A method for removing microplastics in water bodies based on graphene oxide and high-value recycling thereof

Abstract

The application discloses a method for removing microplastics in water bodies based on graphene oxide and high-value recycling of the microplastics, which utilizes the advantages of in-situ reduction and self-assembly of graphene oxide, and plays the blocking characteristics of graphene oxide hydrophobicity to water vapor, firmly combines the microplastics in the water body with the graphene oxide, forms a graphene-microplastic composite plastic-based carbon material, and thus recycles the microplastics from the water body. The application can be applied to the removal of microplastics in water bodies, and the plastic-based carbon material formed by the method can also be used in the fields of environmental functional materials, structural materials, catalysis, energy storage, seawater desalination and microplastic concentration. Compared with traditional methods for removing microplastics in water bodies, the application has good removal efficiency, can save time and cost, and meanwhile, the microplastic / graphene composite formed in the method for removing microplastics in water bodies can be recycled and utilized in high value, such as being used to prepare plastic-based carbon materials, so as to be beneficial to the recycling and reasonable utilization of resources.

Description

Technical Field

[0001] This invention belongs to the field of microplastic removal, and particularly relates to a method for removing microplastics from water and their high-value reuse based on graphene oxide. The plastic-based carbon material can be used in environmental functional materials, structural materials, catalysis, energy storage, seawater desalination and microplastic concentration. Background Technology

[0002] Microplastics refer to plastic particles with a diameter of less than 5 mm. In recent years, with economic development, plastic products have been widely used, resulting in a large amount of plastic waste. Through a series of reactions in the environment, such as abrasion, light exposure, and biological processes, these plastics eventually break down into smaller fragments. These plastic fragments have a large specific surface area, making them excellent carriers for other pollutants and pathogens. These difficult-to-decompose plastic fragments spread to various regions of the world through atmospheric and water cycles, causing permanent and large-scale pollution. At the same time, due to the ingestion of aquatic organisms, microplastics accumulate along the food chain and eventually become bioaccumulated in the human body. According to scientists' estimates, the content of microplastics in freshwater environments is several times higher than in other environments. Therefore, the removal of microplastics from water bodies is attracting increasing attention.

[0003] Graphene oxide is a novel carbon material with superior performance, high specific surface area and abundant functional groups, and has broad application prospects in the field of materials. When applied to the removal of microplastics, it can not only effectively remove microplastic particles in the aquatic environment, but also convert them into plastic-based carbon materials, realizing high-value reuse. It has broad application prospects in environmental functional materials, structural materials, catalysis, energy storage, seawater desalination and microplastic concentration.

[0004] Therefore, designing an efficient, high-value, and reusable method for removing microplastics from water is a technical problem that needs to be solved. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for removing microplastics from water and their high-value reuse based on graphene oxide.

[0006] In a first aspect, embodiments of this application provide a method for removing microplastics from water based on graphene oxide, comprising the following steps:

[0007] S1: Graphene oxide is added to water containing microplastics and dispersed to obtain a mixture containing microplastics and graphene oxide.

[0008] S2: Add a reducing agent to the mixture and heat it. Wash the solid product formed by the heating reduction to obtain a composite of microplastics and graphene oxide.

[0009] S3: The composite is soaked in an activator and dried, and then activated and carbonized at high temperature in an inert gas atmosphere;

[0010] S4: The carbonized composite is washed with hydrochloric acid and deionized water and then dried to obtain a plastic-based carbon material.

[0011] Preferably, the microplastic is composed of one or more of polystyrene (PS), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP);

[0012] The microplastic particles have a size of 5 nm to 0.5 mm.

[0013] Preferably, the mass ratio of dispersed graphene oxide to microplastics is 2:1 to 6:1, and the concentration of graphene oxide is 2 mg / ml to 10 mg / ml.

[0014] Preferably, in step S1, an ultrasonic cleaner is used for dispersion, and the ultrasonic power of the ultrasonic cleaner is 100-240W, and the ultrasonic time is 15-120 minutes.

[0015] Preferably, in step S2, the reducing agent is ascorbic acid, sodium borohydride, or sodium hydroxide, and the mass ratio of the reducing agent to the graphene oxide in the mixture is 2:1 to 5:1; the reduction temperature is 80℃ to 100℃, the reduction reaction time is 3 to 8 hours, and no stirring is performed during the reduction process.

[0016] Preferably, in step S3, the mass ratio of the activator to the complex is 0.2:1 to 3:1, the pretreatment time of the activator is 1-3 hours, and the activator is composed of one or more of potassium hydroxide, potassium carbonate, zinc chloride and H3PO4; the drying time is 12-24 hours, and the drying temperature is 60℃ to 200℃.

[0017] Preferably, the inert gas is nitrogen or argon; during the high-temperature activation carbonization in the inert gas atmosphere, the temperature was raised twice.

[0018] Preferably, during the initial heating, the inert gas flow rate is 20–100 ml / min, the heating rate is 3–5 °C / min, the final temperature is 300–350 °C, and the holding time is 0.5–2 hours.

[0019] During the second heating, the flow rate of the inert gas is 20-100 ml / min, 5-10 °C / min, the final temperature is 600-800 °C, and the holding time is 1-3 hours.

[0020] The concentration of hydrochloric acid used for high-temperature activation carbonization is 0.5–2M, and the drying temperature is 60–80℃.

[0021] Compared with existing technologies, this invention has the following advantages: It utilizes the advantages of in-situ reduction and self-assembly of graphene oxide and leverages the hydrophobic properties of graphene oxide to block water vapor, firmly binding microplastics in water with graphene oxide to form a graphene-microplastic composite plastic-based carbon material, thereby recovering microplastics from water bodies. This invention can not only be applied to the removal of microplastics from water bodies, but the plastic-based carbon material formed by this method can also be used in environmental functional materials, structural materials, catalysis, energy storage, seawater desalination, and microplastic concentration. Compared with traditional methods for removing microplastics from water bodies, this invention has better removal efficiency, saving time and costs. Simultaneously, the microplastic / graphene composite formed in this method can be reused at high value, such as for preparing plastic-based carbon materials, thus promoting the rational and circular use of resources. Attached Figure Description

[0022] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures.

[0023] Figure 1 These are photos of the physical objects before and after restoration in Example 1;

[0024] Figure 2 This is a physical image of the plastic-based carbon material sample obtained after the microplastic and graphene composite of Example 1 was activated and carbonized.

[0025] Figure 3 This is a SEM image of the plastic-based carbon material from Example 1. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] The following describes a method for removing microplastics from water using graphene oxide, according to an embodiment of the present invention.

[0028] Example 1

[0029] A method for removing microplastics from water based on graphene oxide includes the following steps:

[0030] S1: Add graphene oxide and microplastics to 10ml of deionized water at a mass ratio of 2:1. Place the mixture in an ultrasonic cleaner and sonicate for 30 minutes to disperse it evenly, obtaining a mixture of microplastics and graphene oxide.

[0031] S2: Ascorbic acid was added to the mixture of microplastics and graphene oxide in a ratio of 4:1. The mixture was placed in an oil bath at 95°C for 5 hours for reduction reaction. The removal rate of microplastics was calculated, and the solid product was washed to obtain the microplastic and graphene composite.

[0032] S3: Following a 1:1 mass ratio of potassium hydroxide to microplastics, the microplastics and graphene composite were soaked in potassium hydroxide for 1 hour, washed with water, and dried in an oven at 80°C for 12 hours. The dried sample was then activated at high temperature in a tube furnace under a nitrogen atmosphere. The flow rate of nitrogen was 20 ml / min, the first heating rate of the tube furnace was 3°C / min, the carbonization temperature was 350°C, and the holding time was 1 hour. The second heating rate was 5°C / min, the carbonization temperature was 750°C, and the holding time was 1.5 hours.

[0033] S4: The activated sample was rinsed with 1M hydrochloric acid and deionized water until pH=7, and dried in an oven at 80℃ to obtain a plastic-based carbon material sample.

[0034] Example 2:

[0035] The content of Example 2 is basically the same as that of Example 1, except that in step S1, the mass ratio of graphene oxide to microplastics is 3:1.

[0036] Example 3:

[0037] The content of Example 3 is basically the same as that of Example 1, except that in step S1, the mass ratio of graphene oxide to microplastics is 6:1.

[0038] The experimental data are as follows:

[0039] Change in needle weight before and after adsorption

[0040]

[0041]

[0042] Microplastic removal rate

[0043] Unit (g) Before adsorption After adsorption Removal rate Example 1 0.0223 0.0004 98.21％ Example 2 0.0423 0.0025 94.09％ Example 3 0.0605 0.0002 99.67％

[0044] It can be seen that under all three ratio conditions, graphene oxide has a good removal effect on microplastic particles in water.

[0045] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for removing microplastics from a water body based on graphene oxide, characterized in that, The method comprises the following steps: S1: adding graphene oxide into a water body containing microplastics for dispersion to obtain a mixed solution containing microplastics and graphene oxide; S2: adding a reducing agent into the mixed solution and heating, and washing a solid product formed by heating reduction to obtain a composite of microplastics and graphene oxide; S3: soaking the composite in an activator and drying, and performing high-temperature activation carbonization under an inert gas atmosphere; S4: washing the composite after high-temperature activation carbonization with hydrochloric acid and deionized water, and drying to obtain a plastic-based carbon material. In the step S3, the inert gas is nitrogen or argon; when high-temperature activation carbonization is performed under an inert gas atmosphere, two temperature rising processes are performed; in the first temperature rising process, the flow rate of the inert gas is 20-100 mL / min, the temperature rising rate is 3-5 ℃ / min, the final temperature is 300-350 ℃, and the holding time is 0.5-2 hours; in the second temperature rising process, the flow rate of the inert gas is 20-100 mL / min, the temperature rising rate is 5-10 ℃ / min, the final temperature is 600-800 ℃, and the holding time is 1-3 hours.

2. The method for removing microplastics from water bodies based on graphene oxide according to claim 1, characterized in that: The microplastics are composed of one or more of polystyrene plastic, polyethylene plastic, polyvinyl chloride plastic, and polypropylene plastic.

3. The method for removing microplastics from water bodies based on graphene oxide according to claim 1, characterized in that, In the step S1, the dispersion is performed by using an ultrasonic cleaning instrument, the ultrasonic power of the ultrasonic cleaning instrument is 100-240 W, and the ultrasonic time is 15-120 minutes.

4. The method for removing microplastics from water bodies based on graphene oxide according to claim 1, characterized in that, The mass ratio of graphene oxide to microplastics for dispersion is 2:1-6:1, and the concentration of graphene oxide is 2 mg / mL-10 mg / mL.

5. The method for removing microplastics from water bodies based on graphene oxide according to claim 1, characterized in that, In the step S2, the reducing agent is ascorbic acid or sodium borohydride, and the mass ratio of the reducing agent to graphene oxide in the mixed solution is 2:1-5:1; The reduction temperature is 80-100 ℃, the reduction reaction time is 3-8 hours, and the reduction process is not stirred.

6. The method for removing microplastics from water bodies based on graphene oxide according to claim 1, characterized in that, The mass ratio of the activator to the complex in the step S3 is 0.2:1-3:1, and the activator is composed of one or more of potassium hydroxide, potassium carbonate, zinc chloride and The drying time is 12-24 hours, and the drying temperature is 60℃-200℃.

7. A plastic-based carbon material, characterized by, The plastic-based carbon material is prepared by the method for removing microplastics in a water body based on graphene oxide according to any one of claims 1-6.

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