A porous floating evaporator based on dynamic rotating self-cleaning and a preparation method and application thereof

Abstract

The application discloses a kind of porous floating evaporator based on dynamic rotation self-cleaning and its preparation method and application, belong to solar-driven interface photothermal evaporation technical field.The porous floating evaporator, it includes spherical aerogel carrier and TiN / TiO 2‑X Composite material;TiN / TiO 2‑X Composite material is constituted by TiN nanoparticle and TiO 2‑X It is on its surface in situ growth.The TiN / TiO 2‑X Composite material is photo-thermal / photocatalytic active center, through the three-dimensional through hole network structure and dynamic fluid mechanics characteristics in the inside of spherical aerogel microsphere carrier, realize high-efficiency seawater desalination, volatile organic pollutant degradation and salt crystallization self-shedding triple function, especially applicable to high salinity, high organic pollution water body long-term stable treatment, provide innovative solution for marine environmental protection and water resource recycling.

Description

Technical Field

[0001] This invention belongs to the field of solar-driven interface photothermal evaporation technology, specifically relating to a porous floating evaporator based on dynamic rotational self-cleaning, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With the increasing severity of freshwater scarcity and water pollution, the development of efficient and low-energy-consumption water treatment technologies has become a current research hotspot. Interfacial photothermal evaporation technology has attracted much attention due to its use of renewable solar energy for water evaporation, but existing technologies still face many challenges.

[0004] On the one hand, traditional carrier materials (such as polymer foam, carbon-based materials, etc.) have limited porosity and rely heavily on chemical crosslinking agents to form a three-dimensional network structure during the preparation process. The use of chemical crosslinking agents can easily cause secondary pollution.

[0005] On the other hand, existing photothermal evaporators that simultaneously perform seawater desalination and water pollutant degradation often employ physical mixing or simple stacking to combine light-absorbing materials and photocatalysts, resulting in weak interfacial bonding and low photoabsorption-catalysis synergistic efficiency. For example, while TiN materials possess excellent broad-spectrum light absorption characteristics (300-2500 nm), they lack photocatalytic activity; and while TiO2 is a classic photocatalyst, its wide bandgap (3.1 eV) leads to low visible light utilization and high recombination rate of photogenerated carriers. The photothermal evaporator prepared by simply combining these two materials exhibits reduced light absorption characteristics and photocatalytic activity.

[0006] Thirdly, during seawater desalination, salt crystallization leads to surface contamination of the photothermal evaporator. The presence of salt crystals hinders water vapor escape and light energy absorption, significantly reducing the long-term operating efficiency of the photothermal evaporator. Salt contamination has become a key bottleneck restricting the practical application of photothermal evaporation technology. Patent CN119075847A discloses a three-dimensional photothermal evaporator, comprising polyimide aerogel and TiN nanoparticles loaded on the aerogel. This patent uses unidirectional freezing technology to create vertically connected channels in the polyimide aerogel, facilitating radial water transport and improving the water delivery performance of the three-dimensional photothermal evaporator. However, the inventors found that although this three-dimensional photothermal evaporator, compared to a two-dimensional photothermal evaporation membrane, has vertically connected channels and its pore structure is less prone to salt crystallization and has a longer service life, in actual application, with increasing operating time, the inevitable salt crystallization still leads to surface contamination. Salt crystals block or partially block the pore structure, hindering water vapor escape and light energy absorption, thus reducing the photothermal evaporation rate. The three-dimensional photothermal evaporator requires special hydrophobic treatment or periodic cleaning to solve the problem of salt crystallization, which often increases system complexity, reduces solar energy utilization efficiency, and increases maintenance costs. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a porous floating evaporator based on dynamic rotational self-cleaning, its preparation method, and its application. The porous floating evaporator provided by the present invention can achieve three functions: efficient seawater desalination, degradation of volatile organic pollutants (VOCs), and self-shedding of salt crystals. It is particularly suitable for the long-term stable treatment of water bodies with high salinity and high organic pollution, providing an innovative solution for marine environmental protection and water resource recycling.

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

[0009] A first aspect of the present invention provides a porous floating evaporator based on dynamic rotational self-cleaning, comprising a spherical aerogel support and TiN / TiO loaded on the surface of the spherical porous aerogel support. 2-X Composite materials;

[0010] The TiN / TiO 2-X The composite material consists of TiN nanoparticles and TiO2 grown in situ on their surface. 2-X constitute.

[0011] In some embodiments of the present invention, TiN / TiO 2-X The mass fraction of the 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 TiN / TiO2-X The mass fraction of the composite material is 80-90%, preferably 80-85%.

[0013] In some embodiments of the present invention, the TiO 2-X The value of X in the equation is between 0.2 and 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] A second aspect of the present invention provides a method for preparing the above-mentioned porous floating evaporator based on dynamic rotational self-cleaning, comprising:

[0016] Titanium dioxide was grown in situ on the surface of TiN nanoparticles to obtain a TiN / TiO2 composite material;

[0017] TiN / TiO2 composite material was mixed with sodium borohydride (NaBH4) and calcined under a protective atmosphere to obtain TiN / TiO2. 2-X Composite materials;

[0018] TiN / TiO 2-X The composite material was loaded onto the surface of a spherical aerogel carrier to obtain a porous floating evaporator based on dynamic rotational 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] TiN nanoparticles were dispersed in a solvent, and tetrabutyl titanate was added dropwise. The mixture was stirred to obtain a dispersion.

[0021] The dispersion undergoes a hydrothermal reaction. After the reaction is complete, the mixture is cooled and separated into solid and liquid phases to obtain a precipitate. The precipitate is then washed and dried to obtain a TiN / TiO2 composite material.

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

[0023] Preferably, the hydrothermal reaction is carried out at a temperature of 180-220℃ for 8-12 hours.

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

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

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

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

[0028] The TiN / TiO 2-X Composite materials loaded on the surface of a spherical aerogel support include:

[0029] Add TiN / TiO to sodium alginate hydrogel solution 2-X The composite material and calcium carbonate powder are mixed thoroughly to obtain a mixture.

[0030] Under stirring conditions, the mixture is added dropwise to a hydrochloric acid solution. After the addition is complete, the mixture is stirred to crosslink, filtered, washed until neutral, and freeze-dried to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0031] Preferably, the sodium alginate, TiN / TiO 2-X The mass ratio of the composite material to 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 dripping rate of the mixture is 50-90 rpm, more preferably 70 rpm, and the stirring rate is 450-550 rpm.

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

[0036] Preferably, after washing to neutrality, the solvent in the microsphere pores 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.

[0037] A third aspect of the present invention provides the application of the above-described porous floating evaporator based on dynamic rotation self-cleaning or the porous floating evaporator based on dynamic rotation self-cleaning prepared by the above-described preparation method in seawater desalination and / or degradation of volatile organic pollutants.

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

[0039] This invention provides a porous floating evaporator based on dynamic rotational self-cleaning, which features high-efficiency solar energy utilization, dual pollutant treatment, and a self-cleaning mechanism (self-rotational self-cleaning function). TiO 2-X Compared to TiO2, it broadens the photoresponse range, and when combined with TiN nanoparticles, it enhances the synergistic efficiency of photothermal and photocatalytic processes. This is achieved through the broad-spectrum light absorption of TiN nanoparticles and the combination of TiO2 with TiO2. 2-X The visible light response synergistic effect maximizes the utilization of solar energy, achieving an evaporation efficiency 1.5-2 times that of traditional photothermal materials, thus enabling low-energy seawater desalination. While achieving efficient seawater desalination, the porous floating evaporator can utilize TiO₂... 2-X This invention enhances photocatalytic activity to degrade VOCs pollutants in water, achieving a synergistic treatment of pollutants with a single action. The porous floating evaporator based on dynamic rotation and self-cleaning provided by this invention exhibits strong environmental adaptability, maintaining stable and efficient operation in complex water bodies with varying salinity (0-20wt%), pH values ​​(3-11), and organic pollutant concentrations, demonstrating broad application prospects. Using spherical aerogel as a carrier, the unique spherical structure design allows the microspheres to automatically rotate under the combined action of gravity, surface tension, and buoyancy, promoting the peeling off of surface salt crystals and their return to the water. This active removal of surface salt crystals fundamentally solves the salt pollution problem, achieving breakthrough continuous and efficient operation and overcoming the "salt pollution" bottleneck in existing technologies.

[0040] The porous floating evaporator provided by this invention has a simple preparation process, adopts a green preparation route that combines hydrothermal method and bubble template method, the raw materials are readily available, the process is simple, and it is suitable for large-scale production. Attached Figure Description

[0041] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

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

[0043] Figure 2 The diagram shows the structure of the solar-driven evaporation performance testing device used in Experimental Example 2 of the present invention (a) and the evaporation rate of the porous floating evaporator prepared in Example 1, Comparative Example 1 and Comparative Example 2 (b).

[0044] Figure 3 This describes the self-cleaning process of the porous floating evaporator prepared in Example 1 of the present invention.

[0045] Figure 4 The water purification capacity of the porous floating evaporator prepared in Example 1 of the present invention is evaluated. In the figure, a is a structural diagram of the evaporation device, b is the growth of Escherichia coli when Escherichia coli is cultured in the purified condensate, c is the growth of wheat when wheat is cultured in the purified condensate, and d is the germination and germination length of wheat seeds when wheat is cultured in the purified condensate for 7 consecutive days. Detailed Implementation

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

[0047] A first typical embodiment of the present invention provides a porous floating evaporator based on dynamic rotational self-cleaning, comprising a spherical aerogel support and TiN / TiO loaded on the surface of the spherical aerogel support. 2-X Composite materials;

[0048] The TiN / TiO 2-X The composite material consists of TiN nanoparticles and TiO2 grown in situ on their surface. 2-X constitute.

[0049] The porous floating evaporator provided by this invention uses TiN / TiO 2-X Composite materials are the core technology. Specifically, defect-type TiO₂ is grown in situ on the surface using TiN nanoparticles as photothermal active centers. 2-X TiO₂ serves as a photocatalytic active center. 2-X The surface is rich in oxygen-containing vacancies, reducing the band gap from 3.1 eV to approximately 3.06 eV, significantly improving visible light response and charge separation efficiency, enhancing absorption-catalysis synergy efficiency, maximizing solar energy utilization, and achieving evaporation efficiency 1.5-2 times that of traditional photothermal materials, thus realizing low-energy seawater desalination. Furthermore, while achieving efficient seawater desalination production, TiO₂... 2-X The enhanced photocatalytic activity degrades VOCs pollutants in water, achieving a synergistic treatment of pollutants with a "two birds with one stone" approach. Furthermore, the unique spherical aerogel carrier structure and surface mechanical properties enable the dynamically rotating self-cleaning porous floating evaporator to rotate spontaneously during operation, actively removing surface salt crystals and fundamentally solving the salt pollution problem.

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

[0051] In some embodiments of this implementation, the TiO 2-X In TiN / TiO 2-X The mass fraction of the composite material is 80-90%, preferably 80-85%.

[0052] In some embodiments of this implementation, the TiO 2-X The value of x in the equation is between 0.2 and 0.3.

[0053] Understandable, the term TiO 2-X This is oxygen-deficient titanium dioxide, where x represents the proportion of oxygen vacancies. These oxygen vacancies can attract electrons to form oxygen vacancy ions, thereby modulating the structure of TiO2. 2-X The electronic configuration and reactivity of [the substance].

[0054] This invention does not impose requirements on the particle size of the TiN nanoparticles used; any nanoscale particle is acceptable due to the LSPR effect. For example, the particle size can be 20 nm, 50 nm, 500 nm, etc.

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

[0056] The sodium alginate aerogel microspheres have a three-dimensional interconnected pore structure inside, and their surface is uniformly loaded with TiN / TiO. 2-X Composite materials form a stable microsphere structure.

[0057] The present invention provides a porous floating evaporator based on dynamic rotational self-cleaning with TiN / TiO. 2-X The composite material serves as a photothermal / photocatalytic active center. Through the spherical sodium alginate aerogel microsphere carrier structure and dynamic hydrodynamic properties, it achieves three functions: efficient seawater desalination, degradation of volatile organic pollutants, and self-detachment of salt crystals. It is particularly suitable for the long-term stable treatment of water bodies with high salinity and high organic pollution, providing an innovative solution for marine environmental protection and water resource recycling.

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

[0059] I. High-efficiency photothermal evaporation mechanism

[0060] TiN nanoparticles can efficiently absorb sunlight in the 300-2500 nm range and convert light energy into heat energy (photothermal conversion efficiency >95%), driving the rapid evaporation of water molecules on the surface of sodium alginate aerogel microspheres. The three-dimensional interconnected pore structure inside the sodium alginate aerogel microspheres provides efficient heat conduction and moisture migration channels, greatly promoting the evaporation process. Test results show that at 1 sun (1kWm -2 Under standard illumination, the evaporation rate per unit area can reach 1.85 kg / m³. -2 h -1 This is far higher than the natural evaporation rate of water (0.48 kg m³). -2 h -1 ).

[0061] II. Enhancing the photocatalytic degradation mechanism

[0062] TiO 2-X The oxygen vacancies in TiO2 not only reduce the band gap (3.2 eV → 3.06 eV) and expand the photoresponse range, but also effectively trap photogenerated electrons, suppress electron-hole recombination, and significantly improve quantum efficiency. Under illumination, TiO2... 2-X Photogenerated electrons (e - ) and holes (h + It reacts with water and oxygen molecules to generate superoxide radicals (·O2). - Highly reactive oxygen species (ROS) such as hydroxyl radicals (·OH) can efficiently degrade various VOCs pollutants adsorbed on the surface of microspheres.

[0063] III. Innovative Salt Resistance and Self-Cleaning Mechanisms

[0064] The interconnected pore structure inside the sodium alginate aerogel microspheres not only accelerates salt ion diffusion and reduces the salt deposition rate on the surface, but more importantly, under light conditions, the spherical microsphere clusters form a localized thermodynamic system under the combined effects of water surface tension, gravity, and buoyancy. Specifically:

[0065] The microspheres are heated unevenly under light, with the upper surface temperature being higher than the lower surface temperature.

[0066] Salt particles tend to preferentially nucleate and grow in the liquid layer at the upper end of the sphere where evaporation is faster;

[0067] When the torque generated by the mass and position of the salt particles exceeds a critical value, breaking the force balance of the ball, the ball will rotate spontaneously.

[0068] During the rotation, the salt particles slide back into the water 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 a multi-sphere system.

[0070] A second typical embodiment of the present invention provides a method for preparing the above-mentioned porous floating evaporator based on dynamic rotational self-cleaning, comprising:

[0071] Titanium dioxide was grown in situ on the surface of TiN nanoparticles to obtain a TiN / TiO2 composite material;

[0072] TiN / TiO2 composite material was mixed with sodium borohydride and calcined under a protective atmosphere to obtain TiN / TiO2. 2-X Composite materials;

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

[0074] This invention utilizes a hydrothermal method to grow TiO2 in situ on the surface of TiN nanoparticles, followed by reduction and calcination with NaBH4 to introduce oxygen vacancies. This broadens the photoresponse range of TiO2, improves the synergistic efficiency of photothermal and photocatalytic processes, and achieves TiN / TiO2 ... 2-X Controllable preparation of composite materials.

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

[0076] TiN nanoparticles were dispersed in a solvent, and tetrabutyl titanate was added dropwise. The mixture was stirred to obtain a dispersion.

[0077] The dispersion undergoes a hydrothermal reaction. After the reaction is complete, the mixture is cooled and separated into solid and liquid phases to obtain a precipitate. The precipitate is then washed and dried to obtain a TiN / TiO2 composite material.

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

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

[0080] In some embodiments of this implementation, the hydrothermal reaction is carried out at a temperature of 180-220°C for 8-12 hours.

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

[0082] In some embodiments of this implementation, the calcination is performed by 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, after calcination, the mixture is cooled to room temperature, washed to remove residual boride, and dried to obtain TiN / TiO. 2-X Composite materials.

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

[0085] The TiN / TiO 2-X Composite materials loaded on the surface of a spherical aerogel support include:

[0086] Add TiN / TiO to sodium alginate hydrogel solution 2-X The composite material and calcium carbonate powder are mixed thoroughly to obtain a mixture.

[0087] Under stirring conditions, the mixture is added dropwise to a hydrochloric acid solution. After the addition is complete, the mixture is stirred to crosslink, filtered, washed until neutral, and freeze-dried to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

[0088] This invention utilizes the in-situ reaction of calcium carbonate and hydrochloric acid to generate calcium ions that crosslink sodium alginate, while simultaneously releasing carbon dioxide gas to form a continuous structure, thus achieving a green preparation route without the addition of external crosslinking agents. At the same time, it optimizes the specific surface area and liquid transport channels of the material.

[0089] This invention precisely controls the density, hydrophilicity, and surface morphology of microspheres, causing them to heat unevenly under light conditions. Under the combined action of gravitational torque and buoyancy torque, the microspheres spontaneously rotate, ensuring that surface salt crystals automatically detach, thereby achieving a long-term, highly efficient surface self-cleaning function.

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

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

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

[0093] In some embodiments of this implementation, the dripping rate of the mixture is 50-90 rpm, preferably 70 rpm, and the stirring rate is 450-550 rpm, preferably 500 rpm.

[0094] Understandably, in order to achieve precise addition of the mixture, a precision-controlled addition system can be used, in which the mixture is evenly added to the hydrochloric acid solution by a peristaltic pump, and the stirring speed is maintained at 500 rpm to ensure that the microspheres have regular morphology and uniform size.

[0095] In some embodiments of this implementation, the stirring crosslinking time is 5-10 hours to ensure sufficient crosslinking.

[0096] In some embodiments of this implementation, after washing to neutrality, the solvent in the microsphere pores 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 implementation, the present invention provides a specific preparation method for the above-described porous floating evaporator based on dynamic rotational self-cleaning, comprising:

[0098] Step 1: TiN / TiO 2-X Preparation of composite materials

[0099] In-situ growth of TiO2 nanostructures on the surface of TiN nanoparticles using hydrothermal method:

[0100] 0.2 g of commercial TiN nanoparticles were dispersed in 40 mL of acetic acid (HAc) and N'N-dimethylformamide (DMF), and tetrabutyl titanate (TBOT) was slowly added dropwise. The mixture was then sonicated for 30 minutes to form a uniform dispersion. The dispersion was transferred to a 100 mL stainless steel autoclave lined with Teflon and hydrothermally reacted at 200 °C for 10 hours. After cooling to room temperature, the mixture was centrifuged at 8000 rpm for 30 minutes, washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 12 hours to obtain TiN / TiO2 composite nanomaterials.

[0101] NaBH4 reduction and calcination introduces oxygen vacancies:

[0102] The above TiN / TiO2 composite material was mixed with NaBH4 at a mass ratio of 4:1 and placed in a quartz tube furnace. First, high-purity N2 (99.999%) was passed through to replace the composite material for 30 minutes. Then, under continuous N2 flow (50 mL / min) protection, the temperature was increased to 450℃ at 5℃ / min and calcined for 2 hours. After naturally cooling to room temperature, the composite material was removed, soaked in ultrapure water for 24 hours, and washed thoroughly three times to remove residual borides. Finally, it was freeze-dried at -50℃ for 48 hours to obtain oxygen-vacancy-rich TiN / TiO2. 2-X Composite materials.

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

[0104] Preparation of functional mixtures:

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

[0106] Dynamic crosslinking and bubble template pore formation:

[0107] A precisely controlled dripping system was used to uniformly drip the above mixture into a hydrochloric acid solution with pH=2 using a peristaltic pump, while the stirring speed was maintained at 500 rpm to ensure that the microspheres had regular morphology and uniform size.

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

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

[0110] During this reaction, the generated Ca 2+ Ions undergo ionic cross-linking reactions with the carboxyl functional groups in the SA macromolecule to form a stable spherical network structure; at the same time, the released CO2 gas forms microbubbles inside the microspheres, which gradually grow and connect with each other as the reaction proceeds, eventually forming a through-hole porous structure.

[0111] After the mixture was added dropwise, 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℃ for 72 hours to obtain surface-loaded TiN / TiO. 2-X Porous SA aerogel microspheres, named TiN / TiO 2-X @SA.

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

[0113] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0114] The raw materials used in the following experiments are all commercially available products that can be purchased.

[0115] Example 1

[0116] A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning includes the following steps:

[0117] Step 1: TiN / TiO 2-X Preparation of composite materials

[0118] In-situ growth of TiO2 nanostructures on the surface of TiN nanoparticles using hydrothermal method:

[0119] 0.2 g of commercial TiN nanoparticles (20 nm in diameter) were dispersed in 40 mL of a mixed solution of acetic acid and N'N-dimethylformamide in a volume ratio of 2:3. 2 mL of tetrabutyl titanate was slowly added dropwise, followed by ultrasonic treatment for 30 minutes to form a uniform dispersion. The dispersion was transferred to a 100 mL stainless steel high-pressure reactor lined with Teflon and hydrothermally reacted at 200 °C for 10 hours. After cooling to room temperature, the mixture was centrifuged at 8000 rpm for 30 minutes, washed three times with anhydrous ethanol, and vacuum dried at 60 °C for 12 hours to obtain TiN / TiO2 composite nanomaterials.

[0120] NaBH4 reduction and calcination introduces oxygen vacancies:

[0121] The above TiN / TiO2 composite material was mixed with NaBH4 at a mass ratio of 4:1 and placed in a quartz tube furnace. First, high-purity N2 (99.999%) was passed through to replace the composite material for 30 minutes. Then, under continuous N2 flow (50 mL / min) protection, the temperature was increased to 450℃ at 5℃ / min and calcined for 2 hours. After naturally cooling to room temperature, the composite material was removed, soaked in ultrapure water for 24 hours, and washed thoroughly three times to remove residual borides. Finally, it was freeze-dried at -50℃ for 48 hours to obtain oxygen-vacancy-rich TiN / TiO2. 2-X Composite material. Testing revealed that the obtained TiN / TiO... 2-X In composite materials, TiO 2-X The mass percentage is 83%, and x is 0.24.

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

[0123] Preparation of functional mixtures:

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

[0125] Dynamic crosslinking and bubble template pore formation:

[0126] The above mixture was uniformly added dropwise to a hydrochloric acid solution with pH=2 using a peristaltic pump at a dropping rate of 70 rpm, while the stirring speed was maintained at 500 rpm. After the addition of the mixture was completed, the reaction system was stirred and crosslinked 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 pores of the microspheres was gradually replaced with a 30 wt% ethanol solution to protect the pore structure. Finally, it was freeze-dried at -50℃ for 72 hours to obtain surface-loaded TiN / TiO. 2-X The porous sodium alginate aerogel microspheres, namely the porous floating evaporator based on dynamic rotational self-cleaning, are named TiN / TiO. 2-X @SA. Testing revealed that the obtained TiN / TiO 2-X In @SA, TiN / TiO 2-X The mass percentage of composite materials is 8.7%.

[0127] Example 2

[0128] A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning differs from Example 1 in that: 0.05 g, 0.1 g, or 0.3 g of commercial TiN nanoparticles (20 nm in diameter) are dispersed in 40 mL of a mixed solution of acetic acid and N,N-dimethylformamide at a volume ratio of 2:3. The remaining steps are the same as in Example 1.

[0129] Example 3

[0130] A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning differs from Example 1 in that: the TiN / TiO2 composite material is mixed uniformly with NaBH4 at a mass ratio of 1:1 or 1:2. The remaining steps are the same as in Example 1.

[0131] Example 4

[0132] A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning is disclosed, differing from Example 1 in that the commercial TiN nanoparticles have a particle size of 200 nm. The remaining steps are the same as in Example 1.

[0133] Example 5

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

[0135] Example 6

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

[0137] Comparative Example 1

[0138] A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning is disclosed, differing from Example 1 in that it omits the step of "NaBH4 reduction and calcination to introduce oxygen vacancies," while the remaining steps are identical to those in Example 1. Porous sodium alginate aerogel microspheres with a surface-loaded TiN / TiO2 are obtained, i.e., the porous floating evaporator based on dynamic rotational self-cleaning, named TiN / TiO2@SA.

[0139] Experimental Example 1: Photocatalytic Degradation Performance Curves of VOCs by Different Samples

[0140] Accurately weigh 25.0±0.2 mg of photocatalyst (TiN, TiN / TiO2, and TiN / TiO2). 2-X The sample was uniformly dispersed in 50 mL of phenol solution (5.00 ± 0.05 mg / L) by ultrasonication (40 kHz, 30 min). A 300 W xenon lamp light source (AM 1.5 filter, light intensity 100 mW / cm²) was used. 2 Simulated sunlight irradiation was used, and the reaction system temperature was controlled at 25±1℃ using a circulating water bath. Samples were taken periodically and centrifuged to remove the catalyst. VOCs concentration was detected by high-performance liquid chromatography (HPLC, Agilent 1260) (detection limit 0.01 mg / L).

[0141] Test results as follows Figure 1 As shown in Figure a, TiN / TiO 2-XIt exhibits optimal degradation performance, achieving a phenol degradation rate of 95.2% within 6 hours. The residual phenol concentration after treatment is reduced to 0.24 mg / L, which is lower than the 0.5 mg / L limit specified in the Integrated Wastewater Discharge Standard (GB 8978-1996).

[0142] Accurately weigh 25.0 ± 0.2 mg of photocatalyst (TiN / TiO2). 2-X The sample was uniformly dispersed in 50 mL of a solution of 4-fluorophenol, 4-chlorophenol, and 4-bromophenol (5.00 ± 0.05 mg / L) using ultrasonication (40 kHz, 30 min). A 300 W xenon lamp light source (AM1.5 filter, 100 mW / cm²) was used. 2 Simulated sunlight irradiation was used, and the reaction system temperature was controlled at 25±1℃ using a circulating water bath. Samples were taken periodically and centrifuged to remove the catalyst. VOCs concentration was detected by high-performance liquid chromatography (HPLC, Agilent 1260) (detection limit 0.01 mg / L).

[0143] Test results as follows Figure 1 As shown in Figure b, TiN / TiO 2-X It showed significant degradation ability for phenol derivatives with different substituents, and TiN / TiO 2-X The degradation efficiencies for 4-fluorophenol, 4-chlorophenol, and 4-bromophenol were 70.2%, 82.0%, and 96.8%, respectively.

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

[0145] The performance of solar-driven evaporation was tested using a self-made experimental setup. Figure 2 (See Figure a) for details. TiN / TiO 2-X @SA microspheres were floated on the water surface, and their evaporation performance was tested under simulated sunlight (AM 1.5). The amount of water evaporation was monitored in real time using PortScribe software connected to an electronic balance and a computer. The evaporation was measured at a solar intensity of 1 kW·m². -2 Under irradiation conditions, real-time evaporation data were continuously recorded over 180 minutes.

[0146] like Figure 2 As shown in Figure b, the evaporation rate of pure water is 0.48 kg·m³. -2 ·h -1 Pure SA, TiN / TiO2@SA, and TiN / TiO 2-X The evaporation rates of @SA were 0.73 kg·m³. -2 ·h -1 1.37 kg·m -2 ·h -1and 1.85 kg·m -2 ·h -1 This data indicates that, under the same experimental conditions, TiN / TiO2 exhibits enhanced light absorption properties. 2-X @SA microspheres showed significantly improved evaporation performance compared to the blank control group and TiN / TiO2@SA.

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

[0148] Observe the TiN / TiO surface of Experiment Example 2 2-X @SA microsphere, as Figure 3 As shown, the self-cleaning process consists of four steps:

[0149] Under light, salt particles tend to preferentially nucleate and grow in the liquid layer at the top of the sphere where evaporation is faster.

[0150] When the torque generated by the mass and position of the salt particles exceeds a critical value, breaking the force balance of the microsphere, microsphere No. 5 begins to rotate spontaneously.

[0151] Through the surface tension coupling effect, the rotation of one microsphere can trigger a chain reaction of adjacent microspheres (microspheres 1, 2, 3, 4, 6, and 7), realizing the cooperative self-cleaning behavior of the multi-sphere system.

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

[0153] Experimental Example 4: TiN / TiO 2-X @SA Microspheres' Water Purification Capacity Assessment

[0154] Using phenol solution and seawater as the objects to be purified, the following methods were employed: Figure 4 The condensate collected by the evaporation apparatus shown in Figure a is used to culture wheat and E. coli to evaluate the TiN / TiO2 ratio. 2-X The water purification effect of @SA microspheres. Tap water was used as a control group during the cultivation of wheat and E. coli.

[0155] like Figure 4 As shown in Figure b, no *E. coli* strains were observed in the phenol-containing culture medium, while a small number were observed in seawater. However, a large number of strains were observed in the purified water (the purified water was phenol-containing seawater), with the number of colonies approximately 20 times that in seawater, and comparable to the number of *E. coli* colonies cultured in tap water. This indicates that the TiN / TiO2 ratio... 2-X The @SA evaporation system has excellent purification effects on high-salinity wastewater containing VOCs.

[0156] Furthermore, the germination rate and germination length of wheat seeds were compared by cultivating them for seven consecutive days. Figure 4 As shown in Figures c and d, wheat seeds did not germinate in either phenol or seawater, but the malt in the purified wastewater grew to 92±7 mm within 7 days, comparable to the length of malt grown in tap water. This also demonstrates the effectiveness of TiN / TiO2 ratio. 2-X The @SA evaporation system has excellent purification effects on high-salinity wastewater containing VOCs and has a long service life.

[0157] The porous floating evaporators obtained in Examples 2-6 were tested for performance using the methods described in Examples 1-4. The tests showed that the porous floating evaporators obtained in Examples 2-6 had similar performance to the porous floating evaporator obtained in Example 1, and their VOCs photocatalytic degradation performance, photothermal evaporation performance, self-cleaning ability, and water purification capacity were all superior to those of the porous floating evaporator obtained in Comparative Example 1.

[0158] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A porous floating evaporator based on dynamic rotational self-cleaning, characterized in that, Includes a spherical aerogel support and TiN / TiO loaded on the surface of the spherical aerogel support. 2-x Composite materials; The TiN / TiO 2-x The composite material consists of TiN nanoparticles and TiO2 grown in situ on their surface. 2-x constitute; The spherical aerogel carrier is sodium alginate aerogel microspheres with a particle size of 1-10 mm and a porosity of 50-90%.

2. The porous floating evaporator based on dynamic rotational self-cleaning as described in claim 1, characterized in that, TiN / TiO 2-x The mass fraction of composite materials in porous floating evaporators is 5-10%.

3. The porous floating evaporator based on dynamic rotational self-cleaning as described in claim 2, characterized in that, TiN / TiO 2-x The mass fraction of composite materials in porous floating evaporators is 8-9%.

4. The porous floating evaporator based on dynamic rotational self-cleaning as described in claim 2, characterized in that, The TiO 2-x In TiN / TiO 2-x The mass fraction in the composite material is 80-90%.

5. The porous floating evaporator based on dynamic rotational self-cleaning as described in claim 4, characterized in that, The TiO 2-x In TiN / TiO 2-x The mass fraction of the composite material is 80-85%.

6. The porous floating evaporator based on dynamic rotational self-cleaning as described in claim 2, characterized in that, The TiO 2-x The value of X in the equation is between 0.2 and 0.

3.

7. A method for preparing a porous floating evaporator based on dynamic rotational self-cleaning as described in any one of claims 1-6, characterized in that, include: Titanium dioxide was grown in situ on the surface of TiN nanoparticles to obtain a TiN / TiO2 composite material; TiN / TiO2 composite material was mixed with sodium borohydride and calcined under a protective atmosphere to obtain TiN / TiO2. 2-x Composite materials; TiN / TiO 2-x The composite material was loaded onto the surface of a spherical aerogel carrier to obtain a porous floating evaporator based on dynamic rotational self-cleaning.

8. The preparation method according to claim 7, characterized in that, The in-situ growth of titanium dioxide on the surface of TiN nanoparticles includes: TiN nanoparticles were dispersed in a solvent, and tetrabutyl titanate was added dropwise. The mixture was stirred to obtain a dispersion. The dispersion undergoes a hydrothermal reaction. After the reaction is complete, the mixture is cooled and separated into solid and liquid phases to obtain a precipitate. The precipitate is then washed and dried to obtain a TiN / TiO2 composite material.

9. The preparation method according to claim 8, characterized in that, The solvent is a mixed solution of acetic acid and N,N-dimethylformamide in a volume ratio of 1-3:2-5.

10. The preparation method according to claim 8, characterized in that, The ratio of TiN nanoparticles to solvent is 0.05-0.3 g: 35-45 mL.

11. The preparation method according to claim 8, characterized in that, The hydrothermal reaction is carried out at a temperature of 180-220℃ for 8-12 hours.

12. The preparation method according to claim 7, characterized in that, The mass ratio of TiN / TiO2 composite material to sodium borohydride is 3-5:1-2.

13. The preparation method according to claim 12, characterized in that, The calcination process involves heating the temperature to 400-500℃ at a rate of 4-6℃ / min and calcining for 1-3 hours.

14. The preparation method according to claim 12, characterized in that, After calcination, the mixture was cooled to room temperature, washed to remove residual boride, and dried to obtain TiN / TiO. 2-x Composite materials.

15. The preparation method according to claim 7, characterized in that, The spherical aerogel carrier is sodium alginate aerogel microspheres; The TiN / TiO 2-x Composite materials loaded on the surface of a spherical aerogel support include: Add TiN / TiO to sodium alginate hydrogel solution 2-x The composite material and calcium carbonate powder are mixed thoroughly to obtain a mixture. Under stirring conditions, the mixture is added dropwise to a hydrochloric acid solution. After the addition is complete, the mixture is stirred to crosslink, filtered, washed until neutral, and freeze-dried to obtain a porous floating evaporator based on dynamic rotation self-cleaning.

16. The preparation method according to claim 15, characterized in that, The sodium alginate, TiN / TiO 2-x The mass ratio of the composite material to calcium carbonate powder is 10-15:1:10-15.

17. The preparation method according to claim 16, characterized in that, The calcium carbonate powder has a particle size of less than 5 μm.

18. The preparation method according to claim 16, characterized in that, The pH of the hydrochloric acid solution is 2.

19. The preparation method according to claim 16, characterized in that, The stirring crosslinking time is 5-10 h.

20. The preparation method according to claim 15, characterized in that, After washing to neutral, the solvent in the microsphere pores 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.

21. The application of a porous floating evaporator based on dynamic rotation self-cleaning as described in any one of claims 1-6 or a porous floating evaporator based on dynamic rotation self-cleaning prepared by the preparation method described in any one of claims 7-20 in seawater desalination and / or degradation of volatile organic pollutants.

Images