A nano-copper / carrot cellulose porous composite material and a preparation method thereof

Abstract

This invention discloses a nano-copper / radish cellulose porous composite material and its preparation method, belonging to the field of biomass functional materials technology. Using radish residue as raw material, high-purity radish cellulose powder is prepared through drying, pulverizing, acid cooking, alkali cooking, oxidative bleaching, and ammonia treatment. The cellulose powder is dissolved in an ionic liquid to form a homogeneous solution, and chemical cross-linking is achieved using hexamethylene diisocyanate as a cross-linking agent. After displacement, impurity removal, and freeze-drying, a cross-linked cellulose porous material is obtained. A nano-copper precursor solution is prepared using a copper ammonia solution and a reducing agent. The cross-linked porous material is immersed in the precursor solution to achieve in-situ loading of nano-copper, resulting in the target porous composite material. This invention significantly improves the mechanical properties and structural stability of the material, achieves uniform loading of nano-copper, endows the material with highly efficient catalytic performance, the preparation process is green and controllable, the ionic liquid is recyclable, and the obtained material possesses both environmental friendliness and catalytic activity, making it suitable for scenarios such as organic dye wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of biomass functional materials technology, specifically to a nano-copper / carnation cellulose porous composite material and its preparation method. Background Technology

[0002] With the rapid development of the dyeing and printing industry, organic dye wastewater has become one of the major pollutants in the aquatic environment. Its high color, high toxicity, and recalcitrant degradation characteristics pose a serious threat to the ecological environment and human health. Traditional treatment methods such as adsorption, flocculation, and biodegradation suffer from low efficiency, long cycles, and the potential for secondary pollution. Catalytic reduction technology using sodium borohydride as a reducing agent has attracted widespread attention due to its mild reaction conditions and high degradation efficiency. Cellulose, as an abundant and environmentally friendly biomass material, possesses a natural porous structure and abundant hydroxyl active sites, making it an ideal raw material for preparing catalyst supports. However, the presence of numerous hydrogen bonds between natural cellulose molecules results in poor solubility and difficulty in molding, leading to insufficient mechanical properties and structural stability in the prepared porous materials, thus limiting its application in the catalytic field.

[0003] Cellulose molecules are highly polar with extremely strong intermolecular forces. The six-membered pyran ring structure in the molecular chain makes internal rotation difficult. The three hydroxyl groups on each pyran ring further form a strong intermolecular and intramolecular hydrogen bond network, which prevents the glycosidic bonds from rotating freely. This results in poor flexibility and high rigidity of cellulose molecular chains, ultimately causing defects such as poor toughness and easy shedding of porous cellulose materials. To address this issue, researchers have conducted extensive modification studies: H. Sehaqui et al., in a 2010 study published in *Soft Matter*, utilized the interaction forces between cellulose and xylo-glucan molecules to improve the mechanical properties of the material; L. Zhou et al., in a 2019 study published in *ACS Sustainable Chemistry & Engineering*, introduced polycaprolactone (PCL) chains between cellulose molecules to enhance the toughness of the material; N. Pircher et al., in a 2014 study published in *Carbohydrate Polymers*, incorporated secondary polymers such as PCL, polylactic acid (PLA), cellulose acetate (CA), and polymethyl methacrylate (PMMA) into the fiber matrix to prepare porous cellulose materials with certain strength and toughness. However, these existing modification methods all have obvious limitations: cellulose and xylo-glucan are only bound by weak interactions, resulting in limited mechanical reinforcement and difficult process control; although PCL modification can improve toughness, its hydrophobicity and crystalline structure hinder water penetration, disrupt pore connectivity, inhibit material hydrolysis and biodegradation, and significantly prolong the degradation cycle; although incorporating secondary polymers can improve toughness to some extent, the lack of chemical bonding, insufficient interfacial compatibility, and weak intermolecular forces limit the improvement in toughness and leads to a prolonged overall degradation cycle of the material. Some recalcitrant components may also weaken the environmental friendliness of the material and cause potential ecological risks.

[0004] Chinese Patent Publication No. CN107715911A discloses a cellulose-supported copper nanoparticle (I) porous material, its preparation method, and its application. This patent uses cellulose as a carrier and loads copper nanoparticles via an in-situ reduction method. The prepared material exhibits a certain catalytic degradation effect on some organic pollutants. However, this patent still has the following technical defects: First, the cellulose used is not sufficiently cross-linked, resulting in poor mechanical properties and structural stability of the material. It is prone to breakage and flaking during use, leading to the loss of copper nanoparticles. Second, the uniformity of the copper nanoparticle loading is difficult to control, easily leading to agglomeration and reducing the exposure rate of catalytic active sites. Third, the preparation process does not employ a homogeneous dissolution system, resulting in uneven dispersion of cellulose molecules and uneven distribution of the material's pore structure. This affects the penetration and diffusion efficiency of the reaction solution, making it difficult to achieve the ideal overall catalytic performance. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this application discloses a nano-copper / carrot cellulose porous composite material and its preparation method; the preparation method of the nano-copper / carrot cellulose porous composite material includes the following steps:

[0006] S1. Preparation of radish cellulose powder: The radish residue is dried and pulverized, and then subjected to acid boiling, alkali boiling, oxidative bleaching, and ammonia treatment in sequence. After filtration and washing until neutral, the radish cellulose powder is obtained by freeze drying.

[0007] S2. Preparation of cross-linked cellulose porous material: Radish cellulose powder was dissolved in ionic liquid 1-ethyl-3-methylimidazolium chloride EMIMCl at 95℃ to form a homogeneous solution. Hexamethylene diisocyanate HDI was added as a cross-linking agent to carry out the cross-linking reaction. After replacement with deionized water, removal of chloride ions, and freeze drying, cross-linked cellulose porous material was obtained.

[0008] S3. Loading nano-copper: Prepare a copper ammonia solution, add a reducing agent to obtain a nano-copper precursor solution, immerse the cross-linked cellulose porous material in the precursor solution to load nano-copper, wash and freeze-dry to obtain a nano-copper / carrot cellulose porous composite material.

[0009] Preferably, step S1 specifically involves: pulverizing the radish residue into powder, and adding 40 g to 60 g of the powder to a solution with a mass fraction of 1.0 wt% to 1.5 wt%. Boil in aqueous solution for 1-3 hours, filter, and wash several times with deionized water; take the filter cake and add it to a 10.0wt%-15.0wt% KOH aqueous solution, boil for 3-5 hours, filter and wash until the filtrate is colorless; then add the filter residue to a solution containing 3.0wt%-5.0wt% NaOH and 4.0wt%-6.0wt% KOH. 0.01wt%~0.03wt% Boil in an aqueous solution of 1.0wt%–3.0wt% EDTA-2Na for 1–3 hours, filter and wash; finally, place the filter residue in an aqueous solution of 25wt%–30wt% EDTA-2Na. With 35wt%~40wt% Boil the mixture in the solution until it turns white, filter and wash until the filtrate is neutral, and freeze-dry to obtain radish cellulose powder.

[0010] Preferably, in S2, the mass ratio of radish cellulose to EMIMCl is 1:80 to 1:120; after the mixed system is evacuated and purged with nitrogen 2 to 4 times, it is stirred at a constant temperature in an oil bath at 90℃ to 100℃ until it is completely dissolved into a homogeneous solution; the molar ratio of HDI to radish cellulose is 2:1 to 4:1, and the crosslinking reaction time is 0.5 h to 1.5 h.

[0011] Preferably, in step S2, the solution after the cross-linking reaction is poured into a cylindrical mold and defoamed under vacuum at 70℃~90℃ for 20 h~28 h; the ionic liquid is replaced with deionized water, with the water being changed every 12 h~36 h at a concentration of 0.005 mol / L~0.015 mol / L. The solution was tested until no chloride ions were detected, and a cross-linked cellulose hydrogel was obtained.

[0012] Preferably, in step S2, the freeze-drying conditions are -60℃ to -50℃, vacuum degree is 0.5 Pa to 1.5 Pa, and drying time is 20 h to 28 h, to obtain a cylindrical cross-linked cellulose porous material; the ionic liquid EMIMCl is recovered by rotary evaporation.

[0013] Preferably, step S3 specifically involves: stirring the mixture under magnetic force. Dissolve in deionized water, add concentrated ammonia dropwise until a deep blue copper ammonia solution is formed; add vitamin C to obtain a yellow nano-copper precursor solution; immerse the cross-linked cellulose porous material in the precursor solution, remove it, wash it with deionized water, and freeze-dry it to obtain the target material.

[0014] Preferred, The dosage is 10 g to 13 g, the amount of deionized water is 200 mL to 280 mL, the amount of vitamin C is 7 g to 9 g, and the soaking load time is 3 h to 5 h.

[0015] A nano-copper / carrot cellulose porous composite material is provided, which uses cross-linked cellulose as a porous matrix with a three-dimensional cross-linked network pore structure inside the matrix; the cellulose matrix is ​​obtained by chemically cross-linking hexamethylene diisocyanate (HDI) with the hydroxyl groups on the cellulose molecules to form urethane bonds; and nano-copper particles are uniformly loaded on the surface and in the pores of the porous matrix.

[0016] Compared with the prior art, the technical solution of this application has the following technical effects:

[0017] This invention utilizes cellulose extracted from radish residue and performs multi-stage purification, which fully leverages agricultural processing byproducts to achieve efficient conversion and recycling of biomass resources. This avoids resource waste and environmental burden caused by raw material disposal, enhances the added value and sustainability of biomass resource utilization, provides a stable and feasible path for the high-value utilization of agricultural processing waste, and ensures that the raw materials maintain good molecular structure and reactivity under mild treatment conditions, laying a high-quality foundation for the subsequent preparation of porous materials.

[0018] This invention employs a homogeneous dissolution method using ionic liquids combined with chemical bonding modification using crosslinking agents. This method can construct a stable three-dimensional crosslinked network structure between cellulose molecules, significantly improving the structural integrity and morphological stability of the porous matrix. This makes the material less prone to breakage and flaking during molding and use, maintaining good overall morphology and mechanical properties. At the same time, it allows the matrix to form a uniform and well-connected pore structure, providing sufficient and suitable attachment sites for nano-copper loads, ensuring the uniformity and stability of the material structure.

[0019] This invention loads nano-copper particles in situ onto a cross-linked cellulose porous matrix, enabling the nano-copper to be uniformly distributed on the matrix surface and inside the pores. This achieves a strong bond between the active component and the matrix, preventing particle detachment and improving the overall structural stability and durability of the material. Relying on the inherent catalytic properties of nano-copper, the material is endowed with highly efficient catalytic reduction capabilities, allowing it to quickly play a role in scenarios such as pollutant treatment. At the same time, the porous characteristics and environmentally friendly properties of the matrix itself are maintained, achieving a synergistic unity of function and structure.

[0020] The nano-copper / carmine radish cellulose porous composite material prepared by this invention has good structural stability, environmental friendliness and catalytic functionality. It can be used stably under room temperature conditions without the need for harsh reaction conditions. The ionic liquid in the material preparation process can be recycled, reducing the overall preparation cost and energy consumption. After use, the material can maintain stable performance and be reused, extending its service life. It is suitable for various application scenarios such as organic dye degradation, and has both environmental and practical value.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the preferred embodiments of this application are described in detail below with reference to the accompanying drawings.

[0022] The above and other objects, advantages and features of this application will become more apparent to those skilled in the art from the following detailed description of specific embodiments in conjunction with the accompanying drawings. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0024] Based on the description of the figures and their corresponding technical content in the document, the titles of the figures are as follows:

[0025] Figure 1 This is a flowchart illustrating the preparation process of a nano-copper / carmine cellulose porous composite material.

[0026] Figure 2 This is a schematic diagram of the crosslinking reaction between cellulose and HDI in a homogeneous system (EMIMCl is the solvent);

[0027] Figure 3 Macroscopic and microscopic morphological images and spectra of the nano-copper / carmine cellulose porous composite material;

[0028] Figure 4 The UV-Vis absorption spectra of the nano-copper / radish cellulose porous composite material for the catalytic degradation of MB (a), BCG (c) and MO (e) and the blank control MB (b), BCG (d) and MO (f) are shown. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. In the following description, specific details such as specific configurations and components are provided merely to help fully understand the embodiments of this application. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this application. In addition, for clarity and brevity, descriptions of known functions and structures are omitted in the embodiments.

[0030] It should be understood that the phrase "an embodiment" or "this embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of this application. Therefore, "an embodiment" or "this embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0031] Furthermore, reference numerals and / or letters may be repeated in different examples within this application. Such repetition is for the purpose of simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0032] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" in this article describes another type of relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after it are in an "or" relationship.

[0033] In this article, the term "at least one" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, "at least one of A and B" can mean: A exists alone, A and B exist simultaneously, or B exists alone.

[0034] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion.

[0035] Example 1

[0036] This embodiment mainly describes a method for preparing a porous composite material of nano-copper / carmine radish cellulose, such as... Figure 1 As shown, it specifically includes:

[0037] S1. Preparation of radish cellulose powder: The radish residue is dried and pulverized, and then subjected to acid boiling, alkali boiling, oxidative bleaching, and ammonia treatment in sequence. After filtration and washing until neutral, the radish cellulose powder is obtained by freeze drying.

[0038] S2. Preparation of cross-linked cellulose porous material: Radish cellulose powder was dissolved in ionic liquid 1-ethyl-3-methylimidazolium chloride EMIMCl at 95℃ to form a homogeneous solution. Hexamethylene diisocyanate HDI was added as a cross-linking agent to carry out the cross-linking reaction. After replacement with deionized water, removal of chloride ions, and freeze drying, cross-linked cellulose porous material was obtained.

[0039] S3. Loading nano-copper: Prepare a copper ammonia solution, add a reducing agent to obtain a nano-copper precursor solution, immerse the cross-linked cellulose porous material in the precursor solution to load nano-copper, wash and freeze-dry to obtain a nano-copper / carrot cellulose porous composite material.

[0040] The radish residue was dried and pulverized into powder. 50 g of the powder was added to a 1.25 wt% solution. Boil in an aqueous solution for 2 hours, filter, and wash three times with deionized water. Place the filter cake in a 12.5 wt% KOH aqueous solution, boil for 4 hours, filter and wash with deionized water until the filtrate is colorless. Add the filter residue to a solution containing 4 wt% NaOH and 5 wt% KOH. 0.02wt% The mixture was boiled in an aqueous solution of 2wt% EDTA-2Na for 2 h, filtered, and washed with deionized water. The residue was then placed in a solution of 27wt% EDTA-2Na. and 36wt% The solution was boiled until it turned white, then filtered and washed with deionized water until the filtrate was neutral. After freeze-drying, radish cellulose powder was obtained.

[0041] In a 250 mL side-arm flask equipped with a mechanical stirrer, 1 g of radish cellulose (DP = 300) and 100 g of EMIMCl were added. The mixture was evacuated and then refilled with nitrogen three times, and placed in an oil bath at 95°C for constant temperature. Once the mixture of radish cellulose and EMIMCl became a homogeneous solution, HDI (used as a crosslinking agent) was added to the solution at a molar ratio of 3:1. After 1 hour, the liquid in the flask (crosslinked cellulose / EMIMCl solution) was poured into a cylindrical mold and placed in a vacuum oven at 80°C for 24 hours to defoam. Next, the mold was removed from the oven, and deionized water was dripped into it. Subsequently, the mold was placed in a water bath containing deionized water, with the deionized water changed every 24 hours until a concentration of 0.01 mol / L was reached. Chloride ions (Cl) were not detected. - Following this procedure, the mold was opened and the cross-linked cellulose hydrogel was extracted. The hydrogel was then freeze-dried at -55°C under vacuum at 1 Pa for 24 h to form a cylindrical radish cellulose porous material with a diameter of 15 mm and a height of 10 mm. EMIMCl was recovered by rotary evaporation.

[0042] Under magnetic stirring, 11.98 g Dissolve in 240 mL of deionized water, then add concentrated solution dropwise. The solution was gradually diluted until a deep blue color was formed. 7.92 g of vitamin C was added to the solution, and the solution gradually turned yellow. The radish cellulose porous material was then immersed in the yellow solution for 4 hours. The hydrogel was washed three times with deionized water and freeze-dried to obtain a cylindrical nano-copper / radish cellulose porous composite material with a diameter of 15 mm and a height of 10 mm. The mass of nano-Cu loaded on the porous composite material was approximately 0.0181 g.

[0043] Furthermore, such as Figure 2The crosslinking reaction of cellulose and HDI in the homogeneous ionic liquid EMIMCl system is shown. Before the reaction, the cellulose molecular chains interact with each other through numerous hydrogen bonds, forming a highly aggregated intermolecular network. These hydrogen bonds restrict the solubility and reactivity of cellulose, making it difficult to achieve uniform crosslinking. In the ionic liquid EMIMCl solvent at 95°C, the hydrogen bonds between cellulose molecules are effectively broken, and cellulose completely dissolves to form a homogeneous solution. The molecular chains are then fully extended, exposing a large number of reactive hydroxyl sites.

[0044] The isocyanate groups (-NCO) at both ends of the crosslinking agent hexamethylene diisocyanate (HDI) molecule can undergo nucleophilic addition reactions with the hydroxyl groups (-OH) on the cellulose molecular chain to form stable carbamate bonds. As shown in the figure, the two ends of the HDI molecule react with the hydroxyl groups on different cellulose molecular chains, connecting the originally independent cellulose molecular chains through the HDI bridging structure to construct a three-dimensional crosslinked network structure.

[0045] During the reaction, the aliphatic long chain segments of HDI act as flexible connecting units, inserting between cellulose molecular chains. While retaining some intramolecular and intermolecular hydrogen bonds of cellulose, new network nodes are formed through covalent cross-linking. This avoids the brittleness problem caused by hydrogen bond aggregation in traditional cellulose materials, and also endows the material with a stable three-dimensional skeleton structure through covalent bonds.

[0046] In the resulting cross-linked cellulose structure, urethane bonds are uniformly distributed throughout the cellulose network. The flexible segments of HDI act as cross-linking bridges, firmly connecting different cellulose molecular chains to form a three-dimensional cross-linked network porous structure that combines chemical stability with structural flexibility. This structure retains the basic chemical framework of cellulose while achieving permanent connections between molecular chains through covalent cross-linking. It provides a stable and uniform porous matrix for subsequent loading of copper nanoparticles, allowing the copper nanoparticles to be uniformly distributed on the matrix surface and within the pores, achieving a synergistic unity of structure and function.

[0047] This embodiment details the preparation of cellulose from radish residue through multi-stage purification, followed by the construction of a three-dimensional network through homogeneous dissolution with ionic liquid and chemical bonding with HDI, achieving uniform loading of nano-copper. This process not only realizes the high-value utilization of biomass waste but also yields a porous composite material with both structural stability and catalytic activity, providing a new, efficient, and environmentally friendly approach for the treatment of organic dye wastewater.

[0048] Based on Example 1, this example uses the nano-copper / carmine radish cellulose porous composite material prepared in this application as the research object. Using a reducing agent, catalytic degradation performance tests were conducted on three typical organic dyes: methylene blue (MB), bromocresol green (BCG), and methyl orange (MO). A blank control experiment without a catalyst was also set up to verify the catalytic activity, reaction rate, and mechanism of action of the material in this application. At the same time, the microstructure, elemental composition, and distribution of active components of the material were verified by characterization methods such as SEM, EDX, and elemental surface scanning.

[0049] The experimental reagents used included: radish residue (a commercially available byproduct of agricultural product processing), 1-ethyl-3-methylimidazolium chloride (EMIMCl, an ionic liquid), hexamethylene diisocyanate (HDI, a crosslinking agent), and copper acetate monohydrate (…). Vitamin C (reducing agent) ,sulfuric acid( Potassium hydroxide (KOH), sodium hydroxide (NaOH), hydrogen peroxide ( ), magnesium sulfate ( ), EDTA-2Na, silver nitrate ( Methylene blue (MB), bromocresol green (BCG), methyl orange (MO), sodium borohydride ( All reagents were of analytical grade, and the water used in the experiment was deionized water.

[0050] The experimental instruments included: electronic balance, freeze dryer, vacuum oven, magnetic stirrer, oil bath, scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDX), elemental surface scanning (EDSmapping) system, and ultraviolet-visible spectrophotometer.

[0051] The experimental steps specifically include:

[0052] The preparation of nano-copper / carmine cellulose porous composite materials is as follows:

[0053] Preparation of radish cellulose powder: Dry and pulverize radish residue, take 50 g of powder and add 1.25 wt% of [unspecified ingredient]. Boil in aqueous solution for 2 hours, filter and wash three times; then add 12.5 wt% KOH aqueous solution and boil for 4 hours, filter until the filtrate is colorless; subsequently add solution containing 4 wt% NaOH and 5 wt% KOH. 0.02wt% Boil a 2wt% EDTA-2Na aqueous solution for 2 h; finally add 27wt% With 36wt% The mixture was boiled until it turned white, washed until neutral, and freeze-dried to obtain radish cellulose powder.

[0054] Preparation of cross-linked cellulose porous materials: Radish cellulose powder was added to an ionic liquid at a mass ratio of 1:100, and the mixture was dissolved by alternating between vacuum and nitrogen purging three times in a 95°C oil bath with stirring. HDI (molar ratio of 3:1 to radish cellulose) was added and reacted for 1 h. The mixture was then poured into a mold and defoamed under vacuum at 80°C for 24 h. The mixture was then replaced with deionized water (0.01 mol / L, every 24 h). (The test showed no chloride ions) to obtain a hydrogel; it was then freeze-dried at -55℃ and 1 Pa for 24 h to obtain a cross-linked cellulose porous material.

[0055] Copper nanoparticle loading: 11.98 g Dissolved in 240 mL of deionized water, concentrated ammonia was added dropwise to obtain a deep blue copper ammonia solution; 7.92 g of vitamin C was added to obtain a yellow precursor solution; the cross-linked cellulose porous material was immersed in the precursor solution for 4 h, washed, and then freeze-dried to obtain a nano-copper / carrot cellulose porous composite material.

[0056] like Figure 3 The material characterization shown is evident. Figure 3 (a) Macroscopic and microscopic morphology characterization: The macroscopic morphology of the material was captured by a digital camera. It was a regular cylindrical shape with no obvious defects on the surface. The microstructure of the material was observed by low magnification SEM. It was found that the material had a three-dimensional interconnected macroporous structure with a pore size of about 300 μm. The pore walls were intact and continuous without collapse or breakage. The pores were evenly distributed, providing sufficient space for subsequent reaction solution diffusion and loading of active components.

[0057] Figure 3 (b) Morphology and particle size distribution of copper nanoparticles: The surface of the material was observed by high-magnification SEM. It can be seen that the copper nanoparticles are uniformly distributed on the surface of the matrix and the inner wall of the pores. The particles are nearly spherical and there is no obvious agglomeration. The particle size distribution statistics show that the particle size is concentrated in 20-40 nm, with an average particle size of about 30 nm. The distribution is narrow and uniform, indicating that the in-situ reduction process effectively controls the particle growth and ensures the full exposure of active sites.

[0058] Figure 3 (c) Elemental composition analysis: The elemental composition of the material was analyzed by EDX energy dispersive spectroscopy. The results showed that the characteristic peaks of C, O and Cu were clearly present, and there were no other impurity peaks. Quantitative analysis showed that the mass fraction of C was 39.28%, O was 12.17% and Cu was 48.54%, with atomic percentages of 68.20%, 15.86% and 15.93%, respectively. This verified that the nano-copper was successfully loaded onto the cellulose matrix and the elemental composition was stable.

[0059] Figure 3(d) Elemental distribution characterization: The distribution of C, O, and Cu was observed by SEM-EDS elemental surface scanning. C and O elements were uniformly distributed throughout the entire matrix region, which was highly consistent with the morphology of the porous material. Cu elements were uniformly distributed on the matrix surface and the inner wall of the pores, with no local enrichment or blank areas, indicating that the nano-copper achieved uniform dispersion and loading, and was firmly bonded to the matrix without detachment or agglomeration.

[0060] Furthermore, catalytic degradation performance was tested, and the experimental system was set up, including:

[0061] Reaction vessel: 200 mL beaker, reaction volume 200 mL.

[0062] Target pollutants: MB, BCG, and MO solutions, all with an initial concentration of 10 µmol / L.

[0063] reducing agent: The aqueous solution has a concentration of 0.5 mol / L, and 2 mL is added each time.

[0064] Catalyst: Nano-copper / carrot cellulose porous composite material.

[0065] Control group: No catalyst, only the same volume of catalyst added. A dye solution.

[0066] Experimental conditions: magnetic stirring, conducted at room temperature, with timed sampling, and absorbance changes recorded using a UV-Vis spectrophotometer.

[0067] The testing steps include:

[0068] Measure 200 mL of the 10 µmol / L target dye solution, add it to a beaker, stir magnetically until homogeneous, and measure the initial absorbance (0 min).

[0069] Experimental group: Add 2 mL of 0.5 mol / L The solution was reacted with the nano-copper / radish cellulose porous composite material to initiate a catalytic reaction. Samples were taken at predetermined time intervals (e.g., MB for 5, 10, 15, 20, 25 min; BCG for 60, 120, 240 min; MO for 20, 40, 60, 80 min) and the absorbance was recorded.

[0070] Blank control group: only 2 mL of 0.5 mol / L solution was added. For solutions without added catalysts, absorbance changes were recorded at equal time intervals.

[0071] The degradation process was characterized by the change in the intensity of the characteristic absorption peaks of the dyes over time: the characteristic peak of MB was 664 nm, that of BCG was 616 nm, and that of MO was 464 nm.

[0072] The catalytic performance results of the experiment are as follows: Figure 4 As shown, the degradation results of methylene blue (MB) are as follows: Figure 4 a, 4b)

[0073] experimental group Figure 4 (a): As the reaction time increases, the intensity of the characteristic absorption peak of MB at 664 nm decreases rapidly, and the absorption peak intensity drops to an extremely low level within 25 min, indicating that MB is rapidly reduced and degraded, with a fast reaction rate and high degradation efficiency.

[0074] Blank control group Figure 4 (b): Under the same conditions, the characteristic absorption peak of MB only decreased slightly within 240 min, with almost no significant degradation, indicating that it can be degraded by relying solely on... The inability to effectively reduce MB led to the introduction of porous composite materials, which significantly reduced the activation energy of the reaction, greatly increased the reaction rate, and demonstrated excellent catalytic activity.

[0075] Degradation results of bromocresol green (BCG) Figure 4 c, 4d)

[0076] experimental group Figure 4 (c): As the reaction time increases, the intensity of the characteristic absorption peak of BCG at 616 nm gradually decreases, and the absorption peak intensity decreases significantly within 240 min, indicating that BCG is effectively degraded.

[0077] Blank control group Figure 4 (d): Under the same conditions, the characteristic absorption peak of BCG only decreased slightly within 240 min, indicating extremely poor degradation effect. This suggests that the porous composite material also has a significant catalytic promoting effect on BCG and can effectively promote degradation. The reduction reaction of BCG.

[0078] Degradation results of methyl orange (MO) Figure 4 e, 4f)

[0079] experimental group Figure 4 (e): As the reaction time increases, the intensity of the characteristic absorption peak of MO at 464 nm decreases rapidly, and the absorption peak intensity basically disappears within 80 min, indicating that MO is completely degraded.

[0080] Blank control group Figure 4 (f): Under the same conditions, the characteristic absorption peak of MO remained almost unchanged within 240 min, further verifying the high efficiency of the porous composite material for catalytic MO.

[0081] The nano-copper / carmine cellulose porous composite material prepared in this application has the characteristics of uniform three-dimensional interconnected pore structure and uniformly dispersed loading of nano-copper particles. Under the given conditions, the material exhibits highly efficient catalytic degradation performance for three organic dyes: MB, BCG, and MO. The reaction rates are significantly higher than those of the blank control group without a catalyst, demonstrating that the catalytic activity of the material mainly originates from the synergistic effect of nano-copper and the porous matrix. This material can achieve rapid reduction and degradation of various organic dyes without secondary pollution, and the ionic liquid can be recycled during the preparation process, combining environmental friendliness and practicality, providing a new technical solution for the treatment of organic dye wastewater.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any changes, modifications, substitutions, integrations, and parameter changes made to these embodiments within the spirit and principles of the present invention, without departing from the principles and spirit of the present invention, through conventional substitutions or to achieve the same function, fall within the scope of protection of the present invention.

Claims

1. A method for preparing a porous composite material of nano-copper / carmine radish cellulose, characterized in that, Includes the following steps: S1. Preparation of radish cellulose powder: The radish residue is dried and pulverized, and then subjected to acid boiling, alkali boiling, oxidative bleaching, and ammonia treatment in sequence. After filtration and washing until neutral, the radish cellulose powder is obtained by freeze drying. S2. Preparation of cross-linked cellulose porous material: Radish cellulose powder was dissolved in ionic liquid 1-ethyl-3-methylimidazolium chloride EMIMCl at 95℃ to form a homogeneous solution. Hexamethylene diisocyanate HDI was added as a cross-linking agent to carry out the cross-linking reaction. After replacement with deionized water, removal of chloride ions, and freeze drying, cross-linked cellulose porous material was obtained. S3. Loading nano-copper: Prepare a copper ammonia solution, add a reducing agent to obtain a nano-copper precursor solution, immerse the cross-linked cellulose porous material in the precursor solution to load nano-copper, wash and freeze-dry to obtain a nano-copper / carrot cellulose porous composite material.

2. The preparation method according to claim 1, characterized in that, S1 specifically involves: pulverizing the radish residue into powder, and adding 40 g to 60 g of the powder to a solution with a mass fraction of 1.0 wt% to 1.5 wt%. Boil in aqueous solution for 1-3 hours, filter, and wash several times with deionized water; take the filter cake and add it to a 10.0wt%-15.0wt% KOH aqueous solution and boil for 3-5 hours, filter and wash until the filtrate is colorless; then add the filter residue to a solution containing 3.0wt%-5.0wt% NaOH and 4.0wt%-6.0wt% KOH. 0.01wt%~0.03wt% Boil in an aqueous solution of 1.0wt%–3.0wt% EDTA-2Na for 1–3 hours, filter and wash; finally, place the filter residue in an aqueous solution of 25wt%–30wt% EDTA-2Na. With 35wt%~40wt% Boil the mixture in the solution until it turns white, filter and wash until the filtrate is neutral, and freeze-dry to obtain radish cellulose powder.

3. The preparation method according to claim 1, characterized in that, In S2, the mass ratio of radish cellulose to EMIMCl is 1:80 to 1:120; after the mixed system is evacuated and purged with nitrogen 2 to 4 times, it is stirred at a constant temperature in an oil bath at 90℃ to 100℃ until it is completely dissolved into a homogeneous solution; the molar ratio of HDI to radish cellulose is 2:1 to 4:1, and the crosslinking reaction time is 0.5 h to 1.5 h.

4. The preparation method according to claim 3, characterized in that, In step S2, the cross-linked solution is poured into a cylindrical mold and defoamed under vacuum at 70℃~90℃ for 20 h~28 h; the ionic liquid is replaced with deionized water, with the water changed every 12 h~36 h at a concentration of 0.005 mol / L~0.015 mol / L. The solution was tested until no chloride ions were detected, and a cross-linked cellulose hydrogel was obtained.

5. The preparation method according to claim 4, characterized in that, In step S2, the freeze-drying conditions are -60℃ to -50℃, vacuum degree is 0.5 Pa to 1.5 Pa, and drying time is 20 h to 28 h, to obtain a cylindrical cross-linked cellulose porous material; the ionic liquid EMIMCl is recovered by rotary evaporation.

6. The preparation method according to claim 1, characterized in that, Specifically, S3 involves: stirring the mixture under magnetic force. Dissolve in deionized water, add concentrated ammonia dropwise until a deep blue copper ammonia solution is formed; add vitamin C to obtain a yellow nano-copper precursor solution; immerse the cross-linked cellulose porous material in the precursor solution, remove it, wash it with deionized water, and freeze-dry it to obtain the target material.

7. The preparation method according to claim 6, characterized in that, The dosage is 10 g to 13 g, the amount of deionized water is 200 mL to 280 mL, the amount of vitamin C is 7 g to 9 g, and the soaking load time is 3 h to 5 h.

8. A porous composite material of nano-copper / carmine radish cellulose, characterized in that, Cross-linked cellulose is used as a porous matrix with a three-dimensional cross-linked network pore structure inside. The cellulose matrix is ​​obtained by chemically cross-linking hexamethylene diisocyanate (HDI) with the hydroxyl groups on the cellulose molecules to form urethane bonds. The porous matrix is ​​uniformly loaded with nano-copper particles on its surface and in its pores.

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