Degradable polyurethane foam adsorption material, preparation method and application

Abstract

The invention provides a degradable polyurethane foam adsorption material as well as a preparation method and application thereof, the degradable polyurethane foam adsorption material is prepared by taking polyurethane foam with an adjustable structure as a framework and combining natural renewable cellulose and humic acid for modification, and is a porous adsorption material. The degradable polyurethane foam adsorption material has a relatively high adsorption effect on micro-nano plastic, basic fuchsin and tetracycline with the diameter of 40-100nm, and can be used for effectively removing various pollutants in a water environment. In addition, the degradable polyurethane foam adsorption material also has better degradability and renewability, and can reduce the occurrence of secondary pollution. Besides, the preparation method of the degradable polyurethane foam adsorption material is simple, the raw materials for preparation are wide in source and low in cost, and an efficient, degradable and resource-friendly innovative solution is provided for synergistic removal of micro-nano plastics, dyes and antibiotics in a water environment.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material technology, and relates to a biodegradable polyurethane foam adsorption material, its preparation method, and its application. Background Technology

[0002] Micro- and nano-plastics, dyes, and antibiotics are the three most typical micro-pollutants in the aquatic environment, often accumulating in wastewater from hospitals, farms, industries, and domestic water. Micro- and nano-plastics, due to their extremely high chemical stability and difficulty in natural degradation, remain in water bodies for extended periods and accumulate through the food chain, posing a potential threat to ecosystems and human health. Synthetic dyes or their degradation products have carcinogenic or mutagenic effects and can damage the liver and kidneys. Antibiotics in the aquatic environment mainly originate from discharges from hospitals and aquaculture; once antibiotics and drug-resistant genes enter the human body, they can alter the gut microbiota and increase the incidence of drug-resistant infections.

[0003] For the three types of small-sized pollutants mentioned above, existing removal methods mainly include physical methods such as filtration and sedimentation; chemical methods such as flocculation, adsorption, and oxidation-reduction; biological methods such as microbial degradation and phytoremediation; membrane technologies such as nanofiltration and reverse osmosis; and advanced oxidation methods such as photocatalysis and ozonation. Filtration can remove particulate pollutants of different sizes by configuring filter membranes with different pore sizes, which is highly efficient and produces no secondary pollution; sedimentation uses relatively low-cost chemical reagents and equipment, making it suitable for large-scale treatment; flocculation is generally highly efficient at removing charged pollutants; adsorption relies on the functional groups on the surface of adsorbent materials to chemically adsorb the above pollutants, which is low-cost and easy to operate; biological methods have the advantages of being environmentally friendly, low-cost, low-energy, and utilizing biological resources; advanced oxidation methods can degrade organic pollutants. However, filtration methods suffer from a significant performance decline as various pollutants and particles accumulate on the membrane surface; precipitation methods have low removal efficiency, especially limited effectiveness in removing small-sized microplastics; flocculation methods face drawbacks such as high cost, complex operation, poor floc selectivity, and secondary pollution; biological methods are generally characterized by low degradation efficiency, high specificity, sensitivity to environmental conditions, and difficulty in large-scale application; and advanced oxidation methods are not yet sufficiently effective for treating micro- and nano-plastics and macromolecular dyes. Therefore, adsorption methods, with their high efficiency and low cost, have become the mainstream approach in current research on the removal of these small-sized pollutants.

[0004] For the removal of micropollutants by adsorption, common adsorbents can be broadly classified into five categories: traditional inorganic minerals, such as bentonite and zeolite; carbon-based materials, such as activated carbon and graphene oxides; metal-organic frameworks, such as MOFs; polymeric hydrogels, such as PVA / chitosan composites; and functionalized magnetic materials, such as modified Fe3O4 nanoparticles. Traditional inorganic minerals are widely used due to their abundant raw materials, low cost, and good retention performance for large particles, but their removal efficiency for nanoscale pollutants is limited, and they require solid waste treatment after use. Carbon-based materials achieve high-efficiency adsorption due to their ultra-high specific surface area and porous structure, but they are prone to pore blockage, and regeneration often relies on high temperatures or modified chemical agents, resulting in high energy consumption and complex operation. Metal-organic frameworks have designable pore structures, large adsorption capacities, and strong selectivity, but their disadvantages include high synthesis costs and the non-degradability of ligands and metal nodes. Polymeric hydrogels have expandable network structures and some biodegradability, but they are sensitive to pH and temperature, require optimization of cross-linking degree and equilibrium performance, and have limited cycle life. Functionalized magnetic materials can be rapidly separated and recovered, and directionally adsorbed by an external magnetic field, but they are difficult to degrade, easily aggregate, and often have poor long-term cycling performance.

[0005] In summary, most current adsorption materials are unable to effectively adsorb small-sized pollutants and are difficult to degrade. Summary of the Invention

[0006] The purpose of this invention is to provide a biodegradable polyurethane foam adsorbent material, its preparation method, and its application, in order to solve the problems of poor degradation performance and poor removal effect of existing adsorbent materials on micro-pollutants.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This application provides a biodegradable polyurethane foam adsorbent material, which is prepared by using tunable polyurethane foam as a framework and modifying it with natural renewable cellulose and humic acid. It is a porous adsorbent material.

[0008] Specifically, the preparation method of the biodegradable polyurethane foam adsorbent material in this application includes: S01: Dissolve cellulose and humic acid in a solvent, add isocyanate for cross-linking reaction, and obtain a mixture.

[0009] Cellulose and humic acid in a mass ratio of 5:1 to 15:1 are added to a solvent and sonicated until completely dissolved. The mass ratio of cellulose to solvent is 1:2 to 1:5, and the mass ratio of humic acid to solvent is also 1:2 to 1:5. The total mass of cellulose and humic acid constitutes 5-15% of the total mass of the biodegradable polyurethane foam adsorbent material. Isocyanate is added to the dissolved solution and stirred to form a mixture, wherein the mass ratio of cellulose to isocyanate is 0.15:1 to 0.48:1.

[0010] In this application, the cellulose is cellulose microcrystals with a particle size ≤25 μm, the solvent is N,N-dimethylformamide, and the isocyanate includes polyphenylene polymethylene polyisocyanate and / or polymethylene polyphenyl isocyanate. Preferably, the mass ratio of cellulose to humic acid is 10:1.

[0011] S02: Add polyol, catalyst and foaming agent to the mixture, and obtain biodegradable polyurethane foam adsorbent material after stirring, foaming, curing, washing and drying.

[0012] A polyol to isocyanate mass ratio of 3:1 to 1:1 is used to add polyol, 0.1-0.5% (by mass of the total polyol and isocyanate), and 0.5-5% (by mass of the total polyol and isocyanate) of foaming agent to the mixture. The mixture is stirred and foamed at room temperature and a stirring speed of 300-400 rpm to form foam. After the foam is molded and cured, it is washed with water and / or ethanol, and then freeze-dried to obtain a biodegradable polyurethane foam adsorbent material.

[0013] Isocyanates and polyols undergo a cross-linking reaction under the action of a catalyst and a foaming agent, and are further modified by introducing cellulose and humic acid, which are derived from natural renewable biomass, to form a porous, three-dimensional network polyurethane foam adsorbent material. Due to the introduction of numerous polar functional groups such as hydroxyl and carboxyl groups through cellulose and humic acid during the cross-linking process, this polyurethane foam adsorbent material can efficiently capture functional groups on the surface of micro / nanoplastics, dye molecules, and antibiotic molecular skeletons through multiple physicochemical mechanisms, including electrostatic interactions, hydrogen bonding, hydrophobic interactions, and π–π stacking. Simultaneously, the mesoporous structure of the surface-charged cellulose microcrystals significantly enhances the adsorption capacity for nanoplastics, and the open macropores improve mass transfer performance and reduce clogging.

[0014] In addition, by introducing natural biodegradable components cellulose and humic acid and using them to adjust the crosslinking density of the skeleton of biodegradable polyurethane foam adsorbent material, the biodegradable polyurethane foam adsorbent material can be gradually degraded under the action of natural environment or microorganisms, reducing the risk of secondary pollution.

[0015] In this application, the polyol includes propylene glycol polyether with an average molecular weight of 800-2000 g / mol and / or trimethylolpropane polyether with a molecular weight of 400-4000 g / mol; the catalyst includes one or more of triethylenediamine, tetraethylammonium bromide and dibutyltin dilaurate; and the blowing agent includes one or more of cyclopentane, water and dichloromethane.

[0016] This application provides an application of a biodegradable polyurethane foam adsorbent material, namely, the application of a biodegradable polyurethane foam adsorbent material in the adsorption of micro and nano plastics.

[0017] In addition, this application also provides another application of biodegradable polyurethane foam adsorbent materials, namely, the application of biodegradable polyurethane foam adsorbent materials in the removal of polystyrene micro / nanoplastics, basic fuchsin and tetracycline from water.

[0018] The present invention has the following beneficial effects: (1) The biodegradable polyurethane foam adsorbent material prepared in this application has a strong adsorption effect on micro-nano plastics with diameters of 40μm-100nm, and also has a high adsorption effect on basic fuchsin and tetracycline, which can effectively remove a variety of pollutants in the water environment.

[0019] (2) The biodegradable polyurethane foam adsorbent material prepared in this application can undergo partial degradation of the polymer skeleton after 30 days of burial, indicating that it has good biodegradability, reduces the occurrence of secondary pollution, and effectively solves the environmental problem of traditional adsorbent materials being difficult to degrade.

[0020] (3) The biodegradable polyurethane foam adsorbent material prepared in this application has good renewability, and its adsorption rate on micro-nano plastics still reaches more than 90% after five adsorption-desorption cycles.

[0021] (4) The preparation method of this biodegradable polyurethane foam adsorbent material is simple, the raw materials are widely available and the cost is low, providing an efficient, biodegradable and resource-friendly innovative solution for the synergistic removal of micro-nanoplastics, dyes and antibiotics in the water environment. Attached Figure Description

[0022] Figure 1 A graph showing the difference in surface Zeta potential data for cellulose microcrystals, humic acid, the biodegradable polyurethane foam adsorbent material prepared in Example 1, and three pollutants. Figure 2 The graph shows the degradation results of the polyurethane foam adsorbent materials prepared in Examples 1 and 8 and Comparative Examples 1, 2, 3 and 4 after 180 days of burial. Figure 3 The graph shows the renewability test results of different biomass-modified polyurethane foam adsorbent materials. Detailed Implementation

[0023] The technical solution of the present invention will be further explained and described below through specific embodiments. The reagents and equipment used in this application are commercially available reagents and equipment conventionally in the technical field.

[0024] Example 1 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 1.50g of cellulose powder and 0.15g of humic acid were added to 4.5g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 10g of propylene glycol polyether with a Mn concentration of 2000g / mol, 0.064g of tetraethylammonium bromide, and 0.8g of water were added to the mixture and stirred at 25℃ and a stirring speed of 300rpm for 15s to form foam. After the foam was molded and cured, it was repeatedly washed three times with deionized water under ultrasonic oscillation and then freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0025] Example 2 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 0.75g of cellulose powder and 0.113g of humic acid were added to 2.5g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of propylene glycol polyether (Mn=1000g / mol), 0.0025g of triethylenediamine, and 0.025g of cyclopentane were added to the mixture and stirred at 25℃ and 300rpm for 15s to form foam. After the foam was molded and cured, it was repeatedly washed three times with deionized water under ultrasonic oscillation and then freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0026] Example 3 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 2.25g of cellulose powder and 0.225g of humic acid were added to 9g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 5g of propylene glycol polyether with Mn=800g / mol, 0.01g of dibutyltin dilaurate, and 0.75g of dichloromethane were added to the mixture and stirred at 25℃ and a stirring rate of 400rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0027] Example 4 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 0.75g of cellulose powder and 0.15g of humic acid were added to 4.25g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of propylene glycol polyether with Mn=2000g / mol, 0.04g of tetraethylammonium bromide, and 0.15g of water were added to the mixture and stirred at 25℃ and a stirring rate of 320rpm for 15s to form foam. After the foam was molded and cured, it was repeatedly washed three times with deionized water under ultrasonic oscillation and then freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0028] Example 5 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 1.5g of cellulose powder and 0.3g of humic acid were added to 0.6g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 10g of propylene glycol polyether with Mn=1200g / mol, 0.02g of dibutyltin dilaurate, and 0.15g of water were added to the mixture and stirred at 25℃ and a stirring rate of 360rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0029] Example 6 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 1.8g of cellulose powder and 0.18g of humic acid were added to 5.4g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of polymethylene polyphenyl isocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 5g of trimethylolpropane polyether (Mn=4000g / mol), 0.05g of triethylenediamine, and 0.45g of dichloromethane were added to the mixture and stirred at 25℃ and 360rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0030] Example 7 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 1.2g of cellulose powder and 0.12g of humic acid were added to 6g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of polymethylene polyphenyl isocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of trimethylolpropane polyether (Mn=1000g / mol), 0.015g of tetraethylammonium bromide, and 0.075g of water were added to the mixture and stirred at 25℃ and 300rpm for 15s to form foam. After the foam was molded and cured, it was repeatedly washed three times with deionized water under ultrasonic oscillation and then freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0031] Example 8 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 2.4 g of cellulose powder and 0.24 g of humic acid were added to 9.6 g of N,N-dimethylformamide and sonicated until completely dissolved. 5 g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 10 g of propylene glycol polyether with a Mn concentration of 2000 g / mol, 0.064 g of tetraethylammonium bromide, and 0.8 g of water were added to the mixture and stirred at 25°C and a stirring rate of 350 rpm for 15 seconds to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0032] Example 9 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 0.8 g of cellulose powder and 0.08 g of humic acid were added to 1.6 g of N,N-dimethylformamide and sonicated until completely dissolved. 5 g of polymethylene polyphenyl isocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 5 g of trimethylolpropane polyether (Mn=800 g / mol), 0.08 g of dibutyltin dilaurate, and 0.8 g of dichloromethane were added to the mixture and stirred at 25°C and 400 rpm for 15 seconds to form foam. After the foam was molded and cured, it was repeatedly washed three times with anhydrous ethanol under ultrasonic oscillation and then freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0033] Example 10 This application provides a biodegradable polyurethane foam adsorbent material, the preparation method of which includes: 1.6g of cellulose powder and 0.16g of humic acid were added to 8g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of polymethylene polyphenyl isocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of trimethylolpropane polyether (Mn=2000g / mol), 0.064g of tetraethylammonium bromide, and 0.8g of water were added to the mixture and stirred at 25℃ and 320rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain a biodegradable polyurethane foam adsorbent material.

[0034] Comparative Example 1 This application provides a polyurethane foam as a comparative example, the preparation method of which includes: 10g of propylene glycol polyether with Mn=2000g / mol, 0.064g of tetraethylammonium bromide, and 0.8g of water were added to 5g of diphenylmethane diisocyanate under stirring. The mixture was stirred and foamed for 15s at 25℃ and a stirring speed of 300rpm to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, and then washed three times with anhydrous ethanol. Finally, it was freeze-dried in a freeze dryer for 24h to obtain polyurethane foam.

[0035] Comparative Example 2 This application provides a polyurethane foam as a comparative example, the preparation method of which includes: 1.5g of cellulose powder was added to 4.5g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 10g of propylene glycol polyether with Mn=2000g / mol, 0.064g of tetraethylammonium bromide, and 0.8g of water were added to the mixture and stirred at 25℃ and a stirring speed of 300rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain polyurethane foam.

[0036] Comparative Example 3 This application provides a polyurethane foam as a comparative example, the preparation method of which includes: 0.15 g of humic acid was added to 4.51 g of N,N-dimethylformamide and sonicated until completely dissolved. 5 g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 10 g of propylene glycol polyether with Mn = 2000 g / mol, 0.064 g of tetraethylammonium bromide, and 0.8 g of water were added to the mixture and stirred at 25°C and a stirring speed of 300 rpm for 15 seconds to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain polyurethane foam.

[0037] Comparative Example 4 This application provides a polyurethane foam as a comparative example, the preparation method of which includes: 0.5g of cellulose powder and 0.05g of humic acid were added to 8g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of propylene glycol polyether with Mn=2000g / mol, 0.064g of tetraethylammonium bromide, and 0.8g of water were added to the mixture and stirred at 25℃ and a stirring speed of 300rpm for 15s to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain polyurethane foam.

[0038] Comparative Example 5 This application provides a polyurethane foam as a comparative example, the preparation method of which includes: 1.6g of cellulose powder and 0.16g of humic acid were added to 8g of N,N-dimethylformamide and sonicated until completely dissolved. 5g of diphenylmethane diisocyanate was added to the dissolved solution and stirred until homogeneous, forming a mixture. 15g of propylene glycol polyether with Mn=2000g / mol was added to the mixture, and the mixture was stirred and foamed for 15s at 25℃ and a stirring speed of 300rpm to form foam. After the foam was molded and cured, it was first washed three times with deionized water under ultrasonic oscillation, then washed three times with anhydrous ethanol, and finally freeze-dried for 24 hours to obtain polyurethane foam.

[0039] Example 1 is a biodegradable polyurethane foam adsorbent material containing 10% cellulose and 1% humic acid. Example 8 is a biodegradable polyurethane foam adsorbent material containing 15% cellulose and 1.5% humic acid; Comparative Example 1 is polyurethane foam without added biomass; Comparative Example 2 is a polyurethane foam containing 10% cellulose but no humic acid; Comparative Example 3 is a polyurethane foam containing 1% humic acid but no cellulose; Comparative Example 4 is a polyurethane foam containing 5% cellulose and 15% humic acid.

[0040] In this application, the adsorption performance, low-concentration pollutant removal, degradation performance, and regeneration performance of the biodegradable polyurethane foam adsorbent materials prepared in Examples 1-10 and the polyurethane foams prepared in Comparative Examples 1-5 were tested respectively. The specific test process is as follows: (1) Adsorption performance test Stock solutions of nanoplastics with a particle size of 40 nm and microplastics with particle sizes of 1 μm and 40 μm were prepared with deionized water at concentrations of 10-500 mg / L. 0.1 g of the biodegradable polyurethane foam adsorbent material prepared in Examples 1-10 and the polyurethane foam prepared in Comparative Examples 1-4 were added to 50 mL conical flasks containing 40 mL of micro / nanoplastics stock solution, a mixed solution of basic fuchsin dye, and tetracycline, respectively, and shaken for a certain period of time at a shaking frequency of 180 rpm. The concentration of nanoplastics before and after adsorption was measured using a fluorescence spectrophotometer with an excitation wavelength of 470 nm and a fluorescence wavelength of 540 nm, and the concentrations of dye and antibiotic were measured using a UV spectrophotometer. The adsorption capacity of different polyurethane foam samples was calculated using the following equation, and the results are shown in Table 1.

[0041] Among them, C0 and C t , respectively, are the concentrations of the pollutant solution at 0 and t hours, in mg / L; Qe is the adsorption capacity of the pollutant, in mg / g; V is the volume of the pollutant, in mL; m is the mass of the polyurethane foam, in g.

[0042] Table 1: Adsorption capacity of polyurethane foam for various pollutants As shown in Table 1, compared with polyurethane foam without added cellulose and humic acid, the adsorption capacity of polyurethane foam adsorbent material with added cellulose and humic acid is significantly improved for micro-nanoplastics, basic fuchsin dye and tetracycline.

[0043] The high adsorption efficiency of biodegradable polyurethane foam adsorbents for pollutants stems primarily from their unique physicochemical properties. A significant charge difference exists between the biodegradable polyurethane foam adsorbent and the target pollutant, determined by the negative charge on the surfaces of cellulose and humic acid. Figure 1As shown, the zeta potential difference between nanoplastics and biodegradable polyurethane foam adsorbents is the highest, reaching 32.19 mV under neutral conditions. The potential differences between basic fuchsin and antibiotics with biodegradable polyurethane foam adsorbents also reach 23.38 mV and 19.61 mV, respectively, resulting in strong electrostatic attraction. More importantly, by introducing abundant polar functional groups such as hydroxyl and carboxyl groups into the three-dimensional network structure, efficient adsorption of different types of pollutants can be achieved through multiple mechanisms. Furthermore, hydrophobic interactions and π–π stacking effects enable effective capture of micro- and nanoplastics, while hydrogen bonding endows it with highly efficient capture capabilities for polar substances such as dyes and antibiotics.

[0044] (2) Low-concentration pollutant removal test In this application embodiment, micro-nano plastics, basic fuchsin, and tetracycline with a concentration of 10 mg / L were used as research objects. The removal rates of the three pollutants were calculated according to the concentrations obtained in the adsorption performance test (1), as shown in Table 2. The formula for calculating the removal rate is: Where υ is the removal rate of pollutants by polyurethane foam (%), V is the volume of pollutants (mL), C0 is the concentration of pollutants before adsorption (mg / L), and C is the concentration of pollutants after adsorption (mg / L).

[0045] Table 2: Removal rate of various pollutants by polyurethane foam As shown in Table 2, when cellulose and humic acid are added to the biodegradable polyurethane foam adsorbent material, the removal rate of common pollutants such as micro-nanoplastics, basic fuchsin, and tetracycline is significantly improved.

[0046] (3) Degradation performance test The polyurethane foams prepared in Examples 1 and 8 and Comparative Examples 1, 2, 3, and 4 of this application were buried in soil of the same underground layer for 180 days. The mass of each polyurethane foam was tested monthly, and the percentage of remaining mass was calculated according to the following formula. A plot was then drawn to obtain the attached figure. Figure 2 .

[0047] Where υ is the percentage of remaining biodegradable foam mass (%), m0 is the initial mass of biodegradable foam (g), and m is the mass of biodegradable foam after degradation (g).

[0048] From the appendix Figure 2It is evident that pure polyurethane and samples without added foaming agent showed virtually no degradation within 180 days. When cellulose or humic acid was added to polyurethane foam, the degradation rate of the degradable polyurethane foam adsorbent material was improved. The degradation rate was highest when both cellulose and humic acid were added simultaneously, and the degradation rate increased with the amount of biomass added.

[0049] (4) Regeneration performance test To verify the regenerability of the biodegradable polyurethane foam adsorbent materials prepared in this application, the biodegradable polyurethane foam adsorbent materials prepared in Examples 1-10 after adsorbing nanoplastics were immersed in distilled water and 95% ethanol solutions, respectively, and subjected to ultrasonic desorption treatment for 5 minutes. Repeated adsorption experiments on nanoplastics were then performed on the desorbed biodegradable polyurethane foam adsorbent materials to obtain the desired adsorption properties. Figure 3 .

[0050] From the appendix Figure 3 As can be seen, after five repeated uses, the biodegradable polyurethane foam adsorbent material prepared in this application still maintains an adsorption rate of over 90% for nanoplastics, demonstrating a high adsorption capacity. This indicates that the biodegradable polyurethane foam adsorbent material prepared in this application not only exhibits excellent adsorption performance for nanoplastics but also possesses good renewability.

[0051] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for preparing a biodegradable polyurethane foam adsorbent material, characterized in that, include: Cellulose and humic acid are dissolved in a solvent, and isocyanate is added and stirred to obtain a mixture. Polyol, catalyst and foaming agent are added to the mixture, and after stirring, foaming, curing, washing and drying, a biodegradable polyurethane foam adsorbent material is obtained.

2. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The mass ratio of cellulose to humic acid is 5:1-15:1; the total mass of cellulose and humic acid is 5-15% of the total mass of the biodegradable polyurethane foam adsorbent material; the mass ratio of cellulose to isocyanate is 0.15:1-0.48:

1.

3. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The mass ratio of cellulose to solvent is 1:2 to 1:5; the mass ratio of humic acid to solvent is 1:2 to 1:

5.

4. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The mass ratio of the polyol to the isocyanate is 3:1 to 1:1; the amount of catalyst added is 0.1-0.5% of the total mass of the polyol and the isocyanate; the amount of foaming agent added is 0.5-5% of the total mass of the polyol and the isocyanate.

5. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The cellulose is cellulose microcrystals with a particle size ≤25μm, the solvent is N,N-dimethylformamide, and the isocyanate includes polyphenylene polymethylene polyisocyanate and / or polymethylene polyphenyl isocyanate.

6. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The polyol comprises propylene glycol polyether with an average molecular weight of 800-2000 g / mol and / or trimethylolpropane polyether with a molecular weight of 400-4000 g / mol; the catalyst comprises one or more of triethylenediamine, tetraethylammonium bromide and dibutyltin dilaurate; the foaming agent comprises one or more of cyclopentane, water and dichloromethane.

7. The method for preparing the biodegradable polyurethane foam adsorbent material according to claim 1, characterized in that, The washing solvent is water and / or ethanol, and the stirring speed during foaming is 300-400 rpm.

8. The biodegradable polyurethane foam adsorbent material prepared by the preparation method according to any one of claims 1-7.

9. The application of the biodegradable polyurethane foam adsorbent material prepared by the preparation method according to any one of claims 1-7 in the adsorption of micro and nano plastics.

10. The application of the biodegradable polyurethane foam adsorbent material prepared by the preparation method according to any one of claims 1-7 in the removal of polystyrene micro / nanoplastics, basic fuchsin, and tetracycline from water.

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