Metal organic framework material for adsorbing antibiotics as well as preparation method and application of metal organic framework material

Abstract

The invention discloses a method for adsorbing and treating antibiotics in a water body by using a zeolite imidazate framework material prepared from an ionic liquid, which comprises the following steps: synthesizing the zeolite imidazate framework material by using an ionothermal method, and carrying out contact adsorption on the zeolite imidazate framework material and an aqueous solution containing the antibiotics to finish adsorption removal of the antibiotics in the aqueous solution, the ionothermal synthesis zeolite imidazate framework material can realize effective adsorption of cephalosporin antibiotics in an aqueous solution, the synthesis method is simple, convenient to operate, good in adsorption and removal effect and good in material reusability, and as a treatment method which can be commonly used and can effectively adsorb and remove the antibiotics in the aqueous solution, the zeolite imidazate framework material has good application prospects. And the method has certain application potential in practical application.

Description

Technical Field

[0001] The present invention belongs to the technical field of removing pollutants in aqueous systems, and particularly relates to the preparation and application of a metal-organic framework material prepared by an ionothermal method. Background Art

[0002] In recent years, the accumulation of antibiotics in the environment has become a major issue of global concern. Extensive agricultural production and medical activities have led to a large amount of antibiotics being discharged into the environment. Due to the broad-spectrum antibacterial properties and relatively low drug resistance of cephalosporin antibiotics, they are widely used in the treatment of human and animal diseases, and the demand is gradually increasing. These antibiotics have had a serious impact on the environment, such as generating biological drug resistance, disturbing the ecological balance, and posing a potential threat to human health. Traditional water treatment technologies such as biofilm treatment, chemical oxidation, and biodegradation are limited in removing these antibiotics. Therefore, finding new effective methods to treat water bodies contaminated with these antibiotics has become an important topic in environmental science research. Metal-organic frameworks (MOFs), as a new type of adsorbent material, have attracted extensive attention.

[0003] Zeolitic imidazolate frameworks (ZIFs) are a type of MOF material. Their structure is similar to that of conventional aluminosilicate zeolites, and their basic composition is M-IM-M (M represents zinc or cobalt cations, and IM represents the imidazolate moiety), which is constructed by a self-assembly method. The properties of zeolitic imidazolate frameworks, such as high crystallinity, good thermal and chemical stability, and ultra-high surface area, make them applicable in fields such as catalysis, separation, and sensing.

[0004] ZIFs materials are synthesized by hydrothermal or solvothermal methods using water or methanol as the reaction system. With the rapid development of research, in recent years, many new methods for synthesizing ZIFs materials have emerged. A new type of ionothermal synthesis method using ionic liquids or eutectics as solvents can be used for the synthesis of ZIFs materials. Ionic liquids are substances composed of ions that are liquid at room temperature, with advantages such as a large liquid temperature range, a wide dissolution range, low vapor pressure, good stability, and non-flammability, making them safer and more environmentally friendly. A good green solvent after supercritical carbon dioxide, it can be an ideal alternative to traditional volatile solvents. Researchers such as Morris first synthesized ZIFs materials using ionic liquids and synthesized four different ZIFs materials using the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. Summary of the Invention

[0005] The present invention aims to provide a method for preparing zeolitic imidazolate framework materials using ionic liquids to adsorb and treat antibiotics in water. The zeolitic imidazolate framework prepared by this method has regular pore structures and uniform pore sizes, and has good application prospects in adsorbing and removing antibiotics in aqueous solutions.

[0006] In the present invention, choline chloride and urea are selected as solvents, and ZIF-8 is prepared by an ionothermal synthesis method.

[0007] The specific experimental steps are as follows:

[0008] (1) Choline chloride and urea are added to a round-bottom flask according to a molar ratio, and the flask is placed on a heating magnetic stirrer, heated and stirred for 1 to 5 hours to form an ionic liquid;

[0009] (2) Zinc nitrate hexahydrate and dimethylimidazole (molar ratio 8:1 to 1:8) are added to the ionic liquid, the temperature is controlled at 60 to 80 °C, and continuously stirred for 1 to 6 hours, and then cooled to room temperature to obtain a colloidal solution.

[0010] (3) After the stirring stops, absolute ethanol and deionized water are added thereto, a large amount of white solid is generated in the flask, and after standing for a period of time, the required product is obtained by centrifugation.

[0011] The instruments for detecting the co-crystal structure and properties of the drug in the present invention are as follows:

[0012] 1. X-ray diffractometer: model X PERT3 POWDER, Tube voltage 50 kV, tube current 200 mA, scanning speed 5° / min.

[0013] 2. The nitrogen adsorption and desorption curve is tested on an Autosorb-Ql micropore analyzer of Quantacllrome Instruments Company. Before the test, the sample is degassed and activated at a specific temperature under high vacuum.

[0014] Antibiotics are a class of secondary metabolites produced by microorganisms (including bacteria, fungi, and actinomycetes) or higher plants and animals during their life cycles. These compounds have the ability to combat pathogens or other biological activities and can interfere with the growth and development functions of other biological cells. Common antibiotics include antibiotics extracted from microbial culture broths such as tetracyclines, macrolides, β-lactams, and aminoglycosides, as well as drugs synthesized or semi-synthesized by chemical methods such as quinolones and sulfonamides. Among them, cephalosporin antibiotics, belonging to a subclass of β-lactam antibiotics, are also a widely used class of antibiotics. They have broad-spectrum antibacterial properties and can combat a variety of bacterial infections, including Gram-positive bacteria and Gram-negative bacteria. They mainly act by binding to specific targets in bacteria, namely bacterial penicillin-binding proteins (PBPs), thereby interfering with the synthesis of the bacterial cell wall, causing the bacteria to lose their protective cell wall, and ultimately leading to the death of the bacteria. Due to the broad-spectrum antibacterial properties of cephalosporin antibiotics and their relatively low drug resistance, they are widely used in the treatment of human and animal diseases, and the demand is gradually increasing. Brief Description of the Drawings

[0015] The technical solutions and their effects of the present invention will become obvious by combining the following drawings and describing the specific embodiments of the present invention in detail. Figure 1 Chemical structural formulas of cephalexin and cefradine

[0016] Figure 2 XRD pattern of the zeolitic imidazolate framework material prepared in the embodiment of the present invention;

[0017] Figure 3 Nitrogen adsorption / desorption isotherm of the zeolitic imidazolate framework material prepared in the embodiment of the present invention, with the black curve being the adsorption curve and the red curve being the desorption curve;

[0018] Figure 4 Adsorption effect diagrams of the zeolitic imidazolate framework material prepared in the embodiment of the present invention for different antibiotics.

[0019] It can be observed from the figure that ZIF-8 exhibits multiple diffraction peaks, mainly appearing at positions such as 2Theta = 7.3°, 10.3°, 12.6°, 14.6°, 16.4°, 17.9°, etc. According to the reports in the literature, these angles correspond to the (011), (002), (112), (022), (013), (222) planes respectively. Especially at 2Theta = 7.3°, ZIF-8 exhibits the sharpest peak, indicating that the synthesized material has a high degree of crystallinity. Through XRD characterization and analysis, it can be determined that a ZIF-8 material with high crystallinity has been successfully synthesized.

[0020] To study the specific surface area and pore size distribution of ZIF-8, BET analysis was performed on ZIF-8. As Figure 3 can be seen, the nitrogen adsorption / desorption isotherm of the ZIF-8 sample conforms to the type I isotherm. The type I isotherm shows obvious adsorption in the low-pressure region, indicating that ZIF-8 has a microporous structure and a relatively high specific surface area. The BET surface area of ZIF-8 is 1006.966 m 2 / g. The pore size distribution diagram shows a sharp peak at 6.3 nm, indicating that the pore size of ZIF-8 is 6.3 nm.

[0021] To study the adsorption effects of ZIF-8 on cephalexin and cefradine, two antibiotic solutions with a concentration of 20 mg / L were selected, and adsorption kinetics experiments were carried out at 20 °C. The experimental results are shown in the figure. The experimental results show that the adsorption effect of ZIF-8 on cefradine is better than that on cephalexin. The chemical structures of the two antibiotics are similar, but there are differences in the side chain groups. The side chain group of cephalexin contains 1,4-cyclohexadienyl, while the same position of the side chain group of cefradine is a benzene ring. Due to its stable conjugated π-electron system, the benzene ring can have strong interactions with the surface of the adsorbent through van der Waals forces, π-π stacking, electrostatic interactions, etc. However, due to its non-aromaticity and weak conjugation, the interaction between 1,4-cyclohexadiene and the adsorbent may be weak, resulting in differences in the interaction between it and the adsorbent. Specific Embodiments

[0022] The transparent glass instruments used in the invention are domestic. The following is a further description of the application examples of the invention. The method for preparing zeolitic imidazolate framework materials using ionic liquids is as follows:

[0023] Example:

[0024] Preparing zeolitic imidazolate framework materials using ionic liquids:

[0025] Weighing:

[0026] Choline chloride and urea were fed in a molar ratio of 1:2. Using an analytical balance, 1.124 g of choline chloride and 0.224 g of urea were accurately weighed and placed into a round-bottom flask.

[0027] Heating:

[0028] The round-bottom flask was placed on a magnetic stirrer and heated at 70 °C for 2 hours to form an ionic liquid.

[0029] Weighing:

[0030] Zinc nitrate hexahydrate and 2-methylimidazole were fed in a molar ratio of 1:7. 0.152 g of zinc nitrate hexahydrate and 0.334 g of 2-methylimidazole were weighed with an analytical balance. They were added to the ionic liquid, stirred for 5 hours, and cooled to room temperature to obtain a colloidal solution. After stopping stirring, absolute ethanol and deionized water were added thereto, a large amount of white solid was produced, and the desired product was obtained by centrifugation after standing.

Claims

1. Synthesize ZIF-8 by a novel ion thermal synthesis method using ionic liquid or eutectic as solvent. It can be observed from the X-ray diffraction spectrum that ZIF-8 exhibits multiple diffraction peaks, mainly appearing at 2Theta = 7.3°, 10.3°, 12.6°, 14.6°, 16.4°, 17.9° and other positions.

2. The preparation method of ZIF-8 according to claim 1, comprising the following steps: (1) Choline chloride and urea are added in a molar ratio of 1:

2. Accurately weigh 1.124 g of choline chloride and 0.224 g of urea using an analytical balance and place them in a round-bottom flask; (2) placing the round-bottom flask on a magnetic stirrer and heating it at 70° C. for 2 hours to form an ionic liquid; (3) Zinc nitrate hexahydrate and dimethyl imidazole were added in a molar ratio of 1:

7. 0.152 g of zinc nitrate hexahydrate and 0.334 g of dimethyl imidazole were weighed on an analytical balance. The mixture was added to the ionic liquid, stirred for 5 hours, and cooled to room temperature to obtain a colloidal solution. After stopping the stirring, anhydrous ethanol and deionized water were added to the solution to produce a large amount of white solid. The desired product was obtained by centrifugation after standing.

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