Preparation method of Ag2MoO4 / polyimide composite material and its low-power LED photodegradation of tetracycline wastewater

Abstract

The present invention provides a method for preparing a novel composite photocatalyst material and a method for efficiently degrading tetracycline. The method primarily involves combining two materials via a hydrothermal method to produce a highly efficient composite material for treating tetracycline hydrochloride in antibiotic wastewater. Specifically, the composite material for treating tetracycline-like substances in wastewater is added to the wastewater for treatment. The process of the present invention has the advantages of being simple and easy to control, convenient to operate, low in cost, readily available raw materials, and excellent degradation performance. The present invention exhibits excellent degradation performance for tetracycline hydrochloride in antibiotic wastewater and holds significant application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of composite materials and degradation of tetracycline wastewater, and particularly relates to a preparation method of the composite material, a composite material for treating tetracycline substances in wastewater, and a treatment method. Background Art

[0002] The molecular formula of tetracycline hydrochloride (TC) is C 22 H 25 ClN2O8 is a broad-spectrum antibiotic. TC can inhibit the growth of bacteria and even directly kill certain bacteria, thereby destroying the balance of bacterial flora in the environment. TC residues can also induce drug resistance in certain microorganisms, leading to the enrichment of drug-resistant bacteria and the production of drug-resistant genes. Therefore, the degradation of TC in wastewater is of great significance and is conducive to sustainable development. At present, the main methods for removing tetracycline antibiotics include activated sludge method, adsorption method, deep oxidation method, photolysis / photooxidation method, etc. Due to the biological activity, polarity and persistence of antibiotics, most biological processes and advanced oxidation treatments are not sufficient to degrade and mineralize them. Photodegradation has great advantages, but current photocatalytic degradation materials have certain limitations.

[0003] The principle of photocatalysis is based on the redox ability of photogenerated holes and electron pairs generated by photocatalysts under light conditions, which can achieve the purpose of purifying pollutants, synthesizing and converting substances. However, the biggest challenge in the practical application of photocatalytic technology is the need to develop an efficient, low-cost and harmless photocatalyst. At present, photocatalysts such as TiO2, ZnO, and bismuth oxyhalide BiOX (X = Cl, Br, I) have achieved certain results in water treatment, but most photocatalysts are susceptible to photocorrosion during the degradation of pollutants, which may affect their stability and photocatalytic activity. In addition, due to the rapid recombination of photogenerated electrons and holes, the photocatalytic activity is poor.

[0004] Polyimide (PI) is a class of polymers containing an imide ring (-CO-N-CO-) in its backbone. It is one of the most promising organic polymer materials due to its suitable band gap (2.05-2.8 eV), strong chemical inertness, stable aromatic heterocyclic structural units, and abundant raw material resources. In the field of photocatalysis, PI was primarily used as a catalyst support until Chu et al. proposed crystalline PI as a new polymer photocatalyst in 2012. However, pure PI suffers from low light energy utilization, insufficient oxidation capacity due to its high negative valence band position, and significant photocarrier contamination. Therefore, the development of Ag2MoO4 / PI composites for efficient TC degradation is of both academic and practical significance. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: to address the problems in the prior art of low-power LED photodegradable materials such as poor selectivity, low degradation efficiency, complex preparation process, low reuse rate, and environmental pollution, and to provide a method for preparing a composite material with high selectivity, high degradation efficiency, abundant and readily available raw materials, simple preparation method, and environmental friendliness, for treating tetracycline in wastewater.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: a method for preparing a composite low-power LED photodegradable material, comprising the following steps:

[0007] 1. Preparation method of Ag2MoO4 / PI composite material (Ag2MoO4 is abbreviated as AMO)

[0008] 1) Using diamine (melamine) and dianhydride (pyromellitic anhydride) as raw materials, grind and mix them thoroughly in a mortar, and transfer the mixed powder into a crucible;

[0009] 2) placing the crucible of step 1) in a muffle furnace and calcining the temperature to 325° C. at a heating rate of 7° C. / min and maintaining the temperature for 4 h to obtain a calcined material;

[0010] 3) Grinding the material obtained in step 2) and uniformly dispersing the ground material in deionized water and sonicating for 2 hours, then washing it several times with deionized water and anhydrous ethanol, respectively, and finally drying it in an electric blast drying oven at 60° C. for several hours to grind it uniformly, and obtaining a powdered material, PI;

[0011] 4) using the PI obtained in step 3) as raw materials, silver sulfate, and sodium molybdate, the raw materials are mixed to prepare a mixed solution;

[0012] 5) The mixed solution obtained in step 4) was transferred into a 150 ml polytetrafluoroethylene autoclave, kept in an oven at 110-190° C. for 12-24 hours, and naturally cooled to room temperature to obtain a hydrothermal material;

[0013] 6) The hydrothermal material obtained in step 5) was centrifuged, washed several times with deionized water and anhydrous ethanol, dried in an electric blast drying oven at 60° C. for several hours, and ground uniformly to obtain an AMO / PI composite material.

[0014] Polyimide (PI) is primarily used in aerospace, microelectronics, and photoelectrochemistry, but is rarely used in photocatalytic research. PI exhibits excellent photocatalytic performance under ultraviolet light but little to no photocatalytic activity under visible light. Therefore, modifying PI to enhance its photocatalytic performance under visible light is of great research interest. Silver molybdate (Ag2MoO4) has a suitable band gap, ranging from 3.14 to 3.57 eV. Currently, most research on molybdates in photocatalysis focuses on materials such as bismuth molybdate, iron molybdate, and silver molybdate. Silver molybdate, with its advantages of simple preparation, high chemical activity, narrow spectral response, and efficient separation of photogenerated carriers, has garnered significant attention as a photocatalytic material for the degradation of environmental pollutants. Currently, there are no studies using PI and AMO to prepare composite degradation materials, and no prior art research demonstrates that PI and AMO can be used together as raw materials to produce composite degradation materials with excellent degradation performance.

[0015] Furthermore, the molar ratio of the raw materials melamine and pyromellitic anhydride in step 1) is 1: 1. The performance of the materials prepared with other molar ratios is not as good as the PI prepared with the 1:1 ratio.

[0016] Furthermore, in step 4), the mass of PI is 2.253 g, and the molar ratio of silver molybdate to sodium molybdate is 1:1. The catalyst prepared using this ratio has better degradation performance for tetracycline hydrochloride, reaching more than 80% within 150 minutes.

[0017] A method for treating tetracycline hydrochloride in wastewater comprises: adding a composite material for treating tetracycline hydrochloride in wastewater into the wastewater, treating the wastewater in darkness for 40 to 60 minutes, and then irradiating the wastewater with low-power LED visible light for photodegradation for 150 to 240 minutes; wherein the mass-to-volume ratio of the composite degradation material to the wastewater is 0.1 to 1.0 g:1000 mL; degrading the tetracycline hydrochloride in the wastewater according to this treatment method ensures a good degradation treatment effect, shortens the treatment time, and reduces the irradiation intensity, thereby having good market prospects.

[0018] As an optimization, the mass volume ratio of the composite material to wastewater was 0.5 g:1000 mL, and the dark treatment time was 40 min. Under such treatment conditions, the degradation effect was the best.

[0019] Compared with the existing technology, the present invention has the following beneficial effects: The method of the present invention breaks through the existing technology of preparing composite materials with silver molybdate and oxides, metal organic frameworks, silver halides, etc. PI materials, as conventional materials used in the industrial field, have good mechanical and electrical properties. Based on the respective advantages of PI and AMO, a composite material with excellent low-power LED photodegradation performance was prepared by a hydrothermal method. The composite material adsorbed and degraded tetracycline hydrochloride in wastewater by more than 80.57%. The method of the present invention has a simple preparation process, is easy to operate and has a short treatment time when used for wastewater treatment, and has good prospects for industrial production and market application. Implementation Method

[0020] The present invention is further described in detail below with reference to specific examples. This embodiment is carried out based on the technology of the present invention, and detailed implementation methods and specific operation processes are now given to illustrate the creativity of the present invention, but the scope of protection of the present invention is not limited to the following examples. Example

[0021] A method for preparing a composite degradable material comprises the following steps:

[0022] 1) Using diamine (melamine) and dianhydride (pyromellitic anhydride) as raw materials, take 2.520g of melamine and 4.360g of pyromellitic anhydride respectively, grind them thoroughly in a mortar and mix them evenly, and transfer the mixed powder to a crucible;

[0023] 2) placing the crucible of step 1) in a muffle furnace and calcining the temperature to 325° C. at a heating rate of 7° C. / min and maintaining the temperature for 4 h to obtain a calcined material;

[0024] 3) Grinding the material obtained in step 2) and uniformly dispersing the ground material in deionized water and sonicating for 2 hours, then washing it several times with deionized water and anhydrous ethanol, respectively, and finally drying it in an electric blast drying oven at 60° C. for several hours to grind it uniformly, and obtaining a powdered material, PI;

[0025] 4) Dispersing 0.624 g of silver sulfate and 1.127 g of the PI prepared in step 2) in 50 ml of deionized water, and stirring magnetically for 30 minutes to obtain a mixed solution A;

[0026] 5) Disperse 0.484 g of sodium molybdate in deionized water and dissolve it completely to obtain solution B;

[0027] 6) adding the solution B obtained in step 5) dropwise to the mixed solution A obtained in step 4) to obtain a mixed solution;

[0028] 7) The mixed solution obtained in step 6) was transferred into a 150 ml polytetrafluoroethylene autoclave, kept in an oven at 180° C. for 16 h, and naturally cooled to room temperature to obtain a hydrothermal material;

[0029] 8) The hydrothermal material obtained in step 7) was centrifuged, washed several times with deionized water and anhydrous ethanol, dried in an electric blast drying oven at 60° C. for several hours, and ground uniformly to obtain an AMO / PI composite material.

[0030] This embodiment also provides a low-power LED photocatalytic degradation material for treating tetracycline hydrochloride in wastewater, the component of which is the composite material prepared by the method described in this embodiment.

[0031] The composite material was added to a 20 mg / L tetracycline hydrochloride solution, with a mass volume ratio of the composite material to the tetracycline hydrochloride solution of 0.5 g:1000 mL. The tetracycline hydrochloride solution was treated in the dark at 25°C for 40 minutes and then irradiated with visible light for 150 minutes for photodegradation. The results showed that the degradation efficiency of tetracycline hydrochloride using this treatment method could reach 73.28%.

[0032] Example 2:

[0033] In this embodiment, except that the mass of PI in step 4) is modified to 2.253 g, the rest is the same as in Example 1.

[0034] This embodiment also provides a low-power LED photocatalytic degradation material for treating tetracycline hydrochloride in wastewater, the component of which is the composite material prepared by the method described in this embodiment.

[0035] The composite material was added to a 20 mg / L tetracycline hydrochloride solution at a mass volume ratio of 0.5 g to 1000 mL. The tetracycline hydrochloride solution was treated in the dark at 25°C for 40 minutes and then irradiated with visible light for 150 minutes for photodegradation. The results showed that the degradation efficiency of tetracycline hydrochloride could reach 80.57% using this treatment method. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 X-ray diffraction (XRD) patterns of PI, AMO, and AMO / PI composite materials of various ratios synthesized by the method of the present invention;

[0037] Figure 2 SEM spectra of PI, AMO, and AMO / PI prepared by the method of the present invention;

[0038] Figure 3 This is a graph showing the degradation of tetracycline hydrochloride by PI, AMO, and AMO / PI composite materials prepared by the method of the present invention.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a composite low-power LED photodegradable material, comprising the following steps: 1) Using melamine and pyromellitic anhydride as raw materials, grind and mix them thoroughly in a mortar, and transfer the mixed powder into a crucible; 2) placing the crucible of step 1) in a muffle furnace and calcining the temperature to 325° C. at a heating rate of 7° C. / min and maintaining the temperature for 4 h to obtain a calcined material; 3) Grinding the material obtained in step 2) and uniformly dispersing the ground material in deionized water and sonicating for 2 hours, then washing it several times with deionized water and anhydrous ethanol, respectively, and finally drying it in an electric blast drying oven at 60° C. for several hours and grinding it uniformly to obtain a powdery material of polyimide; 4) mixing the polyimide obtained in step 3) with silver sulfate and sodium molybdate to prepare a mixed solution; 5) The mixed solution obtained in step 4) was transferred into a 150 ml polytetrafluoroethylene autoclave, kept in an oven at 110-190° C. for 12-24 hours, and naturally cooled to room temperature to obtain a hydrothermal material; 6) The hydrothermal material obtained in step 5) was centrifuged, washed several times with deionized water and anhydrous ethanol, dried in an electric blast drying oven at 60° C. for several hours, and ground uniformly to obtain an Ag 2 MoO 4 / polyimide composite material.

2. The method for preparing the composite material according to claim 1, characterized in that: In step 3), the ground material is dispersed in 20 mL of deionized water and subjected to water bath ultrasonic dispersion treatment for 2 h to obtain an ultrasonic material.

3. The method for preparing the composite material according to claim 1, wherein: The mass ratio of the polyimide, silver sulfate, and sodium molybdate in step 4) is 1.3:2.32:

1. The polyimide and silver sulfate are dissolved in 50 mL of deionized water to form a mixed solution A, and the sodium molybdate is dissolved in 50 mL of deionized water to form a solution B. The solution B is added dropwise to the mixed solution A to obtain a mixed solution.

4. A composite material for treating tetracyclines in wastewater, characterized in that: The components thereof include the composite material prepared by the method according to any one of claims 1 to 3.

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