Preparation method and application of a magnetic porous carbon adsorbent of a confined hydroxyl functionalized ionic liquid

Abstract

The application relates to a preparation method and application of a magnetic porous carbon adsorbent of a confined hydroxyl functionalized ionic liquid. ZIF-67 is used as a precursor, the specific surface area of the ZIF-67 is expanded through carbonization and etching, and a hydroxyl functionalized ionic liquid is confined in the pore diameter of the ZIF-67 to improve the adsorption performance. In the carbonization process of the ZIF-67 precursor, cobalt nanoparticles with magnetism are generated, which makes the separation of the adsorbent more convenient. After etching and confinement of the ionic liquid, the adsorption performance of the material on triazine pesticides is obviously improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of MOF derived magnetic porous carbon combined with ionic liquid, in particular to a preparation and application of a magnetic porous carbon adsorbent of confined hydroxyl functionalized ionic liquid, and especially to an application of a ZIF-67 derived porous carbon confined hydroxyl functionalized ionic liquid adsorbent in extraction of triazine pesticides. BACKGROUND

[0002] Triazine compounds are widely used in the prevention of insects or weeds in various crops. Although triazine pesticides are a kind of low-toxicity pesticides, their microbial mineralization process is slow, thus causing environmental pollution. Triazine pesticides can enter the body through respiratory tract, skin contact, etc., causing symptoms such as abdominal pain, diarrhea, vomiting in mammals and humans, and are potential carcinogens, so it has practical significance to remove triazine pesticides from environmental wastewater.

[0003] Ionic liquid has the advantages of good chemical stability and good solubility, and is a very promising extraction solvent. However, ionic liquid is not easy to recover, so ionic liquid is combined with magnetic porous carbon material. The confinement of ionic liquid in magnetic porous carbon can solve the problem of ionic liquid recovery, and the synergistic effect of ionic liquid and carbon material can improve the extraction performance of the composite material.

[0004] With the in-depth study of extractants, some conventional extractants have been unable to meet the requirements, so it is necessary to design magnetic carbon materials with confined ionic liquids with different functional groups according to different target substances. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a new type of magnetic porous carbon adsorbent of confined hydroxyl functionalized ionic liquid, which has good extraction capacity for triazine pesticides. Since the adsorbent has magnetism, the separation of the adsorbent and the target substance is also relatively simple.

[0006] The technical scheme adopted by the present application is: a preparation method of a new type of magnetic porous carbon adsorbent of confined hydroxyl functionalized ionic liquid, comprising the following steps:

[0007] 1) Dissolve cobalt nitrate hexahydrate in methanol to form solution A; dissolve 2-methylimidazole in methanol to form solution B; slowly inject solution A into solution B, continuously stir at room temperature for 24 h, centrifuge to collect the precipitate, wash with methanol, and dry to obtain a precursor ZIF-67;

[0008] 2) Put the precursor ZIF-67 into a tube furnace and carbonize under N2 atmosphere to obtain a Co-nitrogen-doped carbon material Co-NC;

[0009] 3) The carbon material Co-NC was placed in an HCl solution and stirred for 24 h to etch away some of the cobalt nanoparticles; the etched Co-NC was washed with water until neutral and then dried in an oven to obtain the etched carbon material e-Co-NC.

[0010] 4) An appropriate amount of carbon material e-Co-NC was dispersed in an aqueous solution of hydroxyl-functionalized ionic liquid [HOmim]NTf2, stirred at room temperature for 5 hours, washed with water to remove the ionic liquid from the surface of e-Co-NC, and vacuum dried to obtain a novel magnetic porous carbon adsorbent IL with confined hydroxyl-functionalized ionic liquid. OH @e-Co-NC.

[0011] Preferably, in step 1), the mass ratio of cobalt nitrate hexahydrate to 2-methylimidazole is 1:1-1.5.

[0012] Preferably, in step 2), the carbonization is performed at 600 °C for 1 h, with a heating rate of 1 °C·min. -1 .

[0013] Preferably, in step 3), the concentration of the HCl solution is 3 mol·L⁻¹. -1 .

[0014] Preferably, in step 4), the mass ratio is [HOmim]NTf2: e-Co-NC = 1: 10.

[0015] The application of the novel magnetic porous carbon adsorbent with confined hydroxyl functionalized ionic liquid provided by this invention in the extraction of triazine pesticides.

[0016] Preferably, the method is as follows: a novel magnetic porous carbon adsorbent IL, consisting of a confined hydroxyl-functionalized ionic liquid, is added to an aqueous solution containing triazine pesticides. OH @e-Co-NC uses a constant temperature shaking chamber for extraction.

[0017] Preferably, the concentration of triazine pesticides is 1-100 mg·L⁻¹. -1 .

[0018] Preferably, based on the solid-liquid ratio, IL OH @e-Co-NC : Triazine pesticide solution = 20 mg : 5 mL.

[0019] Preferably, the triazine pesticides include atrazine, terbutaline, and chlorpyrifos.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses ZIF-67 as a precursor, which is first carbonized and then etched to increase its specific surface area, and hydroxyl-functionalized ionic liquids are confined within its pores to improve adsorption performance. Furthermore, the carbonization process of the ZIF-67 precursor generates magnetic cobalt nanoparticles, which simplifies adsorbent separation.

[0022] 2. In this invention, a composite adsorbent IL is prepared using ZIF-67 and the hydroxyl-type ionic liquid [HOmin]NTf2. OH @e-Co-NC was used for the extraction of triazine pesticides. This adsorbent exhibits high extraction capacity for triazine pesticides, and the combination of ionic liquid and ZIF-67-derived magnetic porous carbon significantly improves the material's extraction performance. Furthermore, due to the magnetic nature of the adsorbent, separation from the target analyte is relatively simple. The adsorption performance of this material for triazine pesticides was significantly enhanced after etching and confinement with ionic liquid. Attached Figure Description

[0023] Figure 1 It is Co-NC, e-Co-NC and IL OH XRD pattern of @e-Co-NC.

[0024] Figure 2 It is Co-NC, e-Co-NC and IL OH N2 adsorption / desorption isotherms of @e-Co-NC.

[0025] Figure 3 It is e-Co-NC and IL OH @e-Co-NC adsorption capacity comparison chart. Detailed Implementation

[0026] Example 1: A novel magnetic porous carbon adsorbent (IL) based on confined hydroxyl-functionalized ionic liquids. OH @e-Co-NC)

[0027] The preparation method is as follows:

[0028] 1. Preparation of hydroxyl-functionalized ionic liquid [HOmin]NTf2

[0029] 5 mmol / L of 1-hydroxymethyl-3-methylimidazolium chloride ([HOmin][Cl]) and 5.5 mmol / L of lithium bis(trifluoromethanesulfonylimide) (NTf2Li) were added to 5 mL of water and stirred at room temperature for 5 h. The lower ionic liquid phase was collected by centrifugation, washed three times with 2 mL of water, and then dried overnight in a vacuum oven at 60 °C to obtain the ionic liquid [HOmin]NTf2. The structural formula is as follows:

[0030]

[0031] [HOmin]NTf2

[0032] 2. Preparation of precursor ZIF-67

[0033] 5.6 g of cobalt nitrate hexahydrate was dissolved in 50 mL of methanol to form solution A. 5.82 g of 2-methylimidazole was dissolved in 50 mL of methanol to form solution B. Solution A was then slowly added to solution B, forming a deep purple solution. The mixture was stirred continuously at room temperature for 24 h to produce a purple solid. The purple solid was collected by centrifugation and washed with methanol until the solution became clear. Finally, the solution was dried in an oven at 60 °C for 12 h to obtain the precursor ZIF-67.

[0034] 3. Preparation of Co-NC

[0035] The dried precursor ZIF-67 was placed in a tube furnace and carbonized at 600℃ for 1 h under a N2 atmosphere (heating rate of 1℃ / min). -1 ), thus obtaining Co-nitrogen-doped carbon material Co-NC.

[0036] 4. Preparation of e-Co-NC

[0037] Co-nitrogen-doped carbon material Co-NC was added to 3 mol·L⁻¹ -1 In a hydrochloric acid solution, the mixture was stirred for 24 h to etch away some of the cobalt nanoparticles. The etched Co-NC was then washed with water until neutral and placed in an oven at 60°C for 12 h to obtain the etched carbon material e-Co-NC.

[0038] 5. Magnetic porous carbon adsorbent IL OH Preparation of @e-Co-NC

[0039] Take [HOmin]NTf2 and e-Co-NC at a mass ratio of 1:10.

[0040] [HOmin]NTf2 and e-Co-NC were added to deionized water and stirred at room temperature for 5 h. Then, the mixture was washed three times with deionized water to remove the ionic liquid on the surface of e-Co-NC. After washing, the mixture was vacuum dried at 60 °C for 12 h to obtain IL. OH @e-Co-NC.

[0041] Using XRD ( Figure 1 ) and BET Figure 2 The material was characterized, demonstrating that IL OH The successful preparation of @e-Co-NC materials and their large specific surface area.

[0042] Example 2 Novel Magnetic Porous Carbon Adsorbent IL OH Application of @e-Co-NC in the extraction of triazine pesticides

[0043] (I) Effects of different adsorbents on the extraction of triazine pesticides:

[0044] In a series of 5 mL samples with initial concentrations ranging from 1 to 100 mg·L⁻¹ -1 Add 20 mg IL to the aqueous solution of triazine pesticides (atrazine, terbutaline, or glyphosate). OH @e-Co-NC adsorbent and 20 mg e-Co-NC adsorbent were shaken at 250 rpm for 35 min in a constant temperature shaker. The adsorbents were then separated using a magnet. The supernatant was used to determine the concentration of triazine pesticides by HPLC, and the adsorption capacity was calculated. The maximum adsorption capacity results are shown in Table 1 and... Figure 3 .

[0045] Table 1

[0046]

[0047] From Table 1 and Figure 3 It is evident that the introduction of ionic liquids significantly improves the adsorption performance of the material for the three pesticides. The IL provided by this invention... OH @e-Co-NC showed good adsorption effects on all three pesticides.

Claims

1. The application of a magnetic porous carbon adsorbent with confined hydroxyl-functionalized ionic liquid in the extraction of triazine pesticides, characterized in that, The preparation method of the magnetic porous carbon adsorbent with confined hydroxyl functionalized ionic liquid includes the following steps: 1) Dissolve cobalt nitrate hexahydrate in methanol to form solution A; dissolve 2-methylimidazole in methanol to form solution B; slowly inject solution A into solution B, stir continuously at room temperature for 24 h, collect the precipitate by centrifugation, wash with methanol, and dry to obtain the precursor ZIF-67. 2) The precursor ZIF-67 was placed in a tube furnace and carbonized at 600 °C for 1 h under a N2 atmosphere, with a heating rate of 1 °C / min. -1 Co-nitrogen-doped carbon material Co-NC was obtained; 3) The carbon material Co-NC was placed in an HCl solution and stirred for 24 h to etch away some of the cobalt nanoparticles; the etched Co-NC was washed with water until neutral and then dried in an oven to obtain the etched carbon material e-Co-NC. 4) Disperse an appropriate amount of carbon material e-Co-NC in an aqueous solution of hydroxyl-functionalized ionic liquid [HOmim]NTf2 at a mass ratio of [HOmim]NTf2:e-Co-NC = 1:

10. Stir at room temperature for 5 hours, wash with water, and vacuum dry to obtain magnetic porous carbon adsorbent IL with confined hydroxyl-functionalized ionic liquid. OH @e-Co-NC.

2. The application according to claim 1, characterized in that, In step 1), the mass ratio of cobalt nitrate hexahydrate to 2-methylimidazole is 1:1-1.

5.

3. The application according to claim 1, characterized in that, In step 3), the concentration of the HCl solution is 3 mol·L⁻¹. -1 .

4. The application according to claim 1, characterized in that, The method is as follows: IL, a magnetic porous carbon adsorbent containing a confined hydroxyl-functionalized ionic liquid, is added to an aqueous solution containing triazine pesticides. OH @e-Co-NC uses a constant temperature shaking chamber for extraction.

5. The application according to claim 4, characterized in that, The concentration of triazine pesticides is 1-100 mg·L⁻¹ -1 .

6. The application according to claim 5, characterized in that, According to the solid-liquid ratio, IL OH @e-Co-NC : Triazine pesticide solution = 20 mg : 5 mL.

7. The application according to claim 4, characterized in that, The triazine pesticides mentioned include atrazine, terbutaline, and chlorpyrifos.

Images