Cryptand-modified magnetic iron oxide nanoparticles, preparation method thereof and use thereof

Abstract

The invention discloses a method for preparing cryptand-modified magnetic iron oxide nanoparticles, comprising the following steps: S1, preparing magnetic iron oxide nanoparticles; S2, preparing a cryptand compound with an R group, wherein the cryptand compound has a structure shown in Formula I; S3, dissolving the cryptand compound in tetrahydrofuran, adding magnetic iron oxide nanoparticles, copper iodide, N-ethyldiisopropylamine and sodium ascorbate, heating reaction under nitrogen protection, collecting the product after the reaction, washing and drying, and obtaining cryptand-modified iron oxide nanoparticles. The invention synthesizes cryptand-modified magnetic iron oxide nanoparticles by chemical reaction the prepared magnetic iron oxide nanoparticles and the cryptand compound, and has the beneficial effect of a simple synthesis method; the invention also discloses a cryptand-modified magnetic iron oxide nanoparticle, which has excellent adsorption and removal effect on Pb and Cd ions in rice soaking liquid.

Description

Technical Field

[0001] The present invention relates to the field of adsorption materials, and more specifically, to cryptand-modified magnetic iron oxide nanoparticles and a preparation method and application thereof. Background Art

[0002] The soaking process of rice can reduce the content of lead and cadmium in it, but the post-treatment of the rice soaking liquid containing a large amount of lead and cadmium becomes a new problem.

[0003] At present, there are many studies on the treatment of lead and cadmium-containing wastewater at home and abroad, and a variety of treatment technologies have been proposed, such as electrolysis, chemical precipitation, adsorption, ion exchange, reverse osmosis, electrodialysis, etc. Among them, the adsorption method is the simplest and easiest to operate, but it has disadvantages such as small processing capacity, poor selectivity, low reuse rate, and easy to cause secondary pollution.

[0004] Iron oxide nanomaterials have shown great application prospects in the field of environmental remediation due to their small size, large specific surface area, and strong surface modifiability. Iron oxide nanomaterials, especially magnetic iron oxide nanoparticles, have been widely studied as nanoadsorbents for the adsorption of heavy metals in wastewater. Unlike traditional adsorbents, magnetic iron oxide nanoparticles can be modified on the surface with specific functional groups and are magnetic, so they can be easily separated magnetically using an external magnetic field. Compared with centrifugation or filtration, magnetic separation has the characteristics of fast separation speed, good selectivity, and high separation efficiency. However, for wastewater, especially wastewater soaked in rice containing lead and cadmium, there is an excellent effect of adsorbing and separating lead and cadmium ions.

[0005] French scientist Jean-Marie Lehn and others found that cryptands have cavities that can form bonds with metal cations through ion-dipole interactions, and can selectively bind to metal cations according to the size of the cavity. Therefore, through the design of the cryptand structure, high selectivity for lead and cadmium ions can be obtained, and they can be used to efficiently adsorb lead and cadmium ions in water. However, the common organic solvents used to dissolve the cryptands and then adsorb the metal ions in the water for extraction and separation have the problems of low adsorption and separation efficiency and slow separation speed. Therefore, it is worth pondering how to combine iron oxide nanomaterials and cryptands to prepare a cryptand-modified magnetic iron oxide nanoparticle to obtain the beneficial effect of high adsorption and separation efficiency for lead and cadmium ions in wastewater. Summary of the invention

[0006] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0007] In order to achieve these purposes and other advantages according to the present invention, a method for preparing cryptand-modified magnetic iron oxide nanoparticles is provided, comprising the following steps:

[0008] S1. preparing magnetic iron oxide nanoparticles;

[0009] S2. Prepare a cryptand compound with an R group, wherein the cryptand compound has a structure shown in Formula I:

[0010]

[0011] Wherein, X is selected from any one of O and N-CH3;

[0012] R is selected from any one of -NH2, -COOH, -N3, -OH and -C≡CH;

[0013] S3. After dissolving the cryptand compound in tetrahydrofuran, add magnetic iron oxide nanoparticles, copper iodide, N-ethyldiisopropylamine and sodium ascorbate, and heat the reaction under nitrogen protection. After the reaction is completed, collect the product, wash and dry it to obtain cryptand-modified iron oxide nanoparticles.

[0014] Preferably, the preparation of magnetic iron oxide nanoparticles in step S1 comprises the following steps:

[0015] Disperse ferroferric oxide in an ethanol aqueous solution, add a silane coupling agent, stir and react at 60-70° C. for 12-15 hours, filter, wash and dry to obtain magnetic iron oxide nanoparticles, wherein the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1-2.

[0016] Preferably, the preparation of the cryptand compound in step S2 comprises the following steps:

[0017] Step 1, 2,2-dimethyl-1,3-dioxolane-4-methanol, sodium hydride and N,N-dimethylformamide are stirred at 0°C for 2-3h, a halide is added and the temperature is raised to room temperature for stirring and reaction. After the reaction is completed, a crude product a is obtained by extraction, drying and concentration. A methanol solution of hydrochloric acid is added to the crude product a, and the mixture is stirred and reacted at room temperature. After the reaction is completed, a sodium hydroxide solution is added and the mixture is concentrated to obtain a crude product b. The crude product b is separated by column chromatography to obtain an intermediate A;

[0018] Step 2: Stir intermediate A, sodium hydride and N,N-dimethylformamide at 0°C for 2-3h, add 2-(2-bromoethoxy)tetrahydropyran, and heat to room temperature for stirring and reacting. After the reaction is completed, extract, dry and concentrate to obtain a crude product c. Stir the crude product c, pyridine p-toluenesulfonate and methanol at 60-80°C for reaction. After the reaction is completed, dry and separate by column chromatography to obtain intermediate B.

[0019] Step 3, dissolving intermediate B, p-toluenesulfonyl chloride, 4-dimethylaminopyridine and triethanolamine in dichloromethane, and stirring at room temperature for reaction. After the reaction is completed, extracting, drying and separating by column chromatography to obtain intermediate C;

[0020] Step 4: Mix the intermediate C, azacrown ether, sodium carbonate and acetonitrile, and reflux with stirring for reaction. After the reaction is completed, filter and concentrate to obtain a crude product d. The crude product d is separated by column chromatography to obtain a cryptand compound.

[0021] Preferably, the silane coupling agent is selected from any one or more of (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 4-(trimethoxysilyl)butyric acid, (3-mercaptopropyl)trimethoxysilane, 3-aminopropyltrimethoxysilane, cyclooctyldimethoxysilane, 3-(3-aminophenoxy)propyltrimethoxysilane, isocyanatopropyltriethoxysilane, 3-(azidopropyl)triethoxysilane, 3-triethoxysilyl-1-propylamine and (3-oxiranylmethoxypropyl)trimethoxysilane.

[0022] Preferably, the particle size of the ferrosoferric oxide is 100-150 nm.

[0023] Preferably, the halide in step 1 is selected from any one of bromoacetylene, bromoacetic acid and bromomethanol.

[0024] Preferably, the azacrown ether in step 4 is selected from any one of 4,13-diaza-18-crown-6-ether and 1,4,10,13-tetramethyl-1,4,7,10,13,6-hexaazacyclooctadecane.

[0025] Provided are cryptand-modified magnetic iron oxide nanoparticles prepared based on the preparation method.

[0026] Provided is an application of the cryptand-modified magnetic iron oxide nanoparticles in the preparation of wastewater treatment products.

[0027] Provided is an application of the cryptand-modified magnetic iron oxide nanoparticles in the preparation of products for treating heavy metal lead and cadmium ions.

[0028] The present invention has at least the following beneficial effects:

[0029] First, the present invention synthesizes cryptand-modified magnetic iron oxide nanoparticles by chemical reaction of the prepared magnetic iron oxide nanoparticles and cryptand compounds, which has the beneficial effect of a simple synthesis method.

[0030] Second, the cryptand-modified magnetic iron oxide nanoparticles prepared by the present invention have excellent adsorption and removal effects on Pb and Cd ions in rice soaking liquid, and the removal rate of Pb and Cd ions is as high as 93%, which makes the cryptand-modified magnetic iron oxide nanoparticles have good application in removing Pb and Cd ions in rice soaking liquid and even in wastewater.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a transmission electron microscope image of the cryptand-modified nano iron oxide particle (single) of the present invention;

[0033] Figure 2 It is a transmission electron microscope image of the cryptand-modified nano iron oxide particles (group) of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0035] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0036] <Example 1>

[0037] Preparation of magnetic iron oxide nanoparticles

[0038] 1 g of ferroferric oxide with a particle size of 100 nm was dispersed in 100 mL of ethanol-water solution, 1 mL of 3-(azidopropyl)triethoxysilane was added, and the mixture was heated to 60° C. and stirred for 12 h. Then, the mixture was filtered, washed three times with water, and dried to obtain 0.7 g of magnetic iron oxide nanoparticles with surface azide functionalization, wherein the volume ratio of ethanol to water in the ethanol-water solution was 1:1.

[0039] <Example 2>

[0040] Preparation of cryptand compounds

[0041] Step 1: 40 mmol of 2,2-dimethyl-1,3-dioxolane-4-methanol, 80 mmol of sodium hydride and 80 mL of N,N-dimethylformamide were stirred at 0°C for 2 h, and then 48 mmol of propargyl bromide was added, and the mixture was heated to room temperature and stirred for 24 h. After the reaction, a mixture was obtained. The mixture was poured into 10 mL of 2 mol / L NaOH solution, and extracted with ether to obtain an organic layer. The organic layer was dried over anhydrous sodium sulfate and concentrated by rotary evaporation to obtain a crude product a. 15 mL of 10% wt hydrochloric acid in methanol solution was added to the crude product a, and the mixture was stirred at room temperature for reaction. After the reaction, 5 mL of 2 mol / L sodium hydroxide solution was added, and the mixture was concentrated by rotary evaporation to obtain a crude product b. The crude product b was separated by silica gel column chromatography with a volume ratio of petroleum ether to ethyl acetate of 2:1 to obtain intermediate A, i.e., 1-propynyl glycerol ether:

[0042]

[0043] The yield was 73%. The characterization data of the intermediate A obtained by nuclear magnetic resonance hydrogen spectrum were: 1 H NMR (400MHz, Chloroform-d) δ4.19 (d, J = 2.4 Hz, 2H), 3.90-3.80 (m, 1H), 3.71 (dd, J = 11.5, 3.9 Hz, 1H), 3.67-3.54 (m, 3H), 2.46 (t, J = 2.4 Hz, 1H); the characterization data of the carbon spectrum were obtained as follows: 13 C NMR (101MHz, Chloroform-d) δ79.4,75.1,71.2,70.8,63.8,58.6;

[0044] Step 2: After 23 mmol of intermediate A, 92 mmol of sodium hydride and 80 mL of N, N-dimethylformamide were stirred at 0 ° C for 2 h, 69 mmol of 2-(2-bromoethoxy)tetrahydropyran was added, and the temperature was raised to room temperature and stirred for reaction for 24 h. After the reaction was completed, 10 mL of water was poured into it, and the organic layer was extracted with ether. The organic layer was dried over anhydrous sodium sulfate and concentrated by rotary evaporation to obtain a crude product c. The obtained crude product c, 0.23 mmol of pyridine p-toluenesulfonate and 60 mL of methanol were stirred and reacted at 60 ° C for 24 h. After the reaction was completed, after rotary evaporation and drying, the intermediate B was separated by silica gel column chromatography with a volume ratio of petroleum ether to ethyl acetate of 2:1 to obtain 1-propynyl-2,3-diethanol glycerol ether:

[0045]

[0046] The yield was 67%. The characterization data of the intermediate B obtained by nuclear magnetic resonance hydrogen spectrum were: 1H NMR (400MHz, Chloroform-d) δ4.16 (d, J = 2.4 Hz, 2H), 3.75-3.66 (m, 7H), 3.62-3.55 (m, 6H), 3.14 (br s, 2H), 2.44 (t, J = 2.4 Hz, 1H); the characterization data of the carbon spectrum obtained are: 13 C NMR (101MHz, Chloroform-d) δ79.3,78.0,74.9,72.8,72.0,71.1,69.6,61.7,61.4,58.5;

[0047] Step 3: Dissolve 1 mmol of intermediate B, 33 mmol of p-toluenesulfonyl chloride, 1.2 mmol of 4-dimethylaminopyridine and 66 mmol of triethanolamine in 60 mL of dichloromethane, and stir at room temperature for 24 hours. After the reaction is completed, dry by rotary evaporation, and separate by silica gel column chromatography with a volume ratio of petroleum ether to ethyl acetate of 2:1 to obtain intermediate C, i.e., 1-propynyl-2,3-di-p-toluenesulfonyloxyethyl glycerol ether:

[0048]

[0049] The yield was 79%. The characterization data of the intermediate C obtained by nuclear magnetic resonance hydrogen spectrum were: 1 H NMR (400MHz, Chloroform-d) δ7.81-7.72 (m, 4H), 7.41-7.32 (m, 4H), 4.15-4.07 (m, 6H), 3.83-3.76 (m, 2H), 3.67-3.60 (m, 2H), 3.57-3.39 (m, 5H), 2.47-2.38 (m, 7H); the characterization data of the carbon spectrum were obtained as follows: 13 CNMR(101MHz,Chloroform-d)δ144.9,144.8,133.2,133.1,129.9,129.8,12 7.9,127.8,79.5,78.5,74.7,71.3,69.6,69.5,69.2,68.9,68.1,58.6,21.6;

[0050] Step 4: 6.8 mmol of intermediate C, 6.8 mmol of 4,13-diaza-18-crown-6-ether, 34.2 mmol of sodium carbonate and 120 mL of acetonitrile were mixed, and the mixture was stirred under reflux at 83 ° C for 36 h. After the reaction was completed, the crude product d was obtained by filtration and rotary evaporation. The crude product d was separated by silica gel column chromatography with a volume ratio of dichloromethane to methanol of 3:1 to obtain an alkynyl-functionalized cryptand, i.e., a cryptand compound (Formula D):

[0051]

[0052] The yield is 55%, and the characterization data of the hydrogen spectrum of the cryptand compound obtained by nuclear magnetic resonance is: 1 H NMR (400MHz, Chloroform-d) δ7.83 (d, J = 7.9 Hz, 2H), 7.09 (d, J = 7.9 Hz, 2H), 4.16 (d, J = 2.5 Hz, 2H), 3.77-3.44 (m, 25H), 2.94-2.50 (m, 12H), 2.48 (t, J = 2.4 Hz, 1H), 2.30 (s, 3H); the characterization data of the carbon spectrum were obtained as follows: 13 C NMR(101MHz,Chloroform-d)δ144.9,138.3,128.3,126.4,79.5,76.6,75.1,70.1,68.9,68.8,68. 8,68.7,68.7,68.6,68.1,67.9,67.7,67.6,66.3,58.7,53.9,53.8,53.3,53.3,53.2,53.1,21.4.

[0053] <Example 3>

[0054] Preparation of Cryptand-modified Magnetic Iron Oxide Nanoparticles

[0055] After 0.1 g of cryptand compound was dissolved in 10 mL of tetrahydrofuran, 0.7 g of magnetic iron oxide nanoparticles, 1 g of copper iodide, 1.5 g of N-ethyldiisopropylamine and 2 g of sodium ascorbate were added, and the mixture was heated to 80 °C under nitrogen protection for 18 h. After the reaction, the product was collected by magnet adsorption, washed with water, and freeze-dried to obtain cryptand-modified iron oxide nanoparticles. The cryptand-modified iron oxide nanoparticles were characterized by transmission electron microscopy. The results are shown in the attached figure. Figure 1 , 2 shown.

[0056] <Adsorption performance test>

[0057] Pb and Cd ion concentration test in rice soaking solution:

[0058] Three portions of rice soaking liquid of 100 mL in daily life were randomly selected, namely rice soaking liquid 1, rice soaking liquid 2, and rice soaking liquid 3, and the initial concentrations of Pb and Cd ions in the three portions of rice soaking liquid were determined by inductively coupled plasma mass spectrometry (ICP-MS). The test results are shown in Table 1 below:

[0059] Table 1 Initial concentrations of Pb and Cd ions in rice soaking solution

[0060] Group Pb ion (ng / mL) Cd ion (ng / mL) Rice soaking liquid 1 1.76 68.60 Rice soaking liquid 2 53.30 212.00 Rice soaking liquid 3 1.43 232.20

[0061] Adsorption treatment of Pb and Cd ions in rice soaking solution:

[0062] Respectively filtering the rice soaking liquid 1, the rice soaking liquid 2, and the rice soaking liquid 3 to remove insoluble impurities therein to obtain the treated rice soaking liquid 1, the rice soaking liquid 2, and the rice soaking liquid 3, and dividing them into three equal parts respectively;

[0063] 1g of cryptand-modified magnetic nanoparticles, nano-iron oxide particles and cryptand compounds (alkynyl-functionalized cryptands) prepared in Examples 1 to 3 were dispersed in 200mL of treated rice soaking solution 1, rice soaking solution 2 and rice soaking solution 3, respectively, stirred at room temperature for 24h, and the cryptand-modified magnetic nanoparticles and nano-iron oxide particles in the solution were recovered by magnet, and the cryptand compounds (alkynyl-functionalized cryptands) were removed by extraction with dichloromethane. The final concentrations of Pb and Cd ions in rice soaking solution 1, rice soaking solution 2 and rice soaking solution 3 after adsorption of the cryptand-modified magnetic nanoparticles, nano-iron oxide particles and cryptand compounds (alkynyl-functionalized cryptands) were determined by ICP-MS, and the metal removal rates of Pb and Cd ions were calculated according to the data in Table 1, and the formula is: The calculation results are shown in Table 2, Table 3 and Table 4 respectively:

[0064] Table 2 Removal efficiency of Pb and Cd ions in three rice soaking solutions by cryptand-modified magnetic nanoparticles

[0065] project Rice soaking liquid 1 Rice soaking liquid 2 Rice soaking liquid 3 Pb ion removal rate (%) 67 93 72 Cd ion removal rate (%) 79 87 92

[0066] Table 3 Removal rate of Pb and Cd ions in three rice soaking solutions by nano iron oxide particles

[0067] project Rice soaking liquid 1 Rice soaking liquid 2 Rice soaking liquid 3 Pb ion removal rate (%) 5 12 9 Cd ion removal rate (%) 13 15 18

[0068] Table 4 Removal efficiency of Pb and Cd ions in three rice soaking solutions by cryptand compounds

[0069] project Rice soaking liquid 1 Rice soaking liquid 2 Rice soaking liquid 3 Pb ion removal rate (%) 14 23 17 Cd ion removal rate (%) 34 46 41

[0070] According to the data in Tables 2 to 4, it was found that the recovery (removal rate) of Pb and Cd ions in rice soaking solution by cryptand-modified magnetic nanoparticles was significantly higher than that by nano-iron oxide particles and cryptand-type compounds, reaching up to 93%. This indicates that the cryptand-modified magnetic nanoparticles of the present application are excellent in removing trace amounts of Pb and Cd ions in rice soaking solution, and have high application value for removing Pb and Cd ions in wastewater.

[0071] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing cryptand-modified magnetic iron oxide nanoparticles, characterized in that: The following steps are involved: S1. preparing magnetic iron oxide nanoparticles; S2. Prepare a cryptand compound with an R group, wherein the cryptand compound has a structure shown in Formula I: Formula I Wherein, X is selected from any one of O and N-CH3; R is selected from any one of -NH2, -COOH, -N3, -OH and -C≡CH; S3. After dissolving the cryptand compound in tetrahydrofuran, add magnetic iron oxide nanoparticles, copper iodide, N-ethyldiisopropylamine and sodium ascorbate, and heat the reaction under nitrogen protection. After the reaction is completed, collect the product, wash and dry it to obtain cryptand-modified iron oxide nanoparticles.

2. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 1, wherein: The preparation of magnetic iron oxide nanoparticles in step S1 comprises the following steps: Disperse ferroferric oxide in an ethanol aqueous solution, add a silane coupling agent, stir and react at 60-70° C. for 12-15 h, filter, wash and dry to obtain magnetic iron oxide nanoparticles, wherein the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1-2.

3. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 1, wherein: The preparation of the cryptand compound in step S2 comprises the following steps: Step 1, 2,2-dimethyl-1,3-dioxolane-4-methanol, sodium hydride and N,N-dimethylformamide are stirred at 0°C for 2-3 h, a halide is added and the temperature is raised to room temperature for stirring and reaction. After the reaction is completed, a crude product a is obtained by extraction, drying and concentration. A methanol solution of hydrochloric acid is added to the crude product a, and the mixture is stirred and reacted at room temperature. After the reaction is completed, a sodium hydroxide solution is added and the mixture is concentrated to obtain a crude product b. The crude product b is separated by column chromatography to obtain an intermediate A; Step 2: Stir intermediate A, sodium hydride and N,N-dimethylformamide at 0°C for 2-3 h, add 2-(2-bromoethoxy)tetrahydropyran, and heat to room temperature for stirring and reacting. After the reaction is completed, extract, dry and concentrate to obtain a crude product c. Stir the crude product c, pyridine p-toluenesulfonate and methanol at 60-80°C for reaction. After the reaction is completed, dry and separate by column chromatography to obtain intermediate B. Step 3, dissolving intermediate B, p-toluenesulfonyl chloride, 4-dimethylaminopyridine and triethanolamine in dichloromethane, and stirring at room temperature for reaction. After the reaction is completed, extracting, drying and separating by column chromatography to obtain intermediate C; Step 4: Mix the intermediate C, azacrown ether, sodium carbonate and acetonitrile, and reflux with stirring for reaction. After the reaction is completed, filter and concentrate to obtain a crude product d. The crude product d is separated by column chromatography to obtain a cryptand compound.

4. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 2, wherein: The silane coupling agent is selected from any one or more of (3-bromopropyl)trimethoxysilane, (3-iodopropyl)trimethoxysilane, 4-(trimethoxysilyl)butyric acid, (3-mercaptopropyl)trimethoxysilane, 3-aminopropyltrimethoxysilane, cyclooctyldimethoxysilane, 3-(3-aminophenoxy)propyltrimethoxysilane, isocyanatepropyltriethoxysilane, 3-(azidopropyl)triethoxysilane, 3-triethoxysilyl-1-propylamine and (3-oxiranylmethoxypropyl)trimethoxysilane.

5. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 2, wherein: The particle size of the ferrosoferric oxide is 100-150 nm.

6. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 3, characterized in that: The halide in step 1 is selected from any one of bromoacetylene, bromoacetic acid and bromomethanol.

7. The method for preparing cryptand-modified magnetic iron oxide nanoparticles according to claim 3, characterized in that: The azacrown ether in step 4 is selected from any one of 4,13-diaza-18-crown-6-ether and 1,4,10,13-tetramethyl-1,4,7,10,13,16-hexaazacyclooctadecane.

8. Cryptand-modified magnetic iron oxide nanoparticles prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the cryptand-modified magnetic iron oxide nanoparticles according to claim 8 in the preparation of wastewater treatment products.

10. Use of the cryptand-modified magnetic iron oxide nanoparticles according to claim 8 in preparing products for treating heavy metal lead and cadmium ions.

Images