Preparation method and application of magnetic amino gel

Abstract

The application belongs to the field of solid adsorbent compositions, and particularly relates to a preparation method of magnetic amino gel and application thereof. The magnetic amino gel is prepared by subjecting magnetic microspheres with amino, organic polyamine and N,N-methylene bisacrylamide to a Michael addition reaction in a solvent. The magnetic amino gel of the application solves the shortcomings of traditional adsorbents that are not easy to separate from water bodies and are difficult to recycle, and has a large adsorption capacity for anionic dyes and a high adsorption capacity of 650 mg / g or more for methyl blue.

Description

Technical Field

[0001] This invention belongs to the field of solid adsorbent compositions, specifically relating to a method for preparing a magnetic amino gel and its application. Background Technology

[0002] Dye wastewater is characterized by high color intensity, high organic pollutant content, complex composition, variable water quality, high biotoxicity, and difficulty in biodegradation, with a trend towards resistance to photolysis and oxidation, further increasing the difficulty of treating it. Chemical adsorbents are an effective method for treating dyeing and printing wastewater, showing excellent treatment results for organic dyes, and are inexpensive, highly efficient, and easy to operate. By adding magnetic nanoparticles to traditional chemical adsorbents, the adsorbent acquires physical magnetism, enabling it to quickly separate from the water in an external magnetic field without causing secondary pollution. This overcomes the shortcomings of traditional adsorbents, such as difficulty in separating from water and difficulty in recovery.

[0003] Currently, magnetic hydrogel materials are increasingly being studied for the adsorption and treatment of organic dyes in water due to their excellent magnetism, stability, and good biocompatibility. However, many magnetic gels have small adsorption capacities and poor adsorption effects, and cannot specifically adsorb high concentrations of a particular type of dye, thus limiting their application in industries with specific needs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing magnetic amino gel, which can achieve high-capacity adsorption of anionic dyes in wastewater.

[0005] A second objective of this invention is to provide an application of the above-mentioned magnetic amino gel as a dye adsorbent.

[0006] To achieve the above objectives, the technical solution for preparing the magnetic amino gel of the present invention is as follows:

[0007] A method for preparing a magnetic amino gel includes the following steps: performing a Michael addition reaction of amino-containing magnetic microspheres, organic polyamines, and N,N-methylenebisacrylamide in a solvent to obtain a magnetic amino gel.

[0008] This invention utilizes the Michael addition reaction between the amino groups in organic polyamines and amino magnetic microspheres and the double bonds of the acryloyl groups in N,N-methylenebisacrylamide. The resulting hyperbranched polymer is chemically bonded to the magnetic microspheres, forming an amino gel with hyperbranched polymer-linked magnetic microspheres. The amino groups of the magnetic microspheres linked by the hyperbranched polymer possess lone pairs of electrons, which, under neutral or acidic conditions, bind to hydrogen ions in aqueous solution to form positively charged amino groups. Based on the principle of electrostatic adsorption of positive and negative ions, negatively charged anionic dyes can be easily adsorbed, achieving a large adsorption capacity for anionic dyes. Furthermore, the magnetic microspheres impart magnetism to the gel, facilitating magnetic separation after adsorption and enabling rapid separation of the gel adsorbent from the water.

[0009] The magnetic amino gel prepared by this invention has a large adsorption capacity for anionic dyes, with an adsorption capacity of methylene blue exceeding 650 mg / g.

[0010] The structure and functional groups of the polymer formed are controlled by adjusting the ratio of double bonds in the polyamine and N,N-methylenebisacrylamide, thereby further improving the adsorption capacity for anionic dyes. Preferably, the molar ratio of the organic polyamine to N,N-methylenebisacrylamide is 1:1 to 2.2.

[0011] To further connect the magnetic microspheres to the hyperbranched polymer, preferably, the mass ratio of the amino-containing magnetic microspheres to the total mass of the organic polyamine and N,N-methylenebisacrylamide is 1-5:15-25.

[0012] To ensure a more complete Michael addition reaction, preferably, the temperature of the addition reaction is 40-70°C and the reaction time is 6-36 hours.

[0013] To further regulate the structure and functional groups of the polymer formed by the addition reaction and improve its adsorption performance for anionic dyes, preferably, the organic polyamine is selected from one or more of diethylenetriamine, hexamethylenediamine, and butanediamine.

[0014] Preferably, the method for preparing the amino-containing magnetic microspheres includes the following steps: 1) co-precipitating a mixed solution of ferrous and ferric ions under the action of polyvinylpyrrolidone dispersant, and obtaining magnetic microspheres after ferromagnetic separation; 2) reacting the magnetic microspheres dispersed in the solvent with an amino-containing silane coupling agent to obtain amino-containing magnetic microspheres.

[0015] To further improve the ferromagnetic separation performance of the magnetic microspheres, preferably, the molar ratio of divalent iron ions to trivalent iron ions in step 1) is 1:2; and the temperature of the ion co-precipitation is 30-50℃.

[0016] In order to obtain magnetic ions with higher purity through ion coprecipitation and to successfully graft more amino groups, preferably, the pH of the solution system in steps 1) and 2) is above 10.

[0017] The technical solution for using the magnetic amino gel of the present invention as a dye adsorbent is as follows:

[0018] An application of a magnetic amino gel as a dye adsorbent, wherein the dye is an anionic dye.

[0019] Preferably, the anionic dye is methylene blue.

[0020] To further improve the adsorption capacity for anions, preferably, the pH of the anionic dye is controlled at 5-7 during adsorption. Attached Figure Description

[0021] Figure 1 A graph showing the relationship between different raw material ratios and adsorption capacity of the magnetic amino gel provided by this invention.

[0022] Figure 2 Adsorption curves of the magnetic amino gel provided by the present invention under different pH conditions;

[0023] Figure 3 The adsorption curves of the magnetic amino gel provided by the present invention at different methylene blue concentrations. Detailed Implementation

[0024] A method for preparing a magnetic amino gel includes the following steps: performing a Michael addition reaction of amino-containing magnetic microspheres, organic polyamines, and N,N-methylenebisacrylamide in a solvent to obtain a magnetic amino gel.

[0025] In a specific embodiment of the present invention, when the organic polyamine is diethylenetriamine, the molar ratio of diethylenetriamine to N,N-methylenebisacrylamide is 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, or 1:2.2.

[0026] When the organic polyamine is hexamethylenediamine or butylenediamine, the molar ratio of hexamethylenediamine or butylenediamine to N,N-methylenebisacrylamide is 1:1 to 2. Specifically, the molar ratio of hexamethylenediamine or butylenediamine to N,N-methylenebisacrylamide is 1:1.2, 1:1.4, 1:1.6, 1:1.8, or 1:2.

[0027] In a specific embodiment of the present invention, the total mass ratio of the organic polyamine and N,N-methylenebisacrylamide to the volume ratio of the solvent is 15-25 g / 100 ml, preferably, the total mass ratio of the organic polyamine and N,N-methylenebisacrylamide to the volume ratio of the solvent is 20 g / 100 ml.

[0028] In a specific embodiment of the present invention, the solvent is a mixed solution of ethanol and distilled water in equal volumes, and the ratio of the mass of the amino-containing magnetic microspheres to the volume of the solvent is 1 to 5 g / 100 mL. Preferably, the ratio of the mass of the amino-containing magnetic microspheres to the volume of the solvent is 1.6 g / 100 mL.

[0029] Preferably, the method for preparing the amino-containing magnetic microspheres includes the following steps: 1) co-precipitating a mixed solution of ferrous and ferric ions under the action of polyvinylpyrrolidone dispersant, and obtaining magnetic microspheres after ferromagnetic separation; 2) reacting the magnetic microspheres dispersed in the solvent with an amino-containing silane coupling agent to obtain amino-containing magnetic microspheres.

[0030] In a specific embodiment of the present invention, the iron ion mixed solution in step 1) is Fe 3+ Solution and Fe 2+ The solutions are mixed in equal volumes, and the volume ratio of the added polyvinylpyrrolidone to the iron ion mixed solution is 2.5 g / 100 mL.

[0031] In a specific embodiment of the present invention, in step 1), concentrated ammonia is slowly added to adjust the pH of the solution system to 10-11, and after adjustment, stirring is continued for 30-90 minutes to carry out ion co-deposition.

[0032] In a specific embodiment of the present invention, the dispersing solvent in step 2) is a mixed solution of distilled water and ethanol, and the ratio of the amount of magnetic microspheres added to the volume of the mixed solution is 0.5 to 3 g / 100 mL.

[0033] In a specific embodiment of the present invention, in step 2), the mass ratio of the amino-containing silane coupling agent to the magnetic microspheres is 1 to 5:10, and the silane coupling agent is dispersed in an ethanol solution with a mass fraction of 10 wt%.

[0034] The present invention will now be described in detail with reference to the embodiments.

[0035] I. Specific Examples of the Preparation Method of the Magnetic Amino Gel of the Present Invention

[0036] Example 1

[0037] (1) Preparation of amino-containing magnetic microspheres

[0038] 1) Prepare 0.2 mol / L Fe solutions respectively 3+ Solution, 0.1 mol / L Fe 2+Take 100 mL of each solution and mix them evenly to form a mixed solution. During stirring, add 5 g of polyvinylpyrrolidone as a dispersant to the mixed solution. After heating to 40 °C, slowly add concentrated ammonia water to adjust the pH to 10. Continue stirring for 1 h to carry out ion co-precipitation. After ferromagnetic separation, magnetic microspheres are obtained.

[0039] 2) Wash the magnetic microspheres obtained in step 1) three times with distilled water, and ultrasonically disperse them in 100 mL of a mixed solution of distilled water and ethanol (the mass ratio of water to ethanol is 2:8). Adjust the pH value to 10 with ammonia water, and slowly add 10 g of an ethanol solution of amino-containing silane coupling agent KH-550 (3-aminopropyltriethoxysilane) under ultrasonication, wherein the mass fraction of KH-550 is 10 wt%. Perform the silanization reaction for 40 min, and after ferromagnetic separation, wash three times with a mixed solution of distilled water and ethanol to obtain amino-containing magnetic microspheres.

[0040] (2) Preparation of magnetic amino gel

[0041] 1.6 g of the amino-containing magnetic microspheres obtained above, 6 g of diethylenetriamine, and 18.5 g of N,N-methylenebisacrylamide were successively added to 107 mL of a mixed solution of ethanol and distilled water of equal volume. At this time, the molar ratio of diethylenetriamine to N,N-methylenebisacrylamide was 1:1.2. After the reagents were completely dissolved, the solution was kept in a constant temperature water bath at 50 °C for 24 h to obtain a magnetic amino gel.

[0042] In other embodiments, the molar ratio of diethylenetriamine and N,N-methylenebisacrylamide was adjusted to 1:1.4, 1:1.6, 1:1.8, and 1:2, while other experimental parameters remained unchanged, to obtain magnetic amino gels with different raw material ratios.

[0043] Example 2

[0044] The difference between this embodiment and Example 1 is that the organic polyamine in step (2) is hexamethylenediamine.

[0045] In other embodiments, the molar ratio of hexamethylenediamine and N,N-methylenebisacrylamide was adjusted to 1:1.2, 1:1.4, 1:1.6, 1:1.8, and 1:2, while keeping other experimental parameters unchanged, to obtain magnetic amino gels with different raw material ratios.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that the organic polyamine in step (2) is butanediamine.

[0048] In other embodiments, the molar ratio of butanediamine and N,N-methylenebisacrylamide was adjusted to 1:1.2, 1:1.4, 1:1.6, 1:1.8, and 1:2, while other experimental parameters remained unchanged, to obtain magnetic amino gels with different raw material ratios.

[0049] Example 4

[0050] The difference between this embodiment and embodiment 1 is that in step (2), 2g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 18.5g of N,N-methylenebisacrylamide are added to 125mL of an equal volume of ethanol and distilled water mixture.

[0051] Example 5

[0052] The difference between this embodiment and Example 1 is that in step (2), 1.4g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 21.6g of N,N-methylenebisacrylamide are added to 140mL of an equal volume of ethanol and distilled water mixture.

[0053] Example 6

[0054] The difference between this embodiment and embodiment 1 is that in step (2), 4g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 24.7g of N,N-methylenebisacrylamide are added to 155mL of an equal volume of ethanol and distilled water mixture.

[0055] Example 7

[0056] The difference between this embodiment and Example 1 is that in step (2), 5.3g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 27.7g of N,N-methylenebisacrylamide are added to 170mL of an equal volume of ethanol and distilled water mixture.

[0057] Example 8

[0058] The difference between this embodiment and embodiment 1 is that in step (2), 6.1g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 30.1g of N,N-methylenebisacrylamide are added to 185mL of an equal volume of ethanol and distilled water mixture.

[0059] Example 9

[0060] The difference between this embodiment and embodiment 1 is that in step (2), 10g of the amino-containing magnetic microspheres obtained above, 6g of diethylenetriamine, and 33.9g of N,N-methylenebisacrylamide are added to 200mL of an equal volume of ethanol and distilled water mixture.

[0061] II. Specific Examples of the Application of the Magnetic Amino Gel of the Present Invention as an Anionic Dye Adsorbent

[0062] Example 10

[0063] The application of the magnetic amino gel as a dye adsorbent provided in this embodiment is to use the magnetic amino gel provided by the present invention as an adsorbent for the adsorption of methylene blue. The specific method is as follows: 0.01g of magnetic amino gel as an adsorbent is added to 25mL of 100-600g / L methylene blue solution, the pH of the solution is adjusted to 2-7, the adsorption time is 6h, and the stirring speed is 100r / min to carry out methylene blue adsorption.

[0064] III. Experimental Examples

[0065] This experimental example uses the adsorption test method of Example 10 to test the adsorption performance of the magnetic amino gels prepared in Examples 1-3. The test results are as follows: Figure 1-3 As shown.

[0066] Figure 1 The adsorption curves for magnetic amino gels prepared with different raw material ratios in the examples are shown below (different molar ratios of diethylenetriamine and N,N-methylenebisacrylamide in Example 1, hexamethylenediamine and N,N-methylenebisacrylamide in Example 2, and butanediamine and N,N-methylenebisacrylamide in Example 3). The adsorption parameters were as follows: 0.01 g of magnetic amino gel was added as adsorbent to 25 mL of 400 mg / L methylene blue solution, the pH of the solution was adjusted to 5, the adsorption time was 6 h, and the stirring speed was 100 r / min. Figure 1 It is known that the magnetic amino gel provided by the present invention can adsorb more than 650 mg / g of the anionic dye methylene blue. The adsorption capacity is the largest when the molar ratio of diethylenetriamine to N,N-methylenebisacrylamide is 1:1.6, reaching 834.3 mg / g. The adsorption capacity is the largest when the molar ratio of hexamethylenediamine or butanediamine to N,N-methylenebisacrylamide is 1:1.4. For the hexamethylenediamine system, the maximum adsorption capacity is 768.9 mg / g, and for the butanediamine system, the maximum adsorption capacity is 736.2 mg / g.

[0067] Figure 2 The adsorption curves of the magnetic amino gel under different pH conditions are shown. The adsorption parameters are as follows: 0.01g of the magnetic amino gel prepared with the optimal raw material ratio obtained above is added as adsorbent to 25mL of 400mg / L methylene blue solution (the optimal ratio in the examples is 1:1.6, and the optimal ratio in Examples 2-3 is 1:1.4). The pH of the solution is adjusted to 2-7, the adsorption time is 6h, and the stirring speed is 100r / min. Figure 1It can be seen that the magnetic amino gel provided by the present invention has an adsorption capacity that first increases and then slightly decreases with increasing pH in the pH range of 2-7, and has a higher adsorption capacity at pH 5.

[0068] Figure 3 The graph shows the adsorption capacity curves of magnetic amino gel with different concentrations of methylene blue. The adsorption parameters were as follows: 0.01g of magnetic amino gel prepared with the optimal raw material ratio obtained above was added as adsorbent to 25mL of 100-600mg / L methylene blue solution, the pH of the solution was adjusted to 5, the adsorption time was 6h, and the stirring speed was 100r / min. Figure 1 It can be seen that the adsorption capacity of the magnetic amino gel provided by the present invention increases first at different methylene blue concentrations, and then reaches equilibrium at a methylene blue concentration of 400 mg / L.

Claims

1. A method for preparing a magnetic amino gel, characterized in that, The method includes the following steps: A Michael addition reaction is carried out on amino-containing magnetic microspheres, an organic polyamine, and N,N-methylenebisacrylamide in a solvent to obtain a magnetic amino gel for anionic dye adsorption; the molar ratio of the organic polyamine to N,N-methylenebisacrylamide is 1:1~2.2; the mass ratio of the amino-containing magnetic microspheres to the total mass of the organic polyamine and N,N-methylenebisacrylamide is 1~5:15~25.

2. The method for preparing the magnetic amino gel according to claim 1, characterized in that, The total mass ratio of the organic polyamine and N,N-methylenebisacrylamide to the volume ratio of the solvent is 15–25 g / 100 ml.

3. The method for preparing the magnetic amino gel as described in claim 1, characterized in that, The mass ratio of amino-containing magnetic microspheres to solvent volume is 1–5 g / 100 mL.

4. The method for preparing the magnetic amino gel according to claim 1, characterized in that, The addition reaction is carried out at a temperature of 40-70℃ for 6-36 hours.

5. The method for preparing the magnetic amino gel according to claim 1, characterized in that, The organic polyamine is selected from one or more of diethylenetriamine, hexamethylenediamine, and butanediamine.

6. The method for preparing the magnetic amino gel according to any one of claims 1-5, characterized in that, The method for preparing the amino-containing magnetic microspheres includes the following steps: 1) Co-precipitating a mixed solution of ferrous and ferric ions under the action of polyvinylpyrrolidone dispersant, and obtaining magnetic microspheres after ferromagnetic separation; 2) reacting the magnetic microspheres dispersed in the solvent with an amino-containing silane coupling agent to obtain amino-containing magnetic microspheres.

7. The method for preparing the magnetic amino gel according to claim 6, characterized in that, In step 1), the molar ratio of ferrous ions to ferric ions is 1:2; the temperature for ion co-precipitation is 30-50℃.

8. The method for preparing the magnetic amino gel as described in claim 6, characterized in that, The pH of the solution system in steps 1) and 2) is above 10.

9. An application of the magnetic amino gel as described in claim 1 as a dye adsorbent, characterized in that, The dye is an anionic dye.

10. The application of the magnetic amino gel as a dye adsorbent as described in claim 9, characterized in that, The pH of the anionic dye is controlled at 5-7 during adsorption.

Images