Application of AgI-coated Eu-MOF-based composite material in fluorescence detection and photocatalysis of tetracycline

Abstract

The invention discloses application of a composite material based on AgI (at) Eu-MOF in fluorescence detection and photocatalysis of tetracycline, in the composite material, the structural unit of Eu-MOF is [Eu2 (BPC) 2 (NBDC) (H2O) 2] 4H2O, BPDC represents 2, 2 '-bipyridine-5, 5'-dicarboxylate radicals with protons lost on two carboxyl groups, and NBDC represents 2-amino-terephthalic acid radicals with protons lost on two carboxyl groups. The composite material powder has excellent red fluorescence performance and shows bright red color under the irradiation of an ultraviolet lamp. In an aqueous solution, the fluorescent dye has a blue fluorescence property. The blue fluorescence of the composite material can be quenched by tetracycline, and the composite material can be used as a catalyst for photocatalysis of tetracycline. Therefore, the composite material can be used for detection and catalysis of tetracycline, and has good photocatalytic recycling performance.

Description

Technical Field

[0001] The invention belongs to the technical field of detection and catalysis of tetracycline, and specifically relates to an application of an AgI@Eu-MOF composite material in fluorescence detection and photocatalysis of tetracycline. Background Art

[0002] Tetracycline is widely used in human medicine, veterinary medicine, agriculture, and aquaculture. Excessive discharge poses potential hazards to the ecosystem, so ultrasensitive detection and efficient catalytic degradation of tetracycline play a very important role. At present, the main methods used to detect tetracycline at home and abroad are high-performance liquid chromatography (HPLC), gas chromatography (GC), enzyme-linked immunosorbent assay (ELISA), mass spectrometry (MS), fluorescence spectroscopy, polymerase chain reaction (PCR) technology, etc. These methods can realize the detection of tetracycline, but there are also some shortcomings, such as complex operation, high cost, differences in sensitivity and specificity, and strict requirements for sample pretreatment. Therefore, achieving sensitive detection and catalytic degradation of tetracycline is still a big challenge.

[0003] Fluorescence sensors are favored by scientific researchers due to their convenient operation, fast analysis speed, high sensitivity, high selectivity and low detection limit. Fluorescent probe materials refer to a class of fluorescent molecules that have characteristic fluorescence in the ultraviolet-visible-near infrared region, and whose fluorescence properties (excitation and emission wavelengths, intensity, lifetime, polarization, etc.) can change sensitively with the properties of the environment, such as polarity, refractive index, viscosity, etc. Lanthanide metal organic framework materials are composed of organic ligands and lanthanide metal atoms through coordination bonds. There is a ligand-metal energy transfer process in its system, which can realize the luminescence of lanthanide atoms by exciting ligands, thereby effectively sensitizing the luminescence process of lanthanide atoms and effectively enhancing the luminescence intensity of lanthanide atoms. Lanthanide metal organic compounds can be used to detect various inorganic ions, organic molecules, etc. due to their unique luminescence principle. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a new application based on AgI@Eu-MOF composite materials.

[0005] The technical solution adopted to solve the above technical problems is: the application of the above-mentioned AgI@Eu-MOF composite material in the detection and photocatalytic degradation of tetracycline, in which the structural unit of Eu-MOF is [Eu2(BPDC)2(NBDC)(H2O)2]∙4H2O, wherein BPDC represents 2,2'-bipyridine-5,5'-dicarboxylate with two carboxyl groups losing protons, and NBDC represents 2-amino-terephthalate with two carboxyl groups losing protons, which belongs to the monoclinic system and has a space group of P 21 / c, the unit cell parameters are a = 9.3853(10) Å, b = 10.5808(10) Å, c = 20.9376(2) Å, β = 95.8860(10)°, and the unit cell volume V = 2068.23(4) Å 3 , Z = 4, which is prepared according to the following method:

[0006] Eu(NO3)3∙6H2O, 2,2'-bipyridine-5,5'-dicarboxylic acid, and 2-amino-terephthalic acid were mixed in a molar ratio of 1:1:1 and dissolved in a mixed solution of 1:1 N,N-dimethylformamide and deionized water by ultrasonication at 160 o C was reacted for three days, cooled to room temperature, and washed with deionized water and ethanol to obtain Eu-MOF; then the Eu-MOF aqueous solution was added to potassium iodide, magnetically stirred for one hour, and then a silver nitrate solution was added. After vigorous stirring for 12 hours in the dark, the product was collected by centrifugation, washed with ethanol three times, and the obtained sample was dried for 6 hours to obtain a dry AgI@Eu-MOF composite material.

[0007] The beneficial effects of the present invention are as follows:

[0008] 1. The AgI@Eu-MOF composite material powder used in the present invention shows red luminescence under ultraviolet light. Fluorescence excitation is performed at 330 nm, and there is an obvious fluorescence emission peak at 616 nm.

[0009] 2. The AgI@Eu-MOF composite material water suspension used in the present invention shows blue luminescence under ultraviolet light. Fluorescence excitation is performed at 330 nm, and there is an obvious fluorescence emission peak at 440 nm.

[0010] 3. The AgI@Eu-MOF composite material used in the present invention can achieve high-sensitivity detection and photocatalytic degradation of tetracycline in aqueous solution, and has good recyclability for photocatalytic degradation of tetracycline. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the structure of Eu-MOF in the AgI@Eu-MOF composite material of the present invention.

[0012] Figure 2 It is a fluorescence image of the AgI@Eu-MOF composite material solid powder of the present invention.

[0013] Figure 3 It is a fluorescence image of the AgI@Eu-MOF composite material of the present invention in aqueous solution.

[0014] Figure 4This is a diagram showing the selective detection effect of the AgI@Eu-MOF composite material of the present invention in aqueous solution.

[0015] Figure 5 This is a fluorescence effect diagram of the AgI@Eu-MOF composite material of the present invention for detecting tetracycline in an aqueous solution.

[0016] Figure 6 It is a linear fitting diagram of the AgI@Eu-MOF composite material of the present invention for detecting tetracycline in aqueous solution.

[0017] Figure 7 This is an anti-interference diagram of the AgI@Eu-MOF composite material of the present invention for detecting tetracycline in aqueous solution.

[0018] Figure 8 This is a tetracycline photocatalytic effect diagram of the AgI@Eu-MOF composite material of the present invention.

[0019] Fig. 9 This is a photocatalytic effect diagram of the AgI@Eu-MOF composite material of the present invention after 5 cycles. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited to these embodiments. Example 1

[0021] Eu(NO3)3∙6H2O (0.1 mmol, 0.0446 g), 2,2'-bipyridine-5,5'-dicarboxylic acid (0.1 mmol, 0.0244 g), and 2-amino-terephthalic acid (0.1 mmol, 0.0181 g) were dissolved in N,N-dimethylformamide (2.0 mL) and deionized water (2.0 mL) at 160 °C. o After three days of reaction in a C oven, the product was washed three times with deionized water and ethanol to obtain a colorless and transparent Eu-MOF. Figure 1 As shown, its structure is [Eu2(BPDC)2(NBDC)(H2O)2]∙4H2O, where BPDC represents 2,2'-bipyridine-5,5'-dicarboxylate with two carboxyl groups losing protons, and NBDC represents 2-amino-terephthalate with two carboxyl groups losing protons. It belongs to the monoclinic system and has a space group of P 21 / c , the unit cell parameters are a = 9.3853(10) Å, b = 10.5808(10) Å, c = 20.9376(2) Å, β = 95.8860(10)°, and the unit cell volume V = 2068.23(4) Å 3 , Z =4.

[0022] 0.0160 g Eu-MOF was dispersed in 35 mL deionized water, 0.0049 g KI was added to the resulting mixture, and after magnetic stirring for one hour, 0.148 mL 0.2 mol∙L −1 AgNO3 aqueous solution. The solution was stirred vigorously for 12 hours in the dark. The product was collected by centrifugation at 8000 rpm for 3 minutes and washed with deionized water and ethanol three times to obtain AgI@Eu-MOF composite material.

[0023] Example 2 is an application of the AgI@Eu-MOF composite material based on Example 1 in tetracycline detection and photocatalysis.

[0024] 1. Solid-state fluorescence performance test

[0025] The AgI@Eu-MOF powder was excited at 330 nm and the solid-state fluorescence performance was tested. The test results are shown in Figure 2 .Depend on Figure 2 It can be seen that there are obvious Eu at 579 nm, 592 nm, 616 nm, 653 nm and 700 nm. 3+ Characteristic emission peaks, corresponding to 5 D0→ 7 F0, 5 D0→ 7 F1, 5 D0→ 7 F2, 5 D0→ 7 F3 and 5 D0→ 7 F4 transition, indicating that the composite material emits red light.

[0026] 2. Liquid fluorescence performance test

[0027] 0.2 mg of AgI@Eu-MOF composite was ultrasonically treated in 1 mL of water for 60 min to obtain a concentration of 0.2 mg∙mL −1 AgI@Eu-MOF suspension. 1 mL 0.2 mg∙mL −1 The AgI@Eu-MOF suspension was excited at 330 nm and the liquid fluorescence performance was tested. The test results are shown in Figure 3 .Depend on Figure 3 It can be seen that there is an obvious emission peak at 440 nm, indicating that the composite material emits blue light.

[0028] 3. Selective detection of aniline in water

[0029] 1 mL 0.2 mg∙mL −1 0.1 mL 10−2 mol∙L −1 Sulfadiazine, sulfadiazine, thiamphenicol, chloramphenicol, kanamycin sulfate, and tetracycline were added to make the final concentration of antibiotics in the suspension 0.909 mmol∙L −1 , and conduct fluorescence test. Record the fluorescence intensity I0 and I of the suspension before and after adding at 440 nm (excitation wavelength is 330 nm). The results are shown in Figure 4 .

[0030] Depend on Figure 4 It can be seen that in the AgI@Eu-MOF suspension, the order of antibiotic quenching rate from large to small is: tetracycline, chloramphenicol, sulfamethoxazole, sulfadiazine, thiamphenicol, and kanamycin sulfate. This shows that among the above antibiotics, only tetracycline has a significant quenching effect on the luminescence of the AgI@Eu-MOF suspension, that is, the composite material can be used to highly selectively detect tetracycline in aqueous solution.

[0031] 4. Fluorescence detection of tetracycline in aqueous solution

[0032] Weigh 0.0222 g of tetracycline and dissolve it in 5 ml of water to prepare 1´10 −2 mol∙L −1 Tetracycline aqueous solution, diluted 10 times to obtain 1´10 −3 mol∙L −1 Tetracycline aqueous solution. Take 1 mL 0.2 mg∙mL −1 The aqueous suspension of AgI@Eu-MOF was placed in a quartz cuvette, and 10 μL of 10 −3 mol∙L −1 Tetracycline aqueous solution was added 10 times in total, and the concentration of tetracycline varied from 0 to 0.909´10 −4 mol∙L −1 After each drop, the fluorescence spectrum was tested and the fluorescence intensity of the suspension at 440 nm was recorded. The excitation wavelength was fixed at 330 nm. Figure 5 , 6 .

[0033] Depend on Figure 5 It can be seen that the luminescence intensity of Eu (III) ions gradually weakens with the increase of tetracycline addition. Figure 6 In the example, I0 / I = 1+K sv The quenching effect was further fitted by the Stern-Volmer (SV) equation of [C], where I0 is the initial fluorescence intensity; I is the fluorescence intensity after adding the analyte. Ksv is the quenching constant and [C] is the molar concentration of tetracycline. The SV curve is between 9.9 and 74.1 μmol∙L −1 There is an approximate linear relationship between 2= 0.991), the linear equation is (I0-I) / I = 2.1576´10 4 [C]. Calculated K sv 2.1576´10 4 M −1 The detection limit (LOD) was 0.117 μmol∙L −1 (LOD = 3σ / k, σ =0.0008413), indicating that the composite material can detect tetracycline with high sensitivity.

[0034] 5. Anti-interference detection of tetracycline

[0035] Take 1 mL of 0.2 mg∙mL −1 The aqueous suspension of AgI@Eu-MOF composite material was placed in a quartz cuvette, and then 10 μL of 10 −1 mol∙L −1 Interfering ions (Na + , K + NH4 + 、Al 3+ , Ba 2+ , Cl − 、NO3 − 、SO4 2− , L-histidine, tyrosine, glutamic acid, sulfamethoxazole, thiamphenicol aqueous solution and tetracycline aqueous solution (interfering ion concentration in the solution is 0.90´10 −3 mol∙L −1 , tetracycline concentration is 0.90´10 −3 mol∙L −1 ) and tested the fluorescence spectrum, with an excitation wavelength of 330 nm and a characteristic peak at 440 nm. Figure 7 As can be seen from the figure, in Na + , K + NH4 + 、Al 3+ , Ba 2+ , Cl − 、NO3 − 、SO4 2− In aqueous solutions of 1, 2-histidine, tyrosine, glutamic acid, sulfamethoxazole, and thiamphenicol, the fluorescence intensity of the AgI@Eu-MOF composite material did not change significantly; when tetracycline was added, the blue fluorescence of the composite material disappeared immediately, and the fluorescence intensity decreased significantly. This shows that when anti-interference substances coexist, it does not affect the detection of tetracycline by the composite material, that is, the composite material has high selectivity and anti-interference for tetracycline.

[0036] 6. Real sample testing

[0037] Tap water and centrifuged lake water were selected as real samples and 10 −3 mol∙L −1 Tetracycline solution of concentration. Add 1 mL of 0.2 mg∙mL −1 20, 42, and 64 μL of 10 −3 mol∙L −1 Tetracycline aqueous solution (final concentration in solution was 20, 40, 60 μmol∙L −1 ). The excitation wavelength was 330 nm, and the fluorescence intensity at 440 nm was recorded in the detection of tetracycline real samples, and the recovery was calculated based on the obtained linear relationship. The calculation shows that the recovery of the spiked samples in this study is between 95.01% and 102.84%, and the calculated standard deviation (RSD) is < 3%. The small RSD indicates that the AgI@Eu-MOF composite material has good reliability in the actual detection application of tetracycline.

[0038] 7. Photocatalytic degradation of tetracycline

[0039] 10 mg of AgI@Eu-MOF composite was added into 50 mL of 20 mg∙L −1 In the tetracycline aqueous solution, magnetic stirring was continued for one hour under dark conditions, and then the tetracycline was photocatalytically degraded under visible light to obtain Figure 8 .from Figure 8 It can be seen that the photocatalytic efficiency of AgI@Eu-MOF composite material in degrading tetracycline is 83.9%, indicating that the composite material has high tetracycline photodegradation performance as a catalyst.

[0040] 8. Photocatalytic cyclic degradation of tetracycline

[0041] AgI@Eu-MOF composite material was used as a photocatalyst to test the catalytic degradation of tetracycline. After each test, the photocatalyst AgI@Eu-MOF was collected by centrifugation, washed with ethanol, and then dried at 60°C for 5 hours. Finally, it was reused in the next test under the same experimental conditions. The experimental details in the cycle experiment were exactly the same as the first cycle test. The cycle was repeated 5 times in sequence, and the results are shown in Fig. 9 .Depend on Fig. 9 It can be seen that the catalytic efficiency of the composite material remains basically unchanged after being recycled for 5 times, indicating that the composite material has good recyclability as a photocatalyst for the catalytic degradation of tetracycline.

Claims

1. Based on the application of AgI@Eu-MOF composite materials in fluorescence detection and photocatalysis of tetracycline, the structural unit of Eu-MOF in this composite material is [Eu2(BPDC)2(NBDC)(H2O)2]∙4H2O, where BPDC represents 2,2'-bipyridine-5,5'-dicarboxylate with two carboxyl groups losing protons, and NBDC represents 2-amino-terephthalate with two carboxyl groups losing protons. It belongs to the monoclinic system with a space group of P 21 / c , the unit cell parameters are a = 9.3853(10) Å, b = 10.5808(10) Å, c = 20.9376(2) Å, β = 95.8860(10)°, and the unit cell volume V = 2068.23(4) Å 3 , Z = 4.

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