WO2015192387A1

WO2015192387A1 - Aqueous phase metal organic framework molecular imprinting material of enriched trace metolcarb

Info

Publication number: WO2015192387A1
Application number: PCT/CN2014/080685
Authority: WO
Inventors: 王硕; 王俊平; 钱坤; 方国臻
Original assignee: 天津科技大学
Priority date: 2014-06-19
Filing date: 2014-06-25
Publication date: 2015-12-23
Also published as: CN104014320B; CN104014320A

Abstract

The present invention relates to an aqueous phase metal organic framework molecular imprinting material of enriched trace metolcarb. The product is prepared by using the method that comprises the following steps: by using a metal organic framework material MIL-101 subjected to aqueous-phase synthesis as a supporter, metolcarb as template molecules, 3-aminopropyltriethoxysilane as a functional monomer and tetraethoxysilane as a crosslinking agent, synthesizing a precursor of MIL@MIP by means of a sol-gel method; and removing the template molecules in the precursor by means of Soxhlet extraction, so as to obtain the aqueous phase metal organic framework molecular imprinting material of enriched trace metolcarb, namely the MIL@MIP. An "imprinting hole" consistent with a space structure of a template molecule of metolcarb is obtained, and a selective identification effect on the template molecule of metolcarb is good.

Description

Aqueous phase metal organic framework molecular imprinting material enriched with trace amount of carbaryl

The invention relates to the field of novel polymer enriched materials, in particular to an aqueous phase metal organic framework molecular imprinted polymer having good adsorption and separation functions for carbamate pesticides, and a preparation method thereof. The specific surface area of the product is relatively large, which makes the mass transfer rate and adsorption amount much higher than those of the prior materials.

Background technique

Metocarb; tsumacide; metacrate, alias m-tolyl-N-methyl-carbamate, molecular formula C ₉ H _u N0 ₂ , molecular weight 165.2, pure white crystal, melting point 76- 77 °C, boiling point 180 °C, flash point 145 °C, hardly soluble in water, slightly soluble in ether, benzene, soluble in methanol and ethanol, relative density (water = 1) 1.2, decomposed in alkaline solution. It is a moderately toxic pesticide, has no chronic toxicity, no carcinogenicity, teratogenicity, mutagenic effect, is toxic to fish, and highly toxic to bees. Health hazards: moderately toxic pesticides. Symptoms of acute poisoning are headache, nausea, vomiting, loss of appetite, tearing, runny nose, severe tremors, and quadriplegia. Toxicity: Moderate toxicity to humans and animals. In recent years, the most commonly used pesticide residue detection methods include gas chromatography (GC), high performance liquid chromatography (HPLC), liquid chromatography/gas chromatography-mass spectrometry (HPLC-MS/GC-MS), and capillary electrophoresis. (CE), enzyme-linked immunosorbent assay (ELISA), etc.

Molecularly imprinting technique (MIT) is a new method for synthesizing new polymer polymeric materials that has developed rapidly in recent decades. It has the characteristics of predetermination, selective identification and practicability of targets, and has been widely used in recent years. In the fields of solid phase extraction, chromatographic separation, sensors, etc.

Metal Organic Frameworks (MOF) are a class of coordination polymers formed by self-assembly of organic ligands containing nitrogen or oxygen with metal ions. Since the mid-1990s, the first generation of metal-organic framework materials have been synthesized. This new type of material is increasingly valued by researchers around the world because of the special structure of this type of material, which makes it fascinating. Huge specific surface area, adsorption capacity, adsorption specificity, catalytic performance, etc. In 2005, Ferey et al. synthesized a new metal organic framework material MIL-101. The material is a trimer composed of Cr ³⁺ , and forms an ultra-tetrahedral structure with an organic ligand terephthalic acid, and this ultra-tetrahedral structure is used as a basic structural unit, together with terephthalic acid. Constructed as a metal organic framework material of the MTN type. The material has good stability, can reach 275 ° C, and has a high specific surface area. It is a relatively large specific surface area material discovered so far. These properties make it possible to use MIL-101 as a novel support for molecularly imprinted materials. The molecular imprinting material synthesized by the traditional bulk polymerization method requires the steps of grinding, the particle size and shape of the grinding are not regular, the mass transfer rate is slow, and the binding site may be destroyed. The core-nuclear imprinted polymer that has emerged in recent years can overcome the above disadvantages. Compared with traditional molecularly imprinted supports, MIL-101 exhibits its unique features: large specific surface area, uniform pores, strong skeleton rigidity, adjustable pore size within a certain range, and high thermal stability. MIL-101 is synthesized in the aqueous phase and has good stability to aqueous solutions. Based on these characteristics, the present invention creatively combines molecular imprinting technology with metal organic framework materials, and synthesizes a shell-core organic-inorganic hybrid material MIL@MIP in a water phase environment by sol-gel method. It is intended to further optimize and improve the performance of molecularly imprinted polymers for wider application in practical testing. Summary of the invention

In view of the potential application of molecular imprinting technology combined with metal organic framework materials, the technical problem to be solved by the present invention is to provide an aqueous phase metal organic framework molecular imprinting material which has good adsorption and selection functions for fast-acting molecules and preparation thereof. method.

The technical solution adopted by the invention is:

An aqueous phase metal organic framework molecularly imprinted material (MIL@MIP) enriched in trace amount of carbaryl, which is prepared by a method comprising the following steps: metal organic framework material MIL synthesized by activated aqueous phase -101 is a support, acesulfame is a template molecule, 3-aminopropyltriethoxysilane (APTES) is a functional monomer, and tetraethoxysilane (TEOS) is a crosslinking agent, synthesized by a sol-gel method. The precursor of MIL@MIP; then the Soxhlet extraction is used to remove the template molecules from the precursor, which is MIL@MIP.

Specifically, in the preparation of MIL@MIP, the catalyst used was 0.2 mol/L of acetic acid, and the solvent was tetrahydrofuran.

Specifically, the amount of the MIL-101 after the support is activated is 0.050 g, and the amount of the template molecule acesulfame is 1.0 mmol, and the amount of the functional monomer 3-aminopropyltriethoxysilane is 600 μί, The amount of the tetraethoxysilane used is 700 μί, the amount of the acetic acid solution of the catalyst 0.2 mol/L is 1.0 mL, and the amount of the solvent tetrahydrofuran is 3.0 mL.

Specifically, the aqueous phase metal organic framework molecularly imprinted material (MIL@MIP) enriched in trace amount of acesulfame has a particle diameter of 200-300 nm and a molecularly imprinted layer thickness of 100 nm. Specifically, the aqueous phase metal organic framework molecularly imprinted material (MIL@MIP) enriched in trace amount of acesulfame has a specific surface area of 1575.43 m ² /g.

The invention also provides a preparation method of the above-mentioned aqueous phase metal organic framework molecularly imprinted material enriched with trace amount of carbaryl, comprising the following steps: 0.165 g of template molecule carbaryl is placed in a 25 mL stoppered round bottom flask Add 3.0 mL of tetrahydrofuran to dissolve completely, then add 600 functional monomer 3-aminopropyltriethoxysilane, stir the reaction for 30 min, add 0.050 g of activated MIL-101, and fully react for 60 min. Add 700 cross-linking agent tetraethoxysilane, mix well, add 1.0 mL of catalyst 0.2 mol/L acetic acid solution, stir the reaction for 30 min, then incubate in a water bath at 60 °C for 20 h to obtain MIL@MIP. Body; The precursor was taken out from the round bottom flask, and the mixture was extracted with a mixture of methanol and glacial acetic acid in a volume ratio of 9:1 until it was detected by the acetonide.

Specifically, the method for preparing the activated MIL-101 includes the following steps:

(1) synthesis

4.00 g of chromium nitrate, 1.64 g of terephthalic acid and 125 μL of 40% hydrofluoric acid were added together to 70 mL of ultrapure water, and ultrasonically mixed thoroughly; transferred to a 100 mL autoclave, 220 ° Heat at 8 ° C for 8 h. After cooling to room temperature, transfer the reaction solution to a 100 mL centrifuge tube, centrifuge, pour off the supernatant, wash the filter residue with ultrapure water, wash it three times, each time for 10 min, then centrifuge at high speed. The machine was centrifuged at 4000 r/min for 15 min, and dried to obtain a green powdery product MIL-101;

(2) Purification

Transfer the synthesized MIL-101 sample to a 100 mL round bottom flask, add 50 mL of ultrapure water, stir well, heat in a 70 water bath for 5 h, centrifuge at 4000 r/min for 10 min; collect the precipitate, then add 50 mL. Water ethanol, fully stirred, heated at 60 °C for 3 h, centrifuged, collected and dried.

(3) Activation

The precipitate after drying in step (2) is placed in 100-200 mL of 30 mmol ammonium fluoride, heated in a water bath at 60 ° C for 10 h; cooled to room temperature, filtered, washed three times with water to remove residual H ₄ F, ie Activated MIL-101.

The beneficial effects of the invention:

The present invention obtains "imprinted pores" consistent with the molecular structure of the fast-acting template. The water-phase metal organic framework molecular imprinted material enriched with trace amount of acesulfame uses a large specific surface area aqueous metal organic framework material MIL-101 as a support carrier, which significantly increases the specific surface area and improves the mass transfer rate of the material. ; The selective recognition effect of the template molecule carbaryl is good.

The aqueous phase metal organic framework molecular imprinting material enriched with trace amount of carbaryl can be prepared by simple preparation process, low production cost and no special instruments and equipment are needed. Moreover, the whole process does not require grinding and sieving, and the particles are evenly distributed, which can meet the requirements of the particle size of the solid phase extraction filler, and is used in combination with the quartz crystal microbalance to apply the trace amount to the actual sample. In the detection of Wei.

DRAWINGS

1 is a scanning electron micrograph of a metal organic framework material MIL-101 synthesized in the aqueous phase after activation in Example 1.

2 is a scanning electron micrograph of the MIL Xinjiang IP obtained in Embodiment 1;

As shown in Fig. 1, the MIL-101 crystal synthesized in the experiment has a uniform particle size and a relatively smooth surface, and the crystal exhibits a complete octahedral structure. The size of a single crystal particle is about 100 nm. After embedding the molecularly imprinted layer, as shown in Fig. 2, the diameter of the octahedral crystal grains is significantly increased to 200-300 nm, and the increased crystal size is the embedded molecular imprinted layer.

Figure 3 shows the adsorption equilibrium curves of MIL IP and MIL explicit IP;

Figure 4 shows the adsorption kinetic curves of MIL@MIP and MIL@NIP;

Figure 5 shows the adsorption capacity of MIL Xinjiang IP and MIL@NIP for acesulfame, propoxur, carbaryl, isoprocarb and zhongdingwei.

detailed description

The following examples are intended to provide a fuller understanding of the invention, but are not intended to limit the invention in any way.

Example 1:

A method for preparing an aqueous phase metal organic framework molecularly imprinted material (MIL@MIP) enriched with trace amount of acesulfame, comprising the following steps:

1). Preparation of MIL-101: 4.00 g of chromium nitrate (Cr(N0 ₃ ) ₃ 9H ₂ 0), 1.64 g of terephthalic acid (H ₂ BDC) and 125 40% hydrofluoric acid (HF) were added together. In 70 mL of ultrapure water, mix thoroughly with ultrasound. Transfer to a 100 mL autoclave, heat at 220 °C for 8 h, cool to room temperature, transfer the reaction solution to a 100 mL centrifuge tube, centrifuge, pour off the supernatant, wash the filter residue with ultrapure water, and wash it three times. Each time of ultrasonic for 10 min, it was centrifuged at a speed of 4000 r/min for 15 min with a high-speed centrifuge, and dried to obtain a green powdery product MIL-101. Transfer the synthesized MIL-101 sample to 100 mL In a round bottom flask, add 50 mL of ultrapure water and stir well, 70 °. The mixture was heated in a water bath for 5 h and centrifuged at 4000 r/min for 10 min. The precipitate was collected, and 50 mL of absolute ethanol was added thereto, stirred well, heated at 60 ° C for 3 h, centrifuged, and the precipitate was collected and dried.

2). Activation of MIL-101: The dried precipitate obtained in step 1) was heated with 150 mL of 30 mmol of ammonium fluoride (H ₄ F) in a 60 ° C water bath for 10 h. After cooling to room temperature, it was filtered, washed three times with water, and the residual H ₄ F was removed to obtain activated MIL-101.

3) Preparation of MIL Xinjiang IP precursor: 0.165 g of template molecule carbaryl (1.0 mmol) was placed in a 25 mL stoppered round bottom flask, and 3.0 mL of tetrahydrofuran (THF) was added to completely dissolve it. Add 600 functional monomer 3-aminopropyltriethoxysilane (APTES), magnetically stir for 30 min, add 0.050 g of activated MIL-101, fully react for 60 min and then add 700 crosslinker tetraethoxy. Silane (TEOS), after mixing well, add 1.0 mL of 0.2 mol/L acetic acid solution, stir the reaction for 30 min, and then incubate in a water bath at 60 °C for 20 h to obtain the precursor of MIL Xinjiang.

4). Elution of template molecules: After the polymerization is completed, the precursor is taken out from the round bottom flask and subjected to sonic extraction with methanol: glacial acetic acid (9: 1, v/v) as solvent until there is no fast-acting Check out; that is, MIL Xinjiang IP.

The aqueous phase metal-organic framework molecular imprinted material (MIL Xinjiang IP) enriched in the amount of the high-speed extract obtained by the method of the present invention has a particle size of 200-300 nm, a molecularly imprinted layer thickness of about 100 nm, and a specific surface area of 1575.43 m. ² / g. Comparative Example 1

The preparation of the non-imprinted polymer was the same as the preparation of Example 1 except that the template molecule was not added and the elution of the template molecule of Example 1 was not included. Get MIL@NIP.

MIL@MIP adsorption equilibrium combined experiment

Accurately weigh 10.0 mg of MIL@MIP or MIL@NIP in a 4.0 mL centrifuge tube, add 3.0 mL of carbaryl-water solution (5.0-30.0 mg l/ ¹ ), seal, mechanically shake for 30 min, room temperature (25 Centrifuge for 15 min at "C) OO r min- ¹ . Accurately remove the supernatant and determine its value on an ultraviolet spectrophotometer to calculate the concentration of carbaryl, with a wavelength of 210 nm.

The MIL@MIP and MIL@NIP adsorption equilibrium curves are shown in Figure 3: In the low concentration range, the difference in adsorption capacity between MIL@MIP and MIL@NIP is not significant; with the increase in the concentration of the fast-acting mother liquor, MIL@ Both MIP and MIL@NIP have different degrees of adsorption capacity for template molecules, and the difference between imprinting and non-imprinting is more obvious. When metolcarb concentration 25.0 mg L ^"1, the MIL @ MIP adsorption capacity was 3.217 mg g- ^1, at the same time, the adsorption capacity of MIL @ NIP 1.994 mg g- ^1, MIL @ MIP It is about 1.6 times that of MIL@NIP. Thereafter, the initial concentration of the carbaryl in the adsorption solution was continuously increased, and there was no significant increase in the adsorption capacity of the carbaryl. The results showed that the specificity of MIL@MIP was obvious and the blotting effect was better.

Adsorption kinetics experiment of MIL@MIP

Accurately weigh 10.0 mg MIL@MIP in a 4.0 mL centrifuge tube, add 3.0 mL of 10 mg!/ ¹ of the speed-water standard solution, and shake at room temperature (25 °C) for 3, 5, 10, 20, respectively. At 30, 40, 50 and 60 min, 4000 r ηήη· ^{1 was} centrifuged for 15 min, and the concentration of the supernatant in the supernatant was accurately determined on an ultraviolet spectrophotometer at a wavelength of 210 nm.

The experimental results are shown in Fig. 4. The new molecularly imprinted material MIL@MIP has a faster adsorption rate for the target velocity. When the adsorption time is 3 min, the adsorption equilibrium has been completed at 34.50%, and 5 min has been completed. The adsorption equilibrium is 49.64%; the shaking is continued, and it takes only 20 minutes to fully reach the adsorption equilibrium. If a lower concentration of the adsorbent is selected during the experiment, the time at which MIL@MIP reaches the adsorption equilibrium will be further shortened. Compared with traditional molecularly imprinted materials, the new material MIL@MIP synthesized by the advanced method in this experiment greatly shortens the time required to reach the adsorption equilibrium. The reason for the analysis may be that the metal organic framework material MIL-101 with high specific surface area is used as a support in the molecularly imprinted polymer, which helps to increase the specific surface area of the molecularly imprinted material. The polymerization reaction is carried out on the surface of MIL-101. The surface of the frame material forms a molecularly imprinted polymer film, which avoids mass transfer to the deep part of the polymer during adsorption, thereby significantly increasing the mass transfer rate of the material, and achieving adsorption equilibrium faster, so that MIL@MIP can be applied to the future quickly. Detection is possible.

MIL@MIP's selective experiment

In order to investigate the selectivity of the novel polymeric material MIL@MIP for the rapid release of the template molecule, carbaryl, propoxur, isoprocarb and zhongdingwei, which are similar in structure and function, were selected as competitors of carbaryl. Weigh 10.0 mg MIL@MIP or MIL@NIP into a 4.0 mL centrifuge tube and add 3.0 mL of a 10.0 mg L mixed solution of five substances. Shake for 30 min at room temperature (25 ° C) and centrifuge for 15 min at 4000 r min- ¹ . The supernatant was removed and the concentration of each of the five substances was measured by a high performance liquid chromatograph (λ = 210 ηιη) equipped with a UV detector, and the adsorption capacity of each substance was calculated according to the change of the solution concentration before and after the adsorption.

The experimental results are shown in Figure 5. Using MIL@MIP as the adsorbent material, the partition coefficients of the five structural analogues of carbaryl, propoxur, carbaryl, isoprocarb and zhongweiwei were 152.67, 15.47, 13.67, respectively. 36.41 and 24.00. Among them, the value of _d is the largest, and the larger _d is the higher the selectivity, which proves Compared with his four competitors, MIL@MIP has high selectivity for acetonide, and the specific effect of the imprinted material MIL@MIP is more obvious. Using MIL@NIP as the adsorbent material, the partition coefficients _{d of the} five structural analogues of carbaryl, propoxur, carbaryl, isoprocarb and zhongweiwei were 47.49, 24.36, 21.39, 43.92 and 26.31, respectively.

Claims

Claim

An aqueous phase metal organic framework molecularly imprinted material enriched with trace amount of acesulfame, characterized in that: the product is prepared by a method comprising the following steps: a metal organic framework material synthesized by an activated aqueous phase MIL-101 is a support, fast-acting is a template molecule, 3-aminopropyltriethoxysilane is a functional monomer, and tetraethoxysilane is a cross-linking agent. MIL@MIP is synthesized by a sol-gel method. Precursor; then the Soxhlet extraction is used to remove the template molecules in the precursor, that is, the aqueous phase metal organic framework molecular imprinted material enriched in trace amount of acesulfame, ie MIL@MIP.

2 . The aqueous phase metal organic framework molecular imprinting material enriched in trace amount of carbaryl according to claim 1 , wherein: in the preparation of MIL@MIP, the catalyst used is 0.2 mol/L acetic acid. The solvent is tetrahydrofuran.

The invention relates to an aqueous phase metal organic framework molecularly imprinted material enriched in trace amount of acesulfame according to claim 2, wherein: the amount of MIL-101 after activation of the support is 0.050 g, and the template molecule is fast-acting. The dosage is 1.0 mmol, the functional monomer 3-aminopropyltriethoxysilane is 600 μί, the cross-linking agent tetraethoxysilane is 700 μί, and the catalyst is 0.2 mol/L acetic acid solution. The dosage is 1.0 mL, and the solvent tetrahydrofuran is used in an amount of 3.0 mL.

The aqueous phase metal organic framework molecularly imprinted material enriched in trace amount of acesulfame according to claim 3, wherein: the MIL@MIP has a particle diameter of 200-300 nm, and the molecularly imprinted layer has a thickness of 4. 100 nm.

The aqueous phase metal organic framework molecularly imprinted material enriched in trace amount of acesulfame according to claim 3, wherein the MIL@MIP has a specific surface area of 1575.43 m ² /g.

The method for preparing an aqueous phase metal organic framework molecularly imprinted material enriched with trace amount of acesulfame according to any one of claims 1 to 5, which comprises the following steps: 0.165 g of template molecule is rapidly released. Into a 25 mL stoppered round bottom flask, add 3.0 mL of tetrahydrofuran to dissolve completely, then add 600 μL of functional monomer 3-aminopropyltriethoxysilane, stir the reaction for 30 min, and add 0.050 g to activate. After MIL-101, fully react for 60 min, add 700 cross-linking agent tetraethoxysilane, mix well, add 1.0 mL of 0.2 mol/L acetic acid solution, stir the reaction for 30 min, and then put in water bath 60 °. After incubation for 20 h, the precursor of MIL@MIP was obtained; the precursor was taken out from the round bottom flask, and the mixture was extracted with a mixture of methanol and glacial acetic acid in a volume ratio of 9:1 until solvent was not used. Check out, that is.

The preparation method according to claim 6, wherein: the activated MIL-101 system The preparation method includes the following steps:

(1) Synthesis

4.00 g of chromium nitrate, 1.64 g of terephthalic acid and 125 μL of 40% hydrofluoric acid were added together to 70 mL of ultrapure water, and ultrasonically mixed thoroughly; transferred to a 100 mL autoclave, 220 ° Heat under C for 8 h, cool to room temperature, transfer the reaction solution to a 100 mL centrifuge tube, centrifuge, pour off the supernatant, wash the filter residue with ultrapure water, wash it three times, each time for 10 min, then use a high-speed centrifuge. Centrifuge at 4000 r/min for 15 min, and dry to obtain green powdery product MIL-101;

(2) Purification

Transfer the synthesized MIL-101 sample to a 100 mL round bottom flask, add 50 mL of ultrapure water, stir well, heat in a 70 water bath for 5 h, centrifuge at 4000 r/min for 10 min; collect the precipitate, then add 50 mL of water. Ethanol, stirred well, heated at 60 °C for 3 h, centrifuged, collected and dried.

(3) Activation

The precipitate after drying in step (2) is placed in 100-200 mL of 30 mmol ammonium fluoride, heated in a water bath at 60 ° C for 10 h _; cooled to room temperature, filtered, washed three times with water to remove residual H ₄ F, ie Activated MIL-101.