Preparation method of a composite membrane for synchronous detection of sediment pollutants and environmental factors

Abstract

The present application relates to the technical field of sediment / soil two-dimensional monitoring, in particular to a preparation method of a composite film for synchronous detection of sediment pollutants and environmental factors. The composite film is designed based on a planar photoelectrode (PO) and a thin film diffusion gradient balance principle. The preparation process includes designing and synthesizing three kinds of fluorescent sensing materials, namely PtTFPP@PSAN, HPTS(ODA)3@PSPVP and BBS@PVDCAN, and two kinds of DGT adsorption materials, namely Nano-ZrO and Nano-Chelex. In the preparation process of the sensing film, the three kinds of fluorescent sensing materials are embedded and fixed in the bottom layer by polyurethane hydrogel D4, and the DGT adsorption materials are embedded and fixed in the surface layer by polyurethane hydrogel D4. With the aid of the sensing film, based on the fluorescent analysis principle, the fluorescence intensity image of the composite film at the sediment or soil contact interface can be obtained in real time, and the DO and pH two-dimensional refined distribution information can be converted through the scale. Then, the composite film is further processed, and the fine distribution information of phosphorus, heavy metals and other pollutants is obtained through thin film color development, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and other fine imaging methods.

Description

Technical Field

[0001] This invention relates to the field of two-dimensional monitoring technology for sediments / soil, specifically to a method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors. Background Technology

[0002] Currently, eutrophication, heavy metal pollution, and aquatic ecosystem degradation caused by nitrogen (N), phosphorus (P) nutrients, and heavy metals such as iron (Fe) and cadmium (Cd) remain among the most pressing issues in my country's lake and reservoir water environment management. With external pollution sources effectively contained, the release of endogenous pollutants from sediments has gradually become the primary cause of water pollution. Sedimentary micro-interfaces are the core units for the distribution, transport, reduction, and reactivation of nutrients and heavy metals, and are a key entry point for in-depth research into the mechanisms of water pollution events. A comprehensive understanding of the biogeochemical processes of nutrients and pollutants at sedimentary micro-interfaces is crucial for elucidating the mechanisms of water pollution events and developing targeted pollution remediation and control strategies. However, sedimentary micro-interfaces are complex, multidimensional systems involving multiple environmental parameters and pollutants, and their interface characteristics and pollutant changes exhibit high spatiotemporal heterogeneity, making micro-interface pollution processes and mechanisms extremely complex. Research on the multi-parameter coupling relationship between pollutants and environmental factors such as pH and DO at sediment micro-interfaces is a core aspect of in-depth exploration of endogenous generation mechanisms, and accurately obtaining two-dimensional spatial distribution information of multiple parameters at sediment micro-interfaces is key to expanding this research direction. However, due to the high spatiotemporal heterogeneity and the multi-factor coupled reaction characteristics of micro-interfaces, current research methods have made it extremely difficult to accurately capture information about sediment micro-interfaces, which has long constrained the in-depth expansion of micro-interface research.

[0003] Planar optical electrodes (PO) and gradient diffusion thin film (DGT) technology are powerful tools for studying micro-interfaces from an in-situ, two-dimensional, high-resolution perspective, each with advantages in capturing environmental factors and pollutant information, respectively. Over the past 20 years, various composite electrodes based on single DGT or PO technologies have been reported multiple times. However, due to the long-term independent development of these technologies within their respective fields, progress in multifunctional sensing materials and high-precision information interpretation techniques has been slow, resulting in relatively limited types and functions of measured indicators and significant deficiencies in measurement sensitivity and accuracy. PO and DGT technologies are highly complementary in terms of environmental factor and pollutant change information, and new combined application modes urgently need to be explored. Although a few researchers have already combined the two technologies in simple ways, most methods suffer from drawbacks such as cumbersome operation, easy interface damage, spatial misalignment, and signal interference, making it difficult to accurately capture the multi-factor coupled changes at heterogeneous interfaces. This hinders the quantitative exploration of the pollutant-environment parameter-driven response relationship at micro-interfaces. Therefore, there is an urgent need to develop new monitoring technologies for in-situ simultaneous imaging of pollutants and environmental parameters. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors, comprising the following steps:

[0006] Step 1: Prepare the pH-sensitive fluorescent dye HPTS(ODA)3 by introducing octadecylamine into the sulfonic acid group of HPTS;

[0007] Step 2: Based on the self-synthesized HPTS(ODA)3 and commercially available PtTFPP and BBS, three fluorescent sensing materials were prepared: PtTFPP@PSAN, HPTS(ODA)3@PSPVP and BBS@PVDCAN;

[0008] Step 3: Mix the three fluorescent sensing materials in a certain proportion and add them to a 5% hydrogel D4 solution. Stir until homogeneous to obtain a fluorescent sensing material mixture. Add Nano-ZrO and Nano-Chelex to a 10% polyurethane hydrogel D4 solution and stir until homogeneous to obtain a DGT adsorption material mixture.

[0009] Step 4: Apply the fluorescent sensing material mixture evenly to the surface of a transparent PET substrate. After the fluorescent sensing material mixture dries completely, apply a 100μm thick layer of polyurethane hydrogel D4 (10% v / v) as an isolation layer. After the isolation layer dries completely, apply the DGT adsorption material mixture to its surface to form a composite film.

[0010] Furthermore, in step one, the fluorescent dye HPTS(ODA)3 is prepared by introducing octadecylamine into the sulfonic acid group of HPTS.

[0011] Furthermore, in step one, the preparation method of HPTS(ODA)3 includes the following steps:

[0012] 1) In sodium hydroxide solution, HPTS was reacted with acetic anhydride, the organic layer was separated, and the product was concentrated to dryness to obtain hydroxyl protected product 1;

[0013] 2) The product 1 was reacted with thionyl chloride under reflux to obtain intermediate product 2;

[0014] 3) Dissolve product 2 and mix it with octadecylamine solution to react, then separate and concentrate to dryness to obtain intermediate product 3;

[0015] 4) Compound 3 was added to sodium hydroxide solution to undergo hydrolysis reaction, yielding the final target product HPTS(ODA)3.

[0016] Furthermore, the preparation method of the three optical sensing materials (PtTFPP, HPTS(ODA)3, and BBS) includes the following steps:

[0017] S1. PtTFPP and PSAN are dissolved in DMF in a certain proportion. Ultrapure water is added to the system under ultrasonic conditions. PtTFPP@PSAN fluorescent sensing material is gradually formed as the water / DMF ratio increases. Then, nanospheres are obtained by centrifugation and washing. Finally, the washed nanospheres are dispersed in 90% ethanol solution for later use.

[0018] S2. Dissolve PSPVP completely in a THF / ultrapure water mixture, add HPTS(ODA)3 solution under magnetic stirring, and then remove THF from the system by vacuum evaporation. HPTS(ODA)3@PSPVP fluorescent sensing material is gradually formed during this process, and obtained by freeze drying to obtain nanoparticles for later use.

[0019] S3. Dissolve PVDCAN and BBS in acetone solution in a certain proportion, add ultrapure water under magnetic stirring, remove acetone from the system by vacuum evaporation, and the BBS@PVDCAN fluorescent sensing material is gradually formed in this process. After freeze drying, nanoparticles are obtained for later use.

[0020] Furthermore, in S2, the THF / ultrapure water mixture is composed of THF and ultrapure water mixed in a volume ratio of 5:3; in the HPTS(ODA)3 solution, the solvent is THF.

[0021] Furthermore, in step three, the concentrations of PtTFPP@PSAN in the fluorescent sensing material mixture are 10–20 mg / mL, HPTS(ODA)3@PSPVP is 80–100 mg / mL, and BBS@PVDCAN is 20–40 mg / mL; the concentration of Nano-ZrO in the DGT adsorbent mixture is 1–2 g / 10 mL, and the concentration of Nano-Chelex is 0.5–1 g / 10 mL.

[0022] Compared to existing simple stacking methods, this invention, for the first time, prepares a multi-element single-layer composite thin film, realizing a new mode of combining PO and DGT technologies, and providing new ideas for the development of multifunctional sensing methods. The beneficial effects achieved by this invention are as follows:

[0023] 1) Existing multi-parameter synchronous monitoring methods are mostly based on improving PO and DGT sensing membranes independently and then simply stacking them together. In contrast, the single-layer multi-element composite membrane of the present invention can realize the synchronous monitoring of two environmental parameters, DO and pH, as well as pollutants such as P and heavy metals, providing a powerful tool for in-depth quantitative exploration of the micro-interface pollutant-environmental parameter driven response relationship.

[0024] 2) The pH fluorescent material used in the composite membrane, HPTS(ODA)3, is prepared by adding octadecylamine to the sulfonic acid group of the pH-sensitive dye HPTS. It has strong hydrophobicity, can exist in the environment for a longer time, and the hydrophobic octadecyl can bind more tightly to the polymer PSPVP, which is beneficial to the preparation of stable fluorescent sensing materials.

[0025] 3) The three fluorescent sensing materials of the composite membrane are prepared by a rapid precipitation method, which is simple to operate and can be scaled up and prepared in batches according to the ratio.

[0026] 4) Existing multi-parameter synchronous information acquisition technologies mostly rely on expensive fluorescence lifetime imaging systems. However, the DO and pH information analysis in this study is designed based on the fluorescence intensity ratio principle. This method can be implemented using ordinary fluorescence intensity imaging systems, with relatively low equipment requirements, making it easy to promote and use.

[0027] 5) The composite membrane has a wide response range of DO (0-100% saturated air) and pH (7-11) as well as a high adsorption capacity, which can meet the detection needs of various complex environments. Attached Figure Description

[0028] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a schematic diagram of the composite membrane structure;

[0030] Figure 2 This is a reaction flow diagram for the preparation of the fluorescent dye HPTS(ODA)3;

[0031] Figure 3 This is the fluorescence spectrum information of PtTFPP@PSAN;

[0032] Figure 4 This is the fluorescence spectrum information of HPTS(ODA)3@PSPVP;

[0033] Figure 5 This is BBS@PVDCAN fluorescence spectral information;

[0034] Figure 6These are the adsorption capacity curves (A) of the sensing membrane for the typical nutrient element P and (B) of the heavy metal Cd.

[0035] Figure 7 It is a standard curve of DO and pH for composite membranes;

[0036] Figure 8 This is the application of composite membranes in the study of the characteristics of changes in the rhizosphere microenvironment of Vallisneria natans. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] The raw materials used and their sources in the following examples:

[0039] HPTS (trisodium 8-hydroxypyrene-1,3,6-trisulfonate, CAS No.: 196504-57-1), acetonitrile (CAS No.: 75-05-8), thionyl chloride (CAS No.: 7719-09-7), dimethylformamide (CAS No.: 68-12-2), octadecylamine (CAS124-30-1), PSAN (styrene-acrylonitrile copolymer, CAS No.: 9004-54-7), PtTFPP (platinum(II)MESO-tetra(pentafluorobenzene)porphyrin, CAS No.: 109781-47-7), PSPVP (styrene-b-vinylpyrrolidone copolymer, CAS No.: 25086-29-7) BBS (4,4′-bis(2-benzoxazolyl)stilbene, CAS No.: 1533-45-5) and PVDCAN (poly(vinylidene chloride-co-acrylonitrile), CAS No.: 9010-76-8) are from Sigma-Aldrich; dichloromethane (CAS No.: 75-09-02), triethylamine (CAS No.: 121-44-08), and acetic anhydride (CAS No.: 108-24-07) are from Shanghai Testing; hydrochloric acid (CAS No.: 7647-01-0) and sodium hydroxide (CAS No.: 1310-73-2) are from Nanjing Chemical Reagent; polyurethane hydrogel D4 is from AdvanSource Biomaterials Corp., model HydroMedTMD4; and PET film substrate is from Mueller-ahlhorn, model Mylar A (0.019mm).

[0040] Example 1:

[0041] The preparation process of the pH fluorescent dye HPTS(ODA)3 in this embodiment is described in [link to example]. Figure 2 This includes the following steps:

[0042] S11: 2.0 g HPTS, 40 mL dichloromethane, 0.95 g triethylamine and 0.78 g acetic anhydride were added sequentially to the reaction flask. After stirring at room temperature for 8 h, 40 mL deionized water was added, and the pH was adjusted to 2.0 with 1.0 mol hydrochloric acid. The organic layer was separated and concentrated to dryness to obtain 1.75 g product 1.

[0043] S12: Add 1.75g ​​of product 1, 10mL of acetonitrile and 2.5g of thionyl chloride to a reaction flask, add a small amount of dimethylformamide as a catalyst, heat to reflux for 8h, cool and concentrate to dryness to obtain 1.95g of product 2.

[0044] S13: Dissolve 1.5g of product 2 in 10mL of dichloromethane, add dropwise to 50mL of 15% (v / v) octadecylamine solution (15%, v / v), then heat to room temperature and stir for 24h. Add 50mL of deionized water to the reactants, separate the dichloromethane layer, and wash with hydrochloric acid and saturated sodium chloride aqueous solution in sequence. Concentrate to dryness to obtain 3.02g of compound 3.

[0045] S14: 3.0 g of compound 3 was added to 20 mL of 1 M sodium hydroxide solution and stirred at room temperature for 5 h. The pH was adjusted to 4.0 with 1 M dilute hydrochloric acid, then extracted and concentrated with dichloromethane. Finally, 2.20 g of final product 4 was obtained by silica gel column chromatography (dichloromethane:methanol = 10:1), with an overall yield of approximately 48%.

[0046] S21: Prepare a 10 mg / mL PSAN solution, then add PtTFPP and dissolve it completely to make the PtTFPP content 0.2 mg / mL. Under ultrasonic conditions, add ultrapure water to the system. As the water / DMF ratio gradually increases, nanospheres gradually form. Remove DMF from the system by centrifugation. Finally, disperse the washed nanospheres in a 90% ethanol solution for later use to obtain the fluorescent sensing material PtTFPP@PSAN that is sensitive to dissolved oxygen.

[0047] The organic fluorescent dye PtTFPP was embedded in PSAN to obtain PtTFPP@PSAN nanofluorescent sensing material; HPTS(ODA)3 was embedded in PSPVP to obtain HPTS(ODA)3@PSPVP nanofluorescent sensing material; and the fluorescent reference dye BBS was embedded in PVDCAN to obtain BBS@PVDCAN fluorescent sensing material.

[0048] S22: A THF / ultrapure water mixture (v:v, 5:3) and PSPVP were added to a round-bottom flask at a ratio of 80:1 (v:v), and the mixture was magnetically stirred to dissolve the polymer solution. Then, under magnetic stirring, a 0.6 mg / mL HPTS(ODA)3 solution (THF as solvent) was added dropwise at a uniform rate. After thorough mixing, the round-bottom flask was transferred to a rotary evaporator and evaporated at a uniform rate under reduced pressure at 60 °C until THF was completely removed. Nanospheres gradually formed during the THF removal process. After freeze-drying, nanoparticles were obtained for later use, yielding the pH-sensitive fluorescent sensing material HPTS(ODA)3@PSPVP.

[0049] S23: Add 5 mL of BBS saturated acetone solution to 20 mL of 2 mg / mL PVDCAN acetone solution, place it on a magnetic stirrer and stir vigorously, then add 60 mL of ultrapure water to the mixed solution and continue stirring for 1 h to ensure uniform solute dispersion. Remove the acetone in the system by rotary evaporator, freeze-dry to obtain nanoparticles for later use, and obtain the fluorescent sensing material BBS@PVDCAN which is insensitive to both pH and dissolved oxygen.

[0050] S31: Disperse 80 mg PtTFPP@PSAN, 360 mg HPTS(ODA)3@PSPVP and 100 mg BBS@PVDCAN into 4 mL of 90% ethanol solution containing 5% (w / v) HYD4, and stir thoroughly to obtain a stock solution of fluorescent nanospheres sensitive to dissolved oxygen and pH.

[0051] The preparation method of Nano-ZrO is referenced in: HAN C, REN J, WANG Z, et al. 2017. A Novel Hybrid Sensor for Combined Imaging of Dissolved Oxygen and Labile Phosphorus Flux in Sediment and Water. Water Research[J],108:179-188);

[0052] References for Nano-Chelex preparation method: ZHOU C, VAN DE VELDE S, BAEYENS W, et al. 2018. Comparison of Chelex based resins in diffusive gradients in thin-film for high resolution assessment of metals. Talanta[J], 186:397-405).

[0053] S32: Mix Nano-ZrO, Nano-Chelex and D4 containing 10% polyurethane hydrogel at a ratio of 1:2:10 (w:w:v), and stir thoroughly to obtain DGT adsorption material stock solution.

[0054] S33: Fluorescent nanosphere stock solution is uniformly coated onto a transparent PET film substrate using a coating method. After drying at room temperature, an optical sensing layer is formed. A 100μm thick polyurethane hydrogel D4 is coated on its surface as an isolation layer. Then, a 300μm thick DGT nano-adsorbent material is coated on its surface in the same manner to form a multi-element single-layer composite film.

[0055] Example 2

[0056] In this embodiment, the spectral information of three optical sensing materials was measured.

[0057] 1) Based on the PtTFPP@PSAN prepared in Example 1, an appropriate amount of the material dispersion was dispersed in a 10 mM NaCl solution, mixed well, and then transferred to a 1 cm quartz cuvette. Its absorption spectrum was measured using a UV spectrophotometer, and its emission spectrum was measured using a fluorescence spectrophotometer. The results are as follows: Figure 3 As shown, its maximum absorption wavelength is determined to be 389 nm, and its maximum emission wavelength is 650 nm.

[0058] 2) Based on the HPTS(ODA)3@PSPVP prepared in Example 1, equal volumes of the pre-lyophilized stock solution were dispersed in 5 mL of 10 mM PBS / NaOH buffer solutions at different pH values ​​(6.26–9.99). After mixing, the solutions were sequentially transferred to 1 cm quartz cuvettes. The absorption spectra were measured using a UV spectrophotometer, and the emission spectra were measured using a fluorescence spectrophotometer. The results are as follows: Figure 4 As shown, the maximum absorption wavelengths are determined to be 412 nm and 480 nm, respectively, and the maximum emission wavelength is approximately 530 nm.

[0059] 3) Based on the BBS@PVDCAN prepared in Example 1, an appropriate amount of the pre-lyophilized material stock solution was dispersed in a 10 mM NaCl solution, mixed well, and then transferred to a 1 cm quartz cuvette. Its absorption spectrum was measured using a UV spectrophotometer, and its emission spectrum was measured using a fluorescence spectrophotometer. The results are as follows: Figure 5 As shown, the material exhibits significant light absorption near 389 nm, with maximum emission wavelengths of 412 nm and 436 nm (both located in the blue channel).

[0060] Example 3

[0061] In this embodiment, the DGT channel adsorption capacity of the composite membrane was tested, using P and Cd as representative elements. The test was conducted through the following steps, and the results are as follows: Figure 6 As shown:

[0062] 1) Using a stainless steel ring cutter The prepared composite membrane is cut into circular pieces of uniform size, loaded into a piston-type DGT device, and subjected to nitrogen aeration deoxygenation treatment.

[0063] 2) Prepare a series of mixed solutions with different concentration gradients of P (1, 2, 4, 8, 10, 15, 20, 40 mg / L) and Cd (1, 3, 6, 10, 16, 20, 34, 50 mg / L) using oxygen-free water, and stir them at a constant speed using a magnetic stirrer.

[0064] 3) Deploy the DGT device prepared in 1) in the solution in 2), with 3 devices for each concentration as parallels, and recover the DGT device after 5 hours of deployment;

[0065] 4) Rinse the surface of the device with ultrapure water to remove the adsorbed solution. Take out the composite membrane and immerse it in 1.0 mol / L HNO3 for 24 h to extract Cd adsorbed on the membrane. Immerse it in deionized water for 4 h to remove residual HNO3 eluent. Immerse it in 1.0 mol / L NaOH for 24 h to extract P adsorbed on the fixed membrane. The P concentration in the extract is determined by micro-colorimetry using an Epoch microplate spectrophotometer (BioTeK, USA). The Cd concentration is determined by ICP-MS.

[0066] 5) Based on the DGT principle, the adsorption capacity of this novel composite membrane for P was calculated to be approximately 16.4 μg / cm³. 2 The adsorption capacity for heavy metals such as Cd is greater than 38 μg / cm³. 2 .

[0067] Example 4

[0068] In this embodiment, the calibration and standard curve applied to the composite membrane are as follows: Figure 7 As shown, the drawing method includes the following steps:

[0069] 1) Prepare a set of buffer solutions with different pH values ​​using NaH2PO4 and Na2HPO4, attach the composite membrane to the inside of the calibration box, pour the buffer solution into the calibration box, excite it with 389nm, 412nm and 480nm LED light sources respectively, and obtain the fluorescence images of the composite membrane under different pH conditions through the photoelectric imaging system in sequence.

[0070] 2) The fluorescence image obtained in step 1) is split into RGB three channels using image processing software (such as ImageJ). The ratio I of the fluorescence intensity of the G channel of the image obtained by 480nm excitation light and 412nm excitation light is used as the fluorescence response signal of the sensing membrane to pH value. The response curve of the sensing membrane to pH value is obtained by curve fitting with the corresponding pH value. The fluorescence release characteristics of the sensing membrane with respect to pH can be described by the Boltzmann equation (Equation 1):

[0071]

[0072] In the formula, A1 and A2 are fitting constants; dx is the slope, and pK is the constant. a I represents the inflection point of the response curve, and I is the response signal of the composite sensing membrane to pH value.

[0073] 3) Use image processing software (such as ImageJ) to split the fluorescence image obtained in step 1) into RGB three channels, and use 389nm excitation light to obtain the fluorescence intensity of the B channel of the image and the corresponding pH value to perform curve fitting, which is used to measure the interference of pH on the blue channel of the sensing membrane. The third-order polynomial equation can well describe this change.

[0074] 4) Pour water similar to the solution in the test environment into the calibration box, adjust the N2 and O2 flow rates to change the DO concentration of the buffer solution, record the actual concentration through the dissolved oxygen probe, excite with a 389nm UV light source, and obtain fluorescence images of the composite membrane under different dissolved oxygen conditions.

[0075] 5) For the fluorescence images obtained in step 4), image processing software is used to extract the two fluorescence values ​​of the R and B channels corresponding to PtTFPP@PSAN and BBS@PVDCAN, respectively. The fluorescence intensity ratio I²(R / B) of the two channels is calculated and curve-fitted with the corresponding dissolved oxygen concentration. The fluorescence response characteristics of the sensing membrane with respect to DO can be described according to the Stern-Volmer equation (Equation 2):

[0076]

[0077] In the formula, R and R0 represent the fluorescence intensity of the composite sensing membrane in the presence and absence of O2, respectively; α is the non-quenchable portion of the fluorescence of the sensing membrane; K sv [O2] is the Stern-Volmer quenching constant; [O2] is the concentration of DO.

[0078] Example 5

[0079] The application method of the composite membrane in this embodiment includes the following steps:

[0080] 1) Pack the thoroughly mixed sediment into a root box lined with an ultra-thin filter membrane (10μm), place the root box vertically in a water tank filled with lake water for stable cultivation for one week. After the sediment-water interface is stable, plant the roots of healthy Vallisneria natans seedlings along the filter membrane into the root box, and place the root box in the water tank for 45° tilt cultivation. The cultivation conditions are: light-dark ratio of 1:1, continuous aeration, 25℃.

[0081] 2) After the seedlings have emerged from the roots, insert the composite membrane into the rhizosphere region through the slit between the filter membrane and the root box window, and deploy it for 5-10 hours (depending on the P and heavy metal content in the sediment). During the deployment period, record the fluorescence images of the sensing membrane at three time points: 1 hour, in the middle, and before removal using an optical imaging system (record three images each time under excitation light of 389nm, 412nm, and 480nm).

[0082] 2) The images obtained under 412nm and 480nm excitation light conditions are split into RGB by software. First, the I of each pixel is calculated. The pH value of each pixel can be obtained by using the pre-obtained pH standard curve.

[0083] 3) The image obtained under 389nm excitation light is split into RGB by software. First, the pH value of each pixel is used to quantitatively subtract the interference of pH on the blue channel according to the pre-obtained response function of the blue channel to the pH value to obtain the corrected B channel. Then, the ratio R of the R channel to the corrected B channel is calculated. The dissolved oxygen concentration of each pixel can be obtained according to the pre-obtained dissolved oxygen standard curve.

[0084] 4) After deployment is completed, accurately record the time and take out the composite film. First, gently absorb the surface moisture with lint-free paper. Take a clean plastic sheet that has been soaked in 1M HNO3 and washed with ultrapure water and cover the surface. Use a dry adhesive dryer with a vacuum pump to dry it at 50°C for 5 hours.

[0085] 5) Fix the dried gel onto a suitably sized glass plate and analyze it using gel chromatography or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) imaging. Figure 8 As shown, data processing and plotting are finally performed using Python and Orign.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0087] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors, characterized in that: Includes the following steps: Step 1: Prepare HPTS(ODA)3 by attaching octadecylamine to the sulfonic acid group of HPTS; Step 2: Embed PtTFPP in PSAN to obtain PtTFPP@PSAN nanofluorescent sensing material; HPTS(ODA)3 was embedded in PSPVP to obtain HPTS(ODA)3@PSPVP nanofluorescent sensing material; the fluorescent reference dye BBS was embedded in PVDCAN to obtain BBS@PVDCAN fluorescent sensing material. Step 3: Add the three fluorescent sensing materials from Step 2 to the polyurethane hydrogel D4 solution and stir until homogeneous to obtain a PO fluorescent sensing material mixture. Add the nano-hydrated zirconia DGT adsorbent Nano-ZrO and the ground Chelex-100 DGT adsorbent Nano-Chelex to the polyurethane hydrogel D4 solution and stir until homogeneous to obtain a DGT adsorbent mixture. Step 4: Take 200-1000 μL of fluorescent sensing material mixture and evenly coat it onto the surface of PET substrate. The coating thickness is 120-150 μm. After the fluorescent sensing material mixture dries completely, coat a 100-120 μm thick polyurethane hydrogel D4 onto its surface as an isolation layer. After the isolation layer dries completely, coat a 200-300 μm thick DGT adsorption material mixture using the above coating method to form a multi-element single-layer composite film.

2. The method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 1, characterized in that: Step one includes the following steps: S1. HPTS was reacted with triethylamine and acetic anhydride until the reaction was complete. The pH was adjusted to 2, the organic layer was separated, and the product was concentrated to dryness to obtain product 1. S2. Product 1 was reacted with thionyl chloride under DMF catalysis by heating and reflux, and then concentrated to dryness after cooling to obtain product 2; S3. Dissolve product 2 in dichloromethane and octadecylamine solution in DMF. Mix the two solutions and react at room temperature. After the reaction is complete, add deionized water, separate, and concentrate to dryness to obtain product 3. S4. Add product 3 to sodium hydroxide solution for hydrolysis to obtain HPTS(ODA)3.

3. The method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 1, characterized in that: In step two, the PtTFPP@PSAN fluorescent sensing material is prepared as follows: PtTFPP and PSAN are dissolved in DMF, ultrapure water is added to the system under ultrasonic conditions, and the PtTFPP@PSAN fluorescent sensing material is obtained by centrifugation and washing.

4. The method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 1, characterized in that: In step two, the preparation method of HPTS(ODA)3@PSPVP fluorescent sensing material is as follows: HPTS(ODA)3 is dissolved in THF to obtain HPTS(ODA)3 solution; PSPVP is fully dissolved in a mixture of THF and ultrapure water, and HPTS(ODA)3 solution is added under magnetic stirring. THF is removed by vacuum evaporation to obtain HPTS(ODA)3@PSPVP fluorescent sensing material, which is then freeze-dried for later use.

5. The method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 1, characterized in that: In step two, the preparation method of BBS@PVDCAN fluorescent sensing material is as follows: PVDCAN and BBS are dissolved in acetone solution, ultrapure water is added under magnetic stirring, acetone is removed by vacuum evaporation to obtain BBS@PVDCAN fluorescent sensing material, and then freeze-dried for later use.

6. The method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 1, characterized in that: In step three, the concentrations of PtTFPP@PSAN in the fluorescent sensing material mixture are 10–20 mg / mL, HPTS(ODA)3@PSPVP is 80–100 mg / mL, and BBS@PVDCAN is 20–40 mg / mL; in the DGT adsorbent mixture, the concentrations of Nano-ZrO is 1–2 g / 10 mL, and the concentrations of Nano-Chelex is 0.5–1 g / 10 mL.

7. The composite membrane for simultaneous detection of sediment pollutants and environmental factors prepared by the method for preparing a composite membrane for simultaneous detection of sediment pollutants and environmental factors according to any one of claims 1 to 6.

8. The application of the composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 7, characterized in that: The composite membrane is used for the simultaneous detection of dissolved oxygen, pH, phosphorus, and heavy metals in sediments.

9. The application of the composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 7, characterized in that: The marking correction and usage method of the composite film are as follows: 1) A series of phosphate buffer solutions with different pH values ​​were prepared using NaH2PO4 and Na2HPO4 solutions. The composite membrane was attached to the inside of the calibration box, and the buffer solution was poured into the calibration box. The fluorescence images of the composite membrane were recorded under LED excitation light conditions of 389nm, 412nm and 480nm. 2) Extract the G-channel information of HPTS(ODA)3@PSPVP under excitation conditions of 412nm and 480nm light sources, and fit the G-channel information using the Boltzmann equation. 480nm With G 412nm The pH response curve of the composite membrane was obtained by analyzing the relationship between the intensity ratio and the corresponding pH value. 3) Extract the B-channel information of BBS@PVDCAN under 389nm light source excitation conditions, and fit the B-channel information using a third-order polynomial. 389nm The relationship between intensity and corresponding pH value is used to measure the interference of pH on the blue channel of the composite membrane; 4) Replace the solution in the calibration box with water that is similar to the properties of the environment to be tested, adjust the amount of N2 and O2 introduced to obtain different DO concentrations, and after stabilization, use the photoelectric imaging system to obtain fluorescence images of the composite membrane under different DO concentration conditions under 389nm LED light source excitation. 5) Extract the R-channel information of PtTFPP@PSAN under 389nm excitation and the B-channel information of BBS@PVDCAN, and then fit the R-channel information using the Stern-Volmer equation. 389nm With B 389nm The relationship between the intensity ratio and the corresponding DO concentration yields the DO response curve of the composite membrane; 6) Deploy the pre-calibrated composite membrane in the test environment for 5-10 hours. Obtain the fluorescence information of the composite membrane at three time points: 1 hour after deployment, in the middle, and before removal. Calculate the three average values ​​by image splitting and substitute them into the pre-obtained standard curve to obtain the DO and pH distribution information. 7) Remove the composite membrane, and after cleaning and drying pretreatment, analyze to obtain the two-dimensional distribution information of P and target heavy metals.

10. The application of the composite membrane for simultaneous detection of sediment pollutants and environmental factors according to claim 9, characterized in that: The Boltzmann equation: ； In the formula, A1 and A2 are fitting constants; dx is the slope, and pK is the constant. a I represents the inflection point of the response curve, and I is the response signal of the composite sensing membrane to pH value. The Stern-Volmer equation: ； In the formula, R and R0 represent the fluorescence intensity of the composite sensing membrane with and without O2, respectively; α is the non-quenchable portion of the sensing membrane's fluorescence; K sv [O2] is the Stern-Volmer quenching constant; [O2] is the concentration of DO.

Images