A method for preparing fenton reagent based on waste lithium iron phosphate electrode material and application thereof
By preparing Fenton reagent based on waste lithium iron phosphate electrode materials, the problems of recycling waste lithium iron phosphate batteries and treating high-concentration wastewater have been solved, realizing resource utilization and cost reduction, and improving economic and environmental benefits.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV
- Filing Date
- 2024-09-18
- Publication Date
- 2026-07-24
AI Technical Summary
The recycling of waste lithium iron phosphate batteries is costly and has low resource utilization. The hydrometallurgical recycling process generates a large amount of strong acid that is difficult to treat. The treatment of high-concentration wastewater is costly and complex. Existing Fenton reagents require a large amount of iron salts and acids to adjust the pH value.
Using waste lithium iron phosphate electrode materials as the iron source, a divalent iron solution was prepared by high-temperature calcination, dissolution and reduction. This solution was then mixed with hydrogen peroxide to prepare Fenton's reagent. The pH value of the wastewater was adjusted using acid leaching solution to reduce the amount of external strong acid and iron salt used.
It has enabled the resource recycling of waste lithium iron phosphate batteries and the effective degradation of high-concentration wastewater, reducing recycling and treatment costs, reducing pollution, and improving economic and environmental benefits.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid waste resource utilization. This invention relates to a method for preparing Fenton reagent based on waste lithium iron phosphate electrode material and its application. Background Technology
[0002] The primary source of global greenhouse gases is the use of fossil fuels. To achieve energy conservation and emission reduction, it is essential to reduce the use of fossil fuels, especially fossil fuel vehicles. Electric vehicles use batteries to store energy, eliminating the need for fuel combustion, thus effectively reducing carbon emissions, protecting the environment, and curbing global warming. Lithium iron phosphate (LFP) batteries have numerous advantages, including abundant raw materials, low price, non-toxicity, simple production processes, good safety, and good thermal stability, and have become one of the main power sources for electric vehicles in my country. Although LFP batteries account for a significant portion of the power battery market, they are now facing increasing challenges in recycling and reusing retired LFP batteries. If these used LFP batteries are not recycled promptly and effectively, they not only cause serious environmental pollution but also result in a severe waste of resources. However, the complex material composition of LFP batteries requires advanced technology and complex processes to separate and extract valuable metals, leading to high recycling costs. Furthermore, the market value of the recovered iron is extremely low, resulting in poor economic benefits and low recycling rates for LFP batteries. In addition, the current main method for recycling lithium iron phosphate battery materials is hydrometallurgical technology. During the recycling process, a large amount of waste strong acid needs to be further processed, which further increases the cost of recycling waste lithium iron phosphate batteries.
[0003] On the other hand, high-concentration, high-salinity, and recalcitrant wastewater has complex water composition, high organic matter content, and COD generally exceeding 10,000 mg / L. It also typically contains toxic and harmful substances, posing a significant challenge to wastewater treatment in my country and worldwide, severely damaging the environment and ecosystem. Homogeneous Fenton reaction, as an advanced oxidation technology, utilizes Fe²⁺ and H₂O₂ to generate strong oxidizing free radicals to degrade pollutants. It possesses extremely strong non-selective oxidation capabilities, efficiently degrading various organic pollutants. It features rapid reaction speed, wide applicability, and good degradation effect, making it one of the primary treatment methods for high-concentration, highly toxic wastewater. However, the homogeneous Fenton process consumes large amounts of hydrogen peroxide and iron salts, and the optimal reaction pH range typically needs to be controlled between 2.5 and 3, resulting in high operating costs for homogeneous Fenton wastewater treatment. Furthermore, it requires the addition of large amounts of strong acid for pH adjustment.
[0004] On the one hand, the iron in waste lithium iron phosphate batteries is cheap, resulting in low economic recycling value. Random disposal will cause serious solid waste pollution and resource waste. The most common hydrometallurgical recycling technology currently used will also generate waste acid. On the other hand, the existing Fenton reagent degradation of wastewater requires the addition of a large amount of divalent iron and a large amount of acid to adjust the pH, which greatly increases the cost of wastewater treatment. Summary of the Invention
[0005] To overcome the shortcomings of existing technologies and achieve low-cost, high-efficiency recycling of iron from spent lithium iron phosphate batteries and effective degradation of high-concentration wastewater, this invention provides a method for preparing Fenton's reagent based on spent lithium iron phosphate electrode materials and its application, utilizing these materials to treat high-concentration wastewater. Addressing the issues of low iron recovery value, complex separation and extraction processes, and the generation of large amounts of strong acid during recycling, this invention uses solid waste from spent lithium iron phosphate electrode materials as the iron source for preparing Fenton's reagent, avoiding multiple complex purification processes for the metal elements in the spent lithium iron phosphate. Furthermore, the strong acid introduced during the hydrometallurgical recycling of lithium iron phosphate electrode materials can be directly used to control the pH value of the Fenton reaction, thereby achieving resource-based recycling of lithium iron phosphate electrode materials and effective utilization of the waste strong acid. On the other hand, the preparation of Fenton reagent based on waste lithium iron phosphate electrode materials can reduce the amount of iron salt required for the Fenton reaction and reduce or even eliminate the need to add large amounts of strong acid from the outside, thereby significantly reducing the operating cost of Fenton reaction wastewater treatment, realizing "waste treatment with waste", and taking into account the economic and environmental benefits of resource recycling and wastewater treatment of waste lithium iron phosphate batteries.
[0006] The above-mentioned objective of this invention is achieved through the following technical solution: A method for preparing Fenton's reagent based on waste lithium iron phosphate electrode materials, the specific steps of which are as follows: S1. After collecting the waste lithium iron phosphate electrode materials, calcine and oxidize them at high temperature under an oxygen-containing atmosphere. S2. Dissolve the material oxidized in step S1 using a strong acid to obtain a solution containing ferric ions; S3. Add a reducing agent to the solution containing ferric ions obtained in step S2 to convert the ferric ions into ferrous ions to obtain a ferrous solution, which serves as the source of ferrous iron in Fenton's reagent; S4. The ferrous iron solution obtained in step S3 is mixed with hydrogen peroxide to obtain a homogeneous Fenton reagent.
[0007] Furthermore, the waste lithium iron phosphate electrode material in step S1 comes from retired lithium iron phosphate batteries from electric vehicles, communication base stations, and grid energy storage.
[0008] Furthermore, the oxygen-containing atmosphere in step S1 is one or more of air, oxygen and argon, or oxygen and nitrogen. Preferably, the oxygen-containing atmosphere in step S1 is an air atmosphere.
[0009] Furthermore, the high-temperature calcination conditions in step S1 are: calcination time of 1-5 hours and calcination temperature of 500-900℃. Preferably, the calcination time is 1-2 hours and the calcination temperature is 500-700℃.
[0010] Furthermore, the strong acid in step S2 is any one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration of the strong acid is 1-3 mol / L. Preferably, the strong acid in step S2 is sulfuric acid, and the concentration of the sulfuric acid is 2-3 mol / L.
[0011] Furthermore, the liquid-to-solid ratio of the strong acid to lithium iron phosphate in step S2 is 6-10:1. Preferably, the liquid-to-solid ratio of the strong acid to lithium iron phosphate in step S2 is 8-10:1.
[0012] Further, the dissolution conditions in step S2 are: a dissolution temperature of 30~70 ℃, a stirring speed of 100~500 r / min, and a reaction time of 1~5 hours. Preferably, the dissolution conditions in step S2 are: a dissolution temperature of 50~70 ℃, a stirring speed of 200~300 r / min, and a reaction time of 3~5 h.
[0013] Furthermore, the reducing agent added in step S3 is any one or more of iron powder, iron blocks, and iron filings, and the reducing agent reacts with Fe. 3+ The molar ratio is 0.8-1.5:2. Preferably, the reducing agent is iron powder; preferably, the iron powder and Fe... 3+ The molar ratio is 0.9-1.2:2.
[0014] Further, in step S4, the mass ratio of ferrous iron to hydrogen peroxide in the homogeneous Fenton reagent is 1:40-50. Preferably, the mass ratio of ferrous iron to hydrogen peroxide in step S4 is 1:45-50.
[0015] Further, the mixing conditions in step S4 are: a mixing temperature of 10~25 ℃ and a mixing speed of 100~600 r / min. Preferably, the mixing conditions in step S4 are: a mixing temperature of 15~25 ℃ and a mixing speed of 300~600 r / min.
[0016] The present invention also seeks protection for the application of the Fenton reagent prepared by the above preparation method in the treatment of wastewater.
[0017] The specific application is as follows: the prepared homogeneous Fenton reagent is added to phenol wastewater, and the pH of the wastewater is adjusted to 2-4 using the waste strong acid introduced in step S2.
[0018] Furthermore, a preferred strong acid is used to adjust the pH to 2.5-3.
[0019] Furthermore, the wastewater is any one or more of the following: phenolic wastewater, dyeing and printing wastewater, pesticide wastewater, coking wastewater, and landfill leachate.
[0020] Furthermore, the initial TOC value of the wastewater is 95~105 mg / L, more preferably, the initial TOC value of the wastewater is 95~100 mg / L.
[0021] This invention provides a method for preparing Fenton's reagent based on waste lithium iron phosphate electrode materials and its application in wastewater treatment. The waste lithium iron phosphate electrode materials are calcined at high temperature under an oxygen-containing atmosphere; the oxidized lithium iron phosphate is dissolved in a strong acid to obtain a solution containing ferric ions; a reducing agent is added to convert the ferric ions into ferrous ions, which serve as the source of ferrous iron in the Fenton's reagent; further, it is mixed with hydrogen peroxide to obtain a homogeneous Fenton's reagent; the pH of the wastewater is adjusted to the optimal oxidation range using the waste strong acid from leaching the waste lithium iron phosphate. This reagent is then applied to wastewater, achieving mineralization through a homogeneous Fenton reaction.
[0022] The advantages of this invention compared to the prior art are: This invention extracts a high-content iron component from waste lithium iron phosphate electrode materials and uses it as the source of divalent iron in the homogeneous Fenton process. Furthermore, the strong acid contained in the iron ion solution during the iron extraction process can directly adjust the pH of the wastewater to 3. This not only makes full use of the waste strong acid in the acid leaching process and reduces the amount of acid added in the homogeneous Fenton process, but also effectively solves the solid waste pollution and water pollution of waste lithium iron phosphate batteries, realizing the good economic and social application value of "treating waste with waste". Attached Figure Description
[0023] Figure 1 These are SEM images of lithium iron phosphate before and after calcination in Example 1, where Figure a is the SEM image of lithium iron phosphate before calcination; and Figure b is the SEM image of lithium iron phosphate after calcination.
[0024] Figure 2 The results are from the mineralization of p-phenol wastewater in Comparative Examples 1 and 2.
[0025] Figure 3 This is a comparison chart showing the results of mineralization of phenol wastewater by homogeneous Fenton reagent prepared in Examples 1-4.
[0026] Figure 4 This is a simplified process diagram of the preparation method of the present invention. Detailed Implementation
[0027] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.
[0028] Comparative Example 1 0.25 g of ferrous sulfate heptahydrate was mixed with H2O2 (1600 mg / L) and added to 500 mL of 60 mg / L phenol wastewater. Sulfuric acid was added dropwise to adjust the pH to 3. Samples were taken every five minutes, and the supernatant was collected after standing. The removal rate of ferrous sulfate for phenol wastewater was 57.61%.
[0029] Comparative Example 2 0.1 g of commercial lithium iron phosphate cathode material powder was calcined in air at 700°C for 1 h, with an initial temperature of 20°C and a heating rate of 1°C / min. The calcined material was then added to a beaker along with 2 mL of 2.5 mol / L H₂SO₄. The mixture was stirred on a magnetic stirrer at 60°C and 300 r / min for 5 h. The mixture was then filtered to obtain a filtrate containing ferric ions. 0.1 g of iron powder was added to the filtrate and reacted for 30 min, converting the ferric ions to ferrous ions, resulting in a ferrous ion solution. This ferrous ion solution was mixed with 1600 mg / L hydrogen peroxide and added to 500 mL of 60 mg / L phenol wastewater. The pH was adjusted to 3, and samples were taken every five minutes. After settling, the supernatant was collected, yielding a phenol wastewater removal rate of 56.25%. Example 1 0.1 g of waste lithium iron phosphate battery powder (obtained by pulverizing the positive electrode portion of retired lithium iron phosphate batteries from electric vehicles, communication base stations, and grid energy storage) was calcined in air at 600 ℃ for 1 h, with an initial temperature of 20 ℃ and a heating rate of 1 ℃ / min. The calcined lithium iron phosphate was then added to a beaker along with 10 mL of 2.5 mol / L H2SO4. The mixture was placed on a magnetic stirrer and reacted at 60 ℃ and 300 r / min for 4 h. After filtration, a filtrate containing ferric ions was obtained. 0.05 g of iron powder was added to the filtrate and reacted for 30 min, converting the ferric ions in the filtrate to ferrous ions, thus obtaining a ferrous ion solution. The ferrous ion solution was mixed with 5000 mg / L hydrogen peroxide and added to 500 mL of 60 mg / L phenol wastewater. The pH was adjusted to 3, and samples were taken every five minutes. After standing, the supernatant was collected. Example 1
[0030] 0.1 g of waste lithium iron phosphate battery powder (obtained by pulverizing the positive electrode portion of retired lithium iron phosphate batteries from electric vehicles, communication base stations, and grid energy storage) was placed in air and calcined at 700 ℃ for 1 h, with an initial temperature of 20 ℃ and a heating rate of 1 ℃ / min to obtain calcined lithium iron phosphate. The calcined lithium iron phosphate was added to a beaker, along with 2 mL of 2.5 mol / L H2SO4, and reacted on a magnetic stirrer at 60 ℃ and 300 r / min for 5 h. The mixture was then filtered to obtain a filtrate containing ferric ions. 0.1 g of iron powder was added to the filtrate and reacted for 30 min, converting the ferric ions in the filtrate to ferrous ions, thus obtaining a ferrous ion solution. The ferrous ion solution was mixed with 1600 mg / L hydrogen peroxide and added to 500 mL of 60 mg / L phenol wastewater. The pH was adjusted to 2, and samples were taken every five minutes. After standing, the supernatant was collected. Example 2
[0031] 0.05 g of waste lithium iron phosphate battery powder (obtained by pulverizing the positive electrode portion of retired lithium iron phosphate batteries from electric vehicles, communication base stations, and grid energy storage) was calcined in air at 600 °C for 1 h, starting at 20 °C with a heating rate of 1 °C / min. The calcined lithium iron phosphate was then added to a beaker with 0.5 mL of 0.5 mol / L H₂SO₄ and reacted at 60 °C and 300 r / min for 4 h using a magnetic stirrer. The mixture was then filtered to obtain a filtrate containing ferric ions. 0.1 g of iron powder was added to the filtrate and reacted for 30 min, converting the ferric ions to ferrous ions, thus obtaining a ferrous ion solution. This ferrous ion solution was then mixed with 2400 mg / L hydrogen peroxide and added to 500 mL of 600 mol / L H₂SO₄ solution. In phenol wastewater with a concentration of mg / L, the pH was adjusted to 5, and samples were taken every five minutes. After standing, the supernatant was collected. Example 3
[0032] 0.05 g of waste lithium iron phosphate battery powder (obtained by pulverizing the positive electrode portion of retired lithium iron phosphate batteries from electric vehicles, communication base stations, and grid energy storage) was calcined in air at 600 °C for 1 h, with an initial temperature of 20 °C and a heating rate of 1 °C / min. Calcinated lithium iron phosphate was obtained. The calcined lithium iron phosphate was then added to a beaker along with 1 mL of 1.5 mol / L H₂SO₄ and reacted on a magnetic stirrer at 60 °C and 300 r / min for 2 h. The mixture was then filtered to obtain a filtrate containing ferric ions. 0.2 g of iron powder was added to the filtrate and reacted for 60 min, converting the ferric ions to ferrous ions, thus obtaining a ferrous ion solution. This ferrous ion solution was mixed with 1600 mg / L hydrogen peroxide and added to 500 mL of 600 mol / L H₂SO₄ solution. In phenol wastewater with a concentration of mg / L, the pH was adjusted to 4, and samples were taken every five minutes. After standing, the supernatant was collected.
[0033] Comparative Example 1 <![CDATA[The addition amount of FeSO4·7H2O is 0.25 g, the addition amount of H2O2 is 1600 mg / L, and the addition amount of H2SO4 is 0.1 ml (2.5 mol / L)]]> The phenol wastewater concentration was 60 mg / L, the volume was 500 ml, the reaction temperature was room temperature, and the pH of the homogeneous Fenton reaction was adjusted to 3. 1. Commercially available Fenton reagent can effectively degrade phenol wastewater, achieving a TOC degradation rate of 57.61%; 2. It requires the consumption of large amounts of iron salts and sulfuric acid, resulting in high degradation costs. Comparative Example 2 <![CDATA[The usage amount of commercial LFP powder is 0.1 g, the addition amount of iron powder is 0.1 g, the addition amount of H2O2 is 1600 mg / L, and the pH value of phenol wastewater is regulated by using waste acid in LFP acid leaching solution]]> The phenol wastewater concentration was 60 mg / L, the volume was 500 ml, the reaction temperature was room temperature, and the pH of the homogeneous Fenton reaction was adjusted to 3. 1. Fenton's reagent was prepared by simulating waste lithium iron phosphate electrode materials using commercially available lithium iron phosphate powder with simple components, and it was confirmed that this technology can effectively reduce the introduction of iron salts and sulfuric acid; 2. It can effectively reduce phenol wastewater, and the TOC degradation rate of phenol wastewater reached 56.25%, which is close to the degradation effect of commercially available Fenton's reagent. This invention <![CDATA[0.1 g of waste lithium iron phosphate electrode material powder, 0.1 g of iron powder added, 1600 mg / L of H2O2 added, and the pH value of phenol wastewater is adjusted with waste acid in waste LFP acid leaching solution]]> The phenol wastewater concentration was 60 mg / L, the volume was 500 ml, the reaction temperature was room temperature, and the pH of the homogeneous Fenton reaction was adjusted to 3. 1. Using actual waste lithium iron phosphate electrode materials, the iron, nickel, manganese, and aluminum metal elements in the electrode materials do not require multiple purification processes and can be directly used to prepare Fenton's reagent. This effectively solves the problem of low recycling value of waste lithium iron phosphate battery electrode materials and the effective resource utilization of metal elements, and eliminates the need to introduce ferrous sulfate for Fenton's reagent. 2. The sulfuric acid waste liquid in the acid leaching solution of waste lithium iron phosphate is directly used to adjust the pH value of the wastewater, solving the problem of strong acid disposal in lithium iron phosphate recycling, and also ensuring that the homogeneous Fenton reaction does not require the introduction of new sulfuric acid. 3. It can effectively reduce phenol wastewater, with a TOC degradation rate of 54.49%, approaching the degradation effect of commercial Fenton's reagent, proving that this invention has excellent environmental and economic value. The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.
Claims
1. An application of Fenton reagent prepared by a method based on waste lithium iron phosphate electrode material in wastewater treatment, characterized in that, The specific steps for preparing Fenton's reagent are as follows: S1. After collecting the waste lithium iron phosphate electrode materials, calcine and oxidize them at high temperature under an oxygen-containing atmosphere. S2. Dissolve the material oxidized in step S1 using a strong acid to obtain a solution containing ferric ions; S3. Add a reducing agent to the solution containing ferric ions obtained in step S2 to convert ferric ions into ferrous ions to obtain a ferrous ion solution, which serves as the source of ferrous ions in Fenton's reagent; S4. The ferrous ion solution obtained in step S3 is mixed with hydrogen peroxide to obtain a homogeneous Fenton reagent; The high-temperature calcination conditions in step S1 are: calcination time of 1-2 h and calcination temperature of 500-700 ℃; The strong acid in step S2 is any one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the concentration of the strong acid is 1~3 mol / L; The liquid-to-solid ratio of the strong acid to lithium iron phosphate in step S2 is 6-10:1; In step S3, the reducing agent is iron powder; the iron powder reacts with Fe... 3+ The molar ratio is 0.9-1.2:2; The specific application is as follows: the prepared homogeneous Fenton reagent is added to phenol wastewater, and the pH of the wastewater is adjusted to 2-4 using the strong acid introduced in step S2.
2. The application of the Fenton reagent prepared by the method for preparing Fenton reagent based on waste lithium iron phosphate electrode material as described in claim 1 in wastewater treatment, characterized in that, The oxygen-containing atmosphere in step S1 is one or more of air, oxygen and argon, or oxygen and nitrogen.
3. The application of the Fenton reagent prepared by the method for preparing Fenton reagent based on waste lithium iron phosphate electrode material as described in claim 1 in wastewater treatment, characterized in that, The dissolution conditions in step S2 are: dissolution temperature of 30~70 ℃, stirring speed of 100~500 r / min, and reaction time of 1~5 hours.
4. The application of the Fenton reagent prepared by the method for preparing Fenton reagent based on waste lithium iron phosphate electrode material as described in claim 1 in wastewater treatment, characterized in that, In step S4, the mass ratio of ferrous ions to hydrogen peroxide in the homogeneous Fenton reagent is 1:40-50. The mixing conditions in step S4 are: mixing temperature of 10~25 ℃ and mixing stirring speed of 100~600 r / min.