Porous floating type evaporator based on dynamic rotary self-cleaning and preparation method and application of porous floating type evaporator

Abstract

The invention discloses a porous floating type evaporator based on dynamic rotation self-cleaning and a preparation method and application thereof, and belongs to the technical field of solar driving interface photo-thermal evaporation. The porous floating type evaporator comprises a spherical aerogel carrier and a TiN / TiO2-X composite material loaded on the surface of the spherical porous aerogel carrier, the TiN / TiO2-X composite material is composed of TiN nano-particles and TiO2-X growing on the surfaces of the TiN nano-particles in situ. A TiN / TiO2-X composite material is used as a photo-thermal / photo-catalytic activity center, and triple functions of efficient seawater desalination, volatile organic pollutant degradation and salt crystallization self-falling are realized through a three-dimensional through pore network structure and dynamic fluid mechanics characteristics in a spherical aerogel microsphere carrier. The method is particularly suitable for long-term stable treatment of high-salinity and high-organic-matter polluted water, and an innovative solution is provided for marine environment protection and water resource recycling.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar-driven interfacial photothermal evaporation, and particularly relates to a porous floating evaporator based on dynamic rotation self-cleaning, a preparation method thereof, and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] The problems of freshwater resource shortage and water body pollution are becoming increasingly severe, and the development of efficient and low-energy-consuming water treatment technologies has become a current research hotspot. The interfacial photothermal evaporation technology has attracted much attention because it uses renewable solar energy to achieve water evaporation, but the existing technologies still face many challenges.

[0004] On the one hand, the porosity of traditional carrier materials (such as polymer foams, carbon-based materials, etc.) is limited, and in the preparation process, they mostly rely on chemical crosslinking agents to form a three-dimensional network structure. The use of chemical crosslinking agents is likely to cause secondary pollution.

[0005] On the other hand, most of the existing photothermal evaporators with both seawater desalination and water pollutant degradation functions use physical mixing or simple stacking methods to compound light-absorbing materials and photocatalysts, resulting in weak interfacial binding force and low light absorption-catalysis synergistic efficiency. For example: Although the TiN material has excellent broadband light absorption characteristics (300 - 2500 nm), it lacks photocatalytic activity itself; while TiO2, although a classic photocatalyst, is limited by the wide bandgap (3.1 eV), resulting in low visible light utilization rate and high photogenerated carrier recombination rate. The light absorption characteristics and photocatalytic activity of the photothermal evaporator prepared by simply compounding the two are reduced.

[0006] Thirdly, during the process of seawater desalination, salt crystallization causes surface contamination of the photothermal evaporator, and the presence of salt crystallization hinders the escape of water vapor and the absorption of light energy, significantly reducing the long-term operating efficiency of the photothermal evaporator. The problem of salt contamination has become a key bottleneck restricting the practical application of photothermal evaporation technology. Patent CN119075847A discloses a three-dimensional photothermal evaporator, including a polyimide aerogel and TiN nanoparticles loaded on the aerogel. This patent makes the polyimide aerogel have vertically connected pores through a unidirectional freezing technique, facilitating the radial transportation of water and improving the water transportation performance of the three-dimensional photothermal evaporator. However, the inventors found that although this three-dimensional photothermal evaporator has vertically connected pores compared with the two-dimensional photothermal evaporation film, the pore structure is not easily blocked by salt crystallization and has a long service life. However, in the actual application process, with the increase of the operating time, the inevitable salt crystallization will still cause surface contamination, and the salt crystallization blocks or partially blocks the pore structure, hindering the escape of water vapor and the absorption of light energy, reducing the photothermal evaporation rate. This three-dimensional photothermal evaporator needs to solve the problem of salt crystallization through special hydrophobic treatment or periodic cleaning, which often increases the system complexity, reduces the solar energy utilization efficiency, and increases the maintenance cost. Summary of the Invention

[0007] To solve the deficiencies of the prior art, the purpose of the present invention is to provide a porous floating evaporator based on dynamic rotation self-cleaning, its preparation method and application. The porous floating evaporator provided by the present invention can achieve three functions of efficient seawater desalination, degradation of volatile organic compounds (VOCs), and self-shedding of salt crystallization, and is particularly suitable for the long-term stable treatment of high-salinity and highly organic-polluted water bodies, providing an innovative solution for marine environmental protection and water resource recycling.

[0008] To achieve the above purpose, the technical solution of the present invention is as follows:

[0009] The first aspect of the present invention provides a porous floating evaporator based on dynamic rotation self-cleaning, including a spherical aerogel carrier and TiN / TiO 2-X composite material loaded on the surface of the spherical porous aerogel carrier;

[0010] The TiN / TiO 2-X composite material is composed of TiN nanoparticles and TiO 2-X grown in-situ on its surface.

[0011] In some embodiments of the present invention, the mass fraction of the TiN / TiO 2-X composite material in the porous floating evaporator is 5-10%, preferably 8-9%.

[0012] In some embodiments of the present invention, the TiO 2-X in the TiN / TiO2-X The mass fraction in the composite material is 80 - 90%, preferably 80 - 85%.

[0013] In some embodiments of the present invention, the TiO 2-X X in it takes a value of 0.2 - 0.3.

[0014] In some embodiments of the present invention, the spherical aerogel carrier is sodium alginate aerogel microspheres, with a particle size of 1 - 10 mm and a porosity of 50 - 90%.

[0015] The second aspect of the present invention provides a preparation method of the above-mentioned porous floating evaporator based on dynamic rotation self-cleaning, including:

[0016] In-situ grow titanium dioxide on the surface of TiN nanoparticles to obtain a TiN / TiO2 composite material;

[0017] Mix the TiN / TiO2 composite material with sodium borohydride (NaBH4) and calcine it under a protective atmosphere to obtain a TiN / TiO 2-X composite material;

[0018] Load the TiN / TiO 2-X composite material on the surface of the spherical aerogel carrier to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0019] In some embodiments of the present invention, the in-situ growth of titanium dioxide on the surface of TiN nanoparticles includes:

[0020] Disperse TiN nanoparticles in a solvent, add tetrabutyl titanate dropwise, and mix evenly to obtain a dispersion;

[0021] Perform a hydrothermal reaction on the dispersion, cool it and separate the solid and liquid after the reaction to obtain a precipitate. Wash and dry the precipitate to obtain a TiN / TiO2 composite material.

[0022] Preferably, the solvent is a mixed solution of acetic acid and N,N-dimethylformamide with a volume ratio of 1 - 3:2 - 5. Further preferably, the dosage ratio of the TiN nanoparticles to the solvent is 0.05 - 0.3 g:35 - 45 mL.

[0023] Preferably, for the hydrothermal reaction, the reaction temperature is 180 - 220 °C and the reaction time is 8 - 12 h.

[0024] In some embodiments of the present invention, the mass ratio of the TiN / TiO2 composite material to sodium borohydride is 3 - 5:1 - 2.

[0025] In some embodiments of the present invention, the calcination is as follows: heating to 400 - 500 °C at a rate of 4 - 6 °C / min and calcining for 1 - 3 hours.

[0026] Preferably, after the calcination, it is cooled to room temperature, washed to remove the residual boride, and dried to obtain the TiN / TiO 2-X composite material.

[0027] In some embodiments of the present invention, the spherical aerogel carrier is sodium alginate aerogel microspheres;

[0028] The loading of the TiN / TiO 2-X composite material on the surface of the spherical aerogel carrier includes:

[0029] Adding the TiN / TiO 2-X composite material and calcium carbonate powder to the sodium alginate hydrogel solution, mixing evenly to obtain a mixed solution;

[0030] Under stirring conditions, dropping the mixed solution into the hydrochloric acid solution. After the dropping is completed, stirring and crosslinking are carried out, filtering and washing until neutral, and freeze-drying to obtain a porous floating evaporator based on dynamic rotary self-cleaning.

[0031] Preferably, the mass ratio of sodium alginate, TiN / TiO 2-X composite material and calcium carbonate powder is 10 - 15:1:10 - 15.

[0032] Preferably, the particle size of the calcium carbonate powder is less than 5 μm.

[0033] Preferably, the pH of the hydrochloric acid solution is 2.

[0034] Preferably, the dropping speed of the mixed solution is 50 - 90 rpm, preferably 70 rpm, and the stirring speed is 450 - 550 rpm.

[0035] Preferably, the stirring and crosslinking time is 5 - 10 h.

[0036] Preferably, after washing until neutral, the solvent in the pores of the microspheres is replaced with a 25 - 35 wt% ethanol solution, and then freeze-drying is carried out to obtain a porous floating evaporator based on dynamic rotary self-cleaning.

[0037] In the third aspect of the present invention, there is provided an application of the above-mentioned porous floating evaporator based on dynamic rotary self-cleaning or the porous floating evaporator based on dynamic rotary self-cleaning prepared by the above-mentioned preparation method in seawater desalination and / or degradation of volatile organic pollutants.

[0038] The beneficial effects of the present invention are as follows:

[0039] The present invention provides a porous floating evaporator based on dynamic rotation self-cleaning, which has efficient solar energy utilization, dual pollutant treatment, and a self-cleaning mechanism (self-rotation self-cleaning function). TiO 2-X Compared with TiO2, it broadens the light response range, and after being compounded with TiN nanoparticles, it improves the synergistic efficiency of photothermal and photocatalysis. Through the synergistic effect of the broad-spectrum light absorption of TiN nanoparticles and the visible light response of TiO 2-X , the maximum utilization of solar energy is achieved, and the evaporation efficiency reaches 1.5-2 times that of traditional photothermal materials, realizing low-energy seawater desalination. While achieving efficient seawater desalination, the porous floating evaporator can degrade VOCs pollutants in water through the enhanced photocatalytic activity of TiO 2-X , realizing the coordinated treatment of pollutants of "killing two birds with one stone". The porous floating evaporator based on dynamic rotation self-cleaning provided by the present invention has strong environmental adaptability, and can operate stably and efficiently in complex water bodies with different salinities (0-20 wt%), different pH values (3-11), and different organic pollutant contents, and has broad application prospects. The present invention uses spherical aerogel as a carrier, and the unique spherical structure design enables the microspheres to automatically rotate under the combined action of gravity, surface tension, and buoyancy, prompting the surface salt crystals to peel off and fall back into the water, realizing the active shedding of surface salt crystals, fundamentally solving the problem of salt pollution, and achieving continuous and efficient operation breakthroughly, overcoming the "salt pollution" bottleneck in the prior art.

[0040] The preparation process of the porous floating evaporator provided by the present invention is simple, adopting a green preparation route combining hydrothermal method and bubble template method. The raw materials are easy to obtain and the process is simple, which is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0042] Figure 1 Photocatalytic degradation curves of phenol by the porous floating evaporators prepared in Example 1, Comparative Example 1, and Comparative Example 2 of the present invention (a) and degradation curves of 4-fluorophenol, 4-chlorophenol, and 4-bromophenol by the porous floating evaporator prepared in Example 1 of the present invention (b);

[0043] Figure 2 Schematic structural diagram of the solar-driven evaporation performance test device used in Experimental Example 2 of the present invention (a) and evaporation rates of the porous floating evaporators prepared in Example 1, Comparative Example 1, and Comparative Example 2 (b);

[0044] Figure 3 Self-cleaning process of the porous floating evaporator prepared in Example 1 of the present invention;

[0045] Figure 4 For the evaluation of the water purification ability of the porous floating evaporator prepared in Example 1 of the present invention, where a is the structural diagram of the evaporation device, b is the growth of Escherichia coli when the purified condensed water is used to culture Escherichia coli, c is the growth of wheat when the purified condensed water is used to culture wheat, and d is the germination situation and germination length of wheat seeds when the purified condensed water is used to culture wheat for 7 consecutive days. Detailed implementation manners

[0046] In view of the problems of low light absorption-catalysis synergistic efficiency, the use of chemical cross-linking agents in porous carriers, and salt pollution existing in existing photothermal evaporators, the present invention proposes a porous floating evaporator based on dynamic rotation self-cleaning, its preparation method and application.

[0047] The first typical implementation manner of the present invention provides a porous floating evaporator based on dynamic rotation self-cleaning, including a spherical aerogel carrier and a TiN / TiO 2-X composite material loaded on the surface of the spherical aerogel carrier;

[0048] The TiN / TiO 2-X composite material is composed of TiN nanoparticles and TiO 2-X grown in-situ on its surface.

[0049] The porous floating evaporator provided by the present invention takes the TiN / TiO 2-X composite material as the core. Specifically, taking TiN nanoparticles as the photothermal active center and the defect-type TiO 2-X grown in-situ on the surface as the photocatalytic active center. The surface of TiO 2-X is rich in oxygen vacancies, the band gap is reduced from 3.1 eV to about 3.06 eV, significantly improving the visible light response ability and charge separation efficiency, enhancing the absorption-catalysis synergistic efficiency, realizing the maximum utilization of solar energy, making the evaporation efficiency reach 1.5-2 times that of traditional photothermal materials, and realizing low-energy consumption seawater desalination. And while realizing efficient seawater desalination production, the enhanced photocatalytic activity of TiO 2-X is used to degrade VOCs pollutants in water, realizing the synergistic treatment of pollutants of "killing two birds with one stone". And the unique spherical aerogel carrier structure design and surface mechanical properties enable the porous floating evaporator based on dynamic rotation self-cleaning to rotate spontaneously during operation, realizing the active shedding of surface salt crystals, and fundamentally solving the salt pollution problem.

[0050] In some embodiments of this implementation manner, the mass fraction of the TiN / TiO 2-X composite material in the porous floating evaporator is 5-10%, preferably 8-9%.

[0051] In some embodiments of this embodiment, the TiO 2-X in the TiN / TiO 2-X composite material has a mass fraction of 80-90%, preferably 80-85%.

[0052] In some embodiments of this embodiment, the value of x in the TiO 2-X is 0.2-0.3.

[0053] It can be understood that the term TiO 2-X refers to oxygen-deficient titanium dioxide, where x represents the proportion of oxygen vacancies. These oxygen vacancies can attract electrons to form oxygen vacancy ions, thereby adjusting the electronic configuration and reactivity of TiO 2-X .

[0054] The present invention does not require the particle size of the used TiN nanoparticles, and those in the nanoscale can be used because they have the LSPR effect. For example, it can be 20nm, 50nm, 500nm, etc.

[0055] In some embodiments of this embodiment, the spherical aerogel carrier is a sodium alginate aerogel microsphere with a particle size of 1-10mm, preferably 3-7mm, and specifically can be 3mm, 4mm, 5mm, 6mm or 7mm, etc., and the porosity is 50-90%, preferably 70-80%.

[0056] The sodium alginate aerogel microsphere has a three-dimensional through-channel structure inside, and its surface is uniformly loaded with TiN / TiO 2-X composite material to form a stable microsphere structure.

[0057] The porous floating evaporator based on dynamic rotation self-cleaning provided by the present invention uses TiN / TiO 2-X composite material as the photothermal / photocatalytic active center, and through the spherical sodium alginate aerogel microsphere carrier structure and dynamic hydrodynamic characteristics, it realizes the triple functions of efficient seawater desalination, degradation of volatile organic pollutants and self-shedding of salt crystals, and is especially suitable for the long-term stable treatment of high-salinity and highly organic-polluted water bodies, providing an innovative solution for marine environmental protection and water resource recycling.

[0058] The porous floating evaporator based on dynamic rotation self-cleaning of the present invention realizes the synergistic seawater desalination and VOCs degradation based on the following triple action mechanisms:

[0059] I. Efficient photothermal evaporation mechanism

[0060] TiN nanoparticles can efficiently absorb sunlight in the range of 300 - 2500 nm and convert light energy into heat (photothermal conversion efficiency > 95%), driving the rapid evaporation of water molecules on the surface of sodium alginate aerogel microspheres; the three-dimensional through-pore structure inside the sodium alginate aerogel microspheres provides efficient heat conduction and water migration channels, greatly promoting the evaporation process. The test results show that under the standard illumination of 1 sun (1 kW m -2 ), the evaporation rate per unit area can reach 1.85 kg m -2 h -1 , which is much higher than the natural evaporation rate of water (0.48 kg m -2 h -1 ).

[0061] II. Enhanced photocatalytic degradation mechanism

[0062] The oxygen vacancies in TiO 2-X not only reduce the band gap (3.2 eV → 3.06 eV), expand the light response range, but also effectively capture photogenerated electrons, inhibit the recombination of electron-hole pairs, and significantly improve the quantum efficiency. Under illumination, the photogenerated electrons (e-) and holes (h+) generated by TiO 2-X react with water and oxygen molecules to generate highly reactive oxygen species (ROS) such as superoxide radicals (·O2-) and hydroxyl radicals (·OH), and these ROS can efficiently degrade various VOCs pollutants adsorbed on the surface of the microspheres.

[0063] III. Innovative anti-salt and self-cleaning mechanism

[0064] The through-pore structure inside the sodium alginate aerogel microspheres not only accelerates the diffusion of salt ions and reduces the deposition rate of salt on the surface. More importantly, under illumination, the spherical microsphere group forms a local thermal dynamic system under the combined action of the surface tension, gravity and buoyancy of water. Specifically:

[0065] The microspheres are unevenly heated under illumination, and the temperature of the upper surface is higher than that of the lower surface;

[0066] Salt particles tend to preferentially nucleate and grow in the liquid layer with faster evaporation at the upper end of the small balls;

[0067] When the torque generated by the mass and position of the salt particles exceeds the critical value and breaks the force balance state of the small balls, the small balls rotate spontaneously;

[0068] During the rotation process, the salt particles slide back into the water body under the action of centrifugal force and gravity, completing the self-cleaning process;

[0069] Through the surface tension coupling effect, the rotation of one microsphere can trigger a chain reaction of adjacent microspheres, realizing the cooperative self-cleaning behavior of the multi-sphere system.

[0070] The second typical embodiment of the present invention provides a preparation method of the above-mentioned porous floating evaporator based on dynamic rotation self-cleaning, including:

[0071] In-situ grow titanium dioxide on the surface of TiN nanoparticles to obtain a TiN / TiO2 composite material;

[0072] Mix the TiN / TiO2 composite material with sodium borohydride and calcine it under a protective atmosphere to obtain a TiN / TiO 2-X composite material;

[0073] Load the TiN / TiO 2-X composite material on the surface of a spherical aerogel carrier to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0074] In the present invention, TiO2 is in-situ grown on the surface of TiN nanoparticles by a hydrothermal method, and then oxygen vacancies are introduced by reduction calcination with NaBH4, broadening the light response range of TiO2 and enhancing the synergistic efficiency of photothermal and photocatalysis to achieve the controllable preparation of the TiN / TiO 2-X composite material.

[0075] In some embodiments of this embodiment, the in-situ growth of titanium dioxide on the surface of TiN nanoparticles includes:

[0076] Disperse the TiN nanoparticles in a solvent, add tetrabutyl titanate dropwise, and mix evenly to obtain a dispersion;

[0077] Perform a hydrothermal reaction on the dispersion. After the reaction is completed, cool it and separate the solid and liquid to obtain a precipitate. Wash and dry the precipitate to obtain a TiN / TiO2 composite material.

[0078] In some embodiments of this embodiment, the solvent is a mixed solution of acetic acid and N,N-dimethylformamide with a volume ratio of 1-3:2-5.

[0079] In some embodiments of this embodiment, the dosage ratio of the TiN nanoparticles to the solvent is 0.05-0.3 g:35-45 mL. When the dosage of the solvent is 40 mL, the dosage of the TiN nanoparticles can be 0.05 g, 0.1 g, 0.2 g, or 0.3 g; preferably 0.2 g:40 mL.

[0080] In some embodiments of this embodiment, for the hydrothermal reaction, the reaction temperature is 180-220 °C and the reaction time is 8-12 h.

[0081] In some embodiments of this embodiment, the mass ratio of the TiN / TiO2 composite material to sodium borohydride is 3-5:1-2.

[0082] In some embodiments of this implementation manner, the calcination is as follows: heating to 400 - 500 °C at a rate of 4 - 6 °C / min and calcining for 1 - 3 hours.

[0083] In some embodiments of this implementation manner, after the calcination, it is cooled to room temperature, washed to remove the residual boride, and dried to obtain the TiN / TiO 2-X composite material.

[0084] In some embodiments of this implementation manner, the spherical aerogel carrier is sodium alginate aerogel microspheres;

[0085] The loading of the TiN / TiO 2-X composite material on the surface of the spherical aerogel carrier includes:

[0086] Adding the TiN / TiO 2-X composite material and calcium carbonate powder to the sodium alginate hydrogel solution, mixing evenly to obtain a mixed solution;

[0087] Under stirring conditions, dropping the mixed solution into the hydrochloric acid solution. After the dropping is completed, stirring and cross-linking are carried out, filtering and washing until neutral, and freeze-drying to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0088] The present invention utilizes the reaction of calcium carbonate with hydrochloric acid to generate calcium ions to cross-link sodium alginate, and simultaneously releases carbon dioxide gas to form through-holes, realizing a green preparation route without adding external cross-linking agents, and at the same time optimizing the specific surface area and liquid transmission channels of the material.

[0089] The present invention precisely controls the microsphere density, hydrophilicity and surface morphology, so that the microspheres are unevenly heated under light conditions, and under the combined action of the gravitational moment and the floating moment, spontaneous rotation is achieved, ensuring that the surface salt crystals automatically fall off, thereby realizing the long-term and efficient surface self-cleaning function.

[0090] In some embodiments of this implementation manner, the mass ratio of the sodium alginate, TiN / TiO 2-X composite material and calcium carbonate powder is 10 - 15:1:10 - 15.

[0091] In some embodiments of this implementation manner, the particle size of the calcium carbonate powder is less than 5 μm.

[0092] In some embodiments of this implementation manner, the pH of the hydrochloric acid solution is 2.

[0093] In some embodiments of this implementation manner, the dropping speed of the mixed solution is 50 - 90 rpm, preferably 70 rpm, and the stirring speed is 450 - 550 rpm, preferably 500 rpm.

[0094] It is understandable that in order to achieve precise dripping of the mixed solution, a precisely controlled delivery system can be adopted. The mixed solution is evenly dripped into the hydrochloric acid solution through a peristaltic pump, and the stirring speed is maintained at 500 rpm to ensure regular microsphere morphology and uniform size.

[0095] In some embodiments of this embodiment, the stirring and cross-linking time is 5-10 h to ensure sufficient cross-linking.

[0096] In some embodiments of this embodiment, after washing to neutrality, the solvent in the pores of the microspheres is replaced with a 25-35 wt% ethanol solution, and then freeze-dried to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0097] In some embodiments of this embodiment, the present invention provides a specific preparation method of the above-mentioned porous floating evaporator based on dynamic rotation self-cleaning, including:

[0098] Step 1: Preparation of TiN / TiO 2-X Composite material

[0099] Hydrothermal method to grow in-situ TiO2 nanostructures on the surface of TiN nanoparticles:

[0100] Disperse 0.2 g of commercial TiN nanoparticles in 40 mL of acetic acid (HAc) and N,N-dimethylformamide (DMF), slowly add tetrabutyl titanate (TBOT), and then ultrasonically treat for 30 minutes to form a homogeneous dispersion; transfer the dispersion to a 100 mL stainless steel autoclave with a Teflon liner, perform a hydrothermal reaction at 200 °C for 10 hours, cool to room temperature, centrifuge at 8000 rpm for 30 minutes, wash three times with absolute ethanol, and vacuum dry at 60 °C for 12 hours to obtain TiN / TiO2 composite nanomaterials.

[0101] NaBH4 reduction calcination to introduce oxygen vacancies:

[0102] Mix the above TiN / TiO2 composite material with NaBH4 evenly according to a mass ratio of 4:1, place it in a quartz tube furnace, first purge with high-purity N2 (99.999%) for 30 minutes, and then calcine at 450 °C for 2 hours under the protection of continuous N2 flow (50 mL / min) at a heating rate of 5 °C / min; take it out after natural cooling to room temperature, soak it in ultrapure water for 24 hours, wash it thoroughly three times to remove residual borides, and freeze-dry at -50 °C for 48 hours to obtain oxygen vacancy-rich TiN / TiO 2-X Composite material.

[0103] Step 2: Preparation of porous sodium alginate microspheres loaded with TiN / TiO 2-X

[0104] Preparation of functional mixed solution:​

[0105] Sodium alginate (SA) was dissolved in ultrapure water and mechanically stirred for 12 hours until completely dissolved to form a transparent gel; subsequently, TiN / TiO 2-X composite material and finely ground CaCO3 powder (particle size <5 μm) were added, and stirring was continued for 2 hours. Subsequently, ultrasonic treatment was carried out for 30 minutes to ensure uniform dispersion of the components and form a stable mixed solution.

[0106] Dynamic crosslinking and bubble template pore formation:

[0107] Using a precisely controlled dropping system, the above mixed solution was uniformly dropped into a hydrochloric acid solution with pH = 2 through a peristaltic pump, and the stirring speed was maintained at 500 rpm to ensure regular microsphere morphology and uniform size.

[0108] In-situ reaction mechanism of CaCO3 and HCl:

[0109] CaCO3 + 2HCl → CaCl2 + CO2↑ + H2O

[0110] During this reaction process, the generated Ca 2+ ions reacted with the carboxyl functional groups in the SA macromolecules to form a stable spherical network structure; at the same time, the released CO2 gas formed microbubbles inside the microspheres, gradually grew and connected with each other as the reaction proceeded, and finally formed a continuous porous structure.

[0111] After the dropping process of the mixed solution was completed, the reaction system continued to crosslink in an acidic environment for 8 hours to ensure sufficient crosslinking; subsequently, it was thoroughly washed with ultrapure water until neutral (pH = 7 ± 0.2), and the water in the microsphere pores was gradually replaced with a 30 wt% ethanol solution to protect the pore structure. Finally, it was freeze-dried at -50°C for 72 hours to obtain porous SA aerogel microspheres with TiN / TiO 2-X loaded on the surface, named TiN / TiO 2-X @SA.

[0112] The third typical embodiment of the present invention provides an application of the above-mentioned porous floating evaporator based on dynamic rotation self-cleaning or the porous floating evaporator prepared by the above-mentioned preparation method in seawater desalination and / or degradation of volatile organic pollutants.

[0113] In order to enable those skilled in the art to more clearly understand the technical solutions of the present invention, the technical solutions of the present invention will be described in detail below with specific embodiments.

[0114] All raw materials used in the following experiments are conventional commercially available products and can be obtained by purchase.

[0115] Example 1

[0116] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, comprising the following steps:

[0117] Step 1: Preparation of TiN / TiO 2-X Composite material

[0118] Hydrothermal method to grow in-situ TiO2 nanostructures on the surface of TiN nanoparticles:

[0119] Disperse 0.2 g of commercial TiN nanoparticles (particle size of 20 nm) in 40 mL of a mixed solution of acetic acid and N,N-dimethylformamide with a volume ratio of 2:3, slowly add 2 mL of tetrabutyl titanate, and then perform ultrasonic treatment for 30 minutes to form a homogeneous dispersion; transfer the dispersion to a 100 mL stainless steel autoclave lined with Teflon, carry out hydrothermal reaction at 200 °C for 10 hours, cool to room temperature, centrifuge at 8000 rpm for 30 minutes, wash three times with absolute ethanol, and vacuum dry at 60 °C for 12 hours to obtain TiN / TiO2 composite nanomaterials.

[0120] NaBH4 reduction calcination to introduce oxygen vacancies:

[0121] Mix the above TiN / TiO2 composite material and NaBH4 evenly according to a mass ratio of 4:1, place it in a quartz tube furnace, first purge with high-purity N2 (99.999%) for 30 minutes, and then heat to 450 °C at a rate of 5 °C / min under the protection of continuous N2 flow (50 mL / min) and calcine for 2 hours; take it out after natural cooling to room temperature, soak in ultrapure water for 24 hours and wash three times thoroughly to remove residual borides, and obtain TiN / TiO 2-X Composite material. After testing, in the obtained TiN / TiO 2-X Composite material, the mass percentage of TiO 2-X is 83%, and x is 0.24.

[0122] Step 2: Preparation of porous sodium alginate microspheres loaded with TiN / TiO 2-X Composite material

[0123] Preparation of functional mixed solution:

[0124] Dissolve 3 g of sodium alginate in 100 mL of ultrapure water, and mechanically stir for 12 hours until completely dissolved to form a transparent gel; then add 0.25 g of TiN / TiO 2-X Composite material and 3 g of finely ground CaCO3 powder (particle size <5 μm), continue to stir for 2 hours, and then perform ultrasonic treatment for 30 minutes to ensure uniform dispersion of the components and form a stable mixed solution.

[0125] Dynamic cross-linking and bubble template pore formation:

[0126] The above-mentioned mixed solution was evenly dropped into a hydrochloric acid solution with pH = 2 by a peristaltic pump at a dropping rate of 70 rpm, and the stirring speed was maintained at 500 rpm. After the dropping process of the mixed solution was completed, the reaction system continued to be stirred and cross-linked in an acidic environment for 8 hours to ensure sufficient cross-linking; then it was thoroughly washed with ultrapure water until neutral (pH = 7 ± 0.2), and the water in the pores of the microspheres was replaced with a 30 wt% ethanol solution in a gradient manner to protect the pore structure. Finally, it was freeze-dried at -50 °C for 72 hours to obtain porous sodium alginate aerogel microspheres with TiN / TiO 2-X loaded on the surface, namely the porous floating evaporator based on dynamic rotation self-cleaning, named TiN / TiO 2-X @SA. After detection, in the obtained TiN / TiO 2-X @SA, the mass percentage of the TiN / TiO 2-X composite material was 8.7%.

[0127] Example 2

[0128] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that: 0.05 g, 0.1 g or 0.3 g of commercial TiN nanoparticles (particle size of 20 nm) were dispersed in 40 mL of a mixed solution of acetic acid and N,N-dimethylformamide with a volume ratio of 2:3. The remaining steps were the same as those in Example 1.

[0129] Example 3

[0130] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that: the TiN / TiO2 composite material and NaBH4 were mixed evenly at a mass ratio of 1:1 or 1:2. The remaining steps were the same as those in Example 1.

[0131] Example 4

[0132] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that: the particle size of the commercial TiN nanoparticles was 200 nm. The remaining steps were the same as those in Example 1.

[0133] Example 5

[0134] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that: 2.5 g or 3.75 g of sodium alginate was dissolved in ultrapure water and mechanically stirred for 12 hours until completely dissolved to form a transparent gel; then 0.25 g of TiN / TiO 2-X composite material and 3 g of finely ground CaCO3 powder (particle size < 5 μm) were added. The remaining steps were the same as those in Example 1.

[0135] Example 6

[0136] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that: 3 g of sodium alginate is dissolved in ultrapure water and mechanically stirred for 12 hours until completely dissolved to form a transparent gel; then 0.25 g of TiN / TiO 2-X composite material and 2.5 g or 3.75 g of finely ground CaCO3 powder (particle size <5 μm) are added. The remaining steps are the same as those in Example 1.

[0137] Comparative Example 1

[0138] A preparation method of a porous floating evaporator based on dynamic rotation self-cleaning, which is different from Example 1 in that it does not contain the step of "introducing oxygen vacancies by NaBH4 reduction calcination", and the remaining steps are the same as those in Example 1. Porous sodium alginate aerogel microspheres with TiN / TiO2 loaded on the surface are obtained, that is, a porous floating evaporator based on dynamic rotation self-cleaning, named TiN / TiO2@SA.

[0139] Experimental Example 1: Photocatalytic degradation performance curves of different samples for VOCs

[0140] Accurately weigh 25.0 ± 0.2 mg of photocatalyst (TiN, TiN / TiO2 and TiN / TiO 2-X ) and disperse it evenly in 50 mL of phenol solution (5.00 ± 0.05 mg / L) by ultrasonic (40 kHz, 30 min). A 300 W xenon lamp light source (AM 1.5 filter, light intensity 100 mW / cm 2 ) is used to simulate sunlight irradiation, and the temperature of the reaction system is controlled at 25 ± 1 °C by a circulating water bath. Samples are taken at regular intervals and the catalyst is removed by centrifugation, and the concentration of VOCs is detected by high performance liquid chromatography (HPLC, Agilent 1260) (detection limit 0.01 mg / L).

[0141] The detection results are as shown in Figure 1 Figure a in, TiN / TiO 2-X shows the best degradation performance. The degradation rate of phenol reaches 95.2% within 6 h, and the residual phenol concentration after treatment drops to 0.24 mg / L, which is lower than the limit of 0.5 mg / L specified in the Comprehensive Wastewater Discharge Standard (GB 8978-1996).

[0142] Accurately weigh 25.0 ± 0.2 mg of photocatalyst (TiN / TiO 2-X ) and disperse it evenly in 50 mL of 4-fluorophenol, 4-chlorophenol and 4-bromophenol solution (5.00 ± 0.05 mg / L) by ultrasonic (40 kHz, 30 min). A 300 W xenon lamp light source (AM1.5 filter, light intensity 100 mW / cm2 )Simulate sunlight irradiation, and control the temperature of the reaction system at 25 ± 1 °C through a circulating water bath. Sample at regular intervals and centrifuge to remove the catalyst, and detect the VOCs concentration (detection limit 0.01 mg / L) by high performance liquid chromatography (HPLC, Agilent 1260).

[0143] The detection results are as shown in Figure 1 Figure b in 2-X TiN / TiO 2-X showed significant degradation ability for phenol derivatives with different substituents. The degradation efficiencies of TiN / TiO

[0144] Experimental Example 2: Photothermal evaporation performance of TiN / TiO 2-X @SA microspheres

[0145] The solar-driven evaporation performance test was carried out using a self-made experimental device ( Figure 2 Figure a in). TiN / TiO 2-X @SA microspheres float on the water surface, and their evaporation performance was tested under simulated sunlight (AM 1.5). The water evaporation amount was monitored in real time through the PortScribe software connected to an electronic balance and a computer. Under the irradiation condition of 1 sun intensity (1 kW·m -2 ), the real-time evaporation data within 180 minutes were continuously recorded.

[0146] As shown in Figure 2 Figure b in, the evaporation rate of pure water is 0.48 kg·m -2 ·h -1 , while the evaporation rates of pure SA, TiN / TiO2@SA, and TiN / TiO 2-X @SA are 0.73 kg·m -2 ·h -1 , 1.37 kg·m -2 ·h -1 and 1.85 kg·m -2 ·h -1 . This data indicates that under the same experimental conditions, due to the enhanced light absorption characteristics, TiN / TiO 2-X @SA microspheres showed significantly improved evaporation performance compared with the blank control group and TiN / TiO2@SA.

[0147] Experimental Example 3: Self-cleaning process of TiN / TiO 2-X @SA microspheres

[0148] Observe the TiN / TiO 2-X @SA microspheres on the surface of Experimental Example 2, asFigure 3 As shown, the self-cleaning process is divided into four steps:

[0149] Under light illumination, salt particles tend to preferentially nucleate and grow in the liquid layer with a faster evaporation rate at the upper end of the small ball.

[0150] When the torque generated by the mass and position of the salt particles exceeds the critical value and breaks the force balance state of the small ball, the No. 5 microsphere undergoes spontaneous rotation.

[0151] Through the surface tension coupling effect, the rotation of one microsphere can trigger a chain reaction of adjacent microspheres (No. 1, 2, 3, 4, 6, 7 microspheres), realizing the collaborative self-cleaning behavior of the multi-sphere system.

[0152] During the rotation process, the salt particles slide back into the water body under the action of centrifugal force and gravity, thus completing the dynamic self-cleaning process.

[0153] Experimental Example 4: TiN / TiO 2-X Evaluation of the water purification ability of @SA microspheres

[0154] Using phenol solution and seawater as the objects to be purified, the condensed water collected by the evaporation device shown in Figure a in Figure 4 was used. The collected condensed water was used to cultivate wheat and Escherichia coli to evaluate the water purification effect of TiN / TiO 2-X @SA microspheres. During the cultivation process of wheat and Escherichia coli, tap water was used as the control group.

[0155] As Figure 4 shown in Figure b, no Escherichia coli strains were observed in the culture medium containing phenol, and a small number of strains were observed in seawater. However, a large number of strains were observed in the purified water (the seawater containing phenol was purified), and the number of colonies was about 20 times that in seawater and was comparable to the number of Escherichia coli colonies cultured with tap water. This indicates that the TiN / TiO 2-X @SA evaporation system has excellent purification effect on high-salinity wastewater containing VOCs.

[0156] In addition, the germination situation and germination length of wheat seeds were compared by continuously cultivating wheat for 7 days. As Figure 4 shown in Figures c and d, wheat seeds did not germinate in phenol and seawater, while the malt could grow to 92 ± 7 mm within 7 days in the purified wastewater, which was comparable to the malt length cultured with tap water. This also indicates that the TiN / TiO 2-X @SA evaporation system has excellent purification effect on high-salinity wastewater containing VOCs and has a long service life.

[0157] The porous floating evaporators obtained in Examples 2-6 were subjected to performance testing using the methods of Experimental Examples 1-4. After testing, the porous floating evaporators obtained in Examples 2-6 had similar performance to the porous floating evaporator obtained in Example 1, and the photocatalytic degradation performance, photothermal evaporation performance, self-cleaning, and water purification ability of VOCs were all superior to those of the porous floating evaporator obtained in Comparative Example 1.

[0158] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A porous floating evaporator based on dynamic rotation self-cleaning, characterized in that Comprising a spherical aerogel support and TiN / TiO supported on the surface of the spherical porous aerogel support 2-X composite material; The TiN / TiO 2-X composite material consists of TiN nanoparticles and TiO 2-X formed in situ on its surface.

2. The porous floating evaporator based on dynamic rotation self-cleaning according to claim 1, characterized in that, TiN / TiO 2-X The mass fraction of the composite material in the porous floating evaporator is 5-10%, preferably 8-9%; Preferably, the TiO 2-X in the TiN / TiO 2-X composite material has a mass fraction of 80-90%, preferably 80-85%; Preferably, X in the TiO 2-X takes a value of 0.2 - 0.

3.

3. The porous floating evaporator based on dynamic rotation self-cleaning according to claim 1, characterized in that, The spherical aerogel support is a sodium alginate aerogel microsphere with a particle size of 1 - 10 mm and a porosity of 50 - 90%.

4. A preparation method of the porous floating evaporator based on dynamic rotation self-cleaning according to any one of claims 1-3, characterized in that, It includes: In-situ growth of titanium dioxide on the surface of TiN nanoparticles to obtain a TiN / TiO₂ composite material; Mix the TiN / TiO2 composite material with sodium borohydride and calcine it under a protective atmosphere to obtain the TiN / TiO 2-X composite material; Load the TiN / TiO 2-X composite material on the surface of the spherical aerogel carrier to obtain a porous floating evaporator based on dynamic rotary self-cleaning.

5. The preparation method according to claim 4, characterized in that, The in-situ growth of titanium dioxide on the surface of TiN nanoparticles includes: Disperse TiN nanoparticles in a solvent, add tetrabutyl titanate dropwise, and mix well to obtain a dispersion; Perform a hydrothermal reaction on the dispersion. After the reaction is completed, cool and separate the solid and liquid to obtain a precipitate. Wash and dry the precipitate to obtain a TiN / TiO₂ composite material; Preferably, the solvent is a mixed solution of acetic acid and N,N-dimethylformamide with a volume ratio of 1 - 3:2 - 5; Further preferably, the dosage ratio of TiN nanoparticles to the solvent is 0.05 - 0.3 g:35 - 45 mL; Preferably, for the hydrothermal reaction, the reaction temperature is 180 - 220 °C and the reaction time is 8 - 12 h.

6. The preparation method according to claim 4, characterized in that, The mass ratio of the TiN / TiO₂ composite material to sodium borohydride is 3 - 5:1 - 2; Preferably, the calcination is: heating to 400 - 500 °C at a rate of 4 - 6 °C / min and calcining for 1 - 3 hours; Preferably, after the calcination is completed, it is cooled to room temperature, washed to remove the residual boride, dried, and a TiN / TiO 2-X composite material is obtained.

7. The preparation method according to claim 4, characterized in that, The spherical aerogel support is a sodium alginate aerogel microsphere; The loading of the TiN / TiO 2-X composite material on the surface of the spherical aerogel support includes: Add TiN / TiO 2-X composite material and calcium carbonate powder to the sodium alginate hydrogel solution, mix well to obtain a mixed solution; Under stirring conditions, drop the mixed solution into a hydrochloric acid solution. After the dropping is completed, stir and crosslink, filter and wash until neutral, and then freeze-dry to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

8. The preparation method according to claim 7, characterized in that, The mass ratio of the sodium alginate, TiN / TiO 2-X composite material and the calcium carbonate powder is 10-15:1:10-15; Preferably, the particle size of the calcium carbonate powder is less than 5 μm; Preferably, the pH of the hydrochloric acid solution is 2; Preferably, the dropping speed of the mixed solution is 50 - 90 rpm, preferably 70 rpm, and the stirring speed is 450 - 550 rpm; Preferably, the stirring crosslinking time is 5 - 10 h.

9. The preparation method according to claim 7, characterized in that, After washing until neutral, replace the solvent in the pores of the microspheres with a 25 - 35 wt% ethanol solution, and then perform freeze-drying to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

10. Application of the porous floating evaporator based on dynamic rotation self-cleaning according to any one of claims 1 - 3 or the porous floating evaporator prepared by the preparation method according to any one of claims 4 - 9 in seawater desalination and / or degradation of volatile organic pollutants.

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