Method for resource utilization of waste graphite, catalyst and use thereof

Abstract

The application provides a waste graphite resource utilization method, a catalyst and application thereof. The waste graphite resource utilization method comprises the following steps: crushing a graphite-containing electrode of a waste battery to obtain a crushing product; pyrolyzing the crushing product to obtain a pyrolysis product; and activating the pyrolysis product to obtain a catalyst. The waste graphite resource utilization method is simple and easy to implement, raw materials are easy to obtain, and the method can realize the recycling of waste graphite and the collaborative management of new pollutants. The catalyst can not only capture new pollutants such as antibiotics by using adsorption sites and catalytic centers, but also analyze the unique gain effect of self-doped metals on the adsorption and degradation process of tetracycline hydrochloride. The catalyst can be used for in-situ enhancement of efficient capture and catalytic behavior of antibiotics, dyes or other pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to a waste graphite resource utilization method, a catalyst and its use, in particular to a waste battery anode graphite resource utilization method, a catalyst and its use, belonging to the field of waste battery resource recycling. BACKGROUND

[0002] The rapid development of new energy electric vehicles has driven the rapid increase in the production and sales of lithium ion batteries. Graphite is the main anode material in commercial lithium batteries, accounting for 10-20wt.% of the mass of lithium batteries. According to the global anode material shipment volume and the proportion of graphite anodes, it is estimated that the waste lithium batteries that will end their life in the next five years will produce 4 million tons of waste graphite. Waste graphite usually contains various trace or trace metal impurities and toxic and harmful electrolyte, which is difficult to recycle and is usually burned at high temperature or discarded for landfill, which results in great resource waste and environmental disposal cost. However, existing research mainly focuses on the recovery of valuable metals in waste lithium battery cathodes, and less attention is paid to the large amount of waste graphite.

[0003] The resource utilization of waste graphite usually includes: after crushing, screening, acid washing to remove metal impurities and high-temperature removal of organic impurities, it is used as a degraded regenerated graphite, or prepared into supercapacitor energy storage materials, or prepared into graphene materials by high-polluting Hummers method. In addition, carbon-based materials, such as carbon nanotubes, graphene, biochar, etc., have been widely concerned in wastewater adsorption treatment in the past decade due to their porous structure, which can be used as stable carriers. Waste graphite belongs to a kind of carbon-based materials, which has the potential to be prepared into carriers for wastewater treatment.

[0004] Reference document 1 discloses a waste old lithium ion battery regenerated graphite-containing electrode by organic acid pyrolysis gas phase reduction and a regeneration method thereof, which provides a technical solution of discharging, disassembling and separating waste lithium batteries to obtain waste graphite powder; the graphite powder is subjected to acid leaching impurity removal using organic acid, solid-liquid separation of the graphite after acid leaching, drying and high-temperature calcination to obtain regenerated graphite.

[0005] Reference document 2 discloses a method for preparing supercapacitor electrode material from waste old lithium battery graphite, which provides a technical solution of preparing graphene / MnO2 supercapacitor electrode material by soaking and cleaning waste graphite in water, roasting and ball milling for purification, and then adding potassium permanganate in a Teflon inner container reaction kettle for hydrothermal reaction.

[0006] Reference Document 3 discloses a method for preparing graphene oxide by improving the Hummers method, which provides mixing graphite, sodium nitrate and potassium permanganate under ice bath conditions, then placing the mixture in concentrated sulfuric acid, stirring until a mud-like substance appears, adding deionized water to the beaker while stirring, transferring the beaker to a 90℃ constant temperature water bath and continuing to stir, adding hydrogen peroxide and continuing to stir, obtaining a solution, filtering the excess sulfate ions in the solution by dialysis, storing after multiple centrifugal treatments, and finally performing ultrasonic treatment by a constant temperature ultrasonic device, and screening out a preparation method of single-layer graphene oxide.

[0007] However, the method of regenerating waste graphite into electrode materials or preparing graphene has high requirements for equipment and cost, and produces a secondary waste stream, and none of the above resource utilization methods has an industrial application case. At the same time, the manufacturing process of carbon material adsorbents is generally complex and expensive, and inevitably needs further carbonization or loading of metals to improve the performance of degrading pollutants, which to some extent reduces the practicability of these carbon materials. It can be seen that the current recycling economy field has appeared the industry contradiction of low resource utilization efficiency of waste graphite and high processing and utilization cost of new carbon materials.

[0008] Therefore, it has become a technical problem to be solved to study a resource utilization method of waste graphite, realizing the recycling of waste graphite and the collaborative treatment of new pollutants.

[0009] Reference:

[0010] Reference Document 1: Patent Application 202310487511.X

[0011] Reference Document 2: Patent Application 202211280713.9

[0012] Reference Document 3: Patent Application 202310470563.6 SUMMARY

[0013] Problems to be solved by the invention

[0014] In view of the technical problems existing in the prior art, the present application provides a resource utilization method of waste graphite. The waste graphite resource utilization method of the present application is simple and easy to implement, the raw materials are easy to obtain, and the recycling of waste graphite and the collaborative treatment of new pollutants can be realized.

[0015] The present application also provides a catalyst which can not only capture new pollutants such as antibiotics by using adsorption sites and catalytic centers, but also analyze the unique gain effect of self-doped metals on the adsorption and degradation process of tetracycline hydrochloride.

[0016] In addition, the present application also provides a use of a catalyst for in-situ enhancing the efficient capture and catalytic behavior of antibiotics, dyes or other similar pollutants.

[0017] Solutions for solving the problem

[0018] [1] A method for recycling waste graphite, comprising the following steps:

[0019] crushing the graphite-containing electrode of the waste battery to obtain a crushed product;

[0020] pyrolyzing the crushed product to obtain a pyrolyzed product;

[0021] activating the pyrolyzed product to obtain a catalyst.

[0022] [2] A method for recycling waste graphite, comprising the following steps:

[0023] crushing the graphite-containing electrode of the waste battery to obtain a crushed product;

[0024] activating the crushed product to obtain an activated product;

[0025] pyrolyzing the activated product to obtain a catalyst.

[0026] [3] The method according to the above [1] or [2], wherein the method further comprises sieving the crushed product to obtain a sieved product.

[0027] [4] The method according to the above [3], wherein the particle size of the sieved product is less than 0.1 mm, preferably less than 0.074 mm.

[0028] [5] The method according to any one of the above [1]-[4], wherein the pyrolyzing is carried out under vacuum, air or inert atmosphere; preferably, the inert atmosphere comprises one or both of nitrogen atmosphere and argon atmosphere.

[0029] [6] The method according to any one of the above [1]-[5], wherein the temperature of the pyrolyzing is 300-800℃; the time of the pyrolyzing is 30-180 min.

[0030] [7] The method according to any one of the above [1]-[6], wherein the activating comprises a step of mechanical ball milling; preferably, the rotation speed of the mechanical ball milling is 300-700 r / min; the time of the mechanical ball milling is 30-180 min.

[0031] [8] A catalyst, characterized by being prepared according to the method of any one of the above [1]-[7].

[0032] [9] The catalyst according to the above-mentioned [8], wherein the average pore diameter of the catalyst is 0.4-1 nm, and the specific surface area of the catalyst is 200-240 m 2

[0033]

[10] Use of the catalyst according to the above-mentioned [8] for catalytic oxidation of pollutants; preferably, the pollutants include antibiotics and / or dyes.

[0034] Effects of the invention

[0035] The waste graphite resource utilization method of the present application is simple and easy to implement, and the raw materials are easy to obtain, which can realize the recycling of waste graphite and the collaborative management of new pollutants.

[0036] The catalyst of the present application not only can capture new pollutants such as antibiotics by using adsorption sites and catalytic centers, but also analyzes the unique gain effect of self-doped metals on the adsorption and degradation process of tetracycline hydrochloride.

[0037] The catalyst of the present application can be used to enhance the efficient capture and catalytic behavior of antibiotics, dyes or other similar pollutants in situ. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The overall flowchart of the waste graphite resource utilization method, the catalyst and the use thereof according to an embodiment of the present application is shown.

[0039] Figure 2 The Raman spectrum of different catalysts is shown.

[0040] Figure 3 The BET graph of different catalysts is shown, wherein a is the specific surface area comparison graph of different catalysts, and b is the isothermal adsorption curve and particle size distribution graph of different catalysts.

[0041] Figure 4 The adsorption performance of different catalysts on tetracycline hydrochloride is shown.

[0042] Figure 5 The adsorption and catalytic performance of catalysts of different experimental systems on tetracycline hydrochloride is shown.

[0043] Figure 6 The adsorption and catalytic performance of catalysts on tetracycline hydrochloride under different solution pH is shown.

[0044] Figure 7 The cyclic adsorption performance of the catalyst is shown. DETAILED DESCRIPTION

[0045] ​Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0046] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0047] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0048] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0049] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0050] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0051] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0052] <First aspect>

[0053] The first aspect of this invention provides a method for the resource utilization of waste graphite, comprising the following steps:

[0054] The graphite-containing electrodes of waste batteries are crushed to obtain the crushed product.

[0055] The crushed product is subjected to pyrolysis treatment to obtain pyrolysis product;

[0056] The pyrolysis products are activated to obtain a catalyst.

[0057] This invention utilizes the self-doping metal properties of waste graphite to prepare catalysts, thereby achieving the resource utilization of waste graphite. The resource utilization method of waste graphite in this invention is simple and easy to implement, the raw materials are readily available, and it can achieve the synergistic treatment of waste graphite and new pollutants.

[0058] Waste battery

[0059] First, the electrodes of the waste battery of this invention contain graphite. This invention does not specifically limit the type of waste battery, as long as it contains graphite. Specifically, the waste battery can be a waste lithium battery. Specifically, the lithium battery can be a lithium cobalt oxide battery, a lithium iron phosphate battery, a ternary lithium battery, or other types of lithium batteries.

[0060] For spent lithium batteries, waste graphite typically retains a good layered structure and readily forms porous structures, defects, and polar / oxygen-containing functional groups during repeated lithium insertion-extraction and electrolyte decomposition, exhibiting excellent physical properties. Furthermore, the inventors accidentally discovered that waste graphite itself contains residual metals such as Cu, Zr, Fe, Co, Ni, and Mn, which can be considered self-doped metals, avoiding the metal loading step in conventional preparation processes. Breaking through the conventional understanding of these impurity metal residues and reversing their waste attributes, they can be used as adsorption sites and catalytic centers for capturing new pollutants such as antibiotics, providing a possibility for the recycling of waste graphite and the synergistic treatment of new pollutants.

[0061] This invention reveals for the first time the occurrence characteristics of self-doped metals in graphite-containing electrodes of waste batteries, coupled with the physical properties of waste graphite itself, such as structural defects and active groups, to enhance the efficient capture and catalytic behavior of antibiotics in situ, and elucidates the unique gain effect of self-doped metals on the adsorption of antibiotics (e.g., tetracycline hydrochloride TC) and the antibiotic degradation process.

[0062] Crushing treatment

[0063] To ensure the safety of the experimental process, the used batteries undergo a safe discharge treatment. Specifically, the used batteries are first discharged by physical short-circuiting, then immersed in NaCl solution for a full discharge of about 12-24 hours, and then air-dried in a fume hood. The discharge continues until the battery voltage is less than 0.1V, at which point disassembly, crushing, and other related experiments can be carried out.

[0064] To obtain the desired catalyst, the graphite-containing electrodes, such as graphite anodes, from dismantled waste batteries should be crushed to obtain crushed products. Crushing removes large pieces of metal foil, such as copper foil, yielding the desired waste graphite. The present invention does not particularly limit the crushing method; it can be selected as needed, as long as the desired crushed products are obtained. Specifically, shear crushing can be used to obtain the desired crushed products.

[0065] In some specific implementations, the method further includes sieving the crushed product to obtain a sieved product, and then subjecting the sieved product to pyrolysis treatment; preferably, the particle size of the sieved product is less than 0.1 mm, more preferably less than 0.074 mm.

[0066] Pyrolysis treatment

[0067] The first aspect of the present invention is to obtain a pyrolysis product by pyrolyzing the crushed product; the pyrolysis treatment can remove some impurities, such as surface impurities like binders.

[0068] In some specific embodiments, the pyrolysis treatment in this invention can be carried out under vacuum conditions, in an air atmosphere, or in an inert atmosphere, preferably in an inert atmosphere. The pyrolysis effect is better when the crushed products are pyrolyzed in an inert atmosphere.

[0069] Specifically, in this invention, an inert atmosphere refers to an atmosphere that does not chemically react with the crushed products. Preferably, the inert atmosphere includes one or both of nitrogen and argon atmospheres. Introducing an inert atmosphere can effectively improve the removal rate of antibiotics from the pyrolysis products. This may be because the inert gas promotes the development of pores in the waste graphite, thereby increasing the specific surface area and thus promoting the adsorption of antibiotics by the waste graphite.

[0070] Furthermore, in this invention, the temperature of the pyrolysis treatment is 300–800°C, for example: 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, etc.; the time of the pyrolysis treatment is 30–180 min, for example: 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, etc.

[0071] Furthermore, the present invention does not impose any particular limitation on the equipment used for pyrolysis treatment, and the equipment can be selected as needed. Specifically, in the present invention, the pyrolysis treatment can be carried out in a tube furnace or a muffle furnace, preferably in a tube furnace.

[0072] Activation treatment

[0073] The first aspect of this invention involves activating the pyrolysis products to obtain a catalyst. The catalyst prepared by this invention through pyrolysis and mechanical activation avoids the addition of chemical reagents, exhibits excellent catalytic activity and stability, and demonstrates a very high antibiotic removal rate over a wide pH range. This not only promotes the high-value utilization of waste graphite, conforming to the principles of green chemistry and the concept of a circular economy, but also achieves "waste-to-waste treatment," contributing to the control of new pollutants.

[0074] In some specific embodiments, the activation treatment includes a step of mechanically ball-milling the pyrolysis products. Mechanical ball milling can refine the waste graphite particles and enhance surface activity.

[0075] Preferably, the rotational speed of the mechanical ball mill is 300–700 r / min, for example: 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, 650 r / min, etc.; the mechanical ball milling time is 30–180 min, for example: 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, etc.

[0076] Furthermore, the present invention does not impose any particular limitation on the equipment used for activation, and it can be selected as needed. Specifically, in the present invention, the activation can be performed mechanically using a ball mill.

[0077] The present invention transforms waste graphite into a high specific surface area catalyst with certain functions by pyrolysis and then activation treatment. Its average pore size can be 0.4-1 nm and its adsorption capacity for pollutants can reach 200-450 mg / g.

[0078] The method of this invention avoids the introduction of strong acids and strong oxidizing agents in traditional methods such as the Hummers method, and avoids the addition of chemical reagents such as metal-supported reagents. Furthermore, the used catalyst can be regenerated and recycled, thus reducing costs to some extent. In addition, the solid-liquid ratio (preferably m) used in this invention... 催化剂 V 污染物溶液 The concentration (0.025g~0.1g):50mL) is relatively low, suggesting that this method has the potential to treat antibiotic wastewater. The method of this invention provides a new approach for the resource utilization of waste graphite from waste lithium batteries and is also expected to become a candidate material for treating pollutants, such as antibiotic wastewater.

[0079] The resource utilization method of waste graphite of the present invention is simple and easy to implement, the raw materials are easy to obtain, and it can realize the recycling and utilization of waste graphite and the synergistic treatment of new pollutants.

[0080] <Second aspect>

[0081] A second aspect of the present invention provides a method for the resource utilization of waste graphite, comprising the following steps:

[0082] The graphite-containing electrodes of waste batteries are crushed to obtain the crushed product.

[0083] The crushed product is activated to obtain an activated product;

[0084] The activated product was subjected to pyrolysis to obtain a catalyst.

[0085] The waste battery of the second aspect of the present invention is the same as the waste battery of the first aspect.

[0086] Crushing treatment

[0087] To ensure the safety of the experimental process, the used batteries undergo a safe discharge treatment. Specifically, the used batteries are first discharged by physical short-circuiting, then immersed in NaCl solution for 12-24 hours to fully discharge, and then air-dried in a fume hood. This continues until the battery voltage is less than 0.1V, at which point disassembly, crushing, and other related experiments can be performed.

[0088] To obtain the desired catalyst, the graphite-containing electrodes of spent batteries, such as graphite anodes, should be crushed to obtain crushed products. The present invention does not particularly limit the crushing method; it can be selected as needed, as long as the desired crushed products are obtained. Specifically, shear crushing can be used to obtain the desired crushed products.

[0089] In some specific implementations, the method further includes sieving the crushed product to obtain a sieved product, and then activating the sieved product; preferably, the particle size of the sieved product is less than 0.1 mm, more preferably less than 0.074 mm.

[0090] Activation treatment

[0091] A second aspect of the present invention involves activating the crushed product to obtain an activated product.

[0092] In some specific embodiments, the activation treatment includes a step of mechanically ball-milling the sieved product. Mechanical ball milling can refine the waste graphite particles and enhance surface activity to some extent.

[0093] Preferably, the rotational speed of the mechanical ball mill is 300–700 r / min, for example: 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, 650 r / min, etc.; the mechanical ball milling time is 30–180 min, for example: 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, etc.

[0094] Furthermore, the present invention does not impose any particular limitation on the equipment used for activation, and it can be selected as needed. Specifically, in the present invention, the activation can be performed mechanically using a ball mill.

[0095] Pyrolysis treatment

[0096] A second aspect of the invention involves pyrolyzing the activated product to obtain a catalyst. Pyrolysis can remove some impurities, such as surface impurities like binders. However, when activation is performed before pyrolysis, the removal rate of antibiotics is somewhat reduced. This is because pyrolyzing to remove the binder before mechanical activation results in a significantly higher specific surface area for the particles compared to pyrolysis.

[0097] In some specific embodiments, the pyrolysis treatment in this invention can be carried out under vacuum conditions, in an air atmosphere, or in an inert atmosphere, preferably in an inert atmosphere. The pyrolysis effect is better when the activated product is pyrolyzed in an inert atmosphere.

[0098] Specifically, in this invention, an inert atmosphere means an atmosphere that does not chemically react with the activation products. Preferably, the inert atmosphere includes one or both of nitrogen and argon atmospheres.

[0099] Furthermore, in this invention, the temperature of the pyrolysis treatment is 300–800°C, for example: 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, etc.; the time of the pyrolysis treatment is 30–180 min, for example: 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, etc.

[0100] Furthermore, the present invention does not impose any particular limitation on the equipment used for pyrolysis, and any equipment can be selected as needed. Specifically, in the present invention, the pyrolysis can be carried out in a tube furnace or a muffle furnace, preferably in a tube furnace.

[0101] The catalyst prepared by this invention through mechanical activation followed by pyrolysis avoids the addition of chemical reagents. However, the antibiotic removal rate is lower than that obtained by pyrolysis followed by mechanical activation.

[0102] Furthermore, the inventors of this invention discovered that the removal rate of antibiotics decreases to some extent when activation is performed before pyrolysis. This is because mechanical activation after pyrolysis to remove the binder results in particles with a much higher specific surface area than activation followed by pyrolysis.

[0103] <Third aspect>

[0104] A third aspect of the present invention provides a catalyst prepared by the method described in the first or second aspect of the present invention. The present invention achieves the recycling and reuse of waste battery anode graphite through a method for preparing antibiotic catalysts from waste lithium battery anode graphite.

[0105] The catalyst preparation process of this invention is simple, avoiding the addition of external chemical reagents. It successfully converts waste battery graphite into a catalyst using pyrolysis and mechanical activation. This method achieves low-cost, green resource utilization of waste graphite, while simultaneously realizing "waste-to-waste treatment," contributing to the control of emerging pollutants.

[0106] Preferably, the catalyst has an average pore size of 0.4-1 nm, for example: 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, etc.; and the catalyst has a specific surface area of ​​200-240 m². 2 / g, for example: 205m 2 / g、210m 2 / g、215m 2 / g、220m 2 / g、225m 2 / g、230m 2 / g、235m 2 / g etc.

[0107] The catalyst of this invention can induce an oxidant to generate free radicals, thereby degrading antibiotics through adsorption and catalytic action. Specifically, the oxidant can be an inorganic oxidant, such as a peroxide oxidant (e.g., hydrogen peroxide), a persulfate oxidant (e.g., sodium persulfate, potassium persulfate, magnesium persulfate), etc.

[0108] The catalyst of this invention can not only capture and degrade new pollutants such as antibiotics through adsorption sites and catalytic centers, but also reveals the unique enhancement effect of self-doped metals in graphite on the adsorption and degradation process of pollutants such as tetracycline hydrochloride.

[0109] <Fourth Aspect>

[0110] A fourth aspect of the invention provides the use of the catalyst according to the third aspect of the invention for the catalytic oxidation of pollutants; preferably, the pollutants include antibiotics and / or dyes. For antibiotics, this may be tetracycline hydrochloride, etc.

[0111] In some specific embodiments, catalytic oxidation in this invention is generally performed on a contaminant solution. That is, in the presence of the catalyst of this invention, an oxidant is used to catalytically oxidize the contaminant solution. Specifically, the oxidant is generally an inorganic oxidant, such as a peroxide oxidant, a persulfate oxidant, etc. For peroxide oxidants, hydrogen peroxide is generally an example; for persulfate oxidants, sodium persulfate, potassium persulfate, magnesium persulfate, etc.

[0112] Furthermore, this invention does not impose particular limitations on parameters such as the time of the catalytic oxidation reaction between the oxidant and the pollutant, the concentration of the pollutant, the pH value of the pollutant, the amount of catalyst added, the amount of oxidant added, and the solid-liquid ratio of the catalyst, and these parameters can be selected as needed.

[0113] Specifically, in the pollutant solution, the concentration of the pollutant can be 100–250 mg / L; the pH of the pollutant solution is adjusted to 2–11; the catalytic oxidation reaction time is 2–60 min; the catalyst dosage is 0.025 g–0.1 g; and the volume of the pollutant solution is 50 mL, i.e., the solid-liquid ratio of the catalyst to the pollutant solution is m. 催化剂 V 污染物溶液 The dosage is 50 mL (0.025 g to 0.1 g); the dosage of oxidant (taking hydrogen peroxide as an example) is 0 to 3 vol.%.

[0114] Preferably, the pH of the pollutant solution is adjusted to 3-7, the catalytic oxidation reaction time is 2-30 min, the catalyst dosage is 0.025 g-0.05 g, and the oxidant dosage (taking hydrogen peroxide as an example) is 0.1-1 vol.%.

[0115] Furthermore, the present invention does not impose particular limitations on the equipment used for the catalytic oxidation reaction of pollutants, and the appropriate equipment can be selected as needed. Specifically, in the present invention, the reaction can occur in a water bath shaker or a water bath.

[0116] The catalyst of this invention does not require loading with metal reagents and is simple to prepare. It can efficiently treat pollutants, such as antibiotics, simply by pyrolysis and activation. Specifically, the adsorption capacity for the antibiotic tetracycline hydrochloride is 200-450 mg / g.

[0117] Example

[0118] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0119] In this embodiment, to ensure the safety of the experimental process, the waste ternary lithium battery anode sheets used were subjected to safe discharge treatment. Specifically, the waste batteries were first physically short-circuited for discharge, then immersed in a 5wt% NaCl solution for full discharge for approximately 12-24 hours, and then air-dried in a fume hood until the battery voltage was less than 0.1V.

[0120] Example 1

[0121] The discharged waste ternary lithium battery anode sheets were sheared and crushed to obtain the crushed product. The crushed product was then sieved through a 0.074mm sieve to remove large pieces of Cu and obtain relatively pure screened graphite.

[0122] The sieved graphite was fed into a tube furnace for medium-low temperature pyrolysis to obtain pyrolytic graphite. The pyrolysis atmosphere for each pyrolysis cycle was set to N2, the pyrolysis temperature to 400℃, and the pyrolysis time to 30 min.

[0123] Pyrolytic graphite was mechanically activated in a ball mill to obtain a catalyst, denoted as PMG. The mechanical activation time was set to 120 min, and the ball mill speed was set to 600 r / min.

[0124] Example 2

[0125] The discharged waste ternary lithium battery anode sheets were sheared and crushed to obtain the crushed product. The crushed product was then sieved through a 0.074mm sieve to remove large pieces of Cu and obtain relatively pure screened graphite.

[0126] The sieved graphite was mechanically activated in a ball mill to obtain activated graphite. The mechanical activation time was set to 120 min, and the ball mill speed was 600 r / min.

[0127] Activated graphite was fed into a tube furnace for medium-low temperature pyrolysis to obtain a catalyst, denoted as MPG. The pyrolysis atmosphere for each pyrolysis was set to N2, the pyrolysis temperature to 400℃, and the pyrolysis time to 30 min.

[0128] Example 3

[0129] The discharged waste ternary lithium battery anode sheets were sheared and crushed to obtain the crushed product. The crushed product was then sieved through a 0.074mm sieve to remove large pieces of Cu and obtain relatively pure screened graphite.

[0130] The sieved graphite was fed into a tube furnace for medium-to-low temperature pyrolysis to obtain pyrolytic graphite. The pyrolysis atmosphere for each pyrolysis cycle was set to N2. The pyrolysis temperature was set to 400℃, and the pyrolysis time was set to 30 minutes.

[0131] Pyrolytic graphite was mechanically activated in a ball mill to obtain a catalyst, denoted as PMG-2. The mechanical activation time was set to 60 min, and the ball mill speed was set to 600 r / min.

[0132] Comparative Example 1

[0133] 200-mesh natural graphite (purchased from Nanjing Greenfa Carbon Materials Co., Ltd.), denoted as NG.

[0134] Comparative Example 2

[0135] The discharged lithium battery anode sheets are sheared and crushed to obtain the crushed product. The crushed product is then sieved through a 0.074mm sieve to remove large pieces of Cu, resulting in relatively pure screened graphite, denoted as SG.

[0136] Comparative Example 3

[0137] The discharged lithium battery anode sheets were sheared and crushed to obtain the crushed product. The crushed product was then sieved through a 0.074mm sieve to remove large pieces of Cu and obtain relatively pure screened graphite.

[0138] The sieved graphite was fed into a tube furnace for medium-low temperature pyrolysis to obtain pyrolytic graphite, denoted as PG. The pyrolysis atmosphere for each pyrolysis cycle was set to N2. The pyrolysis temperature was set to 400℃, and the pyrolysis time was set to 30 min.

[0139] Comparative Example 4

[0140] The discharged lithium battery anode sheets were sheared and crushed to obtain the crushed product. The crushed product was then sieved through a 0.074mm sieve to remove large pieces of Cu and obtain relatively pure screened graphite.

[0141] The sieved graphite was mechanically activated in a ball mill to obtain activated graphite, denoted as MG. The mechanical activation time was set to 120 min, and the ball mill speed was set to 600 r / min.

[0142] Performance test

[0143] 1. Raman characterization

[0144] The defects of the catalysts prepared in Examples 1 and Comparative Examples 1-4 were characterized using laser Raman spectroscopy, as shown in the attached figures. Figure 2 As shown. Among them, the D peaks of natural graphite (NG) and SG-sieved graphite in Comparative Examples 1 and 2 are very weak, indicating low defect density in the catalysts. The S peaks of pyrolytic graphite (PG) in Comparative Example 3 and the catalyst (PMG) in Example 1 are... D / S G The values ​​are significantly larger than SG, increasing to 0.68 and 1.19 respectively. The larger S... D / S G The increase in defects and disordered structure in the catalyst indicates that it can provide more reaction sites. Furthermore, compared to SG, the G peaks of PG and PMG are significantly higher than those of SG (1568 cm⁻¹). -1 Offset to 1578cm -1 and 1570cm -1 The shift in the position of the G peak Raman scattering peak is due to changes in the electronic structure caused by the increased disorder in the catalyst structure.

[0145] 2. BET representation

[0146] The specific surface area and pore size distribution of the catalysts prepared in Examples 1 and Comparative Examples 1-4 were characterized using a specific surface area porosity analyzer, as shown in the attached figures. Figure 3 As shown, compared with natural graphite (NG), sieved graphite (SG), and pyrolytic graphite (PG), the catalyst PMG has the largest specific surface area and pore volume, both at 237.2 m². 2 / g and 0.3954cm 3 / g, which further illustrates that pyrolysis and mechanical activation treatment are beneficial to pore development, and mechanical force impacts, shears, and grinds graphite materials into smaller particles.

[0147] BET characterization indicates that the isotherms of NG, SG, and PG belong to Type III in the IUPAC classification. Their adsorption curves show that at low and medium relative pressures, the adsorption capacity is small, and monolayer adsorption is saturated. With increasing relative pressure, adsorption exhibits a self-accelerating phenomenon, and the number of adsorption layers is not limited. In contrast, the isotherm of PMG belongs to Type IV in the IUPAC classification, with an H4 hysteresis loop. The catalyst at the low-pressure end has a strong interaction with nitrogen, indicating the presence of numerous micropores. Due to the strong adsorption potential within the micropores, the adsorption curve initially exhibits a Type I pattern.

[0148] The pore size distribution diagram further demonstrates that pyrolysis and mechanochemical treatment transform SG from its original macropores into a greater number of micropores and mesopores. In summary, PMG after pyrolysis and mechanical activation possesses a larger specific surface area and more microporous / mesoporous structures, which will improve the catalyst's adsorption performance.

[0149] 3. Adsorption performance test of tetracycline hydrochloride (TC)

[0150] 50 mL of 150 mg / L tetracycline hydrochloride solution and 0.1 g of the catalyst prepared in Examples 1-2 and the carbon material prepared in Comparative Examples 1-4 were added to an Erlenmeyer flask. The shaker speed was set to 200 r / min, the temperature to 30 °C, and the reaction time to 60 min. The solution was then filtered, and the concentration of total chloride (TC) in the solution was determined by high-performance liquid chromatography (HPLC). The TC removal rate and the catalyst adsorption capacity were calculated. The adsorption performance of tetracycline hydrochloride by the catalyst prepared in Examples 1-2 and the graphite material prepared in Comparative Examples 1-4 is shown in the attached figure. Figure 4 As shown.

[0151] Comparative Examples 3 and 4 show that both pyrolysis and mechanical activation can improve the removal rate of tetracycline hydrochloride from waste graphite, and their removal rates are comparable. Although the specific surface area of ​​activated graphite MG (33.1 m²) is significantly higher... 2 / g) Specific thermally degradable graphite PG (7.5m) 2 The concentration of tetracycline hydrochloride ( / g) is much higher. This is mainly because the binder on the SG surface hinders the binding of tetracycline hydrochloride to the SG surface sites.

[0152] Furthermore, the order in which pyrolysis and mechanical activation are coupled also has a certain impact. The removal rate of tetracycline hydrochloride by the PMG catalyst was significantly improved to 93.9%, higher than the 72% of the MPG catalyst. This may be because the PMG that is pyrolyzed first and then mechanically activated is more porous, and after losing the binder impurities, it is more easily compressed, sheared, and impacted into smaller particles. These smaller particles have a higher specific surface area, much higher than that of MPG.

[0153] 4. Catalytic effect verification experiment

[0154] The experimental system for verifying the catalytic effect of self-doped metals in waste graphite was as follows: In a 250 mg / L tetracycline hydrochloride solution, ① only the catalyst PMG prepared in Example 1 was added; ② only 0.5 vol% hydrogen peroxide was added; ③ the catalyst PMG prepared in Example 1 and 0.5 vol% hydrogen peroxide were added; ④ the catalyst of Example 1 (APMG) after leaching with 2 mol / L sulfuric acid to remove self-doped metal ions was added; ⑤ the catalyst of Example 1 (APMG) after leaching with 2 mol / L sulfuric acid to remove self-doped metal ions and 0.5% vol% hydrogen peroxide were added. The tetracycline hydrochloride concentration was detected by HPLC, and the mineralization rate was detected and calculated using a total organic carbon (TOC) analyzer. The results are as follows: Figure 5 As shown.

[0155] Depend on Figure 5 It can be seen that in the experiment using only PMG, due to the adsorption effect of the catalyst, the removal efficiency of tetracycline hydrochloride reached 41.8%, and the removal rate of total organic carbon (TOC) reached 36.8%. In the system using only hydrogen peroxide without the presence of a catalyst, the removal rate of tetracycline hydrochloride by hydrogen peroxide reached 36.2%, but the mineralization rate was almost 0.

[0156] In experiments using PMG catalysts and hydrogen peroxide, the PMG / hydrogen peroxide system achieved significantly higher removal rates of tetracycline hydrochloride and total organic carbon (TOC), reaching 100% and 53.6%, respectively. The TOC removal rate was much lower than the tetracycline hydrochloride removal rate, attributed to the formation of intermediate products after tetracycline hydrochloride degradation. The addition of PMG significantly promoted the degradation and mineralization of TCC by hydrogen peroxide. This is likely because the doped metals in graphite (such as Fe, Co, Ni, Mn, Cu, etc.) can act as catalytic centers, catalyzing hydrogen peroxide to generate more available strongly oxidizing reactive species, thus promoting the oxidative degradation of TCC molecules.

[0157] Furthermore, in experiments using sulfuric acid to leach the PMG catalyst and hydrogen peroxide after it was doped with metal ions, the removal rate of tetracycline hydrochloride decreased from 100% before acid leaching to 32%, which further verifies the important role of doped metals in catalysis in graphite-containing electrodes.

[0158] 5. pH Adjustment Experiment for Antibiotic Wastewater

[0159] 50 mL of a 250 mg / L tetracycline hydrochloride solution was added to an Erlenmeyer flask. The pH of the solution was adjusted to 2, 3, 5, 7, 9, and 11 using 1 mol / L H₂SO₄ or 1 mol / L NaOH, respectively. The catalyst PMG prepared in Example 1 and 0.5 vol% hydrogen peroxide were then added to the pH-adjusted tetracycline hydrochloride solutions (pH approximately 3–5) and the unadjusted solutions, respectively. The shaker speed was set to 200 rpm, the temperature to 30 °C, and the reaction time to 2 h. The relevant results are attached. Figure 6As shown.

[0160] The catalyst exhibits excellent adsorption and catalytic effects on tetracycline hydrochloride at different pH values. PMG not only possesses adsorption properties but also demonstrates excellent catalytic activity and tetracycline hydrochloride mineralization rate. pH value is one of the important influencing factors in Fenton-like oxidation. The PMG / H2O2 system exhibits high TC removal rates over a wide pH range.

[0161] 6. Catalyst cyclic adsorption-regeneration experiment

[0162] The pH of the tetracycline hydrochloride solution was adjusted to 3 and 5, respectively. 250 mg / L tetracycline hydrochloride solution, the PMG catalyst prepared in Example 1, and 0.5 vol% hydrogen peroxide were added to an Erlenmeyer flask. The shaker speed was set to 200 r / min, the temperature to 30 °C, and the reaction time to 30 min. After 30 min of reaction, the adsorbed PMG was filtered and regenerated by pyrolysis at 350 °C for 1 h. This process was repeated 4–5 times for the next round of experiments. The relevant results are attached. Figure 7 As shown.

[0163] The PMG catalyst in Example 1 demonstrates excellent reusability. Throughout four cycles, regardless of pH 3 or 5, the catalyst maintained extremely high adsorption and catalytic degradation capabilities, exhibiting a tetracycline hydrochloride removal efficiency of over 95% in all cycles. Catalyst regeneration can be achieved simply by heating at medium to low temperatures to decompose the tetracycline hydrochloride. This indicates that the catalyst possesses good reusability and high adsorption and catalytic capacity, demonstrating its potential for commercial application.

[0164] 7. Calculation of TC adsorption capacity

[0165] The catalyst from Example 1 and simulated tetracycline hydrochloride wastewater (100-250 mg / L) were mixed at a certain solid-liquid ratio (m 催化剂 :V 抗生素废水 =0.025g~0.1g:50mL) was added to an Erlenmeyer flask, and the shaker speed was set to 200r / min and the temperature to 30℃. After adsorption, the liquid was filtered through a 0.22μm filter, and the filtrate was collected for HPLC and total organic carbon testing to determine the concentrations of tetracycline hydrochloride and total organic carbon, in order to evaluate the catalytic and mineralization effects of porous graphite on antibiotics.

[0166] Adsorption capacity Q t Press Q t = (ρ0-ρ1)V / m, where Q is calculated. t Let ρt be the adsorption capacity at time t, mg / g; ρ0 be the initial lithium ion concentration in the solution, mg / L; ρ1 be the lithium ion concentration after adsorption, mg / L; m be the mass of the adsorbent, g; and V be the volume of the adsorption solution, L. The results are as follows: Figure 4, 6 As shown in Figures 7 and 8.

[0167] The results showed that the catalyst PMG prepared in Example 1 had high adsorption performance for tetracycline hydrochloride, with an adsorption capacity as high as 209.0 mg / g.

[0168] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0169] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. The use of a catalyst for the catalytic oxidation of tetracycline hydrochloride, characterized in that, The method for preparing the catalyst includes the following steps: The graphite-containing electrodes of waste batteries are crushed to obtain crushed products. Through crushing, large pieces of copper foil are removed to obtain the required waste graphite. The crushed product is sieved to obtain a screened product, wherein the particle size of the screened product is less than 0.1 mm; The crushed product is subjected to pyrolysis treatment to obtain pyrolysis product; The pyrolysis products are activated to obtain a catalyst; The activation treatment includes a mechanical ball milling step; the rotation speed of the mechanical ball milling is 300~700 r / min; the mechanical ball milling time is 30~180 min; The pyrolysis treatment temperature is 350~550℃; the pyrolysis treatment time is 30~60 min.

2. The use according to claim 1, characterized in that, The particle size of the sieved product is less than 0.074 mm.

3. The use according to claim 1 or 2, characterized in that, The pyrolysis process is carried out under vacuum conditions, air conditions, or an inert atmosphere.

4. The use according to claim 3, characterized in that, The inert atmosphere includes one or both of nitrogen atmosphere and argon atmosphere.

5. The use according to claim 1 or 2, characterized in that, The catalyst has an average pore size of 0.4~1 nm and a specific surface area of ​​200~240 m². 2 / g.

Images