A COF@hydromagnesia composite material and its preparation method and application

Abstract

The present invention provides a COF@hydromagnesia composite material and a preparation method and application thereof. The preparation method of the composite material comprises the following steps: first, a diisocyanate organic matter is used as a modifier to chemically react with hydromagnesia powder to obtain modified hydromagnesia powder particles. Secondly, tris(4-aminophenyl)amine and 2,5-dihydroxyterephthalaldehyde are used as reaction monomers to obtain a covalent organic framework (COF) material. Finally, the modified hydromagnesia powder particles are used as a core and COF is used as a shell to prepare a COF@hydromagnesia composite material. The COF@hydromagnesia composite material synthesized by the present invention has a simple preparation process, high stability, and good selectivity, and can be used for the adsorption treatment of lead ions in water bodies.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials and discloses a COF@hydromagnesite composite material and a preparation method and application thereof. Background Art

[0002] With the rapid development of modern industry, lead metal has been widely developed and applied. As one of the most toxic heavy metal ions, Pb 2+ It is highly water-soluble and difficult to metabolize and degrade. Therefore, it will accumulate in the environment or in animals and plants for a long time, eventually causing serious harm to public health, especially to the brain and nervous system of children. Therefore, it is necessary to remove Pb from the environment, especially water. 2+ It has always been a global problem and is of great significance to the protection of human life and health. At present, the main technologies for removing lead ions are chemical precipitation, electrochemical method, ion exchange method and adsorption method. Among them, the adsorption method is considered to be one of the most effective technologies due to its high treatment efficiency, lower cost, energy saving and environmental protection, and easy operation and implementation. The performance of the adsorption material is the key to the success of the adsorption method.

[0003] Covalent organic framework materials (COFs) are an emerging type of crystalline porous materials. The framework is mainly composed of carbon, oxygen, and nitrogen elements connected by covalent bonds. Its structure is orderly and stable, with large porosity and specific surface area. Compared with traditional porous solid adsorption materials such as activated carbon, resins, and inorganic zeolites, COFs structures can be flexibly designed, the pore size can be adjusted, and active groups or units can be introduced into the extended framework according to different design requirements, so that COFs materials with different functions can be obtained. Therefore, they are considered to be one of the most promising materials for the adsorption and removal of heavy metal ions. However, COFs materials usually exist in the form of powders, which are inconvenient to use in water bodies, which limits their application.

[0004] The main chemical component of hydromagnesite is basic magnesium carbonate. Hydromagnesite powder is generally flaky, low-priced, highly active, and can be effectively combined with COFs materials containing specific groups to form a composite material to complete the adsorption of heavy metal ions in water. Hydromagnesite powder particles can provide effective support and loading for COF, and are conducive to the elution and recovery of the composite material after adsorption.

[0005] In summary, there is an urgent need in the art to develop a COF@hydromagnesite composite material and a preparation method thereof as an adsorption material for lead ions in water to achieve the purpose of purifying water and protecting the environment. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a COF@hydromagnesite composite material and its preparation method and application, so as to prepare a COF@hydromagnesite composite material, which has better adsorption performance for lead ions in water and can be recycled multiple times.

[0007] In order to achieve the above object, the present invention provides a COF@hydromagnesite composite material and a preparation method and application thereof, the method comprising the following steps:

[0008] (1) Dry the hydromagnesite powder, then add a certain amount of N,N-dimethylformamide and stir to obtain suspension A.

[0009] (2) Add a certain amount of diisocyanate compound and catalyst to suspension A, stir at a certain temperature for a period of time, and react to obtain suspension B. After filtering, washing and drying, modified hydromagnesite powder is obtained.

[0010] (3) A certain amount of 2,5-dihydroxyterephthalaldehyde and tri(4-aminophenyl)amine are placed in a high-temperature resistant reaction tube, and mesitylene, anhydrous ethanol and phosphoric acid are added. The tube is sealed and reacted at a certain temperature for a period of time to obtain a mixture C.

[0011] (4) Add the modified hydromagnesite powder into a certain amount of N,N-dimethylformamide and stir to obtain a suspension D.

[0012] (5) The mixture C is taken out and added to the suspension D. The mixture is stirred at a certain temperature for a period of time to obtain a suspension E. The suspension E is filtered, washed and vacuum dried to obtain the COF@hydromagnesia composite material.

[0013] In step (1) of the preparation method, the median particle size of the hydromagnesite powder is 0.7-3.5 μm, preferably 0.8-2.5 μm, and more preferably 1.0-2.0 μm.

[0014] In step (1) of the preparation method, the drying temperature is 125-150°C, preferably 130-140°C, and the drying time is 4-12 h, preferably 6-8 h.

[0015] In step (1) of the preparation method, the concentration of the hydromagnesite powder in the suspension is 1.00 to 50.00 g / L, preferably 5.00 to 40.00 g / L, and more preferably 10.00 to 25.00 g / L.

[0016] In step (2) of the preparation method, the mass ratio of hydromagnesite powder to diisocyanate compound is 1.0:0.1-1.0, preferably 1.0:0.15-0.8, and more preferably 1.0:0.2-0.4.

[0017] In step (2) of the preparation method, the mass ratio of hydromagnesite powder to catalyst is 1.0:0.05-0.30, preferably 1.0:0.08-0.25, and more preferably 1.0:0.1-0.20.

[0018] In step (2) of the preparation method, the stirring temperature is 60 to 150°C, preferably 80 to 110°C; the stirring time is 4 to 12 h, preferably 6 to 10 h, and more preferably 8 to 10 h.

[0019] In step (3) of the preparation method, the molar ratio of 2,5-dihydroxyterephthalaldehyde to tris(4-aminophenyl) is 1.0-5.0:1.0, preferably 2.0-4.0:1.0.

[0020] In step (3) of the preparation method, the reaction temperature is 130-180°C, preferably 140-160°C; the reaction time is 48-120 h, preferably 60-72 h.

[0021] In step (4) of the preparation method, the concentration of the modified hydromagnesite powder in the suspension is 1.00 g / L-50.00 g / L, preferably 5.00-40.00 g / L, and more preferably 20.00-30.00 g / L.

[0022] In step (5) of the preparation method, the stirring temperature is 40 to 100°C, preferably 50 to 80°C; the stirring time is 4 to 12 h, preferably 6 to 8 h.

[0023] The invention provides a COF@hydromagnesite composite material prepared by the preparation method.

[0024] The present invention also provides an application of the COF@hydromagnesia composite material, wherein the COF@hydromagnesia composite material is used as an adsorbent for adsorption treatment of lead ions in water, specifically comprising the following steps: adding the COF@hydromagnesia composite material to a water sample containing lead ions, oscillating and adsorbing for a period of time at a certain temperature, and detecting the lead ion concentration before and after adsorption by an atomic absorption spectrometer. After adsorption, the composite material is regenerated using a phosphoric acid solution as an eluent for a cycle experiment.

[0025] In the present invention, the liquid-to-solid ratio of the water sample to the COF substance in the composite material is 1L:1g; the pH of the water body is 1-7, preferably 2-6, and more preferably 3-4; the adsorption temperature is 10-45°C, preferably 25-30°C; and the adsorption time is 8-24 h, preferably 10-16 h.

[0026] The beneficial effects of the present invention are:

[0027] (1) The present invention synthesizes a core-shell structured COF@hydromagnesite composite material. The novel material has a simple preparation process and high adsorption efficiency, thereby achieving the purpose of rapidly removing lead ions from water samples.

[0028] (2) The present invention uses diisocyanate-modified hydromagnesite powder particles as the core of the adsorption material, and the COF material formed by the reaction of 2,5-dihydroxyterephthalaldehyde and tri(4-aminophenyl)amine as the shell of the adsorption material to construct a new core-shell structure composite material. The material has abundant nitrogen atoms and oxygen atoms, and its lone electron pairs react with Pb 2+ It forms a coordination effect to adsorb lead ions in water.

[0029] The COF@hydromagnesite composite material synthesized by the present invention has the advantages of simple preparation process, stable structure and reusability, and can meet the needs of rapid adsorption and separation of lead ions in water. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a diagram showing the adsorption effect of COF@hydromagnesite composite material on water containing typical heavy metal ions.

[0031] Figure 2 This is a diagram showing the adsorption effect of the COF@hydromagnesite composite material after three cycles of adsorption of typical heavy metal ions in water. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of the present invention. In the embodiments, each raw reagent material can be obtained commercially, and the experimental method without specifying the specific conditions is a conventional method and conventional conditions well known in the art, or according to the conditions recommended by the instrument manufacturer.

[0033] Example 1

[0034] This embodiment provides a COF@hydromagnesite composite material and a preparation method and application thereof, the method comprising the following steps:

[0035] Step 1: Place hydromagnesite powder with a median particle size of 1.5 μm in an oven and dry at 135 °C for 8 h, weigh 2.0000 g of the powder, add 200 mL of N,N-dimethylformamide, and stir to obtain a suspension.

[0036] Step 2: Weigh 0.4000 g of 2,4-toluene diisocyanate and 0.2000 g of stannous octoate and add them to the suspension, and stir at 100 °C for 8 h. After the reaction, the suspension is centrifuged and washed at a centrifugal rate of 12000 r / min for 3 min. Then dry at 110 °C for 8 h to obtain modified hydromagnesite powder.

[0037] Step 3, weigh 2,5-dihydroxyterephthalaldehyde (0.8 mmol) and tri(4-aminophenyl)amine (0.4 mmol) and place them in a heat-resistant reaction tube, add 1,3,5-trimethylbenzene (4 mL), anhydrous ethanol (4 mL) and 2M H3PO4 (0.4 mL), seal and heat at 150 °C for 72 h.

[0038] Step 4: weigh 1.0000 g of modified hydromagnesite powder, add 50 mL of N,N-dimethylformamide, and stir to obtain a suspension.

[0039] Step 5: Add the mixture in step 3 to the suspension in step 4, the reaction temperature is 50 °C, and the reaction time is 6 hours. After the reaction is completed, centrifuge and wash 4 times, the centrifugal speed is 12000 r / min, and the centrifugal time is 3 min. Then vacuum dry at 60 °C for 12 hours to obtain COF@hydromagnesium composite material.

[0040] The COF@hydromagnesia composite material synthesized in this embodiment is used as an adsorbent for the adsorption of lead ions in water, which specifically includes the following steps: the liquid-to-solid ratio of the water sample to the COF substance in the composite material is 1L:1g. The pH of the water body is 4, and the water body contains Pb 2+ 、Ni 2+ 、Co 2+ 、Cd 2+ Cu 2+ The adsorption temperature was 30 °C and the adsorption time was 12 h. The change of lead ion concentration before and after adsorption was detected by atomic absorption spectrometer. The adsorption amount of lead ions in the first adsorption experiment of the composite material was 393 mg / g (based on the mass of COF in the composite material). After adsorption, the composite material was eluted and regenerated with phosphoric acid solution (0.2 mol / L) as the eluent, and three cycles were performed. The adsorption amount of lead ions in the third adsorption experiment was 378 mg / g (based on the mass of COF in the composite material).

[0041] Embodiment 2 to Embodiment 8.

[0042] The preparation methods provided in Examples 2 to 8 have the same steps as those in Example 1, except for the raw materials, proportions and other conditions used in each example; the experimental details involved in the preparation methods provided in Examples 2 to 8, and the test results of the products as adsorbents for treating lead ions in water are specifically shown in the following table.

[0043]

[0044] Therefore, it can be seen from Examples 1 to 8 that the COF@hydromagnesite composite material prepared by the present invention can efficiently and selectively adsorb lead ions in water in the presence of competitive metal ions, thereby completing water treatment.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the implementation process and features of the present invention, rather than to limit the technical methods of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field should understand that the present invention can still be modified or replaced by equivalents, and any modification or partial replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a COF@hydromagnesite composite material, characterized in that: The following steps are involved: (1) Drying the hydromagnesite powder, adding a certain amount of N,N-dimethylformamide, and stirring to obtain a suspension A; (2) Add a certain amount of diisocyanate compound and catalyst to suspension A, stir at a certain temperature for a period of time, react to obtain suspension B, and obtain modified hydromagnesite powder after filtering, washing and drying; (3) placing a certain amount of 2,5-dihydroxyterephthalaldehyde and tris(4-aminophenyl)amine in a high-temperature resistant reaction tube, adding mesitylene, anhydrous ethanol and phosphoric acid, sealing the tube and reacting the tube at a certain temperature for a period of time to obtain a mixture C; (4) Adding the modified hydromagnesite powder into a certain amount of N,N-dimethylformamide and stirring to obtain a suspension D; (5) The mixture C is taken out and added to the suspension D. The mixture is stirred at a certain temperature for a period of time to obtain a suspension E. The suspension E is filtered, washed and vacuum dried to obtain the COF@hydromagnesia composite material.

2. The method for preparing the COF@hydromagnesite composite material according to claim 1, characterized in that: In step (1), the median particle size of the hydromagnesite powder is 0.7-3.5 μm, the drying temperature is 125-150°C, and the drying time is 4-12 h; the concentration of the hydromagnesite powder in the suspension is 1.00 g / L-50.00 g / L.

3. The method for preparing the COF@hydromagnesite composite material according to claim 1, characterized in that: In step (2), the diisocyanate compound is any one or more of 2,4-toluene diisocyanate, 2,5-toluene diisocyanate, 3,5-toluene diisocyanate, 2,6-toluene diisocyanate, m-phenylene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate, and the mass ratio of hydromagnesia powder to diisocyanate compound is 1.0:0.1-1.0; the catalyst is any one of stannous octoate or dibutyltin dilaurate, and the mass ratio of hydromagnesia powder to catalyst is 1.0:0.05-0.30; the stirring temperature is 60-150°C, and the stirring time is 4-12 h.

4. The method for preparing the COF@hydromagnesite composite material according to claim 1, characterized in that: In step (3), the molar ratio of 2,5-dihydroxyterephthalaldehyde to tris(4-aminophenyl) is 1.0-5.0:1.0; the reaction temperature is 130-180° C.; and the reaction time is 48-120 h.

5. The method for preparing the COF@hydromagnesite composite material according to claim 1, characterized in that: In step (4), the concentration of the modified hydromagnesite powder in the suspension is 1.00 g / L-50.00 g / L.

6. The method for preparing the COF@hydromagnesite composite material according to claim 1, characterized in that: In step (5), the stirring temperature is 40-100°C and the stirring time is 4-12 h.

7. The COF@hydromagnesia composite material obtained by the preparation method according to any one of claims 1 to 6.

8. The use of the COF@hydromagnesia composite material as an adsorbent as claimed in claim 7, characterized in that: Used for the adsorption treatment of lead ions in water.

9. The use of the COF@hydromagnesia composite material as an adsorbent as claimed in claim 8, characterized in that: The COF@hydromagnesia composite material is used as an adsorbent for the adsorption treatment of lead ions in water, which specifically includes the following steps: adding the COF@hydromagnesia composite material to a water sample containing lead ions and adsorbing it for a period of time at a certain temperature; after adsorption, the composite material is regenerated using a phosphoric acid solution as an eluent for a cyclic experiment.

10. The use of the COF@hydromagnesia composite material as an adsorbent as claimed in claim 9, characterized in that: The water pH is 1~7, the temperature is 10~35 ℃, and the adsorption time is 8~24 h.

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