A photothermal sponge based on cross-linked immobilization of catalysts, and a preparation method and application thereof

Abstract

The application provides a kind of photothermal sponge based on hydrogel crosslinking fixed catalyst and its preparation method and application, and a large number of loading sites and three-dimensional structure on porous sponge are fixed under the catalysis of catalyst particles, and the photothermal sponge is prepared, and then the photothermal sponge is used to treat salt-containing organic wastewater under solar light.The application has the advantages of simple preparation process, enhanced catalyst particle fixing effect, solved problems of unstable catalyst particles and high ion leaching rate, and prolonged service life of the sponge.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically relates to a photothermal sponge based on a hydrogel crosslinking and catalyst immobilization method and its preparation method and application. Background Technology

[0002] With population growth and rapid economic development, industrial production has expanded continuously, making water pollution a pressing environmental challenge. It is estimated that 80% of industrial and domestic wastewater is discharged into the environment untreated. This wastewater is complex, containing various persistent organic pollutants and high concentrations of salt. Traditional water treatment methods face numerous difficulties in treating such complex wastewater. However, solar interfacial evaporation technology offers a solution. This technology utilizes clean and continuous solar energy, applying heat to the interface to evaporate surface moisture, effectively separating salt from water. However, this technology has limited effectiveness in treating organic matter. During the photothermal process, water evaporation leads to the accumulation of non-volatile organic pollutants in the raw water, while volatile pollutants evaporate with water into the condensate, affecting the quality of the produced water. To address this problem, a method combining solar interfacial evaporation with advanced oxidation processes has emerged.

[0003] Advanced persulfate-based oxidation processes can effectively degrade organic matter into harmless substances such as carbon dioxide and water by rapidly generating highly oxidizing free radicals. Considering that interfacial solar evaporation positions heat at the water surface, the design of combining photothermal materials and catalysts at the photothermal interface offers new possibilities for simultaneously producing freshwater and removing pollutants from water sources. However, most catalysts exist in particulate form, and fixing catalyst particles to an interfacial carrier through physical adsorption is unstable and prone to detachment. Detachment of catalyst particles in solution leads to the leaching of contained metal ions. These leached metal ions entering the treated water can cause secondary pollution, harming the ecological environment and human safety. Simultaneously, ion leaching also affects the stability and reusability of the catalyst, reducing its lifespan. Therefore, addressing the issues of particle detachment and ion leaching is essential when treating saline organic wastewater. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a photothermal sponge based on hydrogel crosslinking and catalyst immobilization, its preparation method, and its applications. This invention immobilizes photothermal catalyst particles on a porous sponge through the crosslinking effect of hydrogel, effectively solving the problems of particle detachment and ion leaching. Under sunlight, the synergistic effect of the catalyst and persulfate enables highly efficient treatment of saline organic wastewater. The photothermal sponge prepared by this invention exhibits excellent desalination performance in high-salinity water and also demonstrates good activation effect on persulfate, enabling efficient removal of organic pollutants from wastewater.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] The first aspect of this invention provides a method for preparing a photothermal sponge based on a hydrogel crosslinking-immobilized catalyst, comprising the following steps:

[0007] (1) Add a certain amount of catalyst particles to deionized water and disperse them evenly by ultrasonication for 2-5 hours to obtain a catalyst solution;

[0008] (2) Preparation of mixed solution A: Dissolve polyvinyl alcohol powder in deionized water to achieve a polyvinyl alcohol concentration of 1-10 wt%, dissolve at 60-95℃ for 0.5-8 h to obtain mixed solution A;

[0009] (3) Preparation of mixed solution B: Mix glutaraldehyde and deionized water at a volume ratio of 1:200 to 1:50, then add hydrochloric acid, wherein the volume ratio of glutaraldehyde to hydrochloric acid is 1:1 to 1:8, and stir for 2 to 48 hours to obtain mixed solution B;

[0010] (4) Place the sponge into the catalyst solution obtained in step (1), repeatedly immerse it, and then take it out and dry it; then put it into mixed solution A, completely immerse it, take it out and put it into mixed solution B for hydrothermal reaction. The hydrothermal temperature is 40-80℃ and the hydrothermal reaction time is 0.5-2h. After taking it out, wash it with deionized water 2-5 times and then dry it to obtain the photothermal sponge.

[0011] Furthermore, in step (1), the catalyst content in the catalyst solution is 0.1-10 g / L, preferably 0.5-4 g / L; the catalyst particles are cobalt ferrite carbon nanotubes.

[0012] Furthermore, in step (2), the degree of alcoholysis of the polyvinyl alcohol powder is 77-99%; the mass concentration of polyvinyl alcohol is preferably 2wt%; the dissolution temperature is preferably 90℃; and the dissolution time is preferably 2h.

[0013] Furthermore, in step (3), the volume concentration of glutaraldehyde is 90%, the concentration of hydrochloric acid is 0.5-2 mol / L, preferably 1.0 mol / L; the volume ratio of glutaraldehyde to deionized water is preferably 1:100; the volume ratio of glutaraldehyde to hydrochloric acid is preferably 1:2-1:4, and the stirring time is preferably 10 h.

[0014] Furthermore, in step (4), the sponge includes polyurethane sponge and melamine sponge; the catalyst loading on the sponge is 0.1-4%, preferably 0.2%; the hydrothermal temperature is preferably 60°C, and the hydrothermal reaction time is preferably 1h.

[0015] In step (4), the drying conditions are: oven temperature 40-50℃ for 1-4 hours; preferably 45℃ for 2 hours.

[0016] The second aspect of the present invention provides a photothermal sponge with a hydrogel crosslinked and fixed catalyst prepared by the method described in the first aspect.

[0017] The third aspect of this invention provides the application of the photothermal sponge with the hydrogel crosslinking and catalyst immobilized as described in the second aspect in the treatment of saline organic wastewater.

[0018] Furthermore, the application method includes the following steps:

[0019] Under stirring conditions, persulfate is added to saline organic wastewater to form a mixed solution; the photothermal sponge described in the second aspect floats on the mixed solution with the support of polyethylene sponge, and the saline organic wastewater is treated by irradiating the photothermal interface (i.e. the part of the photothermal sponge that is irradiated by sunlight) with sunlight.

[0020] Furthermore, the concentration of the persulfate is 0.1–8 mM; the salinity of the saline organic wastewater is 0.1–5%; the pH of the mixed solution is 1–13; the pollutants in the organic wastewater include one or more of phenol, aniline, sulfamethoxazole, N,N-dimethylformamide, dyes, or antibiotics; and the duration of sunlight irradiation of the photothermal interface is 3–12 hours.

[0021] The advantages of this invention compared to the prior art are as follows:

[0022] 1. Synergistic Achievement of Efficient Desalination and Pollutant Degradation: This invention innovatively combines photothermal evaporation technology with advanced oxidation processes. Through the synergistic effect of the three-dimensional porous structure of the photothermal sponge and the catalyst immobilized by the hydrogel, two core functions are simultaneously achieved under solar energy drive:

[0023] - The desalination rate can reach 99.9%, significantly reducing the salt content in the condensate and meeting the needs of freshwater production;

[0024] - It achieves a degradation rate of up to 100% for various pollutants (such as phenol, sulfamethoxazole, dyes, etc.) in saline organic wastewater, while reducing the concentration of organic matter in the raw liquid and condensate, thus solving the problem of pollutant enrichment or migration in traditional photothermal evaporation technology.

[0025] 2. Significantly improves catalyst stability and avoids secondary pollution: A hydrogel cross-linking method is used to firmly encapsulate catalyst particles (such as cobalt ferrite carbon nanotubes) on a sponge support through a cross-linking network of polyvinyl alcohol and glutaraldehyde, forming a stable "hydrogel-catalyst-sponge" composite structure.

[0026] - Effectively solves the problem of catalyst particles easily falling off in traditional physical adsorption methods, and still maintains high efficiency after 5 cycles of experimentation;

[0027] - The concentration of metal ion leaching is significantly reduced, avoiding secondary pollution of water bodies caused by ion leakage, which is more in line with environmental protection requirements.

[0028] 3. Optimize mass transfer and energy utilization efficiency:

[0029] - The hydrogel network enhances the hydrophilicity of the sponge, accelerates the transfer of moisture to the photothermal interface, and strengthens the evaporation efficiency;

[0030] - The three-dimensional network structure of the sponge not only provides a large number of loading sites for the catalyst, but also enhances the contact probability between active free radicals and pollutants through the confinement effect, while improving light absorption efficiency, thus realizing the efficient conversion and utilization of solar energy.

[0031] 4. The preparation process is simple and has the potential for large-scale application: The preparation process of this invention only requires simple steps such as impregnation and hydrothermal reaction, without the need for complex equipment, and the raw materials used, such as polyvinyl alcohol, glutaraldehyde, and polyurethane foam, are inexpensive and easy to obtain.

[0032] - The entire process generates no toxic byproducts, making it environmentally friendly;

[0033] - Photothermal sponges are reusable, have low operating costs, and are suitable for large-scale promotion in high-salt organic wastewater treatment scenarios.

[0034] In summary, this invention, through material design and process innovation, improves wastewater treatment efficiency while taking into account stability, environmental friendliness, and economy, providing a practical solution for the efficient purification of saline organic wastewater. Attached Figure Description

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0036] Figure 1 Scanning electron microscope image of the prepared photothermal sponge;

[0037] Figure 2 A schematic diagram of the application structure of the prepared photothermal sponge; wherein, 1-photothermal sponge, 2-polyethylene sponge, 3-salt-containing organic wastewater;

[0038] Figure 3 This is a comparison chart showing the effects of photothermal sponges in Examples 1, 2, 3 and the persulfate-free group on desalination and phenol degradation in saline organic wastewater;

[0039] Figure 4 This is a diagram illustrating the effect of the solar interface evaporator prepared in Example 1 on the cyclic treatment of saline organic wastewater.

[0040] Figure 5 This is a graph showing the ion leaching concentration when the photothermal sponge in Example 1 treats saline organic wastewater;

[0041] Figure 6 This is a comparison chart showing the effects of photothermal sponges in Examples 1, 2, 3 and the persulfate-free group on desalination and degradation of sulfamethoxazole in saline organic wastewater. Detailed Implementation

[0042] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0043] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0044] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to exemplify and further explain and illustrate the content of the present invention, and are not intended to limit the present invention.

[0045] Example 1

[0046] This embodiment provides a method for preparing a photothermal sponge based on a hydrogel crosslinking and catalyst immobilization, including the following steps:

[0047] (1) Add 0.6g of CoFe2O4@CNT particles to 150mL of deionized water and sonicate for 2-5h to disperse evenly to obtain a catalyst solution;

[0048] (2) Preparation of mixed solution A: 2g of polyvinyl alcohol powder with a degree of alcoholysis of 99% was added to 100mL of deionized water, the dissolution temperature was 90℃ and the dissolution time was 2h to obtain mixed solution A;

[0049] (3) Preparation of mixed solution B: Mix 0.5 mL of glutaraldehyde with 50 mL of deionized water and add 1 mL of 0.1 mol / L hydrochloric acid. Stir for 10 h to obtain mixed solution B;

[0050] (4) The polyurethane sponge is placed in the catalyst solution obtained in step (1), and after repeated immersion, it is taken out and dried in an oven at 45°C for 2 hours; then it is placed in mixed solution A, completely submerged, and then placed in mixed solution B for hydrothermal reaction. The hydrothermal temperature is 60°C and the hydrothermal reaction time is 1 hour. After taking it out, it is washed with deionized water 2 to 5 times and then dried in an oven at 45°C for 2 hours to obtain the photothermal sponge.

[0051] Figure 1 The image shows a scanning electron microscope image of the prepared photothermal sponge. Figure 1 It can be seen that the photothermal sponge prepared in Example 1 has a three-dimensional porous network structure, which helps the catalyst particles to adhere and be fixed.

[0052] Example 2

[0053] The difference from Example 1 is that no catalyst particles are added in step (1), but the rest is the same as in Example 1.

[0054] Example 3

[0055] The difference from Example 1 is that in step (4), both mixed solution A and mixed solution B are replaced with deionized water, while the rest is the same as in Example 1.

[0056] Example 4: Treatment of saline organic wastewater by photothermal sponge

[0057] The different photothermal sponges prepared in Examples 1-3 were applied to the treatment of high-salt organic wastewater (organic pollutant: phenol). The specific methods are as follows:

[0058] Under stirring conditions, persulfate was added to a 100mL beaker containing 100mL of saline organic wastewater to form a mixture.

[0059] like Figure 2As shown, the photothermal sponge (1) prepared in Examples 1, 2, and 3 was floated on the solution under the support of a polyethylene sponge (2). The polyethylene sponge was ring-shaped, and its inner ring diameter was the same as that of the photothermal sponge. The prepared photothermal sponge was placed inside the polyethylene sponge, and the thickness of the photothermal sponge was greater than that of the polyethylene sponge. The photothermal interface was irradiated with sunlight for 2 hours to treat saline organic wastewater (3). The concentration of persulfate was 2 mM; the salinity of the saline organic wastewater was 2%; the organic pollutant was phenol; and the pH of the mixed solution was 7. At the same time, a control group was prepared by treating high-salt organic wastewater with only photothermal sponge without adding persulfate (referred to as the persulfate-free group).

[0060] The concentration of phenol, an organic pollutant, in the stock solution and condensate was determined using high performance liquid chromatography and a conductivity meter. The conductivity of salt pollutants before and after removal was also measured. The removal rate and desalination rate were then calculated.

[0061] Figure 3 The graphs show the effects of Examples 1, 2, 3, and the persulfate-free group on desalination and degradation of organic pollutants in high-salt organic wastewater. Figure 3 It can be seen that the photothermal sponge prepared in Example 1 has the effect of simultaneous desalination and degradation of organic matter, with a desalination rate of 99.9% and a phenol removal effect of 100% in both the original solution and the condensate.

[0062] Example 5: Recycling of Photothermal Sponge

[0063] To investigate the stability and regenerability of the photothermal sponge prepared in Example 1, the following experiments were conducted in this example:

[0064] The photothermal sponge treated with wastewater in Example 4 was soaked in deionized water for 1 hour and then dried to obtain a regenerated photothermal sponge. Under stirring conditions, persulfate was added to a 100mL beaker containing 100mL of saline organic wastewater to form a mixture; as follows... Figure 2 As shown, the regenerated photothermal sponge (1) was floated on the solution under the support of a polyethylene sponge (2), and the photothermal interface was irradiated with sunlight for 2 hours to treat saline organic wastewater (3). The concentration of persulfate was 2 mM; the salinity of the saline organic wastewater was 2%; the organic pollutant was phenol; and the pH of the mixed solution was 7. The above operation was repeated 5 times. The concentration of organic pollutant phenol in the bottom solution and the conductivity of salt pollutants before and after removal were measured using high performance liquid chromatography and a conductivity meter. The degradation rate and desalination rate were calculated, and the results are shown in the figure. Figure 4 As shown.

[0065] Figure 4 This is an illustration of the effect of recycling saline organic wastewater. Figure 4It can be seen that even after being recycled five times, the solar interface evaporator prepared in Example 1 still exhibits efficient desalination and degradation of organic pollutants, thus demonstrating that the solar interface evaporator of the present invention has good stability and regenerability.

[0066] Figure 5 This is a comparison chart of iron and cobalt ion concentrations during the recycling of saline organic wastewater. Figure 5 It can be seen that the leaching concentration of metal ions in the bottom solution of the photothermal sponge prepared by the method of Example 1 after 1 to 5 cycles is much lower than that of the photothermal sponge without hydrogel fixation in Example 3. This indicates that the cross-linking effect of the hydrogel in this invention can stably fix the catalyst particles on the sponge, effectively inhibit the leaching of metal ions in the solution, thereby reducing the toxicity of metal leaching and avoiding secondary pollution.

[0067] Example 6: Treatment of saline organic wastewater by photothermal sponge

[0068] The difference from Example 4 is that the organic pollutant treated in this example is sulfamethoxazole.

[0069] Figure 6 This image shows the effect of different photothermal sponges on desalination and degradation of organic pollutants in high-salt organic wastewater. Figure 6 It can be seen that the photothermal sponge described in Examples 1 and 3 has the effect of simultaneous desalination and degradation of organic matter, with a desalination rate of 99.9% and a removal effect of 100% on sulfamethoxazole in the original solution.

[0070] Finally, it should be noted that the above description is only used to illustrate the technical solutions of the present invention and is not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention.

Claims

1. An application of a photothermal sponge based on a hydrogel crosslinking-immobilized catalyst in the treatment of saline organic wastewater, characterized in that, The preparation method of the photothermal sponge includes the following steps: (1) A certain amount of catalyst particles are added to deionized water and ultrasonically dispersed for 2-5 h to obtain a catalyst solution; the catalyst content in the catalyst solution is 0.1-10 g / L; the catalyst particles are cobalt ferrite carbon nanotubes; (2) Preparation of mixed solution A: Polyvinyl alcohol powder is dissolved in deionized water to achieve a polyvinyl alcohol concentration of 1-10 wt%, the dissolution temperature is 60-95 ℃, and the dissolution time is 0.5-8 h to obtain mixed solution A; the degree of alcoholysis of the polyvinyl alcohol powder is 77-99%; (3) Preparation of mixed solution B: Mix glutaraldehyde and deionized water at a volume ratio of 1:200 to 1:50, then add hydrochloric acid, wherein the volume ratio of glutaraldehyde to hydrochloric acid is 1:1 to 1:8, and stir for 2 to 48 hours to obtain mixed solution B; (4) The sponge is immersed in the catalyst solution obtained in step (1) repeatedly, then removed and dried; then it is placed in mixed solution A, completely submerged, then removed and placed in mixed solution B for hydrothermal reaction. The hydrothermal temperature is 40~80℃, and the hydrothermal reaction time is 0.5~2 h. After removal, it is washed with deionized water 2~5 times and dried to obtain the photothermal sponge; the catalyst loading on the sponge is 0.1~4%; The application method includes the following steps: Under stirring conditions, persulfate is added to saline organic wastewater to form a mixed solution; the prepared photothermal sponge is floated on the mixed solution with the support of polyethylene sponge, and the photothermal interface is irradiated by sunlight to treat the saline organic wastewater. The concentration of the persulfate is 0.1-8 mM; the salinity of the saline organic wastewater is 0.1-5%; the pH of the mixed solution is 1-13; the pollutants in the organic wastewater include one or more of phenol, aniline, sulfamethoxazole, and N,N-dimethylformamide; and the duration of sunlight irradiation on the photothermal interface is 3-12 hours.

2. The application according to claim 1, characterized in that, In step (3), the volume concentration of glutaraldehyde is 90%, and the concentration of hydrochloric acid is 0.5~2 mol / L.

3. The application according to claim 1, characterized in that, In step (4), the sponge includes polyurethane sponge and melamine sponge.

4. The application according to claim 1, characterized in that, In step (4), the drying conditions are: oven 40~50 ℃, 1~4 h.

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