Multi-property iron-carbon derivative material for adsorbing remediation of water body pfas pollution and preparation method and application thereof

Abstract

The application provides a multi-property iron-carbon derivative material for adsorbing and repairing PFAS pollution of water bodies and a preparation method and application thereof. The preparation method comprises the following steps: in step one, a ferric salt is dissolved in N,N-dimethylformamide, a ligand terephthalic acid is added under stirring, and a precursor is synthesized through a solvothermal method; in step two, the precursor is heat-treated in an inert atmosphere to obtain the multi-property iron-carbon derivative material. The application of the material in environmental remediation includes: using the above multi-property iron-carbon derivative material as an adsorbent, and assisting with a cation complexing agent, to adsorb and purify PFAS polluted water. The multi-property iron-carbon derivative material is synthesized through a two-step method of solvothermal-heat treatment, so that the material has high hydrophobicity, a two-dimensional-three-dimensional close interface and magnetism, can quickly remove PFAS of various structures and carbon chain lengths, and can realize material separation within 30 seconds after the PFAS is removed by adsorption, without causing secondary pollution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water body environmental pollution treatment, and relates to a multi-property iron-carbon derivative material for adsorbing and repairing PFAS pollution in a water body and a preparation method and application thereof. BACKGROUND

[0002] Perfluoroalkyl substances (PFAS) have been proven to cause serious harm to ecology and human health due to their stable chemical properties and long-term existence in the environment. Advanced oxidation technologies widely used in organic pollutant control have limited degradation of PFAS, and even advanced reduction technologies based on hydrated electrons are difficult to completely mineralize PFAS. A large number of water-soluble, highly toxic and difficult-to-remove short-chain intermediates will enter the environment, causing unpredictable harm, and since many countries lack control and discharge standards for PFAS degradation products. Some theoretically easier-to-dispose PFAS substitutes are designed for production and daily life, such as GenX, a substitute for perfluorooctanoic acid (PFOA) containing ether bonds. However, this strategy is obviously unsuccessful, as many toxicity studies have shown that GenX has similar toxicity to PFOA. The removal efficiency of GenX through sedimentation, ozone oxidation, biological filtration and disinfection processes in wastewater treatment plants is negligible, and the adsorption capacity of GenX on activated carbon and other adsorption materials is also lower than that of PFOA. Therefore, many countries have strengthened the control of PFAS. Recently, the United States Environmental Protection Agency (EPA) revised its lifetime health recommendations for PFOA and perfluorooctanesulfonic acid (PFOS) in drinking water, setting more stringent limits of 0.004 and 0.02 ng L -1 , respectively, while the previous comprehensive concentration limit was 70 ng L -1 . The recommended standard for GenX in drinking water has also been reduced to 10 ng L -1 . Hereinafter, this poses a more severe challenge for the rapid and safe removal of PFAS in contaminated water. In contrast, from the perspective of health and policy guidance, faster and safer adsorption methods both show unique advantages.

[0003] However, the commonly used activated carbon and resin adsorbents still have certain disadvantages, such as low adsorption capacity, low removal rate, difficulty in recovery and separation, and especially difficulty in effective co-adsorption of long-chain and short-chain PFAS occurring simultaneously in water.

[0004] To address this, the inventors of this application constructed an environmentally friendly iron-based MOF (Metal Organic Framework) derivative, H:MIL-101(Fe), with a 3D / 2D structure of metal oxides immobilized on a carbon substrate. This derivative can completely remove PFOA from pure water within 5 minutes and achieve separation within 30 seconds. H:MIL-101(Fe) maintains its initial adsorption percentage after four cycles of PFAS adsorption, demonstrating structural stability. Furthermore, a more hydrophobic long-chain complex was synthesized by mixing CTAB with PFAS. At pH 7.0, six PFAS containing 4-8 carbon atoms in surface water could be completely co-adsorbed within ten minutes. This research develops a novel adsorbent material that can match PFAS types, achieving effective co-adsorption of PFAS in water, and is expected to ensure water safety under increasingly stringent PFAS regulations. Summary of the Invention

[0005] The purpose of this application is to provide a multi-characteristic iron-carbon derivative material H:MIL-101(Fe) for adsorbing and remediating PFAS pollution in water bodies, its preparation method, and its application. This material is a multi-characteristic iron-carbon derivative material with high hydrophobicity, a two-dimensional to three-dimensional tight interface, and magnetism. It can achieve complete removal of PFAS with different carbon chain lengths and structures in natural water bodies within minutes and overcomes the interference of naturally dissolved organic matter and anions. It can be used for actual water body remediation.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] In a first aspect, this application provides a method for preparing a multi-characteristic iron-carbon derivative material for adsorbing and remediating PFASs pollution in water bodies, comprising:

[0008] Step 1: Dissolve ferric salt in DMF (N,N-dimethylformamide), add ligand terephthalic acid (H2BDC) under stirring, and synthesize the precursor, MIL-101(Fe), by solvothermal method.

[0009] Step two involves heat-treating the precursor in an inert atmosphere to obtain the multi-characteristic iron-carbon derivative material, namely H:MIL-101(Fe). This iron-carbon derivative material is black and possesses various properties, such as high hydrophobicity, rich in oxygen vacancies, a tight two-dimensional-three-dimensional interface, and magnetism.

[0010] In the above preparation method, as a preferred embodiment, it further includes:

[0011] In step two, the inert atmosphere refers to a nitrogen atmosphere or an inert gas atmosphere. The heat treatment is an incomplete carbonization heat treatment. The heat treatment can allow part of the organic ligand terephthalic acid to be carbonized to form a hydrophobic surface, while generating a cubic Fe3O4 magnetic skeleton, oxygen vacancies and π-π bonds. Through hydrophobic interaction, the long-chain PFAS hydrophobic tail is combined, and the positively charged oxygen vacancies are used to electrostatically attract the target pollutant PFAS head carboxylic acid / sulfonic acid group, thereby achieving the rapid co-adsorption removal of PFAS with different structures and different chain lengths.

[0012] In the above preparation method, as a preferred embodiment, the method further comprises:

[0013] Before the heat treatment, the precursor precipitate is washed with DMF and anhydrous ethanol alternately for two times each, and then transferred to methanol for purification treatment; preferably, the washing comprises: centrifuging the precursor suspension generated by the solvothermal method in step one to remove the supernatant, adding an appropriate amount of DMF or anhydrous ethanol washing liquid, and shaking the washing liquid on a shaker at 2500 r / min for 30 min; preferably, the purification treatment comprises: soaking the precursor precipitate in methanol for 12 hours; preferably, after the purification treatment, the precursor is obtained by further separation, drying and grinding treatment; more preferably, the separation treatment is a centrifugal treatment, and the drying treatment is a vacuum drying treatment.

[0014] In the above preparation method, as a preferred embodiment, in step one, the trivalent iron salt can be selected from at least one of ferric chloride, ferric nitrate, ferric sulfate and the like.

[0015] In the above preparation method, as a preferred embodiment, in step one, the molar ratio of the trivalent iron salt to terephthalic acid is 1:1; as the solvent, N,N-dimethylformamide can be used as long as it is sufficient to ensure that the solid can be dissolved, and more preferably, in step one, the molar ratio of N,N-dimethylformamide to trivalent iron salt to terephthalic acid is 50-300:1:1.

[0016] In the above preparation method, as a preferred embodiment, in step one, after the trivalent iron salt and H2BDC are added to DMF, the iron salt and the organic ligand are completely dissolved and uniformly mixed by constant stirring at 500-1000 r / min (such as 600 r / min, 700 r / min, 800 r / min, 900 r / min, etc.) for 10-60 min (such as 15 min, 20 min, 30 min, 40 min, 50 min, 55 min, etc.), and then the precursor is synthesized by a solvothermal method. More preferably, the stirring speed is 800 r / min, and the stirring time is 60 min.

[0017] In the above preparation method, as a preferred embodiment, in step one, in the solvothermal method, the reaction temperature is 140-160℃ (such as 142℃, 145℃, 150℃, 155℃, etc.), and the reaction time is 10-14h (such as 10.5h, 11h, 12h, 13h, 13.5h, etc.); more preferably, the reaction temperature is 150℃, and the reaction time is 12h.

[0018] In the above preparation method, as a preferred embodiment, in step two, the heat treatment includes first heating to 280-320℃ (such as 290℃, 300℃, 310℃, etc.) and then constant temperature anaerobic calcination for 2-4h (such as 2.5h, 3h, 3.5h, etc.); then continue to heat to 400-1000℃ (such as 500℃, 600℃, 700℃, 800℃, 9000℃, etc.) and then constant temperature anaerobic calcination for 4-12h (such as 4.5h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, etc.). Preferably, the heating rate is 4-10℃ / min (such as 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, etc.).

[0019] In the above preparation method, as a preferred embodiment, in step two, the heat treatment includes: grinding the precursor into powder, then putting it into a corundum box, and then heating to 300℃ at a heating rate of 5±1℃ / min in a tube furnace with nitrogen or inert gas, and then constant temperature anaerobic calcination for 3h; then continue to heat to 500℃ and keep for 5h, and then collect the product after natural cooling.

[0020] In a second aspect, the application also provides a multi-property iron-carbon derivative material for adsorbing and repairing PFAS pollution in water bodies, which is prepared by the above method.

[0021] In a third aspect, the application also provides an application of the above multi-property iron-carbon derivative material in environmental remediation, which includes: using the above multi-property iron-carbon derivative material as an adsorbent, and assisting with a cation complexing agent to adsorb and purify PFAS polluted water bodies.

[0022] Optionally, in the above application, the PFAS is selected from at least one of PFOA, PFHpA, PFHxA, GenX, PFPeA and PFBA. Preferably, in the PFAS polluted water body, the concentration of the PFAS is 0.1-6mg / L (such as 0.6mg / L, 1mg / L, 2mg / L, 3mg / L, 4mg / L, 5mg / L, etc.).

[0023] Optionally, in the above application, the cation complexing agent is selected from at least one of CTAB, dodecyl dimethyl amine oxide, cation panthenol, and octadecyl trimethyl ammonium chloride, etc.

[0024] Preferably, in the above application, CTAB is used as a complexing agent, the amount of CTAB is 10-25 mg / L (such as 12 mg / L, 15 mg / L, 18 mg / L, 20 mg / L, 22 mg / L, 24 mg / L, etc.), the amount of the adsorbent is 0.1-0.5 g / L (such as 0.2 g / L, 0.3 g / L, 0.4 g / L, etc.), and the treatment time is within 8 hours (such as 0.1 hour, 0.5 hour, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, etc.); more preferably, the treatment time is within 30 minutes; further, the treatment time is within 10 minutes.

[0025] Compared with the prior art, the beneficial effects of the present application include but are not limited to:

[0026] 1) The preparation method provided in the present application is a simple two-step method of solvothermal-heat treatment to synthesize the multi-property iron-carbon derivative material H:MIL-101(Fe), which makes the H:MIL-101(Fe) material have high hydrophobicity, a two-dimensional-three-dimensional close interface and magnetism, shortens the preparation time, and the steps are also simpler. The prepared H:MIL-101(Fe) material can quickly remove various PFASs with different structures and carbon chain lengths, and can realize material separation within 30 seconds after the adsorption removal of perfluoroalkyl substances, without producing secondary pollution.

[0027] 2) The water body remediation method provided in the present application uses CTAB to strengthen the adsorption removal of PFASs by H:MIL-101(Fe) material, and establishes a high-efficiency water body pollution remediation system. Through the adsorption performance analysis of PFASs contaminated water samples in simulated surface water, it is found that the system can achieve the purpose of high-efficiency remediation of PFAS water pollution.

[0028] 3) The present application first develops a new type of high-hydrophobic and two-dimensional-three-dimensional close interface magnetic iron-carbon derivative material H:MIL-101(Fe) material, and verifies that the material can efficiently remove various PFASs in water bodies. In practical applications, the amount of the added material and the complexing agent needs to be adjusted according to the content of different PFASs in the contaminated water body. The H:MIL-101(Fe) material provided in the present application can efficiently remove PFASs and realize rapid recovery of the material, and can completely remove PFASs with different structures and carbon chain lengths, which has high value in water body pollution treatment.

[0029] 4) The application ultimately repairs six PFASs (PFOA, PFHpA, PFHxA, GenX, PFPeA and PFBA) with concentrations of 0.1-1 mg / L in surface water by using the magnetic iron-carbon derivative H:MIL-101(Fe) material with high hydrophobicity and two-dimensional-three-dimensional close interface, and the effects of water source, adsorbent and complexing agent content and pH on the adsorption removal of PFAS are discussed.

[0030] H:MIL-101(Fe) for 1 mg / L -1 of PFOA is stably removed within 30 min and the material is quickly recovered. After further adding the complexing agent CTAB, the adsorption performance of the material for six PFASs with different carbon chains and structures in surface water is significantly improved. When the dosage of H:MIL-101(Fe) is increased from 0.3 g / L -1 to 0.5 g / L -1 , it is found that the six PFASs are completely removed within 10 min at the natural pH value of surface water. Therefore, the new magnetic iron-carbon derivative material H:MIL-101(Fe) with high hydrophobicity and two-dimensional-three-dimensional close interface provides a possibility for effective PFASs pollution remediation in actual water bodies, and has important scientific research value and application significance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 and Figure 2 show the microstructure of the Fe-MOF material MIL-101(Fe) and its heat-treated derivative H:MIL-101(Fe) prepared in Example 1; wherein (a) is a SEM image of MIL-101(Fe) with a magnification of 50,000 times; (b)-(g) are SEM images of H:MIL-101(Fe) with a magnification of 20,000 times, wherein (b) is a SEM image; (c) and (d) are TEM images; (e) and (f) are HRTEM images; and (g) is a SEM / EDS image, wherein (g1), (g2) and (g3) are C element image, O element image and Fe element image, respectively.

[0032] Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 are structure determination diagrams of the Fe-MOF and its heat-treated derivative material prepared in Example 1 and the comparative example; wherein (a) is an XRD pattern; (b) is a TFIR spectrum; Figure 4 is a Zeta potential diagram; Figure 5 , Figure 6 , Figure 7Nitrogen adsorption-desorption curves and pore size distribution of MIL-101(Fe), H:MIL-101(Fe) and H:NH2-MIL-101(Fe), respectively.

[0033] Figure 8 The H:MIL-101(Fe) prepared in Example 1 was used for cyclic adsorption of 1 mg L -1 The curve of PFOA; Figure 9 The schematic diagram of rapid separation and recovery of H:MIL-101(Fe) material is shown. Figures 10-13 The structure characterization diagrams of H:MIL-101(Fe) material after adsorption and desorption of PFOA, respectively; wherein, Figure 10 XDR spectrum; Figure 11 XPS full scan spectrum; Figure 12 Fourier transform infrared spectrum; Figure 13 SEM / EDS spectrum of H:MIL-101(Fe) material after desorption of PFOA.

[0034] Figure 14 The surface hydrophobicity of Fe-MOF and its derivative materials prepared in Example 1 and Comparative Example is shown, wherein (a) shows the contact angle of MIL-101(Fe); (b) shows the contact angle of H:NH2-MIL-101(Fe); (c) shows the contact angle of H:MIL-101(Fe); Figure 15 (d) and (e) in show the oxygen vacancy signal diagram measured by EPR (electron paramagnetic resonance), Figure 16 The surface potential distribution of non-deprotonated PFOA at pH = 3 is shown using Fukui function; Figure 17 XPS C 1s spectrum of MIL-101(Fe), H:MIL-101(Fe) and H:NH2-MIL-101(Fe).

[0035] Figure 18 The adsorption performance test results of H:MIL-101(Fe) on 1 mg / L PFBA in surface water at pH = 3 are shown. -1 The mixed adsorption performance test results of H:MIL-101(Fe) on six PFAS with a concentration of 1 mg / L in surface water.

[0036] Figure 19 The adsorption performance test results of H:MIL-101(Fe) on six PFAS with a concentration of 1 mg / L in ultrapure water, respectively. -1 The adsorption performance test results of H:MIL-101(Fe) on six PFAS with a concentration of 1 mg / L in ultrapure water, respectively.

[0037] Figure 20 The results of the adsorption and removal test of 1 mg / L PFBA in surface water with and without the addition of CTAB are compared.

[0038] Figure 21 The results show that at pH 3.0, the initial concentration of six PFAS in surface water was 1 mg / L, and the dosage of H:MIL-101(Fe) was 0.3 g / L. -1 Initial CTAB concentration C 0(CTAB) =10mg L -1 Results of mixed adsorption removal performance test.

[0039] Figure 22 The results show that at pH 7.0, the initial concentration of six PFAS in surface water was 1 mg / L, and the dosage of H:MIL-101(Fe) was 0.5 g / L. -1 C 0(CTAB) =25mg L -1 Results of mixed adsorption removal performance test.

[0040] Figure 23 The initial concentrations (C0) of six PFAS in surface water at pH = 7.0 are shown. 0(PFAS) Both were 0.1 mg / L, and the dosage of H:MIL-101(Fe) was 0.3 g / L. -1 C 0(CTAB) =10mg L -1 Results of mixed adsorption removal performance test.

[0041] Figure 24 The changes in surface hydrophobicity after adsorption of CTAB in combination with H:MIL-101(Fe) are shown.

[0042] Figure 25 The changes in surface hydrophobicity after desorption of CTAB combined with H:MIL-101(Fe) are shown.

[0043] Figure 26 A schematic diagram of the CTAB-enhanced PFAS co-adsorption mechanism is shown.

[0044] Figure 27 The adsorption performance of adsorbent H:MIL-101(Fe) at a dosage of 0.3 g / L for 1 mg / L PFOA in ultrapure water at pH 3, 5 and 7 is shown. Detailed Implementation

[0045] The following embodiments are provided to facilitate a better understanding of this application, but are not intended to limit the scope of this application.

[0046] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0047] Unless otherwise specified, all other experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0048] Example 1

[0049] (I) Preparation of precursor MIL-101(Fe):

[0050] Add 2 mmol FeCl3·6H2O to 43 mL DMF (N,N-dimethylformamide), and after it is fully dissolved, add 2 mmol of ligand H2BDC (terephthalic acid) to the above solution while stirring at 800 r / min. The molar ratio of DMF:FeCl3·6H2O:H2BDC is approximately 279:1:1. Stir for 1 h to fully dissolve. After complete dissolution, the solution was transferred to a polytetrafluoroethylene-lined reactor and reacted at 150°C for 12 hours to generate the precursor MIL-101(Fe). The precursor suspension was centrifuged, and the supernatant was discarded to obtain the precursor precipitate. The precursor precipitate was washed twice each with DMF and anhydrous ethanol (each wash was performed by shaking at 2500 rpm for 30 min on a shaker) to remove unreacted iron salt impurities. Then, it was transferred to methanol and soaked for 12 hours to remove DMF from the material pores, completing the purification process. After centrifugation to separate the solid and liquid components, the solution was freeze-dried to obtain the precursor MIL-101(Fe), which was then ground into powder for later use.

[0051] (II) Synthesis of iron-carbon derivative material H:MIL-101(Fe) material:

[0052] Weigh 1g of precursor MIL-101(Fe) and place it in a corundum boat. Transfer it to a tube furnace and purge with nitrogen atmosphere for 30min. Then, heat the furnace to 300℃ at a heating rate of 5±1℃ / min and anaerobic calcine at a constant temperature for 3h. Subsequently, continue heating at a heating rate of 5±1℃ / min to 500℃ and hold for 5h. After natural cooling, collect the iron-carbon derivative H:MIL-101(Fe) material.

[0053] Comparative Example 1

[0054] (I) Preparation of precursor NH2-MIL-101(Fe):

[0055] This step is exactly the same as in Example 1, except that the ligand is replaced with H2BDC-NH2 (2-aminoterephthalic acid) to prepare the precursor NH2-MIL-101(Fe).

[0056] (II) Synthesis of iron-carbon derivative material H:MIL-101(Fe) material:

[0057] This step is exactly the same as in Example 1, except that the precursor NH2-MIL-101(Fe) is used to prepare the iron-carbon derivative H:NH2-MIL-101(Fe) material.

[0058] Test Example

[0059] (III) Characterization of materials such as H:MIL-101(Fe):

[0060] The surface morphology of the samples was analyzed using a scanning electron microscope (SEM) (Model: SU3500, Japan). The surface morphology of the samples was further analyzed using a transmission electron microscope (TEM) (Model: TF20 Jeol 2100F). Before detection, the samples were dispersed in anhydrous ethanol, and the suspension was dropped onto a copper mesh and air-dried naturally. Surface structure analysis of H:MIL-101(Fe) was performed using an X-ray powder diffractometer (XRD) (Model: Rigaku Smartlab SE), X-ray photoelectron spectroscopy (XPS) (Model: Thermo Fisher Scientific K-Alpha spectrometer). Hydrophilic / hydrophobic analysis of H:MIL-101(Fe) and other materials was performed using a contact angle / surface tension meter (Chengde Ding Sheng JY-82C video contact angle meter).

[0061] (IV) Test of the rapid adsorption and removal performance of materials such as H:MIL-101(Fe) on PFAS in water body:

[0062] The adsorption experiment method is as follows: first, 50 mL of reaction solution containing PFAS is prepared in a 100 polypropylene (PP) beaker using surface water (taken from the Dagu sewage river in Jinnan District) or ultrapure water, and then 1 mol / L of HCl or NaOH solution is used to adjust the solution pH to the specified pH. After the pH is stable, a certain amount of adsorbent is weighed and added to the reaction solution (the addition of the material does not affect the pH of the system), and the adsorbent is immersed in the reaction solution at a temperature of 25°C by magnetic stirring at a speed of about 800 r / min for a period of time. In the dynamic adsorption experiment, 1 mL of the suspension is taken at a set time interval, and then the adsorbent is filtered through a polyether sulfone membrane with a pore size of 0.22 μm, and the first 0.3 mL of filtrate is discarded to eliminate the influence of the membrane on the interception of PFAS. An appropriate amount of filtrate is diluted with methanol, mixed thoroughly, and then transferred to a plastic liquid phase sample vial. The concentration of PFAS in the filtrate is analyzed using HPLC-MS / MS.

[0063] The desorption experiment method is as follows: after the adsorption experiment is completed, the reaction solution is filtered using a polyether sulfone membrane with a pore size of 0.22 μm, and the intercepted adsorbent is transferred to a 15 mL plastic centrifuge tube. 10 mL of analytical grade anhydrous methanol is added, and then ultrasonic treatment is performed for 10 min to elute the adsorbed PFAS. After ultrasonic treatment, solid-liquid separation is performed using a nylon organic membrane with a pore size of 0.22 μm. When the elution process is repeated for the third time, no PFAS is detected in the eluent, so the elution process is repeated three times with 10 mL of methanol.

[0064] (1) The adsorption effect of different pollutants PFAS species under different water environments: In this experiment, six different carbon chain lengths and structures of PFAS, PFOA (perfluorooctanoic acid, C8), PFHpA (perfluoroheptanoic acid, C7), PFHxA (perfluorohexanoic acid, C6), GenX (hexafluoropropylene dimer acid, C6), PFPeA (perfluoropentanoic acid, C5) and PFBA (perfluorobutyric acid, C4) mixed solution was prepared with surface water, wherein the initial concentration of each PFAS solution was 1 mg / L -1 , the total initial concentration of PFAS was 6 mg / L -1 ; at the same time, six different carbon chain lengths and structures of PFAS, PFOA (C8), PFHpA (C7), PFHxA (C6), GenX (C6), PFPeA (C5) and PFBA (C4) single component solution were prepared with ultrapure water, and the initial concentration of each PFAS solution was set to 1 mg / L -1 , the adsorbent H:MIL-101(Fe) dosage was 0.3 g / L -1 at pH = 3. The results are shown in Figure 18 and Figure 19 , Figure 18 , which shows the mixed adsorption performance test results of six PFAS in surface water by 0.3 g / L -1 H:MIL-101(Fe) at pH = 3; Figure 19 , which shows the adsorption performance test results of six PFAS in ultrapure water by 0.3 g / L -1 H:MIL-101(Fe) at pH = 3.

[0065] (2) The influence of adding complexing agent on the adsorption performance of CTAB in surface water under different pH conditions: This experiment has four groups, and the pollutant PFAS is selected as PFBA (C4) with an initial concentration of 1 mg / L, and the reaction time is 8 h. The other process conditions are different as follows: 1) pH = 3.0, CTAB dosage 10 mg / L, adsorbent H:MIL-101(Fe) dosage 0.3 g / L; 2) pH = 9.0, CTAB dosage 10 mg / L, adsorbent H:MIL-101(Fe) dosage 0.3 g / L; 3) pH = 3.0, CTAB dosage 10 mg / L, adsorbent H:MIL-101(Fe) dosage 0 g / L; 4) pH = 3.0, CTAB dosage 0 mg / L, adsorbent H:MIL-101(Fe) dosage 0.3 g / L. The results are shown in Figure 20 .

[0066] (3) Adsorption performance test of PFAS with six different carbon chain lengths and structures - PFOA (C8), PFHpA (C7), PFHxA (C6), GenX (C6), PFPeA (C5) and PFBA (C4) under mixed pollution conditions: This experiment has three groups: 1) six PFAS mixed pollution water is prepared with surface water, the initial concentration of each PFAS is 1 mg / L, the total mass concentration of each PFAS in the mixed pollution water is 6 mg / L, pH = 3.0, CTAB dosage is 10 mg / L, adsorbent H: MIL-101 (Fe) dosage is 0.3 g / L, reaction time is 8 h; 2) six PFAS mixed pollution water is prepared with surface water, the initial concentration of each PFAS is 1 mg / L, the total mass concentration of each PFAS in the mixed pollution water is 6 mg / L, pH = 7.0, CTAB dosage is 25 mg / L, adsorbent H: MIL-101 (Fe) dosage is 0.5 g / L, reaction time is 60 min; 3) six PFAS mixed pollution water is prepared with surface water, the initial concentration of each PFAS is 0.1 mg / L, the total mass concentration of each PFAS in the mixed pollution water is 0.6 mg / L, pH = 7.0, CTAB dosage is 10 mg / L, adsorbent H: MIL-101 (Fe) dosage is 0.3 g / L, reaction time is 60 min. The results are shown in Figure 21 , Figure 22 , Figure 23 .

[0067] (4) Test the effect of CTAB on the hydrophobicity of H: MIL-101 (Fe) material after adsorbing PFAS (PFOA is selected): The H: MIL-101 (Fe) material after adding CTAB and completing adsorption in the experiment (3) of part (3) of this test embodiment is filtered and separated, and then the contact angle of the H: MIL-101 (Fe) material is tested using a contact angle instrument after drying at 105°C. The results are shown in Figure 23 . At the same time, after the H: MIL-101 (Fe) material after adding CTAB and completing adsorption is filtered and separated, methanol is used to elute the PFAS on the H: MIL-101 (Fe) material, and then the contact angle of the H: MIL-101 (Fe) material is tested using a contact angle instrument after drying at 105°C. The results are shown in Figure 24 . Figure 25

[0068] ​(5) The influence of the pH of the reaction system on the adsorption performance of the H:MIL-101(Fe) material: In order to further verify the anti-interference of the H:MIL-101(Fe) material to the pH of the water body, different pH values were set, 3, 5 and 7 respectively, the dosage of the adsorbent H:MIL-101(Fe) material was 0.3 g / L, the pollutant PFAS selected PFOA was dissolved in ultrapure water, the initial concentration was 1 mg / L, and the reaction time was 8 h. The results are shown in Figure 27 . It can be seen from Figure 27 that the H:MIL-101(Fe) has the best adsorption capacity for PFOA at pH = 3, and the removal capacity of PFOA is proportional to the solution acidity, because the dissociation constant pKa of the PFOA molecule is about 3.5, and at pH = 3, deprotonation does not occur, and the longer molecular length is retained, so that the material and the PFOA molecule have stronger hydrophobic interaction, further confirming that the hydrophobic interaction is the main mechanism of the H:MIL-101(Fe) adsorbing PFAS.

[0069] (6) H:MIL-101(Fe) material cyclic adsorption experiment: The pollutant PFAS selected PFOA, and PFOA was added to ultrapure water to prepare a solution with an initial concentration of 1 mg / L -1 , pH = 3.0, without adding CTAB, and the dosage of the adsorbent H:MIL-101(Fe) material was 0.3 g / L; after the adsorption and desorption experiments were completed, the adsorbent filter cake was dried at 105°C for 12 h and then ground and collected, and the regenerated adsorbent was used to repeat the adsorption-desorption-regeneration experiment, and so on, the cyclic test was repeated for multiple times, and the results of the cyclic adsorption experiment in Figure 8 were obtained.

[0070] (7) H:MIL-101(Fe) material separation performance test after 1 mg / L PFOA adsorption was completed: After 0.3 g / L H:MIL-101(Fe) material completed adsorption of 1 mg / L PFOA at pH = 3.0 (i.e. the first adsorption was completed in the experiment in part (6) of the present test example), the H:MIL-101(Fe) material in the suspension liquid was separated by using a magnet, and the results showed that the solid-liquid separation could be realized within 30 s, as shown in Figure 9 .

[0071] (V) Mechanism exploration of the adsorption of iron-carbon derivative H:MIL-101(Fe) material on PFASs:

[0072] To investigate the adsorption mechanism of PFAS by H:MIL-101(Fe), the surface properties and pore structure of H:MIL-101(Fe) and its precursor MIL-101(Fe) were analyzed and compared using a contact angle / surface tension meter, specific surface area and pore size / volume analyzer, X-ray photoelectron spectroscopy, and electron paramagnetic resonance spectroscopy. The results demonstrate that MIL-101(Fe) is a magnetic iron-carbon material simultaneously possessing a highly hydrophobic surface, rich in oxygen vacancies, micro-nano pores, and a two-dimensional to three-dimensional tight interface. Its excellent adsorption performance for PFAS is a synergistic process involving electrostatic attraction and π-π interactions under the dominance of hydrophobic interactions. In summary, H:MIL-101(Fe) achieves efficient co-removal of multiple PFAS from surface water, while also enabling rapid material recovery.

[0073] (VI) Experimental results

[0074] 1. Material characterization

[0075] Figure 1 and Figure 2 The microstructures of the Fe-MOF material MIL-101(Fe) and its heat-treated derivative H:MIL-101(Fe) are shown. (a) is a scanning electron microscope (SEM) image of MIL-101(Fe) at 50,000x magnification; (b)-(g) are SEM images of H:MIL-101(Fe) at 20,000x magnification, where (b) is a SEM image; (c) and (d) are TEM images; (e) and (f) are HRTEM images; (g) is a SEM / EDS image, (g1) is a C element image, (g2) is an O element image, and (g3) is a Fe element image. Scanning electron microscopy (SEM) revealed that MIL-101(Fe) is an octahedron with a uniform morphology, smooth surface, and a size between 500-1000 nm (see [link to SEM]). Figure 1 (a)). During heat treatment, the escape of carbon ligands leads to the breakage of the MOF structure, forming a 2D / 3D composite structure in which three-dimensional iron oxide particles grow on a two-dimensional carbon substrate (see (a)). Figure 1 (b)-(d)). HRTEM revealed a uniform lattice spacing of 0.24 nm on the octahedral particles, corresponding to the {222} crystal plane of Fe3O4, confirming the escape of organic ligands to form a three-dimensional metal oxide framework (see [reference]). Figure 1 (e) and (f) in the table. SEM / EDS results of randomly selected regions show that the distribution of C and O elements is relatively uniform, while the distribution of Fe element is more concentrated at the particle level (see [reference]). Figure 2 The results for (g), (g1), (g2), and (g3) are consistent with those of HRTEM.

[0076] Figure 3 , Figure 4, Figure 5 , Figure 6 , Figure 7 The images show the structure of Fe-MOF and its heat-treated derivatives; where (a) is the XRD pattern and (b) is the TFIR spectrum. Figure 4 This is a Zeta potential diagram; Figure 5 , Figure 6 , Figure 7 Nitrogen adsorption-desorption curves and pore size distributions for MIL-101(Fe), H:MIL-101(Fe), and H:NH2-MIL-101(Fe), respectively. The phases of the synthesized materials were identified by XRD (see [link to XRD diagram]). Figure 3 (a) indicates that the diffraction peaks of Fe-MOF disappeared after heat treatment, and the appearing metal diffraction peaks correspond to Fe3O4 (PDF (i.e., standard diffraction card) card number #99-0074), Fe 2.94 O4 (PDF card number #86-1361) and Fe (PDF card number #87-0721). Based on the XRD diffraction peak signals and the use of different ligands H2BDC (terephthalic acid) and H2BDC-NH2 (2-aminoterephthalic acid), two Fe-MOF materials, namely MIL-101(Fe) and NH2-MIL-101(Fe), were synthesized. Fourier transform infrared (FT-IR) spectral analysis was performed on the three materials: MIL-101(Fe), H:MIL-101(Fe), and H:NH2-MIL-101(Fe) (see [link to FT-IR]). Figure 3 (b) in the middle). Located at 3430cm. -1 The broad absorption band functional groups in the vicinity are attributed to the OH vibrations of surface-adsorbed water. After heat treatment, the vibrations in the materials H:MIL-101(Fe) and H:NH2-MIL-101(Fe) are significantly reduced. (1389 and 1600 cm⁻¹) -1 The peaks at the specified locations correspond to the symmetric and asymmetric vibrations of the carboxyl linker, indicating that the organic linker has been successfully coordinated into the MOF structure and still exhibits weak vibrations after conversion into derivatives (see [link]). Figure 3 (b) of the text. 745cm -1 The peak at that point is the CH stretching vibration of the aromatic ring (see [reference]). Figure 3 In (b) of the study, the strength of derivative H:MIL-101(Fe) is significantly higher than that of H:NH2-MIL-101(Fe).

[0077] The zeta potentials (ζ potentials) of the three materials measured showed a similar pattern, with ζ potentials greater than 0 in the pH ≤ 3.0 range (see [reference]). Figure 4). This is beneficial for electrostatic adsorption because the PFAS has a low dissociation constant, which makes the solution acidified. Nitrogen adsorption-desorption curves show that MIL-101(Fe) is a type I microporous Langmuir monolayer reversible adsorption, which is consistent with the pore size distribution (see Figure 5 ). Both H:MIL-101(Fe) and H:NH2-MIL-101(Fe) exhibit type IV desorption hysteresis with multilayer adsorption (see Figure 6 , Figure 7 ), but the pore size of H:MIL-101(Fe) is mainly concentrated in the mesopore of about 4 nm, with a specific surface area of 273.6 m 2 g -1 . H:NH2-MIL-101(Fe) is mainly microporous, with a specific surface area of 124.0 m 2 g -1 . Overall, the above characterization jointly indicates the successful preparation of the magnetic iron-carbon derivative H:MIL-101(Fe) with high hydrophobicity, two-dimensional-three-dimensional close interface. And the single or multiple differences in structure, surface properties and morphology of the constructed Fe-MOF and its derivative materials determine their different adsorption performance for PFAS.

[0078] 2. Rapid adsorption of H:MIL-101(Fe) material on PFASs and reuse

[0079] Figure 8 shows the curve of H:MIL-101(Fe) for cyclic adsorption of 1 mg L -1 PFOA; Figure 9 shows a schematic diagram of rapid separation and recovery of H:MIL-101(Fe) material. Figures 10-13 are structure characterization diagrams of H:MIL-101(Fe) after adsorption and desorption of PFOA, respectively; wherein, Figure 10 is an XDR spectrum; Figure 11 is an XPS full scan spectrum; Figure 12 is a Fourier transform infrared spectrum; Figure 13 is an SEM / EDS spectrum of H:MIL-101(Fe) material after completing adsorption and desorption of PFOA, wherein (f1), (f2) and (f3) are the distribution and content of C, O and Fe elements, respectively.

[0080] H:MIL-101(Fe) still maintains more than 90% removal rate within 30 minutes for the fourth cycle adsorption of 1 mg L -1 PFOA, and the removal can be almost completed within 4 hours (see Figure 8 ). H:MIL-101(Fe) material is also completely separated by magnetic separation within 30 seconds (see Figure 9). The structural stability and elution regeneration performance of H:MIL-101(Fe) during the recycling process were demonstrated by XRD, XPS, and FTIR characterizations (see Figures 10-12 ). The XRD results showed that the number and intensity of the diffraction peaks of the material did not change after adsorbing and desorbing PFOA (see Figure 10 ), indicating that the structural performance of H:MIL-101(Fe) remained stable during the recycling process. Compared with the initial structure of H:MIL-101(Fe), some of the elemental Fe was transformed into FeO (see Figure 3 (a) and (b) in FIG. 13, Figure 10 , respectively, the figure before adsorption and the figure after adsorption). The FTIR spectra also showed that the structures of C-O, C-H, and Fe-OH were stable during the adsorption and regeneration processes of H:MIL-101(Fe) (see Figure 12 ). Only the adsorbed water represented by O-H at a wave number of 3430 gradually decreased during the dry cycle regeneration process. Figure 13 showed that no F element was detected after H:MIL-101(Fe) completed PFOA adsorption and elution, indicating that the material was easy to recycle and reuse. In summary, H:MIL-101(Fe) exhibited excellent performance, including cyclic adsorption of PFOA, structural stability, and easy recycling. Therefore, the present disclosure prepared a highly hydrophobic 3D / 2D interface magnetic material, which can be used for rapid purification of PFAS-contaminated water and further ensures the safety of drinking water.

[0081] 3. Mechanism of efficient adsorption of H:MIL-101(Fe) material on PFASs

[0082] Figure 14 shows the surface hydrophobicity of Fe-MOF and its derivative materials, wherein (a) shows the contact angle of MIL-101(Fe); (b) shows the contact angle of H:NH2-MIL-101(Fe); (c) shows the contact angle of H:MIL-101(Fe). Figure 15 (d) and (e) in FIG. 13 show the oxygen vacancy signals measured by EPR (electron paramagnetic resonance). Figure 16 shows the surface potential distribution of the non-deprotonated PFOA at pH = 3 using the Fukui function. Figure 17 is the XPS C 1s spectrum of MIL-101(Fe), H:MIL-101(Fe), and H:NH2-MIL-101(Fe).

[0083] H:MIL-101(Fe) exhibits excellent adsorption performance for PFAS, mainly due to the contact angle of its hydrophobic surface being 144.0° (see Figure 14(c) in FIG. 6, which is significantly higher than the contact angles of MIL-101 and H:NH2-MIL-101(Fe), which are about 48.0° and 64.0°, respectively (see FIG. 6). Figure 14 (a), (b)) in FIG. 6. The adsorption of PFOA on the three materials is proportional to their hydrophobicity, i.e., H:MIL-101(Fe) = 99.9% > H:NH2-MIL-101(Fe) = 89.1% > MIL-101(Fe) = 22.5%. The fundamental reason for the high hydrophobic surface of H:MIL-101(Fe) is not only attributed to the carbonization of some MOF structures during the heat treatment process, but also attributed to the formation of a large number of unsaturated C-H bonds on the benzene ring at 3060 cm -1

[0084] In addition, MIL-101(Fe) and H:NH2-MIL-101(Fe) with hydrophilic surfaces also exhibit adsorption capacity for PFOA. The contact angle of H:NH2-MIL-101(Fe) increases by 16.0° compared with MIL-101(Fe), but the adsorption percentage of PFOA increases by 26.6%, indicating the existence of other adsorption mechanisms. Heat treatment of materials in an inert atmosphere usually produces positively charged oxygen vacancies. EPR characterization results show that H:NH2-MIL-101(Fe) contains obvious oxygen vacancy signals and is stronger than H:MIL-101(Fe). The surface potential of the PFOA molecule is calculated using the Fukui function, and the head O atom far from the H atom end experiences significant negative charge accumulation (see FIG. 6 Figure 16 ), leading to the anchoring of PFOA molecules on oxygen vacancies through electrostatic interactions. This indicates that electrostatic attraction helps H:NH2-MIL-101(Fe) and H:MIL-101(Fe) to adsorb PFOA (see FIG. 6 Figure 15 (d) and (e)) in FIG. 6. XPS C 1s spectra show that both MIL-101(Fe) and H:MIL-101(Fe) enhance the adsorption of PFOA through π-π interactions (see FIG. 6 Figure 17 ).

[0085] Therefore, H:MIL-101(Fe) can quickly remove PFAS, which benefits from the synergistic adsorption mechanism dominated by hydrophobic interactions, including oxygen vacancies, π-π bonds, and micropores.

[0086] 4. CTAB enhances the co-removal of H:MIL-101(Fe) material on PFASs in surface water

[0087] When the content of the six PFAS in the actual surface water is 1 mg / L, it is found that there is significant competitive adsorption (see FIG. 6 Figure 18 ). That is, the removal effect of PFOA with the longest carbon chain is the best, and the adsorption of short-chain PFBA and PFPeA is limited. Figure 19 ​It was found that the removal of PFASs was significantly improved when the adsorption of PFASs was carried out in ultrapure water, and the adsorption of PFASs with longer carbon chains was also better.

[0088] When CTAB was used in combination with PFBA, the removal of PFBA by H:MIL-101(Fe) increased from 21.2% to 82.4%. CTAB enhanced the co-adsorption of long-chain and short-chain PFASs on H:MIL-101(Fe) in surface water, and the strong hydrophobic effect overcame the electrostatic repulsion caused by the increase of pH (see Figure 20 ). Accordingly, the adsorption of six mixed PFASs was significantly enhanced after adding CTAB to H:MIL-101(Fe) (see Figure 21 ), and almost completely removed 1 mg L -1 of PFOA (C8), PFHpA (C7) and GenX (C6) within 30 minutes, and the removal rate of PFPeA (C5) was more than 90%. After increasing the amount of CTAB added to enhance the complexation with PFASs, it was found that the adsorption performance of the six PFASs was significantly improved, however, due to the limitation of adsorption sites, PFPeA (C5) and PFBA (C4) could not be completely removed (see Figure 22 ). It is worth noting that excessive CTAB will occupy some adsorption sites, and the optimal adsorption removal of PFASs cannot be achieved. Therefore, the loading of H:MIL-101(Fe) was increased from 0.3 g L -1 to 0.5 g L -1 , and the initial concentration of PFASs was reduced to ensure sufficient adsorption sites, and it was found that 6 PFASs were completely removed within 10 minutes at the natural pH of surface water (see Figure 23 ).

[0089] The effect of CTAB on the hydrophobic properties of H:MIL-101(Fe) was further studied. It was found that the surface contact angle of H:MIL-101(Fe) did not change significantly after adsorption and desorption of PFASs (see Figure 24 , Figure 25 ), indicating that CTAB enhanced the adsorption of PFASs by H:MIL-101(Fe) without affecting its recycling performance. This indicates that the use of cationic chelating agent CTAB to form head electrostatic interaction and hydrophobic tail with PFASs is a successful strategy to improve the hydrophobicity of the material surface to improve its adsorption of PFASs in natural water (see Figure 26 ).

[0090] Finally, it is to be understood that the term "including", "comprising", "having" and variations thereof herein are intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof to the extent that they permit. It is not intended to exclude, by definition for example, structural elements that do not substantially affect the essential characteristics of the composition, method, structure, article, or device, but producing composites structurally similar to those being described.

[0091] While the application has been disclosed by reference to the specific embodiments thereof, it should be understood that various other adaptations and / or modifications can be made within the spirit and / or scope of the application. Therefore, it is not intended that the application be limited to the specific embodiments, which are given by way of example. Rather, it is the following claims including any amendments thereto, together with the full scope of equivalents, which should be accorded to them, that are intended to define the breadth of the application.

Claims

1. A method for preparing an iron-carbon derivative material for adsorptive remediation of PFASs contamination in water bodies, characterized in that, Comprising: Step one, dissolve ferric salt in N,N-dimethylformamide, add ligand terephthalic acid under stirring condition, synthesize precursor by solvothermal method; in the solvothermal method, the reaction temperature is 140-160℃, and the reaction time is 10-14 h; the molar ratio of ferric salt:terephthalic acid is 1:1; Step two, the iron-carbon derivative material is obtained after the precursor is heat treated in an inert atmosphere, the heat treatment includes first heating to 280-320℃, then constant temperature anaerobic burning for 2-4 h, and then continue to heat to 400-500 ℃, constant temperature anaerobic burning for 4-12 h.

2. The production method according to claim 1, characterized by, Also comprising: Before the heat treatment, the precursor precipitate is washed with N,N-dimethylformamide and anhydrous ethanol alternately for two times each, and then it is transferred into methanol for purification treatment.

3. The production method according to claim 2, characterized by, The washing includes: centrifuging the precursor suspension generated by the solvothermal method in step one to remove the supernatant, adding an appropriate amount of N,N-dimethylformamide or anhydrous ethanol washing solution, and shaking on a shaker at 2500 r / min for 30 min.

4. The production method according to claim 3, characterized by, The purification treatment includes: soaking the precursor precipitate in methanol for 12 hours.

5. The production method according to any one of claims 2 to 4, characterized by, After the purification treatment, the precursor is separated, dried, and ground to obtain the precursor.

6. The production method according to claim 5, wherein The separation treatment is centrifugal treatment, and the drying treatment is vacuum drying treatment.

7. The preparation method according to claim 1, characterized in that, In step one, the ferric salt is selected from at least one of ferric chloride, ferric nitrate, and ferric sulfate.

8. The method of claim 1, wherein, In step one, the molar ratio of N,N-dimethylformamide:ferric salt:terephthalic acid is 50-300:1:

1.

9. The production method according to any one of claims 1 to 4, 6 to 8, characterized by, In step one, after the ferric salt and terephthalic acid are added to N,N-dimethylformamide, they are stirred at a constant speed of 500-1000 r / min for 10-60 min to completely dissolve and uniformly mix, and then the precursor is synthesized by the solvothermal method.

10. The method of claim 9, wherein, In step one, the stirring speed is 800 r / min, and the stirring time is 60 min.

11. The production method according to any one of claims 1 to 4, 6 to 8, 10, characterized by, In step one, in the solvothermal method, the reaction temperature is 150℃, and the reaction time is 12 h.

12. The production method according to any one of claims 1 to 4, 6 to 8, 10, characterized by, In step two, the heating rate is 4-10℃ / min.

13. The method of claim 12, wherein, In step two, the inert atmosphere refers to a nitrogen atmosphere or an inert gas atmosphere.

14. The method of any one of claims 1-4, 6-8, 10, wherein, In step two, the heat treatment includes: grinding the precursor into powder, then putting it into a corundum boat, and then introducing nitrogen or inert gas into the tube furnace, and then increasing the temperature to 300℃ at a heating rate of 5±1 ℃ / min, and then constant temperature anaerobic burning for 3 h; then continue to heat to 500℃ and keep for 5 h, and then collect the product after natural cooling.

15. An iron-carbon derivative material for adsorptive remediation of PFAS contamination of water bodies, characterized in that, Prepared by the method of any one of claims 1-14.

16. The use of an iron-carbon derivative material for environmental remediation, characterized in that, Comprising: Using the iron-carbon derivative material of claim 15 as an adsorbent, and assisting with a cation complexing agent, PFAS contaminated water is subjected to adsorption purification treatment; the cation complexing agent is selected from at least one of CTAB, dodecyl dimethyl amine oxide, cation panthenol, and octadecyl trimethyl ammonium chloride.

17. Use of the iron-carbon derivative material according to claim 16 for environmental remediation, characterized in that, The PFAS is selected from at least one of PFOA, PFHpA, PFHxA, GenX, PFPeA, and PFBA.

18. Use of the iron-carbon derivative material according to claim 16 for environmental remediation, characterized in that, The concentration of the PFAS in the PFAS contaminated water body is 0.1-6 mg / L.

19. Use of the iron-carbon derivative material according to any one of claims 16-18 for environmental remediation, characterized in that, CTAB is used as a complexing agent, the amount of CTAB is 10-25 mg / L, the amount of the adsorbent is 0.1-0.5 g / L, and the treatment time is within 8 hours.

20. Use of the iron-carbon derivative material according to claim 19 for environmental remediation, characterized by the fact that, The treatment time is within 30 minutes.

21. Use of the iron-carbon derivative material according to claim 20 for environmental remediation, characterized in that, The treatment time is within 10 minutes.

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