Metal organic framework as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic materials, in particular to a metal organic framework and a preparation method and application thereof, and the metal organic framework is CuBaTi MOFs. Wherein the metal organic framework has a layered structure and a porous structure; the CuBaTi MOFs is modified by a surface active agent; and the CuBaTi MOFs are compounded through mineral components. The metal organic framework can effectively inhibit bacteria and adsorb ethylene, the metal organic framework is made into an antibacterial film, fresh keeping and antibiosis of vegetables and fruits can be achieved, ripening and decay of the vegetables and fruits are delayed, the metal organic framework has good mechanical performance, and meanwhile the preparation method of the metal organic framework is simple, convenient, low in cost, environmentally friendly and wide in application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic materials, in particular to a metal organic framework and a preparation method and application thereof. BACKGROUND

[0002] Traditional food preservation films are usually made of polyethylene (PE), polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC) and other polymer materials, and mainly delay food spoilage through physical barrier (such as oxygen and water vapor isolation). However, such materials can only passively prevent external microbial contamination and cannot inhibit the growth of existing bacteria, mold and other microorganisms on the surface of food, resulting in limited preservation effect, especially for high-moisture and high-nutrition foods (such as meat, fruits and vegetables, dairy products, etc.).

[0003] With the increasing demand for food safety and shelf life extension, simple physical barrier cannot meet the requirements. Food is prone to microbial contamination during processing, transportation and storage, leading to spoilage and even foodborne diseases. Therefore, the development of preservation films with active antibacterial function has become a research hotspot, aiming to inhibit or kill pathogenic bacteria (such as Escherichia coli, Staphylococcus aureus, Salmonella, etc.) and spoilage microorganisms on the surface of food, thereby extending the shelf life of food.

[0004] The core of antibacterial film is to introduce antibacterial ingredients into traditional high molecular substrates, so that it has sustained or slow-release antibacterial performance. The current main technical routes include: a, natural antibacterial agents: such as chitosan (with broad-spectrum antibacterial properties), plant essential oils (such as cinnamyl aldehyde, thymol), lysozyme, etc., which are concerned due to their safety and biodegradability; b, inorganic antibacterial agents: such as nano-silver (Ag), nano-zinc oxide (ZnO), nano-titanium dioxide (TiO2), which destroy microbial structure through metal ion release or photocatalytic effect; c, organic synthetic antibacterial agents: such as quaternary ammonium salts, potassium sorbate, etc., which interfere with microbial cell membrane function through charge effect; d, composite antibacterial system: combining multiple antibacterial agents or carriers (such as cyclodextrin, nano-cellulose) to improve synergistic effect and slow-release performance.

[0005] Although antibacterial film has broad prospects, the following problems still need to be solved in technical implementation: antibacterial performance depends on silver, zinc and other metal coatings, which have problems such as high cost, heavy metal migration risk, narrow antibacterial spectrum, etc. In addition, traditional films cannot effectively adsorb ethylene gas released by fruits and vegetables, leading to accelerated ripening and shortened shelf life.

[0006] Therefore, it is necessary to develop a new antibacterial film. SUMMARY

[0007] The application aims to solve the problems of insufficient antibacterial performance and weak ethylene regulation ability of traditional fruit and vegetable packaging, and provides a metal organic framework and a preparation method and application thereof, which can effectively inhibit bacteria and adsorb ethylene, and the antibacterial film made of the metal organic framework can not only realize fresh-keeping and antibacterial of fruits and vegetables, delay ripening and corruption of fruits and vegetables, but also has good mechanical properties, and the preparation method of the metal organic framework is simple and convenient, low in cost, green and environment-friendly, and has wide application prospect.

[0008] To achieve the above-mentioned purpose, in a first aspect, the application provides a metal organic framework, which is CuBaTi MOFs; wherein,

[0009] The metal organic framework has a layered structure and a porous structure.

[0010] The CuBaTi MOFs are modified by a surfactant.

[0011] The CuBaTi MOFs are compounded with a mineral component.

[0012] Preferably, the surfactant is hexadecyl trimethyl ammonium bromide.

[0013] Preferably, the mineral component is carboxylated nanomica and / or diatomite.

[0014] In a second aspect, the application provides a preparation method of the metal organic framework according to the first aspect, and the preparation method comprises:

[0015] 1) dissolving a copper source and a barium source in a solvent to perform first mixing, adding a titanium source to perform second mixing, adding a ligand to perform third mixing, and performing microwave solvent thermal reaction to obtain a copper-barium-titanium three-dimensional framework;

[0016] 2) modifying the copper-barium-titanium three-dimensional framework with a surfactant, and then adding a mineral component to perform ultrasonic compounding.

[0017] Preferably, in step 1), the copper source is selected from one or two or more of copper sulfate, copper nitrate, copper chloride and copper acetate.

[0018] Preferably, in step 1), the barium source is selected from barium chloride and / or barium nitrate.

[0019] More preferably, in step 1), the titanium source is selected from one or two or more of tetrabutyl titanate, titanium tetrachloride and isopropyl titanate.

[0020] Further preferably, in step 1), the solvent is an aqueous solution of N,N-dimethylformamide.

[0021] More preferably, the ligand is selected from one or two or more of trimesic acid, terephthalic acid and 2-methylimidazole.

[0022] Preferably, in step 1), the molar ratio of the copper source, barium source, titanium source and ligand is 1:0.5-2:0.5-2:1-3, wherein the copper source is calculated as copper ions, the barium source is calculated as barium ions, and the titanium source is calculated as titanium ions.

[0023] Preferably, in step 1), the first mixing conditions include a temperature of 15-30° C., an ultrasonic power of 200-400 W, and a time of 10-30 min.

[0024] Preferably, in step 1), the second mixing conditions include: temperature of 15-30° C., ultrasonic power of 200-400 W, and time of 10-30 min.

[0025] More preferably, in step 1), the conditions for the third mixing include: temperature of 15-30° C., stirring rate of 300-600 rpm, and time of 10-30 min.

[0026] Further preferably, in step 1), the conditions of the microwave solvothermal reaction include: microwave power of 200-500W, temperature of 110-150°C, and time of 20-60min.

[0027] Preferably, in step 2), the surfactant is cetyltrimethylammonium bromide.

[0028] Preferably, in step 2), the mineral component is carboxylated nano-mica and / or diatomaceous earth.

[0029] Preferably, in step 2), the concentration of the surfactant is 0.01-0.05 mol / L.

[0030] Preferably, in step 2), the mass ratio of the copper-barium-titanium three-dimensional framework to the mineral components is 1:1-5.

[0031] Preferably, in step 2), the modification conditions include: temperature of 40-80° C., ultrasonic power of 200-400 W, and time of 10-30 min.

[0032] Preferably, in step 2), the compounding conditions include: temperature of 15-30° C., ultrasonic power of 200-400 W, and time of 10-30 min.

[0033] In a third aspect, the present invention provides an antibacterial film, characterized in that the antibacterial film comprises the metal organic framework as described in the first aspect and PE resin.

[0034] In the above technical solution, the metal organic framework CuBaTi MOFs of the present invention contains Cu 2+ and Ti 4+ , where Cu 2+ and Ti 4+ By destroying the bacterial cell membrane and inducing the generation of reactive oxygen species (ROS), the antibacterial rate against pathogenic bacteria and molds on the surface of fruits and vegetables is ≥99.99%; the metal-organic framework is modified with CTAB, and the hydrophobic alkyl chain of CTAB is inserted into the phospholipid bilayer of the bacterial membrane, destroying the membrane integrity; the positively charged quaternary ammonium group combines with the negatively charged groups on the membrane surface (such as phospholipid head group), causing membrane perforation, and the physical confinement of CTAB by the MOFs pores delays its release rate, thereby achieving long-term antibacterial effect.

[0035] Furthermore, the Ba in the metal organic framework CuBaTi MOFs of the present invention 2+ π-complexation of Ba 2+ The d orbital electrons of Cu / Ti delocalize with the π bond electron cloud of ethylene to form a stable ethylene adsorption complex; at the same time, the open sites of Cu / Ti synergistically adsorb ethylene, and Cu 2+ The Lewis acid sites of Ti enhance the adsorption strength of ethylene through charge transfer, while 4+ The coordinated unsaturated sites improve the ethylene capture rate through dynamic adsorption-desorption equilibrium; MOFs pore breathing effect: CO2 adsorption causes a slight shrinkage of the MOFs skeleton (pore size reduction), further enhancing the ethylene retention capacity through size screening effect.

[0036] The antibacterial film prepared from the metal organic framework CuBaTi MOFs of the present invention has a spontaneous gas conditioning effect and can spontaneously form a low-oxygen (reduced O2 concentration) and high-CO2 gas microenvironment. This environment inhibits the aerobic metabolic pathway in the respiration of fruits and vegetables, delays ripening and corruption, and has high mechanical properties due to the addition of mineral components and the metal organic framework for compounding.

[0037] At the same time, the metal organic framework CuBaTi MOFs of the present invention is prepared by a solvent thermal method, which has simple conditions, is easy to operate, is convenient for industrial mass production, and has broad application prospects.

[0038] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0040] Figure 1X-ray diffraction (XRD) analysis chart of CuBaTi MOFs prepared for the present application embodiment 1;

[0041] Figure 2 TEM chart of CuBaTi MOFs prepared for the present application embodiment 1;

[0042] Figure 3 FTIR analysis chart of MOFs film prepared for the present application application example 1;

[0043] Figure 4 SEM chart of MOFs film prepared for the present application application example 1;

[0044] Figure 5 TGA analysis chart of MOFs film prepared for the present application application example 1;

[0045] Figure 6 Appearance change record of perfume lemon during the experimental process of the present application detection example 6;

[0046] Figure 7 Trend chart of each index of perfume lemon during the experimental process of the present application detection example 6;

[0047] Figure 8 Appearance change record of broccoli during the experimental process of the present application detection example 7;

[0048] Figure 9 Trend chart of each index of broccoli during the experimental process of the present application detection example 7. DETAILED DESCRIPTION

[0049] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the present application, and are not intended to limit the present application.

[0050] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and the values are approximate values and should be understood to include values approximately the same as the stated values. For ranges, the endpoints are included in the ranges, and the ranges are inclusive of the single values therein. For values with increments, the increments are included in the values.

[0051] In a first aspect, the present application provides a metal organic framework, the metal organic framework is CuBaTi MOFs; wherein,

[0052] The metal organic framework has a layered structure and a porous structure;

[0053] The CuBaTi MOFs are modified by a surfactant;

[0054] The CuBaTi MOFs are compounded with mineral components.

[0055] The metal organic framework CuBaTi MOFs of the present application contain Cu 2+ and Ti 4+ , wherein Cu 2+ and Ti 4+ have antibacterial rates of ≥ 99.99% on pathogenic bacteria and mold on the surface of fruits and vegetables by destroying the bacterial cell membrane and inducing the generation of reactive oxygen species (ROS); the metal organic framework is further modified using CTAB, the hydrophobic alkyl chain of CTAB is inserted into the phospholipid bilayer of the bacterial membrane to destroy the membrane integrity; the positively charged quaternary ammonium group binds with the negative groups on the membrane surface (such as the head group of phospholipid) to induce membrane perforation, and the physical confinement of the MOF channel to CTAB delays its release rate, thereby achieving long-acting antibacterial effect.

[0056] Further, Ba 2+ in the metal organic framework CuBaTi MOFs of the present application has π-complexation effect 2+ , the d-orbital electrons of Ba 2+ and the π-bond electron cloud of ethylene undergo delocalization effect to form stable ethylene adsorption complex; at the same time, Cu / Ti open sites synergistically adsorb ethylene, the Lewis acid sites of Cu 2+ enhance the adsorption strength of ethylene through charge transfer, and the coordination unsaturated sites of Ti 4+ improve the ethylene capture rate through dynamic adsorption-desorption equilibrium; MOF channel breathing effect: CO2 adsorption will cause slight shrinkage of the MOF framework (pore size reduction), which further enhances the interception ability of ethylene through size sieving effect.

[0057] In a preferred embodiment of the present application, the surfactant is cetyltrimethylammonium bromide.

[0058] In a preferred embodiment of the present application, the mineral component is carboxylated nanomica and / or diatomite.

[0059] In a second aspect, the present application provides a preparation method of the metal organic framework as described in the first aspect, the preparation method comprising:

[0060] 1) dissolving a copper source and a barium source in a solvent for first mixing, adding a titanium source for second mixing, adding a ligand for third mixing, and performing microwave solvothermal reaction to obtain a copper-barium-titanium three-dimensional framework;

[0061] 2) modifying the copper-barium-titanium three-dimensional framework with a surfactant, and further adding a mineral component for ultrasonic compounding.

[0062] The metal organic framework CuBaTi MOFs are prepared by a solvent thermal method, simple conditions, easy to operate, and convenient for industrial mass production, and have a wide application prospect.

[0063] In a preferred embodiment of the present application, in step 1), the copper source is selected from one or more of copper sulfate, copper nitrate, copper chloride and copper acetate.

[0064] In a preferred embodiment of the present application, in step 1), the barium source is selected from barium chloride and / or barium nitrate.

[0065] In a preferred embodiment of the present application, in step 1), the titanium source is selected from one or more of tetrabutyl titanate, titanium tetrachloride and isopropyl titanate.

[0066] In a preferred embodiment of the present application, in step 1), the solvent is an aqueous solution of N,N-dimethylformamide.

[0067] In a preferred embodiment of the present application, in step 1), the ligand is selected from one or more of trimesic acid, terephthalic acid and 2-methylimidazole.

[0068] In a preferred embodiment of the present application, in step 1), the molar ratio of the copper source, the barium source, the titanium source and the ligand is 1:0.5-2:0.5-2:1-3, wherein the copper source is calculated as copper ions, the barium source is calculated as barium ions, and the titanium source is calculated as titanium ions.

[0069] In a preferred embodiment of the present application, in step 1), the conditions of the first mixing include a temperature of 15-30°C, an ultrasonic power of 200-400W and a time of 10-30min.

[0070] In a preferred embodiment of the present application, in step 1), the conditions of the second mixing include a temperature of 15-30°C, an ultrasonic power of 200-400W and a time of 10-30min.

[0071] In a preferred embodiment of the present application, in step 1), the conditions of the third mixing include a temperature of 15-30°C, a stirring rate of 300-600rpm and a time of 10-30min.

[0072] In a preferred embodiment of the present application, in step 1), the conditions of the microwave solvent thermal reaction include a temperature of 110-150°C and a time of 20-60min.

[0073] In a preferred embodiment of the present application, in step 2), in order to regulate the microenvironment of the pores, inhibit the excessive growth of the crystal grains and optimize the adsorption sites of the MOFs for ethylene, the surfactant is cetyltrimethylammonium bromide.

[0074] In a preferred embodiment of the present invention, in step 2), in order to improve the mechanical properties and gas barrier properties of the film, the mineral component is carboxylated nano-mica and / or diatomaceous earth.

[0075] In a preferred embodiment of the present invention, in step 2), the concentration of the surfactant is 0.01-0.05 mol / L.

[0076] In a preferred embodiment of the present invention, in step 2), the mass ratio of the copper-barium-titanium three-dimensional framework to the mineral components is 1:1-5.

[0077] In a preferred embodiment of the present invention, in step 2), in order to regulate the pore microenvironment, inhibit excessive grain growth, and optimize the adsorption sites of MOFs for ethylene, the modification conditions include: the modification conditions include: temperature of 40-80°C, ultrasonic power of 200-400W, and time of 10-30min.

[0078] In a preferred embodiment of the present invention, in step 2), the compounding conditions include: temperature of 15-30° C., ultrasonic power of 200-400 W, and time of 10-30 min.

[0079] In a third aspect, the present invention provides an antibacterial film, characterized in that the antibacterial film comprises the metal organic framework as described in the first aspect and PE resin.

[0080] The antibacterial film prepared from the metal-organic framework CuBaTi MOFs of the present invention has a spontaneous gas-conditioning effect and can spontaneously form a low-oxygen (reduced O2 concentration) and high-CO2 gas microenvironment. This environment inhibits the aerobic metabolic pathway in the respiration of fruits and vegetables, delays ripening and corruption, and has high mechanical properties due to the addition of mineral components to the metal-organic framework for compounding.

[0081] The present invention will be described in detail below by way of examples. In the following examples, the drugs and pharmaceuticals are all conventional commercial products.

[0082] Example 1

[0083] (1) 1 mmol of copper sulfate and 1 mmol of barium chloride were dissolved in a mixed solvent of deionized water and N,N-dimethylformamide (v / v=1:1), 1 mmol of tetrabutyl titanate was added and stirred at 300 rpm, 1.5 mmol of trimesic acid was added as a ligand and mixed evenly, then transferred to a reactor and heated to 130 °C at a microwave power of 300 W for 20 min to form a Cu-BTC main frame and in situ doped with Ti. 4+ and Ba 2+, centrifuging the product after cooling, and washing the product with ethanol and deionized water for 3-5 times in sequence to obtain primary CuBaTi ternary MOFs;

[0084] (2) The primary CuBaTi ternary MOFs obtained in step (1) are modified using a 0.05 mol / L cetyltrimethylammonium bromide (CTAB) solution to inhibit excessive growth of crystal grains;

[0085] (3) A mixture of carboxylated nanometer mica (5 nm) and diatomite (20 nm pore size) (mass ratio 1:1) is mixed with the CuBaTi ternary MOFs modified by CTAB in step (2) at a mass ratio of 1:2, and then the mixture is compounded into the pore channel of the MOFs by ultrasonic co-precipitation to obtain CuBaTi MOFs, denoted as A1.

[0086] Example 2

[0087] The method of Example 1 is implemented, except that copper sulfate in step (1) is replaced by copper nitrate, and barium chloride is replaced by barium nitrate, and other conditions remain unchanged, to obtain CuBaTi MOFs, denoted as A2.

[0088] Example 3

[0089] The method of Example 1 is implemented, except that trimesic acid in step (1) is replaced by terephthalic acid, and other conditions remain unchanged, to obtain CuBaTi MOFs, denoted as A3.

[0090] Example 4

[0091] The method of Example 1 is implemented, except that the mixture of carboxylated nanometer mica (5 nm) and diatomite (20 nm pore size) in step (3) is replaced by an equal mass of carboxylated nanometer mica (5 nm), and other conditions remain unchanged, to obtain CuBaTi MOFs, denoted as A3.

[0092] The X-ray diffraction pattern of the CuBaTi MOFs of Figure 1 It can be known from the X-ray diffraction pattern of the CuBaTi MOFs of

[0093] The X-ray diffraction pattern of the CuBaTi MOFs of Figure 2The TEM image of the CubaTi MOFs shown in the figure shows that the mineral components are complexed in the microporous channels and surfaces of the CubaTi MOFs, indicating the successful synthesis of the CubaTi MOFs.

[0094] Application Example 1

[0095] (1) The ingredients are prepared according to the following ratios: 85% polyethylene resin, 3% antistatic agent, 5% ultraviolet absorber, 5% maleic anhydride graft copolymer, and 2% of the CubaTi MOFs prepared in Example 1;

[0096] (2) The above ingredients were pre-mixed in a high-speed mixer for 5-10 minutes to ensure uniform dispersion of the components. The mixture was then fed into a twin-screw extruder with a set temperature gradient of 160°C (feeding section) → 180°C (compression section) → 200-220°C (melting section) → 210°C (die section). The melt was extruded through a T-die to form a sheet-like fluid.

[0097] (3) The melt flows from the T-die to the chrome-plated cooling roller (roller temperature 15-25°C), and is rapidly cooled and shaped by the high-speed rotation of the roller to form a primary film with uniform thickness;

[0098] (4) The cooled film is pulled through a tension control system, trimmed, and then rolled up. The rolling speed is synchronously adjusted with the pulling speed to avoid wrinkles or uneven stretching, thereby obtaining a plastic film containing CubaTi MOFs, referred to as MOFs film.

[0099] Depend on Figure 3 The FTIR analysis of the MOFs film shown in the figure shows that the MOFs film has a -1 and 2160.71cm -1 A characteristic infrared absorption peak appears at , which is caused by the CH stretching vibration of CTAB, indicating that CTAB has successfully modified the original CubaTi MOFs.

[0100] like Figure 4 The SEM image of the MOFs film shown in the figure shows that the plastic film prepared using the CubaTi MOFs of the present invention has a porous structure and the film appears rough and dense, indicating that the CubaTi MOFs are effectively dispersed in the film.

[0101] Depend on Figure 5The TGA analysis of the MOFs film shows that the first weight loss stage occurs between 268°C and 400°C, with a weight loss rate of 1.8%. The second stage occurs between 400°C and 500°C. This is because the PE film begins to soften and melt at 120°C to 130°C (melting point). When the temperature exceeds 300°C, the long-chain molecules of PE begin to break and undergo thermal cracking. As the temperature gradually rises to 500°C, the PE film completely decomposes. The TGA analysis shows that the addition of CubaTi MOFs increases the melting point of the PE film and that the CubaTi MOFs exhibit excellent thermal stability before the PE film decomposes.

[0102] Test Example 1

[0103] In Application Example 1, the strength of the plastic film prepared using CuBaTi MOFs (hereinafter referred to as MOFs film) and the ordinary PE plastic film on the market (hereinafter referred to as ordinary PE) were tested. The test method was based on GB / T1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets". The test results are shown in Table 1.

[0104] Table 1

[0105]

[0106] It can be seen from the data in Table 1 that the plastic film prepared by the CubaTi MOFs of the present invention has better tensile strength than ordinary plastic films on the market.

[0107] Test Example 2

[0108] In Application Example 1, the anti-adhesion performance of the plastic film prepared using CuBaTi MOFs (referred to as MOFs film) and the ordinary PE plastic film on the market (referred to as ordinary PE) was tested. The test method referred to GB / T 10006-2021 "Determination of the friction coefficient of plastic films and sheets". The test results are shown in Table 2.

[0109] Table 2

[0110] Static friction coefficient Dynamic friction coefficient MOFs thin films 0.183 0.159 Ordinary PE 0.367 0.352

[0111] Test Example 3

[0112] In Application Example 1, the anti-adhesion properties of a plastic film prepared using CuBaTi MOFs (hereinafter referred to as MOFs film) and a commercially available ordinary PE plastic film (hereinafter referred to as ordinary PE) were tested. The test method referred to the ASTM D3354 parallel plate method for measuring the adhesion load of the plastic film. The test results are shown in Table 3.

[0113] Table 3

[0114] Peel force (N / cm) MOFs thin films 0.3 Ordinary PE 0.8

[0115] It can be seen from the data in Table 2 and Table 3 that the plastic film prepared by the CubaTi MOFs of the present invention has better anti-adhesion performance than ordinary plastic films on the market.

[0116] Test Example 4

[0117] The antibacterial properties of the plastic film prepared using CuBaTi MOFs (referred to as MOFs film) and the ordinary PE plastic film on the market (referred to as ordinary PE) in Application Example 1 were tested. The test method was based on GB / T31402-2023 "Determination of antibacterial activity on the surface of plastics and other non-porous materials". The test results are shown in Table 4.

[0118] Table 4

[0119] Escherichia coli inhibition rate (%) Staphylococcus aureus inhibition rate (%) MOFs thin films 99.99 99.99 Ordinary PE 0.52 0.27

[0120] As can be seen from the data in Table 4, the antibacterial performance of the plastic film prepared by the CubaTi MOFs of the present invention is much higher than that of ordinary plastic films on the market, indicating that the plastic film of the present invention has better antibacterial performance.

[0121] Test Example 5

[0122] In Application Example 1, the ethylene adsorption rates of the plastic film prepared using CubaTi MOFs (hereinafter referred to as MOFs film) and the ordinary PE plastic film on the market (hereinafter referred to as ordinary PE) were tested. The test method was based on GB21551.4-2024 "Antibacterial, sterilization, and purification functions of household and similar electrical appliances" and an ethylene adsorption test was conducted in a 3.9 L glass box. The results are shown in Table 5.

[0123] Table 5

[0124] Ethylene adsorption rate (%) Plastic film containing CubaTi MOFs 62.86 Ordinary plastic film 4.73

[0125] As can be seen from the data in Table 5, the ethylene adsorption rate of the plastic film prepared by the CubaTi MOFs of the present invention is much higher than that of ordinary plastic films on the market, indicating that the plastic film of the present invention has better preservation ability.

[0126] Test Example 6

[0127] The specific method for determining the freshness-locking performance of perfume lemon is as follows:

[0128] (1) The plastic film prepared using CuBaTi MOFs in Application Example 1 (hereinafter referred to as MOFs film) and ordinary PE plastic film on the market (hereinafter referred to as ordinary PE) were prepared into 30×45 cm packaging bags;

[0129] (2) Select lemons with consistent maturity, no mechanical damage, no decay, and similar specifications, and use MOFs film and ordinary PE for packaging respectively. Set up 5 parallel groups of MOFs film and ordinary PE, each group has 5 catties of lemons, and ensure that each group of fruits has the same air volume after packaging;

[0130] (3) The above-mentioned perfume lemons were stored at room temperature of 25°C in the dark. The appearance was recorded by taking photos every 3 days. The weight loss rate, yellowing rate, Vc content, soluble solid content, O2 / CO2 volume fraction in the bag, peroxidase (POD) content and polyphenol oxidase (PPO) content of the perfume lemons were measured. The results are shown in Table 6 and Table 6. Figure 6-Figure 7 shown.

[0131] Wherein, weight loss rate determination: the weight of the perfume lemon was measured using a balance, and the weight loss rate was calculated by the difference between the weight before and after, weight loss rate = (initial weight - measured weight) / initial weight × 100%;

[0132] Yellowing rate determination: Yellowing rate = number of yellowed fruits / total number of fruits in the group × 100%;

[0133] Determination of Vitamin C content: Referring to GB 5009.86-2016 "National Food Safety Standard - Determination of Ascorbic Acid in Foods", the Vitamin C content was determined by the third method 2,6-dichloroindophenol titration method, and the test was repeated three times;

[0134] Determination of soluble solids content: Use a portable digital refractometer.

[0135] O2 / CO2 volume fraction measurement: Use a portable O2 / CO2 meter to measure the gas volume fraction in the package;

[0136] Peroxidase (POD) content determination: The peroxidase content was determined by spectrophotometry;

[0137] Polyphenol oxidase (PPO) content was determined by spectrophotometry.

[0138] Table 6

[0139]

[0140]

[0141] From the data in Table 6 and Figure 6-Figure 7 As can be seen from the results, the various indicators of the preservation of perfume lemons using the MOFs film of the present invention are superior to those of the ordinary PE film on the market, indicating that the MOFs film of the present invention can better retain the moisture and nutrients of perfume lemons and delay the ripening of perfume lemons.

[0142] Test Example 7

[0143] The specific method for determining the freshness-locking performance of broccoli is as follows:

[0144] (1) The CubaTi-MOFs fresh food dormancy and freshness-locking film (referred to as MOFs film) and ordinary blank PE film (referred to as ordinary PE) were prepared into 25×30 cm packaging bags;

[0145] Broccoli of similar size, without mechanical damage or decay, was selected and packaged using MOFs film and ordinary PE. Ten parallel groups of 10 broccoli florets were set up in each group, with 10 broccoli florets in each group. After packaging, the air volume in each group was guaranteed to be the same.

[0146] (3) The broccoli was sealed and stored in a cold storage at a temperature of 0-5°C and a relative humidity of 90%-95%. The appearance of the broccoli was recorded and photographed every 3 days. The weight loss rate, yellowing rate, Vc content, soluble solid content, chlorophyll content, O2 / CO2 volume fraction in the bag, peroxidase (POD) content and polyphenol oxidase (PPO) content of the broccoli were measured. The results are shown in Table 7 and Figure 8-Figure 9 shown.

[0147] The weight loss rate was determined by using a balance to measure the weight of the broccoli. The weight loss rate was calculated by the difference between the initial weight and the measured weight. The weight loss rate = (initial weight - measured weight) / initial weight × 100%;

[0148] Yellowing rate determination: Yellowing rate = number of yellowed pieces / total number of pieces in the group × 100%;

[0149] Determination of Vitamin C content: Referring to GB 5009.86-2016 "National Food Safety Standard - Determination of Ascorbic Acid in Foods", the Vitamin C content was determined by the third method 2,6-dichloroindophenol titration method, and the test was repeated three times;

[0150] Determination of soluble solid content: using a portable digital refractometer;

[0151] Chlorophyll content determination: Use a portable chlorophyll meter to measure;

[0152] O2 / CO2 volume fraction measurement: Use a portable O2 / CO2 meter to measure the gas volume fraction in the package;

[0153] Peroxidase (POD) content determination: The peroxidase content was determined by spectrophotometry;

[0154] Polyphenol oxidase (PPO) content was determined by spectrophotometry.

[0155] Table 7

[0156]

[0157]

[0158] From the data in Table 7 and Figure 8-Figure 9 It can be seen from the content that various indicators obtained by using the MOFs film of the present invention to preserve broccoli are better than the preservation ability of ordinary PE films on the market for broccoli, indicating that the MOFs film of the present invention can better retain the moisture and nutrients of broccoli and delay the spoilage of broccoli.

[0159] In summary, the metal-organic framework (CuBaTiMOFs) of the present invention can be used to prepare plastic films to effectively inhibit bacteria and adsorb ethylene. The antibacterial films can not only preserve fruits and vegetables and prevent bacteria, but also delay their ripening and spoilage. Furthermore, the preparation method of the metal-organic framework is simple, convenient, low-cost, and environmentally friendly, with broad application prospects.

[0160] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0161] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0162] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A metal organic framework, characterized in that The metal organic framework is CubaTi MOFs; wherein, The metal organic framework has a layered structure and a porous structure; The CubaTiMOFs are modified with a surfactant; The CubaTiMOFs are compounded with mineral components.

2. The metal organic framework according to claim 1, characterized in that The surfactant is selected from one or two or more of cetyltrimethylammonium bromide, sodium lauryl sulfate and cetyltrimethylammonium chloride; Preferably, the mineral component is carboxylated nano-mica and / or diatomaceous earth.

3. A method for preparing a metal organic framework according to claim 1 or 2, characterized in that: The preparation method comprises: 1) dissolving a copper source and a barium source in a solvent for a first mixing, adding a titanium source for a second mixing, adding a ligand for a third mixing, and performing a microwave solvothermal reaction to obtain a copper-barium-titanium three-dimensional framework; 2) The copper-barium-titanium three-dimensional framework is modified with a surfactant, and then mineral components are added for ultrasonic compounding.

4. The preparation method according to claim 3, characterized in that In step 1), the copper source is selected from one or two or more of copper sulfate, copper nitrate, copper chloride and copper acetate; Preferably, the barium source is selected from barium chloride and / or barium nitrate; More preferably, the titanium source is selected from one or two or more of tetrabutyl titanate, titanium tetrachloride and isopropyl titanate; Further preferably, the solvent is an aqueous solution of N,N-dimethylformamide; More preferably, the ligand is one or two or more of trimesic acid, terephthalic acid and 2-methylimidazole.

5. The preparation method according to claim 3 or 4, characterized in that In step 1), the molar ratio of the copper source, barium source, titanium source and ligand is 1:0.5-2:0.5-2:1-3, wherein the copper source is calculated as copper ions, the barium source is calculated as barium ions, and the titanium source is calculated as titanium ions.

6. The preparation method according to any one of claims 3 to 5, characterized in that In step 1), the first mixing conditions include: temperature of 15-30° C., ultrasonic power of 200-400 W and time of 10-30 min; Preferably, the second mixing conditions include: temperature of 15-30°C, ultrasonic power of 200-400W and time of 10-30min; More preferably, the conditions for the third mixing include: temperature of 15-30°C, stirring rate of 300-600 rpm, and time of 10-30 min; Further preferably, the conditions of the microwave solvothermal reaction include: microwave power of 200-500W, temperature of 110-150°C, and time of 20-60min.

7. The preparation method according to any one of claims 3 to 6, characterized in that In step 2), the surfactant is selected from one or two or more of cetyltrimethylammonium bromide, sodium lauryl sulfate and cetyltrimethylammonium chloride; Preferably, the mineral component is carboxylated nano-mica and / or diatomaceous earth.

8. The preparation method according to any one of claims 3 to 7, characterized in that In step 2), the concentration of the surfactant is 0.01–0.05 mol / L; Preferably, the mass ratio of the copper-barium-titanium three-dimensional framework to the mineral components is 1:1-5.

9. The preparation method according to any one of claims 3 to 8, characterized in that In step 2), the modification conditions include: temperature of 40-80°C, ultrasonic power of 200-400W, and time of 10-30min; Preferably, the compounding conditions include: temperature of 15-30° C., ultrasonic power of 200-400 W, and time of 10-30 min.

10. An antibacterial film, characterized in that: The antibacterial film comprises the metal organic framework according to claim 1 or 2 and PE resin.

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