Aminated corncob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent and a preparation method and application thereof

Abstract

The application discloses aminated corncob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent and a preparation method and application thereof, and the preparation method comprises the following steps: S1, pretreatment of corncob; S2, extraction of corncob cellulose; S3, dissolution of corncob cellulose; S4, forming of the composite microspheres; S5, amination modification of the microspheres; and S6, post-treatment: after the reaction is completed, washing, pre-freezing and freeze-drying treatment are carried out, and the aminated corncob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent is obtained. The aminated corncob cellulose, the sodium alginate and the lanthanum are used to construct the porous composite microspheres and are used for adsorbing phosphate, the adsorption performance is good, efficient solutions can be provided for water body phosphorus pollution treatment, agricultural waste corncob can be used in a high-value way, and the application has important research significance and application value, and has environmental benefits, economic benefits and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material preparation technology, specifically relating to an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent, its preparation method, and its application. Background Technology

[0002] my country is a major agricultural country, generating massive amounts of agricultural biomass waste annually. Corn cobs, a core byproduct of corn cultivation, accounted for approximately 55 million tons in 2022. They are a widely available, abundant, and inexpensive renewable biomass resource. Currently, traditional methods of disposing of corn cobs primarily involve open burning and indiscriminate landfilling. This not only results in a serious waste of biomass resources but also triggers a series of environmental problems, including air, soil, and water pollution, exacerbating the burden on agricultural ecosystems. Therefore, it is urgent to explore new pathways for the resource-based and high-value utilization of corn cobs, aligning with the strategic needs of green agricultural development and the "dual-carbon" goals.

[0003] Corn cob's main components are cellulose, hemicellulose, and lignin. Cellulose is a linear polymer composed of D-glucopyranose units, containing numerous active hydroxyl groups, exhibiting good hydrophilicity, biocompatibility, and chemical modification potential. However, due to the presence of internal hydrogen bonds, cellulose readily aggregates during adsorption, and powdered cellulose is difficult to recover. Porous cellulose microspheres are spherical particles formed using cellulose as a framework material. They possess a three-dimensional interconnected or closed porous network structure, resulting in a high specific surface area and effectively overcoming the defects of native cellulose, such as easy aggregation and difficulty in separation. However, pure cellulose microspheres have a limited range of surface functional groups, limiting their adsorption capacity. Therefore, to improve the adsorption effect on specific pollutants, functional modification is necessary.

[0004] Phosphate is a key pollutant causing eutrophication in water bodies. Excessive phosphorus discharge from industrial wastewater, agricultural non-point source pollution, and domestic sewage can easily lead to algal blooms, water quality deterioration, and imbalance of aquatic ecosystems, making the development of efficient and green phosphorus removal technologies urgent. Conventional phosphorus removal technologies, such as chemical precipitation and biological methods, have drawbacks such as large sludge production, easy secondary pollution, low removal efficiency, and difficulty in deep phosphorus removal. Adsorption methods, on the other hand, have become the preferred technology for phosphorus removal in water bodies due to their advantages of simple process, high adsorption efficiency, low cost, and no secondary pollution. However, traditional adsorbents such as activated carbon, clay, and zeolite have limited adsorption capacity and poor selectivity for phosphorus. In existing technologies, there are also reports on the preparation of adsorption microspheres with different targets. For example, patent document CN114849659B provides a method for removing heavy metal cadmium and phosphate from water using lanthanum-iron supported chitosan microsphere adsorbents. Using chitosan as a carrier and lanthanum-iron loading, it can efficiently adsorb heavy metal cadmium cations and phosphate anions in water, and is easy to separate and regenerate. However, the above technical solutions failed to fully utilize the corn cob.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent, its preparation method, and its application. The invention synergistically constructs porous composite microspheres from aminated corn cob cellulose, sodium alginate, and lanthanum, and uses these microspheres to adsorb phosphates. The adsorption performance is excellent, providing a highly efficient solution for the treatment of phosphorus pollution in water bodies and enabling the high-value resource utilization of agricultural waste corn cobs. This approach combines environmental, economic, and social benefits, and has significant research and application value.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent, comprising the following steps: S1. Pre-treatment of corn cobs; S2. Extraction of corn cob cellulose: The corn cob powder obtained from the pretreatment in step S1 is added to a sodium chlorite solution, the pH value is adjusted, and the mixture is heated and stirred to obtain a solid product. After rinsing, the solid product is added to a sodium hydroxide solution and stirred in a water bath. After the treatment is completed, the mixture is filtered, washed, and dried to obtain corn cob cellulose. S3. Dissolution of corn cob cellulose: Dissolve the corn cob cellulose obtained in step S2 in a pre-cooled alkaline urea solution to obtain a cellulose solution; S4. Composite microsphere molding: Sodium alginate and calcium carbonate powder are added sequentially to the cellulose solution obtained in step S3. After stirring until uniformly dispersed, the mixed solution is dropped into a coagulation bath containing hydrochloric acid and lanthanum chloride. White microspheres are formed under magnetic stirring. S5. Amination modification of microspheres: The white microspheres obtained in step S4 are added to a polyethyleneimine solution, heated, and after adjusting the pH value, glutaraldehyde solution is slowly added for soaking reaction. S6. Post-treatment: After the reaction is completed, the product is washed, pre-frozen, and freeze-dried to obtain the amination-modified corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0008] As a preferred embodiment of the technical solution of the present invention, in step S1, the pretreatment of corn cobs includes the following steps: washing and drying the corn cobs, then crushing and sieving them to obtain corn cob powder.

[0009] As a preferred embodiment of the technical solution of this invention, in step S1, the drying temperature is 60~90℃, and the pulverized material is sieved through a mesh size of 60~200 mesh. It is understood that the above drying temperature can be any value among 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, and 90℃, or 60~90℃. Any specific value within the ℃ range; the above sieve mesh can be any value among 60 mesh, 70 mesh, 80 mesh, 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 180 mesh, 190 mesh, and 200 mesh, or any specific value within the range of 60 to 200 mesh. Those skilled in the art can flexibly adjust the process parameters.

[0010] As a preferred embodiment of the technical solution of the present invention, in step S2, the concentration of sodium chlorite solution is 2~4 wt%, the ratio of corn cob powder to sodium chlorite solution is 1 g: 40~60 mL, the pH value is adjusted in the range of 3.8~4.5, the heating and stirring treatment temperature is 50~80 ℃, and the treatment time is 5~7 h; The concentration of the sodium hydroxide solution was 4-6 wt%, the ratio of solid product to sodium hydroxide solution was 1 g: 40-60 mL, the water bath stirring temperature was 50-80 ℃, and the treatment time was 3-5 h. Understandably, the concentration of the sodium chlorite solution can be any value from 2 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.4 wt%, 3.6 wt%, 3.8 wt%, 4 wt%, or any specific value within the range of 2 wt% to 4 wt%. Taking 1 g of corn cob powder as an example, the volume of sodium chlorite solution can be any value from 40 mL, 42 mL, 44 mL, 46 mL, 48 mL, 50 mL, 52 mL, 54 mL, 56 mL, 58 mL, 60 mL, or any specific value within the range of 40 to 60 mL. The pH value can be any value from 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, or any specific value within the range of 3.8 to 4.5. The heating and stirring temperature can be 50 ℃, 55 ℃, 60 ℃, 65 ℃. The temperature can be any value among ℃, 70 ℃, 75 ℃, 80 ℃, or any specific value within the range of 50~80 ℃; the processing time can be any value among 5 h, 5.5 h, 6 h, 6.5 h, 7 h, or any specific value within the range of 5~7 h. The concentration of the sodium hydroxide solution can be any one of the following: 4 wt%, 4.2 wt%, 4.4 wt%, 4.6 wt%, 4.8 wt%, 5 wt%, 5.2 wt%, 5.4 wt%, 5.6 wt%, 5.8 wt%, 6 wt%, or any specific value within the range of 4 wt% to 6 wt%. Taking 1 g of corn cob powder as an example, the volume of sodium hydroxide solution can be any one of the following: 40 mL, 42 mL, 44 mL, 46 mL, 48 mL, 50 mL, 52 mL, 54 mL, 56 mL, 58 mL, 60 mL, or any specific value within the range of 40 to 60 mL. The heating and stirring temperature can be any one of the following: 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, or any specific value within the range of 50 to 80 ℃. The treatment time can be any one of the following: 3 h, 3.5 h, 4 h, 4.5 h, 5 h, or any value within the range of 3 to 5 h. Any specific value within the range of h. To improve the purity of corn cob cellulose powder, the sodium chlorite-sodium hydroxide treatment step can be repeated 2 to 3 times. Those skilled in the art can select process parameters as needed.

[0011] As a preferred embodiment of the technical solution of the present invention, in step S3, the alkaline urea solution is obtained by mixing NaOH, urea and water in a mass ratio of 7:12:81, and the pre-cooling temperature is -12 ~ -20 ℃; The ratio of corn cob cellulose to alkali urea solution is 0.8~1.2 g: 20 mL. It is understood that the pre-cooling temperature can be any value among -12 ℃, -14 ℃, -16 ℃, -18 ℃, and -20 ℃, or any specific value within the range of -12 ℃ to -20 ℃; the amount of corn cob cellulose powder used in 20 mL of alkali urea aqueous solution can be any value among 0.8 g, 0.9 g, 1.0 g, 1.1 g, and 1.2 g, or any specific value within the range of 0.8~1.2 g, and can be flexibly adjusted by those skilled in the art.

[0012] As a preferred embodiment of the technical solution of the present invention, in step S4, the amount of sodium alginate added is 1~5 g and the amount of calcium carbonate added is 3~12 g per 100 mL of cellulose solution. The concentration of lanthanum chloride in the coagulation bath was 0.2~2 mol / L, the concentration of hydrochloric acid was 0.2~1 mol / L, the volume of the coagulation bath was 80~120 mL, and the magnetic stirring time was 10~60 min. It is understood that the amount of sodium alginate added can be any one of the following values: 1 g / 100 mL, 2 g / 100 mL, 3 g / 100 mL, 4 g / 100 mL, 5 g / 100 mL, or any specific value within the range of 1 g / 100 mL to 4 g / 100 mL; the amount of calcium carbonate added can be any one of the following values: 3 g / 100 mL, 4 g / 100 mL, 5 g / 100 mL, 6 g / 100 mL, 7 g / 100 mL, 8 g / 100 mL, 9 g / 100 mL, 10 g / 100 mL, 11 g / 100 mL, 12 g / 100 mL, or any specific value within the range of 3 g / 100 mL to 12 g / 100 mL; the concentration of lanthanum chloride can be 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L. The concentration of hydrochloric acid can be any one of the following values: 0.2 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, or any specific value within the range of 0.2 mol / L to 2 mol / L; the concentration of hydrochloric acid can be any one of the following values: 0.2 mol / L, 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, or any specific value within the range of 0.2 mol / L to 1 mol / L; the volume of the coagulation bath can be any one of the following values: 80 mL, 90 mL, 100 mL, 110 mL, 120 mL, or any specific value within the range of 80 to 120 mL, which can be selected by those skilled in the art as needed.

[0013] As a preferred embodiment of the technical solution of the present invention, in step S5, the concentration of the polyethyleneimine solution is 0.5~4 wt%, the volume is 80~120 mL, and the mass of the white microspheres is 1~6 g. The heat treatment temperature is 40~60 ℃, and the treatment time is 8~12 h; The pH value should be adjusted within the range of 7.0 to 8.5, the volume concentration of glutaraldehyde solution should be 20% to 30%, and the amount used should be 1 to 5 mL; the soaking reaction time should be 5 to 9 h. It is understood that the concentration of the polyethyleneimine solution can be any one of 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, or 4 wt%, or any specific value within the range of 0.5 wt% to 4 wt%; the volume can be any one of 80 mL, 90 mL, 100 mL, 110 mL, or 120 mL, or any specific value within the range of 80 to 120 mL; the heating temperature can be any one of 40 ℃, 42 ℃, 45 ℃, 48 ℃, 50 ℃, 52 ℃, 55 ℃, 58 ℃, or 60 ℃, or any specific value within the range of 40 to 60 ℃; and the treatment time can be any one of 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, 11.5 h, or 12 h, or any specific value within the range of 8 to 12 h. The pH adjustment range is 7.0–8.5, the glutaraldehyde concentration is 0.25 vol%–1.0 vol%, the volume added to the polyethyleneimine solution is 1 mL–5 mL, the soaking reaction time is 5–9 h, and the freeze-drying treatment time is 24–48 h. It is understood that the pH value can be any one of 7.0, 7.2, 7.4, 7.6, 7.8, 8.0, 8.2, 8.4, 8.5, or any specific value within the range of 7.0–8.5; the volume of the 25% glutaraldehyde solution added to the polyethyleneimine solution can be any one of 1 mL, 2 mL, 3 mL, 4 mL, 5 mL, or any specific value within the range of 1 mL–5 mL; the soaking reaction time can be any one of 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, or any specific value within the range of 5–9 h, and can be flexibly adjusted by those skilled in the art.

[0014] As a preferred embodiment of the present invention, in step S6, the pre-freezing time is 2-4 hours, and the freeze-drying time is 24-48 hours. It is understood that the pre-freezing time can be any value among 2 hours, 2.5 hours, 3 hours, 3.5 hours, and 4 hours, or any specific value within the range of 2-4 hours; the freeze-drying time can be any value among 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, and 48 hours, or any specific value within the range of 24-48 hours, and can be flexibly adjusted by those skilled in the art.

[0015] Secondly, the present invention also aims to protect the amination-modified corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent prepared by the above method.

[0016] Thirdly, this invention also aims to protect the application of the aforementioned aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent in phosphate adsorption. The specific application method is as follows: the microsphere adsorbent is added to phosphate-containing wastewater at a dosage of 10-50 mg and a phosphorus solution concentration of 2-20 mg / L. Adsorption is carried out under shaking at a pH of 2-10 and a temperature of 25-45 °C for a period of time, followed by filtration. Obviously, the dosage of the adsorbent and the concentration of the phosphate solution can be flexibly adjusted.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the amination corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent provided by the present invention uses agricultural waste corn cob as raw material. Through multiple steps of modification, including sodium chlorite for lignin removal, alkali treatment for cellulose purification, low-temperature dissolution in an alkali-urea system, sodium alginate and calcium carbonate-assisted sphere formation, lanthanum ion loading, and polyethyleneimine amination, composite microspheres with porous structure, abundant active sites, and good mechanical strength are successfully constructed. The reaction conditions are mild, the operation is simple, and the cost is low, realizing the high-value resource utilization of corn cob.

[0018] (2) This invention focuses on the efficient removal of phosphates from water by employing a synergistic strategy of "lanthanum loading + amination modification," which significantly enhances the material's adsorption capacity for phosphates. Compared with control materials without lanthanum loading or amination, the adsorption effect of the microspheres in this invention is significantly improved, and the performance is comparable to that of similar microspheres prepared from commercially available pure cellulose. This indicates that the lanthanum loading and amination modification in this invention synergistically improve the adsorption performance of the composite microsphere adsorbent.

[0019] (3) The composite microspheres prepared by this invention have a regular spherical shape and good mechanical properties, which facilitates solid-liquid separation and reuse after adsorption. This material has broad application prospects in the treatment of domestic sewage, agricultural runoff and industrial phosphorus-containing wastewater, and has both environmental and economic benefits, providing a new technical path for the treatment of eutrophication of water bodies and the utilization of agricultural biomass resources. Attached Figure Description

[0020] Figure 1 The images shown are related to the detection of corn cob cellulose and porous composite microspheres prepared in the examples; wherein, Figure (a) and Figure (b) are SEM images of corn cob cellulose; Figure (c) is a physical image of the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microspheres; Figures (d) to (f) are SEM images of the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microspheres. Figure 2 The images are FTIR plots of Example 1 and Comparative Examples 1 and 2. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be emphasized that, unless otherwise specified in the examples, the conditions should be performed under conventional conditions or those recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. In this invention, the crop used is corn cob; however, other common crops such as wheat straw, rice straw, sorghum straw, and sesame straw are also within the scope of protection of this invention. The specific usage scenarios described above do not constitute a specific limitation on the types of crops used in this invention.

[0023] Example 1 A method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: S1. Pre-treatment of corn cobs: Wash the corn cobs with deionized water to remove sand and dust from the surface; then dry them at 80℃, crush them with a crusher and pass them through a 100-mesh sieve to obtain corn cob powder. S2. Extraction of corn cob cellulose: 5 g of corn cob powder obtained in step S1 was added to 250 mL of 2 wt% sodium chlorite solution, the pH was adjusted to 4.0, and the mixture was heated and stirred in an 80 ℃ water bath for 6 h; the obtained solid product (all) was rinsed with deionized water until neutral, and then transferred to 250 mL of 5 wt% sodium hydroxide solution and stirred in an 80 ℃ water bath for 4 h; after treatment, the mixture was filtered, repeatedly washed with water until the pH of the filtrate was neutral, and then dried in an oven at 60 ℃; the product was treated with sodium chlorite and sodium hydroxide three times in the same manner to obtain corn cob cellulose; S3. Dissolution of corn cob cellulose: Add 4.0 g of corn cob cellulose obtained in step S2 to 100 mL of alkaline urea solution (prepared by NaOH / urea / water mass ratio of 7:12:81) pre-cooled to -12 ℃, and stir until completely transparent to obtain a viscous cellulose solution. S4. Composite microsphere molding: Add calcium carbonate powder to the cellulose solution at a dosage of 6 g per 100 mL of cellulose solution, then add 2 g of sodium alginate and stir until uniformly dispersed; drop the resulting mixed solution into 100 mL of coagulation bath containing 0.2 mol / L lanthanum chloride and 0.6 mol / L hydrochloric acid, and stir magnetically for 15 min to form white microspheres; S5. Amination modification of microspheres: 3 g of white microspheres obtained in step S4 were added to 100 mL of 4 wt% polyethyleneimine solution and heated at 50 °C for 10 h; the pH of the system was adjusted to 8.5, and 3 mL of 25 vol% glutaraldehyde solution was slowly added and the reaction was carried out for 7 h. S6. Post-treatment: After the reaction is complete, wash repeatedly with deionized water, pre-freeze for 3 hours, and freeze-dry for 48 hours to obtain the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0024] Example 2 A method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: S1. Pre-treatment of corn cobs: Wash the corn cobs with deionized water to remove sand and dust from the surface; then dry them at 60℃, crush them with a crusher and pass them through an 80-mesh sieve to obtain corn cob powder. S2. Extraction of corn cob cellulose: 5 g of corn cob powder obtained in step S1 was added to 200 mL of 2 wt% sodium chlorite solution, the pH was adjusted to 3.8, and the mixture was heated and stirred in a 50 ℃ water bath for 5 h; the obtained solid product (all) was rinsed with deionized water until neutral, and then transferred to 200 mL of 5 wt% sodium hydroxide solution and stirred in a 50 ℃ water bath for 3 h; after treatment, the mixture was filtered, repeatedly washed with water until the pH of the filtrate was neutral, and then dried in a 60 ℃ oven; the product was treated with sodium chlorite and sodium hydroxide three times in the same manner to obtain corn cob cellulose; S3. Dissolving corn cob cellulose: Add 5.0 g of corn cob cellulose obtained in step S2 to 100 mL of alkaline urea solution (prepared by NaOH / urea / water mass ratio of 7:12:81) pre-cooled to -12 ℃, and stir until completely transparent to obtain a viscous cellulose solution. S4. Composite microsphere molding: Add calcium carbonate powder to the cellulose solution at a dosage of 3g per 100mL of cellulose solution, then add 1g of sodium alginate and stir until uniformly dispersed; drop the resulting mixed solution into 80mL of coagulation bath containing 0.3mol / L lanthanum chloride and 0.2mol / L hydrochloric acid, and stir magnetically for 15min to form white microspheres; S5. Amination modification of microspheres: 3 g of white microspheres obtained in step S4 were added to 80 mL of 0.5 wt% polyethyleneimine solution and heated at 40 °C for 8 h; the pH of the system was adjusted to 7.0, and 2 mL of 25 vol% glutaraldehyde solution was slowly added, and the reaction was carried out for 5 h. S6. Post-treatment: After the reaction is complete, wash repeatedly with deionized water, pre-freeze for 2 hours, and freeze-dry for 24 hours to obtain the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0025] Example 3 A method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: S1. Pre-treatment of corn cobs: Wash the corn cobs with deionized water to remove sand and dust from the surface; then dry them at 90℃, crush them with a crusher and pass them through a 120-mesh sieve to obtain corn cob powder. S2. Extraction of corn cob cellulose: 5 g of corn cob powder obtained in step S1 was added to 300 mL of 4 wt% sodium chlorite solution, the pH was adjusted to 4.5, and the mixture was heated and stirred in an 80 ℃ water bath for 7 h; the obtained solid product (all) was washed with deionized water until neutral, and then transferred to 300 mL of 6 wt% sodium hydroxide solution and stirred in an 80 ℃ water bath for 5 h; after the treatment was completed, the mixture was filtered, repeatedly washed with water until the pH of the filtrate was neutral, and then dried in an oven at 60 ℃ to obtain corn cob cellulose; S3. Dissolution of corn cob cellulose: Add 6.0 g of corn cob cellulose obtained in step S2 to 100 mL of alkaline urea solution (prepared by NaOH / urea / water mass ratio of 7:12:81) pre-cooled to -20 ℃, and stir until completely transparent to obtain a viscous cellulose solution. S4. Composite microsphere molding: Add calcium carbonate powder to the cellulose solution at a dosage of 12.0g per 100mL of cellulose solution, then add 5.0g of sodium alginate and stir until uniformly dispersed; drop the resulting mixed solution into a coagulation bath containing 2mol / L lanthanum chloride and 1mol / L hydrochloric acid, and stir magnetically for 15 min to form white microspheres; S5. Amination modification of microspheres: 3 g of white microspheres obtained in step S4 were added to 120 mL of 2wt% polyethyleneimine solution and heated at 60 °C for 12 h; the pH of the system was adjusted to 8.5, and 4 mL of 25 vol% glutaraldehyde solution was slowly added, and the reaction was carried out for 9 h. S6. Post-treatment: After the reaction is complete, wash repeatedly with deionized water, pre-freeze for 4 h, and freeze-dry for 48 h to obtain the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0026] Comparative Example 1 Compared to Example 1, the operation in step S4 was adjusted in this comparative example to verify that the lanthanum chloride loading is the core metal coordination site for efficient phosphorus removal by the microspheres, and its absence significantly reduces the adsorption capacity. Specifically, a method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: S1. Pre-treatment of corn cobs: Wash the corn cobs with deionized water to remove sand and dust from the surface; then dry them at 80℃, crush them with a crusher and pass them through a 100-mesh sieve to obtain corn cob powder. S2. Extraction of corn cob cellulose: 5 g of corn cob powder obtained in step S1 was added to 250 mL of 2 wt% sodium chlorite solution, the pH was adjusted to 4.0, and the mixture was heated and stirred in an 80 ℃ water bath for 6 h; the obtained solid product (all) was rinsed with deionized water until neutral, and then transferred to 250 mL of 5 wt% sodium hydroxide solution and stirred in an 80 ℃ water bath for 4 h; after treatment, the mixture was filtered, repeatedly washed with water until the pH of the filtrate was neutral, and then dried in an oven at 60 ℃; the product was treated with sodium chlorite and sodium hydroxide three times in the same manner to obtain corn cob cellulose; S3. Dissolution of corn cob cellulose: Add 4.0 g of corn cob cellulose obtained in step S2 to 100 mL of alkaline urea solution (prepared by NaOH / urea / water mass ratio of 7:12:81) pre-cooled to -12 ℃, and stir until completely transparent to obtain a viscous cellulose solution. S4. Composite microsphere molding: Add calcium carbonate powder to the cellulose solution at a dosage of 6 g per 100 mL of cellulose solution, then add 2 g of sodium alginate and stir until uniformly dispersed; drop the resulting mixed solution into 100 mL of coagulation bath containing 0.6 mol / L hydrochloric acid and stir magnetically for 15 min to form white microspheres. S5. Amination modification of microspheres: 3 g of white microspheres obtained in step S4 were added to 100 mL of 4 wt% polyethyleneimine solution and heated at 50 °C for 10 h; the pH of the system was adjusted to 8.5, and 3 mL of 25 vol% glutaraldehyde solution was slowly added and the reaction was carried out for 7 h. S6. Post-treatment: After the reaction is complete, wash repeatedly with deionized water, pre-freeze for 3 hours, and freeze-dry for 48 hours to obtain the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0027] Comparative Example 2 Compared to Example 1, step S5 is omitted in this comparative example to verify that amination modification is key to improving the positive charge on the microsphere surface and enhancing phosphorus electrostatic adsorption; its absence significantly reduces the removal rate. Specifically, a method for preparing an amination-modified corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: A method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent includes the following steps: S1. Pre-treatment of corn cobs: Wash the corn cobs with deionized water to remove sand and dust from the surface; then dry them at 80℃, crush them with a crusher and pass them through a 100-mesh sieve to obtain corn cob powder. S2. Extraction of corn cob cellulose: 5 g of corn cob powder obtained in step S1 was added to 250 mL of 2 wt% sodium chlorite solution, the pH was adjusted to 4.0, and the mixture was heated and stirred in an 80 ℃ water bath for 6 h; the obtained solid product (all) was rinsed with deionized water until neutral, and then transferred to 250 mL of 5 wt% sodium hydroxide solution and stirred in an 80 ℃ water bath for 4 h; after treatment, the mixture was filtered, repeatedly washed with water until the pH of the filtrate was neutral, and then dried in an oven at 60 ℃; the product was treated with sodium chlorite and sodium hydroxide three times in the above steps to obtain corn cob cellulose; S3. Dissolution of corn cob cellulose: Add 4.0 g of corn cob cellulose obtained in step S2 to 100 mL of alkaline urea solution (prepared by NaOH / urea / water mass ratio of 7:12:81) pre-cooled to -12 ℃, and stir until completely transparent to obtain a viscous cellulose solution. S4. Composite microsphere molding: Add calcium carbonate powder to the cellulose solution at a dosage of 6 g per 100 mL of cellulose solution, then add 2 g of sodium alginate and stir until uniformly dispersed; drop the resulting mixed solution into 100 mL of coagulation bath containing 0.2 mol / L lanthanum chloride and 0.6 mol / L hydrochloric acid, and stir magnetically for 15 min to form white microspheres; S5. Post-treatment: The white microspheres obtained in step S4 are repeatedly washed with deionized water, pre-frozen for 3 hours, and freeze-dried for 48 hours to obtain the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

[0028] Comparative Example 3 Compared with Example 1, this comparative example directly uses commercial cellulose (C804601, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.) to replace steps S1 and S2, and all other steps are the same.

[0029] See Figure 1 This invention successfully prepared porous adsorption microspheres. Further details can be found in the following sections. Figure 2 Comparative Example 2 at 3444 cm-1 The absorption peak at this location is for OH. In Comparative Example 1 and Example 1, the introduction of NH during the amination process shifts the peak to 3404 cm⁻¹. -1 (International Journal of Biological Macromolecules 310 (2025) 143354; Cellulose 32 (2025) 2537-2551); all three are at 2910 cm⁻¹ -1 The absorption peak at 1633 cm⁻¹ is attributed to the stretching vibration of CH (Colloids and Surfaces A: Physicochemical and Engineering Aspects 719(2025) 137015); Comparative Example 1 shows an absorption peak at 1633 cm⁻¹. -1 The peak at this location corresponds to the water adsorbed in cellulose, while the peak at this location in Comparative Example 2 and Example 1 is at 1616 cm⁻¹. -1 COO at the location - Peak coverage (iScience 26 (2023) 107783). Comparative Examples 1, 2 and Example 1 at 1165 cm⁻¹ -1 and 1041 cm -1 and 893 cm -1 The peaks at 808 cm⁻¹ correspond to the vibrational absorptions of the CC group, the COC group in the pyranose ring, and the glycosidic bond, respectively (Jurnal of Hazardous Materials 316 (2016) 11-18; International Journal of Biological Macromolecules 297 (2025) 139915); Example 1 and Comparative Example 2 showed peaks at 808 cm⁻¹. -1 A La-O vibrational absorption peak appeared at this location, while no absorption peak was observed in Comparative Example 1, indicating that lanthanum was successfully loaded.

[0030] Application Example 1 The removal effect of microsphere adsorbent at different dosages was investigated, and the specific steps are as follows: Different amounts of the microsphere adsorbent prepared in Example 1 were added to 50 mL of a 20 mg / L phosphate solution and placed in a constant temperature shaking shaker. The mixture was shaken at 25°C for 24 h at a speed of 150 r / min. The concentration of residual phosphorus in the solution was determined using ammonium molybdate spectrophotometry, and the removal rate was calculated. R (%), Formula 1) and adsorption capacity ( q e (mg / g), Formula 2), the same below: (Equation 1) (Equation 2) In the formula, C 0 represents the concentration of phosphorus in the solution before adsorption, in mg / L; C e The concentration of residual phosphorus in the solution after adsorption equilibrium is given in mg / L.

[0031] The results are shown in Table 1.

[0032] Table 1. Effect of different dosages on removal efficiency Table 1 shows that as the adsorbent dosage increased from 5 mg to 40 mg, the phosphate... R The percentage increased significantly from 11.75% to 94.80%; when the dosage reached 20 mg, R The concentration has reached 89.29%, and the dosage should be increased further. R The growth rate is slowing down; q e As the dosage increased, a trend of first rising and then falling emerged. Taking all factors into consideration... R and q e The preferred adsorbent dosage is 20 mg.

[0033] Application Example 2 The adsorption effects of different adsorbents were investigated, and the specific steps are as follows: Accurately weigh 20 mg of each of the microsphere adsorbents from Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, and add them to 50 mL of a 20 mg / L phosphorus solution. Place the solutions in a constant temperature shaking shaker and shake at 25°C for 24 h at a speed of 150 r / min. Measure the concentration of residual phosphorus in the solution and calculate the removal rate. The results are shown in Table 2.

[0034] Table 2 Comparison of adsorption effects of different adsorbents As shown in Table 2, the adsorption effect of the aminated corn cob cellulose / sodium alginate / lanthanum composite microspheres prepared in this invention (Example 1) on phosphate is significantly higher than that of the aminated corn cob cellulose microspheres without lanthanum loading (Comparative Example 1) and the unaminated corn cob cellulose / sodium alginate / lanthanum microspheres (Comparative Example 2), and is basically equivalent to that of the porous composite microspheres prepared using commercially available pure cellulose (Comparative Example 3).

[0035] In summary, this invention utilizes corn cob as raw material to produce an aminated corn cob cellulose / sodium alginate / lanthanum composite microsphere adsorbent, achieving high-value utilization of corn cob. The resulting adsorbent exhibits excellent phosphorus adsorption performance and has broad application prospects.

[0036] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent, characterized in that, Includes the following steps: S1. Pre-treatment of corn cobs; S2. Extraction of corn cob cellulose: The corn cob powder obtained from the pretreatment in step S1 is added to a sodium chlorite solution, the pH value is adjusted, and the mixture is heated and stirred to obtain a solid product. After rinsing, the solid product is added to a sodium hydroxide solution and stirred in a water bath. After the treatment is completed, the mixture is filtered, washed, and dried to obtain corn cob cellulose. S3. Dissolution of corn cob cellulose: Dissolve the corn cob cellulose obtained in step S2 in a pre-cooled alkaline urea solution to obtain a cellulose solution; S4. Composite microsphere molding: Sodium alginate and calcium carbonate powder are added sequentially to the cellulose solution obtained in step S3. After stirring until uniformly dispersed, the mixed solution is dropped into a coagulation bath containing hydrochloric acid and lanthanum chloride. White microspheres are formed under magnetic stirring. S5. Amination modification of microspheres: The white microspheres obtained in step S4 are added to a polyethyleneimine solution, heated, and after adjusting the pH value, glutaraldehyde solution is slowly added for soaking reaction. S6. Post-treatment: After the reaction is completed, the product is washed, pre-frozen, and freeze-dried to obtain the amination-modified corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent.

2. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S1, the pretreatment of corn cobs includes the following steps: washing and drying the corn cobs, then crushing and sieving them to obtain corn cob powder.

3. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 2, characterized in that, In step S1, the drying temperature is 60~90℃, and the pulverized material is sieved through a mesh size of 60~200.

4. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S2, the concentration of sodium chlorite solution is 2-4 wt%, the ratio of corn cob powder to sodium chlorite solution is 1 g: 40-60 mL, the pH value is adjusted within the range of 3.8-4.5, the heating and stirring temperature is 50-80 ℃, and the treatment time is 5-7 h. The concentration of the sodium hydroxide solution was 4-6 wt%, the ratio of solid product to sodium hydroxide solution was 1 g: 40-60 mL, the water bath stirring temperature was 50-80 ℃, and the treatment time was 3-5 h.

5. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S3, the alkaline urea solution is obtained by mixing NaOH, urea, and water in a mass ratio of 7:12:81, and the pre-cooling temperature is -12 ~ -20 ℃; The ratio of corn cob cellulose to alkaline urea solution is 0.8~1.2 g: 20 mL.

6. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S4, the amount of sodium alginate added to each 100 mL cellulose solution is 1-5 g, and the amount of calcium carbonate added is 3-12 g. The concentration of lanthanum chloride in the coagulation bath is 0.2~2 mol / L, the concentration of hydrochloric acid is 0.2~1 mol / L, the volume of the coagulation bath is 80~120mL, and the magnetic stirring time is 10~60 min.

7. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S5, the concentration of the polyethyleneimine solution is 0.5-4 wt%, the volume is 80-120 mL, and the mass of the white microspheres is 1-6 g. The heat treatment temperature is 40~60 ℃, and the treatment time is 8~12 h; The pH value should be adjusted within the range of 7.0 to 8.5, the volume concentration of glutaraldehyde solution should be 20% to 30%, and the amount used should be 1 to 5 mL; the soaking reaction time should be 5 to 9 h.

8. The preparation method of an aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 1, characterized in that, In step S6, the pre-freezing time is 2-4 h, and the freeze-drying time is 24-48 h.

9. An ammoniated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent prepared by the method according to any one of claims 1 to 8.

10. The application of the aminated corn cob cellulose / sodium alginate / lanthanum porous composite microsphere adsorbent according to claim 9 in phosphate adsorption.

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