Photocatalytic material and method for synergistically promoting growth of submerged plants by using photocatalytic material and underwater full-wavelength light source

Abstract

The invention provides a photocatalytic material and a method for synergistically promoting growth of submerged plants by using the photocatalytic material and an underwater full-wavelength light source. The photocatalytic material comprises modified titanium dioxide, modified graphene and a surfactant, the modified titanium dioxide is prepared from the following raw materials: sodium alginate, gadolinium nitrate and tetrabutyl titanate; the modified graphene is prepared from the following raw materials: graphene, ascorbic acid, acrylic acid and ethyl cellulose. When a photocatalytic net prepared from the photocatalytic material is placed in a polluted river or a polluted pond and the like, even if the photocatalytic net is below the water surface, chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen can still be reduced, and dissolved oxygen can be obviously increased; and even if the prepared photocatalytic net is placed at a deeper position below the water surface, the prepared photocatalytic net still has lower chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen and higher dissolved oxygen when being placed at a deeper position below the water surface compared with the prepared photocatalytic net which is placed at a position closer to the water surface, and meanwhile, by compensating the light source underwater, the photocatalytic net can be more stable in water quality. Therefore, the planting and growth of submerged plants are further improved.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a photocatalytic material and a method for promoting the growth of submerged plants in synergy with an underwater full-wavelength light source. Background Technology

[0002] Photocatalysis is an innovative technology that uses light energy to drive chemical reactions through photocatalysts. These photocatalysts can be activated by visible light, rather than the ultraviolet light commonly used in traditional photochemistry. As a novel approach, photocatalysis drives chemical reactions and utilizes visible light to restore the self-purification of water bodies, reducing severe damage to lake ecosystems. It has many important applications in sustainable energy development and environmental pollution control.

[0003] Existing photocatalytic technologies mainly include graphene photocatalysis and titanium dioxide photocatalysts. Graphene photocatalysis utilizes the light energy present in nature to convert it into the energy required for chemical reactions, thereby generating a catalytic effect. This excites surrounding oxygen and water molecules into highly oxidizing free negative ions, which can decompose organic substances and some inorganic substances harmful to humans and the environment, achieving the effect of treating lake and pond water bodies. However, there are also issues with the poor binding between graphene and photocatalytic materials, leading to a large amount of loss in the water and reducing the overall treatment efficiency. While titanium dioxide photocatalysts also have the effect of treating lake and pond water bodies, conventional pure titanium dioxide only responds to ultraviolet light. In low-light areas of lakes or on cloudy days, its catalytic activity drops sharply, resulting in low treatment efficiency.

[0004] To address the shortcomings of graphene photocatalysis and titanium dioxide photocatalysis, researchers have continuously developed graphene-titanium dioxide composite technologies. For example, patent publication number "CN110026171B" discloses a method for preparing highly efficient graphene-based photocatalytic materials. By adhering titanium dioxide to three-dimensional graphene, the aggregation of nano-titanium dioxide and the easy loss of photocatalytic materials are prevented, thus improving water treatment efficiency. However, problems remain, such as low treatment efficiency when the material is present in water for extended periods and poor water treatment effect when the photocatalytic material is placed underwater. Poor underwater water quality is detrimental to the planting and growth of submerged plants, and the attenuation of natural light in water also limits the growth of submerged plants.

[0005] To address the problems existing in the prior art, this invention urgently seeks to provide a photocatalytic material that maintains high water treatment efficiency even underwater after prolonged rinsing, thereby facilitating the planting and growth of submerged plants, and a method for synergistically promoting the growth of submerged plants with an underwater full-wavelength light source. Summary of the Invention

[0006] The purpose of this invention is to provide a photocatalytic material and a method for synergistically promoting the growth of submerged plants with an underwater full-wavelength light source, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a photocatalytic material comprising modified titanium dioxide, modified graphene, and a surfactant; The raw materials for preparing the modified titanium dioxide include sodium alginate, gadolinium nitrate, and tetrabutyl titanate. The raw materials for preparing the modified graphene include a pretreated graphene mixture, unsaturated carboxylic acid compounds, and cellulose derivatives.

[0008] Furthermore, the surfactants include cocamidopropyl-PG-dimethylammonium chloride phosphate and sodium dioctyl sulfosuccinate.

[0009] Furthermore, the preparation method of modified titanium dioxide includes the following steps: (1) Gadolinium-modified titanium dioxide was placed in sodium alginate solution and mixed to obtain intermediate one; (2) Intermediate 1 is placed in a chloride salt solution for full cross-linking, and then the cross-linked material is washed with water, frozen and freeze-dried to obtain modified titanium dioxide.

[0010] Furthermore, the mass concentration of the sodium alginate solution is 1wt-3wt%.

[0011] Furthermore, the mass concentration of the chloride salt solution is 1.5wt-4wt.

[0012] Furthermore, the chloride salt solution is a calcium chloride solution.

[0013] Furthermore, the preparation method of gadolinium-modified titanium dioxide includes the following steps: (1) Add tetrabutyl titanate to an alcohol solvent, mix well, and prepare a mixture. (2) After mixing alcohol solvent, acid solvent, deionized water and gadolinium nitrate, the mixture is stirred magnetically to obtain mixture II; (3) Add mixture one to mixture two and stir thoroughly. After mixing, age, centrifuge, dry, calcine and cool the mixture to obtain gadolinium-modified titanium dioxide.

[0014] Furthermore, the alcohol solvent is at least one selected from ethanol, propanol, and butanol. Preferably, the ethanol is anhydrous ethanol.

[0015] Furthermore, the acid solvent is at least one of glacial acetic acid and formic acid.

[0016] Furthermore, in the preparation method of gadolinium-modified titanium dioxide, the volume-to-mass ratio of tetrabutyl titanate used in step (1) and gadolinium nitrate used in step (2) is 30-40 mL: 0.2-0.4 g.

[0017] Furthermore, the mass ratio of cocamidopropyl-PG-dimethylammonium chloride phosphate and sodium dioctyl sulfosuccinate is 1:2-3.

[0018] Furthermore, the preparation method of modified graphene includes the following steps: (1) After adding unsaturated carboxylic acid compounds to the pretreated graphene mixture, the mixture is subjected to low-temperature ultrasonication, water bath, and vacuum distillation reactions in sequence, and then set aside for later use. (2) Add the organotitanium compound to an alcohol-based organic solvent, add the cellulose derivative and stir until completely dissolved, then set aside. (3) The substance from step (1) is added to the low-temperature ultrasonic reaction in step (2), dried at constant temperature, purged with nitrogen, and sintered at constant temperature to obtain modified graphene.

[0019] Furthermore, unsaturated carboxylic acid compounds include at least one of acrylic acid, methacrylic acid, and fumaric acid.

[0020] Furthermore, the organotitanium compound is tetrabutyl titanate; the alcoholic organic solvent is anhydrous ethanol.

[0021] Furthermore, the mass ratio of modified titanium dioxide to modified graphene is 1:2-4.

[0022] Furthermore, cellulose derivatives include one or more combinations of ethyl cellulose and methyl cellulose.

[0023] On the other hand, the present invention also provides a method for promoting the growth of submerged plants in synergy between photocatalytic materials and underwater full-wavelength light sources.

[0024] Furthermore, the method includes submerged plants, a light compensation device to provide a full-wavelength light source for the submerged plants, a submerged plant planting frame containing a submerged plant planting substrate for planting submerged plants and fixed by a float and a fixing rod, and a photocatalytic mesh made of photocatalytic material fixed on the submerged plant planting frame with pre-drilled growth holes for submerged plants.

[0025] Compared with the prior art, the beneficial effects of the present invention are: When the photocatalytic net made from the photocatalytic material provided in this application is placed in polluted rivers or ponds, even below the water surface, it can significantly reduce chemical oxygen demand (COD), ammonia nitrogen, total phosphorus, and total nitrogen, and significantly increase dissolved oxygen. Furthermore, even when the prepared photocatalytic net is placed deeper below the water surface of the polluted river or pond, compared to placing it closer to the water surface, it still exhibits lower COD, ammonia nitrogen, total phosphorus, and total nitrogen, and higher dissolved oxygen, thus facilitating the planting and growth of submerged plants. Simultaneously, underwater compensating light sources further enhance the planting and growth of submerged plants. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the photocatalytic material of the present invention used in a photocatalytic network; Figure 2 This is a graph showing the dissolved oxygen variation in the method of promoting the growth of submerged plants in synergy between the photocatalytic material of the present invention and an underwater full-wavelength light source. Figure 3 This is a graph showing the chlorophyll a change in the method of synergistic promotion of submerged plant growth by photocatalytic material and underwater full-wavelength light source according to the present invention. Figure 4 This is a schematic diagram of the method for promoting the growth of submerged plants in synergy between the photocatalytic material and an underwater full-wavelength light source, as described in this invention.

[0027] In the diagram: 1-pipe pile; 2-support rod; 3-ring; 4-photocatalytic mesh; 5-submerged plant planting frame; 6-floating body; 7-photocatalytic mesh film; 8-submerged plant; 9-fixing rod. Detailed Implementation

[0028] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0029] In the following examples, except for gadolinium-modified titanium dioxide, modified titanium dioxide A, and modified graphene A, all other compound monomers and related reagents used were commercially available. Sodium alginate was purchased from Henan Haoxuan Chemical Products Co., Ltd. (item number 1-556); graphene was purchased from Shanghai Zhouhui Welding Materials Co., Ltd. (item number zh-c); ethyl cellulose was purchased from Xi'an Shouhe Biotechnology Co., Ltd. (item number SH-24-67); and cocamidopropyl-PG-dimethylammonium chloride phosphate was purchased from Guangzhou Youbao Chemical Co., Ltd. Product code PGT; sodium dioctyl sulfonate succinate was purchased from Shanghai Donghui Chemical Technology Co., Ltd., product code AL-520755257136; silicone softener was purchased from Guangzhou Xumei Chemical Technology Co., Ltd., product code E3560; polypropylene mesh was purchased from Tiantaishan Screen Filler Factory (General Partnership), product code 4342; polyurethane adhesive was purchased from Hefei Hengtian New Material Technology Co., Ltd., product code 1282; waterborne modified polyacrylate copolymer emulsion was purchased from Yingchuang Technology (Guangdong) Co., Ltd., product code IRW-E007.

[0030] The preparation method of gadolinium-modified titanium dioxide includes the following steps: (1) Add 34 mL of tetrabutyl titanate to 35 mL of anhydrous ethanol and stir until fully mixed to obtain mixture one; (2) Mix 45 mL of anhydrous ethanol, 15 mL of glacial acetic acid, 17 mL of deionized water and 0.36 g of gadolinium nitrate, and then mix them by magnetic stirring to obtain mixture II; (3) Under magnetic stirring, the first mixture was slowly dripped into the second mixture, and magnetic stirring was continued for 2.5 hours. The mixed material was then aged at 25°C for 50 hours. The aged material was centrifuged (centrifugation speed 7000 r / min, centrifugation time 20 min), dried (temperature 80°C, time 24 h), and placed in a muffle furnace. The temperature was increased to 400°C at a rate of 3°C / min, and then constant temperature heat treatment was performed for 2.5 hours. Finally, the material was cooled to obtain gadolinium-modified titanium dioxide.

[0031] The preparation method of modified titanium dioxide A includes the following steps: (1) 1.5g of gadolinium-modified titanium dioxide was placed in sodium alginate solution (wherein, sodium alginate solution is a mixed solution of 2g sodium alginate and 98mL water) and mixed well to obtain intermediate one; (2) 5 mL of intermediate one was placed in a calcium chloride solution (a mixture of 2 g calcium chloride and 98 mL water) for crosslinking for 24 h. Then, the crosslinked material was washed with deionized water 6 times, frozen (freezing temperature was -25℃) for 12 h, and then freeze-dried in a freeze dryer (freezing temperature was -50℃) for 15 h to obtain modified titanium dioxide A.

[0032] The preparation method of modified graphene A includes the following steps: (1) Add 8g of graphene to 1L of distilled water, then add 70g of ascorbic acid and stir evenly (stirring speed is 300r / min) to obtain a pretreated graphene mixture; add 12g of acrylic acid to the pretreated graphene mixture and then carry out low-temperature ultrasonic reaction (low-temperature ultrasonic reaction temperature is 7℃, low-temperature ultrasonic reaction time is 5h, low-temperature ultrasonic reaction frequency is 80kHz), water bath reaction (water bath reaction temperature is 100℃, water bath reaction time is 6.5h), and vacuum distillation (vacuum distillation pressure is 65% of atmospheric pressure, temperature is 110℃) to obtain coated graphene. (2) Add 200g of tetrabutyl titanate to 1L of anhydrous ethanol, add 110g of ethyl cellulose and stir until completely dissolved (stirring speed is 1500r / min), set aside; (3) Add 2g of coated graphene from step (1) to the low-temperature ultrasonic reaction in step (2) for 5h (the temperature of the low-temperature ultrasonic reaction is 8℃ and the ultrasonic frequency is 160kHz), and then dry it rapidly at 110℃. After drying in an infrared drying oven at 220℃ and 50%RH for 4h, purge with nitrogen (the purge speed is 150mL / min and the purge time is 120min) and then sinter at 320℃ for 2.5h to obtain modified graphene A.

[0033] Example 1: A photocatalytic material comprising 10g modified titanium dioxide A, 20g modified graphene A, 0.6g cocamidopropyl-PG-dimethylammonium chloride phosphate and 1.4g sodium dioctyl sulfonate succinate.

[0034] Example 2: A photocatalytic material comprising 12g modified titanium dioxide A, 25g modified graphene A, 0.8g cocamidopropyl-PG-dimethylammonium chloride phosphate and 2g sodium dioctyl sulfonate succinate.

[0035] Example 3: A photocatalytic material comprising 8g modified titanium dioxide A, 24g modified graphene A, 0.5g cocamidopropyl-PG-dimethylammonium chloride phosphate and 1.5g sodium dioctyl sulfonate succinate.

[0036] Example 4: A photocatalytic material comprising 10g modified titanium dioxide A, 20g modified graphene A, 0.6g isooctanol ether phosphate and 1.4g sodium dioctyl sulfonate succinate.

[0037] Comparative Example 1: A photocatalytic material comprising 10g gadolinium-modified titanium dioxide, 20g modified graphene A, 0.6g cocamidopropyl-PG-dimethylammonium chloride phosphate and 1.4g sodium dioctyl sulfonate succinate.

[0038] Comparative Example 2: A photocatalytic material comprising 10g modified titanium dioxide A, 20g graphene, 0.6g cocamidopropyl-PG-dimethylammonium chloride phosphate and 1.4g sodium dioctyl sulfonate succinate.

[0039] Application Examples 1-6: (1) Soak the polypropylene mesh in a solution containing silicone softener (the solution containing silicone softener is a mixture of silicone softener and water with a mass ratio of 2:98) for 15 hours, and then air dry it naturally; (2) The photocatalytic materials and adhesives (the adhesives are polyurethane adhesive and water-based modified polyacrylate copolymer emulsion with a mass ratio of 1:1) prepared in the ratio of 2.8:1 were mixed to obtain an soaking solution. The product that was naturally air-dried in step (1) was soaked in the soaking solution and stirred for 15 minutes. After that, it was stretched and dried for 40 minutes. It was then soaked in the soaking solution again in a stretched state and left to stand for 15 minutes before being taken out and air-dried to obtain a photocatalytic mesh.

[0040] The correspondence between the photocatalytic materials prepared in Examples 1-6 and Examples 1-4 and Comparative Examples 1-2 is shown in Table 1 below: Table 1

[0041] The experimental subjects of this invention are Class V or worse ponds. The water quality of Class V or worse ponds before and after treatment was tested for chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus. The testing methods are as follows: Total nitrogen, total phosphorus, ammonia nitrogen, and chemical oxygen demand: determined according to the methods specified in the "Surface Water Environmental Quality Standard" (GB 3838-2002); Specifically, ammonia nitrogen was determined using Nessler's reagent colorimetric method; Chemical oxygen demand is measured using the dibutyrate method; Total nitrogen was determined by alkaline potassium persulfate digestion and ultraviolet spectrophotometry. Total phosphorus was determined using the ammonium molybdate spectrophotometric method.

[0042] Water from a Class V or worse pond was taken, mixed, and then the total nitrogen, total phosphorus, ammonia nitrogen, and chemical oxygen demand (COD) were measured before treatment to achieve Class V or worse water quality. The COD before treatment was 78 mg / L, ammonia nitrogen was 5 mg / L, total nitrogen was 7 mg / L, and total phosphorus was 3 mg / L. The water taken from the Class V or worse pond before treatment was then placed into 12 identical pools. First, rinse the photocatalytic mesh of Application Examples 1-6 with distilled water for 20 hours, then refer to... Figure 1 After fixing the photocatalytic net 4 around the perimeter with the support rod 2, the support rod 2 is fixedly connected to the pipe pile 1 through the collar 3. Then, the pipe pile 1 is installed in the designated position of the water tank, so that the upper end of the photocatalytic net in Application Examples 1-6 is 15cm and 30cm below the water surface, respectively. After being placed under natural conditions for 4 days (June 16, 2025 - June 19, 2025), the pipe pile 1, support rod 2, collar 3, and photocatalytic net 4 are taken out. The water in the water tank is mixed with a stirrer (stirrer speed is 80r / min). The changes in total nitrogen, total phosphorus, ammonia nitrogen, and chemical oxygen demand of the water in the water tank after treatment are detected. The specific surface area of ​​the photocatalytic net in the water tank is 30% of the corresponding water tank surface area.

[0043] Table 2 shows the test data of the treated water quality after the upper end of the photocatalytic mesh in Application Examples 1-6 was located 15 cm below the water surface: Table 2

[0044] Table 3 shows the test data of the treated water quality after the upper end of the photocatalytic mesh in Application Examples 1-6 was located 30 cm below the water surface: Table 3

[0045] As can be seen from the comparison of Application Example 1 and Application Example 4 in Table 2-3, the photocatalytic material prepared by the surfactant provided in this application, and the photocatalytic net prepared by the prepared photocatalytic material, after being rinsed with distilled water for a long time, can still further reduce chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen even when placed below the water surface of the pool. Moreover, even when the prepared photocatalytic net is placed at a deeper position below the water surface of the pool, it still has relatively low chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen. A comparison of Application Examples 1 and 5-6 in Tables 2-3 shows that the photocatalytic material prepared from the modified titanium dioxide and modified graphene provided in this application, and the photocatalytic net prepared from the prepared photocatalytic material, can significantly reduce chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen even when placed below the water surface in a pool after being rinsed with distilled water for a long time. Even when the prepared photocatalytic net is placed at a deeper position below the water surface in the pool, the chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen are still relatively low. As can be seen from the comparison of Application Examples 1 to 3 in Table 2-3, the photocatalytic material prepared by the surfactant, modified titanium dioxide and modified graphene provided in this application, and the photocatalytic net prepared by the prepared photocatalytic material, after being rinsed with distilled water for a long time, can still significantly reduce chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen even when placed below the water surface in the pool; and even if the prepared photocatalytic net is placed at a deeper position below the water surface in the pool, compared with the prepared photocatalytic net being placed at a position closer to the water surface, although chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen increase, the increase is not significant, and it still has low chemical oxygen demand, ammonia nitrogen, total phosphorus and total nitrogen.

[0046] Therefore, it can be seen that when the photocatalytic net made from the photocatalytic material provided in this application is placed in polluted rivers or ponds, even below the water surface, it can still significantly reduce chemical oxygen demand (COD), ammonia nitrogen, total phosphorus (TP), and total nitrogen. Moreover, even when the prepared photocatalytic net is placed deeper below the water surface of the polluted river or pond, compared to placing the prepared photocatalytic net closer to the water surface, although COD, ammonia nitrogen, TP, and total nitrogen increase, the increase is not significant. When the photocatalytic net is placed deeper below the water surface of the polluted river or pond, it still has low COD, ammonia nitrogen, TP, and total nitrogen, which is conducive to the planting and growth of submerged aquatic plants.

[0047] The experimental subject of this invention is the raw water of Taihu Lake. Dissolved oxygen and chlorophyll a were tested on the raw water of Taihu Lake. The test methods are as follows: Dissolved oxygen: Measured using a multi-parameter water quality analyzer (YSI 6600v2, USA); Chlorophyll a content was determined according to HJ 897-2017 standard. When testing dissolved oxygen and chlorophyll a, refer to Figure 4The method involves first installing a float 6 at the bottom of a submerged plant planting frame 5, which forms a storage space with its bottom and side walls. Then, submerged plant planting substrate is filled into the storage space of the frame 5. A photocatalytic mesh 7 with pre-drilled plant growth holes is then fixed to the frame 5 by binding. Healthy submerged plants (in this example, *Vallisneria natans*) 8 of the same height are selected, passed through the growth holes, and planted in the substrate. A fixing rod 9 and the float 6 are then used to position the frame 5 at a fixed height, with the fixing rod 9 fixedly connected to the lake bottom. The specific surface area of ​​the photocatalytic mesh 7 is 20% of the lake surface area, and the upper end of the mesh 7 is 2m below the water surface. A light compensation device is used to ensure the light intensity of the mesh 7 is 30.5% of the natural light intensity. After one month of illumination (the illumination period is from July 31, 2025 to August 30, 2025), the dissolved oxygen content is measured as follows: Figure 2 As shown, the chlorophyll a content is as follows: Figure 3 As shown ( Figure 2-3 Photocatalytic membrane 7 of T1 is application example 1, and photocatalytic membrane 7 of T2 is application example 4. Figure 2-3 It is evident that when the light compensation device and photocatalytic mesh are used in combination, the dissolved oxygen content increases significantly, while the chlorophyll a content decreases significantly, which is more conducive to the growth of submerged plants such as Vallisneria natans (wherein, the submerged plant planting frame 5 is made of polyethylene; the submerged plant planting substrate is activated carbon; and the float 6 is a blow-molded hollow plastic body made of polyethylene). All components used in the light compensation device were purchased from Jiangsu Shuangliang Environmental Technology Co., Ltd.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is defined by the appended claims and their equivalents. Obviously, the embodiments described in this invention are only a part of the embodiments of the invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A photocatalytic material, characterized by: The photocatalytic material comprises modified titanium dioxide, modified graphene and a surfactant; The preparation raw material of the modified titanium dioxide comprises sodium alginate, gadolinium nitrate and tetrabutyl titanate; The preparation raw material of the modified graphene comprises pretreated graphene mixed solution, unsaturated carboxylic acid compound and cellulose derivative.

2. The photocatalytic material according to claim 1, characterized in that: The surfactant comprises cocamidopropyl-PG-dimethyl ammonium chloride phosphate and sodium sulfosuccinimide.

3. The photocatalytic material according to claim 1, characterized in that: The preparation method of the modified titanium dioxide comprises the following steps: (1) mixing gadolinium modified titanium dioxide in sodium alginate solution to obtain intermediate one; (2) crosslinking the intermediate one in a chloride salt solution, then washing, freezing, freeze-drying the crosslinked substance to obtain modified titanium dioxide.

4. The photocatalytic material according to claim 1, characterized in that: The preparation method of the gadolinium modified titanium dioxide comprises the following steps: (1) mixing tetrabutyl titanate in an alcohol solvent to obtain mixed solution one; (2) mixing alcohol solvent, acid solvent, deionized water and gadolinium nitrate, then mixing by magnetic stirring to obtain mixed solution two; (3) adding mixed solution one into mixed solution two, then aging, centrifuging, drying, roasting and cooling the mixed substance to obtain gadolinium modified titanium dioxide.

5. The photocatalytic material according to claim 4, characterized in that: In the preparation method of the gadolinium modified titanium dioxide, the volume mass ratio of tetrabutyl titanate used in step (1) to gadolinium nitrate used in step (2) is 30-40 mL:0.2-0.4 g.

6. The photocatalytic material according to claim 2, characterized in that: The preparation method of the modified graphene comprises the following steps: (1) adding unsaturated carboxylic acid compound into pretreated graphene mixed solution, then sequentially performing low-temperature ultrasonic, water bath and reduced pressure distillation reaction, and standby; (2) adding organic titanium compound into alcohol organic solvent, then adding cellulose derivative and stirring until completely dissolved, and standby; (3) adding the substance of step (1) into step (2) to perform low-temperature ultrasonic reaction, constant temperature drying, nitrogen blowing and constant temperature sintering to obtain modified graphene.

7. The photocatalytic material according to claim 1, wherein: The mass ratio of the modified titanium dioxide to the modified graphene is 1:2-4.

8. The photocatalytic material according to claim 6, characterized in that: The cellulose derivative comprises one or more combinations of ethyl cellulose and methyl cellulose.

9. The method for promoting growth of submerged plants by the photocatalytic material of any one of claims 1-8 in cooperation with an underwater full-wavelength light source.

10. The method of claim 9, wherein: The method comprises submerged plants (8), light compensation equipment for providing full-wavelength light source for the submerged plants (8), submerged plant planting frame (5) containing submerged plant planting substrate for planting submerged plants (8) and fixed by floating body (6) and fixing rod (9), and photocatalytic net film (7) made of photocatalytic material and fixed on the submerged plant planting frame (5) and reserved with growth holes for the submerged plants (8).

Images