Preparation method of multi-energy coupling water body shading diaphragm plate and shading diaphragm plate

Abstract

The invention relates to a preparation method of a multi-energy coupling water body shading diaphragm plate and the shading diaphragm plate, and belongs to the field of water environment treatment. The preparation method comprises the following steps: preparing outer-layer functional shell slurry consisting of PVDF (Polyvinylidene Fluoride), Fe3O4 and SiO2 aerogel; preparing middle-layer light absorption layer slurry which is composed of nano WO3, nitrogen defect g-C3N4 and Fe3O4 and is filled with nitrogen to regulate and control the density; preparing inner-layer super-hydrophilic layer slurry formed by modified TiO2 doped with Fe < + > and V2O5; and sequentially coating the three layers of slurry by adopting a blade coating method, pre-drying, and curing and forming in an alkaline solution in a mold with a pit structure. The prepared shading diaphragm plate has a three-layer structure of an outer-layer functional shell, a middle-layer regulation and control and an inner-layer functional core, can synchronously realize efficient shading and algal inhibition, microcystin degradation and magnetic control recovery, has the advantages of wide scene adaptability and long service life, and is suitable for algal bloom treatment and pollution regulation and control of static and flowing water bodies.

Description

Technical Field

[0001] This invention relates to the field of water environment management technology, and more specifically, to a method for preparing a multi-energy coupled water body shading film and the shading film itself, which can be adapted to water body control devices for various water environments. Background Technology

[0002] Currently, algal blooms caused by eutrophication are becoming increasingly serious, posing a severe threat to water quality and aquatic ecosystems. Among various treatment technologies, physical shading is widely used due to its environmental friendliness and ease of operation. This method mainly involves laying shading floats, plastic films, or foam blocks on the water surface to block the light required for algal photosynthesis, thereby inhibiting their growth.

[0003] However, existing shading-type water body control devices generally suffer from core technological bottlenecks such as limited functionality and poor adaptability to different scenarios. Most devices only provide physical shading and cannot catalytically degrade existing organic pollutants (such as microcystins) in the water, resulting in incomplete treatment. Furthermore, the material and structural designs of these devices struggle to meet diverse aquatic environment requirements: in static reservoirs, traditional devices are easily contaminated by algal secretions and biofilms, causing shading efficiency to decrease over time; in flowing rivers and canals, they are prone to drifting and stacking due to unreasonable density and flow resistance designs, resulting in insufficient stability; and in highly corrosive coastal or brackish water bodies, their materials often lack sufficient corrosion resistance, leading to shortened service life and the risk of releasing secondary pollution such as microplastics.

[0004] Furthermore, existing devices are often difficult to recycle efficiently after the treatment cycle ends, relying heavily on manual retrieval, which not only increases treatment costs but also limits the sustainability of their large-scale application. Therefore, there is an urgent need in this field to develop a new type of light-shielding membrane that breaks through the limitations of traditional single functions, integrating multiple functions such as light shading, catalytic degradation, anti-fouling, and easy recycling, while possessing good physicochemical stability and being widely adaptable to various water environments, from static reservoirs to flowing rivers and canals, thereby achieving efficient, economical, and sustainable comprehensive water treatment. Summary of the Invention

[0005] To address the aforementioned technical challenges, this invention provides a method for preparing a multi-energy coupled water body shading membrane and the shading membrane itself. This method constructs an integrated shading membrane that combines hydrophobic shading, magnetron light absorption, and coupled catalysis. Through the chemical assembly and structural design of each layer of materials, it simultaneously solves the problems of algae control, degradation, recycling, and pollution prevention in water treatment.

[0006] This invention provides a method for preparing a multi-energy coupled water body light-shielding membrane, comprising: S1: Preparation of outer functional shell slurry: PVDF, Fe3O4 and SiO2 aerogel are mixed in a mass ratio of 8:1:1 and added to a solvent in which N,N-dimethylformamide and acetone are mixed in a volume ratio of 7:3. 0.5% perfluorooctyltriethoxysilane is added and stirred to form a uniform slurry. S2: Preparation of the middle light-absorbing layer slurry: Nano WO3, nitrogen-deficient g-C3N4 composite material and Fe3O4 are mixed at a mass ratio of 1:1:5. 1% polyethylene glycol is added as a dispersant. The mixture is first mechanically stirred for 30 minutes, and then ultrasonically dispersed at 300W power for 45-60 minutes using an ultrasonic cell disruptor to form a non-agglomerated black slurry. Nitrogen gas is then introduced to adjust the overall density to 0.85-0.90 g / cm³. S3: Preparation of the inner superhydrophilic layer slurry: Doping Fe³⁺ + Modified TiO2 and V2O5 were combined, and sodium dodecyl sulfate and polyethylene glycol were used as dispersants. The mixture was subjected to ultrasonic stirring for 30-60 minutes to form a stable suspension-type photocatalytic material. S4: Layered Coating and Molding: Using a doctor blade coating method, the outer functional shell slurry, the middle light-absorbing layer slurry, and the inner superhydrophilic layer slurry are uniformly coated onto the substrate surface in sequence, controlling the thickness of each layer; then the coated material is placed in a 50℃ forced-air drying oven for pre-drying; finally, the material is placed in a mold with a 0.18-0.22mm deep pit structure on the surface, and placed in an alkaline aqueous solution for heat treatment at 30-40℃, and finally cured and molded to obtain the multi-energy coupled water body light-shielding film.

[0007] In this scheme, during step S4, when coating the outer functional shell slurry, the doctor blade gap is controlled to make the dry film thickness 15-20μm and the coating speed 5-8cm / s.

[0008] In this scheme, in step S4, when coating the intermediate light-absorbing layer slurry, the coating thickness is controlled to be 1-1.05mm.

[0009] In this scheme, during step S4, when coating the inner superhydrophilic layer slurry, the doctor blade gap is controlled to be 2080-2100μm.

[0010] In this scheme, in step S4, the curing and molding process is as follows: the pre-dried material is placed in a mold with a pitted surface, and then placed in a sodium hydroxide aqueous solution with a mass fraction of 0.5%-5%, heated to 30-40℃ and kept at that temperature for 2 hours, and then kept at that temperature for more than 12 hours.

[0011] A second aspect of the present invention provides a multi-energy coupled water body shading membrane, the shading membrane having a three-layer integrated structure, comprising: The outer functional shell is composed of PVDF, Fe3O4 and SiO2 aerogel in a mass ratio of 8:1:1; The middle light-absorbing layer is a porous foam layer composed of nano-WO3, nitrogen-deficient g-C3N4 composite material, and Fe3O4, with an overall density of 0.85-0.90 g / cm³, capable of absorbing light in the 450-560 nm and 620-680 nm wavelength bands; The inner superhydrophilic layer contains V2O5 and doped Fe³⁺. + Modified TiO2 composite photocatalytic layer.

[0012] In this design, the outer functional shell surface has a pit structure with a depth of 0.18-0.22 mm and a corrosion resistance of ≥1500 hours.

[0013] In this design, the inner superhydrophilic layer has a diameter of 5-7 cm and a degradation rate of ≥98% for microcystin.

[0014] The third aspect of this invention provides the application of multi-energy coupled water body shading membranes in the treatment of algal blooms in floating water bodies and the regulation of pollutants in flowing water bodies.

[0015] This invention addresses the shortcomings of the prior art and has the following beneficial effects: The multi-energy coupled water shading membrane prepared by the method of this invention achieves synergistic effects through its unique triple structure design of "outer functional shell - middle light-absorbing layer - inner superhydrophilic layer", which comprehensively improves the efficiency, adaptability and sustainability of water treatment.

[0016] The outer hydrophobic shell not only effectively blocks algae and pollutants from adhering, maintaining surface cleanliness and long-term light-shielding stability, but its embedded Fe3O4 component also endows the membrane plate with magnetic recovery capabilities, solving the problems of difficult recovery and high cost in traditional devices. The middle light-absorbing layer, through the composite of nano-WO3 and nitrogen-deficient g-C3N4, achieves precise absorption of key wavelengths of light in the 450-560nm and 620-680nm bands, fundamentally inhibiting the photosynthesis of cyanobacteria; at the same time, the porous foam structure formed by filling with inert gas precisely controls its density at 0.85-0.90g / cm³, ensuring its stable buoyancy in both static and dynamic water bodies. The inner superhydrophilic catalytic layer uses V2O5 and Fe3O4 as its components. +Using doped and modified TiO2 as the core, a highly efficient microenvironment is created, achieving a degradation rate of over 98% for microcystin. The micro-pitted structure on the surface effectively reduces water flow resistance, preventing it from accumulating and drifting in high-velocity rivers and canals. Simultaneously, the outer PVDF-based composite coating provides excellent corrosion resistance (≥1500 hours), ensuring long-term service life in harsh water environments such as high-salinity coastal areas. It can cover various scenarios including static reservoirs, urban rivers, and high-salinity coastal waters, eliminating the need for separate designs for individual scenarios. The magnetically controlled recovery mechanism significantly reduces the labor and time costs of subsequent retrieval, and the slow-release concentration of key elements meets ecological safety standards, avoiding secondary pollution problems during the treatment process. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation method of the multi-energy coupled water body light-shielding membrane in an embodiment of the present invention.

[0018] Figure 2 The test contact angle results are for the hydrophilic layer of the outer functional shell in this embodiment of the invention.

[0019] Figure 3 The test contact angle results are for the hydrophobic layer of the outer functional shell in this embodiment of the invention.

[0020] Figure 4 The XRD test results of the magnetic components of the light-shielding film in this embodiment of the invention are shown. Figure 5 The XRD test results of the algae-inhibiting effect of the light-shielding film in this embodiment of the invention are shown. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0023] A method for preparing a multi-energy coupled water-shading membrane, such as... Figure 1 As shown, it includes the following steps: S1: Preparation of the outer functional shell slurry: Polyvinylidene fluoride (PVDF) powder with a molecular weight of approximately 500,000 was selected and precisely weighed with surface-modified silane-modified nano-Fe3O4 (particle size 50-100nm) and SiO2 aerogel powder at a mass ratio of 8:1:1. This mixture was added to a solvent system consisting of N,N-dimethylformamide (DMF) and acetone at a volume ratio of 7:3, with the total solvent mass being 10 times the total solid mass. Subsequently, perfluorooctyltriethoxysilane (FOTS) was added at 0.5% of the total slurry mass as a hydrophobic modifier. The mixture was stirred at 400 rpm for 2 hours using a mechanical stirrer to form a uniform and stable suspension slurry.

[0024] The outer superhydrophobic functional layer adopts a superhydrophobic coating design, which can effectively block the adhesion of pollutants in the water (such as algal secretions and suspended particles), avoid the decrease in light transmittance caused by surface contamination of the membrane, and ensure the stability of long-term shading effect. At the same time, the introduction of Fe3O4 magnetic particles with excellent stability not only gives the membrane the ability to be magnetically controlled, but also enables the recovery of magnetic energy in the later stage, solving the problems of difficult recovery and high cost of traditional devices.

[0025] S2: Prepare the intermediate light-absorbing layer slurry by weighing nano-WO3, nitrogen-deficient g-C3N4 composite material, and nano-Fe3O4, controlling the mass ratio to 1:1:5. Add polyethylene glycol 400 as a dispersant at 1% of the total slurry mass. First, use mechanical stirring at 500 rpm for 30 minutes for initial mixing, then use an ultrasonic cell disruptor at 300W power for ultrasonic dispersion for 45-60 minutes until a non-agglomerated black slurry is formed. During ultrasonication, nitrogen gas is continuously injected into the slurry to replace the air, ultimately precisely controlling the overall density of the slurry within the range of 0.85-0.90 g / cm³.

[0026] The light-absorbing component of the middle magnetron light-absorbing porous layer adopts a composite system of nano-WO3, nitrogen-deficient g-C3N4, and Fe3O4, with a mass ratio of 1:1:5. Among them, nano-WO3 and nitrogen-deficient g-C3N4 work together to achieve selective absorption of light in the target wavelength band of 450-680nm, while Fe3O4 enhances the magnetron performance and material dispersibility. The filling of inert gas forms a porous foam structure, and the overall density is controlled to 0.85-0.90g / cm³ to ensure that the membrane floats stably in water and reduce the impact of water flow.

[0027] S3: Preparation of the inner superhydrophilic layer slurry: using Fe³ doped material +Modified TiO2 and V2O5 were used as the core photocatalytic components, compounded in a 1:1 mass ratio. Sodium dodecyl sulfate and polyethylene glycol (average molecular weight 6000) were used as composite dispersants, with a total addition amount of 5% of the solid powder mass. The mixture was mixed with deionized water, and the solid content was controlled at 15%. Subsequently, the mixture was placed in an ultrasonic cleaner and ultrasonically stirred at a frequency of 40 kHz for 30-60 minutes to finally form a highly stable suspension-type photocatalytic material.

[0028] The inner superhydrophilic catalytic layer is modified with TiO2 (Fe³⁺). + The core photocatalytic component is doped with sodium dodecyl sulfate and polyethylene glycol as dispersants. After ultrasonic stirring for 30-60 minutes, a stable suspension-type photocatalytic material is formed. Its superhydrophilic properties can accelerate the contact between pollutants such as microcystin in water and the catalytic active sites, thereby improving the efficiency of action.

[0029] S4: Layered Coating and Curing: On a clean PET release film, the outer functional shell slurry is uniformly applied at a speed of 5-8 cm / s, with the dry film thickness adjusted to 15-20 μm by controlling the squeegee gap. The coated substrate is then pre-cured in a 50°C oven for 1 hour. Next, the intermediate light-absorbing layer slurry is applied over the cured outer layer, with the wet film thickness adjusted to approximately 1-1.05 mm by controlling the coating amount. It is then dried again in a 50°C oven for 1 hour. Finally, the inner superhydrophilic layer slurry is applied, with the squeegee gap set to 2080-2100 μm and the application speed maintained at 5-8 cm / s to ensure uniform coating.

[0030] The substrate with the three-layer coating was dried in a 50°C forced-air drying oven for 10 hours to remove the solvent. Then, the dried composite film was placed in a specially designed mold with 0.20mm deep pits on its surface and fixed, while simultaneously immersing it in a 2% sodium hydroxide aqueous solution. The temperature was slowly raised to 35°C and maintained at this temperature for 2 hours. The film was then left submerged for at least 12 hours to fully cure and set. Finally, it was removed from the mold and rinsed thoroughly with deionized water to obtain the multi-energy coupled water-based light-shielding film.

[0031] Each functional layer material is chemically assembled through a single surface polymerization process, avoiding the risk of interlayer delamination and ensuring multi-energy coupling effect. In the membrane plate forming stage, a mold with a surface pit structure of 0.18-0.22mm depth is used for curing and forming. The pit design can reduce the resistance of water flow. The final integrated light-shielding membrane plate is suitable for direct addition to water without pretreatment.

[0032] The performance of the obtained light-shielding film was tested: Static water contact angle tests were performed on the outer functional shell. Contact angle tests were conducted on the hydrophilic layer of the material, and the results of the hydrophilic layer's contact angle tests are as follows: Figure 2 As shown, the contact angle is greater than 150°. The hydrophobic layer of the material is used for contact angle testing. The test contact angle of the hydrophobic layer is shown in the figure. Figure 3 As shown, the contact angle is greater than 90°, exhibiting excellent superhydrophobic properties.

[0033] The magnetic components in the material were measured by XRD using a CuKa target, a power of 35 kV, a scan rate of 0.06° / s, and an angle range of 20–70°2θ. The results are as follows: Figure 4 As shown, the diffraction peaks match the standard card of Fe3O4 (JCPDS No. 19-0629), confirming the successful introduction of spinel-structured Fe3O4.

[0034] Using *Microcystis aeruginosa* 925 as the target, the algae strain was purchased from the Freshwater Algae Bank of the Institute of Hydrobiology, Wuhan, Chinese Academy of Sciences, with the number FACHB-925. The water sample was free of other suspended solids, so the optical density method was chosen to evaluate the algae removal effect. The optical density (OD) measurement method was used to control the concentration of algal cells in the test solution by controlling the absorbance at λ=684nm, and the OD value was used as the indicator. 684 The removal rate was used to characterize the algal cell removal rate. A water sample containing algae was prepared, and the material was placed on the water surface with an 80% coverage rate. The sample was then left to stand outdoors for 6 days under natural conditions. The results are as follows: Figure 5 As shown, compared with traditional light-blocking floats, the algal cell density (OD684) of the membrane plate treatment group of the present invention decreased by more than 95%, demonstrating a very strong algae-suppressing ability.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multi-function coupling light-shielding film plate for a water body, characterized in that, Comprising the following steps: S1: preparing the outer functional shell slurry: mixing PVDF, Fe3O4 and SiO2 aerogel according to the mass ratio of 8:1:1, adding to the solvent mixed by N,N-dimethylformamide and acetone according to the volume ratio of 7:3, adding 0.5% of perfluorooctyltriethoxysilane by mass fraction, and stirring to form a uniform slurry; S2: preparing the middle light-absorbing layer slurry: mixing nano-WO3, nitrogen-deficient g-C3N4 composite material and Fe3O4 according to the mass ratio of 1:1:5, adding 1% of polyethylene glycol by mass fraction as a dispersant, mechanically stirring for 30 minutes, and then ultrasonic dispersion for 45-60 minutes by ultrasonic cell disruptor at 300W power to form a black slurry without agglomeration, and then flushing with nitrogen to control the overall density to 0.85-0.90 g / cm³; S3: Preparation of inner layer super-hydrophilic layer slurry: modified TiO2 doped with Fe3+ + V2O5, with sodium dodecyl sulfate and polyethylene glycol as dispersants, through 30-60 minutes of ultrasonic stirring treatment, to form a stable suspension type photocatalytic material; S4: layered coating and molding: using a doctor blade coating method, the outer functional shell slurry, the middle light-absorbing layer slurry and the inner super-hydrophilic layer slurry are uniformly coated on the surface of the substrate in turn, and the thickness of each layer is controlled; then the coated material is placed in a 50°C air drying oven for pre-drying; finally, the material is placed in a mold with a 0.18-0.22mm deep recess structure on the surface, placed in an alkaline aqueous solution and treated at 30-40°C, and finally cured and molded to obtain the multi-functional coupling water body shading film plate.

2. The method for preparing a multi-energy coupled water body shading membrane according to claim 1, characterized in that, In step S4, when coating the outer functional shell slurry, the doctor blade gap is controlled to make the dry film thickness 15-20μm, and the doctor blade coating speed is 5-8cm / s.

3. The method of claim 1, wherein the multi-functional coupling water body light shielding film plate is prepared by the steps of: a. providing a first film plate and a second film plate; b. coupling the first film plate and the second film plate to form a multi-functional coupling water body light shielding film plate. In step S4, when coating the middle light-absorbing layer slurry, its coating thickness is controlled to be 1-1.05mm.

4. The method for preparing a multi-energy coupled water body shading membrane according to claim 1, characterized in that, In step S4, when coating the inner super-hydrophilic layer slurry, the doctor blade gap is controlled to be 2080-2100μm.

5. The method for preparing a multi-energy coupled water body shading membrane according to claim 1, characterized in that, In step S4, the curing and molding process is as follows: the pre-dried material is placed in a mold with a recess structure on the surface, and is placed in a 0.5%-5% sodium hydroxide aqueous solution, heated to 30-40°C for 2 hours, and then kept for 12 hours or more.

6. The multi-purpose coupling water body shading film sheet prepared by the method of any one of claims 1-5, characterized in that, The shading film plate has a three-layer integrated structure, comprising: The outer functional shell is composed of PVDF, Fe3O4 and SiO2 aerogel according to the mass ratio of 8:1:1; The middle light-absorbing layer is a porous foam layer composed of nano-WO3, nitrogen-deficient g-C3N4 composite material and Fe3O4, with an overall density of 0.85-0.90g / cm³, and can absorb light in the 450-560nm and 620-680nm wavelength bands; An inner super-hydrophilic layer comprising V2O5 and modified TiO2 composite photocatalytic layer doped with Fe3+ + .

7. The multi-purpose coupling light-shielding membrane plate for water bodies according to claim 6, characterized in that, The outer functional shell surface has a 0.18-0.22mm deep recess structure, and the corrosion resistance is ≥1500 hours.

8. The multi-purpose coupling light-shielding membrane plate for water bodies according to claim 6, characterized in that, The inner super-hydrophilic layer has a diameter of 5-7cm, and the degradation rate of microcystin is ≥98%.

9. The application of the multi-functional coupling water body shading film plate of any one of claims 6-8 in the management of floating water body algae and the regulation of flowing water body pollutants.

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