Preparation and application of a light evaporation-light catalysis coupling hydrogel

Abstract

The application discloses a kind of preparation and application of light evaporation-light catalysis coupling hydrogel, using preparation hydrogel is placed on the surface of various sewage (seawater, methylene blue solution, tetracycline solution), carry out light evaporation-light catalysis coupling process under solar drive to handle sewage, and collect evaporation water and concentrated water, determine water quality change situation.The application proposes a simple one-pot solvothermal method to synthesize MWCNTs@NH2-MIL-88B(Fe) composite material, and then load it into a double network hydrogel composed of PVA and gelatin.Using the high light absorption capacity and superior electron transfer ability of MWCNTs, combined with the unique Fenton effect of NH2-MIL-88B(Fe) (NM88B), the hydrogel with rich pore structure can simultaneously perform photocatalytic degradation and photovoltaic evaporation processes, ultimately achieving the removal of clean water and organic pollutants.

Description

Technical Field

[0001] This invention belongs to the field of environmental protection technology and relates to the preparation and application of a photoevaporation-photocatalysis coupled hydrogel. Background Technology

[0002] Globally, the imbalance between water supply and demand is intensifying, water pollution is becoming increasingly prominent, and years of drought and climate change have further exacerbated water scarcity. Currently, traditional water purification technologies, such as reverse osmosis, electrodialysis, and electrocatalysis, rely on energy-intensive processes, making their operation and maintenance costs high. These technologies also contribute to environmental pollution and greenhouse gas emissions. Furthermore, most water treatment processes lead to secondary pollution because organic pollutants accumulate or migrate in the environment, putting pressure on the sustainable development of humanity and the planet.

[0003] Solar-driven interfacial photoevaporation technology can achieve environmentally friendly, low-cost, and electricity-free clean water production, showing great potential in sustainable water treatment. Meanwhile, photocatalysis technology can remove most organic pollutants from wastewater through active oxidation-reduction reactions. Therefore, combining these two photoresponsive technologies is a reliable method for addressing complex water source treatment and achieving sustainable clean water production.

[0004] This invention proposes a method for coupling materials with high light absorption and photocatalytic capabilities within a hydrogel polymer network to prepare a photoevaporation-photocatalytic coupled hydrogel for efficient and complex wastewater treatment. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by providing a photoevaporation-photocatalysis coupled hydrogel for the comprehensive treatment of wastewater (seawater, methylene blue solution, tetracycline solution). A simple one-pot solvothermal method is proposed to synthesize MWCNTs@NH2-MIL-88B(Fe) composite materials, which are then loaded onto a dual-network hydrogel composed of PVA and gelatin. Utilizing the high light absorption and superior electron transfer capabilities of MWCNTs, combined with the unique Fenton effect of NH2-MIL-88B(Fe)(NM88B), photocatalytic degradation and photoevaporation processes can simultaneously occur within the hydrogel's richly porous structure, ultimately achieving the simultaneous acquisition of clean water and removal of organic pollutants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing a photoevaporation-photocatalysis coupled hydrogel and its application in integrated wastewater treatment: The prepared hydrogel is placed on the surface of various types of wastewater (seawater, methylene blue solution, tetracycline solution), and a photoevaporation-photocatalysis coupled process is carried out under solar energy to treat the wastewater. The evaporated water and concentrated water are collected, and the changes in water quality are measured. This includes:

[0008] A method for preparing a photoevaporation-photocatalysis coupled hydrogel, specifically comprising:

[0009] (1) Ferric chloride hexahydrate, 2-aminoterephthalic acid and multi-walled carbon nanotubes (MWCNTs) were uniformly dispersed in N,N-dimethylformamide (DMF) in sequence;

[0010] (2) The above mixed solution was kept in a Teflon-lined high-pressure reactor at a certain temperature for a certain time, and the solid phase and liquid phase were separated by centrifugation. The solid phase was washed several times with DMF and anhydrous ethanol.

[0011] (3) Disperse a certain amount of the above product evenly in deionized water to form a suspension, add a certain proportion of PVA and gelatin, and keep it at a certain temperature for a certain time to ensure that PVA and gelatin are completely dissolved.

[0012] (4) Add ammonium persulfate as an initiator and glutaraldehyde as a crosslinking agent to the solution obtained in step (3), and after molding and gelling for 2 hours, obtain MWCNTs@NM88B-based double network hydrogel (named MMH);

[0013] (5) The MMH obtained by the above polymerization was washed several times and soaked in deionized water for 24 hours to remove unreacted substances. Finally, it was freeze-dried under vacuum to obtain a porous hydrogel.

[0014] Meanwhile, pure NM88B powder (without MWCNTs) was prepared using the same method and introduced into a dual-network structure to construct an NM88B-based dual-network hydrogel (named MH).

[0015] Secondly, photoevaporation and photocatalysis experiments were conducted on the two hydrogels to evaluate their photoevaporation-photocatalysis coupling performance. The evaporation rates of MH and MMH from real seawater (Yellow Sea seawater) under one day of sunlight were 1.36 kg / (m³). 2 h) and 2.86 kg / (m 2Furthermore, under simulated sunlight irradiation (one solar intensity) for one and a half hours, MH achieved a degradation rate of 70.1% for 25 ppm methylene blue (MB) solution, while MMH reached 99.7%. Additionally, under the same time and solar intensity, MH could only degrade 61.1% of tetracycline solution (TC, 20 ppm), while MMH achieved 86.6%. Furthermore, simulated solar evaporation experiments were conducted on MMH for MB and TC to evaluate the photoevaporation-photocatalytic coupling performance of MMH. The results showed that the evaporation rates of MMH in the two wastewaters were 2.74 kg / (m³). 2 h) and 2.73 kg / (m 2 h). The above results indicate that, compared with MH, MMH has superior photoevaporation-photocatalysis coupling performance and can be applied to the comprehensive treatment of complex wastewater.

[0016] The beneficial effects of this invention are as follows:

[0017] This invention provides a method for preparing a hydrogel with a photoevaporation-photocatalysis coupling effect, which can be used for the treatment of complex wastewater, especially organic wastewater. Compared with the prior art, this invention has the following advantages:

[0018] 1. Due to the excellent electron transport and adsorption capabilities of MWCNTs, they can provide electron transport channels and reactive sites, thereby improving the shortcomings of poor conductivity and difficulty in rapid separation of photogenerated electrons and holes in single-component NM88B photocatalytic materials, and enhancing the photocatalytic performance of its composite materials.

[0019] 2. Traditional MOF materials exist in the form of nanoparticles or powders, which have poor processability and face challenges related to reusability, separation, and safety. Introducing them into hydrogels can improve the recyclability of powder materials in practical applications.

[0020] 3. Traditional hydrogel evaporators can only obtain clean fresh water from saline wastewater or seawater through photoevaporation, and cannot treat organic pollutants in wastewater, thus limiting their application. The use of the novel photoabsorbent MWCNTs@NM88B can achieve the coupling of photoevaporation and photocatalysis of hydrogels, thereby broadening its application scenarios in water treatment.

[0021] 4. This technology is pollution-free, environmentally friendly, and has a wide range of applications. It is expected to be widely used in the field of harmless treatment of complex wastewater such as high-salinity wastewater, organic wastewater, and medical wastewater. Attached Figure Description

[0022] Figure 1 This invention uses MWCNTs (in the embodiments) Figure 1 (a)) and the prepared NM88B ( Figure 1 (b) and MWCNTs@NM88B powder ( Figure 1 (c) scanning electron microscope image;

[0023] Figure 2 This is a scanning electron microscope image of the MMH prepared according to Example 2 of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments.

[0025] Example 1

[0026] Ferric chloride hexahydrate (FeCl3-6H2O, 0.27 g) and 2-aminoterephthalic acid (0.5 g) were dissolved in DMF (30 mL) by sonication for 5 minutes to form a homogeneous solution. The solution was then transferred to a 100 mL Teflon-lined autoclave and maintained at 100 °C for 10 hours. After natural cooling, NM88B powder was obtained by centrifugation and repeated washing with DMF and anhydrous ethanol. The resulting brown NM88B powder was then dried in a vacuum oven at 70 °C for 12 hours.

[0027] Next, 75 mg of NM88B powder was added to 10 mL of deionized water and sonicated for 30 minutes to ensure uniform dispersion. 0.25 g of PVA and 0.25 g of gelatin were added to the above solution, and the resulting mixture was kept in a magnetic stirrer at 65 °C and 400 rpm for 2 hours. Subsequently, 1 mL of ammonium persulfate solution (APS, 10 wt.%) was added as a crosslinking agent, and the mixture was stirred for another 10 minutes. Next, glutaraldehyde solution (1 mL, 25 wt.%) was added to solution A to initiate gelation. The mixture was kept at 40 °C for 2 hours until it was completely gelled, and the resulting gel was named MH. MH was washed three times with deionized water and soaked in deionized water for 12 hours to remove unreacted impurities. Finally, MH was rapidly frozen in liquid nitrogen and thawed in deionized water at 30 °C; this process was repeated 10 times to obtain a hydrogel with a porous structure.

[0028] Hydrogels were placed on the surfaces of different wastewaters (seawater, methylene blue solution, and tetracycline solution), with the bottom of the hydrogel in contact with the wastewater. An interfacial photoevaporation-photocatalysis coupling process was then carried out under solar energy. The photoevaporation rate was measured, and the evaporated water and treated wastewater were collected to determine changes in water quality.

[0029] Example 2

[0030] Ferric chloride hexahydrate (FeCl3-6H2O, 0.27 g) and 2-aminoterephthalic acid (0.5 g) were dissolved in DMF (30 mL) by sonication for 5 minutes to form a homogeneous solution. 0.025 g of MWCNTs were added to this solution and sonicated for 30 minutes. The solution was then transferred to a 100 mL Teflon-lined autoclave and maintained at 100 °C for 10 hours. After natural cooling, MWCNTs@NM88B powder was obtained by centrifugation. The resulting black MWCNTs@NM88B powder was then dried in a vacuum furnace at 70 °C for 12 hours. The powder was repeatedly washed with DMF and anhydrous ethanol to obtain MWCNTs@NM88B powder. The resulting brown MWCNTs@NM88B powder was then dried in a vacuum furnace at 70 °C for 12 hours.

[0031] Next, 75 mg of MWCNTs@NM88B powder was added to 10 mL of deionized water and sonicated for 30 minutes to ensure uniform dispersion. 0.25 g of PVA and 0.25 g of gelatin were added to the above solution, and the resulting mixture was kept at 65 °C and 400 rpm for 2 hours using a magnetic stirrer. Subsequently, 1 mL of ammonium persulfate solution (APS, 10 wt.%) was added as a crosslinking agent, and the mixture was stirred for another 10 minutes. Next, glutaraldehyde solution (1 mL, 25 wt.%) was added to solution A to initiate gelation. The mixture was kept at 40 °C for 2 hours until it was completely gelled, and the resulting gel was named MMH. MMH was washed three times with deionized water and soaked in deionized water for 12 hours to remove unreacted impurities. Finally, MMH was rapidly frozen in liquid nitrogen and thawed in deionized water at 30 °C; this process was repeated 10 times to obtain a hydrogel with a porous structure.

[0032] Hydrogels were placed on the surfaces of different wastewaters (seawater, methylene blue solution, and tetracycline solution), with the bottom of the hydrogel in contact with the wastewater. An interfacial photoevaporation-photocatalysis coupling process was then carried out under solar energy. The photoevaporation rate was measured, and the evaporated water and treated wastewater were collected to determine changes in water quality.

[0033] In summary, the two hydrogels in the examples were characterized and experimentally tested, based on... Figure 1 The results show that MWCNTs ( Figure 1 (a)) and the prepared NM88B powder ( Figure 1 (b) exhibits microstructures that are tubular and uniform polyhedral shapes, respectively. Figure 1 (c) It can be seen that NM88B is uniformly distributed on the surface of MWCNTs, and they are closely connected to each other to form MWCNTs@NM88B composite material. Figure 2The results show that MMH exhibits a porous network structure with pore sizes ranging from a few micrometers to tens of micrometers. These porous network structures derived from PVA and gelatin can promote water transport through capillary action, thereby enhancing water evaporation, and can also provide numerous active sites for the retention of guest molecules. Therefore, Example 2 is the optimal solution, and thus, Example 2 is the best choice.

[0034] The above embodiments are merely preferred embodiments of the present invention and therefore cannot be used to limit the scope of the present invention. Any modifications or changes made based on the embodiments and description of the present invention should still fall within the scope of the present invention.

Claims

1. The application of a photoevaporation-photocatalysis coupled hydrogel in integrated wastewater treatment, including the treatment of seawater, methylene blue solution, and tetracycline solution; wherein: This photoevaporation-photocatalysis coupled hydrogel was prepared by the following method: (1) The first solution was obtained by uniformly dispersing ferric chloride hexahydrate, 2-aminoterephthalic acid and MWCNTs in N,N-dimethylformamide in sequence; (2) The first solution was kept in a Teflon-lined autoclave at a certain temperature for a certain time, and the solid and liquid phases were separated by centrifugation. The solid phase was washed several times with DMF and anhydrous ethanol to obtain the first product. (3) A certain amount of the first product is uniformly dispersed in deionized water to form a suspension. A certain proportion of PVA and gelatin are added and kept at a certain temperature for a certain time to allow the PVA and gelatin to completely dissolve, thus obtaining the second solution. (4) Add the initiator ammonium persulfate and the crosslinking agent glutaraldehyde to the second solution. After molding and gelling for 2 hours, MWCNTs@NM88B-based double network hydrogel is obtained and named MMH. (5) Rinse MMH several times and soak it in deionized water for 12 hours. Finally, freeze it rapidly in liquid nitrogen and then thaw it in deionized water at 30°C. Repeat the freezing and thawing operation 10 times to obtain a photoevaporation-photocatalysis coupled hydrogel.

2. The application according to claim 1, wherein: In step (1), the amounts of ferric chloride hexahydrate, 2-aminoterephthalic acid, MWCNTs, and N,N-dimethylformamide are 0.27 g, 0.5 g, 0.025 g, and 30 mL, respectively.

3. The application according to claim 1, wherein: The temperature in step (2) is 100℃ and the time is 10h.

4. The application according to claim 1, wherein: Step (2) The first product further includes a drying process, under the following conditions: Dry at 70℃ for 12 hours.

5. The application according to claim 1, wherein: In step (3), the mass-to-volume ratio of the first product to deionized water is 75 mg: 10 ml; The mass of both PVA and gelatin is 0.25g; The temperature mentioned in step (3) is 65℃ and the time is 2h.

6. The application according to claim 1, wherein: The ammonium persulfate used in step (4) has a mass fraction of 10% and a dosage of 1 ml. The glutaraldehyde has a mass fraction of 25% and is used in a volume of 1 ml. The injection-molded gel was kept at 40°C for 2 hours to obtain MWCNTs@NM88B-based dual-network hydrogel, named MMH.

7. The application according to claim 1, wherein: The number of MMH rinses in step (5) is 3.

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