Preparation and application of a composite aerogel material for removing microplastics in water bodies

Abstract

The application discloses a kind of preparation and application of composite aerogel material for removing water microplastics, belong to microplastics removal field.The method comprises the following steps: (1) carboxymethyl cellulose and hexanediamine are dissolved in water, N-hydroxysuccinimide solution and carbodiimide hydrochloride solution are added, then the reaction liquid is dialyzed, the reaction liquid after dialysis is evaporated under reduced pressure to obtain viscous liquid, then the obtained viscous liquid is prepared into CMC-NHNH2 solution with water;(2) cellulose nanocrystal is dissolved in water, then sodium periodate is added, after stirring, stop the reaction by adding ethylene glycol to obtain reaction liquid, then the reaction liquid is dialyzed, and the dialyzed reaction liquid is evaporated under reduced pressure, and then adjusted to CNC-CHO solution with water;(3) Fe3O4@C 12 It is added to CNC-CHO solution, and added to CMC-NHNH2 solution, shaken and mixed uniformly, refrigerated, and then freeze-dried to obtain composite aerogel material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microplastic removal, and relates to preparation and application of a composite aerogel material for removing microplastics in water bodies. BACKGROUND

[0002] With the rapid development of the world economy, plastics play an important role in human life due to their convenient use, low cost, high economic benefit, corrosion resistance, insulation and other physical and chemical properties. According to statistics, the global plastic production increased by 2.5% in 2019 compared with 2018. After use, about 10% of the plastic products are recycled or incinerated, and the rest are released into the environment or landfills. These waste plastics will be broken down into small particles or fragments through various external factors such as mechanical wear, weathering, ultraviolet radiation and biological metabolism. These plastic fragments with a diameter of less than 5 mm are defined as microplastics. The more plastic products are used, the higher the risk of microplastics. Microplastics are small in size, large in specific surface area, and strong in hydrophobicity, which are ideal carriers for many hydrophobic organic pollutants and heavy metals. At the same time, microplastics are easily mistaken for food by plankton and fish, and are transferred and enriched in the food web, and even eventually ingested by humans. Therefore, efficient removal of microplastics in water environments is of great significance to human health and environmental protection.

[0003] At present, the research on microplastics is still in its infancy, and there is no mature technical system for the removal of microplastics. For microplastics with larger particle size, the method of skimming and filtering is usually used to remove them from water. However, as the particle size of microplastics becomes smaller, the method of skimming and filtering is no longer applicable to their removal. Therefore, researchers at home and abroad are developing more reasonable and effective methods to remove microplastics. Some scientists have synthesized a photocatalyst to catalytically degrade microplastics in water environments; some scientists have isolated a new enzyme MG8 from human saliva, which can effectively decompose microplastic polyethylene terephthalate; in addition to these new methods, adsorption is also an effective method for removing microplastics. Compared with other methods, adsorption is recognized as an important technology for water purification and pollution removal due to its convenient operation, high purification rate, low energy consumption and low cost.

[0004] A method of using superhydrophobic magnetic nanometer ferroferric oxide material to adsorb microplastics is mentioned in "Superhydrophobic and Sustainable Nanostructured Powdered Iron for the Efficient Separation of Oil-in-Water Emulsions and the Capture of Microplastics", but the method still needs to be improved to meet the urgent demand for efficient removal of microplastics in water environment. SUMMARY

[0005] [Technical problem]

[0006] There is a need to improve the existing adsorption technology to further improve the removal rate of microplastics to meet the current environmental protection, health and safety requirements.

[0007] [Technical solution]

[0008] To solve the above problems, the present application uses superhydrophobic magnetic nanometer ferroferric oxide material to prepare composite aerogel to adsorb polystyrene (PS) microplastics in liquid.

[0009] The present application provides a preparation method of composite aerogel material, comprising the following steps:

[0010] (1) Amide modification of carboxymethyl cellulose (CMC):

[0011] Dissolve CMC and hexanedihydrazine in water, add N-hydroxysuccinimide solution and carbodiimide hydrochloride solution, mix to obtain a reaction solution, then adjust the pH of the reaction solution to 6.5-7, then dialyze the reaction solution, and then reduce pressure evaporation to obtain a viscous liquid, then the viscous liquid is prepared into a CMC-NHNH2 solution with water;

[0012] (2) Aldehyde modification of cellulose nanocrystals (CNC):

[0013] Dissolve CNC in water, then add sodium periodate, stir, then add ethylene glycol to stop the reaction to obtain a reaction solution, then dialyze the reaction solution, and then reduce pressure evaporation, then adjust the reaction solution to a CNC-CHO solution with water;

[0014] (3) Preparation of porous nanocellulose aerogel loaded with superhydrophobic magnetic nanometer ferroferric oxide (Fe3O4@C 12 ):

[0015] Dissolve Fe3O4@C 12The CMC-NHNH2 solution prepared in step (1) is added into the CNC-CHO solution prepared in step (2) and mixed uniformly, and then is subjected to ultrasonic treatment. The mixture is then stored in a refrigerator and freeze-dried to obtain a composite aerogel material.

[0016] Further, the mass ratio of CMC to hexamethylene dihydrazine in step (1) is 1:2-4.

[0017] Further, the mass ratio of CMC to water in step (1) is 1:40-60.

[0018] Further, the concentration of the N-hydroxysuccinimide solution in step (1) is 15-20 mg / mL.

[0019] Further, the solvent of the N-hydroxysuccinimide solution in step (1) is a solution of dimethyl sulfoxide (DMSO) and water in a volume ratio of 1:0.5-1.5.

[0020] Further, the mass-volume ratio of CMC to the N-hydroxysuccinimide solution in step (1) is 1 g:2-4 mL.

[0021] Further, the concentration of the carbodiimide hydrochloride solution in step (1) is 0.1-0.5 g / mL.

[0022] Further, the solvent of the carbodiimide hydrochloride solution in step (1) is a solution of DMSO and H2O in a volume ratio of 1:0.5-1.5.

[0023] Further, the mass-volume ratio of CMC to the carbodiimide hydrochloride solution in step (1) is 1 g:0.4-0.8 mL.

[0024] Further, the water in the dialysis is changed every 3-5 h during the dialysis in step (1).

[0025] Further, the water volume for the dialysis in step (1) is 80-100 times the volume of the reaction solution.

[0026] Further, the mass fraction of the CMC-NHNH2 solution in step (1) is 0.5-1.5%.

[0027] Further, the mass ratio of CNC to water in step (2) is 1:40-60.

[0028] Further, the mass ratio of CNC to sodium periodate in step (2) is 1:0.4-0.8.

[0029] Further, the stirring time in step (2) is 1-3 h.

[0030] Further, the mass-volume ratio of CNC and ethylene glycol in step (2) is 1 g:0.2-0.4 mL.

[0031] Further, the water is changed every 3-5 h during dialysis in step (2).

[0032] Further, the water volume for dialysis in step (2) is 80-100 times the reaction liquid volume.

[0033] Further, the mass fraction of the CNC-CHO solution in step (2) is 0.5-1.5%.

[0034] Further, the mass ratio of Fe3O4@C 12 and CNC-CHO solution in step (3) is 1:30-60.

[0035] Further, the ultrasonic time in step (3) is 3-8 min.

[0036] Further, the refrigeration time in step (3) is 4-8 h. Further, the mass ratio of Fe3O4@C 12 and CMC-NHNH2 solution in step (3) is 1:30-60.

[0037] Preferably, the mass ratio of Fe3O4@C 12 and CNC-CHO solution in step (3) is 1:40-50.

[0038] Preferably, the mass ratio of Fe3O4@C 12 and CMC-NHNH2 solution in step (3) is 1:40-50.

[0039] Further, the preparation method of Fe3O4@C 12 comprises the following steps:

[0040] S1. Washing of magnetic nanometer ferroferric oxide

[0041] The magnetic nanometer ferroferric oxide is immersed in a dilute hydrochloric acid solution to remove surface contaminants, then taken out after washing, then immersed in acetone, then taken out after washing, and finally immersed in an ethanol solution, taken out after washing, and dried to obtain clean magnetic nanometer ferroferric oxide;

[0042] S2. Preparation of long-chain fatty acid solution

[0043] A 0.5 mol / L lauric acid solution is prepared, with anhydrous ethanol as the solvent;

[0044] S3. Synthesis of super-hydrophobic magnetic nanometer ferroferric oxide

[0045] The 0.5g clean magnetic nanometer ferroferric oxide prepared in step S1 is soaked in 20mL lauric acid solution prepared in step S2, heated to 80℃ for 1h, then dried for 1h, and finally the super-hydrophobic magnetic nanometer material, lauric acid modified magnetic Fe3O4 nanoparticles Fe3O4@C is obtained 12 .

[0046] The application provides a composite aerogel material prepared according to the method.

[0047] The composite aerogel material prepared by the application has the application in the field of micro-plastic removal and the field of environmental protection.

[0048] [beneficial effects]

[0049] 1) The raw material of the preparation method is convenient and fast, no secondary pollution is generated in water treatment, the material itself is easy to separate, recycle and reuse, and has a good application prospect.

[0050] 2) The removal rate of micro-plastics can reach 94.61% at most, and most of the micro-plastics can be removed, and the product of the application is aerogel, which can be placed arbitrarily, and the problem of micro-plastics can be solved. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 is the hydrophobic characterization of ferroferric oxide and super-hydrophobic magnetic nanometer ferroferric oxide material, which shows that the prepared material has the characteristics of super-hydrophobicity, wherein, figure (a) is a schematic diagram of contact angle test, figures (b1-b5) are the contact angle measurement values of Fe3O4, Fe3O4@C 12 , Fe3O4@C 14 , Fe3O4@C 16 , Fe3O4@C 18 .

[0052] Figure 2 is the characterization of the morphology of ferroferric oxide and super-hydrophobic magnetic nanometer ferroferric oxide material, and transmission electron microscopy and atomic force microscopy are used for characterization, wherein, figures (a)-(e) are transmission electron micrographs of Fe3O4, Fe3O4@C 12 , Fe3O4@C 14 , Fe3O4@C 16 , Fe3O4@C 18 , figures (f)-(j) are atomic force microscope 3D images of Fe3O4, Fe3O4@C 12 , Fe3O4@C 14 , Fe3O4@C 16 , Fe3O4@C 18 , and figures (k)-(o) are Fe3O4, Fe3O4@C 12Fe3O4@C 14 Fe3O4@C 16 Fe3O4@C 18 Atomic force microscope 2D image of Fe3O4@C

[0053] Figure 3 X-ray photoelectron spectroscopy characterization of Fe3O4 and superhydrophobic magnetic Fe3O4 nanomaterials, which characterizes the functional groups on the surface of the magnetic Fe3O4 nanomaterials and the superhydrophobic magnetic Fe3O4 nanomaterials, wherein figure (a) is a full spectrum diagram, figure (b) is an XPS spectrum diagram of Fe 2p, figure (c) is an XPS spectrum diagram of C1s, and figure (d) is an XPS spectrum diagram of O1s.

[0054] Figure 4 Infrared, X-ray diffraction, magnetic measurement, and thermogravimetric analysis characterization of Fe3O4 and superhydrophobic magnetic Fe3O4 nanomaterials. Among them, figure (a) is an infrared spectrum diagram, figure (b) is an X-ray diffraction diagram, figure (c) is a magnetic hysteresis loop, and figure (d) is a thermogravimetric analysis diagram. DETAILED DESCRIPTION

[0055] Detection process

[0056] The method for calculating the PS removal efficiency used in the following examples is as follows:

[0057] η = (C0-C e ) / C e

[0058] In the formula, η is the removal rate of the adsorbent for fluorescent polystyrene (GFL-PS) at equilibrium;

[0059] C0 is the initial concentration (mg / mL);

[0060] C e is the concentration of GFL-PS in the solution at adsorption equilibrium (mg / mL).

[0061] Raw material source

[0062] Unless otherwise specified, the following raw materials are ordinary commercially available materials.

[0063] Example 1

[0064] (1) Magnetic Fe3O4 nanomaterials cleaning

[0065] Firstly, the magnetic nano-Fe304 (average particle size 20 nm) was immersed in dilute hydrochloric acid solution (volume ratio of hydrochloric acid to ultrapure water 1:20) to remove the surface contaminants (10 min), and then taken out after washing. Then, the magnetic nano-Fe304 was immersed in acetone to remove the surface oil impurities (5 min) and taken out. Finally, the magnetic nano-Fe304 was immersed in a solution of high-grade ethanol to clean the surface of the magnetic nano-Fe304 of residual acid solution and acetone (1 min). The cleaning process was carried out in ultrasonic operation. The cleaned magnetic nano-Fe304 was dried and used.

[0066] (2) Preparation of long-chain fatty acid solution

[0067] 100 mL volumetric flask was used to prepare four 0.5 mol / L fatty acid solutions, respectively, and the fatty acids were lauric acid, myristic acid, palmitic acid and stearic acid. The stearic acid needed to be dissolved by water bath heating. The solvents of the four fatty acid solutions were high-purity anhydrous ethanol.

[0068] (3) Synthesis of super-hydrophobic magnetic nano-Fe304

[0069] The four same quality 0.5 g of cleaned magnetic nano-Fe304 were immersed in 20 mL of lauric acid, myristic acid, palmitic acid and stearic acid ethanol solution, respectively. The reaction system was heated to 80°C and reacted for 1 h. After the reaction was completed, it was placed in a drying oven at 80°C and dried for 1 h. Finally, the super-hydrophobic magnetic nano-materials lauric acid modified magnetic Fe304 nanoparticles (Fe3O4@C 12 ), myristic acid modified magnetic Fe304 nanoparticles (Fe3O4@C 14 ), palmitic acid modified magnetic Fe304 nanoparticles (Fe3O4@C 16 ) and stearic acid modified magnetic Fe304 nanoparticles (Fe3O4@C 18 ) were obtained.

[0070] The four kinds of magnetic super-hydrophobic nano-Fe304 prepared above were characterized:

[0071] 1. To prevent roughness effect, Fe3O4@C n (n = 12, 14, 16, 18) powder was sprinkled on a glass slide coated with adhesive, and then flattened with another slide, leaving no excess powder. The water contact angle (WCA) was measured using an interfacial shear rheometer (DSA 30R, Kruss GmbH, Hamburg, Germany). Then 2 μL of deionized water droplets were dropped onto the material plane. A camera was used to take images of the water droplets at a speed of 10 per second, and the Young-Laplace equation was used to fit the curve.

[0072] 2. Transmission electron microscopy (TEM, JEM-2100, JEOL, Tokyo, Japan) was used to observe the micro-morphology of Fe3O4@C n (n=12, 14, 16, 18). Atomic force microscopy (AFM, AFM-5500M, Hitachi, Tokyo, Japan) was used to measure the roughness of Fe3O4@C n (n=12, 14, 16, 18) materials. The sample preparation method of atomic force microscopy was the same as the transmission electron microscopy experiment. A special copper mesh was required for transmission electron microscopy observation of magnetic nanoparticles. Dry magnetic nanoparticles were placed in anhydrous ethanol and dispersed using ultrasonic waves. The dispersed magnetic material was sucked out with a dropper and dropped onto a double-layer mesh support film. After drying, the mesh support film was folded with the nanoparticles sandwiched in the middle for observation.

[0073] 3. Fourier transform infrared spectroscopy (Frontier, Norwalk, CT, USA) was used to identify the functional groups of Fe3O4@C n (n=12, 14, 16, 18). The wavelength was 400-4000 cm -1 .

[0074] 4. X-ray photoelectron spectroscopy (XPS, Thermo ESCALAB 250XI, USA) was used to analyze the element distribution in Fe3O4@C n (n=12, 14, 16, 18).

[0075] 5. Vibrating sample magnetometer (VSM, LAKESHORE-7404, USA) was used to measure the hysteresis loop at room temperature.

[0076] 6. X-ray diffractometer (XRD) 7000 produced by Shimadzu Corporation in Kyoto, Japan was used to obtain images in the 2θ range of 5-80° at a scanning speed of 10° / min.

[0077] 7. Model 550 thermal gravimetric analyzer (TGA) from TA Instruments in New Castle, USA was used to perform thermal gravimetric analysis on 8 mg samples in an alumina crucible at a speed of 10°C / min from 25 to 750°C in a N2 flow atmosphere of 100 mL / min.

[0078] Characterization results: From the micro-morphology and surface roughness, the contact angle was greater than 150° and had certain magnetism, XRD, Fourier infrared spectroscopy and XPS spectra also proved the crystal form and surface structure of Fe3O4@C n (n=12, 14, 16, 18), it can be known that Fe3O4@C n (n=12, 14, 16, 18) has been successfully synthesized and has super-hydrophobic and magnetic effects.

[0079] Example 2

[0080] (1) Selection of beverage samples:

[0081] Five different beverages with different pH (pH 3.29, 4.49, 6.35, 6.92, 8.0) were selected, which were Sprite, tea, coffee, bottled water, and soda.

[0082] (2) Removal step:

[0083] 3.6 mL of each of the five beverages was taken, and 0.4 mL of 10 mg / mL fluorescent microplastic polystyrene (GFL-PS) standard solution was added to each of the five beverages, so that the concentration of GFL-PS in each of the five beverages was 1 mg / mL. 4 mg of Fe3O4@C 12 , Fe3O4@C 14 , Fe3O4@C 16 , and Fe3O4@C 18 was added to each beverage, a total of 20 groups, and after uniform stirring adsorption for 11 h, a magnetic field (12000 G) was applied to remove the adsorbent. At this time, the fluorescence value of the microplastic beverage solution was measured to calculate the removal rate of microplastics.

[0084] (3) Experimental results

[0085] In bottled water, the adsorption efficiency of Fe3O4@C n (n = 12, 14, 16, 18) for PS was 55.99% to 92.89%. In Sprite and soda, the removal rates of Fe3O4@C n (n = 12, 14, 16, 18) for PS were 27.76% to 64.56% and 18.67% to 90.00%, respectively. Coffee and tea are the most popular beverages in the world. In these two beverages, the PS removal rates of Fe3O4@C n were 41.04% to 50.55% and 26.45% to 62.13%, respectively. Among the five beverages, the adsorption rate of Fe3O4@C 12 was the highest among the four super-hydrophobic materials. Among them, Fe3O4@C n (n = 12, 14, 16, 18) had the highest PS adsorption efficiency in bottled water. In the other two beverages, the PS adsorption efficiency of Fe3O4@C n (n = 12, 14, 16, 18) decreased. This may be due to the fact that bottled water contains almost no other additives, which makes Fe3O4@C ndirectly exposed to the adsorption sites. Sprite and soda water contain various additives such as glucose syrup, citric acid, sodium citrate, sodium benzoate, sodium bicarbonate, food flavorings, etc. In addition, coffee and tea also contain many natural products such as fat, protein, carbohydrate, organic acid and caffeine. These additives and natural products can hinder the contact between the adsorption sites and GFL-PS, thereby reducing the adsorption efficiency of GFL-PS. Therefore, the type and composition of the sample greatly affect the removal efficiency of microplastics by Fe3O4@C n removal efficiency of microplastics.

[0086] Table 1 Fe3O4 and Fe3O4@C n (n = 12, 14, 16, 18) removal rate of microplastics in five kinds of beverages

[0087] Adsorbent material Sprite Bottled water Soda Coffee Tea Fe3O4 64.11％ 89.26％ 88.36％ 39.57％ 60.73％ Fe3O4@C 12 ]]> 64.56％ 92.89％ 90.00％ 50.55％ 62.13％ Fe3O4@C 14 ]]> 35.16％ 82.21％ 51.88％ 41.04％ 60.46％ Fe3O4@C 16 ]]> 38.95％ 80.13％ 29.47％ 45.20％ 53.44％ Fe3O4@C 18 ]]> 27.76％ 55.99％ 18.67％ 44.15％ 26.45％

[0088] Example 3

[0089] The preparation steps of the porous nanocellulose aerogel are as follows:

[0090] (1) Amide modification of carboxymethyl cellulose (CMC):

[0091] 1.0 g of CMC and 3.0 g of hexanedihydrazine (ADH) were dissolved in 50 mL of water, and 2.5 mL of 17.5 mg / mL N-hydroxysuccinimide (NHS) (dissolved in DMSO-H2O (1:1, v / v)) and 0.6 mL of 0.3 g / mL carbodiimide hydrochloride (EDC) (dissolved in DMSO-H2O (1:1, v / v)) were added in sequence. The pH of the solution was adjusted to 6.8 with HCl and NaOH, and then the solution was dialyzed, with water being changed every 4 h, the volume of water used being 100 times that of the dialysis liquid. The reaction solution after dialysis was evaporated under reduced pressure, and then the obtained viscous liquid was prepared into a CMC-NHNH2 solution with a mass fraction of 1% with water and stored at 4°C.

[0092] (2) Aldehyde-modified modification of cellulose nanocrystals (CNC):

[0093] First, 1.0 g of CNC was dissolved in 50 mL of water, and then 0.6 g of NaIO4 was added. After stirring for 2 h, 0.3 mL of ethylene glycol was quickly added to stop the reaction, and then the reaction solution was dialyzed, with water being changed every 4 h, the volume of water used being 100 times that of the dialysis liquid. Finally, the dialyzed solution was evaporated under reduced pressure, and then the obtained CNC-CHO solution with a mass fraction of 1% was prepared with water and stored at 4°C.

[0094] (3) Preparation of porous nanocellulose aerogel:

[0095] Take 5 g of CNC-CHO solution, add 5 g of the above CMC-NHNH2 solution, and shake to mix. Add 2 g of the above viscous mixed solution to a centrifuge tube, refrigerate for 6 h, and then freeze-dry for 24 h to obtain a block of sponge-like cellulose composite aerogel.

[0096] Example 4

[0097] Fe3O4@C n The preparation steps of the porous nanocellulose aerogel are as follows:

[0098] (1) Amide modification of carboxymethyl cellulose (CMC):

[0099] 1.0 g of CMC and 3.0 g of hexanedihydrazine (ADH) were dissolved in 50 mL of water, and 2.5 mL of 17.5 mg / mL N-hydroxysuccinimide (NHS) (dissolved in DMSO-H2O (1:1, v / v)) and 0.6 mL of 0.3 g / mL carbodiimide hydrochloride (EDC) (dissolved in DMSO-H2O (1:1, v / v)) were added in sequence. The pH of the solution was adjusted to 6.8 with HCl and NaOH, and then the solution was dialyzed, with water changes every 4 h, using 100 times the volume of the dialysis solution. The reaction solution after dialysis was evaporated under reduced pressure, and then the obtained viscous liquid was prepared into a CMC-NHNH2 solution with a mass fraction of 1% using water, and stored at 4°C.

[0100] (2) Aldehyde modification of cellulose nanocrystals (CNC):

[0101] First, 1.0 g of CNC was dissolved in 50 mL of water, and then 0.6 g of NaIO4 was added. After stirring for 2 h, 0.3 mL of ethylene glycol was quickly added to stop the reaction, and then the reaction solution was dialyzed, with water changes every 4 h, using 100 times the volume of the dialysis solution. Finally, the dialyzed solution was evaporated under reduced pressure, and then water was added to prepare a CNC-CHO solution with a mass fraction of 1%, and stored at 4°C.

[0102] (3) Fe3O4@C n (n = 12, 14, 16, 18) porous nanocellulose aerogel preparation:

[0103] 100 mg of Fe3O4@C n (n = 12, 14, 16, 18) was added to 5 g of CNC-CHO solution, respectively. After ultrasonic treatment for 5 min, 5 g of the above CMC-NHNH2 solution was added and shaken to mix. 2 g of the mixed solution was added to a centrifuge tube, refrigerated for 6 h, and then freeze-dried for 24 h to obtain a block of sponge-like Fe3O4@C n cellulose composite aerogel.

[0104] Example 5

[0105] (1) Removal step:

[0106] Take 3.6 mL of bottled water, add 0.4 mL of 10 mg / mL GFL-PS standard solution, so that the concentration of fluorescent microplastic PS in water is 1 mg / mL. Take 4 mg of Fe3O4@C n (n = 12, 14, 16, 18), porous nanocellulose aerogel, Fe3O4@C n @ cellulose composite aerogel Fe3O4@C n (n = 12, 14, 16, 18) adsorption experiment, uniform stirring adsorption 11 h, apply magnetic field (12000G) to remove the adsorbent, at this time measure the fluorescence value of the solution of microplastic beverage and calculate the removal rate of microplastic.

[0107] (2) The experimental results are as follows:

[0108] Table 2 Fe3O4@C n , porous nanocellulose aerogel and Fe3O4@C n @ cellulose composite aerogel removal rate of microplastics in water

[0109] Adsorbent material Bottled water Fe3O4@C 12 ]]> 92.89％ Fe3O4@C 14 ]]> 82.21％ Fe3O4@C 16 ]]> 80.13％ Fe3O4@C 18 ]]> 55.99％ Porous nanocellulose aerogel 40.13％ Fe3O4@C 12 @cellulose composite aerogel 94.38％ Fe3O4@C 14 @cellulose composite aerogel 87.82％ Fe3O4@C 16 @cellulose composite aerogel 84.29％ Fe3O4@C 18 @cellulose composite aerogel 72.57％

[0110] This kind of adsorbent (aerogel) is a kind of porous and fluffy adsorbent, after loading super-hydrophobic magnetic Fe3O4 nanoparticles, it can achieve enhanced effect and more effective adsorption of microplastics in liquid food.

[0111] Example 6

[0112] (1) The amide modification of carboxymethyl cellulose (CMC) and the aldehyde modification of cellulose nanocrystal (CNC) are consistent with Example 3.

[0113] (2) Preparation and optimization of Fe3O4@C 12 loaded porous nanocellulose aerogel:

[0114] 83.3 mg, 100 mg, 125 mg, 167 mg Fe3O4@C 12 were added to 5 g of CNC-CHO solution (material ratio was 1:60, 1:50, 1:40, 1:30) respectively. After ultrasonic treatment for 5 min, 5 g of CMC-NHNH2 solution was added and shaken uniformly. 2 g of the above viscous mixed solution was added to a centrifuge tube, refrigerated for 6 h, and then freeze-dried for 24 h, to obtain four kinds of blocky sponge-like (material ratio was 1:60, 1:50, 1:40, 1:30) Fe3O4@C 12Cellulose composite aerogel.

[0115] (3) removing step:

[0116] Take 3.6mL of bottled water, add 0.4mL of 10mg / mL GFL-PS standard solution, so that the concentration of fluorescent microplastic PS in water is 1mg / mL. Take 4mg of Fe3O4@C 12 @Cellulose composite aerogel for adsorption experiment, uniform stirring adsorption 11h, apply magnetic field (12000G) to remove the adsorbent, at this time measure the fluorescence value of the solution of microplastic beverage and calculate the removal rate of microplastic.

[0117] (4) the experimental results are as follows:

[0118] Table 3 (material ratio 1:60, 1:50, 1:40, 1:30) Fe3O4@C n @Cellulose composite aerogel in water for microplastic removal rate

[0119] Adsorbent material Bottled water (1 :60) Fe3O4@C 12 @Cellulose composite aerogels]] 93.20％ (1 :50) Fe3O4@C 12 @Cellulose composite aerogel 94.38％ (1 :40) Fe3O4@C 12 @Cellulose composite aerogel 94.61％ (1 :30) Fe3O4@C 12 @Cellulose composite aerogel 93.45％

[0120] According to the data in table 3, it can be found that the removal rate of microplastic increases with the increase of the amount of Fe3O4@C 12 , but when the material ratio is 1:40, the removal rate increases not obviously, and when the material ratio is 1:30, the removal rate begins to decline, so the material ratio of 1:50~40 is selected to prepare Fe3O4@C 12 @Cellulose composite aerogel is more appropriate. In addition, from the economic point of view, the removal rate of microplastic is higher and economic when the material ratio is 1:50.

[0121] Those skilled in the art should understand that the above description is only a specific embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a composite aerogel material for removing microplastics from water, characterized in that, Includes the following steps: (1) Amide modification of carboxymethyl cellulose: CMC and hexamethylenedihydrazine were dissolved in water, and N-hydroxysuccinimide solution and carbodiimide hydrochloride solution were added and mixed to obtain a reaction solution. The pH of the reaction solution was then adjusted to 6.5-7, and the reaction solution was dialyzed. The dialyzed reaction solution was evaporated under reduced pressure to obtain a viscous liquid. The obtained viscous liquid was then diluted with water to prepare a CMC-NHNH2 solution. The mass ratio of CMC to hexamethylenedihydrazine was 1:2-4; the mass ratio of CMC to water was 1:40-60; the concentration of N-hydroxysuccinimide solution was 15-20 mg / mL; the mass-volume ratio of CMC to N-hydroxysuccinimide solution was 1 g:2-4 mL; the concentration of carbodiimide hydrochloride solution was 0.1-0.5 g / mL; the mass-volume ratio of CMC to carbodiimide hydrochloride solution was 1 g:0.4-0.8 mL; and the mass fraction of the CMC-NHNH2 solution was 0.5-1.5%. (2) Aldehyde modification of cellulose nanocrystals: CNC was dissolved in water, then sodium periodate was added, and after stirring, ethylene glycol was added to stop the reaction, yielding a reaction solution. The reaction solution was then dialyzed, and the dialyzed reaction solution was evaporated under reduced pressure and then diluted with water to prepare a CNC-CHO solution. The mass ratio of CNC to water was 1:40~60; the mass ratio of CNC to sodium periodate was 1:0.4~0.8; the mass-volume ratio of CNC to ethylene glycol was 1 g:0.2~0.4 mL; and the mass fraction of the CNC-CHO solution was 0.5~1.5%. (3) Preparation of porous nanocellulose aerogel loaded with superhydrophobic magnetic nano-iron oxide: Fe3O4@C 12 Add the CNC-CHO solution obtained in step (2), sonicate, then add the CMC-NHNH2 solution obtained in step (1), shake to mix, refrigerate, and then freeze-dry to obtain the composite aerogel material; the Fe3O4@C 12 The mass ratio of Fe3O4 to CNC-CHO solution is 1:40; 12 The mass ratio of CMC-NHNH2 solution to CMC-NHNH2 solution is 1:40; The Fe3O4@C mentioned in step (3) 12 The preparation method includes the following steps: S1. Cleaning of magnetic nano-iron oxide The magnetic nano-iron oxide was immersed in dilute hydrochloric acid solution to remove surface contaminants and impurities. After washing, it was taken out and then immersed in acetone. After washing, it was taken out and then immersed in ethanol solution. After washing, it was taken out and dried to obtain clean magnetic nano-iron oxide. S2. Preparation of long-chain fatty acid solution Prepare a 0.5 mol / L lauric acid solution using anhydrous ethanol as the solvent; S3. Synthesis of superhydrophobic magnetic nano-iron oxide 0.5 g of the clean magnetic Fe3O4 nanoparticles obtained in step S1 were immersed in 20 mL of the lauric acid solution obtained in step S2, heated to 80 °C for 1 h, and then dried for 1 h to obtain the superhydrophobic magnetic nanomaterial—lauric acid-modified magnetic Fe3O4 nanoparticles Fe3O4@C. 12 .

2. A composite aerogel material prepared according to the method of claim 1.

3. The application of the composite aerogel material as described in claim 2 in the field of microplastic removal.

Images