Preparation method of In (OH) 3 / MIL-68 (In) composite material and application of In (OH) 3 / MIL-68 (In) composite material in photocatalytic degradation of ciprofloxacin

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to an In (OH) 3 / MIL-68 (In) composite material, a preparation method thereof and application of the In (OH) 3 / MIL-68 (In) composite material in photocatalytic degradation of ciprofloxacin. The preparation method of the In (OH) 3 / MIL-68 (In) composite material comprises the following steps: dissolving In (NO3) 3 * xH2O and terephthalic acid in DMF (Dimethyl Formamide), and carrying out hydrothermal reaction, washing and vacuum drying to obtain MIL-68 (In); ultrasonically dispersing the MIL-68 (In) in a 2-methylimidazole aqueous solution, standing at room temperature, washing and drying to obtain In (OH) 3 / aMIL-68 (In); the removal efficiency of the In (OH) 3 / MIL-68 (In) composite material on the CIP reaches 91.90% within 60 minutes.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to an In(OH)3 / MIL-68(In) composite material, its preparation method, and its application in the photocatalytic degradation of ciprofloxacin. Background Technology

[0002] Quinolone antibiotics are among the most widely used antibacterial drugs globally, possessing broad-spectrum antibacterial activity and finding extensive applications in medical and veterinary fields. Ciprofloxacin (CIP) is particularly prevalent; it is not only incompletely metabolized in humans but also released from animals as a metabolite of enrofloxacin, resulting in large quantities of CIP entering the aquatic environment. More seriously, pathogenic bacteria in wastewater may develop resistance under the selective pressure of CIP, posing a threat to the ecosystem and public health. Therefore, developing effective technologies to degrade CIP and eliminate pathogenic and drug-resistant bacteria is crucial.

[0003] Researchers have explored various water pollution treatment technologies, including biodegradation, membrane filtration, adsorption, and advanced oxidation processes (AOPs). Among these, photocatalysis, as an important branch of AOPs, has attracted much attention due to its ability to efficiently degrade recalcitrant organic pollutants. However, common semiconductor photocatalysts generally suffer from drawbacks such as narrow light absorption range and rapid recombination of photogenerated carriers, which severely limit their practical application. Therefore, constructing photocatalysts that combine high degradation efficiency with broad-spectrum absorption performance has become a key focus of current research. Summary of the Invention

[0004] To address the above problems, this invention provides an In(OH)3 / MIL-68(In) composite material, the preparation method of which is as follows:

[0005] Step 1: Synthesis of MIL-68(In): In(NO3)3·xH2O and terephthalic acid were dissolved in DMF, the mixture was subjected to hydrothermal reaction, the resulting precipitate was washed and dried under vacuum to obtain MIL-68(In);

[0006] Step 2: Synthesis of In(OH)3 / aMIL-68(In): MIL-68(In) was ultrasonically dispersed in an aqueous solution of 2-methylimidazolium, allowed to stand at room temperature, washed and dried to obtain In(OH)3 / aMIL-68(In) (IM).

[0007] In the aforementioned In(OH)3 / MIL-68(In) composite material, in step 1, the mass ratio or molar ratio of In(NO3)3·xH2O and terephthalic acid is 1:1.

[0008] In the above-mentioned In(OH)3 / MIL-68(In) composite material, the hydrothermal reaction in step 1 is carried out at 100 °C for 48 h.

[0009] In the aforementioned In(OH)3 / MIL-68(In) composite material, in step 2, the mass ratio of MIL-68(In) to 2-methylimidazole is 1:19-20, and the concentration of the 2-methylimidazole aqueous solution is 0.6 mol / L.

[0010] The above-mentioned In(OH)3 / MIL-68(In) composite material is used in the photocatalytic degradation of ciprofloxacin.

[0011] The above application is carried out as follows: In a solution containing ciprofloxacin, with or without the addition of persulfate, an In(OH)3 / MIL-68(In) composite material is added to carry out photocatalytic degradation.

[0012] The above application is characterized by the following method: the concentration of ciprofloxacin is 20-30 mg / L. -1 The concentration of the In(OH)3 / MIL-68(In) composite material is 0.8-1.2 mg / mL. -1 .

[0013] The beneficial effects of this invention are:

[0014] MIL-68(In) contains abundant indium-oxygen clusters and exhibits high photoresponsiveness. To optimize its photocatalytic performance, this invention modifies it using an alkaline 2-methylimidazole solution. During this process, the organic linkers of the material are partially etched, and the exposed metal centers react with hydroxyl groups to generate In(OH)3, ultimately forming an In(OH)3 / aMIL-68(In) composite material. This material can efficiently photocatalyze the activation of persulfate, thereby improving the degradation efficiency of CIP. Attached Figure Description

[0015] Figure 1 These are the XRD patterns of In(OH)3, IM, and MIL-68(In).

[0016] Figure 2 The images are scanning electron microscope images of MIL-68(In) (A), IM (B) and In(OH)3 (C); energy dispersive spectroscopy (EDS) of IM; transmission electron microscope (E) and high-resolution transmission electron microscope (F) images of IM and its inverse fast Fourier transform (IFFT) (G).

[0017] Figure 3Fourier transform infrared (A), XPS spectra (B), high-resolution XPS spectra of C 1s (C), high-resolution XPS spectra of In 3d (D), and high-resolution XPS spectra of O 1s (E) for different samples. N2 adsorption-desorption isotherms and pore size distributions for different samples (F).

[0018] Figure 4 Removal rates of CIP by blank, MIL-68(In), IM and In(OH)3 under illumination (A). Removal rates of CIP by blank, MIL-68(In), IM and In(OH)3 under illumination and in the presence of PS (B). Detailed Implementation

[0019] Example 1: Synthesis of In(OH)3 / aMIL-68(In)

[0020] 1. Synthesis of MIL-68(In):

[0021] 0.598 g of In(NO3)3·xH2O (molecular weight 300.83) and 0.598 g of terephthalic acid were dissolved in 20 mL of DMF. The mixture was then reacted in a PTFE-lined autoclave (100 °C, 48 h). The resulting precipitate was washed with water and ethanol and then dried under vacuum at 60 °C to obtain the MIL-68(In) sample.

[0022] 2. Synthesis of In(OH)3 / aMIL-68(In):

[0023] 50 mg of MIL-68(In) sample was ultrasonically dispersed in 20 mL of 2-methylimidazole (2-MeIm) aqueous solution (0.6 mol / L) and allowed to stand at room temperature for 6 hours. The sample was then washed and dried to obtain In(OH)3 / aMIL-68(In), denoted as IM.

[0024] Example 2 Characterization of In(OH)3 / aMIL-68(In)

[0025] The structural features and phase composition of the catalyst were detected by X-ray diffraction (XRD) analysis (Figure 1). The diffraction peaks of MIL-68(In) were in high agreement with the simulated pattern, indicating its high crystallinity and successful formation of the framework structure. In contrast, the IM sample showed almost no clear reflection, suggesting the presence of an amorphous MOF phase. When the processing time was extended to 48 hours, clear peaks corresponding to In(OH)3 gradually appeared. The reflections at 22.26°, 31.69°, 39.07°, 49.43°, 51.15°, and 56.45° corresponded to the (200), (220), (222), (411), (420), and (422) crystal planes of In(OH)3 (PDF#85-1338), respectively, confirming that MIL-68(In) was completely transformed into crystalline In(OH)3. This transformation can be attributed to an alkaline 2-methylimidazole solution, in which the imidazole groups etch the organic linkers of MIL-68(In), exposing the metal center, which then reacts with hydroxyl groups to generate In(OH)3.

[0026] Observation of sample microstructure using SEM ( Figure 2 AC), the original MIL-68(In) has a smooth hexagonal rod-like structure, consistent with the literature; the IM sample surface exhibits a layered "folded" structure, and after complete conversion to In(OH)3, its morphology becomes an irregular aggregate, exhibiting a cubic shape. EDS elemental distribution map of the IM sample ( Figure 2 (D) The C, O, and In elements retain their rectangular outlines, indicating that a portion of the MIL-68(In) framework was preserved during the partial transformation. TEM analysis further reveals the structural features of the IM sample. Figure 2 F), where the 0.253 nm lattice fringes correspond to the (013) crystal plane of In(OH)3, confirming the presence of crystalline In(OH)3; the lattice fringes in adjacent regions are broken and disordered, which is evident in Figure 2 Further confirmation was obtained in G, where the figure shows diffuse rings rather than clear spots. This provides strong evidence for the coexistence of amorphous MIL-68(In) and crystalline In(OH)3. The formation of a distinct interface between the two phases indicates strong interfacial interactions, which may play a crucial role in enhancing catalytic performance.

[0027] Figure 3 Fourier transform infrared spectroscopy showed that the IM sample was within the range of 1300-1500 cm⁻¹. -1 The characteristic absorption band of MIL-68(In) is retained within the range, but at 1400 cm⁻¹ -1 The weakening intensity in the vicinity and the disappearance of the characteristic peak at 540 cm⁻¹ indicate that 2-methylimidazole etching resulted in partial loss of the organic linker. 750 cm⁻¹ -1The OH vibration peaks and overall spectrum appearing nearby are similar to those of In(OH)3, with the 505 cm⁻¹ peak being particularly prominent. -1 and 1385 cm -1 The In-OH vibration peak at the position provides direct evidence for the formation of In(OH)3. XPS analysis ( Figure 3 BF indicates that the carbon content of IM is lower than that of MIL-68(In), further confirming that the linking groups were etched, exposing more indium centers as active sites. In the In 3d spectrum, the In 3d... 5 / 2 and In 3d 3 / 2 The binding energy of indium shifts to a lower value relative to that of MIL-68(In), indicating an increase in electron density around indium, which stems from the removal of organic ligands and the formation of coordinated unsaturated indium species. In the O 1s spectrum, both IM and In(OH)3 samples shift towards lower binding energies compared to MIL-68(In), possibly attributed to interfacial electronic interactions and efficient charge transfer between them. N2 adsorption-desorption results ( Figure 3 F) shows that the BET surface area of ​​IM (214.25 m² / g) is significantly higher than that of MIL-68(In) (44.52 m² / g). 2 / g) and In(OH)3 (66.05 m 2 / g).

[0028] Example 2: Photocatalytic performance of In(OH)3 / aMIL-68(In)

[0029] 1. In(OH)3 / aMIL-68(In) photocatalytic experiment

[0030] The photocatalytic removal performance of CIP by MIL-68(In), IM, and In(OH)3 was investigated experimentally. All experiments were conducted at 25 °C with stirring at 200 rpm. The instruments used were a 500 W xenon lamp simulating daylight with a cutoff filter for wavelengths less than 400 nm and an ultraviolet spectrophotometer.

[0031] Photocatalytic performance experiment: With or without the addition of 0.8 g potassium persulfate (PS), in 30 mL of CIP solution (25 mg / L) -1 Photocatalysts MIL-68(In), IM, and In(OH)3 (at pH=7) were added to achieve a concentration of 1 mg / mL. -1 A 60-minute photocatalytic test was conducted. The degraded solution was filtered through a 0.22 μm filter after adsorption and after light exposure, and the absorbance of the solution was then measured.

[0032] 2. Evaluation of the photocatalytic performance of In(OH)3 / aMIL-68(In)

[0033] like Figure 4 As shown in Figure A, after 60 minutes of visible light irradiation alone, the removal rate of CIP was only 4.81%, indicating that its photolysis effect was negligible. However, the degradation efficiency was significantly improved after adding catalysts MIL-68(In), IM, and In(OH)3, with IM achieving the best removal rate of 50.60% under the same conditions.

[0034] The effects of different catalysts, MIL-68(In), IM, and In(OH)3, on the activation of PS (persulfate) were further investigated. Figure 4 B). In the presence of visible light and PS, IM achieved a removal efficiency of 91.90% for CIP within 60 minutes, far exceeding the levels of MIL-68(In) and In(OH)3.

Claims

1. An In(OH)3 / MIL-68(In) composite material, characterized in that, The preparation method is as follows: Step 1: Synthesis of MIL-68(In): In(NO3)3·xH2O and terephthalic acid were dissolved in DMF, the mixture was subjected to hydrothermal reaction, the resulting precipitate was washed and dried under vacuum to obtain MIL-68(In); Step 2: Synthesis of In(OH)3 / aMIL-68(In): MIL-68(In) was ultrasonically dispersed in an aqueous solution of 2-methylimidazole, allowed to stand at room temperature, washed and dried to obtain In(OH)3 / aMIL-68(In).

2. The In(OH)3 / MIL-68(In) composite material according to claim 1, characterized in that, In step 1, the mass ratio or molar ratio of In(NO3)3·xH2O to terephthalic acid is 1:

1.

3. The In(OH)3 / MIL-68(In) composite material according to claim 1, characterized in that, In step 1, the hydrothermal reaction is carried out at 100 °C for 48 h.

4. The In(OH)3 / MIL-68(In) composite material according to claim 1, characterized in that, In step 2, the mass ratio of MIL-68(In) to 2-methylimidazole is 1:19-20, and the concentration of the 2-methylimidazole aqueous solution is 0.6 mol / L.

5. The application of the In(OH)3 / MIL-68(In) composite material according to any one of claims 1-4 in the photocatalytic degradation of ciprofloxacin.

6. The application according to claim 5, characterized in that, The method is as follows: In a solution containing ciprofloxacin, with or without the addition of persulfate, an In(OH)3 / MIL-68(In) composite material as described in any one of claims 1-4 is added for photocatalytic degradation.

7. The application according to claim 6, characterized in that, The method is as follows: the concentration of ciprofloxacin is 20-30 mg / L. -1 The concentration of the In(OH)3 / MIL-68(In) composite material is 0.8-1.2 mg / mL. -1 .

Images