Ti-13x@go / tpu composite fiber for wastewater decolorization and preparation method thereof
By preparing Ti-13X@GO/TPU composite fibers, the problems of difficult separation and recovery and poor mechanical properties of powdered 13X zeolite/TiO2 composites were solved, achieving efficient adsorption and photocatalytic synergistic decolorization functions, and possessing good mechanical properties and easy recyclability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PANJIN PAIPU ENVIRONMENTAL PROTECTION TECH CO LTD
- Filing Date
- 2026-05-27
- Publication Date
- 2026-06-26
AI Technical Summary
Existing powdered 13X zeolite/TiO2 composites are difficult to separate and recover from water, and the composite fibers have poor mechanical properties at high filling amounts, which limits their practical application.
Ti-13X@GO/TPU composite fibers were used to prepare continuous long fibers by electrostatic self-assembly of titanium-doped 13X molecular sieve nanocrystals and graphene oxide to form a composite filler, which was then combined with a thermoplastic polyurethane fiber matrix. The crystallinity of the material was improved by steam-assisted crystallization and the surface was modified to enhance the interfacial bonding force.
Ti-13X@GO/TPU composite fibers with high adsorption capacity, excellent photocatalytic activity and good mechanical properties are achieved. They are easy to recycle, overcoming the problem of separation and recycling of powder materials, and have good decolorization performance and cycle stability.
Smart Images
Figure CN122279791A_ABST
Abstract
Description
Technical fields:
[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a Ti-13X@GO / TPU composite fiber for wastewater decolorization and its preparation method. Background technology:
[0002] The textile printing and dyeing industry is one of the major sources of global water consumption and environmental pollution. Dye wastewater is characterized by high chemical oxygen demand (COD), high color intensity, high salinity, complex composition, and poor biodegradability, making it one of the most difficult types of industrial wastewater to treat. In particular, cationic dyes such as methylene blue and rhodamine B readily dissociate into positively charged colored ions in water, posing a serious threat to the ecological environment and human health.
[0003] Currently, the main methods for treating dye wastewater include physical methods (adsorption, membrane separation), chemical methods (advanced oxidation, coagulation and sedimentation), and biological methods. Adsorption methods have attracted much attention due to their simple operation, good treatment effect, and wide applicability. However, traditional adsorbents such as activated carbon and zeolite molecular sieves have problems such as limited adsorption capacity, difficulty in regeneration, and difficulty in recovering powdered materials. Although photocatalysis technology can deeply degrade organic pollutants, nano-photocatalysts are prone to aggregation, difficult to recover, and can easily cause secondary pollution.
[0004] In recent years, the preparation of fiber materials by combining adsorbents / photocatalysts with polymer matrices has become an effective way to solve the problem of separating and recycling powder materials. For example, Cordoba et al. loaded titanium dioxide (TiO2) into nanofibers blended with chitosan and polycaprolactone (PCL) using electrospinning technology. They utilized the functional groups of chitosan to enrich dye molecules and synergistically photocatalytically degrade them with TiO2. The fiber membrane could be reused multiple times (see: Cordoba A, et al. International Journal of Biological Macromolecules, 2023, 253: 127111).
[0005] In contrast, 13X zeolite molecular sieves possess a regular three-dimensional pore structure and a large specific surface area (typically >500 m²). 2With its excellent cation exchange capacity ( / g), 13X zeolite itself is a highly efficient adsorbent. Loading TiO2 onto 13X zeolite creates a synergistic system of "adsorption enrichment-photocatalytic degradation": the zeolite channels capture dye molecules through ion exchange and physical adsorption, enriching them around the active sites of TiO2, significantly increasing the photocatalytic reaction rate. Simultaneously, photocatalytic oxidation can regenerate zeolite adsorption sites in situ. More importantly, 13X zeolite effectively alleviates the deactivation problem of TiO2 photocatalysts—its regular channels preferentially adsorb and mineralize intermediate products, reducing irreversible poisoning of intermediate products on the TiO2 surface; the zeolite framework physically isolates and anchors TiO2 nanoparticles, preventing their aggregation; and the acidic sites on the zeolite surface help promote the oxidative removal of carbon deposit precursors. These properties collectively extend the service life and cycle stability of the composite material, which is difficult to achieve with simply loading photocatalysts onto polymers.
[0006] However, the 13X zeolite / TiO2 composite currently exists in powder form, making it difficult to separate and recover from water after direct addition, thus limiting its practical application. If it is to be combined with a polymer matrix to prepare fiber materials, it is necessary to maintain the high adsorption, high catalytic activity, and anti-deactivation characteristics of zeolite / TiO2, while overcoming the technical bottleneck of high fiber brittleness and easy breakage when high-filling inorganic powders are blended and spun with polymers.
[0007] Based on this, developing a 13X zeolite / TiO2 composite fiber material that combines high adsorption capacity, excellent photocatalytic activity, good mechanical properties, anti-deactivation characteristics, and easy recyclability has significant practical significance and application value. Summary of the Invention:
[0008] The purpose of this invention is to provide a Ti-13X@GO / TPU composite fiber and its preparation method, aiming to solve the technical problems of difficulty in separating and recovering existing powdered adsorption / photocatalytic materials, and poor mechanical properties of composite fibers with high filler content. Another purpose of this invention is to provide the application of the above-mentioned composite fiber in the adsorption and catalytic degradation of organic pigments in water.
[0009] To achieve the above objectives, the present invention adopts the following technical solution:
[0010] This invention provides a Ti-13X@GO / TPU composite fiber, which is composed of a thermoplastic polyurethane fiber matrix and a Ti-13X@GO composite filler dispersed therein; the Ti-13X@GO composite filler is a composite formed by titanium-doped 13X molecular sieve nanocrystals after surface modification with cationic surfactants and then electrostatic self-assembly with graphene oxide.
[0011] Furthermore, in the above-mentioned composite fiber, the mass ratio of titanium-doped 13X type molecular sieve nanocrystals to graphene oxide in the Ti-13X@GO composite filler is (10-50):1; the mass ratio of Ti-13X@GO composite filler to thermoplastic polyurethane is 1:(2-10); and the cationic surfactant is hexadecyltrimethylammonium bromide.
[0012] The present invention also provides a method for preparing the above-mentioned composite fiber, comprising the following steps:
[0013] (1) Pretreatment of silica: Tetrabutyl titanate was dissolved in anhydrous ethanol, mixed evenly, and then added dropwise to silica. After stirring and drying, pretreated silica was obtained.
[0014] (2) Preparation of mixture and steam-assisted crystallization: Sodium hydroxide and sodium aluminate were dissolved in deionized water, and the pretreated silica from step (1) was added. The mixture was stirred evenly and dried until a viscous substance was formed. Then it was placed in a hydrothermal reactor and steam-assisted aging and crystallization were carried out under the condition that deionized water was added at the bottom as a steam source to obtain titanium-doped 13X molecular sieve nanocrystals.
[0015] (3) Surface modification: The titanium-doped 13X molecular sieve nanocrystals obtained in step (2) are added to an aqueous solution of hexadecyltrimethylammonium bromide, heated and stirred to carry out surface modification, washed and dried to obtain modified molecular sieve;
[0016] (4) Graphene oxide dispersion: Graphene oxide is dispersed in an ethanol-water mixed solvent and ultrasonically exfoliated to obtain a graphene oxide dispersion.
[0017] (5) Electrostatic self-assembly: The modified molecular sieve from step (3) is added to the graphene oxide dispersion from step (4), stirred, centrifuged, washed, and dried to obtain Ti-13X@GO composite powder.
[0018] (6) Preparation of spinning solution: Thermoplastic polyurethane is dissolved in N,N-dimethylformamide to prepare a solution, and Ti-13X@GO composite powder from step (5) is added and dispersed evenly to obtain spinning solution; the mass ratio of Ti-13X@GO composite powder to thermoplastic polyurethane is 1:(2~10);
[0019] (7) Wet spinning: The spinning solution is extruded into an aqueous coagulation bath containing acetone through an injection pump, solidified and shaped, washed and dried to obtain the composite fiber.
[0020] In the above preparation method, in step (1), the molar ratio of tetrabutyl titanate, anhydrous ethanol and silica is preferably 0.8-2:100:100-300, and silica is calculated as SiO2; the drying temperature is preferably 40-50℃.
[0021] In step (2), the molar ratio of each material is 1:0.37~0.8:0.1~2 for silica:sodium aluminate:sodium hydroxide, and silica is calculated as SiO2. The drying is carried out at 50~80℃ until the moisture loss is 30%~80% of the mass of added deionized water. The preferred steam-assisted aging temperature is 20~30℃, and the aging time is 1~3 days. The preferred steam-assisted crystallization temperature is 70~90℃, and the crystallization time is 6~12 hours. The volume of deionized water added to the lining of the hydrothermal reactor is 4~10 mL.
[0022] In step (3), the concentration of the hexadecyltrimethylammonium bromide aqueous solution is preferably 0.05-0.1 mol / L; the solid-liquid ratio of titanium-doped 13X molecular sieve nanocrystals to the hexadecyltrimethylammonium bromide aqueous solution is 1:50 g / mL; the surface modification temperature is preferably 50-70℃ and the time is 12-24 hours.
[0023] In step (4), the preferred mass ratio of ethanol to water is 1:3 to 1:1, and the mass ratio of graphene oxide to the ethanol-water mixed solvent is 1:(1000 to 2500); ultrasonic exfoliation is performed under ice-water bath conditions for 30 to 60 minutes. In step (5), the mass ratio of modified molecular sieve to graphene oxide is (10 to 50):1, and the stirring time is 4 to 8 hours.
[0024] In step (6), the concentration of the thermoplastic polyurethane solution is preferably 15 wt%; in step (7), the extrusion rate is 0.5 to 2.0 mL / h, the coagulation bath is an aqueous solution containing 15 to 25 vol.% acetone, and the distance between the tip of the syringe needle and the surface of the coagulation bath is 1 to 3 cm.
[0025] The present invention also provides the application of the above-mentioned composite fiber in the decolorization treatment of wastewater containing organic dyes.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] (1) In this invention, titanium species were successfully embedded into the 13X molecular sieve framework in a four-coordinate form by steam-assisted crystallization. The resulting Ti-13X molecular sieve nanocrystals have high crystallinity and high purity, avoiding the generation of free TiO2 impurity phase and endowing the material with excellent photocatalytic potential.
[0028] (2) In this invention, hexadecyltrimethylammonium bromide is used to modify the surface of Ti-13X molecular sieve nanocrystals, changing their surface charge from negative to positive. This allows them to electrostatically self-assemble with negatively charged graphene oxide to form Ti-13X@GO composite filler. The introduction of GO effectively inhibits the aggregation of molecular sieve nanocrystals in the spinning solution and significantly improves the uniformity of filler dispersion in the thermoplastic polyurethane matrix. On the other hand, it enhances the interfacial bonding force between the filler and the polymer matrix, enabling the composite fiber to maintain good flexibility while possessing excellent mechanical integrity.
[0029] (3) The Ti-13X@GO / TPU composite fiber prepared by the present invention has both adsorption and photocatalytic decolorization functions. The preparation method is controllable and easy to operate. The composite fiber is a continuous long fiber, which is easy to separate and recover from the treatment liquid. It overcomes the defects of traditional powder adsorbents that are difficult to recover and easy to cause secondary pollution. It has good application prospects in the actual decolorization treatment of wastewater containing organic dyes. Attached image description:
[0030] Figure 1 The X-ray diffraction pattern of the Ti-13X type molecular sieve nanocrystals prepared in Example 1 of this invention;
[0031] Figure 2 The solid-state ultraviolet-visible spectrum of the Ti-13X molecular sieve nanocrystals prepared in Example 1 of this invention. Detailed implementation method:
[0032] The present invention will be further described below through specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.
[0033] Example 1:
[0034] Step 1: Pretreatment of silica
[0035] 0.453 g of tetrabutyl titanate was dissolved in 7.67 g of anhydrous ethanol and mixed thoroughly. The solution was then added dropwise to 10.0 g of silica while stirring. The resulting mixture was dried in an oven at 45°C for 8 hours to obtain pretreated silica.
[0036] Step 2: Preparation of the mixture
[0037] Dissolve 3.33 g of sodium hydroxide in 37.4 g of deionized water. After complete dissolution, add 5.05 g of sodium aluminate and stir magnetically for 30 min to form a homogeneous mixture. Add the pretreated silica obtained in step 1 to the mixture and stir thoroughly to obtain a final mixture. Dry the mixture in a 50°C oven to 48 g to obtain a viscous, homogeneous substance.
[0038] Step 3: Steam-assisted crystallization
[0039] The mixture was transferred to an open glass vessel, which was then placed into the lining of a hydrothermal reactor. 6 mL of deionized water was added to the lining to prevent water from outside the glass vessel from entering. The mixture was aged at 25°C with steam for 3 days. The hydrothermal reactor was then heated to 80°C and subjected to steam-assisted crystallization for 8 hours to obtain the crystalline product.
[0040] Step 4: Preparation of Ti-13X molecular sieve nanocrystals
[0041] The crystallized product was centrifuged and washed three times, dried at 50°C for 8 hours, and calcined at 400°C for 4 hours in a muffle furnace to obtain Ti-13X molecular sieve nanocrystals.
[0042] Step 5: Preparation of N-Ti-13X molecular sieve nanocrystals
[0043] Prepare a 0.075 mol / L aqueous solution of hexadecyltrimethylammonium bromide and heat it to 40°C to dissolve it. Add the Ti-13X molecular sieve nanocrystals obtained in step 4 to the CTAB solution at a solid-liquid ratio of 1:50 g / mL. After stirring in a water bath at 60°C for 18 hours, centrifuge and separate the nanocrystals. Wash them repeatedly with a large amount of deionized water and then dry them to obtain N-Ti-13X molecular sieve nanocrystals.
[0044] Step 6: Preparation of graphene oxide dispersion
[0045] Weigh 10 mg of graphene oxide (GO) powder and add it to a mixed solution of 17.5 g of anhydrous ethanol and deionized water, with a mass ratio of anhydrous ethanol to deionized water of 1:2. Place the mixture in an ultrasonic cell disruptor and ultrasonically disperse it for 45 minutes under ice-water bath conditions until the graphene oxide is completely exfoliated and forms a uniformly dispersed brownish-yellow suspension.
[0046] Step 7: Preparation of Ti-13X@GO composite powder
[0047] Step 6 was repeated 10 times at a ratio of 250 mg N-Ti-13X to 10 batches of GO dispersion, resulting in 10 batches of GO dispersion. 250 mg N-Ti-13X was added to each batch of GO dispersion, and the mixture was vigorously stirred at room temperature for 6 hours. After centrifugation, the supernatant was discarded, and the precipitate was collected. All 10 batches of precipitates were combined and washed twice each with anhydrous ethanol and deionized water, centrifuged after each wash. The washed complex was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain approximately 2.6 g of Ti-13X@GO composite powder. This powder was ground, sealed, and stored for later use.
[0048] Step 8: Preparation of Ti-13X@GO / TPU spinning solution
[0049] Weigh 1.0 g of the Ti-13X@GO composite powder obtained in step 7. Weigh 6.0 g of TPU particles according to a Ti-13X@GO to thermoplastic polyurethane (TPU) mass ratio of 1:6, dissolve them in 34.0 g of anhydrous N,N-dimethylformamide (DMF) to prepare a 15 wt% TPU solution, and magnetically stir at room temperature for 8 hours until completely dissolved to obtain the TPU spinning solution. Add the 1.0 g of Ti-13X@GO composite powder weighed above to the TPU spinning solution, first stir with a glass rod to initially mix, then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 minutes, and then transfer it to a high-speed disperser for stirring for 10 minutes until the composite powder is uniformly dispersed and there are no visible agglomerates.
[0050] Step 9: Wet spinning to prepare Ti-13X@GO / TPU composite fibers
[0051] The dispersion obtained in step 8 was transferred to a syringe and extruded at a rate of 1.0 mL / h into a coagulation bath containing an aqueous solution of 20 vol.% acetone. The needle tip was kept 2 cm away from the surface of the coagulation bath. The dispersion solidified into continuous fibers in the coagulation bath. After the fibers had completely solidified (approximately 30 minutes), the fibers were carefully removed with tweezers and immersed in deionized water for washing twice, 10 minutes each time, to remove residual DMF and acetone. Finally, the fibers were laid flat on a polytetrafluoroethylene plate and placed in a vacuum drying oven at 50°C for 12 hours to obtain Ti-13X@GO / TPU composite fibers.
[0052] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the Ti-13X molecular sieve nanocrystals prepared in Example 1. As can be seen from the figure, the product exhibits clear characteristic diffraction peaks at 2θ = 6.1°, 10.0°, 11.7°, 15.4°, 20.0°, 23.3°, 26.6°, and 31.0°. The peaks are sharp and have stable baselines, and no characteristic peaks of heterocrystalline phases such as sodalite or P-type zeolite are observed, indicating that the obtained product is a high-purity, highly crystalline 13X molecular sieve. Furthermore, the diffraction peaks are slightly broader than those of commercially available 13X molecular sieves, indicating that the grain size is at the nanoscale. Notably, no characteristic diffraction peaks of the anatase phase TiO2 were observed in the 2θ = 24°–26° range, indicating that the titanium species are highly dispersed within the molecular sieve framework or channels, rather than existing as free titanium oxide.
[0053] Figure 2The image shows the solid-state UV-Vis spectrum of the Ti-13X molecular sieve nanocrystals prepared in Example 1. A sharp UV-vis absorption peak appears in the 200-220 nm range, confirming the presence of four-coordinated Ti species within the Ti-13X molecular sieve nanocrystals. No TiO2 species were found in the XRD characterization. These results indicate that the Ti-13X molecular sieve nanocrystals synthesized using this method possess a four-coordinated framework of Ti species.
[0054] Example 2:
[0055] Step 1: Pretreatment of silica
[0056] 0.396 g of tetrabutyl titanate was dissolved in 3.83 g of anhydrous ethanol and mixed thoroughly. The solution was then added dropwise to 10.0 g of silica while stirring. The resulting mixture was dried in an oven at 45°C for 8 hours to obtain pretreated silica.
[0057] Step 2: Preparation of the mixture
[0058] Weigh 3.33 g of sodium hydroxide. Weigh 7.91 g of sodium aluminate. Dissolve 3.33 g of sodium hydroxide in 56.2 g of deionized water. After complete dissolution, add 7.91 g of sodium aluminate and stir magnetically for 30 min to form a homogeneous mixture. Add the pretreated silica prepared in step 1 to the above mixture and stir thoroughly to obtain a final mixture. Place the mixture in a 50°C oven and dry to 46.9 g (the water loss is 55% of the mass of added deionized water, approximately 30.9 g), obtaining a viscous homogeneous substance.
[0059] Step 3: Steam-assisted crystallization
[0060] The mixture was transferred to an open glass vessel, which was then placed into the lining of a hydrothermal reactor. 6 mL of deionized water was added to the lining to prevent water from outside the glass vessel from entering. The mixture was aged at 25°C with steam for 3 days. The hydrothermal reactor was then heated to 80°C and subjected to steam-assisted crystallization for 8 hours to obtain the crystalline product.
[0061] Step 4: Preparation of Ti-13X molecular sieve nanocrystals
[0062] The crystallized product was centrifuged and washed three times, dried at 50°C for 8 hours, and calcined at 400°C for 4 hours in a muffle furnace to obtain Ti-13X molecular sieve nanocrystals.
[0063] Step 5: Preparation of N-Ti-13X molecular sieve nanocrystals
[0064] Prepare a 0.05 mol / L aqueous solution of hexadecyltrimethylammonium bromide (CTAB) and dissolve it by heating to 40 °C. Add the Ti-13X molecular sieve nanocrystals obtained in step 4 to the CTAB solution at a solid-liquid ratio of 1:50 (g / mL). After stirring in a water bath at 60 °C for 18 hours, centrifuge and separate the nanocrystals. Wash repeatedly with a large amount of deionized water and dry to obtain N-Ti-13X molecular sieve nanocrystals.
[0065] Step 6: Preparation of graphene oxide dispersion
[0066] Weigh 10 mg of graphene oxide (GO) powder and add it to a mixed solution of 17.5 g of anhydrous ethanol and deionized water, with a mass ratio of anhydrous ethanol to deionized water of 1:2. Place the mixture in an ultrasonic cell disruptor and ultrasonically disperse it for 30 minutes under ice-water bath conditions until the graphene oxide is completely exfoliated and forms a uniformly dispersed brownish-yellow suspension.
[0067] Step 7: Preparation of Ti-13X@GO composite powder
[0068] Step 6 was repeated 10 times at a ratio of 250 mg N-Ti-13X to 10 batches of GO dispersion, resulting in 10 batches of GO dispersion. 250 mg N-Ti-13X was added to each batch of GO dispersion, and the mixture was vigorously stirred at room temperature for 6 hours. After centrifugation, the supernatant was discarded, and the precipitate was collected. All 10 batches of precipitates were combined and washed twice each with anhydrous ethanol and deionized water, centrifuged after each wash. The washed complex was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain approximately 2.6 g of Ti-13X@GO composite powder. This powder was ground, sealed, and stored for later use.
[0069] Step 8: Preparation of Ti-13X@GO / TPU spinning solution
[0070] Weigh 1.0 g of the Ti-13X@GO composite powder obtained in step 7. Weigh 6.0 g of TPU particles according to a Ti-13X@GO to thermoplastic polyurethane (TPU) mass ratio of 1:6, dissolve them in 34.0 g of anhydrous N,N-dimethylformamide (DMF) to prepare a 15 wt% TPU solution, and magnetically stir at room temperature for 8 hours until completely dissolved to obtain the TPU spinning solution. Add the 1.0 g of Ti-13X@GO composite powder weighed above to the TPU spinning solution, first stir with a glass rod to initially mix, then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 minutes, and then transfer it to a high-speed disperser for stirring for 10 minutes until the composite powder is uniformly dispersed and there are no visible agglomerates.
[0071] Step 9: Wet spinning to prepare Ti-13X@GO / TPU composite fibers
[0072] The dispersion obtained in step 8 was transferred to a syringe and extruded at a rate of 0.5 mL / h into a coagulation bath containing an aqueous solution of 20 vol.% acetone using a syringe pump. The needle tip was kept 2 cm away from the surface of the coagulation bath. The dispersion solidified into continuous fibers in the coagulation bath. After the fibers had completely solidified (approximately 30 minutes), the fibers were carefully removed with tweezers and immersed in deionized water for washing twice, 10 minutes each time, to remove residual DMF and acetone. Finally, the fibers were laid flat on a polytetrafluoroethylene plate and placed in a vacuum drying oven at 50°C for 12 hours to obtain Ti-13X@GO / TPU composite fibers.
[0073] Example 3:
[0074] Step 1: Pretreatment of silica
[0075] 0.377 g of tetrabutyl titanate was dissolved in 2.56 g of anhydrous ethanol and mixed thoroughly. The solution was then added dropwise to 10.0 g of silica while stirring. The resulting mixture was dried in an oven at 45°C for 8 hours to obtain pretreated silica.
[0076] Step 2: Preparation of the mixture
[0077] Weigh 3.33 g of sodium hydroxide. Weigh 10.91 g of sodium aluminate. Dissolve 3.33 g of sodium hydroxide in 71.2 g of deionized water. After complete dissolution, add 10.91 g of sodium aluminate and stir magnetically for 30 min to form a homogeneous mixture. Add the pretreated silica prepared in step 1 to the above mixture and stir thoroughly to obtain a final mixture. Place the mixture in a 50°C oven and dry to 38.8 g (moisture loss is 80% of the mass of added deionized water, 57.0 g), obtaining a viscous homogeneous substance.
[0078] Step 3: Steam-assisted crystallization
[0079] The mixture was transferred to an open glass vessel, which was then placed into the lining of a hydrothermal reactor. 6 mL of deionized water was added to the lining to prevent water from outside the glass vessel from entering. The mixture was aged at 25°C with steam for 3 days. The hydrothermal reactor was then heated to 80°C and subjected to steam-assisted crystallization for 8 hours to obtain the crystalline product.
[0080] Step 4: Preparation of Ti-13X molecular sieve nanocrystals
[0081] The crystallized product was centrifuged and washed three times, dried at 50°C for 8 hours, and calcined at 400°C for 4 hours in a muffle furnace to obtain Ti-13X molecular sieve nanocrystals.
[0082] Step 5: Preparation of N-Ti-13X molecular sieve nanocrystals
[0083] Prepare a 0.1 mol / L CTAB aqueous solution and heat it to 40℃ to dissolve. Add the Ti-13X molecular sieve nanocrystals obtained in step 4 to the CTAB solution at a solid-liquid ratio of 1:50 (g / mL). After stirring in a water bath at 60℃ for 18 hours, centrifuge and separate the nanocrystals. Wash them repeatedly with a large amount of deionized water and then dry them to obtain N-Ti-13X molecular sieve nanocrystals.
[0084] Step 6: Preparation of graphene oxide dispersion
[0085] Weigh 10 mg of GO powder and add it to a mixed solution of 17.5 g of anhydrous ethanol and deionized water, with a mass ratio of anhydrous ethanol to deionized water of 1:2. Place the mixture in an ultrasonic cell disruptor and ultrasonically disperse it for 60 minutes under ice-water bath conditions until the graphene oxide is completely exfoliated and forms a uniformly dispersed brownish-yellow suspension.
[0086] Step 7: Preparation of Ti-13X@GO composite powder
[0087] Step 6 was repeated 10 times at a ratio of 250 mg N-Ti-13X to 10 batches of GO dispersion, resulting in 10 batches of GO dispersion. 250 mg N-Ti-13X was added to each batch of GO dispersion, and the mixture was vigorously stirred at room temperature for 6 hours. After centrifugation, the supernatant was discarded, and the precipitate was collected. All 10 batches of precipitates were combined and washed twice each with anhydrous ethanol and deionized water, centrifuged after each wash. The washed complex was placed in a vacuum drying oven and dried at 50°C for 12 hours to obtain approximately 2.6 g of Ti-13X@GO composite powder. This powder was ground, sealed, and stored for later use.
[0088] Step 8: Preparation of Ti-13X@GO / TPU spinning solution
[0089] Weigh 1.0 g of the Ti-13X@GO composite powder obtained in step 7. Weigh 6.0 g of TPU particles according to a Ti-13X@GO to thermoplastic polyurethane (TPU) mass ratio of 1:6, dissolve them in 34.0 g of anhydrous N,N-dimethylformamide (DMF) to prepare a 15 wt% TPU solution, and magnetically stir at room temperature for 8 hours until completely dissolved to obtain the TPU spinning solution. Add the 1.0 g of Ti-13X@GO composite powder weighed above to the TPU spinning solution, first stir with a glass rod to initially mix, then place it in an ultrasonic cleaner for ultrasonic dispersion for 30 minutes, and then transfer it to a high-speed disperser for stirring for 10 minutes until the composite powder is uniformly dispersed and there are no visible agglomerates.
[0090] Step 9: Wet spinning to prepare Ti-13X@GO / TPU composite fibers
[0091] The dispersion obtained in step 8 was transferred to a syringe and extruded at a rate of 2.0 mL / h into a coagulation bath containing an aqueous solution of 20 vol.% acetone using a syringe pump. The needle tip was kept 2 cm away from the surface of the coagulation bath. The dispersion solidified into continuous fibers in the coagulation bath. After the fibers had completely solidified (approximately 30 minutes), the fibers were carefully removed with tweezers and immersed in deionized water for washing twice, 10 minutes each time, to remove residual DMF and acetone. Finally, the fibers were laid flat on a polytetrafluoroethylene plate and placed in a vacuum drying oven at 50°C for 12 hours to obtain Ti-13X@GO / TPU composite fibers.
[0092] Comparative Example 1:
[0093] Step 1: Pretreatment of silica
[0094] 0.453 g of tetrabutyl titanate was dissolved in 7.67 g of anhydrous ethanol and mixed thoroughly. The solution was then added dropwise to 10.0 g of silica while stirring. The resulting mixture was dried in an oven at 45°C for 8 hours to obtain pretreated silica.
[0095] Step 2: Preparation of the mixture
[0096] Dissolve 3.33 g of sodium hydroxide in 37.4 g of deionized water. After complete dissolution, add 5.05 g of sodium aluminate and stir magnetically for 30 min to form a homogeneous mixture. Add the pretreated silica obtained in step 1 to the mixture and stir thoroughly to obtain a final mixture. Dry the mixture in a 50°C oven to 48 g to obtain a viscous, homogeneous substance.
[0097] Step 3: Steam-assisted crystallization
[0098] The mixture was transferred to an open glass vessel, which was then placed into the lining of a hydrothermal reactor. 6 mL of deionized water was added to the lining to prevent water from outside the glass vessel from entering. The mixture was aged at 25°C with steam for 3 days. The hydrothermal reactor was then heated to 80°C and subjected to steam-assisted crystallization for 8 hours to obtain the crystalline product.
[0099] Step 4: Preparation of Ti-13X molecular sieve nanocrystals
[0100] The crystallized product was centrifuged and washed three times, dried at 50°C for 8 hours, and calcined at 400°C for 4 hours in a muffle furnace to obtain Ti-13X molecular sieve nanocrystals.
[0101] Step 5: Preparation of Ti-13X / TPU spinning solution
[0102] Weigh 1.0 g of the Ti-13X powder obtained in step 4. Weigh 6.0 g of TPU particles according to a Ti-13X to thermoplastic polyurethane (TPU) mass ratio of approximately 1:6, dissolve them in 34.0 g of anhydrous N,N-dimethylformamide (DMF) to prepare a 15 wt% TPU solution. Stir magnetically at room temperature for 8 hours until completely dissolved to obtain the TPU spinning solution. Add the 1.0 g of Ti-13X powder weighed above to the TPU spinning solution, first stir with a glass rod to initially mix, then place in an ultrasonic cleaner for ultrasonic dispersion for 30 minutes, and then transfer to a high-speed disperser for stirring for 10 minutes until the powder is uniformly dispersed and no visible agglomerates are present.
[0103] Step 6: Wet spinning to prepare Ti-13X / TPU composite fibers
[0104] The dispersion obtained in step 5 was transferred to a syringe and extruded at a rate of 1.0 mL / h into a coagulation bath containing an aqueous solution of 20 vol.% acetone. The needle tip was kept 2 cm away from the surface of the coagulation bath. The dispersion solidified into continuous fibers in the coagulation bath. After the fibers had completely solidified (approximately 30 minutes), the fibers were carefully removed with tweezers and immersed in deionized water for washing twice, 10 minutes each time, to remove residual DMF and acetone. Finally, the fibers were laid flat on a polytetrafluoroethylene plate and placed in a vacuum drying oven at 50°C for 12 hours to obtain Ti-13X / TPU composite fibers.
[0105] Performance testing:
[0106] The composite fibers prepared above were cut into short fibers of 2–3 cm in length. 50 mg of the fiber sample was weighed and added to 100 mL of a 20 mg / L methylene blue aqueous solution. The mixture was magnetically stirred in a dark chamber for 180 minutes under UV light (365 nm, 250 W). Samples were taken every 30 minutes, and the absorbance of the solution at 664 nm was measured using a UV-Vis spectrophotometer to calculate the methylene blue removal rate.
[0107] After completing one decolorization experiment, the fibers were removed with tweezers and immersed in 50 mL of deionized water for 10 minutes, repeating the washing process twice. After washing, the fibers were removed and dried in a vacuum drying oven at 50℃ until constant weight. The dried fibers were then immersed again in 100 mL of freshly prepared 20 mg / L methylene blue solution under the exact same conditions as the first use (UV lamp irradiation at 365 nm, 250 W, and magnetic stirring in a dark chamber) for the next round of decolorization experiments. Each round of experiments lasted 180 minutes, and samples were taken after the reaction to determine the removal rate. This cycle was repeated to examine the reusability of the fibers.
[0108] Table 1. Performance comparison between each embodiment and the comparative example
[0109] Test metrics Example 1 Example 2 Example 3 Comparative Example 1 180 min MB removal rate (%) 98.2 99.1 93.0 62.0 Removal rate (%) in the 5th cycle 85.2 90.3 78.1 No complete structure Fiber reusability excellent excellent good Difference Fiber integrity after 5 cycles intact intact Localized microcracks Cracks and crumbles
[0110] The Ti-13X@GO / TPU composite fibers prepared in Examples 1-3 all achieved a methylene blue removal rate of over 93%, and the removal rate remained above 78% after 5 cycles, demonstrating good fiber reusability and good fiber integrity after cycling. Example 2 showed the best overall performance. In contrast, Comparative Example 1, without GO self-assembly, achieved a removal rate of only 62.0% and exhibited poor repeatability. These results demonstrate that CTAB surface modification and the GO electrostatic self-assembly strategy significantly improve the decolorization performance, cycling stability, and mechanical integrity of the composite fibers.
Claims
1. A Ti-13X@GO / TPU composite fiber, characterized in that, The product comprises a thermoplastic polyurethane fiber matrix and a Ti-13X@GO composite filler dispersed therein; the Ti-13X@GO composite filler is a composite formed by titanium-doped 13X molecular sieve nanocrystals after surface modification with cationic surfactants and electrostatic self-assembly with graphene oxide.
2. The Ti-13X@GO / TPU composite fiber according to claim 1, characterized in that, In the Ti-13X@GO composite filler, the mass ratio of titanium-doped 13X molecular sieve nanocrystals to graphene oxide is (10~50):1; the mass ratio of the Ti-13X@GO composite filler to thermoplastic polyurethane is 1:(2~10); and the cationic surfactant is hexadecyltrimethylammonium bromide.
3. A method for preparing Ti-13X@GO / TPU composite fiber as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Pretreatment of silica: Tetrabutyl titanate was dissolved in anhydrous ethanol, mixed evenly, and then added dropwise to silica. After stirring and drying, pretreated silica was obtained. (2) Preparation of mixture and steam-assisted crystallization: Sodium hydroxide and sodium aluminate were dissolved in deionized water, and the pretreated silica from step (1) was added. The mixture was stirred evenly and dried until a viscous substance was formed. Then it was placed in a hydrothermal reactor and steam-assisted aging and crystallization were carried out under the condition that deionized water was added at the bottom as a steam source to obtain titanium-doped 13X molecular sieve nanocrystals. (3) Surface modification: The titanium-doped 13X molecular sieve nanocrystals obtained in step (2) are added to an aqueous solution of hexadecyltrimethylammonium bromide, heated and stirred to carry out surface modification, washed and dried to obtain modified molecular sieve; (4) Graphene oxide dispersion: Graphene oxide is dispersed in an ethanol-water mixed solvent and ultrasonically exfoliated to obtain a graphene oxide dispersion. (5) Electrostatic self-assembly: The modified molecular sieve from step (3) is added to the graphene oxide dispersion from step (4), stirred, centrifuged, washed, and dried to obtain Ti-13X@GO composite powder; wherein the mass ratio of the modified molecular sieve to graphene oxide is (10~50):
1. (6) Preparation of spinning solution: Thermoplastic polyurethane is dissolved in N,N-dimethylformamide to prepare a solution, and Ti-13X@GO composite powder from step (5) is added and dispersed evenly to obtain spinning solution; the mass ratio of Ti-13X@GO composite powder to thermoplastic polyurethane is 1:(2~10); (7) Wet spinning: The spinning solution is extruded into an aqueous coagulation bath containing acetone through an injection pump, solidified and shaped, washed and dried to obtain the composite fiber.
4. The method for preparing Ti-13X@GO / TPU composite fiber according to claim 3, characterized in that, In step (1), the molar ratio of tetrabutyl titanate, anhydrous ethanol and silica is 0.8~2:100:100~300, and silica is calculated as SiO2; the drying temperature is 40~50℃.
5. The method for preparing Ti-13X@GO / TPU composite fiber according to claim 3, characterized in that, In step (2), the molar ratio of each material is 1:0.37~0.8:0.1~2, and the fumed silica is calculated as SiO2; the drying is carried out at 50~80℃ until the moisture loss is 30%~80% of the mass of added deionized water.
6. The method for preparing Ti-13X@GO / TPU composite fiber according to claim 5, characterized in that, In step (2), the steam-assisted aging temperature is 20~30℃ and the aging time is 1~3 days; the steam-assisted crystallization temperature is 70~90℃ and the crystallization time is 6~12 hours; the volume of deionized water added to the lining of the hydrothermal reactor is 4~10 mL.
7. The method for preparing Ti-13X@GO / TPU composite fiber according to claim 3, characterized in that, In step (3), the concentration of the hexadecyltrimethylammonium bromide aqueous solution is 0.05~0.1 mol / L; the solid-liquid ratio of titanium-doped 13X molecular sieve nanocrystals to the hexadecyltrimethylammonium bromide aqueous solution is 1:50 g / mL; the surface modification temperature is 50~70℃ and the time is 12~24 hours.
8. The method for preparing Ti-13X@GO / TPU composite fiber according to claim 3, characterized in that, In step (4), the mass ratio of ethanol to water is 1:(1~3), and the mass ratio of graphene oxide to ethanol-water mixed solvent is 1:(1000~2500); ultrasonic exfoliation is carried out under ice-water bath conditions for 30~60 minutes; in step (5), the stirring time is 4~8 hours.
9. The application of the composite fiber according to claim 1 or 2, or the composite fiber prepared by the method according to any one of claims 3-8, in the decolorization treatment of wastewater containing organic dyes.