Sustained-release material with self-antifoaming function, preparation method and application thereof
By introducing defoamer microcapsules into paraffin-based encapsulated slow-release oxidant materials, the problems of gaseous products affecting mass transfer and defoamer loss are solved, achieving self-defoaming function, improving the degradation efficiency of organic pollutants and the service life of materials, and reducing maintenance costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-01-03
- Publication Date
- 2026-06-16
AI Technical Summary
Existing paraffin-based encapsulated slow-release oxidant materials suffer from impaired mass transfer and structural damage due to the adhesion and accumulation of gaseous products such as carbon dioxide during the degradation of organic pollutants, thus reducing the remediation effect. Furthermore, the direct addition of defoamers can lead to the defoamers reacting with the oxidants, decomposing or being lost.
The defoamer microcapsules are embedded in paraffin to form a slow-release material with self-defoaming function. The defoamer is encapsulated by microcapsules to avoid the influence of gaseous products and the loss of defoamer. It includes a defoamer core and an encapsulation wall, and uses oxidants such as persulfate and iron powder as active components.
It improves mass transfer performance, enhances the degradation effect of organic pollutants, extends material life, reduces maintenance costs, and achieves environmentally friendly and efficient pollutant remediation.
Smart Images
Figure CN120247222B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental remediation, specifically to materials for the remediation of organic pollutants in soil and groundwater, and in particular to a paraffin-based encapsulated oxidant slow-release material with self-defoaming function, its preparation method, and its application. Background Technology
[0002] Organic pollutants are a class of pollutants that are widely present in the environment. Therefore, the 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. These materials can continuously release oxidants, such as persulfate and hydrogen peroxide, for a certain period of time, degrading organic pollutants into harmless or low-toxicity substances through chemical oxidation reactions. Paraffin-based encapsulated slow-release oxidant materials have many advantages over other slow-release oxidants in degrading organic pollutants. First, paraffin is a safe and non-toxic substance, harmless to the environment and human health, reducing the risks in the environmental remediation process. Second, paraffin has a low cost, which can significantly reduce the economic burden of environmental remediation projects. In addition, the preparation process of paraffin-based encapsulated oxidant materials is relatively simple; the oxidant can be encapsulated through steps such as melting, mixing, and cooling, making it convenient to operate and easy to scale up. In conclusion, paraffin-based encapsulated oxidant materials have enormous application potential and superiority in the field of environmental remediation.
[0004] Although paraffin-based encapsulated slow-release oxidant materials have significant advantages in degrading organic pollutants, certain problems still exist in practical applications. Currently, research on paraffin-based encapsulated slow-release oxidant materials mainly focuses on the activity of the encapsulated oxidant, while the adverse effects of gaseous byproducts such as carbon dioxide on material performance have not received sufficient attention. During degradation, gaseous byproducts such as carbon dioxide may be generated. These gases adhere to the surface of the paraffin-based encapsulated slow-release oxidant material, affecting mass transfer and thus reducing the removal efficiency of the slow-release material for organic pollutants. Furthermore, the generation and accumulation of gaseous byproducts may also lead to the destruction of the slow-release material structure during the remediation process, further affecting the remediation effect. However, directly adding defoamers during the preparation of slow-release materials can cause the defoamers to react with the oxidant and decompose during storage. Simultaneously, some of the liquid defoamer may flow out and be lost after the paraffin cools and solidifies. Summary of the Invention
[0005] To address the aforementioned issues, it is particularly important to develop a slow-release degradation material for organic pollutants with self-defoaming capabilities.
[0006] A first aspect of the present invention provides a sustained-release material with self-defoaming function, the sustained-release material comprising defoamer microcapsules and an active component, wherein the defoamer microcapsules and the active component are embedded in paraffin wax;
[0007] The active components are an oxidant and iron powder.
[0008] According to the sustained-release material of the first aspect, wherein the defoamer microcapsule comprises an defoamer core and an encapsulating wall;
[0009] Preferably, the material of the defoamer core is selected from one or more of the following: white oil-based defoamers, polydimethylsiloxane-based defoamers, and surfactant-based defoamers; and / or the material of the encapsulating capsule wall is selected from one or more of the following: calcium alginate, urea-formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, and chitosan;
[0010] More preferably, the material of the defoamer core is a polydimethylsiloxane defoamer and / or a polyether defoamer; and / or the material of the encapsulating shell is selected from calcium alginate and / or urea-formaldehyde resin.
[0011] According to the sustained-release material of the first aspect, wherein the weight of the defoamer core in the defoamer microcapsule accounts for 5%-40% of the weight of the encapsulated capsule wall.
[0012] According to the slow-release material of the first aspect, the oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, and ammonium persulfate.
[0013] According to the sustained-release material of the first aspect, the content of the defoamer microcapsules is less than 5% of the paraffin mass, preferably 0.1%-5% of the paraffin mass; and / or
[0014] The content of the oxidant is less than 60% of the paraffin mass, preferably 10%-60%, and more preferably 20%-50% of the paraffin mass.
[0015] According to the slow-release material of the first aspect, the melting point of the paraffin is in the range of 40-80°C.
[0016] A second aspect of the present invention provides a method for preparing the sustained-release material described in the first aspect, the method comprising the following steps:
[0017] (1) Heat the paraffin wax to a molten state;
[0018] (2) Add the defoamer microcapsules to the molten paraffin and mix thoroughly;
[0019] (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix thoroughly;
[0020] (4) Cool the mixture from step (3) to the softening point of paraffin and granulate it to obtain a slow-release material with self-defoaming function.
[0021] According to the method of the second aspect, in step (2), the amount of defoamer microcapsules added is 0.1%-5% of the mass of paraffin; and / or
[0022] In step (3), the amount of oxidant powder added is 10%-60% of the mass of paraffin.
[0023] A third aspect of the present invention provides the use 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 the degradation of organic pollutants;
[0024] Preferably, the organic pollutant is selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, hexamethylenetetramine, petroleum hydrocarbons, and polycyclic aromatic hydrocarbons.
[0025] The sustained-release material of the present invention may have, but is not limited to, the following beneficial effects:
[0026] (1) Improve the remediation effect: The self-defoaming function can reduce the impact of gaseous products on the mass transfer process, thereby improving the removal effect of organic pollutants.
[0027] (2) Shorten repair time: The self-defoaming function helps improve the efficiency of the degradation process, thereby shortening the repair time.
[0028] (3) Reduced maintenance costs: The self-defoaming function reduces the damage of gas products to the structure of the slow-release material, reduces the frequency of material replacement or cleaning, and thus reduces maintenance costs.
[0029] (4) Environmentally friendly: Using slow-release degradation materials with self-defoaming function can reduce the impact on the environment and improve the sustainability of the remediation process. Attached Figure Description
[0030] Figure 1 The images show the effect of the materials prepared in Comparative Examples 1-2 and Examples 1-5 in removing pollutants.
[0031] Figure 2 This image shows the surface bubble adhesion of the paraffin-based encapsulated oxidant slow-release material with self-defoaming function prepared in Example 1 when removing aniline contaminants.
[0032] Figure 3 The image shows the surface bubble adhesion when a conventional paraffin-based embedded oxidant slow-release material is prepared to remove aniline contaminants, as shown in Comparative Example 1.
[0033] Figure 4 A comparison chart of the sustained-release material prepared in Comparative Example 2 and the sustained-release material prepared in Example 1 after 72 hours of storage.
[0034] Figure 5 The image shows the surface bubble adhesion of the slow-release material prepared for Comparative Example 2 during the removal of aniline contaminants. Detailed Implementation
[0035] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more apparent.
[0036] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.
[0037] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0038] This invention provides a sustained-release material with self-defoaming function, the sustained-release material comprising defoamer microcapsules and active components, wherein the defoamer microcapsules and active components are embedded in paraffin;
[0039] The active components are an oxidant and iron powder.
[0040] The defoamer microcapsule includes an defoamer core and an encapsulated capsule wall.
[0041] The material of the defoamer core can be a commercially available conventional defoamer;
[0042] Preferably, the material of the defoamer core is selected from one or more of the following: white oil-based defoamers, polydimethylsiloxane-based defoamers, and surfactant-based defoamers; and / or the material of the encapsulating capsule wall is selected from one or more of the following: calcium alginate, urea-formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, and chitosan;
[0043] In one specific embodiment, the material of the defoamer core is a polydimethylsiloxane defoamer and / or a polyether defoamer; and / or the material of the encapsulating shell is selected from calcium alginate and / or urea-formaldehyde resin.
[0044] In one embodiment, the defoamer microcapsule contains a defoamer core that accounts for 5%-40% of the weight of the encapsulated capsule wall.
[0045] The oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, and ammonium persulfate.
[0046] The content of the defoamer microcapsules is less than 5% of the paraffin mass, preferably 0.1%-5%; and / or
[0047] The content of the oxidant is less than 60% of the mass of paraffin, preferably 10%-60%.
[0048] The melting point of the paraffin wax is in the range of 40-80℃.
[0049] The slow-release material of this invention uses persulfate and iron powder as active components. Persulfate and iron powder work together to degrade organic pollutants. However, the reaction process generates gaseous products such as carbon dioxide, which adhere to the surface of the slow-release material in the form of bubbles, affecting its mass transfer efficiency. The generation and accumulation of gaseous products may also damage the structure of the slow-release material, further impacting environmental remediation. By improving the material's structure and composition, and introducing microcapsules containing defoaming agents during preparation, the inventors have achieved a self-defoaming function. The added defoaming agent effectively inhibits foam formation or destroys existing foam, thereby 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] The paraffin-based encapsulated oxidant slow-release material with self-defoaming function of the present invention not only encapsulates the defoamer in the form of microcapsules to prevent the liquid defoamer from flowing out and being lost after the paraffin cools and solidifies, but also prevents the defoamer from being directly exposed to the oxidant, thereby reducing the oxidation of the defoamer and further improving the material's performance and service life. During the degradation of organic pollutants, this material can automatically eliminate the influence of gaseous products on the surface of the slow-release material, thereby maintaining good mass transfer and improving remediation efficiency.
[0051] The self-defoaming slow-release material provided by this invention can automatically eliminate the influence of gaseous products on the surface of the slow-release material during the degradation of organic pollutants, thereby maintaining good mass transfer and improving remediation efficiency. The self-defoaming slow-release degradation material for organic pollutants developed in this invention has significant practical implications and application value. In future research and development, the material's performance can be continuously optimized and improved through experiments and field trials to achieve more efficient and environmentally friendly treatment and remediation of organic pollutants.
[0052] This invention also provides a method for preparing a sustained-release material with self-defoaming function, the method comprising the following steps:
[0053] (1) Heat the paraffin wax to a molten state;
[0054] (2) Add the defoamer microcapsules to the molten paraffin and mix thoroughly;
[0055] (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix thoroughly;
[0056] (4) Cool the mixture from step (3) to the softening point of paraffin and granulate it to obtain a slow-release material with self-defoaming function.
[0057] In one embodiment, in step (2), the amount of defoamer microcapsules added is 0.1%-5% of the mass of paraffin; and / or
[0058] In step (3), the amount of oxidant powder added is 10%-60% of the mass of paraffin.
[0059] This invention discloses a method for preparing a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The method involves mixing paraffin wax, an oxidant, encapsulated defoamer microcapsules, and optional other functional materials in a specific ratio. The oxidant and the encapsulated defoamer microcapsules are then encapsulated together in paraffin wax using a melt-cooling method, forming a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. By using encapsulated defoamer microcapsules, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life.
[0060] The slow-release material with self-defoaming function prepared by the method of this invention has advantages such as good degradation effect on organic pollutants, simple operation, and excellent environmental performance. Its preparation process is simple, the raw materials are readily available, and the cost is low. This material has broad application prospects in the field of organic pollutant treatment and remediation.
[0061] The present invention also provides the application of the above-mentioned slow-release material or the slow-release material prepared according to the above method in the degradation of organic pollutants;
[0062] Preferably, the organic pollutant is selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, hexamethylenetetramine, petroleum hydrocarbons, polycyclic aromatic hydrocarbons, etc.
[0063] The present invention will be further described in detail below through examples. Unless otherwise specified, all reagents and other materials used in the following examples are commercially available finished products.
[0064] The polydimethylsiloxane defoamer used in the following examples is model WSC-102, purchased from Shandong Wancheng Chemical Products Co., Ltd.; the polyether defoamer used is model XC-120 glycerol polyether, purchased from Shandong Xingchi Chemical.
[0065] Example 1
[0066] This embodiment uses aniline as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:
[0067] (1) Preparation of calcium alginate-encapsulated defoamer microcapsules:
[0068] Dissolve 2g of sodium alginate powder in 100ml of water. After the sodium alginate is completely dissolved, add 0.1g of polydimethylsiloxane defoamer to the sodium alginate solution and stir to fully disperse the defoamer in the sodium alginate solution.
[0069] The above dispersion was added dropwise to 200 ml of a 2% calcium chloride solution to form beads. After the addition was completed, the beads were soaked and solidified in the calcium chloride solution for 24 hours, then removed and dried to obtain white defoamer microcapsules encapsulated with calcium alginate with an average particle size of 628 μm.
[0070] (2) Preparation of paraffin-based encapsulated oxidant slow-release material with self-defoaming function:
[0071] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 1g of calcium alginate-encapsulated defoamer microcapsules were added to the molten paraffin wax and mixed thoroughly. Next, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, 7.5g iron powder, 17.5g sodium persulfate) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The material was black and spherical with a particle size of 5mm.
[0072] (3) Aniline removal rate determination:
[0073] Five g of the self-defoaming paraffin-based encapsulated oxidant slow-release material prepared in this embodiment was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0074] The paraffin-based encapsulated oxidant slow-release material with self-defoaming function described in this embodiment exhibits good self-defoaming function during aniline removal, such as... Figure 2 As shown, this effectively enhances the mass transfer effect during the removal of organic pollutants. By using defoamer microcapsules encapsulated with calcium alginate, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life. Furthermore, this paraffin-based encapsulated oxidant slow-release material has a simple preparation process, readily available raw materials, low cost, and good organic pollutant removal performance.
[0075] Example 2
[0076] This embodiment uses aniline as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:
[0077] (1) Preparation of calcium alginate-encapsulated defoamer microcapsules:
[0078] Dissolve 2g of sodium alginate powder in 100ml of water. After the sodium alginate is completely dissolved, add 0.8g of polydimethylsiloxane defoamer to the sodium alginate solution and stir to fully disperse the defoamer in the sodium alginate solution.
[0079] The above dispersion was added dropwise to 200 ml of a 2% calcium chloride solution to form beads. After the addition was completed, the beads were soaked and solidified in the calcium chloride solution for 24 hours, then removed and dried to obtain white defoamer microcapsules encapsulated with calcium alginate with an average particle size of 685 μm.
[0080] (2) Preparation of paraffin-based encapsulated oxidant slow-release material with self-defoaming function:
[0081] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 1g of calcium alginate-encapsulated defoamer microcapsules were added to the molten paraffin wax and mixed thoroughly. Next, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, 7.5g iron powder, 17.5g sodium persulfate) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The material was black and spherical with a particle size of 5mm.
[0082] (3) Aniline removal rate determination:
[0083] Five g of the self-defoaming paraffin-based encapsulated oxidant slow-release material prepared in this embodiment was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0084] The paraffin-based encapsulated oxidant slow-release material with self-defoaming function described in this embodiment exhibits excellent self-defoaming properties during aniline removal, effectively enhancing mass transfer during the removal of organic pollutants. Compared to Example 1, the removal rate of aniline is relatively faster. By using defoamer microcapsules encapsulated with calcium alginate, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life. Furthermore, the preparation process of this paraffin-based encapsulated oxidant slow-release material is simple, the raw materials are readily available, the cost is low, and it possesses good organic pollutant removal performance.
[0085] Example 3
[0086] This embodiment uses aniline as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:
[0087] (1) Preparation of calcium alginate-encapsulated defoamer microcapsules:
[0088] Dissolve 2g of sodium alginate powder in 100ml of water. After the sodium alginate is completely dissolved, add 0.5g of polydimethylsiloxane defoamer to the sodium alginate solution and stir to fully disperse the defoamer in the sodium alginate solution.
[0089] The above dispersion was added dropwise to 200 ml of a 2% calcium chloride solution to form beads. After the addition was complete, the beads were soaked and solidified in the calcium chloride solution for 24 hours, then removed and dried to obtain white defoamer microcapsules encapsulated with calcium alginate with an average particle size of 657 μm.
[0090] (2) Preparation of paraffin-based encapsulated oxidant slow-release material with self-defoaming function:
[0091] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 1g of calcium alginate-encapsulated defoamer microcapsules were added to the molten paraffin wax and mixed thoroughly. Next, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, 7.5g iron powder, 17.5g sodium persulfate) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The material was black and spherical with a particle size of 5mm.
[0092] (3) Aniline removal rate determination:
[0093] Five g of the self-defoaming paraffin-based encapsulated oxidant slow-release material prepared in this embodiment was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0094] The paraffin-based encapsulated oxidant slow-release material with self-defoaming function described in this embodiment exhibits excellent self-defoaming properties during aniline removal, effectively enhancing mass transfer during the removal of organic pollutants. Compared to Example 1, the removal rate of aniline is relatively faster, but similar to that of Example 2. By using defoamer microcapsules encapsulated with calcium alginate, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life. Furthermore, the preparation process of this paraffin-based encapsulated oxidant slow-release material is simple, the raw materials are readily available, the cost is low, and it possesses good organic pollutant removal performance.
[0095] Example 4
[0096] This embodiment uses aniline as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:
[0097] (1) Preparation of calcium alginate-encapsulated defoamer microcapsules:
[0098] Dissolve 2g of sodium alginate powder in 100ml of water. After the sodium alginate is completely dissolved, add 0.1g of polydimethylsiloxane defoamer to the sodium alginate solution and stir to fully disperse the defoamer in the sodium alginate solution.
[0099] The above dispersion was added dropwise to 200 ml of a 2% calcium chloride solution to form beads. After the addition was completed, the beads were soaked and solidified in the calcium chloride solution for 24 hours, then removed and dried to obtain white defoamer microcapsules encapsulated with calcium alginate with an average particle size of 628 μm.
[0100] (2) Preparation of paraffin-based encapsulated oxidant slow-release material with self-defoaming function:
[0101] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 2g of calcium alginate-encapsulated defoamer microcapsules were added to the molten paraffin wax and mixed thoroughly. Next, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, iron powder 7.5g, sodium persulfate 17.5g) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The material was black and spherical with a particle size of 5mm.
[0102] (3) Aniline removal rate determination:
[0103] Five g of the self-defoaming paraffin-based encapsulated oxidant slow-release material prepared in this embodiment was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0104] The paraffin-based encapsulated oxidant slow-release material with self-defoaming function described in this embodiment exhibits excellent self-defoaming properties during aniline removal, effectively enhancing mass transfer during the removal of organic pollutants. By using defoamer microcapsules encapsulated with calcium alginate, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life. Furthermore, this paraffin-based encapsulated oxidant slow-release material has a simple preparation process, readily available raw materials, low cost, and good organic pollutant removal performance.
[0105] Example 5
[0106] This embodiment uses toluene as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The preparation process and removal rate determination are as follows:
[0107] (1) Preparation of defoamer microcapsules encapsulated in urea-formaldehyde resin:
[0108] 12g of urea and 24.3g of formaldehyde solution (37wt.%) were mixed (the molar ratio of urea to methanol was 1:1.5). The pH of the system was adjusted to 9-10 with sodium carbonate solution. Then, the mixture was heated to 70℃ and kept at that temperature for 30min to obtain urea-formaldehyde resin prepolymer.
[0109] Add 4.5g of XC-120 type glycerol polyether (polyether defoamer) to 94.5mL of water, add 1% (1g) of emulsifier sodium dodecyl sulfate, and form an emulsion under vigorous stirring. At this point, the defoamer is encapsulated by tiny water droplets, forming a stable emulsion.
[0110] Urea-formaldehyde resin prepolymer was added to the emulsion, and the pH was adjusted to 2-4 with acetic acid while stirring continued. The urea-formaldehyde resin continued to polymerize in the emulsion, eventually forming a stable coating layer on the surface of the defoamer, thus forming urea-formaldehyde resin-embedded defoamer microcapsules. The resulting microcapsules were white in appearance and had an average particle size of 87 μm.
[0111] (2) Preparation of paraffin-based encapsulated oxidant slow-release material with self-defoaming function:
[0112] 50g of paraffin wax (52#) was heated to 60℃ to melt it. Then, 0.25g of urea-formaldehyde resin-encapsulated defoamer microcapsules were added to the molten paraffin wax and mixed thoroughly. Next, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, iron powder 7.5g, sodium persulfate 17.5g) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material with self-defoaming function. The obtained material is black spherical with a particle size of 5mm.
[0113] (3) Determination of toluene removal rate:
[0114] Five g of the self-defoaming paraffin-based encapsulated oxidant slow-release material prepared in this embodiment was added to a reactor containing 100 ml of a toluene solution (concentration 100 mg / L) and 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the toluene concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0115] In this embodiment, the paraffin-based encapsulated oxidant slow-release material with self-defoaming function exhibits only a very small number of bubbles adhering to the material surface during toluene removal, effectively reducing the bubble adhesion rate and demonstrating good self-defoaming function. This significantly enhances the mass transfer effect during the removal of organic pollutants. By using defoamer microcapsules encapsulated in urea-formaldehyde resin, the oxidation of the defoamer by the oxidant is avoided, further improving the material's performance and service life. Furthermore, the preparation process of this paraffin-based encapsulated oxidant slow-release material is simple, the raw materials are readily available, the cost is low, and it possesses good environmental performance.
[0116] Comparative Example 1
[0117] This comparative example uses aniline as the organic pollutant to prepare a conventional paraffin-based encapsulated oxidant slow-release material. The preparation process and removal rate determination are as follows:
[0118] (1) Preparation of conventional paraffin-based encapsulated oxidant slow-release materials:
[0119] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 25g of iron powder and sodium persulfate powder (mass ratio 3:7, 7.5g iron powder, 17.5g sodium persulfate) were added to the mixture and mixed thoroughly again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material.
[0120] (2) Aniline removal rate determination:
[0121] Five g of a conventional paraffin-based encapsulated oxidant, prepared in a comparative ratio, was slowly released into a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand. The mixture was allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .
[0122] In this embodiment, the conventional paraffin-based encapsulated oxidant slow-release material is used in the aniline removal process, such as... Figure 3 As shown, numerous air bubbles are clearly attached to the surface of the material, which affects the mass transfer effect during the removal of organic pollutants and thus inhibits its removal efficiency for aniline.
[0123] Comparative Example 2
[0124] This comparative example uses aniline as the organic pollutant to prepare a paraffin-based encapsulated oxidant slow-release material with directly added unencapsulated polydimethylsiloxane emulsifier. The preparation process and removal rate determination are as follows:
[0125] (1) Preparation of conventional paraffin-based encapsulated oxidant slow-release materials:
[0126] 50g of paraffin wax (56#) was heated to 60℃ to melt it. Then, 0.8g of polydimethylsiloxane defoamer, 25g of iron powder, and sodium persulfate powder (mass ratio 3:7, 7.5g iron powder, 17.5g sodium persulfate) were added to the mixture and thoroughly mixed again. After cooling the mixture to the softening point of the paraffin wax, it was granulated using an extrusion granulation device to obtain a paraffin-based encapsulated oxidant slow-release material.
[0127] (2) Aniline removal rate determination:
[0128] Five g of a conventional paraffin-based encapsulated oxidant slow-release material prepared in a comparative proportion was added to a reactor containing 100 ml of aniline solution (concentration 100 mg / L) mixed with 100 g of sand, and allowed to stand at a constant temperature of 25°C. Samples were then taken at 6, 12, 24, 48, and 72 hours, and the aniline concentration was determined by gas chromatography. The results are shown in the appendix. Figure 1 .like Figure 4 As shown in the comparative example, the paraffin-based encapsulated oxidant slow-release material with directly added defoamer changed color from black to brown after 72 hours of storage. This is because the presence of a small amount of water in the defoamer caused the persulfate to begin an oxidation reaction under the activation of iron. Simultaneously, the iron was also oxidized to iron oxide. The liquid generated during this process, along with some of the defoamer components not encapsulated in paraffin, resulted in significant liquid leakage from the slow-release material. In the aniline removal process, such as... Figure 5As shown, numerous bubbles are clearly attached to the surface of the material. This is because the components in the unencapsulated defoamer are oxidized by persulfate, resulting in an unsatisfactory defoaming effect. This affects the mass transfer effect during the removal of organic pollutants, thus inhibiting its removal efficiency for aniline.
[0129] Depend on Figure 1 The removal effect of the materials prepared in Comparative Example 1 and Comparative Example 2 on aniline can be seen. 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 has already been consumed by the defoamer before it is added to the pollutant solution, resulting in a higher pollutant concentration after 72 hours in the aniline removal process of the slow-release material of Comparative Example 2.
[0130] The present application has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present application based on these embodiments, all of which fall within the protection scope of the present application.
Claims
1. A slow-release material with self-defoaming function, characterized in that, The sustained-release material comprises defoamer microcapsules and active components, wherein the defoamer microcapsules and active components are encapsulated in paraffin. The active components are an oxidant and iron powder; The defoamer microcapsule includes an defoamer core and an encapsulated capsule wall; The material of the defoamer core is selected from one or more of the following: white oil-based defoamers, polydimethylsiloxane defoamers, and surfactant-based defoamers; The material used to embed the capsule wall is selected from one or more of the following: calcium alginate, urea-formaldehyde resin, phenolic resin, ethyl cellulose, methyl cellulose, and chitosan; In the defoamer microcapsules, the weight of the defoamer core accounts for 5%-40% of the weight of the encapsulated capsule wall; The oxidant is selected from one or more of the following: sodium persulfate, potassium persulfate, calcium persulfate, and ammonium persulfate; The content of the defoamer microcapsules is less than 5% of the mass of paraffin wax, and the content of the oxidant is less than 60% of the mass of paraffin wax.
2. The sustained-release material according to claim 1, characterized in that, The defoamer core is made of polydimethylsiloxane defoamer and / or polyether defoamer; and / or the encapsulating wall is made of calcium alginate and / or urea-formaldehyde resin.
3. The sustained-release material according to claim 1, characterized in that, The content of the defoamer microcapsules is 0.1%-5% of the mass of paraffin.
4. The sustained-release material according to claim 1, characterized in that, The content of the oxidant is 10%-60% of the paraffin mass.
5. The sustained-release material according to claim 4, characterized in that, The content of the oxidant is 20-50% of the mass of paraffin.
6. The sustained-release material according to claim 1, characterized in that, The melting point of the paraffin wax is in the range of 40-80℃.
7. The 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 wax to a molten state; (2) Add the defoamer microcapsules to the molten paraffin and mix thoroughly; (3) Add the oxidant powder and iron powder to the mixture in step (2) and mix thoroughly; (4) The mixture from step (3) is cooled to the softening point of paraffin and granulated to obtain a slow-release material with self-defoaming function.
8. The method according to claim 7, characterized in that, In step (2), the amount of defoamer microcapsules added is 0.1%-5% of the mass of paraffin; and / or In step (3), the amount of oxidant powder added is 10%-60% of the mass of paraffin.
9. The use of the sustained-release material according to any one of claims 1 to 6 or the sustained-release material prepared according to any one of claims 7 to 8 in the degradation of organic pollutants.
10. The application according to claim 9, characterized in that, The organic pollutant is selected from one or more of the following: aniline, benzene, toluene, ethylbenzene, hexamethylenetetramine, petroleum hydrocarbons, and polycyclic aromatic hydrocarbons.