Sensing base material for driving ordered distribution of dioxin in spatial confinement and preparation method of sensing base material

Abstract

The invention discloses a sensing base material for driving ordered distribution of dioxin in a spatial confinement range and a preparation method thereof. The preparation method comprises the following steps: preparing an MOF matrix based on a binary mixed ligand, directionally regulating and controlling a vertical pore channel, hydrophobically modifying-CF3, and regulating and controlling competitive coordination doping. The invention provides a triple strategy of'mixed ligand + post-modification + defect control 'based on a synergistic effect of'gradient modification + vertical confinement'. Through the strategy, the performance is obviously improved in the adsorption application of a typical dioxin compound 2, 3, 7, 8-TCDD. Meanwhile, the material prepared by the invention can effectively drive ordered distribution of 2, 3, 7, 8-TCDD in a vertical pore channel, and provides a key basic material for stable SERS (Surface Enhanced Raman Scattering) sensing analysis.

Description

Technical Field

[0001] The present invention relates to the field of chemical detection technology, and more particularly to a sensing base material capable of driving the orderly distribution of dioxins through spatial confinement and a preparation method thereof. Background Art

[0002] Persistent organic pollutants, exemplified by dioxins, are present in extremely low concentrations, are highly lipophilic, and exhibit teratogenic, carcinogenic, and mutagenic toxicity. High-performance sensing and analysis of these pollutants is urgently needed. Among numerous analytical techniques, surface-enhanced Raman spectroscopy (SERS) offers unique advantages for highly sensitive analysis of dioxin-like compounds. Regulating the adsorption properties of SERS-enhanced substrates for target compounds is crucial, while obtaining base materials with high-capacity capture, rapid mass transfer, and selective recognition properties for dioxin-like compounds is crucial for their preparation.

[0003] Existing MOF materials for dioxin adsorption have many limitations. Most materials are constructed with a single ligand (such as MIL-101) or have unfunctionalized structures (such as ZIF-8). In practical applications, these materials have exposed problems such as low adsorption capacity, insufficient selectivity, and the need for improved recycling performance. For example, the adsorption capacity is generally less than 3×10 2 pg / mg, the selectivity coefficient is usually less than 5, and the number of cycles is difficult to exceed 8 times.

[0004] Therefore, how to overcome the defects of the prior art and provide a new material or method is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In light of this, the present invention leverages the synergistic effects of "gradient modification + vertical confinement" to propose a triple strategy of "mixed ligands + post-modification + defect control." This strategy significantly improves adsorption performance for the typical dioxin compound 2,3,7,8-TCDD. Furthermore, the material prepared in this invention effectively promotes the orderly distribution of 2,3,7,8-TCDD within vertical channels, providing a key foundation for stable SERS sensing analysis.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] First, the present invention provides a method for preparing a sensing base material that spatially confines and drives the orderly distribution of dioxins, comprising the following steps:

[0008] Step 1: Preparation of MOF matrix based on binary mixed ligands

[0009] (1.1) Dissolve zirconium chloride hexahydrate in N,N-dimethylformamide and sonicate for 15 min. Mix 2,6-naphthalenedicarboxylic acid and 1,3,5-benzenetricarboxylic acid, add acetic acid / DMF solution, and mix at 60°C for 2 h.

[0010] (1.2) The two solutions prepared in step (1.1) were mixed and transferred to an autoclave. The temperature was raised to 120±5°C at 2°C / min, maintained at this temperature for 30±0.5h, and then lowered to 55°C at 1°C / min.

[0011] (1.3) The reaction product was removed and centrifuged at 5000 rpm for 20 min. The precipitate was collected, washed three times with DMF and methanol, and dried under vacuum at 60°C for 20 h to obtain the primary MOF, i.e., Zr-MOF-1.

[0012] Step 2: Vertical channel directional control

[0013] (2.1) Ultrasonic dispersion of Zr-MOF-1 in ethanol;

[0014] (2.2) Vertically immerse the porous alumina template in the dispersion prepared in step (2.1), and then apply a 10-15 V DC current for 30 min;

[0015] (2.3) Etch the remaining aluminum oxide on the surface with 0.1 M NaOH solution to ensure that the (001) crystal plane diffraction peak intensity ratio is >3:1 as detected by X-ray diffraction and the vertical deviation of the pore arrangement direction is <5° as observed by scanning electron microscopy;

[0016] Step 3: -CF3 hydrophobic modification

[0017] (3.1) The Zr-MOF-1 treated in step 2 was dehydrated and activated at 150°C in vacuum for 6 hours, then placed in a closed reactor with pentafluorobenzoyl chloride liquid at the bottom. The reactor was heated to 80°C and maintained at a pressure of 0.20±0.02 MPa for 12 hours.

[0018] (3.2) Wash with anhydrous ether three times and dry in vacuo at 40 °C to obtain CF3-modified MOF, namely Zr-MOF-2;

[0019] Step 4: Competitive coordination doping regulation

[0020] Zr-MOF-2 was redispersed in a DMF solution containing 1,2,4-benzenetricarboxylic acid, refluxed at 90°C for 24 hours, and the solid was recovered by centrifugation, washed three times with methanol, and dried with supercritical CO2 to obtain the final product Zr-MOF-3.

[0021] Preferably, it is characterized in that the molar ratio of zirconium chloride hexahydrate, 2,6-naphthalenedicarboxylic acid and 1,3,5-benzenetricarboxylic acid in step (1.1) is 4:3:2.

[0022] Preferably, the volume ratio of acetic acid to DMF in the acetic acid / DMF solution in step (1.1) is 1:4.

[0023] Preferably, in step (2.1), the concentration of Zr-MOF-1 in ethanol is 0.5-1 mg / mL.

[0024] Preferably, the pore size of the porous alumina template in step (2.2) is 200 nm.

[0025] Preferably, in step (3.1), the ratio of Zr-MOF-1 to pentafluorobenzoyl chloride is 5 mmol / g.

[0026] Preferably, the concentration of 1,2,4-benzenetricarboxylic acid in DMF solution in step 4 is 2 mg / mL.

[0027] Preferably, the amount of 1,2,4-benzenetricarboxylic acid added in step 4 is 15±0.5% of the molar amount of 1,3,5-benzenetricarboxylic acid.

[0028] Preferably, in step 4, the supercritical CO2 drying temperature is 32°C, the pressure is 10 MPa, the CO2 flow rate is 2.0±0.1 L / min, and the time is 6 h.

[0029] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a sensing base material that can drive the orderly distribution of dioxins through spatial confinement and a preparation method thereof, which has the following beneficial effects:

[0030] This invention innovates the triple strategy of "mixed ligand + post-modification + defect control" and achieves an adsorption capacity of 8.72×10 3 The MOF material prepared by this method can be used as a molecular pre-enrichment layer on the surface of coinage metal nanostructures to construct a composite sensing substrate suitable for surface-enhanced Raman spectroscopy (SERS) sensing analysis, greatly improving the reliability of SERS sensing analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 Preparation flow chart. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1

[0035] Step 1: Preparation of MOF matrix based on binary mixed ligands

[0036] (1.1) Zirconium chloride hexahydrate (ZrCl4·6H2O, 0.8 mmol, purity ≥99.9%) was dissolved in 20 mL of N,N-dimethylformamide (DMF) and sonicated for 15 min. 2,6-Naphthalenedicarboxylic acid (NDC, purity ≥98%) and 1,3,5-Benzenetricarboxylic acid (BTC, purity ≥99%) were mixed in a 3:2 molar ratio (e.g., 0.6 mmol:0.4 mmol). 20 mL of acetic acid in DMF (acetic acid / DMF (v / v) = 1:4) was added, and the mixture was mixed at 60°C for 2 h.

[0037] (1.2) Mix the two solutions and transfer them to an autoclave. Raise the temperature to 120±5°C at a rate of 2°C / min, maintain the temperature for 30±0.5h, and then cool to 55°C at a rate of 1°C / min.

[0038] (1.3) Centrifuge at 5000 rpm for 20 min, collect the precipitate, wash with DMF and methanol three times, and dry in vacuo at 60°C for 20 h to obtain the primary MOF (Zr-MOF-1).

[0039] Step 2: Vertical channel directional control

[0040] (2.1) Zr-MOF-1 was ultrasonically dispersed in ethanol (1 mg / mL).

[0041] (2.2) A porous alumina template (pore size 200 nm) was vertically immersed in the dispersion. A 10 V direct current was then applied for 30 min.

[0042] (2.3) Use a 0.1 M NaOH solution to slightly etch the remaining aluminum oxide on the surface. Ensure that the (001) diffraction peak intensity ratio is >3:1 as determined by X-ray diffraction (XRD) and that the vertical deviation of the pore arrangement is <5° as determined by scanning electron microscopy (SEM). If the SEM shows a pore tilt >10°, adjust the electric field strength to 15 V and reduce the Zr-MOF-1 dispersion concentration to 0.5 mg / mL.

[0043] Step 3: -CF3 hydrophobic modification

[0044] (3.1) Zr-MOF-1 was activated by vacuum dehydration at 150°C for 6 h and then placed in a sealed reactor with pentafluorobenzoyl chloride (5 mmol / g) at the bottom. The reaction mixture was heated to 80°C and maintained at a pressure of 0.20 ± 0.02 MPa for 12 h.

[0045] (3.2) Wash three times with anhydrous ether and dry under vacuum at 40°C to obtain CF3-modified MOF (Zr-MOF-2). The recovery rate of pentafluorobenzoyl chloride is >95%. X-ray photoelectron spectroscopy (XPS) detection of the F1s peak intensity indicates a F content of 8.7 wt%. The water contact angle test shows a >130° contact angle. If the RSD of the F element distribution detected by XPS is >15%, pulsed vapor deposition is used with a 1 h heating and 0.5 h cooling cycle.

[0046] Step 4: Competitive coordination doping regulation

[0047] (4.1) Redisperse Zr-MOF-2 in a DMF solution containing 1,2,4-benzenetricarboxylic acid (2 mg / mL), controlling the amount of 1,2,4-benzenetricarboxylic acid to be 15 ± 0.5% of the molar weight of BTC. Reflux at 90°C for 24 h.

[0048] (4.2) Recover the solid by centrifugation and wash it with methanol three times.

[0049] (4.3) Supercritical CO2 drying was performed for 6 h (32°C, 10 MPa) at a CO2 flow rate of 2.0±0.1 L / min to obtain the final product (Zr-MOF-3). The SEM characterization showed a size of 1-5 μm, a thermogravimetric analysis weight loss of 12-15%, and a pore size distribution of 1.5±0.2 nm. The yield of a single reaction was ≥5 g, with a yield of >70%.

[0050] Experimental example

[0051] Performance Verification

[0052] 1. Adsorption performance test

[0053] Prepare a 2,3,7,8-TCDD standard solution (concentration gradient: 0.1-1000 pg / mL). Add 10 mg of Zr-MOF-DF to 10 mL of sample solution and adsorb at 25°C for 2 h. Analyze residual concentrations by HPLC-MS / MS. The maximum adsorption capacity of the Langmuir model is ≥8.5 × 10 3 pg / mg, adsorption equilibrium time <30min.

[0054] 2. Select Performance Test

[0055] Dry polychlorinated biphenyls (PCB-77), benzo[a]pyrene, and phthalates were selected as test interfering substances. The concentration of each interfering substance was 10 times that of 2,3,7,8-TCDD, and the test result selectivity coefficient (2,3,7,8-TCDD / interfering substance) was >30.

[0056] 3. Cycle Test

[0057] The adsorbed MOF was treated with a supercritical CO2 / ethanol (9:1) mixed fluid at 40°C for 1 h, and the adsorption capacity was >90% after 20 cycles.

[0058] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a sensing base material that drives the orderly distribution of dioxins by spatial confinement, characterized in that: The following steps are involved: Step 1: Preparation of MOF matrix based on binary mixed ligands (1.1) Dissolve zirconium chloride hexahydrate in N,N-dimethylformamide and sonicate for 15 min. Mix 2,6-naphthalenedicarboxylic acid and 1,3,5-benzenetricarboxylic acid, add acetic acid / DMF solution, and mix at 60°C for 2 h. (1.2) The two solutions prepared in step (1.1) were mixed and transferred to an autoclave. The temperature was raised to 120±5°C at 2°C / min, maintained at this temperature for 30±0.5h, and then lowered to 55°C at 1°C / min. (1.3) The reaction product was removed and centrifuged at 5000 rpm for 20 min. The precipitate was collected, washed three times with DMF and methanol, and dried under vacuum at 60°C for 20 h to obtain the primary MOF, i.e., Zr-MOF-1. Step 2: Vertical channel directional control (2.1) Ultrasonic dispersion of Zr-MOF-1 in ethanol; (2.2) Vertically immerse the porous alumina template in the dispersion prepared in step (2.1), and then apply a 10-15 V DC current for 30 min; (2.3) Etch the remaining aluminum oxide on the surface with 0.1 M NaOH solution to ensure that the (001) crystal plane diffraction peak intensity ratio is >3:1 as detected by X-ray diffraction and the vertical deviation of the pore arrangement direction is <5° as observed by scanning electron microscopy; Step 3: -CF3 hydrophobic modification (3.1) The Zr-MOF-1 treated in step 2 was dehydrated and activated at 150°C in vacuum for 6 hours, then placed in a closed reactor with pentafluorobenzoyl chloride liquid at the bottom. The reactor was heated to 80°C and maintained at a pressure of 0.20±0.02 MPa for 12 hours. (3.2) Wash with anhydrous ether three times and dry in vacuo at 40 °C to obtain CF3-modified MOF, namely Zr-MOF-2; Step 4: Competitive coordination doping regulation Zr-MOF-2 was redispersed in a DMF solution containing 1,2,4-benzenetricarboxylic acid, refluxed at 90°C for 24 hours, and the solid was recovered by centrifugation, washed three times with methanol, and dried with supercritical CO2 to obtain the final product Zr-MOF-3.

2. The method for preparing a sensing base material for spatially confined driving dioxin orderly distribution according to claim 1, characterized in that: In step (1.1), the molar ratio of zirconium chloride hexahydrate, 2,6-naphthalenedicarboxylic acid and 1,3,5-benzenetricarboxylic acid is 4:3:

2.

3. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: The volume ratio of acetic acid to DMF in the acetic acid / DMF solution in step (1.1) is 1:

4.

4. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: In step (2.1), the concentration of Zr-MOF-1 in ethanol is 0.5-1 mg / mL.

5. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: The pore size of the porous alumina template in step (2.2) is 200 nm.

6. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: In step (3.1), the ratio of Zr-MOF-1 to pentafluorobenzoyl chloride is 5 mmol / g.

7. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: Step 4 contains 1,2,4-benzenetricarboxylic acid in DMF solution at a concentration of 2 mg / mL.

8. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: In step 4, the amount of 1,2,4-benzenetricarboxylic acid added is 15±0.5% of the molar amount of 1,3,5-benzenetricarboxylic acid.

9. The method for preparing a sensing base material for spatially confined driving orderly distribution of dioxins according to claim 1, characterized in that: In step 4, the supercritical CO2 drying temperature is 32°C, the pressure is 10 MPa, the CO2 flow rate is 2.0±0.1 L / min, and the time is 6 h.

10. A basic sensing material for driving ordered distribution of dioxins by spatial confinement, prepared by the method according to any one of claims 1 to 9.

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