Preparation method and application of pc-sp-mcn double-layer janus composite membrane synergizing solar-driven interfacial evaporation and photocatalysis

Abstract

This invention relates to the field of materials preparation technology. Firstly, it introduces a method for preparing a PC-SP-MCN bilayer Janus composite membrane with synergistic solar-driven interfacial evaporation and photocatalysis, primarily using graft copolymerization and phase transformation as the main synthesis methods. Secondly, it describes the application of the composite membrane in seawater desalination and the purification of wastewater containing dyes, heavy metals, and biological pollutants. Furthermore, this invention prepares a bilayer Janus composite membrane through phase transformation, and the introduction of silica-grafted ionic liquids gives the material excellent salt resistance. Through application studies in seawater desalination and the purification of wastewater containing dyes, heavy metals, and biological pollutants, it is preliminarily concluded that the PC-SP-MCN bilayer Janus composite membrane prepared in this invention with synergistic solar-driven interfacial evaporation and photocatalysis possesses high solar energy conversion efficiency, excellent salt resistance and antifouling properties, and highly efficient photocatalytic degradation performance, making it widely applicable in seawater desalination and wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, specifically to a method for preparing a PC-SP-MCN bilayer Janus composite film that synergistically drives interfacial evaporation and photocatalysis, and its application. Background Technology

[0002] To address the critical issue of limited freshwater supply in the 21st century, various methods have been created and implemented for freshwater regeneration, including technologies such as reverse osmosis and thermal distillation. Currently, clean and promising sustainable energy sources such as solar energy, photovoltaics, photocatalysis, and SDIE have been developed for efficient utilization. SDIE is one of the most effective methods for water purification or seawater desalination, requiring less infrastructure and reducing energy consumption. However, limited evaporation surface area and salt crystallization issues lead to reduced evaporation rates, significantly hindering the practical application of solar thermal materials. Furthermore, rapid economic and industrial development has created an urgent need for multifunctional purification. A significant concern is the substantial risks to the environment and human health posed by the direct discharge of biological pollutants and dye-containing organic solvents. Traditional technologies such as filtration and organic solvent nanofiltration (OSN) are pressure-driven separation processes that inevitably consume large amounts of energy. Therefore, there is an urgent need to develop novel solar thermal materials that exhibit excellent salt resistance and effective resistance to biofouling during SDIE for continuous water purification, and to achieve multifunctional purification effects in challenging environments through synergistic photocatalysis for continuous wastewater treatment.

[0003] In recent years, two-dimensional transition metal carbide / nitride (MXene) nanomaterials have attracted widespread interest from researchers due to their unique electronic, physical, chemical, and mechanical properties. Research reports indicate that multilayer MXene nanomaterials exhibit excellent photothermal properties due to their superior electromagnetic shielding and localized surface plasmon resonance (LSPR) effect. Furthermore, MXene, as a novel two-dimensional transition metal carbide / nitride, is also a commonly used coupled photocatalyst material in heterostructure systems. This is due to its unique characteristics, such as exceptional structural stability, high concentration of hydrophilic functional groups on its surface, superior metallic conductivity, and increased redox properties due to the Ti-terminal positions on the surface. Therefore, MXene possesses abundant surface functional groups and exposed metal sites, giving it a high adsorption capacity comparable to 2D photocatalysts, making it an effective co-catalyst for accelerating the photocatalytic decomposition of organic dyes. Meanwhile, graphitic carbon nitride (g-C3N4), due to its graphite-like sp2-bonded CN structure and narrow band gap of 2.7 eV, has been widely used in the photodegradation of organic pollutants. Based on existing research, we anticipate that combining g-C3N4 photocatalyst with MXene can further enhance its photocatalytic activity. Furthermore, MXene's excellent metallic conductivity can induce Schottky junctions in heterostructure systems, thereby generating an intrinsic electric field. This phenomenon significantly enhances the separation and movement of light-generated charge carriers in heterostructure systems, thus improving photocatalytic degradation performance. SiO2, with its advantages of high cost-effectiveness, good hydrophilicity, ease of synthesis, and controllable particle size, is one of the most commonly used inorganic nanomaterials for modifying membranes. Ionic liquids, known as environmentally friendly solvents, are entirely composed of ions at room temperature, exhibiting extremely low volatility, excellent stability, and electrochemical performance. Polyionic liquids are novel polymer electrolytes with controllable charge and broad ionic structure versatility. Ionic liquids have been used to prepare highly hydrophilic membranes and inhibitory materials. By controlling the polymerization of ionic liquids on SiO2 particles, the structure and properties of SiO2 particles can be modified. The properties of the membrane surface can be controlled according to its charge characteristics, thereby improving the membrane's salt resistance and inhibiting the aggregation of SiO2 particles. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing a PC-SP-MCN bilayer Janus composite membrane that synergistically drives interfacial evaporation and photocatalysis using solar energy, and explores its application in the purification and treatment of wastewater containing high salinity solutions, dyes, heavy metal ions, and biological contamination.

[0005] To achieve the above objectives, the following technical solution is provided:

[0006] The invention also provides a method for preparing a PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis, comprising the following steps:

[0007] Step 1, the preparation of SiO2-PIL particles, specifically includes the following steps:

[0008] Step (1): Grafting Cl groups onto SiO2 to obtain the SiO2-Cl precursor;

[0009] Step (2): Using SiO2-Cl precursor and CuBr2 as catalysts and 2,2'-bipyridine as ligand, [AMIm]PF6 is immersed in a custom three-necked flask containing DMF.

[0010] Step (3): Stir the obtained mixture uniformly under a nitrogen atmosphere, add 0.05g AIBN to the DMF solution in a three-necked flask and stir, graft the [AMIm]PF6 cation onto the SiO2-Cl particles to form a polyelectrolyte brush;

[0011] Step (4): Centrifuge the obtained product, wash it several times with methanol-water solution and ethanol, and finally dry and collect the modified SiO2-PIL.

[0012] Step 2, the preparation of MXene / g-C3N4, specifically includes the following steps:

[0013] Step (1): Fill the alumina crucible with urea powder and then heat it continuously in a furnace;

[0014] Step (2): After the reaction is complete, the crucible is cooled to room temperature, and the obtained g-C3N4 powder is collected and crushed in a mortar.

[0015] Step (3): Add g-C3N4 to MXene and deionized water, sonicate at room temperature, heat and stir until a slurry is formed, dry the sample in an oven overnight and collect it to obtain MXene / g-C3N4;

[0016] Step 3, preparation of the PC-SP-MCN hybrid film, specifically includes the following steps:

[0017] Step (1): Add MXene / g-C3N4 catalyst to DMF solution and stir. Then add Tween 80, PVDF, PEG, and CB. Stir the resulting solution and cool it to room temperature to obtain solution A.

[0018] Step (2): Add SiO2-PIL to the DMF solution, sonicate, and then mix the mixture with Tween 80, PVDF, PEG and CaCO3. Heat the solution and stir, then cool it to room temperature to obtain solution B.

[0019] Step (3): Cast solution A onto a glass plate, cast solution B onto solution A to form a membrane, and then place the formed membrane in an acidic aqueous solution. A large number of bubbles are generated in the solution. After the process is completed, remove the double membrane from the acidic solution and soak it in clean water to remove the residual acid residue and make the membrane neutral, thus obtaining a PC-SP-MCN mixed membrane.

[0020] Preferably, in step (2) of step one, the mass ratio of the SiO2-Cl precursor to CuBr2 is 50:1.

[0021] Preferably, in step (2) of step one, the mass ratio of 2,2'-bipyridine (BPy) to [AMIm]PF6 is 7:1000.

[0022] Preferably, in step three, the mass ratio of PVDF, PEG and CaCO3 is 32:8:1.

[0023] The present invention also provides a PC-SP-MCN bilayer Janus composite film material that synergistically promotes solar-driven interfacial evaporation and photocatalysis, which is prepared by the above-described method.

[0024] This invention provides the application of a PC-SP-MCN bilayer Janus composite membrane that synergistically drives interfacial evaporation and photocatalysis in seawater desalination and in the purification of wastewater containing dyes, heavy metals, and biologically contaminated wastewater.

[0025] As a preferred option, the PC-SP-MCN bilayer Janus composite membrane, which synergistically drives interfacial evaporation and photocatalysis, is placed in different water source environments and directly exposed to sunlight.

[0026] The beneficial effects of this invention are as follows: First, this invention introduces a method for preparing a PC-SP-MCN bilayer Janus composite membrane with synergistic solar-driven interfacial evaporation and photocatalysis, primarily using graft copolymerization and phase transformation as the main synthesis methods. Secondly, it describes its applications in seawater desalination and the purification of wastewater containing dyes, heavy metals, and biological contamination. Furthermore, this invention prepares a bilayer Janus composite membrane through phase transformation, and the introduction of silica-grafted ionic liquids gives the material excellent salt resistance. Excellent light absorption, salt resistance, and anti-biocontamination properties enable it to exhibit high solar-driven interfacial evaporation efficiency and photocatalytic ability. Through application studies in seawater desalination and the purification of wastewater containing dyes, heavy metals, and biological contamination, it is preliminarily concluded that the PC-SP-MCN bilayer Janus composite membrane prepared in this invention with synergistic solar-driven interfacial evaporation and photocatalysis possesses high solar energy conversion efficiency, excellent salt and fouling resistance, and good photocatalytic ability, and can find wide applications in seawater desalination and wastewater treatment. Attached Figure Description

[0027] Figure 1 This diagram shows the preparation of the PC-SP-MCN bilayer Janus composite membrane that synergistically drives interfacial evaporation and photocatalysis according to the present invention.

[0028] Figure 2 In the image, a, b, and c are the optical photographs and SEM images of the upper layer of PC-SP-MCN; d is the water contact angle; e, f, and g are the optical photographs and SEM images of the lower layer of PC-SP-MCN; h is the water contact angle; and i and j are the EDS element mappings of the upper and lower layers of PC-SP-MCN.

[0029] Figure 3 In the figure, a and b are the infrared spectra of PVDF, SiO2, SiO2-PIL, and PM-SiO2-PIL; c is the potential diagram of SiO2 and SiO2-PIL; d is the thermogravimetric curve of SiO2 and SiO2-PIL; e and f are the BET spectra of SiO2 and SiO2-PIL.

[0030] Figure 4 In the diagram, a and b represent pure water and a PC-SP-MCN composite Janus membrane at a power output of 1 kW m³. -2 Mass loss and evaporation efficiency of the upper and lower surfaces under solar irradiation; c represents PC-SP-MCN at 1 ~ 3 kW m -2 Infrared camera images showing surface temperature changes under solar radiation; d, e are PC-SP-MCN at 1 ~ 3 kW m -2Mass loss and evaporation efficiency and rate under solar irradiation; f is the cycle curve of PC-SP-MCN under solar irradiation within this range; g is a schematic diagram of the device for using PC-SP-MCN composite Janus membrane in SDIE experiments.

[0031] Figure 5 In the figure, a represents the mass loss of PC-SP-MCN in simulated seawater and salt solutions of different concentrations; b represents the evaporation efficiency and rate of PC-SP-MCN in simulated seawater and salt solutions of different concentrations; c and d represent the mass loss and evaporation rate of PC-SP-MCN after continuous evaporation in a 20% NaCl solution for 8 hours; e and f represent the concentrations of metal ions in seawater before and after evaporation; and g is a schematic diagram of the potential salt tolerance mechanism of PC-SP-MCN.

[0032] Figure 6 In the figures, a and c represent the UV-Vis spectra of MB, MO, and RhB at different time intervals; d represents the photocatalytic curves of different dyes such as MB, MO, and RhB on PC-SP-MCN; e represents the kinetic fitting of the pseudo-first-order reaction model of MB, MO, and RhB on PC-SP-MCN; f represents the comparative analysis of the photocatalytic efficiency of MB, MO, and RhB with and without PC-SP-MCN; g represents the degradation curve of PC-SP-MCN after 5 cycles of photodegradation, taking MB as an example; h and I represent the antibacterial band test photos of PC-SP-MCN against Escherichia coli and Staphylococcus aureus. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] The method for preparing the PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis of the present invention includes the following steps:

[0035] (1) Preparation of SiO2-PIL particles

[0036] First, SiO2 was grafted with Cl groups (SiO2-Cl), which was then used as a precursor to synthesize SiO2-PIL. 10 g of vacuum-dried SiO2 and 6 mL of 3-chloropropyltriethoxysilane (ClTES) were added to 250 mL of DMF, and the mixture was heated at 80 °C with continuous stirring for 12 h. The resulting product was collected by centrifugation, washed several times with ethanol, and then vacuum-dried at 50 °C for 24 h. SiO2-PIL particles were then synthesized using atom transfer radical polymerization (ATRP) with 5.0 g of SiO2-Cl precursor and 0.1 g of CuBr2 as a catalyst. 20.0 g of [AMIm]PF6 was immersed in a custom-made three-necked flask containing 200 mL of DMF, using 0.14 g of 2,2′-bipyridine (BPy) as a ligand. The resulting mixture was stirred uniformly under a nitrogen atmosphere for 10 min. A 10 g / L AIBN solution was added to a flask, and the mixture was stirred in 10 mL of DMF for 48 h. [AMIm]PF6 cations were grafted onto SiO2-Cl particles at 70 °C to form a polyelectrolyte brush. The resulting product was collected by centrifugation and washed several times with methanol-water solution and ethanol. Finally, the modified SiO2-PIL was vacuum dried at 50 °C for 24 h.

[0037] The purpose of grafting Cl groups onto the surface of SiO2 and then using them as a precursor to synthesize SiO2-PIL is to graft ionic liquids onto the surface of SiO2 via atom transfer radical polymerization.

[0038] (2) Preparation of MXene / g-C3N4

[0039] g-C3N4 was synthesized using a urea thermal shrinkage method. Urea powder was filled into an alumina crucible and then heated continuously in a furnace at 500 °C with a heating rate of 5 °C / min for 120 min. After the reaction was complete, the crucible was cooled to room temperature, and the powder inside was collected and pulverized in a mortar. MXene / g-C3N4 heterostructure photocatalyst composites were prepared using a wet impregnation method. First, 1 g of g-C3N4 was added to 0.01 g of MXene and 30 mL of deionized water. The mixture was sonicated at room temperature for 30 min and then heated and stirred for 45 min until a slurry was formed. The sample was dried overnight in an oven at 60 °C and collected.

[0040] The purpose of preparing the MXene / g-C3N4 heterojunction is to prepare a PC-SP-MCN film with good photocatalytic performance.

[0041] (3) Preparation of PC-SP-MCN hybrid membrane

[0042] First, 0.015 g of MXene / g-C3N4 catalyst was added to 8 mL of DMF solution and stirred for 30 min. Then, 1 mL of Tween 80, 1.6 g of PVDF, 0.4 g of PEG, and 0.05 g of CB were added. The resulting solution was heated to 80 °C and stirred for 1 h. After cooling to room temperature, the solution was stirred for another 24 h to obtain solution A. Next, 0.05 g of SiO2-PIL was added to 8 mL of DMF solution and sonicated for 30 min. The mixture was then combined with 1 mL of Tween 80, 1.6 g of PVDF, 0.4 g of PEG, and 0.05 g of CaCO3. The solution was heated to 80 °C and stirred for 1 h. After cooling to room temperature again, the solution was stirred for another 24 h to obtain solution B. The next step involves casting the film-forming solution onto a glass plate; then, film-forming solution B is cast onto film-forming solution A, and the resulting membrane is placed in an acidic aqueous solution, where a large number of bubbles are generated. After this process is complete, the bilayer membrane is removed from the acidic solution and soaked in clean water for 48 hours to remove any residual acid and neutralize the membrane. This process ensures that the membrane is free of any unwanted chemicals and is ready for use in its intended application.

[0043] The purpose of placing the formed membrane in an acidic aqueous solution is to modify it with CaCO3 so that its surface has a large number of pores, thus giving it excellent hydrophilicity.

[0044] Example 1: Preparation of SiO2-PIL particles

[0045] First, SiO2 was grafted with Cl groups (SiO2-Cl), which was then used as a precursor to synthesize SiO2-PIL. 10 g of vacuum-dried SiO2 and 6 mL of 3-chloropropyltriethoxysilane (ClTES) were added to 250 mL of DMF, and the mixture was heated at 80 °C with continuous stirring for 12 h. The resulting product was collected by centrifugation, washed several times with ethanol, and then vacuum-dried at 50 °C for 24 h. SiO2-PIL particles were then synthesized using atom transfer radical polymerization (ATRP) with 5.0 g of SiO2-Cl precursor and 0.1 g of CuBr2 as catalyst. 20.0 g of [AMIm]PF6 was immersed in a three-necked flask containing 200 mL of DMF, using 0.14 g of 2,2′-bipyridine (BPy) as a ligand. The resulting mixture was stirred uniformly under a nitrogen atmosphere for 10 min. A 10 g / L AIBN solution was added to a flask, and the mixture was stirred in 10 mL DMF for 48 h. [AMIm]PF6 cations were grafted onto SiO2-Cl particles at 70 °C to form a polyelectrolyte brush. The resulting product was collected by centrifugation and washed several times with methanol-water solution and ethanol.

[0046] Figure 1 This diagram shows the preparation of the PC-SP-MCN bilayer Janus composite membrane that synergistically drives interfacial evaporation and photocatalysis according to the present invention.

[0047] like Figure 1 As shown, this study proposes a novel Janus composite membrane with strong salt resistance and resistance to biofouling. Using PVDF as the membrane material, SiO2-PIL as the hydrophilic agent, calcium carbonate (CaCO3) and hydrochloric acid (HCl) as pore-forming agents for hydrophilic modification, and MXene / g-C3N4 as the photocatalyst, a composite polyvinylidene fluoride (PVDF) Janus membrane (PC-SP-MCN) with Schottky junctions was prepared.

[0048] Example 2 PC-SP-MCN bilayer Janus composite film

[0049] (1) Preparation of MXene / g-C3N4:

[0050] g-C3N4 was synthesized using a urea thermal shrinkage method. Urea powder was filled into an alumina crucible and then heated continuously in a furnace at 500 °C with a heating rate of 5 °C / min for 120 min. After the reaction was complete, the crucible was cooled to room temperature, and the powder inside was collected and pulverized in a mortar. MXene / g-C3N4 heterostructure photocatalyst composites were prepared using a wet impregnation method. First, 1 g of g-C3N4 was added to 0.01 g of MXene and 30 mL of deionized water. The mixture was sonicated at room temperature for 30 min and then heated and stirred for 45 min until a slurry was formed. The sample was dried overnight in an oven at 60 °C and collected.

[0051] (2) Preparation of PC-SP-MCN hybrid membrane:

[0052] First, 0.015 g of MXene / g-C3N4 catalyst was added to 8 mL of DMF solution and stirred for 30 min. Then, 1 mL of Tween 80, 1.6 g of PVDF, 0.4 g of PEG, and 0.05 g of CB were added. The resulting solution was heated to 80 °C and stirred for 1 h. After cooling to room temperature, the solution was stirred for another 24 h to obtain solution A. Next, 0.05 g of SiO2-PIL was added to 8 mL of DMF solution and sonicated for 30 min. The mixture was then combined with 1 mL of Tween 80, 1.6 g of PVDF, 0.4 g of PEG, and 0.05 g of CaCO3. The solution was heated to 80 °C and stirred for 1 h. After cooling to room temperature again, the solution was stirred for another 24 h to obtain solution B. The next step involves casting the film-forming solution onto a glass plate; then, film-forming liquid B is cast onto film-forming liquid A, and the resulting membrane is placed in an acidic aqueous solution, where a large number of bubbles are generated. After this process is complete, the bilayer membrane is removed from the acidic solution and soaked in clean water for 48 hours to remove any residual acid and neutralize the membrane. This process ensures that the membrane is free of any unwanted chemicals and is ready for use in its intended application.

[0053] Figure 2 In the image, a, b, and c are the optical photographs and SEM images of the upper layer of PC-SP-MCN; d is the water contact angle; e, f, and g are the optical photographs and SEM images of the lower layer of PC-SP-MCN; h is the water contact angle; and i and j are the EDS element mappings of the upper and lower layers of PC-SP-MCN.

[0054] like Figure 2 The optical photographs from ah clearly show the different colors of the upper and lower layers, which can be attributed to the presence of carbon black in the upper layer. Due to the addition of CaCO3, the lower PVDF membrane exhibits a uniform porous structure, and the introduction of SiO2-PIL not only did not clog the pores but also enhanced its hydrophilicity. On the other hand, the upper membrane has no obvious pores and has prominent MXene / g-C3N4 particles on its surface, which can effectively store heat, achieving a hydrophobicity of 80°. The lower membrane has good hydrophilicity, with a contact angle of 0°, which facilitates rapid water transfer to the intermediate layer.

[0055] Figure 3 In the figure, a and b are the infrared spectra of PVDF, SiO2, SiO2-PIL, and PM-SiO2-PIL; c is the potential diagram of SiO2 and SiO2-PIL; d is the thermogravimetric curve of SiO2 and SiO2-PIL; e and f are the BET spectra of SiO2 and SiO2-PIL.

[0056] like Figure 3As shown in Figures ab, the pore size distribution of SiO2-PILs / starch was tested using the mercury intrusion porosimetry (MIP) method. From the MIP / extrusion MIP curves, it can be seen that the mercury intrusion is relatively gradual when the pore size is 50-350 µm, but increases rapidly when the pore size is less than 50 µm. The porosity is 60.57%, and the total pore area is 0.195 m². 2 g -1 This indicates that SiO2-PILs / starch has a rich macroporous structure. Figure 3 e and f represent the average pore size of SiO2 (0.82 nm) and SiO2-PIL (0.68 nm). Figure 3 c shows the charge properties of the main SiO2, SiO2-Cl and SiO2-PIL. Figure 3 d represents the composition of the prepared particles as characterized by TGA.

[0057] Example 3: Application of the PC-SP-MCN bilayer Janus composite membrane of the present invention, which combines synergistic solar-driven interfacial evaporation and photocatalysis, in seawater desalination and purification of wastewater containing dyes, heavy metals, and biologically contaminated wastewater.

[0058] The PC-SP-MCN bilayer Janus composite membrane prepared in Example 2 was used as an interfacial evaporation system. An infrared camera was used to measure and record the local temperature of the PC-SP-MCN surface at different time points during the interfacial evaporation process. An electronic balance was used to monitor and record the real-time mass of water during evaporation. The evaporation rate of PC-SP-MCN could be obtained from the slope of the curve showing the change in water mass over time, and the corresponding photothermal conversion efficiency could then be calculated. Furthermore, at 1 kW m³ / s… -2 Under light intensity, the evaporation efficiency of PC-SP-MCN was tested in 10 cycles. Wastewater was prepared as a simulated organic dye wastewater using a solution containing 15 mg / L methylene blue (MB), rhodamine B (RhB), and methyl orange (MB). At 1 kW m -2 (equivalent to 100 mWcm) -2 The photocatalytic degradation performance of a single dye and PC-SP-MCN was tested under the photocatalytic intensity of ).

[0059] Figure 4 a and b represent pure water and a PC-SP-MCN composite Janus membrane at a 1 kW m³ / h. -2 Mass loss and evaporation efficiency of the upper and lower surfaces under solar irradiation; c represents PC-SP-MCN at 1 ~ 3 kW m -2 Infrared camera images showing surface temperature changes under solar radiation; d, e are PC-SP-MCN at 1 ~ 3 kW m -2Mass loss and evaporation efficiency and rate under solar irradiation; f is the cycle curve of PC-SP-MCN under solar irradiation within this range; g is a schematic diagram of the device for using PC-SP-MCN composite Janus membrane in SDIE experiments.

[0060] like Figure 4 As shown in Figure a, experiments were conducted to evaluate the evaporation performance of pure water, PC-SP-MCN, and its various positive and negative sides under SDIE. When exposed to 1 kW m³ / s... -2 Under solar irradiation, PC-SP-MCN exhibited significantly higher mass loss than the control material, indicating its superior evaporation capacity. To further investigate the evaporation efficiency and rate of PC-SP-MCN, the correlation between mass and time for various materials was comprehensively analyzed. For example... Figure 4 As shown in b, the evaporation efficiency of PC-SP-MCN is 1.51 kg m³. -2 h -1 The evaporation rate is 91%. Figure 4 ce represents the variation of surface temperature, mass loss, evaporation efficiency, and evaporation rate of PC-SP-MCN under different light intensities. (In the range of 1-3 kW / m²) -2 Under varying light intensities, the evaporation efficiencies of PC-SP-MCN were 91%, 70%, and 64%, respectively. Increased light intensity led to higher heat loss, resulting in decreased evaporation efficiency. To gain a deeper understanding of the surface temperature changes in PC-SP-MCN, a significant increase in the material's surface temperature was observed using an infrared thermal imager. This occurred when the solar irradiance was between 1 and 3 kW / m³. -2 Within this range, the surface temperature of PC-SP-MCN increased from approximately 18.0 ℃ to 40.5 ℃, 47.7 ℃, and 53.8 ℃, respectively. Under different solar irradiance intensities (1-3 kW m²), -2 Stability tests under various conditions showed that the PC-SP-MCN membrane underwent 5 cycles, demonstrating its stable evaporation capacity and indicating that the composite Janus membrane possesses good cycle stability. Figure 4 g represents the experimental setup for SDIE experiments using a PC-SP-MCN composite Janus membrane.

[0061] Figure 5 a represents the mass loss of PC-SP-MCN in simulated seawater and salt solutions of different concentrations; b represents the evaporation efficiency and rate of PC-SP-MCN in simulated seawater and salt solutions of different concentrations; c and d represent the mass loss and evaporation rate of PC-SP-MCN after continuous evaporation in 20% NaCl solution for 8 h; e and f represent the concentrations of metal ions in seawater before and after evaporation; g is a schematic diagram of the potential salt tolerance mechanism of PC-SP-MCN.

[0062] like Figure 5As shown in a and b, at a solar irradiance of 1 kW m -2 Under these conditions, a high salt concentration in the solution has no significant effect on the stability of PC-SP-MCN, indicating that PC-SP-MCN doped with SiO2-PIL has excellent salt resistance. Figure 5 c and d indicate that when the NaCl concentration is 20 wt%, the evaporation efficiency of PC-SP-MCN is 83%, and the evaporation rate is 1.39 kg m³. -2 h -1 . Figure 5 c and d represent salt tolerance tests where PC-SP-MCN was immersed in a 20% NaCl solution for 8 hours. Figure 5 As shown in (cd), the evaporation rate of PC-SP-MCN remains stable under a solar irradiance of 1 kW m⁻². Figure 5 ef simulates the changes in various ions (Na+) before and after seawater desalination. + Mg 2+ K + Cu 2+ Pb 2+ and Zn 2+ The significantly reduced level of ions indicates that PC-SP-MCN has a high ion retention rate.

[0063] Figure 6 In the figures, a and c represent the UV-Vis spectra of MB, MO, and RhB at different time intervals; d represents the photocatalytic curves of different dyes such as MB, MO, and RhB on PC-SP-MCN; e represents the kinetic fitting of the pseudo-first-order reaction model of MB, MO, and RhB on PC-SP-MCN; f represents the comparative analysis of the photocatalytic efficiency of MB, MO, and RhB with or without PC-SP-MCN; g represents the degradation curve of PC-SP-MCN after 5 cycles of photodegradation, taking MB as an example; h and I represent the antibacterial band test photos of PC-SP-MCN against Escherichia coli and Staphylococcus aureus.

[0064] like Figure 6 As shown, the characteristic peaks of the UV-Vis absorption spectra of MB, RhB, and MO solutions gradually decrease as the photocatalytic reaction proceeds, indicating that PC-SP-MCN has excellent photocatalytic ability for organic pollutants. Figure 6 As shown in d and f, the degradation rates of MB, RhB, and MO decreased from the initial value of 1 to approximately 0.0494, 0.0340, and 0.2577, respectively. The removal rates of MB, RhB, and MO by the PC-SP-MCN composite material were 95.06%, 96.9%, and 74.23%, respectively. Figure 6 The kinetic curve shown in e is used to calculate the kinetic parameters of the reaction, and the reaction conforms to the first-order kinetic model. Figure 6 Cyclic photocatalytic degradation experiments were conducted using PC-SP-MCN as the MB degradation catalyst. The results show that PC-SP-MCN maintains consistent photocatalytic activity even after five consecutive cycles, highlighting its excellent reusability. Figure 6 The widths of the antibacterial bands were approximately 3.5 mm and 4.2 mm, respectively, further confirming the effective antibacterial properties of the composite membrane.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for preparing a PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis, comprising the following steps: Step 1, the preparation of SiO2-PIL particles, specifically includes the following steps: Step (1): Grafting Cl groups onto SiO2 to obtain the SiO2-Cl precursor; Step (2): Using SiO2-Cl precursor and CuBr2 as catalysts and 2,2'-bipyridine as ligand, [AMIm]PF6 is immersed in a custom three-necked flask containing DMF. Step (3): Stir the mixture obtained in step (2) uniformly under a nitrogen atmosphere, add 0.05 g AIBN to the mixture in a three-necked flask and stir, grafting [AMIm]PF6 cations onto SiO2-Cl particles to form a polyelectrolyte brush; Step (4): Centrifuge the obtained product, wash it several times with methanol-water solution and ethanol, and finally dry and collect the modified SiO2-PIL. Step 2, the preparation of MXene / g-C3N4, specifically includes the following steps: Step (1): Fill the alumina crucible with urea powder and then heat it continuously in a furnace; Step (2): After the reaction is complete, the crucible is cooled to room temperature, and the obtained g-C3N4 powder is collected and crushed in a mortar. Step (3): Add g-C3N4 to MXene and deionized water, sonicate at room temperature, heat and stir until a slurry is formed, dry the sample in an oven overnight and collect it to obtain MXene / g-C3N4; Step 3, preparation of the PC-SP-MCN hybrid film, specifically includes the following steps: Step (1): Add MXene / g-C3N4 catalyst to DMF solution and stir. Then add Tween 80, PVDF, PEG, and CB. Stir the resulting solution and cool it to room temperature to obtain solution A. Step (2): Add SiO2-PIL to the DMF solution, sonicate, and then mix the mixture with Tween 80, PVDF, PEG and CaCO3. Heat the solution and stir, then cool it to room temperature to obtain solution B. Step (3): Cast solution A onto a glass plate, cast solution B onto solution A to form a membrane, and then place the formed membrane in an acidic aqueous solution. A large number of bubbles are generated in the solution. After the process is completed, remove the double membrane from the acidic solution and soak it in clean water to remove the residual acid residue and make the membrane neutral, thus obtaining a PC-SP-MCN mixed membrane.

2. The method for preparing the PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis according to claim 1, characterized in that: In step (2) of step one, the mass ratio of the SiO2-Cl precursor to CuBr2 is 50:

1.

3. The method for preparing the PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis according to claim 1, characterized in that: In step (2) of step one, the mass ratio of 2,2'-bipyridine (BPy) to [AMIm]PF6 is 7:1000.

4. The method for preparing the PC-SP-MCN bilayer Janus composite film with synergistic solar-driven interfacial evaporation and photocatalysis according to claim 1, characterized in that: In step three, the mass ratio of PVDF, PEG and CaCO3 is 32:8:

1.

5. The PC-SP-MCN bilayer Janus composite membrane with synergistic solar-driven interfacial evaporation and photocatalysis prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the PC-SP-MCN bilayer Janus composite membrane with synergistic solar-driven interfacial evaporation and photocatalysis as described in claim 5 in seawater desalination and in the purification and treatment of wastewater containing dyes, heavy metals and biological pollutants.

7. The application according to claim 6, characterized in that: The PC-SP-MCN bilayer Janus composite membrane, which synergistically drives interfacial evaporation and photocatalysis, was placed in different water source environments and directly exposed to sunlight.

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