Slow-release oxygen material and its preparation method and application

Abstract

The present invention relates to the field of environmental remediation technology, and discloses a slow-release oxygen material, a preparation method thereof, and an application thereof. The slow-release oxygen material comprises a core component and a shell component; the core component comprises calcium peroxide, and the shell component comprises a carbon-based material; the particle size range of the slow-release oxygen material is 2-30 μm, and the D50 is 6-15 μm. The slow-release oxygen material provided by the present invention is a micron-sized powdered particle, which is easy to inject into the soil and / or groundwater environment to be remediated, and has a core-shell structure of calcium peroxide coated with a carbon-based material. The carbon-based material of the shell portion can effectively adsorb pollutants, increase the contact efficiency between pollutants and oxygen released by calcium peroxide, and improve the remediation efficiency; in addition, it also has a longer oxygen release cycle.

Description

Technical Field

[0001] The present invention relates to the field of environmental restoration, and in particular to a slow-release oxygen material and a preparation method and application thereof. Background Art

[0002] my country has numerous sites of organic pollution. For example, petrochemical sites include refining sites across China owned by Sinopec, PetroChina, and CNOOC, local refineries and chemical companies, and gas stations. Statistical research has shown that some gas stations in my country are still small and inefficient, leading to seepage and leakage of gasoline and diesel components from underground storage tanks, pipelines, and dispensers, becoming one of the largest sources of soil and / or groundwater contamination.

[0003] At present, there are many technologies for remediation of petroleum hydrocarbon contaminated sites at home and abroad, including in-situ chemical oxidation, in-situ permeable reaction barrier technology, multiphase extraction, gas phase extraction, in-situ bioremediation technology, etc. However, the limiting factor for microbial degradation of petroleum hydrocarbon pollutants in groundwater is often the lack of electron acceptors, especially dissolved oxygen. Therefore, how to provide sufficient dissolved oxygen to the soil and / or groundwater environment has become a focus of attention. At present, there are many ways to inject dissolved oxygen into groundwater, including air injection, ozone injection, hydrogen peroxide solution injection, and oxygen-releasing compound injection. Among them, oxygen-releasing compounds can be injected once, without the need for complex ground injection equipment and daily maintenance like air injection technology, and therefore are receiving more and more attention.

[0004] Currently, common preparation methods include organic encapsulation and inorganic encapsulation, but these methods all have some problems. For example, the slow-release oxygen material prepared by the organic encapsulation method is composed of organic matter, which may cause secondary pollution after being injected into the ground. In addition, the biodegradation process of the material also consumes oxygen, resulting in the effective slow-release oxygen component not being used to degrade organic pollutants. For the inorganic encapsulation method, cement encapsulation is often used. During the preparation process, calcium peroxide easily reacts with the water phase, resulting in a decrease in oxygen content and a short oxygen release cycle. At the same time, components such as cement and river sand cause the oxygen-containing substance content in the material to be low. In addition, the prepared oxygen-releasing material is granular, with a particle size of mostly millimeters, which is difficult to inject into groundwater and has a limited diffusion range.

[0005] Therefore, there is a need to seek an oxygen-releasing material with a long oxygen-releasing period and easy injection into soil and / or groundwater environment and a preparation method thereof. Summary of the Invention

[0006] The purpose of the present invention is to overcome the technical problems existing in the prior art such as secondary pollution, short oxygen release cycle, and difficulty in injecting into the soil and / or groundwater environment during the repair process, and to provide a slow-release oxygen material. The slow-release oxygen material has the advantages of a long oxygen release cycle and easy injection into the soil and / or groundwater environment, and can effectively repair contaminated (especially organically contaminated) soil and / or groundwater.

[0007] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a slow-release oxygen material, which includes a core component and a shell component; the core component includes calcium peroxide, and the shell component includes a carbon-based material; the particle size range of the slow-release oxygen material is 2-30μm, and D50 is 6-15μm.

[0008] A second aspect of the present invention provides a method for preparing a slow-release oxygen material, the method comprising the following steps:

[0009] (1) mixing calcium peroxide with an organic polymer to obtain a mixed slurry; wherein the particle size of the calcium peroxide is in the range of 2-30 μm, preferably 5-20 μm; and D50 is in the range of 6-15 μm, preferably 8-13 μm;

[0010] (2) drying and calcining the mixed slurry obtained in step (1) to obtain the slow-release oxygen material;

[0011] Wherein, the calcination temperature is lower than 300°C.

[0012] The third aspect of the present invention provides a slow-release oxygen material prepared by the method described in the second aspect.

[0013] A fourth aspect of the present invention provides a use of the slow-release oxygen material described in the first or third aspect in the remediation of organically contaminated soil and / or groundwater.

[0014] Compared with the prior art, the slow-release oxygen material with the function of repairing soil and / or groundwater provided by the present invention has at least the following advantages:

[0015] 1) The slow-release oxygen material provided by the present invention is in the form of micron-sized powder particles, which can be easily injected into the soil and / or groundwater environment to be repaired;

[0016] 2) The slow-release oxygen material provided by the present invention has a core-shell structure of carbon-based material coated with calcium peroxide. The carbon-based material in the outer shell can effectively adsorb pollutants, increase the contact efficiency between pollutants and oxygen released by calcium peroxide, and improve the remediation efficiency; and the carbon-based material coating can increase the oxygen release period of the slow-release oxygen component;

[0017] 3) The slow-release oxygen material provided by the present invention has the dual functions of adsorbing organic matter (due to the carbon with adsorption properties in the shell) and biostimulating the degradation of organic matter (due to the oxygen-releasing calcium peroxide in its core component), which significantly improves the efficiency of microbial degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is an X-ray diffraction pattern of the slow-release oxygen material prepared in Example 1;

[0019] Figure 2 is a scanning electron microscope image of the slow-release oxygen material prepared in Example 1;

[0020] Figure 3 This is an energy dispersive spectrum (EDX) image of carbon element in an electron microscope image of the slow-release oxygen material prepared in Example 1;

[0021] Figure 4 This is an EDX image of oxygen element in an electron microscope image of the slow-release oxygen material prepared in Example 1;

[0022] Figure 5 This is an EDX image of calcium element in an electron microscope image of the slow-release oxygen material prepared in Example 1;

[0023] Figure 6 1 is an oxygen release cycle curve diagram of the slow-release oxygen material prepared in Example 1. DETAILED DESCRIPTION

[0024] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0025] The first aspect of the present invention provides a slow-release oxygen material, which includes a core component and a shell component; the core component includes calcium peroxide, and the shell component includes a carbon-based material; the slow-release oxygen material has a particle size range of 2-30μm and a D50 of 6-15μm.

[0026] According to some embodiments of the present invention, the weight ratio of the core component to the shell component may be (5-80):1, preferably (10-30):1.

[0027] In the present invention, the weight ratio of the core component to the shell component can be obtained by theoretical calculation. The weight of the core component can be calculated as the sum of the theoretical amount of calcium peroxide produced and the amount of additives added. The weight of the shell component can be calculated as the product of the amount of organic polymer added and the theoretical carbon content, and the sum of the amount of binder added and the amount of optional additives added. Material loss is not considered in the theoretical calculation.

[0028] According to some embodiments of the present invention, the particle size of the slow-release oxygen material may be in the range of 5-20 μm, and D50 may be in the range of 8-13 μm.

[0029] According to some embodiments of the present invention, the core component may further include at least one of phosphate, silicate and carbonate; the shell component may further include at least one of plastic binder, phosphate, silicate and carbonate.

[0030] A second aspect of the present invention provides a method for preparing a slow-release oxygen material, the method comprising the following steps:

[0031] (1) mixing calcium peroxide with an organic polymer to obtain a mixed slurry; wherein the particle size of the calcium peroxide is in the range of 2-30 μm, preferably 5-20 μm; and D50 is in the range of 6-15 μm, preferably 8-13 μm;

[0032] (2) drying and calcining the mixed slurry obtained in step (1) to obtain the slow-release oxygen material;

[0033] Wherein, the calcination temperature is lower than 300°C.

[0034] According to some embodiments of the present invention, the calcium peroxide is obtained by contacting calcium hydroxide and / or calcium oxide with hydrogen peroxide.

[0035] According to some embodiments of the present invention, the molar ratio of the calcium hydroxide and / or calcium oxide to hydrogen peroxide may be (1.01-1.3):1, preferably (1.05-1.2):1.

[0036] According to some embodiments of the present invention, the contact conditions may include: a temperature of 0-30°C, preferably 5-20°C; a time of 5-60 min (5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 40 min, 50 min, 60 min or any value between the above values), preferably 10-30 min; and a stirring speed of 200-1000 rpm, preferably 500-800 rpm.

[0037] In the present invention, to obtain calcium peroxide of suitable particle size, the contacting method is preferably: adding a hydrogen peroxide solution to a material containing calcium oxide and / or calcium hydroxide, wherein the hydrogen peroxide solution (solute mass fraction of 30-50 wt%) is added at a rate of 0.5-5 mL / min relative to 10 g of calcium oxide and / or calcium hydroxide.

[0038] According to some embodiments of the present invention, the amount of the organic polymer used may be 12-600 g, preferably 100-330 g, per kg of calcium peroxide.

[0039] According to some embodiments of the present invention, the carbon content of the organic polymer may be 20-55 wt %, preferably 25-40 wt %.

[0040] In the present invention, preferably, the organic polymer is a biodegradable organic substance without secondary pollution.

[0041] According to some embodiments of the present invention, the organic polymer is selected from at least one of carrageenan, gelatin, sodium alginate, ethyl cellulose and polyvinyl alcohol, preferably selected from at least one of carrageenan, gelatin and sodium alginate.

[0042] According to some embodiments of the present invention, in step (1), the mixing conditions include: temperature of 0-30°C, preferably 5-20°C; time of 5-20 min (5 min, 10 min, 15 min, 20 min or any value between the above values), preferably 5-10 min; stirring speed of 200-1000 rpm, preferably 500-800 rpm.

[0043] In the present invention, the contacting and mixing temperatures may be the same or different.

[0044] In the present invention, preferably, the calcium peroxide is in the form of a solution or slurry before being mixed with the organic polymer.

[0045] According to some embodiments of the present invention, in order to improve the coating effect and stabilize the calcium peroxide, the mixing is performed in the presence of an auxiliary agent.

[0046] Preferably, the amount of the auxiliary agent used is 10-100 g, preferably 20-50 g, relative to each kg of calcium peroxide.

[0047] Preferably, the auxiliary agent is selected from a plastic binder and at least one of phosphates, silicates and carbonates.

[0048] Preferably, the plastic bonding mineral is selected from at least one of attapulgite, montmorillonite and kaolin.

[0049] According to some embodiments of the present invention, in step (2), the drying includes a first drying and a second drying.

[0050] According to some embodiments of the present invention, the conditions for the first drying may include: a temperature of 50-80° C., preferably 60-70° C.; and a time of 10-40 min, preferably 20-30 min.

[0051] According to some embodiments of the present invention, the second drying conditions may include: a temperature of 100-120°C, preferably 100-110°C.

[0052] According to some embodiments of the present invention, in step (2), the calcination conditions may include: a temperature of 150-260° C., preferably 200-250° C.; and a time of 5-50 min, preferably 10-30 min.

[0053] In the present invention, the calcination is carried out under an inert atmosphere; the inert atmosphere can preferably be provided by nitrogen and / or argon.

[0054] In the present invention, there is no particular limitation on the types of the phosphates, silicates and carbonates, as long as they can meet the requirements of the present invention. For example, they can be selected from at least one of sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, tripotassium phosphate, sodium carbonate and sodium silicate, preferably trisodium phosphate and / or tripotassium phosphate.

[0055] The third aspect of the present invention provides a slow-release oxygen material prepared by the method described in the second aspect.

[0056] A fourth aspect of the present invention provides a use of the slow-release oxygen material described in the first or third aspect in the remediation of organically contaminated soil and / or groundwater.

[0057] According to some embodiments of the present invention, the organic pollutant can be selected from at least one of petroleum hydrocarbons, halogenated hydrocarbons, alcohols and ethers, and more preferably selected from at least one of benzene, toluene, ethylbenzene, trimethylbenzene, methyl tert-butyl ether, tert-butanol, dichloroethane, dichloroethylene, vinyl chloride, benzo[a]pyrene, benz[a]anthracene and naphthalene.

[0058] The present invention will be described in detail below through examples.

[0059] In the following examples, all the raw materials used were commercially available;

[0060] The core-shell composition and structure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM);

[0061] The calcium peroxide content in the slow-release oxygen material is determined by potassium permanganate titration: 0.05 g of the test sample is accurately weighed and placed in a 250 mL conical flask. 20 mL of phosphoric acid (1:3 dilution) and 10 mL of deionized water are added successively. After dissolution, the sample is titrated with 0.02 mol / L potassium permanganate until red.

[0062] (Static) sustained-release cycle method: Accurately weigh 1g of the test sample and dissolve it in 100mL of deionized water. Then, place it in a sealed bottle. Measure the calcium peroxide content over a certain period of time (1 week, 6 weeks, 18 weeks, 24 weeks, 30 weeks, 40 weeks, and 52 weeks) to obtain a fitting curve showing the change in calcium peroxide content over time (the measurement time can be adaptively adjusted based on the previous measurement). The calcium peroxide content in the sample is titrated using the potassium permanganate method. When the calcium peroxide content drops below 10% of the initial calcium peroxide content, the sustained-release cycle is considered to have been reached. The corresponding time in the fitting curve obtained above is the oxygen release cycle of the material.

[0063] Example 1

[0064] (1) Accurately weigh 19.7g of solid calcium oxide and 1.27g of solid tripotassium phosphate, mix thoroughly, and add to a beaker containing 48.8g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 20°C. Then, slowly add 20g of a 50% H2O2 solution by mass to the beaker through a peristaltic pump under stirring at 800rpm for 10min. After the H2O2 is completely added, continue stirring and reacting for 30min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 20°C to obtain a material containing calcium peroxide. The particle size range of the calcium peroxide is 2-20μm, and the D50 is 9.9μm. Add 8.36g of solid carrageenan (type λ, carbon content 25wt%) to the above material containing calcium peroxide, and stir and react at 20°C and 800rpm for 10min until a uniform slurry material (mixed slurry) is obtained.

[0065] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 70°C for 20 minutes, and then heated to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 200°C for 30 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 2-20 μm and a D50 of 10.2 μm; and the theoretical weight ratio of the core component to the shell component is approximately 9.7:1.

[0066] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 63%. The slow-release period was verified by a static slow-release test (adding 1g of the slow-release oxygen material obtained above to 100mL of boiled and cooled water) to be 12 months. Figure 1 It can be seen that the core component of the slow-release oxygen material prepared in this embodiment is calcium peroxide. Figure 2-5 It can be seen that the surface of the slow-release oxygen material prepared in this embodiment is rough, and carbon, oxygen and calcium elements are evenly distributed on the surface of the slow-release oxygen material; Figure 6 The sustained-release period of the slow-release oxygen material prepared in this example reached 52 weeks (12 months), and its calcium peroxide content dropped to 10% of the initial calcium peroxide content.

[0067] Example 2

[0068] (1) Accurately weigh 30g of solid calcium hydroxide and 0.6g of solid sodium carbonate, mix thoroughly, and add them to a beaker containing 20.4g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 5°C. Then, slowly add 43.7g of a 30% H2O2 solution by peristaltic pump to the beaker under stirring at 500rpm for 15min. After the H2O2 is completely added, continue stirring and reacting for 20min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 5°C to obtain a material containing calcium peroxide. The particle size range of the calcium peroxide is 2-25μm, and the D50 is 11.2μm. Add 5g of gelatin (type B, carbon content 35wt%) to the material containing calcium peroxide, and stir and react at 5°C and 500rpm for 5min until a uniform slurry is obtained.

[0069] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 60°C for 30 minutes, and then heated to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 250°C for 10 minutes under an argon atmosphere to prepare a slow-release composite material. The particle size of the slow-release oxygen material ranges from 2 to 28 μm, and the D50 is 11.4 μm; the theoretical weight ratio of the core component to the shell component is approximately 17:1.

[0070] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 65%. A static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 9 months.

[0071] Example 3

[0072] (1) Accurately weigh 20g of solid calcium hydroxide and 0.8g of solid sodium dihydrogen phosphate, mix thoroughly, and add them to a beaker containing 31.1g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 15°C. Then, slowly add 27.9g of a 30% H2O2 solution by peristaltic pump to the beaker under stirring at 600rpm for 15min. After the H2O2 is completely added, continue stirring and reacting for 10min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 15°C to obtain a material containing calcium peroxide. The particle size of the calcium peroxide is in the range of 2-30μm and the D50 is 12μm. Add 2.1g of solid sodium alginate (carbon content 36wt%) to the material containing calcium peroxide and stir the reaction at 15°C and 600rpm for 5min until a uniform slurry is obtained.

[0073] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 70°C for 20 minutes, and then the temperature is raised to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 250°C for 10 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 2-30 μm and a D50 of 12.2 μm; and the theoretical weight ratio of the core component to the shell component is approximately 27:1.

[0074] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 57%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 12 months.

[0075] Example 4

[0076] (1) Accurately weigh 23g of solid calcium hydroxide and 1.5g of solid sodium silicate, mix thoroughly, and add them to a beaker containing 46.3g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 5°C. Then, slowly add 19.2g of 50% H2O2 solution by peristaltic pump to the beaker under stirring at 500rpm for 10min. After the H2O2 is completely added, continue stirring and reacting for 20min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 5°C to obtain a material containing calcium peroxide. The particle size of the calcium peroxide is in the range of 5-20μm and the D50 is 9.2μm. Add 4g of solid polyvinyl alcohol (carbon content 55wt%) to the material containing calcium peroxide and stir the reaction at 5°C and 500rpm for 10min until a uniform slurry is obtained.

[0077] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 70°C for 20 minutes, and then heated to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 200°C for 20 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 4-22 μm and a D50 of 9.2 μm; and the theoretical weight ratio of the core component to the shell component is approximately 11:1.

[0078] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 64%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0079] Example 5

[0080] (1) Accurately weigh 26.4g of solid calcium hydroxide and 1g of solid disodium hydrogen phosphate, mix thoroughly, and add them to a beaker containing 22.6g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 10°C. Then, slowly add 38g of a 30% H2O2 solution by peristaltic pump to the beaker under stirring at 700rpm for 20min. After the H2O2 is completely added, continue stirring and reacting for 15min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 10°C to obtain a material containing calcium peroxide. The particle size range of the calcium peroxide is 4-25μm, and the D50 is 11.9μm. Add 8g of solid carrageenan (type λ, carbon content 25wt%) to the material containing calcium peroxide, and stir and react at 10°C and 700rpm for 8min until a uniform slurry is obtained.

[0081] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 70°C for 20 minutes, and then heated to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 220°C for 20 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 5-25 μm and a D50 of 12.0 μm; and the theoretical weight ratio of the core component to the shell component is approximately 13:1.

[0082] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 67%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0083] Example 6

[0084] (1) Accurately weigh 22.6g of solid calcium hydroxide, mix thoroughly, and add it to a beaker containing 44.9g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 4°C. Then, slowly add 16g of 50% H2O2 solution by peristaltic pump to the beaker under stirring at 1000rpm for 8 minutes. After the H2O2 is completely added, continue stirring and reacting for 60 minutes. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 4°C to obtain a material containing calcium peroxide. The particle size range of calcium peroxide is 2-22μm, and D50 is 10.2μm. Add 0.23g of solid carrageenan (type λ, carbon content 25wt%) and 0.23g of solid kaolin to the material containing calcium peroxide, and stir and react at 4°C and 1000rpm for 5 minutes until a uniform slurry is obtained.

[0085] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 50°C for 40 minutes, and then heated to 120°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 180°C for 50 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 2-23 μm and a D50 of 10.4 μm; and the weight ratio of the core component to the shell component is approximately 76:1.

[0086] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 65%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0087] Example 7

[0088] (1) Accurately weigh 15g of solid calcium hydroxide and 1.5g of solid sodium silicate, mix thoroughly, and slowly add them to a beaker containing 30.5g of deionized water. Stir and mix until uniform. Place the beaker in a thermostatic reactor set to 30°C. Then, slowly add 21g of a 30% H2O2 solution by mass to the beaker through a peristaltic pump under stirring at 200rpm for 10min. After the H2O2 is completely added, continue stirring and reacting for 5min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 30°C to obtain a material containing calcium peroxide. The particle size of the calcium peroxide is in the range of 3-24μm, and the D50 is 10.4μm. Add 1.5g of solid ethyl cellulose (carbon content 46wt%) to the material containing calcium peroxide, and stir and react at 30°C and 200rpm for 20min until a uniformly mixed slurry is obtained.

[0089] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 80°C for 10 minutes, and then heated to 120°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 260°C for 5 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 3-25 μm and a D50 of 10.5 μm; and the theoretical weight ratio of the core component to the shell component is approximately 23:1.

[0090] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 59%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 8 months.

[0091] Example 8

[0092] (1) Accurately weigh 20g of solid calcium hydroxide, mix thoroughly, and add it to a beaker containing 40.7g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor and set the thermostatic reactor to 10°C. Then, slowly add 27.8g of a 30% H2O2 solution by peristaltic pump to the beaker under stirring at 600rpm for 10min. After the H2O2 is completely added, continue stirring and reacting for 30min. This process is carried out in a thermostatic reactor and the reaction temperature is kept at 10°C to obtain a material containing calcium peroxide. The particle size of the calcium peroxide is in the range of 2-20μm and the D50 is 9.6μm. Add 4.3g of solid sodium alginate, 1g of montmorillonite, and 1g of potassium silicate to the material containing calcium peroxide, and stir and react at 10°C and 600rpm for 10min until a uniform slurry is obtained.

[0093] (2) The mixed slurry obtained in step (1) is placed in a drying dish, dried in an oven at 70°C for 20 minutes, and then heated to 110°C for a second drying to obtain a dried powder sample; the dried powder sample is placed in a corundum crucible, placed in a tube furnace, and calcined at 235°C for 15 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. The slow-release oxygen material has a particle size range of 2-20 μm and a D50 of 9.7 μm; and the weight ratio of the core component to the shell component is approximately 5.5:1.

[0094] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 56%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0095] Example 9

[0096] The method of Example 1 is as follows, except that

[0097] The mass of the added hydrogen peroxide solution was changed to 21.7 g, thereby changing the amount of calcium hydroxide and / or calcium oxide and hydrogen peroxide (including the mass fraction of hydrogen peroxide, etc.) to make the molar ratio of the solution 1.1:1;

[0098] Among them, the particle size range of calcium peroxide is 2-24μm, and D50 is 10.6μm;

[0099] The particle size range of the slow-release oxygen material is 2-25 μm, and D50 is 10.8 μm; the weight ratio of the core component to the shell component is 7.4:1.

[0100] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 65%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 14 months.

[0101] Example 10

[0102] The method of Example 1 is as follows, except that

[0103] The weight of added carrageenan was changed to 0.8 g;

[0104] Among them, the particle size range of calcium peroxide is 2-20μm, and D50 is 9.9μm;

[0105] The particle size range of the slow-release oxygen material is 2-20 μm, and D50 is 10 μm; the theoretical weight ratio of the core component to the shell component is about 80:1.

[0106] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 71%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 7 months.

[0107] Example 11

[0108] The method of Example 1 is as follows, except that

[0109] The reaction time of calcium peroxide and solid carrageenan was changed to 30 min;

[0110] Among them, the particle size range of calcium peroxide is 2-20μm, and D50 is 9.9μm;

[0111] The particle size range of the slow-release oxygen material is 2-20 μm, and D50 is 10.1 μm; the theoretical weight ratio of the core component to the shell component is about 7.5:1.

[0112] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 56%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0113] Example 12

[0114] The method of Example 1 is as follows, except that

[0115] Change the calcination temperature to 160°C;

[0116] Among them, the particle size range of calcium peroxide is 2-20μm, and D50 is 9.9μm;

[0117] The particle size range of the slow-release oxygen material is 2-20 μm, and D50 is 10.4 μm; the theoretical weight ratio of the core component to the shell component is about 7.5:1.

[0118] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 60%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 9 months.

[0119] Example 13

[0120] The process was carried out in the same manner as in Example 1, except that no auxiliary agent was added.

[0121] Among them, the particle size range of calcium peroxide is 2-18μm, and D50 is 8.6μm;

[0122] The particle size range of the slow-release oxygen material is 2-19 μm, and D50 is 8.7 μm; the theoretical weight ratio of the core component to the shell component is about 9.2:1.

[0123] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 58%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 9 months.

[0124] Example 14

[0125] The process was carried out in the same manner as in Example 1, except that an auxiliary agent, sodium carbonate, was added.

[0126] Among them, the particle size range of calcium peroxide is 2-20μm, and D50 is 9.7μm;

[0127] The particle size range of the slow-release oxygen material is 2-21 μm, and D50 is 9.8 μm; the theoretical weight ratio of the core component to the shell component is about 9.7:1.

[0128] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 60%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 10 months.

[0129] Comparative Example 1

[0130] (1) Accurately weigh 20g of solid calcium oxide and 1.5g of solid potassium phosphate, mix thoroughly, and add to a beaker containing 40.7g of deionized water. Stir and mix evenly. Place the beaker in a thermostatic reactor set at 10°C. Then, slowly add 27.8g of a 30% H2O2 solution to the beaker under stirring at 800rpm for 15min. After the H2O2 is completely added, continue stirring and reacting for 30min. This process is carried out in a thermostatic reactor and the reaction temperature is maintained at 10°C to obtain a material containing calcium peroxide. The particle size of the calcium peroxide is in the range of 2-20μm.

[0131] (2) The calcium peroxide-containing material was placed in a drying dish and dried in an oven at 70°C for 20 minutes. The temperature was then raised to 110°C for a second drying time of 30 minutes to obtain a dried powder sample. The dried powder sample was mixed with solid carrageenan in a mortar and pestle, then placed in a corundum crucible and calcined in a tube furnace at 200°C for 10 minutes under a nitrogen atmosphere to prepare a slow-release oxygen material. No core-shell structure was obtained.

[0132] The slow-release oxygen material obtained above was titrated with potassium permanganate to determine its oxygen content and thus to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 67%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 6 months.

[0133] Comparative Example 2

[0134] The method of Example 1 is as follows, except that

[0135] Commercially available calcium peroxide (Aladdin, analytical grade) was used, with a particle size range of 0.2-10 μm and a D50 of 4.8 μm;

[0136] The particle size range of the slow-release oxygen material is 0.2-10 μm, and D50 is 4.9 μm; the weight ratio of the core component to the shell component is 10:1.

[0137] The obtained slow-release oxygen material was titrated with potassium permanganate to determine its oxygen content and then to determine that the mass fraction of calcium peroxide in the slow-release oxygen material was 61%. The static slow-release test (1 g of slow-release oxygen material was added and placed in 100 mL of boiled and cooled water) verified that its slow-release period reached 7 months.

[0138] Test Case

[0139] Test method:

[0140] Sediments from aquifers contaminated with benzene, toluene, and xylene were collected from a refinery. The initial total concentration of pollutants was 120 mg kg-1 In a nitrogen atmosphere glove box, the sediment was mixed with the slow-release oxygen materials prepared in Example 1 and Comparative Example 1, respectively, at a ratio of 5 g of slow-release oxygen material to 1 kg of sediment, and an appropriate amount of deionized water was added. The mixture was placed in a sealed glass bottle, protected from light, and reacted in a constant temperature shaking incubator.

[0141] The dissolved oxygen content of the slow-release oxygen material of Example 1 was 10 ppm, 18 ppm and 8 ppm after 1 month, 3 months and 8 months respectively, and the pollutant concentration was 109 mg kg after 1 month, 3 months and 8 months respectively. -1 , 86mg kg -1 and 16 mg kg -1 .

[0142] The dissolved oxygen content of the slow-release oxygen material in comparative example 1 was 19 ppm, 5 ppm and 0.4 ppm after 1 month, 3 months and 8 months respectively, and the pollutant concentration was 103 mg kg after 1 month, 3 months and 8 months respectively. -1 , 84 mg kg -1 and 79 mg kg -1 .

[0143] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A slow-release oxygen material, characterized in that: The slow-release oxygen material comprises a core component and a shell component; the core component comprises calcium peroxide, and the shell component comprises a carbon-based material; the particle size of the slow-release oxygen material ranges from 2 to 30 μm, and the D50 is 6 to 15 μm; The carbon-based material is obtained by calcining an organic polymer in an inert atmosphere at 150-260° C. for 5-50 minutes, and the organic polymer is at least one of carrageenan, gelatin, sodium alginate, ethyl cellulose and polyvinyl alcohol.

2. The slow-release oxygen material according to claim 1, wherein The weight ratio of the core component to the shell component is (5-80):

1.

3. The slow-release oxygen material according to claim 2, wherein: The weight ratio of the core component to the shell component is (10-30):

1.

4. The slow-release oxygen material according to claim 1, wherein The particle size of the slow-release oxygen material is in the range of 5-20 μm, and D50 is in the range of 8-13 μm.

5. The slow-release oxygen material according to claim 1 or 2, wherein The core component further comprises at least one of phosphate, silicate and carbonate; the shell component further comprises at least one of plastic binder, phosphate, silicate and carbonate.

6. A method for preparing a slow-release oxygen material, characterized in that: The method comprises the following steps: (1) mixing calcium peroxide with an organic polymer to obtain a mixed slurry; wherein the particle size of the calcium peroxide is in the range of 2-30 μm and the D50 is in the range of 6-15 μm; (2) drying and calcining the mixed slurry obtained in step (1) to obtain the slow-release oxygen material; The calcination is carried out under an inert atmosphere, and the calcination conditions include: a temperature of 150-260° C. and a time of 5-50 min. The organic polymer is at least one of carrageenan, gelatin, sodium alginate, ethyl cellulose and polyvinyl alcohol.

7. The method according to claim 6, wherein: The calcium peroxide is obtained by contacting calcium hydroxide and / or calcium oxide with hydrogen peroxide, and the molar ratio of the calcium hydroxide and / or calcium oxide to hydrogen peroxide is (1.01-1.3):

1.

8. The method according to claim 7, wherein: The contact conditions include: temperature of 0-30° C., time of 5-60 min, and stirring speed of 200-1000 rpm.

9. The method according to any one of claims 6 to 8, wherein: The amount of the organic polymer used is 12-600 g per kg of calcium peroxide.

10. The method according to any one of claims 6 to 8, wherein: The carbon content of the organic polymer is 20-55% by weight.

11. The method according to any one of claims 6 to 8, wherein: The organic polymer is selected from at least one of carrageenan, gelatin and sodium alginate.

12. The method according to any one of claims 6 to 8, wherein: In step (1), the mixing is carried out in the presence of an auxiliary agent, and the mixing conditions include: temperature of 0-30°C, time of 5-20 minutes, and stirring speed of 200-1000 rpm.

13. The method according to claim 12, wherein: In step (1), the amount of the auxiliary agent used is 10-100 g per kg of calcium peroxide.

14. The method according to claim 13, wherein In step (1), the auxiliary agent is selected from at least one of attapulgite, montmorillonite, kaolin, phosphate, silicate and carbonate.

15. The method according to any one of claims 6 to 8, wherein: In step (2), the drying includes a first drying and a second drying; the conditions for the first drying include: a temperature of 50-80°C and a time of 10-40 minutes; and a temperature of the second drying is 100-120°C.

16. The method according to any one of claims 6 to 8, wherein: In step (2), the calcination conditions include: temperature of 200-250°C and time of 10-30 minutes.

17. The method according to any one of claims 6 to 8, wherein: In step (2), the inert atmosphere is provided by nitrogen and / or argon.

18. The slow-release oxygen material obtained by the method according to any one of claims 6 to 17.

19. Use of the slow-release oxygen material according to any one of claims 1 to 5 and 18 in the remediation of organically contaminated soil and / or groundwater.

20. The use according to claim 19, wherein: The organic pollutants are selected from at least one of petroleum hydrocarbons, halogenated hydrocarbons, alcohols and ethers.

21. The use according to claim 20, wherein: The organic pollutants are selected from at least one of benzene, toluene, ethylbenzene, trimethylbenzene, methyl tert-butyl ether, tert-butyl alcohol, ethylene dichloride, vinyl dichloride, vinyl chloride, benzo[a]pyrene, benz[a]anthracene and naphthalene.

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