Sustained-release material with self-defoaming function as well as preparation method and application thereof

Abstract

The invention discloses a sustained-release material with a self-defoaming function and a preparation method and application thereof, the sustained-release material with the self-defoaming function comprises a defoaming agent microcapsule and an active component, and the defoaming agent microcapsule and the active component are embedded in paraffin in the structure. The defoaming agent microcapsule can prevent the defoaming agent from being directly exposed in the oxidizing agent, so that the phenomenon that the defoaming agent is oxidized is reduced. In the process of degrading organic pollutants, the material can automatically eliminate the influence of gas products on the surface of the slow-release material, so that a good mass transfer effect is kept, and the remediation efficiency is improved. The paraffin-based embedded oxidant material with the self-defoaming function, which is obtained by the method, has the advantages of good degradation effect, simplicity and convenience in operation, excellent environmental protection performance and the like, and has a wide application prospect in the field of organic pollutant treatment and repair.

Description

Technical Field

[0001] The present invention relates to the field of environmental remediation, specifically to remediation materials for organic pollutants in soil and groundwater, and particularly to a paraffin-based embedded oxidant slow-release material with self-defoaming function, its preparation method and application. Background Art

[0002] Organic pollutants are a type of pollutants widely present in the environment. It is statistically shown that about 400 million tons of organic wastewater are generated globally every year, which contains various toxic and harmful substances, such as polycyclic aromatic hydrocarbons, volatile organic compounds, and pesticide residues. Research indicates that the average concentration range of polycyclic aromatic hydrocarbon pollutants in the environment is from 0.1 to 10 ng / g. These organic pollutants pose a serious threat to the ecological system and human health. For example, the concentration of volatile organic compounds in urban atmosphere generally exceeds 10 ppb, and long-term exposure may lead to respiratory diseases, nervous system damage, and even cancer. Therefore, effective treatment and remediation of organic pollutants are of great significance.

[0003] In recent years, slow-release oxidant materials have shown significant advantages in degrading organic pollutants. Such materials can continuously release oxidants, such as persulfate, hydrogen peroxide, etc., within a certain period of time, and degrade organic pollutants into harmless or low-toxic substances through chemical oxidation reactions. Paraffin-based embedded oxidant slow-release materials have many advantages compared with other slow-release oxidation materials in degrading organic pollutants. Firstly, paraffin, as a safe and non-toxic substance, is harmless to the environment and human health, reducing the risks during the environmental remediation process. Secondly, paraffin has a relatively low cost, which can greatly reduce the economic burden of environmental remediation projects. In addition, the preparation process of paraffin-based embedded oxidant materials is relatively simple, and the embedding of oxidants can be achieved through steps such as melting, mixing, and cooling, with convenient operation and easy large-scale production. In summary, paraffin-based embedded oxidant materials have great application potential and superiority in the field of environmental remediation.

[0004] Although paraffin-based embedded slow-release oxidant materials have significant advantages in degrading organic pollutants, there are still certain problems in practical applications. At present, the research on paraffin-based embedded slow-release oxidant materials mainly focuses on the study of the activity of the embedded oxidants, and the adverse effects of gas products such as carbon dioxide on the material properties have not attracted attention. During the degradation process, gas products such as carbon dioxide may be generated, and these gases will adhere to the surface of the paraffin-based embedded slow-release oxidant materials, resulting in the influence of mass transfer, thereby reducing the removal effect of the slow-release materials on organic pollutants. In addition, the generation and accumulation of gas products may also lead to the destruction of the structure of the slow-release materials during the remediation process, further affecting the remediation effect. However, directly adding an antifoaming agent during the preparation of the slow-release material will cause the antifoaming agent to react with the oxidant and decompose during storage. At the same time, part of the liquid antifoaming agent will flow out and be lost after the paraffin cools and solidifies. Summary of the Invention

[0005] To solve the above problems, it is particularly important to develop an organic pollution slow-release degradation material with self-defoaming function.

[0006] The first aspect of the present invention provides a slow-release material with self-defoaming function, and the slow-release material includes antifoaming agent microcapsules and active components, and the antifoaming agent microcapsules and active components are embedded in paraffin;

[0007] Among them, the active components are oxidants and iron powder.

[0008] According to the slow-release material of the first aspect, among them, the antifoaming agent microcapsules include an antifoaming agent core and an embedding capsule wall;

[0009] Preferably, the material of the antifoaming agent core is selected from one or more of the following: white oil-based antifoaming agents, polydimethylsiloxane-based antifoaming agents, surfactant-based antifoaming agents; and / or the material of the embedding capsule wall is selected from one or more of the following: calcium alginate, urea-formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, chitosan;

[0010] More preferably, the material of the antifoaming agent core is a polydimethylsiloxane-based antifoaming agent and / or a polyether-based antifoaming agent; and / or the material of the embedding capsule wall is selected from calcium alginate and / or urea-formaldehyde resin.

[0011] According to the slow-release material of the first aspect, among them, in the antifoaming agent microcapsules, the weight percentage of the antifoaming agent core in the embedding capsule wall is 5%-40%.

[0012] According to the slow-release material of the first aspect, among them, the oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, ammonium persulfate.

[0013] The sustained-release material according to the first aspect, wherein the content of the defoaming agent microcapsules is less than 5% of the mass of the paraffin, preferably 0.1%-5% of the mass of the paraffin; and / or

[0014] The content of the oxidant is less than 60% of the mass of the paraffin, preferably 10%-60%, more preferably 20%-50% of the mass of the paraffin.

[0015] The sustained-release material according to the first aspect, wherein the melting point range of the paraffin is 40-80°C.

[0016] The second aspect of the present invention provides a preparation method of the sustained-release material described in the first aspect, and the method includes the following steps:

[0017] (1) Heat the paraffin to a molten state;

[0018] (2) Add the defoaming agent microcapsules to the molten paraffin and mix well;

[0019] (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix well;

[0020] (4) Cool the mixture in step (3) to the softening point of the paraffin for granulation to obtain a sustained-release material with self-defoaming function.

[0021] According to the method of the second aspect, wherein in step (2), the addition amount of the defoaming agent microcapsules is 0.1%-5% of the mass of the paraffin; and / or

[0022] In step (3), the addition amount of the oxidant powder is 10%-60% of the mass of the paraffin.

[0023] The third aspect of the present invention provides the application of the sustained-release material described in the first aspect or the sustained-release material prepared according to the method described in the second aspect in degrading organic pollutants;

[0024] Preferably, the organic pollutants are selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, diphenyl, petroleum hydrocarbon, polycyclic aromatic hydrocarbon.

[0025] The sustained-release material of the present invention can have but is not limited to the following beneficial effects:

[0026] (1) Improve the remediation effect: The self-defoaming function can reduce the influence of gas products on the mass transfer process, thereby improving the removal effect of organic pollutants.

[0027] (2) Shorten the remediation time: The self-defoaming function helps to improve the efficiency of the degradation process, thereby shortening the time required for remediation.

[0028] (3) Reducing maintenance costs: The self-defoaming function reduces the damage of gas products to the structure of the slow-release material, decreases the frequency of material replacement or cleaning, and thus reduces maintenance costs.

[0029] (4) Environmentally friendly: Using the slow-release degradation material with self-defoaming function can reduce the impact on the environment and improve the sustainability of the remediation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the effect diagram of removing pollutants by the materials prepared in Comparative Examples 1-2 and Examples 1-5.

[0031] Figure 2 It is the diagram of the surface bubble attachment situation when the paraffin-based embedded oxidant slow-release material with self-defoaming function prepared in Example 1 removes aniline pollutants.

[0032] Figure 3 It is the diagram of the surface bubble attachment situation when the conventional paraffin-based embedded oxidant slow-release material prepared in Comparative Example 1 removes aniline pollutants.

[0033] Figure 4 It is the comparison diagram of the slow-release material prepared in Comparative Example 2 and the slow-release material prepared in Example 1 after storing for 72 hours.

[0034] Figure 5 It is the diagram of the surface bubble attachment situation when the slow-release material prepared in Comparative Example 2 removes aniline pollutants. DETAILED DESCRIPTION OF THE INVENTION

[0035] The present application will be further described in detail below with reference to the drawings and examples. Through these descriptions, the features and advantages of the present application will become clearer and more definite.

[0036] The special term "exemplary" here means "serving as an example, embodiment or illustration". Any embodiment described as "exemplary" here does not have to be construed as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.

[0037] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0038] The present invention provides a slow-release material with self-defoaming function, and the slow-release material includes defoamer microcapsules and active components, and the defoamer microcapsules and active components are embedded in paraffin;

[0039] Wherein, the active components are oxidants and iron powder.

[0040] The defoamer microcapsules include a defoamer core and an embedding capsule wall.

[0041] Among them, the material of the defoamer core can be selected from commercially available conventional defoamers;

[0042] Preferably, the material of the defoamer core is selected from one or more of the following: white oil defoamers, polydimethylsiloxane defoamers, surfactant defoamers; and / or the material of the embedding capsule wall is selected from one or more of the following: calcium alginate, urea formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, chitosan;

[0043] In a specific embodiment, the material of the defoamer core is a polydimethylsiloxane defoamer and / or a polyether defoamer; and / or the material of the embedding capsule wall is selected from calcium alginate and / or urea formaldehyde resin.

[0044] In one embodiment, in the defoamer microcapsules, the weight percentage of the defoamer core in the embedding capsule wall is 5%-40%.

[0045] The oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, ammonium persulfate.

[0046] The content of the defoamer microcapsules is less than 5% of the mass of the paraffin, preferably 0.1%-5%; and / or

[0047] The content of the oxidant is less than 60% of the mass of the paraffin, preferably 10%-60%.

[0048] The melting point range of the paraffin is 40-80°C.

[0049] The slow-release material of the present invention uses persulfate and iron powder as active components. The persulfate and iron powder act together to degrade organic pollutants, but gas products such as carbon dioxide are generated during the reaction and adhere to the surface of the slow-release material in the form of bubbles, affecting the mass transfer effect of the slow-release material. The generation and accumulation of gas products may also cause the destruction of the structure of the slow-release material, further affecting the environmental remediation effect. The inventor of the present invention can achieve a self-defoaming function by improving the structure and composition of the material and introducing defoamer microcapsules encapsulated by microcapsules during the preparation process. The added defoamer can effectively inhibit the formation of foam or destroy the already formed foam, improving the mass transfer performance of the slow-release material and enhancing the degradation effect and efficiency of the active components on organic pollutants.

[0050] In the structure of the paraffin-based embedded oxidant slow-release material with self-defoaming function of the present invention, not only can the defoaming agent be encapsulated in the form of microcapsules to prevent the liquid defoaming agent from flowing out and being lost after the paraffin cools and solidifies, but also the embedded defoaming agent microcapsules can prevent the defoaming agent from being directly exposed to the oxidant, thereby reducing the phenomenon of the defoaming agent being oxidized and further improving the performance and service life of the material. During the process of degrading organic pollutants, the material can automatically eliminate the influence of gas products on the surface of the slow-release material, thereby maintaining a good mass transfer effect and improving the repair efficiency.

[0051] The slow-release material with self-defoaming function provided by the present invention can automatically eliminate the influence of gas products on the surface of the slow-release material during the process of degrading organic pollutants, thereby maintaining a good mass transfer effect and improving the repair efficiency. The organic pollution slow-release degradation material with self-defoaming function developed by the present invention has important practical significance and application value. In future research and development, the performance of the material can be continuously optimized and improved through experiments and field tests to achieve more efficient and environmentally friendly treatment and repair of organic pollutants.

[0052] The present invention also provides a preparation method of a slow-release material with self-defoaming function, and the method includes the following steps:

[0053] (1) Heat the paraffin to a molten state;

[0054] (2) Add the defoaming agent microcapsules to the molten paraffin and mix well;

[0055] (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix well;

[0056] (4) Cool the mixture in step (3) to the paraffin softening point for granulation to obtain a slow-release material with self-defoaming function.

[0057] In one embodiment, in step (2), the addition amount of the defoaming agent microcapsules is 0.1%-5% of the mass of the paraffin; and / or

[0058] In step (3), the addition amount of the oxidant powder is 10%-60% of the mass of the paraffin.

[0059] The preparation method of the paraffin-based embedded oxidant slow-release material with self-defoaming function disclosed by the present invention mixes paraffin, oxidant, embedded defoaming agent microcapsules and optional other functional materials in a certain proportion, and uses the melt cooling method to encapsulate the oxidant and the embedded defoaming agent microcapsules in the paraffin together to form a paraffin-based embedded oxidant slow-release material with self-defoaming function. By using the embedded defoaming agent microcapsules, the phenomenon of the defoaming agent being oxidized by the oxidant is avoided, and the performance and service life of the material are further improved.

[0060] The slow-release material with self-defoaming function prepared by the method of the present invention has the advantages of good degradation effect of organic pollutants, simple operation, excellent environmental protection performance, etc. Its preparation process is simple, the raw materials are easily available, and the cost is low. The material has broad application prospects in the field of organic pollutant treatment and remediation.

[0061] The present invention also provides the use of the above-mentioned slow-release material or the slow-release material prepared according to the above-mentioned method in degrading organic pollutants;

[0062] Preferably, the organic pollutants are selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, hexylene, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, etc.

[0063] The present invention is further described in detail by way of examples below. Unless otherwise specified, the reagents used in the following examples are all commercially available products.

[0064] The polydimethylsiloxane defoamer used in the following examples is WSC-102, purchased from Shandong Wancheng Chemical Products Co., Ltd.; the polyether defoamer used is XC-120 glycerol polyether, purchased from Shandong Xingchi Chemical.

[0065] Example 1

[0066] In this example, aniline is used as an organic pollutant to prepare a paraffin-based embedded oxidant sustained-release material with self-defoaming function. The preparation process and removal rate determination are as follows:

[0067] (1) Preparation of calcium alginate-embedded defoamer microcapsules:

[0068] Dissolve 2 g of sodium alginate powder in 100 ml of water. After the sodium alginate is completely dissolved, add 0.1 g of polydimethylsiloxane defoamer into the sodium alginate solution and fully disperse the defoamer in the sodium alginate solution by stirring.

[0069] The above dispersion was added dropwise into 200 ml of 2% calcium chloride solution to form beads. After the addition was completed, the beads were soaked in the calcium chloride solution for 24 hours for solidification, then taken out and dried to obtain calcium alginate-encapsulated defoamer microcapsules with a white appearance and an average particle size of 628 μm.

[0070] (2) Preparation of paraffin-based embedded oxidant sustained-release materials with self-defoaming function:

[0071] Heat 50 g of paraffin wax (56#) to 60 °C until it melts. Then, add 1 g of calcium alginate-embedded defoamer microcapsules to the molten paraffin wax and mix well. Next, add 25 g of iron powder and sodium persulfate powder (mass ratio 3:7, 7.5 g of iron powder and 17.5 g of sodium persulfate) to the mixture and mix well again. After cooling the mixture to the softening point of paraffin wax, granulate it through an extrusion granulation device to obtain a paraffin-based embedded oxidant slow-release material with self-defoaming function. The material is black spherical with a particle size of 5 mm.

[0072] (3) Determination of aniline removal rate:

[0073] Add 5 g of the paraffin-based embedded oxidant slow-release material with self-defoaming function prepared in this example to a reactor containing a mixture of 100 ml of aniline solution (concentration 100 mg / L) and 100 g of sand, and let it stand under the condition of constant temperature 25 °C. Then, take samples at 6, 12, 24, 48, and 72 h, and determine the aniline concentration by gas chromatography. The test results are shown in the appendix Figure 1 .

[0074] The paraffin-based embedded oxidant slow-release material with self-defoaming function described in this example shows good self-defoaming function during the aniline removal process. As Figure 2 shown, it effectively enhances the mass transfer effect during the removal process of organic pollutants. By using calcium alginate-embedded defoamer microcapsules, the phenomenon of defoamer being oxidized by the oxidant is avoided, further improving the performance and service life of the material. In addition, the preparation process of this paraffin-based embedded oxidant slow-release material is simple, the raw materials are easy to obtain, the cost is low, and it has good organic pollutant removal performance.

[0075] Example 2

[0076] In this example, aniline will be used as the organic pollutant to prepare a paraffin-based embedded oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:

[0077] (1) Preparation of calcium alginate-embedded defoamer microcapsules:

[0078] Dissolve 2 g of sodium alginate powder in 100 ml of water. After the sodium alginate is completely dissolved, add 0.8 g of polydimethylsiloxane-based defoamer to the sodium alginate solution and disperse the defoamer well in the sodium alginate solution by stirring.

[0079] Drop the above dispersion into 200 ml of calcium chloride solution with a mass fraction of 2% to form beads. After the dropping is completed, soak and solidify in the calcium chloride solution for 24 h, then fish out and dry to obtain calcium alginate-embedded defoamer microcapsules with a white appearance and an average particle size of 685 μm.

[0080] (2) Preparation of paraffin-based embedded oxidant sustained-release materials with self-defoaming function:

[0081] Heat 50g of paraffin (56#) to 60°C to melt it. Then, add 1g of calcium alginate-embedded defoamer microcapsules to the molten paraffin and mix thoroughly. Next, add 25g of iron powder and sodium persulfate (mass ratio 3:7, iron powder 7.5g, sodium persulfate 17.5g) powder to the mixture and mix thoroughly again. After the mixture is cooled to the softening point of paraffin, it is granulated by extrusion granulation equipment to obtain a paraffin-based embedded oxidant sustained-release material with self-defoaming function. The material is black spherical with a particle size of 5mm.

[0082] (3) Determination of aniline removal rate:

[0083] 5 g of the paraffin-based embedded oxidant sustained-release material with self-defoaming function prepared in this example was added to a reactor containing 100 ml of aniline solution (concentration of 100 mg / L) and 100 g of sand, and allowed to stand at a constant temperature of 25° C. Then, samples were taken at 6, 12, 24, 48 and 72 h, and the aniline concentration was determined by gas chromatography. The test results are shown in the attached figure. Figure 1 .

[0084] The paraffin-based embedded oxidant slow-release material with self-defoaming function described in this embodiment shows good self-defoaming function in the process of removing aniline, effectively enhances the mass transfer effect in the process of removing organic pollutants, and the removal rate of aniline is relatively fast compared with Example 1. By using calcium alginate embedded defoamer microcapsules, the phenomenon of defoamer being oxidized by oxidant is avoided, and the performance and service life of the material are further improved. In addition, the preparation process of the paraffin-based embedded oxidant slow-release material is simple, the raw materials are easily available, the cost is low, and it has good organic pollutant removal performance.

[0085] Example 3

[0086] In this example, aniline is used as an organic pollutant to prepare a paraffin-based embedded oxidant sustained-release material with self-defoaming function. The preparation process and removal rate determination are as follows:

[0087] (1) Preparation of calcium alginate-embedded defoamer microcapsules:

[0088] Dissolve 2 g of sodium alginate powder in 100 ml of water. After the sodium alginate is completely dissolved, add 0.5 g of polydimethylsiloxane defoamer into the sodium alginate solution and fully disperse the defoamer in the sodium alginate solution by stirring.

[0089] The above dispersion was added dropwise to 200 ml of a calcium chloride solution with a mass fraction of 2% to form coagulation beads. After the addition was completed, the beads were soaked and solidified in the calcium chloride solution for 24 h, then fished out and dried to obtain calcium alginate-embedded defoamer microcapsules with a white appearance and an average particle size of 657 μm.

[0090] (2) Preparation of a paraffin-based embedded oxidant slow-release material with self-defoaming function:

[0091] 50 g of paraffin wax (56#) was heated to 60 °C until it melted. Then, 1 g of calcium alginate-embedded defoamer microcapsules was added to the melted paraffin wax and mixed well. Next, 25 g of iron powder and sodium persulfate (mass ratio 3:7, 7.5 g of iron powder and 17.5 g of sodium persulfate) powder were added to the mixture and mixed well again. After the mixture was cooled to the paraffin wax softening point, it was granulated through an extrusion granulation device to obtain a paraffin-based embedded oxidant slow-release material with self-defoaming function. The material was black spherical with a particle size of 5 mm.

[0092] (3) Determination of aniline removal rate:

[0093] 5 g of the paraffin-based embedded oxidant slow-release material with self-defoaming function prepared in this example was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and left standing under the condition of a constant temperature of 25 °C. Then, samples were taken at 6, 12, 24, 48, and 72 h, and the aniline concentration was measured by gas chromatography. The test results are shown in the appendix Figure 1 .

[0094] The paraffin-based embedded oxidant slow-release material with self-defoaming function described in this example showed good self-defoaming function during the aniline removal process, effectively strengthening the mass transfer effect during the removal process of organic pollutants. Compared with Example 1, the removal rate of aniline was relatively fast, but similar to that of Example 2. By using calcium alginate-embedded defoamer microcapsules, the phenomenon of defoamer being oxidized by the oxidant was avoided, further improving the performance and service life of the material. In addition, the preparation process of this paraffin-based embedded oxidant slow-release material is simple, the raw materials are easy to obtain, the cost is low, and it has good performance in removing organic pollutants.

[0095] Example 4

[0096] In this example, aniline was used as the organic pollutant to prepare a paraffin-based embedded oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:

[0097] (1) Preparation of calcium alginate-embedded defoamer microcapsules:

[0098] Dissolve 2 g of sodium alginate powder in 100 ml of water. After the sodium alginate is completely dissolved, add 0.1 g of polydimethylsiloxane defoamer to the sodium alginate solution and disperse the defoamer thoroughly in the sodium alginate solution by stirring.

[0099] Drop the above dispersion into 200 ml of calcium chloride solution with a mass fraction of 2% to form beads. After the dropping is completed, soak and solidify in the calcium chloride solution for 24 h, then fish out and dry to obtain defoamer microcapsules embedded in calcium alginate with a white appearance and an average particle size of 628 μm.

[0100] (2) Preparation of a paraffin-based embedded oxidant slow-release material with self-defoaming function:

[0101] Heat 50 g of paraffin wax (56#) to 60 °C to make it melt. Then, add 2 g of defoamer microcapsules embedded in calcium alginate to the molten paraffin wax and mix well. Next, add 25 g of iron powder and sodium persulfate (mass ratio 3:7, 7.5 g of iron powder and 17.5 g of sodium persulfate) powder to the mixture and mix well again. After cooling the mixture to the softening point of paraffin wax, granulate it through an extrusion granulation device to obtain a paraffin-based embedded oxidant slow-release material with self-defoaming function. The material is black spherical with a particle size of 5 mm.

[0102] (3) Determination of aniline removal rate:

[0103] Add 5 g of the paraffin-based embedded oxidant slow-release material with self-defoaming function prepared in this example to a reactor containing a mixture of 100 ml of aniline solution (concentration 100 mg / L) and 100 g of sand, and let it stand under the condition of constant temperature 25 °C. Then, take samples at 6, 12, 24, 48, and 72 h, and determine the aniline concentration by gas chromatography. The test results are shown in the appendix Figure 1 。

[0104] The paraffin-based embedded oxidant slow-release material with self-defoaming function described in this example shows good self-defoaming function during the aniline removal process, effectively strengthening the mass transfer effect during the removal process of organic pollutants. By using defoamer microcapsules embedded in calcium alginate, the phenomenon that the defoamer is oxidized by the oxidant is avoided, further improving the performance and service life of the material. In addition, the preparation process of this paraffin-based embedded oxidant slow-release material is simple, the raw materials are easy to obtain, the cost is low, and it has good performance in removing organic pollutants.

[0105] Example 5

[0106] In this example, toluene will be used as the organic pollutant to prepare a paraffin-based embedded oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:

[0107] (1) Preparation of defoamer microcapsules embedded with urea-formaldehyde resin:

[0108] Mix 12 g of urea and 24.3 g of formaldehyde solution (37 wt.%) (the molar ratio of urea to methanol is 1:1.5), adjust the pH of the system to 9 - 10 with sodium carbonate solution, then heat to 70 °C and keep it at a constant temperature for 30 min to obtain a urea-formaldehyde resin prepolymer.

[0109] Add 4.5 g of XC-120 type glycerol polyether (polyether defoamer) to 94.5 mL of water, add 1% (1 g) of emulsifier sodium dodecyl sulfate, and form an emulsion under strong stirring. At this time, the defoamer is wrapped by tiny water droplets to form a stable emulsion.

[0110] Add the urea-formaldehyde resin prepolymer to the emulsion, adjust the pH to 2 - 4 with acetic acid, and continue stirring. The urea-formaldehyde resin continues to polymerize in the emulsion, and finally forms a stable coating layer on the surface of the defoamer, forming defoamer microcapsules embedded with urea-formaldehyde resin, and preparing defoamer microcapsules embedded with urea-formaldehyde resin with a white appearance and an average particle size of 87 μm.

[0111] (2) Preparation of paraffin-based embedded oxidant sustained-release material with self-defoaming function:

[0112] Heat 50 g of paraffin (52#) to 60 °C to make it melt. Then, add 0.25 g of defoamer microcapsules embedded with urea-formaldehyde resin to the molten paraffin and mix well. Next, add 25 g of iron powder and sodium persulfate (mass ratio 3:7, 7.5 g of iron powder, 17.5 g of sodium persulfate) powder to the mixture and mix well again. After cooling the mixture to the paraffin softening point, granulate it through an extrusion granulation device to obtain a paraffin-based embedded oxidant sustained-release material with self-defoaming function. The prepared material is black spherical with a particle size of 5 mm.

[0113] (3) Determination of toluene removal rate:

[0114] Add 5 g of the paraffin-based embedded oxidant sustained-release material with self-defoaming function prepared in this example to a reactor containing a mixture of 100 ml of toluene solution (concentration 100 mg / L) and 100 g of sand, and let it stand under the condition of a constant temperature of 25 °C. Then, take samples at 6, 12, 24, 48, and 72 h, and determine the toluene concentration by gas chromatography. The test results are shown in the appendix Figure 1 .

[0115] In the process of toluene removal by the paraffin-based embedded oxidant slow-release material with self-defoaming function described in this embodiment, only a very small amount of bubbles adhere to the surface of the material, effectively reducing the adhesion rate of bubbles on the material surface, showing good self-defoaming function, and better enhancing the mass transfer effect in the process of organic pollutant removal. By using microcapsules of defoamer embedded with urea-formaldehyde resin, the phenomenon of the defoamer being oxidized by the oxidant is avoided, further improving the performance and service life of the material. In addition, the preparation process of the paraffin-based embedded oxidant slow-release material is simple, the raw materials are easy to obtain, the cost is low, and it has good environmental protection performance.

[0116] Comparative Example 1

[0117] In this comparative example, aniline will be used as the organic pollutant to prepare a conventional paraffin-based embedded oxidant slow-release material. The preparation process and removal rate determination are as follows:

[0118] (1) Preparation of conventional paraffin-based embedded oxidant slow-release material:

[0119] Heat 50 g of paraffin (56#) to 60 °C until it melts, then add 25 g of iron powder and sodium persulfate (mass ratio 3:7, 7.5 g of iron powder and 17.5 g of sodium persulfate) powder to the mixture and mix well again. After cooling the mixture to the softening point of paraffin, granulate it through an extrusion granulation device to obtain the paraffin-based embedded oxidant slow-release material.

[0120] (2) Determination of aniline removal rate:

[0121] Add 5 g of the conventional paraffin-based embedded oxidant slow-release material prepared in the comparative example to a reactor containing a mixture of 100 ml of aniline solution (concentration 100 mg / L) and 100 g of sand, and let it stand under the condition of constant temperature 25 °C. Then, sample at 6, 12, 24, 48, and 72 h, and determine the aniline concentration by gas chromatography. The test results are shown in the appendix Figure 1 .

[0122] In the process of aniline removal by the conventional paraffin-based embedded oxidant slow-release material described in this embodiment, as Figure 3 shown, multiple bubbles are obviously attached to the surface of the material, which affects the mass transfer effect in the process of organic pollutant removal, resulting in the inhibition of its aniline removal efficiency.

[0123] Comparative Example 2

[0124] In this comparative example, aniline will be used as the organic pollutant to prepare a paraffin-based embedded oxidant slow-release material directly added with unembedded polydimethylsiloxane emulsifier. The preparation process and removal rate determination are as follows:

[0125] (1) Preparation of conventional paraffin-based embedded oxidant slow-release material:

[0126] Heat 50 g of paraffin wax (56#) to 60 °C until it melts. After that, add 0.8 g of polydimethylsiloxane defoamer, 25 g of iron powder, and a powder of sodium persulfate (mass ratio 3:7, 7.5 g of iron powder and 17.5 g of sodium persulfate) to the mixture and mix well again. Cool the mixture to the softening point of paraffin wax and then granulate it through an extrusion granulation device to obtain a paraffin-based embedded oxidant slow-release material.

[0127] (2) Determination of aniline removal rate:

[0128] Add 5 g of the conventional paraffin-based embedded oxidant slow-release material prepared in the comparative example to a reactor containing a mixture of 100 ml of aniline solution (concentration 100 mg / L) and 100 g of sand, and let it stand under the condition of a constant temperature of 25 °C. Then, take samples at 6, 12, 24, 48, and 72 h, and determine the aniline concentration by gas chromatography. The test results are shown in the appendix Figure 1 . As Figure 4 shown, after 72 h of storage, the color of the paraffin-based embedded oxidant slow-release material with directly added defoamer in this comparative example changed from black to brown. This is because there is a small amount of water in the defoamer, which causes the persulfate to start an oxidation reaction under the activation of iron, and at the same time, the iron is oxidized to iron oxide. The liquid generated during this process and some defoamer components not embedded in paraffin wax cause obvious liquid leakage in this slow-release material. During the aniline removal process, as Figure 5 shown, there are obviously multiple bubbles attached to the surface of the material. This is because the components in the unembedded defoamer are oxidized by the persulfate, resulting in an unsatisfactory defoaming effect, which affects the mass transfer effect during the removal of organic pollutants and inhibits the aniline removal efficiency.

[0129] From Figure 1 the aniline removal effects of the materials prepared in Comparative Example 1 and Comparative Example 2 in the appendix, it can be seen that the removal effect of Comparative Example 2 is worse than that of Comparative Example 1. This is because in the slow-release material of Comparative Example 2, the persulfate was consumed under the action of the defoamer before being added to the pollutant solution, resulting in a higher pollutant concentration after 72 hours during the aniline removal process of the slow-release material of Comparative Example 2.

[0130] The above has described the present application in combination with preferred embodiments. However, these embodiments are only exemplary and only serve an illustrative purpose. On this basis, various substitutions and improvements can be made to the present application, and these all fall within the protection scope of the present application.

Claims

1. A sustained-release material with self-defoaming function, characterized in that, The slow-release material includes defoamer microcapsules and active components, and the defoamer microcapsules and active components are embedded in paraffin; Among them, the active components are oxidants and iron powder.

2. The sustained-release material according to claim 1, wherein The defoamer microcapsules include a defoamer core and an embedding capsule wall; Preferably, the material of the defoamer core is selected from one or more of the following: white oil defoamers, polydimethylsiloxane defoamers, surfactant defoamers; and / or the material of the embedding capsule wall is selected from one or more of the following: calcium alginate, urea-formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, chitosan; More preferably, the material of the defoamer core is a polydimethylsiloxane defoamer and / or a polyether defoamer; and / or the material of the embedding capsule wall is selected from calcium alginate and / or urea-formaldehyde resin.

3. The sustained-release material according to claim 2, wherein In the defoamer microcapsules, the weight percentage of the defoamer core in the embedding capsule wall is 5%-40%.

4. The sustained-release material according to claim 1, wherein The oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, ammonium persulfate.

5. The sustained-release material according to claim 1, characterized in that, The content of the defoamer microcapsules is less than 5% of the mass of paraffin, preferably 0.1%-5% of the mass of paraffin; and / or The content of the oxidant is less than 60% of the mass of paraffin, preferably 10%-60%, more preferably 20%-50% of the mass of paraffin.

6. The sustained-release material according to claim 1, characterized in that, The melting point range of the paraffin is 40-80°C.

7. A method for preparing the sustained-release material according to any one of claims 1 to 6, characterized in that, The method includes the following steps: (1) Heat the paraffin to a molten state; (2) Add the defoamer microcapsules to the molten paraffin and mix well; (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix well; (4) Cool the mixture in step (3) to the softening point of paraffin for granulation to obtain a slow-release material with self-defoaming function.

8. The method according to claim 7, characterized in that In step (2), the addition amount of the defoamer microcapsules is 0.1%-5% of the mass of paraffin; and / or In step (3), the addition amount of the oxidant powder is 10%-60% of the mass of paraffin.

9. Application of the slow-release material according to any one of claims 1 to 6 or the slow-release material prepared by the method according to any one of claims 7 to 9 in degrading organic pollutants; Preferably, the organic pollutants are selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, diphenyl, petroleum hydrocarbons, polycyclic aromatic hydrocarbons.

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