Catalytic membrane-based treatment method for sulfamethoxazole in reclaimed water

Abstract

The invention provides a method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane. The method comprises the following steps: step 10, preparing a nano catalytic material; step 20, preparing the powdery nano catalytic material into a catalytic membrane; 30, the catalytic membrane is installed in a reactor, and an oxidizing agent solution is injected into the reactor; reclaimed water containing sulfamethoxazole is conveyed into the reactor and passes through the catalytic membrane in a circular flow mode; and meanwhile, the catalytic membrane is illuminated. According to the method for treating the sulfamethoxazole in the reclaimed water based on the catalytic membrane, provided by the invention, the service life of the catalytic membrane can be prolonged, and the removal effect of the sulfamethoxazole is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and specifically relates to a method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane. Background Art

[0002] With the wide application of reclaimed water in ecological water replenishment, agricultural irrigation and other fields in urban and rural areas of China, its reuse safety has attracted extensive attention. Various new pollutants contained in reclaimed water, such as the neonicotinoid insecticide nitenpyram, the anti-epileptic drug carbamazepine, and the antibiotic sulfamethoxazole, will migrate to the receiving water body during the reuse process, and be enriched and transformed through the water-soil-plant continuum, posing a potential threat to ecological safety and human health. Advanced oxidation technologies have shown application potential in treating complex new pollutants due to their strong oxidation ability.

[0003] Among them, the most commonly used Fenton oxidation technology can be divided into the traditional homogeneous Fenton oxidation technology and the improved heterogeneous Fenton oxidation technology according to its reaction form. The traditional homogeneous Fenton oxidation technology uses ferrous ions and hydrogen peroxide to react in an acidic aqueous solution to generate highly reactive hydroxyl radicals to remove harmful substances in the wastewater. Significantly different from the homogeneous catalytic process (where the reaction occurs throughout the liquid phase medium), the heterogeneous Fenton method cleverly transfers the reaction interface to the surface of the solid catalyst, realizing the efficient adsorption and conversion of the oxidant at the active sites of the catalyst, and broadening the scope of application. For example, the solid catalyst is prepared into a catalytic membrane, and the catalytic membrane is used to treat new pollutants such as sulfamethoxazole in reclaimed water.

[0004] However, after multiple cycles of use of the existing catalytic membrane, the electron donors near the active sites are gradually oxidized and cannot continue to provide electrons for the oxidant, ultimately resulting in the inactivation of the sites, a decrease in the oxidation reaction rate, and a short service life of the catalytic membrane. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to provide a method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane, which can extend the service life of the catalytic membrane and improve the removal effect of sulfamethoxazole.

[0006] To solve the above technical problem, the present invention adopts the following technical scheme: The present invention provides a method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane, comprising the following steps: Step 10, preparing a nano-catalytic material; Step 20, preparing the powdered nano-catalytic material into a catalytic membrane; Step 30: Install the catalytic membrane in the reactor, inject the oxidant solution into the reactor; convey the reclaimed water containing sulfamethoxazole to the reactor, and let it flow through the catalytic membrane in a circulating manner; meanwhile, irradiate the catalytic membrane with light.

[0007] As a further improvement of the present invention, step 10 specifically includes: Step 101: Prepare a metal-organic framework material; Step 102: Prepare iron oxide particles inside the metal-organic framework material to obtain a confined iron nanomaterial; Step 103: Vertically grow molybdenum disulfide nanosheets on the surface of the confined iron nanomaterial to obtain a nano-catalytic material.

[0008] As a further improvement of the present invention, step 102 specifically includes: Step 1021: Use an ether solution as a solvent and 2-tert-butyl-p-cresol as a solute to prepare a 2-tert-butyl-p-cresol ether solution. Under closed conditions, mix the 2-tert-butyl-p-cresol ether solution with the metal-organic framework material to obtain a mixed solution; Step 1022: Heat the mixed solution obtained in step 1021 to a constant weight; Step 1023: Disperse the mixed solution treated in step 1022 in an aqueous solution of FeCl2·4H2O and carry out a shaking reaction at room temperature; Step 1024: Centrifuge to collect the precipitate product obtained in step 1023. After repeatedly washing the product with an ethanol solution and deionized water, place the product in an oven for aging to obtain a confined iron nanomaterial.

[0009] As a further improvement of the present invention, in step 1021, the mass ratio of 2-tert-butyl-p-cresol to the metal-organic framework material is 1:3 to 7; In step 1022, use an inert gas flow at 100-120°C to heat the mixed solution obtained in step 201 to a constant weight.

[0010] As a further improvement of the present invention, in step 1023, during the reaction, control the pH of the reaction solution within the range of 5-10.

[0011] As a further improvement of the present invention, in step 1024, the temperature in the oven is 130-140°C.

[0012] As a further improvement of the present invention, step 103 specifically includes: Step 1031: Disperse the confined iron nanomaterial in deionized water to obtain a confined iron nanoparticle dispersion; Step 1032: Add ammonium molybdate and thiourea to the confined iron nanoparticle dispersion and stir; Step 1033: Transfer the mixture obtained in Step 1032 to a high-pressure reactor equipped with a polytetrafluoroethylene liner, and place it in an oven for reaction; Step 1034: Centrifuge to collect the precipitate product in the high-pressure reactor in Step 1033. After repeatedly washing the product with deionized water and ethanol solution, place the product in an oven for vacuum drying to obtain the nano-catalytic material.

[0013] As a further improvement of the present invention, in Step 1032, the mass ratio of ammonium molybdate, thiourea, and the confined iron nano-material is 1﹕1~2﹕2~3; In Step 1033, the temperature in the oven is 185~195 °C; In Step 1034, the temperature in the oven is 40~60 °C.

[0014] As a further improvement of the present invention, Step 101 specifically includes: Step 1011: Dissolve cobalt nitrate hexahydrate in a methanol solution to obtain a cobalt nitrate hexahydrate methanol solution; dissolve 2-methylimidazole in a methanol solution to obtain a 2-methylimidazole methanol solution; Step 1012: Drop the cobalt nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution, stir, and then let it stand for aging; Step 1013: Centrifuge to collect the precipitate product obtained in Step 1012. After repeatedly washing the product with an ethanol solution, place it in an oven for drying to obtain a zeolitic imidazolate framework material containing metal Co coordination.

[0015] As a further improvement of the present invention, Step 20 specifically includes: Step 201: Add the powdered nano-catalytic material to deionized water and perform ultrasonic dispersion treatment to obtain a catalytic dispersion; Step 202: Use vacuum filtration to load the catalytic dispersion onto the surface of a polytetrafluoroethylene membrane; Step 203: Place the polytetrafluoroethylene membrane loaded with the catalytic dispersion in an oven for vacuum drying to obtain a catalytic membrane.

[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1)A method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane provided by the present invention prepares a powdered nano-catalytic material into a catalytic membrane, and uses the catalytic membrane to treat reclaimed water. During the treatment process, the catalytic membrane is irradiated. By applying light, the active sites are induced to repair, enhancing the cyclic stability of the catalytic membrane and prolonging the service life of the catalytic membrane; by applying light, a non-radical pathway is added on the basis of the radical pathway, generating diverse oxidation substances, accelerating the catalytic reaction rate, and promoting the effective degradation of sulfamethoxazole.

[0017] (2)The nano-catalytic material prepared by the method of the present invention has a confined structure, which can protect the Fe reaction sites inside the nano-space, reduce the leaching of Fe, thereby reducing the generation of secondary pollutants of iron sludge, reducing the impact on the membrane flux, and maintaining the integrity of the membrane structure; Fe within the confined structure and MoS2 loaded on the surface can enhance the conductivity of the catalytic membrane, which is beneficial to improving the carrier migration rate on the surface of the catalytic membrane. Under light conditions, Mo(IV) can act as a co-catalyst, transfer electrons in the reaction, induce the reduction of the high valence states of Fe(III) and Co(IV) to highly active low valence states, promote the Fe(II) / Fe(III) cycle of the catalyst, prolong the service life of the catalytic membrane, and at the same time reduce the leaching of Fe, thereby reducing the generation of secondary pollutants of iron sludge. The reaction system activates the oxidant by relying on the electron transfer between multivalent transition metals inside the catalytic membrane to generate •SO4 - and •OH to participate in the degradation of pollutants; under light conditions, the catalytic membrane uses its own photocatalytic ability to react with dissolved oxygen in the water environment to generate •O2, and then generates more degradation-selective active 1 O2 through the surface electron transfer mechanism of the catalytic membrane, and forms multiple radical pathways with •SO4- to jointly participate in the degradation of sulfamethoxazole.

[0018] Using the nano-material prepared by the method of the present invention to prepare a catalytic membrane, and under light conditions, the active sites can be restored, maintaining the stability of the catalytic membrane, prolonging the service life of the catalytic membrane, and at the same time reducing the leaching of Fe, thereby reducing the generation of iron sludge; during the reaction, there are both radical pathways and non-radical pathways, providing a faster way to achieve carbon transfer of sulfamethoxazole in reclaimed water and improving the removal effect of sulfamethoxazole. Description of the Drawings

[0019] Figure 1 It is a flow chart of the preparation method of the method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane provided by the present invention; Figure 2 It is a schematic diagram of the synthesis of the nano-catalytic material in the method of the present invention; Figure 3 It is a bar chart of the SMX removal efficiency of Example 1, Comparative Example 1 and Comparative Example 2; Figure 4 Permeability and Fe ion leaching concentration diagrams of the catalytic membranes of Comparative Example 1 and Comparative Example 2; Figure 5 SEM images of the ZFM catalytic membrane before and after the reaction in Comparative Example 1 and Comparative Example 2, where (a) is the SEM image of the ZFM catalytic membrane before and after the reaction in Comparative Example 1, and (b) is the SEM image of the ZFM-OUT catalytic membrane before and after the reaction in Comparative Example 2. Detailed implementation manners

[0020] The technical solutions of the present invention will be described in detail below.

[0021] The present invention provides a method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane, as Figure 1 shown, including the following steps: Step 10, preparing a nano-catalytic material; Step 20, preparing the powdered nano-catalytic material into a catalytic membrane; Step 30, installing the catalytic membrane in a reactor, injecting an oxidant solution into the reactor; conveying the reclaimed water containing sulfamethoxazole to the reactor, and passing it through the catalytic membrane in a circulating flow manner; meanwhile, irradiating the catalytic membrane.

[0022] The method of the present invention uses a catalytic membrane to treat reclaimed water, and irradiates the catalytic membrane during the treatment process. By applying light, the repair of active sites is induced, the cyclic stability of the catalytic membrane is enhanced, and the service life of the catalytic membrane can be extended; by applying light, a non-radical pathway is added on the basis of the radical pathway, generating diverse oxidation substances, accelerating the catalytic reaction rate, and promoting the effective degradation of sulfamethoxazole.

[0023] Preferably, as Figure 2 shown, step 10 specifically includes: Step 101, preparing a metal-organic framework material; Step 102, preparing iron oxide particles inside the metal-organic framework material to obtain a confined iron nano-material; Step 103, vertically growing molybdenum disulfide nanosheets on the surface of the confined iron nano-material to obtain a nano-catalytic material.

[0024] Step 101 specifically includes: Step 1011: Dissolve cobalt nitrate hexahydrate in methanol solution to obtain cobalt nitrate hexahydrate methanol solution; dissolve 2-methylimidazole in methanol solution to obtain 2-methylimidazole methanol solution. The methanol solution serves as the solvent. Preferably, the mass (mg) ratio of cobalt nitrate hexahydrate to the volume (mL) of methanol solution is 15 - 19:1, and the mass (mg) ratio of 2-methylimidazole to the volume (mL) of methanol solution is 13 - 17:1. During preparation, the cobalt nitrate hexahydrate methanol solution and 2-methylimidazole methanol solution have the same volume of methanol solution.

[0025] Step 1012: Drop all of the cobalt nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution, stir, and then let it stand for aging.

[0026] Step 1013: Centrifuge to collect the precipitate obtained in Step 1012, repeatedly wash the product with ethanol solution, and then place it in an oven for drying to obtain a zeolitic imidazolate framework material (ZIF) containing metal Co coordination. Preferably, the temperature in the oven is 40 - 60 °C.

[0027] Preferably, Step 102 specifically includes: Step 1021: Using ether solution as the solvent and 2-tert-butyl-p-cresol as the solute, prepare 2-tert-butyl-p-cresol ether solution, and mix the 2-tert-butyl-p-cresol ether solution with the metal-organic framework material under closed conditions to obtain a mixed solution. During this process, under the action of ether, 2-tert-butyl-p-cresol (tBMP) is introduced into the cavity of the metal-organic framework material, as Figure 2 shown. Preferably, the mass (mg) ratio of 2-tert-butyl-p-cresol to the volume (mL) of ether solution is 5 - 15:1. The mass ratio of 2-tert-butyl-p-cresol to the metal-organic framework material is 1:3 - 7.

[0028] Step 1022: Heat the mixed solution obtained in Step 1021 to a constant weight to remove the ether and tBMP outside the metal-organic framework material.

[0029] Step 1023: Disperse the mixed solution treated in Step 1022 in an aqueous solution of FeCl2·4H2O, and carry out a shaking reaction at room temperature to generate FeO x hydrate inside the metal-organic framework material, as Figure 2 shown. Preferably, the concentration of the FeCl2·4H2O aqueous solution is 15 - 25 mM.

[0030] Step 1024: Centrifuge to collect the precipitate obtained in Step 1023, repeatedly wash the product with ethanol and deionized water to remove the residual organic reagents. Place the product in an oven for aging to obtain the confined iron nanomaterial.

[0031] Preferably, in step 1022, an inert gas stream at 100-120 °C is used to heat the mixed solution obtained in step 1021 to a constant weight. Heating the mixed solution with an inert gas stream isolates oxygen, causing FeCl2·4H2O in the cavity of the metal-organic framework material to be converted to FeO under the action of 2-tert-butyl-p-cresol. x The inert gas stream can be a nitrogen gas stream, an argon gas stream, etc. The temperature of the inert gas stream is in the range of 100-120 °C, which can maintain the structural stability of the metal-organic framework material.

[0032] Preferably, in step 1023, during the reaction, the pH of the reaction solution is controlled within the range of 5-10. Controlling the pH within the range of 5-10 regulates the redox potential, thereby driving the reduction reaction to proceed, which is beneficial to the synthesis of FeO. x .

[0033] Preferably, in step 1024, the temperature in the oven is 130-140 °C, which is convenient for material curing.

[0034] Step 102 in the method of the present invention is based on the differences in redox potential and pH value between compounds. Diethyl ether is used to introduce 2-tert-butyl-p-cresol (tBMP) into the cavity of the metal-organic framework material, thereby preparing FeO x particles inside the metal-organic framework material and synthesizing a nanomaterial with a confined iron structure. FeO x nanoparticles mainly grow inside the pores of the metal-organic framework material rather than aggregating outside the pores. Therefore, they do not hinder the formation of the channels of the catalytic material, ensuring effective mass transfer during the catalytic process. Secondly, the FeO x nanoparticles inside the pores increase the specific surface area in the micropores, providing more adsorption sites for the reactants and promoting the adsorption and reaction of the reactants inside the catalytic material. The confined structure can protect the Fe reaction sites inside the nanospace, reduce the leaching of Fe, thereby reducing the generation of secondary pollutants of iron sludge, reducing the impact on the membrane flux, and maintaining the integrity of the membrane structure.

[0035] Preferably, step 103 specifically includes: Step 1031, dispersing the confined iron nanomaterial in deionized water to obtain a confined iron nanoparticle dispersion. The mass (mg) ratio of the confined iron nanomaterial to the volume (mL) of deionized water is 1.5-1.8:1.

[0036] Step 1032, adding ammonium molybdate and thiourea to the confined iron nanoparticle dispersion and stirring. Preferably, the mass ratio of ammonium molybdate, thiourea, and the confined iron nanomaterial is 1:1-2:2-3.

[0037] Step 1033: Transfer the mixture obtained in Step 1032 to a high-pressure reactor equipped with a polytetrafluoroethylene liner, and place the high-pressure reactor in an oven for reaction.

[0038] Step 1034: Centrifuge to collect the precipitate product in the high-pressure reactor in Step 1033. After repeatedly washing the product with deionized water and ethanol, place the product in an oven for vacuum drying to obtain the nano-catalytic material.

[0039] Preferably, in Step 1033, the temperature in the oven is 185 - 195 °C. Too low a temperature is likely to result in overly thick MoS2 nanosheet morphology, affecting the photoelectric conversion efficiency, while too high a temperature will cause the MoS2 nanosheet morphology to break. Reacting within the above temperature range can ensure the successful formation of MoS2 nanosheets.

[0040] Preferably, in Step 1033, the reaction time is 9 - 24 hours. A shorter reaction time may only form simple structures such as nanosheets or nanorods, and as the reaction time extends, these nanosheets will gradually assemble into a flower-like structure. However, too long a reaction time will affect the stability of the confined iron nano-material.

[0041] Preferably, in Step 1034, the temperature in the oven is 40 - 60 °C.

[0042] Step 103 in the method of the present invention, as Figure 2 shown, adopts the hydrothermal method. By controlling the reaction temperature, reaction time, and the mass ratio of reactants, MoS2 nanosheets are vertically grown on the surface of the confined iron nano-material. The active sites of MoS2 are mostly concentrated on the edges of the nanosheets. This vertical growth mode can maximize the exposure of the edge active sites of MoS2, which is beneficial to the occurrence of catalytic reactions. Under light conditions, Mo(IV) can act as a co-catalyst, transfer electrons in the reaction, induce the reduction of the high valence states of Fe(III) and Co(IV) to highly active low valence states, promote the Fe(II) / Fe(III) cycle of the catalyst, can extend the service life of the catalytic membrane, and at the same time reduce the leaching of Fe, thereby reducing the generation of secondary pollutants of iron sludge.

[0043] The nanocatalytic material prepared in the method of the present invention has a confined structure. When the catalytic membrane is made into a reaction, the confined structure can protect the Fe reaction site inside the nano space, reduce the leaching of Fe, thereby reducing the generation of secondary pollutants such as iron mud, reducing the impact on the membrane flux, and maintaining the integrity of the membrane structure. At the same time, most natural organic matter is excluded from the reaction space, reducing the interference of competitive adsorption of coexisting substances near the active site, thereby providing a more superior catalytic environment for sulfamethoxazole, having excellent anti-interference ability under complex water quality matrices, and improving reaction activity. The Fe in the confined structure and the surface-loaded MoS2 can enhance the conductivity of the catalytic membrane, which is beneficial to improving the carrier migration rate on the surface of the catalytic membrane and improving the activity of the catalytic membrane. At the same time, under light conditions, Mo(IV) can act as a co-catalyst to transfer electrons in the reaction, induce the high-valence state of Fe(III) and Co(IV) to be reduced to a highly active low-valence state, and promote the Fe(II)-Fe(III) cycle of the catalyst: Mo 4+ +Fe 3+ →Mo 5+ +Fe 2+ The nanomaterial prepared in the method of the present invention is used to prepare a catalytic film, and under light conditions, the active sites can be restored, the stability of the catalytic film is maintained, the service life of the catalytic film is extended, and the leaching of Fe is reduced, thereby reducing the generation of iron mud.

[0044] The electron transfer between multivalent transition metals in the catalytic membrane activates the oxidant to produce SO4 - and •OH participate in the degradation of pollutants: e metal - +HSO5 - →•SO4 - +OH - , e metal - +HSO5 - →SO4 2- +•OH. Under light conditions, the catalytic film uses its own photocatalytic ability to react with dissolved oxygen in the water environment to generate •O2:e CB - +O2→•O2, and then generate more selective degradation active 1 O2: •O2+•OH→ 1 O2+ OH - , and with •SO4 - Composed of multiple free radical pathways, jointly involved in the degradation of sulfamethoxazole: 1 O2 / •SO4 -+SMX → H2O + CO2. The catalytic membrane is prepared using the nanomaterials prepared by the method of the present invention. Under light conditions, during the reaction, there are both free radical pathways and non-free radical pathways, providing a faster pathway for carbon transfer of sulfamethoxazole in reclaimed water and improving the removal effect of sulfamethoxazole.

[0045] Preferably, step 20 specifically includes: Step 201, adding the powdered nano-catalytic material into deionized water and performing ultrasonic dispersion treatment to obtain a catalytic dispersion.

[0046] Step 202, using vacuum filtration to load the catalytic dispersion onto the surface of a polytetrafluoroethylene membrane.

[0047] Step 203, placing the polytetrafluoroethylene membrane loaded with the catalytic dispersion in an oven for vacuum drying to obtain a catalytic membrane. Preferably, the operating temperature of the oven is 20 - 30 °C. Three examples and two comparative examples are provided below to verify the performance of the method of the present invention.

[0048] In the following examples and comparative examples, the methanol solution used is anhydrous methanol, the ethanol solution used is anhydrous ethanol, and the ether solution used is anhydrous ether.

[0049] Example 1 Step 1, preparing a zeolitic imidazolate framework material (abbreviated as ZIF) containing metal Co coordination Dissolve 837 mg of cobalt nitrate hexahydrate in 50 mL of methanol solution to obtain a cobalt nitrate hexahydrate methanol solution. Dissolve 730 mg of 2-methylimidazole in 50 mL of methanol solution to obtain a 2-methylimidazole methanol solution.

[0050] Drop the cobalt nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution, stir for 5 minutes, and then let it stand for 24 h for aging precipitation. Centrifuge to collect the precipitate product, repeatedly wash it with ethanol solution to remove the residual organic reagents on the surface, and place it in an oven at 60 °C for drying for 12 h to obtain the purple product ZIF.

[0051] Step 2, preparing a nanomaterial ZIF-FeO with a confined structure x (abbreviated as ZF) 10 mg of 2-tert-butyl-p-cresol was added to 1 mL of an ether solution to prepare a 2-tert-butyl-p-cresol ether solution tBMP / DE. Under closed conditions, the 2-tert-butyl-p-cresol ether solution was mixed with 50 mg of ZIF, and the mixed solution was heated to a constant weight in a nitrogen stream at 120 °C. The treated mixed solution tBMP@ZIF was dispersed in an excessive amount of an aqueous solution of FeCl2·4H2O with a concentration of 20 mM, and the reaction was shaken at room temperature for 4 h, and the pH was 8 during the reaction. The product was collected by centrifugation, and the residual organic reagents were removed by repeated washing with an ethanol solution and deionized water, and then aged in an oven at 140 °C for 2 h to obtain ZF.

[0052] Step 3: Preparation of the catalytic material ZIF-FeO x @ MoS2 (abbreviation: ZFM) 50 mg of ZF was added to 30 mL of deionized water to obtain a ZF nanoparticle dispersion. 20 mg of ammonium molybdate and 34.5 mg of thiourea were added to the ZF nanoparticle dispersion and stirred for 30 min. The mixed solution was transferred to a high-pressure reaction kettle equipped with a 100 ml polytetrafluoroethylene liner and placed in an oven at 190 °C for reaction for 15 h. After the reaction was completed, the precipitate product was collected by centrifugation, and the surface residual organic reagents were removed by repeated washing with deionized water and an ethanol solution. The obtained product was placed in an oven at 60 °C for vacuum drying for 6 h to obtain a black nanomaterial ZFM.

[0053] Step 4: Preparation of the ZFM catalytic membrane 50 mg of powdered ZFM was added to 50 mL of deionized water and subjected to ultrasonic dispersion treatment for 10 h. 15 mL of the ZFM dispersion was loaded onto the surface of a PTFE membrane with a diameter of 10 cm by vacuum filtration. The membrane was placed in an oven at 25 °C for vacuum drying for 24 h to obtain a ZFM catalytic membrane, and the effective diameter of the material on the membrane was 9 cm.

[0054] Step 5: Treatment of reclaimed water The ZFM catalytic membrane was installed in a reactor, and a solution of peroxymonosulfate (PMS) with a mass concentration of 0.5 mM was injected into the reactor. Reclaimed water with a sulfamethoxazole (SMX) mass concentration of 0.1 mg / L was transported to the reactor and passed through the catalytic membrane in a circulating flow manner, and the catalytic membrane was irradiated. Example 2 Step 1: Preparation of a zeolitic imidazolate framework material containing metal Co coordination (abbreviation: ZIF) 750 mg of cobalt nitrate hexahydrate was dissolved in 50 mL of a methanol solution to prepare a cobalt nitrate hexahydrate methanol solution. 650 mg of 2-methylimidazole was dissolved in 50 mL of a methanol solution to prepare a 2-methylimidazole methanol solution.

[0055] The cobalt nitrate hexahydrate methanol solution was dropped into the 2-methylimidazole methanol solution. After stirring for 5 minutes, it was left standing for 24 h for aging precipitation. The precipitate product was collected by centrifugation, and the residual organic reagents on the surface were removed by repeated washing with ethanol solution. It was placed in an oven at 40 °C and dried for 12 h to obtain the purple product ZIF.

[0056] Step 2: Preparation of the nanomaterial ZIF-FeO with a confined structure x (abbreviation: ZF) 5 mg of 2-tert-butyl-p-cresol was added to 1 mL of ether solution to prepare the 2-tert-butyl-p-cresol ether solution tBMP / DE. Under closed conditions, the 2-tert-butyl-p-cresol ether solution was mixed with 15 mg of ZIF, and the mixed solution was heated to a constant weight in an argon stream at 100 °C. The treated mixed solution tBMP@ZIF was dispersed in an excess of an aqueous solution of FeCl2·4H2O with a concentration of 15 mM, and the reaction was shaken at room temperature for 4 h, and the pH during the reaction was 5. The product was collected by centrifugation, and the residual organic reagents were removed by repeated washing with ethanol solution and deionized water. It was placed in an oven at 130 °C and aged for 2 h to obtain ZF.

[0057] Step 3: Preparation of the catalytic material ZIF-FeO x @MoS2 (abbreviation: ZFM) 45 mg of ZF was added to 30 mL of deionized water to obtain a ZF nanoparticle dispersion. 27.5 mg of ammonium molybdate and 27.5 mg of thiourea were added to the ZF nanoparticle dispersion and stirred for 30 min. The mixed solution was transferred to a high-pressure reactor equipped with a 100 ml polytetrafluoroethylene liner and placed in an oven at 185 °C for reaction for 9 h. After the reaction was completed, the precipitate product was collected by centrifugation, and the residual organic reagents on the surface were removed by repeated washing with deionized water and ethanol solution. The obtained product was placed in an oven at 40 °C and vacuum-dried for 6 h to obtain the black nanomaterial ZFM.

[0058] Step 4: Preparation of the ZFM catalytic membrane 50 mg of powdered ZFM was added to 50 mL of deionized water and subjected to ultrasonic dispersion treatment for 10 h. 15 mL of the ZFM dispersion was loaded onto the surface of a PTFE membrane with a diameter of 10 cm by vacuum filtration. The membrane was placed in an oven at 25 °C and vacuum-dried for 24 h to obtain the ZFM catalytic membrane, and the effective diameter of the material on the membrane was 9 cm.

[0059] Step 5: Treatment of reclaimed water Install the ZFM catalytic membrane in the reactor, and inject a peroxymonosulfate (PMS) solution with a mass concentration of 0.5 mM into the reactor. Deliver the reclaimed water with a sulfamethoxazole (SMX) mass concentration of 0.1 mg / L to the reactor, and let it flow through the catalytic membrane in a circulating manner and irradiate the catalytic membrane. Example 3 Step 1: Prepare a zeolitic imidazolate framework material coordinated with metal Co (abbreviation: ZIF) Dissolve 950 mg of cobalt nitrate hexahydrate in 50 mL of methanol solution to obtain a cobalt nitrate hexahydrate methanol solution. Dissolve 850 mg of 2-methylimidazole in 50 mL of methanol solution to obtain a 2-methylimidazole methanol solution.

[0060] Drop the cobalt nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution. After stirring for 5 minutes, let it stand for 24 h for aging precipitation. Centrifuge to collect the precipitate product, repeatedly wash it with ethanol solution to remove the residual organic reagents on the surface, and place it in an oven at 50 °C for drying for 12 h to obtain the purple product ZIF.

[0061] Step 2: Prepare a nanomaterial ZIF-FeO with a confined structure x (abbreviation: ZF) Add 15 mg of 2-tert-butyl-p-cresol to 1 mL of ether solution to prepare a 2-tert-butyl-p-cresol ether solution tBMP / DE. Under airtight conditions, mix the 2-tert-butyl-p-cresol ether solution with 105 mg of ZIF, and heat the mixed solution to a constant weight in a nitrogen stream at 110 °C. Disperse the treated mixed solution tBMP@ZIF in an excessive aqueous solution of FeCl2·4H2O with a concentration of 25 mM, and shake and react at room temperature for 4 h, with the pH being 10 during the reaction. Centrifuge to collect the product, and repeatedly wash it with ethanol solution and deionized water to remove the residual organic reagents, and place it in an oven at 130 °C for aging for 2 h to obtain ZF.

[0062] Step 3: Prepare a catalytic material ZIF-FeO x @ MoS2 (abbreviation: ZFM) Add 54 mg of ZF to 30 mL of deionized water to obtain a ZF nanoparticle dispersion. Add 19 mg of ammonium molybdate and 38 mg of thiourea to the ZF nanoparticle dispersion, and stir for 30 min. Transfer the mixed solution to a high-pressure reactor equipped with a 100 ml polytetrafluoroethylene liner, and place it in an oven at 195 °C for reaction for 24 h. After the reaction is completed, centrifuge to collect the precipitate product, and repeatedly wash it with deionized water and ethanol solution to remove the residual organic reagents on the surface. Place the obtained product in an oven at 50 °C for vacuum drying for 6 h to obtain the black nanomaterial ZFM.

[0063] Step 4, Preparation of ZFM catalytic membrane Add 50 mg of powdered ZFM into 50 mL of deionized water and perform ultrasonic dispersion treatment for 10 h. Load 15 mL of the ZFM dispersion onto the surface of a PTFE membrane with a diameter of 10 cm by vacuum filtration. Place the membrane in an oven at 25 °C and dry it under vacuum for 24 h to obtain the ZFM catalytic membrane, and the effective diameter of the material on the membrane is 9 cm.

[0064] Step 5, Treatment of reclaimed water Install the ZFM catalytic membrane in the reactor and inject a peroxymonosulfate (PMS) solution with a mass concentration of 0.5 mM into the reactor. Feed the reclaimed water with a sulfamethoxazole (SMX) mass concentration of 0.1 mg / L into the reactor, and let it flow through the catalytic membrane in a circulating manner and irradiate the catalytic membrane. Comparative Example 1 Same as Example 1, except that the catalytic membrane is not irradiated in Step 5. Comparative Example 2 Step 1, Preparation of ZIF. The same as Step 1 of Example 1 to obtain ZIF.

[0065] Step 2, Preparation of the nanomaterial ZF-OUT without a confinement structure. Replace the ether solution in Step 2 of Example 1 with deionized water, and the rest remains the same to obtain ZF-OUT.

[0066] Step 3, Preparation of the catalytic material ZFM-OUT. Replace ZF in Step 3 of Example 1 with ZF-OUT, and the rest remains the same to obtain ZFM-OUT.

[0067] Step 4, Preparation of the ZFM-OUT catalytic membrane. Replace ZFM in Step 4 of Example 1 with ZFM-OUT, and the rest remains the same to obtain the ZFM-OUT catalytic membrane.

[0068] Step 5, Treatment of reclaimed water. Replace the ZFM catalytic membrane in Step 5 of Example 1 with the ZFM-OUT catalytic membrane, and do not irradiate the catalytic membrane, and the rest remains the same. In Example 1, Comparative Example 1 and Comparative Example 2, the concentration of SMX in the water was detected using high performance liquid chromatography (HPLC, 1290, Aglient) at different reaction times, so as to obtain the removal efficiency of SMX, as Figure 3 . The permeation performance of the membrane module was tested at different reaction times, and the amount of Fe element in the effluent was quantitatively analyzed using inductively coupled plasma optical emission spectrometer (ICP-OES), as Figure 4。The ZFM catalytic membrane before use in Comparative Example 1, the ZFM catalytic membrane after 6 hours of reaction, the ZF-OUT catalytic membrane before use in Comparative Example 2, and the ZFM-OUT catalytic membrane after 6 hours of reaction were scanned using a scanning electron microscope (SEM, S-4800, Hitachi) to obtain their surface morphologies, as Figure 5 。

[0069] From Figure 3 It can be seen that after 5 cycles, also under dark conditions, the SMX removal efficiencies of the ZFM catalytic membrane and the ZFM-OUT catalytic membrane reached 59% and 31% respectively. The differences in the degradation efficiency and catalytic stability between the two are mainly attributed to the different reaction activities and catalytic environments of the active iron sites within the nano-space of the ZFM catalytic material and the iron sites exposed outside the ZFM-OUT. It can be concluded that the confined structure of the ZFM catalytic material enhances the utilization efficiency of reactive oxygen species (ROS) by shortening the mass transfer distance between pollutants and internal active sites, thus significantly improving the catalytic reaction efficiency. After 5 cycles, the SMX removal efficiency of the ZFM catalytic membrane under light still remained above 95%, higher than that of the ZFM catalytic membrane under dark conditions for SMX removal. It can be concluded that the stimulation of light not only accelerates the catalytic reaction rate, promotes the effective degradation of pollutants, but also enhances the cyclic stability of the catalyst.

[0070] From Figure 4 It can be seen that in Comparative Example 2 (i.e., using the ZFM-OUT catalytic membrane under dark conditions), the leaching concentration of dissolved Fe ions was approximately 100 μg / L, while in Comparative Example 1 (i.e., using the ZFM catalytic membrane under dark conditions), the leaching concentration of dissolved Fe ions was less than 10 μg / L. It can be seen that the effective protection of FeOx within the metal-organic framework by the nano-space in the ZFM catalytic membrane effectively inhibited the dissolution of Fe. Moreover, the permeation of the ZFM catalytic membrane decreased by 12.7%, while the permeation of the ZFM-OUT catalytic membrane decreased by 34.7%.

[0071] After continuous reaction for 6 hours, the surface of the ZFM catalytic membrane still remained black, while dark red flocculent substances appeared on the surface of the ZFM-OUT catalytic membrane. The catalytic membrane after the reaction was detected using ICP-OES, and the results showed that the red substances were mainly iron mud composed of iron and oxygen elements. It can be seen that another reason for the significant reduction in the catalytic efficiency of the ZFM-OUT is that the dissolved iron ions react with inorganic ions and natural organic matter in the wastewater to form iron mud, which deposits on the surface of the catalytic membrane, reducing the flux of the catalytic membrane and hindering the mass transfer efficiency of substances in the reactor. The above results confirm that the confined structure of the ZFM catalytic membrane, whose nano-confinement effect promotes the protection of the metal-organic framework for the confined FeOx nanoparticles, reduces the leaching of iron ions and maintains the integrity of the membrane structure.

[0072] From Figure 5 (b), it can be seen that the fragments of the ZFM-OUT catalytic membrane increased significantly after the reaction. From Figure 5 (a), it can be seen that the ZFM catalytic membrane maintained its structural integrity.

[0073] Free radical quenching experiments were conducted to evaluate the types of free radicals generated by the ZFM catalytic material under dark conditions and the ZFM catalytic material under light conditions. Since the reaction rate constants of •SO4- and •OH are similar, methanol solution was used as a general quenching agent. At the same time, tert-butanol (TBA) was usually used as an •OH scavenger, benzoquinone (BQ) was used as an •O2- quenching agent, and furfuryl alcohol (FFA) was used to quench 1O2. Under dark reaction conditions, the methanol solution had a strong inhibitory effect on the degradation of SMX, while the inhibitory effect of TBA was weak. This indicates that there is only one reactive oxygen species, •SO4-, in the ZFM catalytic material under dark conditions. In contrast, under light conditions, the addition of FFA and BQ significantly inhibited the degradation of SMX, while the presence of methanol solution had only a slight inhibitory effect. This indicates that there are multiple free radical redox pathways composed of 1O2, •O2- and •SO4- acting together in the ZFM catalytic material under light conditions, promoting its efficient degradation of SMX under light conditions.

[0074] XPS was used to analyze the changes in the oxidation states of metal elements (Fe, Mo, Co) in the catalytic material before and after the reaction. Under dark reaction conditions, the metal elements mainly underwent a transformation from low valence states to high valence states. Before the reaction, Fe(II) was dominant (70%) in ZFM, and after the dark reaction, it was largely converted to Fe(III), resulting in a decrease in the Fe(II) / Fe(III) ratio from 1.78 to 0.37. At the same time, a small amount of Co(III) was also observed to transform into the high valence state Co(IV). However, under light conditions, the ratio of Fe(II) / Fe(III) recovered to 0.86, which is 2.3 times that of the dark reaction system. In the photosystem, Mo(IV) was transformed into the high valence states of Mo(V) and Mo(VI), indicating that Mo(IV) can act as a co-catalyst, transfer electrons in the reaction, and induce the reduction of the high valence states of Fe(III) and Co(IV) to highly active low valence states.

[0075] Through the above experiments, it can be verified that the catalytic membrane is prepared by using the nanomaterials prepared by the method of the present invention, and under light conditions, the active sites of the catalytic membrane can be restored, maintaining the stability of the catalytic membrane, extending the service life of the catalytic membrane, while reducing the leaching of Fe, thereby reducing the generation of iron sludge; during the reaction, there are both free radical pathways and non-free radical pathways, providing a faster way for the carbon transfer of sulfamethoxazole in reclaimed water and improving the removal effect of sulfamethoxazole.

[0076] The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited by the above specific embodiments, and the above specific embodiments and the descriptions in the specification are only for further explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, various changes and improvements will still occur to the present invention, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A treatment method for sulfamethoxazole in reclaimed water based on a catalytic membrane, characterized in that, It includes the following steps: Step 10, preparing a nano-catalytic material; Step 20, preparing a catalytic membrane from the powdered nano-catalytic material; Step 30, installing the catalytic membrane in a reactor, injecting an oxidant solution into the reactor; conveying the reclaimed water containing sulfamethoxazole to the reactor, and passing it through the catalytic membrane in a circulating flow manner; meanwhile, irradiating the catalytic membrane with light.

2. The method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 1, wherein The specific steps of Step 10 include: Step 101, preparing a metal-organic framework material; Step 102, preparing iron oxide particles inside the metal-organic framework material to obtain a confined iron nano-material; Step 103, vertically growing molybdenum disulfide nanosheets on the surface of the confined iron nano-material to obtain a nano-catalytic material.

3. The treatment method of sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 2, wherein, The specific steps of Step 102 include: Step 1021, using an ether solution as a solvent and 2-tert-butyl-p-cresol as a solute to prepare a 2-tert-butyl-p-cresol ether solution, and mixing the 2-tert-butyl-p-cresol ether solution with the metal-organic framework material under closed conditions to obtain a mixed solution; Step 1022, heating the mixed solution obtained in Step 1021 to a constant weight; Step 1023, dispersing the mixed solution treated in Step 1022 in an aqueous solution of FeCl2·4H2O and performing a shaking reaction at room temperature; Step 1024, centrifuging to collect the precipitate obtained in Step 1023, repeatedly washing the product with an ethanol solution and deionized water, and then aging the product in an oven to obtain a confined iron nano-material.

4. The method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 3, characterized in that, In Step 1021, the mass ratio of 2-tert-butyl-p-cresol to the metal-organic framework material is 1﹕3 - 7; In Step 1022, the mixed solution obtained in Step 201 is heated to a constant weight using an inert gas flow at 100 - 120°C.

5. The method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 3, wherein In Step 1023, during the reaction, the pH of the reaction solution is controlled within the range of 5 - 10.

6. The treatment method of sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 3, wherein, In Step 1024, the temperature in the oven is 130 - 140°C.

7. The treatment method of sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 2, wherein The specific steps of Step 103 include: Step 1031, dispersing the confined iron nano-material in deionized water to obtain a confined iron nano-particle dispersion; Step 1032, adding ammonium molybdate and thiourea to the confined iron nano-particle dispersion and stirring; Step 1033, transferring the mixed solution obtained in Step 1032 to a high-pressure reaction kettle equipped with a polytetrafluoroethylene liner and placing it in an oven for reaction; Step 1034, centrifuging to collect the precipitate in the high-pressure reaction kettle in Step 1033, repeatedly washing the product with deionized water and an ethanol solution, and then vacuum drying the product in an oven to obtain a nano-catalytic material.

8. The method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 7, wherein In Step 1032, the mass ratio of ammonium molybdate, thiourea, and the confined iron nano-material is 1﹕1 - 2﹕2 - 3; In Step 1033, the temperature in the oven is 185 - 195°C; In Step 1034, the temperature in the oven is 40 - 60°C.

9. The method for treating sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 2, wherein The specific steps of Step 101 include: Step 1011, dissolving cobalt nitrate hexahydrate in a methanol solution to obtain a cobalt nitrate hexahydrate methanol solution; dissolving 2-methylimidazole in a methanol solution to obtain a 2-methylimidazole methanol solution; Step 1012: Drop the cobalt nitrate hexahydrate methanol solution into the 2-methylimidazole methanol solution, stir, and then let it stand for aging. Step 1013: Centrifuge to collect the precipitate product obtained in Step 1012. After repeatedly washing the product with an ethanol solution, dry it in an oven to obtain a zeolitic imidazolate framework material containing metal Co coordination.

10. The treatment method of sulfamethoxazole in reclaimed water based on a catalytic membrane according to claim 1, characterized in that, The specific steps of Step 20 include: Step 201: Add the powdered nano-catalytic material into deionized water and perform ultrasonic dispersion treatment to obtain a catalytic dispersion. Step 202: Use vacuum filtration to load the catalytic dispersion onto the surface of a polytetrafluoroethylene membrane. Step 203: Place the polytetrafluoroethylene membrane loaded with the catalytic dispersion in an oven for vacuum drying to obtain a catalytic membrane.

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