An adsorbent for removing perchlorate from water and its preparation method and application

Abstract

The present invention discloses an adsorbent for removing perchlorate from water, and a preparation method and application thereof, and belongs to the technical field of water quality detection and treatment. The preparation method proposed in the present invention mainly includes the following steps: S1, preparing TAm; S2, preparing (4-bromononyl) triethylammonium bromide; S3, preparing COF1; S4, removing COF from perchlorate. Based on the above preparation method, the present invention further protects the adsorbent material prepared by the above method and the application of the material in the removal of perchlorate from water. Compared with the prior art, the preparation process of the present invention is simpler and more efficient; the present invention creatively utilizes the prepared adsorbent to carry out orderly arrangement of quaternary ammonium groups and excellent adjustment of hydrophobicity, so that the material has extremely high adsorption capacity, adsorption speed and extremely high selectivity for perchlorate.

Description

Technical Field

[0001] The invention relates to the technical field of water quality detection and treatment, and more specifically provides an adsorbent for removing perchlorate in water, and a preparation method and application thereof. Background Art

[0002] Perchlorate is a persistent, highly diffusible, water-soluble anion. In recent years, perchlorate has been detected in a large amount of groundwater and surface water, and has attracted great attention worldwide. Since perchlorate ingested by the human body will lead to insufficient secretion of thyroid hormones, thereby inhibiting the normal metabolism and growth and development of the human body, it has been included in the drinking water hygiene standards, so it is very important to control the concentration of perchlorate in drinking water.

[0003] Conventional drinking water treatment processes mainly include flocculation, sedimentation, filtration, disinfection, etc., and activated carbon adsorption is used as adsorbent, but the above methods have almost no effect on the removal of perchlorate. At present, although some perchlorate treatment technologies such as ion exchange technology, membrane filtration technology, chemical reduction method, and biological method have been developed, these technologies are complex to use and cannot be used in actual water plants.

[0004] Adsorption is one of the most common drinking water pollutant removal technologies that is simple to operate and quickly implemented. However, current adsorption materials are unable to effectively remove perchlorate from raw water because the existing adsorption materials have low selectivity for perchlorate and are unable to remove the complex ion system in raw water.

[0005] In view of this, the present invention proposes an adsorbent for removing perchlorate in water, and a preparation method and application thereof. Summary of the invention

[0006] The purpose of the present invention is to provide a preparation method of a new drinking water perchlorate removal material with simple process, high efficiency and high selectivity and its application to solve the problems raised in the background technology.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] A method for preparing an adsorbent for removing perchlorate from water comprises the following steps:

[0009] S1. Preparation of TAm:

[0010] S1.1. Add 1,3,5-phenyltriboric acid tris(pinacol) ester, CsF, Pd(dppf)Cl2-CH2Cl2 and 4-bromo-2,6-diisopropylaniline into a flask;

[0011] S1.2, degas the mixture obtained in S1.1 three times, and then add 1,4-dioxane / H2O solvent to the degassed mixture;

[0012] S1.3, heating the suspension under an inert gas environment for 24 h, cooling to room temperature, and extracting the resulting mixture with ethyl acetate;

[0013] S1.4, wash the organic phase extract with water and brine, dry over anhydrous Na2SO4, and then concentrate under reduced pressure;

[0014] S1.5, purify the crude solid obtained after the treatment in 1.4 by silica gel column chromatography to obtain light grey solid TAm;

[0015] S2. Preparation of (4-bromononyl)trimethylammonium bromide:

[0016] S2.1, reflux triethylamine, 1,4-dibromononane and acetonitrile under an inert gas environment for 12-24 hours;

[0017] S2.2, after cooling, evaporating the solvent under reduced pressure, dissolving the residue in hot acetonitrile; after further cooling, a diionic product precipitate is formed;

[0018] S2.3, filter out the precipitate, add ethyl acetate to the filtrate to obtain a white solid;

[0019] S2.4. Filter and collect the white solid obtained in S2.3, and dry it in vacuo to obtain (4-bromononyl)trimethylammonium bromide;

[0020] S3. Preparation of COF1:

[0021] S3.1, put 2,5-dihydroxyterephthalaldehyde and TAm prepared in S1 into a test tube, and dissolve them in a mixed solution of 1,2-dichlorobenzene / n-butanol / 6 M acetic acid water;

[0022] S3.2, sonicate the mixture obtained in S3.1 for 20-60 minutes, then quickly freeze in liquid nitrogen at 77 K, evacuate and vacuum seal;

[0023] S3.3, heat the test tube at 110-140 °C for 96-128 hours, separate the brown precipitate by filtration, and wash with anhydrous tetrahydrofuran;

[0024] S3.4, subjecting the washed precipitate to Soxhlet extraction for 6-8 days to obtain COF1;

[0025] S4. Preparation of perchlorate-removed COF:

[0026] S4.1. Place COF1 prepared in S3, (4-bromononyl)trimethylammonium bromide and Cs2CO3 into a flask, and then evacuate the flask and purge it with helium three times;

[0027] S4.2, add anhydrous DMF under helium atmosphere, and heat the reaction mixture at 100 °C for 24 hours;

[0028] S4.3. After the reaction is completed, filter the generated solid and wash it thoroughly with water and ethanol;

[0029] S4.4. The washed final product is vacuum dried at 70-90°C for 12-24 hours to obtain the final perchlorate removal COF.

[0030] Preferably, the molar ratio of 1,3,5-phenyltriboric acid tris(pinacol) ester, CsF, Pd(dppf)Cl2-CH2Cl2 and 4-bromo-2,6-diisopropylaniline in S1.1 is 4.5-5.5:45-55:0.2-0.3:15-19.

[0031] Preferably, the volume ratio of 1,4-dioxane to H2O in the 1,4-dioxane / H2O solvent described in S1.2 is 3-5:1.

[0032] Preferably, the inert gas in S1.3 includes but is not limited to N2, and the temperature of the inert gas environment is 105-125°C.

[0033] Preferably, the silica gel column in S1.5 is composed of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 4-6:1.

[0034] Preferably, the molar ratio of triethylamine to 1,4-dibromononane in S2.1 is 0.05-0.15:0.4-0.6; the inert gas includes but is not limited to N2, and the temperature of the inert gas environment is 70-90°C.

[0035] Preferably, the molar ratio of 2,5-dihydroxyterephthalaldehyde to TAm in S3.1 is 0.1-0.2:0.05-0.15; the volume ratio of 1,2-dichlorobenzene to n-butanol and 6 M acetic acid in the 1,2-dichlorobenzene / n-butanol / 6 M acetic acid aqueous solution is 4-6:4-6:1.

[0036] Preferably, the mass ratio of COF1, (4-bromononyl)trimethylammonium bromide and Cs2CO3 in S4.1 is 70-90:60-80:80-100.

[0037] An adsorbent prepared by the method and used for removing perchlorate in water.

[0038] The invention discloses an application of the prepared adsorbent in removing perchlorate from water.

[0039] Compared with the prior art, the present invention provides an adsorbent for removing perchlorate in water and a preparation method and application thereof, which have the following beneficial effects:

[0040] The present invention provides a method for preparing an adsorbent for removing perchlorate from water. Compared with the prior art, the preparation process of the method is simpler and more efficient. The present invention creatively utilizes the prepared adsorbent to carry out orderly arrangement of quaternary ammonium groups and excellent adjustment of hydrophobicity, so that the material has extremely high adsorption capacity, adsorption speed and extremely high selectivity for perchlorate. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a synthesis flow chart of an adsorbent material for removing perchlorate from water mentioned in an embodiment of the present invention;

[0042] Figure 2 The powder XRD pattern of the COF material prepared in the embodiment of the present invention;

[0043] Figure 3 This is an infrared characteristic image of the COF material prepared in the embodiment of the present invention;

[0044] Figure 4 is a C nuclear magnetic resonance image of the COF material prepared in the embodiment of the present invention;

[0045] Figure 5 TEM transmission image of the COF material prepared in the embodiment of the present invention;

[0046] Figure 6 Graph showing the contact angle of the COF material prepared in the embodiment of the present invention;

[0047] Figure 7 Graph showing the adsorption capacity of perchlorate by the COF material prepared in the embodiment of the present invention;

[0048] Figure 8 is a graph showing the adsorption rate of perchlorate by the COF material prepared in an embodiment of the present invention;

[0049] Fig. 9 Graph showing the selectivity of the COF material prepared in the examples of the present invention to perchlorate. DETAILED DESCRIPTION

[0050] The following examples further illustrate the specific implementation of the present application, but the protection scope of the present application is not limited by these specific implementations, but is determined by the appendix claims. Unless otherwise specified, the raw materials used are conventional products purchased from the market.

[0051] Example 1

[0052] See also Figure 1 The present invention provides a method for preparing an adsorbent for removing perchlorate from water, comprising the following steps:

[0053] Step 1:

[0054] 5.0 mmol 1,3,5-phenyltriboric acid tris(pinacol) ester, 50 mmol CsF, 0.25 mmol Pd(dppf)Cl2-CH2Cl2, and 17 mmol 4-bromo-2,6-diisopropylaniline were added to the flask. The mixture was degassed three times, and then 150 mL 1,4-dioxane / H2O (v / v=4 / 1) was added to the degassed mixture. The suspension was heated under an inert gas such as N2 at 105-125 °C for 24 h. After cooling to room temperature, the resulting mixture was extracted with ethyl acetate. The organic phase extract was washed with water and brine, dried over anhydrous Na2SO4, and then concentrated under reduced pressure. The crude solid was purified by silica gel column chromatography (petroleum ether / ethyl acetate, 5 / 1, v / v) to obtain a light gray solid TAm. This molar ratio can be scaled up or down for material synthesis.

[0055] Step 2:

[0056] 0.1 mmol triethylamine, 0.5 mmol 1,4-dibromononane and 20 ml acetonitrile are refluxed in an inert gas environment such as N2 at 70-90 °C for 12 to 24 hours. After cooling, the solvent is evaporated under reduced pressure and the residue is dissolved in hot acetonitrile. After cooling, a precipitate is formed, which is mainly a diionic product. The precipitate is filtered off and ethyl acetate is added to the filtrate to obtain a white solid. This solid is collected by filtration and vacuum dried to obtain (4-bromononyl)trimethylammonium bromide. This molar ratio can be scaled up or down in equal proportions for material synthesis.

[0057] Step 3:

[0058] 0.15 mmol 2,5-dihydroxyterephthalaldehyde and 0.1 mmol TAm were placed in a test tube and dissolved in 1.2 mL 5:5:1 (v / v / v) 1,2-dichlorobenzene / n-butanol / 6 M acetic acid aqueous solution. The mixture was sonicated for 20-60 minutes, then quickly frozen in liquid nitrogen at 77 K, evacuated and vacuum sealed. The test tube was then heated at 110-140 °C for 96-128 hours. The brown precipitate was separated by filtration, washed with anhydrous tetrahydrofuran, and then Soxhlet extracted for 6-8 days to obtain COF1. This molar ratio can be scaled up or down to synthesize materials.

[0059] Step 4:

[0060] 80 mg COF1, 71 mg (4-bromononyl) trimethylammonium bromide and 90 mg Cs2CO3 were placed in a flask, which was then evacuated and purged with helium three times. Then 20 mL of anhydrous DMF was added under helium. The reaction mixture was heated at 100 °C for 24 hours. After the reaction, the solid was filtered and thoroughly washed with water and ethanol. The final product was vacuum dried at 70-90 °C for 12-24 hours to obtain the final perchlorate-removed COF. This mass ratio can be scaled up or down to synthesize the material.

[0061] An adsorbent for removing perchlorate in water was prepared by the above method, and the prepared adsorbent was experimentally characterized. The specific contents are as follows.

[0062] XRD Characterization:

[0063] The powder of the prepared adsorbent was characterized by XRD. The data are as follows: Figure 2 As shown. Figure 2 It can be seen that the XRD data are consistent with the theoretical peak of the adsorbent, proving the successful synthesis of the material, and the crystal parameters of the material are also obtained.

[0064] Infrared FT-IR characterization:

[0065] The prepared adsorbent material was characterized by infrared FT-IR, and the data are as follows: Figure 3 As shown. Figure 3 It can be seen that the formation of the C=N double bond indicates that the material group units are successfully connected, proving the successful synthesis of the material.

[0066] C NMR Characterization:

[0067] In order to further determine whether the synthetic structure of the material is the same as the expected result, the C nuclear magnetic resonance spectrum of the prepared adsorbent was measured. Figure 4The peak position of the material shown is consistent with the structure, indicating that the structure of the synthesized material is the same as expected.

[0068] TEM transmission characterization:

[0069] The structure of the prepared adsorbent material was characterized and observed, such as Figure 5 As shown, the material has an obvious crystal structure and the lattice morphology is consistent with the characteristics of COF materials.

[0070] Contact angle characterization:

[0071] The prepared adsorbent material was tested for its hydrophilicity and hydrophobicity contact angle, such as Figure 6 As shown, the material contact angle is as high as 140 o , with strong hydrophobicity.

[0072] Adsorption capacity characterization:

[0073] Take 0.1 mg of the prepared adsorbent material and add it to a 500 mL beaker. Add different concentrations of perchlorate solution to the beaker to make up to 500 mL, such as Figure 7 The figure shows 0-400 mg / L. Place the beaker in an oscillator and oscillate for 24 hours. After settling for 1 hour, take out the solution, filter it into an ion chromatograph to measure the perchlorate concentration at this time. The concentration of perchlorate added at the beginning - the concentration of perchlorate after adsorption, divided by the concentration of the adsorbent material of 0.2 mg / L, and finally converted to mg / g to obtain the adsorption isotherm in the figure. Different temperatures refer to adjusting the temperature of the oscillator so that the temperature in the beaker is the set temperature, and the adsorption isotherm of the material is obtained according to the same conditions and calculations as above.

[0074] Adsorption rate characterization:

[0075] Take 0.1 mg of the prepared adsorbent material and add it to a 500 mL beaker. Add a 20 mg / L perchlorate solution to the beaker to make it 500 mL. Place the beaker in an oscillator and oscillate. Take samples every 1 min to measure the perchlorate concentration until 20 min. Then calculate the removal rate using the ratio of the initial concentration to the perchlorate concentration difference at different adsorption times. Figure 8 Content shown.

[0076] Selective Characterization:

[0077] The ion selectivity of the synthesized adsorbent material was tested. 0.1 mg of the synthesized adsorbent material was added to a 500 mL beaker, and 20 mg / L perchlorate and other anion solutions were added to the beaker to make up to 500 mL. Other anion species such as Fig. 9 As shown, only perchlorate solution and another anion are added each time, and the calculation formula is as follows:

[0078]

[0079]

[0080] in, C 0 and C e Respectively represent ClO4 - Initial concentration and equilibrium solution concentration (mg / L). β t represents the selectivity coefficient of the target anion, K d,t represents the distribution coefficient of the target ion in the presence of competitors, K d,c Represents the distribution coefficient of the competitor in the presence of the target ion.

[0081] In summary, the present invention proposes a method for preparing an adsorbent for removing perchlorate from water. Compared with the prior art, the preparation process of the present method is simpler and more efficient. The present invention creatively utilizes the prepared adsorbent to carry out orderly arrangement of quaternary ammonium groups and excellent adjustment of hydrophobicity, so that the material has extremely high adsorption capacity, adsorption speed and extremely high selectivity for perchlorate.

[0082] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing an adsorbent for removing perchlorate from water, characterized in that: The following steps are involved: S1. Preparation of TAm: S1.

1. Add 1,3,5-phenyltriboric acid tris(pinacol) ester, CsF, Pd(dppf)Cl2-CH2Cl2 and 4-bromo-2,6-diisopropylaniline into a flask; S1.2, degas the mixture obtained in S1.1 three times, and then add 1,4-dioxane / H2O solvent to the degassed mixture; S1.3, heating the suspension under an inert gas environment for 24 h, cooling to room temperature, and extracting the resulting mixture with ethyl acetate; S1.4, wash the organic phase extract with water and brine, dry over anhydrous Na2SO4, and then concentrate under reduced pressure; S1.5, purify the crude solid obtained after the treatment in 1.4 by silica gel column chromatography to obtain light grey solid TAm; S2. Preparation of (4-bromononyl)trimethylammonium bromide: S2.1, reflux triethylamine, 1,4-dibromononane and acetonitrile under an inert gas environment for 12-24 hours; S2.2, after cooling, evaporating the solvent under reduced pressure, dissolving the residue in hot acetonitrile; after further cooling, a diionic product precipitate is formed; S2.3, filter out the precipitate, add ethyl acetate to the filtrate to obtain a white solid; S2.

4. Filter and collect the white solid obtained in S2.3, and dry it in vacuo to obtain (4-bromononyl)trimethylammonium bromide; S3. Preparation of COF1: S3.1, put 2,5-dihydroxyterephthalaldehyde and TAm prepared in S1 into a test tube, and dissolve them in a mixed solution of 1,2-dichlorobenzene / n-butanol / 6 M acetic acid water; S3.2, sonicate the mixture obtained in S3.1 for 20-60 minutes, then quickly freeze in liquid nitrogen at 77 K, evacuate and vacuum seal; S3.3, heat the test tube at 110-140 °C for 96-128 hours, separate the brown precipitate by filtration, and wash with anhydrous tetrahydrofuran; S3.4, subjecting the washed precipitate to Soxhlet extraction for 6-8 days to obtain COF1; S4. Preparation of perchlorate-removed COF: S4.

1. Place COF1 prepared in S3, (4-bromononyl)trimethylammonium bromide and Cs2CO3 into a flask, and then evacuate the flask and purge it with helium three times; S4.2, add anhydrous DMF under helium atmosphere, and heat the reaction mixture at 100 °C for 24 hours; S4.

3. After the reaction is completed, filter the generated solid and wash it thoroughly with water and ethanol; S4.

4. The washed final product is vacuum dried at 70-90°C for 12-24 hours to obtain the final perchlorate removal COF.

2. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The molar ratio of 1,3,5-phenyltriboric acid tris(pinacol) ester, CsF, Pd(dppf)Cl2-CH2Cl2 and 4-bromo-2,6-diisopropylaniline described in S1.1 is 4.5-5.5:45-55:0.2-0.3:15-19.

3. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The volume ratio of 1,4-dioxane to H2O in the 1,4-dioxane / H2O solvent described in S1.2 is 3-5:

1.

4. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The inert gas in S1.3 includes N2, and the temperature of the inert gas environment is 105-125°C.

5. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The silica gel column in S1.5 is composed of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether to ethyl acetate is 4-6:

1.

6. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The molar ratio of triethylamine to 1,4-dibromononane in S2.1 is 0.05-0.15:0.4-0.6; the inert gas includes N2, and the temperature of the inert gas environment is 70-90°C.

7. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The molar ratio of 2,5-dihydroxyterephthalaldehyde to TAm in S3.1 is 0.1-0.2:0.05-0.15; the volume ratio of 1,2-dichlorobenzene to n-butanol and 6 M acetic acid in the 1,2-dichlorobenzene / n-butanol / 6 M acetic acid aqueous solution is 4-6:4-6:

1.

8. The method for preparing an adsorbent for removing perchlorate from water according to claim 1, characterized in that: The mass ratio of COF1, (4-bromononyl)trimethylammonium bromide and Cs2CO3 described in S4.1 is 70-90:60-80:80-100.

9. An adsorbent for removing perchlorate from water, prepared by the method according to any one of claims 1 to 8.

10. Use of the adsorbent according to claim 9 in removing perchlorate from water.

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