An organic-inorganic hybrid fiber for microplastic adsorption and a method of preparing the same

Abstract

The application discloses an organic-inorganic hybrid fiber for microplastic adsorption and a preparation method thereof, and comprises the following steps: (1) washing waste acetate fiber and reserving it for use; (2) placing the waste acetate fiber in an amine compound solution, adding glutaraldehyde solution, and reacting; (3) placing the waste acetate fiber in a mixed solution of a polyphenol solution and a Tris-HCl buffer solution; and (4) treating the waste acetate fiber with a mixed solution of a calcium precursor, sodium hydroxide and a phosphorus source, and finally obtaining the organic-inorganic hybrid fiber. The application adopts the method of "waste treatment with waste" to adsorb and remove microplastics, and provides a theoretical basis and technical support for value-added conversion of bio-based waste into high-value-added and environmentally friendly functional adsorption materials, and provides a new idea for development and application of microplastic adsorption materials.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of waste fiber functionalization preparation and microplastic adsorbent, more specifically, relates to an organic-inorganic hybrid fiber for microplastic adsorption and a preparation method thereof. BACKGROUND

[0002] Plastics are the most widely used, most durable, and cheapest and most common materials in our lives, playing a crucial role. Most plastics will undergo decomposition, fragmentation and degradation in the environment under the action of multiple physical, chemical and biological forces, forming microplastics (diameter <5mm) and nanoplastics (diameter <1μm) such as tiny fragments, which will widely exist in environmental freshwater, seawater, north and south polar ice, sediments, biological groups, soil, air, drinking water and food, and even enter the human body through ingestion and inhalation, affecting the immune system and human health. Therefore, compared with non-degradable "white pollution" plastics, microplastics have a greater degree of harm to the environment. Common types of microplastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polyamide (PA), acrylonitrile butadiene styrene (ABS), polyurethane (PUR), tire wear particles (TWP), degradable plastics (PLA, PHB, PVA, etc.), textile microfibers (synthetic microfibers FMPs mainly composed of nylon and polyester), and discarded cigarette butts. It is worth mentioning that FMPs released during textile washing are considered one of the most important sources of textile microfibers in the environment, and it is very important to take effective measures and means to control and manage microplastics.

[0003] Common microplastic treatment methods include coagulation and flocculation (electro-flocculation), membrane biological reaction technology, adsorption, photocatalytic degradation, etc. Coagulation and flocculation are commonly used methods in wastewater treatment plants. In the treatment process, coagulants such as ferric sulfate or aluminum sulfate are used to trigger the integration of suspended particulate matter into flocculation bodies, and then form sediments that can be easily separated from water. However, this technology is effective for large-sized microplastics, but not for smaller microplastics and nanoplastics. Membrane biological reaction technology is also widely used in the capture and removal of microplastics, but after primary and secondary wastewater treatment, millions of MPs remain in the wastewater. Adsorption is often used to absorb heavy metals and organic pollutants in water, and at the same time, adsorption can also capture microplastics in water and wastewater. Based on adsorption, photocatalysts with catalytic effects can be introduced to generate reactive oxygen species (ROSs) and trigger the degradation of MPs.

[0004] Adsorption is considered as a cost-effective, simple, reliable and effective method to capture microplastics. The adsorbents currently developed to remediate microplastics in wastewater and natural water are classified into four categories: sponges / aerogels, metal-based, biochar and other adsorbents. The invention patent with patent publication number CN117143389A discloses a kind of bamboo shoot shell microcrystalline cellulose / chitosan composite aerogel, which presents a stable three-dimensional cross-linked network structure and can produce electrostatic adsorption and physical adhesion to PS micro-nano plastics. However, aerogels have the disadvantages of poor mechanical properties and high brittleness, which directly limit their reusability and renewable effect. At the same time, due to the high cost of raw materials, the cost is limited. The invention patent with patent publication number CN111825241A discloses a kind of micro-nano motor material, which generates micro-nano bubbles in the water environment under the catalytic reaction driven by fuel hydrogen peroxide, drives the pollutants in the water to float to the water surface and enriches in the bubble foam phase for separation. The method is simple and easy to operate, but most of the micro-nano motors are metal catalysts, which are not easy to recover and have poor biocompatibility. The invention patent with patent publication number CN116371388B discloses a kind of magnetic sponge carbon for efficient adsorption of microplastics, which uses glucosamine hydrochloride as carbon source and melamine as activator, and incorporates magnetic metal to obtain magnetic sponge carbon by high-temperature carbonization. A small amount of water environment magnetic adsorption PS microplastics has excellent effect, but this magnetic adsorption is not suitable for large-scale real complex environment for removing various microplastics, and the pore size of carbon material is small during the adsorption process, which will block the pore channel at the same time of fast adsorption in the early stage, and cannot achieve the best adsorption effect. The invention patent with patent publication number CN118223330A discloses a kind of composite paper-based material for filtering micro-nano plastics, which uses vacuum filtration method to load TEMPO oxidized nanocellulose on the surface of filter paper, and connects nanocellulose and filter paper fibers by glutaraldehyde cross-linking treatment to obtain nanocellulose / filter paper composite paper-based material, which has excellent reusability and adsorption effect, but the filtering efficiency and filtering flux effect of microplastics with small size are not good.

[0005] A large proportion of waste textiles is waste cellulose acetate, and discarded cigarette filters in the form of cigarette butts are the main source of waste cellulose acetate, solid waste and environmental pollution. More seriously, the continuous fragmentation and degradation of the main component of waste cigarette butts, cellulose acetate fibers, in complex environments will produce a large amount of microplastics, and these microplastics will attach a large amount of toxic metals and polycyclic aromatic hydrocarbons (PAHs) in waste cigarette butts to penetrate into the environment, causing harm to humans and wild animals. Studies have shown that waste cigarette butts can be converted into adsorption and filtration materials such as membranes, fibers, fiber bundles and porous carbon through simple recycling and functionalization, which can effectively treat a large amount of pollutants in wastewater. Therefore, it is a very desirable and effective means to value-add waste cigarette butts to adsorption materials for capturing and removing microplastics. SUMMARY

[0006] [Technical Problem] [Technical Problem]

[0007] The problems existing in the prior art are: (1) the cost of the substrate is high, and the preparation is complicated, especially the metal-based adsorbent material; (2) the single adsorption mechanism or physical adsorption has limitations, and as the adsorbent is consumed, the adsorption capacity is also weakened; (3) the adsorption of different types of microplastics with different functional groups has limitations, and most of the materials only have adsorption to the most broad-spectrum PS microplastics.

[0008] [Technical Solution] [Technical Solution]

[0009] In view of the above problems existing in the prior art, the present application provides an organic-inorganic hybrid fiber for microplastic adsorption and a preparation method thereof. The present application obtains acetic cellulose fibers by pretreating waste acetic fibers, functionalizes through two-step Schiff base cross-linking, and in-situ grows hydroxyapatite nanowires to obtain an organic-inorganic hybrid fiber with excellent performance, which adsorbs and removes microplastics by "waste treatment with waste". It provides a theoretical basis and technical support for the value-added conversion of bio-based waste into high-value-added environmentally friendly functional adsorbent materials, and provides a new idea for the development and application of microplastic adsorbent materials.

[0010] The technical scheme of the present application is as follows:

[0011] The first object of the present application is to provide a preparation method of an organic-inorganic hybrid fiber for microplastic adsorption, comprising the following steps:

[0012] (1) Soak the waste acetic fiber in deionized water, dry it, then wash it with ethanol under ultrasonic, dry it, then clean it with non-polar organic solvent under ultrasonic, and finally clean it with deionized water, and dry it for use;

[0013] (2) Put the waste acetic fiber treated in step (1) into an amine compound solution, stir it under magnetic field at room temperature for 12 hours, then add glutaraldehyde solution, adjust the pH to 8.0, rinse it with deionized water after the stirring reaction is completed, and dry it for use;

[0014] (3) Put the fiber treated in step (2) into a mixed solution of polyphenol solution and Tris-HCl buffer solution, stir it under magnetic field at room temperature, rinse it with deionized water, and dry it for use;

[0015] (4) Mix ethanol and oleic acid under mechanical stirring, add calcium precursor, sodium hydroxide and phosphorus source in sequence, transfer the mixed solution to a Teflon-lined stainless steel reaction kettle, add the fiber treated in step (3) at the same time, seal it, and heat it in an oven for 24 hours. After completion, stir it with ethanol and deionized water for three times under magnetic field respectively, and dry it to obtain the organic-inorganic hybrid fiber.

[0016] In an embodiment of the present application, in step (1), the waste acetate fiber is one or more of waste cigarette butts, waste textile fibers.

[0017] In an embodiment of the present application, in step (1), the waste acetate fiber is one or more of waste cigarette butts from which the filter segment and the plug wrap are removed, waste acetate staple nonwoven fabric, and waste acetate filament of textile.

[0018] In an embodiment of the present application, in step (1), the soaking condition is that the temperature is 40-80℃ and the time is 6-12h.

[0019] In an embodiment of the present application, in step (1), the ethanol has a mass concentration of 75%, and is ultrasonically cleaned for 1-4h with 50-100mL.

[0020] In an embodiment of the present application, in step (1), the ultrasonic cleaning power of the ethanol is 40-100kHz, and the ultrasonic cleaning is performed for 1-4h, with fresh ethanol being replaced every 1h.

[0021] In an embodiment of the present application, in step (1), the non-polar organic solvent is one or more of cyclohexane, petroleum ether, and toluene.

[0022] In an embodiment of the present application, in step (1), the non-polar organic solvent is ultrasonically cleaned for 1-4h with 50-100mL.

[0023] In an embodiment of the present application, in step (2), the amine compound is one or more of polyethyleneimine, ethylenediamine, hexanediamine, dodecanamine, and octadecanamine; and the concentration of the aqueous amine compound solution is 0.8-2.0g / L.

[0024] The polyethyleneimine has a molecular weight of one or more of 600, 1800, 10000, and 70000.

[0025] In an embodiment of the present application, in step (2), the concentration of the glutaraldehyde solution is 25wt%.

[0026] In an embodiment of the present application, in step (2), the molar ratio of glutaraldehyde to the amine compound is 1:0.5-2.

[0027] In an embodiment of the present application, in step (2), one or more of hydrochloric acid, sodium hydroxide, and sodium bicarbonate is used to adjust the pH value of the reaction solution.

[0028] In an embodiment of the present application, in step (2), the reaction temperature is 50-80℃, and the reaction time is 1-3h.

[0029] In an embodiment of the present application, in step (3), the polyphenol is one or more of tannic acid, gallic acid, catechol, pyrocatechol, ellagic acid, anthocyanin, catechin, tea polyphenol; the concentration of the polyphenol aqueous solution is 1.0-3.0 g / L.

[0030] In an embodiment of the present application, in step (3), the Tris-HCl buffer solution is prepared by mixing 50 mL of a 0.1 mol / L tris-hydroxyl aminomethane solution and 14.7 mL of a 0.1 mol / L hydrochloric acid solution; the pH value of the prepared Tris-HCl buffer solution is 8.5.

[0031] In an embodiment of the present application, in step (3), the volume ratio of the polyphenol aqueous solution to the Tris-HCl buffer solution is 1:0.5-1; the magnetic stirring is performed at room temperature at 300-600 rpm for 6-24 h.

[0032] In an embodiment of the present application, in step (4), the mechanical stirring speed is 500-700 rpm.

[0033] In an embodiment of the present application, in step (4), the volume ratio of ethanol to oleic acid is 1:0.5-2; the mass concentration of ethanol is 95%.

[0034] In an embodiment of the present application, in step (4), the calcium precursor is one or more of calcium chloride, calcium nitrate, and calcium hydroxide; the phosphorus source is one or more of diphosphorus pentoxide, phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and dipotassium hydrogen phosphate.

[0035] In an embodiment of the present application, in step (4), the calcium precursor is added dropwise to the mixed solution of ethanol and oleic acid at a rate of 1-100 mL / min; then the sodium hydroxide solution is added dropwise to the solution obtained in the previous step at a rate of 1-100 mL / min; finally, the phosphorus source is added dropwise to the solution obtained in the previous step at a rate of 1-50 mL / min.

[0036] In an embodiment of the present application, in step (4), the mass concentration of the calcium precursor is 5-20 g / L; the mass concentration of the sodium hydroxide solution is 30-50 g / L; the mass concentration of the phosphorus source solution is 20-300 g / L.

[0037] In an embodiment of the present application, in step (4), the mass ratio of the calcium precursor to sodium hydroxide is 1-4:6-10.

[0038] In an embodiment of the present application, in step (4), the mass-to-volume ratio of the treated fiber to the solution prepared in step (4) is 0.5-5 g:100-1000 mL.

[0039] In an embodiment of the present application, in step (4), the temperature of the oven is 140-160 DEG C.

[0040] In an embodiment of the present application, in step (4), the capacity of the Teflon-lined stainless steel reactor is one of 100 mL, 200 mL, 500 mL, and 1 L.

[0041] In an embodiment of the present application, a 100 mL hydrothermal reactor is used, and the hydrothermal reaction is carried out in an oven, and the reaction is kept at a certain temperature for a certain time, and then the reactor is taken out and cooled, and then the reactor is opened and the sample is taken out. The reaction container is a polytetrafluoroethylene lining. For hydrothermal reactions that do not produce a large amount of gas, the polytetrafluoroethylene lining is required to be no more than 75% full, and the stainless steel outer sleeve is required to be sealed to ensure the overall sealing. This is a stable, fully mixed, and successful hydrothermal reaction. At the same time, it ensures the successful preparation of the sample.

[0042] The second object of the present application is to provide an organic-inorganic hybrid fiber prepared by the above preparation method.

[0043] The third object of the present application is to provide an application of the above organic-inorganic hybrid fiber, which is used for adsorbing one or more of microplastics PS, PET, PE, PVC, PMMA, and PP, and textile microfibers PA and PU.

[0044] The size of common microplastics and textile microfibers is 1 nm-100 microns.

[0045] The microplastics are PS, PET, PU, and PA, the size of the microplastics is 5-20 microns, and the concentration of the microplastics is 0.1-2 mg / mL.

[0046] Microplastics have different sizes and shapes, and fibers are generally referred to as microfibers. Microfibers are generally derived from textile washing, so textile microfibers are a type of microplastic. Common microplastics are ordinary PE, PP, PET, PS, and PMMA, and textile microfibers are mainly polyurethane PU and polyamide PA.

[0047] The beneficial technical effects of the present application are:

[0048] The application first applies the functionalized waste acetate fiber combined with hydroxyapatite nanowires in the removal of microplastics. The waste acetate fiber undergoes the first Schiff base reaction with amine compounds under the cross-linking action of glutaraldehyde, and the fiber surface has a large number of amino and hydroxyl functional groups. At the same time, a polyphenol compound with rich phenolic hydroxyl groups is introduced, and the second Schiff base reaction occurs in the alkaline Tris-HCl solution. It is worth noting that the cross-linking of the fiber surface introduces a large number of benzene rings, which provides favorable conditions for the π-π interaction between the microplastics. Finally, the hydroxyapatite nanowires are grown in situ on the fiber surface at a certain temperature, providing multiple hydroxyl functional groups and rich adsorption sites, and the nanowire structure on the surface provides favorable conditions for the pore filling of microplastics. The construction of this organic-inorganic hybrid fiber realizes the synergy of multiple adsorption mechanisms, and the overall adsorption effect and reusable effect of common microplastics and textile microfibers are excellent.

[0049] The application introduces rich amino, hydroxyl and large aromatic ring structures through glutaraldehyde solution cross-linking and polyphenol compound self-polymerization cross-linking, and in-situ growth of hydroxyapatite nanowires to prepare an environmentally friendly functionalized waste acetate fiber as an adsorbent for micro-nano plastics in water.

[0050] The application introduces corresponding functional groups on the surface of the waste acetate fiber for different structures of micro-nano plastics, realizes the effect of efficiently capturing and removing microplastics through electrostatic interaction, hydrogen bond interaction, π-π interaction and pore filling, and has excellent reusable effect, thereby achieving the purpose of expanding multiple application scenarios.

[0051] The organic-inorganic hybrid fiber has multiple functional groups and active adsorption sites, can effectively adsorb different types of microplastics according to different adsorption mechanisms, and has a wide application range. The base material waste acetate fiber is a harmful solid waste, which is widely available and low in cost, and has economic advantages. Through functionalization, the solid waste has high added value, and the effect of "waste treatment" is achieved.

[0052] The organic-inorganic hybrid fiber has excellent reusable effect, and at the same time can be recycled and reused through a simple method, fully embodying the current concept of green development. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 The fiber sample graph of the organic-inorganic hybrid fiber prepared by the waste cigarette butt base material in Examples 1-2;

[0054] Figure 2 The Fourier infrared spectrum graph of each fiber sample in Examples 1-2;

[0055] Figure 3 The X-ray photoelectron spectroscopy graph of each fiber sample in Examples 1-2;

[0056] Figure 4 SEM images of each fiber sample in Examples 1-2;

[0057] Figure 5 Zeta potentials of microplastics and each fiber sample in Examples 1-2 at pH = 7.0;

[0058] Figure 6 TG analysis images of each fiber sample in Examples 1-2. DETAILED DESCRIPTION

[0059] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0060] Test methods involved in the following examples:

[0061] Fiber sample performance test method:

[0062] Functional group analysis of the fiber sample was performed using an infrared spectrometer with an attenuated total reflection accessory, with a scanning range of 500-4000 cm -1 ; surface element composition and valence state change analysis of the fiber sample was performed using X-ray photoelectron spectroscopy; in order to observe the overall morphology and surface morphology of the fiber sample, the fiber sample was observed using a scanning electron microscope. Before testing, the fiber sample cut into 0.5 x 0.5 m 2 was fixed on the surface of the electron microscope stage by conductive glue, vacuum gold spraying treatment was performed, and the acceleration voltage was 5 kV; the fiber sample was heated and tested under N2 atmosphere using a thermal analysis instrument, with a test range of 30-800℃, a heating rate of 10℃ / min, and an N2 flow rate of 50 mL / min; the surface charge polarity and charge of the fiber sample were characterized by a Zeta potential analyzer.

[0063] Maximum adsorption capacity test method:

[0064] In order to explore the adsorption potential of the fiber adsorbent for various microplastics, the microplastics were dispersed in a mixed solution of deionized water and Tween 80 (0.5 wt%) with the aid of ultrasonic, and then the fiber adsorbent was weighed and placed in the above microplastic solution, and shaken in a water bath at room temperature to reach adsorption saturation, and the adsorption capacity was determined by the following formula:

[0065]

[0066] In the formula, m0and m e represent the initial weight and the equilibrium weight of the fiber adsorbent, respectively. m t is the weight of the fiber adsorbent extracted from the solution at a given time point. It is worth noting that the above weights refer to the weight dried to constant weight at 60℃. In addition, q e(mg g -1 ) and q t (mg g -1 ) represent the adsorption capacity at the equilibrium time point and the given time point, respectively. The mass of the fiber adsorbent is m (g). The above experiment is repeated three times, and the results are averaged.

[0067] Raw materials used in the following examples:

[0068] The waste acetate fiber used in the present application is collected at designated public smoking points and billiard halls; the polyethyleneimine is purchased from Shanghai Alalamp Biochemical Technology Co., Ltd., with a molecular weight of 1800; the tris(hydroxymethyl)aminomethane (Tris), oleic acid, tea polyphenol (TP), sodium hydroxide, ethanol, sodium chloride, sodium acetate, diethyl ether, n-hexane, methanol, sulfuric acid, hydrochloric acid are all purchased from the National Pharmaceutical Group Chemical Reagent Co., Ltd.; the sodium phosphate dibasic dihydrate and glutaraldehyde are purchased from Shanghai Titan Science and Technology Co., Ltd.; the calcium chloride is purchased from Shanghai Epi Chemical Reagent Co., Ltd.; the polystyrene (15 μm), polyethylene terephthalate (20 μm), polyamide (10 μm), polyurethane (20 μm), polyethylene (10 μm), polymethyl methacrylate (8 μm), polypropylene (6.5 μm), and polyvinyl chloride (6.5 μm) are purchased from Shanghai Runwang International Trade Co., Ltd.

[0069] Example 1:

[0070] A preparation method of an organic-inorganic hybrid fiber for microplastic adsorption, comprising the following steps:

[0071] (1) 0.15 g of waste acetate fiber is soaked in deionized water at 60°C for 12 h, dried at 60°C, and then placed in 100 mL of anhydrous ethanol with a mass concentration of 75%, and ultrasonically washed for 2 h at a power of 100 kHZ, with fresh anhydrous ethanol being replaced every 1 h; after drying at 60°C, it is placed in 50 mL of cyclohexane solution, and ultrasonically washed for 2 h at a power of 100 kHZ, and finally washed with deionized water three times, and dried at 60°C for use, denoted as CA fiber.

[0072] (2) 0.2 g of polyethyleneimine with a molecular weight of 1800 is added to 100 mL of deionized water to prepare a PEI solution with a mass concentration of 2.0 g / L, and the fiber for use in step (1) is placed in the above solution, stirred at 300 rpm at room temperature for 12 h, the pH is adjusted to 8.0 using a 0.1 mol / L sodium bicarbonate solution, and then 8.76 mL of a glutaraldehyde solution with a mass concentration of 50 wt% is added to ensure that the molar ratio of glutaraldehyde to polyethyleneimine is 2:1, and stirred at 300 rpm at 60°C for 3 h, after the reaction is completed, it is washed with deionized water, and dried at 60°C for use, denoted as PEI / GA-CA fiber.

[0073] (3) In 100 mL of deionized water, add 0.15 g of tea polyphenol to prepare a tea polyphenol solution with a concentration of 1.5 g / L; in 50 mL of deionized water, add 0.6057 g of tris-hydroxymethyl aminomethane to prepare a Tris solution with a concentration of 0.1 mol / L, add 14.7 mL of hydrochloric acid solution with a concentration of 0.1 mol / L to obtain a Tris-HCl buffer solution with a pH of 8.5; mix the tea polyphenol solution with the Tris-HCl buffer solution, and place the fibers prepared in step (2) in the mixed solution, and stir at room temperature at 300 rpm for 12 h; after the reaction is completed, wash with deionized water, and dry at 60°C for use, and record as PEI / GA / TP-CA fibers.

[0074] (4) In 20 mL of deionized water, add 0.22 g of CaCl2, and stir at room temperature at 300 rpm for 10 min to prepare a CaCl2 solution with a mass concentration of 11.0 g / L; in 20 mL of deionized water, add 1 g of NaOH, and stir at room temperature at 300 rpm for 10 min to prepare a NaOH solution with a mass concentration of 50.0 g / L; in 10 mL of deionized water, add 0.28 g of NaH2PO4.2H2O, and stir at room temperature at 300 rpm for 10 min to prepare a CaCl2 solution with a concentration of 28.0 g / L; in 12 g of anhydrous ethanol with a mass fraction of 99.5%, add 12 g of oleic acid, and mechanically stir at room temperature at 700 rpm; then slowly add the above-mentioned CaCl2 solution at a rate of 5 mL / min, mechanically stir for 15 min, then slowly add the above-mentioned NaOH solution at a rate of 5 mL / min, mechanically stir for 15 min, then slowly add the above-mentioned NaH2PO4.2H2O solution at a rate of 5 mL / min, and mechanically stir for 15 min to obtain a reaction precursor solution.

[0075] (5) Transfer the precursor solution of step (4) to a polytetrafluoroethylene liner in a 100 mL Teflon-lined stainless steel reaction kettle, and place 0.6 g of the fibers prepared in step (3) in the liner, seal it, and then place it in a 150°C oven for 24 h. After the reaction is completed, wash with anhydrous ethanol with a mass fraction of 99.5% at room temperature at 100 rpm for three times, and then wash with deionized water for three times to obtain an organic-inorganic hybrid fiber, and record as HANWs 150 @PEI / GA / TP-CA fibers.

[0076] Example 2:

[0077] A method for preparing an organic-inorganic hybrid fiber for microplastic adsorption, comprising the following steps:

[0078] Same as Example 1, except that the sealing temperature in step (5) of Example 1 is changed from 150°C to 160°C in the oven. Specifically:

[0079] The precursor solution from step (4) was transferred to a 100 mL Teflon-lined stainless steel reactor lined with polytetrafluoroethylene. 0.6 g of the fiber prepared in step (3) was placed inside, sealed, and then kept in an oven at 160 °C for 24 h. After completion, the fiber was washed three times with 99.5% anhydrous ethanol at room temperature using magnetic stirring at 100 rpm, followed by three washes with deionized water to obtain the organic-inorganic hybrid fiber, denoted as HANWs. 160 @PEI / GA / TP-CA fiber.

[0080] The other steps were performed according to the method in Example 1 to prepare organic-inorganic hybrid fibers that could be used for microplastic adsorption.

[0081] The organic-inorganic hybrid fibers prepared in Examples 1-2 and their physical images are shown below. Figure 1 As shown, (a) are waste cigarette butts without the removal of cigarette segments and forming paper; (b) are waste acetate fibers after multiple cleanings with deionized water, ethanol, and non-polar organic solvents; (c) are fibers after the first functionalization; (d) are fibers after the second functionalization; (e) are fibers with hydroxyapatite nanowires grown at 150℃; and (f) are fibers with hydroxyapatite nanowires grown at 160℃. It can be seen that with the two cross-linking processes and the growth of hydroxyapatite nanowires, the surface of the fiber adsorbent gradually becomes rough and porous, which will be beneficial for the adsorption and capture of microplastics.

[0082] Figure 2 The Fourier transform infrared spectra of each fiber sample in Examples 1-2 are shown below; Figure 2 It can be clearly seen that the fiber adsorbent after two cross-linking processes and the growth of hydroxyapatite nanowires has a viscosity of 300-3600 cm⁻¹. -1 The presence of -OH / -NH2 peaks is attributed to the polyamino crosslinking of PEI via Schiff base reaction and the abundant hydroxyl functional groups in the hydroxyapatite nanowires, along with a peak at 2357 cm⁻¹. -1 The presence of O=C=O double bonds proves the cross-linking of glutaraldehyde. Meanwhile, at 1650 cm⁻¹... -1 and 1550cm -1 The presence of C=N and NH at the site favorably demonstrates the Schiff base reaction between the oxidized quinone group and the amino group, while at 550-1100 cm⁻¹ -1 Multiple peaks appearing within the range belong to PO4 3- This demonstrates the successful growth of hydroxyapatite nanowires. From Figure 2It can also be seen from the figure that the infrared peaks of the fiber adsorbents treated at 150℃ and 160℃ are relatively sharp, which may be due to the fact that the growth temperature of 160℃ is close to the glass transition temperature of the waste acetate fiber, which affects the growth stability of the fiber surface.

[0083] Figure 3 X-ray photoelectron spectrograms of each fiber sample in Example 1-2; from Figure 3 Ca2 P P2 P The Ca2 P P2 P peaks of the fiber adsorbents treated at 150℃ and 160℃ are more prominent, which proves this statement.

[0084] Figure 4 SEM images of each fiber sample in Example 1-2; wherein (a) is the waste acetate fiber after multiple washing with deionized water, ethanol and non-polar organic solvents, scale = 100 microns; (b) is the fiber after the first functionalization, scale = 100 microns; (c) is the fiber after the second functionalization, scale = 50 microns; (d) is the fiber growing hydroxyapatite nanowires at 150℃, scale = 50 microns; (e) is the fiber growing hydroxyapatite nanowires at 160℃, scale = 5 microns. It can be seen that the surface of the waste acetate fiber is smooth and has obvious grooves, and after two-step functionalization, the surface has obvious coating and roughness change, which is conducive to the adsorption of microplastics and the growth of hydroxyapatite nanowires in the next step. As shown in (d) and (e), the nanowires grow densely and irregularly on the surface of the fiber, and this large specific surface area feature is conducive to the capture and enrichment of microplastics. At the same time, as shown in Figure 6 HANWs 150 @PEI / GA / TP—CA and HANWs 160 @PEI / GA / TP—CA fibers have a residual weight of 20% at 800℃, which is higher than the 10% residual weight of the waste acetate fiber, PEI / GA-CA fiber and PEI / GA / TP-CA fiber at 800℃, which proves that the growth of hydroxyapatite nanowires also improves the thermal stability of the fiber adsorbent.

[0085] Example 3

[0086] A method for preparing an organic-inorganic hybrid fiber for microplastic adsorption, comprising the following steps:

[0087] The same as Example 1, except that the sealing in step (5) of Example 1 is changed to 140℃ in a 150℃ oven, specifically:

[0088] The precursor solution of step (4) was transferred to a 100 mL Teflon-lined stainless steel reactor, 0.6 g of the fiber prepared in step (3) was placed in the polytetrafluoroethylene lining, and the reactor was sealed and placed in an oven at 140°C for 24 h. After the end of the experiment, the fiber was washed with 99.5% anhydrous ethanol at room temperature for 100 rpm magnetic stirring for three times, and then with deionized water for three times to obtain the organic-inorganic hybrid fiber, which is denoted as HANWs 140 @PEI / GA / TP-CA fiber.

[0089] Other steps were prepared according to the method of Example 1 to obtain the organic-inorganic hybrid fiber for microplastic adsorption.

[0090] Through the adsorption test of 1.5 mg / mL PS-15 μm at room temperature for 24 h, the adsorption capacity was 491.11 ± 10.18 mg / g. The adsorption effect is good, but compared with the adsorption capacity at 150°C, it is decreased, which may be due to the lower temperature affecting the nucleation and crystal formation of hydroxyapatite nanowires during the growth process, thereby affecting the microplastic adsorption effect.

[0091] Example 4: Adsorption effect of different types of microplastics

[0092] Prepare 1.5 mg / mL PS-15 μm, PET-20 μm, PU-20 μm, PA-10 μm, PE-10 μm, PMMA-8 μm, PP-6.5 μm, and PVC-6.5 μm microplastic solutions, respectively. Add 10 mL of the above solution to a 15 mL glass bottle, and add 15 mg of HANWs 150 @PEI / GA / TP—CA fiber adsorbent, under the condition of pH = 7, 300 rpm water bath oscillator, room temperature oscillation for 24 h, the maximum adsorption capacity is determined by the above-mentioned maximum adsorption capacity test method. The specific data are shown in Table 1:

[0093] Table 1 HANWs 150 @PEI / GA / TP—CA fiber maximum adsorption capacity

[0094] Microplastics Maximum adsorption capacity (mg / g) PS - 15 pm 722.22±40.18 PET - 20 pm 593.33±43.71 PU - 20 pm 688.89±31.50 PA - 10 pm 224.44±34.21 PE - 10 pm 237.78±16.78 PMMA - 8 pm 175.56±23.41 PP - 6.5 pm 77.78±23.41 PVC - 6.5 pm 171.11±21.43

[0095] As can be seen from the table, the adsorption effect on PS-15 μm is the best, and the effect on PP-6.5 μm is the worst, but the adsorption capacity of each kind of microplastic also has certain advantages compared with the adsorption capacity of most of the currently published microplastic adsorbents, which proves that this organic-inorganic hybrid fiber has certain adsorption and removal advantages for broad-spectrum microplastics.

[0096] Example 5: Regeneration effect of organic-inorganic hybrid fiber after adsorbing microplastics

[0097] The fiber adsorbent after adsorption in Example 3 was collected and dissolved by adding a small amount of aqueous acetone, and a homogeneous film with a microplastic reinforced phase was obtained by pouring the polymer into a film through phase transfer. The microplastics in the film act as a filler for the pores, effectively improving the strength performance of the film.

[0098] Comparative Example 1: Effect of hydrothermal growth temperature of 170°C on the preparation of fiber adsorbent

[0099] The same as Example 1, except that the sealing in step (5) of Example 1 was adjusted to 150°C in an oven to 170°C. The experiment was carried out as described above, and after the hydrothermal reaction was completed and the sample was cooled, the fiber sample was directly crushed and could not be formed into a fiber shape. This is because the glass transition temperature of the cellulose acetate fiber is about 185°C. When the oven temperature is set to 170°C, the instantaneous temperature may be greater than the glass transition temperature at some stage, and the long-term 170°C may reduce the stability of the cellulose acetate fiber, which is not conducive to the subsequent adsorption experiment of the fiber adsorbent.

[0100] Comparative Example 2

[0101] A method for preparing an organic-inorganic hybrid fiber for microplastic adsorption, comprising the following steps:

[0102] The same as Example 1, except that the 50 mL cyclohexane solution in step (1) of Example 1 was removed, and the ultrasonic washing was carried out for 2 h at a power of 100 kHz, specifically:

[0103] 0.15 g of waste cellulose acetate fiber was soaked in 60°C deionized water for 12 h, and after drying at 60°C, it was placed in 100 mL of anhydrous ethanol with a mass concentration of 75%, and ultrasonic washing was carried out for 2 h at a power of 100 kHz, and fresh anhydrous ethanol was replaced every 1 h; Finally, it was washed with deionized water three times and dried at 60°C for use, and was recorded as CA fiber.

[0104] Other steps were prepared according to the method of Example 1 to obtain an organic-inorganic hybrid fiber for microplastic adsorption.

[0105] The CA fiber obtained by steps (1) of Example 1 and steps (1) of Example 3 was subjected to microplastic adsorption experiment, and the adsorption capacity was 273.33 mg / g and 366.66 mg / g respectively after 24 h adsorption of 1.5 mg / mL PS-15 μm microplastic. After washing with a non-polar solvent, the nicotine and harmful ingredients on the surface of the CA fiber were greatly reduced, which was beneficial to the adsorption of more microplastics, and the adsorption capacity test proved this conclusion.

[0106] The above examples are not intended to limit the scope of the present application, nor are the described steps intended to limit the order in which they are performed. Modifications apparent to one skilled in the art in light of the above teachings are intended to fall within the scope of the claims.

Claims

1. A method for preparing organic-inorganic hybrid fibers for microplastic adsorption, characterized in that, The preparation method includes the following steps: (1) Soak the waste cellulose acetate in deionized water, dry it, then ultrasonically wash it in ethanol, dry it, ultrasonically clean it with a non-polar organic solvent, and finally clean it with deionized water and dry it for later use. (2) Place the waste cellulose acetate treated in step (1) into an amine compound solution, stir magnetically at room temperature for 12 hours, add glutaraldehyde solution, adjust the pH to 8.0, after stirring the reaction is complete, rinse with deionized water, and dry for later use; (3) Place the fiber treated in step (2) in a mixed solution of polyphenol solution and Tris-HCl buffer solution, stir magnetically at room temperature, rinse with deionized water, and dry for later use; (4) Under mechanical stirring, ethanol and oleic acid are mixed, and calcium precursor, sodium hydroxide and phosphorus source are added in sequence. The mixed solution is transferred to a Teflon-lined stainless steel reactor, and the fiber treated in step (3) is added at the same time. After sealing, it is kept in the oven for 24 hours. After the end, it is magnetically stirred three times with ethanol and deionized water respectively. After drying, organic-inorganic hybrid fiber is obtained.

2. The preparation method according to claim 1, characterized in that, In step (1), one or more of the following conditions must be met: Waste acetate fiber is one or more types of waste cigarette butts and waste textile fibers; The soaking conditions are: temperature 40-80℃, time 6-12h; The conditions for ultrasonic washing in ethanol are: 50-100 mL of ethanol and ultrasonication for 1-4 hours; The nonpolar organic solvent is one or more of cyclohexane, petroleum ether, and toluene; The conditions for ultrasonic cleaning with non-polar organic solvents are: 50-100 mL of ultrasonic solution for 1-4 hours.

3. The preparation method according to claim 1, characterized in that, In step (2), one or more of the following conditions must be met: The amine compounds are one or more of polyethyleneimine, ethylenediamine, hexamethylenediamine, dodecylamine, and octadecylamine; The concentration of aqueous solutions of amine compounds is 0.8-2.0 g / L; Polyethyleneimine has one or more molecular weights of 600, 1800, 10000, and 70000.

4. The preparation method according to claim 1, characterized in that, In step (2), one or more of the following conditions must be met: The concentration of the glutaraldehyde solution is 25 wt%. The molar ratio of glutaraldehyde to amine compounds is 1:0.5-2; The pH value of the reaction solution is adjusted by using one or more of hydrochloric acid, sodium hydroxide, and sodium bicarbonate; The reaction temperature is 50-80℃, and the reaction time is 1-3h.

5. The preparation method according to claim 1, characterized in that, In step (3), one or more of the following conditions must be met: Polyphenols are one or more of the following: tannic acid, gallic acid, catechin, catechol, ellagic acid, anthocyanins, catechins, and tea polyphenols. The concentration of polyphenol aqueous solution is 1.0-3.0 g / L; Tris-HCl buffer is prepared by mixing 50 mL of 0.1 mol / L trihydroxyaminomethane solution and 14.7 mL of 0.1 mol / L hydrochloric acid solution; The pH of the prepared Tris-HCl buffer solution is 8.

5.

6. The preparation method according to claim 1, characterized in that, In step (3), one or more of the following conditions must be met: The volume ratio of polyphenol aqueous solution to Tris-HCl buffer is 1:0.5-1; The magnetic stirring time is 6-24 hours.

7. The preparation method according to claim 1, characterized in that, In step (4), one or more of the following conditions must be met: The volume ratio of ethanol to oleic acid is 1:0.5-2; The calcium precursor is one or more of calcium chloride, calcium nitrate, and calcium hydroxide; The phosphorus source is one or more of phosphorus pentoxide, phosphoric acid, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, and dipotassium hydrogen phosphate; The calcium precursor was added dropwise to a mixed solution of ethanol and oleic acid at a rate of 1-100 mL / min; then the sodium hydroxide solution was added dropwise to the solution from the previous step at a rate of 1-100 mL / min; finally, the phosphorus source was added dropwise to the solution from the previous step at a rate of 1-50 mL / min.

8. The preparation method according to claim 1, characterized in that, In step (4), one or more of the following conditions must be met: The mass ratio of calcium precursor to sodium hydroxide is 1-4:6-10; The mass-to-volume ratio of the treated fiber to the solution prepared in step (4) is 0.5-5g:100-1000mL; The oven temperature is maintained at 140-160℃.

9. An organic-inorganic hybrid fiber prepared by the preparation method according to any one of claims 1-8.

10. An application of the organic-inorganic hybrid fiber according to claim 9, characterized in that, It is used to adsorb one or more of the following microplastics: PS, PET, PE, PVC, PMMA, PP, and textile microfibers: PA, PU.

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