A bio-based photothermal microsphere and its preparation method and application

Abstract

The present invention discloses a bio-based photothermal microsphere and a preparation method and application thereof, wherein the microsphere comprises a bio-based material and a photothermal conversion material. The bio-based photothermal microsphere provided by the present invention has good biodegradability and is environmentally friendly. At the same time, the photothermal microsphere of the present invention has good light absorption performance, photothermal conversion ability, and high water evaporation rate under illumination, and thus has important practical value in the fields of energy utilization, seawater desalination, photothermal sterilization, etc.

Description

Technical Field

[0001] The invention belongs to the field of solar interface water evaporation materials and preparation thereof, and relates to a bio-based photothermal microsphere and a preparation method and application thereof. Background Art

[0002] Drinking water scarcity is a global issue of fundamental human rights and well-being, prompting people to obtain fresh water from the ocean as well as industrial and municipal wastewater. However, addressing drinking water scarcity entirely through nature-based solutions remains a huge challenge.

[0003] In order to overcome the above technical problems, water evaporation collection equipment is currently mainly built based on synthetic polymer gels, foams and solar thermal materials to obtain fresh water. However, synthetic polymer gels or foams are difficult to degrade when they are applied and promoted on a large scale, which is not conducive to outdoor application scenarios where they need to be discarded. In addition, conventional solar thermal materials or water evaporation collection equipment are often bulky and difficult to carry. Therefore, how to solve the problem of drinking water shortage in remote areas remains a huge challenge. Summary of the invention

[0004] In order to improve the above technical problems, the present invention utilizes the biodegradable characteristics of bio-based materials and the excellent photothermal conversion performance of photothermal materials to produce bio-based photothermal microspheres with high photothermal conversion efficiency and solar water evaporation rate, which have important application value.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A microsphere comprising a bio-based material and a photothermal conversion material.

[0007] According to the present invention, the average particle size of the microspheres is 1 μm-3 mm; specifically, it can be 100 μm-1 mm, exemplified by 1 μm, 2 μm, 5 μm, 8 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 500 μm, 800 μm, 1 mm, 2 mm, 3 mm or any point within the range composed of any two of the aforementioned values.

[0008] According to the present invention, the microspheres have good biodegradability, light absorption performance, photothermal conversion performance and high water evaporation rate.

[0009] According to the present invention, the light absorption efficiency of the microspheres is ≥99.0%, specifically ≥99.5%, exemplified by 99.2%, 98.9%, and 99.0%.

[0010] According to the present invention, the light-to-heat conversion efficiency of the microspheres is ≥85%, such as ≥90%, and also such as ≥92%, exemplarily 87.9%, 92.3%, and 87.1%.

[0011] According to the present invention, the water evaporation rate of the microspheres under one solar equivalent is ≥1.65kg.m -2 .h -1 , for example ≥1.70kg.m -2 .h -1 , for example ≥1.80kg.m -2 .h -1 , for example ≥1.90kg.m -2 .h -1 , and can also be ≥2.0kg.m -2 .h -1 , exemplified by 1.65kg.m -2 .h -1 、1.85kg.m -2 .h -1 , 2.03kg.m -2 .h -1 .

[0012] According to the present invention, the microspheres contain water or do not contain water. Among them, the microspheres containing water are bio-based gel microspheres, the bio-based comes from the bio-based material, and the gel includes the photothermal conversion material. Taking cellulose as an example of the bio-based material, when the photothermal conversion material is selected from carbon nanotubes, it is cellulose@carbon nanotube (Cell@CNT) bio-based gel microspheres; when the photothermal conversion material is selected from polydopamine, it is cellulose@polydopamine (Cell@PDA) bio-based gel microspheres; when the photothermal conversion material is selected from polypyrrole, it is cellulose@polypyrrole (Cell@PPy) bio-based gel microspheres. Taking the bio-based material as an example, when the photothermal conversion material is selected from carbon nanotubes, it is chitosan@carbon nanotubes (chitosan@CNT) bio-based gel microspheres; when the photothermal conversion material is selected from polydopamine, it is chitosan@polydopamine (chitosan@PDA) bio-based gel microspheres; when the photothermal conversion material is selected from polypyrrole, it is chitosan@polypyrrole (chitosan@PPy) bio-based gel microspheres. Taking the bio-based material as an example, when the photothermal conversion material is selected from carbon nanotubes, it is starch@carbon nanotubes (starch@CNT) bio-based gel microspheres; when the photothermal conversion material is selected from polydopamine, it is starch@polydopamine (starch@PDA) bio-based gel microspheres; when the photothermal conversion material is selected from polypyrrole, it is starch@polypyrrole (starch@PPy) bio-based gel microspheres. Taking straw as an example of bio-based material, when the photothermal conversion material is selected from carbon nanotubes, it is straw@carbon nanotube (straw@CNT) bio-based gel microspheres; when the photothermal conversion material is selected from polydopamine, it is straw@polydopamine (straw@PDA) bio-based gel microspheres; when the photothermal conversion material is selected from polypyrrole, it is straw@polypyrrole (straw@PPy) bio-based gel microspheres.

[0013] According to the present invention, the bio-based gel microspheres have a hydrophilic three-dimensional network structure, in which a portion of intermediate water can be retained. In the present invention, the intermediate water retained in the hydrophilic three-dimensional network of the bio-based gel microspheres significantly reduces the evaporation enthalpy, thereby improving the efficiency of solar evaporation. Thus, a sustainable solution for collecting clean water from the environment using solar energy to obtain fresh water is achieved.

[0014] According to the present invention, in the microspheres, the mass percentage of the photothermal conversion material is 0.01-1wt%, for example, 0.01-0.1wt%, and illustratively can be 0.01wt%, 0.015wt%, 0.02wt%, 0.05wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt% or 1.0wt%.

[0015] According to the present invention, the photothermal conversion material is selected from at least one of plasmonic metal particles, carbon-based materials and photothermal polymer materials.

[0016] For example, the plasmonic metal particles include at least one of plasma gold, plasma silver, and plasma copper.

[0017] For example, the carbon-based material includes at least one of carbon nanotubes, graphite, carbon black, graphene, and graphene oxide.

[0018] For example, the photothermal polymer material includes at least one of polypyrrole (Py), polydopamine, polythiophene, and polyaniline.

[0019] According to the present invention, in the microspheres, the photothermal conversion material is dispersed, aggregated, adsorbed, or exists in the interior and / or on the surface of the bio-based material in two or three of the above-mentioned ways.

[0020] According to the present invention, when the photothermal conversion material is selected from a photothermal polymer material, the microsphere has a core-shell structure, the core includes the bio-based material, and the shell includes the photothermal conversion material.

[0021] According to the present invention, the photothermal conversion material is loaded on the surface and / or inside of the bio-based material. More specifically, the photothermal conversion material is loaded on the surface of the spherical granular bio-based material by in-situ polymerization, or loaded on the surface of the spherical granular bio-based material by adsorption.

[0022] According to the present invention, in the microspheres, the loading amount of the photothermal conversion material is 0.01-1wt%, for example, 0.01-0.1wt%, and illustratively can be 0.01wt%, 0.015wt%, 0.02wt%, 0.05wt%, 0.07wt%, 0.08wt%, 0.09wt%, 0.1wt%, 0.2wt%, 0.4wt%, 0.6wt%, 0.8wt% or 1.0wt%.

[0023] According to the present invention, the bio-based material is derived from biomass natural polymer material; preferably, the biomass natural polymer material is selected from one or more of the following substances: cellulose, starch, lignin, chitosan, chitin, hemicellulose, glucan, low-quality cellulose and / or natural plant tissue containing one or more of the above components.

[0024] Preferably, the cellulose can be selected from at least one of microcrystalline cellulose, bacterial cellulose, cotton pulp, wood pulp, bamboo pulp, straw pulp, refined cotton, absorbent cotton, cotton linters, and cellulose extracted from plant tissues such as bagasse, wood and straw. Preferably, the cellulose is at least one of microcrystalline cellulose, refined cotton, absorbent cotton and wood pulp.

[0025] Preferably, the starch can be selected from at least one of amylopectin, amylose, high amylose starch, modified starch, and cross-linked starch; and / or selected from soluble starch, such as α-starch; and / or selected from at least one of potato starch, corn starch, cassava starch, wheat starch, sweet potato starch, kudzu starch, pea starch, water chestnut starch, soybean starch, and lotus root starch.

[0026] The present invention does not particularly limit the selection of the chitosan, chitin, lignin, hemicellulose, glucan, etc. For example, they can be selected from systems well known to those skilled in the art and applicable to the present invention.

[0027] For example, the deacetylation degree of the chitosan is 50-100%; in another example, the deacetylation degree of the chitosan is 70-95%.

[0028] For example, the lignin is selected from at least one of syringyl lignin, guaiacyl lignin, p-hydroxyphenyl lignin, etc.; or, the lignin can be selected from at least one of alkaline lignin, acidic lignin, dealkalized lignin, and organic solvent-dissolved lignin.

[0029] The low-quality cellulose is a plant tissue containing at least two components, cellulose and lignin. For example, the plant tissue may be at least one of herbaceous plants and / or agricultural and forestry wastes.

[0030] For example, the herb is selected from plant tissues of trees, shrubs, vines, leaves, bamboo, and the like.

[0031] For example, the agricultural and forestry waste is selected from bark, leaves, sawdust, crop straw, fruit shells or cores, corn cobs, bagasse, etc. Preferably, the crop straw can be selected from at least one of wheat straw, rice straw, corn straw, soybean straw, cotton straw, ginger stalk, and sesame straw.

[0032] The present invention also provides a method for preparing the above microspheres, which includes the following two methods:

[0033] The first method comprises the following steps: obtaining the microspheres by in-situ polymerization and / or adsorption on the surface of spherical granular bio-based materials;

[0034] The second method comprises the following steps: preparing the microspheres by blending a bio-based material solution with a photothermal conversion material.

[0035] According to the present invention, the preparation method may further include a drying step. Before drying, the microspheres contain water and are bio-based gel microspheres; after drying, the microspheres do not contain water. The present invention does not particularly limit the conditions for the drying treatment, and those skilled in the art may select according to actual needs, which may be drying at room temperature and pressure, vacuum drying, freeze drying, or supercritical drying.

[0036] [First method]

[0037] According to the present invention, the first method specifically comprises: dispersing the spherical granular bio-based material in a solvent, adding a photothermal polymer material monomer, and preparing the microspheres by in situ polymerization; or, dispersing the spherical granular bio-based material in a solvent, adding a photothermal polymer material, and the photothermal polymer material is adsorbed on the surface of the bio-based material to prepare the microspheres.

[0038] According to the present invention, in the first method, the solvent is selected from at least one of water, N,N-dimethylformamide (DMF), N,N-dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), acetone, butanone, chloroform, ethyl acetate, pyridine, ethanol, methanol, n-hexane, cyclohexane, and dichloromethane.

[0039] According to the present invention, in the first method, the monomer is selected from at least one of pyrrole, thiophene and dopamine.

[0040] According to the present invention, in the first method, the spherical granular bio-based material, also called bio-based microspheres, is prepared by a method comprising the following steps: dissolving the bio-based material in a solvent, and obtaining the bio-based microspheres by a coaxial airflow shearing method.

[0041] According to the present invention, the bio-based material has the definition and selection as described above.

[0042] The present invention does not specifically limit the process parameters of the coaxial airflow shearing method, and those skilled in the art can prepare it using conventional coaxial airflow shearing equipment. For example, the inner and outer needle tubes of the coaxial airflow nozzle can be combined into 16G / 27G (flush), the injection pressure can be 0.18MPa, the gas flow rate can be controlled to 1.8L / min, and water can be used as the coagulation bath.

[0043] According to the present invention, the bio-based microspheres may contain water or not contain water, wherein the bio-based gel microspheres contain water.

[0044] According to the present invention, in the first method, when the monomer of the photothermal polymer material is pyrrole, the polymerization reaction needs to be carried out in the presence of ferric chloride.

[0045] According to an exemplary embodiment of the present invention, the concentration of ferric chloride is 0.0125M-0.2M; preferably 0.05M-0.1M, exemplified by 0.0125M, 0.02M, 0.05M, 0.08M, 0.1M, 0.2M or any point in the range consisting of any two of the foregoing values.

[0046] According to an exemplary embodiment of the present invention, the concentration of pyrrole is 0.00036M-4.24M; preferably 0.13M-1.06M, exemplified by 0.00036M, 0.0005M, 0.001M, 0.005M, 0.008M, 0.01M, 0.05M, 0.1M, 0.5M, 1.06M, 1.5M, 2.0M, 3.0M, 4.0M, 4.24M or any point within the range consisting of any two of the foregoing values.

[0047] According to an exemplary embodiment of the present invention, in the first method, when the photothermal polymer material monomer is pyrrole, the solvent is selected from at least one of cyclohexane, N,N-dimethylformamide (DMF), N,N-dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMAc), acetone, butanone, chloroform, ethyl acetate and pyridine. Cyclohexane is preferred.

[0048] According to the present invention, in the first method, when the monomer of the photothermal polymer material is dopamine, the polymerization reaction needs to be carried out in the presence of dopamine hydrochloride.

[0049] According to an exemplary embodiment of the present invention, in the dopamine polymerization reaction, the mass ratio of bio-based microspheres to dopamine hydrochloride is 3.15-200; preferably 10-50, exemplified by 3.15, 5, 10, 20, 50, 80, 100, 200 or any point in the range consisting of the foregoing values ​​in pairs.

[0050] [Second method]

[0051] According to the present invention, in the second method, the photothermal conversion material has the definition and selection as shown above.

[0052] According to the present invention, in the second method, the bio-based microspheres may contain water or may not contain water, wherein the bio-based gel microspheres contain water.

[0053] According to the present invention, in the second method, the blending process can specifically adopt at least one of an emulsion method, a membrane emulsion method, a falling ball method, a vibration granulation method, a microfluidics method, an ultrasonic atomization method, a shear jet method, a piezoelectric ball method, an electrostatic ball method, and a coaxial airflow shear method. Preferably, the coaxial airflow shear method is used.

[0054] The present invention does not specifically limit the process parameters of the coaxial airflow shearing process, and those skilled in the art can prepare it using conventional coaxial airflow shearing equipment. For example, the inner and outer needle tubes of the coaxial airflow nozzle can be combined into 16G / 27G (flush), the injection pressure can be 0.18MPa, the gas flow rate can be controlled to 1.8L / min, and water can be used as the coagulation bath.

[0055] The present invention also provides the use of the microspheres in collecting clean water from ambient water using solar energy to obtain fresh water.

[0056] According to the present invention, the environmental water may be at least one of lake water, sea water, industrial waste water, etc.

[0057] The present invention does not particularly limit the method for collecting clean water from ambient water by using solar energy with the microspheres, and conventional methods known to those skilled in the art may be used.

[0058] For example, the microspheres are directly poured into the above-mentioned environmental water, and the generated water vapor is collected to obtain drinkable pure water.

[0059] The beneficial effects of the present invention are:

[0060] (1) The present invention provides a microsphere having good biodegradability, light absorption performance, photothermal conversion performance and high water evaporation rate. Specifically, the microsphere is a bio-based photothermal microsphere with solar interface water evaporation function, having high photothermal conversion efficiency and high water evaporation rate under one solar equivalent (100mw / cm 2 ) light intensity, and due to the good biodegradability of bio-based materials, it is environmentally friendly. In addition, the bio-based photothermal microspheres of the present invention also have good antibacterial and shape-adaptive characteristics, and have important practical value.

[0061] (2) The present invention proposes a microsphere, which may contain water or not; wherein the microsphere containing water is a bio-based gel microsphere (based on the intermediate water retained in the hydrophilic three-dimensional network of the bio-based gel microsphere, the evaporation enthalpy is significantly reduced, thereby improving the efficiency of solar evaporation). The microsphere of the present invention can realize the sustainable solution of collecting clean water from the environment using solar energy to obtain fresh water. And the main body of the microsphere of the present invention is made of bio-based materials (such as cellulose), and the photothermal microspheres prepared therefrom are degradable. And the source of bio-based materials is wide, taking cellulose as an example, it is the most abundant natural polymer on the earth, which can promote the large-scale production and application of photothermal microspheres. In addition, by utilizing the advantages of photothermal microspheres such as portability, shape adaptation and antibacterial, a simplified water collection device can be easily assembled with common materials in daily life. This low-cost device can provide a convenient and practical solution to alleviate the shortage of drinking water in poor areas around the world, which is fully in line with the goals of sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 (a) is a microscope image of the cellulose gel microspheres used for surface polymerization in Examples 1 and 5.

[0063] Figure 1 (b) is a microscope image of the chitosan gel microspheres used for surface polymerization in Examples 2 and 6.

[0064] Figure 1 (c) is a microscope image of the Cell@PPy gel microspheres obtained in Example 1.

[0065] Figure 1 (d) is a scanning electron micrograph of the supercritically dried cellulose microspheres used for surface polymerization in Examples 1 and 5.

[0066] Figure 1 (e) is a scanning electron micrograph of the supercritically dried chitosan microspheres used for surface polymerization in Examples 2 and 6.

[0067] Figure 1 (f) is a scanning electron microscope image of the Cell@PPy gel microspheres obtained in Example 1 after supercritical drying.

[0068] Figure 2 (a) is a scanning electron microscope image of the cellulose / carbon nanotube (Cell / CNT) gel microspheres in Example 9 after supercritical drying.

[0069] Figure 2 (b) is a scanning electron microscope image of the cellulose@polydopamine (Cell@PDA) gel microspheres in Example 5 after supercritical drying.

[0070] Figure 3(a) is an optical picture of the cellulose gel microspheres used for surface polymerization in Examples 1 and 5.

[0071] Figure 3 (b) is an optical image of the Cell@PPy photothermal microspheres obtained by polymerization in Example 1.

[0072] Figure 3 (c) is an optical image of the Cell@PDA photothermal microspheres obtained by polymerization in Example 5.

[0073] Figure 3 (d) is an optical image of the Cell / CNT photothermal microspheres obtained in Example 9.

[0074] Figure 4 (a) is the UV-visible absorption spectrum of Cell@PPy gel microspheres obtained by adjusting the pyrrole concentration in Example 1.

[0075] Figure 4 (b) is the UV-visible absorption spectrum of Cell@PDA gel microspheres obtained by adjusting the concentration of dopamine hydrochloride in Example 5.

[0076] Figure 4 (c) is the UV-visible absorption spectrum of the Cell / CNT gel microspheres obtained by adjusting the carbon nanotube content in Example 9.

[0077] Figure 4 (d) is the average absorbance of the three cellulose-based photothermal microspheres in Examples 1, 5, and 9 in the visible light region.

[0078] Figure 5 (a) is the water evaporation rate of the three photothermal microspheres in Examples 1, 5, and 9 under a light intensity of 1 sun equivalent.

[0079] Figure 5 (b) is the temperature rise curve of the three photothermal microspheres in Examples 1, 5, and 9 under a light intensity of 1 sun equivalent.

[0080] Figure 5 (c) is a thermal imaging picture of the three photothermal microspheres in Examples 1, 5, and 9 under a light intensity of 1 sun equivalent.

[0081] Figure 6 (a) is a physical picture of the water collection device in Example 17 and its interface during the evaporation process (wherein: the left picture is a physical picture of the water collection device obtained by bonding plexiglass with AB glue during the water collection process; the middle picture is a partial enlarged picture of the evaporation interface in the left picture; the right picture is a physical picture of the water collection device obtained by bonding plexiglass rods and anti-fog film with AB glue during the water collection process).

[0082] Figure 6 (b) is the relationship between the temperature, light intensity, water collection per unit area, and water collection rate per unit area and time in Example 17.

[0083] Figure 7 The mold used in Example 18 was used to shape the microspheres into a rosette shape.

[0084] Figure 8 (a) is a diagram showing the bactericidal effect of the bio-based photothermal microspheres (taking Cell@PPy as an example) in Example 19 on Escherichia coli and Staphylococcus aureus relative to the control group PBS.

[0085] Figure 8 (b) is a graph showing the sterilization rate of the bio-based photothermal microspheres (taking Cell@PPy as an example) against Escherichia coli and Staphylococcus aureus in Example 19. DETAILED DESCRIPTION

[0086] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The raw materials described can be obtained from public commercial channels unless otherwise specified.

[0087] Example 1

[0088] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0089] (1) Weigh 25.5 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 80° C. Then slowly add 2.5 g of microcrystalline cellulose, and after complete dissolution in vacuum, add 25 g of DMF and stir until mixed evenly to obtain a cellulose ionic liquid solution;

[0090] (2) placing the cellulose solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare cellulose gel microspheres;

[0091] (3) Take 3.5 g of cellulose microspheres prepared in step (2) and add them to 50 ml of 0.1 M FeCl 3 After soaking for 12 hours, filter (until no droplets remain within 10 seconds), and the FeCl 3 The cellulose microspheres were added to a 0.26 M pyrrole (Py) cyclohexane solution and reacted at room temperature for 12 h to obtain Cell@PPy photothermal gel microspheres.

[0092] Furthermore, the Cell@PPy photothermal gel microspheres may be dried to obtain water-free Cell@PPy photothermal microspheres.

[0093] Example 2

[0094] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0095] (1) Add 3 g of glacial acetic acid and 45 g of deionized water into a 100 ml beaker, then add 2 g of chitosan, and stir until the mixture is evenly dispersed to obtain a chitosan solution;

[0096] (2) placing the chitosan solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare the microspheres;

[0097] (3) Take 3.5 g of chitosan microspheres prepared in step (2) and add them to 50 ml of 0.1 M FeCl 3 After soaking for 12 hours, filter (until no droplets remain within 10 seconds), and the FeCl 3 The chitosan microspheres were added to a 0.26 M Py cyclohexane solution and reacted at room temperature for 12 h to obtain chitosan@PPy photothermal gel microspheres.

[0098] Furthermore, the chitosan@PPy photothermal gel microspheres may be dried to obtain water-free chitosan@PPy photothermal microspheres.

[0099] Example 3

[0100] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0101] (1) Weigh 2.5 g corn starch, add it to 22.5 g ionic liquid AmimCl, heat it to 100° C. under nitrogen protection, and stir it mechanically until the starch is completely dissolved and the solution is transparent; after the solution is cooled, add 25.0 g DMF co-solvent, stir it evenly to obtain a starch solution;

[0102] (2) filtering the mixed solution obtained in step (1) through a 1 μm glass fiber filter and setting aside for use, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare the microspheres;

[0103] (3) Take 3.5 g of the starch microspheres prepared in step (2) and add them to 50 ml of 0.1 M FeCl 3 After soaking for 12 hours, filter (until no droplets remain within 10 seconds), and the FeCl 3The starch microspheres were added to a 0.26 M Py cyclohexane solution and reacted at room temperature for 12 h to obtain starch@PPy photothermal gel microspheres.

[0104] Furthermore, the starch@PPy photothermal gel microspheres may be dried to obtain water-free starch@PPy photothermal microspheres.

[0105] Example 4

[0106] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0107] (1) Weigh 95 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 120°C, then slowly add 5 g of straw and dissolve it in vacuum for 5 h. Centrifuge the obtained dispersion and take 40 g of the supernatant and add 10 g of DMF to it and stir thoroughly to obtain a straw ionic liquid solution;

[0108] (2) placing the straw solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; water is used as a coagulation bath to prepare the microspheres;

[0109] (3) Take 3.5 g of straw microspheres prepared in step (2) and add them to 50 ml of 0.1 M FeCl 3 After soaking for 12 hours, filter (until no droplets remain within 10 seconds), and the FeCl 3 The straw microspheres were added into 0.26 M Py cyclohexane solution and reacted at room temperature for 12 h to obtain straw@PPy photothermal gel microspheres.

[0110] Furthermore, the straw@PPy photothermal gel microspheres may be dried to obtain water-free straw@PPy photothermal microspheres.

[0111] Example 5

[0112] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0113] (1) Weigh 25.5 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 80° C. Then slowly add 2.5 g of microcrystalline cellulose, and after complete dissolution in vacuum, add 25 g of DMF and stir until mixed evenly to obtain a cellulose ionic liquid solution;

[0114] (2) placing the cellulose solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare cellulose microspheres;

[0115] (3) Weigh 1.25 g of the cellulose microspheres obtained in step (2) and add them into a two-necked flask, then add 50 ml of deionized water, 0.07 g of tris(hydroxymethyl)aminomethane (Tris) and 0.1 g of dopamine hydrochloride (pH 8.4±0.1) under stirring, and then heat at 60°C for 20 h to obtain Cell@PDA photothermal gel microspheres.

[0116] Furthermore, the Cell@PDA photothermal gel microspheres may be dried to obtain water-free Cell@PDA photothermal microspheres.

[0117] Example 6

[0118] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0119] (1) Add 3 g of glacial acetic acid and 45 g of deionized water into a 100 ml beaker, then add 2 g of chitosan, and stir until the mixture is evenly dispersed to obtain a chitosan solution;

[0120] (2) placing the chitosan solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare the microspheres;

[0121] (3) Weigh 1.25 g of the chitosan microspheres obtained in step (2) and add them to a two-necked flask, then add 50 ml of deionized water, 0.07 g of tris(hydroxymethyl)aminomethane (Tris) and 0.1 g of dopamine hydrochloride (pH 8.4±0.1) under stirring, and then heat at 60°C for 20 h to obtain chitosan@PDA photothermal gel microspheres.

[0122] Furthermore, the chitosan@PDA photothermal gel microspheres may be dried to obtain water-free chitosan@PDA photothermal microspheres.

[0123] Example 7

[0124] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0125] (1) Weigh 2.5 g corn starch, add it to 22.5 g ionic liquid AmimCl, heat it to 100° C. under nitrogen protection, and stir it mechanically until the starch is completely dissolved and the solution is transparent; after the solution is cooled, add 25.0 g DMF co-solvent, stir it evenly to obtain a starch solution;

[0126] (2) filtering the mixed solution obtained in step (1) through a 1 μm glass fiber filter and setting aside for use, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; and water is used as a coagulation bath to prepare the microspheres;

[0127] (3) Weigh 1.25 g of the starch microspheres obtained in step (2) and add them to a two-necked flask, then add 50 ml of deionized water, 0.07 g of tris(hydroxymethyl)aminomethane (Tris) and 0.1 g of dopamine hydrochloride (pH 8.4±0.1) under stirring, and then heat at 60°C for 20 h to obtain starch@PDA photothermal gel microspheres.

[0128] Furthermore, the starch@PDA photothermal gel microspheres may be dried to obtain water-free starch@PDA photothermal microspheres.

[0129] Example 8

[0130] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0131] (1) Weigh 95 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 120°C, then slowly add 5 g of straw and dissolve it in vacuum for 5 h. Centrifuge the obtained dispersion and take 40 g of the supernatant and add 10 g of DMF to it and stir thoroughly to obtain a straw ionic liquid solution;

[0132] (2) placing the straw solution obtained in step (1) into a 50 ml syringe, and preparing microspheres by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination is 16G / 27G (flush), the injection pressure is 0.18 MPa, and the gas flow rate is controlled at 1.8 L / min; water is used as a coagulation bath to prepare the microspheres;

[0133] (3) Weigh 1.25 g of the straw microspheres obtained in step (2) and add them into a two-necked flask, then add 50 ml of deionized water, 0.07 g of tris(hydroxymethyl)aminomethane (Tris) and 0.1 g of dopamine hydrochloride (pH 8.4±0.1) under stirring, and then heat at 60°C for 20 h to obtain straw@PDA photothermal gel microspheres.

[0134] Furthermore, the straw@PDA photothermal gel microspheres may be dried to obtain water-free straw@PDA photothermal microspheres.

[0135] Example 9

[0136] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0137] (1) Weigh 0.20 g of fully ground CNTs and add them to a two-necked flask, then add 25.5 g of ionic liquid AmimCl, stir and heat to 80°C, then slowly add 2.5 g of microcrystalline cellulose, and after complete vacuum dissolution, add 25 g of DMF and stir until mixed evenly to obtain a cellulose CNT ionic liquid solution with a CNT content of 0.4%;

[0138] (2) The cellulose solution obtained in step (1) was placed in a 50 ml syringe, and microspheres were prepared by a coaxial airflow shear method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as a coagulation bath to prepare Cell@CNT photothermal gel microspheres.

[0139] Furthermore, the Cell@CNT photothermal gel microspheres may be dried to obtain water-free Cell@CNT photothermal microspheres.

[0140] Example 10

[0141] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0142] (1) Weigh 95 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 120°C, then slowly add 5 g of straw and dissolve it in a vacuum for 5 h, centrifuge the obtained dispersion and take 40 g of the supernatant, add 10 g of DMF and 0.20 g of fully ground CNT, and stir well to obtain a straw CNT ionic liquid solution with a CNT content of 0.4%;

[0143] (2) The straw solution obtained in step (1) was placed in a 50 ml syringe, and microspheres were prepared by coaxial airflow shearing method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as the coagulation bath to prepare the straw@CNT photothermal gel microspheres.

[0144] Furthermore, the straw@CNT photothermal gel microspheres may be dried to obtain water-free straw@CNT photothermal microspheres.

[0145] Embodiment 11

[0146] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0147] (1) Add 3 g of glacial acetic acid and 45 g of deionized water into a 100 ml beaker, then add 2 g of chitosan and 0.20 g of fully ground CNT, and stir until evenly dispersed to obtain a chitosan CNT solution with a CNT content of 0.04%;

[0148] (2) The chitosan solution obtained in step (1) was placed in a 50 ml syringe, and microspheres were prepared by coaxial airflow shearing method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as the coagulation bath to prepare chitosan@CNT photothermal gel microspheres.

[0149] Furthermore, the chitosan@CNT photothermal gel microspheres may be dried to obtain water-free chitosan@CNT photothermal microspheres.

[0150] Example 12

[0151] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0152] (1) Weigh 0.010 g of nano-gold and add it to a two-necked flask, then add 25.5 g of ionic liquid AmimCl, stir and heat to 80° C., then slowly add 2.5 g of microcrystalline cellulose, and after complete dissolution in vacuum, add 25 g of DMF and stir until mixed evenly to obtain a cellulose nano-gold ionic liquid solution with a nano-gold content of 0.02 wt.%;

[0153] The cellulose nanogold solution obtained in step (1) was placed in a 50 ml syringe, and the microspheres were prepared by a coaxial airflow shearing method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as a coagulation bath to prepare the cellulose@nanogold photothermal gel microspheres.

[0154] Furthermore, the cellulose@nano-gold photothermal gel microspheres may be dried to obtain water-free cellulose@nano-gold photothermal microspheres.

[0155] Embodiment 13

[0156] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0157] (1) Weigh 95 g of ionic liquid AmimCl and add it to a two-necked flask, stir and heat to 120°C, then slowly add 5 g of straw and dissolve it in vacuum for 5 h, centrifuge the obtained dispersion and take 40 g of the supernatant, add 10 g of DMF and 0.10 g of nano-gold, and stir thoroughly to obtain a straw nano-gold ionic liquid solution with a nano-gold content of 0.2%;

[0158] (2) The straw nanogold solution obtained in step (1) was placed in a 50 ml syringe, and microspheres were prepared by coaxial airflow shearing method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as the coagulation bath to prepare the straw@nanogold photothermal gel microspheres.

[0159] Furthermore, the straw@nano-gold photothermal gel microspheres may be dried to obtain water-free straw@nano-gold photothermal microspheres.

[0160] Embodiment 14

[0161] A method for preparing bio-based photothermal microspheres comprises the following steps:

[0162] (1) Add 3 g of glacial acetic acid and 45 g of deionized water into a 100 ml beaker, then add 2 g of chitosan and 0.1 g of nano-gold, and stir until uniformly dispersed to obtain a chitosan nano-gold solution with a nano-gold content of 0.2%;

[0163] (2) The chitosan nanogold solution prepared in step (1) was placed in a 50 ml syringe, and microspheres were prepared by coaxial airflow shearing method; wherein: the inner and outer needle tube combination was 16G / 27G (flush), the injection pressure was 0.18 MPa, and the gas flow rate was controlled at 1.8 L / min; ethanol was used as the coagulation bath to prepare chitosan@nanogold photothermal gel microspheres.

[0164] Furthermore, the chitosan@nano-gold photothermal gel microspheres may be dried to obtain water-free chitosan@nano-gold photothermal microspheres.

[0165] Example 15 Test of light absorption performance of bio-based photothermal gel microspheres

[0166] The bio-based photothermal gel microspheres obtained in Examples 1, 5, and 9 were tested for their light absorption performance at 220-1400 nm. The experimental results are as follows: Figure 4 As shown. Figure 4 It can be seen that the average photothermal conversion efficiency of the photothermal gel microspheres prepared by the present invention is greater than 99%.

[0167] Example 16 Indoor water evaporation experiment of bio-based photothermal gel microspheres

[0168] The bio-based photothermal gel microspheres obtained in Examples 1, 5, and 9 were respectively measured for their indoor water evaporation rate and corresponding temperature rise curve under a solar equivalent light intensity. The specific method is as follows: the photothermal gel microspheres were placed in a plastic beaker wrapped with foam on the outer layer, and then a solar light source simulator was used to irradiate vertically and maintain the light intensity at 1 solar equivalent (100 mw / cm 2 ). During the experiment, the infrared camera was used to monitor the temperature change of the sample over time and take corresponding infrared photos. The bottom balance was used to monitor the mass reduction, i.e., the evaporation amount, in real time. The experimental results are shown in Figure 2. Figure 5 As shown. Figure 5 It can be seen that the photothermal gel microspheres prepared by the present invention have good photothermal effect. Under the light intensity of 1 sun equivalent, the temperature can be rapidly increased to more than 30°C within 10 minutes, and the final temperature can reach above 45°C. In addition, they have a high evaporation rate, among which the evaporation rate of Cell@CNT photothermal gel microspheres is the fastest, and its evaporation rate after stabilization is as high as 2.03kg.m -2 .h -1 .

[0169] Example 17 Bio-based photothermal gel microspheres for outdoor portable water collection

[0170] The bio-based photothermal gel microspheres obtained in Example 1 were used to obtain fresh water through a portable water collection device under outdoor sunlight on a sunny day (average light intensity of 0.55 solar equivalents), and the specific method was as follows: Figure 6 As shown in (a), a water collection device and a water storage tank are built by using organic glass plates or glass rods, AB glue, hot melt adhesive and other materials. The sewage tank is placed in the water collection device and a porous plastic plate (300mm×300mm) is placed on the sewage tank. Water-absorbing paper and the photothermal gel microspheres prepared in Example 1 are laid on the top in sequence, and wastewater is added. The experiment was carried out in an open area during a clear day. The wastewater volatilized through the photothermal effect and condensed on the glass plate and slid into the pre-prepared plastic water guide tank (cold water tank) and finally slid into the collection bottle (see Figure 6 (a)). From Figure 6 It can be seen from (b) that from 8:00 to 18:00, the water collection capacity per unit area of ​​the water collection device constructed by the photothermal microspheres prepared in Example 1 reached 4.60 kg.m -2 , and the evaporation rate per unit area reached a peak of 0.72 kg.m at 13:00. -2 .h -1 This indicates that the bio-based photothermal gel microspheres prepared by the present invention have a high water collection capacity.

[0171] Example 18 Shape Adaptation of Bio-based Photothermal Gel Microspheres

[0172] The bio-based photothermal gel microspheres obtained in Example 1 were compression molded by two different molds to obtain different shapes (see Figure 7 ).

[0173] Example 19 Antibacterial Experiment of Bio-based Photothermal Gel Microspheres

[0174] Take the bio-based photothermal gel microspheres (Cell@PPy) obtained in Example 1 as an example. 0.01g of Cell@PPy bio-based photothermal gel microspheres obtained in Example 1 were placed in a small glass bottle, 160μL of PBS solution with pH=7.4 was added, and then 40μL of Escherichia coli / Staphylococcus aureus solution (OD=1) was added and mixed evenly. The mixed solution was illuminated under near-infrared light for 15min (light intensity was 2W / cm 2 After the illumination, 10 μL of the solution was taken and diluted 10,000 times in PBS solution, then plated, the colonies were counted, and the inhibition rate was calculated.

[0175] Wherein: inhibition rate = (1-number of colonies in the experimental group / number of colonies in the control group) × 100%.

[0176] The control group was pure cellulose microspheres obtained in step (2) of Example 1. Figure 8 As shown in the figure, it can be seen that the photothermal microspheres prepared by the present invention have good inhibition rates on Escherichia coli and Staphylococcus aureus, and the inhibition rates are (98.77±0.28)% and (98.94±0.42)%, respectively.

[0177] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing microspheres for collecting clean water from ambient water using solar energy to obtain fresh water, It is characterized in that The preparation method comprises the following two methods: The first method comprises the following steps: dispersing the spherical particulate bio-based material in a solvent, adding a photothermal polymer material monomer, and preparing the microspheres by in-situ polymerization; or dispersing the spherical particulate bio-based material in a solvent, adding a photothermal polymer material, and the photothermal polymer material is adsorbed on the surface of the bio-based material to prepare the microspheres; The spherical granular bio-based material is prepared by a method comprising the following steps: dissolving the bio-based material in a solvent, and obtaining the spherical granular bio-based material by a coaxial airflow shearing method; The second method comprises the following steps: preparing the microspheres by blending a bio-based material solution with a photothermal conversion material; The blending process specifically adopts at least one of an emulsion method, a membrane emulsion method, a falling ball method, a vibration granulation method, a microfluidics method, an ultrasonic atomization method, a shear jet method, a piezoelectric ball making method, an electrostatic ball making method, and a coaxial airflow shearing method; The microspheres include bio-based materials and photothermal conversion materials; The photothermal conversion material is selected from at least one of plasmon metal particles, carbon-based materials and photothermal polymer materials; The bio-based material is derived from biomass natural polymer materials, and the biomass natural polymer materials are selected from one or more of the following substances: cellulose, starch, lignin, chitosan, chitin, hemicellulose, glucan, low-quality cellulose and / or natural plant tissue containing one or more of the above components; In the microspheres, the loading amount of the photothermal conversion material is 0.01-0.1 wt.%; The average particle size of the microspheres is 1 μm-3 mm; The light absorption efficiency of the microspheres is ≥99.0%; The water evaporation rate of the microsphere under one solar equivalent is ≥2.0 kg.m -2 .h -1 .

2. The method for preparing microspheres according to claim 1, It is characterized in that The average particle size of the microspheres is 100 μm-1 mm.

3. The method for preparing microspheres according to claim 1, It is characterized in that The light absorption efficiency of the microspheres is ≥99.5%.

4. The method for preparing microspheres according to claim 1, It is characterized in that The photothermal conversion efficiency of the microspheres is greater than 85%.

5. The method for preparing microspheres according to claim 4, It is characterized in that The photothermal conversion efficiency of the microspheres is greater than 92%.

6. A method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The microspheres contain water or do not contain water; wherein the microspheres containing water are bio-based gel microspheres.

7. A method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The plasmon metal particles include at least one of plasma gold, plasma silver, and plasma copper; And / or, the carbon-based material includes at least one of carbon nanotubes, graphite, carbon black, graphene, and graphene oxide; And / or, the photothermal polymer material includes at least one of polypyrrole, polydopamine, polythiophene, and polyaniline.

8. The method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that When the photothermal conversion material is selected from a photothermal polymer material, the microsphere has a core-shell structure, the core includes the bio-based material, and the shell includes the photothermal conversion material.

9. The method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The cellulose is selected from microcrystalline cellulose, bacterial cellulose, and at least one of cellulose extracted from cotton pulp, wood pulp, bamboo pulp, straw pulp, refined cotton, absorbent cotton, cotton linters, bagasse, wood and straw; And / or, the starch is selected from at least one of amylopectin, amylose, high-amylose starch, modified starch, and cross-linked starch; And / or, the deacetylation degree of the chitosan is 50-100%; And / or, the lignin is selected from at least one of syringyl lignin, guaiacyl lignin and p-hydroxyphenyl lignin.

10. The method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The starch is selected from soluble starch, and the soluble starch is selected from α-starch.

11. The method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The starch is selected from at least one of potato starch, corn starch, cassava starch, wheat starch, sweet potato starch, kudzu starch, pea starch, water chestnut starch, soybean starch and lotus root starch.

12. The method for preparing microspheres according to any one of claims 1 to 5, It is characterized in that The lignin is selected from at least one of alkaline lignin, acidic lignin, dealkalized lignin, and lignin dissolved by an organic solvent.

13. Use of the microspheres prepared by the method for preparing microspheres according to any one of claims 1 to 12 in collecting clean water from ambient water using solar energy to obtain fresh water.

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