CN120790237B

CN120790237B - Nano-MOFs-supported bio-based fiber photoFenton catalytic materials, their preparation methods and applications

Info

Publication number: CN120790237B
Application number: CN202511309006.1A
Authority: CN
Inventors: 李纪委; 汤程顺; 杨亚娟; 邓正中; 曹颖
Original assignee: Nanjing Deprec Environmental Protection Technology Co ltd
Current assignee: Nanjing Deprec Environmental Protection Technology Co ltd
Priority date: 2025-09-15
Filing date: 2025-09-15
Publication date: 2025-11-21
Anticipated expiration: 2045-09-15
Also published as: CN120790237A

Abstract

This invention provides a nano-MOFs-supported bio-based fiber photo-Fenton catalytic material, its preparation method, and its application. The invention uses the environmentally friendly photosensitive material 4-carboxyphenylporphyrin (TCPP) as the organic ligand and ^Fe²⁺ as the central metal to prepare nano-Fe-MOFs, which are then loaded onto the surface of bio-based cotton fibers for photo-Fenton degradation of organic pollutants. Enhancing the bonding between the nano-Fe-MOFs and the bio-based cotton fibers mainly involves plasma cleaning, alkalization treatment, and carboxymethyl treatment of the fibers. Compared with traditional powder catalytic materials, the three-dimensional composite material Fe-MOFs/CF facilitates post-use recycling, greatly improving the material's practical performance. This invention has advantages such as being green, environmentally friendly, having a fast degradation rate, high removal rate, and easy recycling.

Description

Nanometer MOFs loaded bio-based fiber photo-Fenton catalytic material and preparation method and application thereof

Technical Field

The invention belongs to the technical fields of biological base environment-friendly materials, nano metal organic frame materials, and relates to the combination technology of nano materials and biological base carriers, photocatalysis technology, fenton-like degradation, organic matter removal and the like. In particular to a nano MOFs supported bio-based fiber photo-Fenton catalytic material, a preparation method and application.

Background

Antibiotics have been considered as emerging pollutants as the degradation of persistent organic pollutants in wastewater progresses. Their persistent effect on the entire ecosystem directly results in irreversible damage worldwide. At present, the methods for removing the antibody and other organic pollutants mainly comprise ion exchange, microbial treatment, membrane filtration, adsorption and Fenton advanced oxidative degradation, wherein the Fenton advanced oxidative method has the characteristics of strong oxidative degradation capability, no pollution, environmental protection, simple operation and the like, and is considered as one of the most promising methods in the organic pollutant removal technology. Fenton-like reaction is a high-level oxidation process for degrading organic pollutants by catalyzing hydrogen peroxide to generate high-activity free radicals (such as OH) through transition metals (such as iron, copper, manganese and the like) or compounds thereof. Common Fenton-like catalysts are iron oxides, copper oxides, single-atom catalysts, metal organic frameworks MOFs, and the like. Among the various types of Fenton catalysts, MOFs show tremendous potential in the field of catalytic degradation due to their active center metals, large specific surface area, and abundant pore structures. There are also some disadvantages in the Fenton-like reaction process. For example, powdered Fenton-like catalysts are not easily recovered, and the slow circulation of metal valence states in Fenton-like catalysts results in insufficient free radical yields. Some studies have used the photo Fenton technique to increase the degradation efficiency in order to increase the free radical conversion efficiency. The photo Fenton technology is to remarkably improve the generation efficiency of free radicals by introducing ultraviolet light or visible light on the basis of Fenton-like, so as to enhance the degradation capability of organic pollutants. During the reaction, the photo-Fenton catalyst plays an important role, and the catalyst can not only activate hydrogen peroxide, but also generate photo-generated electrons by light excitation to promote the metal valence state circulation. Therefore, it is necessary to explore a few photo-Fenton catalysts which are environment-friendly, high in catalytic efficiency and convenient to recycle.

Disclosure of Invention

Aiming at the technical problems, the invention provides a nano MOFs supported bio-based fiber photo-Fenton catalytic material, a preparation method and application thereof. In order to enhance the binding capacity of the nano MOFs and the bio-based cotton fiber, a series of pretreatment such as plasma cleaning, alkalization treatment, carboxymethylation and the like are carried out on the cotton fiber CF. The Fe _0.2 -MOFs/CF composite material is successfully prepared by taking a photosensitive material 4-carboxyphenyl porphyrin TCPP as an organic ligand Fe as a central metal and growing nano MOFs on the surface of cotton fiber CF in situ by a hydrothermal method. The 4-carboxyphenyl porphyrin TCPP has better visible light capturing capability as a green organic ligand, and particularly, the 4-carboxyphenyl porphyrin TCPP can be implanted with a single atom in the center of a rigid framework, so that the 4-carboxyphenyl porphyrin TCPP is mainly used as a component part of MOFs with various photosensitive characteristics. The light-induced e ⁻ excited by 4-carboxyphenyl porphyrin TCPP can transfer to Fe ₃O(COO)₆, resulting in accelerated reduction of Fe (III) to Fe (II) further promoting free radical generation. The photosensitiser 4-carboxyphenyl porphyrin TCPP is used as an organic ligand and Fe ions with Fenton activity are used as central metals, fe-MOFs are synthesized through hydrothermal synthesis, and the Fe-MOFs are loaded on cotton fibers, so that the dispersibility and the practicability of the cotton fibers are improved. Meanwhile, the combination promotes the separation of photo-generated electron-hole pairs, improves the oxidation-reduction capability of Fe (II)/Fe (III) in MOFs, and greatly improves the degradation efficiency through the synergistic effect of photocatalysis and Fenton.

Under the illumination condition, the catalyst activates H ₂O₂ to generate free radicals, and the generated free radicals attack tetracycline TC and other organic pollutants and decompose the tetracycline TC and other organic pollutants into micromolecules CO ₂ and H ₂ O.

The present invention achieves the above technical object by the following means.

The preparation method of the nano MOFs supported bio-based fiber photo-Fenton catalytic material is characterized by comprising the following steps of:

step S1, pretreatment of biological cotton fiber CF:

the cleaned cotton fiber CF is cleaned by adopting plasma for 60S, then alkalization treatment is carried out to activate cellulose in the cotton fiber CF, and finally carboxymethylation is carried out on the cotton fiber CF, so that the series of measures are beneficial to loading of MOFs of the metal organic frameworks;

S2, preparing a nano MOFs bio-based fiber composite material Fe _X -MOFs/CF:

Dissolving FeCl2.6H2O in an organic solvent, soaking the pretreated cotton fiber CF in the step S1 in the organic solvent for 8 h, dissolving benzoic acid, 4-carboxyphenyl porphyrin TCPP into the organic solvent, carrying out hydrothermal reaction on the solution of 4-carboxyphenyl porphyrin TCPP with FeCl2.6H2O=30:1:5 and 90 ℃ for 5:5 h to obtain Fe _X -MOFs/CF, drying the prepared Fe _X -MOFs/CF, and washing the prepared Fe _X -MOFs/CF with ethanol to remove undissolved ligand, thereby obtaining the final nano MOFs bio-based fiber composite material Fe _X-MOFs/CF;Fe_X -MOFs/CF, wherein X represents the doping amount of FeCl2.6H2O;

In this step, the ratio of benzoic acid to 4-carboxyphenyl porphyrin TCPP to fecl2.6h2o=30:1:5 was kept unchanged, and the change in the loading rate of MOFs on cotton fiber CF was achieved by varying the amount of fecl2.6h2o without changing the volume of the organic solvent.

Preferably, the alkalization treatment in the step S1 is to swell cotton fiber CF activated cellulose so as to facilitate better carboxymethylation, wherein alkali is a NaOH solution with a mass ratio of 20% -30%, 50 ml NaOH solutions correspond to 0.5 g-1.0 g of cotton fiber CF, and stirring is carried out for 1-3 hours at room temperature of 25-30 ℃.

In the above scheme, the carboxymethylation in step S1 is to enhance the binding of MOFs to cotton fibers CF. The chloroacetic acid solution 50 ml with the mass ratio of 20% -30% corresponds to 0.5 g-1.0 g of cotton fiber CF, and reacts for 2 h-4 h at 50 ℃ to 70 ℃.

Preferably, the organic solvent in step S2 is any one of N, N-dimethylformamide and ethanol.

Preferably, in the step S3, X is 0.05 to 0.25. In the step S3, the ratio of benzoic acid to 4-carboxyphenyl porphyrin TCPP to FeCl2.6H2O=30:1:5 is kept unchanged, the volume of an organic solvent is kept unchanged, the amount of FeCl2.6H2O is changed to realize the change of the loading rate of MOFs, and benzoic acid, 4-carboxyphenyl porphyrin TCPP and FeCl2.6H2O in Fe _X -MOFs/CF are respectively fixed for 0.3 g、0.01 g、0.05 g;0.6 g、0.02 g、0.10 g;0.9 g、0.03 g、0.15 g;1.2 g、0.04 g、0.20 g;1.5 g、0.05 g、0.25 g; pretreated cotton fibers CF to be 0.5 g unchanged.

Preferably, in the step S3 Fe _X -MOFs/CF, X is optimally 0.2, namely benzoic acid, 4-carboxyphenyl porphyrin TCPP, feCl2.6H2O, which is respectively 1.2 g, 0.04 g and 0.20 g, and the nano MOFs bio-based fiber composite material is Fe _0.2 -MOFs/CF.

The application of MOFs biological-based fiber composite material Fe _0.2 -MOFs/CF prepared by the preparation method of the nanometer MOFs supported biological-based fiber photo-Fenton catalytic material in the aspect of degrading and removing tetracycline TC and other organic pollutants. The other organic contaminants include methyl orange MO, methyl blue MB, norfloxacin NFX, enrofloxacin ENR, oxytetracycline OTC.

In the scheme, the application of the nanometer MOFs bio-based fiber composite material Fe _0.2 -MOFs/CF in catalyzing hydrogen peroxide H ₂O₂ to generate free radical oxidation and degradation of tetracycline TC and other organic pollutants under the illumination condition comprises the following steps:

Weighing Fe _0.2 -MOFs/CF of the nano MOFs biological-based fiber composite material, adding the nano MOFs/CF into water to be treated containing tetracycline TC and other organic pollutants, adding hydrogen peroxide H ₂O₂ under the illumination condition of a xenon lamp, adjusting pH, and degrading and removing TC and other organic pollutants by catalyzing H ₂O₂ to generate free radicals through the Fe _0.2 -MOFs/CF of the nano MOFs biological-based fiber composite material.

Furthermore, the adding amount of the Fe _0.2 -MOFs/CF of the nano MOFs bio-based fiber composite material is 0.05 g.L ^–1~0.25 g·L^–1, the using amount of the hydrogen peroxide H ₂O₂ is 5 mM-40 mM, the pH is adjusted to 2-10, the organic pollutant is 10 mg.L ^–1~100 mg·L^–1, and the illumination intensity of a xenon lamp is 100 mW/cm < 2 >.

Furthermore, the adding amount of the Fe _0.2 -MOFs/CF of the nano MOFs bio-based fiber composite material is 0.20 g.L ^–1.

Further, the hydrogen peroxide H ₂O₂ is used in an amount of 30: 30 mM.

Further, the pH is 6.

Further, the organic pollutant 50 mg.L ^–1.

Compared with the prior art, the invention has the beneficial effects that:

(1) According to the invention, 4-carboxyphenyl porphyrin TCPP is taken as an organic ligand, ferrous ions are taken as central metal, a novel nano MOFs is prepared and loaded on biological base fibers, and the novel nano MOFs are used for efficiently degrading organic pollutants by photo Fenton.

(2) The invention provides a biological base fiber surface treatment method which is used for enhancing the loading effect of nanometer MOFs, namely plasma cleaning, alkalization treatment and carboxymethylation treatment. The binding capacity of the nanometer MOFs and the fiber can be greatly enhanced through the treatment of three procedures, and the usability and the recoverability of the material are improved.

(3) The Fe _0.2 -MOFs/CF prepared by the method is used for catalyzing H ₂O₂ to degrade and remove tetracycline TC and other organic pollutants under the illumination condition, has good stability and high removal efficiency, and particularly can reach 99.13% removal rate for tetracycline TC after degrading 60min.

Drawings

FIG. 1 is a schematic illustration of a preparation process;

FIG. 2 is a mechanism diagram of photo-Fenton degradation TC;

FIG. 3 is a view of a material scanning electron microscope, wherein (a) in FIG. 3 is a view of a fresh cotton fiber CF scanning electron microscope, (b) in FIG. 3 is a view of a cotton fiber electron microscope after alkali treatment and carboxymethylation treatment, (c) in FIG. 3 is a view of a Fe _0.2 -MOFs/CF composite material, and (d) in FIG. 3 is a partial enlarged view of a Fe _0.2 -MOFs/CF composite material;

FIG. 4 is a characterization of the material, where (a) in FIG. 4 is the XRD pattern of Fe _0.2-MOFs、CF、Fe_0.2 -MOFs/CF and (b) in FIG. 4 is the XPS pattern of Fe _0.2-MOFs、Fe_0.2 -MOFs/CF;

FIG. 5 shows the removal rate of tetracyclines TC by composite materials (Fe _X -MOFs/CF) with different Fe doping ratios;

FIG. 6 shows the effect of different pH values on the removal rate of tetracycline TC under different conditions, FIG. 6 (a) shows the effect of different catalyst amounts on the removal rate of tetracycline TC, FIG. 6 (b) shows the effect of different hydrogen peroxide H ₂O₂ on the removal rate of tetracycline TC, and FIG. 6 (d) shows the removal effect of the system on tetracycline TC at different concentrations;

FIG. 7 shows the ability of different systems to degrade and remove tetracycline TC, FIG. 7 (a) shows the time profile of different systems degrading tetracycline TC, and FIG. 7 (b) shows the removal rate of tetracycline TC after degradation of 60 min;

Fig. 8 is a graph of the degradation of different organic contaminants by the photo-Fenton system over time.

Detailed Description

The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

Example 1A preparation method of nano MOFs supported bio-based fiber photo-Fenton catalytic material comprises the following steps:

the preparation method of the MOFs bio-based fiber composite material Fe _0.2 -MOFs/CF comprises the following steps:

step S1, pretreatment of cotton fiber CF:

The cotton fiber CF is alternately cleaned by deionized water and ethanol, and is dried and then is cleaned by plasma 60 s for activating oxygen-containing functional groups on the surface of the cotton fiber. An alkalization treatment was then performed to activate the cellulose in the cotton fibers CF, and 0.5 g cotton fibers CF were soaked in 50ml NaOH solution using a NaOH solution at a mass ratio of 20 ℃ and stirred for 2 hours at room temperature of 25 ℃. Finally, cotton fiber CF is subjected to carboxymethylation, 20% chloroacetic acid solution 50ml is used for soaking 0.5 g cotton fiber CF, and reaction is carried out at 70 ℃ for 2h. As shown in fig. 3 (a), the fresh cotton fiber CF surface was very smooth. When the surface of the cotton fiber CF shows a spiral microfibril structure after plasma, alkalization and carboxymethylation, the structure can well load the nanometer MOFs, and the structure is shown in figure 3 (b).

Step S2, preparing the nanometer MOFs bio-based fiber composite material Fe _X -MOFs/CF:

Fe _X -MOFs/CF was prepared by dissolving 0.05 g-0.25 g FeCl2.6H2O in 40 ml ethanol solution, and subsequently impregnating the pretreated cotton fibers CF with 8 h. 0.3 g-1.5 g of benzoic acid, 0.01 g-0.05 g of 4-carboxyphenyl porphyrin TCPP are then dissolved therein and the benzoic acid 4-carboxyphenyl porphyrin TCPP is reacted hydrothermally at 90℃with FeCl2.6H2O=30:1:5 to produce Fe _X -MOFs/CF at5 h. And then drying and cleaning the prepared Fe _X -MOFs/CF to obtain the final nano MOFs bio-based fiber composite material Fe _X -MOFs/CF.

The ratio of benzoic acid to 4-carboxyphenyl porphyrin TCPP to FeCl2.6H2O=30:1:5 is kept unchanged in the preparation process of Fe _X -MOFs/CF, cotton fiber CF is fixed to be 0.5: 0.5 g, the volume (40 mL) of an organic solvent is kept unchanged, and the amount of FeCl2.6H2O is changed to realize the change of the loading rate of MOFs. Scanning electron microscope images of benzoic acid, 4-carboxyphenyl porphyrin TCPP and FeCl2.6H2O in Fe _X -MOFs/CF respectively are 0.3 g、0.01 g、0.05 g;0.6 g、0.02 g、0.10 g;0.9 g、0.03 g、0.15 g;1.2 g、0.04 g、0.20 g;1.5 g、0.05 g、0.25 g.X, and represent doping amounts of FeCl2.6H2O of 0.05, 0.10, 0.15, 0.20 and 0.25, namely Fe_0.05-MOFs/CF、Fe_0.10-MOFs/CF、Fe_0.15-MOFs/CF、Fe_0.20-MOFs/CF、Fe_0.25-MOFs/CF,Fe_0.20-MOFs/CF respectively, as shown in fig. 3 (c) and 3 (d).

Example 2A Fe _X -MOFs/CF composite material prepared by the invention catalyzes hydrogen peroxide H ₂O₂ to generate free radicals under the illumination condition for degrading tetracycline TC, and the specific steps include:

(1) Preparing a tetracycline TC mother solution:

100mg tetracyclines TC were weighed into a 1L beaker, added with 800 mL deionized water, sonicated to dissolve, and then transferred to a 1L volumetric flask to volume. Tetracycline TC mother liquor was prepared at 100 mg.L ^–1.

(2) Drawing of the tetracycline TC solution standard curve:

And (3) diluting the mother solution to different concentration gradients of 1 mg.L ^–1、5 mg·L^–1、10 mg·L^–1、30 mg·L^–1、50 mg·L^–1, detecting the absorbance of different concentrations of TC at 358nm by adopting an ultraviolet spectrophotometer, and drawing a standard curve for subsequent calculation of TC concentration according to the linear relation between the absorbance of different concentrations of TC at 358nm and the concentration value thereof.

(3) Fe _X -MOFs/CF catalyzes the degradation of tetracycline TC by H ₂O₂ under light conditions:

A solution of TC at a concentration of 50 mg.L ^–1 in 20: 20 mL was added to the vial, followed by weighing 0.004 g Fe _X -MOFs/CF material into it, and finally, at 10mM H ₂O₂ (30%) was added, the xenon light source was spaced from the vial 20: 20 cm. Under the illumination condition, fe _X -MOFs/CF catalyzes H ₂O₂ to generate free radicals to degrade and remove TC, and the illumination can obviously enhance the efficiency of Fe _X -MOFs/CF in catalyzing H ₂O₂ to generate free radicals. At intervals of 0min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min respectively, 1mL of the sample was extracted, absorbance thereof was measured by ultraviolet and carried into a standard curve to calculate the TC concentration of the sample, and degradation efficiency was evaluated based on the ratio of the existing concentration to the initial concentration (C _t/C₀). The concentration of the reaction mixture may be measured by sampling after the reaction mixture is reacted with 60 min, and the TC removal rate after the reaction mixture is reacted with 60 min may be calculated.

(4) The TC degradation efficiency at each time period is denoted by C _t/C₀ and the removal rate is calculated as follows:

r = (1– C_t/C₀)× 100%

(5) Effect of different doping ratios on Fe _X -MOFs/CF photo Fenton removal TC:

under the condition of ensuring that the conditions of catalyst addition amount, illumination intensity, H ₂O₂ addition amount, TC concentration and the like are consistent, the catalysis performance of the composite materials with different proportions is compared. 0.004 g Fe_0.05-MOFs/CF、Fe_0.10-MOFs/CF、Fe_0.15-MOFs/CF、Fe_0.20-MOFs/CF、Fe_0.25-MOFs/CF was weighed and added to a solution of TC 20 in mL concentration 50 mg.L ^–1, to which solution was added 21.6. Mu.L of 30% H ₂O₂ (10 mM), followed by reaction 60 min under irradiation with a xenon lamp light source. And testing the TC concentration after degradation to calculate the removal rate. As shown in FIG. 5, the results of the test show that the removal rates of .Fe_0.05-MOFs/CF、Fe_0.10-MOFs/CF、Fe_0.15-MOFs/CF、Fe_0.20-MOFs/CF、Fe_0.25-MOFs/CF on TC under the photo Fenton system are 86.90%, 92.86%, 97.38%, 98.05% and 98.57%, respectively. The removal rate of Fe _0.05 -MOFs/CF to Fe _0.15 -MOFs/CF increases with increasing doping ratio of MOFs in the composite material under the same conditions, and the removal rate hardly increases when the doping ratio increases further (Fe _0.20 -MOFs/CF to Fe _0.25 -MOFs/CF), so that the Fe _0.20 -MOFs/CF composite material is used for characterization and condition screening. The Fe _X -MOFs/CF content and removal rate of the different doping ratios are shown in the following table:

Example 3 different pH and usage conditions of Fe _0.20 -MOFs/CF and H ₂O₂ photo Fenton system in degradation process are optimized, and the specific steps are as follows:

pH condition optimization probe:

Under the condition of ensuring that the addition amount of H ₂O₂, the TC concentration, the use amount of a catalytic group, the illumination intensity and other conditions are consistent, the prepared TC solution is adjusted to be a solution with pH of 2, 4, 6, 8 and 10 by using 0.1M HCl and 0.1M NaOH.

0.004 g Fe_0.05-MOFs/CF、Fe_0.10-MOFs/CF、Fe_0.15-MOFs/CF、Fe_0.20-MOFs/CF、Fe_0.25-MOFs/CF Was weighed and added to a solution of TC 20 in mL concentration 50 mg.L ^–1, to which solution was added 21.6. Mu.L of 30% H ₂O₂ (10 mM), followed by reaction 60 min under irradiation with a xenon lamp light source. The TC removal rates under different pH conditions are shown in FIG. 6 (a), and the removal rates of the photo-Fenton system on TC at pH 2, 4, 6, 8 and 10 are 83.24%, 98.32%, 97.55%, 76.76% and 69.45% respectively. Proton-promoted dissolution under peracid conditions may lead to partial destruction of the material, H ₂O₂ readily decomposing into O ₂ and H ₂ O under alkaline conditions, reducing the yield of free radicals. The pH is 6 closer to the actual body of water, so the pH is 6 after subsequent use.

The dosage of the catalyst Fe _0.20 -MOFs/CF is optimized:

A glass bottle of 50 mL was charged with 20 mL of TC solution at a concentration of 50 mg.L ^–1, followed by weighing 0.001 g, 0.002g, 0.003 g, 0.005 g, 0.005 g Fe _0.20 -MOFs/CFF material and adding thereto, and finally adding 21.6. Mu.L of H ₂O₂ (10 mM). The TC concentration was then measured by placing the vial under irradiation of a xenon lamp light source, reaction 60 min. As shown in FIG. 6 (b), the effect of the amounts of Fe _0.20 -MOFs/CF on the TC-removing rate was increased gradually as the amount of Fe _0.20 -MOFs/CF added was increased from 0.05 g.L ^–1 to 0.25 g.L ^–1. After 60 min of degradation, the removal rates of Fe _0.20 -MOFs/CF of 0.05 g.L ^–1、0.10 g·L^–1、0.15 g·L^–1、0.20 g·L^–1、0.25 g·L^–1 of catalyst to TC are 86.23%, 92.07%, 93.97%, 96.11% and 96.25% respectively.

When the amount of the catalyst to be added was 0.20 g.L ^–1、0.25 g·L^–1, the removal rate was almost flat, and therefore, 0.20 g.L ^–1 was selected as the optimum amount to be added from the viewpoint of cost.

(3) H ₂O₂ concentration optimization:

Under the condition of ensuring that the addition amount of Fe _0.20 -MOFs/CF is 0.20 g.L ^–1, the TC concentration of 20 mL is 50 mg.L ^–1, the pH=6, the illumination condition and other conditions are consistent, the addition amount of H ₂O₂ is changed. To the solution, 10.8. Mu.L, 21.6. Mu.L, 43.2. Mu.L, 64.8. Mu.L, 86.4. Mu. L H ₂O₂, respectively, corresponding to 5mM, 10mM, 20 mM, 30 mM, 40 mM, respectively, were added. The TC solution concentration after the reaction was measured after the glass bottle was placed under a xenon lamp light source for the reaction of 60 min. As a result, as shown in FIG. 6 (c), the amounts of H ₂O₂ used were 5mM, 10mM, 20 mM, 30 mM, 40 mM, and TC removal rates after degradation of 50 min were 88.24%, 95.66%, 97.84%, respectively,

98.67%, 98.99, And the TC removal rate is increased along with the increase of the H ₂O₂ concentration, so that the final removal rate reaches a plateau, and 30 mM is the final addition amount from the economic cost.

(4) The ability of the photoFenton system to degrade different TC concentrations:

In order to explore the degradation capability of the photo Fenton system on TC with different concentrations, under the conditions of ensuring that the addition amount of Fe _0.20 -MOFs/CF is 0.20 g.L ^–1,pH=6,H₂O₂ and 30mM, the volume of TC solution is 20 mL, the illumination conditions and the like are consistent, the TC with different concentration gradients is respectively 10 g.L ^–1、30 g·L^–1、50 g·L^–1、70 g·L^–1、100 g·L^–1. Reaction 60 min measured the TC solution concentration to calculate the removal rate. As a result, as shown in FIG. 6 (d), the removal rates of TC solution of 10 g.L ^–1、30 g·L^–1、50 g·L^–1、70 g·L^–1、100 g·L^–1 by the photo Fenton system were 97.56%, 98.72%, 98.69%, 96.09% and 95.32%, respectively. The result shows that the photo Fenton system has good removal effect on low-concentration and high-concentration TC solutions.

In the embodiment 4, the effect of removing TC under different systems is explored, and whether the influence of single factor variable on TC degradation and the adsorption performance, fenton-like performance, photocatalytic performance and photo Fenton performance of the material are mainly examined, wherein the method specifically comprises the following steps:

(1) Degradation effect of H ₂O₂ on TC:

64.8. Mu.L of H ₂O₂ (30 mM) was added to a TC solution of 20mL concentration 50 mg.L ^–1, and the degradation efficiency was evaluated by C _t/C₀ at intervals of 10min, 20 min, 30 min, 40min, 50 min, 60 min samples, and the degradation process was as shown in FIG. 7 (a). The TC removal after degradation of 60 min was only 0.57%, and the results are shown in FIG. 7 (b). The results show that the mere addition of H ₂O₂（30 mM）,H₂O₂ by itself hardly stimulates the production of free radicals to degrade TC.

(2) Degradation effect of light on TC:

To investigate the effect of light irradiation on degradation performance, a xenon lamp light source was directly irradiated to a TC solution having a concentration of 50mg ·l ^–1 of 20 mL, and the degradation efficiency was evaluated by C _t/C₀ every 10min, 20 min, 30 min, 40 min, 50min, 60 min check for a change in concentration as shown in fig. 7 (a). The TC removal after degradation of 60 min was only 4.24%, and the results are shown in FIG. 7 (b). The results indicate that light exposure affects TC concentration.

(3) Degradation effect of light + H ₂O₂ on TC:

To investigate the effect of light in combination with H ₂O₂ on TC degradation, 64.8 μl of H ₂O₂ (30 mM) was added to a TC solution of 20 mL concentration 50 mg ·l ^–1 and the solution was placed under a xenon light source for irradiation. The degradation efficiency was evaluated by C _t/C₀ for the concentration measured every 10min, 20 min, 30min, 40min, 50 min, 60 min samples, and the degradation process was as shown in fig. 7 (a). The TC-removal after degradation of 60 min was 12.04%, and the results are shown in FIG. 7 (b). The results show that the degradation capacity of the combination of illumination and H ₂O₂ on TC is obviously better than that of pure H ₂O₂ and pure illumination, which shows that the illumination can excite H ₂O₂ to generate a small part of free radicals for TC degradation.

(4) Adsorption removal effect of catalyst on TC:

In order to evaluate the adsorption performance of the catalyst per se, the adsorption performance of the catalyst was examined by adding only the catalyst to the TC solution in the removal ratio of TC in the photo-Fenton system. The degradation efficiency was evaluated by C _t/C₀ by adding 0.004 g catalyst Fe _0.20 -MOFs/CF to a TC solution of 20mL concentration 50 mg.L ^–1 and checking the concentration change every 10 min, 20 min, 30 min, 40 min, 50 min, 60 min as shown in FIG. 7 (a). The TC removal after degradation of 60 min was only 8.03%, and the results are shown in FIG. 7 (b). The results show that the adsorption capacity of the catalyst itself to TC is low.

(5) Degradation effect of catalyst+illumination photocatalytic system on TC:

To evaluate the effect of the catalyst+illuminated photocatalytic system in photo-Fenton, 0.004 g of the catalyst Fe _0.20 -MOFs/CF was added to a TC solution of 20 mL concentration 50 mg.L ^–1 and irradiated by a xenon light source, the degradation efficiency was evaluated by C _t/C₀ every 10min, 20 min, 30 min, 40 min, 50 min, 60 min of its concentration change, the degradation process being shown in FIG. 7 (a). The TC removal after degradation of 60 min was 14.24%, and the results are shown in FIG. 7 (b). The result shows that the photocatalytic system has a certain degradation effect, which indicates that light can excite electron-hole separation for TC degradation, but the electron-hole easy composite degradation effect is lower, so that the photocatalysis does not play a leading role. Photocatalytic reaction formula:

Fe_0.20-MOFs/CF+hν → h⁺+e^- (1)

(6) Degradation effect of H ₂O₂ + catalyst Fenton-like system on TC:

0.004 g of the catalyst Fe _0.20 -MOFs/CF was added to a TC solution of 20mL concentration 50 mg.L ^–1 and 64.8. Mu.L of H ₂O₂ (30 mM) was added, and the degradation efficiency was evaluated by C _t/C₀ every 10min, 20 min, 30 min, 40min, 50 min, 60 min for concentration changes, and the degradation process was as shown in FIG. 7 (a). Fe ²⁺ is able to activate H ₂O₂ to generate hydroxyl radicals for TC degradation. The reaction formula is as follows:

Fe²⁺+H₂O₂ → Fe³⁺+·OH+OH⁻ (2)

Fe³⁺+H₂O₂ → Fe²⁺+·OOH+H⁺(3)

The rate of Fe ²⁺ to react with H ₂O₂ in the Fenton-like reaction to form Fe ³⁺ is very fast, however, the rate of Fe ³⁺ reduction to Fe ²⁺ is very slow, resulting in rapid depletion of Fe ²⁺ and accumulation of Fe ³⁺. The results of the degradation effect of the H ₂O₂ + catalyst Fenton-like system on TC in this example are shown in FIG. 7 (b). The TC removal rate after degradation of 60 min is 58.86%, and the result shows that although the Fenton-like system plays a dominant role in the process of degrading TC, the cycle process of Fe ²⁺/Fe³⁺ still has an improvement space.

(7) Degradation effect of light + catalyst + H ₂O₂ photo Fenton system on TC:

0.004 g of Fe _0.20 -MOFs/CF was added to a TC solution of 20mL concentration 50 mg.L ^–1 and 64.8. Mu.L of H ₂O₂ (30 mM) was added, and reacted under a xenon light source, the degradation efficiency was evaluated by C _t/C₀ every 10 min, 20 min, 30min, 40 min, 50 min, 60 min for concentration change, and the degradation process was shown in FIG. 7 (a). The photo Fenton system reaction formula is as follows:

Fe²⁺+H₂O₂ → Fe³⁺+·OH+OH⁻ (2)

Fe³⁺+H₂O₂ → Fe²⁺+·OOH+H⁺(3)

Fe_0.20-MOFs/CF+hν → h⁺+e^- (1)

Fe³⁺+e^- → Fe²⁺(4)

light can excite electron hole separation in the photo Fenton reaction, generated electrons can be consumed by Fe ³⁺ so as to promote Fe ²⁺/Fe³⁺ circulation in the Fenton-like reaction to solve the problem that Fe ²⁺ rapidly consumes Fe ³⁺ and accumulates, and holes are difficult to recombine after the electrons are consumed, so that the photocatalysis performance is enhanced. The results of the degradation effect of the H ₂O₂ + catalyst + illuminated photo-Fenton system on TC in this example are shown in FIG. 7 (b). The TC removal rate after 60 min of degradation is 99.13%, and the result shows that the photo-Fenton system can efficiently degrade and remove TC. The data of the TC degradation process of different reaction systems are shown in the following table:

the removal rate r of TC in each time period of different reaction systems is r= (1-C _t/C₀) ×100%, and detailed data are shown in the following table:

Example 5 the photo Fenton system degrades other organic pollutants, the specific steps are:

Other organic contaminant solutions of 50 mg.L ^–1 were prepared. Other organic contaminants are methyl orange MO, methyl blue MB, norfloxacin NFX, enrofloxacin ENR, oxytetracycline OTC. 0.004 g of Fe _0.20 -MOFs/CF was added to a solution of 20mL concentration 50 mg.L ^–1 of methyl orange MO, methyl blue MB, norfloxacin NFX, enrofloxacin ENR, oxytetracycline OTC and 64.8. Mu.L of H ₂O₂ (30 mM) and reacted under xenon light source conditions, the degradation efficiency was evaluated by C _t/C₀ every 10min, 20 min, 30 min, 40 min, 50 min, 60min of concentration change, degradation process being shown in FIG. 6. The removal rates of methyl orange MO, methyl blue MB, norfloxacin NFX, enrofloxacin ENR and oxytetracycline OTC after reaction 60min are 51.28%, 99.41%, 87.84%, 65.33% and 97.31% respectively. The photo Fenton system has good degradation and removal effects on other organic pollutants. The detailed data of degradation process with time are shown in the following table:

the removal rate of other organic pollutants from the optical Fenton system is changed along with time as shown in the following table:

The nano Fe-MOFs prepared by taking the green and environment-friendly photosensitive material 4-carboxyphenyl porphyrin TCPP as an organic ligand and Fe ²⁺ as central metal has excellent photo-Fenton catalytic performance, and can rapidly and efficiently remove tetracycline TC and other organic pollutants. The improvement of the photo Fenton degradation performance is mainly attributed to the separation of photo-excited electron holes, photo-generated electrons can promote the reduction of Fe ³⁺ in Fenton-like process, electrons are consumed in Fenton-like process, so that electron holes are not easy to be combined, and the photo-catalytic degradation process is promoted in a reverse feeding way. The photocatalysis and Fenton-like synergy greatly promote free radical to produce degradation of high-efficiency degradation organic matters, and the removal rate of the methyl blue MO can reach 99.41 percent within 60 min.

Besides, the invention also relates to the combination technology of nano Fe-MOFs and bio-based cotton fibers, which mainly comprises plasma cleaning, alkalization treatment and carboxymethyl treatment. The nano Fe-MOFs is loaded on the bio-based fiber CF, so that agglomeration of the nano Fe-MOFs can be well avoided, and the catalytic efficiency of the nano Fe-MOFs is improved. The photo-Fenton degradation system of Fe _0.20 -MOFs/CF+illumination+H ₂O₂ has the advantages of high degradation rate, high removal rate, environment friendliness, convenience in recovery and the like, and is successfully used for degrading tetracycline TC and other organic pollutants.

It should be noted that, although this patent document describes embodiments, it does not mean that each embodiment relates to only a single technical solution. Such expressions are for illustrative clarity only, and one skilled in the relevant art will understand the description in its entirety. In fact, the technical solutions disclosed in the embodiments may be reasonably combined according to actual needs, so as to form other technical solutions that can be implemented by those skilled in the art.

The foregoing example details are merely specific illustrations of possible embodiments of the invention and are not intended to limit the scope of the invention. Any equivalent substitutions or modifications based on the core technical idea of the present invention should be considered to fall within the scope of the claims of the present invention.

Claims

1. A method for preparing a bio-based fiber photoFenton catalytic material supported on nano-MOFs, characterized by comprising the following steps:

Step S1, Pretreatment of bio-based cotton fiber (CF):

The cleaned cotton fiber CF was plasma cleaned for 60 seconds, followed by alkalization to activate the cellulose in the cotton fiber CF, and finally carboxymethylation of the cotton fiber CF. This series of measures is beneficial for loading metal-organic frameworks (MOFs).

Step S2: Preparation of Fe _X -MOFs/CF nano-MOFs bio-based fiber composite material:

Will The cotton fibers CF pretreated in step S1 were dissolved in an organic solvent, and then impregnated in the organic solvent for 8 hours; subsequently, benzoic acid and 4-carboxyphenylporphyrin TCPP were dissolved in the solvent, and the ratio of benzoic acid:4-carboxyphenylporphyrin TCPP: _FeX- MOFs/CF was prepared by hydrothermal reaction at 90℃ for 5 h with a ratio of 30:1:5. The prepared _FeX -MOFs/CF was then dried and washed with ethanol to remove undissolved ligands, yielding the final nano-MOFs bio-based fiber composite material, _FeX -MOFs/CF. In _FeX- MOFs/CF, X represents... Doping amount;

In this step, maintain benzoic acid: 4-carboxyphenylporphyrin TCPP: The ratio of 30:1:5 remains unchanged, and the volume of the organic solvent is not altered. The change is achieved by altering... The amount of MOFs is used to change the loading rate of CF in cotton fibers.

2. The method for preparing nano-MOFs-supported bio-based fiber photo-Fenton catalytic material according to claim 1, characterized in that, in step S1, the alkalization treatment is to swell cotton fiber CF to activate cellulose for better carboxymethylation, the alkali is a 20%~30% mass ratio NaOH solution, 50 ml of NaOH solution corresponds to 0.5 g~1.0 g of cotton fiber CF, and the mixture is stirred at room temperature (25~30℃) for 1~3 h.

3. The method for preparing nano-MOFs-supported bio-based fiber photo-Fenton catalytic material according to claim 1, characterized in that, in step S1, carboxymethylation is to improve the binding of MOFs with cotton fiber CF; 50 ml of 20%~30% chloroacetic acid solution corresponds to 0.5 g~1.0 g of cotton fiber CF, and the reaction is carried out at 50℃~70℃ for 2 h~4 h.

4. The method for preparing the nano-MOFs-supported bio-based fiber photo-Fenton catalytic material according to claim 1, characterized in that the organic solvent in step S2 is any one of N,N-dimethylformamide and ethanol.

5. The method for preparing nano-MOFs-supported bio-based fiber photo-Fenton catalytic material according to claim 1, wherein X in step S2 is 0.05~0.25.

6. The method for preparing the nano-MOFs-supported bio-based fiber photoFenton catalytic material according to claim 5, characterized in that X in step S2 is 0.2, i.e., benzoic acid, 4-carboxyphenylporphyrin TCPP, The amounts were 1.2 g, 0.04 g, and 0.20 g, respectively, and the nano-MOFs bio-based fiber composite material was Fe _0.2 -MOFs/CF.

7. The application of a nano-MOFs bio-based fiber composite material prepared by the method according to any one of claims 1-6 for photo-Fenton degradation of tetracycline TC and other organic pollutants.

8. The application of the nano-MOFs bio-based fiber composite material according to claim 7 to photo-Fenton degradation of tetracycline TC and other organic pollutants, characterized in that the other organic pollutants include methyl orange (MO), methylene blue (MB), norfloxacin (NFX), enrofloxacin (ENR), and oxytetracycline (OTC).

9. The application of the nano-MOFs bio-based fiber composite material according to claim 7 in photo-Fenton degradation of tetracycline TC and other organic pollutants, characterized in that the application of photo-enhanced composite material catalyzing the generation of free radicals from hydrogen peroxide ( _H₂O₂ ₎ to oxidize and degrade tetracycline TC and other organic pollutants includes the following steps:

The nano-MOFs bio-based fiber composite material Fe _0.2 -MOFs/CF was weighed and added to the water to be treated containing tetracycline TC and other organic pollutants. Hydrogen peroxide ( _H₂O₂ ₎ was then added to adjust the pH. A _xenon lamp light source was introduced to catalyze _the _H₂O₂ to generate free radicals under light irradiation, thereby degrading and removing tetracycline TC and other organic pollutants.

10. The application of the nano-MOFs bio-based fiber composite material according to claim 9 in the photo-Fenton degradation of tetracycline TC and other organic pollutants, characterized in that the dosage of the MOFs bio-based fiber composite material Fe _0.2 -MOFs/CF is 0.05 g· ^L⁻¹ to 0.25 g· ^L⁻¹ ; the amount of hydrogen peroxide ( _H₂O₂ ₎ used is 5 mM to 40 mM; the pH is 2 to 10; the organic pollutant concentration is 10 mg· ^L⁻¹ to 100 mg· ^L⁻¹ ; and the xenon lamp irradiation intensity is 100 mW/cm².