Graphene-loaded flat sheet packing and its use

Abstract

The application provides a graphene-loaded flat plate filler and application thereof, and relates to the technical field of sewage treatment. The graphene-loaded flat plate filler provided by the application comprises a flat plate filler base material and positive charge modified graphene oxide, and the positive charge modified graphene oxide is loaded on the flat plate filler base material; and the preparation method of the positive charge modified graphene oxide comprises the following steps: dispersing graphene oxide in a solvent, then mixing with an iron salt, and then preparing the positive charge modified graphene oxide through gamma ray irradiation reaction. The graphene-loaded flat plate filler can attract the microorganism flora with negative charges which are dominant in sewage treatment through the loaded positive charge modified graphene oxide, and the surface of the flat plate filler can be provided with a honeycomb-shaped recess structure, so that the specific surface area of the filler is improved, the optimal environment and space are provided for the microorganism adhesion, and the biofilm formation effect is greatly promoted.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a graphene-loaded flat packing material and its application. Background Technology

[0002] In wastewater treatment processes, biofilm processes widely utilize various packing materials. These materials provide a growth space for microorganisms, improving wastewater treatment efficiency. Commonly used packing materials in biofilm processes include suspended packing, flexible packing, and combined packing. Suspended packing is injection-molded from polypropylene material, consisting of inner and outer double-layered spheres. The outer layer is a hollow, net-like sphere, while the inner layer is a rotating sphere. Flexible packing uses vinylon filaments as raw material, composed of a central rope and soft fiber bundles. Combined packing is developed based on flexible and semi-flexible packing, combining the advantages of both. Its structure involves evenly distributing soft fibers or polyester filaments on the outer ring, while the inner ring consists of ice-flower-shaped plastic branches, which can both support biofilm and effectively cut air bubbles, improving oxygen transfer rate and utilization.

[0003] Flat plate packing is a type of packing material, but its practical application is not widespread. This is because existing flat plate packing technologies focus on the application of the packing device itself, lacking development on the material of the packing itself. Current flat plate packing materials are all made of conventional PP (polypropylene)-ES (ES fiber) blended materials. There is a lack of research on key performance indicators beneficial to biofilm treatment of wastewater, such as specific surface area, microbial adhesion performance, and water permeability, resulting in poor biofilm formation during practical applications.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The first objective of this invention is to provide a flat sheet filler loaded with graphene to solve at least one of the above-mentioned problems.

[0006] A second objective of this invention is to provide the application of the above-mentioned graphene-loaded flat packing material in wastewater treatment.

[0007] In a first aspect, the present invention provides a flat sheet filler loaded with graphene, comprising a flat sheet filler substrate and positively charged modified graphene oxide, wherein the positively charged modified graphene oxide is loaded on the flat sheet filler substrate.

[0008] The preparation method of the positively charged modified graphene oxide includes:

[0009] Positively charged modified graphene oxide was prepared by dispersing graphene oxide in a solvent, mixing it with iron salt, and then reacting it with gamma rays.

[0010] As a further technical solution, the solvent includes tetrahydrofuran, polyethylene, or ethylene-methyl acrylate copolymer.

[0011] As a further technical solution, the iron salt includes ferrous sulfate;

[0012] During the reaction, the final concentration of the iron salt is 1wt%-10wt%.

[0013] As a further technical solution, the radiation dose of the gamma rays is 10-100 kGy.

[0014] As a further technical solution, the positively charged modified graphene oxide is loaded onto a flat filler substrate in the form of a graphene film or graphene fiber.

[0015] As a further technical solution, the graphene film is a substrate material on which the positively charged modified graphene oxide is sprayed.

[0016] The graphene film is loaded onto the flat filler substrate by means of stitching or bonding.

[0017] As a further technical solution, the graphene fiber is a fiber filament of a substrate material doped with the positively charged modified graphene oxide;

[0018] The method of loading graphene fibers onto a flat sheet filler substrate includes: blending graphene fibers with a flat sheet filler substrate.

[0019] As a further technical solution, the substrate material includes PP or PE (polyethylene).

[0020] As a further technical solution, the flat sheet filler substrate is mainly made of at least one blend of polypropylene, PP, ES or polyester;

[0021] And / or, the surface of the flat filler substrate has a honeycomb-like recessed structure.

[0022] Secondly, the present invention provides the application of the above-mentioned graphene-loaded flat packing material in wastewater treatment.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The graphene-loaded flat packing provided by this invention, through the positively charged modified graphene oxide, can attract the dominant negatively charged microbial community in wastewater treatment. Simultaneously, the surface of the flat packing can be configured with a honeycomb-like concave structure, increasing the specific surface area of ​​the packing and providing an optimal environment and space for microbial implantation, greatly promoting biofilm formation. The flat packing has high permeability, does not obstruct the flow pattern in the wastewater treatment process, ensures uniform mixing of sludge and water without short-circuiting, and can withstand various load impacts, making it suitable for treating different types of wastewater. The flat packing also has a filtration function, and can be used as the end-stage material in biological wastewater treatment sedimentation tanks to filter effluent SS (suspended solids), improving effluent quality standards. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the flat sheet packing material for supporting graphene provided in Example 1;

[0027] Figure 2 A schematic diagram of the flat sheet packing material for supporting graphene provided in Example 2;

[0028] Figure 3 The results of microscopic examination of the biofilm formation on the packing material in Example 2 are shown.

[0029] Figure 4 The results of microscopic examination of the biofilm formation on the packing material in Comparative Example 2 are shown.

[0030] Figure 5 The results of microscopic examination of the biofilm formation on the packing material in Example 1 are shown.

[0031] Figure 6 The results of microscopic examination of the attached membrane of the packing material in Comparative Example 1 are shown.

[0032] Icons: 1- Flat sheet filler substrate; 2- Graphene film; 3- Honeycomb recessed structure; 4- Blended graphene flat sheet filler substrate. Detailed Implementation

[0033] The embodiments and examples of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments and examples are for illustrative purposes only and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0034] In a first aspect, the present invention provides a flat sheet filler loaded with graphene, comprising a flat sheet filler substrate and positively charged modified graphene oxide, wherein the positively charged modified graphene oxide is loaded on the flat sheet filler substrate.

[0035] The preparation method of the positively charged modified graphene oxide includes:

[0036] Positively charged modified graphene oxide was prepared by dispersing graphene oxide in a solvent, mixing it with iron salt, and then reacting it with gamma rays. This method achieves positive charge modification by loading iron ions onto the surface of graphene oxide.

[0037] The graphene-loaded flat packing provided by this invention, through the positively charged modified graphene oxide, can attract the dominant negatively charged microbial community in wastewater treatment. Simultaneously, the surface of the flat packing can be configured with a honeycomb-like concave structure, increasing the specific surface area of ​​the packing and providing an optimal environment and space for microbial implantation, greatly promoting biofilm formation. The flat packing has high permeability, does not obstruct the flow pattern in the wastewater treatment process, ensures uniform mixing of sludge and water without short-circuiting, and can withstand various load impacts, making it suitable for treating different types of wastewater. The flat packing also has a filtration function, and can be used as the end-stage material in biological wastewater treatment sedimentation tanks to filter effluent SS (suspended solids), improving effluent quality standards.

[0038] In some alternative embodiments, the solvent includes, but is not limited to, tetrahydrofuran, polyethylene, or ethylene-methyl acrylate copolymer.

[0039] In some alternative embodiments, the iron salt includes, but is not limited to, ferrous sulfate, or other iron salts known to those skilled in the art may also be selected;

[0040] During the reaction, the final concentration of the iron salt can be, for example, but not limited to, 1 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, or 10 wt%.

[0041] In some alternative embodiments, the radiation dose of the gamma rays may be, for example, but not limited to, 10 kGy, 20 kGy, 40 kGy, 60 kGy, 80 kGy or 100 kGy.

[0042] Further optimization and adjustment of reaction conditions enable better achievement of positive charge modification of graphene oxide.

[0043] In some alternative embodiments, the positively charged modified graphene oxide is loaded onto a flat filler substrate in the form of a graphene film or graphene fibers.

[0044] In some alternative embodiments, the graphene film is a substrate material on which the positively charged modified graphene oxide is sprayed.

[0045] The graphene film is loaded onto the flat filler substrate by means of stitching or bonding.

[0046] In some optional embodiments, the graphene film is prepared by spraying positively charged modified graphene oxide onto a preheated substrate material to obtain a graphene film.

[0047] In some optional embodiments, the graphene film is elongated, with a thickness of 0.5-2 mm and a width of 1-10 cm, and includes at least two graphene films with a spacing of 1-10 cm between adjacent graphene films.

[0048] In some alternative embodiments, the graphene fiber is a fiber filament of a substrate material doped with the positively charged modified graphene oxide;

[0049] The method of loading graphene fibers onto a flat sheet filler substrate includes: blending graphene fibers with a flat sheet filler substrate.

[0050] In some optional embodiments, the graphene fiber is prepared by mixing positively charged modified graphene oxide into a preheated substrate material and then preparing graphene fiber through a spinneret.

[0051] In some alternative embodiments, the graphene fibers have a diameter of 10-50 μm and a length of 10-100 mm;

[0052] In some alternative embodiments, the graphene fiber content in the flat packing is 2%-30% by mass.

[0053] In some alternative embodiments, the substrate material includes PP or PE (polyethylene).

[0054] In some alternative embodiments, the flat sheet filler substrate is primarily made of at least one blend of polypropylene, PP, ES, or polyester.

[0055] In some alternative embodiments, the thickness of the blended flat packing is 1-3 mm, and the air permeability reaches 200-1000 L / m. 2 / S, permeability reaches 500-3000 L / h / m 2 The filtration accuracy is 50-500μm;

[0056] In some alternative embodiments, the surface of the flat filler substrate has a honeycomb-like recessed structure.

[0057] By incorporating a honeycomb-like recessed structure, the specific surface area of ​​the flat packing can be increased. For example, the honeycomb-like recessed structure can increase the specific surface area of ​​the flat packing to 500-5000 m². 2 / m 3 .

[0058] Secondly, the present invention provides the application of the above-mentioned graphene-loaded flat packing material in wastewater treatment.

[0059] The graphene-loaded flat packing material provided by this invention has good biofilm formation effect and can be used for wastewater treatment.

[0060] The present invention will be further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0061] Example 1

[0062] A type of graphene-loaded flat sheet filler, such as Figure 1 As shown, it includes a flat filler substrate 1 and a graphene film 2;

[0063] Among them, the flat filler substrate 1 is mainly made of PP and ES blend, with a thickness of 2mm and an air permeability of 500L / m. 2 / S, water permeability reaches 2000L / h / m 2 The filtration accuracy is 200μm, and the surface is provided with a honeycomb-shaped recessed structure 3.

[0064] The graphene film 2 is a strip with a thickness of 1 mm and a width of 5 cm. The adjacent graphene films are spaced 5 cm apart and are loaded onto the flat filler substrate 1 by stitching.

[0065] The preparation method of graphene film 2 is as follows:

[0066] Step 1. Preparation of positively charged modified graphene oxide:

[0067] Graphene oxide was dispersed in tetrahydrofuran to obtain a graphene oxide colloidal solution. The graphene oxide colloidal solution was mixed with ferrous sulfate, with a final ferrous sulfate concentration of 2 wt%. After irradiation with γ-rays at a radiation dose of 60 kGy, positively charged modified graphene oxide was obtained.

[0068] Step 2. Preparation of graphene film 2:

[0069] The solution containing positively charged modified graphene oxide obtained in step 1 was uniformly sprayed onto a preheated PP substrate to prepare graphene film 2.

[0070] Example 2

[0071] A type of graphene-loaded flat sheet filler, such as Figure 2 As shown, it includes a blended graphene flat sheet filler substrate 4;

[0072] Among them, the blended graphene flat filler substrate 4 is mainly made of PP, ES and graphene fiber (the graphene fiber has a diameter of 30μm, a length of 50mm, and a mass ratio of 10%), with a thickness of 2mm and an air permeability of 600L / m. 2 / S, water permeability reaches 2500L / h / m 2 The filtration accuracy is 300μm, and the surface is provided with a honeycomb-shaped recessed structure 3.

[0073] The preparation method of graphene fiber is as follows:

[0074] Step 1. Preparation of positively charged modified graphene oxide:

[0075] Graphene oxide was dispersed in tetrahydrofuran to obtain a graphene oxide colloidal solution. The graphene oxide colloidal solution was mixed with ferrous sulfate, with a final ferrous sulfate concentration of 5 wt%. After irradiation with γ-rays at a radiation dose of 20 kGy, positively charged modified graphene oxide was obtained.

[0076] Step 2. Preparation of graphene fibers:

[0077] The solution containing positively charged modified graphene oxide obtained in step 1 is uniformly mixed in preheated PP substrate material, and graphene fibers are prepared by spinneret.

[0078] Comparative Example 1

[0079] A sheet filler loaded with graphene differs from Example 1 in that the positively charged modified graphene oxide is prepared as follows:

[0080] Graphene oxide was dispersed in tetrahydrofuran to obtain a graphene oxide colloidal solution. The graphene oxide colloidal solution was mixed with magnesium sulfate, with a final magnesium sulfate concentration of 2 wt%. After irradiation with γ-rays at a radiation dose of 60 kGy, positively charged modified graphene oxide was obtained.

[0081] Comparative Example 2

[0082] A graphene-loaded flat sheet filler differs from Example 1 in that positively charged modified graphene oxide is replaced with an equal amount of graphene oxide.

[0083] Experimental Example 1

[0084] A rural integrated wastewater treatment plant has a treatment capacity of 200 tons / day. The treatment process used in the plant is A. 2 The process involves an anaerobic, anoxic, and aerobic sedimentation tank, with the effluent meeting the Class A standard of the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002). To ensure stable effluent quality, the combined packing material of the equipment was replaced with the flat packing material of Example 1 of this invention. After only 10 days of commissioning, the effluent already met the effluent standards, significantly reducing the process commissioning time.

[0085] Experimental Example 2

[0086] A rural integrated wastewater treatment plant has a treatment capacity of 100 tons / day. The treatment process is AOAO + secondary sedimentation tank. The total nitrogen concentration effluent discharge standard is 15 mg / L, and the COD concentration effluent discharge standard is 50 mg / L. Due to large fluctuations in the influent COD concentration, which ranges from a maximum of over 1200 mg / L to a minimum of only 100 mg / L, the packing material was replaced from the traditional combined packing material to the flat packing material of Example 2 of this invention to mitigate water quality shock loads. Within just 6 days of the modification, a large number of microorganisms were found attached to the surface of the flat packing material. Microscopic examination revealed numerous indicator microorganisms indicating good effluent quality. The overall effluent from the equipment stabilized and met the standards, and the impact of water quality fluctuations on the equipment's effluent was significantly reduced. Simultaneously, a flat packing material made using the same method and without modified graphene oxide attachment (Comparative Example 2) was suspended at the same location in the tank. Within 7 days, the biomass was measured according to the biomass determination method specified in the "HJ 2009-2011 Technical Specification for Biological Contact Oxidation Wastewater Treatment Engineering". The biomass attached to the flat packing material of this invention exceeded 110 g / m³. 2 The biomass attached to the flat packing material using ordinary graphene oxide is less than 30 g / m². 2 Microscopic examination was performed on Example 2 and Comparative Example 2, and the results are as follows: Figure 3 and Figure 4 As shown in the figure, microscopic examination clearly shows that the plate packing material of the present invention indicates a large number of microorganisms, and the effect is significant.

[0087] Experimental Example 3:

[0088] A rural integrated wastewater treatment plant has a treatment capacity of 100 tons / day. The treatment process is AOAO + secondary sedimentation tank. The total nitrogen concentration effluent discharge standard is 15 mg / L, and the COD concentration effluent discharge standard is 50 mg / L. Due to large fluctuations in the influent COD concentration, which ranges from a maximum of over 1200 mg / L to a minimum of only 100 mg / L, the plant was modified using the technology of this invention to mitigate water quality shock loads. The packing material was replaced with the flat plate packing material of Example 1 of this invention. Within just 6 days of the modification, a large number of microorganisms were found attached to the surface of the flat plate packing material. Microscopic examination revealed numerous indicator microorganisms indicating good effluent quality. The overall effluent from the plant consistently met the standards, and the impact of water quality fluctuations on the effluent was significantly reduced. To compare the biofilm formation effect of flat plate packing materials made using different methods, a piece of modified graphene oxide-attached flat plate packing material (Comparative Example 1) was suspended at the same location in the tank. Within 7 days, the biomass was measured according to the method specified in the "HJ 2009-2011 Technical Specification for Biological Contact Oxidation Wastewater Treatment Engineering". The biomass attached to the flat plate packing in Example 1 of this invention exceeded 110 g / m³. 2 In Comparative Example 1, the biomass attached to the flat substrate was only 70 g / m². 2 Microscopic examination was performed on Example 1 and Comparative Example 1, and the results are as follows: Figure 5 and Figure 6 As shown in the microscopic comparison, it can be clearly seen that the plate packing material of the present invention indicates more microorganisms, while the plate packing material loaded with magnesium ions is loaded with algae, and its biochemical effect is not as good as that of the plate packing material of the present invention.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flat sheet filler loaded with graphene, characterized in that, It includes a flat sheet filler substrate and positively charged modified graphene oxide, wherein the positively charged modified graphene oxide is loaded on the flat sheet filler substrate; The preparation method of the positively charged modified graphene oxide includes: Positively charged modified graphene oxide was prepared by dispersing graphene oxide in a solvent, mixing it with iron salt, and then reacting it with gamma rays. The solvent includes tetrahydrofuran; The iron salt includes ferrous sulfate; During the reaction, the final concentration of the iron salt is 1wt%-10wt%; The radiation dose of the gamma rays is 10-100 kGy.

2. The flat sheet packing material supported on graphene according to claim 1, characterized in that, The positively charged modified graphene oxide is loaded onto a flat filler substrate in the form of graphene film or graphene fiber.

3. The graphene-supported flat packing material according to claim 2, characterized in that, The graphene film is a substrate material on which the positively charged modified graphene oxide is sprayed. The graphene film is loaded onto the flat filler substrate by means of stitching or bonding.

4. The graphene-supported flat packing material according to claim 2, characterized in that, The graphene fiber is a fiber filament of a substrate material doped with the positively charged modified graphene oxide; The method of loading graphene fibers onto a flat sheet filler substrate includes: blending graphene fibers with a flat sheet filler substrate.

5. The flat sheet filler for supporting graphene according to claim 3 or 4, characterized in that, The substrate material includes PP or PE.

6. The flat sheet packing material supported on graphene according to claim 1, characterized in that, The flat packing substrate is mainly made of at least one blend of polypropylene, PP, ES or polyester. And / or, the surface of the flat filler substrate has a honeycomb-like recessed structure.

7. The application of the graphene-loaded flat packing material according to any one of claims 1-6 in wastewater treatment.

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