ZnFe2O4 / MXene / ZnO / collagen aerogel as well as preparation method and application thereof
By constructing a heterojunction structure of ZnFe2O4/MXene/ZnO/collagen aerogel, the problems of easy recombination and difficult recovery of photogenerated carriers in photocatalysts are solved, achieving efficient photocatalytic degradation and magnetic recovery, which is suitable for the rapid removal of organic pollutants.
Patent Information
- Application Number
- CN202511088451.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2026-01-20
AI Technical Summary
Existing photocatalysts such as ZnFe2O4 have problems with easy recombination of photogenerated carriers, ZnO has a wide band gap leading to insufficient light utilization efficiency, co-catalysts are expensive and difficult to recycle, and semiconductor photocatalysts have poor enrichment and recycling effects.
A ZnFe2O4/MXene/ZnO/collagen aerogel was prepared by constructing a heterojunction structure and introducing two-dimensional highly conductive MXene to optimize the separation of photogenerated carriers. This structure was then combined with the collagen aerogel to form an integrated adsorption-degradation system.
It significantly improves the photogenerated electron-hole separation rate of photocatalysts, enhances the degradation efficiency of organic pollutants, and achieves recycling through magnetic recovery, solving the problem of difficult recycling of traditional photocatalysts.
Smart Images
Figure CN121360596A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a ZnFe2O4 / MXene / ZnO / collagen aerogel as well as a preparation method and application thereof. BACKGROUND
[0002] In recent years, with the rapid development of the industrial, agricultural and medical industries, the types and concentrations of organic matter in wastewater have significantly increased, and the complexity and environmental hazards thereof have posed severe challenges to traditional water treatment technologies. Currently, the organic matter detected in wastewater mainly includes pesticide residues, pharmaceutical active substances (such as antibiotics and hormones), organic solvents (such as chloroform) and emerging pollutants (such as microplastics and perfluorinated compounds). These pollutants not only directly endanger life and health, but also damage the ecological chain, exacerbate the crisis of drug resistance and derive secondary pollution, forming a vicious cycle of “pollution-treatment-repollution”. The current common organic pollutant removal technologies in wastewater mainly include adsorption, chemical degradation and biological treatment methods. The adsorption method has the advantages of high selectivity and simple operation, but has the disadvantages of easy saturation of adsorption materials, poor selectivity, possible secondary pollution and incomplete treatment of pollutants. The biological treatment method has a high removal rate for easily degradable organic matter, but is limited by the sensitivity of microorganisms to toxic substances (such as antibiotics and heavy metals), which can easily cause sludge activity inhibition and even system collapse. The photocatalytic oxidation technology in the chemical degradation method can realize the decomposition of organic matter through the generation of free radicals, has a wide range of applications and does not produce secondary pollution, and is environmentally friendly. However, the semiconductor photocatalysts used in the photocatalytic oxidation technology are mostly in powder form and are difficult to recover. The free radicals generated have a very short time from generation to disappearance, which limits the degradation efficiency of the photocatalytic oxidation technology on refractory organic matter.
[0003] With the acceleration of industrialization, the traditional linear economic model has caused excessive consumption of resources and environmental pollution. The current global challenges such as climate change and loss of biodiversity highlight the importance of circular economy. In the leather industry, chromium tanning is the mainstream tanning process, which produces a large amount of chromium-containing leather scraps (CLSs) containing a large amount of Cr 3+ , which has potential harm to the environment and human body, so CLSs are listed as hazardous waste and included in the National Hazardous Waste List. More than 90% of the components in CLSs are collagen, which is a natural renewable resource. In order to solve the problem of chromium pollution and achieve economic benefits, the chromium in CLSs is removed and the collagen is used for high-value utilization. The collagen is rich in active groups such as -COOH, -NH2 and -OH, and has excellent renewability and biodegradability, so the collagen can be made into porous aerogel and used as adsorbent in water treatment.
[0004] As a photocatalyst, nano ZnFe2O4 has a narrow band gap (~1.9 eV) and can efficiently absorb visible light to improve the utilization rate of sunlight. Its magnetic properties make the catalyst easy to recycle and reuse, reducing secondary pollution. At the same time, ZnFe2O4 has high chemical stability and light stability, and is non-toxic, low in cost and environmentally friendly. However, its high charge recombination rate leads to easy recombination of photo-generated electron-hole pairs, reducing the photocatalytic efficiency. Low photo-carrier mobility limits the reaction activity. The main ways to improve the photocatalytic efficiency of ZnFe2O4 include loading of cocatalysts, regulation of microstructure and construction of heterojunction structure. Among them, by regulating the microstructure, the rich active sites of ZnFe2O4 can be increased, thereby improving its catalytic activity; loading of cocatalysts can effectively improve and enhance the separation and transfer efficiency of ZnFe2O4 carriers, and promote and stabilize the activity of the photocatalyst; the construction of heterojunction is composed of two kinds of semiconductors. Due to the different energy band structures of the two semiconductors, an energy level difference will be formed between the two semiconductors. The photo-generated electrons produced in this way will transfer to the energy level of the other semiconductor material, prolonging the recombination time of photo-generated electrons and holes and improving the separation rate of photo-generated electrons and holes.
[0005] As a new type of two-dimensional material, MXene is usually prepared by etching titanium aluminum carbide (Ti3AlC2). Its structural feature is that metal ion layers and carbon or nitrogen atom layers are alternately stacked. This unique layered structure endows MXene with excellent electrical conductivity. In the field of photocatalysis, MXene can be used as a substitute material for noble metal cocatalysts. The electrons generated by the excitation of semiconductors can effectively migrate to MXene, thereby significantly promoting the separation of photo-generated electron-hole pairs and ultimately improving the overall performance of the photocatalyst.
[0006] Among many photocatalysts, ZnO has a mature preparation process, is inexpensive and non-toxic, and also has high photocatalytic activity. However, due to its wide band gap, it has limited utilization of visible light, and most ZnO is in the form of fine powder particles, which is difficult to separate and recover from water when used for photocatalytic treatment of wastewater pollutants. SUMMARY
[0007] In view of the problems existing in the prior art, the purpose of the present application is to provide a ZnFe2O4 / MXene / ZnO / collagen aerogel and a preparation method and application thereof, to overcome the technical limitations of the easy recombination of photo-generated carriers (electron-hole pairs) of ZnFe2O4, the insufficient light utilization efficiency of ZnO due to its wide band gap, the high cost defect of the existing cocatalyst system, and the poor enrichment and recovery effect of semiconductor photocatalysts.
[0008] The technical scheme adopted by the present application is as follows:
[0009] A ZnFe2O4 / MXene / ZnO / collagen aerogel and a preparation method thereof, comprising the following steps:
[0010] (1) iron source FeSO4·7H2O and zinc source Zn(NO3)2·6H2O are added to a solvent, stirred to completely dissolve, and then a structure directing agent is added to obtain a precursor solution;
[0011] (2) the precursor solution is placed in a polytetrafluoroethylene reaction kettle for hydrothermal reaction, and after the reaction is completed, it is naturally cooled to room temperature, and after being washed with deionized water and anhydrous ethanol alternately for 3-7 times, vacuum drying at 60 DEG C and grinding, ZnFe2O4 powder is obtained;
[0012] (3) MXene is dispersed in deionized water to form a MXene dispersion liquid; the ZnFe2O4 powder obtained in (1) is added to the MXene dispersion liquid, and after ultrasonic, stirring, centrifugal, vacuum drying at 60 DEG C, ZnFe2O4 / MXene is prepared;
[0013] (4) the ZnFe2O4 / MXene is added to a zinc precursor solution, stirred to fully mix; then NaOH solution is added dropwise, and reacted at 50-90 DEG C for 4-8 h; after the reaction is completed, it is washed with deionized water and ethanol alternately for 3-6 times, and vacuum dried at 60 DEG C to obtain a photocatalyst ZnFe2O4 / MXene / ZnO;
[0014] (5) the ZnFe2O4 / MXene / ZnO is added to a collagen fiber dispersion liquid, stirred to fully mix, and freeze-dried to obtain an aerogel base;
[0015] (6) the aerogel base is placed in a zinc precursor solution, soaked at room temperature for 12 h, then placed in a NaOH / ethanol solution and reacted at 40-60 DEG C. Then the aerogel is sequentially placed in n-hexane and ethanol, and taken out, and naturally dried at room temperature to obtain a ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0016] The preferred concentration of the iron source in the above step (1) is 0.06-0.20 mol / L, more preferably 0.1-0.16 mol / L; the preferred concentration of the zinc source is 0.03-0.10 mol / L, more preferably 0.05-0.08 mol / L. Higher or lower concentrations of iron source and zinc source will reduce the yield or yield of ZnFe2O4. The molar ratio of iron source and zinc source is fixed at 2:1, the main reason is that the molar ratio of zinc element and iron element in the product ZnFe2O4 is 2:1, and this ratio can reduce the appearance of Fe2O3 in the product.
[0017] The preferred solvent in step (1) is one or both of ethylene glycol and deionized water, and the structure directing agent is one of NaOH, urea, oxalic acid, a urea / ammonium fluoride mixture, or none. The choice of solvent affects the heat transfer process of the reaction system through its thermal conductivity difference, which in turn affects the properties of the final product. The role of the structure directing agent is to guide the specific oriented growth of ZnFe2O4 crystals, and by adjusting its type and concentration, selective control of the growth kinetics of different crystal faces can be achieved, ultimately obtaining the target morphology.
[0018] The preferred temperature for the hydrothermal reaction in step (2) is 180-220°C, and the reaction time is 12-24h, and more preferably the temperature and time are 190-200°C and 16-20h, respectively. By precisely controlling the reaction temperature, the growth kinetics of different crystal faces of ZnFe2O4 crystals can be differentially adjusted, thereby effectively controlling the morphology of the product. At the same time, the reaction time is also a key parameter: too short will affect the integrity of the crystal development and the achievement of the target particle size, and too long will significantly reduce the efficiency of the preparation process.
[0019] The preferred mass percentage concentration of MXene in step (3) is 0.01%-0.2%, and more preferably 0.05%-0.1%, and the mass ratio of ZnFe2O4 to MXene is 1:(0.01-0.2), and more preferably the mass ratio is 1:(0.05-0.15). The ultrasonic time is 4-8h, and the stirring time is 12-16h, and more preferably the ultrasonic time and stirring time are 5-6h and 13-15h. Too low a concentration of MXene will result in a decrease in the solid content of the product, reducing the efficiency of the preparation; while too high a concentration will easily lead to deterioration of the dispersion of MXene, hindering its effective compounding with ZnFe2O4. In addition, excess MXene will inhibit the photocatalytic activity due to the optical shielding effect.
[0020] The zinc precursor in step (4) is one of zinc nitrate or zinc acetate, and more preferably zinc nitrate. The preferred mass of ZnFe2O4 / MXene is 10-60mg, and more preferably the mass is 30-50mg, the molar concentration of the zinc precursor solution is 0.01-0.12mol / L, and more preferably the concentration is 0.05-0.10mol / L, and the molar concentration of the NaOH solution is 0.02-0.48mol / L, and more preferably the concentration is 0.08-0.24mol / L. Too much ZnO agglomerates on the surface of the catalyst, which may affect the absorption efficiency of visible light by ZnFe2O4, thereby reducing the photocatalytic activity of ZnFe2O4 / MXene / ZnO.
[0021] The mass of ZnFe2O4 / MXene / ZnO in the above step (5) is 10-60 mg, and the more preferred mass is 30-50 mg; the collagen fiber dispersion liquid is obtained by using oxalic acid / sulfuric acid mixed solution to carry out chromium removal treatment on chromium-containing waste leather scraps, and the solid content is 1%-3%, and the more preferred solid content is 1.5-2.5%. If the solid content of the collagen dispersion liquid is too high, the porosity of the aerogel will be reduced, thereby affecting the enrichment effect of the aerogel on pollutants; but if the solid content is too low, the strength and stability of the aerogel will be affected. The introduction of an appropriate amount of ZnFe2O4 / MXene / ZnO photocatalyst is beneficial to strengthening the photocatalytic degradation effect, but too much will affect the light transmittance and reduce the light absorption rate, which is not conducive to the removal of organic matter.
[0022] The zinc precursor in the above step (6) is one of zinc nitrate and zinc acetate, and the more preferred one is zinc nitrate. The preferred concentration of the zinc precursor is 0.02-0.12 mol / L, and the more preferred concentration is 0.05-0.10 mol / L; the preferred concentration of the NaOH / ethanol solution is 0.04-0.72 mol / L, and the more preferred concentration is 0.10-0.40 mol / L.
[0023] The ZnFe2O4 / MXene / ZnO / collagen aerogel prepared by the above preparation method is introduced with MXene and heterojunction, which effectively promotes the separation of photo-generated carriers of the photocatalyst and inhibits the recombination of electrons and holes. By further introducing the catalyst into the aerogel, the enrichment effect of the material is improved. The composite aerogel has a rapid degradation efficiency for organic pollutants under visible light, and can be recycled by magnetic recovery for cyclic utilization.
[0024] The ZnFe2O4 / MXene / ZnO / collagen aerogel prepared by the above preparation method is suitable for the treatment of medical wastewater.
[0025] The beneficial effects of the present application are:
[0026] 1) The chromium-containing waste leather scraps are turned into treasure, and the enrichment effect of the collagen aerogel is utilized:
[0027] In order to respond to the concept of sustainable circular economy, leather waste is converted into a new type of material. The hazardous waste, chromium-containing waste leather scraps, are used as raw materials, and collagen is extracted from them by using mixed acid method. The photocatalyst ZnFe2O4 / MXene / ZnO is introduced to prepare collagen composite aerogel. This design breaks through the limitation of traditional collagen aerogel which needs strong acid / alkali regeneration treatment. At the same time, the enrichment effect of the aerogel on pollutants is utilized to cooperate with photocatalytic degradation, forming an adsorption-degradation coupling system, which significantly improves the removal efficiency of tetracycline hydrochloride. For example, Figure 2As shown, the adsorption rate of Comparative Example 1 on tetracycline hydrochloride reached about 29% in 30 minutes, and the adsorption of the sample in Example 5 on tetracycline hydrochloride reached equilibrium in 60 minutes, and the adsorption rate was 2-3 times that of the comparative example. Due to the enrichment effect of aerogel, the removal rate of tetracycline hydrochloride in Example 10 minutes can almost reach the effect of Comparative Example 140 minutes.
[0028] 2) Morphology adjustability and structural advantages:
[0029] By adjusting the structure-directing agent and hydrothermal reaction parameters, polyhedral, nanospheres and other diversified morphologies of ZnFe2O4 can be prepared. This strategy effectively improves the specific surface area of the material and widens the light response range, thereby significantly improving its surface adsorption capacity and light excitation efficiency on pollutants.
[0030] 3) High-efficiency photocatalytic performance and carrier separation optimization:
[0031] By introducing two-dimensional high-conductivity MXene and constructing a heterojunction structure, the key problem of low catalytic efficiency of ZnFe2O4 due to the easy recombination of photo-generated electrons and holes is effectively solved.
[0032] 4) Integration of adsorption-photocatalytic technology to accelerate degradation:
[0033] By combining adsorption method with photocatalytic technology, the adsorbent is used to enrich pollutants, and then under light conditions, the photocatalyst generates active free radicals to in-situ degrade pollutants. This synergistic mechanism not only improves the removal efficiency of pollutants, but also effectively overcomes the defects of single technology. BRIEF DESCRIPTION OF DRAWINGS
[0034] Figure 1 SEM images of ZnFe2O4 in Examples 1-5.
[0035] Figure 2 Degradation curve of tetracycline hydrochloride by Comparative Example 1.
[0036] Figure 3 Adsorption curve of tetracycline hydrochloride by Example 1. Figure 4 Degradation curve of tetracycline hydrochloride by Example 1. Figure 5 Magnetic recovery schematic diagram of Example 5. DETAILED DESCRIPTION
[0037] The application will be further described in detail below in conjunction with specific embodiments, but the embodiments of the application include but are not limited to the scope represented by the following examples.
[0038] The conductive material MXene in the present application is prepared by the following method: 1.3g of LiF is weighed and dissolved in a polytetrafluoroethylene container containing 30mL of concentrated hydrochloric acid, and magnetically stirred at room temperature for 5min to completely dissolve it. 1.95g of Ti3AlC2 powder is slowly added within 10min, keeping the molar ratio of LiF and Ti3AlC2 at 5:1. The mixture is placed at 50±5°C and stirred overnight, then ultrasonic-assisted mechanical stirring is used at 50°C for 12h, followed by overnight stirring. After the reaction is completed, the mixture is cooled to room temperature, and the mixture is washed alternately with water and ethanol until the pH value reaches 6 to remove excess acid and LiF. Finally, the washed product is centrifuged to obtain a precipitate, which is vacuum dried at 60°C to obtain MXene.
[0039] Example 1
[0040] Take 0.595 g Zn(NO3)2·6H2O and 1.112 g FeSO4·7H2O, dissolve in 40 mL of deionized water; then, add NaOH to make the pH value of the system 13, to obtain the precursor solution. Put the above precursor solution in a polytetrafluoroethylene reaction kettle and hydrothermal reaction at 190℃ for 24 h. After the reaction is completed, it is naturally cooled to room temperature, washed with deionized water and anhydrous ethanol alternately for 4 times, vacuum dried at 60℃ and ground to obtain ZnFe2O4 powder; 0.02 g of MXene is added to deionized water, and stirred under ultrasonic action for 50 min to obtain a MXene dispersion liquid with a mass percentage of 0.10%; ZnFe2O4 is directly added to the above MXene dispersion liquid, so that the mass ratio of ZnFe2O4 to MXene is 1:0.1, and after ultrasonic for 8 h, stirring for 12 h, the precipitate is taken by centrifugation, and vacuum dried at 60℃ to obtain ZnFe2O4 / MXene; take 40 mg of ZnFe2O4 / MXene and add it to 8 mL of 0.1 mol / L Zn(NO3)2·6H2O solution, stir for 30 min to make it fully mixed; then add 16 mL of 0.2 mol / L NaOH solution dropwise, and react at 60℃ for 6 h. After the reaction is completed, it is washed with deionized water and ethanol alternately for 3 times, and vacuum dried at 60℃ to obtain a photocatalyst ZnFe2O4 / MXene / ZnO; 35 mg of ZnFe2O4 / MXene / ZnO is added to 2 g of a collagen fiber dispersion liquid with a solid content of 3%, and stirred to make them fully mixed, and freeze-dried to obtain an aerogel substrate; a 0.12 mol / L zinc precursor solution is prepared with Zn(NO3)2·6H2O as zinc source and ethanol as solvent, the aerogel substrate is placed in the precursor solution, soaked at room temperature for 12 h, and then placed in a 0.72 mol / L NaOH / ethanol solution, the volume ratio of zinc precursor solution to NaOH / ethanol solution is 1:2, and the reaction is carried out at 50℃ for 6 h. Then the aerogel is taken out after being placed in n-hexane and ethanol for 1 h respectively, and naturally dried at room temperature to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0041] Example 2
[0042] Take 0.595 g Zn(NO3)2·6H2O and 1.112 g FeSO4·7H2O, dissolve in 50 mL of ethylene glycol to obtain a precursor solution. The above precursor solution is placed in a polytetrafluoroethylene reaction kettle and hydrothermally reacted at 180°C for 18h. After the reaction is completed, it is naturally cooled to room temperature, washed with deionized water and anhydrous ethanol alternately for 3 times, vacuum dried at 60°C and ground to obtain ZnFe2O4 powder; 0.01 g of MXene is added to deionized water, and stirred under ultrasonic action for 50 min to obtain a 0.05% mass percentage concentration of MXene dispersion; ZnFe2O4 is directly added to the above MXene dispersion, so that the mass ratio of ZnFe2O4 to MXene is 1:0.05, and after ultrasonic for 6h, stirring for 14h, centrifugation is taken to precipitate, and vacuum drying at 60°C obtains ZnFe2O4 / MXene; take 35 mg of ZnFe2O4 / MXene and add it to 8 mL of 0.05 mol / L Zn(NO3)2·6H2O solution, stir for 30 min to mix thoroughly; then add 16 mL of 0.1 mol / L NaOH solution dropwise, and react at 60°C for 4h. After the reaction is completed, it is washed with deionized water and ethanol alternately for 4 times, and vacuum dried at 60°C to obtain a photocatalyst ZnFe2O4 / MXene / ZnO; 35 mg of ZnFe2O4 / MXene / ZnO is added to 2 g of a collagen fiber dispersion solution with a solid content of 2%, and stirred to mix thoroughly, and freeze-dried to obtain an aerogel substrate; a 0.05 mol / L zinc precursor solution is prepared with Zn(NO3)2·6H2O as zinc source and ethanol as solvent, and the aerogel substrate is placed in the precursor solution, soaked at room temperature for 12h, and then placed in a 0.10 mol / L NaOH / ethanol solution, the volume ratio of zinc precursor solution to NaOH / ethanol solution is 1:2, and the reaction is carried out at 40°C for 6h. Then the aerogel is taken out after being placed in n-hexane and ethanol for 1h respectively, and naturally dried at room temperature to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0043] Example 3
[0044] Take 0.595 g Zn(NO3)2·6H2O and 1.112 g FeSO4·7H2O, dissolve in a mixed solution of 15 mL ethylene glycol and 5 mL deionized water, then add 0.54 g oxalic acid, stir and mix uniformly. Put the above precursor solution in a polytetrafluoroethylene reaction kettle and hydrothermal reaction at 200℃ for 16h. After the reaction is completed, it is naturally cooled to room temperature, washed with deionized water and anhydrous ethanol alternately for 3 times, vacuum dried at 60℃ and ground to obtain ZnFe2O4 powder; 0.002 g MXene is added to deionized water, stirred for 50 min under ultrasonic action to obtain a MXene dispersion solution with a mass percentage of 0.01%; ZnFe2O4 is directly added to the above MXene dispersion solution, so that the mass ratio of ZnFe2O4 to MXene is 1:0.01, and after ultrasonic for 4h, stirring for 16h, the precipitate is centrifuged and vacuum dried at 60℃ to obtain ZnFe2O4 / MXene; take 50 mg of ZnFe2O4 / MXene and add it to 8 mL of 0.08 mol / L Zn(NO3)2·6H2O solution, stir for 30 min to mix thoroughly; then add 16 mL of 0.32 mol / L NaOH solution dropwise, and react at 60℃ for 6h. After the reaction is completed, it is washed with deionized water and ethanol alternately for 5 times, and vacuum dried at 60℃ to obtain a photocatalyst ZnFe2O4 / MXene / ZnO; 10 mg of ZnFe2O4 / MXene / ZnO is added to 2 g of a collagen fiber dispersion solution with a solid content of 1%, and the two are stirred to mix thoroughly, and freeze-dried to obtain an aerogel substrate; a 0.08 mol / L zinc precursor solution is prepared with Zn(NO3)2·6H2O as zinc source and ethanol as solvent, and the aerogel substrate is placed in the precursor solution, soaked at room temperature for 12h, then placed in a 0.16 mol / L NaOH / ethanol solution, the volume ratio of zinc precursor solution to NaOH / ethanol solution is 1:2, and the reaction is carried out at 50℃ for 6h. Then the aerogel is taken out after being placed in n-hexane and ethanol for 1h respectively, and naturally dried at room temperature to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0045] Example 4
[0046] Zn(NO3)2·6H2O and 1.112 g of FeSO4·7H2O were weighed out and dissolved in 25 mL of deionized water, and after complete dissolution, 0.6 g of urea was added and stirred and mixed uniformly. The above precursor solution was placed in a polytetrafluoroethylene reaction kettle and hydrothermally reacted at 220°C for 12 h. After the reaction was completed, it was naturally cooled to room temperature, washed with deionized water and anhydrous ethanol alternately for 3 times, vacuum dried at 60°C and ground to obtain ZnFe2O4 powder; 0.03 g of MXene was added to deionized water, and stirred for 50 min under ultrasonic action to obtain a MXene dispersion liquid with a mass percentage concentration of 0.15%; ZnFe2O4 was directly added to the above MXene dispersion liquid, so that the mass ratio of ZnFe2O4 to MXene was 1:0.15, and after ultrasonic action for 7 h and stirring for 13 h, the precipitate was centrifuged and vacuum dried at 60°C to obtain ZnFe2O4 / MXene; 20 mg of ZnFe2O4 / MXene was weighed out and added to 8 mL of 0.01 mol / L Zn(NO3)2·6H2O solution, and stirred for 30 min to mix thoroughly; then 16 mL of 0.02 mol / L NaOH solution was added dropwise, and reacted at 60°C for 6 h; after the reaction was completed, it was washed with water and ethanol alternately for 3 times, centrifuged to collect the precipitate, and vacuum dried at 60°C to obtain ZnFe2O4 / MXene / ZnO. 20 mg of photocatalyst ZMZ was added to 2 g of collagen fiber dispersion liquid with a solid content of 2%, and stirred to mix thoroughly, and an aerogel substrate was prepared by freeze-drying; a 0.01 mol / L zinc precursor solution was prepared with Zn(NO3)2·6H2O as the zinc source and ethanol as the solvent, and the aerogel substrate was placed in the precursor solution and soaked at room temperature overnight, then placed in a 0.04 mol / L NaOH / ethanol solution, the volume ratio of zinc precursor solution to NaOH / ethanol solution was 1:2, and the reaction was carried out at 40°C for 6 h. Subsequently, the aerogel was taken out after being placed in n-hexane and ethanol for 1 h each time, and naturally dried at room temperature to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0047] Example 5
[0048] Take 0.892 g Zn(NO3)2·6H2O and 1.668 g FeSO4·7H2O, dissolve in 50 mL of deionized water; then add 0.0056 g of NH4F and 0.60 g of urea, and stir until uniform. Place the above precursor solution in a polytetrafluoroethylene reaction kettle and hydrothermally react at 210°C for 20 h. After the reaction is completed, naturally cool to room temperature, wash with deionized water and anhydrous ethanol alternately for 4 times, vacuum dry at 60°C, and grind to obtain ZnFe2O4 powder; add 0.04 g of MXene to deionized water, stir for 50 min under ultrasonic action to obtain a 0.2% mass percentage MXene dispersion; add ZnFe2O4 directly to the above MXene dispersion, so that the mass ratio of ZnFe2O4 to MXene is 1:0.2, stir for 12 h after ultrasonic action for 8 h, centrifuge to obtain the precipitate, and vacuum dry at 60°C to obtain ZnFe2O4 / MXene; take 60 mg of ZnFe2O4 / MXene and add to 8 mL of 0.12 mol / L Zn(NO3)2·6H2O solution, stir for 30 min to mix thoroughly; then add 16 mL of 0.48 mol / L NaOH solution, wash with water and ethanol alternately for 3 times after the reaction is completed, centrifuge to obtain the precipitate, and vacuum dry at 60°C to obtain ZnFe2O4 / MXene / ZnO. Add 60 mg of ZnFe2O4 / MXene / ZnO to 2 g of a collagen fiber dispersion solution with a solid content of 3%, stir to mix thoroughly, and freeze-dry to obtain an aerogel substrate; prepare a 0.10 mol / L zinc precursor solution with Zn(NO3)2·6H2O as the zinc source and ethanol as the solvent, place the aerogel substrate in the precursor solution, soak at room temperature for 12 h, then place in a 0.20 mol / L NaOH / ethanol solution, the volume ratio of the zinc precursor solution to the NaOH / ethanol solution is 1:2, and react at 50°C for 6 h. Then take out the aerogel after placing it in n-hexane and ethanol for 1 h each, and naturally dry at room temperature to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
[0049] Comparative Example 1
[0050] Take 0.595 g Zn(NO3)2·6H2O and 1.112 g FeSO4·7H2O, dissolve in 40 mL of deionized water; then add NaOH to make the pH value of the system 13 to obtain a precursor solution. Place the above precursor solution in a polytetrafluoroethylene reaction kettle and hydrothermally react at 190°C for 24 h. After the reaction is completed, naturally cool to room temperature, wash with deionized water and anhydrous ethanol alternately for 4 times, vacuum dry at 60°C, and grind to obtain ZnFe2O4 powder.
[0051] Through specific implementations of Examples 1-5 and Comparative Example 1, this invention verifies the significant advantages of the magnetic ZnFe2O4 / MXene / ZnO / collagen aerogel in the treatment of organic wastewater.
[0052] Structural controllability and its advantages: Figure 1 Images (a)-(e) sequentially show scanning electron microscope (SEM) images of the ZnFe₂O₄ materials prepared in Examples 1 to 5. The experimental results show that precise control of the material morphology was successfully achieved by changing the solvent, the type of structure-directing agent, and the hydrothermal synthesis parameters (temperature / time). Specifically, the ZnFe₂O₄ in Example 1 exhibits an octahedral morphology (a), the ZnFe₂O₄ in Example 2 is a nanosphere aggregate (b), the ZnFe₂O₄ in Example 3 has a micron-sized rod-like structure (c), the ZnFe₂O₄ in Example 4 has an irregular octahedral morphology (d), and the ZnFe₂O₄ in Example 5 forms a polyhedral structure (e). This multi-dimensional morphology control mechanism indicates that by systematically controlling the synthesis conditions, the microstructure of the product can be effectively controlled, thereby optimizing the specific surface area and surface active site distribution of the material, ultimately achieving a synergistic improvement in light absorption capacity and catalytic performance.
[0053] Highly efficient adsorption and degradation performance: Figure 2 To show the adsorption and degradation curves of tetracycline hydrochloride in Comparative Example 1, the adsorption of tetracycline hydrochloride reached a basic equilibrium at 30 minutes, with an adsorption rate of approximately 29%, and the degradation rate of tetracycline hydrochloride was 83.7% at 140 minutes. Figure 3 The adsorption curve of tetracycline hydrochloride in Example 1 shows that the adsorption of tetracycline hydrochloride reached equilibrium within 60 minutes, and its adsorption rate was 2 to 3 times that of the control example. Figure 4 The degradation curve of tetracycline hydrochloride in Example 1 shows that the removal rate of tetracycline hydrochloride reached 82.9% within 10 minutes and 87.9% within 60 minutes, achieving the effect of Comparative Example 1 at 140 minutes. This indicates that the collagen aerogel fully exerts its enrichment effect and can accelerate the degradation efficiency of pollutants by the photocatalyst.
[0054] Magnetic recycling and reuse: Figure 5 This is a schematic diagram of magnetic recovery in Example 5. Studies show that, in practical applications, besides being separated by conventional filtration methods, the material's unique magnetic properties facilitate efficient recovery using magnetic separation technology. This magnetic response characteristic effectively overcomes the technical bottleneck of difficult solid-liquid separation in traditional photocatalysts, significantly reducing operating costs and improving treatment efficiency. Particularly in industrial treatment scenarios such as dyeing and printing wastewater and medical wastewater, the magnetically controlled recovery advantages exhibited by this material provide an innovative solution for achieving continuous and large-scale water treatment applications.
[0055] Low cost and environmental protection: low-temperature hydrothermal method is used to prepare green, non-toxic and partially visible light absorbing ZnO. On this basis, visible light absorbing magnetic ZnFe2O4 and cocatalyst MXene are introduced to form a heterojunction structure between the three, thereby improving the light absorption capacity of the material, reducing the recombination rate of its electron-hole, and realizing the high catalytic activity of the photocatalyst under visible light. In addition, chromium-containing waste leather scraps are treated by acid method to obtain collagen fibers, which are processed to prepare aerogel adsorption materials; further, the prepared photocatalyst is introduced into the aerogel to prepare a recyclable collagen-based aerogel. The "enrichment effect" of collagen aerogel accelerates the photocatalytic degradation rate of photocatalyst, realizing the construction of an integrated adsorption and degradation system for rapid removal of tetracycline hydrochloride.
Claims
1. A ZnFe2O4 / MXene / ZnO / collagen aerogel composite material, characterized in that: The magnetic ZnFe2O4 nanoparticles, two-dimensional material MXene, ZnO and porous collagen aerogel network are composed; the mass ratio of ZnFe2O4 and MXene is 1:(0.01-0.2), the porous collagen aerogel network is prepared by freeze drying of a collagen dispersion liquid, the solid content of the collagen dispersion liquid is 1%-3%, and the mass ratio of ZnFe2O4 / MXene / ZnO and the collagen dispersion liquid is (0.01-0.03):1; after freeze drying, ZnFe2O4 / MXene / ZnO is loaded in the pores of the collagen aerogel to form a three-dimensional porous composite system.
2. The ZnFe204 / MXene / ZnO / collagen aerogel composite material according to claim 1, characterized in that, The morphology of the ZnFe2O4 is one of an octahedron, nanosphere, microrod or polyhedron.
3. A method for preparing the ZnFe2O4 / MXene / ZnO / collagen aerogel composite material according to any one of claims 1-2, characterized by, The method comprises the following steps: (1) iron source and zinc source are added into a solvent in a molar ratio of 2:1, after stirring and dissolving, a structure directing agent is added to obtain a precursor solution, and ZnFe2O4 powder is prepared after hydrothermal reaction, cooling, washing, drying and grinding; (2) MXene is dispersed in deionized water to form a dispersion liquid, and ZnFe2O4 powder is added, and ZnFe2O4 / MXene is prepared after ultrasonic treatment, stirring, centrifugation and drying; (3) ZnFe2O4 / MXene is added into a zinc precursor solution, NaOH solution is added after stirring, and the mixture is reacted at 50-90 DEG C for 4-8 h, and ZnFe2O4 / MXene / ZnO is prepared after washing and drying; (4) ZnFe2O4 / MXene / ZnO is added into a collagen fiber dispersion liquid, and the mixture is stirred and freeze-dried to obtain an aerogel base; (5) the aerogel base is soaked in a zinc precursor solution, and after soaking at room temperature for 12 h, the mixture is placed in a NaOH / ethanol solution and reacted at 40-60 DEG C, and after treatment with n-hexane and ethanol, the mixture is dried to obtain ZnFe2O4 / MXene / ZnO / collagen aerogel.
4. The production method according to claim 3, characterized by, In step (1), the concentration of the iron source is 0.06-0.20 mol / L, the concentration of the zinc source is 0.03-0.10 mol / L, the hydrothermal reaction temperature is 180-220 DEG C, and the reaction time is 12-24 h.
5. The production method according to claim 4, characterized by, In step (2), the mass percentage concentration of the MXene dispersion liquid is 0.01%-0.2%, the mass ratio of ZnFe2O4 and MXene is 1:(0.01-0.2), the ultrasonic treatment time is 4-8 h, and the stirring time is 12-16 h.
6. The production method according to claim 5, wherein In step (3), the zinc precursor is zinc nitrate or zinc acetate, and the concentration is 0.01-0.12 mol / L, and the concentration of the NaOH solution is 0.02-0.48 mol / L.
7. The production method according to claim 6, characterized by, In step (4), the solid content of the collagen fiber dispersion liquid is 1%-3%, and the collagen fiber dispersion liquid is prepared by chromium removal treatment of chromium-containing waste leather shavings with oxalic acid / sulfuric acid mixed solution.
8. The preparation method according to claim 7, characterized in that, In step (5), the concentration of the zinc precursor is 0.02-0.12 mol / L, and the concentration of the NaOH / ethanol solution is 0.04-0.72 mol / L.
9. The preparation method according to claim 7, characterized in that, The iron source is FeSO4·7H2O, the zinc source is Zn(NO3)2·6H2O, and the structure directing agent is one of NaOH, urea, and a mixture of urea / ammonium fluoride.
10. Use of the ZnFe2O4 / MXene / ZnO / collagen aerogel composite material according to any one of claims 1 to 2 in the treatment of medical wastewater, characterized in that: The application discloses a composite material for degrading organic pollutants in medical wastewater under visible light irradiation by utilizing the magnetic recovery property and adsorption-photocatalysis coupling effect of the composite material.