Micro-plastic enriched fiber as well as preparation method and application thereof
By preparing modified MXene suspension-treated cellulose nanocrystals from sea squirts, the problem of enrichment and detection of nanoscale microplastics in complex environments has been solved, realizing an efficient, rapid, and environmentally friendly method for microplastic detection, suitable for non-laboratory environments.
Patent Information
- Application Number
- CN202511630331.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-01-30
AI Technical Summary
Existing technologies are insufficient for the efficient enrichment and detection of nanoscale microplastics in complex environments. Traditional methods are inefficient and susceptible to contamination, and laboratory analysis is time-consuming, making it difficult to meet the needs of practical applications.
Microfluidic spinning technology was used to prepare cellulose nanocrystals from sea squirts, and microplastic-enriched fibers were prepared by treatment with modified MXene suspension. The microplastic enrichment of the sea squirt cellulose nanocrystals modified with modified MXene suspension was carried out by using the modified MXene suspension to enhance the Raman spectral signal.
It achieves efficient enrichment and detection of nanoscale microplastics in complex environments, enhances Raman spectral signals by 5 times, improves detection sensitivity and accuracy, shortens analysis time, is suitable for non-laboratory environments, meets the needs of rapid detection, and is environmentally friendly with no secondary pollution.
Smart Images
Figure CN121428822A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of microplastic adsorbent, in particular to a microplastic enrichment fiber and a preparation method and application thereof. BACKGROUND
[0002] Microplastic pollution has become a major environmental concern, posing a serious threat to ecosystems and human health. However, effective enrichment, detection, and removal of microplastics face many challenges. Currently, the analysis methods for microplastics are limited to laboratory environments and often take a long time, which severely limits their application in actual pollution samples.
[0003] Currently, the analysis and detection methods for microplastics mainly include the following types: ① morphological analysis: mainly through visual observation, microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), etc., to observe the shape, size, and color of microplastics, and provide high-resolution images. ② spectroscopic analysis: including Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and near-infrared hyperspectral imaging technology (NIR hyperspectral imaging), etc., which can provide information on the chemical composition and molecular structure of microplastics, and is a key means for identifying the polymer type of microplastics. Among them, Raman spectroscopy can detect and classify microplastics as small as microns due to its unique fingerprint information. ③ thermal analysis: including thermal desorption-gas chromatography-mass spectrometry (TDS-GC-MS) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), which are used to identify additives, plasticizers, or polymer structures in microplastics. ④ new methods: including plasmonic resonance-based sensor technology and microfluidic chip technology, aiming to improve detection sensitivity, throughput, and automation. Although the above methods have various advantages, they still face challenges in analyzing and detecting microplastics in complex environments (such as polluted water bodies), especially for nanoscale microplastics. Due to their small size and strong dispersibility, the above traditional analysis and detection methods often fail to effectively identify and quantify nanoscale microplastics, and the traditional filtration + scanning method is inefficient and easily contaminated.
[0004] Therefore, it is of great significance for environmental governance to develop a microplastic enrichment and detection method that can be applied to complex environments and is universally applicable and efficient even for nanoscale microplastics. SUMMARY
[0005] The present application aims to provide a microplastic enrichment fiber and a preparation method and application thereof to overcome the shortcomings of the prior art.
[0006] To achieve the above-mentioned application purposes, the present application provides the following technical solutions: This invention provides a method for preparing microplastic-enriched fibers, comprising the following steps: 1) Microfluidic spinning was performed on the cellulose solution of sea squirt to obtain cellulose nanocrystalline fibers of sea squirt; The MXene suspension was modified to obtain modified MXene, and the modified MXene was dispersed in water to obtain a modified MXene suspension. 2) Soaking sea squirt cellulose nanocrystal fibers in modified MXene suspension yields microplastic-enriched fibers.
[0007] Preferably, the microfluidic spinning in step 1) is performed using a single-sheath microfluidic chip, by injecting a sea squirt cellulose solution into the core layer of the single-sheath microfluidic chip and injecting hydrochloric acid into the sheath layer of the single-sheath microfluidic chip. The mass fraction of the sea squirt cellulose solution is 0.5-2%, and the flow rate of the sea squirt cellulose solution is 350-400 μL / min; The concentration of hydrochloric acid is 3~8 mol / L, and the flow rate of hydrochloric acid is 430~480 μL / min.
[0008] Preferably, the modifier used in step 1) is polydiallyl dimethylammonium chloride, and the mass ratio of the modifier to MXene in the MXene suspension is 8~12:1; The modification time is 20-28 hours.
[0009] Preferably, the mass-to-volume ratio of the modified MXene to water in step 1) is 1 g: 45~55 mL.
[0010] Preferably, the mass-to-volume ratio of the sea squirt cellulose nanocrystals and the modified MXene suspension in step 2) is 0.1 mg: 0.5~2 mL; Step 2) The soaking time is 8-15 minutes.
[0011] Preferably, the cellulose in the succubus cellulose solution in step 1) is obtained by sequentially soaking, bleaching, and acid hydrolyzing succubi in an alkaline solution.
[0012] Preferably, the alkaline solution used for the alkaline soaking is a sodium hydroxide solution with a mass fraction of 3-7%, and the mass ratio of sea squirt to sodium hydroxide in the sodium hydroxide solution is 1000:100-200. The bleaching agent used is hydrogen peroxide, and the mass ratio of sea squirt to hydrogen peroxide is 1000:30~40; The acid hydrolysis was performed using sulfuric acid, with a mass fraction of 40-60%, and the mass ratio of sea squirt to sulfuric acid was 2:80-120.
[0013] The present invention also provides microplastic enriched fibers prepared by the aforementioned preparation method.
[0014] The present invention also provides the application of the aforementioned microplastic enrichment fiber in the enrichment and detection of microplastics in polluted water bodies.
[0015] Preferably, the microplastics include micron-sized microplastics and nano-sized microplastics.
[0016] The beneficial effects of this invention are: The microplastic enrichment fiber of this invention exhibits excellent microplastic adsorption performance, efficiently capturing nanoscale microplastics in complex environments with an adsorption capacity of 845.1 mg / g. In Raman spectroscopy analysis, the microplastic enrichment fiber can enhance the Raman spectral signal by up to 5 times, not only improving detection sensitivity but also enabling quantitative analysis of microplastics, thus enhancing the accuracy and reliability of detection technology, filling a technological gap, and playing a significant role in the monitoring and control of microplastics. Compared with traditional methods, using the microplastic enrichment fiber of this invention for microplastic enrichment and detection is more convenient and suitable for use in non-laboratory environments, enabling wider promotion and popularization of routine microplastic monitoring. The method of this invention significantly shortens the time from sample collection to result analysis, improves detection efficiency, and meets the demand for rapid detection in practical applications. The raw materials and preparation method used in this invention are more environmentally friendly and will not cause secondary pollution to the environment. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of a single-sheath microfluidic chip; Figure 2 Scanning electron microscope image of the microplastic-enriched fibers prepared in Example 1; Figure 3 Atomic force microscopy (AFM) image of the modified MXene (P-MXene nanosheets) prepared in Example 1; Figure 4 Scanning electron microscope image of TCNC cellulose nanocrystals prepared in Example 1; Figure 5 Image showing the knotting of the microplastic-enriched fibers prepared in Example 1 under polyoxymethylene (POM) fibers; Figure 6 Zeta potential diagrams of tunicate cellulose nanocrystal fibers TCNC, microplastic-enriched fibers TCNC / P-MXene, and three microplastics prepared in Example 1; Figure 7 Raman spectra of Rhodamine B for the cellulose nanocrystal fibers TCNC and microplastic enriched fibers TCNC / P-MXene prepared in Example 1; Figure 8The bar chart shows the change in Raman signal intensity of the microplastic-enriched fibers prepared in Example 1 after adsorption in an aqueous solution of microplastics (50 nm polystyrene) at a concentration of 0.1 mg / ml as a function of adsorption time. Figure 9 These are scanning electron microscope (SEM) images of the microplastic-enriched fibers prepared in Example 1 and Comparative Examples 1-2 after adsorbing different microplastics. Figure 10 The Raman spectra of the microplastic enrichment fibers prepared in Example 1 after adsorbing different concentrations of microplastics are shown. Detailed Implementation
[0018] This invention provides a method for preparing microplastic-enriched fibers, comprising the following steps: 1) Microfluidic spinning was performed on the cellulose solution of sea squirt to obtain cellulose nanocrystalline fibers of sea squirt; The MXene suspension was modified to obtain modified MXene, and the modified MXene was dispersed in water to obtain a modified MXene suspension. 2) Soaking sea squirt cellulose nanocrystal fibers in modified MXene suspension yields microplastic-enriched fibers.
[0019] In this invention, the microfluidic spinning in step 1) is preferably carried out through a single-sheath microfluidic chip, wherein a sea squirt cellulose solution is injected into the core layer of the single-sheath microfluidic chip and hydrochloric acid is injected into the sheath layer of the single-sheath microfluidic chip; The mass fraction of the sea squirt cellulose solution is preferably 0.5-2%, more preferably 0.8-1.5%, and even more preferably 1-1.2%; the flow rate of the sea squirt cellulose solution is preferably 350-400 μL / min, more preferably 360-390 μL / min, and even more preferably 370-380 μL / min. The concentration of hydrochloric acid is preferably 3~8 mol / L, more preferably 4~7 mol / L, and even more preferably 5~6 mol / L; the flow rate of hydrochloric acid is preferably 430~480 μL / min, more preferably 440~470 μL / min, and even more preferably 450~460 μL / min.
[0020] In this invention, the modifier used in step 1) is preferably polydiallyldimethylammonium chloride, and the mass ratio of the modifier to MXene in the MXene suspension is preferably 8~12:1, more preferably 9~11:1, and even more preferably 10:1; The modification time is preferably 20-28 hours, more preferably 22-26 hours, and even more preferably 24 hours. By modifying the MXene suspension with polydiallyldimethylammonium chloride, a modified MXene suspension with a positively charged surface can be obtained.
[0021] In this invention, stirring is preferably performed during the modification process, and the stirring speed is preferably 370~420 rpm, more preferably 380~410 rpm, and even more preferably 390~400 rpm.
[0022] In this invention, after the modification in step 1), centrifugation is preferably performed to obtain modified MXene; The centrifugation speed is preferably 3000~4000 rpm, more preferably 3200~3800 rpm, and even more preferably 3500 rpm; the centrifugation time is preferably 0.5~2h, more preferably 0.8~1.5h, and even more preferably 1~1.2h.
[0023] In this invention, the mass-to-volume ratio of modified MXene and water in step 1) is preferably 1g:45~55mL, more preferably 1g:48~52mL, and even more preferably 1g:50mL.
[0024] In this invention, the dispersion in step 1) is preferably ultrasonic dispersion, and the ultrasonic dispersion power is preferably 370~410W, more preferably 380~400W, and even more preferably 390W; the ultrasonic dispersion time is preferably 3~8min, more preferably 4~7min, and even more preferably 5min.
[0025] In this invention, the mass-to-volume ratio of the sea squirt cellulose nanocrystals and the modified MXene suspension in step 2) is preferably 0.1 mg: 0.5~2 mL, more preferably 0.1 mg: 0.8~1.5 mL, and even more preferably 0.1 mg: 1 mL; The soaking time in step 2) is preferably 8-15 min, more preferably 9-13 min, and even more preferably 10-12 min.
[0026] In this invention, the sea squirt cellulose in the sea squirt cellulose solution in step 1) is preferably obtained by sequentially soaking, bleaching, and acid hydrolyzing sea squirts in alkaline solution.
[0027] In this invention, the alkaline solution used for the alkaline soaking is preferably a sodium hydroxide solution, and the mass fraction of the sodium hydroxide solution is preferably 3-7%, more preferably 4-6%, and even more preferably 5%; the mass ratio of sea squirt to sodium hydroxide in the sodium hydroxide solution is preferably 1000:100-200, more preferably 1000:120-180, and even more preferably 1000:150. The preferred bleaching agent used for bleaching is hydrogen peroxide, and the mass ratio of sea squirt to hydrogen peroxide is preferably 1000:30~40, more preferably 1000:32~38, and even more preferably 1000:34~36; The reagent used for acid hydrolysis is preferably sulfuric acid, with a mass fraction of 40-60%, more preferably 45-55%, and even more preferably 50%. The mass ratio of sea squirt to sulfuric acid is preferably 2:80-120, more preferably 2:90-110, and even more preferably 2:100.
[0028] In this invention, the temperature of the alkaline solution soaking is preferably 75~85℃, more preferably 78~82℃, and even more preferably 80℃; the soaking time is preferably 20~28h, more preferably 22~26h, and even more preferably 24h. During the alkaline soaking process, stirring is performed, preferably at a speed of 270~320 rpm, more preferably at 280~310 rpm, and even more preferably at 290~300 rpm.
[0029] In this invention, after the alkaline soaking is completed, the product is preferably washed and dried to obtain tunicate cellulose intermediate 1; The washing is preferably done with water, and the washing is preferably done until the washing solution is neutral. The drying temperature is preferably 75~85℃, more preferably 80℃; the drying time is preferably 2~4h, more preferably 3h. The process of soaking, washing, and drying in alkaline solution is preferably repeated 2 to 4 times, and more preferably 3 times.
[0030] In this invention, the bleaching temperature is preferably 75~85℃, more preferably 78~82℃, and even more preferably 80℃; the bleaching time is preferably 1~5h, more preferably 2~4h, and even more preferably 3h. During the bleaching process, stirring is performed, preferably at a speed of 270-320 rpm, more preferably at 280-310 rpm, and even more preferably at 290-300 rpm.
[0031] In this invention, the bleaching is carried out in a bleaching agent solution, and the pH value of the bleaching agent solution is preferably 7.5~8.5, more preferably 7.8~8.2, and even more preferably 8; Sodium hydroxide solution is preferably used to adjust the pH value of the bleach solution.
[0032] In this invention, after bleaching, it is preferable to wash, and after washing, the bleaching and washing process is repeated, preferably 2 to 4 times, and more preferably 3 times. The washing process is preferably carried out with a neutral washing solution; after washing, the product is preferably dried to obtain white sea squirt fibers; the drying temperature is preferably 75~85℃, more preferably 80℃; the drying time is preferably 2~4h, more preferably 3h.
[0033] In this invention, the acid hydrolysis time is preferably 10-16 hours, more preferably 12-14 hours; stirring is preferably carried out during the acid hydrolysis process, and the stirring speed is preferably 270-320 rpm, more preferably 280-310 rpm, and even more preferably 290-300 rpm.
[0034] In this invention, after the acid hydrolysis is completed, the sea squirt cellulose is preferably washed and vacuum dried sequentially. After acid hydrolysis, washing is preferably performed until the pH of the washing solution is 5. The temperature of vacuum drying is preferably 50~60℃, more preferably 53~57℃, and even more preferably 55℃. The vacuum degree of vacuum drying is preferably 0.06~0.09MPa, more preferably 0.07~0.08MPa, and even more preferably 0.075MPa. The vacuum drying time is preferably 260~340min, more preferably 280~320min, and even more preferably 300min.
[0035] In this invention, the method for preparing the MXene suspension preferably includes the following steps: ① Lithium fluoride, hydrochloric acid, Ti3AlC2 and water are mixed and reacted to obtain MXene; ② Disperse MXene into water using ultrasound to obtain an MXene suspension.
[0036] In this invention, the reaction temperature is preferably 30~40℃, more preferably 32~38℃, and even more preferably 35℃; the reaction time is preferably 32~40h, more preferably 34~38h, and even more preferably 35~36h. Stirring is preferably performed during the reaction process, and the stirring speed is preferably 520~570 rpm, more preferably 530~560 rpm, and even more preferably 540~550 rpm.
[0037] In this invention, after the reaction is completed, the product is preferably washed and centrifuged to obtain MXene; The centrifugation speed is preferably 8000~12000 rpm, more preferably 9000~11000 rpm, and even more preferably 10000 rpm; preferably, the centrifugation is performed until the supernatant is neutral.
[0038] In this invention, the ultrasonic dispersion in step ② is preferably carried out in a nitrogen atmosphere, the ultrasonic dispersion power is preferably 370~410W, more preferably 380~400W, and even more preferably 390W; the ultrasonic dispersion time is preferably 1~3h, more preferably 1.5~2.5h, and even more preferably 2h. The preferred mass-to-volume ratio of MXene to water in step ② is 0.1~1 mg:1 mL, more preferably 0.3~0.8 mg:1 mL, and even more preferably 0.5 mg:1 mL.
[0039] The present invention also provides microplastic enriched fibers prepared by the aforementioned preparation method.
[0040] The present invention also provides the application of the aforementioned microplastic enrichment fiber in the enrichment and detection of microplastics in polluted water bodies.
[0041] In this invention, the microplastics preferably include micron-sized microplastics and nano-sized microplastics.
[0042] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0043] In the embodiments and comparative examples of this invention, the preparation method of sea squirt cellulose is as follows: The sea squirt is dissected, retaining the outer capsule, which is then cut into small pieces and dried. At 80°C, 1000g of the dried sea squirt outer capsule is taken and soaked in 3kg of a 5% sodium hydroxide solution, stirred at 300rpm for 24 hours. After soaking, the sea squirt outer capsule is removed, washed with deionized water until the pH of the washing solution is 7, and dried at 80°C for 3 hours. The soaking, washing, and drying steps are repeated three times to obtain sea squirt cellulose intermediate 1. At 80°C, sea squirt cellulose intermediate 1 is placed in 3kg of hydrogen peroxide (the hydrogen peroxide has a hydrogen peroxide content of 1.2%, and the pH of the hydrogen peroxide is adjusted to 8 using a 0.1mol / L sodium hydroxide solution), stirred at 300rpm for bleaching for 3 hours. After bleaching, sea squirt cellulose intermediate 1 is removed and washed with deionized water until the washing solution is neutral. The bleaching and washing process was repeated three times, and finally dried at 80℃ for 3 hours to obtain white sea squirt fibers. The white sea squirt fibers were crushed to obtain cellulose powder. 2g of the cellulose powder was placed in 100g of sulfuric acid (50% by mass) and acid-hydrolyzed at 300rpm for 12 hours. After acid hydrolysis, the solution was washed with deionized water until the pH of the washing solution reached 5, and then dried at 55℃ and 0.075MPa vacuum for 300 minutes to obtain sea squirt cellulose.
[0044] The MXene suspension was prepared as follows: 1.6 g of lithium fluoride, 15 mL of hydrochloric acid (37% by mass), and 5 mL of deionized water were stirred until homogeneous. Then, 1 g of Ti3AlC2 was added, and the mixture was stirred at 550 rpm for 35 h in a water bath at 35 °C. After the reaction, the suspension was washed with deionized water and centrifuged at 10,000 rpm until the supernatant was neutral, yielding MXene. Under a nitrogen atmosphere, MXene was dispersed in deionized water (MXene to deionized water mass-to-volume ratio of 0.5 mg:1 mL) and ultrasonically dispersed at 400 W for 2 h to obtain the MXene suspension.
[0045] Example 1
[0046] 2 g of sea squirt cellulose was dispersed in 200 mL of deionized water to obtain a 1% (w / w) sea squirt cellulose solution. Using a single-sheath microfluidic chip, the sea squirt cellulose solution was injected into the core layer at a flow rate of 390 μL / min, and 5 mol / L hydrochloric acid was injected into the sheath layer at a flow rate of 450 μL / min. The regenerated sea squirt cellulose nanocrystals (TCNC) were collected. 20 mL of MXene suspension was mixed with 2 mL of a 5% (w / w) polydiallyldimethylammonium chloride solution (the density of the polydiallyldimethylammonium chloride solution was 1.01 g / mL). The mixture was stirred at 400 rpm for 24 h for modification, followed by centrifugation at 3500 rpm for 1 h to obtain modified MXene (P-MXene nanosheets). The modified MXene was dispersed in deionized water (the mass-to-volume ratio of modified MXene to deionized water was 1 g:50 mL) and ultrasonically dispersed at 400 W for 5 min to obtain a modified MXene suspension. Cut the sea squirt cellulose nanocrystal fibers into 1cm pieces and soak them in a modified MXene suspension. The mass-to-volume ratio of the sea squirt cellulose nanocrystal fibers to the modified MXene suspension is 0.1mg:1mL. After soaking for 10min, the fibers are removed and air-dried to obtain microplastic-enriched fibers (TCNC / P-MXene).
[0047] Figure 1 This is a schematic diagram of a single-sheath microfluidic chip. Figure 1 It can be seen that, due to the symmetrical structure of the sheath channel, the injection of sea squirt cellulose solution into the core layer and hydrochloric acid into the sheath layer can generate shear force, which can improve the orientation of cellulose fibers during the "sol-gel" transformation process, and is conducive to the formation of surface wrinkled structures for adsorbing microplastics.
[0048] Figure 2 The image shows a scanning electron microscope (SEM) image of the microplastic-enriched fibers prepared in Example 1.
[0049] Figure 3Atomic force microscopy (AFM) image of the modified MXene (P-MXene nanosheets) prepared in Example 1. Figure 3 It can be clearly seen that the thickness of the P-MXene nanosheets is only 4.18 nm. The thinner P-MXene nanosheets have a larger specific surface area, which can provide sufficient active sites and maintain a certain conductivity, effectively enhancing the Raman spectral signal.
[0050] Figure 4 Scanning electron microscope image of the cellulose nanocrystals (TCNC) prepared in Example 1.
[0051] Figure 5 The image shows the knotted microplastic-enriched fibers prepared in Example 1 under polyoxymethylene (POM) fibers. Figure 5 The microplastic-enriched fibers exhibit flexibility.
[0052] Figure 6 Zeta potential diagrams of the tunicate cellulose nanocrystalline fibers TCNC, microplastic-enriched fibers TCNC / P-MXene, and three microplastics prepared in Example 1. Figure 6 It can be seen that the three types of microplastics carry negative charges, while the surface of the microplastic-enriched fiber carries positive charges, which can effectively adsorb the microplastics.
[0053] Figure 7 Raman spectra of Rhodamine B for the tunicate cellulose nanocrystalline fibers TCNC and microplastic-enriched fibers TCNC / P-MXene prepared in Example 1. Figure 7 It can be seen that the Raman signal intensity of the microplastic-enriched fibers is significantly higher than that of the sea squirt cellulose nanocrystal fibers. This result indicates that soaking in a positively charged modified MXene suspension is a key step in enhancing the Raman spectral intensity.
[0054] Example 2
[0055] 1 g of sea squirt cellulose was dispersed in 200 mL of deionized water to obtain a 0.5% (w / w) sea squirt cellulose solution. Using a single-sheath microfluidic chip, the sea squirt cellulose solution was injected into the core layer at a flow rate of 350 μL / min, and 8 mol / L hydrochloric acid was injected into the sheath layer at a flow rate of 480 μL / min. The regenerated sea squirt cellulose nanocrystals were collected. 20 mL of MXene suspension was mixed with 2 mL of a 5% (w / w) polydiallyldimethylammonium chloride solution (the density of the polydiallyldimethylammonium chloride solution was 1.01 g / mL). The mixture was stirred at 370 rpm for 28 h for modification, followed by centrifugation at 400 rpm for 0.5 h to obtain modified MXene. The modified MXene was dispersed in deionized water (the mass-to-volume ratio of modified MXene to deionized water was 1 g:55 mL) and ultrasonically dispersed at 400 W for 3 min to obtain a modified MXene suspension. Sea squirt cellulose nanocrystal fibers were cut into 1cm pieces and soaked in a modified MXene suspension. The mass-to-volume ratio of sea squirt cellulose nanocrystal fibers to modified MXene suspension was 0.1mg:0.5mL. After standing for 15 minutes, the fibers were removed and air-dried to obtain microplastic-enriched fibers.
[0056] Example 3
[0057] 4 g of sea squirt cellulose was dispersed in 200 mL of deionized water to obtain a 2% (w / w) sea squirt cellulose solution. Using a single-sheath microfluidic chip, the sea squirt cellulose solution was injected into the core layer at a flow rate of 400 μL / min, and 3 mol / L hydrochloric acid was injected into the sheath layer at a flow rate of 430 μL / min. The regenerated sea squirt cellulose nanocrystals were collected. 20 mL of MXene suspension was mixed with 2 mL of a 5% (w / w) polydiallyldimethylammonium chloride solution (the density of the polydiallyldimethylammonium chloride solution was 1.01 g / mL). The mixture was stirred at 420 rpm for 20 h for modification, followed by centrifugation at 3000 rpm for 2 h to obtain modified MXene. The modified MXene was dispersed in deionized water (the mass-to-volume ratio of modified MXene to deionized water was 1 g:45 mL) and ultrasonically dispersed at 400 W for 8 min to obtain a modified MXene suspension. Sea squirt cellulose nanocrystal fibers were cut into 1cm pieces and soaked in a modified MXene suspension. The mass-to-volume ratio of sea squirt cellulose nanocrystal fibers to modified MXene suspension was 0.1mg:2mL. After standing for 8 minutes, the fibers were removed and air-dried to obtain microplastic-enriched fibers.
[0058] Comparative Example 1
[0059] 2 g of sea squirt cellulose was dispersed in 200 mL of deionized water to obtain a 1% (w / w) sea squirt cellulose solution. Using a single-sheath microfluidic chip, the sea squirt cellulose solution was injected into the core layer at a flow rate of 390 μL / min, and 5 mol / L hydrochloric acid was injected into the sheath layer at a flow rate of 450 μL / min. The regenerated sea squirt cellulose nanocrystals (TCNC) were collected. Uncomposite microplastic-enriched fibers (TCNC) were obtained.
[0060] Comparative Example 2
[0061] 2g of tunicate cellulose was dispersed in 200mL of deionized water to obtain a 1% (w / w) tunicate cellulose solution. Using a single-sheath microfluidic chip, the tunicate cellulose solution was injected into the core layer at a flow rate of 390μL / min, and 5mol / L hydrochloric acid was injected into the sheath layer at a flow rate of 450μL / min. The regenerated tunicate cellulose nanocrystalline fibers (TCNC) were collected. The tunicate cellulose nanocrystalline fibers were cut into 1cm pieces and immersed in an unmodified MXene suspension with a mass-to-volume ratio of 0.1mg:1mL. After standing for 10min, the fibers were removed and air-dried to obtain unmodified microplastic-enriched fibers (TCNC / MXene).
[0062] Microplastic-enriched fibers prepared in Example 1 and Comparative Examples 1 and 2 were used to adsorb and detect microplastics. Specifically, 0.317 mg of fiber was immersed in 100 mL of an aqueous solution with a microplastic concentration of 0.1 mg / mL at 25°C. After standing for 50 min, the fiber was removed. Raman spectroscopy analysis was performed on the fibers. The microplastics were identified as 50 nm polystyrene, 100 nm polystyrene, or 100 nm polyethylene terephthalate.
[0063] Figure 8 The bar chart shows the change in Raman signal intensity of the microplastic-enriched fibers prepared in Example 1 after adsorption in an aqueous solution of microplastics (50 nm polystyrene) at a concentration of 0.1 mg / ml as a function of adsorption time.
[0064] Figure 9 Scanning electron microscope (SEM) images of the microplastic-enriched fibers prepared in Examples 1 and 1-2 after adsorbing different microplastics. Figure 9It can be seen that the microplastic enrichment fiber prepared in Example 1 has a significantly higher adsorption and enrichment effect on microplastics than that in Comparative Examples 1 and 2. This result indicates that the presence of positively charged modified MXene nanosheets is indispensable for microplastic detection. MXene nanosheets possess Raman enhancement effects, which are essential for the detection of nanoscale microplastics. Other positively charged suspensions may adsorb nanoplastics, but Raman spectroscopy analysis cannot be performed, and the aforementioned effect cannot be achieved.
[0065] The microplastic-enriched fibers prepared in Example 1 were subjected to adsorption in 50 nm polystyrene aqueous solutions of different concentrations. Specifically, at 25°C, 0.317 g of microplastic-enriched fibers were immersed in 100 mL of 50 nm polystyrene aqueous solutions of different concentrations, and the fibers were removed after standing for 50 min for adsorption. The fibers were then subjected to Raman spectroscopy analysis.
[0066] Figure 10 The images show the Raman spectra of the microplastic-enriched fibers prepared in Example 1 after adsorbing different concentrations of microplastics. Figure 10 It can be seen that as the concentration of microplastics (50nm polystyrene) decreases, the concentration of microplastics in fibers at 1000 cm⁻¹ decreases. -1 The Raman signal intensity at the concentration also decreased until it completely disappeared at a concentration of 2.5 ng / mL. This result indicates that the detection limit for microplastic-enriched fibers is 2.5 ng / mL.
[0067] As can be seen from the above embodiments, the present invention provides microplastic enrichment fibers, their preparation methods, and applications. The microplastic enrichment fibers still exhibit excellent microplastic adsorption performance and Raman signal intensity for nanoscale microplastics with concentrations as low as 2.5 ng / mL, with an adsorption capacity reaching 845.1 mg / g. This improves the detection sensitivity and accuracy of microplastics. Furthermore, the method is applicable not only to laboratory environments but also to non-laboratory environments, meeting the needs of daily monitoring and rapid analysis of microplastics in practical applications.
[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method of preparing a microplastic-enriched fiber, characterized by, The preparation method comprises the following steps: 1) performing microfluidic spinning on a sea cucumber cellulose solution to obtain sea cucumber cellulose nanocrystal fibers; The MXene suspension is modified to obtain modified MXene, and the modified MXene is dispersed in water to obtain a modified MXene suspension; 2) soaking the sea cucumber cellulose nanocrystal fibers in the modified MXene suspension to obtain the microplastic enrichment fibers.
2. The production method according to claim 1, characterized by, The microfluidic spinning in step 1) is performed by a single-sheath microfluidic chip, sea cucumber cellulose solution is injected into the core layer of the single-sheath microfluidic chip, and hydrochloric acid is injected into the sheath layer of the single-sheath microfluidic chip; The mass fraction of the sea cucumber cellulose solution is 0.5-2%, and the flow rate of the sea cucumber cellulose solution is 350-400 μL / min; The concentration of the hydrochloric acid is 3-8 mol / L, and the flow rate of the hydrochloric acid is 430-480 μL / min.
3. The production method according to claim 1 or 2, characterized by, The modifier used in the modification in step 1) is polydiallyldimethylammonium chloride, and the mass ratio of the modifier to MXene in the MXene suspension is 8-12:1; The modification time is 20-28 h.
4. The production method according to claim 3, characterized by, The mass-to-volume ratio of the modified MXene to water in step 1) is 1 g:45-55 mL.
5. The preparation method according to claim 4, characterized in that, The mass-to-volume ratio of the sea cucumber cellulose nanocrystal fibers to the modified MXene suspension in step 2) is 0.1 mg:0.5-2 mL; The soaking time in step 2) is 8-15 min.
6. The production method according to claim 4 or 5, characterized by, The sea cucumber cellulose in the sea cucumber cellulose solution in step 1) is prepared by sequentially immersing sea cucumber in lye, bleaching, and acidolysis.
7. The preparation method according to claim 6, characterized in that, The lye used in the lye immersion is sodium hydroxide solution, the mass fraction of the sodium hydroxide solution is 3-7%, and the mass ratio of the sea cucumber to sodium hydroxide in the sodium hydroxide solution is 1000:100-200; The bleaching agent used in the bleaching is hydrogen peroxide, and the mass ratio of the sea cucumber to hydrogen peroxide is 1000:30-40; The reagent used in the acidolysis is sulfuric acid, the mass fraction of the sulfuric acid is 40-60%, and the mass ratio of the sea cucumber to sulfuric acid is 2:80-120.
8. The microplastic enrichment fibers prepared by the preparation method in any one of claims 1-7.
9. The use of the microplastic enrichment fibers in claim 8 in enriching and detecting microplastics in contaminated water bodies.
10. Use of the microplastic-enriching fiber according to claim 9 for the enrichment and detection of microplastics in a contaminated water body, characterized in that, The microplastics comprise micro-sized microplastics and nano-sized microplastics.