Sodium acetate-based nano water purifier and preparation method thereof

Abstract

The present invention relates to a benzocrown ether coupling agent and a preparation method thereof, as well as a corresponding sodium acetate-based nano water purifier and a preparation method thereof. The design idea is to perform surface silanization modification on magnetic nanoparticles that are easy to recycle using a non-ionic benzocrown ether coupling agent and an anionic sodium acetate-based coupling agent. First, a silane coupling agent containing benzocrown ether and sodium acetate groups is hydrolyzed and condensed, and crown ether and sodium acetate groups are introduced on the surface of the magnetic nanoparticles. The silanized magnetic nanoparticles are used as nano water purifiers, thereby improving the adsorption capacity and circulation efficiency of heavy metal ions, and enhancing the adsorption of Pb. 2+ selective adsorption effect.

Description

Technical Field

[0001] The invention belongs to the field of environmentally friendly materials, and particularly relates to a benzocrown ether coupling agent and a preparation method thereof, as well as a corresponding sodium acetate-based nano water purifier and a preparation method thereof. Background Art

[0002] Heavy metal ions are highly toxic and difficult to biodegrade, and their water pollution poses a serious threat to human health and ecosystems. Industrial emissions and atmospheric particulate matter are the two main sources of heavy metal pollution in water. Heavy metal concentrations above 5000g / L in water are considered toxic to the environment. Among these, Hg, Cu, Th, Cd, Pb, Cr, As, and Ni are the most serious heavy metals that pose a serious threat to the environment, animals, and public health. The concentration requirements for toxic heavy metal ions in water are generally between 200 and 500mg / L for lead ions in conventional industrial wastewater, which places very high demands on water treatment to remove heavy metal ions.

[0003] The main technologies for removing heavy metals include ion exchange, electrochemical methods, chemical precipitation, and biological removal. However, these methods are subject to high investment and operating costs, which seriously hinder their practical application. In contrast, adsorption is a feasible and promising technology due to its low cost, simple operation, and high removal efficiency. Currently, nanocomposite adsorbents are commonly used for removing heavy metal ions from water bodies, including EDTA-graphene oxide, magnetic EDTA-modified chitosan, magnetic PSEDTA resin, and EDTA-modified chitosan-silica hybrids.

[0004] It is worth noting that the current research on the removal of heavy metal ions in wastewater mainly focuses on the monolithic system, in which the object of treatment is usually a specific heavy metal ion. However, the composition of industrial wastewater in practice is complex and often contains multiple metal ions at the same time. For example, Cu 2+ and Pb 2+ Usually coexist in wastewater from printed circuit board (PCB) manufacturing. Electroplating wastewater contains a variety of metal ions, including Pb 2+ Cr 3+ 、Cu 2+ 、Zn 2+ 、Cd 2+ , Ca 2+ Mg 2+ 、Na + , K + Therefore, competitive adsorption between heavy metal ions and occupation and interference of adsorption sites are inevitable, which will lead to a serious decrease in the removal efficiency of the adsorbent, making it difficult for the treated water to meet increasingly stringent discharge standards.

[0005] In order to improve the specificity and selectivity of adsorbents, a common method is to modify the surface of inorganic adsorbents by introducing a chelating agent containing sodium acetate on the surface of the adsorbent, which has excellent chelating properties for heavy metal ions. For example, Eveliina Repo used ethylenediaminetetraacetic acid (EDTA), which is most commonly used for chelating and adsorbing heavy metal ions, to modify mesoporous materials for the selective adsorption of heavy metal ions Cu from complex water bodies in Journal of Colloid and Interface Science, 2011, 358, 1, 261-267. 2+ David Dupont used a commercial EDTA-derived silane coupling agent in Ind.Eng.Chem.Res.2014,53,15222-15229: N-(trimethoxysilyl)propylethylenediaminetriacetic acid sodium (TMS-EDTA) modified Fe3O4-based magnetic nanoparticles Fe3O4@SiO2 (TMS-EDTA) to adsorb lanthanide elements. The TMS-EDTA can be hydrolyzed into silanetriol, which condenses with the surface hydroxyl groups of the inorganic substrate. However, this type of sodium acetate-modified inorganic adsorbent still lacks selectivity for heavy metal ions. The poor adsorption specificity and selectivity result in unsatisfactory removal rate for adsorbing industrial wastewater containing multiple mixed heavy metal ions. Summary of the Invention

[0006] In view of the defects of the prior art, the technical problem to be solved by the present invention is to provide a benzocrown ether coupling agent and a preparation method thereof, as well as a corresponding sodium acetate-based nano water purifier and a preparation method thereof. By hydrolyzing and condensing a silane coupling agent containing benzocrown ether and sodium acetate groups, crown ether and sodium acetate groups are introduced on the surface of magnetic nanoparticles, and the silanized magnetic nanoparticles are used as nano water purifiers, thereby improving the adsorption capacity and circulation efficiency of heavy metal ions, and enhancing the adsorption of Pb 2+ selective adsorption effect.

[0007] The present invention relates to a benzocrown ether coupling agent and a preparation method thereof, as well as a corresponding sodium acetate-based nano-water purifier and a preparation method thereof. The design concept involves surface silanization modification of recyclable magnetic nanoparticles using a nonionic benzocrown ether coupling agent and an anionic sodium acetate-based coupling agent. First, a silane coupling agent containing benzocrown ether and sodium acetate groups is hydrolyzed and condensed to introduce the crown ether and sodium acetate groups onto the surface of the magnetic nanoparticles. The silanized magnetic nanoparticles are then used as a nano-water purifier, thereby increasing the adsorption capacity and circulation efficiency of heavy metal ions and enhancing the selective adsorption of Pb2+.

[0008] In the first aspect, a benzocrown ether coupling agent has the following general structural formula:

[0009]

[0010] wherein the R group is selected from any one of methyl, ethyl or isopropyl; the A group comprises any one of a carbamate bond or a urea bond, and the A group comprises 1 to 12 carbon atoms in total;

[0011] Preferably, the A group comprises 1 to 6 carbon atoms in total;

[0012] More preferably, the A group is selected from: or Any one of .

[0013] In a second aspect, the preparation method of the above-mentioned benzocrown ether coupling agent comprises: using an isocyanate-containing coupling agent to react with a hydroxyl-containing or amino-containing phenyl crown ether to obtain the benzocrown ether.

[0014] Preferably, the silane is obtained by reacting isocyanatepropyltrimethoxysilane or isocyanatepropyltriethoxysilane with 4'-hydroxymethylbenzo-18-crown-6 or 4'-aminobenzo-18-crown-6.

[0015] Furthermore, the reaction temperature of the reaction is room temperature to 90° C., and the reaction time is 1 to 24 hours;

[0016] Preferably, nitrogen or an inert gas is used to protect the reaction mixture during the reaction.

[0017] In a third aspect, a sodium acetate-based nano water purifier comprises magnetic nanoparticles and organic modification groups on the surface;

[0018] Wherein, the magnetic nanoparticles include Fe3O4 nanoparticles; or, Fe3O4 nanoparticles doped with MnO2;

[0019] The organic modification groups on the surface include: crown ether and sodium acetate group, wherein the crown ether is a ring structure formed by alternating connection of multiple -CH2CH2- and oxygen atoms, and the crown ether ring contains 12-24 atoms, of which the oxygen atoms include 4-8;

[0020] Preferably, the crown ether is selected from any one of 12-crown-4, 15-crown-5, 18-crown-6, 21-crown-7, 24-crown-8, benzo-18-crown-6 or benzo-24-crown-8;

[0021] More preferably, the crown ether is selected from benzo-18-crown-6.

[0022] Among them, the sodium acetate group (-CH2COONa) is connected to the N atom, and the carboxylate group and the N atom act as electron donors to jointly form a complex to complex the metal ions.

[0023] In a fourth aspect, a method for preparing a sodium acetate-based nano water purifier comprises: silanizing magnetic nanoparticles using the benzocrown ether coupling agent described above and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt;

[0024] Wherein, the magnetic nanoparticles are prepared by chemical precipitation, hydrothermal method or sol-gel method;

[0025] The silanization comprises adding an organic acid, a benzocrown ether coupling agent and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt to an alcohol dispersion of nanoparticles;

[0026] Preferably, the organic acid is selected from formic acid or acetic acid;

[0027] Preferably, the alcohol dispersion includes a dispersion of methanol, ethanol, n-propanol or isopropanol.

[0028] The beneficial effect of the present invention lies in the combined use of a nonionic crown ether, an anionic sodium acetate-based complexing agent, and easily recyclable magnetic nanoparticles. First, a silane coupling agent containing benzocrown ether is designed and prepared, and the crown ether-containing silane coupling agent and a sodium acetate-based silane coupling agent are hydrolyzed and condensed to introduce the crown ether and sodium acetate groups onto the surface of the magnetic nanoparticles. The silanized magnetic nanoparticles are then used as nano-water purifiers, thereby increasing the adsorption capacity and recycling efficiency of heavy metal ions, and enhancing the adsorption of Pb. 2+ selective adsorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the silanization modification of Fe3O4-MnO2 nanoparticles in Example 7.

[0030] Figure 2 These are X-ray photoelectron spectroscopy (XPS) spectra of the Fe3O4-MnO2 nanoparticles and silanized Fe3O4-MnO2 nanoparticles prepared in Example 7.

[0031] Figure 3 These are the X-ray diffraction (XRD) spectra of the Fe3O4-MnO2 nanoparticles and silanized Fe3O4-MnO2 nanoparticles prepared in Example 7.

[0032] Figure 4 The SEM image (a) and EDS spectrum (b) of the Fe3O4-MnO2 nanoparticles prepared in Example 7, as well as the SEM image (c) and EDS spectrum (d) of the silanized Fe3O4-MnO2 nanoparticles. DETAILED DESCRIPTION

[0033] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] If the specific experimental conditions are not specified in the examples, they are usually based on conventional conditions in the field or conditions recommended by the reagent company; the materials, reagents, etc. used in the examples can be purchased through commercial channels unless otherwise specified.

[0036] Example 1

[0037] 12.36 g (0.05 mol) of 3-isocyanatopropyltriethoxysilane was reacted with 17.12 g (0.05 mol) of 4'-hydroxymethylbenzo-18-crown-6 (CAS No.: 71015-62-8) previously dissolved in 30 mL of ethyl acetate in an environment excluding oxygen and water. Nitrogen was continuously introduced during the reaction process. The reaction temperature was 80° C. After the reaction was maintained at this temperature for 12 hours, the solvent was removed by distillation under reduced pressure to finally obtain benzocrown ether coupling agent 1. Its structural formula and corresponding reaction process are as follows:

[0038]

[0039] Structure confirmation of benzocrown ether coupling agent 1: 1H NMR (400MHz, solvent DMSO-d6): δ1.03(2H,t,J=7.67Hz), 1.32(9H,t,J=6.90Hz), 1.93(2 H,tt,J=7.67,7.51Hz),3.19(2H,t,J=7.51Hz),3.39(6H,q,J=6.90Hz),3.52-3.87 (16H,3.60(ddd,J=13.35,6.86,2.11Hz),3.61(ddd,J=13.33,6.86,2.11Hz),3.66 (ddd,J=11.27,6.97,1.92Hz),3.71(ddd,J=10.81,7.05,1.75Hz),3.75(ddd,J=15. 49,7.16,1.52Hz),3.77(ddd,J=13.35,7.16,1.52Hz),3.78(ddd,J=14.26,6.92,2 .01Hz),3.80(ddd,J=13.36,6.92,2.01Hz)),3.97-4.15(4H,4.05(ddd,J=13.70,6. 97,1.92Hz),4.07(ddd,J=13.55,7.05,1.75Hz)),5.03(2H,s),6.65-6.84(2H,6.7 0(dd,J=2.65,0.46Hz), 6.78(dd,J=8.50,0.46Hz)), 6.98(1H,dd,J=8.50,2.65Hz).

[0040] Example 2

[0041] 12.36 g (0.05 mol) of 3-isocyanatopropyltriethoxysilane was reacted with 16.35 g (0.05 mol) of 4'-aminobenzo-18-crown-6 (CAS No.: 68941-06-0) previously dissolved in 30 mL of methyl acetate in an environment excluding oxygen and water. Nitrogen was continuously introduced during the reaction process. The reaction temperature was 55° C. After the reaction was maintained at this temperature for 20 hours, the solvent was removed by distillation under reduced pressure to finally obtain benzocrown ether coupling agent 2. Its structural formula and corresponding reaction process are as follows:

[0042]

[0043] Structure confirmation of benzocrown ether coupling agent 2: 1H NMR (400MHz, solvent DMSO-d6): δ1.03 (2H,t,J=7.67Hz), 1.32 (9H,t,J=6.90Hz), 1.8 8(2H,tt,J=7.67,7.55Hz),3.11(2H,t,J=7.55Hz),3.39(6H,q,J=6.90Hz),3.52 -3.88(16H,3.60(ddd,J=11.34,6.86,2.86Hz),3.64(ddd,J=15.35,7.20,1.44H z),3.64(ddd,J=11.33,6.93,1.99Hz),3.65(ddd,J=9.95,6.86,2.86Hz),3.68( ddd,J=13.80,7.20,1.44Hz),3.69(ddd,J=10.97,7.04,1.76Hz),3.78(ddd,J=1 4.22,6.88,2.08Hz),3.80(ddd,J=13.38,6.88,2.08Hz)),3.92-4.17(4H,4.00( ddd,J=13.67,6.93,1.99Hz),4.09(ddd,J=13.54,7.04,1.76Hz)),6.76(1H,dd, J=8.75,0.44Hz), 6.89(1H,dd,J=2.47,0.44Hz), 7.33(1H,dd,J=8.75,2.47Hz).

[0044] Example 3

[0045] For the synthesis of precursor Fe3O4 nanoparticles, 35 mL of ethylene glycol and 25 mL of n-octylamine were poured into a flask and heated to 150 ° C. At the same time, 2.4 g of FeCl3 was dissolved in a beaker containing ethylene glycol (10 mL) and deionized water (3.5 mL). Once FeCl3 was completely dissolved in the aqueous solution of ethylene glycol, the Fe 3+ The solution was added to a flask containing ethylene glycol and n-octylamine and further heated under reflux at 180°C for 24 hours. After the reaction, the precipitated particles in the reaction mixture were separated using a centrifuge (5500 rpm, 15 minutes) and washed three times with acetone. Finally, they were vacuum-dried at 50°C for 30 minutes to obtain a black powder, namely Fe3O4 nanoparticles, with a yield of 1.15 g.

[0046] The silanization of Fe3O4 nanoparticles comprises the following steps: 100 mg of Fe3O4 nanoparticles are dispersed in 100 mL of methanol solution and placed in an ultrasonic bath for 30 min. Then 0.463 g (1 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.118 g (0.2 mmol) of the benzocrown ether coupling agent of Example 1 are added together with 3 mL of acetic acid, and a beaker is ultrasonically bathed for 90 min. Particles are precipitated from the reaction mixture by a centrifuge (6000 rpm, 15 min), washed once with water, and twice with acetone. Finally, vacuum drying at room temperature for 30 min yields the silanized Fe3O4 nanoparticles.

[0047] Example 4

[0048] The synthesis steps of the precursor Fe3O4 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4 nanoparticles is carried out, wherein the reactants are changed to 0.324 g (0.7 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.295 g (0.5 mmol) of the benzocrown ether coupling agent of Example 1, and the remaining steps are the same as those in Example 3.

[0049] Example 5

[0050] The synthesis steps of the precursor Fe3O4 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4 nanoparticles is carried out, wherein the reactants are changed to 0.463 g (1 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.115 g (0.2 mmol) of the benzocrown ether coupling agent of Example 2, and the remaining steps are the same as those in Example 3.

[0051] Example 6

[0052] The synthesis steps of the precursor Fe3O4 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4 nanoparticles is carried out, wherein the reactants are changed to 0.324 g (0.7 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.287 g (0.5 mmol) of the benzocrown ether coupling agent of Example 2, and the remaining steps are the same as those in Example 3.

[0053] Example 7

[0054] Synthesis of precursor Fe3O4-MnO2 nanoparticles. In a flask, 2.085g (7.5mmol) of FeSO4·7H2O was dissolved in 100mL of deionized water and heated to 90°C. Then, 2.5mL of 5M NaOH solution was added to the solution to obtain a blue-green suspension. After continuous mechanical stirring for 15min, 33mL of 0.1mM potassium permanganate solution was added dropwise, and a dark brown precipitate was produced in the flask. After continuous stirring for 2 hours, the mixture was allowed to stand for 12 hours. The precipitate was separated with a magnet, washed three times with deionized water, and vacuum dried at 50°C for 30min to obtain a black powder with a yield of 1.32g.

[0055] The silanization of Fe3O4-MnO2 nanoparticles specifically comprises the following steps: dispersing 100 mg of Fe3O4-MnO2 nanoparticles in 100 mL of a 95 wt% ethanol aqueous solution, ultrasonically bathing the solution for 30 minutes, adding acetic acid to adjust the pH of the solution to approximately 4.0, and continuously stirring the solution at room temperature for 2 hours. Then, 0.463 g (1 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt (TMS-EDTA) and 0.118 g (0.2 mmol) of the benzocrown ether coupling agent of Example 1 are added together, and the beaker is ultrasonically bathed for 90 minutes. The particles are precipitated from the reaction mixture by centrifugation (6000 rpm for 15 minutes), washed once with water, and twice with acetone. Finally, the silanized Fe3O4-MnO2 nanoparticles are dried under vacuum at room temperature for 30 minutes.

[0056] The schematic diagram of the silanization reaction of Example 7 is shown in Figure 1 , through the dehydration-condensation step of the coupling agent, benzocrown ether and EDTA groups were introduced onto the surface of Fe3O4-MnO2 nanoparticles.

[0057] Example 8

[0058] The synthesis steps of the precursor Fe3O4-MnO2 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4-MnO2 nanoparticles is carried out, wherein the reactants are changed to 0.324 g (0.7 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.295 g (0.5 mmol) of the benzocrown ether coupling agent of Example 1, and the remaining steps are the same as those in Example 7.

[0059] Example 9

[0060] The synthesis steps of the precursor Fe3O4-MnO2 nanoparticles are the same as those in Example 7; the silanization of the Fe3O4-MnO2 nanoparticles is performed, wherein the reactants are changed to 0.463 g (1 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA and 0.115 g (0.2 mmol) of the benzocrown ether coupling agent of Example 2, and the remaining steps are the same as those in Example 7.

[0061] Example 10

[0062] The synthesis steps of the precursor Fe3O4-MnO2 nanoparticles are the same as those in Example 7; the silanization of the Fe3O4-MnO2 nanoparticles is carried out, wherein the reactants are changed to 0.324 g (0.7 mmol) of trisodium N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid TMS-EDTA and 0.287 g (0.5 mmol) of the benzocrown ether coupling agent of Example 2, and the remaining steps are the same as those in Example 7.

[0063] Comparative Example 1

[0064] The synthesis steps of the precursor Fe3O4 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4 nanoparticles is performed with the reactant being changed to 0.707 g (1.2 mmol) of the benzocrown ether coupling agent in Example 1, and the remaining steps being the same as those in Example 3.

[0065] Comparative Example 2

[0066] The synthesis steps of the precursor Fe3O4-MnO2 nanoparticles are the same as those in Example 7; the silanization of the Fe3O4-MnO2 nanoparticles is performed, wherein the reactant is changed to 0.707 g (1.2 mmol) of the benzocrown ether coupling agent in Example 2, and the remaining steps are the same as those in Example 7.

[0067] Comparative Example 3

[0068] The synthesis steps of the precursor Fe3O4 nanoparticles are the same as those in Example 3; the silanization of the Fe3O4 nanoparticles is carried out, wherein the reactant is changed to 0.392 g (1.2 mmol) of N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA, and the remaining steps are the same as those in Example 3.

[0069] Comparative Example 4

[0070] The synthesis steps of the precursor Fe3O4-MnO2 nanoparticles are the same as those in Example 7; the silanization of the Fe3O4-MnO2 nanoparticles is performed by changing the reactant to N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt TMS-EDTA 0.392 g (1.2 mmol), and the remaining steps are the same as those in Example 7.

[0071] Test part:

[0072] The silanized Fe₃O₄-MnO₂ nanoparticles prepared in Example 7 were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy-electron spectroscopy (SEM-EDS). This confirmed the hybridization of Fe₃O₄ and MnO₂ to form Fe₃O₄-MnO₂ nanoparticles. Upon hybridization, an organosilane coupling agent was introduced to obtain silanized Fe₃O₄-MnO₂ nanoparticles. The corresponding results are listed in Tables 2-5.

[0073] The adsorption effect of the silanized nanoparticles of Examples 3-7 and Comparative Examples 1-4 was tested by absorbing four different heavy metal ions Pb in a pH = 6 aqueous solution in which multiple heavy metal ions coexisted. 2+ 、Zn 2+ 、Cu 2+ with cd 2+ The adsorption and desorption of the obtained silanized nanoparticles to Pb were determined by inductively coupled plasma emission spectroscopy. 2+ 、Zn 2+ 、Cu 2+ with cd 2+ The adsorption capacity Q of the nanoparticles after silanization modification was calculated, and the selectivity coefficient α for different heavy metal ions was calculated. The selectivity coefficient α was used to evaluate the adsorption of Pb by the nanoparticles after silanization modification. 2+ adsorption selectivity.

[0074]

[0075] At the same time, after 5 cycles of adsorption and desorption, the adsorption of Pb by silanized nanoparticles was determined by inductively coupled plasma emission spectroscopy. 2+ The adsorption amount Q (5,Pb2+) , and thus the Pb 2+ Adsorption cycle efficiency E (%).

[0076]

[0077] The results of testing and calculating the adsorption effects of the silanized nanoparticles of Examples 3-10 and Comparative Examples 1-4 using the above method are listed in Table 1.

[0078] XPS analysis was performed on the Fe3O4-MnO2 powder and the silanized Fe3O4-MnO2 powder prepared in Example 7 to compare the differences in elemental composition. Figure 2From the above, we can see that the binding energies of C1s, O1s, Mn2p and Fe2p are 284.8, 529.8, 642.5 and 710.3 eV respectively. After the functionalization of the nanoparticle surface by introducing the coupling agent, the two new peaks at 102.0 eV and 399.5 eV are attributed to Si2p and N1s. These are new peaks brought about by the introduction of the benzocrown ether coupling agent prepared in Example 1 and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt onto the surface of the nanoparticles. Further analysis of the O1s spectrum shows that the peak at 529.8 eV is due to the MOM (M=Fe or Mn) bond formed by hybridization in the Fe3O4-MnO2 nanoparticles. Due to the formation of Mn-O-Si, the peak moves to 529.5 eV. The spectrum of the silanized Fe3O4-MnO2 nanoparticles exhibits another difference at a binding energy of 532.2 eV, which can be attributed to the Si-O-Si and C=O bonds formed during the silanization process. The presence of Si-O-Si confirms the self-condensation of the coupling agent molecules. Furthermore, the C1s spectrum further confirms the anchoring of the nitrogen-containing coupling agent molecules to the Fe3O4-MnO2 nanoparticles, as the peak at 286.1 eV is attributed to C-N and C=O bonds. Simultaneously, the Si2p spectrum reveals three peaks at 99.8, 101.7, and 102.6 eV, corresponding to Si-C, Si-OM (M=Fe, Mn), and Si-O-Si bonds, respectively. This also confirms that the Fe3O4-MnO2 nanoparticles were surface-silanized after silanization.

[0079] The XRD characterization results are as follows Figure 3 As shown in Figure 3, the diffraction peaks at 30.13°, 35.55°, 43.17°, 53.46°, 57.18°, and 62.68° correspond to the (220), (311), (400), (422), (511), and (440) crystal planes of Fe3O4. The XRD patterns of Fe3O4-MnO2 and silanized Fe3O4-MnO2 are similar, indicating that the dehydration-condensation modification process of the coupling agent has no effect on the physical phase of the Fe3O4-MnO2 nanoparticles.

[0080] The SEM-EDS analysis results are as follows Figure 4 As shown in the figure, the appearance of Fe3O4-MnO2 nanoparticles can be obtained by direct observation. After silanization, the particle size of Fe3O4-MnO2 nanoparticles increases slightly. At the same time, EDS element semi-quantitative analysis shows that the Fe3O4-MnO2 nanoparticles after silanization have increased C, N and Si elements, and the O element content has also increased. This is due to the introduction of benzocrown ether coupling agent and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt on its surface.

[0081] Table 1

[0082]

[0083] From the results in Table 1, it can be seen that when the benzocrown ether coupling agent of Example 1 or Example 2 is used alone to silanize the nanoparticles, and the benzocrown ether modification group is introduced on the outer surface of the nanoparticles, the resulting nano water purifier has a higher circulation efficiency, but poor selectivity for Pb2+ and a low overall adsorption capacity for various heavy metal ions. In Examples 3 and 4, TMS-EDTA is used alone to silanize the nanoparticles, and EDTA modification groups are introduced on the outer surface of the nanoparticles. The resulting nano water purifier has a significantly increased adsorption capacity for heavy metal ions, but has a low selectivity for Pb2+. 2+ The selectivity is poor, and the circulation efficiency of the adsorbent is significantly reduced compared with the benzocrown ether modified group.

[0084] For Examples 3-10, benzocrown ether coupling agent and TMS-EDTA were simultaneously introduced into the surface of magnetic nanoparticles. The adsorption amount of heavy metal ions of the resulting nano water purifier did not decrease significantly compared with Comparative Examples 3 and 4, especially the selectivity for Pb2+ was improved. Each gram of adsorbent molecule was able to adsorb a higher amount of heavy metal ions Pb2+, thereby achieving a better effect in removing water pollution. It was also found that the reduction in the cycle efficiency of Examples 3-10 was not significant compared with Comparative Examples 1 and 2. After 5 adsorption-desorption cycles, the cycle adsorption efficiency E of the nano water purifier was no less than 80%, which can meet the requirements for repeated use of the water purifier.

[0085] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A sodium acetate-based nano water purifier, characterized in that: The sodium acetate-based nano water purifier comprises magnetic nanoparticles and organic modification groups on the surface; Wherein, the magnetic nanoparticles include Fe3O4 nanoparticles; or, Fe3O4 nanoparticles doped with MnO2; The organic modification groups on the surface include: crown ether and sodium acetate group; wherein the crown ether is selected from benzo-18-crown-6; The sodium acetate group is connected to the N atom, and the structural formula is -CH2-COO - Na + , in which the carboxylate and the N atom act as electron donors and jointly participate in forming a complex to complex the metal ions.

2. The preparation method of sodium acetate-based nano water purifier according to claim 1, wherein Magnetic nanoparticles were silanized using benzocrown ether coupling agent and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt; Wherein, the general structural formula of the benzocrown ether coupling agent is as follows: ； Wherein, the R group is selected from any one of methyl, ethyl or isopropyl; the A group is any one of -NH-CO-NH- or -NH-CO-O-CH2-; The magnetic nanoparticles are prepared by chemical precipitation, hydrothermal method or sol-gel method; The silanization comprises adding organic acid, benzocrown ether coupling agent and N-[(3-trimethoxysilyl)propyl]ethylenediaminetriacetic acid trisodium salt into the alcohol dispersion of nanoparticles.

3. The preparation method of sodium acetate-based nano water purifier according to claim 2, wherein The organic acid is selected from formic acid or acetic acid.

4. The preparation method of sodium acetate-based nano water purifier according to claim 2, wherein The alcohol dispersion includes: a dispersion of methanol, ethanol, n-propanol or isopropanol.

5. The preparation method of sodium acetate-based nano water purifier as claimed in claim 2, wherein The preparation method of the benzocrown ether coupling agent comprises: reacting an isocyanate-containing coupling agent with a phenyl crown ether containing a hydroxyl group or an amino group.

6. The preparation method according to claim 5, characterized in that The preparation method of the benzocrown ether coupling agent comprises: using isocyanate propyltrimethoxysilane or isocyanate propyltriethoxysilane to react with 4'-hydroxymethylbenzo-18-crown-6 or 4'-aminobenzo-18-crown-6 to obtain the benzocrown ether coupling agent.

7. The preparation method according to claim 5, characterized in that The reaction temperature is room temperature to 90° C., and the reaction time is 1 to 24 hours.

8. The preparation method according to claim 5, characterized in that During the reaction, nitrogen or inert gas is used to protect the reaction mixture.

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