Chemical-photothermal synergistic antibacterial composite hydrogel evaporator and preparation thereof

Abstract

The present application belongs to the field of seawater desalination, and particularly relates to a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function and preparation thereof. In view of the problems such as marine biological pollution in the seawater evaporation process of the existing hydrogel evaporator, the present application homogenizes and composites high-entropy alloy nanoparticles and hydrogel, the molecular weight of the hydrogel ranges from 10000 to 100000, the mass ratio of the hydrogel matrix to the high-entropy alloy nanoparticles is 100:(1-10), and the physical cross-linking solidification is carried out at-50 DEG C to 0 DEG C for 6h-24h to obtain the composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function. When the composite hydrogel evaporator is used for seawater desalination, it has photothermal antibacterial capacity and can resist microbial pollution in seawater.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of seawater desalination, and particularly relates to a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function and preparation thereof. BACKGROUND

[0002] The seawater desalination technologies in use can be divided into three categories: thermal distillation and membrane permeation technologies relying on fossil energy; novel distillation technologies relying on green energy such as wind energy and geothermal energy; and seawater desalination technologies driven by solar energy. Among them, the seawater desalination technologies driven by solar energy have become a research hotspot due to their small centralized requirement, no carbon dioxide emission, wide source and low cost. The photothermal interfacial evaporation technology derived to improve the solar energy utilization efficiency and seawater desalination rate has become a relatively mature seawater desalination method. Photothermal interfacial evaporation is carried out by light absorption on the water surface, and heating and evaporation are only carried out at the gas-liquid interface, so that the light-heat conversion efficiency is improved from 40%-50% to more than 90%, providing an effective solution to the shortage of fresh water resources.

[0003] The photothermal interfacial evaporator based on hydrogel can realize high solar energy absorption, efficient light-heat conversion, heat localization, rapid water transportation and water activation under natural light, and is an ideal porous structure evaporator. In actual application, the hydrogel evaporator will be in contact with sewage and seawater in a large area, and a large number of microorganisms (such as bacteria) usually exist in these waters. Bacteria and other microorganisms can adhere, accumulate and colonize on various surfaces of different materials, and heterogeneous porous materials are the first choice for microorganism adsorption and parasitism. After the evaporator is in contact with sewage, the rapid adsorption and reproduction of microorganisms will change the original structure of the evaporator and induce the formation of biofilm on the evaporator, resulting in blockage of water transportation channels, reduction of evaporation efficiency, instability of performance, and even degradation of photothermal materials, ultimately leading to failure of the evaporator. Therefore, it is an urgent need in the practical application of solar evaporation technology to develop a porous hydrogel evaporator with high light-heat conversion efficiency, high seawater desalination rate and anti-fouling property. SUMMARY

[0004] In view of the existing main technical problems, the present application provides a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function and a preparation method thereof. The core purpose is to directly endow the photothermal material with the ability to resist microbial corrosion through a simple process, and to prepare a composite hydrogel evaporator with high light-heat conversion efficiency, high seawater desalination rate and anti-fouling property in an efficient and convenient manner, so as to overcome the limitations of large-scale application of photothermal interfacial water evaporator.

[0005] High-entropy alloy is an alloy formed by five or more than five equal or approximately equal metals. Due to the controllability of the component structure, through reasonable element design and particle size control, full-waveband high-efficiency light absorption can be realized in the spectral range of 300nm-2500nm. On the premise of not affecting the light absorption performance, if antibacterial elements (such as Cu, Ag, etc.) are introduced at the same time, a light-heat conversion material with integrated function can be prepared, which integrates efficient light-heat conversion and chemical element antibacterial function. This design scheme will help to overcome the limitation of traditional light-heat conversion materials in solar spectrum absorption, and innovatively realize the integration of light-heat and sterilization capacity, which will show great application potential in the field of requiring fast light response, excellent light-heat conversion and sterile environment.

[0006] The composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function provided by the application has a hierarchical porous structure and is composed of high-entropy alloy nanoparticles and hydrogel. The high-entropy alloy nanoparticles are composed of equal-molar Fe, Ni, Ti, Cr, Mn and Cu elements and have a particle size of 40nm-100nm and are uniformly dispersed in the hydrogel. The hydrogel is mainly composed of cross-linked polyvinyl alcohol (PVA). The mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the raw material of the composite hydrogel evaporator is 100:(1-10), and the molecular weight of polyvinyl alcohol ranges from 10000 to 100000. When the composite hydrogel evaporator is used for seawater desalination, it has photothermal antibacterial capacity and can resist microbial pollution in seawater.

[0007] The preparation method of the composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function provided by the application comprises the following steps:

[0008] Step 1: preparing high-entropy alloy nanoparticles composed of equal-molar Fe, Ni, Ti, Cr, Mn and Cu elements;

[0009] Step 2: dissolving polyvinyl alcohol in a mixed solution of water and an organic solvent, adding high-entropy alloy nanoparticles and uniformly mixing to obtain a precursor solution;

[0010] Step 3: obtaining an initial high-entropy alloy hydrogel polymer after physical cross-linking and solidification of the precursor solution;

[0011] Step 4: removing the organic solvent in the initial high-entropy alloy hydrogel polymer to obtain a high-entropy alloy hydrogel polymer, i.e. a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function.

[0012] In step 1, the preparation method of high-entropy alloy nanoparticles comprises the following steps:

[0013] Step 1-1: Take the initial raw material of equimolar ratio of iron (Fe), nickel (Ni), titanium (Ti), chromium (Cr), manganese (Mn) and copper (Cu) metal powder with high purity (≥99.9%) as the starting material, take anhydrous ethanol as the process control agent, and use mechanical alloying technology to carry out ball milling treatment to obtain high-entropy alloy microchips; then the high-entropy alloy microchips are processed into a cylindrical preform through cold pressing forming process; the particle size of the initial raw material is 45-100 μm.

[0014] Step 1-2: Place the preform in a vacuum arc melting furnace, and introduce a mixed gas of hydrogen (H2) and argon (Ar) as plasma medium into the reaction cavity under vacuum environment for arc discharge treatment, and obtain high-entropy alloy nanoparticles after passivation of the product obtained by arc discharge treatment.

[0015] The vacuum degree of the vacuum environment is ≤5×10 -3 Pa, an oxygen-free environment is established; the volume ratio of hydrogen to argon in the mixed gas is 4:1.

[0016] The arc discharge time is 5-30 min, the voltage is 66 V, the current is 180-250 A, and the cooling substrate temperature is 7-10 ℃ to maintain the non-equilibrium solidification condition; the high-entropy alloy microchips are melted and transformed into nanoparticles by nucleation growth through melting;

[0017] Passivation refers to exposing the product obtained by arc discharge treatment in air for 6-12 h to form an oxide film on the surface to stabilize the surface properties, and finally obtaining high-entropy alloy nanoparticles with a particle size range of 40-100 nm; after passivation, the air is isolated and sealed for storage.

[0018] In the precursor solution of step 2: the mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles is 100:(1-10); the mass ratio of the total mass of organic solvent and water to the mass of polyvinyl alcohol is 100:(10-80); the mass ratio of organic solvent to water is 100:(1-10); the molecular weight of polyvinyl alcohol is 10,000-100,000; the organic solvent is dimethyl sulfoxide (DMSO);

[0019] In step 2, the polyvinyl alcohol dissolving temperature is 50-120 ℃, so that the polyvinyl alcohol is fully stretched and completely dissolved; after adding the high-entropy alloy nanoparticles, continue to stir for 1-5 h, and then obtain the precursor solution after mixing uniformly.

[0020] In step 3, the physical crosslinking and curing temperature is -50-0 ℃, and the reaction time is 6-24 h, so that the polyvinyl alcohol is physically crosslinked and cured to form a solid gel.

[0021] In step 4, the initial high-entropy alloy hydrogel polymer is immersed in deionized water at 15-30 DEG C for 1-12 hours until the organic solvent is completely replaced by deionized water immersion, and a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function is obtained, which is stored in deionized water for standby.

[0022] The present application realizes a novel integrated photothermal conversion material integrating high-efficiency photothermal conversion and synergistic antibiosis by precisely selecting high-entropy alloy composition elements to make the 3d energy bands of different elements near the Fermi level, and constructs a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function with a hydrogel, the high-strength hydrogel evaporator has a solar absorption rate of 97.2%, and the killing rate of gram-positive bacteria and gram-negative bacteria under illumination is more than 99%, and the water evaporation rate reaches 2.4 kg·m -2 -1 The present application provides a new idea and technical approach for the research and development of photothermal interface hydrogel evaporators.

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] Compared with adding elemental metal particles, the composite hydrogel evaporator after adding high-entropy alloy nanoparticles has excellent performance in absorbance, antibacterial efficiency and material stability. 1. Absorbance: the high-entropy alloy nanoparticles enhance the light absorption capacity through multi-element synergistic effect. Its unique lattice distortion and interband transition effect (d-d interband absorption) significantly widens the absorption range of the solar spectrum, thereby improving the photothermal conversion efficiency, while the absorption spectrum of elemental metal particles is usually narrow (such as Cu only has strong absorption for visible light), and lacks the ability of multi-element synergistic band regulation, resulting in low photothermal efficiency and weak photothermal response. Therefore, the water evaporation rate of the evaporator with high-entropy alloy nanoparticles is higher. 2. Antibacterial efficiency: photothermal heating not only directly destroys the structure of bacteria, but also inhibits bacterial metabolism through heat shock effect, and enhances the diffusion efficiency of copper ions and the generation efficiency of ROS. While the antibacterial ability of elemental particles is limited to a single chemical or physical mechanism. Therefore, the antibacterial effect of the evaporator with high-entropy alloy nanoparticles is better. 3. Material stability and long-term effectiveness: the high-entropy effect (high configuration entropy) of high-entropy alloy nanoparticles inhibits element phase separation and oxidation tendency, ensuring the structural stability of the nanoparticles in long-term use, while elemental particles may cause performance degradation due to oxidation or agglomeration.

[0025] ​The present application has different characteristics of metal elements, and the high-entropy alloy is prepared by compounding, so that the high-entropy alloy has higher light-heat conversion performance than traditional materials, and the antibacterial element is introduced to realize the innovative and stable integration of the light-heat performance and the antibacterial performance of the material. The high-entropy alloy nanoparticles provided by the present application have good compatibility with the hydrogel matrix and can be uniformly distributed in the hydrogel matrix; at the same time, the high-entropy alloy nanoparticles do not react with the hydrogel components and have physical and chemical stability. The composite hydrogel evaporator provided by the present application has excellent water evaporation capacity and good stability to meet the application requirements under complex conditions.

[0026] The present application selects a hydrogel as the matrix material of the evaporator to obtain hydrophilicity and porosity, accelerates water transmission, introduces an antibacterial element into a hydrophilic light-heat high-entropy alloy that has been fully designed to realize d-d orbital transition, realizes the stable integration of the light-heat material and the antibacterial material, the high-entropy alloy uniformly dispersed in the hydrogel matrix maintains physical and chemical stability, expands the use scenarios of the hydrogel evaporator, and the hydrophilicity of the high-entropy alloy nanoparticles and the hydrogel is superimposed to accelerate the water evaporation speed. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is an image of the high-entropy alloy nanoparticles prepared in Example 3 of the present application under the assistance of scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS);

[0028] Figure 2 is an X-ray photoelectron spectroscopy (XPS) graph of the high-entropy alloy nanoparticles prepared in Example 3 of the present application;

[0029] Figure 3 is an X-ray diffraction (XRD) graph of the high-entropy alloy nanoparticles prepared in Example 3 of the present application;

[0030] Figure 4 is an X-ray diffraction (XRD) graph of the sample; wherein, HEA is the high-entropy alloy nanoparticles prepared in Example 3, HEA-PVA is the composite hydrogel evaporator prepared in Example 3, and PVA is the hydrogel evaporator prepared in Comparative Example 1;

[0031] Figure 5 is an absorption spectrum curve graph of the sample; wherein, HEA is the high-entropy alloy nanoparticles prepared in Example 3, HEA-PVA is the composite hydrogel evaporator prepared in Example 3, and PVA is the hydrogel evaporator prepared in Comparative Example 1;

[0032] Figure 6is a water evaporation weight loss curve diagram of the sample; wherein, HEA-PVA is a composite hydrogel evaporator prepared in Example 3, and PVA is a hydrogel evaporator prepared in Comparative Example 1;

[0033] Figure 7 is an anti-pseudomonas aeruginosa effect diagram of the sample; wherein, (a) is a hydrogel evaporator prepared in Comparative Example 1, (b) is a composite hydrogel evaporator prepared in Example 3, and (c) is the composite hydrogel evaporator prepared in Example 3 after being irradiated by sunlight.

[0034] Figure 8 is an anti-bacillus vietnamensis effect diagram of the sample; wherein, (a) is a hydrogel evaporator prepared in Comparative Example 1, (b) is a composite hydrogel evaporator prepared in Example 3, and (c) is the composite hydrogel evaporator prepared in Example 3 after being irradiated by sunlight. DETAILED DESCRIPTION

[0035] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below in combination with the drawings and preferred embodiments.

[0036] The experimental methods not specified in the specific conditions are usually according to the conventional conditions, such as the conditions described in the textbooks and experimental guidelines, or the conditions recommended by the manufacturers, which are well known or easily obtained by the ordinary skilled in the art. The following examples are only preferred embodiments of the present application, and do not limit the present application. The present application can have various modifications and changes for the skilled in the art, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0037] The present application is further illustrated below in combination with specific embodiments and drawings.

[0038] Example 1

[0039] The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles composed of equal molar ratios of Fe, Ni, Ti, Cr, Mn and Cu elements and polyvinyl alcohol hydrogel. The mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the evaporator raw material is 100:6.7, and the molecular weight of polyvinyl alcohol is 10000.

[0040] The preparation method of the composite hydrogel evaporator is as follows:

[0041] Step 1: Preparation of high-entropy alloy nanoparticles, the specific steps are as follows:

[0042] Step 1-1: Fe, Ni, Ti, Cr, Mn and Cu metal powders with purity not less than 99.9% are used as raw materials, and the particle size of the raw materials is about 80 μm. The above-mentioned metal powders are proportioned according to equal molar ratio, and high-entropy alloy microchips are prepared by mechanical alloying technology in a full-range planetary ball mill with anhydrous ethanol as a process aid under the condition of 350 rpm rotation speed, and the ball-to-material ratio is 10:1. Subsequently, the high-entropy alloy microchips are punched into a cylindrical preform with a diameter of Φ10 mm and a height of 5 mm.

[0043] Step 1-2: After creating an oxygen-free environment in a vacuum arc furnace, the cylindrical preform high-entropy alloy microchips are placed in the vacuum chamber of the arc furnace for arc discharge treatment. When the vacuum degree is reduced to 5×10 -3 Pa, the reaction gas H2 and Ar are introduced into the furnace cavity at a volume ratio of 4:1, the reaction voltage is adjusted to 66 V, the reaction current is 230 A, the arc discharge process lasts for 30 min, and the high-entropy alloy microchips are converted into nanoparticles by melting; the temperature of the cooling substrate is set to 10℃, thereby constructing a non-equilibrium synthesis environment to promote the nucleation growth of the high-entropy alloy and form nanoparticles. After the above steps are completed, passivation treatment is carried out, and the product obtained by arc discharge treatment is exposed to air for 6 h to form an oxide film on the surface to stabilize the surface properties, and at the same time, the nanoparticles are allowed to settle and then collected, and finally the high-entropy alloy nanoparticles with a particle size of 40 nm are successfully obtained.

[0044] Step 2: 0.15 g of polyvinyl alcohol with a molecular weight of 10000 is dissolved in a mixed solution of 0.1 g of water and 1 g of dimethyl sulfoxide, the temperature is heated to 90℃ and magnetic stirring is carried out, 0.01 g of high-entropy alloy nanoparticles is added after the polyvinyl alcohol is completely dissolved, and the stirring is continued for 1 h, and the mixed solution is uniformly mixed to obtain a precursor solution.

[0045] Step 3: The uniformly mixed precursor solution is injected into a self-made polytetrafluoroethylene mold at a high temperature of 90℃, and the mold is transferred to a low temperature environment of -50℃, so that the polyvinyl alcohol is physically crosslinked to form a solid gel. The low-temperature polymerization time is 6 h. After the reaction is completed, the solid gel is demolded and taken out to obtain an initial high-entropy alloy hydrogel polymer.

[0046] Step 4: The initial high-entropy alloy hydrogel polymer is immersed in deionized water at room temperature of 15℃ for 1 h, and the organic solvent is completely replaced by deionized water to obtain a high-entropy alloy hydrogel polymer, that is, a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function; and is placed in deionized water for storage.

[0047] Example 2

[0048] The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles composed of equal molar ratios of Fe, Ni, Ti, Cr, Mn and Cu elements and polyvinyl alcohol hydrogel, and the mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the raw material of the evaporator is 100:5, and the molecular weight of polyvinyl alcohol is 20000.

[0049] The preparation method of the composite hydrogel evaporator is as follows:

[0050] Step 1: preparation of high-entropy alloy nanoparticles, the specific steps are as follows:

[0051] Step 1-1: taking Fe, Ni, Ti, Cr, Mn and Cu metal powders with a purity of not less than 99.9% as raw materials, the particle size of the raw materials is about 50μm. The above-mentioned metal powders are proportioned according to equal molar ratio, and high-entropy alloy microsheets are prepared by mechanical alloying technology in a full-range planetary ball mill with anhydrous ethanol as a process aid under the condition of 350rpm rotation speed, and the ball-to-material ratio is 10:1. Then the high-entropy alloy microsheets are punched into Φ10mm×5mm cylindrical preforms.

[0052] Step 1-2: after creating an oxygen-free environment in a vacuum arc furnace, the cylindrical preform high-entropy alloy microsheets are placed in the vacuum chamber of the arc furnace for arc discharge treatment. When the vacuum degree is reduced to 5×10 -3 Pa, the reaction gas H2 and Ar are introduced into the furnace cavity at a volume ratio of 4:1, the reaction voltage is adjusted to 66V, the reaction current is 200A, the arc discharge process lasts for 5min, and the high-entropy alloy microsheets are converted into nanoparticles by melting; the temperature of the cooling substrate is set at 7℃ to build a non-equilibrium synthesis environment to promote the nucleation growth of high-entropy alloy and form nanoparticles. After the above steps, passivation treatment is carried out, and the product obtained by arc discharge treatment is exposed to air for 12h to form an oxide film on the surface to stabilize the surface properties, and at the same time, the nanoparticles are allowed to settle and then collected, and finally the high-entropy alloy nanoparticles with a particle size of 70nm are successfully obtained.

[0053] Step 2: 0.4g of polyvinyl alcohol with a molecular weight of 20000 is dissolved in a mixed solution of 0.1g of water and 2g of dimethyl sulfoxide, the temperature is heated to 120℃ and magnetically stirred, 0.02g of high-entropy alloy nanoparticles is added after the polyvinyl alcohol is completely dissolved, and the stirring is continued for 5h, and then the precursor solution is obtained after mixing uniformly.

[0054] Step 3: the uniformly mixed precursor solution is injected into a self-made polytetrafluoroethylene mold at a high temperature of 120℃, and the mold is transferred to a low temperature environment of 0℃, so that the polyvinyl alcohol is physically crosslinked to form a solid gel, and the low temperature polymerization time is 24h. After the reaction is completed, the solid gel is demolded and taken out to obtain the initial high-entropy alloy hydrogel polymer.

[0055] Step 4: Submerge the initial high-entropy alloy hydrogel polymer in deionized water at room temperature of 30℃ for 12h to completely replace the organic solvent with deionized water, obtain the high-entropy alloy hydrogel polymer, i.e. the composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function; put it in deionized water for storage for standby.

[0056] Example 3

[0057] The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles composed of equal molar ratio of Fe, Ni, Ti, Cr, Mn and Cu elements and polyvinyl alcohol hydrogel. The mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the evaporator raw material is 100:2.5, and the molecular weight of polyvinyl alcohol is 20000.

[0058] The preparation method of the composite hydrogel evaporator is as follows:

[0059] Step 1: Prepare high-entropy alloy nanoparticles, the specific steps are as follows:

[0060] Step 1-1: Use Fe, Ni, Ti, Cr, Mn and Cu metal powders with purity not less than 99.9% as raw materials, and the particle size of the raw materials is about 45μm. The above-mentioned metal powders are proportioned according to equal molar ratio, and high-entropy alloy microsheets are prepared by mechanical alloying technology in a full-range planetary ball mill with anhydrous ethanol as a process aid at a rotation speed of 350rpm, and the ball-to-material ratio is 10:1. Then the high-entropy alloy microsheets are punched into Φ10mm×5mm cylindrical preforms.

[0061] Step 1-2: After creating an oxygen-free environment in a vacuum arc furnace, place the cylindrical preform high-entropy alloy microsheet in the vacuum chamber of the arc furnace for arc discharge treatment. When the vacuum degree is reduced to 5×10 -3 Pa, introduce reaction gases H2 and Ar into the furnace cavity at a volume ratio of 4:1, adjust the reaction voltage to 66V and the reaction current to 180A, and the arc discharge process lasts for 20min. By melting, the high-entropy alloy microsheet is converted into nanoparticles; the temperature of the cooling substrate is set at 8℃ to build a non-equilibrium synthesis environment to promote the nucleation growth of high-entropy alloy and form nanoparticles. After the above steps, perform passivation treatment, expose the product obtained by arc discharge treatment in air for 8h to form an oxide film on the surface to stabilize the surface properties, and then collect the settled nanoparticles to finally successfully obtain high-entropy alloy nanoparticles with a particle size of 60nm.

[0062] Step 2: 2 g of polyvinyl alcohol with a molecular weight of 20000 was dissolved in a mixed solution of 0.5 g of water and 8 g of dimethyl sulfoxide, the temperature was heated to 100°C and magnetic stirring was carried out, after the polyvinyl alcohol was completely dissolved, 0.05 g of high-entropy alloy nanoparticles was added, and the stirring was continued for 3 h until the mixture was uniformly mixed to obtain a precursor solution.

[0063] Step 3: The uniformly mixed precursor solution was injected into a self-made polytetrafluoroethylene mold at a high temperature of 100°C, and the mold was transferred to a low temperature environment of -30°C, so that the polyvinyl alcohol was physically crosslinked to form a solid gel, and the low temperature polymerization time was 12 h. After the reaction was completed, the solid gel was demolded and taken out to obtain an initial high-entropy alloy hydrogel polymer.

[0064] Step 4: The initial high-entropy alloy hydrogel polymer was immersed in deionized water at room temperature of 20°C for 6 h until the organic solvent was completely replaced by deionized water, and a high-entropy alloy hydrogel polymer was obtained, which was a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function; it was placed in deionized water for storage.

[0065] The high-entropy alloy nanoparticles synthesized by arc discharge melting are regular spherical structures, as shown in Figure 1 , each metal element is randomly and uniformly dispersed in the nanoparticles, and there is no element segregation and phase separation phenomenon. As shown in Figure 2 , the elemental composition of the high-entropy alloy nanoparticles contains Fe, Ni, Ti, Cr, Mn and Cu elements (C and O in Figure 2 are impurities inevitably introduced during the detection process). As shown in Figure 3 , three peaks are observed at 43.14°, 49.70° and 72.34°, corresponding to (111), (200) and (220) planes, respectively, which can be analyzed to be face-centered cubic structure. From Figure 4 , the peak shape and position of HEA-PVA, HEA and PVA in the figure can be known that the composite hydrogel evaporator prepared in Example 3 has successfully combined the high-entropy alloy nanoparticles in terms of crystal structure, and the combination of the hydrogel components and the high-entropy alloy nanoparticles will not damage the structures of the high-entropy alloy nanoparticles and the hydrogel components respectively.

[0066] Example 4

[0067] The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles composed of equimolar Fe, Ni, Ti, Cr, Mn and Cu elements and polyvinyl alcohol hydrogel, and the mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the evaporator raw material is 100:1, and the molecular weight of polyvinyl alcohol is 50000.

[0068] The preparation method of the composite hydrogel evaporator is as follows:

[0069] Step 1: Preparation of high-entropy alloy nanoparticles, the specific steps are as follows:

[0070] Step 1-1: Fe, Ni, Ti, Cr, Mn and Cu metal powders with a purity of not less than 99.9% are used as raw materials, and the particle size of the raw materials is about 90 μm. The above-mentioned metal powders are proportioned according to equal molar ratio, and high-entropy alloy microsheets are prepared by mechanical alloying technology in a full-range planetary ball mill with anhydrous ethanol as a process aid under the condition of 350 rpm rotation speed, and the ball-to-material ratio is 10:1. Subsequently, the high-entropy alloy microsheets are punched into Φ10 mm × 5 mm cylindrical preforms.

[0071] Step 1-2: After creating an oxygen-free environment in a vacuum arc furnace, the cylindrical preform high-entropy alloy microsheets are placed in the vacuum chamber of the arc furnace for arc discharge treatment. When the vacuum degree is reduced to 5 × 10 -3 Pa, the reaction gas H2 and Ar are introduced into the furnace cavity at a volume ratio of 4:1, the reaction voltage is adjusted to 66 V, the reaction current is 220 A, the arc discharge process lasts for 15 min, and the high-entropy alloy microsheets are converted into nanoparticles by melting; the temperature of the cooling substrate is set at 9℃ to build a non-equilibrium synthesis environment to promote the nucleation growth of high-entropy alloy and form nanoparticles. After the above steps are completed, passivation treatment is carried out, and the product obtained by arc discharge treatment is exposed to air for 9 h to form an oxide film on the surface to stabilize the surface properties, and at the same time, the nanoparticles are allowed to settle and then collected, and finally the high-entropy alloy nanoparticles with a particle size of 100 nm are successfully obtained.

[0072] Step 2: 3 g of polyvinyl alcohol with a molecular weight of 50000 is dissolved in a mixed solution of 0.7 g of water and 9 g of dimethyl sulfoxide, the temperature is heated to 80℃ and magnetic stirring is carried out, 0.03 g of high-entropy alloy nanoparticles is added after the polyvinyl alcohol is completely dissolved, and the stirring is continued for 2 h, and the mixture is uniformly mixed to obtain a precursor solution.

[0073] Step 3: The uniformly mixed precursor solution is injected into a self-made polytetrafluoroethylene mold at a high temperature of 80℃, and the mold is transferred to a low temperature environment of -20℃, so that the polyvinyl alcohol is physically crosslinked to form a solid gel. The low-temperature polymerization time is 15 h. After the reaction is completed, the solid gel is demolded and taken out to obtain an initial high-entropy alloy hydrogel polymer.

[0074] Step 4: The initial high-entropy alloy hydrogel polymer is immersed in deionized water at room temperature of 25℃ for 8 h until the organic solvent is completely replaced by deionized water, and a high-entropy alloy hydrogel polymer is obtained, which is a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function; it is placed in deionized water for storage.

[0075] Example 5

[0076] The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles composed of equal molar ratios of Fe, Ni, Ti, Cr, Mn and Cu elements and polyvinyl alcohol hydrogel, and the mass ratio of polyvinyl alcohol to high-entropy alloy nanoparticles in the evaporator raw material is 100:7, and the molecular weight of polyvinyl alcohol is 30000.

[0077] The preparation method of the composite hydrogel evaporator is as follows:

[0078] Step 1: Preparation of high-entropy alloy nanoparticles, the specific steps are as follows:

[0079] Step 1-1: The purity of Fe, Ni, Ti, Cr, Mn and Cu metal powder is not less than 99.9%, and the particle size of the raw material is about 90μm. The above-mentioned metal powder is proportioned according to equal molar ratio, and high-entropy alloy microfilm is prepared by mechanical alloying technology in a full-range planetary ball mill with anhydrous ethanol as a process aid under the condition of 350 rpm rotation speed, and the ball-to-material ratio is 10:1. Then the high-entropy alloy microfilm is punched into a cylindrical preform with a diameter of Φ10mm and a height of 5mm.

[0080] Step 1-2: After creating an oxygen-free environment in the vacuum arc furnace, the cylindrical preform high-entropy alloy microfilm is placed in the vacuum chamber of the arc furnace for arc discharge treatment. When the vacuum degree is reduced to 5×10 -3 Pa, the reaction gas H2 and Ar are introduced into the furnace cavity at a volume ratio of 4:1, the reaction voltage is adjusted to 66V, the reaction current is adjusted to 240A, the arc discharge process lasts for 25min, and the high-entropy alloy microfilm is converted into nanoparticles by melting; the temperature of the cooling substrate is set to 10℃, so as to build a non-equilibrium synthesis environment, promote the nucleation growth of high-entropy alloy and form nanoparticles. After the above steps are completed, passivation treatment is carried out, and the product obtained by arc discharge treatment is exposed to air for 10h to form an oxide film on the surface to stabilize the surface properties, and at the same time, the nanoparticles are settled and collected, and finally the high-entropy alloy nanoparticles with a particle size of 75nm are successfully obtained.

[0081] Step 2: 1g of polyvinyl alcohol with a molecular weight of 30000 is dissolved in a mixed solution of 0.4g of water and 8g of dimethyl sulfoxide, the temperature is heated to 110℃ and magnetically stirred, 0.07g of high-entropy alloy nanoparticles is added after the polyvinyl alcohol is completely dissolved, and the stirring is continued for 4h, and the precursor solution is obtained after mixing uniformly.

[0082] Step 3: The uniformly mixed precursor solution was injected into a self-made polytetrafluoroethylene mold at a high temperature of 110°C, and the mold was transferred to a low-temperature environment of -10°C to cause physical crosslinking of the polyvinyl alcohol to form a solid gel. The low-temperature polymerization time was 20 h. After the reaction was completed, the solid gel was removed from the mold to obtain the initial high-entropy alloy hydrogel polymer.

[0083] Step 4: The initial high-entropy alloy hydrogel polymer was immersed in deionized water at room temperature of 25°C for 9 h until the organic solvent was completely replaced by deionized water, obtaining a high-entropy alloy hydrogel polymer, i.e., a composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function. It was stored in deionized water for standby.

[0084] Comparative Example 1

[0085] The hydrogel evaporator does not contain high-entropy alloy nanoparticles, and the molecular weight of polyvinyl alcohol is 20000.

[0086] The specific preparation method of the hydrogel evaporator is as follows:

[0087] Step 1: High-entropy alloy nanoparticles were not prepared.

[0088] Step 2: 2 g of polyvinyl alcohol with a molecular weight of 20000 was dissolved in a mixed solution of 0.5 g of water and 8 g of dimethyl sulfoxide, heated to 100°C and magnetically stirred. After stirring for 3 h, the polyvinyl alcohol was completely dissolved to obtain a precursor solution.

[0089] Step 3: The precursor solution was injected into a self-made polytetrafluoroethylene mold at a high temperature of 100°C, and the mold was transferred to a low-temperature environment of -30°C to cause physical crosslinking of the polyvinyl alcohol to form a solid gel. The low-temperature polymerization time was 12 h. After the reaction was completed, the solid gel was removed from the mold to obtain the initial hydrogel polymer.

[0090] Step 4: The initial hydrogel polymer was immersed in deionized water at room temperature of 20°C for 6 h until the organic solvent was completely replaced by deionized water, obtaining a hydrogel polymer, i.e., a hydrogel evaporator. It was stored in deionized water for standby.

[0091] Comparative Example 2

[0092] The composite hydrogel evaporator does not contain high-entropy alloy nanoparticles, but is composed of equimolar Fe, Ni, Ti, Cr, Mn and Cu metal elemental powders and a polyvinyl alcohol hydrogel. The total mass ratio of polyvinyl alcohol to metal elemental powder in the evaporator raw material is 100:2.5, and the molecular weight of polyvinyl alcohol is 20000.

[0093] The specific preparation method of the composite hydrogel evaporator is as follows:

[0094] Step 1: Without preparing high-entropy alloy nanoparticles, weigh equal molar ratio of Fe, Ni, Ti, Cr, Mn, Cu metal elemental powders.

[0095] Step 2: Dissolve 2g of polyvinyl alcohol with a molecular weight of 20000 in a mixed solution of 0.5g water and 8g dimethyl sulfoxide, heat the temperature to 100℃ and conduct magnetic stirring, after the polyvinyl alcohol is completely dissolved, add a total mass of 0.05g of metal elemental powder, continue to stir for 3h until the mixture is uniform, then obtain the precursor solution.

[0096] Step 3: Inject the uniformly mixed precursor solution into a self-made polytetrafluoroethylene mold at a high temperature of 100℃, transfer the mold to a low temperature environment of -30℃, make the polyvinyl alcohol physically crosslink to form a solid gel, and the low temperature polymerization time is 12h. After the reaction is completed, the solid gel is demolded and taken out to obtain the initial alloy hydrogel polymer.

[0097] Step 4: Immerse the initial alloy hydrogel polymer in deionized water at room temperature of 20℃ for 6h until the organic solvent is completely replaced by deionized water, obtain the alloy hydrogel polymer, that is, the composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function; put it in deionized water for storage.

[0098] Performance analysis:

[0099] 1. Solar absorption spectrum analysis:

[0100] Use UV-visible-near infrared spectrophotometer (UV-3600i) to test the absorbance of the sample in the range of 300nm-2500nm, first turn on the instrument and preheat it to stable state, select the appropriate integral sphere accessory sample cell. With barium sulfate as blank reference, baseline correction is carried out, then the sample to be tested is uniformly loaded into the sample cell, ensuring no impurity interference and pressing the sample. Set the scanning parameters to 300nm-2500nm, adjust the slit width to 20nm, the data interval to 1nm, and the luminosity value type to reflectance. After starting the scan, the instrument will irradiate the sample with deuterium lamp (ultraviolet region) and halogen tungsten lamp (visible-near infrared region) step by step, and the detector will record the reflected light intensity and convert it into absorbance data.

[0101] Figure 5 The medium gray area is the solar radiation spectrum, indicating that the addition of high-entropy alloy nanoparticles greatly improves the solar light absorption of the hydrogel evaporator, and the high-entropy alloy nanoparticles and the hydrogel composition show a synergistic effect in solar light absorption, further improving the solar light absorption rate of the composite hydrogel evaporator with chemical-photothermal synergistic antibacterial function to 97.2%.

[0102] 2. Water evaporation mass loss curve analysis:

[0103] The water evaporation mass loss of the sample was tested by using a xenon lamp light source and a precision analytical balance with an accuracy of 0.0001 g. First, the sample was placed in a constant temperature environment, and the initial mass was recorded. The xenon lamp light source was turned on and adjusted to a single solar radiation light intensity (AM = 1.5G), ensuring uniform heating of the sample surface. The sample was placed within the light source irradiation range, and the precision balance was set to output the current weight reading every 1 min. By continuously recording the time-mass data, the mass loss per unit time was calculated, and combined with the sample surface area, the water evaporation rate was finally obtained, with the unit being kg·m -2 ·h -1 .

[0104] Figure 6 The absolute value of the middle curve slope represents the water evaporation rate, wherein the water evaporation rates of the composite hydrogel evaporator of Example 3 and the hydrogel evaporator of Comparative Example 1 were calculated to be 2.4 kg·m -2 ·h -1 and 2.0 kg·m -2 ·h -1 , indicating that the addition of high-entropy alloy nanoparticles greatly improves the solar light absorption rate, thereby accelerating the water evaporation rate.

[0105] 3. Antibacterial effect analysis:

[0106] The flat plate coating method was used to evaluate the antibacterial effect. First, the target bacteria solution (Pseudomonas aeruginosa or Bacillus vietnamensis) was diluted to an appropriate concentration (about 10 5 CFU / mL-10 6 CFU / mL), and the sample was immersed in the target bacteria solution for 24 h. Then, using sterile PBS buffer as the liquid medium, the bacteria attached to the surface of the sample were separated under vortex shaking, and coated on the surface of sterile solid culture medium. The solid culture medium inoculated with bacteria was inverted and incubated in a 37°C constant temperature incubator under dark conditions for 18-24 h. The number of bacterial colonies was observed to evaluate the antibacterial activity. All experiments were performed under sterile conditions.

[0107] From Figure 7 (a), Figure 7 (b) and Figure 7 (c) and Figure 8 (a), Figure 8 (b) and Figure 8(c) It can be known that the prepared composite high-entropy alloy hydrogel evaporator has excellent antibacterial ability, and the survival rate of bacteria co-cultured with the composite high-entropy alloy hydrogel evaporator is significantly lower than that of the hydrogel evaporator of the comparative example 1. After the composite hydrogel evaporator of example 3 is irradiated for 30 min under one solar intensity (other conditions are the same as those of the sample antibacterial experiment), due to the synergistic bactericidal effect of the high-entropy alloy photothermal effect, the antibacterial rate is further increased to more than 99%. In addition, the high-entropy alloy has significant killing ability on Bacillus vietnamensis, and on the basis of no synergistic photothermal effect, it can basically achieve complete killing of Bacillus vietnamensis.

Claims

1. A composite hydrogel evaporator with chemical-photothermal synergistic antibacterial, characterized in that, The composite hydrogel evaporator is composed of high-entropy alloy nanoparticles and a hydrogel; the high-entropy alloy nanoparticles are composed of equimolar Fe, Ni, Ti, Cr, Mn and Cu elements, have a particle size of 40-100 nm and are uniformly dispersed in the hydrogel; the hydrogel is composed of polyvinyl alcohol cured by physical cross-linking; the mass ratio of the polyvinyl alcohol to the high-entropy alloy nanoparticles is 100: (1-10), and the molecular weight of the polyvinyl alcohol ranges from 10,000 to 100,000; when the composite hydrogel evaporator is used for seawater desalination, it has light-heat antibacterial ability and can resist microbial pollution in seawater.

2. The method for preparing the composite hydrogel evaporator with chemical- photothermal synergistic antibacterial according to claim 1, characterized in that, It comprises the following steps: Step 1-1: equimolar Fe, Ni, Ti, Cr, Mn and Cu metal powders are used as initial raw materials, and a high-entropy alloy flake is obtained by mechanical alloying technology; the high-entropy alloy flake is formed into a preform by cold pressing; Step 1-2: vacuum degree ≤ 5 × 10 -3 The prepared body is subjected to arc discharge treatment in a vacuum environment with a vacuum degree of 5 × 10 Pa and a hydrogen gas and an argon gas mixture as plasma medium, and the product obtained by the arc discharge treatment is passivated to obtain high-entropy alloy nanoparticles; the volume ratio of the hydrogen gas to the argon gas is 4:1, the arc discharge treatment time is 5 min-30 min, the voltage is 66 V, the current is 180 A-250 A, and the cooling substrate temperature is 7℃-10℃; the passivation refers to exposing the product obtained by the arc discharge treatment in air for 6 h-12 h to form an oxide film on the surface; the high-entropy alloy nanoparticles have a particle size of 40 nm-100 nm. Step 2: polyvinyl alcohol is dissolved in a mixed solution of water and an organic solvent, high-entropy alloy nanoparticles are added, and the mixture is uniformly mixed to obtain a precursor solution; the mass ratio of the polyvinyl alcohol to the high-entropy alloy nanoparticles is 100: (1-10); the molecular weight of the polyvinyl alcohol ranges from 10,000 to 100,000; the organic solvent is dimethyl sulfoxide, the mass ratio of the organic solvent and water to the polyvinyl alcohol is 100: (10-80), and the mass ratio of the organic solvent to water is 100: (1-10); Step 3: the precursor solution is cured by physical cross-linking to obtain an initial high-entropy alloy hydrogel polymer; Step 4: the initial high-entropy alloy hydrogel polymer is immersed in deionized water at 15-30℃ for 1-12h until the organic solvent is completely replaced by deionized water, to obtain a high-entropy alloy hydrogel polymer, i.e. a composite hydrogel evaporator with chemical-light-heat synergistic antibacterial ability.

3. The method according to claim 2, wherein the method is characterized by, In step 1-1, the particle size of the initial raw material is 45-100 μm.

4. The method according to claim 2, wherein the method is characterized by, In step 2, the dissolution temperature is 50-120℃, the polyvinyl alcohol is completely dissolved, then the high-entropy alloy nanoparticles are added, and the mixture is uniformly mixed by stirring for 1-5h to obtain the precursor solution.

5. The method according to claim 2, wherein the method is characterized by, In step 3, the physical cross-linking curing temperature is -50-0℃, and the time is 6-24h, so that the polyvinyl alcohol is cured to form a solid gel by physical cross-linking.

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