Method for green synthesis of CaBDC MOF

Abstract

The invention provides a method for green synthesis of CaBDC MOF, which is characterized in that biological CaCO3 and waste PET plastic are respectively used as a metal source and an organic ligand source, and PDF # 46-1873 type Ca-MOF is successfully prepared through a solvent-assisted mechanical ball milling process at room temperature. The oyster shells and the clam shells used in the method are typical solid wastes in the marine food processing industry, the waste PET plastics are white wastes produced in a large amount in the food packaging industry, and the method can efficiently realize resource reutilization of the two types of solid wastes, is very green and environment-friendly, and has a wide future application prospect. The product CaBDC MOF is an ideal MOF material with good water stability, good biocompatibility and high pollutant removal performance, and the method has important significance in the fields of environmental protection, chemical industry, medicine and the like.

Description

Technical Field

[0001] The invention relates to a method for green synthesis of CaBDC MOF (BDC stands for terephthalic acid), belonging to the field of solid waste resource utilization and the technical field of metal organic framework materials. Background Art

[0002] MOF materials usually have advantages such as large specific surface area, regular pores, and adjustable structure. They are widely used in gas adsorption and separation, drug carriers, catalysis, pollutant removal, etc. However, the current method for synthesizing MOF is mainly solvothermal method, which not only requires the use of toxic and harmful organic solvents (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), but also inherently requires that the raw materials can be dissolved in organic solvents (which greatly limits the range of raw materials for preparing MOF), and the preparation cycle is also relatively long. How to prepare MOF materials in a green, low-cost and fast way is the key to its large-scale application in the future.

[0003] CaBDC is a very unique MOF material. Its remarkable features are stability in aqueous solution, low biotoxicity, and relatively light weight [Small, 2021, 17(22): 2005165]. Ahmad Zaharin Aris' research team found that soaking CaBDCMOF in aqueous solution for 5 days, placing it in a solution with a pH range of 2 to 10, or treating it with polar solvents such as methanol, acetonitrile, and n-hexane will not significantly change its XRD spectrum (Journal of Molecular Structure, 2024, 1303: 137566). Based on the above advantages, CaBDC MOF has great application potential in the future in the removal of water pollutants (heavy metals, endocrine disruptors, etc.), gas separation, and drug carriers (Water Research, 2022, 218: 118406).

[0004] CaCO 3 There are many sources in nature. For example, oysters and clams, which are the most important marine economic shellfish in my country, have CaCO as the main component of their shells. 3 (more than 92%). Moreover, the production of shellfish such as oysters and clams is very large, with tens of millions of tons produced each year worldwide. Usually, after they are eaten, their shells are discarded as garbage. Obviously, CaCO 3 can be used as a metal source for the synthesis of Ca-MOF, but conventional solvothermal methods are not feasible (CaCO 3 Insoluble in water and common organic solvents). Therefore, the use of biological CaCO 3 A green method for synthesizing CaBDC MOF is crucial for its future large-scale application. Summary of the invention

[0005] The purpose of the present invention is to provide a green method for synthesizing CaBDC MOF: using biological CaCO 3 CaBDC MOF was synthesized using waste PET (polyethylene terephthalate) plastic as the metal source and organic ligand source without using organic solvent.

[0006] To achieve the above object, the present invention provides a method for green synthesis of CaBDC MOF, and the specific technical scheme is as follows: S1. CaCO 3 and H 2 BDC is mixed thoroughly;

[0007] Wherein, the CaCO 3 Including any one of inorganic calcium carbonate, oyster shell, oyster shell, egg shell, crab shell;

[0008] The H 2 BDC can be commodity H 2 BDC, or green H obtained from the hydrolysis of PET plastic 2 BDC;

[0009] CaCO 3 With H 2 The ratio of BDC ranges from 2:1 to 1:2 in molar ratio;

[0010] CaCO 3 With H 2 BDC is in powder form and can be mixed by grinding, stirring or vibration.

[0011] S2. placing the mixture on a ball mill for mechanochemical treatment;

[0012] The ball mill is a stainless steel mill or a polytetrafluoroethylene mill, preferably a polytetrafluoroethylene mill, and the grinding balls are stainless steel balls or zirconium oxide balls, preferably zirconium oxide balls.

[0013] The ratio of the total mass of the grinding balls to the mass of the reactants is between 30:1 and 100:1;

[0014] The applicant has found through research that the ball milling process can add H 2 O(CaCO 3 1 to 50 times the molar amount), or H 2 O;

[0015] The ball milling speed ranges from 300 to 800 rpm, and the time ranges from 30 to 240 min.

[0016] S3. Washing the product after the ball milling treatment using a solvent;

[0017] The washing solvent is H 2 O and ethanol, any washing method;

[0018] The applicant has repeatedly studied and found that if H is not added during the ball milling process 2 O, then the washing process must use H 2 O.

[0019] S4. Finally, drying was performed to obtain CaBDC MOF, with the molecular formula of Ca(BDC)(H 2 O) 3 , PDF No. 46-1873;

[0020] Wherein, drying can be drying under normal conditions or vacuum drying;

[0021] Drying temperature is 60-120℃, and drying time is 6-24h.

[0022] Compared with the prior art, the advantages of the present invention include: the synthesis method of the present invention realizes the use of biological CaCO 3 CaBDC MOF was synthesized green and fast using waste PET plastic as metal source and organic ligand source without using environmentally harmful organic solvents. 2 O is a key factor in the synthesis process (H 2 O, otherwise the target product cannot be obtained), which has great guiding value for the low-cost batch synthesis of Ca-MOF using solid waste in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is the XRD diagram of the products obtained from different grinding jars in Example 1 of the present invention.

[0024] Figure 2 This is the XPS graph of the products obtained from different grinding jars in Example 1 of the present invention.

[0025] Figure 3 These are photos of the products obtained from different grinding jars in Example 1 of the present invention.

[0026] Figure 4 These are the XRD and SEM images of the products obtained by different washing methods in Example 2 of the present invention.

[0027] Figure 5 The different addition H in Example 3 of the present invention 2 XRD and SEM images of the product obtained.

[0028] Figure 6 The two H used in Examples 1 to 6 of the present invention 2Comparison chart of BDC.

[0029] Figure 7 These are the XRD and SEM images of the product obtained using oyster shells as raw materials in Example 4 of the present invention.

[0030] Figure 8 These are the XRD and SEM images of the product obtained using clam shells as raw materials in Example 5 of the present invention.

[0031] Fig. 9 These are the XRD and SEM images of the product obtained using egg shell as raw material in Example 6 of the present invention. DETAILED DESCRIPTION

[0032] The following examples will help to understand the present invention, but are not intended to limit the content of the present invention. It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

[0033] Example 1: Effect of grinding jar and grinding balls

[0034] 5 mmol of commercial H was added to a stainless steel tank (grinding balls were stainless steel balls) and a polytetrafluoroethylene tank (grinding balls were zirconium oxide balls) respectively. 2 BDC, 5mmol commercial CaCO 3 , and then 0.45 mL H 2 O, sealed and placed in a ball mill at 500 rpm for 120 min, the product was washed by centrifugation with water and ethanol, and finally dried in an ordinary oven at 80°C overnight.

[0035] The total mass of the grinding balls is 150 g, and the mass ratio of the grinding balls to the reactants is about 120:1.

[0036] Depend on Figure 1 It can be seen that the crystal forms of the products obtained from the two grinding jars are both PDF#46-1873 type CaBDC MOF.

[0037] Depend on Figure 2 It can be seen that the product obtained from the stainless steel tank (stainless steel ball) contains a small amount of Fe element, while the product obtained from the polytetrafluoroethylene tank (zirconia ball) has no Zr element remaining.

[0038] Depend on Figure 3 It can be seen that the color of the product obtained from the stainless steel tank (stainless steel ball) is iron blue, while the color of the product obtained from the polytetrafluoroethylene tank (zirconia ball) is white.

[0039] In summary, the use of polytetrafluoroethylene tanks (zirconia balls) can obtain purer CaBDC MOF, so polytetrafluoroethylene tanks (zirconia balls) are used in subsequent cases.

[0040] Example 2: Effect of washing solvent

[0041] Weigh 6 mmol of commercial CaCO 3 and 6mmol commercial H 2 BDC was placed in a centrifuge tube and vibrated and mixed using a vortex mixer. The mixture was then poured into a polytetrafluoroethylene jar and placed on a ball mill for 120 min at 600 rpm. Two groups were prepared in parallel. One group was washed with ethanol only and the other with ethanol and H 2 O, and finally dried in a conventional oven at 80°C overnight.

[0042] The total mass of the grinding balls is 150 g, and the mass ratio of the grinding balls to the reactants is about 100:1.

[0043] Depend on Figure 4 It can be seen that the product obtained by washing with ethanol only has a phase of CaCO 3 and H 2 BDC, and H 2 After washing with O, the crystalline form of the product was PDF#46-1873 type CaBDC MOF.

[0044] Combining cases 1 and 2, we can see that CaCO 3 and H 2 During the preparation of CaBDC MOF by ball milling with BDC, H 2 O (can be added during the ball milling step, or H 2 O washing).

[0045] Example 3: Adding H 2 Effect of O amount

[0046] Weigh 6 mmol of commercial CaCO 3 and 6mmol commercial H 2 BDC was ground and mixed in a mortar for 10 min, then poured into a polytetrafluoroethylene jar and placed on a ball mill for 120 min at 600 rpm, and then washed with ethanol and H 2 O, and finally dried in a conventional oven at 80°C overnight.

[0047] Two groups were made in parallel, the only difference was the addition of H during the ball milling process. 2 The amount of O was different (0.11 and 5.4 mL).

[0048] Depend on Figure 5 It can be seen that adding H 2 As the amount of O increases, the crystallinity of the product can be significantly improved, while the size of the product morphology becomes significantly smaller and the edges and corners become significantly less.

[0049] Example 4: Green Synthesis of CaBDC MOF (Oyster Shell)

[0050] 6 mmol of oyster shell and 6 mmol of green BDC (converted by hydrolysis of PET) were weighed into a polytetrafluoroethylene jar, placed on a ball mill at 150 rpm for 10 min to fully mix the two reactants, and then ball-milled at 600 rpm for 120 min. 2 O, and finally dried in a vacuum oven at 80 °C overnight.

[0051] Depend on Figure 6 It can be seen that the product H used in Examples 1 to 3 2 Compared with green BDC, there is no obvious difference in the crystal shape and surface functional groups of green BDC converted from PET, but the morphology size is significantly smaller.

[0052] Depend on Figure 7 It can be seen that after mechanical ball milling, the oyster shells were treated with PDF#05-0586 type CaCO 3 It is transformed into PDF#46-1873 type CaBDC MOF, and the morphology changes from long flakes to bricks.

[0053] Example 5: Green Synthesis of CaBDC MOF (Clam Shell)

[0054] Example 4 was repeated except that clam shells were used as the biological CaCO 3 .

[0055] Depend on Figure 8 It can be seen that after mechanical ball milling, the clam shells were purified from the PDF#41-1475 type CaCO 3 It was transformed into PDF#46-1873 type CaBDC MOF, and the morphology changed from amorphous to brick-like.

[0056] Example 6: Green synthesis of CaBDC MOF (eggshell)

[0057] Example 4 was repeated except that egg shells were used as the biological CaCO 3 .

[0058] Depend on Fig. 9 It can be seen that after mechanical ball milling, the eggshell was transformed from PDF#05-0586 type CaCO 3 It was transformed into PDF#46-1873 type CaBDC MOF, and the morphology changed from amorphous to brick-like.

[0059] From cases 4 to 6, we can see that the common biological CaCO 3 and waste PET plastics as metal sources and organic ligand sources, and the synthesis method provided by the present invention can be used to synthesize PDF#46-1873 type CaBDC MOF in a green way.

Claims

1. A method for green synthesis of CaBDC MOF, characterized in that: The molecular formula of the material is Ca(BDC)(H2O)3, the PDF number is 46-1873, and the green synthesis method thereof comprises the following steps: CaCO3 and H2BDC are fully mixed in a certain ratio, and then placed on a ball mill for mechanochemical treatment. The initial product is then washed with a solvent and finally dried to obtain Ca(BDC)(H2O)3MOF. H2BDC stands for terephthalic acid.

2. A method for green synthesis of CaBDC MOF according to claim 1, characterized in that: (1) The CaCO3 comprises any one of inorganic calcium carbonate, oyster shell, oyster shell, egg shell, and crab shell; (2) The H2BDC may be commercial H2BDC or green H2BDC converted from PET plastic; (3) The ratio of CaCO3 to H2BDC ranges from a molar ratio of 2:1 to 1:2; (4) Both CaCO3 and H2BDC are in powder form and can be mixed by grinding, stirring or vibration.

3. A method for green synthesis of CaBDC MOF according to claim 1, characterized in that ； (1) The ball mill is a stainless steel mill or a polytetrafluoroethylene mill, and the grinding balls are stainless steel balls or zirconia balls; (2) The ratio of the total mass of the grinding balls to the mass of the reactants is between 30:1 and 100:1; (3) H2O may or may not be added during the ball milling process; (4) The ball milling speed ranges from 300 to 800 rpm, and the time ranges from 30 to 240 min.

4. The method for green synthesis of CaBDC MOF according to claim 1, characterized in that: (1) The washing solvents are H2O and ethanol, and the washing method is not limited; (2) In particular, if H2O is not added during the ball milling process, H2O must be used during the washing process; (3) Drying can be done under normal conditions or under vacuum; (4) Drying temperature: 60-120°C, drying time: 6-24h.

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