Adsorption material for personal wearable passive sampler as well as preparation method and application of adsorption material

Abstract

The invention belongs to the technical field of preparation of passive adsorption samplers, and particularly relates to an adsorption material for a personal wearable passive sampler as well as a preparation method and application of the adsorption material. The mass of PFAS measured in a sampler can be quantitatively converted into time-weighted air concentration, and different from a traditional wrist strap method which lacks chemical sampling rate and has multi-way exposure, the receptor has good capture capability relative to anionic (PFCAs / PFSAs) and neutral precursors (FTOHs, FTSs and diPAPs), so that the receptor can cover wider-spectrum PFAS in a real scene, and can be used for detecting the content of the PFAS in the real scene. The PFAS concentration in the air can be inversely calculated, and a traceable and comparable quantitative inhalation exposure evaluation method is constructed, so that the key technical defect that the loading capacity of a sampler cannot be reliably extrapolated into real exposure of a human body by the existing personal sampling tool is overcome.

Description

Technical Field

[0001] This invention belongs to the field of passive adsorption sampler preparation technology, and particularly relates to an adsorption material, preparation method and application for a personal wearable passive sampler. Background Technology

[0002] Personal wearable passive samplers are devices worn on the human body to continuously and non-intrusively collect and concentrate specific chemical pollutants in the environment surrounding the human body. Their core principle is to use adsorbent materials with high affinity for the target pollutants, causing these pollutants to spontaneously accumulate in the material from the surrounding environment (air, water, skin vapor, etc.), thereby achieving the collection and detection of the target pollutants. Traditional passive adsorption samplers commonly use materials (such as polydimethylsiloxane (PDMS), high-density polyethylene (HDPE), thermoplastic polyurethane (TPU), and polyurethane foam (PUF)) that primarily rely on non-polar polymer adsorption mechanisms. These materials exhibit good adsorption performance for neutral perfluorinated and polyfluoroalkyl substances (PFAS) precursors (such as perfluoroalkyl ethanol (FTOHs) and perfluorooctane sulfonamide / perfluorooctane sulfonamide ethanol (FOSA / FOSE)). However, these materials have significantly insufficient adsorption capacity for ionic PFAS (such as perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs)). The main reason for this is that the partition coefficient between ionic PFAS and the materials is low and the van der Waals interaction is weak.

[0003] Furthermore, existing "polymer-absorbing" passive materials such as silicone wristbands, PDMS, HDPE / TPU wristbands, and PUF share common limitations in quantitative exposure inversion for PFAS, especially anionic perfluoroalkyl acids (PFAAs), due to limitations in adsorption performance or unknown adsorption rates. Firstly, these hydrophobic polymers primarily rely on partition absorption rather than specific adsorption, resulting in low partition coefficients, small capacities, and premature equilibrium for PFAAs, leading to short linear accumulation windows. Secondly, wristband samples are affected by multiple pathways, including inhalation and skin contact / migration, and the mixed sources make it difficult to deduce the air equivalent concentration from the PFAS mass M enriched in the wristband. Thirdly, the adsorption rates of the aforementioned wristband materials are not clearly defined, making it impossible to invert the true human exposure. Based on these factors, traditional materials cannot reliably convert measured loads into individual true external exposure indicators. Summary of the Invention

[0004] To address the issues of insufficient capacity for volatile fluorides and short linear sampling period in existing passive sampling adsorbents, this paper proposes an adsorbent material, its preparation method, and its application for personal wearable passive samplers. This adsorbent material is prepared by impregnating a polyurethane foam disc (PUF) with an adsorbent (XAD-4) to achieve high-efficiency adsorption using a PFAS material. By uniformly immobilizing the high-specific-surface-area styrene-divinylbenzene copolymer adsorbent resin (XAD-4) on the inner wall of the PUF pores, the total effective capacity of the acceptor phase can be significantly increased and the linear accumulation phase extended. When applied to a personal wearable passive sampler (PAWS), time-weighted passive air sampling can be achieved.

[0005] To achieve the above objectives, the first technical solution of this application discloses a method for preparing an adsorbent material for a personal wearable passive sampler, comprising the following steps:

[0006] S1. Mix XAD-4 adsorbent with an organic solvent to obtain XAD-4 / organic solvent slurry;

[0007] S2. Immerse the PUF adsorption medium in XAD-4 / organic solvent slurry for dip coating;

[0008] S3. The PUF adsorption medium after impregnation is shaped and dried at low temperature to obtain the adsorption material for personal wearable passive samplers.

[0009] Preferably, the particle size range of the XAD-4 adsorbent in S1 is 0.5–1.0 μm.

[0010] Preferably, the concentration of XAD-4 adsorbent in the XAD-4 / organic solvent slurry in S1 is 5.0–8.0 g·L⁻¹.

[0011] Preferably, during the dip-coating process described in S2, the XAD-4 adsorbent powder is kept in suspension, and the dip-coating is repeated until the PUF adsorption medium loading is 401–469 mg.

[0012] Preferably, the low-temperature setting temperature in S3 is 30–40 °C, the time is 5–10 min, and the drying time is 48–72 h.

[0013] And, the adsorbent material for a personal wearable passive sampler obtained according to the above preparation method.

[0014] The second technical solution of this application discloses the application of the above-mentioned adsorbent material for personal wearable passive samplers in the preparation of personal wearable passive samplers. The adsorbent material is used to adsorb target pollutants, and the concentration of target pollutants is determined by determining the sampling rate of the adsorbent material.

[0015] Furthermore, the sampling rate of the adsorbent material is determined by deploying samplers containing the adsorbent material in the target environment and simultaneously deploying high-flow-rate active sampling devices.

[0016] And a personal wearable passive sampler comprising the aforementioned adsorbent material.

[0017] Beneficial effects: This invention can quantitatively convert the mass of PFAS measured in the sampler into time-weighted air concentration, and further combine parameters such as adsorption rate to calculate the individual's daily inhalation exposure. Unlike the traditional wristband method which lacks chemical sampling rate, this receptor has good capture ability for both anionic PFAS (PFCAs / PFSAs) and neutral precursors (FTOHs, FTSs, diPAPs). Therefore, in real-world scenarios, it can cover a wider spectrum of PFAS, achieve traceable and comparable quantitative inhalation exposure assessment, and identify exposure differences related to individual behaviors (such as smoking). This overcomes the key technical shortcoming of existing personal sampling tools that cannot reliably extrapolate "sampler load" to "real human exposure". Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 SIP disks composed of PUF material impregnated with XAD-4.

[0020] Figure 2 PAWS internal structure diagram.

[0021] Figure 3 How to use and wear the PAWS sampler and silicone wristband.

[0022] Figure 4 A comparison of the differences in PFAS species and concentrations captured by the PAWS sampler and the silicone wristband; among them... Figure 4 (A) refers to the captured perfluorocarboxylic acid (PFACs) substances, including perfluorobutyric acid (PFBA), perfluorovalerate (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA). Figure 4(B) refers to the captured perfluorosulfonic acid (PFSA) substances, including perfluorobutyl sulfonic acid (PFBS), perfluoropentyl sulfonic acid (PFPeS), perfluorohexyl sulfonic acid (PFHxS), perfluoroheptyl sulfonic acid (PFHpS), perfluorooctyl sulfonic acid (PFOS), perfluorononyl sulfonic acid (PFNS), and perfluorododecyl sulfonic acid (PFDoS); Figure 4 (C) Other ionic PFAS compounds captured, including perfluorohexyl ethyl sulfonic acid (6:2 FTS), perfluoro2-methyl-3-oxahexanoic acid (HFPO-DA), bis[2-(perfluorohexyl)ethyl] phosphate (6:2 diPAP), and bis[2-(perfluorooctyl)ethyl) phosphate (8:2 diPAP); Figure 4 (D) refers to the captured neutral PFAS substances, including N-methylperfluorooctylsulfonamide (NMeFOSA), N-methylperfluorooctylsulfonamide ethanol (NMeFOSE), N-ethylperfluorooctylsulfonamide ethanol (NEtFOSE), perfluorobutyl ethanol (4:2 FTOH), perfluorohexyl ethanol (6:2 FTOH), perfluorooctyl ethanol (8:2 FTOH), and perfluoro-1-dodecyl alcohol (10:2 FTOH).

[0023] Figure 5 PAWS estimates of PFAS concentration in the air. Detailed Implementation

[0024] To make the technical problems solved, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0025] The first technical solution of this application discloses a method for preparing an adsorbent material for a personal wearable passive sampler (PAWS), comprising the following steps: S1. Mixing XAD-4 adsorbent with an organic solvent to obtain an XAD-4 / organic solvent slurry; S2. Immersing a PUF adsorbent medium in the XAD-4 / organic solvent slurry for impregnation; S3. After impregnation, the PUF adsorbent medium is shaped at low temperature and dried to obtain an adsorbent material for a personal wearable passive sampler.

[0026] In this embodiment, to maintain the purity of the XAD-4 adsorbent and PUF adsorption medium, the XAD-4 adsorbent and PUF adsorption medium can be subjected to steps such as washing and desorption, ultrasonic impurity removal, and Soxhlet extraction to ensure the accuracy and reliability of the prepared adsorption material for sampling the target pollutants.

[0027] In this embodiment, the organic solvent is used to disperse the XAD-4 adsorbent, and is preferably a non-polar organic solvent such as n-hexane or cyclohexane.

[0028] In this embodiment, the average particle size of the XAD-4 adsorbent is 0.75 μm. It has a higher specific surface area and a smaller average pore size (approximately 725 m²·g⁻¹, 40 Å), which is more conducive to increasing capacity compared to XAD-2 (approximately 300 m²·g⁻¹, 90 Å). It is understood that XAD-4 and the organic solvent require dispersion treatment after mixing to ensure that XAD-4 is uniformly dispersed in the organic solvent. The concentration of XAD-4 adsorbent in the XAD-4 / organic solvent slurry is 6.4 g·L⁻¹.

[0029] In this embodiment, during the dip-coating process described in S2, the XAD-4 adsorbent powder is kept suspended to ensure the uniformity of the XAD-4 coating on the PUF adsorption medium. The dip-coating is repeated until the PUF adsorption medium loading is 401-469 mg, preferably 435 mg. After each dip-coating, the excess solution needs to be removed and allowed to drip back. To ensure a uniform coating, it is preferable to change the direction of excess solution reflux after each dip-coating removal.

[0030] In this embodiment, the low-temperature setting temperature in S3 is 30–40 °C, the time is 5–10 min, and after setting, it is dried in a vacuum dryer for 48–72 h, thereby obtaining an adsorbent material for personal wearable passive samplers in which XAD-4 is uniformly fixed in the pores of PUF and the average loading of a single piece is 401–469 mg.

[0031] It should be noted that, throughout the process, the shape of the PUF adsorption medium can be customized according to the needs of the personal wearable passive sampler, such as by preparing it into a PUF disk.

[0032] The second embodiment of this application discloses the application of the adsorbent material for a personal wearable passive sampler in the preparation of the personal wearable passive sampler. The adsorbent material is a core component of the adsorption structure of the personal wearable passive sampler and is used to adsorb target pollutants. By determining the sampling rate of the adsorbent material, the population exposure to the target pollutants can be calculated.

[0033] In a further embodiment, the sampling rate of the adsorbent material is determined by deploying a sampler containing the adsorbent material in the target environment and simultaneously deploying high-flow-rate active sampling devices.

[0034] The adsorption capacity of the adsorbent material and the personal wearable passive sampler described in this application will be explained below through specific embodiments.

[0035] Example 1: Preparation of Adsorbent Material for Personal Wearable Passive Sampler

[0036] S1. PUF pretreatment: PUF dish (diameter 14 cm, thickness 1.35 cm; surface area approximately 365 cm²; mass approximately 4.40 g; volume approximately 207 cm³; density approximately 0.0213 g·cm⁻³) was selected and washed and desorbed sequentially: first washed with water, then extracted with Soxhlet using acetone and petroleum ether for 24 h respectively; after extraction, dried in a vacuum desiccator for 16–20 h, and stored in sealed glassware rinsed with solvent for later use.

[0037] S2. Pretreatment of Adsorbent (XAD-4): XAD-4 was subjected to ultrasonic treatment for 30 min each with methanol, dichloromethane, and n-hexane to remove impurities, and then ground with a planetary ball mill to an average particle size of approximately 0.75 μm. The powder was then placed in a porous filter cartridge and subjected to Soxhlet extraction with methanol, dichloromethane, and n-hexane in that order for 24 h, and dried in a vacuum dryer. XAD-4 was preferred to obtain a higher specific surface area and a smaller average pore size (approximately 725 m²·g⁻¹, 40 Å), which is more conducive to increasing capacity compared to XAD-2 (approximately 300 m²·g⁻¹, 90 Å).

[0038] S3. Preparation of impregnation slurry: Prepare XAD-4 / n-hexane slurry in a clean glass container with a concentration of about 6.4 g·L⁻¹ and a total volume of about 1700 mL; sonicate for about 30 min to disperse it evenly, and keep the powder suspended by magnetic stirring during the impregnation process.

[0039] S4. Immersion-Coating: Hold the PUF disk with clean tweezers / clamps and immerse it completely in the above slurry for about 30 seconds; remove it and allow excess solution to drip back down. Repeat the immersion coating 3 times, changing the dripping direction each time to promote uniform coating.

[0040] S5. Low-Temperature Setting and Drying: After the final dip coating, the PUF disks are placed on pre-cleaned and heated aluminum foil (approximately 30–40 °C, 5–10 min) for low-temperature setting; subsequently, the impregnated PUF disks are placed in a vacuum dryer for 48–72 h. Following the above process, XAD-4 can be uniformly immobilized within the PUF pores, with an average single-disk loading of 401–469 mg, and a novel XAD-4-impregnated PUF adsorbent material, the SIP disk, can be obtained, as shown in the schematic diagram. Figure 1 As shown.

[0041] Example 2: Determining the SIP disk sampling rate and preparing a PAWS with a known sampling rate.

[0042] The SIP disk adsorbent material prepared in Example 1 was deployed in the target environment, and a high-flow-rate active sampling device was simultaneously deployed to determine the sampling rate of the SIP disk. One-eighth of the SIP disk was cut and assembled into a carrier prepared by a 3D printer to fabricate PAWS, as shown below. Figure 2 As shown.

[0043] Experiment 1: Determining the Sampling Rate of a SIP Disk

[0044] The SIP disk prepared in Example 1 was sampled, and high-flow-rate active samplers were deployed in parallel. The sampling rate of the SIP disk was determined by obtaining the time-weighted average air concentration through the high-flow-rate active samplers. The specific method is as follows:

[0045] S1 Joint Deployment and Time-Division Sampling: Simultaneously deploy a SIP passive sampler and a high-volume active sampling device in the target environment (the active sampling device has a daily sampling volume of 1000–1500). The active end continuously collects data in 24-hour increments to obtain the time-series concentration of target PFAS in the air. The SIP disk can be set with multiple sampling durations (1, 3, 7, 14, 21 days) to recover and determine the adsorbed mass in batches. And perform field blanking.

[0046] S2 Selection of linear adsorption range and calculation of average concentration: The linear adsorption phase in the early stage of deployment (first 21 days) was selected for rate calibration.

[0047] S3 Linear Regression to Calculate the Slope: Based on the measured cumulative mass of the SIP disk. Regarding time Perform least squares linear regression to obtain the slope. During the linear adsorption phase, the sampling rate is calculated using the following formula:

[0048] ;

[0049] in The time-weighted average air concentration obtained by S2 corresponding to this linear interval ( This method has been used to calibrate the linear sampling rate of SIP disks for multiple types of PFAS.

[0050] Experimental Result 1: Typical results obtained from indoor / outdoor environmental calibration using the above steps show that a 14cm diameter SIP has a good effect on neutral FTOHs. Approximately 4–5 For ionic PFCAs / PFSAs Approximately 2–5 .

[0051] Experimental Example 2: Preparation of PAWS with a known sampling rate

[0052] S1 cuts the SIP disk into 8 equal parts, with each 1 / 8 of the SIP disk serving as a PAWS absorbent material.

[0053] S2 uses a 3D printer to print a carrier that absorbs the material.

[0054] S3 inserts 1 / 8 of the SIP disk into the carrier, which is equipped with a clamp at the top, to prepare a complete PAWS sampler.

[0055] PAWS's internal structure is as follows Figure 2 As shown.

[0056] Example 3: Application of PAWS sampler in estimating PFAS concentration in air

[0057] The PAWS sampler was prepared using the method described in Example 2, and a silicone wristband was simultaneously deployed on the same subject as a control to measure the concentration of target pollutants in the air. The usage and wearing position of the PAWS and silicone wristband are as follows. Figure 3 As shown. Measurement method: Subjects wore both PAWS and a silicone wristband for two weeks. After recovery, the 48 PFAS in the sampling medium were quantified using the isotope internal standard method: except for FTOHs, all were measured by UHPLC-MS / MS according to EPA Draft Method 1633, and FTOHs were measured by GC-MS. The results were corrected for blank. Subsequently, only the net mass of the PAWS sample was sampled at the established sampling rate. Converted to air equivalent concentration (using the average SIP disk sampling rate calculated in Example 2) Due to the lack of corresponding silicone wristbands... The result is not converted into air concentration.

[0058] Example 1: Comparison of PFAS sampling types and concentrations between PAWS and silicone wristbands

[0059] Experimental results are as follows Figure 4 As shown: PAWS captured a total of 25 PFAS, and PFCAs ( Figure 4 A) Some PFSAs ( Figure 4 B), 6:2 FTS ( Figure 4 C) and most FTOHs Figure 4D) has a higher detection frequency; the median concentration of most PFCAs is higher in PAWS than in silicone wristbands. The SIP disk adsorption medium has good capture capabilities for both anionic PFCAs / PFSAs and neutral precursors (FTOHs, FTSs, diPAPs), thus covering a broader spectrum of PFAS in real-world scenarios. Notably, the 6:2 and 8:2 diPAP levels in silicone wristbands are approximately 10 times higher than in PAWS, suggesting that silicone wristbands may contain exposure signals from non-inhalation pathways. Since silicone wristbands are worn on the wrist and come into direct contact with the skin, there is a high possibility of skin absorption. This multi-pathway exposure characteristic of silicone wristbands makes it difficult to calculate the concentration of PFAS in the air using them.

[0060] Experimental Example 2: Calculation of PFAS Concentration in Air Based on SIP Disk Sampling Rate

[0061] To overcome the shortcomings of existing polymer absorption samplers such as PDMS / HDPE / TPU / PUF / silicone wristbands in accurately reflecting individual PFAS exposure, this invention selects an average value of 4 based on the results of Example 2. Sampling rate as adsorbent material of SIP disk The method for converting PFAS mass measured on PAWS into "air equivalent concentration" is to use the sampling rate of the linear phase of the passive sampler. Multiply by the wearing time t to get the equivalent sampling volume, then divide the mass by the volume:

[0062] ;

[0063] in: The PFAS mass (pg) measured on a single PAWS (SIP wedge). For the corresponding blank correction quality; t represents the sampling rate during the linear adsorption phase of the SIP; t represents the number of days of wear. This represents the ratio of the adsorption medium used relative to the entire SIP. Since each PAWS only uses 1 / 8 of the entire SIP, =1 / 8 (the equivalent air volume is one-eighth of the whole piece). Through this calculation formula, the present invention can quantitatively convert the measured receptor phase mass into the individual's actual inhalation exposure, realizing a comparable and traceable assessment of PFAS exposure in the population.

[0064] The test results are as follows Figure 5 As shown: Using the calculation formula, the average concentrations of PFCAs and PFSAs in the air were 83.4 and 17.6, respectively. After being converted to air concentration, the box curve for FTOHs falls between several hundred and tens of thousands. The present invention can quantitatively convert the mass of PFAS measured in the sampler into time-weighted air concentration. Unlike the traditional wristband method which lacks chemical sampling rate, it can achieve traceable and comparable quantitative inhalation exposure assessment and can identify exposure differences related to individual behaviors (such as smoking). This overcomes the key technical shortcoming of existing personal sampling tools that cannot reliably extrapolate "sampler load" to "real human exposure".

[0065] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for preparing an adsorbent material for a personal wearable passive sampler, characterized in that, Includes the following steps: S1. Mix XAD-4 adsorbent with an organic solvent to obtain XAD-4 / organic solvent slurry; S2. Immerse the PUF adsorption medium in XAD-4 / organic solvent slurry for dip coating; S3. The PUF adsorption medium after impregnation is shaped and dried at low temperature to obtain the adsorption material for personal wearable passive samplers.

2. The preparation method according to claim 1, characterized in that, The particle size range of the XAD-4 adsorbent described in S1 is 0.5–1.0 μm.

3. The preparation method according to claim 1, characterized in that, The concentration of XAD-4 adsorbent in the XAD-4 / organic solvent slurry described in S1 is 5.0–8.0 g·L⁻¹.

4. The preparation method according to claim 1, characterized in that, During the dip-coating process described in S2, the XAD-4 adsorbent powder is kept in suspension, and the dip-coating is repeated until the PUF adsorption medium loading is 401–469 mg.

5. The preparation method according to claim 1, characterized in that, The low-temperature setting temperature of S3 is 30–40℃, the time is 5–10 min, and the drying time is 48–72 h.

6. The adsorbent material for a personal wearable passive sampler obtained by any of the preparation methods described in claims 1-5.

7. The application of the adsorbent material for a personal wearable passive sampler according to claim 6 in the preparation of a personal wearable passive sampler, characterized in that, The adsorbent material is used to adsorb the target pollutant, and the concentration of the target pollutant is determined by determining the sampling rate of the adsorbent material.

8. The application according to claim 7, characterized in that, The sampling rate of the adsorbent material is determined by deploying a sampler containing the adsorbent material in the target environment, while simultaneously deploying a high-flow-rate active sampling device in parallel.

9. A personal wearable passive sampler, characterized in that, It contains the adsorbent material as described in claim 6.

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