Porous carbon material taking PVC as raw material, preparation method and application of porous carbon material in adsorption of metal ions
By using waste PVC plastic as raw material and combining ultrasonic cleaning and strong alkali double ball milling to prepare porous carbon materials, the problems of high cost and environmental pollution of traditional methods are solved, and the preparation and application of high-performance porous carbon materials are realized, which are suitable for supercapacitors and electrical adsorption.
Patent Information
- Application Number
- CN202510981741.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-16
- Publication Date
- 2025-10-17
AI Technical Summary
Traditional methods for preparing porous carbon materials are costly, environmentally polluting, unevenly doped, and have imprecise pore structure control, making it difficult to meet the demands of high-performance applications.
Waste PVC plastic is used as the carbon source. Through ultrasonic cleaning and polyethylene glycol swelling pretreatment, combined with strong alkali and double ball milling, porous carbon materials are prepared to optimize the pore structure and surface chemical properties, reduce costs and improve material performance.
The low-cost and environmentally friendly preparation of porous carbon materials has been achieved, the pore structure can be controlled, the specific surface area and adsorption performance of the material are improved, and it is suitable for supercapacitors and electrical adsorption, with significant economic and environmental benefits.
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Figure CN120793891A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to PVC material technology, in particular to a porous carbon material taking PVC as raw material, a preparation method and application thereof in adsorbing metal ions. BACKGROUND
[0002] Porous carbon materials have important applications in many fields, and traditional preparation methods have many limitations. On the one hand, high-purity carbon sources or complex chemical synthesis are relied on, which is high in cost and pollutes the environment; on the other hand, the doping is uneven, the pore structure is not fine-tuned, and it is difficult to meet the high-performance application requirements, such as supercapacitors, electric adsorption, catalysts, etc.
[0003] In view of the difficulties in processing waste PVC plastics and the lack of porous carbon material preparation, it is necessary to realize clean and environmentally friendly processing of waste PVC plastics, solve the pollution problem, explore the use of waste PVC plastics as carbon source to prepare porous carbon materials, reduce cost, realize resource recycling, optimize the preparation process, make the doping uniform, the pore structure controllable, improve the material performance, reduce the use of chemical reagents, reduce the environmental impact, improve the conversion rate of waste PVC plastics, and enhance the process economy. SUMMARY
[0004] The purpose of the present application is to provide a porous carbon material taking PVC as raw material, a preparation method and application thereof in adsorbing metal ions, in order to solve the above-mentioned deficiencies in the prior art.
[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of a porous carbon material taking PVC as raw material, comprising the following steps:
[0006] S1, pretreating waste PVC plastics to obtain pretreated PVC plastics; taking 10g of the pretreated PVC plastics, putting into a mixed solution of 50mL dimethylformamide and 5mL polyethylene glycol, heating and stirring in a 60℃ oil bath for 30 minutes to obtain a swollen PVC solution;
[0007] S2, transferring the swollen PVC solution to a ball mill tank, adding 3g of sodium hydroxide and 2g of potassium hydroxide, stirring at a speed of 200r / min at room temperature for 2 hours, adding ball milling balls according to a material ball mass ratio of 1:10, ball milling at a speed of 400r / min at room temperature for 3 hours to obtain a black mixture;
[0008] S3, adding 0.8g of thiourea and 0.5g of melamine to the black mixture, stirring at a speed of 150r / min at room temperature, and uniformly mixing and then drying in a 60℃ oven for 12 hours to obtain a precursor of a hierarchical porous carbon material;
[0009] S4, the precursor of the hierarchical porous carbon material is placed in a tube furnace, and is heated to 600 DEG C at a heating rate of 5 DEG C / min under the protection of argon atmosphere, and is kept for 2 hours; then is heated to 650 DEG C at a heating rate of 3 DEG C / min, and is kept for 1 hour, and is naturally cooled to room temperature, and the product is taken out and washed to obtain a washed product;
[0010] S5, the washed product is placed in a vacuum drying oven at 80 DEG C and dried for 12 hours, and then is placed in a tube furnace, and argon gas is introduced, and is calcined at 700 DEG C for 2 hours to obtain a crude porous carbon material, and the crude porous carbon material is surface modified to obtain a porous carbon material.
[0011] Further, the pretreatment in S1 comprises the following steps: the waste PVC plastics are physically cut into small pieces less than 2mm, and are placed in an ultrasonic cleaner, and are ultrasonically cleaned with deionized water and ethanol for 10-15 minutes respectively, and after drying, the pretreated PVC plastics are obtained.
[0012] Further, the relative molecular mass of the polyethylene glycol in S1 is 400.
[0013] Further, the ball mill ball in S2 is a mixture of stainless steel balls and zirconia balls in a mass ratio of 1:1.
[0014] Further, the washing in S4 comprises the following steps: the product is repeatedly washed with deionized water, and then is soaked in 10% dilute hydrochloric acid for 30 minutes, and finally is washed with deionized water until neutral to obtain the washed product.
[0015] Further, the surface modification in S5 comprises the following steps: the crude porous carbon material is mixed with pyrrole monomers in a mass ratio of 5:1, and ammonium persulfate is added, and in-situ polymerization is carried out at room temperature for 12 hours to obtain the porous carbon material.
[0016] A porous carbon material prepared from PVC as raw material, which is prepared by the preparation method.
[0017] The porous carbon material prepared by the preparation method is used in adsorbing metal ions.
[0018] Compared with the prior art, the porous carbon material with PVC as raw material, the preparation method and the application thereof in adsorbing metal ions provided by the application effectively improve the pretreatment effect of PVC by using ultrasonic cleaning and polyethylene glycol assisted swelling, so that the subsequent reaction is more sufficient; the combination of strong alkali pretreatment and double ball milling not only destroys the molecular structure of PVC, but also refines the particles and improves the porosity and specific surface area of the material through the synergistic effect of different material ball milling balls; the whole preparation process is simple in operation, mild in conditions, low in cost and friendly to the environment, easy for large-scale industrial production, provides an effective way for high-value utilization of waste PVC plastics, realizes the recycling of waste resources, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF DRAWINGS
[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art according to these drawings.
[0020] Figure 1 The preparation flow structure schematic diagram of the porous carbon material provided by the embodiments of the present application is shown in the figure.
[0021] Figure 2 The scanning electron microscope schematic diagram of the porous carbon material provided by the embodiments of the present application is shown in the figure. DETAILED DESCRIPTION
[0022] In order to make those skilled in the art better understand the technical solutions of the present application, the present application will be further described in detail with reference to the drawings.
[0023] Embodiment one:
[0024] Please refer to Figure 1 A preparation method of a porous carbon material with PVC as raw material, comprising the following steps:
[0025] S1, the waste PVC plastics are physically cut into less than 2mm debris, put into an ultrasonic cleaning machine, and cleaned with deionized water and ethanol for 10-15 minutes respectively, and then dried to obtain pretreated PVC plastics; 10g of the pretreated PVC plastics are taken and put into a mixed solution of 50mL dimethylformamide and 5mL polyethylene glycol with a relative molecular mass of 400, heated and stirred in a 60℃ oil bath for 30 minutes to obtain a swollen PVC solution;
[0026] S2, the swollen PVC solution is transferred to a ball mill tank, 3g of sodium hydroxide and 2g of potassium hydroxide are added, and stirring is carried out at room temperature at a speed of 200r / min for 2 hours, ball milling balls are added at a material to ball mass ratio of 1:10, the ball milling balls are a mixture of stainless steel balls and zirconia balls at a mass ratio of 1:1, ball milling is carried out at room temperature at a speed of 400r / min for 3 hours, and a black mixture is obtained;
[0027] In the experiment, the ball mill tank is stirred at a speed of 200r / min for 2 hours, which can make the material in the tank move relatively, so that the swollen PVC solution can be fully mixed with sodium hydroxide and potassium hydroxide, and the reaction can be carried out. At the same time, in the subsequent process of ball milling at a speed of 400r / min for 3 hours, the ball milling balls move at high speed in the tank, and the stirring capacity of the ball mill tank ensures that the ball milling balls can uniformly contact with the material, and the consistency of the ball milling effect is ensured.
[0028] Through stirring, the diffusion layer between the reactants can be broken, the collision frequency between the molecules of the reactants can be accelerated, and the chemical reaction can be promoted. In the reaction of the swollen PVC solution, sodium hydroxide and potassium hydroxide, good stirring capacity can help the reactants to be fully mixed, increase the contact area between the reactants, improve the reaction rate and the reaction degree, so that the black mixture can be obtained more efficiently.
[0029] S3, 0.8g of thiourea and 0.5g of melamine are added to the black mixture, stirring is carried out at room temperature at a speed of 150r / min, the mixture is uniformly mixed, and then is placed in a 60℃ oven for drying for 12 hours, to obtain a precursor of the hierarchical porous carbon material;
[0030] S4, the precursor of the hierarchical porous carbon material is placed in a tube furnace, is heated to 600℃ at a heating rate of 5℃ / min under the protection of argon atmosphere, is kept for 2 hours, is then heated to 650℃ at a heating rate of 3℃ / min, is kept for 1 hour, is naturally cooled to room temperature, and the product is taken out; the product is repeatedly washed with deionized water, is soaked in 10% dilute hydrochloric acid for 30 minutes, and is finally washed with deionized water until neutral, to obtain a washed product;
[0031] S5, the washed product is placed in a 80℃ vacuum drying box for drying for 12 hours, is then placed in a tube furnace, argon gas is introduced, and calcination is carried out at 700℃ for 2 hours, to obtain a crude porous carbon material, the crude porous carbon material is mixed with pyrrole monomers at a mass ratio of 5:1, ammonium persulfate is added, and in-situ polymerization reaction is carried out at room temperature for 12 hours, to obtain the porous carbon material.
[0032] Example two:
[0033] Please refer to Figure 2The embodiment provides a technical scheme based on the embodiment one: a porous carbon material taking PVC as a raw material.
[0034] 1. Porous carbon material structure characterization:
[0035] Please refer to Figure 2 As can be seen from the scanning electron microscope image, the porous carbon material as a whole presents a large number of pore structures, and the pore shapes are irregular, including circular, elliptical and some irregular crack-like pores. These pores penetrate the material interior, forming a complex internal channel, providing a large amount of space for the adsorption and transmission of substances, and enabling ions to more easily enter the material interior for adsorption; as can be seen from the image, the pore sizes are different, and such a multi-scale pore size distribution helps to increase the specific surface area of the material, and different sizes of pores can adsorb different sizes of molecules or ions, increasing the application adaptability of the material, such as in supercapacitors, small pores can provide high specific surface area to increase the capacitance, and large pores are beneficial to the rapid transmission of electrolyte ions.
[0036] The surface of the porous carbon material is not smooth and flat, but presents a relatively rough morphology. Such a rough surface increases the contact area of the material with external substances, which is beneficial to improve its adsorption performance and catalytic performance. There are interconnected channels between the pores, and substances can diffuse and migrate in the material interior through these channels. This is very important in the application of supercapacitor electrode materials, which can enable electrolyte ions to shuttle quickly in the electrode material interior, thereby improving the charging and discharging efficiency of the electrode.
[0037] 2. Specific surface area and pore structure determination experiment: The specific surface area and pore structure parameters of the porous carbon material are determined, and the influence of the structure on the adsorption performance is analyzed.
[0038] The porous carbon material is taken, a specific surface area and porosity analyzer is used, the specific surface area and pore structure are determined according to the instrument operation procedure, the specific surface area is determined by using the Brunauer-Emmett-Teller (BET) method, and the pore size distribution and pore volume and other parameters are determined by using the Barrett-Joyner-Halenda (BJH) method. The experimental data results are as follows:
[0039] Material <![CDATA[比表面积(m 2 / g)]]> Average pore size (nm) <![CDATA[总孔容(cm 3 / g)]]> Porous carbon material 1250 2.8 0.68
[0040] The porous carbon material has a higher specific surface area and pore volume, and a relatively appropriate average pore size, which provides more adsorption active sites and channels for the material, and is beneficial to the adsorption of metal ions.
[0041] 3. Surface chemical property analysis experiment: The surface chemical properties of the porous carbon material are analyzed, and the influence of the surface chemical properties on the adsorption performance is explained.
[0042] The surface element composition and chemical state of the porous carbon material are analyzed by surface analysis techniques such as X-ray photoelectron spectroscopy (XPS). The material sample is placed on the sample seat of the XPS instrument, and data collection is performed according to the instrument operation procedure.
[0043] The experimental data results are as follows:
[0044]
[0045]
[0046] The porous carbon material contains a certain amount of O and N elements on the surface. The presence of these elements can change the surface chemical properties of the material, increase the surface active sites, and improve the adsorption capacity of metal ions. The surface elements of ordinary activated carbon are relatively simple, and the adsorption performance is relatively weak.
[0047] Example Three
[0048] This embodiment provides a technical solution based on Example One: an application experiment of a porous carbon material.
[0049] Preparation of electrodes for supercapacitors using porous carbon materials: Take 5.0 mg of porous carbon material and 1.0 μL of polytetrafluoroethylene (PTFE, 60 wt% dispersed in water) in 1.0 mL of anhydrous ethanol to form a uniform suspension. Ultrasonic for about 30-60 min, drop the suspension onto a 1 cm x 4 cm foam nickel. After all the suspension is dropped, place the foam nickel in an oven at 80°C and dry for 30 min, then press into a sheet. Test in a three-electrode system, when the electrolyte is 50 mL of 6.0 mol·L - 1 KOH solution, the counter electrode is a platinum electrode, and the reference electrode is a Hg / HgO electrode; when the electrolyte is 50.0 mL of 1.0 mol·L -1 NaCl or H2SO4 solution, the counter electrode is a platinum electrode, and the reference electrode is a silver / silver chloride electrode.
[0050] The testing method for porous carbon materials for electrosorption involves mixing the porous carbon material, acetylene black, and a binder in a specific ratio (80:15:5 by mass), adding anhydrous ethanol, and ultrasonicating the mixture to form a suspension. This suspension is then formed into electrodes and assembled into an electrosorption device. A peristaltic pump is used to pump a salt solution containing the metal ions to be adsorbed into the device. A constant DC voltage of 1.0-1.5V is applied to cause electrosorption, which causes the metal ions in the solution to be adsorbed onto the electrosorption electrode material. After the electrosorption process is complete, a reverse voltage is applied to desorb the ions back into the original solution. If desorbed into another aqueous solution, the adsorption process is repeated repeatedly, followed by natural desorption after the voltage is removed, until the metal ion salt solution is completely adsorbed. At the beginning and end of the electrosorption process, as well as at the end of desorption, a certain amount of the metal ion salt solution is collected from the beaker and quantitatively analyzed for metal element content using an inductively coupled plasma (ICP) spectrometer. Repeated adsorption and desorption cycles allow the cyclic stability of the material during the electrosorption test to be determined.
[0051] In a 6.0mol / L KOH electrolyte, a constant current charge and discharge test was performed. The specific capacitance of the porous carbon material electrode reached about 370F / g at a current density of 1A / g. In a 1.0mol / L NaCl electrolyte and a 1.0mol / L H2SO4 electrolyte, the specific capacitance values measured under the corresponding working conditions also had corresponding results, which were 180F / g and 390F / g, respectively. After a certain period (1000 times) of cyclic charge and discharge tests, the specific capacitance retention rate of the electrode can reach about 90%, indicating that it has good cycle stability. When the current density gradually increases from a lower value (0.5A / g) to a higher value (5A / g), the specific capacitance of the electrode decreases to a certain extent, but can still be maintained at 70%.
[0052] Porous carbon materials have rich pore structures, which can provide a large number of active sites and ion transport channels, so that the ions in the electrolyte can quickly and fully contact the surface of the electrode material, thereby realizing efficient charge storage, which provides a structural basis for obtaining a higher specific capacitance; its good cycle stability is due to the improvement of the structural stability by the stable carbon skeleton structure of the material, which can maintain the integrity of the electrode structure during repeated charge and discharge, reducing the loss of active substances and structural collapse; in terms of rate performance, the porous structure helps to shorten the ion diffusion path, and to a certain extent alleviates the problem of limited ion diffusion caused by the increase in current density, so that the electrode can still exert a relatively considerable specific capacitance at a higher current density, showing good rate performance.
[0053] Adsorption efficiency: Cu 2+ For example, the porous carbon material was used as an electrosorption electrode, and electrosorption was performed under a constant DC voltage of 1.0-1.5 V. After a certain period of time (1 hour), the Cu 2+The adsorption rate reaches about 85%, and with further extension of the adsorption time, the adsorption rate gradually tends to saturation, and finally can reach about 95%.
[0054] Desorption performance: after the end of the electric adsorption process, a reverse voltage is applied, and after a certain time (30 minutes), Cu 2+ The desorption rate of the material can reach about 90%, indicating that the material has good renewable utilization. If the electric adsorption and natural desorption process after removing the voltage are repeated for several times, the adsorption of the metal ion salt solution to be adsorbed can be gradually realized.
[0055] Different metal ion adsorption: for a mixed solution containing multiple different metal ions, the porous carbon material electrode exhibits the same adsorption capacity for different metal ions, and the adsorption capacity for Na + , Mg 2+ , Fe 3+ , Ni 2+ , Cd 2+ , Zn 2+ , Cu 2+ , Co 2+ , Pb 2+ is relatively stable.
[0056] The pore structure of the porous carbon material provides it with a large specific surface area, increases the contact area and adsorption sites with metal ions, and is beneficial to the adsorption and enrichment of metal ions. The good desorption performance is due to the fact that the material can effectively control the adsorption and desorption process of ions under the action of an electric field, and by changing the direction of the electric field or removing the electric field, the ions adsorbed on the surface of the material can be smoothly desorbed back into the solution; on the other hand, the stability of the structure of the material itself makes it not appear obvious structural damage or loss of active sites in the process of multiple adsorption and desorption cycles, thereby ensuring good renewable utilization.
[0057] The above only describes certain exemplary embodiments of the present application in a descriptive manner, and it is needless to say that for ordinary skilled persons in the art, the described embodiments can be modified in various ways without departing from the spirit and scope of the present application. Therefore, the above figures and description are illustrative in nature and should not be understood as limiting the scope of protection of the claims of the present application.
Claims
1. A method for preparing a porous carbon material using PVC as raw material, characterized in that: The steps include: S1. Pretreating waste PVC plastic to obtain pretreated PVC plastic; taking 10 g of the pretreated PVC plastic, placing it in a mixed solution of 50 mL of dimethylformamide and 5 mL of polyethylene glycol, heating and stirring in a 60° C. oil bath for 30 minutes to obtain a swollen PVC solution; S2. The swollen PVC solution was transferred to a ball mill, 3 g of sodium hydroxide and 2 g of potassium hydroxide were added, and the mixture was stirred at 200 r / min at room temperature for 2 hours. Ball milling balls were added at a mass ratio of 1:10, and the mixture was ball milled at 400 r / min at room temperature for 3 hours to obtain a black mixture; S3. Add 0.8 g of thiourea and 0.5 g of melamine to the black mixture, stir at 150 r / min at room temperature, mix well, and then dry in an oven at 60° C. for 12 hours to obtain a precursor of a hierarchically porous carbon material. S4. Place the precursor of the hierarchically porous carbon material into a tube furnace, and under argon atmosphere, heat the temperature to 600° C. at a rate of 5° C. / min, and keep the temperature for 2 hours; then heat the temperature to 650° C. at a rate of 3° C. / min, keep the temperature for 1 hour, and cool the mixture naturally to room temperature. Take out the product and wash it to obtain a washed product; S5. The cleaned product is placed in a vacuum drying oven at 80°C and dried for 12 hours, then placed in a tubular furnace, introduced with argon gas, and calcined at 700°C for 2 hours to obtain a crude porous carbon material. The crude porous carbon material is surface-modified to obtain a porous carbon material.
2. The method for preparing a porous carbon material using PVC as raw material according to claim 1, characterized in that: The pretreatment in S1 includes the following steps: physically cutting the waste PVC plastic into fragments smaller than 2 mm, placing the fragments in an ultrasonic cleaning machine, ultrasonically cleaning the fragments with deionized water and ethanol for 10-15 minutes respectively, and drying the pretreated PVC plastic.
3. The method for preparing a porous carbon material using PVC as raw material according to claim 1, characterized in that: The relative molecular mass of the polyethylene glycol described in S1 is 400.
4. The method for preparing a porous carbon material using PVC as raw material according to claim 1, characterized in that: The ball milling balls in S2 are obtained by mixing stainless steel balls and zirconia balls in a mass ratio of 1:
1.
5. The method for preparing a porous carbon material using PVC as raw material according to claim 1, characterized in that: The cleaning in S4 comprises the following steps: firstly repeatedly washing the product with deionized water, then soaking it in 10% by mass dilute hydrochloric acid for 30 minutes, and finally washing it with deionized water until it is neutral to obtain a washed product.
6. The method for preparing a porous carbon material using PVC as raw material according to claim 1, characterized in that: The surface modification in S5 includes the following steps: mixing a crude porous carbon material and a pyrrole monomer in a mass ratio of 5:1, adding ammonium persulfate, and performing an in-situ polymerization reaction at room temperature for 12 hours to obtain a porous carbon material.
7. A porous carbon material using PVC as raw material, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 6.
8. Use of the porous carbon material prepared by the preparation method according to any one of claims 1 to 6 in the adsorption of metal ions.