A binary composite lignin-based aerogel adsorption material and its preparation method and application

Abstract

The present invention belongs to the field of water treatment technology, and specifically relates to a binary composite lignin-based aerogel adsorption material, a preparation method thereof, and an application thereof. The binary composite lignin-based aerogel adsorption material is compounded by lignin sulfonate and carboxyl xylan, and polymerized with acrylamide, a cross-linking agent, an initiator, and tetramethylethylenediamine, and freeze-dried. The present invention uses green, non-toxic, and widely available industrial waste lignin sulfonate as a raw material, utilizes its aromatic properties and sulfonic acid anions to compound carboxyl xylan for synergistic adsorption, and obtains an aerogel adsorption material by simple solution blending and freeze-drying. It has the advantages of low cost, environmental friendliness, simple synthesis process, and safe operation, and can be used for the efficient removal of methylene blue in printing and dyeing wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a binary composite lignin-based aerogel adsorption material, a preparation method thereof, and an application thereof. Background Art

[0002] Methylene blue is an organic pollutant harmful to humans. Developing efficient water treatment technologies to remove methylene blue from printing and dyeing wastewater is crucial for addressing water pollution and maintaining a healthy human environment. Compared to other water treatment technologies, such as flocculation, precipitation, and oxidation, adsorption offers promise for large-scale application in the treatment of printing and dyeing wastewater due to its simplicity and pollution-free nature. However, currently used adsorbent materials suffer from low adsorption rates and are difficult to regenerate. In contrast, aerogels offer advantages such as low density, high specific surface area, high porosity, and high pore volume, offering broad application prospects in the adsorption field. However, the preparation of traditional inorganic and organic aerogels often involves the use of toxic and hazardous reagents, such as acids, bases, and organic reagents, which pose certain risks to the ecological environment and human health. Furthermore, their high cost limits their industrial application. Therefore, the search for a green, non-toxic, environmentally friendly, and low-cost aerogel material is a key research priority in wastewater treatment.

[0003] Lignin is a rich renewable organic carbon resource in nature, mainly found in industrial waste such as papermaking, with the advantages of being green, non-toxic, biocompatible, degradable and inexpensive. In addition, lignin is rich in aromatic structures, and its structure contains rich functional groups such as methoxy, carbonyl, phenolic hydroxyl, etc., with high reactivity, making it an ideal aerogel synthetic material. At present, existing lignin-based aerogel materials for methylene blue adsorption in water bodies are mostly prepared by composite preparation of graphene oxide and lignin. For example, Li et al. (International Journal of Biological Macromolecules, 2020, 143, 325-333) prepared aerogel adsorption materials by composite preparation of graphene oxide and alkali lignin, and Li et al. (International Journal of Biological Macromolecules, 2019, 136, 927-935) prepared aerogel adsorption materials by composite preparation of graphene oxide with lignin sulfonate and chitosan. However, the preparation process of graphene oxide is complicated, and involves the use of strong oxidants potassium permanganate and hydrogen peroxide, causing certain operational safety hazards. Therefore, for the treatment of methylene blue wastewater, it is necessary to develop efficient lignin-based aerogel adsorption materials with simple synthesis process and safe operation. Summary of the Invention

[0004] To address these needs, the present invention has developed a binary composite lignin-based aerogel adsorption material. Targeted to the structural characteristics of the target pollutant, the material utilizes lignin sulfonate as a raw material and is compounded with carboxylated xylan to synergistically adsorb methylene blue from water. This aerogel material, derived from environmentally friendly biomass raw materials, is obtained through simple solution blending and freeze-drying. This material boasts a simple synthesis process, safe operation, environmental friendliness, and low cost, better meeting the needs of aerogel adsorption materials.

[0005] The technical solution adopted in the present invention is:

[0006] A binary composite lignin-based aerogel adsorption material is prepared by reacting 1.0-5.0 wt% of lignin sulfonate, 0-10.0 wt% of carboxyxylan, 5.0-20.0 wt% of acrylamide, 1.0-5.0 wt% of a cross-linking agent, 0.5-2.5 wt% of an initiator and 0.5-2.5 wt% of tetramethylethylenediamine.

[0007] Furthermore, in the above-mentioned binary composite lignin-based aerogel adsorption material, the lignin sulfonate is one or a combination of sodium lignin sulfonate and calcium lignin sulfonate.

[0008] Furthermore, in the above-mentioned binary composite lignin-based aerogel adsorption material, the carboxyxylan is carboxymethylxylan or carboxyethylxylan.

[0009] Furthermore, in the above-mentioned binary composite lignin-based aerogel adsorption material, the cross-linking agent is N,N'-methylenebisacrylamide or aluminum hydroxide.

[0010] Furthermore, in the above-mentioned binary composite lignin-based aerogel adsorption material, the initiator is one of hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide and methyl ethyl ketone peroxide.

[0011] The above-mentioned method for preparing a binary composite lignin-based aerogel adsorption material comprises the following steps:

[0012] 1) adding 5.0-20.0 wt% acrylamide, 1.0-5.0 wt% cross-linking agent, 0-10.0 wt% carboxyxylan, and 1.0-5.0 wt% lignin sulfonate to 20 mL of deionized water and stirring at room temperature for 2 h, then adding 0.5-2.5 wt% initiator and 0.5-2.5 wt% tetramethylethylenediamine, stirring evenly, and further polymerizing the resulting solution at room temperature for 12 h to obtain a hydrogel;

[0013] 2) The hydrogel was washed with deionized water, then placed in a freeze dryer, and dried at -50°C for 48 hours to obtain a binary composite lignin-based aerogel adsorption material.

[0014] The binary composite lignin-based aerogel adsorption material described in any one of the above items is used to adsorb methylene blue in printing and dyeing wastewater.

[0015] Furthermore, the above application method is as follows: the pH value of the methylene blue solution is adjusted to 1-14, and a binary composite lignin-based aerogel adsorption material is added thereto for adsorption.

[0016] Furthermore, in the above application, the concentration of the methylene blue solution is 10-200 mg / mL, and the volume is 50 mL; the amount of the binary composite lignin-based aerogel adsorption material is 0.01-0.09 g.

[0017] Furthermore, the adsorption conditions of the above application are: adsorption temperature is 10-80°C, and adsorption time is 5-1440 minutes.

[0018] The beneficial effects of the present invention are:

[0019] 1. In order to solve the problem of high cost of aerogel materials, the extremely low-cost industrial waste resource lignin sulfonate is used to significantly reduce the cost of aerogel materials and bring considerable economic benefits.

[0020] 2. In response to the problem of using toxic and harmful reagents in traditional aerogels, the use of biocompatible and degradable biomass raw materials can greatly avoid the harm to the human body and the pollution to the environment caused by the production process.

[0021] 3. In order to solve the problem that traditional aerogels use non-renewable raw materials, the use of renewable organic carbon materials with a wide range of sources promotes the recycling of carbon resources.

[0022] 4. In order to solve the problem of limited adsorption efficiency of single lignin, carboxyl xylan was added to the aerogel to enable synergistic adsorption of lignin sulfonate and carboxyl xylan, thereby improving the adsorption efficiency of methylene blue.

[0023] 5. In response to the problems of complex process and unsafe operation of existing lignin-based aerogel materials, a simple solution blending and freeze-drying step is adopted to simplify the synthesis process and increase operational safety. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

[0025] Example 1

[0026] 0.9900g of xylan was dispersed in 9.00L of a mixed solution of 20% alcohol and water, stirred for 10 minutes, and then 4.93mL of a 25wt% NaOH solution was added thereto at 30°C. After stirring for 30min, 3.4900g of sodium chloroacetate was added to the mixed solution and reacted at 65°C for 2 hours; then, 4.93mL of a 25wt% NaOH solution and 3.4900g of sodium chlorate were added, and the reaction was continued at 65°C for 2 hours. After the reaction was completed, the pH value of the obtained solution was adjusted to 7 with dilute acetic acid, and then the mixed solution was slowly added to ethanol. At this time, a precipitate was generated in the ethanol solution. The obtained precipitate was washed three times with 95% ethanol and then dried in an oven at 50°C for 48h. The obtained sample was carboxymethyl xylan.

[0027] Example 2

[0028] 7.5 wt% acrylamide, 3.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 h. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 h to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 h, a binary composite lignin-based aerogel adsorption material was obtained.

[0029] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 28.45% and the adsorption amount was 13.34 mg / g.

[0030] Example 3

[0031] 17.5 wt% acrylamide, 3.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0032] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 24.06% and the adsorption amount was 11.16 mg / g.

[0033] Example 4

[0034] 10.0 wt% acrylamide, 2.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0035] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 3.14% and the adsorption amount was 1.35 mg / g.

[0036] Example 5

[0037] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0038] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 30.40% and the adsorption amount was 13.64 mg / g.

[0039] Example 6

[0040] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.0 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0041] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 54.10% and the adsorption amount was 28.59 mg / g.

[0042] Example 7

[0043] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 2.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0044] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 27.61% and the adsorption amount was 14.20 mg / g.

[0045] Example 8

[0046] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 5.0 wt% carboxymethyl xylan, and 5.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0047] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 31.54% and the adsorption amount was 15.19 mg / g.

[0048] Example 9

[0049] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 10.0 wt% carboxymethyl xylan, and 1.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0050] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask with a pH of 6.9. Then, 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The solution was adsorbed at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 16.56% and the adsorption amount was 8.07 mg / g.

[0051] Example 10

[0052] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0053] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 3, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 19.48% and the adsorption amount was 9.74 mg / g.

[0054] Example 11

[0055] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0056] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 24 h. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 40.22% and the adsorption amount was 17.80 mg / g.

[0057] Example 12

[0058] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0059] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 15 minutes. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 4.06% and the adsorption amount was 3.87 mg / g.

[0060] Example 13

[0061] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0062] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 720 min. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 17.38%, and the adsorption amount was 26.83 mg / g.

[0063] Example 14

[0064] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0065] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0100 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 720 min. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 15.94% and the adsorption amount was 38.31 mg / g.

[0066] Example 15

[0067] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0068] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0900 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 720 min. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 28.96% and the adsorption amount was 7.95 mg / g.

[0069] Example 16

[0070] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0071] 50 mL of a 10 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 720 min. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 34.38%, and the adsorption amount was 5.87 mg / g.

[0072] Example 17

[0073] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0074] 50 mL of a 200 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at room temperature for 720 min. The absorbance of methylene blue in the solution was detected by a UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 8.34% and the adsorption amount was 30.34 mg / g.

[0075] Example 18

[0076] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0077] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at 20 ° C for 720 min. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 31.32% and the adsorption amount was 24.77 mg / g.

[0078] Example 19

[0079] 10.0 wt% acrylamide, 5.0 wt% N,N'-methylenebisacrylamide, 8.0 wt% carboxymethyl xylan, and 4.0 wt% sodium lignin sulfonate were added to 20 mL of deionized water and stirred at room temperature for 2 hours. Then, 1.5 wt% ammonium persulfate and 1.5 wt% tetramethylethylenediamine were added thereto and stirred evenly. A hydrogel began to form. The obtained solution was then further polymerized at room temperature for 12 hours to obtain a hydrogel. The hydrogel was washed with deionized water and then placed in a freeze dryer. After drying at -50°C for 48 hours, a binary composite lignin-based aerogel adsorption material was obtained.

[0080] 50 mL of a 50 mg / L methylene blue solution was placed in a 250 mL conical flask, the pH was adjusted to 11, and then 0.0500 g of the binary composite lignin-based aerogel adsorption material prepared above was added. The adsorption was carried out at 40 ° C for 720 min. The absorbance of methylene blue in the solution was detected by UV-visible spectrophotometer, and the removal rate and adsorption amount were calculated. The removal rate was 51.11% and the adsorption amount was 39.80 mg / g.

[0081] The above is an exemplary description of the present invention. Without departing from the core of the present invention, any simple deformation, modification, substitution, combination, and simplification are equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A binary composite lignin-based aerogel adsorption material, characterized in that: The binary composite lignin-based aerogel adsorption material is prepared by reacting 1.0-5.0wt% of lignin sulfonate, 0-10.0wt% of carboxyxylan, 5.0-20.0wt% of acrylamide, 1.0-5.0wt% of a cross-linking agent, 0.5-2.5wt% of an initiator and 0.5-2.5wt% of tetramethylethylenediamine; the amount of the carboxyxylan is not zero.

2. A binary composite lignin-based aerogel adsorption material according to claim 1, characterized in that: The lignin sulfonate is one or a combination of sodium lignin sulfonate and calcium lignin sulfonate.

3. The binary composite lignin-based aerogel adsorption material according to claim 1, characterized in that: The carboxyxylan is carboxymethylxylan or carboxyethylxylan.

4. The binary composite lignin-based aerogel adsorption material according to claim 1, characterized in that: The cross-linking agent is N,N'-methylenebisacrylamide or aluminum hydroxide.

5. The binary composite lignin-based aerogel adsorption material according to claim 1, characterized in that: The initiator is one of hydrogen peroxide, ammonium persulfate, potassium persulfate, benzoyl peroxide, tert-butyl benzoyl peroxide and methyl ethyl ketone peroxide.

6. The method for preparing a binary composite lignin-based aerogel adsorption material according to claim 1, characterized in that: The steps include: 1) Add 5.0-20.0 wt% acrylamide, 1.0-5.0 wt% cross-linking agent, 0-10.0 wt% carboxyxylan, and 1.0-5.0 wt% lignin sulfonate to 20 mL of deionized water and stir at room temperature for 2 h. Then, add 0.5-2.5 wt% initiator and 0.5-2.5 wt% tetramethylethylenediamine and stir evenly. Then, further polymerize the resulting solution at room temperature for 12 h to obtain a hydrogel. 2) The hydrogel was washed with deionized water, placed in a freeze dryer, and dried at -50 °C for 48 h to obtain a binary composite lignin-based aerogel adsorption material.

7. Use of the binary composite lignin-based aerogel adsorption material according to any one of claims 1 to 5 in adsorbing methylene blue in printing and dyeing wastewater.

8. The use according to claim 7, characterized in that The method is as follows: the pH value of the methylene blue solution is adjusted to 1-14, and a binary composite lignin-based aerogel adsorption material is added thereto for adsorption.

9. The use according to claim 8, characterized in that The concentration of the methylene blue solution is 10-200 mg / mL, and the volume is 50 mL; the amount of the binary composite lignin-based aerogel adsorption material is 0.01-0.09 g.

10. The use according to claim 8, characterized in that The adsorption conditions are as follows: adsorption temperature is 10-80° C., and adsorption time is 5-1440 min.