sensors are in powder form, potentially causing secondary pollution to water bodies, and require complex post-processing; most also only detect Pb. 2+ The single function still presents significant challenges in practical applications. Summary of the Invention

[0004] To address the problems in the prior art, this application provides a coumarin-based fluorescent compound and a fluorescent sensitive membrane, along with their preparation method and applications. The fluorescent sensitive membrane of this application can be used for ultrasensitive detection and efficient removal of metal ions, especially lead ions, in real water samples.

[0005] In a first aspect, this application provides a coumarin-based fluorescent compound with the structure shown in Formula I:

[0006]

[0007] In Formula I, X is selected from O or S, and L is absent or selected from C1-C6 alkylene groups;

[0008] R1 and R2 may be the same or different, and each is independently selected from C1-C6 alkyl groups;

[0009] R3, R4, R5, R6, R7, R8 and R9 are each independently selected from hydrogen, halogens or C1-C6 alkyl groups.

[0010] In some embodiments, X is selected from O, L is absent or selected from C1-C4 alkylene groups, such as methylene, ethylene, propylene, isopropylene, butylene, isobutylene or tert-butylene.

[0011] In some embodiments, R1 and R2 may be the same or different, each independently selected from C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0012] In some embodiments, R3, R4, R5, R6, R7, R8 and R9 are each independently selected from hydrogen, fluorine, chlorine, bromine or C1-C4 alkyl groups.

[0013] In some embodiments, R3, R4, R5, and R6 are the same and are selected from hydrogen, fluorine, chlorine, bromine, or C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0014] In some embodiments, R7, R8, and R9 are the same and are selected from hydrogen, fluorine, chlorine, bromine, or C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0015] In some embodiments, the coumarin-based fluorescent compound is selected from the following compounds:

[0016]

[0017] In a second aspect, this application provides a fluorescent sensitive membrane comprising a chitosan-based membrane and the coumarin-based fluorescent compound described in the first aspect.

[0018] This application describes the preparation of a fluorescently sensitive membrane using coordination and electrostatic adsorption between a flexible chitosan-based membrane and a fluorophore (coumarin-based fluorescent compound). This membrane possesses a large number of interconnected pores, providing convenient and rapid mass transfer channels between the membrane and its surroundings, and also increasing the adhesion between the membrane and metal ions, especially Pb. 2+ The contact area between them is crucial for achieving sensitive on-site detection and efficient adsorption of heavy metal ions, especially Pb. 2+ Key factors.

[0019] In some embodiments, the chitosan-based membrane is bonded to the coumarin-based fluorescent compound via chemical bonds and / or intermolecular forces.

[0020] In some embodiments, the loading amount of the coumarin-based fluorescent compound on the chitosan-based membrane is 1 mg / g to 30 mg / g, for example, 1.5 mg / g, 2 mg / g, 2.5 mg / g, 3 mg / g, 3.5 mg / g, 4 mg / g, 4.5 mg / g, 5 mg / g, 5.5 mg / g, 6 mg / g, 6.5 mg / g, 7 mg / g, 7.5 mg / g, 8 mg / g, 8.5 mg / g, 9 mg / g, 9.5 mg / g, 10 mg / g, 11 mg / g, 12 mg / g, 13 mg / g, 14 mg / g, 15 mg / g, 16 mg / g, 17 mg / g, 18 mg / g, 19 mg / g, 20 mg / g, 22 mg / g, 24 mg / g, 26 mg / g, or 28 mg / g. In some embodiments, the coumarin-based fluorescent compound is loaded at an amount of 2.5 mg / g to 4.3 mg / g on the chitosan-based membrane.

[0021] In some embodiments, the coumarin-based fluorescent compound is loaded onto the chitosan-based membrane at a rate greater than 1 mg / g, for example, 50 mg / g, 150 mg / g, 200 mg / g, 250 mg / g, or 300 mg / g.

[0022] In some embodiments, the thickness of the fluorescent sensing film is 10 μm-50 μm, for example, 13 μm, 15 μm, 17 μm, 20 μm, 23 μm, 25 μm, 27 μm, 30 μm, 33 μm, 35 μm, 37 μm, 40 μm, 43 μm, 45 μm, or 47 μm. In some embodiments, the thickness of the fluorescent sensing film is 15 μm-35 μm. In some embodiments, the thickness of the fluorescent sensing film is 16.70 μm-32.54 μm.

[0023] Thirdly, this application provides a method for preparing a fluorescent sensitive film, which includes the following steps:

[0024] S1: The compounds shown in formula A and formula B are subjected to a first reaction in a solvent to obtain the reaction products;

[0025] S2: The reaction product of step S1 is reacted with a solution containing a chitosan-based membrane in a second reaction;

[0026]

[0027] In formula A, R1 and R2 may be the same or different, and each is independently selected from C1-C6 alkyl groups; R3, R4, R5 and R6 are each independently selected from hydrogen, halogen or C1-C6 alkyl groups.

[0028] In formula B, X is selected from O or S, L is absent or selected from C1-C6 alkylene groups; R7, R8 and R9 are each independently selected from hydrogen, halogen or C1-C6 alkyl groups.

[0029] In some embodiments, in Formula A, R1 and R2 may be the same or different, each independently selected from C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0030] In some embodiments, in Formula A, R3, R4, R5 and R6 are each independently selected from hydrogen, fluorine, chlorine, bromine or C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl.

[0031] In some embodiments, in formula B, X is selected from O, and L is absent or selected from C1-C4 alkylene groups, such as methylene, ethylene, propylene, isopropylene, butylene, isobutylene, or tert-butylene.

[0032] In some embodiments, in Formula B, R7, R8 and R9 are each independently selected from hydrogen, fluorine, chlorine, bromine or C1-C4 alkyl groups, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert-butyl.

[0033] In some embodiments, the compound represented by formula A is selected from the following compounds:

[0034] (7-(diethylamino)coumarin-3-carboxaldehyde),

[0035]

[0036] In some embodiments, the compound represented by formula B is selected from the following compounds:

[0037] (2-Furfural hydrazide)

[0038] In some embodiments, in step S1, the solvent is selected from C1-C5 alcohols. In some embodiments, the solvent is selected from methanol or ethanol.

[0039] In some embodiments, in step S1, the molar ratio of the compound represented by formula A to the compound represented by formula B is (0.8-1.2):1, for example, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1 or 1.15:1.

[0040] In some embodiments, in step S1, the temperature of the first reaction is 50°C-100°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, or 85°C. In some embodiments, the temperature of the first reaction is 60°C-90°C.

[0041] In some embodiments, the first reaction time is 5h-30h, for example 7h, 10h, 13h, 15h, 17h, 20h, 23h, 25h, or 27h. In some embodiments, the first reaction time is 10h-20h.

[0042] In some embodiments, the reaction product is recrystallized and then subjected to a second reaction with a solution containing a chitosan-based membrane. In some embodiments, a C1-C5 alcohol, preferably methanol or ethanol, is used for recrystallization.

[0043] In some embodiments, in step S2, the mass ratio of the reaction product to chitosan is 0.001-0.5, for example, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, or 0.45. In some embodiments, the mass ratio of the reaction product to chitosan is 0.005-0.1. In some embodiments, the mass ratio of the reaction product to chitosan is 0.005-0.015.

[0044] In some embodiments, in step S2, the temperature of the second reaction is 5°C-35°C, for example, 10°C, 15°C, 20°C, 25°C, or 30°C. In some embodiments, the temperature of the second reaction is 10°C-30°C. In some embodiments, the temperature of the second reaction is room temperature.

[0045] In some embodiments, in step S2, the second reaction time is 5h-30h, for example, 7h, 10h, 13h, 15h, 17h, 20h, 23h, 25h, or 27h. In some embodiments, the second reaction time is 10h-20h.

[0046] In some embodiments, in step S2, the solution containing the chitosan-based membrane is obtained by:

[0047] Chitosan is dissolved in an acidic solution to obtain an acidic chitosan solution; the acidic chitosan solution is mixed with a polyol and then subjected to a prepolymerization reaction to obtain the solution containing the chitosan-based membrane.

[0048] In some embodiments, the acid solution is selected from one or more of acetic acid, lactic acid, and propionic acid.

[0049] In some embodiments, the acid solution contains 0.5-5% by mass, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5% by mass. In some embodiments, the acid content is 0.5-2% by mass.

[0050] In some embodiments, the polyol is selected from one or more C2-C6 polyols. In some embodiments, the polyol is selected from ethylene glycol or glycerol.

[0051] In some embodiments, the mass ratio of chitosan to the total volume of the acid solution and polyol is (1-4) g:100 mL, for example, 1.3 g:100 mL, 1.5 g:100 mL, 1.7 g:100 mL, 2.0 g:100 mL, 2.3 g:100 mL, 2.5 g:100 mL, 2.7 g:100 mL, 3.0 g:100 mL, 3.3 g:100 mL, 3.5 g:100 mL, or 3.7 g:100 mL. In some embodiments, the mass ratio of chitosan to the total volume of the acid solution and polyol is (2-3) g:100 mL.

[0052] In some embodiments, the volume ratio of the acid solution to the polyol is (95-99):(1-5), for example, 98:2, 97:3 or 96:4.

[0053] In some embodiments, the preparation method further includes step S3: evaporating and cooling the reaction product of step S2 to obtain a rough film, and washing the rough film to obtain the fluorescence-sensitive film.

[0054] In some embodiments, the evaporation temperature is 40°C-65°C, for example 45°C, 50°C, 55°C or 60°C.

[0055] In some embodiments, the washing includes washing the coarse film with water until it becomes neutral.

[0056] In some embodiments, the preparation of the fluorescent sensitive film includes the following steps:

[0057] (1) A fluorophore was prepared by using 7-(diethylamino)coumarin-3-carboxaldehyde, 2-furanoylhydrazide and ethanol;

[0058] (2) Stir chitosan and acetic acid until the chitosan is completely dissolved; then add glycerol and prepolymerize at room temperature to obtain a chitosan-based film solution;

[0059] (3) Add the above fluorophores to the chitosan-based membrane solution and react;

[0060] (4) Evaporate and cool the solution after the reaction to obtain a rough film. Rinse the rough film with water, preferably until it is neutral, to obtain the fluorescent sensitive film.

[0061] In some embodiments, the method for preparing the fluorescence-sensitive film includes the following specific steps:

[0062] 1) Preparation of the fluorophore CM-L:

[0063] 7-(diethylamino)coumarin-3-carboxaldehyde (preferably 245 mg, 1 mmol) and 2-furanoylhydrazide (preferably 126 mg, 1 mmol) were dissolved in ethanol (preferably 20 mL), and the mixture was stirred at a temperature of, for example, 85 °C for, for example, 12 h, and then rotary distilled to obtain a brown crude product. The product was recrystallized from ethanol to obtain the fluorophore CM-L.

[0064] 2) Preparation of an ultrasensitive membrane for detecting lead ions in water:

[0065] Chitosan (preferably 1.75 g) and 1% acetic acid (preferably 97 mL) were added to a single-necked flask and stirred until the chitosan was completely dissolved. Then, glycerol (preferably 3 mL) was added and prepolymerized at room temperature for, for example, 4 h, to obtain a chitosan-based film solution. Finally, the fluorophore CM-L (e.g., 17 mg) was added, and the reaction was continued for, for example, 12 h. The solution was poured into a glass dish and evaporated and cooled to obtain a rough film. The rough film was washed with water until neutral (three times) to obtain a CM-L / CG film.

[0066] Thirdly, this application provides the application of the coumarin-based fluorescent compound described in the first aspect, or the fluorescent sensitive membrane described in the second aspect, or the fluorescent sensitive membrane prepared by the preparation method described in the third aspect, in the detection and / or removal of heavy metal ions, especially lead ions, in water.

[0067] Compared with the prior art, the beneficial effects of this application are as follows:

[0068] 1) A novel CM-L / CG thin-film quenching fluorescent probe was prepared by using the coordination and electrostatic adsorption between a flexible chitosan-based membrane and a fluorophore.

[0069] 2) CM-L / CG membranes have strong adsorption capacity, good hydrophilicity and water stability, and can enrich lead ions in water. No sample preparation is required for detection and adsorption, which can improve detection efficiency.

[0070] 3) The materials used to prepare CM-L / CG films are inexpensive, do not cause secondary pollution to the environment, and are easy to integrate, and can be applied to the detection and removal of actual groundwater samples. Attached Figure Description

[0071] Figure 1 This is a scanning electron microscope (SEM) image of the CG base film in Embodiment 1 of the present invention.

[0072] Figure 2 This is a scanning electron microscope (SEM) image of the CM-L / CG thin film in Example 1.

[0073] Figure 3 This is a linear titration diagram of the CM-L / CG thin film in Example 1.

[0074] Figure 4 This is a graph showing the selectivity and anti-interference properties of the CM-L / CG film for cations in Example 1.

[0075] Figure 5 This is a graph showing the selectivity and anti-interference performance of the CM-L / CG thin film for anions in Example 1.

[0076] Figure 6 This is the kinetic adsorption curve of the CM-L / CG thin film in Example 2.

[0077] Figure 7 This is the isothermal adsorption curve of the CM-L / CG thin film in Example 2. Detailed Implementation

[0078] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and technologies have also been described in numerous publications.

[0079] The present application will be further described below through specific embodiments.

[0080] Example 1

[0081] (1) 7-(diethylamino)coumarin-3-carboxaldehyde (245 mg, 1 mmol) and 2-furanoylhydrazide (126 mg, 1 mmol) were dissolved in ethanol (20 mL) to obtain a mixed solution. The mixed solution was stirred at 85 °C for 12 h, and then rotary distilled to obtain a brown crude product. The crude product was recrystallized from ethanol to obtain the fluorophore CM-L. Yield: 291 mg; Yield: 82%.

[0082] 1 H NMR (400MHz, DMSO-d6) δ: 11.91 (s, 1H), 8.48 (s, 1H), 8.33 (s, 1H), 7.93 (s, 1H), 7.64 (d, J = 9.0Hz, 1H), 7.30 (s, 1H) ), 6.75 (dd, J = 9.1, 2.4Hz, 1H), 6.69 (s, 1H), 6.56 (d, J = 2.6Hz, 1H), 3.45 (q, J = 7.0Hz, 4H), 1.13 (d, J = 6.9Hz, 6H).

[0083] 13 C NMR(101MHz,DMSO-d6)δ:161.29,156.57,153.95,151.35,146.60,145.89,142.3 9,138.69,130.92,114.83,112.51,112.10,109.74,108.09,96.39,44.26,12.38.

[0084] ESI-MS (m / z): Theoretical value: 353.1376. Measured value: 353.3166.

[0085] (2) Chitosan (1.75 g) and 1% acetic acid (97 mL) were added to a single-necked flask and stirred until the chitosan was completely dissolved. Then, glycerol (3 mL) was added and prepolymerized at room temperature for 4 h to obtain a chitosan-based membrane solution. Finally, fluorophore CM-L (17 mg) was added, and the reaction was continued for 12 h. The reaction solution was poured into a glass dish and evaporated and cooled to obtain a rough membrane. After rinsing the rough membrane three times with water, a fluorescently sensitive membrane (CM-L / CG film) was obtained.

[0086] Figure 1 This is a scanning electron microscope image of the CG film. The CG film is obtained by freeze-drying the chitosan-based film solution obtained in step (2).

[0087] Figure 2 This is a scanning electron microscope image of the synthesized CM-L / CG thin film. Figure 2 As shown, the CM-L / CG film has a honeycomb structure, with the fluorophores CM-L and CG intertwined and cross-linked. The prepared CM-L / CG film is more dense and uniform than the independent CG film.

[0088] Example 2

[0089] (1) The preparation of the fluorophore CM-L is the same as in Example 1.

[0090] (2) Chitosan (1.75 g) and 1% acetic acid (97 mL) were added to a single-necked flask and stirred until the chitosan was completely dissolved. Then, glycerol (3 mL) was added and prepolymerized at room temperature for 4 h to obtain a chitosan-based membrane solution. Finally, fluorophore CM-L (500 mg) was added, and the reaction was continued for 12 h. The reaction solution was poured into a glass dish and evaporated and cooled to obtain a rough membrane. After rinsing the rough membrane three times with water, a fluorescently sensitive membrane (CM-L / CG film) was obtained.

[0091] Application examples

[0092] Application Example 1 - Detection of Solid-State Fluorescence in CM-L / CG Thin Films

[0093] The CM-L / CG film prepared in Example 1 was cut into 6mm × 6mm square film sheets. One of the film sheets was fixed onto a glass slide and blotted dry with filter paper. 50mL of deionized water was placed in a beaker, and the glass slide containing the film sheet was placed in the beaker. After soaking for 2-5 minutes, the film sheet was removed, and the surface moisture was first blotted dry with filter paper. Then, 10μL of deionized water was added to the film sheet to ensure a consistent water content. The film sheet was pressed firmly onto the glass slide with a quartz plate, and the initial fluorescence intensity of the film sheet was measured using a fluorescence spectrophotometer.

[0094] The quartz slide was then removed, and the slide with the thin film fixed on it was placed into 20 mL of the test solution. Then, 1 μL of a solution containing Pb was added to the test solution. 2+ A solution of ions (concentration 100 ppm) was mixed thoroughly to obtain a test solution with a concentration of 5 ppb. The glass slide with the immobilized film was immersed in the mixed solution for 2-5 minutes, then removed. The surface moisture of the film was first blotted dry with filter paper, and then 10 μL of secondary water was added to the film to ensure a consistent water content. The film was then pressed firmly with another quartz plate, and the change in fluorescence intensity was detected using a fluorescence spectrophotometer.

[0095] The detection method for test solutions of other concentrations (10 ppb, 15 ppb, 20 ppb, 25 ppb, 30 ppb, 35 ppb, 40 ppb) is the same as that for the test solution with a concentration of 5 ppb. Finally, the results are obtained. Figure 3 The corresponding concentration-fluorescence intensity standard working curve is shown below.

[0096] from Figure 3 The standard curve shows that as the Pb in the test solution increases... 2+ As the ion concentration increases, the fluorescence intensity of the sensitive membrane gradually decreases. When Pb... 2+ When the ion concentration is 5 ppb, it contains Pb. 2+ The fluorescence intensity of the ion-sensitive membrane was significantly lower than that of the blank membrane, meaning that Pb was not detected using fluorescence emission spectroscopy. 2+At that time, the actual detection limit of the sensitive membrane prepared by the present invention can be as low as 5 ppb.

[0097] Application Example 2 - Specific recognition (selectivity and anti-interference) of lead ions by CM-L / CG thin film

[0098] First, prepare the following solutions:

[0099] 1) 20 mL of Pb with a concentration of 400 ppb 2+ Solution;

[0100] 2) 20 mL of other metal ion solutions, each with a concentration of 4 ppm (equivalent to 10 times). Other metal ion solutions include KCl solution, MgCl2 solution, AlCl3 solution, CrCl3·3H2O solution, ZnCl2 solution, FeCl3 solution, CuCl2·2H2O solution, CdCl2·2.5H2O solution, HgCl2 solution, NaI solution, Na2SO4 solution, Na2S2O3 solution, Na2S·9H2O solution, NaNO3 solution, NaSCN solution, NaNO2 solution, CH3COONa solution, and NaBr solution.

[0101] The CM-L / CG films prepared in Example 1 were then cut into 6mm × 6mm square films and fixed onto a glass slide. The moisture on the films was absorbed with filter paper, and then 10 μL of deionized water was added to ensure consistent water content. The glass slides containing the films were then immersed in 20 mL of the aforementioned test solution. The initial fluorescence intensity of each 6mm × 6mm square film was first measured, followed by the fluorescence intensity under different ion conditions. Finally, the Pb content was measured. 2+ Fluorescence intensity when coexisting with other ions.

[0102] Figure 4 The graph shows the selectivity and anti-interference properties of the sensitive membrane prepared in Example 1 to cations. Figure 5 The graph shows the selectivity and anti-interference performance of the sensitive membrane prepared in Example 1 for anions. Figure 4 and Figure 5 As can be seen from the comparison of fluorescence intensity changes, only the lead ion solution caused a significant change in the fluorescence intensity of the film, indicating that the sensitive film of the present invention has excellent selectivity and anti-interference ability for lead ions.

[0103] Application Example 3 - Application of CM-L / CG membrane in the detection of actual water samples

[0104] The CM-L / CG film prepared in Example 1 was cut into 6mm × 6mm square films and fixed onto a glass slide. The moisture on the film was absorbed with filter paper, and then 10 μL of secondary water was added to ensure consistent water content. The initial fluorescence intensity of the film was measured first. Then, the glass slides containing the films were immersed in 20 mL of groundwater from three different sites (SK1, SK2, and SK3) that had been filtered through filter paper (microporous membrane, mixed membrane, pore size 0.22 μM). The Pb content in each groundwater sample was determined by the specific concentration of Pb in the sample. 2+ The fluorescence intensity was measured at concentrations of 5, 10 and 20 ppb, and the specific results are shown in Table 1.

[0105] Table 1

[0106]

[0107] Table 1 shows that, under the same conditions, three repetitions yielded a good recovery rate (90.60%-104.70%). Application Example 4: Adsorption of Lead Ions by the CM-L / CG Thin Film.

[0108] First, prepare a solution with a concentration of 500 mg / L. -1 Pb 2+ Stock solution, from stock solution (500mg L) -1 Pb in the dilution and immobilization adsorption experiment 2+ The concentration.

[0109] Cut 0.1g sheets of the CM-L / CG film prepared in Example 2 and immerse them in 50mL of Pb. 2+ Aqueous solution (50 mg / L) -1 In a solution, shake continuously at room temperature to obtain the following result: Figure 6 The adsorption kinetics curves are shown. Application Example 5: Adsorption of lead ions by the CM-L / CG thin film.

[0110] First, prepare a solution with a concentration of 500 mg / L. -1 Pb 2+ Stock solution, from stock solution (500mg L) -1 Pb in the dilution and immobilization adsorption experiment 2+ The concentration.

[0111] Cut 0.1g sheets of the CM-L / CG film prepared in Example 2 and immerse them in 50mL of different initial concentrations (0-400mg / L). -1 Pb 2+ In solution. Shake the mixture for 180 minutes until adsorption reaches equilibrium, to obtain the following... Figure 7 The isothermal adsorption curve is shown.

[0112] The sensitive membrane of this invention has a large number of interconnected pore structures, which not only provides convenient and rapid mass transfer channels between the inside and outside of the membrane, but also increases the membrane's conductivity and Pb content. 2+ The contact area between them is crucial for achieving sensitive on-site detection and efficient adsorption of Pb. 2+ Key factors.

[0113] This CM-L / CG thin film is easily integrated as a solid-state fluorescence sensing platform for Pb. 2+ The ions exhibit enrichment properties and good stability. When the CM-L / CG film is immersed in a solution containing lead ions, a decrease in fluorescence intensity can be detected. The fluorescence excitation wavelength of this film is 405 nm, the emission wavelength is 515 nm, the response time is 2 min, and its detection range is 5–400 ppb, with an actual minimum detection limit of 5.0 ppb.

[0114] Meanwhile, CM-L / CG films for Pb 2+ The ions exhibit excellent adsorption properties. Pb 2+ Isothermal adsorption curves and kinetic data on the CM-L / CG membrane indicate that the adsorption behavior can be well described by Langmuir and pseudo-second-order kinetics. This membrane provides a basis for the simultaneous and sensitive detection and effective removal of Pb. 2+ It provides a multifunctional platform and offers new design strategies for the monitoring and purification of heavy metals in polluted water.

[0115] The preferred embodiments of this application have been described in detail above; however, this application is not limited thereto. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in this application and are all within the protection scope of this application.

Claims

1. The application of a coumarin-based fluorescent compound in the detection and / or removal of lead ions in water. The coumarin-based fluorescent compound is:

2. The application of a fluorescently sensitive membrane in the detection and / or removal of lead ions in water, comprising a chitosan-based membrane and a coumarin-based fluorescent compound, wherein the coumarin-based fluorescent compound is...

3. The application according to claim 2, characterized in that, The chitosan-based membrane is bonded to the coumarin-based fluorescent compound through chemical bonds and / or intermolecular forces.

4. The fluorescent sensitive film according to claim 2, characterized in that, The coumarin-based fluorescent compound is loaded onto the chitosan-based membrane at a rate of 1 mg / g-30 mg / g; and / or The thickness of the fluorescent sensitive film is 10μm-50μm.

5. The fluorescent sensitive film according to claim 2, characterized in that, The coumarin-based fluorescent compound is loaded at an amount of 2.5 mg / g-10 mg / g on the chitosan-based membrane; and / or The thickness of the fluorescent sensitive film is 15μm-35μm.

6. The application according to claim 2, characterized in that, The method for preparing the fluorescent sensitive film includes the following steps: S1: The compounds shown in formula A and formula B are subjected to a first reaction in a solvent to obtain the reaction products; S2: The reaction product of step S1 is reacted with a solution containing a chitosan-based membrane in a second reaction; The compound shown in Formula A is selected from the following compounds: The compound shown in Formula B is selected from the following compounds:

7. The application according to claim 6, characterized in that, In step S1, the solvent is selected from C1-C5 alcohols; and / or The molar ratio of the compound shown in Formula A to the compound shown in Formula B is (0.8-1.2):1; The temperature of the first reaction is 50℃-100℃; and / or The first reaction time is 5h-30h; and / or The reaction product was recrystallized and then subjected to a second reaction with a solution containing a chitosan-based membrane.

8. The application according to claim 7, characterized in that, In step S1, the solvent is selected from methanol or ethanol; and / or The temperature of the first reaction is 60℃-90℃; and / or The first reaction takes 10-20 hours; and / or The reaction product was recrystallized and then subjected to a second reaction with a solution containing a chitosan-based membrane, using methanol or ethanol for recrystallization.

9. The application according to claim 7, characterized in that, In step S2, the mass ratio of the reaction product to chitosan is 0.001-0.5; and / or The temperature of the second reaction is 5℃-35℃; and / or The second reaction takes 5-30 hours; and / or The solution containing the chitosan-based membrane is obtained by the following method: Chitosan is dissolved in an acidic solution to obtain an acidic chitosan solution; the acidic chitosan solution is mixed with a polyol and then subjected to a prepolymerization reaction to obtain the solution containing the chitosan-based membrane.

10. The application according to claim 9, characterized in that, In step S2, the mass ratio of the reaction product to chitosan is 0.005-0.1; and / or The temperature of the second reaction is 10℃-30℃; and / or The second reaction takes 10-20 hours; and / or The acid solution is selected from one or more of acetic acid, lactic acid, and propionic acid; The acid solution contains 0.5-5% acid by mass. The mass ratio of chitosan to the total volume of acid solution and polyol is (1-4) g: 100 mL; The polyol is selected from one or more C2-C6 polyols.

11. The application according to claim 9, characterized in that, In step S2, the mass ratio of the reaction product to chitosan is 0.005-0.015; and / or The temperature of the second reaction is 10℃-30℃; and / or The second reaction takes 10-20 hours; and / or The acid solution is selected from one or more of acetic acid, lactic acid, and propionic acid; The acid solution contains 0.5-2% acid by mass. The mass ratio of chitosan to the total volume of the acid solution and polyol is (2-3) g: 100 mL. The volume ratio of the acid solution to the polyol is (95-99):(1-5); The polyol is selected from ethylene glycol or glycerol.

12. The application according to claim 6, characterized in that, The preparation method further includes step S3: evaporating and cooling the reaction product of step S2 to obtain a crude film, and washing the crude film to obtain the fluorescent sensitive film.

13. The application according to claim 12, characterized in that, The evaporation temperature is 40℃-65℃; The washing process includes washing the coarse film with water until it becomes neutral.

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