A lignin-doped montmorillonite hydrogel, and a preparation method and application thereof

Abstract

The present application relates to a kind of lignin doped montmorillonite hydrogel and its preparation method and application, belong to functional material field.A kind of lignin doped montmorillonite hydrogel preparation method, in the aqueous solution of aminated lignin, montmorillonite k-10 is sequentially added, methacryloyloxyethyl trimethylammonium chloride, acrylic acid, acrylamide, N, N-methylene bisacrylamide and potassium persulfate, stirring is uniform, carries out free radical polymerization, the product obtained is soaked in deionized water, and lignin doped montmorillonite hydrogel is obtained.The method for preparing lignin doped montmorillonite hydrogel of the present application is one-step method, process is simple, production cost is low, more suitable for large-scale industrial use.The lignin doped montmorillonite hydrogel prepared in the present application contains abundant active sites, has strong adsorption capacity to nitrogen and phosphorus ions and microplastics, and can simultaneously adsorb nitrogen and phosphorus ions and microplastics.

Description

Technical Field

[0001] This invention relates to a lignin-doped montmorillonite hydrogel, its preparation method and application, belonging to the field of functional materials. Background Technology

[0002] Nitrogen and phosphorus are essential elements for the survival of all living things in nature. However, the long-term discharge of various nitrogen- and phosphorus-containing wastewaters from industrial and agricultural production has caused severe eutrophication of natural water bodies, thereby seriously damaging aquatic ecosystems. Therefore, the efficient removal and recycling of nitrogen and phosphorus pollutants in water bodies has become crucial for solving the current problems of eutrophic water body management and the sustainable utilization of nitrogen and phosphorus resources. Similarly, with the widespread use of plastic products, microplastics are widely present in environmental media and organisms globally. They have wide sources, widespread distribution, complex environmental behavior, and potential ecotoxicological effects, posing a serious threat to ecosystems and human health. Therefore, achieving the efficient removal and recycling of microplastics in wastewater containing microplastics is of paramount importance.

[0003] Hydrogels are considered a potential candidate material for wastewater treatment, in addition to traditional adsorbents such as zeolites, clay minerals, synthetic resins, and activated carbon. Generally, hydrogels possess good hydrophilicity, a large specific surface area, and numerous porous structures and active adsorption groups or sites, ultimately leading to strong interactions between pollutant ions and these sites, thereby improving the removal efficiency of pollutants from wastewater. Natural polymers in biomass, such as lignin, cellulose, and chitosan, are widely used as raw materials for hydrogel preparation due to their abundance, environmental friendliness, and biodegradability, thus endowing hydrogels with favorable environmental properties.

[0004] Lignin, a major chemical component widely found in plants, is a three-dimensional network of natural polymers with an aromatic structure. Simultaneously, the lignin structure contains numerous active functional groups, such as carboxyl, phenolic, and aliphatic hydroxyl groups, making it easy to process into hydrogels or endowing lignin materials with limited adsorption capacity. Lignin is considered an ideal polymer for preparing hydrogels because utilizing hydrogels not only brings high value to lignin but also helps reduce costs and improve the mechanical properties of hydrogels. Furthermore, it has been confirmed that eutrophic wastewater often contains pollutants such as anions, cations, and microplastics. Lignin-doped hydrogel adsorbents containing only one type of ionic group cannot remove all pollutants, thus failing to meet practical application needs. Therefore, the preparation of multi-component lignin-doped montmorillonite hydrogels for the simultaneous recovery of nitrogen, phosphorus, and microplastics from wastewater is of great significance.

[0005] However, early methods for preparing amphoteric lignin-based hydrogels were complex, typically requiring two or more synthetic steps. First, water-soluble lignin derivatives were synthesized from lignin. Then, these lignin derivatives were modified to introduce different functional groups, resulting in the amphoteric lignin-based hydrogel. This complex synthetic process hindered the large-scale industrial application of amphoteric lignin-based hydrogels. Therefore, a simple and convenient synthetic method for preparing amphoteric lignin-based hydrogels was needed. This invention utilizes a one-step chemical modification process to prepare an environmentally friendly, efficient, stable, and economical lignin-doped montmorillonite hydrogel for the efficient removal of nitrogen and phosphorus ions and microplastics from water. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies in the preparation of pollutant-adsorbing materials by providing a lignin-doped montmorillonite hydrogel, its preparation method, and its applications. This invention uses amination-modified lignin as a raw material, montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, and acrylamide as monomers, and potassium persulfate as an initiator. N, N Using methylenebisacrylamide as a crosslinking agent, lignin-doped montmorillonite hydrogels capable of adsorbing nitrogen and phosphorus ions and microplastic pollutants were prepared through free radical polymerization. This process has low production costs and promising application prospects.

[0007] A method for preparing lignin-doped montmorillonite hydrogels involves sequentially adding montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, and acrylamide to an aqueous solution of aminated lignin. N, N Methylenebisacrylamide and potassium persulfate were stirred evenly and subjected to free radical polymerization. The resulting product was then soaked in deionized water to obtain lignin-doped montmorillonite hydrogel.

[0008] In the method of the present invention, the mass-to-volume ratio of aminated lignin to deionized water in the aminated lignin aqueous solution is 0.15 g : 5~15 mL.

[0009] Preferably, the mass-to-volume ratio of aminated lignin to deionized water in the aminated lignin aqueous solution is 0.15 g: 7 mL.

[0010] In the method described in this invention, the aminated lignin, montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, acrylamide, N, N The mass ratio of methylenebisacrylamide to potassium persulfate is 0.15 g : 0.5~1.5 g : 1.0~3.0 g : 1.0~3.0 g : 0.5~1.5 g : 0.01~0.09 g : 0.01~0.03 g.

[0011] Preferably, the aminated lignin, montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, and acrylamide are... N, N The ratio of methylenebisacrylamide to potassium persulfate is 0.15 g : 1.0 g : 2.5 g : 2.5 g : 1.0 g : 0.06 g : 0.02 g.

[0012] In the method described in this invention, the stirring conditions are magnetic stirring at 200-600 rpm for 10-30 min.

[0013] In the method described in this invention, the free radical polymerization reaction conditions are 40~80℃ for 1~3 h.

[0014] Preferably, the free radical polymerization reaction is carried out at a temperature of 60°C for 2 hours.

[0015] Furthermore, the free radical polymerization reaction is carried out in an oven.

[0016] In the method of the present invention, the product is soaked in deionized water for 20-40 hours.

[0017] Preferably, the product is soaked in deionized water for 24 hours.

[0018] Another object of the present invention is to provide a lignin-doped montmorillonite hydrogel prepared by the above method.

[0019] Another object of the present invention is to provide the application of the above-mentioned lignin-doped montmorillonite hydrogel in the adsorption of nitrogen and / or phosphorus ions and / or microplastics.

[0020] Furthermore, the application of the lignin-doped montmorillonite hydrogel in adsorbing nitrogen and / or phosphorus ions and / or microplastics can be divided into four cases: first, the application of lignin-doped montmorillonite hydrogel in adsorbing nitrogen ions; second, the application of lignin-doped montmorillonite hydrogel in adsorbing phosphorus ions; third, the application of lignin-doped montmorillonite hydrogel in adsorbing microplastics; and fourth, the application of lignin-doped montmorillonite hydrogel in simultaneously adsorbing nitrogen and phosphorus ions and microplastics.

[0021] Furthermore, the specific process for applying the lignin-doped montmorillonite hydrogel in adsorbing nitrogen and / or phosphorus ions and / or microplastics is as follows: the lignin-doped montmorillonite hydrogel is mixed with an aqueous solution of nitrogen and / or phosphorus ions and / or microplastics, and adsorption is carried out in a shaker. After the adsorption is completed, the mixture is filtered, and the resulting solid sample is the lignin-doped hydrogel after adsorbing nitrogen and / or phosphorus ions and / or microplastics.

[0022] Preferably, the lignin-doped montmorillonite hydrogel is used in the simultaneous adsorption of nitrogen and phosphorus ions and microplastics.

[0023] In the above technical solution, the adsorption conditions are adsorption at 100-200 rpm for 10-600 min at a temperature of 20-40℃.

[0024] Preferably, the adsorption conditions are adsorption at 25°C and 150 rpm for 300 min.

[0025] In the above technical solution, the nitrogen ion aqueous solution is one or more of ammonium chloride solution, ammonium sulfate solution and ammonium nitrate solution.

[0026] In the above technical solution, the concentration of the nitrogen ion aqueous solution is 10~200 mg N / L.

[0027] Preferably, the concentration of the nitrogen ion aqueous solution is 100 mg N / L.

[0028] More preferably, the nitrogen ion aqueous solution is an ammonium chloride solution.

[0029] In the above technical solution, the phosphate ion aqueous solution is one or more of potassium dihydrogen phosphate solution, dipotassium hydrogen phosphate solution, and sodium dihydrogen phosphate solution.

[0030] In the above technical solution, the concentration of the phosphorus ion aqueous solution is 10~200 mgP / L.

[0031] Preferably, the concentration of the phosphorus ion aqueous solution is 200 mg P / L.

[0032] More preferably, the phosphorus ion aqueous solution is a potassium dihydrogen phosphate solution.

[0033] In the above technical solution, the microplastic aqueous solution is one or more of polystyrene solution, polypropylene solution and polyethylene solution.

[0034] In the above technical solution, the concentration of the microplastic aqueous solution is 100~1000 mg / L.

[0035] Preferably, the concentration of the polystyrene aqueous solution is 800 mg / L.

[0036] More preferably, the microplastic aqueous solution is a polystyrene solution.

[0037] In the above technical solution, the nitrogen and phosphorus ion and microplastic mixed solution is obtained by dissolving nitrogen-containing substances, phosphorus-containing substances and microplastics in deionized water and stirring them evenly.

[0038] Preferably, the nitrogen and phosphorus ion and microplastic mixed solution is obtained by dissolving ammonium chloride, potassium dihydrogen phosphate and polystyrene in deionized water and stirring until homogeneous.

[0039] Furthermore, the concentration of nitrogen ions in the nitrogen-phosphorus ion and microplastic mixed solution is 10-200 mg N / L, the concentration of phosphorus ions is 10-200 mg P / L, and the concentration of microplastics is 100-1000 mg / L.

[0040] Preferably, the nitrogen ion concentration in the nitrogen-phosphorus ion mixed solution is 100 mg N / L, the phosphorus ion concentration is 100 mg P / L, and the microplastic concentration is 1000 mg / L.

[0041] In the above technical solution, the mass-to-volume ratio of the lignin-doped montmorillonite hydrogel to the aqueous solution of nitrogen and / or phosphorus ions and / or microplastics is 0.05 g : 10~100 mL.

[0042] Preferably, the mass-to-volume ratio of the lignin-doped montmorillonite hydrogel to the aqueous solution of nitrogen and / or phosphorus ions and / or microplastics is 0.05 g : 50 mL.

[0043] The beneficial effects of this invention are:

[0044] 1. The method used in this invention to prepare lignin-doped montmorillonite hydrogel is a one-step preparation method. Compared with two-step or multi-step methods, the one-step method is simpler, has lower production costs, and is more suitable for large-scale industrial use.

[0045] 2. The lignin-doped montmorillonite hydrogel prepared by this invention contains abundant active sites, has a strong adsorption capacity for nitrogen and phosphorus ions and microplastics, and can adsorb nitrogen and phosphorus ions and microplastics simultaneously.

[0046] 3. The lignin used in this invention is a major byproduct of the papermaking industry, widely available and inexpensive. Montmorillonite is a common natural mineral material with abundant reserves and low price. Compared with some synthetic polymer adsorbents, lignin-doped montmorillonite hydrogels have a greater cost advantage in large-scale applications and show promising application prospects. Attached Figure Description

[0047] Figure 1 This is a picture of the lignin-doped montmorillonite hydrogel sample obtained in Example 1.

[0048] Figure 2 The image shows the SEM pattern of the lignin-doped montmorillonite hydrogel obtained in Example 1.

[0049] Figure 3 The lignin-doped montmorillonite hydrogel obtained in Example 1, at a dosage of 1.0 g / L, affects the NH4+ content in the multi-component system. + H2PO4 - Adsorption data of competing ions and microplastics.

[0050] Figure 4 The effects of lignin-doped montmorillonite hydrogel obtained in Example 1 on NH4 under different dosages + H2PO4 - Graphs showing the adsorption amounts of ions and microplastics.

[0051] Figure 5 To implement the effects of lignin-doped montmorillonite hydrogel (AALH@MMT) obtained in Example 1 and undoped montmorillonite hydrogel (AALH) obtained in Comparative Example 1 on NH4 + H2PO4 - Graphs showing the adsorption amounts of ions and microplastics. Detailed Implementation

[0052] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.

[0053] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0054] Example 1

[0055] A method for preparing lignin-doped montmorillonite hydrogel includes the following steps:

[0056] (1) Mix 0.15 g of aminated lignin with 7 mL of deionized water to obtain a homogeneous aminated lignin solution. Then, add 1.0 g of montmorillonite K-10, 2.5 g of methacryloyloxyethyltrimethylammonium chloride, 2.5 g of acrylic acid, 1.0 g of acrylamide, 0.02 g of potassium persulfate, and 0.06 g of [unspecified substance] in sequence. N, N -Methylenebisacrylamide, and magnetically stirred at 400 rpm for 20 min to completely dissolve it and remove air with N2 to obtain a mixed solution;

[0057] (2) The mixed solution obtained in step (1) was transferred to a sealed container and placed in a 60°C oven for 3 h of free radical polymerization. The resulting product was soaked in deionized water for 24 h to obtain lignin-doped montmorillonite hydrogel (AALH@MMT) (see Figure 1 and Figure 2 ).

[0058] Application of the lignin-doped montmorillonite hydrogel obtained above in the simultaneous adsorption of nitrogen and phosphorus ions and microplastics:

[0059] Weigh 0.05 g of the AALH@MMT hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of a mixed solution of ammonium chloride (100 mg N / L), potassium dihydrogen phosphate (100 mg P / L), and polystyrene (1000 mg / L). (The mixed solution is prepared by simultaneously weighing 0.0382 g of ammonium chloride, 0.0439 g of potassium dihydrogen phosphate, and 0.1000 g of polystyrene into 100 mL of deionized water and mixing thoroughly to obtain NH4.) + Concentration of 100 mg N / L, H2PO4 - A mixed solution with a concentration of 100 mg P / L and a polystyrene concentration of 1000 mg / L was prepared. The conical flask was then sealed and placed in a constant temperature shaker. The mixture was shaken at 25°C and 150 rpm for 5 h. The solution was then filtered through a 0.22 μm filter membrane. The resulting solid sample was a lignin-doped montmorillonite hydrogel after adsorption of nitrogen and phosphorus ions and microplastics.

[0060] The lignin-doped montmorillonite hydrogel (AALH@MMT) obtained above, at a dosage of 1.0 g / L, showed good performance in inhibiting the growth of NH4+ in water. + H2PO4 - Simultaneous adsorption of ions and microplastics:

[0061] Based on the NH4 in the aqueous solution before and after adsorption + H2PO4 - The adsorption capacity of nitrogen and phosphorus ions and microplastics in the lignin-doped montmorillonite hydrogel was calculated based on the concentrations of ions and polystyrene (see results). Figure 3 ), of which NH4 in the filtrate + The ion concentration was determined by Nessler's reagent method for H2PO4. - Ion concentration was determined by ammonium molybdate colorimetric method, and polystyrene concentration was determined by ultraviolet spectrophotometry.

[0062] Application of the lignin-doped montmorillonite hydrogel obtained above in the adsorption of nitrogen ions:

[0063] Weigh 0.05 g of the AALH@MMT hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of ammonium chloride solution (weigh 0.0382 g of ammonium chloride in 100 mL of deionized water to obtain NH4+). + The ammonium chloride solution with a concentration of 100 mg N / L was used. Finally, the conical flask was sealed and placed in a constant temperature shaker. It was shaken for 5 h at 25℃ and 150 rpm. Then, it was filtered through a 0.22 μm filter membrane. The resulting solid sample was a lignin-doped montmorillonite hydrogel after adsorption of nitrogen ions.

[0064] The lignin-doped montmorillonite hydrogel (AALH@MMT) obtained above exhibits different effects on NH4 in water at various dosages. + Ion adsorption:

[0065] Based on the NH4 in the aqueous solution before and after adsorption + The nitrogen ion adsorption capacity of the lignin-doped montmorillonite hydrogel was calculated from the concentration (results are shown in [see table]). Figure 4 ), of which NH4 in the filtrate + Ion concentrations were determined using the Nessler reagent method.

[0066] Application of the lignin-doped montmorillonite hydrogel obtained above in the adsorption of phosphorus ions:

[0067] Weigh 0.05 g of the AALH@MMT hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of potassium dihydrogen phosphate solution (weigh 0.0878 g of potassium dihydrogen phosphate in 100 mL of deionized water, mix well to obtain H2PO4). - A potassium dihydrogen phosphate solution with a concentration of 200 mg P / L was prepared. The conical flask was then sealed and placed in a constant temperature shaker. The mixture was shaken at 25°C and 150 rpm for 5 h. The flask was then filtered through a 0.22 μm filter membrane. The resulting solid sample was the lignin-doped montmorillonite hydrogel after adsorbing phosphorus ions.

[0068] The lignin-doped montmorillonite hydrogel (AALH@MMT) obtained above exhibits different effects on H2PO4 in water at various dosages. - Ion adsorption:

[0069] Based on the H2PO4 in the aqueous solution before and after adsorption - The phosphorus ion adsorption capacity of the lignin-doped montmorillonite hydrogel was calculated from the concentration (results are shown in...). Figure 4 ), of which, the filtrate contains H2PO4 - Ion concentration was determined by the ammonium molybdate colorimetric method.

[0070] Application of the lignin-doped montmorillonite hydrogel obtained above in the adsorption of microplastics:

[0071] Weigh 0.05 g of the AALH@MMT hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of polystyrene solution (weigh 0.0800 g of polystyrene into 100 mL of deionized water, mix well to obtain a polystyrene solution with a concentration of 800 mg / L). Finally, seal the Erlenmeyer flask and place it in a constant temperature shaker, shake at 25 °C and 150 rpm for 5 h. The resulting solid sample is lignin-doped montmorillonite hydrogel after adsorption of microplastics.

[0072] The above-mentioned lignin-doped montmorillonite hydrogel (AALH@MMT) adsorbs polystyrene in water at different dosages:

[0073] The polystyrene adsorption capacity of the lignin-doped montmorillonite hydrogel was calculated based on the polystyrene concentration in the aqueous solution before and after adsorption (see results). Figure 4 The concentration of polystyrene in the filtrate was determined by ultraviolet spectrophotometry.

[0074] Comparative Example 1

[0075] A method for preparing lignin-free montmorillonite hydrogel includes the following steps:

[0076] (1) Mix 0.15 g of aminated lignin with 7 mL of deionized water to obtain a homogeneous aminated lignin solution, and then add 2.5 g of methacryloyloxyethyltrimethylammonium chloride, 2.5 g of acrylic acid, 1.0 g of acrylamide, 0.02 g of potassium persulfate, and 0.06 g of [unspecified substance] in sequence. N, N -Methylenebisacrylamide was magnetically stirred at 400 rpm for 20 min to completely dissolve it, and air was removed with N2 to obtain a mixed solution;

[0077] (2) The mixed solution obtained in step (1) was transferred to a sealed container and placed in a 60°C oven for 3 h of free radical polymerization. The resulting product was soaked in deionized water for 24 h to obtain lignin-free montmorillonite hydrogel (AALH).

[0078] Application of the above-obtained lignin-free montmorillonite hydrogel in nitrogen ion adsorption:

[0079] Weigh 0.04 g of the AALH hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of ammonium chloride solution (weigh 0.0382 g of ammonium chloride in 100 mL of deionized water to obtain NH4). + The ammonium chloride solution with a concentration of 100 mg N / L was used. Finally, the conical flask was sealed and placed in a constant temperature shaker. It was shaken for 5 h at 25℃ and 150 rpm. Then, it was filtered through a 0.22 μm filter membrane. The resulting solid sample was lignin-free montmorillonite hydrogel after adsorption of nitrogen ions.

[0080] The lignin-free montmorillonite hydrogel (AALH) obtained above exhibits good performance in treating NH4+ in water at a dosage of 0.8 g / L. + Ion adsorption:

[0081] Based on the NH4 in the aqueous solution before and after adsorption + The nitrogen ion adsorption capacity of the lignin-free montmorillonite hydrogel was calculated from the concentration (results are shown in...). Figure 5 ), of which NH4 in the filtrate+ Ion concentrations were determined using the Nessler reagent method.

[0082] Application of the above-obtained lignin-free montmorillonite hydrogel in the adsorption of phosphorus ions:

[0083] Weigh 0.02 g of the AALH hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of potassium dihydrogen phosphate solution (weigh 0.0878 g of potassium dihydrogen phosphate in 100 mL of deionized water, mix well to obtain H2PO4). - A potassium dihydrogen phosphate solution with a concentration of 200 mgP / L was prepared. The conical flask was then sealed and placed in a constant temperature shaker. The mixture was shaken at 25°C and 150 rpm for 5 hours. The flask was then filtered through a 0.22 μm filter membrane. The resulting solid sample was the lignin-free montmorillonite hydrogel after adsorbing phosphorus ions.

[0084] The lignin-free montmorillonite hydrogel (AALH) obtained above exhibits good performance in treating H2PO4 in water at a dosage of 0.4 g / L. - Ion adsorption:

[0085] Based on the H2PO4 in the aqueous solution before and after adsorption - The phosphorus ion adsorption capacity of the lignin-free montmorillonite hydrogel was calculated from the concentration (results are shown in...). Figure 5 ), of which, the filtrate contains H2PO4 - Ion concentration was determined by the ammonium molybdate colorimetric method.

[0086] Application of the above-obtained lignin-free montmorillonite hydrogel in the adsorption of microplastics:

[0087] Weigh 0.04 g of the AALH hydrogel obtained above into a 100 mL Erlenmeyer flask, then add 50 mL of polystyrene solution (weigh 0.0800 g of polystyrene into 100 mL of deionized water, mix well to obtain a polystyrene solution with a concentration of 800 mg / L). Finally, seal the Erlenmeyer flask and place it in a constant temperature shaker, shake at 25℃ and 150 rpm for 5 h. The resulting solid sample is lignin-free montmorillonite hydrogel after adsorption of microplastics.

[0088] The above-obtained lignin-free montmorillonite hydrogel (AALH) exhibited the following adsorption properties on polystyrene in water at a dosage of 0.8 g / L:

[0089] The polystyrene adsorption capacity of the lignin-free montmorillonite hydrogel was calculated based on the polystyrene concentration in the aqueous solution before and after adsorption (see results). Figure 5 The concentration of polystyrene in the filtrate was determined by ultraviolet spectrophotometry.

[0090] Figure 1This is a picture of the lignin-doped montmorillonite hydrogel sample obtained in Example 1 of the present invention.

[0091] Figure 2 This is a SEM image of the lignin-doped montmorillonite hydrogel obtained in Example 1 of this invention. As can be seen from the image, the lignin-doped montmorillonite hydrogel exhibits a three-dimensional porous network structure. These structures increase the specific surface area of ​​the lignin-doped montmorillonite hydrogel, which facilitates the exposure of more active sites, thereby providing more channels for the penetration of nitrogen and phosphorus ions and microplastics.

[0092] Figure 3 The lignin-doped montmorillonite hydrogel obtained in Example 1 of this invention, at a dosage of 1.0 g / L, affects the NH4+ content in the multi-component system. + H2PO4 - Adsorption data show competition between ions and polystyrene. The graph indicates that increasing the concentration of NH4+ in the multi-component solution... + H2PO4 - The concentration of either ions or polystyrene can lead to a decrease in the equilibrium adsorption capacity of the lignin-doped montmorillonite hydrogel for the other two substances.

[0093] Figure 4 The lignin-doped montmorillonite hydrogel obtained in Example 1 of this invention, under different dosages, affects NH4. + H2PO4 - Graph showing adsorption data for ions and microplastics. The graph shows that as the concentration of lignin-doped montmorillonite hydrogel increased from 0.20 g / L to 0.40 g / L, its adsorption of H₂PO₄⁻ increased. - The equilibrium adsorption capacity of ions reaches its maximum value. As the concentration of lignin-doped montmorillonite hydrogel increases from 0.20 g / L to 0.80 g / L, its adsorption capacity for NH4+ ions increases. + The equilibrium adsorption capacities of both ions and polystyrene reached their maximum values.

[0094] Figure 5 The lignin-doped montmorillonite hydrogel (AALH@MMT) obtained in Example 1 and the lignin-undoped montmorillonite hydrogel (AALH) obtained in Comparative Example 1 are compared to NH4+. + H2PO4 - A comparison chart of adsorption data for ions and microplastics. Among them, the adsorption of NH4+ in lignin-doped montmorillonite hydrogels is shown. + H2PO4 - The amounts used for ion and microplastic adsorption were the same as those used for the lignin-doped montmorillonite hydrogel. The figure shows that the montmorillonite-doped hydrogel exhibited better adsorption of NH4+. + H2PO4 - The equilibrium adsorption capacities of ions and microplastics were both higher than those of the undoped montmorillonite hydrogel.

Claims

1. A method for preparing lignin-doped montmorillonite hydrogel, characterized in that: Montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, and acrylamide were added sequentially to an aqueous solution of aminated lignin. N, N Methylenebisacrylamide and potassium persulfate were stirred evenly and subjected to free radical polymerization. The resulting product was soaked in deionized water to obtain lignin-doped montmorillonite hydrogel. The mass-to-volume ratio of aminated lignin to deionized water in the aminated lignin aqueous solution was 0.15 g : 5~15 mL. The aminated lignin, montmorillonite K-10, methacryloyloxyethyltrimethylammonium chloride, acrylic acid, acrylamide, and... N, N The mass ratio of methylenebisacrylamide to potassium persulfate is 0.15 g : 0.5~1.5 g : 1.0~3.0 g : 1.0~3.0 g : 0.5~1.5 g : 0.01~0.09 g : 0.01~0.03 g.

2. The preparation method according to claim 1, characterized in that: The free radical polymerization reaction conditions are 40~80℃ for 1~3 h.

3. The preparation method according to claim 1, characterized in that: The product is soaked in deionized water for 20-40 hours.

4. The lignin-doped montmorillonite hydrogel prepared by the method according to any one of claims 1 to 3.

5. The application of the lignin-doped montmorillonite hydrogel of claim 4 in the adsorption of nitrogen ions and / or phosphorus ions and / or microplastics.

6. The application according to claim 5, characterized in that: The lignin-doped montmorillonite hydrogel was mixed with an aqueous solution of nitrogen ions and / or phosphorus ions and / or microplastics, and adsorbed in a shaker. After the adsorption was completed, the mixture was filtered, and the resulting solid sample was the lignin-doped hydrogel after adsorption of nitrogen ions and / or phosphorus ions and / or microplastics.

7. The application according to claim 6, characterized in that: The adsorption conditions are: adsorption at 100-200 rpm for 10-600 min at a temperature of 20-40℃.

8. The application according to claim 6, characterized in that: The nitrogen ion aqueous solution is one or more of ammonium chloride solution, ammonium sulfate solution and ammonium nitrate solution; The phosphate ion aqueous solution is one or more of potassium dihydrogen phosphate solution, dipotassium hydrogen phosphate solution, and sodium dihydrogen phosphate solution; The microplastic aqueous solution is one or more of polystyrene solution, polypropylene solution, and polyethylene solution.

9. The application according to claim 6, characterized in that: The concentration of the nitrogen ion aqueous solution is 10~200 mg N / L; the concentration of the phosphorus ion aqueous solution is 10~200 mg P / L; and the concentration of the microplastic aqueous solution is 100~1000 mg / L. The mass-to-volume ratio of the lignin-doped montmorillonite hydrogel to the aqueous solution of nitrogen ions and / or phosphorus ions and / or microplastics is 0.05 g : 10~100 mL.

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