A Mn 2+ Doped metal-organic gel composites, methods of making and using the same

Abstract

The application belongs to the technical field of antibiotic degradation, and discloses a Mn 2+ The preparation method comprises the following steps: stirring aspartic acid and a cerium salt in an alkaline solvent, and then standing to obtain a metal organic gel; and adding a soluble manganese salt solution into the metal organic gel, standing, and drying to make manganese ions uniformly doped and dispersed in the metal organic gel, so as to obtain a Mn 2+ The preparation method of the application is simple and low in cost, and the Mn 2+ The doped metal organic gel composite material has high porosity, high specific surface area, and good adsorption effect on reaction substrate molecules, can adsorb antibiotic molecules close to the metal ion Mn 3+ / Mn 2+ and Ce 4+ / Ce 3+ , to participate in the oxidative degradation reaction of antibiotic molecules, and further enhance the ability of the material to degrade antibiotics through the photocatalytic Fenton reaction.

Description

Technical Field

[0001] This invention relates to the field of antibiotic degradation technology, and more particularly to a Mn 2+ Doped metal-organic gel composites, their preparation methods, and applications. Background Technology

[0002] Among various antibiotics, tetracycline hydrochloride is frequently used due to its broad-spectrum antibacterial activity and high production volume. Therefore, effectively removing tetracycline hydrochloride from wastewater has become an important task for protecting the environment and safeguarding human health.

[0003] To address the aforementioned technical problems, existing technologies mainly employ adsorption, flocculation, biodegradation, and Fenton reaction. Among these, the Fenton reaction can be carried out under near-ambient temperature and pressure conditions, and the resulting free radicals can degrade organic pollutants such as antibiotics into non-toxic substances such as CO2, H2O, and inorganic salts, making it one of the most effective technologies for removing pollutants from wastewater. However, the iron Fenton catalyst used in traditional Fenton reactions has the following drawbacks: (1) a narrow applicable pH range; (2) reaction conditions are predominantly acidic; (3) a large amount of iron sludge is produced after the reaction, which is difficult to treat; and (4) low H2O2 utilization rate.

[0004] Therefore, the present invention provides a Mn 2+ Doped metal-organic gel composites, their preparation methods, and applications. Summary of the Invention

[0005] To address the problems of high requirements for iron Fenton catalyst preparation, harsh reaction conditions, and difficult post-catalytic product treatment in existing technologies, as well as the low efficiency and high cost of antibiotic removal, this invention takes into account that metallic manganese and cerium have multiple valence states, such as Mn 3+ / Mn 2+ and Ce 4+ / Ce 3+ It has a similar multivalent state to Fe in iron. 3+ / Fe 2+ Due to the Fenton reaction properties, this invention aims to provide a catalyst based on manganese and cerium ions to achieve Fenton-like catalyst effects while avoiding the defects of traditional iron Fenton catalysts. Therefore, this invention provides a Mn... 2+ Doped metal-organic gel composites, their preparation methods, and applications.

[0006] A Mn of the present invention 2+ The doped metal-organic gel composite materials, their preparation methods, and applications are achieved through the following technical solutions:

[0007] The first objective of this invention is to provide a Mn 2+A method for preparing doped metal-organic gel composite materials includes the following steps:

[0008] Step 1: Using aspartic acid as a ligand, aspartic acid and cerium salt are placed in an alkaline solvent and stirred to react, then allowed to stand to obtain a metal-organic gel with a three-dimensional network structure.

[0009] Step 2: Using a soluble manganese salt solution as the doping ion source, it is uniformly added dropwise to the organometallic gel. After standing and drying, the manganese ions provided by the soluble manganese salt solution are uniformly doped and dispersed in the organometallic gel to obtain Mn. 2+ Doped metal-organic gel composites.

[0010] It should be noted that, considering the similarity between the coordination polymer molecules in the metal-organic gel and the three-dimensional network structure of metal-organic frameworks (MOFs), which possess advantages such as large porosity and specific surface area, and strong adsorption, this invention uses a metal-organic gel as a carrier and Mn as the substrate. 2+ As a loading medium, the target degradation product is first adsorbed through the organometallic gel, and then the Mn loaded on the organometallic gel is used as a loading medium. 2+ Ce on ion and metal organogel network nodes 4+ Ions participate in the redox reaction that degrades TC, and with the assistance of H2O2, they are conducive to the formation of Mn. 3+ / Mn 2+ and Ce 4+ / Ce 3+ The Fenton-like double redox reaction cycle enhances the redox capacity of the resulting catalyst, thereby achieving the degradation treatment of the target degradation products.

[0011] To ensure that the formed organometallic gel can not only act as a Mn 2+ The carrier to realize Mn 2+The uniform distribution of the aspartic acid and the good adsorption effect on the target degradation products are achieved. In some preferred embodiments of the present invention, aspartic acid is used as the ligand. For ease of description, aspartic acid will be referred to as Asp in the following invention. A cerium salt composed of cerium ions and inorganic anions is used as the cerium source. The mixture is stirred to ensure thorough homogenization, thereby allowing the aspartic acid to fully contact and coordinate with the cerium ions and inorganic anions provided by the cerium salt to form a coordination polymer. Since inorganic anions and solvent molecules are also present in the reaction system, adjacent coordination polymers can further form a metal-organic gel with a three-dimensional network structure through hydrogen bonding and intermolecular interactions with solvent molecules. The ratio of cerium salt to Asp has a crucial influence on gel formation. When the ratio of aspartic acid to cerium salt is insufficient or exceeds a certain proportion, gel formation cannot be effective. Therefore, in some preferred embodiments of the present invention, the molar ratio of aspartic acid to cerium salt is limited to 1:1.8 to 2.2 to ensure that the two can form a metal-organic gel. In some other preferred embodiments of the present invention, the molar ratio of aspartic acid to cerium salt may be more preferably 1:2.

[0012] To ensure that the cerium salt used in this invention not only provides cerium ions for coordination with Asp, but also forms coordination polymers under the action of the inorganic anions provided by the cerium salt, in some preferred embodiments of this invention, a soluble tetravalent cerium salt is used. In other preferred embodiments of this invention, cerium sulfate is used as the soluble tetravalent cerium salt.

[0013] To further promote the full contact and coordination of Asp with cerium ions provided by cerium salt to form a coordination polymer, in some preferred embodiments of the present invention, the reaction system also includes an alkaline solvent. This allows the carboxyl group in the Asp ligand to dehydrogenate under alkaline conditions, further increasing the solubility of Asp and facilitating coordination between Asp and cerium ions, leading to the formation of a coordination polymer under the action of the inorganic anions provided by the cerium salt. To further ensure that the formed coordination polymer can construct a metal-organic gel with a three-dimensional network structure through hydrogen bonding and intermolecular interactions with solvent molecules, in other preferred embodiments of the present invention, the alkaline solvent used is an aqueous solution of a soluble inorganic base. In other preferred embodiments of the present invention, the soluble inorganic base is one or both of sodium hydroxide and potassium hydroxide. In other preferred embodiments of the present invention, the concentration of the soluble inorganic base in the alkaline solvent is 0.1 mol / L to 1.5 mol / L.

[0014] The present invention takes into account that the amount of alkaline solvent has an impact on the formation of gel-like organometallic gels. Too much or too little alkaline solvent will not effectively form organometallic gels. Therefore, in some preferred embodiments of the present invention, the molar ratio of soluble inorganic base to cerium salt in the alkaline solvent is 0.9 to 1.1:1.

[0015] To ensure that the cerium salt and Asp can be fully mixed and reacted in the alkaline solvent to form a metal-organic gel through stirring, in some other preferred embodiments of the present invention, the stirring time for the stirring reaction is 5 min to 10 min.

[0016] To further ensure that the cerium salt and Asp are thoroughly mixed and react to form a metal-organic gel, in some preferred embodiments of the present invention, after stirring, the mixture is allowed to stand at room temperature for 5 to 15 minutes to achieve the formation of a metal-organic gel.

[0017] This invention takes into account that Mn has multiple oxidation states. In some preferred embodiments of this invention, the concentration of manganese ions in the soluble manganese salt solution is 0.05 mol / L to 0.15 mol / L, in order to achieve the formation of Ce in the material. 4+ / Ce 3+ and Mn 3+ / Mn 2+ The Fenton-like redox reaction dual cycle aims to enhance the catalytic degradation of antibiotics.

[0018] To ensure that manganese ions in the added soluble manganese salt solution are uniformly doped into the organometallic gel, in some preferred embodiments of the present invention, the settling temperature after the soluble manganese salt solution is added is room temperature, and the settling time is 5 min to 15 min. Due to the semi-solid nature of the gel, Mn 2+ It slowly penetrates into the gel during the standing process, thus achieving full doping through standing.

[0019] To further ensure that the soluble manganese salt solution used can be uniformly dispersed in the metal-organic gel, and to achieve Mn 2+ In some preferred embodiments of the present invention, the molar ratio of manganese ions in the soluble manganese salt solution to cerium ions in the organometallic gel is 1-2:1-6.

[0020] In order to improve the obtained Mn 2+To improve the catalytic performance of the doped gel composite material, this invention also dries the doped product after standing to enhance gel adsorption. Considering the presence of solvent water molecules in the gel structure, in some preferred embodiments, the drying temperature is controlled between 45°C and 55°C to remove water from the gel and increase its porosity. This invention also considers that a drying time that is too short will not effectively improve gel adsorption to adsorb antibiotic molecules, while a drying time that is too long will result in excessive loss of solvent water and denser gel fiber packing, leading to a decrease in the Fenton-like photocatalytic degradation effect of the material. Therefore, in other preferred embodiments, the drying time is controlled between 48h and 72h.

[0021] A second objective of this invention is to provide a Mn prepared by the above-described preparation method. 2+ Doped metal-organic gel composites.

[0022] A third objective of this invention is to provide the above-mentioned Mn 2+ Application of doped metal-organic gel composites in photocatalytic Fenton-like degradation of tetracycline hydrochloride.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] This invention uses aspartic acid as a ligand and a cerium salt composed of cerium ions and inorganic anions as a cerium source. Through stirring, the mixture is thoroughly homogenized, allowing the aspartic acid to fully contact and coordinate with the cerium ions and inorganic anions provided by the cerium salt to form a coordination polymer. Furthermore, the presence of inorganic anions and solvent molecules in the reaction system allows adjacent coordination polymers to further form a three-dimensional network structure of organometallic gel through hydrogen bonding and intermolecular interactions with solvent molecules. And by using Mn... 2+ When dropped into a metal-organic gel, Mn was formed in situ. 2+ Doped metal-organic gel composite materials. The preparation method of this invention is simple and low in cost.

[0025] Mn prepared by this invention 2+ In doped metal-organic gel composites, the three-dimensional network structure of the metal-organic gel has advantages such as high porosity and large specific surface area. Therefore, it has a good adsorption effect on reaction substrate molecules, and can adsorb antibiotic TC molecules near the reaction site, close to the metal ion Mn. 3+ / Mn 2+ and Ce 4+ / Ce 3+ This facilitates participation in redox reactions, thereby enhancing the material's photocatalytic Fenton-like ability to degrade antibiotics, making the Mn of this invention... 2+Doped organometallic gel composites can be used to address water pollution problems caused by antibiotics.

[0026] Furthermore, experiments conducted according to this invention demonstrate that the Mn of this invention... 2+ With the assistance of H2O2, the doped metal-organic gel composite material can efficiently achieve photocatalytic degradation and removal of tetracycline hydrochloride from aqueous solution, avoiding the defects of traditional iron Fenton catalysts. Attached Figure Description

[0027] Figure 1 Mn of the present invention 2+ A schematic diagram of the preparation process of doped metal-organic gel composite materials.

[0028] Figure 2 The image shows the SEM image of Ce-Asp-Mn in Example 1.

[0029] Figure 3 The images show the XRD patterns of Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1.

[0030] Figure 4 The BET plots are for Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1.

[0031] Figure 5 The pore size distribution diagrams are for Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1.

[0032] Figure 6 The UV DRS images are of Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1.

[0033] Figure 7 The images show the Kubelka-Munk diagrams of Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1.

[0034] Figure 8 Electrochemical impedance spectroscopy (EIS) diagrams of Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 are shown.

[0035] Figure 9 The photocurrent response diagrams are for Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1.

[0036] Figure 10 The results show the effect of catalyst type on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride.

[0037] Figure 11 The results show the effect of manganese ion doping on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride.

[0038] Figure 12 The results show the effect of catalyst dosage on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride.

[0039] Figure 13 The results show the effect of pH on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride.

[0040] Figure 14 The results show the effect of initial H2O2 concentration on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride. Detailed Implementation

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below. It should be noted that in the following embodiments of the present invention, the aspartic acid used was purchased from Sinopharm Chemical Reagent Co., Ltd., and the double-distilled water used was prepared by Shanghai Yarong Biochemical Instrument Factory using an SZ-93 double pure water distiller. It should also be noted that in the following embodiments of the present invention, mM represents mmol·L⁻¹. -1 Furthermore, PBS buffer solution was used to represent Phosphate buffer saline solutions with pH = 2 to 12.

[0042] Example 1

[0043] Please see Figure 1 This embodiment provides a Mn 2+ The doped metal-organic gel composite material, and its preparation method is as follows:

[0044] Step 1, Preparation of metal-organic gel:

[0045] 1) Mix sodium hydroxide with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Sodium hydroxide solution is used as an alkaline solvent.

[0046] 2) Mix aspartic acid with deionized water to prepare a solution with a concentration of 0.5 mol·L⁻¹. -1 Aspartic acid solution.

[0047] 3) Mix Ce(SO4)2 with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Ce(SO4)2 solution.

[0048] 4) Take 1.0 mL of the alkaline solvent, 1.0 mL of the aspartic acid solution, and 1.0 mL of the Ce(SO4)2 solution prepared above and mix them. Stir for 10 min to mix well, and then let stand for 5 min to obtain a pale yellow opaque gel, i.e., a metal-organic gel.

[0049] Step 2, doping with Mn 2+ :

[0050] Take 10 μL of a solution with a concentration of 0.1 mol·L⁻¹ -1 The MnCl2 solution was uniformly added to the gel, and the process was allowed to proceed as planned. 2+ The metal-organic gel obtained in step 1 was slowly infiltrated and then allowed to stand at room temperature for 10 minutes, followed by drying at 50°C for 48 hours to obtain Mn. 2+ The doped metal-organic gel composite material is denoted as Ce-Asp-Mn.

[0051] Example 2

[0052] This embodiment provides a Mn 2+ The doped metal-organic gel composite material, and its preparation method is as follows:

[0053] Step 1, Preparation of metal-organic gel:

[0054] 1) Mix sodium hydroxide with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Sodium hydroxide solution is used as an alkaline solvent.

[0055] 2) Mix aspartic acid with deionized water to prepare a solution with a concentration of 0.5 mol·L⁻¹. -1 Aspartic acid solution.

[0056] 3) Mix Ce(SO4)2 with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Ce(SO4)2 solution.

[0057] 4) Take 1.0 mL of the alkaline solvent, 1.0 mL of the aspartic acid solution, and 1.0 mL of the Ce(SO4)2 solution prepared above and mix them. Stir for 10 min to mix well, and then let stand for 5 min to obtain a pale yellow opaque gel, i.e., a metal-organic gel.

[0058] Step 2, doping with Mn 2+ :

[0059] Take 5 μL of a solution with a concentration of 0.1 mol·L⁻¹. -1 The MnCl2 solution was uniformly added to the gel, and the process was allowed to proceed as planned. 2+ The metal-organic gel obtained in step 1 was slowly infiltrated and then allowed to stand at room temperature for 10 minutes, followed by drying at 50°C for 48 hours to obtain Mn. 2+ The doped metal-organic gel composite material is denoted as Ce-Asp-Mn.

[0060] The only difference between this embodiment and Embodiment 1 is that:

[0061] In this embodiment, the concentration is 0.1 mol·L⁻¹. -1 The amount of MnCl2 solution used was 5 μL, which means that the molar ratio of Ce to Mn in this example was 2:1.

[0062] Example 3

[0063] This embodiment provides a Mn 2+ The doped metal-organic gel composite material, and its preparation method is as follows:

[0064] Step 1, Preparation of metal-organic gel:

[0065] 1) Mix sodium hydroxide with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Sodium hydroxide solution is used as an alkaline solvent.

[0066] 2) Mix aspartic acid with deionized water to prepare a solution with a concentration of 0.5 mol·L⁻¹. -1 Aspartic acid solution.

[0067] 3) Mix Ce(SO4)2 with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Ce(SO4)2 solution.

[0068] 4) Take 1.0 mL of the alkaline solvent, 1.0 mL of the aspartic acid solution, and 1.0 mL of the Ce(SO4)2 solution prepared above and mix them. Stir for 10 min to mix well, and then let stand for 5 min to obtain a pale yellow opaque gel, i.e., a metal-organic gel.

[0069] Step 2, doping with Mn 2+ :

[0070] Take 40 μL of a solution with a concentration of 0.1 mol·L⁻¹. -1 The MnCl2 solution was uniformly added to the gel, and the process was allowed to proceed as planned. 2+ The metal-organic gel obtained in step 1 was slowly infiltrated and then allowed to stand at room temperature for 10 minutes, followed by drying at 50°C for 48 hours to obtain Mn. 2+ The doped metal-organic gel composite material is denoted as Ce-Asp-Mn.

[0071] The only difference between this embodiment and Embodiment 1 is that:

[0072] In this embodiment, the concentration is 0.1 mol·L⁻¹. -1 The amount of MnCl2 solution used was 40 μL, which means that the molar ratio of Ce to Mn in this example was 1:4.

[0073] Example 4

[0074] This embodiment provides a Mn 2+ The doped metal-organic gel composite material, and its preparation method is as follows:

[0075] Step 1, Preparation of metal-organic gel:

[0076] 1) Mix sodium hydroxide with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Sodium hydroxide solution is used as an alkaline solvent.

[0077] 2) Mix aspartic acid with deionized water to prepare a solution with a concentration of 0.5 mol·L⁻¹. -1 Aspartic acid solution.

[0078] 3) Mix Ce(SO4)2 with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Ce(SO4)2 solution.

[0079] 4) Take 1.0 mL of the alkaline solvent, 1.0 mL of the aspartic acid solution, and 1.0 mL of the Ce(SO4)2 solution prepared above and mix them. Stir for 10 min to mix well, and then let stand for 5 min to obtain a pale yellow opaque gel, i.e., a metal-organic gel.

[0080] Step 2, doping with Mn 2+ :

[0081] Take 60 μL of a solution with a concentration of 0.1 mol·L⁻¹. -1 The MnCl2 solution was uniformly added to the gel, and the process was allowed to proceed as planned. 2+ The metal-organic gel obtained in step 1 was slowly infiltrated and then allowed to stand at room temperature for 10 minutes, followed by drying at 50°C for 48 hours to obtain Mn. 2+ The doped metal-organic gel composite material is denoted as Ce-Asp-Mn.

[0082] The only difference between this embodiment and Embodiment 1 is that:

[0083] In this embodiment, the concentration is 0.1 mol·L⁻¹. -1 The amount of MnCl2 solution used was 60 μL, which means that the molar ratio of Ce to Mn in this example was 1:6.

[0084] Comparative Example 1

[0085] This comparative example provides a metal-organic gel material, and its preparation method is as follows:

[0086] 1) Mix sodium hydroxide with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Sodium hydroxide solution is used as an alkaline solvent.

[0087] 2) Mix aspartic acid with deionized water to prepare a solution with a concentration of 0.5 mol·L⁻¹. -1 Aspartic acid solution.

[0088] 3) Mix Ce(SO4)2 with deionized water to prepare a solution with a concentration of 1.0 mol·L⁻¹. -1 Ce(SO4)2 solution.

[0089] 4) Take 1.0 mL of the alkaline solvent, 1.0 mL of the aspartic acid solution, and 1.0 mL of the Ce(SO4)2 solution prepared above and mix them. Stir for 10 min and mix well. Then let it stand for 5 min to obtain a pale yellow opaque gel, which is a metal-organic gel, namely Ce-Asp.

[0090] The only difference between this comparative example and Example 1 is that:

[0091] This comparative example does not involve Mn. 2+ Doping.

[0092] Experimental Section

[0093] (I) Scanning Electron Microscopy Testing

[0094] This invention takes Ce-Asp-Mn from Example 1 as an example and performs scanning electron microscopy (SEM) tests on it, and the test results are as follows. Figure 2 As shown.

[0095] Depend on Figure 2 As can be seen, the Ce-Asp-Mn dry gel of Example 1 has the morphology of aggregated porous spherical structures. This indicates that the addition of Mn... 2+ Part of Ce in the post-metal-organic polymer Ce-Asp 4+ Mn 2+ Restored to Ce 3+ With SO4 added as a raw material 2- The particles combine to form Ce2(SO4)3 nanoparticles, resulting in the partial disruption of the gel network, with the nanoparticles dispersed within the gel network.

[0096] (II) XRD Testing

[0097] This invention uses Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples, and performs XRD tests on them respectively, and the test results are as follows. Figure 3 As shown.

[0098] Depend on Figure 3 It can be seen that the Ce-Asp-Mn gel composite material in Example 1 contains a certain amount of Ce2(SO4)3. This indicates that Mn 2+ Partial Ce is doped into the Ce-Asp gel network.4+ Mn 2+ Restored to Ce 3+ , with SO4 2- They combine to form Ce2(SO4)3 nanoparticles.

[0099] (III) BET Adsorption Test

[0100] This invention uses Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples, and performs BET adsorption tests on them respectively. The test method is as follows: using a JW-DX400 surface area analyzer, 100 mg of sample is taken, vacuum dried and activated at 120℃ for about 5 hours, and then the sample is placed on the instrument. The adsorption isotherm is measured at 77.35 K under liquid N2. Based on the adsorption isotherm data, the BET equation is used for fitting to obtain the slope and intercept of the adsorption isotherm. The specific surface area is calculated according to the BET equation. The test results are then... Figure 4 As shown.

[0101] Depend on Figure 4 It can be seen that both the Ce-Asp of Comparative Example 1 and the Ce-Asp-Mn of Example 1 exhibit typical Type IV curves, accompanied by hysteresis loops, indicating that they are both mesoporous materials. The BET specific surface area of ​​the Ce-Asp gel in Comparative Example 1 is 5.3289 m². 2 / g, while the specific surface area of ​​Ce-Asp-Mn in Example 1 was 18.3359m². 2 / g, this surface Mn 2+ After doping, the adsorption capacity of Ce-Asp gel can be significantly enhanced.

[0102] (iv) Aperture Distribution Test

[0103] This invention takes Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples, and performs BET tests on them respectively. The pore size distribution is calculated from the BET data, and the pore size distribution is as follows. Figure 5 As shown.

[0104] Depend on Figure 5 It can be seen that the pore size distribution of Ce-Asp in Comparative Example 1 is significantly larger than that of Ce-Asp-Mn in Example 1. Furthermore, calculations based on BET data show that the average pore radius of Ce-Asp-Mn in Example 1 is approximately 2 nm, which may be due to the agglomeration of the Ce-Asp-Mn composite material.

[0105] (V) Ultraviolet-Visible Diffuse Reflectance Spectroscopy Test

[0106] This invention takes Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples and performs ultraviolet-visible diffuse reflectance spectroscopy tests on them respectively.

[0107] The test conditions were as follows: a UV-2600i ultraviolet spectrophotometer was used. 10 mg of the solid sample was placed on a MgCl2 white plate, and the absorbance was measured to obtain the DRS spectrum. The test results... Figure 6 As shown.

[0108] Depend on Figure 6 It can be seen that Ce-Asp in Comparative Example 1 and Ce-Asp-Mn in Example 1 have significant solar light absorption rates around 420 nm. This indicates that both Ce-Asp and Ce-Asp-Mn materials can absorb solar energy and possess photocatalytic properties.

[0109] (vi) Bandgap energy calculation

[0110] This invention uses Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples, and uses UV-Vis diffuse reflectance DRS data to plot Kubelka-Munk curves, utilizing (ahv) 2 The band gap energy was calculated based on its relationship with photon energy (hv). The calculation results are as follows. Figure 7 As shown.

[0111] Figure 7 The Kubelka-Munk diagrams are for Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1, and are derived from... Figure 7 It can be seen that E in Comparative Example 1 g The E of Ce-Asp-Mn in Example 1 is 2.13 eV. g The value is 2.51 eV. This indicates that Mn is incorporated into the Ce-Asp gel. 2+ Afterwards, the band gap energy increases, and the photocatalytic activity improves.

[0112] (vii) Electrochemical impedance spectroscopy

[0113] In this invention, the electrochemical impedance spectroscopy was performed on Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1.

[0114] The test conditions were as follows: electrochemical tests were performed using a CHI760E electrochemical analyzer, and the electrolyte solution was 1.0 mol·L⁻¹. -1 Na₂SO₄. Weigh 10 mg of the catalyst, disperse it in 80 μL of anhydrous ethanol solution, add 4 drops of 5% naphthol, sonicate to disperse, and then evenly spread it to a 1.0 cm² area. 2 The working electrode was fabricated on ITO conductive glass. The scan rate was 0.1 V / sec, the test potential was 2 V, and the scan window was maintained at +2 V to -2 V (vsAg / AgCl). The sensitivity was 1.0 × 10⁻⁶. -6 A / V, runtime 400s.

[0115] And the test results Figure 8 As shown.

[0116] Figure 8 The electrochemical impedance spectroscopy diagrams are of Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1, and are derived from... Figure 8 As can be seen, compared with Ce-Asp in Comparative Example 1, the Ce-Asp-Mn composite material in Example 1 has a smaller impedance curve diameter and lower charge transfer resistance. This indicates that the Ce-Asp-Mn prepared by the method of the present invention has stronger charge transfer capability.

[0117] (viii) Photocurrent response test

[0118] This invention uses Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as examples, and performs photocurrent response tests on them respectively. The test method is the same as the electrochemical impedance spectroscopy test described above, except that a xenon lamp is used to irradiate the sample during the photocurrent response test. The test results... Figure 9 As shown.

[0119] Figure 9 The photocurrent response diagrams are those of Ce-Asp-Mn in Example 1 and Ce-Asp in Comparative Example 1, and are derived from... Figure 9 It can be seen that when the light is turned off and on, the photocurrent generated by Ce-Asp-Mn under visible light irradiation is significantly enhanced compared to Ce-Asp gel. This indicates that the photoinduced carrier transfer rate in Ce-Asp-Mn is faster, confirming the Mn doping in the gel. 2+ This inhibits the recombination rate of photogenerated electron-hole pairs, thereby improving the photocurrent performance of the material and enhancing its photocatalytic ability.

[0120] (ix) Performance testing of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0121] 1) The effect of catalyst type on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0122] This invention uses Ce-Asp-Mn from Example 1 and Ce-Asp from Comparative Example 1 as catalysts to test the photocatalytic degradation effect of Ce-Asp-Mn and Ce-Asp on tetracycline hydrochloride under H2O2 environment. The test group of Example 1 is designated as Ce-Asp-Mn+H2O2, and the test group of Comparative Example 1 is designated as Ce-Asp+H2O2. The experimental group without catalyst and H2O2 is used as a blank control, designated as TC+H2O2. The experimental group without any catalyst is used as control group 1, designated as TC. The experimental group with only Ce-Asp-Mn from Example 1 is used as control group 2, designated as Ce-Asp-Mn. All tests were conducted using the same method, and the test results... Figure 10 As shown.

[0123] The testing method is as follows:

[0124] The photocatalytic degradation reaction was carried out at room temperature. A PBS buffer solution was used, and the pH of the reaction solution was adjusted from 0.1 mol·L⁻¹. -1 HCl solution or 0.1 mol·L -1 Adjusted with NaOH solution.

[0125] Add 100 mg of the above catalyst to 100 mL of TC solution, and stir in the dark for 30 minutes under 500 W xenon lamp irradiation until adsorption / desorption equilibrium is reached. Take 3 mL of the mixed solution, centrifuge to obtain a clear solution, and determine the residual TC concentration at the maximum absorption peak of 371 nm using a UV spectrophotometer.

[0126] The photocatalytic efficiency e is calculated according to Equation 1:

[0127]

[0128] In Equation 1, C0 and C represent the concentrations of TC before and after photoexcitation, respectively.

[0129] Figure 10 The results show the effect of catalyst type on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride, and are derived from... Figure 10 It can be seen that the photodegradation reaction of TC is negligible in the absence of a catalyst, indicating that TC is very stable and not easily decomposed. In the adsorption / desorption equilibrium experiment, the adsorption rates of TC on Ce-Asp and Ce-Asp-Mn were approximately 40% and 50%, respectively. The adsorption capacity of Ce-Asp-Mn was slightly higher than that of Ce-Asp. In the presence of H2O2 and with the action of the Fenton-like catalyst Ce-Asp-Mn, the photodegradation efficiency of TC was significantly improved, reaching as high as 98%. This indicates that Mn... 2+ Doping into Ce-Asp gel improves the Fenton-like photocatalytic degradation ability of TC.

[0130] 2) The effect of manganese ion doping amount on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0131] This invention uses Examples 1-4 as photocatalysts, and tests the degradation effect of catalysts prepared with different manganese ion doping amounts on tetracycline hydrochloride photocatalytic degradation with the assistance of H2O2. The test results are as follows. Figure 11 As shown. Figure 11 In the text, Ce:Mn = 1:1 represents Example 3, Ce:Mn = 2:1 represents Example 2, Ce:Mn = 1:4 represents Example 3, and Ce:Mn = 1:6 represents Example 4.

[0132] The test method was as follows: A 500W Xe lamp was used to simulate sunlight. At room temperature, 20 mg of photocatalyst and 20 mg of tetracycline hydrochloride were added to 50 mL of aqueous solution containing PBS buffer, and the mixture was ultrasonically dispersed. A 1 mol·L⁻¹ solution was then used. -1 hydrochloric acid solution with a concentration of 1 mol·L -1 The pH of the solution was adjusted to 7 using sodium hydroxide solution. Before photocatalysis, the suspension was stirred in the dark for 30 min to allow adsorption / desorption equilibrium to be reached between the substrate and catalyst. Then, 20 mmol·L⁻¹ of sodium hydroxide solution was added. -1 10 mL of 30% H2O2 solution was added, then transferred to an Xe lamp for irradiation and timing was started. Every 5 min, 3 mL of suspension was taken out, the supernatant was collected by centrifugation, and the absorption at 371 nm was measured using a liquid ultraviolet spectrophotometer to calculate the TC degradation rate.

[0133] Figure 11 The results show the effect of manganese ion doping on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride. Figure 11 It can be seen that when the amount of manganese ions is too much or too little, the degradation effect of tetracycline hydrochloride by photocatalysis cannot be effectively improved. Therefore, the optimal Ce / Mn ratio of 1:1 to 4 is the best for catalytic effect in this invention.

[0134] 3) Test results of the effect of catalyst dosage on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0135] The present invention employs the following testing methods to test the degradation effect of the catalyst on the photocatalytic degradation of tetracycline hydrochloride in an H2O2 environment, and the test results are as follows. Figure 12 As shown.

[0136] The test method was as follows: A 500W Xe lamp was used to simulate sunlight. At room temperature, 30 mg of Ce-Asp-Mn from Example 1 was used as a photocatalyst, and it was added to 50 mL of an aqueous solution containing PBS buffer solution along with 20 mg of tetracycline hydrochloride. The mixture was then ultrasonically dispersed. A 0.1 mol·L⁻¹ solution was used.-1 HCl solution and 0.1 mol·L -1 The pH of the solution was adjusted to 7 using NaOH solution. Before photocatalysis, the suspension was stirred in the dark for 30 min to allow the substrate and catalyst to reach adsorption / desorption equilibrium. Then, 20 mmol·L⁻¹ of NaOH solution was added. -1 10 mL of a 30% H2O2 solution was added, then transferred to an Xe lamp for irradiation and timing was started. Every 5 min, 3 mL of the suspension was taken out, the supernatant was collected by centrifugation, and the absorption at 371 nm was measured using a liquid ultraviolet spectrophotometer to calculate the TC degradation rate.

[0137] Figure 12 The results show the effect of catalyst dosage on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride, and are derived from... Figure 12 It can be seen that the optimal catalyst dosage is 30mg.

[0138] 4) Test results on the effect of pH value on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0139] This invention employs the following testing methods to test the degradation effect of the catalyst on tetracycline hydrochloride photocatalytically under different pH values ​​and with H2O2-assisted reaction, and the test results are presented. Figure 13 As shown.

[0140] The test method was as follows: a 500W Xe lamp was used to simulate sunlight. At room temperature, 30mg of Ce-Asp-Mn from Example 1 was used as a photocatalyst, and it and 20mg of tetracycline hydrochloride were added separately to 50mL of aqueous solution containing PBS buffer, ultrasonically dispersed, and then treated with 0.1mol·L⁻¹ water. -1 HCl solution or 0.1 mol·L -1 The pH values ​​of the solutions were adjusted to 3.7, 4.1, 5.4, 6.2, 7.6, and 9.3 using NaOH solutions. Before photocatalysis, the suspension was stirred in the dark for 30 min to allow adsorption / desorption equilibrium between the substrate and catalyst. Then, 20 mmol·L⁻¹ NaOH solution was added. -1 10 mL of a 30% H2O2 solution was added, then transferred to an Xe lamp for irradiation and timing was started. Every 5 minutes, 3 mL of the suspension was taken out, the supernatant was collected by centrifugation, and the absorption at 371 nm was measured using a liquid ultraviolet spectrophotometer to calculate the degradation rate.

[0141] Figure 13 The results show the effect of solution pH on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride, and are derived from... Figure 13 It can be seen that the catalyst exhibits the best degradation performance when the solution pH is 6.2.

[0142] 5) Results of the test on the effect of initial H2O2 concentration on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride

[0143] This invention employs the following testing methods to test the photocatalytic degradation effect of the catalyst on tetracycline hydrochloride under an initial H2O2 environment, and the test results are presented. Figure 14 As shown.

[0144] The test method was as follows: a 500W Xe lamp was used to simulate sunlight. At room temperature, 20mg of Ce-Asp-Mn from Example 1 was used as a photocatalyst, and it was added to 50mL of an aqueous solution containing PBS buffer with 20mg of tetracycline hydrochloride. The mixture was ultrasonically dispersed, and then 0.1mol·L⁻¹ was used. -1 HCl solution and 0.1 mol·L -1 The pH of the solution was adjusted to 7 using NaOH solution. Before photocatalysis, the suspension was stirred in the dark for 30 min to allow the substrate and catalyst to reach adsorption / desorption equilibrium. Then, 10 mL of H₂O₂ solutions with concentrations of 9.8 mM, 14.7 mM, 19.6 mM, and 24.5 mM were added, respectively. The solution was then transferred to a Xe lamp for irradiation, and timing was started. Every 5 min, 3 mL of suspension was collected, the supernatant was collected by centrifugation, and the absorbance at 371 nm was measured using a liquid ultraviolet spectrophotometer to calculate the TC degradation rate.

[0145] Figure 14 The results show the effect of initial H2O2 concentration on the performance of Fenton-like photocatalytic degradation of tetracycline hydrochloride. Figure 14 It can be seen that the catalytic performance is best when the initial concentration of H2O2 is 19.6 mM.

[0146] Obviously, the above embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A type of Mn 2+ A method for preparing doped metal-organic gel composite materials, characterized in that, Includes the following steps: Using aspartic acid as a ligand and a cerium salt composed of cerium ions and inorganic anions as a cerium source, aspartic acid and cerium salt are placed in an alkaline solvent and stirred for reaction, followed by standing to allow the aspartic acid to coordinate with the cerium ions provided by the cerium salt, and form a coordination polymer under the action of the inorganic anions provided by the cerium salt; adjacent coordination polymers form a metal-organic gel with a three-dimensional network structure through hydrogen bonding with solvent molecules and intermolecular interactions. A soluble manganese salt solution was used as the doping ion source and uniformly added dropwise to the organometallic gel. After standing and drying, the manganese ions provided by the soluble manganese salt solution were uniformly dispersed in the organometallic gel to obtain Mn. 2+ Doped metal-organic gel composite material; drying temperature 45℃~55℃, drying time 48h~72h; The alkaline solvent is an aqueous solution of a soluble inorganic base.

2. The preparation method according to claim 1, characterized in that, The cerium salt is a soluble tetravalent cerium salt.

3. The preparation method according to claim 1, characterized in that, The molar ratio of soluble inorganic base to cerium salt in the alkaline solvent is 0.9~1.1:

1.

4. The preparation method according to claim 1, characterized in that, The concentration of soluble inorganic base in the alkaline solvent is 0.1 mol / L to 1.5 mol / L.

5. The preparation method according to claim 1, characterized in that, The molar ratio of aspartic acid to cerium salt is 1:1.8~2.

2.

6. The preparation method according to claim 1, characterized in that, The concentration of manganese ions in the soluble manganese salt solution is 0.05 mol / L to 0.15 mol / L; the molar ratio of manganese ions in the soluble manganese salt solution to cerium ions in the organometallic gel is 1 to 2: 1 to 6.

7. The preparation method according to claim 1, characterized in that, The stirring time for the stirring reaction is 5 min to 15 min.

8. The preparation method according to claim 1, characterized in that, The soluble manganese salt solution was allowed to stand at room temperature for 5 to 15 minutes after being added dropwise.

9. A Mn prepared by the preparation method according to any one of claims 1-8 2+ Doped metal-organic gel composites.

10. A Mn according to claim 9 2+ Application of doped metal-organic gel composites in photocatalytic Fenton-like degradation of antibiotics.

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