Synthetic method of xanthan gum-polyethyleneimine composite sponge and application of xanthan gum-polyethyleneimine composite sponge in adsorption of heavy metal ions
Through the cross-linking reaction of xanthan gum and polyethyleneimine composite sponge, a three-dimensional network structure is formed, which solves the problem of insufficient adsorption capacity and stability of existing adsorption materials, and achieves efficient and economical heavy metal ion adsorption and regeneration treatment.
Patent Information
- Application Number
- CN202510560253.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-07-11
AI Technical Summary
When removing heavy metal ions, existing adsorption materials have problems such as limited adsorption capacity, poor selectivity, insufficient stability, complex synthesis process and high cost, making it difficult to achieve efficient and economical large-scale industrial production.
Xanthan gum is combined with polyethyleneimine, and a three-dimensional network structure is formed through cross-linking reaction. The active groups of the two are combined with heavy metal ions to form stable complexing and coordination bonds, enhancing adsorption capacity, and adding epoxypropane as a cross-linking agent to enhance mechanical properties and chemical stability.
It improves the adsorption capacity and selectivity of the composite sponge, ensures stability in an acid-base environment, reduces production costs, realizes multiple reuses and simple regeneration, and is suitable for efficient adsorption of a variety of heavy metal ions.
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Figure CN120285960A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of adsorption materials, and particularly relates to a synthesis method of xanthan gum - polyethyleneimine composite sponge and its application in adsorbing heavy metal ions. Background Art
[0002] Heavy metal ions such as lead, mercury, cadmium, chromium, etc. are characterized by high toxicity, difficult degradation, easy enrichment in organisms, etc., posing a great threat to the ecological environment and human health. Therefore, the efficient removal of heavy metal ions from water has become the focus of research in the environmental field.
[0003] At present, the adsorption method has been widely used in the removal of heavy metal ions due to its advantages such as simple operation, low cost, good treatment effect, etc. In terms of adsorption materials, traditional adsorbents such as activated carbon, ion exchange resins, etc. have certain adsorption capacities for heavy metal ions, but they have disadvantages such as limited adsorption capacity, poor selectivity, and difficult regeneration. In recent years, the research and development of new adsorption materials have received extensive attention. For example, some inorganic adsorbents such as montmorillonite, zeolite, etc. have certain adsorption effects on heavy metal ions by utilizing their special crystal structures, but their adsorption performances are often greatly affected by environmental conditions such as pH value, temperature, etc. And organic polymer adsorbents, although having high adsorption capacity and selectivity, some adsorbents have complex synthesis processes, and some materials may have problems such as poor biocompatibility and easy secondary pollution.
[0004] For bio - based adsorption materials, xanthan gum (XG), as a natural polymer polysaccharide, has a wide source, low price, and good biocompatibility. Its molecular structure contains a large number of active groups such as hydroxyl groups and carboxyl groups, and theoretically has the ability to complex heavy metal ions, but its mechanical properties are poor, it is not acid - resistant, and it is easy to lose during the adsorption process when used alone, which limits its practical application. Polyethyleneimine (PEI) contains a large number of amino groups and has good complexing ability for heavy metal ions, but also has problems such as insufficient stability. Therefore, how to combine the advantages of the two to develop an efficient, stable and environmentally friendly adsorption material has become a research hotspot.
[0005] In the prior art, although there have been attempts to combine natural polymers and synthetic polymers to prepare adsorption materials, most of them have problems such as complex synthesis processes, harsh conditions, high costs, etc., which are not conducive to large - scale industrial production. Moreover, in terms of how to optimize their adsorption performances after the combination of the two, and how to improve the repeated use performance of the materials, the existing research still has deficiencies. Therefore, it is of great practical significance to develop a simple, efficient and economically feasible synthesis method of xanthan gum - polyethyleneimine (XG - PEI) composite sponge and make it have excellent heavy metal ion adsorption performance. Summary of the Invention
[0006] To solve the above technical problems, the present invention provides a method for synthesizing xanthan gum-polyethyleneimine composite sponge and its application in adsorbing heavy metal ions.
[0007] To achieve the above object, the present invention provides the following technical solutions:
[0008] The present invention provides a method for synthesizing xanthan gum-polyethyleneimine composite sponge, comprising the following steps: adding a polyethyleneimine solution to a xanthan gum solution to obtain a mixed solution; adding epichlorohydrin to the mixed solution for crosslinking reaction, and drying to obtain the xanthan gum-polyethyleneimine composite sponge.
[0009] Technical principle: The present invention uses xanthan gum, polyethyleneimine and epichlorohydrin to prepare a composite sponge for adsorbing heavy metal ions. The hydroxyl and carboxyl groups in the xanthan gum molecule can undergo ion exchange and complexation reactions with heavy metal ions, and the amino group of polyethyleneimine can further form stable coordination bonds with heavy metal ions. The two work together to enhance the complexation ability of heavy metal ions, improve the adsorption capacity and selectivity of the composite sponge, and achieve efficient adsorption of various heavy metal ions; then adding a crosslinking agent, epichlorohydrin, to undergo a crosslinking reaction with xanthan gum and polyethyleneimine to construct a three-dimensional network structure, improving the mechanical properties and chemical stability of the composite sponge, ensuring a stable adsorption effect while improving its reusability.
[0010] Further, the mass concentration of the polyethyleneimine solution is 50%.
[0011] Further, the volume ratio of the polyethyleneimine solution to the mass of xanthan gum in the xanthan gum solution is (1.5 - 3) mL∶0.3 g.
[0012] Further, the volume ratio of epichlorohydrin to the polyethyleneimine solution is 1∶(1 - 2.5).
[0013] Further, the temperature of the crosslinking reaction is room temperature, and the time is 3 - 4 hours.
[0014] Further, the drying is freeze-drying; the temperature of the freeze-drying is -70°C, the number of freeze-drying times is 3 times, and the time of each freeze-drying is 12 h.
[0015] Further, the preparation method of the xanthan gum solution is: sprinkling xanthan gum into water to obtain a mixed solution; stirring the obtained mixed solution at 60°C for 30 minutes to obtain the xanthan gum solution.
[0016] Further, the molecular weight of polyethyleneimine in the polyethyleneimine solution is 70000.
[0017] The present invention provides a xanthan gum - polyethyleneimine composite sponge synthesized by the synthesis method described in the above technical solution.
[0018] The present invention also provides the application of the xanthan gum - polyethyleneimine composite sponge described in the above technical solution in adsorbing heavy metal ions.
[0019] Compared with the prior art, the present invention has the following advantages and technical effects:
[0020] In the present invention, by combining xanthan gum with polyethyleneimine, and utilizing the rich active groups of xanthan gum and the large number of amino groups contained in polyethyleneimine, the two act synergistically to enhance the complexing ability of the composite sponge for heavy metal ions, and improve the adsorption capacity and selectivity of the composite sponge. The hydroxyl and carboxyl groups in xanthan gum can undergo ion exchange and complexation reactions with heavy metal ions, and the amino groups of polyethyleneimine can further form stable coordination bonds with heavy metal ions, thereby realizing the efficient adsorption of various heavy metal ions and solving the problems of limited adsorption capacity and poor selectivity of traditional adsorption materials.
[0021] In the present invention, by adding epichlorohydrin as a cross - linker to carry out cross - linking reactions with xanthan gum and polyethyleneimine to construct a three - dimensional network structure, the mechanical properties and chemical stability of the composite sponge are improved. During the adsorption process, the composite sponge can resist changes in the acid - base environment, is not easily broken and lost, ensuring a stable adsorption effect, and solving the problem of insufficient stability when xanthan gum and polyethyleneimine are used alone.
[0022] The synthesis method of the present invention is simple to operate and has mild reaction conditions. Xanthan gum can be fully dissolved in water by simply stirring, then the polyethyleneimine solution is added and stirred evenly, and then the cross - linker epichlorohydrin is added and stirred at room temperature for cross - linking, and then the composite sponge can be obtained after drying. The whole process does not require special equipment and harsh conditions. The raw material xanthan gum has a wide source and low price, and polyethyleneimine is also a common chemical raw material, effectively reducing the production cost and solving the problems of complex process and high cost in the preparation of adsorption materials by combining natural polymers and synthetic polymers.
[0023] Due to the stable three - dimensional network structure of the composite sponge synthesized by the present invention, during multiple adsorption - desorption cycles, the structure and performance are not easily damaged, and a high number of repeated uses can be achieved. And after adsorbing heavy metal ions, the heavy metal ions can be removed by a simple elution method to restore the adsorption performance, further reducing the use cost and solving the problems of difficult regeneration of traditional adsorbents and limited repeated use. Brief Description of the Drawings
[0024] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:
[0025] Figure 1 Finished product diagram of the xanthan gum - polyethyleneimine composite sponge prepared for Example 2;
[0026] Figure 2 Physical diagram of the xanthan gum - polyethyleneimine composite sponge prepared for Example 2 in water (left) and after soaking in water (right);
[0027] Figure 3 Physical diagram of the xanthan gum - polyethyleneimine composite sponges prepared for Examples 1 - 2 and Comparative Examples 1 - 7;
[0028] Figure 4 Physical diagram of the xanthan gum - polyethyleneimine composite sponges prepared for Examples 2 - 6 and Comparative Examples 8 - 9;
[0029] Figure 5 Adsorption effect diagram of the composite sponge in Examples 2 - 6;
[0030] Figure 6 Adsorption effect diagram of the composite sponge in Example 5 under different pH conditions;
[0031] Figure 7 Adsorption effect diagram of the composite sponge in Example 5 for different metal ions;
[0032] Figure 8 Cyclic stable adsorption effect diagram of the composite sponge in Example 5. Detailed implementation manners
[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.
[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.
[0035] The embodiments of the present invention provide a synthesis method of a xanthan gum - polyethyleneimine composite sponge, including the following steps: adding a polyethyleneimine solution to a xanthan gum solution to obtain a mixed solution; adding epichlorohydrin to the mixed solution for cross - linking reaction, and drying to obtain the xanthan gum - polyethyleneimine composite sponge.
[0036] In a preferred embodiment, the method for preparing the xanthan gum solution is as follows: sprinkle xanthan gum into water to obtain a mixed solution; stir the obtained mixed solution at 60 °C for 30 minutes to obtain the xanthan gum solution; the stirring method is magnetic stirring. Stirring at 60 °C can enable it to dissolve quickly to form a homogeneous solution without overly damaging the molecular structure of xanthan gum; controlling the stirring speed can ensure the uniform dispersion of xanthan gum and improve the dissolution efficiency.
[0037] In a preferred embodiment, the xanthan gum selected is food-grade or industrial-grade xanthan gum to ensure its purity and quality stability. The purity and quality of xanthan gum have an important impact on the performance of the final product. Excessive impurities may interfere with the reaction process or reduce the adsorption performance of the composite sponge. As a natural polymer, xanthan gum has good biodegradability and will not cause long-term pollution to the environment. During the synthesis and use of the composite sponge, no toxic or harmful by-products are generated. Moreover, after the composite sponge is saturated with adsorption, it can be reused multiple times through simple elution and regeneration treatments, reducing the generation of adsorption material waste, conforming to the environmental protection concept of sustainable development, and having a positive significance for environmental protection.
[0038] In a preferred embodiment, the mass concentration of the polyethyleneimine solution is 50%.
[0039] In a preferred embodiment, the molecular weight of the polyethyleneimine in the polyethyleneimine solution is 70,000 to ensure the solubility of polyethyleneimine in the solution and its reaction activity with xanthan gum.
[0040] In a preferred embodiment, the volume ratio of the polyethyleneimine solution to the mass of xanthan gum in the xanthan gum solution is (1.5 - 3) mL∶0.3 g, and more preferably (2 - 3) mL∶0.3 g. In the present invention, the dosage ratio of the polyethyleneimine solution to xanthan gum is controlled within the above range, giving full play to the synergistic adsorption effect of the two, while ensuring the smooth progress of the subsequent reaction, which is beneficial to obtaining a composite sponge with good performance.
[0041] In a preferred embodiment, the polyethyleneimine solution is added to the xanthan gum solution and stirred to obtain a mixed solution; the stirring temperature is room temperature and the time is 30 minutes. During the stirring process, the amino groups in the polyethyleneimine molecules start to approach and undergo physical or preliminary chemical interactions with the hydroxyl and carboxyl groups in the xanthan gum molecules, laying the foundation for the cross-linking reaction.
[0042] In a preferred embodiment, the volume ratio of epichlorohydrin to the polyethyleneimine solution is 1∶(1 - 2.5), more preferably 1∶(1 - 2), and more specifically preferably 1∶1, 1∶1.33 or 1∶1.67. By controlling the volume ratio of epichlorohydrin to the polyethyleneimine solution within the above range in the present invention, it is beneficial to form a stable three-dimensional network structure. If the amount of epichlorohydrin used is too small, the crosslinking degree is insufficient; if the amount of epichlorohydrin used is too large, the structure of the composite sponge may be too dense, affecting the adsorption performance.
[0043] In a preferred embodiment, the temperature of the crosslinking reaction is room temperature and the time is 3 - 4 hours. During the crosslinking reaction, the epoxy groups in epichlorohydrin react with the active groups on the xanthan gum and polyethyleneimine molecules to gradually form a three-dimensional network structure. Conducting the crosslinking reaction at room temperature not only saves energy but also avoids the adverse effects of high temperature on the material properties.
[0044] In a preferred embodiment, after the crosslinking reaction, it further includes pouring the reaction solution after the crosslinking reaction into a mold, then performing curing and shaping, then performing freeze-drying and washing, and repeating the freeze-drying 2 - 3 times to obtain the xanthan gum - polyethyleneimine composite sponge.
[0045] In a preferred embodiment, the shape of the mold is selected according to the shape of the required composite sponge; the shape of the mold is square or circular. When pouring the reaction solution after the crosslinking reaction into the mold, bubbles should be avoided as much as possible to ensure the uniformity of the formed composite sponge.
[0046] In a preferred embodiment, the method of curing and shaping is drying; the drying temperature is 70°C and the time is 15 minutes. 70°C can make the water evaporate slowly and at the same time promote the further curing and shaping of the crosslinked polymer to form a composite sponge semi-finished product with a certain strength and shape.
[0047] In a preferred embodiment, the temperature of the freeze-drying is -70°C, the number of times of freeze-drying is 3 times, and the time of each freeze-drying is 12 h. Freeze-drying can retain the porous structure of the composite sponge, increase the specific surface area, and enhance the adsorption performance. Repeating the freeze-drying 2 - 3 times can further remove residual moisture and impurities to ensure the purity and performance of the composite sponge.
[0048] In a preferred embodiment, the washing is specifically as follows: First, soak the composite sponge semi-finished product after freeze-drying in ethanol for 30 minutes to remove unreacted impurities and small molecule substances, and then rinse it with deionized water 3 - 5 times, with each rinse for 10 minutes until the washing liquid is neutral.
[0049] The present invention provides a xanthan gum - polyethyleneimine composite sponge synthesized by the synthesis method described in the above technical solution.
[0050] The present invention also provides the application of the xanthan gum - polyethyleneimine composite sponge described in the above technical solution in adsorbing heavy metal ions.
[0051] In a preferred embodiment, the heavy metal ions include one or both of mercury ions and lead ions.
[0052] In the embodiments of the present invention, room temperature refers to "25 ± 2 °C".
[0053] Unless otherwise specified, the raw materials in the embodiments of the present invention are all obtained through commercial channels.
[0054] In the following examples and comparative examples, xanthan gum was purchased from Adamas (Shanghai Adamas Reagent Co., Ltd.), industrial grade, 76.95 yuan / 500 g; epichlorohydrin was purchased from Adamas, 45.60 yuan / 500 g; polyethyleneimine was purchased from Adamas, with a molecular weight of 70,000, 320.37 yuan / 500 g.
[0055] Examples 1 - 2 and Comparative Examples 1 - 7
[0056] Xanthan gum (XG) was slowly sprinkled into deionized water to obtain a mixed solution; the obtained mixed solution was magnetically stirred at 60 °C for 30 minutes to fully dissolve xanthan gum, obtaining a xanthan gum solution. A 50% polyethyleneimine (PEI) solution was added to the above xanthan gum solution, stirred at room temperature for 30 minutes, and then epichlorohydrin (ECH) was added, stirred at room temperature for 4 hours, obtaining a reaction solution.
[0057] The above reaction solution was poured into a circular mold and dried and shaped in an oven at 70 °C to obtain a preliminary composite sponge; the preliminary composite sponge was taken out of the oven and placed in a freeze dryer, freeze-dried repeatedly at -70 °C for 3 times, 12 hours each time. Subsequently, the freeze-dried preliminary composite sponge was soaked in ethanol for 30 minutes, and then rinsed with deionized water 3 times, 10 minutes each time, until the cleaning solution was neutral, and then freeze-dried repeatedly 2 times to obtain the xanthan gum - polyethyleneimine composite sponge XEP;
[0058] The dosages of xanthan gum, polyethyleneimine solution, and epichlorohydrin are shown in Table 1.
[0059] Table 1 Dosages of xanthan gum, polyethyleneimine solution, and epichlorohydrin in Examples 1 - 2 and Comparative Examples 1 - 7
[0060]
[0061]
[0062] Figure 1The finished product diagram of the xanthan gum - polyethyleneimine composite sponge prepared in Example 2. From Figure 1 it can be seen that the forming effect of this composite sponge is good, without obvious cracks, and the height is about 2.2 cm.
[0063] Figure 2 The physical diagram of the xanthan gum - polyethyleneimine composite sponge prepared in Example 2 in water (left) and after soaking in water (right). From Figure 2 it can be seen that the xanthan gum - polyethyleneimine composite sponge prepared by the present invention can float in water, and the composite sponge after soaking in water becomes slightly transparent.
[0064] Weigh the weight of the xanthan gum - polyethyleneimine composite sponge prepared in Example 2 before and after water absorption, and calculate the water absorption rate using the formula water absorption rate = (m2 - m1) / m1×100%, where m1 is the weight of the composite sponge before water absorption, and m2 is the weight of the composite sponge after water absorption; after calculation, the water absorption rate of the xanthan gum - polyethyleneimine composite sponge prepared in Example 2 is 996%.
[0065] Figure 3 The physical diagram of the xanthan gum - polyethyleneimine composite sponges prepared in Examples 1 - 2 and Comparative Examples 1 - 7. From Figure 3 it can be seen that as the addition amount of xanthan gum (XG) increases, the formed substance becomes more viscous and more difficult to shape, and the substance after freeze - drying is very brittle. Among them, the a group is too thin, and the forming effect of the raw material dosage between the b group and the c group is the best. Then, the dosage of xanthan gum (XG) is selected as 0.3 g, and optimization experiments are carried out between the b group and the c group.
[0066] Examples 3 - 6 and Comparative Examples 8 - 9
[0067] The preparation process of the xanthan gum - polyethyleneimine composite sponge is the same as that of Example 1, and the dosages of xanthan gum, polyethyleneimine solution and epichlorohydrin are shown in Table 2.
[0068] Table 2 Dosages of xanthan gum, polyethyleneimine solution and epichlorohydrin in Examples 2 - 6 and Comparative Examples 8 - 9
[0069]
[0070]
[0071] Figure 4 The physical diagram of the xanthan gum - polyethyleneimine composite sponges prepared in Examples 2 - 6 and Comparative Examples 8 - 9. From Figure 4It can be seen that too much XG was added to sample XEP-1, resulting in excessive viscosity during molding; compared with sample XEP-7, sample XEP-3 had less ECH added, resulting in poor cross-linking effect and cracks; samples XEP-2, XEP-4, XEP-5, XEP-6, and XEP-7 had better molding effects.
[0072] Adsorption tests were carried out on the composite sponges in Examples 2-6. The initial concentration of lead ions was 500 mg·L -1 , pH: 5.5, the dosage of the composite sponge was 20 mg / 20 mL, the adsorption temperature was 30 °C, and the adsorption time was 1440 min. The results are shown in Figure 5 .
[0073] Figure 5 Figure is the adsorption effect diagram of the composite sponges in Examples 2-6. By comparing XEP-2 and XEP-6, it can be seen that only changing the amount of the cross-linking agent ECH will affect the adsorption performance. When the dosage of the cross-linking agent ECH is reduced by 0.5 mL, the adsorption capacity decreases from 385.89 mg / g to 371.62 mg / g. At the same time, combined with Figure 4 it can be seen that as the dosage of the cross-linking agent decreases, cracks are likely to appear on the appearance of the samples. By comparing the adsorption capacities of XEP-4, XEP-5, XEP-6, and XEP-7, it can be seen that as the amount of PEI added increases, the adsorption capacity also increases, and the adsorption capacity is the largest when 3 mL of PEI is added.
[0074] Adsorption tests were carried out on the composite sponge in Example 5. The initial concentration of lead ions was 500 mg·L -1 , pH: 1.5 - 5.5, the dosage of the composite sponge was 20 mg / 20 mL, the adsorption temperature was 30 °C, and the adsorption time was 1440 min. The results are shown in Figure 6 .
[0075] Figure 6 Figure is the adsorption effect diagram of the composite sponge in Example 5 under different pH conditions. It can be seen from Figure 6 that within the range of pH from 1.5 to 5.5, the adsorption effect of the composite sponge increases with the increase of the pH value, and the adsorption capacity is the largest when the pH value is 5.5.
[0076] Selective adsorption tests were carried out on the composite sponge in Example 5. The composite sponge in Example 5 was placed in a mixed solution containing lead ions (Pb(II)), cadmium ions (Cd(II)), copper ions (Cu(II)), and mercury ions (Hg(II)). Among them, the initial concentrations of lead ions, cadmium ions, copper ions, and mercury ions were all 500 mg·L -1 , pH: 5.5, the dosage of the composite sponge was 20 mg / 20 mL, the adsorption temperature was 30 °C, and the adsorption time was 1440 min. The results are shown in Figure 7 .
[0077] Figure 7 Adsorption effect diagrams of the composite sponge in Example 5 for different metal ions. From Figure 7 It can be seen that in the multi-component heavy metal competition system, the composite sponge XEP shows significant selective capture ability for Pb(II). Experimental data shows that its Pb(II) adsorption capacity reaches 388.32 mg / g, which is 31.4 times, 5.5 times and 1.3 times higher than that of Cd(II) (12.37 mg / g), Cu(II) (70.63 mg / g) and Hg(II) (294.56 mg / g) respectively. This shows that in a mixed solution containing multiple metal ions (such as lead, cadmium, copper, mercury, etc.), the composite sponge provided by the present invention shows high selectivity for the target heavy metal ions, greatly improving the separation and removal efficiency of the target heavy metal ions in complex wastewater, and providing a strong guarantee for subsequent heavy metal recovery and water resource purification.
[0078] The composite sponge in Example 5 was subjected to a cyclic stable adsorption test. Initial concentration of lead ions: 500 mg·L -1 , pH: 5.5, dosage of composite sponge: 20 mg / 20 mL, adsorption temperature: 30 °C, adsorption time: 1440 min; the composite sponge adsorbed with lead ions was dynamically eluted with EDTA and then used for adsorption experiments again. The results are shown in Figure 8 .
[0079] Figure 8 Adsorption effect diagrams of the composite sponge in Example 5 for cyclic stability. From Figure 8 It can be seen that the composite sponge adsorbed with Pb(II) ions can be efficiently regenerated after dynamic elution with EDTA - after 5 consecutive adsorption - desorption cycles, the adsorption rate of Pb(II) ions still remains above 80%. This result shows that the three-dimensional network structure inside the composite sponge can still remain intact under strong coordination elution conditions. It can be seen that the composite sponge provided by the present invention not only has strong adsorption ability for Pb(II), but also has good stability and reusability.
[0080] In summary, it can be seen that the adsorption capacity of the xanthan gum - polyethyleneimine composite sponge synthesized by the present invention for lead ions can reach more than 350 mg / g, which is about 2.5 times higher than the adsorption capacity of about 100 mg / g of lead ions by traditional activated carbon. For mercury ions, the adsorption capacity can reach more than 280 mg / g, far exceeding the adsorption capacity of about 150 mg / g of mercury ions by ordinary ion exchange resins. This significant increase in adsorption capacity greatly reduces the dosage of the composite sponge required when treating the same volume and concentration of heavy metal ion-containing wastewater, reducing the treatment cost.
[0081] The composite sponge exhibits good chemical stability in solutions with different pH values. This enables the composite sponge to be widely applied to various industrial wastewater treatment scenarios without the need for complex pretreatment due to the differences in the acidity and alkalinity of the wastewater, thereby expanding its practical application scope.
[0082] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims
1. A method for synthesizing xanthan gum-polyethyleneimine composite sponge, characterized in that, It includes the following steps: Add the polyethyleneimine solution to the xanthan gum solution to obtain a mixed solution; Add epichlorohydrin to the mixed solution for cross-linking reaction, and after drying, obtain the xanthan gum-polyethyleneimine composite sponge.
2. The synthesis method of the xanthan gum-polyethyleneimine composite sponge according to claim 1, characterized in that, The mass concentration of the polyethyleneimine solution is 50%.
3. The synthesis method of the xanthan gum-polyethyleneimine composite sponge according to claim 1 or 2, characterized in that, The volume ratio of the polyethyleneimine solution to the mass of xanthan gum in the xanthan gum solution is (1.5 - 3) mL∶0.3 g.
4. The synthesis method of the xanthan gum - polyethyleneimine composite sponge according to claim 1 or 2, characterized in that, The volume ratio of the epichlorohydrin to the polyethyleneimine solution is 1∶(1 - 2.5).
5. The synthesis method of the xanthan gum - polyethyleneimine composite sponge according to claim 1, characterized in that, The temperature of the cross-linking reaction is room temperature, and the time is 3 - 4 hours.
6. The synthesis method of the xanthan gum-polyethyleneimine composite sponge according to claim 1, characterized in that, The drying is freeze-drying; the temperature of the freeze-drying is -70 °C, the number of freeze-drying times is 3 times, and the time of each freeze-drying is 12 h.
7. The synthesis method of the xanthan gum-polyethyleneimine composite sponge according to claim 1, wherein, The preparation method of the xanthan gum solution is as follows: sprinkle xanthan gum into water to obtain a mixed solution; stir the obtained mixed solution at 60 °C for 30 minutes to obtain the xanthan gum solution.
8. The synthesis method of the xanthan gum - polyethyleneimine composite sponge according to claim 1, characterized in that The molecular weight of polyethyleneimine in the polyethyleneimine solution is 70000.
9. A xanthan gum-polyethyleneimine composite sponge synthesized by the synthesis method according to any one of claims 1 to 8.
10. Use of the xanthan gum-polyethyleneimine composite sponge according to claim 9 in adsorbing heavy metal ions.