Method for removing micro-plastics in water body based on graphene oxide and high-valued recycling of micro-plastics

Abstract

The invention discloses a method for removing micro-plastics in a water body based on graphene oxide and high-valued recycling of the micro-plastics, the advantage of in-situ reduction self-assembly of graphene oxide is utilized, the barrier characteristic of hydrophobicity of graphene oxide to water vapor is exerted, and the micro-plastics in the water body and graphene oxide are firmly combined, so that the micro-plastics in the water body can be recycled, and the utilization rate of the micro-plastics in the water body is increased. The graphene-micro-plastic composite plastic-based carbon material is formed, so that the micro-plastic is recycled from a water body. The method can be applied to removal of micro-plastics in water, 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, micro-plastic concentration and the like. Compared with a traditional water body micro-plastic removal method, the method has the advantages that the removal efficiency is high, and the time and the cost can be saved; meanwhile, the micro-plastic / graphene compound formed in the water body micro-plastic removal method can be recycled in a high-valued mode, for example, the micro-plastic / graphene compound is used for preparing a plastic-based carbon material, and therefore cyclic and reasonable utilization of resources is facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of microplastic removal, and in particular relates to a method for removing microplastics from water bodies and their high-value recycling based on graphene oxide. Plastic-based carbon materials can be used in the fields of environmental functional materials, structural materials, catalysis, energy storage, seawater desalination and microplastic concentration. Background Art

[0002] Microplastics refer to plastic particles with a diameter of less than 5mm. In recent years, with the development of the economy, plastic products have been widely used, and a lot of plastic waste has also been generated. They are broken into smaller plastic fragments through a series of reactions in the environment such as wear, light, and biology. These plastic fragments have a large specific surface area and are good attachment carriers for other pollutants and pathogens. These difficult-to-decompose plastic fragments will spread to various regions of the world through atmospheric circulation, water circulation, etc., causing permanent, large-scale pollution. At the same time, due to the ingestion of aquatic organisms, microplastics will continue to accumulate along the food chain and eventually accumulate in the human body. According to scientists' estimates, the content of microplastics in freshwater environments is several times that in other environments. Therefore, the removal of microplastics in water bodies has attracted more and more attention.

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

[0004] Therefore, how to design an efficient, high-value and reusable method to remove microplastics from water is a technical problem to be solved. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a method for removing microplastics in water and their high-value reuse based on graphene oxide.

[0006] In a first aspect, the present application provides a method for removing microplastics in water based on graphene oxide, comprising the following steps:

[0007] S1: adding graphene oxide to water containing microplastics for dispersion to obtain a mixed solution containing microplastics and graphene oxide;

[0008] S2: adding a reducing agent to the mixed solution and heating the mixed solution, washing the solid product formed by the heating reduction, and obtaining a composite of microplastics and graphene oxide;

[0009] S3: soaking the composite in an activator and drying it, and performing high-temperature activation carbonization in an inert gas atmosphere;

[0010] S4: washing the carbonized composite with hydrochloric acid and deionized water, and then drying it to obtain a plastic-based carbon material.

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

[0012] The particle size of the microplastics is 5nm-0.5mm.

[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, the ultrasonic power of the ultrasonic cleaner is 100 to 240 W, and the ultrasonic time is 15 to 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 mixed solution is 2:1 to 5:1; the reduction temperature is 80° C. to 100° C., 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 composite is 0.2:1 to 3:1, the pretreatment time of the activator is 1 to 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 to 24 hours, and the drying temperature is 60°C to 200°C.

[0017] Preferably, the inert gas is nitrogen or argon; when high-temperature activated carbonization is performed under an inert gas atmosphere, the temperature is increased twice.

[0018] Preferably, during the first heating, the flow rate of the inert gas is 20 to 100 ml / min, the heating rate is 3 to 5°C / min, the final temperature is 300 to 350°C, and the holding time is 0.5 to 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 activated carbonization is 0.5-2M, and the drying temperature is 60-80°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the present invention utilizes the advantages of in-situ reduction self-assembly of graphene oxide, and gives play to the barrier properties of graphene oxide hydrophobicity to water vapor, firmly combines microplastics in water with graphene oxide, and forms graphene-microplastic composite plastic-based carbon materials, thereby recovering microplastics from water bodies. The present invention can not only be applied to the removal of microplastics in water bodies, but also the plastic-based carbon materials formed by the method of the present invention can be used in the fields of environmental functional materials, structural materials, catalysis, energy storage, seawater desalination and microplastic concentration. Compared with the traditional method for removing microplastics from water bodies, the present invention has better removal efficiency and can save time and cost; at the same time, the microplastic / graphene composite formed in the method for removing microplastics from water bodies can be reused at a high value, such as for preparing plastic-based carbon materials, which is conducive to the rational recycling of resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A more complete understanding of exemplary embodiments of the present invention may be obtained by reference to the following drawings.

[0023] Figure 1 The figure is a physical picture before and after restoration in Example 1;

[0024] Figure 2 This is a physical picture of the plastic-based carbon material sample obtained after the activation and carbonization of the microplastic and graphene composite of Example 1;

[0025] Figure 3 This is the SEM image of the plastic-based carbon material of Example 1. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] The following is a description of a method for removing microplastics in water using graphene oxide according to an embodiment of the present invention.

[0028] Example 1

[0029] A method for removing microplastics in water based on graphene oxide, comprising the following steps:

[0030] S1: Add graphene oxide and microplastics to 10 ml of deionized water in a mass ratio of 2:1, and place the mixed solution in an ultrasonic cleaner for 30 minutes to disperse it evenly to obtain a mixed solution of microplastics and graphene oxide:

[0031] S2: adding ascorbic acid to the mixture of microplastics and graphene oxide in a ratio of 4:1, placing the mixture in an oil bath at 95°C for reduction reaction for 5 hours, calculating the removal rate of microplastics, and washing the solid product to obtain a microplastic and graphene composite;

[0032] S3: According to the mass ratio of potassium hydroxide to microplastics of 1:1, the microplastics and graphene composites were soaked in potassium hydroxide for 1 hour and then washed with water, and placed in an oven at 80°C for 12 hours. The dried samples were activated at high temperature in a nitrogen atmosphere in a tubular furnace. The flow rate of nitrogen was 20 ml / min, the first heating rate of the tubular furnace was 3°C / min, the carbonization temperature was 350°C, 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°C to obtain a plastic-based carbon material sample.

[0034] Embodiment 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] Embodiment 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] Changes 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 the three ratio conditions, graphene oxide has a good removal effect on microplastic particles in water bodies.

[0045] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for removing microplastics in water based on graphene oxide, characterized in that: The steps include: S1: adding graphene oxide to water containing microplastics for dispersion to obtain a mixed solution containing microplastics and graphene oxide; S2: adding a reducing agent to the mixed solution and heating the mixed solution, washing the solid product formed by the heating reduction, and obtaining a composite of microplastics and graphene oxide; S3: soaking the composite in an activator and drying it, and performing high-temperature activation carbonization in an inert gas atmosphere; S4: washing the carbonized composite with hydrochloric acid and deionized water, and then drying it to obtain a plastic-based carbon material.

2. A method for removing microplastics in water based on graphene oxide according to claim 1, characterized in that: The microplastics are composed of one or more of polystyrene plastics (PS), polyethylene plastics (PE), polyvinyl chloride plastics (PVC), and polypropylene plastics (PP); the particle size of the microplastics is 5nm-0.5mm.

3. A method for removing microplastics in water based on graphene oxide according to claim 1, characterized in that: In the step S1, an ultrasonic cleaner is used for dispersion, the ultrasonic power of the ultrasonic cleaner is 100 to 240 W, and the ultrasonic time is 15 to 120 minutes.

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

5. The method for removing microplastics in water based on graphene oxide according to claim 1, characterized in that: 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 mixed solution is 2:1 to 5:1; The reduction temperature is 80° C. to 100° C., the reduction reaction time is 3 to 8 hours, and no stirring is performed during the reduction process.

6. The method for removing microplastics in water based on graphene oxide according to claim 1, characterized in that: In the step S3, the mass ratio of the activator to the composite is 0.2:1 to 3:1, the pretreatment time of the activator is 1 to 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 to 24 hours, and the drying temperature is 60°C to 200°C.

7. The method for removing microplastics in water based on graphene oxide according to claim 1, characterized in that: In step S3, the inert gas is nitrogen or argon; when high-temperature activation carbonization is performed in an inert gas atmosphere, the temperature is increased twice.

8. A method for removing microplastics in water based on graphene oxide according to claim 7, characterized in that: During the first heating, the flow rate of the inert gas 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; 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; The concentration of hydrochloric acid used for high temperature activated carbonization is 0.5-2M, and the drying temperature is 60-80°C.

9. A plastic-based carbon material, characterized in that: The plastic-based carbon material is prepared by a method for removing microplastics in water based on graphene oxide as described in any one of claims 1 to 8.

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