A geopolymer-carbon-based photoevaporation material and a preparation method thereof, and a photoevaporation device

Abstract

The application provides a geopolymer-carbon-based photoevaporation material and a preparation method and a photoevaporation device thereof.The geopolymer-carbon-based photoevaporation material comprises a porous geopolymer support body and a carbon-based photo-thermal conversion layer on the porous geopolymer support body.The geopolymer-carbon-based photoevaporation material prepared by the application has great advantages compared with other types of photoevaporation films.The preparation process is very simple, and the cost problem caused by industrialization and expansion is significantly saved.The preparation conditions are very mild, and the material can be prepared at room temperature to 80 DEG C.The preparation raw material is very green and environmentally friendly, and does not cause secondary pollution to water sources.The prepared geopolymer-carbon-based photoevaporation material has the advantages of composite materials, and the advantages are complementary, and the evaporation efficiency and evaporation rate are extremely high, the industrial high-salinity wastewater can be efficiently concentrated and treated, and the treatment cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of membrane evaporation materials technology, and in particular to a geopolymer-carbon-based photoevaporation material, its preparation method, and a photoevaporation device. Background Technology

[0002] Industrial high-salinity wastewater refers to wastewater containing high concentrations of pollutants such as inorganic salts, organic matter, and heavy metals, primarily originating from industries such as metallurgy, chemicals, power generation, oil refining, and pharmaceuticals. This type of wastewater poses serious threats to the environment and human health, while also wasting significant amounts of water resources and recyclable materials. Therefore, the treatment and reuse of industrial high-salinity wastewater is a crucial issue for environmental protection and water conservation. Currently, the main methods for treating industrial high-salinity wastewater include physical, chemical, biological, and membrane separation methods. Among these, membrane separation is a technology that uses semi-permeable membranes to selectively separate solutes and solvents in a solution. It boasts advantages such as simple operation, low energy consumption, high efficiency, and small footprint, and has become one of the mainstream technologies for treating industrial high-salinity wastewater. Membrane separation methods can be further categorized into microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO) based on membrane pore size and separation mechanism. However, these separation methods require substantial driving force and incur high maintenance and preparation costs, handle only a limited range of solution types, and exhibit extremely low treatment efficiency, hindering their application in treating industrial high-salinity wastewater. In recent years, some novel membrane separation technologies or combined processes have emerged, such as membrane evaporation (MD), electrodialysis (ED), forward osmosis (FO), and multi-effect membrane distillation (MED). These technologies or combined processes have certain advantages and potential in improving permeate quality, reducing energy consumption, increasing recovery rates, and reducing concentrate volume. However, these technologies inevitably require the use of large amounts of energy, which is undoubtedly a fatal flaw in today's energy-scarce environment.

[0003] Solar-driven membrane evaporation (SDME) is a novel membrane separation technology that uses solar energy as a driving force to move the solvent in the solution from the low-temperature side through a porous membrane to the high-temperature side, where it is converted into steam, thereby achieving the purpose of separation and producing purified water.

[0004] The basic structure of SDME technology mainly consists of three parts: a photothermal conversion layer, a support structure, and a moisture transport structure. Each component plays a crucial role. The photothermal conversion layer, composed of photothermal conversion materials, is responsible for converting solar energy into thermal energy, thereby efficiently producing steam. The support structure supports the photothermal conversion layer and separates it from the water, preventing excessive energy dissipation. The moisture transport structure provides the power and channels for water to be transported from bottom to top.

[0005] Compared to traditional wastewater treatment technologies, SDME technology offers the following advantages in treating high-salinity industrial wastewater: SDME technology has lower requirements for influent water quality, eliminates the need for complex pretreatment to remove suspended solids, colloids, hardness, and acid / base neutralization, and due to its membrane characteristics, it can retain the vast majority of solutes. It also boasts relatively low energy consumption and has already found some application in industrial high-salinity wastewater treatment. Currently, membrane evaporation technology is mainly applied in the following areas:

[0006] Seawater desalination: Membrane evaporation technology can utilize renewable energy sources such as solar energy, geothermal energy, or waste heat as heat sources to achieve low-cost seawater desalination, while avoiding problems such as membrane fouling, scaling, and concentrate discharge in traditional technologies. Currently, some countries and regions have carried out pilot and demonstration projects for membrane evaporation seawater desalination, such as Australia, Spain, and Morocco.

[0007] Industrial wastewater concentration and reuse: Membrane evaporation technology can recover and reuse valuable solutes from industrial wastewater, such as metal ions, organic matter, and salts, while reducing wastewater discharge and treatment costs. Currently, several industrial sectors, such as metallurgy, chemical engineering, pharmaceuticals, and food processing, have adopted membrane evaporation technology for wastewater concentration and reuse.

[0008] Zero discharge of high-salinity wastewater: Membrane evaporation technology can concentrate high-salinity wastewater to a saturated or supersaturated state, and then achieve solid-liquid separation and zero discharge through crystallization or drying. Currently, some zero-discharge projects for high-salinity wastewater have adopted membrane evaporation technology as a pretreatment or final treatment method, such as landfill leachate, coal chemical wastewater, and power plant desulfurization wastewater.

[0009] Although membrane evaporation technology has certain advantages and potential in the treatment of high-salinity industrial wastewater, it also faces some problems and challenges, mainly in the following aspects:

[0010] Selection and preparation of membrane materials: While commonly used hydrophobic organic materials such as PTFE and PVDF possess good hydrophobicity and chemical resistance, they also have drawbacks, such as high cost, low strength, and poor temperature resistance. Therefore, it is necessary to develop novel hydrophobic materials or modification methods to improve membrane performance and reduce costs. Furthermore, the influence of membrane morphology and structure on mass transfer and thermal efficiency, as well as the impact of membrane preparation processes on cost and the environment, must be considered.

[0011] In summary, membrane evaporation technology is a novel thermally driven separation technology with broad application prospects in the treatment of high-salinity industrial wastewater. However, further basic research and engineering practice are needed to address existing problems and challenges and improve the system's performance and economic efficiency. Summary of the Invention

[0012] In view of this, the present invention provides a geopolymer-carbon-based photoevaporation material, its preparation method, and a photoevaporation device to overcome the defects existing in the prior art.

[0013] In a first aspect, the present invention provides a geopolymer-carbon-based photoevaporation material, comprising a porous geopolymer support and a carbon-based photothermal conversion layer located on the porous geopolymer support.

[0014] Preferably, the preparation method of the geopolymer-carbon-based photoevaporation material includes the following steps:

[0015] A mixture is obtained by mixing slag and metakaolin.

[0016] Add water glass and water to the mixture, stir, then add foaming agent and continue stirring to obtain porous geopolymer slurry;

[0017] Porous geopolymer slurry is placed in a mold and cured to obtain a porous geopolymer support.

[0018] Carbon-based materials are added to water to obtain a carbon-based slurry;

[0019] Carbon-based slurry is coated onto a porous geopolymer support and cured to obtain a geopolymer-carbon-based photoevaporation material.

[0020] Preferably, in the method for preparing the geopolymer-carbon-based photoevaporation material, the carbon-based material includes at least one of graphene oxide, graphite, and carbon nanotubes;

[0021] The modulus of the water glass is 1.2 to 1.4;

[0022] The foaming agent includes sodium dodecyl sulfate and / or hydrogen peroxide.

[0023] Preferably, in the preparation method of the geopolymer-carbon-based photoevaporation material, the mass ratio of slag to metakaolin is (0.2-1.8):(0.2-1.8);

[0024] The ratio of the sum of the masses of slag and metakaolin to the mass of water glass is (0.5–2.0):(1.0–2.0).

[0025] In the step of adding water glass and water to the mixture, the mass of the water is 5 to 40% of the sum of the masses of the slag and metakaolin.

[0026] The foaming agent is 0.1% to 11% of the sum of the masses of slag and metakaolin.

[0027] Preferably, in the preparation method of the geopolymer-carbon-based photoevaporation material, the steps of placing the porous geopolymer slurry in a mold and curing it to obtain a porous geopolymer support, and the steps of coating the carbon-based slurry onto the porous geopolymer support and curing it to obtain the geopolymer-carbon-based photoevaporation material, the curing temperature is 50-80°C and the time is 1-2 hours.

[0028] In the step of coating the carbon-based slurry onto the porous geopolymer support, the coating thickness is 5–100 μm.

[0029] Preferably, in the method for preparing the geopolymer-carbon-based photoevaporation material, if the carbon-based material is graphene oxide, graphene oxide is added to water to obtain a carbon-based slurry;

[0030] If the carbon-based material includes graphite or carbon nanotubes, then the graphite or carbon nanotubes are added to the porous geopolymer slurry to obtain the carbon-based slurry; wherein the mass ratio of the carbon-based material to the total mass of metakaolin and slag in the porous geopolymer slurry is 1:(0.5~1.5).

[0031] Thirdly, the present invention also provides a photoevaporation device, comprising the aforementioned geopolymer-carbon-based photoevaporation material or the geopolymer-carbon-based photoevaporation material prepared by the aforementioned preparation method.

[0032] Preferably, the photoevaporation apparatus further includes:

[0033] A base, wherein multiple geopolymer-carbon-based photoevaporation materials are fixed to the surface of the base;

[0034] The base has a water storage chamber inside, and the end of the geopolymer-carbon-based photoevaporation material extends into the water storage chamber.

[0035] Preferably, the photoevaporation apparatus further includes:

[0036] A transparent cover is located on the surface of the base and covers the outer periphery of the geopolymer-carbon-based photoevaporation material. The transparent cover has a water inlet pipe on one side and a water outlet pipe on the other side. The water inlet pipe is connected to the water storage chamber.

[0037] A plane mirror, located on the base and outside the transparent cover, is used to reflect sunlight onto the geopolymer-carbon-based photoevaporation material;

[0038] A Fresnel lens, located on the base and outside the transparent cover, is used to focus sunlight onto the geopolymer-carbon-based photoevaporation material.

[0039] Fourthly, the present invention also provides an application of the geopolymer-carbon-based photoevaporation material or the geopolymer-carbon-based photoevaporation material prepared by the preparation method or the photoevaporation device in the treatment of wastewater.

[0040] The present invention has the following advantages over the prior art:

[0041] 1. The geopolymer-carbon-based photoevaporation material of the present invention comprises a porous geopolymer support and a carbon-based photothermal conversion layer located on the porous geopolymer support. The geopolymer-carbon-based photoevaporation material prepared by the present invention has significant advantages over other types of photoevaporation films. Its preparation process is very simple, significantly reducing the costs associated with industrialization and scaling up. The preparation conditions are also very mild, occurring between room temperature and 80°C. The raw materials used are also very green and environmentally friendly, causing no secondary pollution to water sources. Furthermore, the prepared geopolymer-carbon-based photoevaporation material possesses the advantages of composite materials, complementing each other to exhibit extremely high evaporation efficiency and rate, enabling efficient concentration treatment of high-salt industrial wastewater and greatly reducing treatment costs. The geopolymer-carbon-based photoevaporation material itself also possesses advantages such as salt resistance, acid and alkali resistance, corrosion resistance, and high-temperature resistance, and has extremely high plasticity, allowing for flexible application in various harsh environments.

[0042] 2. The geopolymer-carbon-based photoevaporation material prepared by this invention is lightweight, has high mechanical strength, and a density less than water, allowing it to float stably on water. Coupled with a solar enhancement device, it enables the device to float at a suitable height on the water surface. Ultimately, the liquid to be treated below can continuously transfer water from bottom to top through its own water supply layer. Furthermore, the carbon-based photothermal conversion layer can block the continuously transported water, preventing it from accumulating on the upper surface and causing significant heat loss, thus reducing evaporation efficiency. This is because the carbon-based photothermal conversion layer and the porous geopolymer support have different hydrophilic and hydrophobic properties, exhibiting properties similar to a Janus membrane. The porous geopolymer support also has excellent thermal management performance. Its abundant capillaries not only allow for rapid water transfer via capillary action but also, due to its low thermal conductivity, prevent the carbon-based photothermal conversion layer from transferring a large amount of heat to the water below during photothermal conversion, allowing the carbon-based photothermal conversion layer to utilize more energy for evaporation and concentration.

[0043] 3. The photoevaporation device of the present invention includes a geopolymer-carbon-based photoevaporation material. The photoevaporation device of the present invention has excellent salt resistance and can achieve self-cleaning effect through the Marangoni effect. Compared with other evaporators, there is no need to spend additional labor costs to clean up salt accumulation. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the structure of the photoevaporation device in one embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the structure of the photoevaporation device in another embodiment of the present invention;

[0047] Figure 3 This is a schematic diagram of the structure of the photoevaporation device in another embodiment of the present invention;

[0048] Figure 4 This is a schematic diagram of the structure of the photoevaporation device in another embodiment of the present invention;

[0049] Figure 5 This is a schematic diagram illustrating the principle of sunlight reflection by a plane mirror and focusing of sunlight by a Fresnel lens in another embodiment of the photoevaporation device of the present invention.

[0050] Figure 6 This is a layout diagram of the geopolymer-carbon-based photoevaporation material of the present invention when it is used in the form of a ditch to store industrial high-salt wastewater.

[0051] Figure 7 This is a diagram showing the arrangement of the geopolymer-carbon-based photoevaporation material of the present invention when it is used in a pool to store high-salt industrial wastewater.

[0052] Figure 8 The thermal stability curve of the porous geopolymer support obtained in step S3 of Example 1;

[0053] Figure 9 The compressive strength curve of the porous geopolymer support obtained in step S3 of Example 1;

[0054] Figure 10 This is a photograph of the geopolymer-carbon-based photoevaporation material prepared in Example 1 floating on the water surface.

[0055] Figure 11 The evaporation rates of the geopolymer-carbon-based photoevaporation material prepared in Example 1 under different concentrations of salt water solution were measured.

[0056] Figure 12 The evaporation curves of the geopolymer-carbon-based photoevaporation material prepared in Example 1 are shown in acidic and alkaline solutions. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0058] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single digits within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0059] This application provides a geopolymer-carbon-based photoevaporation material, including a porous geopolymer support and a carbon-based photothermal conversion layer located on the porous geopolymer support.

[0060] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned geopolymer-carbon-based photoevaporation material, comprising the following steps:

[0061] S1. Mix slag and metakaolin to obtain a mixture;

[0062] S2. Add water glass and water to the mixture, stir, then add foaming agent and continue stirring to obtain porous geopolymer slurry;

[0063] S3. Place the porous geopolymer slurry in a mold and cure it to obtain a porous geopolymer support.

[0064] S4. Add the carbon-based material to water to obtain a carbon-based slurry;

[0065] S5. Coat the carbon-based slurry onto the porous geopolymer support and cure it to obtain the geopolymer-carbon-based photoevaporation material.

[0066] In some embodiments, the carbon-based material includes at least one of graphene oxide, graphite, and carbon nanotubes.

[0067] Specifically, carbon nanotubes can be functionalized carbon nanotubes, such as functionalized carbon nanotubes obtained by modifying carbon nanotubes with acids.

[0068] In some embodiments, the modulus of water glass is 1.2 to 1.4. Water glass, commonly known as sodium silicate, is a water-soluble silicate, and its aqueous solution is also known as water glass. It is a mineral binder. In this case, water glass is sodium silicate. The modulus of water glass refers to the ratio of SiO2 to Na2O in water glass.

[0069] In some embodiments, the foaming agent includes sodium dodecyl sulfate and / or hydrogen peroxide.

[0070] Specifically, the amount of foaming agent added is measured as a percentage of the total mass of slag and metakaolin. Specifically, the mass of the foaming agent is 0.1% to 11% of the sum of the masses of slag and metakaolin. If the foaming agent includes a mixture of sodium dodecyl sulfate and hydrogen peroxide, the mass of sodium dodecyl sulfate is (0.1% to 0.4%) of the sum of the masses of slag and metakaolin, preferably (0.2% to 0.3%), and most preferably 0.24%. The mass of hydrogen peroxide is (0.1% to 10%) of the sum of the masses of slag and metakaolin, preferably (1% to 5%), and most preferably 2%.

[0071] In some embodiments, the mass ratio of slag to metakaolin is (0.2–1.8):(0.2–1.8), more preferably (0.8–1.2):(0.8–1.2), and most preferably 0.9:1.1.

[0072] In some embodiments, the mass ratio of the sum of the masses of slag and metakaolin to the mass of water glass is (0.5-2.0):(1.0-2.0). Specifically, the mass ratio of the sum of the masses of slag and metakaolin to the mass of water glass is the solid-liquid ratio. Preferably, the mass ratio of the sum of the masses of slag and metakaolin to the mass of water glass is (1.0-1.2):(1.3-1.7), and most preferably 1:1.5.

[0073] In some embodiments, in the step of adding water glass and water to the mixture, the mass of water is 5 to 40% of the sum of the masses of slag and metakaolin.

[0074] In some embodiments, in the steps of placing a porous geopolymer slurry in a mold and curing it to obtain a porous geopolymer support, and in the steps of coating a carbon-based slurry onto the porous geopolymer support and curing it to obtain a geopolymer-carbon-based photoevaporation material, the curing temperature is 50-80°C and the time is 1-2 hours.

[0075] In the step of coating the carbon-based slurry onto the porous geopolymer support, the coating thickness is 5–100 μm.

[0076] In some embodiments, a carbon-based slurry is coated onto a porous geopolymer support and cured to form a carbon-based photothermal conversion layer on the porous geopolymer support, thereby preparing a geopolymer-carbon-based photoevaporation material.

[0077] In some embodiments, the apparent density of the prepared porous geopolymer support is 0.5–1.2 g / cm³. 3 The optimal range is between 0.5 and 0.9 g / cm³. 3 When these conditions are met, porous geopolymer supports exhibit good water transport performance and hydrophilicity. Under these preferred conditions, porous geopolymer supports with good thermal positioning ability, suitable water transport performance and strength, and suitable pore size distribution can be prepared.

[0078] In some embodiments, the carbon-based material includes at least one of graphene oxide, graphite, and carbon nanotubes; there are two methods for preparing the carbon-based photothermal conversion layer using the carbon-based material; if the carbon-based material is graphene oxide, graphene oxide is added to water to obtain a carbon-based slurry, and then the carbon-based slurry is coated onto a porous geopolymer support and cured to form a carbon-based photothermal conversion layer; if the carbon-based material includes graphite or carbon nanotubes, graphite or carbon nanotubes are added to a porous geopolymer slurry to obtain a carbon-based slurry, and then the carbon-based slurry is coated onto a porous geopolymer support and cured to form a carbon-based photothermal conversion layer.

[0079] Specifically, carbon-based materials such as graphene oxide and functionalized carbon nanotubes are carbon-based photothermal materials that are reactive with geopolymers. Taking graphene oxide as an example, graphene oxide is added to water to obtain a carbon-based slurry. The amount of graphene oxide used is measured by the surface area of ​​the porous geopolymer support, ranging from 0.1 to 0.4 g / m². 2 For optimal application, the thickness of the coated graphene oxide should be between 50 and 60 μm. The coated sample should then be cured in a constant temperature chamber at a temperature between 50 and 80°C for 1 to 2 hours. During curing, the geopolymer reacts with the graphene oxide, removing some oxygen-containing functional groups. This improves the geopolymer's photothermal conversion performance and also creates a stronger bond with the porous geopolymer support, enhancing the device's durability.

[0080] Pure carbon-based materials such as graphite and carbon nanotubes cannot react and bond with the prepared porous geopolymer. However, they can be directly composited with the porous geopolymer slurry and bonded to the surface of the porous geopolymer support, achieving a strong bond. The ratio of the mass of the carbon-based material to the total mass of metakaolin and slag in the porous geopolymer slurry is 1:(0.5-1.5), with a preferred ratio of 1:1. The coating thickness is preferably between 500 and 1000 μm, with 600-700 μm being optimal.

[0081] Specifically, in the above embodiments, the carbon-based material includes graphite or carbon nanotubes. Graphite or carbon nanotubes are added to the porous geopolymer slurry to obtain a carbon-based slurry. The carbon-based slurry is then coated onto the porous geopolymer support and cured to form a carbon-based photothermal conversion layer. The preparation method of the porous geopolymer slurry is exactly the same as in steps S1 to S2, and the mass ratio of slag to metakaolin, the mass ratio of the sum of the masses of slag and metakaolin to water glass, and the amount of foaming agent added are all exactly the same as described above.

[0082] In some embodiments, slag and metakaolin are mixed to obtain a mixture; then, water glass and water are mixed evenly, and then the mixed water glass and water are poured into the mixture of slag and metakaolin. The mixture is stirred using a mixer. The preferred stirring time is between 2 and 10 minutes, and the stirring speed is between 500 and 2000 r / min to ensure that the slurry is fully and evenly mixed. Preferably, a stirring time of 2 minutes and a stirring speed of 2000 r / min are optimal. After stirring, a foaming agent is added to the slurry, and the mixture is stirred at the same speed for 1 minute to successfully prepare a porous geopolymer slurry. Finally, the slurry is poured into the corresponding mold and placed in an oven for curing to prepare a porous geopolymer support.

[0083] In some embodiments, slag, metakaolin, and pure carbon photothermal materials (such as graphite or carbon nanotubes) are mixed evenly in a predetermined ratio. Next, water glass and water are mixed evenly. Then, the mixed water glass and water are poured into the mixture of slag, metakaolin, and pure carbon photothermal materials, and stirred using a mixer. The stirring time is preferably between 2 and 10 minutes, and the stirring speed is between 500 and 2000 r / min to ensure thorough mixing of the slurry. In this embodiment, a stirring time of 2 minutes and a stirring speed of 2000 r / min are optimal. After stirring, a foaming agent is added to the slurry, and it is stirred at the same speed for 1 minute to successfully prepare a porous geopolymer / carbon composite slurry (i.e., the carbon-based slurry mentioned above). The obtained porous geopolymer / carbon composite slurry is coated onto the surface of a porous geopolymer support to complete the preparation of the carbon-based photothermal conversion layer.

[0084] The graphene oxide used in this invention is prepared from graphite using a modified Hummers method, and the functionalized carbon nanotubes are obtained by functionalizing carbon nanotubes. Both graphite and carbon nanotubes are commercially available products well-known to those skilled in the art and are inexpensive. These materials can be prepared into a solution and then directly loaded onto a porous geopolymer support by vacuum filtration or coating to complete the preparation of the carbon-based photothermal conversion layer.

[0085] The geopolymer-carbon-based photoevaporation material prepared by this invention has significant advantages over other types of photoevaporation films. Its preparation process is very simple, significantly reducing the costs associated with industrialization and scaling up. The preparation conditions are also very mild, occurring between room temperature and 80°C. Furthermore, the raw materials are very environmentally friendly, causing no secondary pollution to water sources. The prepared geopolymer-carbon-based photoevaporation material combines the advantages of composite materials, exhibiting extremely high evaporation efficiency and rate, enabling efficient concentration treatment of high-salt industrial wastewater and greatly reducing treatment costs. The geopolymer-carbon-based photoevaporation material itself also possesses advantages such as salt resistance, acid and alkali corrosion resistance, and high-temperature resistance, and is highly ductile, allowing for flexible application in various harsh environments.

[0086] Based on the same inventive concept, the present invention also provides a photoevaporation device, comprising the above-mentioned geopolymer-carbon-based photoevaporation material or the geopolymer-carbon-based photoevaporation material prepared by the above-mentioned preparation method.

[0087] In some embodiments, the photoevaporation device, such as Figures 1-5 As shown, it also includes:

[0088] Base 1, multiple geopolymer-carbon-based photoevaporation materials 2 are fixed on the upper surface of base 1;

[0089] The base 1 has a water storage chamber 11 inside, and the end of the geopolymer-carbon-based photoevaporation material extends into the water storage chamber 11.

[0090] In the above embodiment, multiple geopolymer-carbon-based photoevaporation materials 2 are fixed on the upper surface of the base 1, and a water storage chamber 11 is provided inside the base 1. The lower end of the geopolymer-carbon-based photoevaporation material 2 extends into the water storage chamber 11. By introducing wastewater to be treated, such as high-concentration brine, into the water storage chamber 11, the geopolymer-carbon-based photoevaporation material absorbs solar energy and converts it into heat energy, thereby causing the wastewater to be treated to evaporate.

[0091] In some embodiments, the base 1 has protrusions 12 on both sides, and multiple geopolymer-carbon-based photoevaporation materials 2 are located on the base 1 and between the two protrusions 12, forming a waste heat channel 13. The purpose of designing the waste heat channel 13 is to utilize some high-temperature waste heat generated in the factory to compensate for the loss of evaporation efficiency due to the inability to utilize wind power to improve evaporation efficiency after the addition of the acrylic transparent cover 3. The waste heat-enhanced photoevaporation concentration process can be completed simply by guiding the high-temperature waste gas generated in the factory to the waste heat channel at the bottom of the device through a simple pipe.

[0092] In some embodiments, the bottom sides of the transparent cover 3 are respectively fixed on the protrusions 12, and multiple geopolymer-carbon-based photoevaporation materials 2 pass through the bottom of the transparent cover 3 and extend into the water storage chamber 11. The transparent cover 3 has an inlet pipe 31 on one side and an outlet pipe 32 on the other side. The inlet pipe 31 is connected to the water storage chamber 11. In use, the wastewater to be treated is introduced into the water storage chamber 11 through the inlet pipe 31. The clean water obtained after the wastewater evaporates is collected in the transparent cover 3. Specifically, the transparent cover 3 can be an acrylic transparent cover, and the upper end of the transparent cover 3 can be either open or closed.

[0093] For details, please refer to the following again. Figure 2 As shown, the transparent cover 3 is also provided with fasteners 14, which are used to fix the geopolymer-carbon-based photoevaporation material 2.

[0094] Please refer to this again. Figure 4 As shown, in some embodiments, the transparent cover 3 may not be provided. In this case, the waste heat of the high-temperature exhaust gas can be utilized by the waste heat channel 13, and the wind energy 16 and ambient heat energy 15 can also be utilized. In some embodiments, plane mirrors 4 are respectively provided on the base 1 and on both sides of the transparent cover 3. Specifically, the plane mirrors 4 are provided on the protrusion 12, and the angle between the plane mirrors 4 and the surface of the protrusion 12 is 45-60°. The plane mirrors 4 can enhance the intensity of sunlight at noon and from 11:00 to 13:00, and the plane mirrors 4 reflect sunlight onto the geopolymer-carbon-based photoevaporation material 2.

[0095] In some embodiments, Fresnel lenses 5 are respectively provided on the base 1 and on both sides of the transparent cover 3. Specifically, a bracket is provided on the protrusion 12, and the Fresnel lenses 5 are mounted on the bracket and hinged to the bracket, so that the Fresnel lenses 5 can rotate and their angles can be adjusted. Specifically, the angle between the Fresnel lens 5 on one side of the transparent cover 3 and the plane of the protrusion 12 is adjustable between 34° and 60°, and the angle between the Fresnel lens 5 on the other side of the transparent cover 3 and the plane of the protrusion 12 is adjustable between 120° and 146°. The Fresnel lenses 5 are provided to enhance the intensity of sunlight in the morning and evening. The Fresnel lenses 5 are used to focus sunlight onto the geopolymer-carbon-based photoevaporation material.

[0096] The aforementioned plane mirror 4 and Fresnel lens 5 (collectively referred to as the solar enhancement device) are designed to maximize the intensity of sunlight during the day in order to improve the evaporation efficiency and concentration speed of the photoevaporation device.

[0097] In some embodiments, the diameter of the Fresnel lens 5 is preferably 3 to 8 times, and 4 to 5 times, the diameter of the geopolymer-carbon-based photoevaporation material.

[0098] The photo-evaporation device of the present invention has excellent salt resistance and can achieve self-cleaning effect through the Marangoni effect. Compared with other evaporators, it does not require additional labor costs for cleaning salt accumulation.

[0099] Please refer to this again. Figure 5 As shown, it illustrates the reflection of sunlight by the plane mirror 4 and the focusing of sunlight by the Fresnel lens 5.

[0100] In some embodiments, reference Figure 6 As shown, when industrial high-salt wastewater is stored in a ditch, the arrangement of multiple geopolymer-carbon-based photoevaporation materials 2 is shown, where 21 is the ditch inlet and 22 is the ditch outlet.

[0101] In some embodiments, reference Figure 7 As shown, when industrial high-salt wastewater is stored in a pool, the arrangement of multiple geopolymer-carbon-based photoevaporation materials 2 is shown, where 33 is the pool inlet and 34 is the pool outlet.

[0102] The geopolymer-carbon-based photoevaporation material prepared by this invention is lightweight, less dense than water, and has high mechanical strength. It can float stably on water and, when coupled with a solar enhancement device, allows the device to float at a suitable height. The liquid to be treated below can continuously transfer water upwards through its own water supply layer. Furthermore, the carbon-based photothermal conversion layer can block the continuously transported water, preventing it from accumulating on the upper surface and causing significant heat loss, thus reducing evaporation efficiency. This is because the carbon-based photothermal conversion layer and the porous geopolymer support have different hydrophilic and hydrophobic properties, exhibiting properties similar to a Janus membrane. The porous geopolymer support also has excellent thermal management performance. Its abundant capillaries not only allow for rapid water transfer via capillary action but also, due to its low thermal conductivity, prevent the carbon-based photothermal conversion layer from transferring a large amount of heat to the water below during photothermal conversion, allowing the carbon-based photothermal conversion layer to utilize more energy for evaporation and concentration.

[0103] Based on the same inventive concept, the present invention also provides an application of the above-mentioned geopolymer-carbon-based photoevaporation material or the geopolymer-carbon-based photoevaporation material prepared by the above-mentioned preparation method or the above-mentioned photoevaporation device in the treatment of wastewater.

[0104] Specifically, the aforementioned wastewater includes wastewater containing high concentrations of pollutants such as inorganic salts, organic matter, and heavy metals. The wastewater is evaporated and concentrated using the geopolymer-carbon-based photoevaporation material of the present invention, and the evaporated steam is collected to obtain clean water.

[0105] The following further illustrates the geopolymer-carbon-based photoevaporation material, its preparation method, and the photoevaporation apparatus of this application with specific embodiments. This section further illustrates the content of the present invention with reference to specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0106] Example 1

[0107] This embodiment provides a method for preparing geopolymer-carbon-based photoevaporation materials, including the following steps:

[0108] S1. Mix 100g of slag and 100g of metakaolin to obtain a mixture;

[0109] S2. Mix 200g of water glass with a modulus of 1.3 and 50g of water. Then add the mixed water glass and water to the mixture in S1. Stir at 2000r / min for 2min. Then add the foaming agent and continue stirring at 2000r / min for 1min to obtain a porous geopolymer slurry. The foaming agent includes a mixture of sodium dodecyl sulfate (0.48g) and hydrogen peroxide (4g).

[0110] S3. Place the porous geopolymer slurry in a mold and cure it at 60°C for 1 hour to obtain a porous geopolymer support; wherein the mold is a hollow cylinder with an inner diameter of 2 cm.

[0111] S4. Add 15mg of graphene oxide to 50mL of deionized water and stir until homogeneous to obtain a carbon-based slurry.

[0112] S5. The carbon-based slurry in S4 is coated onto the upper surface of the porous geopolymer support in S3 (coating thickness is 50 μm), and cured at 60℃ for 2 h to obtain the geopolymer-carbon-based photoevaporation material.

[0113] Example 2

[0114] This embodiment provides a method for preparing geopolymer-carbon-based photoevaporation materials, including the following steps:

[0115] S1. Mix 100g of slag and 100g of metakaolin to obtain the first mixture;

[0116] S2. Mix 200g of water glass with a modulus of 1.3 and 50g of water. Then add the mixed water glass and water to the first mixture in S1. Stir at 2000r / min for 2min. Then add the foaming agent and continue stirring at 2000r / min for 1min to obtain a porous geopolymer slurry. The foaming agent includes a mixture of sodium dodecyl sulfate (0.48g) and hydrogen peroxide (4g).

[0117] S3. Place the porous geopolymer slurry in a mold and cure it at 60°C for 1 hour to obtain a porous geopolymer support; wherein the mold is a hollow cylinder with an inner diameter of 2 cm.

[0118] S4. Mix 5g of slag, 5g of metakaolin, and 10g of graphite to obtain a second mixture; mix 10g of water glass with a modulus of 1.3 and 2.5g of water, then add the mixed water glass and water to the second mixture, stir at 2000r / min for 2min, then add foaming agent, and continue stirring at 2000r / min for 1min to obtain geopolymer carbon-based slurry;

[0119] S5. Coat the geopolymer carbon-based slurry in S4 onto the upper surface of the porous geopolymer support in S3 (coating thickness is 870μm) and cure at 60℃ for 2h to obtain the geopolymer-carbon-based photoevaporation material.

[0120] Example 3

[0121] This embodiment provides a photoevaporation device, the structure of which is as follows: Figures 1-3 As shown, the photoevaporation device includes multiple geopolymer-carbon-based photoevaporation materials prepared in Example 1. Specifically, a plane mirror is mounted on the base and located on both sides of the transparent cover; the plane mirror is positioned on a protrusion with an angle of 45° between the plane mirror and the surface of the protrusion. A Fresnel lens is also mounted on the base and located on both sides of the transparent cover. Specifically, a support is mounted on the protrusion, and the Fresnel lens is mounted on the support and hinged to the support, allowing the Fresnel lens to rotate and its angle to be adjusted. Specifically, the angle between the Fresnel lens and the plane of the protrusion is 60°. The diameter of the Fresnel lens is 40cm, and the dimensions of the plane mirror are 40cm × 40cm (i.e., both length and width are 40cm).

[0122] Example 4

[0123] This embodiment provides a photoevaporation device, the structure of which is as follows: Figures 1-3As shown, the photoevaporation device includes multiple geopolymer-carbon-based photoevaporation materials prepared in Example 2. Specifically, a plane mirror is mounted on the base and located on both sides of the transparent cover; the plane mirror is positioned on a protrusion with an angle of 45° between the plane mirror and the surface of the protrusion. A Fresnel lens is also mounted on the base and located on both sides of the transparent cover. Specifically, a support is mounted on the protrusion, and the Fresnel lens is mounted on the support and hinged to the support, allowing the Fresnel lens to rotate and its angle to be adjusted. Specifically, the angle between the Fresnel lens and the plane of the protrusion is 60°. The diameter of the Fresnel lens is 40cm, and the dimensions of the plane mirror are 40cm × 40cm (i.e., both length and width are 40cm).

[0124] Performance testing

[0125] Figure 8 The thermal stability curve of the porous geopolymer support obtained in step S3 of Example 1 is shown below. Figure 8 As can be seen, the porous geopolymer support loses some weight before 250℃ (mainly water loss in the early stage), but its weight remains almost unchanged between 250℃ and 1000℃, indicating that the porous geopolymer support has good thermal stability. Therefore, it can be concluded that the geopolymer-carbon-based photoevaporation material of the present invention also has good thermal stability.

[0126] Figure 9 The compressive strength curve of the porous geopolymer support obtained in step S3 of Example 1 is shown below. Figure 9 As can be seen from the data, the porous geopolymer support can withstand a pressure of up to 25 MPa, indicating that the porous geopolymer support of the present invention has good mechanical strength. Therefore, it can be shown that the geopolymer-carbon-based photoevaporation material of the present invention also has mechanical strength.

[0127] Figure 10 This is a photograph of the geopolymer-carbon-based photoevaporation material prepared in Example 1 floating on the water surface. Figure 10 It is known that the geopolymer-carbon-based photoevaporation material prepared by this invention is lightweight and has a density lower than that of water.

[0128] Figure 11 The evaporation rates of the geopolymer-carbon-based photoevaporation material prepared in Example 1 under different concentrations of salt water solution were measured. Figure 11 Pure water refers to pure water. 3.5wt.%, 7wt.%, and 15wt.% represent salt solutions with mass concentrations of 3.5%, 7%, and 15%, respectively. The specific preparation method for 3.5wt.%, 7wt.%, and 15wt.% salt solutions is to add different masses of NaCl to the water, so that the NaCl mass fractions are 3.5%, 7%, and 15%, respectively, which are salt solutions with different mass concentrations.

[0129] from Figure 11 As can be seen, the geopolymer-carbon-based photoevaporation material of the present invention has a high evaporation rate even for high-quality brine, indicating that the geopolymer-carbon-based photoevaporation material of the present invention has strong salt resistance.

[0130] Figure 12 The figures show the evaporation curves of the geopolymer-carbon-based photoevaporation material prepared in Example 1 under acidic and alkaline solutions; wherein, Figure 12 In the equation HCl-pH=1, it means that HCl was used to adjust the water to an acidic aqueous solution with a pH of 1, and in the equation NaOH-pH=13, it means that NaOH was used to adjust the water to an alkaline aqueous solution with a pH of 13.

[0131] from Figure 12 As can be seen from the above, the geopolymer-carbon-based photoevaporation material of the present invention also has good evaporation effect in acidic and alkaline solutions, indicating that the geopolymer-carbon-based photoevaporation material of the present invention has good acid and alkali corrosion resistance.

[0132] Evaporation effect test

[0133] Using simulated sunlight (light intensity adjusted to 1kW / m²) 2 The geopolymer-carbon-based photoevaporation materials prepared in Examples 1 and 2 were directly irradiated with a sample simulating the intensity of real sunlight, and placed in a prepared NaCl 3.5 wt.% solution. The evaporation rate was recorded in real time using a balance connected to a computer.

[0134] On a sunny day, the photoevaporation apparatus from Examples 3 and 4 was placed outdoors for a real solar irradiation experiment. A prepared 3.5 wt.% NaCl solution was poured into the water storage chamber 11. The vapor from Example 4 was collected.

[0135] Evaporation rate m is the steam output per unit area per unit time, expressed in kg / m². 2 / h), the evaporation efficiency η is:

[0136] Where m is the evaporation rate, h LV It is a phase transition enthalpy with a value of 2256 kJ / kg, q i A solar intensity (1kW / m 2 ), C opt It is a multiple of the sun's intensity (this example only has one intensity).

[0137] The test results are as follows:

[0138] The evaporation rate of the geopolymer-carbon-based photoevaporation material in Example 1 was 1.79 kg / m³. 2 / h, evaporation efficiency is 92.1%.

[0139] The evaporation rate of the geopolymer-carbon-based photoevaporation material in Example 2 was 1.81 kg / m³. 2 / h, evaporation efficiency is 90.3%.

[0140] The evaporation rate of the photoevaporation device in Example 3 is 4.05 kg / m³. 2 / h, which is 2.26 times that of Example 1, with an evaporation efficiency exceeding 100% (due to the additional energy input).

[0141] After 8 hours of continuous outdoor evaporation, ICP analysis of the steam-desalinated water collected in Example 4 showed a removal rate of 99.9% for potassium, sodium, calcium, and magnesium ions. This demonstrates that the photoevaporation device of the present invention has the potential to photo-evaporate and concentrate industrial wastewater.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a geopolymer-carbon-based photoevaporation material, characterized in that, Includes the following steps: A mixture is obtained by mixing slag and metakaolin. Add water glass and water to the mixture, stir, then add foaming agent and continue stirring to obtain porous geopolymer slurry; Porous geopolymer slurry is placed in a mold and cured to obtain a porous geopolymer support. Carbon-based materials are added to water to obtain a carbon-based slurry; A carbon-based slurry was coated onto a porous geopolymer support and cured to obtain a geopolymer-carbon-based photoevaporation material. The carbon-based material includes one of graphene oxide and graphite; The modulus of the water glass is 1.2 to 1.4; The foaming agent includes sodium dodecyl sulfate and hydrogen peroxide; The mass ratio of the slag to metakaolin is (0.8–1.2):(0.8–1.2); The mass of sodium dodecyl sulfate is 0.24% of the sum of the masses of slag and metakaolin; the mass of hydrogen peroxide is 2% of the sum of the masses of slag and metakaolin. The ratio of the sum of the masses of slag and metakaolin to the mass of water glass is (0.5–2.0):(1.0–2.0). In the step of adding water glass and water to the mixture, the mass of the water is 5 to 40% of the sum of the masses of the slag and metakaolin. In the steps of placing porous geopolymer slurry in a mold and curing it to obtain a porous geopolymer support, and in the steps of coating carbon-based slurry onto the porous geopolymer support and curing it to obtain a geopolymer-carbon-based photoevaporation material, the curing temperature is 50-80℃ and the time is 1-2h. In the step of coating the carbon-based slurry onto the porous geopolymer support, the coating thickness is 5–100 μm; If the carbon-based material is graphene oxide, then graphene oxide is added to water to obtain a carbon-based slurry; If the carbon-based material is graphite, then graphite is added to the porous geopolymer slurry to obtain the carbon-based slurry; wherein, the ratio of the mass of the carbon-based material to the total mass of metakaolin and slag in the porous geopolymer slurry is 1:(0.5~1.5).

2. A photoevaporation apparatus, characterized in that, Including the geopolymer-carbon-based photoevaporation material prepared by the preparation method described in claim 1.

3. The photoevaporation apparatus as described in claim 2, characterized in that, Also includes: A base, wherein multiple geopolymer-carbon-based photoevaporation materials are fixed to the surface of the base; The base has a water storage chamber inside, and the end of the geopolymer-carbon-based photoevaporation material extends into the water storage chamber.

4. The photoevaporation apparatus as described in claim 3, characterized in that, Also includes: A transparent cover is located on the surface of the base and covers the outer periphery of the geopolymer-carbon-based photoevaporation material. The transparent cover has a water inlet pipe on one side and a water outlet pipe on the other side. The water inlet pipe is connected to the water storage chamber. A plane mirror, located on the base and outside the transparent cover, is used to reflect sunlight onto the geopolymer-carbon-based photoevaporation material; A Fresnel lens, located on the base and outside the transparent cover, is used to focus sunlight onto the geopolymer-carbon-based photoevaporation material.

5. The application of a geopolymer-carbon-based photoevaporation material prepared by the preparation method according to claim 1 or the photoevaporation device according to any one of claims 2 to 4 in the treatment of wastewater.

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