A non-targeted DGT adsorption membrane for enriching multiple types of new pollutants and its preparation method and application

Abstract

The present invention discloses a non-targeted DGT adsorption membrane for enriching multiple types of new pollutants, and a preparation method and application thereof, including the following steps: S1, purifying and activating resin raw materials: the resin raw materials include WAX ​​resin and MCX resin; S2, preparing adsorption membrane solution: taking WAX resin and MCX resin, adding them to a crosslinker solution, and then adding an initiator and a catalyst to mix; S3, making gel: injecting the adsorption membrane solution into a gel-forming model, standing for the solution to solidify into a gel membrane; S4, washing the gel membrane until the pH is neutral. Compared with other single resin materials, the non-targeted DGT adsorption membrane of the present invention has a wider range of adsorbed pollutant types, can be used to determine the concentration of cationic, anionic, neutral and amphoteric organic pollutants in the solution, and has high adsorption efficiency and elution efficiency; combined with DGT passive sampling technology, it can simultaneously realize non-targeted analysis and accurate quantification of pollutants.

Description

Technical Field

[0001] The present invention relates to the field of thin film diffusion gradient technology, and in particular to a non-targeted DGT adsorption membrane for enriching multiple types of new pollutants, and a preparation method and application thereof. Background Art

[0002] At present, due to the progress of science and technology and the increase of human activities, many pollutants are discharged into the water environment, and water environment problems have become one of the top ten environmental problems in China. Among these pollutants, there are a variety of new pollutants, which are characterized by high toxicity, persistence and bioaccumulation. Taking perfluorinated alkylsubstances (PFAS) as an example, PFAS is a class of artificial organic fluorides that have been widely produced and used in consumer products and industrial processes since 1940. It itself has potential hepatotoxicity, neurotoxicity, reproductive toxicity, carcinogenicity, etc. At the same time, because the carbon-fluorine bond is one of the strongest chemical bonds, PFAS can exist widely and persistently in various environmental media. Therefore, identifying and determining these different types of new organic pollutants is of great significance for evaluating their environmental and ecological risks. Compared with the traditional targeted analysis method, the suspicious screening and non-targeted analysis based on high-resolution mass spectrometry can obtain tens of thousands of material peaks at a time, and can identify known compounds in samples or predict the structure of unknown compounds based on isotope distribution, secondary mass spectrometry information, etc. without relying on standard products. It is an important way to identify and determine a large number of new organic pollutants in the water environment.

[0003] The detection of new pollutants in water environment mostly adopts active sampling method, that is, after the water samples are collected on site, they are transported back to the laboratory for further pre-treatment and detection and analysis. However, the active sampling method has the disadvantages of large human and material consumption, the water sample transportation process is easily affected, and it can only reflect the instantaneous concentration. Passive sampling technology has the advantages of simple sampling process, convenient operation, low cost, and no energy input. Among them, the diffusion gradient in thin films (DGT) technology is a technology for in-situ quantitative determination of ion diffusion flux or ion concentration in the medium. This method is based on Fick's first diffusion law. The concentration value of a certain ion is obtained by quantitatively measuring and calculating a certain ion passing through a diffusion membrane of a certain thickness within a specific time. As a more mature kinetic passive sampling technology, DGT has more accurate concentration measurement results and more convenient measurement methods compared with other equilibrium passive sampling technologies. DGT technology has been applied to the concentration determination of pollutants such as heavy metals and trace organic matter in water environment and soil. It is mainly used for quantitative analysis of the concentration of pollutants in the environment. It is also claimed to be used for suspicious screening and non-targeted analysis of pollutants in the environment. The combination of DGT technology and suspected screening / non-target analysis also requires confirmation of the ability of the adsorbent to concentrate a wider range of analytes (Eliza et al., 2023).

[0004] The DGT device is composed of a fixed layer (i.e., a fixed membrane / adsorption membrane, i.e., a binding phase) and a diffusion layer (diffusion membrane and filter membrane) stacked together. The target ions diffuse through the diffusion layer and are then captured by the fixed membrane (adsorption membrane) and form a linear gradient distribution in the diffusion layer. At present, there are four main types of DGT devices, namely, piston type, double mode, flat type, and liquid fixed phase device. The first two devices are used for the determination of soil and water bodies, the third device is used for the determination of sediments and wetland soils, and the last device is mainly used for the determination of water bodies (Thin Film Diffusion Gradient (DGT) - Technological Progress and Prospects, Li Cai et al., Journal of Agricultural Environmental Science, 2018, 37 (12): 2613-2628). Among them, the piston type DGT device consists of a base and a cap. The fixed membrane (adsorption membrane), diffusion membrane, and filter membrane are placed on the base in sequence, and the three layers of membranes are fixed with a cap.

[0005] At present, the DGT technology used for non-targeted analysis mainly uses an adsorption membrane prepared by HLB resin. Although it can capture most different types of new organic pollutants, the adsorption efficiency of some weakly alkaline organic pollutants (such as sulfonamide antibiotics) is low at high pH. In the environment with low pollutant concentration in the field, HLB-DGT may cause pollutants to be missed due to being below the detection limit (Jonathan et al., 2020). In addition, the carrier of the DGT adsorption membrane currently prepared by HLB adsorbent is mostly agarose, which may be eaten by microorganisms in seawater or heavily polluted environments, resulting in the loss of adsorption membrane and affecting quantification. Therefore, it is necessary to develop a new binding phase that can not only adsorb new pollutants in various ionic forms to achieve the goal of suspected screening and non-targeted analysis to capture pollutants, but also have a high adsorption efficiency to meet quantitative requirements. Summary of the invention

[0006] The purpose of the present invention is to address the above-mentioned problems and provide a non-targeted DGT adsorption membrane for enriching multiple types of new pollutants and a preparation method thereof, which has high adsorption efficiency for cationic, anionic, neutral and amphoteric organic pollutants in water, so as to meet the requirements of DGT for suspicious screening and non-targeted analysis in the environment.

[0007] In order to achieve its purpose, the present invention adopts the following technical solution:

[0008] A method for preparing a non-targeted DGT adsorption membrane for enriching multiple types of new pollutants comprises the following steps:

[0009] S1. Purify and activate the resin raw material: use an organic solvent to elute the resin raw material so that the impurities on the adsorption and binding sites of the resin raw material are dissolved in the organic solvent, and then rinse it with ultrapure water and dehydrate it to obtain a purified and activated resin raw material; the resin raw material includes WAX resin and MCX resin;

[0010] S2, preparing an adsorption film solution: taking the resin raw materials WAX resin and MCX resin treated in step S1, adding them to a crosslinker solution, and then adding an initiator and a catalyst to mix well, wherein the crosslinker solution is a 14-16wt% polyacrylamide solution; the mass ratio of WAX resin, MCX resin, and crosslinker solution is 2-3.5:0.5-2:10;

[0011] S3, gel preparation: inject the adsorption film solution prepared in step S2 into the gel forming model, let the solution stand until it solidifies into a gel film, open the gel forming model, and take out the gel film;

[0012] S4. Wash and soak the gel membrane in ultrapure water until the pH is neutral to obtain the desired adsorption membrane.

[0013] In step S1, the volume ratio of the resin raw material to the organic solvent and ultrapure water used is about 1:(10-20):(10-20); the organic solvent is methanol.

[0014] In step S2, the mass ratio of WAX resin, MCX resin and crosslinking agent solution is 2.5-3.5:0.5-1.5:10 or 2.7-3.3:0.7-1.3:10 or 2.8-3.2:0.8-1.2:10 or 2.9-3.1:0.9-1.1:10.

[0015] The initiator is ammonium persulfate and the catalyst is TEMED.

[0016] The gelling model in step S3 is composed of two glass plates, with a gap between the two glass plates for accommodating the adsorption film solution; the thickness of the gel film is 0.3-1.0 mm.

[0017] The pollutants include cationic, anionic, neutral and amphoteric organic pollutants.

[0018] A non-targeted DGT adsorption membrane for enriching multiple types of new pollutants is prepared by any of the methods described above.

[0019] The present invention also provides a DGT device, wherein the fixed membrane is the above-mentioned DGT adsorption membrane.

[0020] The DGT device is a piston-type DGT device, comprising a base and a cap, on which a fixed membrane, a diffusion membrane and a filter membrane are placed in order from small to upper, and the cap is used to fix the three layers of membranes; preferably, the diffusion membrane is a polyacrylamide gel diffusion membrane, the filter membrane is a polycarbonate filter membrane, and the diffusion membrane is a gel membrane prepared by polymerization and coagulation of a 14-16wt% polyacrylamide solution.

[0021] The present invention also provides the application of the above-mentioned DGT device in the enrichment and analysis of multiple types of new pollutants, wherein the multiple types of new pollutants include cationic, anionic, neutral and amphoteric organic pollutants, preferably including PFAS pollutants, ionic liquid pollutants, denatonium benzyl, sulfonamide antibiotics, and estrogen.

[0022] The beneficial effects of the present invention are:

[0023] The non-targeted DGT adsorption membrane (MIX) for adsorbing new pollutants provided by the present invention does not require heating during the preparation process, is time-saving and energy-saving, and has the advantages of simple preparation method, high standardization, strong gelation, etc.

[0024] Compared with other single resin materials (such as HLB resin and WAX resin, etc.), the non-targeted DGT adsorption membrane (MIX) of the present invention has a wider range of adsorbed pollutant types and can be used to determine the concentrations of cationic, anionic, neutral and amphoteric organic pollutants in solutions in DGT. It has high adsorption efficiency and elution efficiency. Combined with DGT passive sampling technology, it can simultaneously realize non-targeted analysis and accurate quantification of pollutants.

[0025] Compared with other mixed adsorption membranes, such as adsorption membranes made of combinations of WCX+WAX, MCX+MAX, WCX+MAX, MAX+HLB and WAX+HLB, the non-targeted DGT adsorption membrane (MIX) of the present invention has the advantages of moderate gelation time, strong and tough colloid, uniform adsorbent mixing, higher adsorption efficiency and elution efficiency in terms of colloid properties, adsorption properties and elution effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The adsorption rates of the MIX adsorption membrane of the present invention are compared with those of the WCX / WAX adsorption membranes and the WCX / MAX adsorption membranes in different ratios.

[0027] Figure 2 The adsorption rates of the MIX adsorption membrane of the present invention and the MCX / MAX adsorption membranes of different ratios for more targets are compared.

[0028] Figure 3 It is a comparison of the adsorption rates of the target substance by the HLB adsorption membrane and the MIX adsorption membrane of the present invention.

[0029] Figure 4 It is a comparison of the elution rate of the target substance on the MIX adsorption membrane of the present invention and the MCX / MAX adsorption membranes with different ratios.

[0030] Figure 5 It is a schematic diagram of the MIX-DGT device structure.

[0031] Figure 6 is the sampling kinetics of MIX-DGT for typical target new pollutants. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0033] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0034] The main sources of reagents and materials are as follows:

[0035] 1. Adsorption membrane raw materials

[0036]

[0037] Among them, WAX (weak anion exchange) filler is a mixed weak anion exchange adsorbent with macroporous PS / DVB as the matrix and modified by tertiary amine groups. Its benzene ring has a strong hydrophobic interaction, and the tertiary amine group provides weak anion exchange capacity.

[0038] MCX (mixed strong cation exchange) filler is a mixed strong cation exchange adsorbent with polystyrene / vinyl pyrrolidone as the basic skeleton and sulfonic acid groups bonded to the highly cross-linked PS / DVB surface.

[0039] 2. Pollutant samples:

[0040] (1) PFAS pollutant standards:

[0041] Compound Abbreviations CAS Reagent Brand Perfluorobutyric acid PFBA 375-22-4 Maclean Perfluorooctanoic acid PFOA 335-67-1 Maclean Perfluorooctane sulfonic acid PFOS 1763-23-1 Maclean Perfluorohexanoic acid PFh 307-24-4 Maclean Perfluorobutanesulfonic acid PFBS 375-73-5 Maclean Perfluorooctylaminopropyltrimethylammonium iodide PFOAAmS 335-90-0 Fluorobon Perfluorooctanesulfonamido betaine PFOSB 75046-16-1 Fluorobon Perfluoroheptanoic acid PFHpA 375-85-9 Maclean Perfluorododecanoic acid PFDoDA 307-55-1 Anpel Perfluoroundecanoic acid PFUnDA 2058-94-8 Anpel Hexafluoropropylene oxidized dimer acid HFPO-DA 13252-13-6 Maclean Hexafluoropropylene oxide trimer acid HFPO-TA 13252-14-7 MREDA Perfluoropropionic acid PfA 422-64-0 Aladdin Sodium trifluoromethanesulfonate TFMS-Na 2926-30-9 Aladdin 1H,1H,6H,6H-Perfluoro-1,6-hexanediol PFHD 355-74-8 Maclean 1H,1H,8H,8H-Perfluorooctane-1,8-diol PFRTD 90177-96-1 Maclean 2,2-Bis(4-carboxyphenyl)hexafluoropropane TFBBA 1171-47-7 Maclean Sodium perfluorononenyloxybenzenesulfonate OBS 87-56-8 Wengjiang reagent Perfluorotridecanoic acid PFTrDA 72629-94-8 TMstandard Perfluorotetradecanoic acid PFTeDA 376-06-7 TMstandard 6:2 Fluorosulfonic acid 6:2FTS 27619-97-2 Maclean

[0042] (2) Other pollutant standards:

[0043]

[0044] Example 1 Preparation of adsorption film

[0045] The adsorption film was prepared as follows:

[0046] S1. Purification and activation of resin raw materials: Place the resin raw materials in an SPE column (solid phase extraction column), pour methanol into the column for elution, and filter the methanol out from the filter disc at the bottom of the SPE column. Rinse 3-5 times to dissolve the impurities on the adsorption binding sites of the resin material in methanol, then rinse with ultrapure water, dehydrate, and obtain the purified and activated resin raw materials. The SPE column can also be replaced with a plastic tube with holes at the bottom, as long as it is convenient to rinse with methanol and ultrapure water from top to bottom. Resin raw materials 1 and 2 are purified and activated by this method. The volume ratio of resin raw materials to methanol and ultrapure water is about 1:(10-20):(10-20).

[0047] S2. Preparation of adsorption film solution: Take the resin raw material treated in step S1, add it to the crosslinker solution (15wt% polyacrylamide solution), then add 10wt% ammonium persulfate solution and catalyst N,N,N',N'-tetramethylethylenediamine (TEMED) in sequence, and mix well.

[0048] S3, gel preparation: Take two clean glass plates, place a 0.5 mm thick gasket between the two glass plates so that the gap between the two glass plates is 0.5 mm, then clamp the three sides of the glass plate with clips, leaving one side for injecting the solution. Take an appropriate amount of the adsorption film solution prepared in step S2 and inject it into the prepared glass plate forming mold, let it stand until a gel film is formed, pry the glass plates apart and take out the gel film.

[0049] S4. Soak the gel film in ultrapure water, changing the water several times until the pH of the aqueous solution is about 7 (soaking for about 24 hours in total). At this time, the gel film is fully expanded and the gel film is uniformly brown-yellow. Cut the gel film into discs with a diameter of 25 mm to obtain the desired adsorption film.

[0050] Adsorption membranes with different raw material ratios were prepared by the above method, including adsorption membranes made of combinations of WCX+WAX, MCX+MAX, WCX+MAX, MAX+HLB, WAX+HLB, etc., and 160 μL of 10 wt% ammonium persulfate solution and 50 μL TEMED were added to each adsorption membrane. The specific raw material ratios and colloidal properties are shown in Table 1:

[0051] Table 1 Comparison of performance of mixed adsorption membrane colloids with different typical raw material ratios

[0052]

[0053] The adsorption film glue made from the raw materials WAX+MCX is recorded as MIX adsorption film, and the adsorption film made from the other raw materials is recorded as BAPA glue. The results in Table 1 show that the adsorbent mixing of MAX / HLB-BAPA glue and WAX / HLB-BAPA glue under this condition is not ideal. The colloids of WCX / WAX-BAPA glue, WCX / MAX-BAPA glue, MCX / MAX-BAPA glue and MIX adsorption film are strong and tough, and the adsorbent mixing is uniform.

[0054] WCX / WAX-BAPA glue, WCX / MAX-BAPA glue and MCX / MAX-BAPA glue with different ratios were selected as the control group, and the adsorption capacity of the target pollutants was compared with the MIX adsorption membrane of the experimental group 2 with a moderate gelation time. The experimental method is the same as that of Example 2. The adsorption rate of the target substance measured above is shown in Figure 1-2 .

[0055] from Figure 1-2 It can be seen that there are obvious differences in the adsorption rates of WCX / WAX-BAPA glue, WCX / MAX-BAPA glue and MIX adsorption membrane for target substances such as SDZ, DB, C8, C6, and C4. Among them, the adsorption rates of WCX / WAX-BAPA glue and WCX / MAX-BAPA glue for C8, C6, and C4 are less than 60%, while MCX / MAX-BAPA glue and MIX adsorption membrane (WAX+MCX) have higher adsorption rates for target substances. In general, to prepare a DGT binding phase with high adsorption efficiency for cationic, anionic, neutral and amphoteric organic pollutants, the components of the mixed adsorption membrane must contain MCX resin.

[0056] Example 2

[0057] In order to optimize a DGT binding phase with high adsorption efficiency for cationic, anionic, neutral and amphoteric organic pollutants, the adsorption performance of the MIX adsorption membrane and the currently commonly used HLB adsorption membrane were compared. The HLB adsorption membrane in this embodiment is prepared by using HLB resin as the resin raw material according to the method in Example 1, that is, both resin raw materials 1 and 2 are HLB resins, the total amount of HLB resin is 4g, and the amount of 15wt% polyacrylamide solution is 10g.

[0058] Preparation of pollutant standard solution:

[0059] Mixed standard solution 1: Take PFBA, PFOA, PFOS, PFHxA, and PFBS standards and dissolve them in methanol to prepare a mixed standard solution of the five PFASs with a concentration of 100 mg / L.

[0060] Mixed standard solution 2: Take DB and ILs (C12, C10, C8, C6, C4), dissolve them in methanol and prepare a mixed standard solution with a concentration of 100 mg / L.

[0061] Mixed standard solution 3: Take PFOAamS and PFOSB and dissolve them in methanol to form a mixed standard solution with a concentration of 100 mg / L.

[0062] SAs single standard solution: Take SDZ, SMX, SMZ, SCP, and SDM and add them to methanol respectively to prepare a standard solution of a single pollutant component with a concentration of 100 mg / L.

[0063] EGs single standard solution: Take E1, E2, E3, EE2, DES, and BPA respectively, and add them to methanol to prepare standard solutions of single pollutant components with a concentration of 100 mg / L.

[0064] The pollutant standard solutions prepared above were mixed to prepare spiked solutions, and then two portions were taken and the pH was adjusted to 6-7 with 1 mol / L NaAC solution and 1 mol / L NaHCO 3 After the solution was adjusted to pH 8, it was covered with aluminum foil and left overnight to obtain two overnight equilibrated spiked solutions with different pH values. The concentration of each pollutant in the spiked solutions was 50 μg / L.

[0065] A MIX adsorption membrane with a diameter of 25 mm and a thickness of 0.5 mm (the adsorption membrane of experimental group 2 in Example 1) and a control HLB adsorption membrane of the same size were placed in 15 mL of the aforementioned spiked solution equilibrated overnight, and adsorbed on a shaker at 200 rpm. After adsorption for 24 hours, 50 μL of aqueous solution sample was taken, and 50 μL of internal standard methanol mixed standard solution (20 ppb PFAS+ILs+DB+SAs+EGs internal standard methanol mixed standard solution) was added. The concentration of the target substance in the solution before and after adsorption was determined using an ultra-high performance liquid chromatography-mass spectrometer to calculate the adsorption rate of the adsorption membrane for the target substance. The results are shown in FIG. Figure 3 shown.

[0066] The key working conditions, parameters and chromatographic conditions set by ultra-high performance liquid chromatography-mass spectrometry are as follows:

[0067] The liquid chromatography column used was a Waters ACUITY UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm), and gradient elution was performed at a flow rate of 0.4 mL·min-1 under mobile phase conditions containing 2 mM ammonium acetate aqueous solution (solvent A) and acetonitrile (solvent B). The mobile phase ratio was varied with the linear gradient program as follows: 0-0.5 min 1% B, 6 min 80% B, 8 min 100% B, 10 min 1% B.

[0068] The mass spectrometer was operated in negative electrospray ionization multiple reaction monitoring (MRM) mode. The target compounds were quantified using the internal standard method.

[0069] Depend on Figure 3 It can be seen that for the spiked solutions with different pH values ​​of pH=6-7 and pH=8, except for SDZ, SCP, SMX, C4, PFHxA, PFBS, and PFBA, there is no significant difference in the adsorption rate of the other target substances between the HLB adsorption membrane and the MIX adsorption membrane. It is worth noting that among the compounds with no significant difference in adsorption rate between the HLB adsorption membrane and the MIX adsorption membrane, the adsorption rate of most compounds at pH=6-7 is lower than that at pH approximately equal to 8, among which PFOSB is the most obvious. In addition, the adsorption rate of SDZ, SCP, and SMX at pH approximately equal to 8 is significantly lower than that of the MIX adsorption membrane at pH=6-7; the adsorption rate of C4, PFHxA, PFBS, and PFBA on the HLB adsorption membrane under both pH conditions is lower than that of the MIX adsorption membrane. Among them, the adsorption rate of C4 and PFBA on the HLB adsorption membrane is less than 40%, while the adsorption rate of the MIX adsorption membrane on various types of target substances is more than 80%. Compared with the HLB adsorption membrane, the MIX adsorption membrane has a higher adsorption rate for the target substances.

[0070] In summary, the results of this repeated experiment still show that the adsorption performance of MIX adsorption membrane is better than that of HLB adsorption membrane.

[0071] Example 3

[0072] In order to further explore the adsorption and elution performance of the mixed adsorption membrane containing MCX resin, more organic pollutants were added than in Example 2, and adsorption and elution experiments were carried out on MCX / MAX-BAPA glue with similar adsorption efficiency and the MIX adsorption membrane of experimental group 2 in Example 1.

[0073] Based on the pollutant standard solution prepared in Example 2, a new pollutant standard solution was prepared:

[0074] Mixed standard solution 4: Take PFBA, PFOA, PFOS, PFHxA, PFBS, PFHpA, PFDoDA, PFUnDA, HFPO-DA, and HFPO-TA standards respectively, add them to methanol and dissolve them to prepare a mixed standard solution of 10 PFAS with a concentration of 100 mg / L.

[0075] Mixed standard solution 5: Take PFPrA, TFMS-Na, PFHD, PFRTD, PFOSB, TFBBA, and OBS standards respectively, add them to methanol and dissolve them to prepare a mixed standard solution of 7 PFAS with a concentration of 100 mg / L.

[0076] Mixed standard solution 6: Take PFOAAmS, PFTrDA, PFTeDA, and 6:2FTS standards respectively, add them to methanol and dissolve them to prepare a mixed standard solution of 4 PFAS with a concentration of 100 mg / L.

[0077] 6:2FTSB methanol single standard solution: Take 6:2FTSB and add it to methanol to prepare a standard solution of a single pollutant component with a concentration of 100 mg / L.

[0078] The prepared pollutant standard solutions are mixed to prepare a spiked solution, and the concentration of each pollutant in the spiked solution is 50 μg / L. After the adsorption experiment is carried out in the same manner as in Example 2, the adsorption film (with a diameter of 25 mm and a thickness of 0.5 mm) is taken out and placed in a PE centrifuge tube, and 2.5 mL of methanol containing 0.5% ammonia water and 2.5 mL of acetonitrile are used for elution. After ultrasonication for 30 minutes, the step is repeated again (i.e., the adsorption film is taken out and placed in new methanol / acetonitrile and ultrasonicated for 30 minutes). Thereafter, 0.1 mL of the eluent is taken and blown to near dryness with nitrogen, and then redissolved with methanol: water in a volume ratio of 1:1. Finally, an ultra-high performance liquid chromatography-mass spectrometer is used for quantitative analysis (the detection method is the same as in Example 2). The adsorption efficiency and elution efficiency are shown in the following table. Figure 4 shown.

[0079] from Figure 4 It can be seen that the elution efficiency of MCX / MAX-BAPA glue for TFBBA, OBS, SAs (SDZ, SMX, SDM), ILs (C10, C8, C6, C4) and other substances is less than 80%. Compared with MCX / MAX-BAPA glue, MIX adsorption membrane shows a stable and higher elution efficiency, which has obvious advantages in mixed adsorption membranes containing MCX resin.

[0080] Example 4

[0081] In this embodiment, the diffusion membrane of the piston-type DGT device is made of a polyacrylamide diffusion membrane, and the filter membrane is a 25 mm polycarbonate filter membrane (0.4 μm) (Whatman). The preparation method of the polyacrylamide diffusion membrane is as follows:

[0082] S1. Prepare polyacrylamide solution: weigh appropriate amount of acrylamide monomer and N,N'-methylenebisacrylamide, add them into ultrapure water and ultrasonically dissolve them into 15wt% polyacrylamide solution. Take 10mL of the above sol, and add 10wt% ammonium persulfate solution and catalyst N,N,N',N'-tetramethylethylenediamine (TEMED) in sequence, and mix well.

[0083] S2, gel preparation: take two glass plates, leave a gap of 1.0 mm in between, inject the diffusion membrane solution prepared in step S1 from the injection port, wait until the solution forms a gel film, pry the glass plates apart and take out the gel film.

[0084] S3. Soak the gel membrane in ultrapure water, changing the water several times until the pH of the aqueous solution is about 7 (soaking for about 24 hours in total). At this time, the gel membrane is fully expanded and colorless. Cut the gel membrane into discs with a diameter of 25 mm to obtain the desired diffusion membrane.

[0085] The filter membrane, the diffusion membrane and the MIX adsorption membrane (diameter 25 mm, thickness 0.5 mm) of the experimental group 2 in Table 1 are placed on the base from top to bottom, and the three layers of membranes are fixed with a cap to assemble a piston-type DGT device containing the MIX adsorption membrane of the present invention (abbreviated as MIX-DGT), the structure of which is as follows: Figure 5 shown.

[0086] MIX-DGT was placed in a 5L spiked solution containing 5 PFAS (PFBA, PFBS, PFHxA, PFOA and PFOS), 2 sulfonamide antibiotics (SMX, SCP), 2 ionic liquids (C6, C10), and 2 estrogens (DES, E1), with the concentration of each pollutant being 20μg / L. Three parallel MIX-DGTs were taken out at 10h, 24h, 48h, 72h, and 108h, and the MIX adsorption membrane was taken out and eluted using the same method as in Example 3. The results are shown in Figure 2. Figure 6 As shown, MIX-DGT can linearly adsorb the target substance within 108 hours, indicating that the non-targeted adsorption membrane prepared by the present invention can be loaded into DGT for the simultaneous collection of organic pollutants in different ionic forms (cationic, anionic, neutral and amphoteric organic pollutants), and has high adsorption efficiency and elution efficiency. Combined with DGT passive sampling technology, non-targeted analysis and accurate quantification of pollutants can be achieved simultaneously.

Claims

1. A method for preparing a non-targeted DGT adsorption membrane for enriching multiple types of new pollutants, characterized in that: The steps include: S1. Purify and activate the resin raw material: use an organic solvent to elute the resin raw material so that the impurities on the adsorption and binding sites of the resin raw material are dissolved in the organic solvent, and then rinse it with ultrapure water and dehydrate it to obtain a purified and activated resin raw material; the resin raw material includes WAX resin and MCX resin; S2, preparing an adsorption film solution: taking the resin raw materials WAX resin and MCX resin treated in step S1, adding them to a crosslinker solution, and then adding an initiator and a catalyst to mix well, wherein the crosslinker solution is a 14-16wt% polyacrylamide solution; the mass ratio of WAX resin, MCX resin, and crosslinker solution is 2-3.5:0.5-2:10; S3, gel preparation: inject the adsorption film solution prepared in step S2 into the gel-forming model, let the solution stand until it solidifies into a gel film, open the gel-forming model, and take out the gel film; S4. Wash and soak the gel membrane in ultrapure water until the pH is neutral to obtain the desired adsorption membrane.

2. The method according to claim 1, characterized in that: The volume ratio of the resin raw material to the organic solvent and ultrapure water used in step S1 is 1:(10-20):(10-20); the organic solvent is methanol.

3. The method according to claim 1, characterized in that: In step S2, the mass ratio of WAX resin, MCX resin and crosslinking agent solution is 2.5-3.5:0.5-1.5:

10.

4. The method according to claim 1, characterized in that: The initiator is ammonium persulfate and the catalyst is TEMED.

5. The method according to claim 1, characterized in that: The gelling model in step S3 is composed of two glass plates, with a gap between the two glass plates for accommodating the adsorption film solution; the thickness of the gel film is 0.3-1.0 mm.

6. The method according to claim 1, characterized in that: The pollutants include cationic, anionic, neutral and amphoteric organic pollutants.

7. A non-targeted DGT adsorption membrane for enriching multiple types of new pollutants, prepared by the method described in any one of claims 1 to 6.

8. A DGT device, characterized in that: The fixed membrane is the DGT adsorption membrane described in claim 7.

9. The DGT device according to claim 8, characterized in that: The DGT device is a piston-type DGT device, comprising a base and a cap, on which a fixed membrane, a diffusion membrane and a filter membrane are placed in sequence from bottom to top, and the cap is used to fix the three layers of membranes.

10. The DGT device according to claim 9, characterized in that: The diffusion membrane is a polyacrylamide gel diffusion membrane, and the filter membrane is a polycarbonate filter membrane.

11. The DGT device according to claim 10, characterized in that: The diffusion membrane is a gel membrane prepared by polymerization and coagulation of a 14-16 wt % polyacrylamide solution.

12. The use of the DGT device according to claim 9 in enriching and analyzing multiple types of new pollutants, characterized in that: The multiple types of new pollutants include cationic, anionic, neutral and amphoteric organic pollutants.

13. The use of the DGT device according to claim 12 in enriching and analyzing multiple types of new pollutants, characterized in that: The multiple types of new pollutants include PFAS pollutants, ionic liquid pollutants, denatonium benzoate, sulfonamide antibiotics, and estrogen.

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