Preparation method of acacia gum nano-composite hydrogel
By introducing CuFe2O4 magnetic nanoparticles and amide oxime groups into acacia resin, a highly efficient nanocomposite hydrogel was prepared, which solved the problem of insufficient adsorption capacity of unmodified acacia resin and achieved efficient removal and regeneration of heavy metals.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN POLYTECHNIC
- Filing Date
- 2023-04-14
- Publication Date
- 2026-04-17
AI Technical Summary
The adsorption capacity of existing unmodified acacia resin is not satisfactory, making it difficult to effectively remove heavy metals.
CuFe2O4 magnetic nanoparticles were prepared by coprecipitation, and polyacrylonitrile was grafted onto the acacia resin polymer chain in its presence. Subsequently, hydroxylamine hydrochloride was used to treat the nanoparticles to form amamidoxime groups, thus preparing acacia resin nanocomposite hydrogel.
The prepared acacia resin nanocomposite hydrogel combines the characteristics of natural polymers, synthetic polymers and inorganic nanoparticles, making it a highly efficient adsorbent that can stably adsorb heavy metals and can be recycled and regenerated to maintain high adsorption capacity.
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Figure CN121869309A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of environmental protection materials technology, specifically relating to a method for preparing acacia resin nanocomposite hydrogel. Background Technology
[0002] With the development of industries such as electroplating, leather making, corrosion prevention, and dyeing, the harm of heavy metal-containing wastewater to human health and the environment is becoming increasingly serious, attracting widespread attention. How to effectively remove heavy metals from industrial wastewater is a crucial issue related to human health and the ecological environment. Adsorption methods are widely welcomed due to their advantages such as convenient operation, excellent performance, the ability to use large quantities of cost-effective materials as adsorbents, and high regeneration efficiency. Among them, biopolymer adsorbents, with their abundant natural resources, diverse varieties, low cost, economic efficiency, minimal environmental impact, good stability, high reusability, and strong adsorption capacity, have been widely used as eco-friendly adsorbents for removing pollutants from water bodies.
[0003] Existing technologies utilize various gums for the preparation of polysaccharide-based adsorbents. Natural polymers such as guar gum, xanthan gum, and tragacanth gum possess excellent hydrogel-forming capabilities, facilitating the construction of gel-based hydrogels. This hydrogel is a three-dimensional homopolymer or copolymer network compound. This highly swellable, highly absorbent, insoluble, and shape-flexible soft wet material allows metal ions to diffuse into its three-dimensional network, thereby stimulating the interaction between metal ions diffused from polluted water and the functional groups on the hydrogel surface. Acacia gum, also known as gum arabic, is extracted from specific acacia tree species. Depending on the source, its chemical and physical properties and the percentage composition of its components can vary. Generally, this compound is 97% polysaccharide, with a small portion, approximately 3%, composed of proteins. The backbone of this natural polymer consists of galactoses linked by β(1,3)-glycosidic bonds. The side chains mostly consist of 2-5 β-(1,3)-galactose units linked by β-glycosidic bonds to form chains. In addition to galactose, glucuronic acid, rhamnose, arabinose, and methylglucuronic acid monomers are also present in the main chain and branches.
[0004] Acacia gum is a complex neutral or slightly acidic compound, typically composed of acidic salts of calcium, magnesium, and potassium, thus exhibiting strong solubility in water. Due to its excellent physicochemical and structural properties, this heteropolysaccharide has found wide application in various industries. Its emulsifying, thickening, and stabilizing abilities make it widely used in the food sector, such as in beverage, syrup, jelly, soft drink, and ice cream formulations, and it is also used in the textile industry, printing, pharmaceuticals, and cosmeceuticals. As mentioned earlier, natural polymer-based hydrogel adsorbents offer significant advantages, while the adsorption capacity of these unmodified adsorbents is unsatisfactory.
[0005] Therefore, there is an urgent need to find a technical solution to modify acacia resin in order to obtain a highly efficient adsorbent with high adsorption capacity and high stability. Summary of the Invention
[0006] To overcome the shortcomings of the prior art, the present invention provides a method for preparing acacia resin nanocomposite hydrogel, so as to solve the problem that the adsorption capacity of unmodified acacia resin in the prior art is not satisfactory.
[0007] This invention provides a method for preparing acacia resin nanocomposite hydrogel, comprising the following steps:
[0008] S1. Preparation of CuFe2O4 magnetic nanoparticles using a coprecipitation method;
[0009] S2. Add acacia resin aqueous solution, crosslinking agent, free radical initiator and acrylonitrile to CuFe2O4 nanoparticles to obtain intermediate product;
[0010] S3. Under alkaline conditions, hydroxylamine hydrochloride solution is mixed with the intermediate product and heated to obtain the acacia resin nanocomposite hydrogel.
[0011] In the above technical solution, in the presence of CuFe2O4 magnetic nanoparticles, polyacrylonitrile is grafted onto the polymer chain of acacia resin, and then the prepared magnetic hydrogel is treated with hydroxylamine hydrochloride to convert the nitrile group into an amide oxime group as a bidentate ligand, which can form a stable complex with metal ions. The resulting acacia resin nanocomposite hydrogel combines the characteristics of natural polymers, synthetic polymers and inorganic nanoparticles, and becomes an effective adsorbent for adsorbing heavy metals in aqueous solution.
[0012] Furthermore, the preparation method of the CuFe2O4 magnetic nanoparticles includes the following steps:
[0013] Iron and copper salts were dissolved in water and heated in a water bath with stirring to 85-95°C for 40-50 minutes. An alkaline solution was then added dropwise while stirring vigorously. The reaction continued for 1.5-2 hours. The brownish-black precipitate was collected with a magnet and washed repeatedly with water and acetone to remove excess reagents. The precipitate was then dried in an oven at 80-90°C for 5-6 hours to obtain CuFe2O4 magnetic nanoparticles.
[0014] Furthermore, the mass ratio of the iron salt to the copper salt is 1.15-2:1-1.5.
[0015] Furthermore, the free radical initiator is selected from either ammonium persulfate or potassium persulfate.
[0016] Preferably, the free radical initiator is ammonium persulfate.
[0017] Furthermore, the crosslinking agent is selected from N,N'-methylenebisacrylamide.
[0018] Furthermore, the iron salt is selected from any one of Fe(NO3)3·9H2O, FeCl3·6H2O, and FeSO4·9H2O.
[0019] Preferably, the iron salt is ferric nitrate.
[0020] Furthermore, the copper salt is selected from any one of Fe(NO3)3·9H2O, CuCl2·2H2O, and CuSO4·5H2O.
[0021] Furthermore, the alkaline solution is selected from either sodium hydroxide solution or potassium hydroxide solution.
[0022] Preferably, the alkaline solution is a sodium hydroxide solution.
[0023] Furthermore, the hydroxylamine hydrochloride solution is a hydroxylamine hydrochloride methanol solution.
[0024] Further, the hydroxylamine hydrochloride methanol solution is 3-5 mmol of hydroxylamine hydrochloride dissolved in 100-150 mL of methanol aqueous solution.
[0025] Furthermore, the steps are specifically as follows:
[0026] Acacia resin aqueous solution was prepared by dissolving acacia resin in distilled water. The mixture was stirred at 50-60℃ for 30-60 min, and then the acacia resin aqueous solution was stripped with N2 for 15-20 min. Then, a catalytic amount of free radical initiator was added, and the reaction was carried out for 40-50 min. Acrylonitrile was added, and the reaction was stirred at 50-60℃ for 40-60 min. Then, CuFe2O4 nanoparticles and N,N'-methylenebisacrylamide were added, and the reaction was continued at 50-60℃ for 16-20 h. The mixture was precipitated in acetone, collected with a magnet, and then washed alternately with water and acetone. The mixture was then dried at room temperature in a vacuum oven to obtain the intermediate product.
[0027] Hydroxylamine hydrochloride methanol solution and NaOH solution were added to the intermediate product for reaction. The reaction was carried out under vigorous stirring at 50-60℃ for about 16-18 hours. The mixture after reaction was precipitated in acetone, washed repeatedly with water to remove unreacted reagents and salts, and then dried in a vacuum oven at room temperature to obtain acacia resin nanocomposite hydrogel.
[0028] Furthermore, the pH of the alkaline conditions is 7-12.
[0029] Furthermore, the mass ratio of the acacia resin aqueous solution, acrylonitrile, CuFe2O4 nanoparticles, and crosslinking agent is 1-2:4-6:1-2:1.5-3.
[0030] Furthermore, the mass ratio of the hydroxylamine hydrochloride solution to the intermediate product is 1-1.5:2.5-3.
[0031] The method for preparing acacia resin nanocomposite hydrogel provided by this invention has the following beneficial effects:
[0032] 1. The method for preparing acacia resin nanocomposite hydrogel of the present invention is simple, easy to control, mild, and uses readily available raw materials, and is eco-friendly.
[0033] 2. The acacia resin nanocomposite hydrogel of the present invention combines the characteristics of natural polymers, synthetic polymers and inorganic nanoparticles, and is an effective adsorbent for removing heavy metals from aqueous solutions. The magnetic hydrogel prepared by treating it with hydroxylamine hydrochloride converts the nitrile groups into amide oxime groups as bidentate ligands, which is beneficial for forming chelates with metal ions. The presence of CuFe2O4 in the acacia resin nanocomposite hydrogel network makes it possible to recycle the magnetic hydrogel, which can be easily removed from the aqueous solution and regenerated. After three consecutive cycles, it still has a high heavy metal adsorption capacity. Attached Figure Description
[0034] Figure 1 This is a diagram illustrating the preparation process of acacia resin nanocomposite hydrogels.
[0035] Figure 2 a is a SEM image of the acacia resin nanocomposite hydrogel on a 2μm scale;
[0036] Figure 2 b is a SEM image of the acacia resin nanocomposite hydrogel on a 1μm scale.
[0037] Figure 3 The adsorption capacity of Pb(II) by the acacia resin nanocomposite hydrogel in Example 1 is shown. Detailed Implementation
[0038] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.
[0039] Acacia resin, ammonium persulfate, acrylonitrile, N,N'-methylenebisacrylamide, Fe(NO3)3·9H2O, FeCl3·6H2O, FeSO4·9H2O, Cu(NO3)2·3H2O, CuCl2·2H2O, CuSO4·5H2O, NaOH, acetone, hydroxylamine hydrochloride, and methanol were all purchased from Merck.
[0040] Example 1
[0041] S1. Dissolve 0.54 g of Fe(NO3)3·9H2O and 0.24 g of Cu(NO3)2·3H2O in 25 mL of distilled water, heat and stir in a water bath to 90 °C, maintain for 40 min, add 25 mL of 4 mol / L NaOH solution dropwise under vigorous stirring, and continue the reaction for 1.5 h. Collect the brown-black precipitate with a magnet, wash repeatedly with deionized water and acetone to remove excess reagents, and then dry in an oven at 80 °C for 5 h to obtain CuFe2O4 magnetic nanoparticles.
[0042] S2. Dissolve 1g of acacia resin in 100mL of distilled water and stir at 55℃ for 30min to obtain an aqueous solution of acacia resin. Use N2 to strip the aqueous solution of acacia resin for 15min, then add a catalytic amount of ammonium persulfate solution, react for 45min, then add 6mL of acrylonitrile, stir at 55℃ for 40min, then add 1g of CuFe2O4 nanoparticles and 1.6g of crosslinking agent N,N'-methylenebisacrylamide, and continue to react at 55℃ for 20h. Precipitate the mixture after reaction in 250mL of acetone, then collect the precipitate with a magnet, wash alternately with distilled water and acetone, and dry at room temperature in a vacuum oven to obtain the intermediate product.
[0043] S3. Add 100 mL of 0.03 mol / L hydroxylamine hydrochloride methanol solution and 100 mL of 50% NaOH solution to 0.5 g of intermediate product, and react under vigorous stirring at 50 °C for about 16 h. Precipitate the mixture in acetone, wash repeatedly with distilled water to remove unreacted reagents and salts, and then dry in a vacuum oven at room temperature to obtain acacia resin nanocomposite hydrogel.
[0044] Figure 1 This is a diagram illustrating the preparation process of acacia resin nanocomposite hydrogels. Figure 2 a is a SEM image of the acacia resin nanocomposite hydrogel on a 2μm scale. Figure 2 b is a SEM image of the acacia resin nanocomposite hydrogel on a 1 μm scale. Figure 3 The adsorption capacity of Pb(II) by the acacia resin nanocomposite hydrogel in Example 1 is shown.
[0045] Example 2
[0046] S1. Dissolve 0.54 g of Fe(NO3)3·9H2O and 0.24 g of Cu(NO3)2·3H2O in 25 mL of distilled water, heat and stir in a water bath at 90 °C for 45 min, add 25 mL of 4 mol / L NaOH solution dropwise under vigorous stirring, and continue the reaction for 1.7 h. Collect the brownish-black precipitate with a magnet, wash repeatedly with deionized water and acetone to remove excess reagents, and then dry in an oven at 85 °C for 5.5 h to obtain CuFe2O4 magnetic nanoparticles.
[0047] S2. Dissolve 1.5g of acacia resin in 100mL of distilled water and stir at 55℃ for 40min to obtain an aqueous solution of acacia resin. Use N2 to strip the aqueous solution of acacia resin for 20min, then add a catalytic amount of ammonium persulfate solution and react for 50min. Then add 6mL of acrylonitrile and stir at 55℃ for 50min. Then add 1.5g of CuFe2O4 nanoparticles and 2g of crosslinking agent N,N'-methylenebisacrylamide and continue to react at 55℃ for 20h. Precipitate the mixture after reaction in 250mL of acetone, collect the precipitate with a magnet, wash alternately with distilled water and acetone, and dry at room temperature in a vacuum oven to obtain the intermediate product.
[0048] S3. Add 100 mL of 0.03 mol / L hydroxylamine hydrochloride methanol solution and 100 mL of 50% NaOH solution to 0.5 g of intermediate product, and react under vigorous stirring at 55 °C for about 17 h. Precipitate the mixture in acetone, wash repeatedly with distilled water to remove unreacted reagents and salts, and then dry in a vacuum oven at room temperature to obtain acacia resin nanocomposite hydrogel.
[0049] Example 3
[0050] S1. Dissolve 0.36 g of FeCl3·6H2O and 0.17 g of CuCl2·2H2O in 25 mL of distilled water, heat and stir in a water bath to 90 °C for 50 min, add 25 mL of 4 mol / L NaOH solution dropwise under vigorous stirring, and continue the reaction for 2 h. Collect the brownish-black precipitate with a magnet, wash repeatedly with deionized water and acetone to remove excess reagents, and then dry in an oven at 90 °C for 6 h to obtain CuFe2O4 magnetic nanoparticles.
[0051] S2. Dissolve 1g of acacia resin in 100mL of distilled water and stir at 60℃ for 30min to obtain an aqueous solution of acacia resin. Use N2 to strip the aqueous solution of acacia resin for 20min, then add a catalytic amount of ammonium persulfate solution and react for 50min. Then add 6mL of acrylonitrile and stir at 60℃ for 40min. Then add 1g of CuFe2O4 nanoparticles and 2g of crosslinking agent N,N'-methylenebisacrylamide, and continue to react at 60℃ for 20h. Precipitate the mixture after reaction in 200mL of acetone, collect the precipitate with a magnet, wash alternately with distilled water and acetone, and dry at room temperature in a vacuum oven to obtain the intermediate product.
[0052] S3. Add 100 mL of 0.03 mol / L hydroxylamine hydrochloride methanol solution and 100 mL of 50% NaOH solution to 0.5 g of intermediate product, and react under vigorous stirring at 60 °C for about 18 h. Precipitate the mixture in acetone, wash repeatedly with distilled water to remove unreacted reagents and salts, and then dry in a vacuum oven at room temperature to obtain acacia resin nanocomposite hydrogel.
[0053] Comparative Example 1
[0054] A hydrogel, the difference between this comparative example and Example 1 is that the preparation of CuFe2O4 magnetic nanoparticles is not carried out, but the intermediate product is directly prepared, and then the acacia resin nanocomposite hydrogel is prepared.
[0055] Test Example 1
[0056] Adsorption capacity test
[0057] Test method:
[0058] The adsorption capacity of the acacia resin nanocomposite hydrogels prepared in Example 1 and Comparative Example 1 was tested, and the specific test methods are as follows:
[0059] Take 10 mg of the acacia resin nanocomposite hydrogel prepared in Example 1 and Comparative Example 1, and place it in a Pb(II)-containing water body, wherein the Pb(II) concentration is 100 mg / L, the water temperature is 25℃, and the pH is set to 4, 6, 8, and 10 respectively.
[0060] The test results are shown in Table 1:
[0061] Table 1. Pb(II) adsorption capacity (mg / g) test results for Example 1 and Comparative Example 1
[0062]
[0063]
[0064] Test Example 2
[0065] The adsorption capacity of the acacia resin nanocomposite hydrogels of Example 1 and Comparative Example 1 after 3 consecutive cycles.
[0066] Table 2 Adsorption capacity test after 3 consecutive cycles for Example 1 and Comparative Example 1
[0067] sample Example 1 Comparative Example 1 Pb(II) adsorption percentage 93.98％ 53.25％
[0068] According to Table 1-2, the adsorption capacity of the acacia gum nanocomposite hydrogel prepared in Example 1 of the present invention is above 115 mg / g compared with the hydrogel of Comparative Example 1. This is because the CuFe2O4 magnetic nanoparticles have a significant affinity for the Pb(II) complex formed, and the adsorption capacity is also high at different pH values.
[0069] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
[0070] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for preparing acacia resin nanocomposite hydrogel, characterized in that, Includes the following steps: S1. Preparation of CuFe2O4 magnetic nanoparticles using a coprecipitation method; S2. Add acacia resin aqueous solution, crosslinking agent, free radical initiator and acrylonitrile to CuFe2O4 nanoparticles to obtain intermediate product; S3. Under alkaline conditions, hydroxylamine hydrochloride solution is mixed with the intermediate product and heated to obtain the acacia resin nanocomposite hydrogel.
2. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 1, characterized in that, The mass ratio of acacia resin, acrylonitrile, CuFe2O4 nanoparticles, and crosslinking agent is 1-2:4-6:1-2:1.5-3.
3. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 2, characterized in that, The preparation method of the CuFe2O4 magnetic nanoparticles includes the following steps: Iron and copper salts were dissolved in water, an alkaline solution was added, and the mixture was heated to react, yielding CuFe2O4 magnetic nanoparticles.
4. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 3, characterized in that, The mass ratio of the iron salt to the copper salt is 1.15-2:1-1.
5.
5. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 3, characterized in that, The iron salt is selected from any one of Fe(NO3)3·9H2O, FeCl3·6H2O, and FeSO4·9H2O.
6. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 3, characterized in that, The copper salt is selected from any one of Fe(NO3)3·9H2O, CuCl2·2H2O, and CuSO4·5H2O.
7. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 2, characterized in that, The free radical initiator is selected from either ammonium persulfate or potassium persulfate.
8. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 2, characterized in that, The crosslinking agent is selected from N,N'-methylenebisacrylamide.
9. The preparation method of the acacia resin nanocomposite hydrogel as described in claim 1, characterized in that, In step S2, the pH of the alkaline conditions is 7-12.
10. The method for preparing the acacia resin nanocomposite hydrogel as described in claim 1, characterized in that, In step S2, the mass ratio of the hydroxylamine hydrochloride solution to the intermediate product is 1-1.5:2.5-3.