Metal organic framework adsorbing material as well as preparation method and application thereof

Abstract

The invention discloses a metal organic framework adsorption material and a preparation method and application thereof, and relates to the technical field of chemical adsorption material preparation, the metal organic framework adsorption material comprises the following raw materials: ZrCl4, 2-aminoterephthalic acid, imidazole, chloramine salt, plant essential oil, a pore-forming agent and the like. The invention also discloses a preparation method which comprises the following steps: dissolving ZrCl4, 2-aminoterephthalic acid and hydrochloric acid in N, N-dimethylformamide; the reaction liquid, dichloroalkane and xylene are mixed, and UIO66-Cl is obtained; the preparation method comprises the following steps: putting UIO66-Cl and aminoimidazole into xylene; reacting with glycidyl methacrylate; and sequentially adding the reaction product, plant essential oil, a pore-forming agent and the like into absolute ethyl alcohol, and reacting to obtain the metal organic framework adsorbing material. The adsorption material provided by the invention has selectivity on plant essential oil mainly containing alcohol and ketone chemical substances and is high in adsorption capacity.

Description

Technical Field

[0001] The invention relates to the technical field of chemical adsorption material preparation, and in particular to a metal organic framework adsorption material and a preparation method and application thereof. Background Art

[0002] Steam distillation is one of the common methods for producing plant essential oils. At present, steam distillation is the most widely used method, with simple equipment, convenient operation, no solvent residue, low cost, easy to promote, strong practicality, good stability, and relatively mature technology, equipment and operation. When plant materials are distilled by steam, plant essential oils will be distilled out together with water vapor, and after condensation, the plant essential oils can be obtained by separating the oil and water phases. However, the condensate obtained after condensation is mainly composed of water, and the amount of plant essential oils is much less than water. A small amount of essential oil droplets are suspended in the condensate to form oil droplets with a particle size of less than 0.1 microns. Because of its increased solubility in water, it cannot be used by the oil-water two-phase separation method.

[0003] Adsorption is another common method for producing plant essential oils. The adsorption method uses the interaction between chemical substances and adsorption materials to make them combine with the adsorption materials, thereby achieving the purpose of separation and purification from the raw materials. The selection of adsorption materials is the key. Excellent adsorption materials have the advantages of good selectivity, stable physical and chemical properties, simple operation and easy regeneration. Traditional adsorption materials often use animal and plant oils, silica gel, activated carbon, etc., but their disadvantage is that they have no selectivity for the adsorption of plant essential oils. They just adsorb all essential oil molecules indiscriminately with the help of the similar hydrophilic and hydrophobic properties between the adsorption materials and the plant essential oils. Therefore, in order to improve the performance of the adsorption material and its selective adsorption of plant essential oils, materials with framework structures should be selected and the molecular imprinting principle should be used to develop corresponding adsorption materials based on the specific structure of plant essential oil molecules.

[0004] For plant essential oils mainly composed of alcohols and ketones, the adsorption materials in the prior art often do not have selective adsorption and have low adsorption capacity, so the extraction rate and utilization rate of alcohols and ketones are often low. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide a metal organic framework adsorption material and its preparation method and application, and solve the technical problems that the adsorption materials in the prior art have no selectivity for plant essential oils mainly composed of alcohols and ketones and have low adsorption capacity.

[0006] In order to achieve the above technical purpose, the technical solution of the present invention provides a metal organic framework adsorption material, the raw materials of which include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent;

[0007] The pore-forming agent is composed of a mixture of an ionic liquid and a surfactant, wherein the ionic liquid is one or more of 1-pentyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-heptyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium chloride, and the surfactant is one or more of Tween 20, Tween 80, and Span 20, and the mass ratio of the ionic liquid to the surfactant is 1:0.5-3.

[0008] Preferably, the plant essential oil is one or more of camphor tree essential oil, maple poplar essential oil, and peppermint essential oil, and the cross-linking agent is one of ethylene glycol dimethacrylate, ethylene glycol dimethacrylate, and divinylbenzene.

[0009] A method for preparing the metal organic framework adsorption material as described above comprises the following steps:

[0010] S1, dissolving ZrCl4, 2-aminoterephthalic acid and hydrochloric acid in N,N-dimethylformamide, heating to 120°C, and reacting for 24 hours to obtain the metal organic framework UIO66, namely UIO66-NH2;

[0011] S2, mixing the UIO66-NH2 and dichloroalkane with xylene, heating to 80°C and stirring for 2 hours to obtain chlorinated UIO66, i.e., UIO66-Cl;

[0012] S3, mixing imidazole, chloramine salt and triethylamine with xylene, heating to 80°C and stirring continuously for 6 hours to obtain aminoimidazole;

[0013] S4, placing the UIO66-Cl and the aminoimidazole in xylene, heating to 80° C. and continuously stirring for 8 hours to obtain ionic liquid-modified UIO66, namely, UIO66-IL-NH2;

[0014] S5, placing the UIO66-IL-NH2 and glycidyl methacrylate in anhydrous ethanol, mixing, heating to 70° C. and continuously stirring for 4 hours to obtain GMA-ionic liquid modified UIO66, i.e., UIO66-IL-GMA;

[0015] S6. Add UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent to anhydrous ethanol in sequence, heat to 70°C and continue stirring for 6 hours after mixing, to obtain UIO66-IL-MIP, i.e., metal organic framework adsorption material. The characteristic of plant essential oil is its volatility. After the metal organic framework adsorption material is prepared at 70°C, the plant essential oil as a template molecule is still in a free state, and will gradually evaporate in a continuous high temperature environment, leaving vacancies in the structure.

[0016] Preferably, the mass ratio of ZrCl4, 2-aminoterephthalic acid, hydrochloric acid and N,N-dimethylformamide in S1 is 1:1-2:0.5-3:5-10. The ratio of ZrCl4, 2-aminoterephthalic acid, hydrochloric acid and N,N-dimethylformamide is matched according to the size of the chemical structure of the plant essential oil molecule. If the ratio exceeds this range, either a metal organic framework material with a suitable space size cannot be obtained, or the metal organic framework structure will collapse and be damaged during the subsequent modification process.

[0017] Preferably, the mass ratio of UIO66-NH2 to dichloroalkane in S2 is 1:1-3, and the dichloroalkane is one of 1,4-dichlorobutane, 1,6-dichlorohexane and 1,9-dichlorononane.

[0018] Preferably, the mass ratio of imidazole, chloramine salt and triethylamine in S3 is 1:0.5-3:0.1-0.3, and the chloramine salt is one of 2-chloroethylamine hydrochloride and 3-aminopropylamine hydrochloride.

[0019] Preferably, the mass ratio of UIO66-Cl to aminoimidazole in S4 is 1:0.2-5.

[0020] Preferably, the mass ratio of UIO66-IL-NH2 and glycidyl methacrylate in S5 is 1:0.1-6.

[0021] Preferably, the mass ratio of UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent in S6 is 1:0.1-1:0.1-0.5:0.2-2.

[0022] In the preparation process of the present invention, the innermost metal organic framework structure can be obtained through steps S1 and S2; steps S3 and S4 modify a layer of ionic liquid functional groups outside the metal organic framework; finally, steps S5 and S6 wrap the molecular imprinting layer on the outermost layer of the adsorption material through chemical reaction.

[0023] Steps S3 and S4 modify a layer of ionic liquid functional groups outside the metal organic framework. Among them, the aminoimidazole formed in step S3 has an imidazole ring structure and an amino side chain structure. In the step S4 reaction, the imidazole ring electron cloud is attracted by the chloride ions on UIO66-Cl, forming a layer of ionic liquid functional groups with anionic and cationic structures. Because the chloride ions are on the outside of UIO66, the formed ionic liquid functional groups are wrapped in the outer layer of UIO66; and because of the intramolecular force, the amino side chains are arranged on the outside of the ionic liquid functional groups.

[0024] Steps S5 and S6 wrap the molecular imprinting layer on the outermost layer of the adsorbent material through chemical reactions. In the step S5 reaction, the amino side chain and the epoxy structure of GMA produce a ring-opening reaction and form a new covalent bond, connecting GMA to the amino side chain, and the steric hindrance force makes the GMA alkyl chain point outward. In the step S6 reaction, as UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent are added in sequence, the reaction raw materials are solidified on the outermost side of the adsorbent material with the GMA functional group as the anchor point, forming the outermost molecular imprinting layer.

[0025] UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent are added to S6 in sequence. When the plant essential oil is added, the essential oil molecules use their alkyl chains, hydroxyl groups and carbon ring structures to generate chemical bond forces with the amino groups on UIO66, the alkyl and imidazole rings on the ionic liquid, and the alkyl and carbonyl groups on GMA, so that the essential oil molecules are attached to the inner and outer surfaces of the UIO66-IL-GMA channels in a certain direction; when the pore-forming agent is added, firstly, the pore-forming agent uses the hydrophilicity and hydrophobicity generated by its surfactant to dissolve well with the essential oil molecules and form droplets close to the size of the essential oil molecules, and secondly, the pore-forming agent The ionic liquid forms a specific arrangement order around the chemical structure of the essential oil molecules by means of the hydrogen bonds, π-π bonds, ionic bonds and other chemical bonds formed between it and the essential oil molecules. The addition of pore-forming agent can create cavities that are close in size to the essential oil molecules and have a similar spatial structure. When the cross-linking agent is added, the cross-linking agent molecules use their alkyl chains, carbon rings and carbonyl functional groups to form hydrogen bonds, π-π bonds and other chemical bonds with the alkyl chains and hydroxyls of the essential oil molecules, as well as with the imidazole rings, anions and cations of the ionic liquids to arrange themselves in a specific order and direction, and form a molecular imprinting layer of the adsorption material after curing.

[0026] In aqueous solution, when plant essential oil molecules with the same or similar size, structure, and functional group arrangement as the template molecules come into contact with the adsorption material, the adsorption material uses the highly similar spatial structure and strong chemical bond forces between functional groups to identify and adsorb the plant essential oil molecules. Therefore, even essential oil molecules with lower concentrations in aqueous solution can be selectively adsorbed to reduce the loss of plant essential oil molecules.

[0027] The metal organic framework adsorption material prepared by the present invention is a multilayer structure, with a metal organic framework inside, an ionic liquid functional group modified with a chemical bond on the outer layer, and a molecular imprinting polymer layer wrapped with an organic synthesis on the outermost layer. When adsorbing specific plant essential oils, in addition to the physical adsorption effect of the metal organic framework on the plant essential oil molecules, there are also forces generated by the ionic liquid functional groups and the molecular imprinting polymer layer and various chemical bonds therebetween, which is conducive to improving the adsorption effect on specific plant essential oil molecules.

[0028] The advantage of a multilayer structure is that each layer has its own special structure and functional groups. For example, the metal-organic framework has a large number of porous structures, the ionic liquid contains a large number of ionic bonds, and the molecular imprinting layer contains special spatial holes, etc., so that each layer of the resulting material can interact with the plant essential oil molecules during the adsorption process, thereby achieving selectivity while increasing the adsorption amount.

[0029] An application of the metal organic framework adsorption material as described above in the selective adsorption of alcohol and ketone essential oils.

[0030] Compared with the prior art, the beneficial effects of the present invention include:

[0031] The present invention utilizes the framework structure and molecular imprinting principle of MOF materials, takes camphor tree essential oil, maple poplar essential oil and peppermint essential oil as template molecules, and uses ionic liquids with different structures as molecular recognition cores to prepare an adsorption material with a multilayer structure, good adsorption performance and the ability to achieve molecular recognition for specific plant essential oils.

[0032] In the process of preparing the adsorption material, ionic liquid modified UIO66 is first obtained. This step can introduce ionic liquid functional groups into the UIO66 framework structure, providing a large number of chemical bonds that can be used for molecular recognition in the subsequent molecular imprinting process. The camphor tree essential oil, maple poplar essential oil and peppermint essential oil used contain a large number of alcohol and ketone chemicals, which contain chemical bonds such as hydroxyl and carbonyl. By adjusting different types of ionic liquids, hydrophilicity / hydrophobicity and hydrogen bonds, π-π bonds, ionic bonds and other chemical bonds can be used to form a specific spatial structure and chemical bond arrangement with plant essential oil molecules, so that plant essential oil molecules with similar structures can be recognized during the adsorption process.

[0033] The metal organic framework adsorption material of the present invention uses plant essential oil molecules as templates and ionic liquids as molecular recognition cores, and adjusts the types and amounts of raw materials in the preparation process according to the structural characteristics of the template molecules, so that the physicochemical properties (multilayer structure, specific spatial structure, specific chemical bond arrangement order) of the metal organic framework adsorption material have high selectivity and adsorption for plant essential oils mainly composed of alcohol and ketone chemicals, and can be used to adsorb and concentrate specific plant essential oils in low-concentration environments, thereby improving the utilization rate of plant essential oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1-1 is a scanning electron microscope image of UIO66-NH2 prepared in Example 4;

[0035] Figure 1-2 is another scanning electron microscope image of UIO66-NH2 prepared in Example 4;

[0036] Figure 1-3 is a scanning electron microscopy image of the UIO66-IL-MIP prepared in Example 4;

[0037] Figure 1-4 is another scanning electron microscopy image of the UIO66-IL-MIP prepared in Example 4;

[0038] Figure 2 is the Fourier transform infrared spectrum of UIO66-IL-MIP prepared in Example 4;

[0039] Figure 3 This is the thermogravimetric analysis diagram of UIO66-IL-MIP prepared in Example 4;

[0040] Figure 4 It is the liquid chromatogram of the adsorption amount of specific plant essential oil by different metal organic framework adsorption materials under different temperature conditions;

[0041] Figure 5 Liquid chromatograms of the adsorption amount of specific plant essential oils by different metal-organic framework adsorbents under different time conditions. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] Example 1

[0044] The present embodiment provides a metal organic framework adsorption material, whose raw materials include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent.

[0045] A method for preparing the metal organic framework adsorption material as described above comprises the following steps:

[0046] 1) Dissolve 1 g of ZrCl4, 1 g of 2-aminoterephthalic acid and 0.5 g of hydrochloric acid in 5 g of N,N-dimethylformamide, then heat to 120°C and react for 24 hours to obtain 2 g of UIO66-NH2;

[0047] 2) Mix the obtained 2 g UIO66-NH2 and 2 g 1,4-dichlorobutane in 150 g xylene, heat to 80°C and continue stirring for 2 hours to obtain 3.8 g UIO66-Cl.

[0048] 3) 5 g of imidazole, 2.5 g of 2-chloroethylamine hydrochloride, and 0.5 g of triethylamine were uniformly mixed in 150 g of xylene, heated to 80°C and stirred for 6 hours to obtain 7.3 g of aminoimidazole;

[0049] 4) The obtained 3.8 g UIO66-Cl and 7.3 g aminoimidazole were uniformly mixed in 150 g xylene, heated to 80°C and stirred for 8 hours to obtain 9.7 g UIO66-IL-NH2;

[0050] 5) Mix the obtained 9.7 g of UIO66-IL-NH2 and 0.9 g of glycidyl methacrylate (GMA) in 150 g of anhydrous ethanol, heat to 70°C and continue stirring for 4 hours to obtain 10.1 g of UIO66-IL-GMA;

[0051] 6) 0.67 g of 1-pentyl-3-methylimidazolium chloride and 0.33 g of Tween 20 were mixed to prepare 1 g of a pore-forming agent;

[0052] The obtained 10.1 g UIO66-IL-GMA, 1 g camphor essential oil, 1 g pore-forming agent and 2 g divinylbenzene were sequentially added to 150 g anhydrous ethanol and mixed, heated to 70°C and stirred for 6 hours to obtain 12.1 g UIO66-IL-MIP.

[0053] Example 2

[0054] The present embodiment provides a metal organic framework adsorption material, whose raw materials include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent.

[0055] A method for preparing the metal organic framework adsorption material as described above comprises the following steps:

[0056] 1) Dissolve 1 g of ZrCl4, 2 g of 2-aminoterephthalic acid and 3 g of hydrochloric acid in 10 g of N,N-dimethylformamide, then heat to 120°C and react for 24 hours to obtain 2.8 g of UIO66-NH2;

[0057] 2) Mix the obtained 2.8 g of UIO66-NH2 and 8.4 g of 1,9-dichlorononane in 150 g of xylene, heat to 80°C and continue stirring for 2 hours to obtain 9.9 g of UIO66-Cl.

[0058] 3) 15 g of imidazole, 45 g of 3-aminopropylamine hydrochloride, and 4.5 g of triethylamine were uniformly mixed in 150 g of xylene, heated to 80° C. and stirred for 6 hours to obtain 53 g of aminoimidazole;

[0059] 4) 9.9 g of UIO66-Cl and 49.5 g of aminoimidazole were uniformly mixed in 150 g of xylene, heated to 80°C and stirred for 8 hours to obtain 52.3 g of UIO66-IL-NH2;

[0060] 5) 52.3 g of UIO66-IL-NH2 was mixed with 313.8 g of glycidyl methacrylate (GMA) in 150 g of anhydrous ethanol, heated to 70°C and stirred for 4 hours to obtain 318.5 g of UIO66-IL-GMA;

[0061] 6) 39.8 g of ionic liquid (including 10 g of 1-pentyl-3-methylimidazolium chloride, 10 g of 1-hexyl-3-methylimidazolium chloride, 10 g of 1-heptyl-3-methylimidazolium chloride and 9.8 g of 1-octyl-3-methylimidazolium chloride) and 119.4 g of surfactant (including 39.8 g of Tween 20, 39.8 g of Tween 80 and 39.8 g of Spam 20) were mixed to obtain 159.2 g of pore-forming agent;

[0062] The obtained 318.5 g UIO66-IL-GMA, 318.5 g plant essential oil (including 106.2 g camphor essential oil, 106.2 g maple essential oil, 106.1 g peppermint essential oil), 159.2 g pore-forming agent and 637 g ethylene glycol dimethacrylate were added to 150 g anhydrous ethanol in sequence, and the mixture was heated to 70°C and stirred for 6 hours to obtain 955.5 g UIO66-IL-MIP.

[0063] Example 3

[0064] The present embodiment provides a metal organic framework adsorption material, whose raw materials include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent.

[0065] A method for preparing the metal organic framework adsorption material as described above comprises the following steps:

[0066] 1) Dissolve 1 g of ZrCl4, 1.5 g of 2-aminoterephthalic acid and 2 g of hydrochloric acid in 8 g of N,N-dimethylformamide, then heat to 120°C and react for 24 hours to obtain 2.4 g of UIO66-NH2;

[0067] 2) Mix the obtained 2.4 g UIO66-NH2 and 4.8 g 1,6-dichlorohexane in 150 g xylene, heat to 80°C and continue stirring for 2 hours to obtain 7 g UIO66-Cl.

[0068] 3) 10 g of imidazole, 15 g of 2-chloroethylamine hydrochloride and 2 g of triethylamine were uniformly mixed in 150 g of xylene, heated to 80°C and stirred for 6 hours to obtain 21 g of aminoimidazole;

[0069] 4) The obtained 7 g UIO66-Cl and 21 g aminoimidazole were uniformly mixed in 150 g xylene, heated to 80°C and stirred for 8 hours to obtain 26.5 g UIO66-IL-NH2;

[0070] 5) Mix the obtained 26.5 g of UIO66-IL-NH2 and 79.5 g of glycidyl methacrylate (GMA) in 150 g of anhydrous ethanol, heat to 70°C and continue stirring for 4 hours to obtain 95 g of UIO66-IL-GMA;

[0071] 6) 9.5 g of ionic liquid (including 4.7 g of 1-pentyl-3-methylimidazolium chloride and 4.8 g of 1-heptyl-3-methylimidazolium chloride) and 19 g of surfactant (including 10 g of Tween 20 and 9 g of Spam 20) were mixed to prepare 28.5 g of pore-forming agent;

[0072] The obtained 95 grams of UIO66-IL-GMA, 47.5 grams of plant essential oil (including 15 grams of camphor essential oil, 15 grams of maple essential oil, and 17.5 grams of peppermint essential oil), 28.5 grams of pore-forming agent and 95 grams of ethylene glycol dimethacrylate were added to 150 grams of anhydrous ethanol in sequence, and the mixture was heated to 70°C and stirred for 6 hours to obtain 190 grams of UIO66-IL-MIP.

[0073] Example 4

[0074] The present embodiment provides a metal organic framework adsorption material, whose raw materials include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent.

[0075] A method for preparing the metal organic framework adsorption material as described above comprises the following steps:

[0076] 1) Dissolve 1 g of ZrCl4, 1.5 g of 2-aminoterephthalic acid and 2 g of hydrochloric acid in 8 g of N,N-dimethylformamide, then heat to 120°C and react for 24 hours to obtain 2.4 g of UIO66-NH2;

[0077] 2) Mix the obtained 2.4 g UIO66-NH2 and 4.8 g 1,6-dichlorohexane in 150 g xylene, heat to 80°C and continue stirring for 2 hours to obtain 7 g UIO66-Cl.

[0078] 3) 9 g of imidazole, 25.2 g of 3-aminopropylamine hydrochloride, and 1.8 g of triethylamine were uniformly mixed in 150 g of xylene, heated to 80° C. and stirred for 6 hours to obtain 28 g of aminoimidazole;

[0079] 4) The obtained 7 g UIO66-Cl and 28 g aminoimidazole were uniformly mixed in 150 g xylene, heated to 80°C and stirred for 8 hours to obtain 33.4 g UIO66-IL-NH2;

[0080] 5) 33.4 g of UIO66-IL-NH2 was mixed with 83.5 g of glycidyl methacrylate (GMA) in 150 g of anhydrous ethanol, heated to 70°C and stirred for 4 hours to obtain 114 g of UIO66-IL-GMA;

[0081] 6) 11.4 g of ionic liquid (including 6.4 g of 1-hexyl-3-methylimidazolium chloride and 5 g of 1-heptyl-3-methylimidazolium chloride) and 11.4 g of surfactant (including 8 g of Tween 80 and 3.4 g of Spam 20) were mixed to prepare 22.8 g of pore-forming agent;

[0082] The obtained 114 g UIO66-IL-GMA, 28.5 g plant essential oil (including 17 g camphor essential oil, 1.5 g maple essential oil, 10 g peppermint essential oil), 22.8 g pore-forming agent and 83.5 g ethylene glycol dimethacrylate were added to 150 g anhydrous ethanol in sequence, and the mixture was heated to 70°C and stirred for 6 hours to obtain 197.5 g UIO66-IL-MIP.

[0083] The following measurements were performed on the materials produced in this example.

[0084] 1. Scanning electron microscopy

[0085] The microstructure was measured using a scanning electron microscope (SEM), using a MIRA3 (Tesken, Czech Republic). Figure 1-1 and Figure 1-2 It can be seen that its particle size is about 200 nanometers, the surface is smooth and has a good framework structure; the morphology of UIO66-IL-MIP prepared in this example is as follows Figure 1-3 and Figure 1-4 It can be seen that the surface has been wrapped by polymer and ionic liquid, forming a multilayer structure with rough surface and multiple pores. Therefore, the scanning electron microscopy data shows that the metal organic framework adsorption material of the present invention is successfully prepared.

[0086] 2. Fourier transform infrared spectroscopy

[0087] The UIO66-IL-MIP prepared in Example 4 was subjected to Fourier transform infrared spectroscopy using a Nicolet 6700 (Thermo Fisher Scientific, USA). Figure 2 As shown, at 670.8cm -1 The -NH vibration peak appeared at 697.3cm-1 The vibration peaks of C-Cl appeared at 751.6 cm -1 3430.3cm -1 The vibration peaks of -OH appeared at 832.3cm -1 The vibration peak of -CH appeared at 1310cm -1 The vibration peak of -CH2 appeared at 950.9cm -1 3126.4cm -1 The alkyl chain vibration peaks appeared at 993 cm-1, which belonged to the functional groups on the metal organic framework, glycidyl methacrylate, ionic liquid and crosslinker; -1 1402cm -1 The -CO vibration peaks appeared at 1236.2 cm -1 The vibration peak of -CN appears at 1630cm -1 A vibration peak of -C=O appears at , and this vibration peak belongs to the functional groups on the metal organic framework, glycidyl methacrylate, and the crosslinking agent. Therefore, the Fourier infrared spectroscopy analysis data shows that the metal organic framework adsorption material of the present invention is successfully prepared.

[0088] 3. Thermogravimetric analysis

[0089] The UIO66-IL-MIP prepared in Example 4 was subjected to thermogravimetric analysis using Labsys evo (Setaram, France). Figure 3 As shown, it can be seen that the metal organic framework adsorption material UIO66-IL-MIP in this embodiment loses 36.1% of its mass within 350°C, which is caused by the decomposition of the outermost coated polymer layer at high temperature; and loses 25.8% of its mass between 350°C and 600°C, which is caused by the decomposition of the ionic liquid and the metal organic framework at high temperature. Therefore, the thermogravimetric analysis data shows that the metal organic framework adsorption material of the present invention is successfully prepared and has a multi-layer coating structure.

[0090] Comparative Example 1

[0091] The implementation scheme of this comparative example is similar to that of Example 4, except that the original step (2) of this comparative example, "mixing the obtained 2.4 grams of UIO66-NH2 with 4.8 grams of 1,6-dichlorohexane in 150 grams of xylene" is modified to "mixing the obtained 2.4 grams of UIO66-NH2 in 150 grams of xylene".

[0092] Comparative Example 2

[0093] The implementation of this comparative example is similar to that of Example 4, except that the pore-forming agent in step (6) of this comparative example contains only 11.4 g of surfactant (including 8 g of Tween 80 and 3.4 g of Spam 20) and no ionic liquid.

[0094] Comparative Example 3

[0095] The implementation scheme of this comparative example is similar to that of Example 4, except that in step (6) of this comparative example, the pore-forming agent contains only 11.4 g of ionic liquid (including 6.4 g of 1-hexyl-3-methylimidazolium chloride and 5 g of 1-heptyl-3-methylimidazolium chloride), and does not contain 11.4 g of surfactant.

[0096] Comparative Example 4

[0097] The implementation scheme of this comparative example is similar to that of Example 4, except that 28.5 g of plant essential oil is not added in step (6) of this comparative example.

[0098] Comparative Example 5

[0099] The implementation scheme of this comparative example is similar to Example 4, except that step (1) of this comparative example is "dissolving 1 gram of ZrCl4, 0.1 gram of 2-aminoterephthalic acid and 0.1 gram of hydrochloric acid in 1 gram of N,N-dimethylformamide".

[0100] Comparative Example 6

[0101] The implementation scheme of this comparative example is similar to that of Example 4, except that step (1) of this comparative example is "dissolving 1 g of ZrCl4, 5 g of 2-aminoterephthalic acid and 8 g of hydrochloric acid in 20 g of N,N-dimethylformamide".

[0102] The adsorption amount of plant essential oils was measured for the metal organic framework adsorption materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6.

[0103] 10 ml of camphor essential oil, maple essential oil, peppermint essential oil, lemon essential oil and pine needle essential oil were respectively placed in a conical flask, and then 1 gram of the metal organic framework adsorption material prepared in Examples 1 to 4 and Comparative Examples 1 to 6 was added; the conical flask was shaken for 1 minute and then allowed to stand for 20 minutes, and the concentration of the plant essential oil before and after adsorption was determined by liquid chromatography.

[0104] The determination of plant essential oil concentration was carried out under the same liquid chromatography conditions. Liquid chromatography detection conditions were: LC3000 (CXTH, China), TC-C18 column (4.6×150mm, 5μm, Agilent, USA), mobile phase methanol / water (85:15, v / v), flow rate 0.8mL / min, UV detector wavelength 470nm, column temperature 30℃. The concentration of plant essential oil was calculated by the sum of peak areas.

[0105] The adsorption amount of plant essential oil is calculated by formula (1):

[0106]

[0107] Where q e is the adsorption amount of plant essential oil when adsorption reaches equilibrium, in mg / g; C0 is the solution concentration before adsorption, in mg / mL; C e is the concentration of the solution at adsorption equilibrium, in mg / mL; V is the volume of the solution, in mL; m is the mass of the adsorbent material, in g.

[0108] The results of measuring the amount of plant essential oil adsorption of the metal organic framework adsorption materials prepared in Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1.

[0109] Table 1 Determination of adsorption capacity of plant essential oils

[0110]

[0111]

[0112] The metal-organic framework adsorption materials prepared in Examples 1 to 4 have plant essential oils mainly composed of alcohol and ketone chemicals added as molecular templates, while lemon essential oil and pine needle essential oil are mainly composed of terpene chemicals. Therefore, the metal-organic framework adsorption materials prepared in Examples 1 to 4 have good adsorption performance and selectivity for camphor essential oil, maple poplar essential oil and peppermint essential oil.

[0113] In the preparation method of comparative example 1, during the modification of UIO66, the raw materials for forming ionic liquids were lacking, resulting in the inability to form an ordered spatial structure between UIO66 and the molecular imprinting layer, and also lacking a large number of ionic liquid functional groups. Although the molecular imprinting layer can selectively adsorb specific plant essential oils, the adsorption amount is small.

[0114] In the preparation method of Comparative Example 2, the pore-forming agent lacks ionic liquid as a molecular recognition core. Although the prepared adsorption material has a certain spatial pore structure, it lacks molecular recognition ability and only utilizes the spatial pore structure and hydrophilic and hydrophobic properties to adsorb plant essential oils. It has no selectivity for specific plant essential oils (camphor essential oil, maple essential oil and peppermint essential oil).

[0115] In the preparation method of Comparative Example 3, the pore-forming agent lacks a surfactant, which results in the adsorption material being unable to form a sufficient spatial structure to accommodate plant essential oil molecules during the preparation process. Therefore, it has selective adsorption for specific plant essential oils, but the adsorption amount is small.

[0116] The adsorption material in Comparative Example 4 has a good framework structure and ionic liquid functional groups, but no plant essential oil is added during the preparation process, resulting in a disorderly arrangement of functional groups and inability to achieve molecular recognition. It only utilizes the spatial pore structure and the hydrophilic and hydrophobic properties of the functional groups to adsorb plant essential oils, and has no selectivity for specific plant essential oils (camphor essential oil, maple poplar essential oil and peppermint essential oil).

[0117] Although the outer molecular imprinting layers of Comparative Examples 5 and 6 have a certain selective adsorption for specific plant essential oils (plant essential oils mainly composed of alcohol and ketone chemicals), the raw material ratio in the preparation of UIO66 exceeds the relevant requirements in the technical solution of the present invention. In Comparative Example 5, UIO66 cannot form a framework structure of appropriate spatial size due to the small amount of organic ligand used; in Comparative Example 6, the excessive amount of organic ligand used will cause the metal organic framework structure to collapse and be destroyed in the subsequent modification process, and functional groups with appropriate arrangement cannot be formed, so the adsorption amount is small.

[0118] In order to further illustrate the effect of the metal organic framework adsorption material of the present invention on the adsorption of specific plant essential oils under different external environments, the following tests were performed.

[0119] Take six conical flasks, add 10 ml of camphor essential oil and 1 gram of the metal organic framework adsorption material in Example 4 to three of them, respectively, record them as A, B, and C, and add 10 ml of camphor essential oil and 1 gram of the metal organic framework adsorption material in Comparative Example 4 to the other three conical flasks, respectively, record them as D, E, and F.

[0120] In different environments, the conical flask was shaken for 1 minute and then left to stand for 20 minutes, and the concentration of plant essential oil before and after adsorption was determined by liquid chromatography. Among them, the environmental temperature of A and D was 45℃; the environmental temperature of B and E was 37℃; the environmental temperature of C and F was 30℃.

[0121] Figure 4 The data of the adsorption amount of camphor essential oil by metal organic framework adsorption materials at different ambient temperatures are shown. It can be seen that the increase in temperature is conducive to increasing the adsorption amount of camphor essential oil by metal organic framework adsorption materials. At the same time, the adsorption amount of camphor essential oil by Example 4 is higher than that by Comparative Example 4, which is because a template molecule is added to Example 4. The metal organic framework adsorption material in the present invention has a good adsorption effect on specific plant essential oils and a high adsorption amount.

[0122] Take two conical flasks, record them as M and N, add 10 ml of camphor essential oil and 1 gram of the metal-organic framework adsorption material of Example 4 to M, and add 10 ml of camphor essential oil and 1 gram of the metal-organic framework adsorption material of Comparative Example 4 to N; vibrate the conical flask for 1 minute and then let it stand for 20 minutes, and take samples at different time periods to determine the concentration of the plant essential oil after adsorption by liquid chromatography.

[0123] Figure 5 The data of the adsorption amount of camphor tree essential oil by the metal organic framework adsorption material under different time conditions are shown. It can be seen that the adsorption amount of camphor tree essential oil by the metal organic framework adsorption material prepared in Example 4 at different time periods is higher than the adsorption amount of camphor tree essential oil by the metal organic framework adsorption material prepared in Comparative Example 4. This shows that the metal organic framework adsorption material in the present invention has a good adsorption effect on specific plant essential oils.

[0124] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A metal organic framework adsorption material, characterized in that: Its raw materials include ZrCl4, 2-aminoterephthalic acid, hydrochloric acid, N,N-dimethylformamide, dichloroalkane, imidazole, chloramine salt, triethylamine, glycidyl methacrylate, plant essential oil, pore-forming agent and cross-linking agent; The pore-forming agent is composed of a mixture of an ionic liquid and a surfactant, wherein the ionic liquid is one or more of 1-pentyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium chloride, 1-heptyl-3-methylimidazolium chloride, and 1-octyl-3-methylimidazolium chloride, and the surfactant is one or more of Tween 20, Tween 80, and Span 20, and the mass ratio of the ionic liquid to the surfactant is 1:0.5-3.

2. The metal organic framework adsorption material according to claim 1, characterized in that: The plant essential oil is one or more of camphor tree essential oil, maple poplar essential oil and peppermint essential oil.

3. A method for preparing a metal organic framework adsorption material as claimed in claim 1 or 2, characterized in that: The following steps are involved: S1, dissolving ZrCl4, 2-aminoterephthalic acid and hydrochloric acid in N,N-dimethylformamide, heating to 120°C, and reacting for 24 hours to obtain the metal organic framework UIO66, namely UIO66-NH2; S2, mixing the UIO66-NH2 and dichloroalkane with xylene, heating to 80°C and stirring for 2 hours to obtain chlorinated UIO66, i.e., UIO66-Cl; S3, mixing imidazole, chloramine salt and triethylamine with xylene, heating to 80°C and stirring continuously for 6 hours to obtain aminoimidazole; S4, placing the UIO66-Cl and the aminoimidazole in xylene, heating to 80° C. and continuously stirring for 8 hours to obtain ionic liquid-modified UIO66, namely, UIO66-IL-NH2; S5, placing the UIO66-IL-NH2 and glycidyl methacrylate in anhydrous ethanol, mixing, heating to 70° C. and continuously stirring for 4 hours to obtain GMA-ionic liquid modified UIO66, i.e., UIO66-IL-GMA; S6. Add UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent to anhydrous ethanol in sequence, mix, heat to 70° C. and continue stirring for 6 hours to obtain a metal organic framework adsorption material.

4. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of ZrCl4, 2-aminoterephthalic acid, hydrochloric acid and N,N-dimethylformamide in S1 is 1:1-2:0.5-3:5-10.

5. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of UIO66-NH2 and dichloroalkane described in S2 is 1:1-3.

6. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of imidazole, chloramine salt and triethylamine in S3 is 1:0.5-3:0.1-0.

3.

7. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of UIO66-Cl to aminoimidazole in S4 is 1:0.2-5.

8. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of UIO66-IL-NH2 and glycidyl methacrylate in S5 is 1:0.1-6.

9. The method for preparing a metal organic framework adsorption material according to claim 3, characterized in that: The mass ratio of UIO66-IL-GMA, plant essential oil, pore-forming agent and cross-linking agent in S6 is 1:0.1-1:0.1-0.5:0.2-2.

10. Use of the metal organic framework adsorption material as claimed in claim 1 or 2 in the selective adsorption of alcohol and ketone essential oils.

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