A device for formaldehyde removal by manganese oxide with capacitive effect synergistic triboelectric enhancement

Abstract

A device for removing formaldehyde using manganese oxide with a synergistic effect of capacitance and triboelectric enhancement belongs to the field of formaldehyde removal technology. Two parallel copper meshes are positioned with a gap between them. Between the upper and lower copper meshes, from top to bottom, are a nylon air filter and a manganese oxide / carbon nanoparticle composite material. The nylon air filter is tightly fitted to the upper copper mesh, and the manganese oxide / carbon nanoparticle composite material is tightly fitted to the lower copper mesh. The two copper meshes are sealed with an insulating frame, forming an integrated formaldehyde purification device. During operation, a power source is connected between the upper and lower copper meshes. This allows the surface of the manganese oxide catalyst to become an electron-rich region, promoting the removal of active substances (0... * This process accelerates the decomposition of intermediate products, thereby improving catalyst efficiency and lifespan.

Description

Technical Field

[0001] This invention belongs to the field of formaldehyde removal technology, specifically relating to a device that utilizes capacitance characteristics to enhance electron aggregation through triboelectric power generation, thereby improving the formaldehyde removal efficiency of manganese oxides. Background Technology

[0002] In recent decades, people's quality of life has gradually improved, and interior decoration styles have become increasingly diverse. It is estimated that over 90% of people spend most of their time indoors. However, people are increasingly aware of the air pollution problems caused by interior decoration materials. Formaldehyde (HCHO) is the most significant harmful substance released from interior decoration materials and furniture. When the indoor formaldehyde concentration exceeds 0.1 mg / m³... 3 A concentration of formaldehyde (~0.08 ppm) is considered to exceed the standard. A stable and healthy living environment helps meet people's needs for a better life. Therefore, how to effectively and sustainably reduce indoor formaldehyde concentrations to below the national standard (~0.08 ppm) and minimize potential risks to human health is of great significance in understanding people's growing demand for a better life.

[0003] Transition metal oxides are a promising alternative catalyst. Recent studies have shown that metal cations in transition metal oxides possess the greatest potential for redox catalytic decomposition of formaldehyde due to their d orbitals (3d... 5 4s 2 The unique structure of manganese oxides (MnO) allows for the activation of transitions between different energy levels and the acquisition of variable valence states by outer electrons. x Triboelectric nanogenerators (TNAs) are transition metal oxides considered promising materials for the catalytic oxidation and degradation of formaldehyde due to their high room-temperature catalytic activity, low cost, good stability, and environmental friendliness. The accumulation of intermediates is a significant cause of deactivation in many catalysts, including those used in formaldehyde degradation materials. Heating can effectively remove these intermediates, thereby improving catalyst efficiency and lifespan. The use of clean energy is the future trend, and achieving zero-energy-consumption, room-temperature, low-concentration formaldehyde catalytic oxidation is an urgent challenge. Triboelectric nanogenerators with sustainable energy harvesting capabilities can provide an effective method for directly addressing these issues. Summary of the Invention

[0004] This invention provides a device and method for improving the formaldehyde capture and removal efficiency of manganese oxides by utilizing capacitance characteristics in conjunction with triboelectric power generation to enhance electron aggregation. This method enables the surface of the manganese oxide catalyst to become an electron-rich region, promoting the activity of active substances (0... * The generation of accelerated intermediates decomposes, improves catalyst efficiency and lifespan, and proposes a practical application model.

[0005] A device that utilizes capacitance characteristics to enhance electron aggregation through triboelectric power generation, thereby improving the efficiency of manganese oxide in capturing and removing gaseous formaldehyde, is characterized by a gap between two parallel copper meshes. Between the upper and lower copper meshes, from top to bottom, are placed a nylon air filter and a manganese oxide / carbon nanoparticle composite material. The nylon air filter and the upper copper mesh are tightly fitted together, as are the manganese oxide / carbon nanoparticle composite material and the lower copper mesh. The two copper meshes are sealed around their perimeter with an insulating frame, forming an integrated formaldehyde purification device. During operation, a power source is connected between the upper and lower copper meshes; preferably, the upper copper mesh is connected to the positive terminal of the power source, and the lower copper mesh is connected to the negative terminal.

[0006] The aforementioned manganese oxide / carbon nanocomposite material consists of manganese oxide loaded onto carbon nanomaterials, where the carbon nanomaterials are conductive carbon fibers. The manganese oxide includes Mn. +4 .

[0007] Furthermore, the thickness of the nylon air filter and the manganese oxide / carbon nanocomposite material is 1:1, which is 3mm, and the length dimension in the area direction is at least 30mm, such as 60mm.

[0008] Formaldehyde-containing gas enters through the upper and lower copper meshes, then sequentially passes through a nylon air filter, a manganese oxide / carbon nanocomposite material, and the lower copper mesh. The gas exiting from the lower copper mesh is transformed into carbon dioxide and water. Specifically, when the integrated formaldehyde purification shaft is connected to a DC power supply, due to the capacitance effect, the lower copper mesh accumulates electrons. These accumulated electrons preferentially transfer to the carbon fiber surface in the composite material, resulting in varying electron concentrations on the manganese oxide / carbon nanocomposite material. Under the influence of diffusion, electrons migrate from the carbon fiber surface to the MnOx surface. Furthermore, the electric field promotes charge polarization and redistribution on the MnOx surface, thereby enhancing the adsorption of gaseous reactants. Under the influence of the electric field, more electrons promote the conversion of O2 and H2O into active O* and ·OH, thus accelerating the oxidative decomposition of HCHO and intermediates. Simultaneously, under the blowing of the formaldehyde airflow, the nylon air filter initially vibrates and continuously rubs against the upper copper mesh. Due to the difference in electronegativity between copper and nylon, electrons on the nylon air filter migrate to the surface of the upper copper mesh, continuously replenishing the electrons consumed by the lower copper mesh, thus achieving a long-term catalytic effect on HCHO. Under the influence of electron-rich conditions and an electric field, Mn in manganese oxide... +4 It will be converted to Mn 2+ and Mn 3+ This process generates oxygen vacancies, promoting the formation of O* and the degradation of HCHO. In summary, the introduction of an electric field during the catalytic process in this device can increase the adsorption of reactants and the generation of O* active groups, effectively accelerating the decomposition of intermediate products. At the same time, the presence of triboelectricity enables MnOx to efficiently and sustainably degrade HCHO.

[0009] The operating voltage is 60V.

[0010] The method improved by this invention not only achieves efficient and long-term formaldehyde degradation at room temperature, but also effectively removes dust particles from the air, greatly enhancing air purification capabilities and playing a significant role in protecting human health. We hope that the proposed new working system can be applied to high-efficiency indoor air purifiers, which would also be of great value to the development of indoor air purifiers.

[0011] Advantages of this invention:

[0012] 1. Utilizing the characteristics of capacitance to synergistically generate electricity through triboelectricity enhances electron aggregation and improves the catalytic oxidation and decomposition of formaldehyde by manganese oxides. Nylon air filters preferentially filter dust particles.

[0013] 2. It has a dual-function device that can efficiently remove indoor formaldehyde and dust particles.

[0014] 3. This method can also be used to remove gaseous organic pollutants.

[0015] 4. The entire device is simple and the raw materials are inexpensive, making it suitable for large-scale industrial production.

[0016] 5. It has a wide range of applications and can be used in various devices such as air purifiers and air conditioners. Attached Figure Description

[0017] Figure 1 Schematic diagram of the testing device and its dimensions.

[0018] Figure 2 The principle of capacitor model charging and storing charge.

[0019] Figure 3 Working mechanism of vertical contact separated single-electrode triboelectric nanogenerator

[0020] Figure 4 (a) Open-circuit voltage (V) of a triboelectric nanogenerator formed by copper mesh and nylon oc (a) and (b) short-circuit current (l) sc ).

[0021] Figure 5 (a) Formaldehyde static test efficiency graph and (b) Catalyst lifetime data graph;

[0022] Figure 6 Formaldehyde catalytic oxidation mechanism diagram (a) without using this device and (b) with this device. Detailed Implementation

[0023] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0024] Example 1

[0025] 1. Preparation of manganese oxide / carbon nanocomposite catalysts:

[0026] The preparation method is basically the same as one of my patents (ZL 2021 2 1787325.0). First, manganese oxide is loaded onto conductive fibers, and then a manganese oxide / carbon nanocomposite material with a high specific surface area is prepared using electrochemical deposition. Based on the principle of redox reaction, a constant current electrochemical deposition method is used to prepare the manganese oxide / carbon nanocomposite material by reacting potassium permanganate (KMnO4) with carbon cloth. The specific implementation steps are as follows: 3.9 g of KMnO4 is dissolved in a beaker containing 500 mL of deionized water and stirred for 15 minutes to obtain a 49.3 mM KMnO4 solution. Carbon cloth (CCs, 6×6 cm) 2 The carbon cloth was thoroughly cleaned with ethanol or water, dried, and then fixed onto a polytetrafluoroethylene frame. A carbon cloth sheet was used as the anode of the electrochemical deposition system, and a platinum sheet as the cathode. The DC output power was turned on, the deposition current was 3A, the deposition time was 60 minutes, and the deposition temperature was 65℃. Finally, the carbon cloth was removed, cleaned with deionized water, and dried at 105℃ for 12 hours to obtain the manganese oxide / carbon nanocomposite material.

[0027] 2. Capacitive characteristics synergistically enhance electron aggregation in a manganese oxide formaldehyde removal device:

[0028] The device consists of four components: a copper mesh conductive electrode plate, a nylon air filter, an insulating frame, and a manganese oxide / carbon nanocomposite catalyst. The static testing setup uses polylactic acid (PLA) as the insulating material to support the frame. Two parallel copper meshes are arranged on the insulating frame, spaced 6 mm apart. The manganese oxide / carbon nanocomposite catalyst is tightly integrated into the lower copper mesh, separated from the upper copper mesh by an insulating nylon air filter to form an integrated purification device. Formaldehyde gas and air are driven into the upper copper mesh, first passing through the nylon air purifier filter, then through the manganese oxide / carbon nanocomposite catalyst, and finally exiting from the lower copper mesh. A schematic diagram of the device and its dimensions is shown below. Figure 1 .

[0029] 3. The principle of capacitors storing charge:

[0030] A capacitor is a container that stores electrical charge. It consists of two copper meshes. The copper meshes are conductive; typically, the number of positively and negatively charged particles in a metal is equal, meaning it is electrically neutral. When current flows through the meshes, electrons move from the upper mesh (positive electrode) to the lower mesh (negative electrode) due to the electromotive force. However, because of the dielectric material between the upper and lower meshes, electrons cannot pass through the capacitor. Therefore, once a certain number of electrons accumulate in the lower mesh, the power source lacks sufficient energy to allow new electrons to enter the capacitor, causing it to become fully charged. The plates will then have a net positive charge. An electric field is generated between the upper and lower meshes to maintain the charge on the capacitor. The schematic diagram is shown below. Figure 2 As shown.

[0031] 4. Working mechanism of vertical contact separation single-electrode triboelectric generator:

[0032] The working principle of the vertical contact-separated nano-triboelectric generator can be attributed to the coupling effect of contact electrification and electrostatic induction. Initially, no charge is generated, and there is no potential difference between the two electrodes. When gas flows through the nylon air filter, its surface fibers vibrate, causing the copper mesh and the nylon air filter surfaces to come into contact. Due to the triboelectric effect, charge transfer occurs at the contact points between the two materials. Because the two materials have different electronegativity, electrons from the nylon air filter surface transfer to the upper copper mesh surface, making the upper copper mesh surface negatively charged. This charge is confined to the surface; two equal and opposite charges exist on the same plane, so there is still no potential difference between the upper and lower copper meshes. Figure 3 In section I; when two charged surfaces separate, a potential difference is created between the upper and lower copper meshes, such as... Figure 3 II. When the nylon air filter element returns to its original position completely, the voltage reaches its maximum saturation value, such as... Figure 3 In stages III and IV, the surface of the upper copper mesh will be negatively charged; the open-circuit voltage (V) of the triboelectric nanogenerator formed by the upper copper mesh and nylon... oc ) and short-circuit current (l sc ) and such Figure 4 As shown.

[0033] 5. The working principle of enhancing electron aggregation and improving the formaldehyde removal efficiency of manganese oxides through capacitive characteristics synergistic with triboelectric generation:

[0034] When the integrated formaldehyde purification device is connected to a DC power supply (60V), it is preferable to connect the upper copper mesh to the positive terminal and the lower copper mesh to the negative terminal. Due to the capacitance effect, the lower copper mesh accumulates electrons, which preferentially transfer to the conductive carbon fiber surface. This results in different electron concentrations between the carbon fiber and manganese oxide. Under the influence of diffusion, electrons migrate from the carbon fiber surface to the manganese oxide surface, making the manganese oxide surface an electron-rich region. The redistribution of surface charge polarization of manganese oxide under the action of an electric field enhances the adsorption of HCHO and O2 on the catalyst surface. At this time, electrons can directly promote the formation of active O* groups from O2, thereby promoting the oxidative decomposition of HCHO and intermediates. In addition, electrons can also promote the transformation of high-valence manganese to low-valence manganese, increasing the low-valence manganese component and generating more O*. Simultaneously, the triboelectric generator system composed of copper mesh and nylon causes the upper copper mesh to become negatively charged, continuously replenishing the electrons consumed by the lower copper mesh, achieving long-term catalysis of HCHO. Figure 5 It is worth noting that the upper copper mesh above the catalyst also weakens the negatively charged HCOO. - COO - CO3 2- The adsorption of intermediate products on the catalyst surface was observed. Test results showed that the static removal rate of HCHO increased by 31.3% within 30 minutes and by 51.76% within 2 hours, with a catalyst lifetime of 90 hours and no significant degradation. Figure 6 As shown. In addition, when charged dust particles in the air pass through the nylon air filter, an electric field and charge exist on the surface of the nylon filter, which can achieve electrostatic dust removal. Compared with ordinary nylon air purifier filters without an electric field, the dust removal effect is greatly improved.

Claims

1. A device for removing formaldehyde using manganese oxides with a synergistic effect of capacitance and triboelectricity, characterized in that, There is a gap between two parallel copper meshes. Between the upper and lower copper meshes, from top to bottom, are a nylon air filter and a manganese oxide / carbon nanocomposite material. The nylon air filter is tightly attached to the upper copper mesh, and the manganese oxide / carbon nanocomposite material is tightly attached to the lower copper mesh. The two copper meshes are sealed with an insulating frame, forming an integrated formaldehyde purification device. When working, the upper and lower copper meshes are connected to a DC power supply. The aforementioned manganese oxide / carbon nanocomposite material consists of manganese oxide loaded onto carbon nanomaterials, wherein the carbon nanomaterials are conductive carbon fibers; the manganese oxide includes Mn. 4+ Oxides.

2. The device for removing formaldehyde using capacitive effect synergistic triboelectric enhancement of manganese oxide according to claim 1, characterized in that, The upper copper mesh is connected to the positive terminal of the power supply, and the lower copper mesh is connected to the negative terminal of the power supply.

3. The device for removing formaldehyde using capacitive effect synergistic triboelectric enhancement of manganese oxide according to claim 1, characterized in that, The nylon air filter and the manganese oxide / carbon nanocomposite material have a thickness ratio of 1:1, which is 3 mm, and the length dimension in the area direction is at least 30 mm.

4. The method of operating the apparatus according to any one of claims 1-3, characterized in that, Formaldehyde-containing gas enters through the upper copper mesh, then passes sequentially through a nylon air filter, a manganese oxide / carbon nanocomposite material, and the lower copper mesh. The gas exiting from the lower copper mesh is transformed from formaldehyde into carbon dioxide and water. Specifically, when the integrated formaldehyde purification device is connected to a DC power supply, due to the capacitance effect, the lower copper mesh accumulates electrons. These accumulated electrons preferentially transfer to the surface of the carbon fibers in the composite material, resulting in different electron concentrations on the manganese oxide / carbon nanocomposite material. Under the influence of diffusion driving force, electrons migrate from the carbon fiber surface to the MnOx surface. Furthermore, the electric field promotes the migration of MnOx... The surface charge polarization and redistribution of x enhance the adsorption of gaseous reactants. Under the influence of the electric field, more electrons promote the conversion of O2 and H2O into active O* and •OH, thereby accelerating the oxidative decomposition of HCHO and intermediates. Simultaneously, under the blowing of the formaldehyde gas flow, the nylon air filter initially vibrates and continuously rubs against the upper copper mesh. Due to the difference in electronegativity between copper and nylon, electrons on the nylon air filter migrate to the surface of the upper copper mesh, continuously replenishing the electrons consumed by the lower copper mesh, achieving a long-term catalytic effect on HCHO. Under the influence of the electron-rich environment and the electric field, Mn in manganese oxide... 4+ It will be converted to Mn 2+ and Mn 3+ It also generates oxygen vacancies, promoting the generation of O* and the degradation of HCHO.

5. The method according to claim 4, characterized in that, The operating voltage is 60V.

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