A microplastic degrading agent for water, its preparation method and application

Abstract

This invention discloses a microplastic degrading agent for water, its preparation method, and its application. The microplastic degrading agent comprises a first metal component, a second metal component, and a third metal component. The first metal component is selected from one or more of cerium, lanthanum, and gadolinium; the second metal component is selected from one or more of iron, titanium, and manganese; and the third metal component is selected from one or more of gallium, indium, and tin. The microplastic degrading agent of this invention can efficiently degrade microplastics in water, exhibiting characteristics such as low degradation temperature, high reactivity, and near-neutral pH in the water. Furthermore, the reaction process is simple and suitable for industrial-scale batch operation.

Description

Technical Field

[0001] This invention belongs to the field of microplastic treatment technology, specifically relating to a microplastic degrading agent for water bodies, its preparation method, and its application. Background Technology

[0002] Plastic products are widely used in today's society, with an annual global production exceeding 3 × 10⁻⁶. 8 tons, and at 0.2×10 8 The rate of increase is tonnes per year. Due to the large-scale production and use, plastic products inevitably enter various aquatic environments. It is estimated that more than 2.5 × 10⁻⁶ tons of plastic are floating on the global ocean surface. 5 Tons of plastic waste, through physical, photodegradation, and biodegradation, further decomposes into microplastics with a diameter of less than 5 millimeters. Microplastics are diverse, and categorized by material, they mainly include polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polyethylene terephthalate (PET). Microplastics undergo a series of migrations and transformations in water. Due to their lower density than water, they float or remain suspended in various aquatic environments, spreading under the influence of wind, waves, and ocean currents. Over long-term exposure to the aquatic environment, the surface characteristics of hydrophobic microplastics become complex, easily adsorbing organic and metallic chemical pollutants, which can then be ingested by aquatic organisms, harming their health and safety. Furthermore, human consumption of aquatic organisms containing microplastic pollutants can trigger a series of adverse physiological reactions.

[0003] Currently, the degradation technologies for plastic products mainly target virgin plastics and their compounds, and are primarily used for the degradation of solid plastic products. There is a lack of effective methods for degrading secondary microplastics in water bodies, which is one of the key technologies that urgently needs to be solved.

[0004] CN111825241A discloses a method for treating microplastic pollutants based on micro / nano motor materials. The method includes: adding micro / nano motor materials to wastewater to be treated, then adding hydrogen peroxide to the wastewater to initiate the treatment process. The micro / nano motor materials undergo a catalytic reaction in the water to be treated, continuously generating micro / nano bubbles, which drive pollutants in the water to float to the surface and accumulate in the bubble foam phase. The foam phase is then separated from the wastewater, achieving the purpose of treating microplastic pollutants; wherein the outer diameter of the micro / nano bubbles is 20 nm to 5000 μm. This method utilizes the self-driven motion and self-stirring ability of micro-nano motors to generate microbubbles at high speed, achieving the adsorption-bubble separation process of suspended pollutants in water. However, this method separates microplastics from wastewater through bubble adsorption and then treats the microplastics. It cannot directly degrade plastics in water. Moreover, the method uses iron oxide powder as the base material and grows manganese dioxide through hydrothermal means. The bonding force between the two is weak, meaning the loading of manganese dioxide as a catalyst component is limited, and it is prone to detachment after long-term use. At the same time, there will be a lot of loss of iron oxide base material, meaning the lifespan of the degradation agent is limited.

[0005] CN111514868A discloses a magnetic carbon nanotube, its preparation method, and its application in removing microplastics from water. This method uses a combination of chemical deposition and high-temperature calcination to prepare magnetic carbon nanotubes. The synthesized magnetic carbon nanotubes are then added to water containing microplastics. After sufficient contact, the magnetic carbon nanotubes are adsorbed onto the surface of the microplastics, which can then be removed from the water using a permanent magnet. The mixture of microplastics and magnetic carbon nanotubes is then placed in a tube furnace and subjected to high-temperature treatment under a nitrogen atmosphere. The microplastics are thermally decomposed into gases, thus removing them. However, the iron compounds adhering to the carbon nanotubes are easily lost during recycling. After four cycles, the microplastic removal rate decreases by about 15%, which is not conducive to industrial application. Furthermore, this method requires combining high-temperature calcination with the microplastic removal process, which not only increases energy consumption but also fails to achieve a one-step microplastic removal method. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a microplastic degrading agent for water, its preparation method, and its application. The method of this invention can efficiently degrade microplastics in water, featuring low degradation temperature, high reactivity, and near-neutral pH in the water. Furthermore, the reaction process is simple and suitable for industrial-scale batch operation.

[0007] The first aspect of the present invention provides a microplastic degrading agent for water, comprising a first metal component, a second metal component and a third metal component, wherein the first metal component is selected from one or more of cerium, lanthanum and gadolinium, preferably gadolinium; the second metal component is selected from one or more of iron, titanium and manganese, preferably titanium; and the third metal component is selected from one or more of gallium, indium and tin, preferably indium.

[0008] Furthermore, the general formula for microplastic degrading agents is X a Y b Z c O x Where X is the first metal component, Y is the second metal component, Z is the third metal component, a, b, and c represent the atomic ratios of X, Y, and Z, respectively, and x is the total number of oxygen atoms required to satisfy the valence of other elements.

[0009] Furthermore, based on the molar amounts of the metal elements contained in each component, the molar ratio of the first metal component, the second metal component, and the third metal component is 1:(0.05~0.5):(0.01~0.1), preferably 1:(0.08~0.35):(0.03~0.07).

[0010] Furthermore, the degrading agent belongs to the orthorhombic crystal system, and the components are tightly bound together by covalent bonds.

[0011] Furthermore, the specific surface area of ​​the degrading agent is 53 m². 2 / g~68m 2 / g, pore volume is 2.75cm³ 3 / g~3.56cm 3 / g.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned microplastic degrading agent in water, comprising the following steps:

[0013] (1) Prepare a mixed metal salt solution containing a first metal component, a second metal component and a third metal group, and then carry out a precipitation reaction with sodium hydroxide solution;

[0014] (2) The mixture after precipitation reaction in step (1) is subjected to solid-liquid separation, washing, drying and calcination to obtain the degradation agent.

[0015] Further, the concentration of the mixed metal salt solution in step (1) is 0.1 mol / L to 0.8 mol / L, preferably 0.35 mol / L to 0.65 mol / L.

[0016] Further, the molar ratio of the first metal component precursor, the second metal component precursor and the third metal component precursor in step (1) is 1:(0.04~0.6):(0.008~0.12), preferably 1:(0.07~0.37):(0.027~0.08).

[0017] Further, in step (1), the first metal component precursor is selected from one or more of cerium nitrate, lanthanum nitrate and gadolinium nitrate, preferably gadolinium nitrate; the second metal component precursor is selected from one or more of ferrous sulfate, titanyl sulfate and manganese sulfate, preferably titanyl sulfate; the third metal component precursor is selected from one or more of gallium nitrate, indium nitrate and tin nitrate, preferably indium nitrate.

[0018] Further, the mass ratio of the mixed metal salt solution to the sodium hydroxide solution in step (1) is 1:(0.3-2.5), preferably 1:(0.8-1.5).

[0019] Further, the concentration of the sodium hydroxide solution in step (1) is 0.5 mol / L to 2.5 mol / L, preferably 0.8 mol / L to 1.2 mol / L.

[0020] Furthermore, the solvent water in the mixed metal salt solution and sodium hydroxide solution in step (1) is selected from one or more of deionized water, distilled water, and purified water, with deionized water being preferred.

[0021] Further, the precipitation reaction temperature in step (1) is 30℃~90℃, preferably 50℃~70℃, and the precipitation reaction time is 0.5h~8h, preferably 2h~5h.

[0022] Furthermore, the solid-liquid separation and washing described in step (2) can be carried out in a conventional manner in the art, such as solid-liquid separation by vacuum filtration and washing by repeated rinsing with deionized water.

[0023] Further, the drying temperature in step (2) is 80℃~150℃, preferably 100℃~120℃, and the drying time is 10h~30h, preferably 16h~25h.

[0024] Further, the roasting temperature in step (2) is 300℃~700℃, preferably 450℃~550℃, and the roasting time is 1h~8h, preferably 3h~5h.

[0025] The third aspect of the present invention provides the application of the above-mentioned microplastic degrading agent in water bodies for degrading microplastics in water bodies.

[0026] Furthermore, the method for degrading microplastics in water using microplastic degrading agents includes:

[0027] A degrading agent and hydrogen peroxide were added to an aqueous solution of microplastics, and an organic acid was added to adjust the pH of the solution before a thermal degradation reaction was carried out.

[0028] Furthermore, the microplastics are selected from any one of low-density polyethylene plastic, polystyrene plastic, polypropylene plastic, and ultra-high molecular weight polyethylene plastic.

[0029] Furthermore, the average particle size of the microplastic particles is 0.1 mm to 2.5 mm.

[0030] Furthermore, the mass concentration of the microplastic aqueous solution is 1 g / L to 5 g / L.

[0031] Further, the mass ratio of the microplastics, the degrading agent and the hydrogen peroxide is 1:(0.005-0.15):(0.1-1), preferably 1:(0.02-0.08):(0.15-0.5).

[0032] Furthermore, the water in the microplastic aqueous solution is selected from one or more of tap water, river water, and seawater.

[0033] Furthermore, the organic acid is selected from one or more of oxalic acid, citric acid, malic acid, and tartaric acid.

[0034] Furthermore, the pH of the solution is adjusted to 4–6.8, preferably 5.7–6.3.

[0035] Furthermore, the thermal degradation temperature is 80℃~130℃, preferably 100℃~120℃, and the thermal degradation time is 8h~20h, preferably 10h~14h.

[0036] Furthermore, the aqueous solution of microplastics, the degrading agent, hydrogen peroxide, and the organic acid conditioning solution can be placed in a stainless steel reactor lined with polytetrafluoroethylene. After sealing the reactor, it can be transferred to an oven under normal pressure for thermal degradation reaction.

[0037] Furthermore, the present invention conducts a simulation experiment on the degradation of microplastics in water by a microplastic degrading agent. Specifically, the microplastic particles are dissolved in deionized water, and then a degrading agent, hydrogen peroxide solution, and organic acid are added, followed by a degradation reaction.

[0038] The fourth aspect of the present invention provides a method for the recovery and regeneration of the above-mentioned degradation agent.

[0039] Furthermore, methods for the recovery and regeneration of the degradation agent include:

[0040] After the thermal degradation of the degrading agent is completed, the thermally degraded microplastic degrading agent is subjected to vacuum filtration. The resulting filter cake is repeatedly washed with organic solvent and / or tap water, and then the resulting material is dried and calcined.

[0041] Furthermore, after the thermal degradation of the degrading agent is completed, the reaction vessel is opened only after the temperature drops to room temperature, and then the thermally degraded microplastic degrading agent is subjected to vacuum filtration.

[0042] Furthermore, the room temperature is 20℃~30℃.

[0043] Furthermore, the organic solvent is selected from one or more of acetone, diethyl ether, petroleum ether, and anhydrous ethanol, with anhydrous ethanol being preferred.

[0044] Furthermore, the drying temperature is 100℃~200℃, preferably 130℃~160℃, and the drying time is 6h~24h, preferably 12h~18h.

[0045] Furthermore, the calcination temperature is 350℃~700℃, preferably 450℃~600℃, and the calcination time is 1h~7h, preferably 3h~6h.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) In the degrading agent of the present invention, each metal component is firmly locked inside the degrading agent to prevent the metal components from being lost. Among them, the first metal component, as the carrier of the degrading agent, has stable performance and can not only highly disperse the second and third metal components, but also has a complexation and cross-linking interaction with them, which effectively improves the reactivity of the degrading agent.

[0048] (2) Under the synergistic effect of the degrading agent and hydrogen peroxide, the present invention can significantly shorten the degradation time, reduce the reaction temperature, and complete the degradation under near-neutral pH conditions in the water. Among them, the multiple metal components of the degrading agent can provide more active sites for the generation of hydroxyl radicals by reacting with hydrogen peroxide, especially the third metal component, which can enhance the activity rate of hydroxyl radicals generated by hydrogen peroxide, that is, improve the thermal degradation efficiency.

[0049] (3) The operation method of the present invention is simple and highly controllable, and the reaction process is safe and environmentally friendly, making it suitable for industrial-scale batch treatment of microplastics in water. Attached Figure Description

[0050] Figure 1 This is a scanning electron microscope image of the microplastics before degradation in Example 1.

[0051] Figure 2 This is a scanning electron microscope image of the microplastics after degradation in Example 1.

[0052] Figure 3 Example 1 compares the degradation rates of different microplastics. Detailed Implementation

[0053] The following examples further illustrate the microplastic degrading agent for water bodies of the present invention, its preparation method, application, and effects. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0054] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples were purchased from conventional biochemical reagent stores.

[0055] In this invention, the morphology and particle size of the microplastics were observed using a Hitachi S-4700 field emission scanning electron microscope (SEM) from Japan.

[0056] In this invention, the content of each metal in the degradation agent is quantitatively analyzed using an XDL 230 X-ray fluorescence spectrometer (XRF) manufactured by Fischer GmbH, Germany.

[0057] In this invention, the specific surface area and pore volume of the degradation agent were determined using a 3H-2000PM2 specific surface area analyzer manufactured by Beijing Bestech Co., Ltd. Before testing, the samples underwent vacuum degassing at 373K, and nitrogen adsorption-desorption isotherms were tested at 77K. The specific surface area and pore volume of the samples were analyzed using the BET method.

[0058] In this invention, the cell parameters and lattice constant of the degrading agent were determined and calculated using a Rigaku D / max-IIIC fully automated X-ray diffractometer (XRD) from Japan. The test conditions were: CuKα radiation, Ni filter, tube voltage 40 kV, tube current 40 mA, and scan rate 2° / min.

[0059] The degradation rate of microplastics in water is calculated as follows: [(weight of degrading agent + weight of microplastics) - weight of dried product after degradation] / (weight of degrading agent + weight of microplastics) × 100%.

[0060] The degradation agent regeneration method involves soaking the degradation agent, which has cooled to room temperature after the reaction, in a 0.01 mol / L dilute citric acid solution for 24 hours. After removing it, wash it with deionized water until neutral, then place it in a forced-air drying oven and dry it at 110℃ for 12 hours, and then calcine it at 500℃ for 2 hours.

[0061] Example 1

[0062] Preparation of the degrading agent: 187.6 g of gadolinium nitrate hexahydrate, 23.9 g of titanium dioxide sulfate, and 6.0 g of indium nitrate were weighed and dissolved in 1 L of deionized water. 40 g of sodium hydroxide was then weighed and dissolved in another 1 L of deionized water. After complete dissolution, 500 g of the sodium hydroxide solution was weighed and added to 500 g of the mixed metal salt solution at 60 °C. The precipitation reaction was allowed to proceed for 3 hours. The resulting mixture was filtered and repeatedly washed with deionized water. The filter cake was transferred to an oven for drying at 110 °C for 20 hours, followed by calcination at 500 °C for 4 hours to obtain the degrading agent.

[0063] Quantitative analysis using X-ray fluorescence spectroscopy revealed that the molar ratio (by element) of gadolinium, titanium, and indium in the degradation agent was 1:0.17:0.043.

[0064] Analysis using a specific surface area analyzer revealed that the specific surface area and pore volume of the degradation agent were 68 m². 2 / g and 3.56cm 3 / g.

[0065] The morphology and particle size of the low-density polyethylene microplastics to be degraded were observed using a Hitachi S-4700 field emission scanning electron microscope (SEM). Figure 1 As shown, the average particle size of the microplastics is 0.5 mm.

[0066] Microplastic degradation treatment: A 1L solution of low-density polyethylene microplastics at a concentration of 2g / L was prepared and placed in a stainless steel reactor lined with polytetrafluoroethylene. 0.1g of degradation agent and 0.7g of hydrogen peroxide were added, and the pH of the solution was adjusted to 6.0 with citric acid. After sealing the reactor, it was transferred to an oven under normal pressure and subjected to thermal degradation at 110℃ for 12 hours. The morphology of the degraded microplastics was observed using a Hitachi S-4700 field emission scanning electron microscope (SEM). Figure 2 As shown.

[0067] After degradation, the reactor was removed from the oven and allowed to cool to 25°C. The reactor was then opened and the mixture inside was filtered. The resulting filter cake was repeatedly rinsed with anhydrous ethanol and tap water. The resulting material was then transferred to an oven and dried at 150°C for 15 hours before being weighed.

[0068] Example 2

[0069] The degradation agent is the same as in Example 1.

[0070] Microplastic degradation treatment: 1 L of a 4 g / L low-density polyethylene microplastic tap water solution (with an average particle size of 0.5 mm) was placed in a PTFE-lined stainless steel reactor. 0.08 g of degradation agent and 0.6 g of hydrogen peroxide were added, and the pH was adjusted to 5.7 with citric acid. After sealing the reactor, it was transferred to an oven under normal pressure and subjected to thermal degradation at 100°C for 10 h. After degradation, the reactor was removed from the oven and allowed to cool to 20°C before being opened. The mixture inside the reactor was filtered, and the resulting filter cake was repeatedly washed with anhydrous ethanol and tap water. The resulting material was then transferred to an oven and dried at 130°C for 12 h before weighing.

[0071] Example 3

[0072] The degradation agent is the same as in Example 1.

[0073] Microplastic degradation treatment: Same as in Example 1, except that the tap water in the preparation of the microplastic aqueous solution is replaced with river water, and the citric acid is replaced with oxalic acid. The degraded and dried substances are weighed and processed.

[0074] Example 4

[0075] The degradation agent is the same as in Example 1.

[0076] Microplastic degradation treatment: Same as in Example 1, except that the pH of the mixed solution was lowered from 6.0 to 4.5, and the degraded and dried material was weighed.

[0077] Example 5

[0078] The degradation agent is the same as in Example 1.

[0079] Microplastic degradation treatment: Same as in Example 1, except that the washing solvent is replaced with petroleum ether, and the degraded and dried material is weighed.

[0080] Example 6

[0081] Preparation of the degrading agent: 158.8 g of gadolinium nitrate hexahydrate, 47.2 g of titanium dioxide sulfate, and 7.3 g of indium nitrate were weighed and dissolved in 1 L of deionized water. 40 g of sodium hydroxide was then weighed and dissolved in another 1 L of deionized water. After complete dissolution, 750 g of the sodium hydroxide solution was weighed and added to 500 g of the mixed metal salt solution at 70 °C. The precipitation reaction was allowed to proceed for 5 hours. The resulting mixture was filtered and repeatedly washed with deionized water. The filter cake was transferred to an oven for drying at 120 °C for 25 hours, followed by calcination at 550 °C for 5 hours to obtain the degrading agent.

[0082] Quantitative analysis using X-ray fluorescence spectrometry revealed that the molar ratio (by element) of gadolinium, titanium, and indium in the degradation agent was 1:0.31:0.067.

[0083] Analysis using a surface area analyzer revealed that the specific surface area and pore volume of the degradation agent were 62 m². 2 / g and 3.45cm 3 / g.

[0084] The microplastic degradation process is the same as in Example 1.

[0085] Example 7

[0086] Preparation of the degrading agent: Same as in Example 1, except that the concentration of the mixed metal salt solution was increased to 0.65 mol / L, and the mass of gadolinium nitrate hexahydrate, titanium sulfate and indium nitrate were increased to 244.2 g, 31.1 g and 8.1 g respectively to obtain the degrading agent.

[0087] Quantitative analysis using X-ray fluorescence spectroscopy revealed that the molar ratio (by element) of gadolinium, titanium, and indium in the degradation agent was 1:0.29:0.062.

[0088] Analysis using a specific surface area analyzer revealed that the specific surface area and pore volume of the degradation agent were both 60 m². 2 / g and 3.07cm 3 / g.

[0089] The microplastic degradation process is the same as in Example 1.

[0090] Example 8

[0091] Preparation of the degradation agent: Same as in Example 1, except that the mass of titanium sulfate and indium nitrate was increased to 70.6 g and 12.3 g, respectively, to obtain the degradation agent.

[0092] Quantitative analysis using X-ray fluorescence spectroscopy revealed that the molar ratio (by element) of gadolinium, titanium, and indium in the degradation agent was 1:0.43:0.09.

[0093] Analysis using a specific surface area analyzer revealed that the specific surface area and pore volume of the degradation agent were 59 m². 2 / g and 2.93cm 3 / g.

[0094] The microplastic degradation process is the same as in Example 1.

[0095] Example 9

[0096] Preparation of the degradation agent: Same as in Example 1, except that gadolinium nitrate hexahydrate, titanium sulfate and indium nitrate are replaced with cerium nitrate hexahydrate, ferrous sulfate and tin nitrate, respectively, to obtain the degradation agent.

[0097] Quantitative analysis using X-ray fluorescence spectrometry revealed that the molar ratio (in terms of elements) of cerium, iron, and tin in the degradation agent was 1:0.06:0.02.

[0098] Analysis using a surface area analyzer revealed that the specific surface area and pore volume of the degradation agent were 55 m². 2 / g and 2.83cm 3 / g.

[0099] The microplastic degradation process is the same as in Example 1.

[0100] Comparative Example 1

[0101] Same as Example 1, except that the pH of the solution was lowered to 3.0 to complete the degradation process.

[0102] Comparative Example 2

[0103] Same as Example 1, except that gadolinium nitrate is omitted to complete the degradation process.

[0104] Comparative Example 3

[0105] Same as Example 1, except that indium nitrate is omitted to complete the degradation process.

[0106] Test Example 1

[0107] The degradation agents recovered from the examples and comparative examples were recycled 10 times under their original conditions. The degradation rate of microplastics in the water after 10 cycles was calculated. The specific results are shown in Table 1.

[0108] Table 1. Degradation rates of microplastics in water bodies in the examples and comparative examples.

[0109] sample Microplastic degradation rate / % Degradation rate after 10 cycles / % Example 1 90.0 88.5 Example 2 86.0 83.2 Example 3 84.0 82.0 Example 4 82.8 80.2 Example 5 90.0 84.6 Example 6 87.8 83.4 Example 7 88.9 86.1 Example 8 82.3 80.5 Example 9 83.0 81.2 Comparative Example 1 70.5 62.3 Comparative Example 2 65.0 58.6 Comparative Example 3 69.3 62.1

[0110] As shown in Table 1, the thermal degradation effect of microplastics in aqueous solution using the method of the present invention is significantly better than that of the comparative example method. In Example 1, the degradation rate can reach 90%, which is attributed to the synergistic effect of the degrading agent and hydrogen peroxide. The various metal components of the degrading agent provide more active sites for the generation of hydroxyl radicals by reacting with hydrogen peroxide. In particular, the third metal component enhances the activity rate of hydroxyl radicals generated by hydrogen peroxide, thus improving the thermal degradation efficiency. After 10 consecutive cycles, the degradation rate of Example 1 remained at 88.5%, with a degradation rate loss of only 1.6%, while the degradation rate loss of the comparative example samples was around 10%. This demonstrates that the degrading agent prepared by the method of the present invention has excellent reusability.

[0111] Test Example 2

[0112] The degrading agents prepared in Example 1 and Comparative Example 3 were analyzed and calculated using XRD characterization instruments to determine the corresponding cell parameters and lattice constants. The specific results are shown in Table 2.

[0113] Table 2. XRD analysis results of samples from Example 1 and Comparative Example 3.

[0114] sample α / ° β / ° γ / ° a / nm b / nm c / nm Example 1 90 90 90 1.5711 1.4603 1.6355 Comparative Example 3 90 90 120 0.5788 0.5788 1.3967

[0115] As can be seen from Table 2, in the unit cell parameters of the sample of Example 1, α=β=γ=90°, and its lattice constant a≠b≠c, which is completely in line with the basic rules of the orthorhombic crystal system; while in the sample of Comparative Example 3, α=β=90°, γ=120°, and its lattice constant a=b≠c, which is characteristic of the hexagonal crystal system.

[0116] Test Example 3

[0117] Using the degradation agent prepared in Example 1, under the operating conditions of Example 1, tests were conducted by sequentially replacing the low-density polyethylene microplastic (LDPE) of Example 1 with polystyrene plastic (PS), polypropylene plastic (PP), and ultra-high molecular weight polyethylene plastic (UHMWPE).

[0118] Based on the above calculation formula, the degradation rates of polystyrene (PS), polypropylene (PP), and ultra-high molecular weight polyethylene (UHMWPE) after degradation by the degradation agent prepared in the examples were calculated respectively. Figure 3 As shown.

[0119] It can be seen that the method of the present invention has a good degradation effect on various types of microplastics, with a degradation rate maintained between 80% and 90%. In actual industrial wastewater, several types of microplastics coexist in most cases, indicating that the method of the present invention is suitable for industrial-scale batch treatment processes.

Claims

1. A microplastic degrading agent for water, comprising a first metal component, a second metal component, and a third metal component, wherein, The first metal component is selected from one or more of cerium, lanthanum, and gadolinium; the second metal component is selected from one or more of iron and titanium; the third metal component is selected from one or more of gallium, indium, and tin; the general formula of the microplastic degrader is X. a Y b Z c O x Where X is the first metal component, Y is the second metal component, and Z is the third metal component, and a:b:c = 1:(0.05~0.5):(0.01~0.1); the degrading agent belongs to the orthorhombic crystal system.

2. The microplastic degrading agent according to claim 1, characterized in that, The first metal component is gadolinium; the second metal component is titanium; and the third metal component is indium.

3. The microplastic degrading agent according to claim 1, characterized in that, In the general formula of microplastic degrading agents, a:b:c = 1:(0.08~0.35):(0.03~0.07).

4. The microplastic degrading agent according to claim 1, characterized in that, The specific surface area of ​​the degrading agent is 53 m². 2 / g~68m 2 / g, pore volume is 2.75cm³ 3 / g~3.56cm 3 / g.

5. A method for preparing the microplastic degrading agent in water as described in any one of claims 1 to 4, comprising the following steps: (1) Prepare a mixed metal salt solution containing a first metal component, a second metal component and a third metal component, and then carry out a precipitation reaction with sodium hydroxide solution; (2) The mixture after precipitation reaction in step (1) is subjected to solid-liquid separation, washing, drying and calcination to obtain the degradation agent.

6. The preparation method according to claim 5, characterized in that, The concentration of the mixed metal salt solution in step (1) is 0.1 mol / L to 0.8 mol / L.

7. The preparation method according to claim 6, characterized in that, The concentration of the mixed metal salt solution in step (1) is 0.35 mol / L to 0.65 mol / L.

8. The preparation method according to claim 5, characterized in that, Step (1) The first metal component precursor is selected from one or more of cerium nitrate, lanthanum nitrate and gadolinium nitrate; the second metal component precursor is selected from one or more of ferrous sulfate and titanium sulfate; the third metal component precursor is selected from one or more of gallium nitrate, indium nitrate and tin nitrate.

9. The preparation method according to claim 8, characterized in that, Step (1) The first metal component precursor is gadolinium nitrate; the second metal component precursor is titanium sulfate; and the third metal component precursor is indium nitrate.

10. The preparation method according to claim 5, characterized in that, The mass ratio of the mixed metal salt solution to the sodium hydroxide solution in step (1) is 1:(0.3~2.5).

11. The preparation method according to claim 10, characterized in that, The mass ratio of the mixed metal salt solution to the sodium hydroxide solution in step (1) is 1:(0.8~1.5).

12. The preparation method according to claim 5, characterized in that, The concentration of the sodium hydroxide solution in step (1) is 0.5 mol / L to 2.5 mol / L.

13. The preparation method according to claim 12, characterized in that, The concentration of the sodium hydroxide solution in step (1) is 0.8 mol / L to 1.2 mol / L.

14. The preparation method according to claim 5, characterized in that, The precipitation reaction temperature in step (1) is 30℃~90℃, and the precipitation reaction time is 0.5h~8h.

15. The preparation method according to claim 14, characterized in that, The precipitation reaction temperature in step (1) is 50℃~70℃, and the precipitation reaction time is 2h~5h.

16. The preparation method according to claim 5, characterized in that, The drying temperature in step (2) is 80℃~150℃ and the drying time is 10h~30h; and / or the calcination temperature is 300℃~700℃ and the calcination time is 1h~8h.

17. The preparation method according to claim 16, characterized in that, The drying temperature in step (2) is 100℃~120℃ and the drying time is 16h~25h; and / or the calcination temperature is 450℃~550℃ and the calcination time is 3h~5h.

18. The application of the microplastic degrading agent in water as described in any one of claims 1 to 4 in degrading microplastics in water.

19. The application according to claim 18, characterized in that, A method for degrading microplastics in water using a microplastic degrading agent includes: adding the degrading agent and hydrogen peroxide to an aqueous solution of microplastics, adding an organic acid to adjust the pH of the solution, and then carrying out a thermal degradation reaction.

20. The application according to claim 19, characterized in that, The microplastics are selected from any one of low-density polyethylene plastic, polystyrene plastic, polypropylene plastic and ultra-high molecular weight polyethylene plastic; and / or, the water in the microplastic aqueous solution is selected from one or more of tap water, river water and seawater; and / or, the mass concentration of the microplastic aqueous solution is 1g / L to 5g / L; and / or, the average particle size of the microplastic particles is 0.1mm to 2.5mm.

21. The application according to claim 19, characterized in that, The mass ratio of the microplastics, degrading agent and hydrogen peroxide is 1:(0.005~0.15):(0.1~1).

22. The application according to claim 21, characterized in that, The mass ratio of the microplastics, degrading agent and hydrogen peroxide is 1:(0.02~0.08):(0.15~0.5).

23. The application according to claim 19, characterized in that, Adjust the pH of the solution to 4-6.8; and / or, the organic acid is selected from one or more of oxalic acid, citric acid, malic acid, and tartaric acid.

24. The application according to claim 23, characterized in that, Adjust the pH of the solution to 5.7-6.

3.

25. The application according to claim 19, characterized in that, The thermal degradation temperature is 80℃~130℃, and the thermal degradation time is 8h~20h.

26. The application according to claim 25, characterized in that, The thermal degradation temperature is 100℃~120℃, and the thermal degradation time is 10h~14h.

27. A method for regenerating a microplastic degrading agent, characterized in that, include: The microplastic degrading agent after thermal degradation in any of the applications described in claims 18 to 26 is subjected to vacuum filtration, and the resulting filter cake is repeatedly washed with organic solvent and / or tap water, and then the resulting material is dried and calcined.

28. The regeneration method according to claim 27, characterized in that, The organic solvent is selected from one or more of acetone, diethyl ether, petroleum ether, and anhydrous ethanol.

29. The regeneration method according to claim 28, characterized in that, The organic solvent is anhydrous ethanol.

30. The regeneration method according to claim 27, characterized in that, The drying temperature is 100℃~200℃, and the drying time is 6h~24h; and / or, the calcination temperature is 350℃~700℃, and the calcination time is 1h~7h.

31. The regeneration method according to claim 30, characterized in that, The drying temperature is 130℃~160℃, and the drying time is 12h~18h; and / or, the calcination temperature is 450℃~600℃, and the calcination time is 3h~6h.

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