Preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles

Abstract

The application discloses a preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles, and belongs to the technical field of environment-friendly adsorption materials. The carboxymethyl cellulose composite fiber is prepared by using a green and environment-friendly alkali-urea aqueous solvent system, and the La-UiO66-NH2 nanoparticles are introduced into the composite fiber by an in-situ synthesis method to perform functional modification, so that the composite fiber material loaded with the La-UiO66-NH2 nanoparticles is finally obtained. The problems that the nanoparticles are prone to aggregation in water bodies due to small size, recycling and recycling utilization are difficult to realize, and the existing phosphorus removal materials do not have the ability of processing and forming, so that practical application is difficult to achieve are effectively solved.

Description

Technical Field

[0001] This invention relates to a preparation process of carboxymethyl cellulose composite fiber, specifically a preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles for phosphorus removal, belonging to the technical field of environmentally friendly adsorption materials. Background Technology

[0002] Water resource management is one of the most challenging issues at both local and global levels. Phosphorus is a fundamental element for all life forms, but its overuse and release into the environment can lead to serious consequences. With the increasing incidence of eutrophication, phosphorus is considered key to solving the problem of eutrophication, namely, the urgent need to address the contradiction between phosphorus pollution in the environment and the growing demand for phosphorus.

[0003] Currently, most phosphorus removal methods utilize functional nanomaterial adsorbents with specific surface properties to capture, remove, and recover phosphorus from water. These materials mainly include carbon materials, zeolites, mesoporous silica, metal-organic frameworks (e.g., CN109806844A), metal oxides and hydroxides, biomass-derived materials, and phosphorus-binding acceptor dopants. While these materials exhibit good phosphorus adsorption effects, their powdered form and lack of processing capabilities, coupled with the absence of suitable supports, make them unsuitable for practical applications (e.g., CN111203190A). Therefore, developing a highly efficient phosphorus removal material that can overcome processing limitations is urgently needed and is of great significance for solving phosphorus pollution problems. Furthermore, due to their small size, nanoparticles tend to aggregate in water, making recycling difficult and potentially leading to secondary water pollution. Summary of the Invention

[0004] To address the problems in existing technologies where nanoparticles, due to their small size, easily aggregate in water, making recycling difficult, and where existing phosphorus removal materials lack the ability to be processed and shaped, thus hindering practical applications, this invention proposes a preparation process for carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles.

[0005] To achieve the above technical objectives, the following technical solution is proposed:

[0006] A process for preparing carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles includes the following steps:

[0007] A: Wood pulp raw material with a degree of polymerization of 400-600 is added to an alkali / urea solvent and stirred to form a pulp porridge. Then, it is stirred at -12 to -15°C to obtain a wood cellulose solution. The alkali / urea solvent consists of 7-8 wt% NaOH, 11-15 wt% urea, and 0.5-1 wt% ZnO. The stirring time is controlled at 10-20 min, the stirring speed at 400-800 rpm, and the concentration of wood cellulose in the solution is 4.0-6.0 wt%. This concentration is determined by the degree of polymerization of the wood pulp raw material. Controlling this concentration ensures that the solution has good fluidity and stability, thereby ensuring the smooth progress of subsequent processes. At the same time, it ensures that the composite fibers prepared later have high strength, so that they can be better applied to phosphorus removal.

[0008] The selection of wood pulp with a degree of polymerization of 400–600 as raw material ensures its solubility in alkali / urea solvents, resulting in high solubility and good stability of the solution. This choice of raw material also guarantees the mechanical properties of the subsequent composite fiber products. If the raw material has too high a degree of polymerization, its solubility in alkali / urea solvents will be poor, leading to poor stability of the solution; conversely, if the raw material has too low a degree of polymerization, the final composite fiber product will have poor mechanical properties. Therefore, to ensure the stability and sustainability of the preparation process, and to guarantee the performance of the subsequent composite fiber products, wood pulp with a degree of polymerization of 400–600 is selected as the raw material.

[0009] Dissolving wood pulp raw materials by stirring at -12 to -15°C effectively dissolves the cellulose within the pulp. The dissolution mechanism involves the formation of hydrates from alkali (such as NaOH), urea, and water at low temperatures. These hydrates disrupt the hydrogen bonds between the cellulose molecules within the pulp, thus dissolving the cellulose. If the dissolution temperature is too high, dissolution fails; if the temperature is too low, the entire solution system freezes, losing its fluidity. Furthermore, lower temperatures result in higher energy consumption. Similarly, the settings of "stirring time 10-20 min, stirring speed 400-800 rpm" ensure that the wood pulp raw materials can be fully dissolved. If the time is too short, the dissolution will be insufficient, affecting subsequent spinning and other processes; if the time is too long, it will increase the cycle of the entire production process and will not help with dissolution. Within 10-20 min, the cellulose can be completely dissolved without the need to increase the time. On the other hand, if the stirring speed is too low, it will easily cause uneven stirring and prolong the stirring time, increasing the cycle of the production process; if the stirring speed is too high, it will cause the solution to splash, which is not conducive to dissolution.

[0010] In addition, the alkali / urea solvent composition includes: NaOH 7-8wt%, urea 11-15wt% and ZnO 0.5-1wt%. This is to control the cost of additives while also ensuring the solubility of cellulose in the raw wood pulp with a degree of polymerization of 400-600.

[0011] B: Add carboxymethyl cellulose powder to the wood cellulose solution and stir evenly to obtain a wood cellulose-carboxymethyl cellulose spinning solution; wherein, the following controls are applied: the amount of carboxymethyl cellulose powder added is 0.1-10% of the mass of wood cellulose, the stirring temperature is 0-20℃, the stirring time is 10-30 min, and the stirring speed is 400-800 rpm.

[0012] Carboxymethyl cellulose (CMC), being a water-soluble polymer, enhances the hydrophilicity of wood cellulose fibers when added to the solution, which is beneficial for the subsequent preparation of nanoparticle composite fibers. However, excessive CMC addition reduces the mechanical properties of the fibers; conversely, insufficient addition results in minimal hydrophilicity. Therefore, the amount of CMC powder added should be controlled to 0.1–10% of the mass of wood cellulose.

[0013] In addition, "stirring temperature 0~20℃, stirring time 10~30 min, stirring speed 400~800rpm" improves the efficiency and quality of the process while ensuring that carboxymethyl cellulose powder and wood cellulose solution are fully and evenly mixed, and also effectively reduces energy consumption.

[0014] C: Using a wet spinning method, the obtained filaments are wound, washed, dried and formed into tubes to obtain carboxymethyl cellulose composite fibers with a single filament linear density of 128-138 dtex;

[0015] For this carboxymethyl cellulose composite fiber, the introduction of carboxymethyl cellulose is beneficial for the subsequent in-situ generation of nanoparticles, mainly because the carboxyl groups on carboxymethyl cellulose play a key role. However, carboxymethyl cellulose is a water-soluble substance, and it is difficult to directly prepare composite materials with nanoparticles. Therefore, this technical solution uses cellulose fiber as a carrier, introduces carboxymethyl cellulose which can promote the synthesis of nanoparticles, and prepares carboxymethyl cellulose composite fiber. Then, in-situ synthesis is carried out on the surface of the composite fiber to load nanoparticles.

[0016] D: Dissolve equimolar amounts of NH2-BDC (2-amino-1,4-phthalic acid) and ZrCl4 (zirconium chloride) in 20–50 mL of DMF (N,N-dimethylformamide) to obtain a ZrCl4 / NH2-BDC precursor solution; add LaCl3·7H2O (lanthanum chloride heptahydrate) to the ZrCl4 / NH2-BDC precursor solution and place it in an ultrasonic oscillator for 20–40 min to ensure complete dissolution, to obtain a mixture of La-UiO66-NH2 nanoparticles; wherein, the amounts of NH2-BDC, ZrCl4, and LaCl3·7H2O added are controlled to be 1–3 mmol, 1–3 mmol, and 0.25–3 mmol.

[0017] The chemical reaction involved includes: 6ZrOCl2 + 6C8H6O4 + 12H2O → C 48 H 28 O 32 Zr6+ 12HCl+ 10H2O. Controlling the addition of NH2-BDC to 1-3 mmol, ZrCl4 to 1-3 mmol, and LaCl3·7H2O to 0.25-3 mmol can effectively ensure the yield of the target product and reduce costs.

[0018] E: Pass the mixture of La-UiO66-NH2 nanoparticles into a high-pressure autoclave lined with polytetrafluoroethylene, add the carboxymethyl cellulose composite fiber obtained in step C, and treat at 80-120℃ for 12-24 h to obtain a precipitate (specifically, La-UiO66-NH2 nanoparticles attached to carboxymethyl cellulose).

[0019] The amount of carboxymethyl cellulose composite fiber added is controlled to be 0.3-0.5g, and the mass ratio of carboxymethyl cellulose to La-UiO66-NH2 nanoparticles is 1:0.03-0.05 to ensure the loading amount between carboxymethyl cellulose and La-UiO66-NH2 nanoparticles.

[0020] The lining of the autoclave is made of polytetrafluoroethylene (PTFE), which has stable and excellent heat and cold resistance. It can be used for a long time at temperatures ranging from -180 to 260°C. It will not become brittle in liquid air or soften in boiling water. It is also resistant to corrosion, acids, alkalis, and various organic solvents. This ensures the loading effect between the mixture of La-UiO66-NH2 nanoparticles and carboxymethyl cellulose composite fibers.

[0021] The condition of "treatment at 80-120℃ for 12-24 h" effectively ensures the loading rate of La-UiO66-NH2 nanoparticles on carboxymethyl cellulose composite fibers.

[0022] F: The precipitate was washed with DMF (N,N-dimethylformamide) to remove unreacted excess organic linkages, yielding a solid; then, the solid was soaked in methanol for 24 h to remove truncated DMF molecules.

[0023] The organic linker specifically refers to NH2-BDC (2-amino-1,4-phthalic acid), and the solid specifically refers to carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles.

[0024] The precipitate was washed with DMF (N,N-dimethylformamide) to remove excess NH2-BDC (2-amino-1,4-phthalic acid) and Zr. 4+ Due to NH2-BDC and Zr 4+ It is easily soluble in solvents, thus ensuring good rinsing efficiency and quality;

[0025] Methanol was used for soaking; here, pure methanol was used, and the methanol needed to completely submerge the carboxymethyl cellulose composite fibers. Its purpose was to remove DMF molecules captured by the La-UiO66-NH2 nanoparticles. Furthermore, methanol was chosen as the soaking solution because it can dissolve DMF, facilitating its removal, and because the molecules are small, they are easily dried and removed through the pores of the nanoparticles. Other soaking solvents were less effective and more expensive.

[0026] G: The product is dried under vacuum or electric heating at 45-60℃ for 12-24 hours to obtain carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles.

[0027] The instruction to "dry the composite fiber material under vacuum or electric heating air at 45-60℃ for 12-24 hours" can both dry the composite fiber material and ensure its stability. That is, if the temperature is too low, the drying effect cannot be achieved; if the temperature is too high, the structure of the composite fiber material will be damaged.

[0028] The beneficial technical effects of adopting this technical solution are as follows:

[0029] I. Existing phosphorus removal materials are generally pure MOFs materials, which are powdered crystals. They are prone to agglomeration and sedimentation during application, affecting their adsorption efficiency and making separation difficult during application. In contrast, this application uses cellulose as a carboxymethyl carrier, that is, a combination of "wood cellulose + carboxymethyl cellulose + La-UiO66-NH2 nanoparticles", which ensures that phosphorus adsorption will not agglomerate. After adsorption, it can be easily removed and processed for recycling.

[0030] Specifically, this invention involves the preparation of carboxymethyl cellulose composite fibers using a green and environmentally friendly alkali-urea aqueous solvent system. Based on these composite fibers, La-UiO66-NH2 nanoparticles are introduced through in-situ synthesis for functional modification, ultimately yielding a composite fiber material loaded with La-UiO66-NH2 nanoparticles. This proposed composite fiber material effectively solves the problems in existing technologies where nanoparticles, due to their small size, easily aggregate in water, making recycling difficult, and existing phosphorus removal materials lack the ability to be processed and shaped, thus hindering practical applications. Meanwhile, this preparation process not only enhances the utilization value of cellulose fibers, namely, the composite fiber material can effectively adsorb phosphorus in water; but also involves mild process conditions, simple operation, strong stability, and is suitable for industrial-scale production. Compared with existing technologies (such as: "Preparation and phosphorus removal performance of sodium carboxymethyl cellulose / chitosan composite material, Liu Tao, Changchun University of Technology, 2021", "Preparation and adsorption performance of lanthanum-containing compound modified phosphorus adsorbent, Liao Taiwan, Jinan University, 2019", etc.), it has greater industrial application value.

[0031] II. In this invention, the resulting carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles exhibits superior processability, adsorption capacity, reusability, and cost compared to existing composite materials (such as CN109806844A, CN111203190A, and CN110449120A). Furthermore, the composite fiber material of this invention demonstrates high efficiency in removing phosphates from water at room temperature and pressure, achieving the goals of high-efficiency adsorption, economy, processability, and strong plasticity. Testing of the phosphate removal efficiency of this composite fiber material shows that at room temperature (25 ℃) and atmospheric pressure, with an initial phosphate concentration of 6 mg / L, the composite fiber material achieves a 75% phosphate removal rate in water. Attached Figure Description

[0032] Figure 1 This is a schematic diagram illustrating the principle of loading La-UiO66-NH2 nanoparticles onto carboxymethyl cellulose composite fibers in this invention.

[0033] Figure 2 This is a photograph of the wood pulp raw material (degree of polymerization of 400) used in this invention.

[0034] Figure 3 This is a photograph of the carboxymethyl cellulose powder used in this invention.

[0035] Figure 4 This is a physical image of the mixture of La-UiO66-NH2 nanoparticles used in this invention.

[0036] Figure 5 This is a photograph of the initial product of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles in this invention (without post-treatment such as rinsing, soaking and drying).

[0037] Figure 6 This is a photograph of the carboxymethyl cellulose composite fiber product loaded with La-UiO66-NH2 nanoparticles in this invention (after rinsing, soaking and drying).

[0038] Figure 7 The X-ray diffraction patterns are those of the composite fibers prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0039] Figure 8 These are SEM images of the composite fibers obtained in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0040] Figure 9 This is a comparison chart showing the phosphate removal rates in water by the composite fibers obtained in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0041] Figure 10 The image shows a physical photograph of a failed sample involved in this invention.

[0042] Figure 11 The images shown are of the failed samples involved in this invention (where A is a UIO-66 metal-organic framework material sample in the prior art, B is a composite fiber sample corresponding to La-UiO66-NH2 nanoparticles prepared with a La to Zr molar ratio of 0.25:1, C is a composite fiber sample corresponding to La-UiO66-NH2 nanoparticles prepared with a La to Zr molar ratio of 0.5:1, D is a composite fiber sample corresponding to La-UiO66-NH2 nanoparticles prepared with a La to Zr molar ratio of 0.75:1, and E is a composite fiber sample corresponding to La-UiO66-NH2 nanoparticles prepared with a La to Zr molar ratio of 1:1). Detailed Implementation

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] This embodiment provides a process for preparing carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles, including the following steps:

[0046] I. Preparation of Carboxymethyl Cellulose Composite Fibers

[0047] (1) Wood pulp raw material with a degree of polymerization of 400 was added to an alkali / urea solvent and stirred to form a pulp porridge. Then, the pulp porridge was placed at -12℃ and stirred to obtain a wood cellulose solution with a wood cellulose concentration of 6.0 wt%.

[0048] The alkali / urea solvent includes: 7 wt% NaOH, 12 wt% urea and 0.5 wt% ZnO, with a stirring time of 20 min and a stirring speed of 600 rpm;

[0049] (2) Add carboxymethyl cellulose powder to the wood cellulose solution obtained above, stir evenly to obtain a wood cellulose-carboxymethyl cellulose mixed solution, which is used as the spinning solution;

[0050] The amount of carboxymethyl cellulose powder added was 5% of the mass of wood cellulose, the stirring temperature was 5℃, the stirring time was 20 min, and the stirring speed was 500 rpm.

[0051] (3) Using wet spinning process, the spun filaments are wound, washed, dried and formed into tubes to obtain carboxymethyl cellulose composite fiber. The linear density of the single filament of the carboxymethyl cellulose composite fiber is 133 dtex, which is ready for use.

[0052] II. Preparation of La-UiO66-NH2 nanoparticles

[0053] Equimolar amounts of NH2-BDC and ZrCl4 were dissolved in 30 mL of DMF. LaCl3·7H2O was added to the precursor ZrCl4 / NH2-BDC solution according to a La:Zr molar ratio of 0.25:1. The mixture was then placed in an ultrasonic oscillator and shaken for 30 min to ensure complete dissolution, resulting in a mixed solution containing La-UiO66-NH2 nanoparticles for later use.

[0054] III. Preparation of Carboxymethyl Cellulose Composite Fibers Loaded with La-UiO66-NH2 Nanoparticles

[0055] (1) Pass the mixture into a high-pressure autoclave lined with polytetrafluoroethylene, and at the same time add 0.4g of carboxymethyl cellulose composite fiber, and treat at 120℃ for 24h to obtain precipitate;

[0056] (2) The precipitate was washed with DMF to remove unreacted excess organic linkages, and a solid was obtained. Then, the solid was soaked in methanol for 24 h to remove the retained DMF molecules.

[0057] (3) The soaked product was vacuum dried at 60°C for 12 hours to obtain carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles.

[0058] Example 2

[0059] Based on Example 1, the difference between this example and Example 1 is that the molar ratio of La to Zr is 0.5:1, while the rest is the same as in Example 1.

[0060] Example 3

[0061] Based on Example 1, the difference between this example and Example 1 is that the molar ratio of La to Zr is 0.75:1, while the rest is the same as in Example 1.

[0062] Example 4

[0063] Based on Example 1, the difference between this example and Example 1 is that the molar ratio of La to Zr is 1:1, while the rest is the same as in Example 1.

[0064] Comparative Example 1

[0065] Based on Example 1, this comparative example is unloaded La-UiO66-NH2 nanoparticles, otherwise the same as in Example 1.

[0066] Comparative Example 2

[0067] Based on Example 1, this comparative example is as follows: LaCl3·7H2O was not added to the ZrCl4 / NH2-BDC precursor solution, and everything else was the same as in Example 1.

[0068] Based on Examples 1-4 and Comparative Examples 1-2, the influencing factors in the preparation process (including: type of additives, purity of additives, amount of additives added, processing temperature, processing time, etc.) are discussed, specifically including:

[0069] I. The composite fibers obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to X-ray diffraction analysis, and the results are shown in the figure. Figure 7 .from Figure 7 As can be seen from the data: 1) The composite fiber samples in Examples 1-4 show diffraction peaks of La-UiO66-NH2, indicating that La-UiO66-NH2 nanoparticles were successfully synthesized on the surface of the composite fibers in Examples 1-4; 2) The same diffraction peaks as in Examples 1-4 appeared in Comparative Example 2, indicating that La doping did not completely change the crystal growth of the UiO unit; 3) No diffraction peaks of nanoparticles appeared in the composite fiber in Comparative Example 1, indicating that no nanoparticles were generated on the surface of the composite fiber.

[0070] II. The composite fibers obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to scanning electron microscopy for examination. The results are shown in the figure. Figure 8 .from Figure 8 It can be seen that: 1) The composite fiber samples in Examples 1-4 and Comparative Example 2 have a large number of nanoparticles attached to their surfaces, while no nanoparticles appear on the surface of the composite fiber in Comparative Example 1. This indicates that La-UiO66-NH2 nanoparticles were successfully synthesized on the surface of the composite fiber in Examples 1-4, while UiO66-NH2 nanoparticles were synthesized on the surface of the composite fiber in Comparative Example 2.

[0071] III. The composite fibers obtained in Examples 1-4 and Comparative Examples 1-2 were subjected to phosphate adsorption performance tests. Specifically, 150 mg of the La-UiO66-NH2-loaded composite fibers and carboxymethyl cellulose prepared in Examples 1-4 and Comparative Examples 1-2 were added to a phosphate solution (concentration 6 mg / L), shaken thoroughly, and allowed to undergo an adsorption reaction. Samples were taken at 2 min, 3 min, 5 min, 10 min, 20 min, 30 min, 45 min, 60 min, 90 min, 120 min, and 180 min to measure the concentration of the phosphate solution. The results were as follows: Figure 9 As shown. From Figure 9 It can be seen that when the molar ratio of La:Zr is 0.25∶1, the best adsorption effect is achieved, with an adsorption rate of up to 75%; and the adsorption performance is improved compared to the composite material without La.

[0072] Furthermore, in the discussion of the influencing factors in this preparation process, failed samples (such as...) are involved. Figure 10 The sample shown was dark brown (phosphorus removal rate 37%), preliminarily inferred to be due to the purity of the additives and uneven heating during subsequent drying. Additionally, for some failed samples (…),… Figure 11 The color is an uneven dark brown, which is preliminarily inferred to be caused by the purity of the additives and uneven heating during subsequent drying.

[0073] Comparative Example 3

[0074] Based on Example 1, this comparative example further discusses and optimizes the influencing factors in the preparation process (the ratio of La-UiO66-NH2 nanoparticles, soaking conditions, and drying conditions, etc.), specifically including:

[0075] 1) The sizing ratio within La-UiO66-NH2 nanoparticles: Under different sizing ratios, according to... Figure 8The SEM images show that when the La:Zr molar ratio is 0.25:1, the synthesized nanoparticles almost completely cover the cellulose surface; when the La:Zr molar ratio is 0.5:1, the number of synthesized nanoparticles is somewhat reduced compared to the former; when the La:Zr molar ratio is 0.75:1, the synthesis efficiency of nanoparticles decreases sharply; and when the La:Zr molar ratio is 1:1, the number of synthesized nanoparticles is even smaller. Therefore, it can be concluded that excessive addition of La reduces the synthesis efficiency of nanoparticles. Thus, a La:Zr molar ratio of 0.25:1 yields the best synthesis results.

[0076] 2) Immersion conditions: Immersion in methanol can remove DMF molecules captured by La-UiO66-NH2 nanoparticles. Methanol is chosen as the solvent because it is economical, facilitates methanol removal, and does not introduce impurities. Using ethanol would increase costs; using water would hinder subsequent drying steps, preventing the composite fiber material from drying sufficiently. Therefore, methanol is selected as the immersion solution.

[0077] 3) Drying conditions: Vacuum or electric heating drying at 45–60℃ for 12–24 hours. Drying below 20℃ will not achieve the desired effect, and substances such as methanol and DMF carried by the composite fiber material will not fully volatilize, affecting the quality of subsequent products. Temperatures above 80℃ will damage the structure of the composite fiber material. Therefore, a drying temperature of 45–60℃ is selected to ensure thorough drying of the sample without damaging the material structure and to effectively reduce energy consumption.

[0078] Furthermore, influencing factors are not limited to the ratio, soaking conditions, and drying conditions, and will not be discussed in detail here.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles, characterized in that, Includes the following steps: S1: Add wood pulp raw material with a degree of polymerization of 400-600 to an alkali / urea solvent, stir, dissolve, and control the concentration of wood cellulose to obtain a wood cellulose solution with a concentration of 4.0-6.0 wt%. S2: Add carboxymethyl cellulose powder to a wood cellulose solution and stir to obtain a wood cellulose-carboxymethyl cellulose spinning solution; wherein, the amount of carboxymethyl cellulose powder added is controlled to be 0.1-10% of the mass of wood cellulose; S3: Wet spinning is used to obtain filaments; then, the filaments are wound, washed, dried and formed into tubes to obtain carboxymethyl cellulose composite fibers with a monofilament linear density of 128-138 dtex, for later use; S4: Dissolve equimolar amounts of NH2-BDC and ZrCl4 in DMF to obtain a ZrCl4 / NH2-BDC precursor solution; add LaCl3·7H2O to the ZrCl4 / NH2-BDC precursor solution and dissolve to obtain a mixture of La-UiO66-NH2 nanoparticles for later use; wherein, the molar ratio between LaCl3·7H2O and ZrCl4 is controlled to be 0.25 to 1:1; S5: Pass the mixture of La-UiO66-NH2 nanoparticles into a high-pressure autoclave lined with polytetrafluoroethylene, add the carboxymethyl cellulose composite fiber obtained in step S3, and treat at 80-120℃ for 12-24 h to obtain a precipitate; wherein, the mass ratio of carboxymethyl cellulose to La-UiO66-NH2 nanoparticles is controlled to be 1:0.03-0.05; S6: The precipitate obtained in step S5 is washed, soaked and dried to obtain carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles.

2. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, The composition of the alkali / urea solvent includes: 7-8 wt% NaOH, 11-15 wt% urea, and 0.5-1 wt% ZnO.

3. The preparation process of carboxymethyl cellulose composite fibers loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In step S1, the following parameters are controlled: stirring temperature -12 to -15℃, stirring time 10 to 20 min, and stirring speed 400 to 800 rpm.

4. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In step S2, the stirring temperature is controlled as follows: 0-20℃, stirring time is 10-30 min, and stirring speed is 400-800 rpm.

5. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In step S4, after adding LaCl3·7H2O, the mixture is ultrasonically vibrated for 20–40 min.

6. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In step S4, the following amounts are controlled: NH2-BDC is added at 1–3 mmol, ZrCl4 is added at 1–3 mmol, and LaCl3·7H2O is added at 0.25–3 mmol.

7. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In the rinsing step of step S6, the precipitate is rinsed with DMF; in the soaking step of step S6, the precipitate is soaked in methanol for 24 hours.

8. The preparation process of carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles according to claim 1, characterized in that, In the drying process of step S6, the drying is carried out at 45-60°C for 12-24 hours.

9. A carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles, characterized in that, It is prepared by the preparation process described in any one of claims 1-8.

10. The carboxymethyl cellulose composite fiber loaded with La-UiO66-NH2 nanoparticles, prepared by the preparation process described in any one of claims 1-8, is used for phosphorus removal.

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