Preparation method and application of MXene / Zr-Fe-C composite adsorption material

Abstract

The invention relates to the technical field of composite materials and harmful pollutant removal, in particular to a preparation method and application of an MXene / Zr-Fe-C composite adsorption material, the MXene / Zr-Fe-C composite adsorption material is obtained by optimizing a composite process of MXene and MOFs derived carbon and utilizing electrostatic interaction; comprising the following steps: step 1, preparing MXene; step 2, preparation of Zr / Fe-MOF (at) C; and step 3, MXene / Zr-Fe-C is synthesized by immobilizing the MOFs with the MXene. According to the MXene / Zr-Fe-C prepared by the preparation method disclosed by the invention, the maximum adsorption capacities of the MXene / Zr-Fe-C on DIC and IND respectively reach 277.7 mg / g and 238.09 mg / g by virtue of a high specific surface area, a multi-stage pore structure and a bimetallic synergistic effect, the MXene / Zr-Fe-C is obviously superior to that of monometal MOFs and a traditional adsorbent, and efficient synergistic removal of DIC and IND is realized by virtue of spatial separation of heterogeneous adsorption domains. In addition, after the material is recycled for 40 times, the adsorption capacity retention rate still exceeds 80%, and the recoverability and stability of the material in practical application are highlighted.

Description

Technical Field

[0001] The present invention relates to the technical fields of composite materials and removal of harmful pollutants, and particularly relates to a preparation method and application of an MXene / Zr-Fe@C composite adsorbent material. Background Art

[0002] Non-steroidal anti-inflammatory drugs (NSAIDs) are a class of drugs widely used for relieving pain, anti-inflammatory and antipyretic effects. However, due to their widespread presence in the environment and bioaccumulation effects, NSAIDs have become recognized emerging pollutants globally. The residues of NSAIDs in environmental media may cause serious impacts on the ecosystem and human health, resulting in toxic effects on aquatic organisms, endocrine disruption and potential genotoxicity. Diclofenac (DIC) and indomethacin (IND) are common representative drugs of NSAIDs. DIC is widely used for treating inflammation and pain, but due to its high stability and low biodegradability, it is difficult to remove in the water environment and may have teratogenic, toxic and physiological interference effects on fish and aquatic organisms. IND also has significant anti-inflammatory and analgesic effects, but its metabolites have potential environmental toxicity.

[0003] Traditional removal methods include biodegradation, photocatalytic degradation and membrane separation, etc. However, these methods have certain limitations in practical applications, such as low removal efficiency, high cost, complex operation or generation of secondary pollution, etc. Chemical oxidation methods such as Fenton method and ozonation method are more efficient, but may produce harmful by-products. Biodegradation is limited by the chemical stability and bioavailability of the drugs. In recent years, the adsorption method has gradually become a research hotspot due to its advantages such as simple operation, low cost and no secondary pollution, etc., but the adsorption capacity and selectivity of traditional adsorbent materials are often insufficient. Developing efficient, stable and renewable adsorbent materials is the key to the successful application of the adsorption method. Therefore, constructing adsorbent materials and removal methods for highly efficient removal of non-steroidal drugs in water bodies is of great significance to the ecosystem and public health. Summary of the Invention

[0004] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to propose a preparation method and application of an MXene / Zr-Fe@C composite adsorbent material. By optimizing the composite process of MXene and MOFs-derived carbon, the prepared MXene / Zr-Fe@C exhibits ultra-high adsorption capacity, excellent reusability and long-term stability during the removal process of DIC and IND, and has strong anti-interference ability.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A preparation method of an MXene / Zr-Fe@C composite adsorbent material, by optimizing the composite process of MXene and MOF-derived carbon, and obtaining the MXene / Zr-Fe@C composite adsorbent material by using electrostatic interaction; the method includes the following steps:

[0007] Step 1, Preparation of MXene:

[0008] Dissolve 1 g of lithium fluoride in 10 mL of 12 mol / L concentrated hydrochloric acid, and perform magnetic stirring for 30 min to fully dissolve it; then, while continuously stirring, slowly add 1 g of titanium aluminum carbide powder to the solution to ensure uniform dispersion; place the reaction system in a 35°C water bath and continuously stir for 24 h to promote full reaction; after the reaction is completed, repeatedly wash the obtained powder with deionized water until the pH of the washing solution is about 7 to remove residual acidic substances; then, centrifuge and wash the powder three times with ethanol to further remove impurities; finally, place the obtained powder in a 60°C vacuum oven and dry it overnight to obtain dry Ti3C2T x powder;

[0009] Step 2, Preparation of Zr / Fe-MOF@C:

[0010] First, add 233.04 mg of 1 mmol ZrCl4, 540.58 mg of 2 mmol FeCl3·6H2O, and 332.26 mg of 2 mmol H2BTC to 60 mL of DMF solution, and ultrasonically dissolve for 10 min until completely dissolved; then transfer the homogeneous mixture to a stainless steel autoclave lined with polytetrafluoroethylene and react at 120°C for 24 h; after the reaction is completed, cool to room temperature, collect the solid powder by centrifugation for 5 min, and wash it three times with DMF, ethanol, and pure deionized water respectively; finally, dry it in a vacuum drying oven at 80°C for 8 h to obtain Zr / Fe-MOF; transfer the powder of Zr / Fe-MOF to a ceramic boat, then heat it to 800°C at a rate of 5°C / min, and keep it for 2 h under a nitrogen flow in a tube furnace, and the obtained product is respectively designated as Zr / Fe-MOF@C;

[0011] Step 3, Immobilization of MXene on MOFs to synthesize MXene / Zr-Fe@C:

[0012] 150 mg of MXene and 100 mg of Ze / Fe-MOF@C were separately dispersed in 10 mL of deionized water to form uniform suspensions. Subsequently, the two suspensions were mixed and oscillated at a speed of 250 rpm / min at room temperature for 2 h to ensure that the two materials were in full contact and a uniform composite material was formed. After the reaction, the magnetic composite material was adsorbed to the bottom of the container using an external magnet, and the supernatant was carefully poured out to remove unbound impurities. Subsequently, the composite material was washed multiple times with deionized water or ethanol to further remove residual impurities until the washing solution was clear and free of residual impurities. The finally obtained magnetic Zr / Fe-MOF@C-MXene composite material was named MXene / Zr-Fe@C.

[0013] The present invention also provides an application of the MXene / Zr-Fe@C composite adsorbent material obtained by the above preparation method in adsorbing and removing diclofenac and indomethacin in water. Based on the magnetic separation characteristics of Zr / Fe-MOF@C and the multi-mechanism synergistic effect of MXene / Zr-Fe@C, efficient adsorption and synergistic removal of diclofenac and indomethacin in water by the MXene / Zr-Fe@C composite material are achieved.

[0014] Preferably, it includes the following steps:

[0015] 15 mg of MXene / Zr-Fe@C was dissolved in 20 mL of NSAIDs solution, and experiments were carried out under different initial concentrations (10 - 450 mg / L), contact times (0.5 - 40 min), temperatures (298.15 K - 318.15 K) or pH values (3 - 10) conditions. Then, it was uniformly oscillated during a series of contact times. After reaching the adsorption equilibrium, MXene / Zr-Fe@C was separated from the NSAIDs solution using a magnet. A certain amount of supernatant was taken out with a syringe and filtered through a 0.22 μm filter membrane. The residual NSAIDs concentration in the supernatant was monitored by an ultraviolet-visible spectrophotometer at the maximum absorption wavelengths of 276 and 320 nm.

[0016] Among them, in the binary adsorption system, the adsorption behavior of a DIC and IND mixture in the concentration range of 10 + 10 to 450 + 450 mg / L was studied. A fixed dose of 25 mg of the MXene / Zr-Fe@C composite material was used in the experiment to simultaneously remove DIC and IND in the binary mixture. The experiment was carried out based on the optimal conditions determined by the previous single-component adsorption study to evaluate the removal performance of DIC and IND in the mixed system.

[0017] By adopting the above technical solutions: Here, the magnetic separation characteristics of Zr / Fe-MOF@C and the multi-mechanism synergistic effect of MXene / Zr-Fe@C are utilized to provide a new idea for the efficient removal of pharmaceutical pollutants in water bodies, and also provide a theoretical basis and technical support for the development and application of MXene and MOFs-derived carbon composite materials. MXene / Zr-Fe@C, with its high specific surface area, hierarchical pore structure, and bimetallic synergistic effect, has the maximum adsorption capacities for DIC and IND reaching 277.7 mg / g and 238.09 mg / g respectively, significantly superior to single-metal MOFs and traditional adsorbents, and realizes the efficient co-removal of DIC and IND through the spatial separation of heterogeneous adsorption domains. In addition, after 40 cycles of use, the adsorption capacity retention rate of this material still exceeds 80%, highlighting its recyclability and stability in practical applications. The present invention provides a new strategy for the remediation of water bodies polluted by non-steroidal drugs, expands the co-removal application of multi-pollutant coexistence systems, and provides a solid theoretical and technical foundation for the development of efficient and economical adsorbents, having important scientific significance and practical application value.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. MXene / Zr-Fe@C prepared by the present invention, with its high specific surface area, hierarchical pore structure, and bimetallic synergistic effect, exhibits ultra-high adsorption capacity, excellent reusability and long-term stability during the removal process of DIC and IND, and has strong anti-interference ability.

[0020] 2. By using the hierarchical design of MXene / Zr-Fe@C, the Zr / Fe@C layer provides coordination adsorption sites for DIC with stronger ionic properties. At the same time, MXene and the carbon matrix promote the non-polar interaction of aromatic IND. In the multi-component system, the structural independence of heterogeneous adsorption domains and the spatial separation of adsorption pathways reduce direct competition, and may even produce a synergistic effect through surface modification, realizing the efficient co-removal of DIC and IND, and effectively solving the problems of limited adsorption capacity and insufficient cycle stability of single MOFs materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 SEM images of MXene (a), Zr-Fe@C (b), and MXene / Zr-Fe@C (c-d) in the present invention;

[0022] Figure 2 XRD pattern (a), FT-IR spectrum (b), zeta potential diagram (c), and VSM diagram (d) of MXene / Zr-Fe@C in the present invention;

[0023] Figure 3 This is the XPS spectrum of MXene / Zr-Fe@C in the present invention; (a) Total spectrum; (b) Fe 2p spectrum; (c) Ti 2p spectrum; (d) O 1s spectrum; (e) C 1s spectrum; (f) Raman spectrum;

[0024] Figure 4 This is the adsorption isotherm fitting curve of NSAIDs on MXene / Zr-Fe@C in the present invention: (a) Langmuir model; (b) Freundlich model; (c) Temkin model; (d) D-R model;

[0025] Figure 5 This is the kinetic model fitting curve of the adsorption of NSAIDs by MXene / Zr-Fe@C in the present invention: (a) Pseudo-first-order model; (b) Pseudo-second-order model; (c) Elovich model; (d) Liquid film diffusion model. Detailed implementation manners

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, and thus make a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] Example 1: Preparation of MXene / Zr-Fe@C composite adsorbent material

[0028] A preparation method of a MXene / Zr-Fe@C composite adsorbent material includes the following steps:

[0029] Step 1: Preparation of MXene:

[0030] Dissolve 1 g of lithium fluoride in 10 mL of concentrated hydrochloric acid (12 mol / L), and perform magnetic stirring for 30 min to fully dissolve it. Subsequently, under continuous stirring, slowly add 1 g of aluminum titanium carbide powder to the solution to ensure uniform dispersion. Place the reaction system in a 35 °C water bath and continuously stir for 24 h to promote the full progress of the reaction. After the reaction is completed, repeatedly wash the obtained powder with deionized water until the pH of the washing solution is about 7 to remove residual acidic substances. Subsequently, centrifuge and wash the powder three times with ethanol to further remove impurities. Finally, place the obtained powder in a 60 °C vacuum oven and dry it overnight to obtain dry Ti3C2T x powder.

[0031] Step 2: Preparation of Zr / Fe-MOF@C:

[0032] First, ZrCl4 (233.04 mg, 1 mmol), FeCl3·6H2O (540.58 mg, 2 mmol), and H2BTC (332.26 mg, 2 mmol) were added to 60 mL of DMF solution and sonicated for 10 min until completely dissolved. Then the homogeneous mixture was transferred to a stainless-steel autoclave lined with polytetrafluoroethylene and reacted at 120 °C for 24 h. After the reaction was completed, it was cooled to room temperature, and the solid powder was collected by centrifugation for 5 min and washed three times with DMF, ethanol, and pure deionized water respectively. Finally, it was dried in a vacuum drying oven at 80 °C for 8 h to obtain Zr / Fe-MOF. The powder of Zr / Fe-MOF was transferred to a ceramic boat, then heated to 800 °C at a rate of 5 °C / min and held for 2 h in a tube furnace under a N2 flow. The obtained product was denoted as Zr / Fe-MOF@C.

[0033] Step 3: Synthesis of MXene-immobilized MOFs MXene / Zr-Fe@C:

[0034] 150 mg of MXene and 100 mg of Ze / Fe-MOF@C were respectively dispersed in 10 mL of deionized water to form homogeneous suspensions. Subsequently, the two suspensions were mixed and oscillated at a speed of 250 rpm / min at room temperature for 2 h to ensure sufficient contact between the two materials and form a homogeneous composite material. After the reaction was completed, the magnetic composite material was adsorbed to the bottom of the container using an external magnet, and the supernatant was carefully poured out to remove unbound impurities. Subsequently, the composite material was washed multiple times with deionized water or ethanol to further remove residual impurities until the washing liquid was clear and free of impurities. The finally obtained magnetic Zr / Fe-MOF@C-MXene composite material was named MXene / Zr-Fe@C.

[0035] Among them, the SEM images of MXene (a), Zr-Fe@C (b), and MXene / Zr-Fe@C (c-d) are as Figure 1 shown: The morphology of MXene / Zr-Fe@C still presents a two-dimensional rough multi-layer structure similar to an accordion and contains a large number of spherical Zr-Fe@C particles. Compared with MXene, the surface roughness has increased. These particles are encapsulated between the layers of MXene and cover its surface, while retaining the nano-layered morphology of MXene and the porous characteristics of Zr-Fe@C.

[0036] The adsorption principle of the present invention is:

[0037] At pH ≈ 3, the carboxyl group (-COOH) on NSAIDs (pKa ≈ 4.0 - 4.5) is protonated to form a positively charged -COOH + species, while the MXene / Zr-Fe@C surface maintains a pH-independent negative charge. This charge difference induces an electrostatic interaction between the protonated -COOH + group and the negatively charged MXene / Zr-Fe@C surface, significantly improving the adsorption efficiency. The Fe and Zr in MXene / Zr-Fe@C form coordination or chemical bonds with functional groups such as the carboxyl and amino groups of diclofenac and indomethacin. The combination of Fe / Zr bimetallic MOF-derived carbon and MXene introduces additional active sites and functional groups on the metal oxide surface. This synergistic combination enhances the adsorption capacity through multiple mechanisms, including coordination, π-π interaction, hydrogen bonding, and electrostatic interaction. In addition, the hierarchical design of MXene / Zr-Fe@C enables the Zr / Fe@C layer to provide coordination adsorption sites for DIC with stronger ionic properties. Meanwhile, MXene and the carbon matrix promote the non-polar interaction of aromatic IND. In the multi-component system, the structural independence of the heterogeneous adsorption domain and the spatial separation of the adsorption pathways reduce direct competition and may even generate a synergistic effect through surface modification, enhancing the adsorption performance of DIC and IND under the multi-component system.

[0038] Example 2: Adsorption and removal of diclofenac and indomethacin in water by MXene / zirconium iron-derived carbon composite

[0039] Dissolve 15 mg of MXene / Zr-Fe@C in 20 mL of NSAIDs solution and conduct experiments under different initial concentrations (10 - 450 mg / L), contact times (0.5 - 40 min), temperatures (298.15 K - 318.15 K), or pH values (3 - 10). Then, oscillate evenly at a series of contact times. After reaching the adsorption equilibrium, use a magnet to separate MXene / Zr-Fe@C from the NSAIDs solution. Take a certain amount of supernatant with a syringe and filter it through a 0.22 μm filter membrane. The residual NSAIDs concentration in the supernatant is monitored by a UV-visible spectrophotometer at the maximum absorption wavelengths of 276 and 320 nm.

[0040] Four adsorption isotherm models, namely Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich, were adopted to study the interaction between MXene / Zr-Fe@C and adsorbates during the equilibrium adsorption process. The corresponding parameters of the fitting results of all isotherm models for the adsorption of NSAIDs on the surface of MXene / Zr-Fe@C are shown in Table 1. Five common adsorption kinetic models (pseudo-first-order kinetic model, pseudo-second-order kinetic model, Elovich model, liquid film diffusion model, and intraparticle diffusion model) were used, and the relevant parameters of the fitting results are shown in Table 2.

[0041] Table 1

[0042]

[0043]

[0044] Table 2

[0045]

[0046] The fitting coefficients of each isotherm model with the experimental data are all greater than 0.92 (R 2 = 0.9217 - 0.9985), indicating that all four models can effectively describe the adsorption process of MXene / Zr-Fe@C for NSAIDs. Therefore, the adsorption of NSAIDs by MXene / Zr-Fe@C is not a single adsorption mode, but a combination of multiple adsorption behaviors. The results show that the Langmuir model has the highest correlation coefficient, and the R 2 values for DIC and IND are between 0.9972 and 0.9985, which is significantly better than other models, indicating that the Langmuir model is most suitable for fitting the adsorption process. Both the pseudo-first-order kinetic model and the pseudo-second-order kinetic model show good fitting effects, and the R 2 values are all greater than 0.90. The R 2 value of the pseudo-second-order kinetic model is between 0.9990 and 0.9995, which is significantly higher than the R 2 value (0.9519 - 0.9742) of the pseudo-first-order kinetic model. The theoretical adsorption capacities of DIC and IND calculated by the pseudo-second-order kinetic model are 333.33 mg / g and 227.27 mg / g respectively, which are in good agreement with the experimental data. Therefore, the adsorption process of MXene / Zr-Fe@C for NSAIDs follows the pseudo-second-order kinetic model and is mainly chemisorption. The adsorption process may involve the electron sharing and transfer between the adsorbent and the adsorbate through valence bond forces (such as hydrogen bonds, π-π interactions, etc.).

[0047] Example 3: Competitive Adsorption of Diclofenac and Indomethacin in Water by MXene / Zr-Fe@C Composite

[0048] In the binary adsorption system, the adsorption behavior of the DIC and IND mixture in the concentration range of 10 + 10 to 450 + 450 mg / L was studied. A fixed dose of 25 mg of the MXene / Zr-Fe@C composite was used in the experiment to simultaneously remove DIC and IND in the binary mixture. The experiment was carried out based on the optimal conditions determined by the previous single-component adsorption study to evaluate the removal performance of DIC and IND in the mixed system.

[0049] The binary system of DIC and IND was analyzed using the Langmuir competitive adsorption model to study the cooperative and antagonistic adsorption behaviors between the two NSAIDs. Subsequently, the modified Langmuir competitive model for the removal of DIC and IND in the DIC + IND binary system was represented by equations (1 - 3) respectively.

[0050]

[0051] For the binary system containing both DIC and IND, q e,DIC and q e,IND represent the adsorption capacities of DIC and IND at equilibrium, respectively. Similarly, Q m,DIC and Q m,IND correspond to the maximum adsorption capacities of DIC and IND in the mixed solution, respectively. The Langmuir constants of DIC and IND are represented by K L,DIC and K L,IND respectively. In addition, C e,DIC and C e,IND represent the equilibrium concentrations of DIC and IND in the binary system.

[0052] The test results are shown in Table 3:[[]]END]]

[0053] Table 3

[0054]

[0055] The competitive adsorption data show that compared with the single-component system, the binary system of DIC + IND exhibits a cooperative enhancement effect in adsorption capacity, and the adsorption capacities of both drugs are improved. As can be seen from Table 3, by comparing q single and q binary (representing the maximum adsorption capacities of DIC and IND in the single-component system and the binary system respectively), the antagonistic or cooperative characteristics of the DIC + IND mixture were studied. The parameter q binary / q single reveals three different interaction models: when q binary / qsingle When the value is 1, it indicates molecular independence, that is, the adsorption capacity of co-existing compounds (DIC and IND) is not affected by their single-component systems, indicating that the adsorption process proceeds through parallel paths without interfacial interference. When q binary / q single When the value is less than 1, it indicates the existence of a competitive antagonistic effect, that is, the presence of one NSAIDs will significantly reduce the adsorption efficiency of another NSAIDs. On the contrary, when q binary / q single When the value is greater than 1, it indicates the existence of a synergistic effect, that is, co-existing NSAIDs enhance each other's adsorption capacity through complementary intermolecular interactions. Therefore, MXene / Zr-Fe@C of the present invention exhibits synergistic characteristics in the mixed competitive adsorption system of DIC and IND.

[0056] As Figure 2 (a) shows that the characteristic diffraction peaks of (002) of MXene nanosheets and Zr-Fe@C are at 6.0 - 7.5° and 30.1° respectively, and appear simultaneously in the XRD pattern, indicating the successful synthesis of MXene / Zr-Fe@C composite by adding Zr-Fe@C on the surface of MXene. As Figure 2 (b) shows that the functional groups of MXene, Zr / Fe-MOF@C and MXene / Zr-Fe@C were analyzed by FT-IR spectroscopy. Similar absorption bands were observed near 3440 cm -1 for all samples, corresponding to the stretching vibration of -OH. The peaks at 560 cm -1 and 620 cm -1 observed in MXene / Zr-Fe@C were attributed to the Ti-C bond and Ti-O bond of MXene / Zr-Fe@C respectively. In addition, the small peak at 593 cm -1 in MXene / Zr-Fe@C corresponded to the Fe-O bond, which did not exist in MXene, confirming the existence of Zr-Fe@C on the surface of MXene. The surface charge densities of two materials, Zr-Fe@C and MXene / Zr-Fe@C, were analyzed by Zeta potential. As Figure 2 (c) shows that under acidic conditions, the higher Zeta potential value of Zr-Fe@C indicates that a large number of positive charges are distributed on its surface, while MXene / Zr-Fe@C is completely occupied by negative charges in the pH range of 2 to 11. According to the acidity coefficients of the two adsorbates (PK of DIC and IND aRespectively 4 and 4.5), both adsorbates carry positive charges in the range of 2.0 < pH < 4.0. Therefore, the negative charge characteristics exhibited by MXene / Zr-Fe@C in this pH range will facilitate its adsorption with the two NSAIDs through electrostatic attraction. The magnetism of the nanocomposite was analyzed by VSM. The saturation magnetization intensities of Zr-Fe@C and MXene / Zr-Fe@C are 10.48 and 13.65 emu / g, respectively. In addition, Figure 2 The hysteresis regression line shown in (d) also indicates that, compared with Zr-Fe@C, the magnetism of MXene / Zr-Fe@C has decreased, which can be attributed to the reduced proportion of strongly magnetic Zr-Fe@C in the MXene / Zr-Fe@C composite.

[0057] The valence states and elemental compositions of the materials were studied by XPS. Figure 3 The full spectrum in (a) shows the presence of Zr, Fe, Ti, C, and O elements in MXene / Zr-Fe@C, confirming the successful doping of Zr-Fe@C into MXene, which is consistent with the SEM and XRD results. The four main peaks in the Fe 2p spectrum are located at 707.68, 710.38, 720.18, and 724.78 eV, corresponding to Fe 0 2p3 / 2, Fe 3+ 2p3 / 2, Fe 0 2p1 / 2 and Fe 3+ 2p1 / 2, indicating that Fe in MXene / Zr-Fe@C exists in the forms of Fe and Fe3C ( Figure 3 (b)). In the Ti 2p XPS spectrum of MXene / Zr-Fe@C ( Figure 3 (c)), the two peaks located at 463.88 eV (Ti 2p1 / 2) and 458.18 eV (Ti2p3 / 2) are attributed to Ti-C and Ti-O bonds. From the O 1s and C1s XPS spectra ( Figure 3 .(d, e)), it can be seen that compared with the peaks of Zr-Fe@C (284.45 eV and 529.56 eV), the peaks located at 283.98 eV and 529.28 eV (C-Ti-O) show an obvious shift, indicating the existence of a chemical bond between MXene and Zr-Fe@C. Figure 3 The Raman spectrum of Zr-Fe@C shown in (f) shows two peaks near 1350 and 1600 cm -1 which correspond to the D band and the G band, representing disordered carbon and ordered graphite carbon, respectively. However, the spectrum of MXene / Zr-Fe@C only shows an obvious G band, while the peak intensity of the D band is significantly reduced. Compared with Zr-Fe@C, the peak intensity ratio of the D band to the G band (ID / I G ) was significantly reduced, indicating that the presence of MXene layers improved the order of Zr-Fe@C.

[0058] Figure 4 The fitting results of all isotherm models for the adsorption of NSAIDs on the MXene / Zr-Fe@C surface are shown. The results indicate that the Langmuir model has the best fit and the highest correlation coefficient, significantly superior to other models, suggesting that the Langmuir model is most suitable for fitting the adsorption process. Therefore, NSAIDs are uniformly distributed on the MXene / Zr-Fe@C surface, and monolayer adsorption is the main adsorption mechanism. The Freundlich isotherm model also shows good fitting effects for the adsorption data of DIC and IND, with R 2 values of 0.9217 and 0.9885 respectively, indicating that there may be both monolayer and multilayer adsorption modes for the adsorption of NSAIDs by MXene / Zr-Fe@C. The "n" values of DIC and IND in the Freundlich model are both greater than 1, indicating that these two NSAIDs are more easily adsorbed by MXene / Zr-Fe@C. The R 2 values of the Dubinin-Radushkevich and Temkin models are both higher than 0.93 and close to 1. Therefore, these two isotherm models can also well describe the adsorption process. The average free energies (E values, in kJ / mol) of DIC and IND calculated by the Dubinin-Radushkevich model are 70.71 and 50 respectively, both greater than 8.0 kJ / mol, indicating that chemisorption is the main mechanism controlling the adsorption process. In addition, the b T values (R 2 = 0.9394 - 0.9866) of the Temkin model are 51.86 J / mol for DIC and 70 J / mol for IND respectively, both greater than 20 J / mol, which further confirms that chemisorption is involved in the adsorption process. The fitting coefficients of each isotherm model with the experimental data are all greater than 0.92, indicating that these four models can all effectively describe the adsorption process of MXene / Zr-Fe@C for NSAIDs, confirming that the adsorption of NSAIDs by MXene / Zr-Fe@C is not a completely single adsorption mode, but a combination of multiple adsorption behaviors.

[0059] Figure 5 The fitting results of the pseudo-first-order kinetic model, pseudo-second-order kinetic model, Elovich model, and liquid film diffusion model in the adsorption kinetic model are shown. The pseudo-first-order kinetic model ( Figure 5 (a)) and the pseudo-second-order kinetic model ( Figure 5 (b)) both show good fitting effects, with R 2The values are all greater than 0.90. However, the R value of the pseudo-second-order kinetic model 2 is between 0.9990 and 0.9995, which is significantly higher than the R value of the pseudo-first-order kinetic model 2 (0.9519 - 0.9742). In addition, the theoretical adsorption capacities of DIC and IND calculated by the pseudo-second-order kinetic model are 333.33 mg / g and 227.27 mg / g respectively, which are in good agreement with the experimental data. Therefore, the adsorption process of NSAIDs by MXene / Zr-Fe@C follows the pseudo-second-order kinetic model and is mainly chemical adsorption. The adsorption process may involve electron sharing and transfer between the adsorbent and the adsorbate through valence bond forces (such as hydrogen bonds, π-π interactions, etc.). The Elovich model describes the heterogeneous chemical adsorption process occurring at the liquid-solid interface, which is characterized by a relatively fast adsorption rate in the initial stage and a gradually decreasing reaction rate in the subsequent stage. It should be noted that the Elovich model( Figure 5 (c), R 2 > 0.9951) is also very suitable for describing the adsorption behavior of NSAIDs, further supporting the dominant position of chemical adsorption on the heterogeneous surface of the adsorbent. The α value (28.57 - 79.91 mg / g / min) of the Elovich model is significantly higher than the β value (0.013 - 0.035 g / mg), further confirming that the adsorption intensity is greater than the desorption. The fitting results of the liquid film diffusion model( Figure 5 (d)) indicate that liquid film diffusion is the main mechanism in the initial stage of adsorption. In addition, the intraparticle diffusion kinetic model finally confirms that intraparticle diffusion is the main rate-controlling mechanism in the adsorption kinetics in the later stage.

[0060] In summary, the MXene / Zr-Fe@C prepared in the present invention exhibits ultra-high adsorption capacity, excellent reusability and long-term stability in the removal of diclofenac and indomethacin, and has strong anti-interference ability. Through the synergistic effect of bimetals, functionalized composite and high-temperature carbonization derivation strategies, combined with the spatial separation of heterogeneous adsorption domains, the efficient synergistic removal of diclofenac and indomethacin is achieved, effectively solving the problems of limited adsorption capacity and insufficient cycle stability of single MOF materials.

[0061] The descriptions and practices disclosed in the present invention are easy to think and understand for those of ordinary skill in the art. Without departing from the principle of the present invention, several improvements and refinements can also be made. Therefore, the modifications or improvements made without departing from the spirit of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A preparation method of an MXene / Zr-Fe@C composite adsorbent material, characterized in that, By optimizing the composite process of MXene and MOF-derived carbon, a MXene / Zr-Fe@C composite adsorbent material is obtained by using electrostatic interaction; the method includes the following steps: Step 1, Preparation of MXene: Dissolve 1 g of lithium fluoride in 10 mL of 12 mol / L concentrated hydrochloric acid, and perform magnetic stirring for 30 min to fully dissolve it; then, under continuous stirring, slowly add 1 g of aluminum titanium carbide powder to the solution to ensure uniform dispersion; place the reaction system in a 35 °C water bath and continuously stir for 24 h to promote the full progress of the reaction; after the reaction is completed, repeatedly wash the obtained powder with deionized water until the pH of the washing solution is 7 to remove residual acidic substances; Subsequently, the powder was centrifugally washed three times with ethanol to further remove impurities; finally, the obtained powder was placed in a vacuum oven at 60 °C and dried overnight to obtain dry Ti3C2T x powder; Step 2, Preparation of Zr / Fe-MOF@C: First, add 233.04 mg of 1 mmol ZrCl4, 540.58 mg of 2 mmol FeCl3·6H2O, and 332.26 mg of 2 mmol H2BTC to 60 mL of DMF solution, and ultrasonicate for 10 min until completely dissolved; then transfer the homogeneous mixture to a stainless steel autoclave lined with polytetrafluoroethylene and react at 120 °C for 24 h; after the reaction is completed, cool to room temperature, collect the solid powder by centrifugation for 5 min, and wash it three times with DMF, ethanol, and pure deionized water respectively; finally, dry it in a vacuum drying oven at 80 °C for 8 h to obtain Zr / Fe-MOF; transfer the powder of Zr / Fe-MOF to a ceramic boat, then heat it to 800 °C at a rate of 5 °C / min and keep it in a tube furnace under a N2 flow for 2 h, and the obtained product is denoted as Zr / Fe-MOF@C; Step 3, Immobilization of MXene on MOFs to synthesize MXene / Zr-Fe@C: Disperse 150 mg of MXene and 100 mg of Ze / Fe-MOF@C in 10 mL of deionized water respectively to form uniform suspensions; then, mix the two suspensions and oscillate and mix them at a speed of 250 rpm / min at room temperature for 2 h to ensure sufficient contact between the two materials and form a uniform composite material; after the reaction is completed, use an external magnet to adsorb the magnetic composite material to the bottom of the container, carefully pour out the supernatant to remove unbound impurities; then, wash the composite material with deionized water or ethanol multiple times to further remove residual impurities until the washing solution is clear and free of residual impurities; finally, the obtained magnetic Zr / Fe-MOF@C-MXene composite material is named MXene / Zr-Fe@C.

2. Use of the MXene / Zr-Fe@C composite adsorbent material obtained by the preparation method described in claim 1 for adsorbing and removing diclofenac and indomethacin in water, characterized in that, Based on the magnetic separation characteristics of Zr / Fe-MOF@C and the multi-mechanism synergistic effect of MXene / Zr-Fe@C, the efficient adsorption and synergistic removal of diclofenac and indomethacin in water by the MXene / Zr-Fe@C composite material are realized.

3. The application according to claim 2, wherein The method includes the following steps: Dissolve 15 mg of MXene / Zr-Fe@C in 20 mL of NSAIDs solution, and conduct experiments under different conditions of initial concentration, contact time, temperature or pH value. Then, oscillate evenly for a series of contact times. After reaching the adsorption equilibrium, separate MXene / Zr-Fe@C from the NSAIDs solution using a magnet; take a certain amount of supernatant with a syringe and filter it through a 0.22 μm filter membrane; monitor the residual NSAIDs concentration in the supernatant at the maximum absorption wavelengths of 276 and 320 nm using an ultraviolet-visible spectrophotometer.

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