Electrocoppering waste liquid-based preparation method of graphene oxide by electrochemical process

Abstract

The invention discloses a method for preparing graphene oxide by an electrochemical process based on electroplating copper waste liquid. The method comprises the following steps: S1, collecting the electroplating copper waste liquid and performing pretreatment; s2, the pretreated electroplating copper waste liquid serves as basic liquid, and copper-containing mixed liquid is prepared; s3, taking a porous graphite electrode as a working electrode, wrapping the working electrode with a filter screen, and taking the copper-containing mixed solution obtained in the step S2 as an electrolyte to construct an electrochemical reaction system for electrochemical reaction, so that the surface of the porous graphite electrode is subjected to oxidation reaction to generate graphene oxide; and S4, collecting the graphene oxide on the surface of the porous graphite electrode and in the filter screen, and performing purification and drying treatment to obtain a final graphene oxide product. The scheme provided by the invention has the following advantages of remarkable environmental friendliness, great improvement of cost effectiveness, controllability and optimization of product performance, process simplification and operation convenience, promotion of sustainable development, and good market application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of graphene oxide preparation, and in particular to an electrochemical method for preparing graphene oxide based on copper electroplating waste liquid. Background Art

[0002] As a star member of the two-dimensional material family, graphene oxide has shown great application potential in energy storage, catalysis, sensors and composite materials due to its excellent electrical, thermal and mechanical properties. Traditionally, the Hummers method and the Staudenmaier method are two classic methods for preparing graphene oxide. They act on graphite with strong oxidants such as concentrated nitric acid, concentrated sulfuric acid and potassium permanganate to promote the oxidation of graphite interlayers and insert oxygen-containing functional groups, thereby realizing the transformation of graphite to graphene oxide. However, these methods are not only dangerous in operation and produce a large amount of toxic waste liquid, but also have high energy consumption and high cost, which runs counter to the current concept of sustainable development and environmental protection.

[0003] In recent years, with the growing demand for environmentally friendly preparation methods, researchers have been committed to developing new green preparation technologies. Among them, the electrochemical method has attracted widespread attention due to its environmental friendliness, simple operation and strong adjustability. Although some studies have explored the use of electrochemical methods to prepare graphene oxide, most studies still rely on synthetic electrolytes or specific additives, and the resource utilization of waste liquid is not sufficient. For example, the document "Research Progress in the Preparation of Graphene Oxide by Electrochemical Method" (Journal of Materials Chemistry A, 2018, 6, 16779-16794) reviews the latest progress in electrochemical methods, pointing out that although this method shows advantages in controlling product structure, how to efficiently use industrial waste liquid as a resource, especially electroplating waste liquid containing heavy metal ions, is still an underdeveloped field.

[0004] "Research Progress in Electrochemical Preparation of Graphene Oxide", Journal of Materials Chemistry A, 2018, 6, 16779-16794. This paper reviews various strategies for electrochemical preparation of graphene oxide, including the effects of electrolyte type, electrode material selection and operating parameters on the product, but does not directly explore the possibility of using electroplating waste liquid as an electrolyte.

[0005] The traditional electrochemical method for preparing graphene oxide usually involves applying an external electric field in an electrolyte containing a certain concentration of oxidant to induce an oxidation reaction on the surface of a graphite electrode to form graphene oxide. In this process, the selection of electrode materials (such as graphite, platinum, etc.), electrolyte components (such as sulfuric acid, phosphate buffer, etc.) and electrochemical parameters (voltage, current density) are key factors affecting the quality of the product.

[0006] Most existing electrochemical methods rely on synthetic electrolytes and fail to effectively utilize industrial waste. At the same time, there is still room for improvement in the structural control of graphene oxide and the improvement of product purity, and there is insufficient assessment of cost-effectiveness and environmental impact in large-scale production.

[0007] In summary, the problems and defects of the prior art include:

[0008] 1. Environmental hazards and high costs: Traditional graphene oxide preparation methods, such as the Hummers method and the Staudenmaier method, rely on strong acids and strong oxidants. The use of these substances not only poses a threat to the health of operators, but also causes long-term environmental pollution due to the discharged waste liquid, requiring expensive post-processing steps to mitigate environmental impact. In addition, the cost of chemical raw materials in such methods is high, which increases the overall preparation cost.

[0009] 2. Waste of resources and environmental pollution: Chemical precipitation or electrolysis is generally used to treat electroplating copper wastewater. Although it can remove some pollutants, it often fails to effectively recycle and utilize the copper resources, resulting in waste of resources. At the same time, the treated water may still contain other harmful substances, posing a potential risk to the environment.

[0010] 3. Technical limitations: Existing electrochemical methods often require specific electrolytes and additives when preparing graphene oxide, which limits their universality and flexibility, and lacks effective strategies for structural control and purity improvement of the products. Summary of the invention

[0011] The technical problem to be solved by the present invention is to provide a method for preparing graphene oxide by an electrochemical method based on electroplating copper waste liquid in view of the deficiencies in the above-mentioned prior art. The electrochemical method for preparing graphene oxide by an electrochemical method based on electroplating copper waste liquid proposed by the present invention aims to overcome the environmental and cost problems in the prior art. Through the waste resource approach, it not only solves the problem of treating electroplating waste liquid, but also opens up a new path for green and low-cost preparation of graphene oxide. The scheme provided by the present invention has the following characteristics: 1. Environmentally friendly: directly using electroplating copper waste liquid as an electrolyte, avoiding the use of strong acid and strong oxidant in traditional methods, greatly reducing environmental pollution. 2. Resource recycling: through the electrochemical process, not only graphene oxide is prepared, but also copper metal is deposited and recovered at the cathode, realizing the effective resource utilization of electroplating waste liquid. 3. Cost reduction: abandoning expensive chemical reagents, using industrial waste as raw materials, greatly reducing production costs. 4. Controllable performance: by adjusting electrochemical conditions, such as voltage, current density and reaction time, the oxidation degree and structural characteristics of graphene oxide can be effectively controlled to improve its adaptability in specific application fields. The technical solution of the present invention not only solves the environmental and cost problems of the prior art, but also realizes waste resource utilization, reflecting the important contribution of technological innovation to promoting sustainable development.

[0012] To achieve the above object, the technical solution adopted by the present invention is: the present invention provides an electrochemical method for preparing graphene oxide based on electroplating copper waste liquid, characterized in that it comprises the following steps:

[0013] S1, collecting and pre-treating electroplating copper waste liquid;

[0014] S2, using the pretreated copper electroplating waste liquid obtained in step S1 as a base liquid to prepare a copper-containing mixed liquid;

[0015] S3, using the porous graphite electrode as the working electrode and wrapping it with a filter screen, and using the copper-containing mixed solution obtained in step S2 as the electrolyte, constructing an electrochemical reaction system, and performing an electrochemical reaction to cause an oxidation reaction to occur on the surface of the porous graphite electrode to produce graphene oxide;

[0016] S4. Collecting graphene oxide on the surface of the porous graphite electrode and in the filter screen, purifying and drying the graphene oxide to obtain the final graphene oxide product.

[0017] Preferably, the pretreatment in step S1 includes: adjusting the copper ion concentration in the electroplating copper waste liquid, filtering and removing impurities, and adjusting the pH value.

[0018] Preferably, step S1 specifically comprises:

[0019] S1-1, collecting electroplating copper waste liquid containing copper ions and other metal impurity ions, the copper ion concentration is 0.1-0.5M, and the concentration of other metal impurity ions does not exceed 0.1M;

[0020] S1-2, adjusting the copper ion concentration in the electroplating copper waste liquid to 0.2-0.3M;

[0021] S1-3, filter using a 0.45 μm pore size filter membrane and discard the filter residue;

[0022] S1-4, adjusting the pH value of the filtrate obtained in step S1-3 to 2-5 to obtain pretreated electroplating copper waste liquid.

[0023] Preferably, step S2 specifically comprises: adding 0.05-0.2% by weight of hydrogen peroxide to the pretreated electroplating copper waste liquid to obtain a copper-containing mixed liquid.

[0024] Preferably, step S3 specifically comprises:

[0025] A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system;

[0026] At room temperature, a constant voltage of 3-7 V was applied to the porous graphite electrode, and the current density was controlled at 1-10 mA / cm 2 Within the range, electrochemical reaction is carried out and the reaction time is controlled to be 1-24h.

[0027] Preferably, step S3 specifically comprises:

[0028] A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system;

[0029] At room temperature, a constant voltage of 5 V was applied to the porous graphite electrode, and the current density was controlled at 10 mA / cm 2 Within this range, electrochemical reaction was carried out and the reaction time was controlled to be 15h.

[0030] Preferably, the porous graphite electrode is prepared by the following method:

[0031] The waste graphite thermal conductive film is crushed into graphite powder, which is then mixed with a polytetrafluoroethylene binder, pressed into shape, and then sintered at 400-600°C for 1-4 hours to obtain a porous graphite electrode.

[0032] Preferably, the porous graphite electrode is prepared by the following method: graphite thermal conductive film waste is crushed into graphite powder with a flake diameter of 10-100 μm, then mixed with polytetrafluoroethylene binder at a mass ratio of 9:1, pressed into shape, sintered at 500°C for 2 hours, and cooled to room temperature to obtain a porous graphite electrode.

[0033] Preferably, step S4 is specifically:

[0034] After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and the porous graphite electrode and the filter are cleaned with deionized water. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned. After the cleaning is completed, the porous graphite electrode and the filter are taken out, the obtained cleaning liquid is collected, centrifuged, the solid product is collected, and dried to obtain the final graphene oxide product.

[0035] Preferably, step S4 is specifically:

[0036] After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and they are washed with deionized water. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned for 15-60 minutes at a frequency of 20-60 kHz. After cleaning, the porous graphite electrode and the filter are taken out, the cleaning liquid is collected, and the cleaning liquid is centrifuged at 2500-10000 rpm for 5-20 minutes. The solid product is collected and dried to obtain the final graphene oxide product.

[0037] The beneficial effects of the present invention are:

[0038] The present invention provides a method for preparing graphene oxide by an electrochemical method based on electroplating copper waste liquid, which has at least the following advantages:

[0039] Significant environmental friendliness: This invention directly uses electroplating copper waste liquid as electrolyte, which not only effectively solves the environmental pollution problem caused by the use of strong acid and strong oxidant in the preparation of traditional graphene oxide, but also realizes the resource utilization of electroplating industry waste liquid, greatly reducing the burden on the environment. This improvement is due to the unique mechanism of electrochemical method, which avoids the use of harmful chemical reagents and reflects the green transformation of technical means.

[0040] Significantly improved cost-effectiveness: Compared with traditional methods such as the Hummers method and the Staudenmaier method, the present invention significantly reduces production costs. By using industrial waste liquid as a reaction medium, the cost of purchasing expensive chemical reagents is eliminated. At the same time, the copper recovery process further increases the economic value, achieving a win-win situation in economic and environmental benefits. This cost saving is attributed to the present invention's creative waste liquid reuse strategy and simplified and efficient electrochemical process.

[0041] Controllability and optimization of product performance: The present invention can better control the oxidation degree and structural characteristics of graphene oxide by precisely regulating electrochemical conditions (such as voltage, current density and reaction time), which is difficult to achieve with traditional methods. This means that process parameters can be flexibly adjusted according to different application scenarios to produce graphene oxide that meets specific requirements, such as higher conductivity or stronger mechanical strength.

[0042] Process simplification and operational convenience: The electrochemical method of the present invention is simpler than the traditional chemical method in preparation process, and the operation is easy to standardize and automate, which is suitable for large-scale industrial production. The construction and operation of the electrochemical device are relatively simple, which reduces the complex chemical steps, reduces the requirements for professional operating skills, and improves production efficiency.

[0043] Promoting sustainable development: This invention realizes the transformation from waste to high-value materials, promotes the development of circular economy, and provides a model for the resource utilization of other industrial waste liquids. Through technological innovation, this invention not only solves a single environmental problem, but also opens up a new path for the integration of material science and environmental protection technology, and promotes the realization of sustainable development goals.

[0044] The above beneficial effects directly correspond to the innovative points adopted in the technical solution of the present invention, such as using electroplating copper waste liquid as electrolyte, optimizing electrochemical conditions, efficient product recovery and purification steps, etc. These technical means jointly solve the problems of environmental protection, cost, performance control and process complexity in the prior art, reflecting the significant advantages of the present invention in technological progress and social benefits. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0046] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0047] The test methods used in the following examples are conventional methods unless otherwise specified. The materials and reagents used in the following examples are all commercially available unless otherwise specified. In the following examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if the manufacturer is not specified, are all conventional products that can be purchased commercially.

[0048] The present invention provides a method for preparing graphene oxide by an electrochemical method based on electroplating copper waste liquid, comprising the following steps:

[0049] S1, collecting and pre-treating electroplating copper waste liquid;

[0050] S2, using the pretreated copper electroplating waste liquid obtained in step S1 as a base liquid to prepare a copper-containing mixed liquid;

[0051] S3, using a porous graphite electrode as a working electrode and wrapping it with a filter (the filter bag has enough space so as not to affect subsequent reactions), and using the copper-containing mixed solution obtained in step S2 as an electrolyte, constructing an electrochemical reaction system, and performing an electrochemical reaction to cause an oxidation reaction to occur on the surface of the porous graphite electrode to produce graphene oxide;

[0052] S4. Collect the graphene oxide on the surface of the porous graphite electrode and the filter, purify and dry it to obtain the final graphene oxide product. Then calculate the consumption of the graphite electrode, the final yield, and test the graphene oxide content.

[0053] In a preferred embodiment, the pretreatment in step S1 includes: adjusting the copper ion concentration in the electroplating copper waste liquid, filtering and removing impurities, and adjusting the pH value.

[0054] In a preferred embodiment, step S1 is specifically as follows:

[0055] S1-1, collecting electroplating copper waste liquid containing copper ions and other metal impurity ions from the electroplating industry, the copper ion concentration is 0.1-0.5M, and the concentration of other metal impurity ions (such as nickel, zinc ions, etc.) does not exceed 0.1M; more preferably, the content of organic matter and inorganic salts in the electroplating copper waste liquid is not higher than 5wt%;

[0056] S1-2, adjusting the copper ion concentration in the electroplating copper waste liquid to 0.2-0.3M;

[0057] In the present invention, the copper ion concentration in the electroplating solution is accurately measured before use. This step is completed by using a precision analytical instrument (such as atomic absorption spectrometry AAS or inductively coupled plasma mass spectrometry ICP-MS) to ensure that the waste liquid can be adjusted according to the actual measured value to achieve the ideal reaction conditions. According to the test results, the copper ion concentration in the waste liquid is adjusted to the optimal range, i.e., 0.2-0.3M, by appropriate dilution or other means (such as evaporating part of the waste liquid), laying the foundation for the efficient conduct of the subsequent electrochemical process.

[0058] S1-3, filter using a 0.45 μm pore size filter membrane and discard the filter residue;

[0059] In a preferred embodiment, a polytetrafluoroethylene (PTFE) filter membrane is used;

[0060] S1-4, adjusting the pH value of the filtrate obtained in step S1-3 to 2-5 to obtain pretreated electroplating copper waste liquid.

[0061] In the present invention, the pH value of the waste liquid needs to be adjusted to a suitable range, i.e., pH 2-5. The neutral acid environment is to more effectively promote the occurrence of electrochemical reactions and control the oxidation process. This interval is more focused on accelerating the formation of graphene oxide in a neutral acid environment. It is also considered that in this pH value interval, it may be more conducive to the stability of copper ions and subsequent recycling. In a preferred embodiment, this accurate pH value adjustment is achieved by adding an appropriate amount of dilute sulfuric acid (H2SO4) to ensure the stability and efficiency of the electrochemical reaction environment. The specific adjustment method is as follows: use a pH meter to monitor the pH value of the waste liquid in real time, and gradually drip 1M of dilute sulfuric acid until the pH value reaches the range of 2-5.

[0062] In a preferred embodiment, step S2 is specifically: adding 0.05-0.2% by weight of hydrogen peroxide to the pretreated electroplating copper waste liquid to obtain a copper-containing mixed solution. By adding a certain proportion of hydrogen peroxide (H2O2) to enhance the oxidation effect, the optimal conditions of the electroplating waste liquid in the electrochemical reaction are ensured, laying a solid foundation for the efficient preparation of high-quality graphene oxide. In a more preferred embodiment, 0.1% by weight of hydrogen peroxide is added.

[0063] In a preferred embodiment, step S3 is specifically as follows:

[0064] A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter (the filter bag has enough space so as not to affect the subsequent reaction), a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system;

[0065] At room temperature, a constant voltage of 3-7 V was applied to the porous graphite electrode, and the current density was controlled at 1-10 mA / cm 2 The electrochemical reaction is carried out within the range of 1-24 hours. The electrochemical reaction process promotes oxidation reaction on the surface of the porous graphite electrode to form a graphene oxide layer, accompanied by reduction deposition of copper ions in the cathode area, effectively reducing the concentration of copper ions in the waste liquid and achieving waste liquid purification and resource recovery.

[0066] In a more preferred embodiment, step S3 is specifically:

[0067] A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter (the filter bag has enough space so as not to affect the subsequent reaction), and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system;

[0068] At room temperature, a constant voltage of 5 V was applied to the porous graphite electrode, and the current density was controlled at 10 mA / cm 2 Within the range, electrochemical reaction is carried out and the reaction time is controlled to be 1h.

[0069] In a preferred embodiment, the porous graphite electrode is prepared by the following method:

[0070] The waste graphite thermal conductive film is crushed into graphite powder, which is then mixed with a polytetrafluoroethylene binder, pressed into shape, and then sintered at 400-600°C for 1-4 hours to obtain a porous graphite electrode.

[0071] In a more preferred embodiment, the porous graphite electrode is prepared by the following method: the waste graphite thermal conductive film is crushed into graphite powder with a flake diameter of 10-100 μm, and then mixed with a polytetrafluoroethylene binder in a mass ratio of 9:1. After pressing and molding, it is sintered at 500°C for 2 hours and cooled to room temperature to obtain a porous graphite electrode.

[0072] In a preferred embodiment, step S4 is specifically as follows:

[0073] After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and they are washed with deionized water to remove the residual waste liquid on the surface of the electrode. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned. After the cleaning is completed, the porous graphite electrode and the filter are taken out, the obtained cleaning liquid is collected, and centrifuged to remove impurities attached to the surface of the graphene oxide. The solid product is collected and dried (placed in a vacuum freeze-drying device for drying, or dried under natural conditions) to obtain the final graphene oxide product.

[0074] In a more preferred embodiment, step S4 is specifically:

[0075] After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and they are washed with deionized water. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned for 15-60 minutes at a frequency of 20-60 kHz. After the cleaning is completed, the porous graphite electrode and the filter are taken out, the obtained cleaning liquid is collected, and the solid product is centrifuged at 2500-10000 rpm for 5-20 minutes. The solid product is collected and dried to obtain the final graphene oxide product.

[0076] The present invention realizes the method for preparing graphene oxide by electrochemical method using electroplating copper waste liquid by at least the following technical optimization and improvement:

[0077] Direct utilization and conversion of electroplating waste liquid: The present invention creatively uses electroplating copper waste liquid as the electrolyte for electrochemical reactions, which not only solves the problem of dependence on environmentally harmful chemicals in traditional graphene oxide preparation, but also realizes the efficient resource utilization of industrial waste liquid, converting the waste liquid that originally needed to be treated into valuable preparation raw materials.

[0078] Precise control of electrochemical conditions: By finely adjusting the conditions of the electrochemical reaction, including voltage, current density and reaction time, the present invention can effectively control the generation process of graphene oxide and ensure the controllability of the oxidation degree and product quality. The optimization of such conditions is the key to achieving the preparation of high-quality graphene oxide.

[0079] Integrated resource recovery and material synthesis: During the electrochemical oxidation process, graphene oxide is formed on the surface of the graphite electrode while copper ions are deposited as metallic copper in the cathode area, achieving the simultaneous recovery of metal resources. This simultaneous resource recovery and material synthesis mechanism greatly improves the economic and environmental benefits of the entire process.

[0080] Efficient purification and recovery technology: Ultrasonic cleaning combined with physical methods such as centrifugal separation, rather than chemical reagents, is used to recover graphene oxide from graphite electrodes. This not only simplifies the post-processing steps and reduces secondary pollution, but also maintains the high purity and good dispersibility of graphene oxide, providing high-quality materials for subsequent applications.

[0081] Balance between environment and economic benefits: The present invention proposes a method for preparing graphene oxide that is both environmentally friendly and economical by comprehensively considering environmental impact and economic benefits. By reducing the use of harmful chemicals, lowering processing costs, and recovering valuable metals, a win-win situation of environmental friendliness and economic benefits is achieved.

[0082] In summary, the outstanding improvements of the present invention are not only reflected in its original electroplating waste liquid utilization strategy, but also include the precise control of electrochemical conditions, the integrated design of resource recovery and material synthesis, green and efficient post-processing technology, and the balance between environmental protection and economic benefits, which together constitute the technical core and innovative value of the invention.

[0083] The above is the overall concept of the present invention, and detailed embodiments and comparative examples are provided below on the basis of the overall concept of the present invention to further illustrate the present invention.

[0084] The following is a basic example, on which the subsequent examples and comparative examples are based.

[0085] Basic Example

[0086] A method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid comprises the following steps:

[0087] S1. Collect and pre-treat copper electroplating waste liquid:

[0088] Waste liquid containing copper ions and other metal impurities was obtained from the electroplating industry. After testing, the waste liquid components included a copper ion concentration of 0.25M, a total concentration of other metal ions such as nickel and zinc of 0.08M, and an organic and inorganic salt content of 4%.

[0089] Adjusting the copper ion concentration: Atomic absorption spectroscopy (AAS) is used to accurately measure the copper ion concentration in the plating solution. Since the initial copper ion concentration is relatively close to the target value, no major adjustment is required. Only a small amount of deionized water is added for fine-tuning to ensure that the copper ion concentration is stable near the lower limit of the target range, that is, the final copper ion concentration is 0.2M.

[0090] Filter to remove large particles of impurities:

[0091] A polytetrafluoroethylene (PTFE) filter membrane with a pore size of 0.45 μm was selected and the waste liquid was filtered using a vacuum filtration device. During the filtration process, the sealing of the filtration device was ensured to be good to prevent the mixing of external impurities. After filtration, large particle impurities in the waste liquid were effectively removed, providing a clean reaction system for subsequent reactions.

[0092] Adjust pH:

[0093] Use 1M dilute sulfuric acid (H2SO4) as a regulator, use a pH meter to monitor the pH value of the waste liquid in real time, slowly add 1M dilute sulfuric acid, and stir while adding to fully mix the dilute sulfuric acid and the waste liquid; during the addition process, closely observe the changes in the pH meter readings. When the pH value reaches a value close to 2, slow down the dropping speed and finally accurately adjust the pH value to 2.1.

[0094] S2. Using the pretreated copper electroplating waste liquid obtained in step S1 as a base liquid, adding 0.1 wt% of hydrogen peroxide (H2O2) to obtain a copper-containing mixed liquid.

[0095] S3, using a porous graphite electrode as a working electrode and wrapping it with a 500-mesh bag filter (the filter bag has enough space so as not to affect the subsequent reaction), a platinum sheet as a counter electrode, a saturated calomel electrode as a reference electrode, and the copper-containing mixed solution obtained in step S2 as an electrolyte to construct an electrochemical reaction system;

[0096] At room temperature (25°C), a constant voltage of 3-7V was applied to the porous graphite electrode, and the current density was controlled at 1-10mA / cm 2 Within the range, electrochemical reaction is carried out and the reaction time is controlled to be 1-24h.

[0097] S4. After the electrochemical reaction is completed, the porous graphite electrode is taken out and the filter is removed. The porous graphite electrode and the filter are washed with deionized water for multiple times. The porous graphite electrode and the filter are then placed in deionized water for ultrasonic cleaning for 30 minutes. The ultrasonic cleaning frequency is 40kHz. After the cleaning is completed, the porous graphite electrode is taken out, the obtained cleaning liquid is collected, and the solid product is collected by centrifugation at 5000rpm for 10 minutes. The solid product is vacuum freeze-dried to obtain the final graphene oxide product. The consumption of the graphite electrode is calculated, and the final yield is calculated: (mass of graphene oxide product / mass of graphite electrode consumption) × 100%; and the purity of graphene oxide is tested.

[0098] Among them, the porous graphite electrode is prepared by the following method: the waste graphite thermal conductive film with a thickness of 12-70μm is crushed into graphite powder with a flake diameter of 10-100μm, and then mixed with a polytetrafluoroethylene binder at a mass ratio of 9:1, pressed into shape, sintered at 500°C for 2 hours, and cooled to room temperature to obtain a porous graphite electrode.

[0099] Example Group 1 Voltage Impact Analysis Experiment

[0100] Example 1: The voltage was set to 3 V and the current density was 5 mA / cm 2 The reaction time was 12 hours. The results showed that the graphene oxide layer formed was thin, the copper ion reduction deposition rate was moderate, the yield of the graphene oxide product was 50%, and the purity reached 85%.

[0101] Example 2: The voltage is increased to 5 V (preferred value) and the current density is 5 mA / cm 2 , the reaction time is 12 hours. The thickness of the graphene oxide layer increases, the copper recovery increases, the product yield increases to 70%, and the purity reaches 90%.

[0102] Example 3: The voltage was further increased to 7 V and the current density was 5 mA / cm 2 , the reaction time was 12 hours. It was found that although the copper recovery rate was further improved, the structural integrity of graphene oxide was damaged, the yield dropped to 60%, and the purity was maintained at 88%.

[0103] Example Group 2 Current Density Impact Analysis Experiment

[0104] Example 4: The voltage was maintained at 5 V and the current density was set to 1 mA / cm 2 The results showed that the graphene oxide grew slowly and had a low yield of 35%, but a high purity of 92%.

[0105] Example 5: At 5V, the current density was adjusted to 10mA / cm 2 The reaction time was 12 hours. The yield was significantly increased to 70%, and the purity was maintained at 90%.

[0106] Example 6: At 5V, the current density increased to 20mA / cm 2 , the reaction time was 12 h. Although the yield was slightly improved to 75%, the purity decreased to 88%, indicating that too high current density may lead to increased side reactions.

[0107] Example Group 3: Experiment on the effect of reaction time

[0108] Example 7: At 5V, 10mA / cm 2 At the current density of 1.34 Å, when the reaction time was shortened to 5 h, the yield was only 45%, indicating that the oxidation was not sufficient.

[0109] Example 8: At 5V, 10mA / cm 2 Under the current density, the reaction time was 15 hours, the yield increased to 80%, and the purity reached 92%, indicating that sufficient reaction time is conducive to the complete formation of graphene oxide.

[0110] Example 9: At 5V, 10mA / cm 2 Under the current density, the reaction time was 20 hours, and the yield did not change much, but the purity decreased slightly. This may be because the long reaction time led to an increase in by-products.

[0111] Comparative Example 1

[0112] Although the purity of graphene oxide can reach 95% using the traditional Hummers method, the yield is low (about 30%), and a large amount of toxic chemical reagents are used in the process, which imposes a serious burden on the environment.

[0113] Comparative Example 2

[0114] The only difference from Example 1 is that 0.1% H2O2 is not added in step S2. After measurement and comparison, the yield of graphene oxide in this comparative example is about 30 grams, which is significantly lower than the yield in Example 1. And because no hydrogen peroxide is added, the oxidation effect is relatively weak, and the purity of the product is about 80%, which is also reduced.

[0115] Comparative Example 3

[0116] The only difference from Example 1 is that ordinary graphite electrodes are used instead of homemade porous graphite electrodes. The yield of graphene oxide is about 40 grams, which is lower than that of Example 1. The degree of oxidation is not uniform enough, and the quality and performance of the product are obviously inferior to those of Example 1. At the same time, during the reaction process, ordinary graphite electrodes may have problems such as rapid loss and insufficient stability. After testing, the purity of the product is about 82%.

[0117] The obtained graphene oxide powder was characterized and analyzed. In this comparative example, due to the use of ordinary graphite electrodes, its performance is significantly different from that of the homemade porous graphite electrode in Example 1. The yield of graphene oxide is low, the degree of oxidation is not uniform, and the quality and performance of the product are obviously inferior to those in Example 1. At the same time, during the reaction process, ordinary graphite electrodes may suffer from problems such as rapid loss and insufficient stability.

[0118] The main parameters and product indicators of the above embodiments and comparative examples are summarized in Table 1 below:

[0119] Table 1

[0120]

[0121]

[0122] By comparing the data of the above embodiments, it can be seen that the present invention has a high 2 Under the conditions of current density and reaction time of 15 hours (Example 8), a relatively high graphene oxide yield (80%) and purity (92%) were achieved, while effective utilization of electroplating copper waste liquid and recovery of copper metal were achieved.

[0123] Compared with the traditional method, the present invention not only significantly improves the environmental friendliness and economy, but also maintains the good performance of the product, fully reflecting its technological advancement and practicality.

[0124] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid, characterized in that: The following steps are involved: S1, collecting and pre-treating electroplating copper waste liquid; S2, using the pretreated copper electroplating waste liquid obtained in step S1 as a base liquid to prepare a copper-containing mixed liquid; S3, using the porous graphite electrode as the working electrode and wrapping it with a filter screen, and using the copper-containing mixed solution obtained in step S2 as the electrolyte, constructing an electrochemical reaction system, and performing an electrochemical reaction to cause an oxidation reaction to occur on the surface of the porous graphite electrode to produce graphene oxide; S4. Collecting graphene oxide on the surface of the porous graphite electrode and in the filter screen, purifying and drying the graphene oxide to obtain the final graphene oxide product.

2. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 1, characterized in that: The pretreatment in step S1 includes: adjusting the copper ion concentration in the electroplating copper waste liquid, filtering and removing impurities, and adjusting the pH value.

3. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 2, characterized in that: Step S1 is specifically as follows: S1-1, collecting electroplating copper waste liquid containing copper ions and other metal impurity ions, the copper ion concentration is 0.1-0.5M, and the concentration of other metal impurity ions does not exceed 0.1M; S1-2, adjusting the copper ion concentration in the electroplating copper waste liquid to 0.2-0.3M; S1-3, filter using a 0.45 μm pore size filter membrane and discard the filter residue; S1-4, adjusting the pH value of the filtrate obtained in step S1-3 to 2-5 to obtain pretreated electroplating copper waste liquid.

4. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 1, characterized in that: Step S2 specifically includes: adding 0.05-0.2% by weight of hydrogen peroxide to the pretreated electroplating copper waste liquid to obtain a copper-containing mixed liquid.

5. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 1, characterized in that: Step S3 is specifically as follows: A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system; At room temperature, a constant voltage of 3-7 V was applied to the porous graphite electrode, and the current density was controlled at 1-10 mA / cm 2 Within the range, electrochemical reaction is carried out and the reaction time is controlled to be 1-24h.

6. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 5, characterized in that: Step S3 is specifically as follows: A porous graphite electrode is used as a working electrode and wrapped with a 500-mesh bag filter, a platinum sheet is used as a counter electrode, a saturated calomel electrode is used as a reference electrode, and the copper-containing mixed solution obtained in step S2 is used as an electrolyte to construct an electrochemical reaction system; At room temperature, a constant voltage of 5 V was applied to the porous graphite electrode, and the current density was controlled at 10 mA / cm 2 Within this range, electrochemical reaction was carried out and the reaction time was controlled to be 15h.

7. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 1, characterized in that: in, The porous graphite electrode was prepared by the following method: The waste graphite thermal conductive film is crushed into graphite powder, which is then mixed with a polytetrafluoroethylene binder, pressed into shape, and then sintered at 400-600°C for 1-4 hours to obtain a porous graphite electrode.

8. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 7, characterized in that: The porous graphite electrode is prepared by the following method: graphite thermal conductive film waste is crushed into graphite powder with a flake diameter of 10-100 μm, and then mixed with polytetrafluoroethylene binder at a mass ratio of 9:1, pressed and sintered at 500° C. for 2 hours, and cooled to room temperature to obtain a porous graphite electrode.

9. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 1, characterized in that: Step S4 is specifically as follows: After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and the porous graphite electrode and the filter are cleaned with deionized water. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned. After the cleaning is completed, the porous graphite electrode and the filter are taken out, the obtained cleaning liquid is collected, centrifuged, the solid product is collected, and dried to obtain the final graphene oxide product.

10. The method for preparing graphene oxide by electrochemical method based on electroplating copper waste liquid according to claim 9, characterized in that: Step S4 is specifically as follows: After the electrochemical reaction is completed, the porous graphite electrode and the filter are taken out, and the porous graphite electrode and the filter are cleaned with deionized water. The porous graphite electrode and the filter are then placed in deionized water and ultrasonically cleaned for 15-60 minutes at a frequency of 20-60 kHz. After cleaning, the porous graphite electrode and the filter are taken out, the cleaning liquid is collected, and the cleaning liquid is centrifuged at 2500-10000 rpm for 5-20 minutes. The solid product is collected and dried to obtain the final graphene oxide product.

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