ZIF-67-coated Co / HPLFM composite material as well as preparation method and application thereof

Abstract

The invention provides a ZIF-67 (at) Co / HPLFM composite material and a preparation method and application of the ZIF-67 (at) Co / HPLFM composite material, and the preparation method comprises the following steps: providing a hollow porous straw lignin fiber membrane (HPLFM); cobalt salt is dissolved in absolute ethyl alcohol, the hollow porous straw lignin fiber membrane is taken and placed in the mixed solution, absolute ethyl alcohol dissolved with 2-methylimidazole is dropwise added into the mixed solution after oscillation, and oscillation continues for a period of time; taking out the hollow porous straw lignin fiber membrane, washing, and freeze-drying to obtain a precursor material; and carrying out high-temperature calcination on the precursor material to obtain the ZIF-67 (at) Co / HPLFM composite material. The high surface activity and the porous hollow structure of the hollow porous straw lignin fiber membrane are utilized, ZIF-67 is loaded on HPLFM, the ZIF-67-coated Co / HPLFM composite material is obtained through further treatment, and the material has high specific surface area and excellent adsorption performance and has good application prospects in organic pollutant degradation by activating peroxymonosulfate.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a ZIF-67@Co / HPLFM composite material, its preparation method, and its application. Background Technology

[0002] In recent years, with the development of various new materials and drugs, some new organic pollutants have emerged, such as bisphenol A (BPA), carbamazepine (CBZ), norfloxacin (NOR), p-nitrophenol (PNP), and sulfamethoxazole (SMX). These emerging pollutants are gradually permeating various water bodies, posing a serious threat to human health. For example, BPA can cause severe endocrine disorders and even induce birth defects or cancer. Therefore, it is essential to develop effective water purification methods to address these new pollutants. Among the various methods that have been developed, advanced salt oxidation technology based on persulfate (PMS) has received increasing attention due to its high efficiency and wide adaptability.

[0003] ZIF-67, an organometallic framework (MOF) synthesized from divalent cobalt and 2-methylimidazole, exhibits excellent surface activity due to its porous zeolite-like crystal structure, with a stable specific surface area reaching 1000 m². 2 With a surface activity of over 1 g / g and excellent thermal stability, ZIF-67 can withstand high temperatures without losing its surface activity, making it a promising new material. Among various transition metals for activating PMS, cobalt is the most active, and ZIF-67 is a highly surface-active MOF composed of divalent cobalt, which gives it excellent PMS activation performance. However, using powdered ZIF-67 alone to activate PMS often leads to problems such as difficult recovery, cobalt leaching, and insufficient stability.

[0004] Therefore, it is necessary to modify or composite ZIF-67 to improve its performance, and based on this, this application is made. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ZIF-67@Co / HPLFM composite material, its preparation method, and its application. Utilizing the high surface activity and porous hollow structure of hollow lignin fiber membrane (HPLFM), ZIF-67 is loaded onto HPLFM, and further processing yields the ZIF-67@Co / HPLFM composite material. This material possesses a high specific surface area and excellent adsorption performance, showing promising application prospects in the degradation of organic pollutants using activated persulfate.

[0006] This invention provides the following technical solution:

[0007] This invention provides a method for preparing ZIF-67@Co / HPLFM composite material, comprising the following steps:

[0008] Provide porous hollow straw lignin fiber membranes;

[0009] Cobalt salt was dissolved in anhydrous ethanol. Hollow porous straw lignin fiber membrane was placed in the mixed solution and shaken. Anhydrous ethanol containing 2-methylimidazole was added dropwise, and shaking was continued for a period of time. The porous hollow straw lignin fiber membrane was removed, washed, and freeze-dried to obtain the precursor material. The precursor material was calcined at high temperature to obtain the ZIF-67@Co / HPLFM composite material.

[0010] Hollow porous straw lignin fiber membrane (HPLFM) has excellent surface activity and porous structure, which can solve the pain points of ZIF-67 when used alone. It can also increase the effective contact area between ZIF-67 and external systems by means of the special morphology of HPLFM. In addition, since lignin molecules have a lot of active groups, they can provide possible reaction sites for activating PMS.

[0011] This invention uses HPLFM as a template, and loads ZIF-67 onto the surface of HPLFM through in-situ growth. Then, the loaded HPLFM and the ZIF-67 on its surface are further pre-oxidized and calcined through annealing to obtain ZIF-67@Co / HPLFM composite material.

[0012] Further, the preparation process of the hollow porous straw lignin fiber membrane is as follows: polyacrylonitrile is added to N,N-dimethylformamide and stirred in a water bath until completely dissolved. A certain amount of polyvinylpyrrolidone is added and stirred in a water bath until completely dissolved. Then, straw lignin is added to obtain a shell spinning solution. A certain amount of polyvinylpyrrolidone is added to N,N-dimethylformamide and stirred in a water bath to dissolve to obtain a core spinning solution. The shell spinning solution and the core spinning solution are coaxially electrospun to obtain a fiber membrane. The fiber membrane is placed in a high-pressure reactor, deionized water is added to the reactor, and polyvinylpyrrolidone is removed by heating in a drying oven. The fiber membrane is taken out and washed with deionized water until neutral. It is then freeze-dried to obtain a hollow porous lignin fiber membrane.

[0013] The straw lignin is one or more of rice straw lignin, wheat straw lignin, rapeseed straw lignin, or corn straw lignin.

[0014] Furthermore, the mass ratio of straw lignin to polyacrylonitrile is 2:1, the mass ratio of straw lignin to polyvinylpyrrolidone is 1:(0.5-2), and the mass ratio of polyvinylpyrrolidone in the shell spinning solution and the core spinning solution is 1:3.

[0015] Furthermore, the cobalt salt is a divalent Co nitrate and its hydrate, and the amount of cobalt salt used is 0.5–2.0 mmol.

[0016] Furthermore, the molar ratio of 2-methylimidazole to cobalt salt is 8:1.

[0017] Furthermore, the washing process involves: after the oscillation is completed, removing the hollow porous straw lignin fiber membrane and washing it alternately with anhydrous ethanol and deionized water.

[0018] Furthermore, the high-temperature calcination is as follows: the precursor material is placed in a muffle furnace and heated to 250°C in an air atmosphere at a rate of 5°C / min for 3 hours.

[0019] The present invention also provides a ZIF-67@Co / HPLFM composite material prepared by the above preparation method.

[0020] The present invention also provides the application of the above-mentioned ZIF-67@Co / HPLFM composite material in the degradation of organic pollutants by activated persulfate.

[0021] The present invention has the following beneficial effects:

[0022] 1. This invention loads ZIF-67 onto a hollow porous straw lignin fiber membrane and further pre-oxidizes and calcines it to obtain a ZIF-67@Co / HPLFM composite material, which can solve the pain points of using ZIF-67 alone.

[0023] 2. The ZIF-67@Co / HPLFM composite material prepared in this invention exhibits electron cloud overlap on its surface, which facilitates electron transfer between the two materials and guides non-radical electron transfer pathways to degrade pollutants. It has a degradation rate of up to 92% in the degradation of bisphenol A (BPA) by activated persulfate, showing good application prospects. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0025] Figure 1 The present invention relates to ZIF-67@Co and 1.0-ZIF-67@Co / HPLFM 0.9 The results of microstructure characterization;

[0026] Figure 2The present invention is ZIF-67@Co, HPLFM 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9 XRD patterns (a), FTIR patterns (b), N2 adsorption-desorption isotherms (c), and pore size distribution (d) are shown.

[0027] Figure 3 The present invention is ZIF-67@Co, HPLFM 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9 XPS spectra: total spectrum (a), C 1s (b), O 1s (c), N 1s (d) and Co 2p (e);

[0028] Figure 4 The degradation efficiency (a) and corresponding quasi-first-order rate constant (b) of BPA in different systems are shown in this invention; the effects of PVP dosage (c), cobalt salt dosage (d), catalyst dosage (e) and PMS dosage (f) on BPA degradation are also shown.

[0029] Figure 5 The graph shows the degradation efficiency of BPA (a) and Co leaching (b) in the ZIF-67@Co / HPLFM / PMS system during five cycles of testing; and the degradation efficiency of the ZIF-67@Co / HPLFM / PMS system in real water (c) and for various new pollutants (d). Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the following examples, the straw lignin is selected from rice straw lignin, but it can also be wheat straw lignin, rapeseed straw lignin, corn straw lignin, and composite straw lignin (a mixture of the above-mentioned lignins).

[0032] Example 1:

[0033] Add 0.3 g of polyacrylonitrile to 5.4 g of N,N-dimethylformamide and stir in a water bath at 60 °C until completely dissolved. Then add a certain amount of polyvinylpyrrolidone to the spinning solution and continue stirring in a water bath until the polyvinylpyrrolidone is completely dissolved. Finally, introduce 0.6 g of rice straw lignin into the system and heat and stir in a water bath for 12 h to obtain the shell spinning solution; add a certain amount of polyvinylpyrrolidone to 3.6 g of N,N-dimethylformamide and stir in a water bath at 60 °C until completely dissolved to obtain the core spinning solution.

[0034] The prepared electrospinning solution was electrospinned using a coaxial electrospinning process. The spinning conditions were as follows: positive voltage of 20 kV, negative voltage of 5 kV, translation width of the spinning needle of 0 cm, distance from the receiver of 16 cm, spinning humidity of 60%, injection rates of 15 and 10 μL / min for the shell and core layers, respectively, and room temperature. After spinning, the obtained nanofiber membrane was cut into several sheets with a mass of 60 mg each. Each sheet was placed individually in a 50 mL polytetrafluoroethylene high-pressure reactor, and 40 mL of deionized water was added to the reactor. The reactor was then placed in an electric heating drying oven at 120 °C for 3 h to remove polyvinylpyrrolidone. After the reaction was completed, the reactor was cooled to room temperature. The fiber membrane was then removed and washed with deionized water until neutral. Finally, the fiber membrane was placed in a freeze dryer to dry and obtain a hollow porous lignin fiber membrane (HPLFM). The total amount of polyvinylpyrrolidone added to the shell and core layers was 0.9 g, and the mass ratio of polyvinylpyrrolidone added to the shell and core layers was 1:3.

[0035] Weigh 1.0 mmol of Co(NO3)2·6H2O and dissolve it in a 100 mL Erlenmeyer flask containing 25 mL of anhydrous ethanol. Then, cut 20 mg of HPLFM and place it in the Erlenmeyer flask. Place the Erlenmeyer flask on a gyroscope at 120 rpm and shake it to allow a certain amount of cobalt salt to be adsorbed onto the fiber surface. After shaking for half an hour, slowly add 25 mL of anhydrous ethanol containing 2-methylimidazole (2-MeIm) to the Erlenmeyer flask. Continue shaking for another hour, maintaining the molar ratio of 2-methylimidazole to Co(NO3)2·6H2O at 8:1. After shaking is complete, remove the HPLFM, wash it alternately with anhydrous ethanol and deionized water, and then dry it in a freeze dryer to obtain the ZIF-67 / HPLFM precursor. Finally, the obtained ZIF-67 / HPLFM was placed in a muffle furnace and heated to 250°C at a rate of 5°C / min in air atmosphere, and calcined for 3 hours to obtain ZIF-67@Co / HPLFM, denoted as 1.0-ZIF-67@Co / HPLFM.

[0036] Example 2:

[0037] The steps are basically the same as in Example 1, except that the amount of Co(NO3)2·6H2O is 0.5 mmol, and the material prepared is denoted as 0.5-ZIF-67@Co / HPLFM.

[0038] Example 3:

[0039] The steps are basically the same as in Example 1, except that the amount of Co(NO3)2·6H2O is 0.75 mmol, and the material prepared is denoted as 0.75-ZIF-67@Co / HPLFM.

[0040] Example 4:

[0041] The steps are basically the same as in Example 1, except that the amount of Co(NO3)2·6H2O is 1.5 mmol, and the prepared material is denoted as 1.5-ZIF-67@Co / HPLFM.

[0042] Example 5:

[0043] The steps are basically the same as in Example 1, except that the amount of Co(NO3)2·6H2O is 2.0 mmol, and the prepared material is denoted as 2.0-ZIF-67@Co / HPLFM.

[0044] Comparative example:

[0045] Pure ZIF-67 and ZIF-67@Co particles:

[0046] The preparation process of pure ZIF-67 is as follows: 1.0 mmol of Co(NO3)2·6H2O was weighed and dissolved in a 100 mL Erlenmeyer flask containing 25 mL of anhydrous ethanol. The Erlenmeyer flask was placed on a vortex shaker at a speed of 120 rpm and shaken for half an hour. Then, 25 mL of anhydrous ethanol containing 2-methylimidazole (2-MeIm) was slowly added dropwise to the Erlenmeyer flask. The shaking was continued for another hour, maintaining the molar ratio of 2-methylimidazole to Co(NO3)2·6H2O at 8:1. After shaking, the flask was washed alternately with anhydrous ethanol and deionized water and then dried in a freeze dryer to obtain pure ZIF-67.

[0047] The preparation process of ZIF-67@Co particles is as follows: the pure ZIF-67 obtained above is placed in a muffle furnace, heated to 250°C at a rate of 5°C / min in air atmosphere, and calcined for 3 hours to obtain ZIF-67@Co particles.

[0048] Comparative Example 2:

[0049] Prepared HPLFM 0.9(That is, the hollow porous lignin fiber membrane prepared in Example 1, with a total amount of polyvinylpyrrolidone added to the shell and core layers of 0.9g, and a mass ratio of polyvinylpyrrolidone added to the shell and core layers of 1:3).

[0050] Test Analysis:

[0051] The samples prepared above were analyzed by SEM, TEM and EDS, and the results are shown in the figure. Figure 1 Among them, ZIF-67@Co( Figure 1 a) and 1.0-ZIF-67@Co / HPLFM 0.9 ( Figure 1 b) SEM image; 1.0-ZIF-67@Co / HPLFM 0.9 ( Figure 1 c) TEM image; 1.0-ZIF-67@Co / HPLFM 0.9 Element mapping ( Figure 1 d-1h):

[0052] from Figure 1 As can be seen from this, ZIF-67@Co exhibits a disordered granular structure, which is quite different from the traditional dodecahedral morphology of ZIF-67. This indicates that structural collapse occurred during the calcination of ZIF-67, resulting in the formation of disordered ZIF-67@Co. Figure 1 b shows that the disordered ZIF-67@Co has been successfully loaded onto the fiber structure of HPLFM, as can be seen from TEM ( Figure 1 Results c) show that ZIF-67@Co has also bonded tightly with HPLFM, and the hollow porous structure of HPLFM is not damaged during the calcination bonding process. Meanwhile, as shown in EDS mapping ( Figure 1 As shown in d-1h), C (66.5 Atomic%), O (17.7 Atomic%), N (13.3 Atomic%) and Co (2.5 Atomic%) elements are uniformly distributed in the composite material, indicating that the ZIF-67@Co / HPLFM composite material was successfully constructed.

[0053] The loading status of ZIF-67@Co on the HPLFM surface was detected by XRD test. Figure 2 a provides ZIF-67@Co, HPLFM 0.9XRD patterns of ZIF-67@Co / HPLFM composites synthesized with different amounts of cobalt salt were also presented. The HPLFM sample showed a broad peak around 2θ = 24°, corresponding to the (002) crystal plane of amorphous carbon. Furthermore, it can be seen that ZIF-67@Co, formed after calcination of ZIF-67, only showed a characteristic peak at 2θ = 13°, corresponding to disordered crystals, which is significantly different from the XRD pattern of traditional dodecahedral ZIF-67. This indicates that the crystal structure of ZIF-67 collapsed after calcination, consistent with the SEM results. Among the three synthesized ZIF-67@Co / HPLFM composites, the 0.5-ZIF-67@Co / HPLFM composite with the lowest cobalt salt content showed the best performance. 0.9 It shows the same performance as HPLFM 0.9 Similar XRD patterns, while 1.0-ZIF-67@Co / HPLFM 0.9 In addition to the amorphous peak, a weak characteristic peak appeared at 2θ = 17°, which may originate from the (013) crystal plane of the ZIF-67 dodecahedron that has not completely collapsed on its surface, and 2.0-ZIF-67@Co / HPLFM 0.9 The XRD patterns showed a significantly stronger characteristic peak at the same position. These results indicate that during the synthesis of ZIF-67@Co / HPLFM, the more cobalt salt used, the more ZIF-67@Co is loaded onto the HPLFM surface, and the ZIF-67@Co / HPLFM composite was successfully achieved.

[0054] ZIF-67@Co and HPLFM were analyzed using FTIR. 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9 Surface functional groups, such as Figure 2 As shown in b. All three materials are at 1600 and 1400 cm. -1 Characteristic absorption peaks appeared on the left and right sides, which are attributed to the stretching vibrations of C=N and C=C, respectively. The C=N and C=C in ZIF-67@Co may originate from the 2-methylimidazole molecule in ZIF-67. Additionally, ZIF-67@Co and 1.0-ZIF-67@Co / HPLFM... 0.9 At 1300cm -1 Another characteristic peak appearing at this point may also originate from the CN stretching vibration of the 2-methylimidazole molecule. HPLFM 0.9 The C=N and C=C may originate from the aromatic conjugated heterocyclic structure produced by PAN after pre-oxidation and calcination, and straw lignin molecules, while 1.0-ZIF-67@Co / HPLFM 0.9 The absorption peaks at both locations are likely related to the aforementioned structure. ZIF-67@Co shows absorption peaks at 668 and 750 cm⁻¹. -1The characteristic peaks at these locations are correlated with the stretching vibrations of Co(II)-O and Co(III)-O, respectively, indicating that some divalent cobalt is oxidized during the calcination of ZIF-67. Meanwhile, in 1.0-ZIF-67@Co / HPLFM... 0.9 These two characteristic peaks were also detected. Combined with the previous characteristic peak analysis, this indicates that ZIF-67@Co has been successfully loaded onto the surface of HPLFM.

[0055] The specific surface area and pore structure of the samples (ZIF-67@Co and ZIF-67@Co / HPLFM) were characterized using N2 adsorption-desorption measurements, such as... Figure 2 As shown in c, HPLFM 0.9 It still exhibits a type IV adsorption-desorption isotherm, with a specific surface area, pore volume, and average pore diameter of 10.7 m². 2 / g, 0.061cm 3 / g and 10.96nm indicate that HPLFM after calcination 0.9 Only a slight shrinkage of the fiber structure occurred, but the hollow and porous fiber morphology was still maintained, which is consistent with the TEM results. ZIF-67@Co and ZIF-67@Co / HPLFM also exhibited a type IV adsorption-desorption isotherm with an H3 hysteresis loop, indicating that both materials have a mesoporous structure. The specific surface area, pore volume, and average pore diameter of ZIF-67@Co are 836.9 m² / s. 2 / g, 0.612cm 3 The g / g and 6.60 nm indicate that although ZIF-67 underwent morphological collapse during calcination, the resulting ZIF-67@Co still retained its highly surface-active porous structure. However, ZIF-67@Co powder also suffers from the drawbacks of ZIF-67, such as difficulty in recovery and easy leaching. 1.0-ZIF-67@Co / HPLFM 0.9 The specific surface area, pore volume, and average pore diameter are 528.6 m². 2 / g, 0.417cm 3 The g / g and 7.06 nm indicate that the surface activity of ZIF-67@Co / HPLFM was significantly improved after the introduction of ZIF-67, suggesting that ZIF-67@Co has been successfully loaded onto the HPLFM surface structure. Furthermore, the relationship between ZIF-67@Co and HPLFM... 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9 Aperture distribution diagram ( Figure 2 As can also be seen in d), 1.0-ZIF-67@Co / HPLFM 0.9 The pore size distribution curve is between ZIF-67@Co and HPLFM 0.9The results are consistent with those of the adsorption-desorption isotherm.

[0056] The surface chemical state of the catalyst was analyzed using XPS spectroscopy. Figure 3 As can be seen in a, 1.0-ZIF-67@Co / HPLFM 0.9 The composite material exhibits characteristic peaks for C, O, N, and Co elements. Figure 3 b presents the C1s spectra of three samples. ZIF-67@Co exhibits two peaks at 285.8 and 284.8 eV, corresponding to CO and CC / C=C, respectively, which may originate from calcined 2-methylimidazole. HPLFM... 0.9 Three peaks were observed at 288.2, 286.0, and 284.8 eV, corresponding to C=O, CO, and CC / C=C, respectively, which may originate from lignin molecules in calcined straw. These peaks also appeared at 1.0-ZIF-67@Co / HPLFM. 0.9 However, their positions have shifted slightly. Figure 3 c shows the O1s spectrum of the selected sample. The peaks at 532.6 and 531.3 eV in ZIF-67@Co are attributed to adsorbed water and Co-O, respectively. HPLFM 0.9 The peaks at 533.1 and 531.6 eV are attributed to surface hydroxyl / adsorbed water and CO, which may also originate from calcined straw lignin molecules. These two characteristic peaks can also be observed in the composite material, with slightly shifted positions. In the N1s spectrum ( Figure 3 d), ZIF-67@Co and HPLFM 0.9 The nitrogen in the sample originates from 2-methylimidazole and calcined pre-oxidized PAN, respectively. The two peaks at 400.6 and 398.8 eV in ZIF-67@Co and HPLFM are also present. 0.9 The two peaks at 400.4 and 399.7 eV are attributed to pyrrole nitrogen and pyridine nitrogen, respectively, while the peaks at 1.0-ZIF-67@Co / HPLFM are attributed to pyrrole nitrogen and pyridine nitrogen, respectively. 0.9 These two characteristic peaks can also be observed in the spectrum, and their positions have changed in the same way as in the O1s spectrum. Figure 3 e shows the Co 2p spectra of the three materials. For the ZIF-67@Co sample, the two peaks at 796.5 and 780.8 eV are attributed to Co. 2+ The two peaks at 798.2 and 782.4 eV are attributed to Co. 3 + The two peaks at 802.4 and 786.7 eV are satellite peaks. (1.0-ZIF-67@Co / HPLFM) 0.9The aforementioned characteristic peaks were also detected in the composite material, and the positions of these peaks were slightly shifted. In summary, 1.0-ZIF-67@Co / HPLFM 0.9 The XPS spectrum of the composite film exhibits characteristic peaks of both ZIF-67@Co and HPLFM, indicating that the composite film material has been successfully synthesized. Furthermore, the binding energies of various elements show slight shifts after the ZIF-67@Co and HPLFM composite is formed, suggesting that electron cloud overlap may have occurred on the surfaces of the two materials, facilitating electron transfer between them.

[0057] Application Examples:

[0058] Using bisphenol A (BPA) as the target pollutant, the catalytic activity of the prepared samples was evaluated by PMS activation:

[0059] All catalytic degradation experiments were conducted in 100 mL light-proof glass beakers with continuous stirring at 200 rpm at room temperature. First, 10 mg of catalyst was added to 50 mL of a 100 mg / L BPA solution and stirred for 30 min to reach adsorption-desorption equilibrium. Then, 30 mg of PMS was added to initiate the catalytic degradation reaction. At 0, 5, 10, 15, 20, 25, 30, 35, and 40 min, 1 mL of the sample solution was taken, filtered through a 0.45 μm microporous membrane, and then placed in a sample vial containing 100 μL of 0.1 M Na₂S₂O₃ to terminate the reaction. Finally, the BPA concentration in the sample solution was detected using high-performance liquid chromatography (HPLC). The detection conditions were as follows: C-18 column (5 μm, 250 × 4.6 mm), column temperature 35 °C, UV detection wavelength 278 nm, mobile phase methanol / water (V / V = 80 / 20), and flow rate 0.8 mL / min.

[0060] Some of the conditions have changed as follows:

[0061] Catalyst dosage: The amount of catalyst in the reaction system was changed (0.1, 0.2, 0.3 and 0.4 g / L);

[0062] PMS concentration: Change the PMS concentration in the reaction system (0.2, 0.4, 0.6 and 0.8 g / L);

[0063] from Figure 4 The results showed ZIF-67@Co, HPLFM 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9 The adsorption of BPA by the catalyst reached equilibrium 30 minutes after the addition of PMS. (ZIF-67@Co, HPLFM) 0.9 and 1.0-ZIF-67@Co / HPLFM 0.9The catalyst adsorbed 17.4%, 5.0%, and 11.5% of BPA, respectively, after 30 min. Among them, HPLFM... 0.9 The adsorption capacity is the smallest, possibly due to its smaller specific surface area. ZIF-67@Co, retaining the high surface activity of ZIF-67, exhibits the largest adsorption capacity among the three materials. The composite membrane material 1.0-ZIF-67@Co / HPLFM... 0.9 The adsorption capacity is between ZIF-67@Co and HPLFM. 0.9 .

[0064] The samples underwent five consecutive cycles of degradation analysis (using different BPA contaminants, such as four novel contaminants: NOR, CBZ, SMX, and PNP), and the results are as follows. Figure 5 As shown, in five consecutive cycles, the degradation efficiencies of the ZIF-67@Co / HPLFM / PMS system for BPA were 92%, 88%, 86%, 85%, and 84%, respectively. This indicates that the BPA degradation efficiency slowly decreases with increasing experimental cycles. This may be due to the leaching of cobalt from the catalyst surface and the occupancy of some active sites by intermediates generated during the degradation reaction. Nevertheless, after the fifth cycle, the degradation efficiency of 1.0-ZIF-67@Co / HPLFM... 0.9 The degradation efficiency of BPA by PMS decreased by only 8%, indicating that the catalyst has good stability. Figure 5 As shown in b, the leaching of cobalt in the ZIF-67@Co / HPLFM composite material was significant in the first two uses, but the leaching amount decreased with increasing cycle number. By the fifth cycle, the cobalt leaching amount was only 0.136 mg / L. However, when ZIF-67@Co was used alone, the cobalt leaching amount remained consistently high. This indicates that after calcination, HPLFM effectively anchors ZIF-67@Co to its surface. These results demonstrate that ZIF-67@Co / HPLFM is a stable and highly efficient catalyst.

[0065] from Figure 5 As can be seen from d, when NOR, CBZ, SMX, and PNP are the four emerging pollutants as target pollutants, under the same conditions, using 1.0-ZIF-67@Co / HPLFM 0.9 Catalytic PMS degradation of these target pollutants. Results are as follows: Figure 5As shown in Figure d, the ZIF-67@Co / HPLFM / PMS system exhibits good degradation effects on NOR, CBZ, SMX, and PNP, with degradation efficiencies of 97%, 96%, 93%, and 87% respectively within 40 min. These results demonstrate that the ZIF-67@Co / HPLFM composite membrane material has good versatility and can be applied to various real water bodies and novel pollutants.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing ZIF-67@Co / HPLFM composite material, characterized in that, Includes the following steps: Provide porous hollow straw lignin fiber membranes; Cobalt salt was dissolved in anhydrous ethanol. Hollow porous straw lignin fiber membrane was placed in the mixed solution and shaken. Anhydrous ethanol containing 2-methylimidazole was added dropwise, and shaking was continued for a period of time. The hollow porous straw lignin fiber membrane was removed, washed, and freeze-dried to obtain the precursor material. The precursor material was calcined at high temperature to obtain the ZIF-67@Co / HPLFM composite material.

2. The preparation method of the ZIF-67@Co / HPLFM composite material as described in claim 1, characterized in that: The preparation process of hollow porous straw lignin fiber membrane is as follows: Polyacrylonitrile is added to N,N-dimethylformamide and stirred in a water bath until completely dissolved. A certain amount of polyvinylpyrrolidone is added and stirred in a water bath until completely dissolved. Then, straw lignin is added to obtain a shell spinning solution. A certain amount of polyvinylpyrrolidone is added to N,N-dimethylformamide and stirred in a water bath to dissolve to obtain a core spinning solution. The shell spinning solution and the core spinning solution are coaxially electrospun to obtain a fiber membrane. The fiber membrane is placed in a high-pressure reactor, deionized water is added to the reactor, and polyvinylpyrrolidone is removed by heating in a drying oven. The fiber membrane is taken out and washed with deionized water until neutral. It is then freeze-dried to obtain a porous hollow lignin fiber membrane. The straw lignin is one or more of rice straw lignin, wheat straw lignin, rapeseed straw lignin, or corn straw lignin.

3. The preparation method of the ZIF-67@Co / HPLFM composite material as described in claim 2, characterized in that: The mass ratio of straw lignin to polyacrylonitrile is 2:1, the mass ratio of straw lignin to polyvinylpyrrolidone is 1:(0.5-2), and the mass ratio of polyvinylpyrrolidone in the shell spinning solution and the core spinning solution is 1:

3.

4. The preparation method of the ZIF-67@Co / HPLFM composite material as described in claim 1, characterized in that: The cobalt salt is a divalent Co nitrate and its hydrate, and the amount of cobalt salt used is 0.5 to 2.0 mmol.

5. The method for preparing the ZIF-67@Co / HPLFM composite material as described in claim 4, characterized in that: The molar ratio of 2-methylimidazole to cobalt salt is 8:

1.

6. The method for preparing the ZIF-67@Co / HPLFM composite material as described in claim 1, characterized in that: The washing process involves removing the hollow porous straw lignin fiber membrane after the oscillation is complete and washing it alternately with anhydrous ethanol and deionized water.

7. The method for preparing the ZIF-67@Co / HPLFM composite material as described in claim 1, characterized in that: The high-temperature calcination is as follows: the precursor material is placed in a muffle furnace and heated to 250°C in an air atmosphere at a rate of 5°C / min for 3 hours.

8. The ZIF-67@Co / HPLFM composite material prepared by any of the preparation methods described in claims 1 to 7.

9. The application of the ZIF-67@Co / HPLFM composite material according to claim 8 in the degradation of organic pollutants by activated persulfate.

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