A graphene-based porous medium material and its preparation method and application

Abstract

The present invention belongs to the field of water treatment, and relates to a graphene-based porous medium material, a preparation method thereof, and an application thereof. The preparation method of the graphene-based porous medium material comprises loading graphene oxide in a porous medium material to obtain a porous medium material loaded with graphene oxide, and then sequentially performing a heating reduction treatment, an ascorbic acid reduction treatment, and a microwave reduction treatment on the porous medium material loaded with graphene oxide. The graphene-based porous medium material obtained by the method provided by the present invention has very good oleophilic and hydrophobic properties, and can effectively separate oil and water in oily wastewater.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and specifically relates to a graphene-based porous medium material and a preparation method and application thereof. Background Art

[0002] The main source of oil pollution in water bodies is human activities. Since the beginning of the last century, oil has become one of the most important energy sources for mankind, and the production and consumption of oil have increased rapidly. The transportation of petroleum products leads to oil spills from ships, especially the risk of oil spills from large ships. Oil pollutants floating on the surface of the water body will affect the oxygen exchange between the air and water interface; oil dispersed in the water can be oxidized and decomposed by microorganisms, and in this process, it will consume dissolved oxygen in the water and deteriorate the water quality. Among them, petroleum compounds contain aromatic hydrocarbons, which are less than alkanes, but their toxicity is much greater and can be enriched by aquatic organisms to endanger human health.

[0003] At present, the treatment measures for oily wastewater are mainly divided into three categories: biological method, chemical method and physical method. Among them, the biological method not only has a slow treatment speed, but is also not suitable for treating oily wastewater with high concentrations, and is mainly used as an auxiliary means; the various chemical agents added by the chemical method are prone to secondary pollution; the mainstream treatment methods of the physical method are sedimentation separation method, flotation method and physical adsorption method. The treatment methods of sedimentation separation method and flotation method have low treatment efficiency and need to be used in combination with various chemical reagents to achieve efficient oil-water separation. However, the separated oil phase cannot be recycled and reused after the introduction of chemical reagents, and may even pollute some water phases with special requirements. Physical adsorption method has good application prospects due to its high efficiency, rapidity and non-toxicity. However, conventional adsorption materials (such as activated carbon) have small oil absorption capacity, low oil retention capacity, poor oil-water selectivity, and most importantly, they cannot be regenerated and separated. After the final adsorption saturation, secondary pollution will occur. In addition, the hydrophobic properties of these oil-absorbing materials are usually poor. While recovering the floating oil, they will also absorb water, and the selective adsorption of oil and water cannot be achieved. In summary, it is urgent to develop materials that are conducive to oil-water separation in oily wastewater. Summary of the invention

[0004] The first purpose of the present invention is to provide a new method for preparing a graphene-based porous medium material. The graphene-based porous medium material prepared by the method is beneficial to the oil-water separation of oily wastewater.

[0005] Although graphene aerogel can be used to separate oil and water in oily wastewater, if the graphene aerogel is prepared entirely from graphene as raw material, not only is the production cost high, but the structural strength and regeneration performance are also poor. At the same time, graphene cannot be replaced by other forms such as graphene oxide, because graphene oxide is a hydrophilic material and cannot be used to separate oil and water in oily wastewater.

[0006] After in-depth and extensive research, the inventors of the present invention found that using graphene oxide as the starting material, directly loading graphene oxide on a porous medium material, and then sequentially adopting heating reduction treatment, ascorbic acid reduction treatment and microwave reduction treatment, the final graphene-based porous medium material obtained has very good oleophilic and hydrophobic properties, and can effectively separate oil and water in oily wastewater. It is speculated that the reason may be due to: heating reduction treatment can initially reduce graphene oxide, ascorbic acid reduction treatment can further reduce the unreduced graphene oxide located on the surface of the particles, microwaves can penetrate into the interior of the particles, and microwave reduction treatment can further reduce the unreduced graphene oxide inside the particles. Therefore, by combining these three reduction methods in a specific order, graphene oxide can be fully and deeply reduced to graphene, and the oleophilic and hydrophobic properties of the obtained material are finally improved. In view of this, the present invention is completed.

[0007] Specifically, the preparation method of the graphene-based porous medium material provided by the present invention includes loading graphene oxide in a porous medium material to obtain a porous medium material loaded with graphene oxide, and then sequentially subjecting the porous medium material loaded with graphene oxide to heating reduction treatment, ascorbic acid reduction treatment, and microwave reduction treatment.

[0008] In a preferred embodiment, the method for loading graphene oxide in a porous medium material comprises the following steps:

[0009] S1, initially immersing the porous medium material in an ethanol aqueous solution, and after the initial immersion is completed, taking the porous medium material out of the ethanol aqueous solution to obtain a wet porous medium material;

[0010] S2, immersing the wet porous medium material in the graphene oxide dispersion again, so that the graphene oxide enters the interior of the porous medium material, and after the immersion is completed, taking the wet porous medium material out of the graphene oxide dispersion to obtain a porous medium material loaded with graphene oxide.

[0011] In a preferred embodiment, in step S1, the concentration of the ethanol aqueous solution is 5wt% to 20wt%.

[0012] In a preferred embodiment, in step S1, the initial immersion is performed under ultrasonic conditions, and the ultrasonic conditions include a temperature of 15°C to 40°C and a time of 0.5h to 2h.

[0013] In a preferred embodiment, in step S2, the concentration of the graphene oxide dispersion is 0.2 wt‰ to 7 wt‰.

[0014] In a preferred embodiment, in step S2, the re-immersion is performed under ultrasonic conditions, and the ultrasonic conditions include a temperature of 20°C to 70°C and a time of 2h to 4h.

[0015] In a preferred embodiment, the method for preparing the graphene-based porous medium material further includes squeezing out the ethanol aqueous solution in the porous medium material after taking the porous medium material out from the ethanol aqueous solution; and / or, the method further includes extruding the wet porous medium material during the re-impregnation process; and / or, the method further includes removing the wet porous medium material from the graphene oxide dispersion and expelling 40% to 70% of the graphene oxide solution adsorbed in the wet porous medium material by extrusion.

[0016] In a preferred embodiment, the conditions of the heating reduction treatment include a temperature of 130° C. to 210° C. and a time of 5 h to 20 h.

[0017] In a preferred embodiment, the porous medium material loaded with graphene oxide is turned over once every 10 to 20 minutes during the heating reduction treatment.

[0018] In a preferred embodiment, the ascorbic acid reduction treatment is performed by spraying an ascorbic acid solution onto the porous medium material loaded with graphene oxide after the heating reduction treatment, and then reducing the material at a temperature of 80° C. to 100° C. for 2 h to 4 h.

[0019] In a preferred embodiment, the concentration of the ascorbic acid solution is 8 to 15 times the concentration of the graphene oxide solution.

[0020] In a preferred embodiment, the amount of the ascorbic acid solution is 0.5 to 2 times the mass of the porous medium material.

[0021] In a preferred embodiment, the microwave reduction treatment conditions include a microwave power of 500 to 900 W and a time of 60 to 150 s.

[0022] In a preferred embodiment, the porous medium material is selected from at least one of melamine sponge, polyurethane sponge, polyester fiber, polyvinyl alcohol porous material, low-density polyether sponge and EPDM rubber foam.

[0023] The second object of the present invention is to provide a graphene-based porous medium material prepared by the above method.

[0024] The third object of the present invention is to provide the application of the above-mentioned graphene-based porous medium material as an oil-water separation material and / or adsorption material.

[0025] The graphene-based porous medium material provided by the present invention has excellent oleophilic and hydrophobic properties and good adsorption effect. It can not only effectively separate oil and water from oily wastewater, but also can be used for amine liquid regeneration, etc., and solves the problem of the introduction of impurities in conventional oil-water separation. At the same time, the separated oil phase can be regenerated, which improves the economic value of the separated product. Furthermore, the graphene-based porous medium material provided by the present invention can be reused many times after regeneration, has high regeneration efficiency, has a good treatment effect on oily wastewater, and is particularly suitable for the separation and treatment of liquid mixtures with high oil phase cost, certain recovery value, and large water phase purity requirements, and are not suitable for the introduction of other impurities. The preparation method is green and non-toxic, environmentally friendly, and simple to operate. DETAILED DESCRIPTION

[0026] The preparation method of the graphene-based porous medium material provided by the present invention comprises loading graphene oxide in a porous medium material to obtain a porous medium material loaded with graphene oxide, and then sequentially performing a heating reduction treatment, an ascorbic acid reduction treatment, and a microwave reduction treatment on the porous medium material loaded with graphene oxide. The present invention combines graphene with the porous medium material, utilizes the mechanical strength and regeneration performance of the porous medium material itself and the oleophilic and hydrophobic properties of graphene, and gives the final graphene-based porous medium material good oil-water separation performance.

[0027] The present invention has no specific limitation on the method for loading graphene oxide on a porous medium material, and can be carried out in various existing ways, preferably including the following steps: S1, initially immersing the porous medium material in an ethanol aqueous solution, and after the initial immersion is completed, taking the porous medium material out of the ethanol aqueous solution to obtain a wet porous medium material S2, re-immersing the wet porous medium material in a graphene oxide dispersion so that the graphene oxide enters the interior of the porous medium material, and after the re-immersion is completed, taking the wet porous medium material out of the graphene oxide dispersion to obtain a porous medium material loaded with graphene oxide. Wherein, before the porous medium material is immersed in the graphene oxide dispersion, it is first immersed in an ethanol aqueous solution, the purpose is to improve the wettability of the porous medium material and the surface and void steric hindrance, which is conducive to the uniform dispersion of graphene oxide on the surface and voids of the porous medium material, and can more effectively improve the oil-water separation performance of the graphene-based porous medium material. The concentration of the ethanol solution is preferably 5wt% to 20wt%, such as 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt% or any value therebetween. The initial immersion is carried out under ultrasonic conditions, and the ultrasonic conditions preferably include a temperature of 15°C to 40°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C or any value therebetween; and a time of 0.5h to 2h, such as 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h or any value therebetween. The concentration of the graphene oxide dispersion is preferably 0.2wt‰ to 7wt‰, such as 0.2wt‰, 0.5wt‰, 1wt‰, 1.5wt‰, 2wt‰, 2.5wt‰, 3wt‰, 3.5wt‰, 4wt‰, 4.5wt‰, 5wt‰, 5.5wt‰, 6wt‰, 6.5wt‰, 7wt‰ or any value therebetween. The re-immersion is carried out under ultrasonic conditions, and the ultrasonic conditions preferably include a temperature of 20°C to 70°C, such as 20°C, 30°C, 40°C, 50°C, 60°C, 70°C or any value therebetween; the time is 2h to 4h. In the present invention, the terms "initial immersion" and "re-immersion" are intended to distinguish different immersion processes for ease of description and have no other special meanings.

[0028] In a preferred embodiment, the method of loading graphene oxide on a porous medium material further comprises extruding the ethanol aqueous solution in the porous medium material after the porous medium material is taken out from the ethanol aqueous solution; and / or, the method further comprises extruding the wet porous medium material during the re-impregnation process; and / or, the method further comprises extruding the 40% to 70% graphene oxide solution adsorbed in the wet porous medium material after the wet porous medium material is taken out from the graphene oxide dispersion. When the method of loading graphene oxide on a porous medium material further comprises extruding the ethanol aqueous solution in the porous medium material after the porous medium material is taken out from the ethanol aqueous solution, the utilization rate of ethanol can be improved, the loading efficiency and loading rate of graphene oxide can be increased, and the oil-water separation performance of the obtained graphene-based porous medium material is more excellent. When the method of loading graphene oxide on a porous medium material further comprises extruding the wet porous medium material during the re-impregnation process, the loading efficiency and loading amount of graphene oxide can be improved, the ultrasonic time can be shortened, and the oil-water separation performance of the graphene-based porous medium material can be improved. When the above-mentioned method of loading graphene oxide on a porous medium material also includes taking out the wet porous medium material from the graphene oxide dispersion, and then extruding 40% to 70% (such as 40%, 45%, 50%, 55%, 60%, 65%, 70% or any value therebetween) of the graphene oxide solution adsorbed in the wet porous medium material, the loading amount of graphene oxide can be effectively adjusted, the loading efficiency of graphene oxide can be improved, and the oil-water separation effect can be better.

[0029] In the present invention, the conditions for the heating reduction treatment preferably include a temperature of 130°C to 210°C, such as 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C or any value therebetween; a time of 5h to 20h, such as 5h, 8h, 10h, 12h, 15h, 18h, 20h or any value therebetween. In addition, preferably, during the heating reduction treatment, the porous medium material loaded with graphene oxide is turned over once every 10min to 20min, which can ensure the uniformity of the reduction and give the graphene-based porous medium material better oleophilic and hydrophobic properties, thereby more effectively separating the oily wastewater.

[0030] In the present invention, the ascorbic acid reduction treatment can be carried out by spraying an ascorbic acid solution on the porous medium material loaded with graphene oxide after the heating reduction treatment, and then heating and reducing. Wherein, the temperature of the heating reduction is preferably 80°C to 100°C, such as 80°C, 85°C, 90°C, 95°C, 100°C or any value therebetween; the time is preferably 2h to 4h, such as 2h, 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, 3.8h, 4h or any value therebetween. The concentration of the ascorbic acid solution is preferably 8 to 15 times the concentration of the graphene oxide solution, such as 8 times, 10 times, 12 times, 15 times or any value therebetween. The amount of the ascorbic acid solution is preferably 0.5 to 2 times the mass of the porous medium material, such as 0.5 times, 0.8 times, 1 times, 1.2 times, 1.5 times, 1.8 times, 2 times or any value therebetween.

[0031] In the present invention, the conditions for the microwave reduction treatment preferably include a microwave power of 500w to 900w, such as 500w, 550w, 600w, 650w, 700w, 750w, 800w, 850w, 900w or any value therebetween; and a time of 60s to 150s, such as 60s, 70s, 80s, 90s, 100s, 105s, 110s, 115s, 120s, 125s, 130s, 135s, 140s, 145s, 150s or any value therebetween.

[0032] In the present invention, specific examples of the porous medium material include but are not limited to: at least one of melamine sponge, polyurethane sponge, polyester fiber, polyvinyl alcohol porous material, low-density polyether sponge and EPDM rubber foam. The polyurethane sponge can be a high-density polyurethane sponge (density of 40-50 kg / m 3 ) and / or medium density polyurethane sponge (density 30-40kg / m 3). In practical applications, by adjusting the material, density, etc. of the porous medium material, graphene-based porous medium materials for different application scenarios can be obtained. For example, when the porous medium material is melamine, the graphene-based porous medium material has the ability to quickly and efficiently adsorb the oil phase, and is very suitable for emergency treatment of oil-water separation such as seawater crude oil leakage and oil field crude oil leakage contaminated water bodies; when the porous medium material is a medium-density polyurethane sponge, the graphene-based porous medium material has a high efficiency in adsorbing the oil phase and a strong regeneration ability. The adsorbed oil phase can be completely discharged by squeezing the saturated graphene porous medium material. The graphene-based porous medium material can be repeatedly used to adsorb the oil phase, and is very suitable for oily wastewater treatment in chemical plants and oil-water separation and recovery. When the porous medium material is a high-density polyurethane sponge, the graphene-based porous medium material has a high efficiency in adsorbing oil. Phase capacity and strong regeneration capacity, can be used in the field of amine liquid recovery and regeneration in chemical plants (amine liquid (aqueous phase) is mainly used for carbon capture or sulfur capture in chemical plants. After a period of use, impurities from the oil phase will be introduced into the amine liquid, which greatly affects the absorption efficiency of the amine liquid. Amine liquid has high requirements for purity and is not suitable for traditional oil-water separation methods such as flotation or precipitation). When the porous medium material is a medium-density polyurethane sponge and / or polyester fiber, the graphene-based porous medium material, in addition to having good oil-water separation performance, also has the ability to efficiently adsorb dust and VOC in the air. It is not only suitable for oil-water separation, but also suitable for air purification scenarios in homes or offices. Installing it in air purification equipment will have a better purification effect by enhancing air flow.

[0033] The present invention also provides a graphene-based porous medium material prepared by the above method.

[0034] In addition, the present invention also provides the use of the above-mentioned graphene-based porous medium material as an oil-water separation material and / or adsorption material.

[0035] The present invention will be described in detail below through examples.

[0036] Example 1

[0037] S1, placing a porous medium material (melamine sponge) in an ethanol aqueous solution with a concentration of 5wt% and ultrasonically treating it at room temperature for 0.5h, taking out the porous medium material after the ultrasonic treatment and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0038] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 1‰ and subjected to ultrasonic treatment for 2 hours. During the ultrasonic treatment, the temperature needs to be controlled at 70°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate into the porous medium material. The porous medium material is taken out, and 40% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0039] S3. The porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 130°C, the heating treatment time is 20h, and the porous medium material needs to be turned over every 15min during the thermal reduction treatment. The graphene porous medium material that has completed the thermal reduction treatment is evenly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 8 times the concentration of graphene oxide solution, and the amount of ascorbic acid solution is 2 times the mass of the porous medium material, and then reduced at 80°C for 4h. The graphene porous medium material that has completed the ascorbic acid reduction treatment is subjected to microwave reduction treatment, the microwave power is 500w, and the reduction time is 100s to obtain a graphene-based porous medium material.

[0040] Example 2

[0041] S1. placing a porous medium material (medium-density polyurethane sponge) in an ethanol aqueous solution with a concentration of 20 wt% and ultrasonically treating it at room temperature for 2 h. After the ultrasonic treatment, taking out the porous medium material and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0042] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 7‰ and subjected to ultrasonic treatment for 4 hours. During the ultrasonic treatment, the temperature needs to be controlled at 60°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate into the porous medium material. The porous medium material is taken out, and 70% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0043] S3. The porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 210°C, the heating treatment time is 7h, and the porous medium material needs to be turned over every 10min during the thermal reduction treatment. The graphene porous medium material that has completed the thermal reduction treatment is evenly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 15 times the concentration of graphene oxide solution, and the amount of ascorbic acid solution is 0.5 times the mass of the porous medium material, and then reduced at 100°C for 2h. The graphene porous medium material that has completed the ascorbic acid reduction treatment is subjected to microwave reduction treatment, the microwave power is 500w, and the reduction time is 150s, to obtain a graphene-based porous medium material.

[0044] Example 3

[0045] S1. placing a porous medium material (high-density polyurethane sponge) in an ethanol aqueous solution with a concentration of 12 wt% and subjecting it to ultrasonic treatment at room temperature for 1 h. After the ultrasonic treatment, taking out the porous medium material and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0046] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 3‰ and subjected to ultrasonic treatment for 3 hours. During the ultrasonic treatment, the temperature needs to be controlled at 50°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate the porous medium material. The porous medium material is taken out, and 55% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0047] S3. The porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 180°C, the heating treatment time is 12h, and the porous medium material needs to be turned over every 20min during the thermal reduction treatment. The graphene porous medium material that has completed the thermal reduction treatment is evenly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 12 times the concentration of graphene oxide solution, and the amount of ascorbic acid solution is 1 times the mass of the porous medium material, and then reduced at 90°C for 3h. The graphene porous medium material that has completed the ascorbic acid reduction treatment is subjected to microwave reduction treatment, the microwave power is 900w, and the reduction time is 125s, to obtain a graphene-based porous medium material.

[0048] Example 4

[0049] A graphene-based porous medium material is prepared according to the method of Example 1, except that step S1 does not include the step of squeezing out the ethanol aqueous solution in the porous medium material, and the remaining steps and conditions are the same as those of Example 1 to obtain a graphene-based porous medium material.

[0050] Example 5

[0051] A graphene-based porous medium material is prepared according to the method of Example 1, except that step S2 does not include a step of extruding the wet porous medium material during the impregnation process, and the remaining steps and conditions are the same as those of Example 1 to obtain a graphene-based porous medium material.

[0052] Example 6

[0053] A graphene-based porous medium material is prepared according to the method of Example 1, except that step S2 does not include the step of expelling the adsorbed 40% graphene oxide solution by extrusion, and the remaining steps and conditions are the same as those of Example 1 to obtain a graphene-based porous medium material.

[0054] Example 7

[0055] A graphene-based porous medium material is prepared according to the method of Example 1, except that in step S3, the porous medium material is not turned over during the thermal reduction treatment. The remaining steps and conditions are the same as those of Example 1 to obtain a graphene-based porous medium material.

[0056] Example 8

[0057] The graphene-based porous medium material is prepared according to the method of Example 1, except that step S1 is not included, and the porous medium material is directly immersed in the graphene oxide dispersion. The remaining steps and conditions are the same as those of Example 1. The specific steps are as follows:

[0058] S1. The wet porous medium material (melamine sponge) is completely immersed in a graphene oxide dispersion having a concentration of 1‰ and subjected to ultrasonic treatment for 2 hours. During the ultrasonic treatment, the temperature needs to be controlled at 70°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate the porous medium material. The porous medium material is taken out, and 40% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0059] S2. The porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 130°C, the heating treatment time is 20h, and the porous medium material needs to be turned over every 15min during the thermal reduction treatment. The graphene porous medium material that has completed the thermal reduction treatment is evenly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 8 times the concentration of graphene oxide solution, and the amount of ascorbic acid solution is 2 times the mass of the porous medium material, and then reduced at 80°C for 4h. The graphene porous medium material that has completed the ascorbic acid reduction treatment is subjected to microwave reduction treatment, the microwave power is 500w, and the reduction time is 100s to obtain a graphene-based porous medium material.

[0060] Comparative Example 1

[0061] The graphene-based porous medium material is prepared according to the method of Example 1, except that the thermal reduction treatment is not included, but the ascorbic acid reduction treatment is directly performed. The specific steps are as follows:

[0062] S1, placing a porous medium material (melamine sponge) in an ethanol aqueous solution with a concentration of 5wt% and ultrasonically treating it at room temperature for 0.5h, taking out the porous medium material after the ultrasonic treatment and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0063] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 1‰ and subjected to ultrasonic treatment for 2 hours. During the ultrasonic treatment, the temperature needs to be controlled at 70°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate into the porous medium material. The porous medium material is taken out, and 40% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0064] S3, the porous medium material loaded with graphene oxide is uniformly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 8 times the concentration of graphene oxide solution, the amount of ascorbic acid solution is 2 times the mass of the porous medium material, first reduced at 130°C for 20h, and then reduced at 80°C for 4h. The graphene porous medium material after ascorbic acid reduction treatment is subjected to microwave reduction treatment, the microwave power is 500w, and the reduction time is 100s, to obtain a graphene-based porous medium material.

[0065] Comparative Example 2

[0066] The graphene-based porous medium material is prepared according to the method of Example 1, except that the ascorbic acid reduction treatment is not included, and only the thermal reduction treatment and the microwave reduction treatment are sequentially performed. The specific steps are as follows:

[0067] S1, placing a porous medium material (melamine sponge) in an ethanol aqueous solution with a concentration of 5wt% and ultrasonically treating it at room temperature for 0.5h, taking out the porous medium material after the ultrasonic treatment and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0068] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 1‰ and subjected to ultrasonic treatment for 2 hours. During the ultrasonic treatment, the temperature needs to be controlled at 70°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate into the porous medium material. The porous medium material is taken out, and 40% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0069] S3, the porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 130°C, the heating treatment time is 20h, and then reduced at 80°C for 4h, and the porous medium material needs to be turned over every 15min during the thermal reduction process. The graphene porous medium material that has completed the thermal reduction treatment is subjected to microwave reduction treatment, the microwave power is 500w, and the reduction time is 100s, to obtain a graphene-based porous medium material.

[0070] Comparative Example 3

[0071] The graphene-based porous medium material is prepared according to the method of Example 1, except that the microwave reduction treatment is not included, and only the thermal reduction treatment and the ascorbic acid reduction treatment are sequentially performed. The specific steps are as follows:

[0072] S1, placing a porous medium material (melamine sponge) in an ethanol aqueous solution with a concentration of 5wt% and ultrasonically treating it at room temperature for 0.5h, taking out the porous medium material after the ultrasonic treatment and squeezing out the ethanol aqueous solution in the porous medium material to obtain a wet porous medium material;

[0073] S2. The wet porous medium material is completely immersed in a graphene oxide dispersion having a concentration of 1‰ and subjected to ultrasonic treatment for 2 hours. During the ultrasonic treatment, the temperature needs to be controlled at 70°C. During the immersion process, the wet porous medium material is squeezed to allow the graphene oxide dispersion to fully penetrate into the porous medium material. The porous medium material is taken out, and 40% of the adsorbed graphene oxide solution is expelled by squeezing to obtain a porous medium material loaded with graphene oxide.

[0074] S3. The porous medium material loaded with graphene oxide is subjected to thermal reduction treatment, the thermal reduction temperature is 130°C, the heating treatment time is 20h, and the porous medium material needs to be turned over every 15min during the thermal reduction treatment. The graphene porous medium material that has completed the thermal reduction treatment is evenly sprayed with ascorbic acid solution, the concentration of ascorbic acid solution is 8 times the concentration of graphene oxide solution, and the amount of ascorbic acid solution is 2 times the mass of the porous medium material, and then reduced at 80°C for 4h, and then reduced at room temperature for 100s to obtain a graphene-based porous medium material.

[0075] Test Case

[0076] The graphene-based porous medium materials obtained in the above examples and comparative examples were tested for oil-water separation performance according to the following method:

[0077] Diesel was used to prepare oily wastewater with a concentration of 1800 g / L. The graphene-based porous medium materials obtained in the above examples and comparative examples were respectively loaded into an oil-water separator, and the oily wastewater was passed through the oil-water separator equipped with the graphene-based porous medium material. The oil content in the effluent was monitored in real time. When the oil content in the effluent was greater than 10 g / L, the graphene-based porous medium material was considered to be saturated with oil adsorption, and water was stopped. The saturated graphene-based porous medium material was extruded and regenerated, and the regenerated oil was weighed. The weight of the oil divided by the volume of the graphene-based porous medium material was the oil absorption rate. The results are shown in Table 1.

[0078] Table 1

[0079] serial number <![CDATA[Oil-water separation performance - Oil absorption rate (g / cm 3 )]]> Example 1 0.67 Example 2 0.70 Example 3 0.72 Example 4 0.61 Example 5 0.60 Example 6 0.63 Example 7 0.55 Example 8 0.52 Comparative Example 1 0.40 Comparative Example 2 0.46 Comparative Example 3 0.43

[0080] It can be seen from the results in Table 1 that the graphene-based porous medium material obtained by the method provided by the present invention has good oil-water separation performance.

[0081] From the comparison between Example 1 and Examples 4 to 6, it can be seen that in the preparation process of the graphene-based porous medium material, squeezing out the ethanol aqueous solution in the porous medium material after the initial impregnation, or squeezing the wet porous medium material during the re-impregnation process, or removing the wet porous medium material from the graphene oxide dispersion and then expelling part of the graphene oxide solution adsorbed in the wet porous medium material by squeezing, can all more significantly improve the oil-water separation performance of the graphene-based porous medium material.

[0082] From the comparison between Example 1 and Example 7, it can be seen that when the porous medium material loaded with graphene oxide is turned over at regular intervals during the heating reduction process, the uniformity of the reduction can be ensured, and the graphene-based porous medium material can be given better oleophilic and hydrophobic properties, and the oil-water separation effect is better.

[0083] From the comparison between Example 1 and Example 8, it can be seen that in the preparation process of the graphene-based porous medium material, the porous medium material is immersed in an ethanol aqueous solution before being immersed in the graphene oxide dispersion, which can give the graphene-based porous medium material a better oil-water separation performance.

[0084] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for preparing a graphene-based porous medium material, characterized in that: The method comprises loading graphene oxide in a porous medium material to obtain a porous medium material loaded with graphene oxide, and then sequentially performing heating reduction treatment, ascorbic acid reduction treatment and microwave reduction treatment on the porous medium material loaded with graphene oxide; The method for loading graphene oxide in a porous medium material comprises the following steps: S1, initially immersing the porous medium material in an ethanol aqueous solution, and after the initial immersion is completed, taking the porous medium material out of the ethanol aqueous solution to obtain a wet porous medium material; S2, re-immersing the wet porous medium material in the graphene oxide dispersion so that the graphene oxide enters the interior of the porous medium material, and after the re-immersion is completed, taking the wet porous medium material out of the graphene oxide dispersion to obtain a porous medium material loaded with graphene oxide; The conditions of the heating reduction treatment include a temperature of 130°C to 210°C and a time of 5h to 20h; The ascorbic acid reduction treatment is carried out by spraying an ascorbic acid solution onto the porous medium material loaded with graphene oxide after the heating reduction treatment, and then reducing the material at a temperature of 80° C. to 100° C. for 2 h to 4 h; The microwave reduction treatment conditions include a microwave power of 500w-900w and a time of 60s-150s; The porous medium material is selected from at least one of melamine sponge, polyurethane sponge, polyester fiber, polyvinyl alcohol porous material, low-density polyether sponge and EPDM rubber foam.

2. The method for preparing a graphene-based porous medium material according to claim 1, characterized in that: In step S1, the concentration of the ethanol aqueous solution is 5wt%~20wt%; the initial immersion is performed under ultrasonic conditions, and the ultrasonic conditions include a temperature of 15°C~40°C and a time of 0.5h~2h; In step S2, the concentration of the graphene oxide dispersion is 0.2wt‰~7wt‰; the re-immersion is performed under ultrasonic conditions, and the ultrasonic conditions include a temperature of 20°C~70°C and a time of 2h~4h.

3. The method for preparing a graphene-based porous medium material according to claim 1, characterized in that: The method further includes squeezing out the ethanol aqueous solution in the porous medium material after taking the porous medium material out from the ethanol aqueous solution; and / or, the method further includes squeezing the wet porous medium material during the re-impregnation process; and / or, the method further includes expelling 40% to 70% of the graphene oxide dispersion adsorbed in the wet porous medium material by squeezing after taking the wet porous medium material out from the graphene oxide dispersion.

4. The method for preparing a graphene-based porous medium material according to any one of claims 1 to 3, characterized in that: During the heating reduction treatment, the porous medium material loaded with graphene oxide is turned over once every 10 minutes to 20 minutes.

5. The method for preparing a graphene-based porous medium material according to any one of claims 1 to 3, characterized in that: The concentration of the ascorbic acid solution is 8 to 15 times the concentration of the graphene oxide dispersion.

6. The method for preparing a graphene-based porous medium material according to any one of claims 1 to 3, characterized in that: The amount of the ascorbic acid solution used is 0.5 to 2 times the mass of the porous medium material.

7. Use of the graphene-based porous medium material prepared by the method according to any one of claims 1 to 6 as an oil-water separation material and / or adsorption material.