A nanopyl high-charge layered grid carbon fiber material and a preparation method thereof

Abstract

This invention relates to the field of water purification materials technology, specifically to a nano-sized, highly charged layered electrical grid carbon fiber material, comprising activated carbon fiber, an active component, and a hydrophilic modification layer. The material uses activated carbon fiber as a substrate, then adsorbs the active component onto the substrate to obtain an intermediate, and subsequently coats the surface of the intermediate with a hydrophilic modification layer to prepare the final product. The active component is Zn-Al-La ternary LDH. This invention's Zn-Al-La ternary layered polymetallic hydroxide composite activated carbon fiber water purification material uses activated carbon fiber as a substrate, Zn-Al-La ternary LDH as the core adsorption active component, and a hydrophilic modification layer on the surface. These three components are compounded according to a specific mass ratio and process, and the synergistic effect of each component achieves simultaneous and efficient removal of multiple pollutants.

Description

Technical Field

[0001] This invention relates to the field of water purification functional materials technology, specifically to a nano-highly charged layered grid carbon fiber material and its preparation method. Background Technology

[0002] With the acceleration of industrialization and the increasing frequency of human production and daily life activities, water pollution is exhibiting significant characteristics of being complex, diversified, and difficult to degrade. Purification of single types of pollutants is no longer sufficient to meet actual water purification needs. Currently, drinking water and industrial wastewater commonly contain bacteria (such as Escherichia coli and Staphylococcus aureus), viruses (such as SARS-CoV-2 and bacteriophages), and heavy metal ions (such as Pb). 2+ Cd 2+ Microplastics (1-5μm), antibiotics (such as tetracycline and amoxicillin), PFAS (such as perfluorooctanoic acid PFOA and perfluorooctane sulfonate PFOS), VOCs (such as chloroform and carbon tetrachloride), and organic pollutants (characterized by COD) interact with each other, posing a serious threat to the ecological environment and human health. Summary of the Invention

[0003] In view of the above-mentioned shortcomings of the prior art, the present invention provides a nano-charged high-charge layered electrical grid carbon fiber material and its preparation method, which can effectively solve the above-mentioned problems of the prior art.

[0004] Technical solution

[0005] To achieve the above objectives, the present invention provides the following technical solution: A nano-charged layered electrical grid carbon fiber material includes activated carbon fiber, an active component, and a hydrophilic modification layer. The material is prepared by using activated carbon fiber as a substrate, then adsorbing the active component on the substrate to obtain an intermediate, and then coating the surface of the intermediate with a hydrophilic modification layer. The active component is Zn-Al-La ternary LDH.

[0006] Furthermore, the activated carbon fiber is made of polyacrylonitrile-based activated carbon fiber, with a diameter of 8-15 μm, a length of 2-6 cm, and a specific surface area of ​​1200-1800 m². 2With a porosity of 70%-85% and a pore size distribution of 2-50 nm, this type of ACF possesses a well-developed pore structure and a large specific surface area, providing ample loading sites for Zn-Al-La ternary LDH. Simultaneously, it exhibits a certain physical adsorption capacity, which can assist in the adsorption of organic pollutants and VOCs in water, enhancing the water purification effect of the material. To further improve the binding force between ACF and Zn-Al-La ternary LDH, the ACF needs to undergo pretreatment to remove surface impurities and inert groups, and introduce active groups (hydroxyl and carboxyl groups) to provide binding sites for the subsequent in-situ growth of LDH.

[0007] Furthermore, the Zn-Al-La ternary LDH uses Zn 2+ Al 3+ La 3+ Three metal ions are arranged in a specific molar ratio to form a layered structure, and the Zn 2+ ∶Al 3+ ∶La 3+ The molar ratio of metal ions is (2.8–3.2):(1.0–1.3):(0.4–0.7). The interlayer anion of Zn-Al-La ternary LDH is Cl⁻, the interlayer spacing is 0.8-1.2 nm, and the surface Zeta potential is +32 to +48 mV.

[0008] Furthermore, the active component is loaded onto activated carbon fiber via in-situ co-precipitation. The hydrophilic modified layer adopts a composite system of chitosan and dopamine, and the thickness of the hydrophilic modified layer is 30-80 nm.

[0009] Furthermore, based on a total weight percentage of 100%, it includes 50–65 wt% activated carbon fiber, 30–45 wt% active components, and 3–8 wt% hydrophilic modification layer.

[0010] Preferably, based on a total weight percentage of 100%, it comprises 52–62 wt% activated carbon fiber, 33–43 wt% active components, and 5 wt% hydrophilic modified layer.

[0011] A method for preparing a nano-charged layered electrical grid carbon fiber material includes the following steps: S1: Pretreatment of activated carbon fiber: Pretreatment of activated carbon fiber to obtain ACF substrate; S2: Prepare a Zn-Al-La ternary metal salt mixture; S3: An LDH-loaded ACF intermediate was obtained by in-situ co-precipitation of Zn-Al-La ternary LDH on an ACF substrate; S4: The LDH-loaded ACF intermediate is washed and dried to obtain LDH-loaded ACF; S5: The LDH-loaded ACF is surface-modified with hydrophilicity to obtain nano-charged layered grid carbon fiber material.

[0012] The activated carbon fiber pretreatment steps in step S1 are as follows: (1) Select polyacrylonitrile-based activated carbon fiber, cut it into fiber segments of 2-6 cm in length, put it into deionized water, and ultrasonically clean it for 15-25 min (ultrasonic power 200-300W, frequency 40kHz) to remove dust, impurities and residual organic pollutants from the surface. (2) Place the ultrasonically cleaned ACF into a beaker, add a 5%-10% dilute hydrochloric acid solution, and soak at room temperature for 30-60 minutes to remove metal impurities and inert groups on the surface of ACF, while introducing active groups such as hydroxyl and carboxyl groups on the surface. (3) Rinse the ACF repeatedly with deionized water until the pH of the rinsing solution is 7.0±0.2, then put it in an oven and dry it at 60~70℃ until constant weight (the criterion for drying to constant weight is: the mass difference between two consecutive weighings ≤0.001g). After taking it out, put it in a desiccator for later use to obtain the pretreated ACF substrate.

[0013] In step S2, the method for preparing the Zn-Al-La ternary metal salt mixture is as follows: (1) According to Zn 2+ ∶Al 3+ ∶La 3+ = (2.8~3.2) ∶ (1.0~1.3) ∶ (0.4~0.7) molar ratio, weigh out zinc chloride hexahydrate (ZnCl2·6H2O), aluminum chloride hexahydrate (AlCl3·6H2O), and lanthanum chloride heptahydrate (LaCl3·7H2O) respectively, and put them into beakers; (2) Add an appropriate amount of deionized water to the beaker, place it on a magnetic stirrer, and stir at room temperature for 30-60 min (stirring speed 150-200 r / min) until the three metal salts are completely dissolved to obtain a Zn-Al-La ternary metal salt mixture with a concentration of 0.15-0.3 mol / L. (3) After stirring, filter the mixture with filter paper to remove undissolved impurities and ensure that the mixture is uniform and transparent for later use.

[0014] The preparation method of step S3 is as follows: (1) Place the pretreated ACF substrate into a three-necked flask, add the prepared Zn-Al-La ternary metal salt mixture, ensure that the ACF is completely immersed in the mixture, place it on a constant temperature water bath, adjust the water bath temperature to 55-75℃, keep it warm and stir for 10-20 minutes to fully wet the ACF surface and prepare for the in-situ growth of LDH. (2) Slowly add a dilute NaOH solution with a concentration of 0.1-0.2 mol / L using a pipette, and control the dropping rate to 1-2 drops / second to avoid local pH being too high and causing LDH particles to agglomerate. At the same time, use a pH meter to monitor the pH value of the mixture in real time and adjust the pH of the mixture to 9.0-9.8. (3) After pH adjustment, maintain the water bath temperature at 55-75℃ and continue the reaction for 6-10 hours, stirring once every 2 hours for 10-15 minutes each time to ensure Zn 2+ Al 3+ La 3+ A co-precipitation reaction occurs simultaneously on the ACF surface to form Zn-Al-La ternary LDH, which is uniformly loaded on the ACF surface and in the pores. (4) After the reaction is complete, turn off the constant temperature water bath, wait for the mixture to cool to room temperature, filter by vacuum filtration, and collect the filter cake (i.e. LDH-supported ACF intermediate).

[0015] The specific method for step S4 is as follows: (1) Place the LDH-supported ACF intermediate obtained by vacuum filtration into a beaker, add deionized water, stir and wash for 10-15 min, then vacuum filter, repeat the water washing-vacuum filtration operation 3-5 times until the pH of the rinsing solution is 7.0±0.2 to remove residual metal ions and NaOH on the surface; (2) Place the washed intermediate into an oven and dry it at 60-70℃ for 4-6 hours. Turn it over once every 1 hour during the drying process to ensure uniform drying. The intermediate of Zn-Al-La ternary LDH / ACF composite material is obtained and placed in a desiccator for later use.

[0016] The specific method for step S5 is as follows: (1) Preparation of chitosan-dopamine composite modified solution: Weigh a certain amount of dopamine, dissolve it in Tris-HCl buffer solution (pH=8.5), stir for 20-30 min to obtain a dopamine solution with a concentration of 0.4-0.8 g / L; then add chitosan to the dopamine solution, continue stirring for 30-40 min to completely dissolve the chitosan, adjust the chitosan concentration to 0.2-0.5 g / L to obtain the chitosan-dopamine composite modified solution; (2) The intermediate of Zn-Al-La ternary LDH / ACF composite material was placed in the composite modification solution and soaked at room temperature for 2-4 hours. During this period, the mixture was stirred once every 30 minutes to ensure that the modification solution fully wetted the surface of the intermediate, so that dopamine could undergo self-polymerization on the LDH surface and cross-link with chitosan to form a stable hydrophilic modification layer. (3) After soaking, vacuum filter, rinse the filter cake with deionized water 2-3 times to remove the unreacted modifier on the surface, and then put it in an oven and dry it at 60-70℃ for 2-4 hours to obtain the finished product of Zn-Al-La ternary layered bimetallic hydroxide composite activated carbon fiber water purification material.

[0017] A nano-charged layered grid carbon fiber material and the material prepared by the above-described preparation method are used to simultaneously remove bacteria, viruses, heavy metal ions, microplastics, antibiotics, perfluorinated and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOCs) and chemical oxygen demand (COD) from water bodies. It is suitable for drinking water purification, industrial wastewater treatment and groundwater remediation.

[0018] As the core adsorption active component of the material, Zn-Al-La ternary LDH uses Zn 2+ Al 3+ La 3+ Three metal ions were used to construct a layered structure in a specific molar ratio. After extensive experimental optimization, the molar ratio of the metal ions was strictly controlled as follows: Zn 2+ ∶Al 3+ ∶La 3+ = 2.8~3.2 ∶ 1.0~1.3 ∶ 0.4~0.7. This ratio ensures that LDH possesses excellent layered structure, high positive charge, and good adsorption activity. The roles of each metal ion are as follows: Zn 2+ As a divalent metal cation, it participates in the construction of LDH layers and has the intrinsic activity of broad-spectrum antibacterial and virus inactivation. It can destroy the integrity of bacterial cell membranes, causing leakage of intracellular substances and inactivation of bacteria. At the same time, it can destroy the viral capsid structure, exposing viral nucleic acids and losing their infectivity, thus enhancing the material's removal effect on bacteria and viruses. Al 3+ As a trivalent metal cation, it is mainly used to adjust the interlayer charge density of LDH, optimize the layered structure of LDH, improve the surface positive charge and ternary stability of the material, and enhance the electrostatic adsorption capacity of negatively charged pollutants (bacteria, viruses, microplastics, PFAS, etc.) in water. La 3+Rare earth metal ions, when introduced, can further optimize and stabilize the interlayer spacing and surface active sites of LDH, enhance the adsorption capacity for PFAS, antibiotics, and halogenated VOCs (chloroform, carbon tetrachloride), and also have a certain catalytic degradation effect, which can convert some recalcitrant organic pollutants into harmless substances, thereby improving the material's COD removal efficiency.

[0019] The interlayer anion of Zn-Al-La ternary LDH is Cl⁻, the interlayer spacing is 0.8-1.2 nm, the surface Zeta potential is +32 to +48 mV, and it has strong positive charge, which can rapidly adsorb negatively charged pollutants in water through electrostatic attraction. LDH is loaded onto the surface of ACF by in-situ co-precipitation to form an “ACF@LDH” core-shell structure. LDH particles are uniformly dispersed on the surface and in the pores of ACF, with a particle size of 80-200 nm. There is no obvious agglomeration phenomenon, which can fully expose the adsorption active sites and improve the adsorption efficiency of the material.

[0020] To further enhance the bonding force between Zn-Al-La ternary LDH and the ACF substrate, and to improve the material's hydrophilicity and biocompatibility, making it easier to disperse in water and fully contact pollutants, a hydrophilic modification layer is coated onto the LDH surface. The modifier is a composite system of chitosan and dopamine, with a thickness of 30-80 nm, uniformly covering the LDH surface. The catechol groups in the dopamine molecule can chemically bond with the hydroxyl groups on the LDH surface and the active groups on the ACF surface, while the amino groups in the chitosan molecule can cross-link with the quinone groups in the dopamine molecule, forming a stable composite modification layer. This not only effectively prevents LDH powder from detaching but also further enhances the material's adsorption capacity for various pollutants through the amino groups of chitosan and the catechol groups of dopamine.

[0021] Layered polymetallic hydroxides (LDHs), as a novel type of anionic layered clay mineral, possess excellent properties such as interlayer anion exchangeability, large specific surface area, adjustable surface charge, and good environmental compatibility. Their general chemical formula is: M 2+ It is a divalent metal cation, M 3+ It is a trivalent metal cation, An - As interlayer anions, the surface charge and adsorption performance of LDH can be precisely optimized by controlling the type and ratio of metal ions in the layers, making it a research hotspot in the field of water pollutant adsorption. Activated carbon fiber (ACF) has a well-developed pore structure, a large specific surface area, good conductivity, and chemical stability. As a carrier for LDH, it can effectively solve the problems of LDH's easy aggregation, difficult recovery, and insufficient exposure of adsorption active sites. The LDH-ACF composite material formed by combining the two has good effects in the field of water purification.

[0022] Beneficial effects

[0023] The technical solution provided by this invention has the following advantages compared with known public technologies: (1) The present invention provides a Zn-Al-La ternary layered double hydroxide (LDH) composite activated carbon fiber water purification material and its preparation method, which can be widely used in drinking water terminal filtration, outdoor emergency water purification, whole house water purification system, industrial wastewater deep treatment, groundwater remediation and other scenarios. It can simultaneously and efficiently remove bacteria, viruses, heavy metal ions, microplastics, antibiotics, perfluorinated and polyfluoroalkyl substances (PFAS), volatile organic compounds (VOC, specifically chloroform and carbon tetrachloride) and chemical oxygen demand (COD) and other complex pollutants in water, and solve the technical problems of existing water purification materials such as single function, easy infringement, poor stability and insufficient test data; (2) The Zn-Al-La ternary layered multimetal hydroxide composite activated carbon fiber water purification material of the present invention uses activated carbon fiber as the base, Zn-Al-La ternary LDH as the core adsorption active component, and a hydrophilic modified layer on the surface. The three components are compounded according to a specific mass ratio and process. The components work synergistically to achieve simultaneous and efficient removal of multiple pollutants. (3) The in-situ co-precipitation method is used to achieve uniform loading of Zn-Al-La ternary LDH on the ACF surface. Combined with surface hydrophilic modification, the bonding force between LDH and ACF is significantly improved, and LDH powder is prevented from falling off. The process steps are simple, no high temperature and high pressure equipment is required, energy consumption is low, raw materials are readily available (zinc chloride hexahydrate, aluminum chloride hexahydrate, lanthanum chloride heptahydrate, activated carbon fiber, etc. are all conventional chemical raw materials), production cost is low, controllability is strong, and it is suitable for large-scale industrial production. (4) The Zn-Al-La ternary LDH composite activated carbon fiber water purification material of the present invention, through the synergistic effect of ACF substrate, Zn-Al-La ternary LDH active component and hydrophilic modification layer, adopts a five-in-one action mechanism of "physical interception + electrostatic adsorption + ion exchange + complexation precipitation + catalytic degradation" to achieve simultaneous and efficient removal of multiple pollutants in response to the physicochemical properties of different pollutants. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] The present invention will be further described below with reference to embodiments.

[0026] (I) Implementation Examples Example 1

[0027] A Zn-Al-La ternary layered bimetallic hydroxide composite activated carbon fiber water purification material, wherein the mass percentages of each component are: activated carbon fiber (ACF) 58 wt%, Zn-Al-La ternary LDH 37 wt%, and hydrophilic modified layer 5 wt%.

[0028] Among them, Zn in Zn-Al-La ternary LDH 2+ ∶Al 3+ ∶La 3+ The molar ratio is 3.0:1.2:0.5; the ACF is made of polyacrylonitrile, with a diameter of 10μm, a length of 4cm, a specific surface area of ​​1500m² / g, and a porosity of 78%; the LDH has a particle size of 100-150nm and a surface Zeta potential of +41mV; the hydrophilic modification layer is a chitosan-dopamine composite layer with a thickness of 50nm.

[0029] The preparation method of the material is as follows: S1. Pretreatment of activated carbon fiber: Select polyacrylonitrile-based ACF, cut it into 4cm lengths, ultrasonically clean it for 20min (power 250W, frequency 40kHz), soak it in 8% dilute hydrochloric acid for 45min, rinse it with deionized water until pH=7.0, and dry it at 70℃ to constant weight for later use. S2. Preparation of metal salt mixture: According to Zn 2+ ∶Al 3+ ∶La 3+ Weigh out ZnCl2·6H2O, AlCl3·6H2O, and LaCl3·7H2O in a molar ratio of 3.0:1.2:0.5, dissolve them in deionized water, stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L, and filter for later use. S3. In-situ coprecipitation loading: Place the pretreated ACF into a three-necked flask, add the mixed solution, keep the mixture in a constant temperature water bath at 65℃, stir for 15 min, slowly add 0.15 mol / L NaOH solution (dropping rate 1.5 drops / second), adjust the pH to 9.3, keep the reaction at this temperature for 8 h, stirring for 12 min every 2 h during the reaction, filter after the reaction is complete, and collect the intermediate. S4. Washing and drying: Wash the intermediate 4 times with deionized water until pH=7.0, and dry at 65℃ for 5h to obtain the LDH / ACF intermediate; S5. Surface modification: Prepare a 0.6 g / L dopamine-Tris buffer solution (pH=8.5), add chitosan to a concentration of 0.3 g / L, and stir for 35 min; place the intermediate into the modification solution, soak at room temperature for 3 h, filter, rinse twice with deionized water, and dry at 65℃ for 3 h to obtain the finished product.

[0030] Example 2: A Zn-Al-La ternary layered bimetallic hydroxide composite activated carbon fiber water purification material, wherein the mass percentages of each component are: activated carbon fiber (ACF) 62 wt%, Zn-Al-La ternary LDH 33 wt%, and hydrophilic modified layer 5 wt%.

[0031] Among them: Zn in Zn-Al-La ternary LDH 2+ ∶Al 3+ ∶La 3+ The molar ratio is 2.8:1.0:0.4; the ACF is made of polyacrylonitrile, with a diameter of 8μm, a length of 2cm, a specific surface area of ​​1300m² / g, and a porosity of 70%; the LDH has a particle size of 80-120nm and a surface Zeta potential of +35mV; the hydrophilic modification layer is a chitosan-dopamine composite layer with a thickness of 30nm.

[0032] The preparation method of the material: S1. Pretreatment of activated carbon fiber: Select polyacrylonitrile-based ACF, cut it into 2cm lengths, ultrasonically clean it for 15min (power 200W, frequency 40kHz), soak it in 5% dilute hydrochloric acid for 30min, rinse it with deionized water until pH=7.0, and dry it at 60℃ to constant weight for later use. S2. Preparation of metal salt mixture: According to Zn 2+ ∶Al 3+ ∶La 3+ Weigh out ZnCl2·6H2O, AlCl3·6H2O, and LaCl3·7H2O in a molar ratio of 2.8:1.0:0.4, dissolve them in deionized water, stir for 30 min (150 r / min) to obtain a mixed solution with a concentration of 0.15 mol / L, and filter for later use. S3. In-situ coprecipitation loading: Place the pretreated ACF into a three-necked flask, add the mixed solution, keep the temperature in a constant water bath at 60℃, stir for 10 min, slowly add 0.1 mol / L NaOH solution (dropping rate 1 drop / second), adjust the pH to 9.0, keep the reaction at the temperature for 6 h, stirring for 10 min every 2 h during the reaction, filter after the reaction is completed, and collect the intermediate; S4. Washing and drying: Wash the intermediate three times with deionized water until pH=7.0, and dry at 60℃ for 4 hours to obtain the LDH / ACF intermediate; S5. Surface modification: Prepare a 0.4 g / L dopamine-Tris buffer solution (pH=8.5), add chitosan to a concentration of 0.2 g / L, and stir for 30 min; immerse the intermediate in the modification solution, soak at room temperature for 2 h, filter, rinse twice with deionized water, and dry at 60℃ for 2 h to obtain the finished product.

[0033] Example 3: A Zn-Al-La ternary layered bimetallic hydroxide composite activated carbon fiber water purification material, wherein the mass percentages of each component are: activated carbon fiber (ACF) 52 wt%, Zn-Al-La ternary LDH 43 wt%, and hydrophilic modified layer 5 wt%.

[0034] Among them: Zn in Zn-Al-La ternary LDH 2+ ∶Al 3+ ∶La 3+ The molar ratio is 3.2:1.3:0.7; the ACF is made of polyacrylonitrile, with a diameter of 15μm, a length of 6cm, a specific surface area of ​​1700m² / g, and a porosity of 85%; the LDH has a particle size of 150-200nm and a surface Zeta potential of +48mV; the hydrophilic modification layer is a chitosan-dopamine composite layer with a thickness of 80nm.

[0035] The preparation method of the material: S1. Pretreatment of activated carbon fiber: Select polyacrylonitrile-based ACF, cut it into 6cm lengths, ultrasonically clean it for 25min (power 300W, frequency 40kHz), soak it in 10% dilute hydrochloric acid for 60min, rinse it with deionized water until pH=7.0, and dry it at 70℃ to constant weight for later use. S2. Preparation of metal salt mixture: According to Zn 2+ ∶Al 3+ ∶La 3+ Weigh out ZnCl2·6H2O, AlCl3·6H2O, and LaCl3·7H2O in a molar ratio of 3.2:1.3:0.7, dissolve them in deionized water, stir for 60 min (200 r / min) to obtain a mixed solution with a concentration of 0.3 mol / L, and filter for later use. S3. In-situ coprecipitation loading: Place the pretreated ACF into a three-necked flask, add the mixed solution, keep the temperature in a constant water bath at 70℃, stir for 20 min, slowly add 0.2 mol / L NaOH solution (dropping rate 2 drops / second), adjust the pH to 9.6, keep the reaction at the temperature for 10 h, stirring for 15 min every 2 h during the reaction, filter after the reaction is completed, and collect the intermediate. S4. Washing and drying: Wash the intermediate 5 times with deionized water until pH=7.0, and dry at 70℃ for 6 hours to obtain the LDH / ACF intermediate; S5. Surface modification: Prepare a 0.8 g / L dopamine-Tris buffer solution (pH=8.5), add chitosan to a concentration of 0.5 g / L, and stir for 40 min; immerse the intermediate in the modification solution, soak at room temperature for 4 h, filter, rinse twice with deionized water, and dry at 70℃ for 4 h to obtain the finished product.

[0036] Comparative Example 1: The preparation steps for Mg-Al binary LDH / ACF are as follows: S1: Pretreatment of activated carbon fiber: Using the same ACF raw material as in Example 1, cut to a length of 4cm, ultrasonically cleaned at 250W and 40kHz for 20min, soaked in 8% dilute hydrochloric acid at room temperature for 45min, rinsed with deionized water until pH=7.0, and dried at 70℃ to constant weight for later use.

[0037] S2: Preparation of Mg-Al binary metal salt mixture: according to Mg 2+ ∶Al 3+ Weigh magnesium chloride hexahydrate and aluminum chloride hexahydrate in a 3:1 molar ratio, dissolve them together in 100 mL of deionized water, stir at 180 r / min for 40 min at room temperature until the solids are completely dissolved, filter with quantitative filter paper to remove trace amounts of insoluble impurities, and prepare a 0.2 mol / L clear and transparent binary metal salt mixture.

[0038] S3: In-situ co-precipitation loading of Mg-Al-LDH: 2.0g of pretreated activated carbon fiber was placed in a three-necked flask, and the prepared binary metal mixture was added. The mixture was stirred at 65℃ for 15min to fully wet the pores of the ACF. 0.15mol / L NaOH solution was slowly added at a rate of 1.5 drops / second to precisely control the pH of the system to 9.3. The reaction was continued at a constant temperature for 8h. The mixture was stirred every 2h for 12min each time to ensure uniform loading of the powder and no local agglomeration.

[0039] S4: Water washing and drying treatment: After the reaction, the composite intermediate was collected by filtration and washed with deionized water for 12 min / time, repeated 4 times, until the pH of the filtrate stabilized at 7.0; the filter cake was placed in an oven and dried at 65℃ for 5 h. During the drying period, the sample was turned over once every 1 h to prevent local agglomeration, and the Mg-Al binary LDH / ACF intermediate was obtained.

[0040] S5: Surface hydrophilic modification: Prepare a 0.6 g / L dopamine-Tris buffer solution (pH=8.5), add chitosan to a concentration of 0.3 g / L, and stir for 35 min; place the intermediate into the modification solution, soak at room temperature for 3 h, filter, rinse twice with deionized water, and dry at 65 ℃ for 3 h to obtain the Mg-Al binary LDH / ACF control sample.

[0041] Comparative Example 2: The only difference from Example 1 is that Zn-Al binary LDH is used instead of Zn-Al-La ternary LDH. The preparation method of Zn-Al binary LDH is as follows: According to Zn 2+ ∶Al 3+ Weigh out ZnCl2·6H2O and AlCl3·6H2O at a molar ratio of 3.0:1.2, dissolve them in deionized water, stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L, and filter for later use.

[0042] Comparative Example 3: The only difference from Example 1 is that Zn-La binary LDH is used instead of Zn-Al-La ternary LDH. The preparation method of Zn-La binary LDH is as follows: According to Zn 2+ ∶La 3+ Weigh out ZnCl2·6H2O and LaCl3·7H2O in a molar ratio of 3.0:0.5, dissolve them in deionized water, stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L, and filter for later use.

[0043] Comparative Example 4: The only difference from Example 1 is that Al-La binary LDH is used instead of Zn-Al-La ternary LDH. The preparation method of Al-La binary LDH is as follows: Press Al 3+ ∶La 3+ Weigh AlCl3·6H2O and LaCl3·7H2O in a molar ratio of 1.2:0.5, dissolve them in deionized water, stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L, and filter for later use.

[0044] Comparative Example 5: The only difference from Example 1 is that only steps S1-S4 are performed, and step S5 is not performed.

[0045] Comparative Example 6: The only difference from Example 1 is that all dopamine is replaced with the same amount of chitosan.

[0046] Comparative Example 7: The only difference from Example 1 is that all chitosan is replaced with the same amount of dopamine.

[0047] Comparative Example 8: The only difference from Example 1 is that Zn in the Zn-Al-La ternary LDH is... 2+ ∶Al 3+ ∶La3+ The molar ratios are different, according to Zn 2+ ∶Al 3+ ∶La 3+ Weigh out ZnCl2·6H2O, AlCl3·6H2O, and LaCl3·7H2O in a ratio of 2.6∶1.3∶0.4, dissolve them in deionized water, and stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L. Filter the solution for later use.

[0048] Comparative Example 9: The only difference from Example 1 is that Zn in the Zn-Al-La ternary LDH is... 2+ ∶Al 3+ ∶La 3+ The molar ratios are different, according to Zn 2+ ∶Al 3+ ∶La 3+ Weigh out ZnCl2·6H2O, AlCl3·6H2O, and LaCl3·7H2O in a ratio of 3.2∶0.9∶0.3, dissolve them in deionized water, and stir for 45 min (180 r / min) to obtain a mixed solution with a concentration of 0.2 mol / L. Filter the solution for later use.

[0049] (II) Performance Testing Methods (1) Experimental environment: ambient temperature 25±1℃, relative humidity 50±5%, normal pressure; (2) Experimental water: Deionized water was used to prepare the simulated wastewater. The initial concentrations of pollutants in the simulated wastewater were as follows: Escherichia coli 1×10⁻⁶ 6 CFU / mL, bacteriophage (alternative virus) 1×10 5 PFU / mL, Pb 2+ 50mg / L, Cd 2+ 20 mg / L, microplastics (1-5 μm, polyethylene) 50 mg / L, tetracycline 50 mg / L, PFOA 100 μg / L, chloroform 0.1 mg / L, carbon tetrachloride 0.05 mg / L, COD 500 mg / L; (3) Experimental parameters: material dosage 1.0±0.05g / L, stirring speed 200r / min, adsorption reaction time 60min, and standing for 10min after the reaction; fixed bed dynamic water filtration method was adopted, and the prepared spiked simulated wastewater was passed through the filter layer (7mm thick and 2cm in diameter) made of the present invention and comparative materials at a water flow rate of 150±10mL / min. The water volume was 500mL. After the water filtration was completed, the supernatant of the filtered water was taken for testing. (4) Detection methods: The concentration and removal rate of various pollutants were determined using national standard detection methods, as follows: bacteria were determined by plate count method, viruses (bacteriophages) by double-layer plate method, heavy metal ions by atomic absorption spectrophotometry, microplastics by microscopic count method, antibiotics by high performance liquid chromatography, PFAS by liquid chromatography-mass spectrometry, VOCs by gas chromatography, and COD by potassium dichromate titration method. (5) Parallel experiments: Three parallel samples are set up for each experiment, and the average value is taken as the final test result to ensure the reliability of the experimental data.

[0050] (III) Performance Test Results

[0051]

[0052] As can be seen from the above embodiments and comparative examples, the Zn-Al-La ternary layered multimetal hydroxide composite activated carbon fiber water purification material of the present invention uses activated carbon fiber as a base, Zn-Al-La ternary LDH as the core adsorption active component, and a hydrophilic modified layer coated on the surface. The three components are compounded according to a specific mass ratio and process, and the components work synergistically to achieve the simultaneous and efficient removal of multiple pollutants.

[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nano-sized, highly charged layered electrical grid carbon fiber material, characterized in that, It includes activated carbon fiber, active component and hydrophilic modification layer. The material is prepared by using activated carbon fiber as a substrate, then adsorbing active component on the substrate to obtain an intermediate, and then coating the surface of the intermediate with hydrophilic modification layer; wherein, the active component is Zn-Al-La ternary LDH.

2. The nano-charged layered electrical grid carbon fiber material according to claim 1, characterized in that, The activated carbon fiber is made of polyacrylonitrile-based activated carbon fiber, with a diameter of 8-15 μm, a length of 2-6 cm, and a specific surface area of ​​1200-1800 m². 2 / g, with a porosity of 70%-85% and a pore size distribution of 2-50nm.

3. The nano-charged high-charge layered electrical grid carbon fiber material and its preparation method according to claim 2, characterized in that, The Zn-Al-La ternary LDH uses Zn 2+ Al 3+ La 3+ Three metal ions are arranged in a specific molar ratio to form a layered structure, and the Zn 2+ ∶Al 3+ ∶La 3+ The molar ratio of metal ions is (2.8–3.2): (1.0–1.3): (0.4–0.7). The interlayer anion of Zn-Al-La ternary LDH is Cl. - The interlayer spacing is 0.8-1.2 nm, and the surface Zeta potential is +32 to +48 mV.

4. The nano-highly charged layered electrical grid carbon fiber material and its preparation method according to claim 3, characterized in that, The active components are loaded onto activated carbon fibers via in-situ co-precipitation. The hydrophilic modified layer adopts a composite system of chitosan and dopamine, and the thickness of the hydrophilic modified layer is 30-80 nm.

5. The nano-charged high-charge layered electrical grid carbon fiber material and its preparation method according to claim 4, characterized in that, Based on a total weight percentage of 100%, it includes 50–65 wt% activated carbon fiber, 30–45 wt% active components, and 3–8 wt% hydrophilic modification layer.

6. A method for preparing a nano-sized, highly charged layered electrical grid carbon fiber material as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Pretreatment of activated carbon fiber: Pretreatment of activated carbon fiber to obtain ACF substrate; S2: Prepare a Zn-Al-La ternary metal salt mixture; S3: An LDH-loaded ACF intermediate was obtained by in-situ co-precipitation of Zn-Al-La ternary LDH on an ACF substrate; S4: The LDH-loaded ACF intermediate is washed and dried to obtain LDH-loaded ACF; S5: The LDH-loaded ACF is surface-modified with hydrophilicity to obtain nano-charged layered grid carbon fiber material.

7. The method for preparing a nano-sized, highly charged layered electrical grid carbon fiber material according to claim 6, characterized in that, The activated carbon fiber pretreatment steps in step S1 are as follows: (1) Select polyacrylonitrile-based activated carbon fiber, cut it into fiber segments of 2-6 cm in length, put it into deionized water, and ultrasonically clean it for 15-25 min; (2) Place the ultrasonically cleaned ACF into a beaker, add a 5%-10% dilute hydrochloric acid solution, and soak at room temperature for 30-60 minutes. (3) Rinse the ACF repeatedly with deionized water until the pH of the rinsing solution is 7.0±0.2, then put it in an oven and dry it at 60-70℃ until constant weight. After taking it out, put it in a desiccator for later use to obtain the pretreated ACF substrate.

8. The nano-highly charged layered electrical grid carbon fiber material and its preparation method according to claim 6, characterized in that, In step S2, the method for preparing the Zn-Al-La ternary metal salt mixture is as follows: (1) According to Zn 2+ ∶Al 3+ ∶La 3+ = (2.8~3.2) ∶ (1.0~1.3) ∶ (0.4~0.7) molar ratio, weigh out zinc chloride hexahydrate (ZnCl2·6H2O), aluminum chloride hexahydrate (AlCl3·6H2O), and lanthanum chloride heptahydrate (LaCl3·7H2O) respectively, and put them into beakers; (2) Add an appropriate amount of deionized water to the beaker, place it on a magnetic stirrer, and stir for 30-60 minutes at room temperature until the three metal salts are completely dissolved to obtain a Zn-Al-La ternary metal salt mixture with a concentration of 0.15-0.3 mol / L. (3) After stirring, filter the mixture to obtain a uniform and transparent mixture.

9. The nano-highly charged layered electrical grid carbon fiber material and its preparation method according to claim 6, characterized in that, The preparation method of step S3 is as follows: (1) Place the pretreated ACF substrate into a three-necked flask, add the prepared Zn-Al-La ternary metal salt mixture, ensure that the ACF is completely immersed in the mixture, place it on a constant temperature water bath, adjust the water bath temperature to 55-75℃, keep it warm and stir for 10-20 minutes to fully wet the ACF surface. (2) Slowly add a dilute NaOH solution with a concentration of 0.1-0.2 mol / L using a pipette, with the dropping rate controlled at 1-2 drops / second. At the same time, monitor the pH value of the mixture in real time with a pH meter and adjust the pH of the mixture to 9.0-9.

8. (3) After pH adjustment, maintain water bath temperature at 55-75℃ and continue the reaction for 6-10 h. Stir once every 1-3 h for 10-15 min each time to form Zn-Al-La ternary LDH and uniformly load it on the surface and pores of ACF. (4) After the reaction is complete, turn off the constant temperature water bath, wait for the mixture to cool to room temperature, filter by vacuum filtration, and collect the filter cake, which is the LDH-supported ACF intermediate. The specific method for step S4 is as follows: (1) Place the LDH-loaded ACF intermediate obtained by vacuum filtration into a beaker, add deionized water, stir and wash for 10-15 min, then vacuum filter, repeat the water washing-vacuum filtration operation 3-5 times until the pH of the rinsing solution is 7.0±0.

2. (2) Place the washed intermediate into an oven and dry it at 60-70℃ for 4-6 hours. Turn it over every 0.5-2 hours during the drying process to obtain the Zn-Al-La ternary LDH / ACF composite intermediate, and place it in a desiccator for later use. The specific method for step S5 is as follows: (1) Preparation of chitosan-dopamine composite modified solution: Weigh dopamine and dissolve it in Tris-HCl buffer solution, stir for 20-30 min to obtain a dopamine solution with a concentration of 0.4-0.8 g / L; then add chitosan to the dopamine solution, continue stirring for 30-40 min to completely dissolve the chitosan, adjust the chitosan concentration to 0.2-0.5 g / L to obtain the chitosan-dopamine composite modified solution; (2) The intermediate of Zn-Al-La ternary LDH / ACF composite material was placed in the composite modification solution and soaked at room temperature for 2-4 h, with stirring every 20-40 min during the process; (3) After soaking, vacuum filter, rinse the filter cake with deionized water 2-3 times, and then put it in an oven and dry it at 60-70℃ for 2-4 hours to obtain the finished product of Zn-Al-La ternary layered bimetallic hydroxide composite activated carbon fiber water purification material.

10. A nano-charged layered grid carbon fiber material as described in any one of claims 1-6 and the material prepared by the preparation method described in any one of claims 7-9, for the simultaneous removal of bacteria, viruses, heavy metal ions, microplastics, antibiotics, perfluorinated and polyfluoroalkyl substances, volatile organic compounds and chemical oxygen demand from water bodies, suitable for drinking water purification, industrial wastewater treatment and groundwater remediation scenarios.

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