A method for electrosynthesizing hydrogen peroxide from waste electronic ceramics and its application

Abstract

This invention discloses a method and application for the electrosynthesis of hydrogen peroxide (H2O2) from waste electronic ceramics. The waste electronic ceramics are used as two-electron oxygen reduction catalysts to synthesize H2O2 via an electrocatalytic reaction in an alkaline electrolyte. The waste electronic ceramics are perovskite-phase lead zirconate titanate piezoelectric ceramics and / or tungsten bronze-phase lead metaniobate piezoelectric ceramics. This invention achieves high-value utilization of electronic hazardous waste while solving the dual problems of high cost of traditional catalysts and solid waste pollution. Furthermore, by utilizing the in-situ generated H2O2 coupled with the Fenton reaction, the removal rate of pollutants such as methyl orange and carmine can reach 85%-100%.

Description

Technical Field

[0001] This invention relates to the fields of solid waste resource utilization and electrocatalysis technology, specifically to a method and application of electrosynthesizing hydrogen peroxide using waste electronic ceramics. Background Technology

[0002] Hydrogen peroxide (H2O2) is an oxidant widely used in wastewater treatment, chemical synthesis, medical and health applications, paper bleaching, and semiconductor processing. Currently, existing technologies mainly use the anthraquinone process to produce H2O2. While this process can achieve large-scale production, it suffers from significant drawbacks such as a lengthy process, high equipment investment, large amounts of organic waste, and high carbon emissions. Furthermore, H2O2 is chemically unstable, posing safety risks during long-distance storage and transportation. Therefore, there is an urgent need to develop on-site distributed preparation processes. The electrochemical two-electron oxygen reduction reaction (2e...) - Electrocatalytic oxygen reduction (ORR) uses air and water as raw materials to synthesize H2O2 in situ at room temperature and pressure using renewable electricity, offering advantages such as green raw materials, mild conditions, and zero pollution. However, the ORR faces intense competition between the two-electron pathway (generating H2O2) and the four-electron pathway (generating H2O), both sharing the *OOH intermediate. The adsorption strength of the catalyst on this intermediate determines the reaction direction. Therefore, achieving highly selective H2O2 synthesis requires precise control of the catalyst's adsorption energy and avoidance of *OOH bond breakage.

[0003] There are 2e - ORR catalyst systems all suffer from insurmountable bottlenecks. While noble metal-based catalysts (such as platinum-mercury alloys) exhibit excellent activity and selectivity, their large-scale application is limited by resource scarcity and high cost. Carbon-based catalysts are less expensive, but their structure-activity relationships at active sites are unclear, and they are easily corroded by free radicals in strongly oxidizing environments, resulting in poor long-term stability. Single-atom and transition metal-nitrogen-carbon (MNC) catalysts, although possessing high atom utilization, are prone to metal leaching and aggregation during long-term electrolysis, and their carbon skeletons are easily oxidized and degraded, leading to rapid performance degradation. The problem with existing non-noble metal catalytic systems lies in the widespread structural instability of active sites under strong oxidizing and high-potential conditions. There is a lack of intrinsically high-activity, stable-crystal-structure, and inexpensive, readily available 2e-electrolyte catalysts. - ORR catalyst.

[0004] On the other hand, electronic ceramics such as lead zirconate titanate (PZT) and lead metaniobate (PNB) are core materials in the microelectronics industry. Their production process generates a large amount of scrap and defective products, with waste accounting for 30%-50%. These waste electronic ceramics are classified as hazardous solid waste: firstly, their high lead content means that simple landfilling or open-air storage will lead to lead ion leaching, severely polluting soil and groundwater; secondly, the waste is rich in strategic metals such as zirconium, titanium, and niobium. Traditional recycling processes, which employ physical sorting or high-temperature remelting, are energy-intensive, have low added value, and are economically unsustainable, making industrialization difficult. Furthermore, it is generally believed in the field that lead-containing materials will leach large amounts of lead ions under electroreduction conditions, constituting secondary pollution, and are therefore excluded from electrocatalyst research.

[0005] In summary, there are two independent but interconnected technical problems in the existing technology: the green synthesis of H2O2 lacks a low-cost and highly stable electrocatalytic system; and the disposal methods for waste lead-containing electronic ceramics are outdated, causing environmental pollution and resource waste. Summary of the Invention

[0006] The purpose of this invention is to provide a method and application for the electrosynthesis of H2O2 from waste electronic ceramics, which can not only solve the environmental pollution problem of waste electronic solid waste (especially lead-containing PZT and PNB-based ceramics), but also provide a low-cost, high-stability H2O2 synthesis method. - ORR catalyst.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] The first aspect of this invention provides a method for electrosynthesizing H2O2 using waste electronic ceramics, comprising the following steps: using waste electronic ceramics as a two-electron oxygen reduction (2e... - ORR catalyst is used to synthesize H2O2 through electrocatalytic reaction in alkaline electrolyte; the waste electronic ceramics are perovskite phase lead zirconate titanate (PZT) piezoelectric ceramics and / or tungsten bronze phase lead metaniobate (PNB) piezoelectric ceramics.

[0009] This invention directly converts waste commercial electronic ceramics into electrocatalysts (2e - ORR catalysts, taking PZT ceramics as an example, effectively isolate the multi-metal sites (Pb, Zr, Ti) in their perovskite structure from oxygen atoms. Through their specific adsorption capacity for each reactant / intermediate (O2 and *OOH), they can precisely inhibit the breaking of O2 / O2 bonds, thereby achieving highly selective 2e ... - ORR exhibits excellent in-situ synthesis performance of H2O2, and the prepared H2O2 can be applied to the efficient treatment of wastewater containing different pollutants.

[0010] Furthermore, the waste electronic ceramics are directly derived from waste products generated by industrial electronic ceramic production lines. Before use, they only undergo physical crushing and grinding, without the need for high-temperature calcination or chemical doping modification.

[0011] Furthermore, the lead zirconate titanate piezoelectric ceramic is selected from PZT-4 type and / or PZT-8 type.

[0012] Further, the atomic ratio of Pb, Zr, Ti, O, and doping elements in the lead zirconate titanate piezoelectric ceramic is 1:(0.42-0.58):(0.44-0.51):3:(0.002-0.01), and the doping elements are one or more of Mn, Fe, Co, and Ni; the atomic ratio of Pb, Nb, O, Ba, and W in the lead metaniobate piezoelectric ceramic is (0.7-1.0):(1.8-2.0):6:(0.1-0.3):(0.1-0.2).

[0013] Furthermore, the method for electrosynthesizing H2O2 using waste electronic ceramics includes the following steps:

[0014] (1) Physically crush or grind waste electronic ceramics into ceramic powder;

[0015] (2) The ceramic powder is mixed evenly with conductive carbon black, binder and dispersant to prepare electrode slurry;

[0016] (3) The electrode slurry is loaded onto the surface of the gas diffusion layer and dried to obtain a gas diffusion electrode;

[0017] (4) Using the gas diffusion electrode as the cathode, oxygen is introduced into the cathode in an alkaline electrolyte, and an electrocatalytic reaction is carried out under constant current or constant potential conditions to generate H2O2 in situ.

[0018] Further, in step (1), the waste electronic ceramics are mechanically crushed until micron-sized ceramic powder is formed.

[0019] Further, in step (2), the conductive carbon black is Ketjen black, and the model can be EC-600JD, used to promote 2e - Electron transport in the ORR reaction.

[0020] Further, in step (2), the adhesive is a Nafion perfluorosulfonic acid resin solution, and the dispersant is ethanol or water.

[0021] Further, in step (2), the mass ratio of the ceramic powder to the conductive carbon black is (4-5):(0.5-1).

[0022] Further, in step (3), the gas diffusion layer is carbon paper or carbon cloth; the loading amount of ceramic powder on the surface of the gas diffusion layer is 0.1-1.0 mg·cm³. -2 .

[0023] Further, in step (4), the alkaline electrolyte is a potassium hydroxide (KOH) solution with a concentration of 0.1-1.0 M.

[0024] Furthermore, in step (4), the current density of the electrocatalytic reaction is 50-150 mA·cm⁻¹. -2 .

[0025] Furthermore, in step (4), the electrocatalytic reaction is carried out in a flow cell, and the flow rate of the alkaline electrolyte is 15-35 mL·min. -1 The oxygen flow rate is 20-40 mL / min. -1 Under these conditions, the ceramic powder acts as 2e. - The ORR catalyst operates continuously and stably for no less than 96 hours, and the reaction Faraday efficiency is maintained above 85%.

[0026] The second aspect of the present invention provides an application of electrosynthesizing H2O2 from waste electronic ceramics, wherein the H2O2 synthesized by the method described in the first aspect is used to degrade organic pollutants in wastewater.

[0027] Furthermore, the organic pollutants include one or more of organic dyes, phenols, and antibiotics. The organic dyes include methyl orange and / or carmine, the phenols include bisphenol A and / or 4-chlorophenol, and the antibiotics include tetracycline and / or norfloxacin.

[0028] Furthermore, ferrous ions (Fe2+) are added to the wastewater to be treated. 2+ ) reagents.

[0029] This invention combines H2O2 generated in situ during electrocatalysis with Fe 2+ It constitutes the Fenton system, used to degrade organic pollutants in wastewater.

[0030] The above-described technical solution of the present invention has the following beneficial effects:

[0031] 1. This invention directly collects waste products from the industrial electronic ceramics production process as raw materials, particularly lead zirconate titanate piezoelectric ceramics with a pure-phase perovskite structure (such as commercial PZT-4 and PZT-8 piezoelectric ceramic materials), which can be used as electrocatalysts after only mechanical crushing or grinding. This catalyst exhibits excellent 2e⁻ activity in alkaline media. -The method exhibits high ORR selectivity (approximately 90%) and stability. Furthermore, it demonstrates broad applicability, extending to other crystalline phases of waste electronic ceramics, such as lead niobate piezoelectric ceramics in the tungsten bronze phase, showing promising prospects for large-scale application.

[0032] 2. This invention achieves high-value utilization of electronic hazardous waste, while simultaneously solving the dual problems of high cost of traditional catalysts and solid waste pollution. In a flow cell, at 100 mA·cm⁻¹ -2 The device operated continuously at high current density for 96 hours, maintaining a stable Faraday efficiency of around 85%, with lead leaching concentrations far below national standards. Life cycle assessment further confirmed that the electrochemical solid waste recycling strategy of this invention is significantly superior to the traditional anthraquinone H2O2 synthesis route in several key ecological and environmental indicators (such as CO2 emissions). Furthermore, by utilizing in-situ generated H2O2 coupled with the Fenton reaction, the removal rate of pollutants such as methyl orange and carmine can reach 85%-100%. Attached Figure Description

[0033] Figure 1 The figure shows the test results of the oxygen reduction reaction of the rotating ring-disk electrode in Test Example 1; where a is the curve of the ring current (top figure) and disk current density (bottom figure) of the rotating ring-disk electrode, b is the H2O2 selectivity curve, and c is the electron transfer number curve.

[0034] Figure 2 The figure shows the long-term stability test results of the gas diffusion electrode flow cell system constructed in Example 1.

[0035] Figure 3 The graph shows the test results of the organic pollutant degradation performance of the in-situ electrosynthesis of H2O2 coupled with the Fenton reaction in Test Example 3; where a is a bar chart of pollutant removal rate and b is a comparison photo of pollutant degradation before and after.

[0036] Figure 4 This is a comparative analysis chart of the environmental impacts of hydrogen peroxide prepared using the traditional anthraquinone cycle method in Belgium, Germany, France, and the Netherlands, and constructed using the electrochemical synthesis method of this invention. Among them, a is a sector evaluation chart of three types of environmental assessment indicators: ecosystem damage, human health damage, and resource consumption and depletion, and b is a bar chart comparing carbon emissions. Detailed Implementation

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0039] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0040] The PZT-4 type waste electronic ceramics (trace Mn-doped PZT type electronic ceramics) used in the following examples are defective products produced during the preparation of PZT-4 type electronic ceramics at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, with an atomic ratio of Pb, Zr, Ti, O, and Mn of 1:0.56:0.44:3:0.006; the PNB type waste electronic ceramics are defective products produced during the preparation of PNB type electronic ceramics at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, with an atomic ratio of Pb, Nb, O, Ba, and W of 0.9:1.8:6:0.1:0.2; the PZT-8 type electronic ceramics (trace Fe-doped PZT type electronic ceramics) are defective products produced during the preparation of PZT-8 type electronic ceramics at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, with an atomic ratio of Pb, Zr, Ti, O, and Fe of 1:0.53:0.462:3:0.008.

[0041] Example 1

[0042] A method for electrosynthesizing H2O2 using PZT-4 type waste electronic ceramics includes the following steps:

[0043] (1) PZT-4 type waste electronic ceramics were placed in a mortar and manually ground through a 200-mesh sieve to make ceramic powder;

[0044] (2) Place 4.5 mg of ceramic powder and 0.5 mg of Ketjen Black (EC-600JD) powder in a centrifuge tube, add 100 μL of 5 wt.% Nafion solution and 900 μL of anhydrous ethanol, and sonicate the mixture in an ice-water bath for 30 min until a uniformly dispersed black electrode slurry is formed.

[0045] (3) The electrode paste was loaded onto the surface of carbon paper (TGP-H-060) using a spraying method, and the loading amount of ceramic powder on the carbon paper surface was controlled to be 0.5 mg·cm³. -2 The gas diffusion electrode was prepared by natural drying.

[0046] (4) Construct a gas diffusion electrode flow cell system with a gas diffusion electrode as the cathode, commercial nickel foam as the anode, and an anion exchange membrane (ASTOM ASE) as the diaphragm, and use polytetrafluoroethylene gaskets for sealing assembly; prepare 1 M KOH solution as the cathode and anode electrolytes respectively, and control the cathode electrolyte flow rate to 25 mL·min using a peristaltic pump. -1 High-purity oxygen (99.999%) is introduced into the cathode at a flow rate controlled at 30 mL / min. -1 In constant current mode (100 mA·cm) -2 An electrocatalytic reaction is carried out under these conditions to generate H2O2 in situ.

[0047] According to Pb(Zr) 0.5 Ti 0.5 Pb3O4, ZrO2, and TiO2 raw materials were weighed according to the stoichiometric ratio of O3, and then ball-milled, calcined at 860 ℃, and sintered at 1240 ℃ to obtain a comparative sample. XRD test results showed that the PZT-4 type waste electronic ceramics completely matched the spectrum of the standard card PDF#33-0784, with no impurity peaks appearing; scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) mapping results showed that the atomic ratio of Pb, Zr, and Ti in the PZT-4 type waste electronic ceramics was approximately 1:0.56:0.44, and the elemental distribution was uniform, proving that the waste electronic ceramics still retain a complete perovskite lattice structure.

[0048] Example 2

[0049] A method for electrosynthesizing H2O2 using PNB-type waste electronic ceramics is basically the same as that in Example 1, except that in step (1), PZT-4 type waste electronic ceramics are replaced with PNB-type waste electronic ceramics.

[0050] Example 3

[0051] A method for electrosynthesizing H2O2 using PZT-8 type waste electronic ceramics is basically the same as that in Example 1, except that in step (1), PZT-4 type waste electronic ceramics are replaced with PZT-8 type waste electronic ceramics.

[0052] Test Example 1

[0053] Linear sweep voltammetry using a rotating ring-disk electrode (RRDE) was performed on different waste electronic ceramics to evaluate their 2e2 content under alkaline conditions. - The electrocatalytic performance of ORR was evaluated to assess its ability to electrosynthesize H2O2.

[0054] The test method was as follows: 6.20 μL of the electrode paste from Examples 1, 2, and 3 were respectively drop-coated onto an area of ​​0.1256 cm².2 The glassy carbon rotating ring disk electrode, after being dried by an infrared lamp, was placed in an oxygen-saturated 0.1 M KOH solution and scanned at a rate of 10 mV·s. -1 The test was conducted at a speed of 1600 rpm.

[0055] Test results are as follows Figure 1 As shown, the disk current density of the PZT-4 catalyst is >2.25 mA·cm² at 0 V vs. reversible hydrogen electrode (RHE) potential. -2 The selectivity of H2O2 is as high as 90%, and the number of electrons transferred is n≈2.1.

[0056] Test Example 2

[0057] Long-term stability tests were conducted on the gas diffusion electrode flow cell system constructed in Example 1 at 100 mA·cm⁻¹. -2 The electrolyte was continuously run for 96 hours under constant current density conditions, with samples taken every 12 hours during which the H2O2 concentration in the electrolyte was determined by potassium permanganate titration.

[0058] Test results are as follows Figure 2 As shown, the PZT-4 catalyst maintained a stable operating potential throughout the entire operating cycle, and the reaction Faraday efficiency remained above 85% without significant decay, demonstrating excellent long-term catalytic performance.

[0059] After the reaction was completed, the electrolyte was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the lead (Pb) leaching concentration was only 3.03 μg / L, which is far below the lead discharge limit for industrial wastewater (0.2 mg / L) specified in GB 39731-2020. This indicates that the catalyst achieved safe encapsulation of heavy metals during the electrochemical reaction and has good environmental friendliness.

[0060] Application Example 1

[0061] An application of electrosynthesizing H2O2 using waste electronic ceramics, following step (4) in Example 1, constructs a gas diffusion electrode flow cell system, operating in constant current mode (100 mA·cm). -2 An electrocatalytic reaction was carried out under [a specific environment / condition], and the H2O2 generated in situ was passed into simulated wastewater with pH=3. The simulated wastewater contained one or more pollutants selected from methyl orange, carmine, bisphenol A, 4-chlorophenol, and norfloxacin, with each pollutant having a concentration of 10 mg·L⁻¹. -1 Fe was added to the simulated wastewater. 2+ Construct a Fenton reaction system to allow Fe within the system 2+ When the concentration reaches 2 mM, it triggers the Fenton oxidation reaction to degrade organic pollutants.

[0062] Test Example 3

[0063] Degradation tests were conducted on various organic pollutants using the Fenton reaction system constructed in Application Example 1, and the results are as follows: Figure 3 As shown.

[0064] Figure 3 Figure a shows the reaction under the same Fenton reaction conditions (Fe). 2+ The removal rates of carmine and methyl orange were measured at a concentration of 2 mM and a reaction time of 60 min. The removal rate of carmine was close to 100%, and the removal rate of methyl orange was approximately 85%, demonstrating that the system has a high efficiency in degrading different types of pollutants. Figure 3 Figure b visually demonstrates the color changes of simulated wastewater containing carmine and methyl orange before and after the Fenton reaction. The simulated wastewater containing carmine fades from its initial color before the reaction to become clear, while the simulated wastewater containing methyl orange changes from yellow to colorless, further verifying the effective degradation of pollutants.

[0065] Test Example 4

[0066] Life cycle environmental impact assessment (LCA) tests were conducted on the traditional anthraquinone recycling method and the waste ceramic-electrochemical method of this invention. Based on the process database of industrial hydrogen peroxide production in the four EU countries of Belgium, Germany, France and the Netherlands, a quantitative comparison of the environmental load of the two H2O2 production routes was carried out, which was divided into two major modules: comprehensive environmental damage multi-dimensional assessment and quantitative comparison of carbon emissions.

[0067] Test results are as follows Figure 4 As shown, Figure 4 Using three environmental assessment indicators—ecological system damage, human health damage, and resource consumption—a comprehensive comparison was made between the environmental load of the traditional anthraquinone cycle process and the electrochemical H2O2 synthesis process. The results showed that the comprehensive negative environmental impact of the electrochemical H2O2 synthesis process was significantly lower than that of the traditional anthraquinone cycle process across all three assessment dimensions. Figure 4 The quantitative analysis of the carbon emission differences between the industrial anthraquinone recycling method in four EU countries and the waste ceramic-electrochemical method of this invention shows that the carbon emissions of the traditional anthraquinone recycling process in Belgium, Germany, France, and the Netherlands are much higher than those of the electrochemical synthesis process of this invention, further confirming the outstanding advantages of the electrosynthesis H2O2 process of this invention in terms of low carbon emissions and low environmental impact.

[0068] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for electrosynthesizing H2O2 using waste electronic ceramics, characterized in that, The process includes the following steps: using waste electronic ceramics as a two-electron oxygen reduction catalyst to synthesize H2O2 through an electrocatalytic reaction in an alkaline electrolyte; the waste electronic ceramics are perovskite phase lead zirconate titanate piezoelectric ceramics and / or tungsten bronze phase lead metaniobate piezoelectric ceramics.

2. The method according to claim 1, characterized in that, The atomic ratio of Pb, Zr, Ti, O, and doping elements in the lead zirconate titanate piezoelectric ceramic is 1:(0.42-0.58):(0.44-0.51):3:(0.002-0.01), and the doping elements are one or more of Mn, Fe, Co, and Ni; the atomic ratio of Pb, Nb, O, Ba, and W in the lead metaniobate piezoelectric ceramic is (0.7-1.0):(1.8-2.0):6:(0.1-0.3):(0.1-0.2).

3. The method according to claim 1 or 2, characterized in that, Includes the following steps: (1) Physically crush or grind waste electronic ceramics into ceramic powder; (2) The ceramic powder is mixed evenly with conductive carbon black, binder and dispersant to prepare electrode slurry; (3) The electrode slurry is loaded onto the surface of the gas diffusion layer and dried to obtain a gas diffusion electrode; (4) Using the gas diffusion electrode as the cathode, oxygen is introduced into the cathode in an alkaline electrolyte, and an electrocatalytic reaction is carried out under constant current or constant potential conditions to generate H2O2 in situ.

4. The method according to claim 3, characterized in that, In step (2), the conductive carbon black is Ketjen black; the binder is a perfluorosulfonic acid resin solution; the dispersant is ethanol or water; and the mass ratio of the ceramic powder to the conductive carbon black is (4-5):(0.5-1).

5. The method according to claim 3, characterized in that, In step (3), the gas diffusion layer is carbon paper or carbon cloth; the loading amount of the ceramic powder on the surface of the gas diffusion layer is 0.1-1.0 mg·cm -2 .

6. The method according to claim 3, characterized in that, In step (4), the current density of the electrocatalytic reaction is 50-150 mA-cm -2 .

7. The method according to claim 3, characterized in that, In step (4), the electrocatalytic reaction is carried out in a flow cell, the flow rate of the alkaline electrolyte is 15-35 mL·min -1 , and the oxygen flow rate is 20-40 mL·min -1 .

8. An application of electrosynthesizing H2O2 from waste electronic ceramics, characterized in that, The H2O2 synthesized by the method described in any one of claims 1-7 is used to degrade organic pollutants in wastewater.

9. The application according to claim 8, characterized in that, The organic pollutants include one or more of the following: organic dyes, phenols, and antibiotics. The organic dyes include methyl orange and / or carmine. The phenols include bisphenol A and / or 4-chlorophenol. The antibiotics include tetracycline and / or norfloxacin.

10. The application according to claim 8, characterized in that, Add a reagent containing ferrous ions to the wastewater to be treated.

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