A photothermal foam gel and its preparation method and application

Abstract

The present invention provides a photothermal foam gel, a preparation method thereof and an application thereof. The preparation method of the photothermal foam gel comprises the following steps: (1) dissolving sodium alginate in an aqueous solution of a hydrophilic organic solvent to obtain a mixed solution; (2) adding a photocatalyst, a photothermal conversion agent and a surfactant to the mixed solution, mixing and reacting to obtain a reaction sol; wherein, the photocatalyst is Cu 2+1 O / Cu photocatalyst; (3) sequentially adding calcium carbonate and hydrochloric acid solution to the reaction sol, and stirring and reacting to obtain the photothermal foam gel. The photothermal foam gel prepared by the present invention has the advantages of low preparation cost, good effect on treating uranium-containing wastewater and being capable of being applied on a large scale, and clean water production can be realized by using the photothermal foam gel.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysis, and in particular to a photothermal foam gel and a preparation method and application thereof. Background Art

[0002] The rapid development of society has intensified the contradiction between energy demand and supply, and has also promoted the continuous exploration of sustainable energy. Compared with solar energy, geothermal energy and wind energy, nuclear energy, as a mature, green and sustainable clean energy, has become an important alternative to fossil energy. However, the development of nuclear energy is still restricted by the pollution of uranium-containing wastewater and the shortage of uranium resources. Therefore, the separation and recovery of uranium in uranium-containing wastewater has become an important guarantee for the sustainable development of nuclear energy.

[0003] In recent years, the international community has actively carried out research on the enrichment and separation technology of uranium in wastewater systems. Among them, the adsorption method has become one of the main methods for removing uranium from wastewater due to its advantages such as convenient operation, low economic cost and environmental friendliness. However, the adsorption method is still limited by the poor adsorption performance and low selectivity of the adsorbent. The photocatalytic method has the advantages of good selectivity, high efficiency and rapidity, non-toxicity and mild reaction conditions, so it has become one of the effective ways to repair uranium-containing wastewater.

[0004] In the related technology, there are a large number of photocatalysts used for the enrichment and separation of uranium nuclides in uranium-containing wastewater; however, these photocatalysts still have disadvantages such as high cost, poor treatment effect, and difficulty in large-scale production. In addition, most of the uranium-containing wastewater treated by photocatalysts is directly discharged into the environment. Due to the low treatment efficiency, the direct discharge of such wastewater not only poses a potential threat to the environment, but also causes a waste of water resources.

[0005] Therefore, based on the above problems, it is urgent to study a photothermal foam gel and a preparation method thereof. Summary of the invention

[0006] The present invention provides a photothermal foam gel and a preparation method and application thereof. The photothermal foam gel has the advantages of low preparation cost, good effect in treating uranium-containing wastewater and large-scale application, and the photothermal foam gel can be used to produce clean water.

[0007] In a first aspect, the present invention provides a method for preparing a photothermal foam gel, the preparation method comprising the following steps:

[0008] (1) dissolving sodium alginate in a hydrophilic organic solvent aqueous solution to obtain a mixed solution;

[0009] (2) adding a photocatalyst, a photothermal conversion agent and a surfactant to the mixed solution and mixing them to obtain a reaction sol; wherein the photocatalyst is Cu 2+1 O / Cu photocatalyst;

[0010] (3) Adding calcium carbonate and hydrochloric acid solution to the reaction sol in sequence, stirring and reacting to obtain the photothermal foam gel.

[0011] Preferably, the Cu 2+1 The preparation method of O / Cu photocatalyst comprises the following steps:

[0012] (21) adding sodium hydroxide to the aqueous solution of copper sulfate pentahydrate and mixing to obtain a reaction solution;

[0013] (22) Glucose is added to the reaction solution, and the Cu is obtained after stirring the reaction. 2+1 O / Cu photocatalyst.

[0014] Preferably, in step (21), the mass concentration of the copper sulfate pentahydrate aqueous solution is 0.04-0.08 g / mL; and the mass ratio of copper sulfate pentahydrate to sodium hydroxide is 2:(2.5-15).

[0015] Preferably, in step (21), the reaction temperature is 65-70°C and the reaction time is 5-15 min.

[0016] Preferably, in step (22), the mass ratio of sodium hydroxide to glucose is (1-4):1.

[0017] Preferably, in step (22), the stirring reaction temperature is 65-70° C. and the time is 60-70 min.

[0018] Preferably, in step (22), after the stirring reaction, the process further comprises the steps of centrifuging, washing and vacuum drying the reaction product in sequence.

[0019] Preferably, in step (1), in the hydrophilic organic solvent aqueous solution, the hydrophilic organic solvent is glycerol, and the volume ratio of the hydrophilic organic solvent to water is (5-8):3; and the amount of sodium alginate added is 2.0-3.0wt% of the total amount of the mixed solution.

[0020] Preferably, in step (2), the photothermal conversion agent is carbon black, ferric oxide or carbon nanotubes, and the surfactant is alkyl sulfate or polyethylene ether.

[0021] Preferably, the added amount of the photocatalyst is 0.02-0.2 g, the mass ratio of the photocatalyst to the photothermal conversion agent is (1-10):1, and the added amount of the surfactant is 1-3 wt % of the total amount of the reaction sol.

[0022] Preferably, in step (3), the concentration of the hydrochloric acid solution is 0.1-0.2 mol / L; and the amount of calcium carbonate added is 0.5-0.8 wt % of the amount of sodium alginate added.

[0023] In a second aspect, the present invention further provides a photothermal foam gel, which is prepared by any preparation method described in the first aspect.

[0024] In a third aspect, the present invention provides an application of a photothermal foam gel for photocatalytic degradation of uranium-containing wastewater and production of clean water.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] The present invention firstly mixes sodium alginate with a hydrophilic organic solvent and water, during which the sodium alginate and the hydrophilic organic solvent can self-assemble by hydrogen bonds, so that the sodium alginate and the hydrophilic organic solvent form a double network structure, then adds a photocatalyst, a photothermal conversion agent and a surfactant into the mixed solution, stirs and mixes them, and finally adds calcium carbonate and hydrochloric acid to the sodium alginate for sol-gel reaction, so as to prepare a photothermal foam gel loaded with a photocatalyst and a photothermal conversion agent and having good stability;

[0027] The photocatalyst in the foam gel of the present invention is a self-made defective Cu 2+1 O / Cu photocatalyst, the photocatalyst has good photocatalytic degradation performance for uranium-containing wastewater, when the photothermal foam gel is used to treat uranium-containing wastewater, the photothermal foam gel can float on the surface of the uranium-containing wastewater, firstly, the adsorption performance of the foam gel is used to adsorb uranium ions in the uranium-containing wastewater; at the same time, under the irradiation of sunlight, the photothermal converter can capture the energy of sunlight and convert it into heat energy, thereby further enhancing the adsorption effect of the foam gel on uranium ions in the uranium-containing wastewater, and then the Cu distributed in the foam gel 2+1 The O / Cu photocatalyst can photocatalytically degrade the adsorbed uranium ions, and this cycle can be repeated to achieve continuous degradation treatment of uranium-containing wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 is the XRD spectrum of the photocatalyst prepared in Examples 7 to 11 of the present invention; wherein the abscissa is the scanning angle;

[0030] Figure 2 : is the ESI result diagram of the photocatalyst prepared in Examples 7 to 11 of the present invention; wherein the abscissa is the real part of the impedance, representing the resistive loss, and the ordinate is the imaginary part of the impedance, representing the capacitive loss;

[0031] Figure 3 is the LSV result diagram of the photocatalyst prepared in Examples 7 to 11 of the present invention;

[0032] Figure 4 is a photocurrent response curve diagram of the photocatalysts prepared in Examples 7 to 11 of the present invention;

[0033] Figure 5 is the XRD spectrum of the photothermal foam gel provided in Example 1 of the present invention; wherein the abscissa is the scanning angle;

[0034] Figure 6 is a mechanical compression-strain curve diagram of the foam gel provided in Example 1 and Comparative Examples 3 to 4 of the present invention;

[0035] Figure 7 is a graph of compressive strength and compression modulus of the foam gel provided in Example 1 and Comparative Examples 3 to 4 of the present invention;

[0036] Figure 8 This is a result diagram of the effect of the foam gel provided in Example 1 of the present invention and Comparative Examples 3 to 4 on the removal of uranium from uranium-containing wastewater under different time and light conditions;

[0037] Fig. 9 is the isotherm fitting curve diagram of the foam gel provided in Example 1 and Comparative Examples 3 to 4 of the present invention;

[0038] Fig.10 It is a temperature change curve diagram of the foam gel provided in Example 1 and Comparative Examples 2, 3 and 4 of the present invention under light exposure at different time periods;

[0039] Fig.11 This is a graph showing the purified water production results of the foam gel provided in Example 1, Comparative Examples 2, 3 and 4 of the present invention within 11 hours;

[0040] Fig.12 is a graph showing the photocatalytic reduction effect of the photothermal foam gel provided in Example 1 of the present invention on uranium in uranium-containing wastewater and the clean water production within 15 days;

[0041] Fig.13 This is a graph showing the removal rate of uranium in uranium-containing wastewater and the water purification rate within 15 days by the photothermal foam gel provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] The embodiment of the present invention provides a method for preparing a photothermal foam gel, the preparation method comprising the following steps:

[0044] (1) dissolving sodium alginate in a hydrophilic organic solvent aqueous solution to obtain a mixed solution;

[0045] (2) adding a photocatalyst, a photothermal conversion agent and a surfactant to the mixed solution and mixing them to obtain a reaction sol; wherein the photocatalyst is Cu 2+1 O / Cu photocatalyst;

[0046] (3) Adding calcium carbonate and hydrochloric acid solution to the reaction sol in sequence, stirring and reacting to obtain the photothermal foam gel.

[0047] In the embodiment of the present invention, sodium alginate is first mixed with a hydrophilic organic solvent and water. During the mixing process, sodium alginate and the hydrophilic organic solvent can self-assemble by hydrogen bonds, so that sodium alginate and the hydrophilic organic solvent form a double network structure. Then, a photocatalyst, a photothermal converter and a surfactant are added to the mixed solution and stirred and mixed. Finally, calcium carbonate and hydrochloric acid are added to the sodium alginate and the like to perform a sol-gel reaction, thereby preparing a photothermal foam gel loaded with a photocatalyst and a photothermal converter and having good stability. At the same time, the photocatalyst in the foam gel of the embodiment of the present invention is a self-made defective Cu 2+1 O / Cu photocatalyst, the photocatalyst has good photocatalytic degradation performance for uranium-containing wastewater, and when the photothermal foam gel is used to treat uranium-containing wastewater, the photothermal foam gel can float on the surface of the uranium-containing wastewater, and firstly, the adsorption performance of the foam gel is used to adsorb uranium ions in the uranium-containing wastewater. At the same time, under the irradiation of sunlight, the photothermal converter can capture the energy of sunlight and convert it into heat energy, thereby further enhancing the adsorption effect of the foam gel on uranium ions in the uranium-containing wastewater, and then the Cu distributed in the foam gel 2+1 The O / Cu photocatalyst can photocatalytically degrade the adsorbed uranium ions, and this cycle can be repeated to achieve continuous degradation treatment of uranium-containing wastewater.

[0048] According to some preferred embodiments, the Cu 2+1 The preparation method of O / Cu photocatalyst comprises the following steps:

[0049] (21) adding sodium hydroxide to an aqueous solution of copper sulfate pentahydrate and mixing to obtain a reaction solution;

[0050] (22) Glucose is added to the reaction solution, and the Cu is obtained after stirring the reaction. 2+1 O / Cu photocatalyst.

[0051] Different from the traditional preparation methods of photocatalysts (such as hydrothermal method and calcination method), the present invention uses a one-step wet chemical reduction method to prepare the photocatalyst. First, copper sulfate pentahydrate solution and sodium hydroxide are stirred to react without using a surfactant to regulate the morphology of the photocatalyst. Then, glucose is used for oxidation and reduction to simultaneously achieve metal defect cuprous oxide (Cu 2+1 O), and successfully reduces part of divalent copper to metallic copper. Meanwhile, the photocatalyst is a composite structure of metallic copper and defective cuprous oxide, the prepared metallic copper is uniformly coated on the surface of the metallic defective cuprous oxide, the metallic defective photocatalyst has a good crystallization effect, and the composite structure is conducive to reducing the contact interface barrier, improving the efficiency of hot electron transfer, and has excellent photocatalytic degradation performance for uranium ions. Compared with the hydrothermal method, the method does not require high temperature and high pressure conditions, and compared with the calcination method, the crystal structure is controllable; the preparation process is non-toxic and pollution-free, has no by-products, does not require the adaptation of special equipment, has low economic cost, and has mild reaction conditions, and is suitable for industrial-scale production.

[0052] According to some preferred embodiments, in step (21), the mass concentration of the copper sulfate pentahydrate aqueous solution is 0.04-0.08 g / mL (for example, it can be 0.04 g / mL, 0.05 g / mL, 0.06 g / mL, 0.07 g / mL or 0.08 g / mL); the mass ratio of copper sulfate pentahydrate to sodium hydroxide is 2:(2.5-15) (for example, it can be 2:2.5, 2:5, 2:10 or 2:15); the reaction temperature is 65-70°C (for example, it can be 65°C, 66°C, 67°C, 68°C, 69°C or 70°C), and the reaction time is 5-15 min (for example, it can be 5 min, 10 min or 15 min).

[0053] In the embodiment of the present invention, the stoichiometric ratio of cuprous oxide is regulated by controlling the addition amount of cupric sulfate pentahydrate, sodium hydroxide and glucose during the reaction process, and metal excess point defects are introduced to regulate the energy level structure of cuprous oxide, thereby effectively improving the heterojunction interface structure of the photocatalyst, optimizing the electron transport process of the photocatalyst, broadening the light response range, effectively suppressing the problem of photogenerated electron-hole recombination, improving the photocatalytic efficiency of the photocatalyst, alleviating the photocorrosion problem of pure cuprous oxide, and significantly improving the removal rate of uranium ions in wastewater.

[0054] According to some preferred embodiments, in step (22), the mass ratio of sodium hydroxide to glucose is (1-4):1 (for example, it can be 1:1, 2:1, 3:1 or 4:1); in step (22), the stirring reaction temperature is 65-70°C (for example, it can be 65°C, 66°C, 67°C, 68°C, 69°C or 70°C), and the time is 60-70min (for example, it can be 60min, 65min or 70min).

[0055] In the embodiment of the present invention, by adjusting the content and ratio of sodium hydroxide and glucose during the reaction, it is beneficial to prepare a metal defect type Cu with stronger photocatalytic reduction ability of uranium ions. 2+1 The experiment of the present invention confirmed that by controlling the mass ratio of sodium hydroxide to glucose within the above range, the optimal copper and cuprous oxide can interact with each other in the reaction system, which is conducive to the formation of efficient Cu 2+1 O / Cu composite structure, which is conducive to achieving optimal electron transport and photocatalytic performance. In addition, the appropriate content of sodium hydroxide can not only ensure that metallic copper fully utilizes the active sites on the surface of defective cuprous oxide, which helps to improve the photocatalytic activity, but also makes it easier for defective cuprous oxide and metallic copper to form a stable composite structure, which helps to improve the stability of the photocatalyst. If the amount of sodium hydroxide added is lower or higher than the above range, it will cause Cu 2+1 The instability of the O / Cu composite structure may lead to excessive accumulation of active sites, thereby reducing the catalytic activity of the photocatalyst and causing Cu 2+1 The incomplete O / Cu composite structure affects electron transport and photocatalytic performance. In addition, inappropriate addition of sodium hydroxide will also lead to uneven dispersion between defective cuprous oxide and metallic copper, which also has an adverse effect on the overall performance of the photocatalyst.

[0056] According to some preferred embodiments, in step (22), after the stirring reaction, the reaction product is centrifuged, washed and vacuum dried in sequence.

[0057] It should be noted that there is no specific limitation on the conditions of centrifugation, washing and vacuum drying in the embodiments of the present invention, and they can be adjusted according to the requirements in the actual application process.

[0058] According to some preferred embodiments, in step (1), in the hydrophilic organic solvent aqueous solution, the hydrophilic organic solvent is propylene glycol, and the volume ratio of the hydrophilic organic solvent to water is (5-8):3 (for example, it can be 5:3, 6:3, 7:3 or 8:3); the amount of sodium alginate added is 2.0-3.0wt% of the total amount of the mixed solution (for example, it can be 2wt%, 2.2wt%, 2.5wt%, 2.8wt% or 3wt%).

[0059] In the embodiment of the present invention, by preferably selecting propylene glycol as the hydrophilic organic solvent and controlling the volume ratio of the hydrophilic organic solvent propylene glycol and water, after propylene glycol and sodium alginate are mixed, the two can undergo hydrogen bond self-assembly to form a double network structure, which is not only beneficial to ensure the mechanical stability of the photothermal foam gel, but also propylene glycol can act as a surfactant in the subsequent reaction process, thereby helping to improve the economy of the reaction; if the content of the hydrophilic organic solvent is too high or too low, it is not conducive to the preparation of a photothermal foam gel with good mechanical stability.

[0060] According to some preferred embodiments, in step (2), the photothermal conversion agent is carbon black, ferric oxide or carbon nanotubes, and the surfactant is alkyl sulfate or polyethylene ether; the amount of the photocatalyst added is 0.02-0.2g (for example, it can be 0.02g, 0.04g, 0.06g, 0.08g, 0.1g, 0.15g or 0.2g), the mass ratio of the photocatalyst to the photothermal conversion agent is (1-10):1 (for example, it can be 1:1, 3:1, 5:1, 8:1 or 10:1), and the amount of the surfactant added is 1-3wt% of the total amount of the reaction sol (for example, it can be 1wt%, 2wt% or 3wt%).

[0061] In an embodiment of the present invention, when preparing the photothermal foam gel, the photocatalyst and the photothermal conversion agent are first added to the mixed solution for ultrasonic treatment, and then the photocatalyst and the photothermal conversion agent are uniformly fixed to the photothermal foam gel by rapid mechanical stirring; under the irradiation of sunlight, the photothermal conversion agent can convert the energy of solar radiation into heat energy and store it in the foam gel, thereby accelerating the adsorption process of uranium ions by the foam gel, and the photocatalyst can photocatalytically degrade the uranium ions adsorbed by the foam gel in real time, which is conducive to further accelerating the adsorption process of uranium ions by the foam gel, and this cycle is repeated, thereby continuously realizing the adsorption and degradation treatment of uranium-containing wastewater.

[0062] The experiment of the present invention confirms that when the photothermal converter is preferably carbon black, it is more conducive to the uniform fixation of the photothermal converter in the foam gel, thereby accelerating the adsorption process of the foam gel on uranium ions; at the same time, the amount of photocatalyst added and the mass ratio of the photocatalyst and the photothermal converter are further controlled within the above range, which is conducive to ensuring that the photothermal foam gel has both excellent adsorption performance and photocatalytic degradation performance, so that the photothermal foam gel can treat uranium-containing wastewater more efficiently. In order to ensure a better photocatalytic effect, the amount of photocatalyst added in the embodiment of the present invention is preferably 0.08-0.2g. Too high or too low a content of the photocatalyst is not conducive to ensuring a better photocatalytic effect of the photothermal foam gel; at the same time, if the amount of photothermal converter added is too low, it is not conducive to ensuring a better adsorption performance of the photothermal foam gel. If the amount of photothermal converter added is too high, it will have an adverse effect on the photocatalytic degradation performance of the photocatalyst.

[0063] It should be noted that in the embodiments of the present invention, the surfactant can be selected from alkyl sulfates or polyvinyl ethers according to actual needs, for example, sodium dodecyl sulfate or polyvinyl methyl ether; at the same time, in order to ensure the dispersion effect of the photothermal conversion agent in the foam gel, the powder particle size of the photothermal conversion agent is at the nanometer level.

[0064] According to some preferred embodiments, in step (3), the concentration of the hydrochloric acid solution is 0.1-0.2 mol / L (for example, it can be 0.1 mol / L, 0.15 mol / L or 0.2 mol / L); the amount of calcium carbonate added is 0.5-0.8 wt% of the amount of sodium alginate added (for example, it can be 0.5 wt%, 0.6 wt%, 0.7 wt% or 0.8 wt%).

[0065] In the embodiment of the present invention, calcium carbonate is further added to the reaction sol under mechanical stirring, so that the calcium carbonate is fully dispersed in the reaction sol, and then a certain concentration of hydrochloric acid solution is added, so that the calcium carbonate is dissolved to release calcium ions, and the calcium carbonate reacts with the sodium alginate in the reaction sol to form a photothermal foam gel with a closed-cell structure. Compared with the photothermal foam gel with a traditional open-cell structure, the closed-cell foam gel in the embodiment of the present invention can alleviate the thermal convection phenomenon between heat and water, which is conducive to further improving the utilization efficiency of the thermal energy stored in the foam gel, and the foam gel prepared in the embodiment of the present invention has a self-floating property, which can fix the contact area between the photothermal foam gel and the uranium-containing wastewater, thereby controlling the solar energy absorption and water evaporation process on the surface of the photothermal foam gel exposed above the surface of the uranium-containing wastewater, so that the photothermal foam gel not only has efficient photothermal conversion and interface evaporation performance, but also greatly reduces the solar demand and unnecessary energy loss.

[0066] It should be noted that, in the embodiment of the present invention, the amount of hydrochloric acid added is not specifically limited, and the amount of hydrochloric acid added can be excessive relative to calcium carbonate; at the same time, in order to ensure that the photocatalyst and the photothermal conversion agent can be evenly dispersed in the photothermal foam gel and facilitate the formation of a foam gel with a closed-cell structure, in the embodiment of the present invention, mechanical stirring is used during the mixing reaction in steps (2) and (3), and the speed of the mechanical stirring is preferably 1100-1300 r / min, and the time is preferably 5-10 min.

[0067] The present invention also provides a photothermal foam gel, which is prepared by any of the above-mentioned preparation methods.

[0068] The photothermal foam gel prepared in the embodiment of the present invention has the advantages of being green and clean, high solar energy utilization efficiency, high efficiency of photocatalytic degradation of wastewater and low economic cost.

[0069] The present invention also provides an application of the photothermal foam gel, which is applied to photocatalytic degradation of uranium-containing wastewater and production of clean water.

[0070] The photothermal foam gel prepared in the embodiment of the present invention can realize the adsorption and degradation of wastewater, especially has excellent adsorption and degradation effect on uranium-containing wastewater. The concentration of uranium ions in uranium-containing wastewater is in the range of 10 to 5200 mg / L, and has excellent treatment effect on uranium-containing wastewater, especially when the pH of uranium-containing wastewater is 4, it can basically achieve complete degradation of uranium ions; and, in the process of degradation treatment of uranium-containing wastewater, clean water can be produced simultaneously, which can not only improve the utilization efficiency of solar energy, but also help to avoid waste of water resources.

[0071] In order to more clearly illustrate the technical solution and advantages of the present invention, a photothermal foam gel and a preparation method and application thereof are described in detail through several embodiments below.

[0072] Example 1

[0073] (1) At room temperature (25° C.), 1.25 g of sodium alginate was added to 50 mL of a hydrophilic organic solvent (propylene glycol) and deionized water to obtain a mixed solution; wherein the volume ratio of the hydrophilic organic solvent to the deionized water was 7:3;

[0074] (2) Add 0.1 g of photocatalyst (Cu 2+1 O / Cu photocatalyst), 0.02g photothermal conversion agent (carbon black), firstly subjected to ultrasonic treatment, then stirred at a speed of 1200r / min for 5min to mix, then added with surfactant (sodium dodecyl sulfate) and stirred to mix, and obtained reaction sol after reaction; wherein, the mass proportion of the added amount of surfactant in the reaction sol is 2wt%;

[0075] The photocatalyst is prepared by the following method:

[0076] (21) 2 g of CuSO 4 ·5H 2 O was added to 50 mL of deionized water and mixed to obtain CuSO 4 ·5H 2 O aqueous solution, to CuSO 4 ·5H 2 O aqueous solution was added with 2.5 g of sodium hydroxide and reacted in a water bath at 70° C. with stirring for 20 min to obtain a reaction solution;

[0077] (22) Keeping the temperature constant, 5 g of glucose was added to the reaction solution. After stirring for 1 h, the reaction product was filtered, washed, and dried at 60 °C to obtain Cu 2+1 O / Cu photocatalyst;

[0078] (3) Under mechanical stirring conditions, calcium carbonate was added to the reaction sol to make it fully dispersed, and then it was immersed in a 0.1 mol / L hydrochloric acid solution for gelation reaction for 12 h to obtain a photothermal foam gel, which was recorded as SGC@Cu 2+1 O / Cu1,0.1; wherein the amount of calcium carbonate added is 0.6wt% of the amount of sodium alginate added.

[0079] Example 2

[0080] (1) At room temperature (25° C.), 1.25 g of sodium alginate was added to 50 mL of a hydrophilic organic solvent (propylene glycol) and deionized water to obtain a mixed solution; wherein the volume ratio of the hydrophilic organic solvent to the deionized water was 7:3;

[0081] (2) Add 0.04 g of photocatalyst (Cu 2+1 O / Cu photocatalyst), 0.02g photothermal conversion agent (carbon black), firstly subjected to ultrasonic treatment, then stirred at a speed of 1200r / min for 5min to mix, then added with surfactant (sodium dodecyl sulfate) and stirred to mix, and obtained reaction sol after reaction; wherein, the mass proportion of the added amount of surfactant in the reaction sol is 2wt%;

[0082] The photocatalyst is prepared by the following method:

[0083] (21) 2 g of CuSO 4 ·5H 2 O was added to 50 mL of deionized water and mixed to obtain CuSO 4 ·5H 2 O aqueous solution, to CuSO 4 ·5H 2O aqueous solution was added with 2.5 g of sodium hydroxide and reacted in a water bath at 70° C. with stirring for 20 min to obtain a reaction solution;

[0084] (22) Keeping the temperature constant, 5 g of glucose was added to the reaction solution. After stirring for 1 h, the reaction product was filtered, washed, and dried at 60 °C to obtain Cu 2+1 O / Cu photocatalyst;

[0085] (3) Under mechanical stirring conditions, calcium carbonate was added to the reaction sol to make it fully dispersed, and then it was immersed in a 0.1 mol / L hydrochloric acid solution for gelation reaction for 12 h to obtain a photothermal foam gel; denoted as SGC@Cu 2+1 O / Cu1,0.04; wherein the amount of calcium carbonate added is 0.6wt% of the amount of sodium alginate added.

[0086] Example 3

[0087] (1) At room temperature (25° C.), 1.25 g of sodium alginate was added to 50 mL of a hydrophilic organic solvent (propylene glycol) and deionized water to obtain a mixed solution; wherein the volume ratio of the hydrophilic organic solvent to the deionized water was 7:3;

[0088] (2) Add 0.06 g of photocatalyst (Cu 2+1 O / Cu photocatalyst), 0.02g photothermal conversion agent (carbon black), firstly subjected to ultrasonic treatment, then stirred at a speed of 1200r / min for 5min to mix, then added with surfactant (sodium dodecyl sulfate) and stirred to mix, and obtained reaction sol after reaction; wherein, the mass proportion of the added amount of surfactant in the reaction sol is 2wt%; the photocatalyst is prepared by the following method:

[0089] (21) 2 g of CuSO 4 ·5H 2 O was added to 50 mL of deionized water and mixed to obtain CuSO 4 ·5H 2 O aqueous solution, to CuSO 4 ·5H 2 O aqueous solution was added with 2.5 g of sodium hydroxide and reacted in a water bath at 70° C. with stirring for 20 min to obtain a reaction solution;

[0090] (22) Keeping the temperature constant, 5 g of glucose was added to the reaction solution. After stirring for 1 h, the reaction product was filtered, washed, and dried at 60 °C to obtain Cu 2+1 O / Cu photocatalyst;

[0091] (3) Under mechanical stirring conditions, calcium carbonate was added to the reaction sol to make it fully dispersed, and then it was immersed in a 0.1 mol / L hydrochloric acid solution for gelation reaction for 12 h to obtain a photothermal foam gel; denoted as SGC@Cu 2+1 O / Cu1,0.06; wherein the amount of calcium carbonate added is 0.6wt% of the amount of sodium alginate added.

[0092] Example 4

[0093] (1) At room temperature (25° C.), 1.25 g of sodium alginate was added to 50 mL of a hydrophilic organic solvent (propylene glycol) and deionized water to obtain a mixed solution; wherein the volume ratio of the hydrophilic organic solvent to the deionized water was 7:3;

[0094] (2) Add 0.08 g of photocatalyst (Cu 2+1 O / Cu photocatalyst), 0.02g photothermal conversion agent (carbon black), firstly subjected to ultrasonic treatment, then stirred at a speed of 1200r / min for 5min to mix, then added with surfactant (sodium dodecyl sulfate) and stirred to mix, and obtained reaction sol after reaction; wherein, the mass proportion of the added amount of surfactant in the reaction sol is 2wt%; the photocatalyst is prepared by the following method:

[0095] (21) 2 g of CuSO 4 ·5H 2 O was added to 50 mL of deionized water and mixed to obtain CuSO 4 ·5H 2 O aqueous solution, to CuSO 4 ·5H 2 O aqueous solution was added with 2.5 g of sodium hydroxide and reacted in a water bath at 70° C. with stirring for 20 min to obtain a reaction solution;

[0096] (22) Keeping the temperature constant, 5 g of glucose was added to the reaction solution. After stirring for 1 h, the reaction product was filtered, washed, and dried at 60 °C to obtain Cu 2+1 O / Cu photocatalyst;

[0097] (3) Under mechanical stirring conditions, calcium carbonate was added to the reaction sol to make it fully dispersed, and then it was immersed in a 0.1 mol / L hydrochloric acid solution for gelation reaction for 12 h to obtain a photothermal foam gel; denoted as SGC@Cu 2+1 O / Cu1,0.08; wherein the amount of calcium carbonate added is 0.6wt% of the amount of sodium alginate added.

[0098] Example 5

[0099] Example 5 is basically the same as Example 1, except that in step (2), the amount of photocatalyst added is 0.02 g, and the prepared photothermal foam gel is denoted as SGC@Cu 2+1 O / Cu1,0.02.

[0100] Example 6

[0101] Example 6 is basically the same as Example 1, except that in step (2), the amount of photocatalyst added is 0.2 g, and the prepared photothermal foam gel is denoted as SGC@Cu 2+1 O / Cu1,0.2.

[0102] Example 7

[0103] Example 7 is basically the same as Example 1, except that in step (2), during the preparation of the photocatalyst, the amount of sodium hydroxide added is 2.5 g, and the prepared photocatalyst is recorded as Cu 2+1 O / Cu-0.5.

[0104] Example 8

[0105] Example 8 is basically the same as Example 1, except that in step (2), during the preparation of the photocatalyst, the amount of sodium hydroxide added is 5 g, and the prepared photocatalyst is recorded as Cu 2+1 O / Cu-1.

[0106] Example 9

[0107] Example 9 is basically the same as Example 1, except that in step (2), during the preparation of the photocatalyst, the amount of sodium hydroxide added is 10 g, and the prepared photocatalyst is recorded as Cu 2+1 O / Cu-2.

[0108] Example 10

[0109] Example 10 is basically the same as Example 1, except that in step (2), during the preparation of the photocatalyst, the amount of sodium hydroxide added is 15 g, and the prepared photocatalyst is recorded as Cu 2+1 O / Cu-3.

[0110] Embodiment 11

[0111] Example 11 is basically the same as Example 1, except that in step (2), during the preparation of the photocatalyst, the amount of glucose added is 2 g, and the prepared photocatalyst is recorded as Cu 2 O.

[0112] Example 12

[0113] Example 12 is basically the same as Example 1, except that in step (2), the amount of photothermal conversion agent added is 0.05 g.

[0114] Example 13

[0115] Example 13 is basically the same as Example 1, except that in step (2), the photothermal conversion agent is ferric oxide.

[0116] Comparative Example 1

[0117] Comparative Example 1 is basically the same as Example 1, except that in step (2), no photocatalyst is added, that is, 0.02 g of photothermal conversion agent (carbon black) is directly added to the mixed solution, firstly ultrasonic treatment is performed, then stirring at a speed of 1200 r / min for 5 min to mix, and then a surfactant (sodium dodecyl sulfate) is added and stirred to mix, and a reaction sol is obtained after reaction. The prepared foam gel is recorded as SA / GL / CB.

[0118] Comparative Example 2

[0119] Comparative Example 2 is basically the same as Example 1, except that in step (2), no photothermal conversion agent is added, that is, 0.02 g of photocatalyst (Cu 2+1 O / Cu photocatalyst), firstly subjected to ultrasonic treatment, then stirred at a speed of 1200r / min for 5min to mix, then added with a surfactant (sodium dodecyl sulfate) to stir and mix, and after reaction, a reaction sol was obtained.

[0120] Comparative Example 3

[0121] At room temperature (25°C), 1.25g of sodium alginate was added to 50mL of deionized water and mixed to obtain a sodium alginate aqueous solution; calcium carbonate was added to the reaction sol under mechanical stirring to make it fully dispersed, and then it was immersed in a 0.1mol / L hydrochloric acid solution for gelation reaction for 12h to obtain a gel; wherein the amount of calcium carbonate added was 0.6wt% of the amount of sodium alginate added, and the prepared gel was recorded as SA.

[0122] Comparative Example 4

[0123] (1) At room temperature (25° C.), 1.25 g of sodium alginate was added to 50 mL of a hydrophilic organic solvent (propylene glycol) and deionized water to obtain a mixed solution; wherein the volume ratio of the hydrophilic organic solvent to the deionized water was 7:3;

[0124] (2) adding a surfactant (sodium dodecyl sulfate) to the mixed solution, stirring and mixing, and obtaining a reaction sol after reaction; wherein the amount of the surfactant added in the reaction sol accounts for 2 wt % by weight;

[0125] (3) Under mechanical stirring conditions, calcium carbonate is added to the reaction sol to make it fully dispersed, and then it is immersed in a 0.1 mol / L hydrochloric acid solution for gelation reaction for 12 hours to obtain a foam gel; wherein the amount of calcium carbonate added is 0.6 wt% of the amount of sodium alginate added, and the prepared foam gel is recorded as SA / GL.

[0126] The present invention firstly performs XRD analysis on the photocatalysts prepared in Examples 7 to 11. Figure 1 It can be seen that the characteristic peaks at 29.58°, 36.44°, 42.32°, 52.48°, 61.4°, 73.5°, and 77.4° belong to Cu 2 O(PDF#78-2076) (110), (111), (200), (211), (220), (311), (222) crystal planes. From the above analysis, it can be seen that in the process of preparing the photocatalyst, by changing the mass ratio of sodium hydroxide and glucose, the Cu 2+1 The crystal structure of the O / Cu photocatalyst changed significantly. With the increase of the proportion of sodium hydroxide, the diffraction peak intensity of copper increased. When the mass ratio of sodium hydroxide to glucose was 3:1, cuprous oxide was completely converted into copper. This is because when the alkali was excessive, the solution was filled with a large amount of H + , so that the reaction occurs Cu 2+ →Cu 1+ →Cu 0 Secondly, the excess alkali causes metal excess point defects to be introduced into the Cu 2 O, changes its elemental chemical structure to form Cu 2+1 O structure. Among them, the positions at 43.2°, 50.4°, and 74.1° correspond to the (111), (200), and (220) crystal planes of Cu (PDF#04-0836), and the positions at 29.55°, 36.41°, 42.29°, 61.34°, and 73.52° correspond to the Cu 2+1 O (PDF#05-0667) (110), (111), (200), (220), (310) crystal planes. 2 O, Cu 2+1 O shifts in position on the same crystal plane, which provides strong evidence for the introduction of point defects. 2+1 O / Cu has high crystallinity and no impurity peaks, indicating that Cu 2+1 O / Cu is a pure phase. Based on this, it is proved that the metal-defective Cu2+1O / Cu photocatalyst was successfully prepared by a one-step wet chemical reduction method.

[0127] In order to verify the charge transfer efficiency and photogenerated electron-hole separation of the photocatalysts prepared in Examples 7 to 11, the photocatalysts prepared in the above examples were subjected to EIS, LSV and photocurrent response tests. The test results are as follows: Figures 2 to 4 As shown by Figure 2 It can be seen that Cu 2+1 O / Cu-1 has the lowest charge transfer resistance, which helps to promote the separation of photogenerated electrons and holes. Figure 3 As can be seen from the figure, as the applied bias voltage increases, the photocurrent density of the photocatalyst prepared in the embodiment shows an increasing trend, and the photocurrent density is arranged in descending order as follows: Cu 2+1 O / Cu-1>Cu 2+1 O / Cu-2>Cu 2+1 O / Cu-3>Cu 2+1 O / Cu-0.5>Cu 2 O, when the external bias voltage is 1.15V RHE When Cu 2+1 The photocurrent density of CuO / Cu-1 2 O is 2.7 times that of Cu 2+1 O / Cu-1 photocatalyst has the best carrier separation efficiency. The photocatalytic photoresponse characteristics of the photocatalyst were further studied. 2 O and Cu 2+1 The photocurrent response curves of O / Cu-x (x = 0.5, 1, 2, 3) photocatalysts are shown in Figure 2. Figure 4 It can be seen that Cu 2+1 O / Cu-1 exhibits the highest photocurrent intensity, indicating that the photogenerated electron-hole separation is more efficient, which suggests that by regulating the Cu 2 O element stoichiometric ratio, the introduction of metal excess point defects, and the regulation of Cu 2 O energy level structure, improve the heterojunction interface structure of the composite material, optimize the electron transport process of the composite material, and increase the Cu 2+1 The above analysis shows that the Cu prepared in the embodiment of the present invention has a good separation efficiency of photogenerated electrons and holes. 2+1 O / Cu-1 photocatalyst has the best photocatalytic performance.

[0128] The present invention firstly performs XRD test on the photothermal foam gel prepared in Example 1. The test results are as follows: Figure 5 As shown in the figure, it can be clearly seen that the characteristic peaks at 36.41° and 42.29° belong to Cu 2+1 O(PDF#05-0067) (111) and (200) crystal planes, indicating that the photocatalyst was successfully immobilized in the gel system. Figure 5It can be seen that the overall crystallinity of the photothermal foam gel is not high and it tends to be amorphous, which proves the good compatibility of sodium alginate hydrogel.

[0129] Secondly, the present invention also tests the mechanical properties of the photothermal foam gel prepared in Example 1 and Comparative Examples 3 to 4 to investigate the stability of the photothermal foam gel. Figure 5 and 6 As shown in the figure, it can be clearly seen that under the same mechanical strain degree, SGC@Cu 2+1 O / Cu1,0.1 has the highest mechanical stress (4.33MPa). Figure 7 It can be further seen that SA / GL in Comparative Example 7 has the highest compression modulus (1.75 MPa), which is attributed to the double network structure constructed by hydrogen bond self-assembly between sodium alginate and hydrophilic organic solvent, which improves the stability of the system. 2+1 The compression modulus of SGC@Cu was lower (1.08MPa) because the addition of photocatalyst particles increased the rigidity of the foam gel, thereby reducing the compression resistance. 2+1 The compression modulus of SGC@CuO / Cu1,0.1 is still higher than that of SA in Comparative Example 4 (0.35 MPa), which is 3 times that of the foam gel SA in Comparative Example 4. 2+1 O / Cu1,0.1 photothermal foam gel has excellent mechanical stability.

[0130] Application of photothermal foam gel:

[0131] The present invention is to prepare SGC@Cu in Example 1 2+1 The photocatalytic reduction U(VI) performance of the O / Cu1,0.1 photothermal foam gel and the foam gel prepared in Comparative Examples 3 to 4 was tested. The test results are shown in Tables 1 and Figures 8 to 9 As shown in Figure 2, under light conditions, the photocatalytic degradation process not only improves the 2+1 The removal effect of O / Cu1,0.1 photothermal foam gel on uranium also increased the kinetic reaction rate; Figure 8 It can be seen that SGC@Cu 2+1 O / Cu1,0.1 photothermal foam gel (130min), SGC@Cu 2+1 The time for the SGC@CuO / Cu1,0.1 photothermal foam gel to reach adsorption equilibrium under illumination was shortened to 40 min. 2+1The adsorption capacity of O / Cu1,0.1 photothermal foam gel for uranium reached 398.8 mg / g (the upper limit of uranium concentration is 400 mg / L), and the removal rate exceeded 99%. This shows that the photothermal foam gel prepared in the embodiment of the present invention has an excellent photocatalytic degradation effect on U(VI) in uranium-containing wastewater.

[0132] Furthermore, the present invention uses Langmuir and Freundlich isotherm models to fit the adsorption data of foam gel on uranium-containing wastewater, and studies the removal isotherms of uranium ions in uranium-containing wastewater at pH = 4 under light and dark control by the foam gel in Example 1 and Comparative Example 1, Comparative Examples 3 to 4. The uranium concentration at equilibrium is the concentration of the remaining uranyl ions in the solution after the adsorption is completed. Fig. 9 It can be seen that under light conditions, the SGC@Cu 2+1 The removal rate of SGC@Cu1,0.1 photothermal foam gel was close to 100% in the uranium concentration range of 20-200 mg / L, which indicated that 2+1 O / Cu1,0.1 photothermal foam gel has an excellent treatment effect on low-concentration uranium-containing wastewater. It can be seen that the R 2 is closer to 1. Therefore, the Langmuir isotherm model can more accurately describe the adsorption process, indicating that the adsorption process of uranium by photothermal foam gel is a single-layer adsorption. 2+1 O / Cu1,0.1 photothermal foam gel has the best photocatalytic reduction effect, and the adsorption capacity obtained by Langmuir fitting is 806.8 mg / g. The fitting calculation formula is as follows:

[0133] Langmuir isotherm model: C e / Q e =C e / q m +1 / (b·q m )

[0134] Freundlich isotherm model: lnq e =lnK f +1 / n·lnC e

[0135] In the formula, C e is the concentration of uranyl ions in the solution after adsorption equilibrium is reached (mg / L), Q e is the adsorption capacity of photothermal foam gel for uranyl ions at adsorption equilibrium (mg / g), b is the Langmuir adsorption equilibrium constant (L / mg), K f is the Freundlich constant [(mg / g)(L / mg)] 1 / nThe larger the value of b, the stronger the adsorption capacity. m is the saturated adsorption capacity of the photothermal foam gel (mg / g).

[0136] The present invention also prepares the SGC@Cu 2+1 The interfacial evaporation ability of O / Cu1,0.1 photothermal foam gel and the foam gels in Comparative Example 2 and Comparative Examples 3 to 4 under light was investigated. Fig.10 and 11 As shown. Fig.10 It can be clearly seen that the SGC@Cu 2+1 The temperature of the O / Cu1,0.1 photothermal foam gel can reach a maximum of 46.9°C after 14 hours, and the temperature is 14.6°C higher than that of the SA / GL / CB foam gel in Comparative Example 2. Fig.11 It can be seen that from 7 am to 18 pm, 11 hours have passed, and the SGC@Cu 2+1 O / Cu1,0.1 photothermal foam gel produced a total of 138.7 mL of water, with the highest purification rate being 0.82 L / m 2 / h.

[0137] Finally, the present invention measures the adsorption performance of the foamed gel prepared in the above embodiments and comparative examples for uranium-containing wastewater, and calculates using the following formula, and the calculation results are shown in Table 1; specifically, 0.01 g of the foamed gel in the embodiments and comparative examples is weighed, and 20 mL of uranium-containing wastewater (wherein the concentration of uranyl ions is 200 mg / L) is added, and after adsorption for 300 min under visible light conditions, the filtrate is collected, and the concentration of remaining uranyl ions in the filtrate is measured using an inductively coupled plasma mass spectrometer (ICP-MS), and the adsorption capacity and removal rate of uranium by the foamed gel are calculated using the following formula.

[0138] Furthermore, a water solution from an urban lake was taken as a simulated environment for uranium-containing wastewater, and the uranium concentration in the solution was set to 10 mg / L as uranium-containing wastewater. 2 g of the photothermal foam gel prepared in Example 1 was weighed and added to the uranium-containing wastewater (U(VI) solution) and irradiated with sunlight for 15 days in a real outdoor environment. The filtrate was then collected and the concentration of the remaining uranyl ions in the filtrate was determined using an inductively coupled plasma mass spectrometer (ICP-MS). The adsorption capacity and removal rate of uranium by the photothermal foam gel were calculated using the following formula. The calculation results are as follows: Figures 12 to 13 As shown;

[0139] Among them, the adsorption capacity of photothermal foam gel for uranium is obtained by the following formula:

[0140] Q e =(C 0 -Ce )×V / m

[0141] Among them, Q e is the adsorption capacity, C 0 is the initial concentration of U(VI), in mg / L, C e is the adsorption equilibrium concentration of U(VI), in mg / L, V is the volume of U(VI) solution, in L, and m is the mass of the photothermal foam gel, in g;

[0142] The removal rate of uranium by photothermal foam gel is obtained by the following formula:

[0143]

[0144] Among them, C 0 is the initial concentration of U(VI), C e is the adsorption equilibrium concentration of U(VI).

[0145] At the same time, the container containing wastewater and photothermal foam gel was sealed, and a collection container was placed at one place to collect the pure water produced by solar evaporation during the photocatalytic reduction of U(VI), measuring the potential of photothermal foam gel for high-value conversion and utilization of uranium-containing wastewater. 2+1 O / Cu1,0.1 photothermal foam gel can achieve a removal efficiency of over 98% for U(VI) in the solution and a clean water production (1.367L) with a total efficiency of 75.1%, which provides a potential solution for the high-value conversion and utilization of uranium-containing wastewater and the future solution to the shortage of fresh water resources.

[0146] Table 1

[0147]

[0148]

[0149] Combining Table 1 and Figures 8 to 9 It can be seen that the photothermal foam gel prepared in the embodiment of the present invention has an excellent treatment effect on uranium-containing wastewater, providing feasibility for treating U(VI) in actual uranium-containing wastewater.

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a photothermal foam gel, characterized in that: The preparation method comprises the following steps: (1) dissolving sodium alginate in a hydrophilic organic solvent aqueous solution to obtain a mixed solution; in the hydrophilic organic solvent aqueous solution, the hydrophilic organic solvent is glycerol, and the volume ratio of the hydrophilic organic solvent to water is (5-8):3; (2) adding a photocatalyst, a photothermal conversion agent and a surfactant to the mixed solution and mixing them to obtain a reaction sol; wherein the photocatalyst is Cu 2+1 O / Cu photocatalyst; the photothermal conversion agent is carbon black, ferric oxide or carbon nanotubes, and the surfactant is alkyl sulfate or polyethylene ether; The Cu 2+1 The preparation method of O / Cu photocatalyst comprises the following steps: (21) adding sodium hydroxide to the aqueous solution of copper sulfate pentahydrate and mixing to obtain a reaction solution; (22) Glucose is added to the reaction solution, and the Cu is obtained after stirring the reaction. 2+1 O / Cu photocatalyst; (3) adding calcium carbonate and hydrochloric acid solution to the reaction sol in sequence, stirring and reacting to obtain the photothermal foam gel; the photothermal foam gel has a closed-cell structure.

2. The preparation method according to claim 1, characterized in that: In step (21), the mass concentration of the copper sulfate pentahydrate aqueous solution is 0.04-0.08 g / mL; the mass ratio of copper sulfate pentahydrate to sodium hydroxide is 2:(2.5-15); and / or In step (21), the reaction temperature is 65-70°C and the reaction time is 5-15 min.

3. The preparation method according to claim 1, characterized in that: In step (22), the mass ratio of sodium hydroxide to glucose is (1-4):1; and / or In step (22), the stirring reaction temperature is 65-70°C and the time is 60-70 minutes.

4. The preparation method according to claim 1, characterized in that: In step (22), after the stirring reaction, the reaction product is centrifuged, washed and vacuum dried in sequence.

5. The preparation method according to claim 1, characterized in that: The amount of sodium alginate added is 2.0-3.0 wt % of the total amount of the mixed solution.

6. The preparation method according to claim 1, characterized in that: In step (2), the amount of the photocatalyst added is 0.02-0.2 g, the mass ratio of the photocatalyst to the photothermal conversion agent is (1-10):1, and the amount of the surfactant added is 1-3 wt % of the total amount of the reaction sol.

7. The preparation method according to claim 1, characterized in that: In step (3), the concentration of the hydrochloric acid solution is 0.1-0.2 mol / L; the amount of calcium carbonate added is 0.5-0.8 wt% of the amount of sodium alginate added.

8. A photothermal foam gel, characterized in that: Prepared according to the preparation method described in any one of claims 1 to 7.

9. Use of the photothermal foam gel prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The photothermal foam gel is applied to photocatalytically degrade uranium-containing wastewater and produce clean water.

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