KR101130934B1 - Preparation method of micro core shell solid oxidant powder - Google Patents

Abstract

The present invention comprises the steps of (a) mixing the solid oxidant particles into the molten paraffin wax;

(b) dropping the mixture obtained in step (a) into water to prepare core-shell bulk particles; And

(c) milling the core-shell bulk particles to produce a micro core-shell solid oxidant powder;

It provides a method for producing a solid oxidant powder of a micro core-shell structure comprising a.

Potassium Permanganate, Core-Shell, Paraffin Wax, Solid Oxidizer, PCE

Description

Manufacturing method of solid oxidant powder of micro core shell structure {PREPARATION METHOD OF MICRO CORE SHELL SOLID OXIDANT POWDER}

The present invention relates to a method for producing a solid oxidant powder, and more particularly, it can be controlled to release the oxidant only to the contaminant selectively while minimizing the loss of non-specific oxidant until the transfer to the pollutant in the soil. The present invention relates to a method for producing a solid oxidant powder having a micro core-shell structure.

Controlled or delayed-release techniques have attracted interest in a variety of fields such as pharmaceutical and agrochemical technologies. Controlled release technologies for oxidants in subsurface environments are also emerging in the field of environmental engineering. In particular, controlled release of oxidants during in situ oxidation has been of interest.

In situ chemical oxidation of DNA No. (Dense Nonaqueous Phase Liquid) by potassium permanganate (KMnO ₄ ) has been described in many reports. Excess oxidant is often required to break down quickly due to non-specific oxidant loss. This is a problem that applies in most cases irrespective of the type of oxidant. For example, in a 3-D flow tank study, when the mass ratio of potassium permanganate to TCE (trichloroethylene, 1.0L) was 82: 1, it was completely degraded within 120 days. In another example, when the mass ratio of potassium permanganate to PCE (perchlorethylene, 0.576 L) was 73: 1, about 41% of the total mass of DNAPL was degraded for more than 63 days in a 1-D column experiment. The oxidant also reacts with natural organics, inorganic soil components and other reducing compounds, so that only a fraction of the applied oxidant actually reaches the target compound. Therefore, it is important to develop a delivery method that reduces the throughput of oxidant required to completely remove contaminants while minimizing nonspecific oxidant loss.

The healing performance of ISCO depends very strongly on how potassium permanganate is delivered to the contaminated area. Configurations of current delivery systems include pressurized direct push or auged probe permeation, soil mixing, hydraulic fracturing, vertical or horizontal well flushing, treatment walls, and oxidant recycling. However, very little research has been made, particularly with respect to controlled oxidant delivery systems, in potassium permanganate. OPMs (oxidant particle mixtures) of less than 5 mm have been reported containing potassium permanganate granules suspended in cement containing water as clay or carrier. However, once OPMs are introduced into underground soils or groundwater, their release rates are too slow, and the released oxidants are moved by molecular diffusion or advection to react with contaminants. Different approaches to release are required.

The present invention has been made to solve the above problems of the prior art as described above, the object of which is environmentally friendly and only oxidizing agent to the contaminant selectively, while minimizing the loss of non-specific oxidant until the movement to the contaminant in the soil It is to provide a method for producing a solid core oxidant powder of a micro core-shell structure that can be controlled to be released.

Another object of the present invention is a micro-core-shell structured solid oxidant powder which can be controlled to release the oxidant only to the pollutant selectively while minimizing the loss of non-specific oxidant until the transfer to the environmentally contaminant. In providing.

The technical problem of the present invention as described above is achieved by the following means.

(1) (a) mixing the solid oxidant particles into the molten paraffin wax;

(b) dropping the mixture obtained in step (a) into water to prepare core-shell bulk particles; And

(c) milling the core-shell bulk particles to produce a micro core-shell solid oxidant powder;

Method of producing a solid oxidant powder of the micro core-shell structure comprising a.

(2) The method of claim 1,

Molten paraffin wax is a method for producing a solid core oxidizer powder of a micro-core shell structure, characterized in that it is adjusted to less than 80 ℃.

(3) The method according to claim 1,

A solid oxidant is selected from oxidants capable of decomposing PCE and TCE.

(4) The method according to 1,

A solid oxidant is a method for producing a solid core oxidant powder having a microcore-shell structure, characterized in that permanganate.

(5) The method according to claim 1,

The solid oxidant powder is a method for producing a solid core oxidizer powder having a micro core-shell structure, characterized in that the average particle diameter of 10 to 20 ㎛.

(6) (a) pulverizing permanganate first and cooling down to room temperature, and repeating this process several times to an average particle diameter of 10 to 20 μm and storing in an atmosphere from which humidity is removed;

(b) mixing the permanganate particles in a molten paraffin wax maintained at less than 80 ° C. while raising the temperature to 8-12 ° C. per minute;

(c) dropping the reactant obtained in step (b) into water to prepare core-shell bulk particles; And

(d) removing moisture from the surface of the core-shell bulk particles obtained in step (c) and vacuum drying at room temperature; And

(e) pulverizing the coreshell bulk particles in a mill of 15,000 to 25,000 RPM for 1 to 3 minutes to produce a micro core-shell solid oxidant powder;

Method of producing a solid oxidant powder of the micro core-shell structure comprising a.

(7) A solid oxidant powder having a micro core-shell structure, which can be prepared by any one of items 1 to 6.

According to the present invention, there is provided a micro-core-shell structured solid oxidant powder which is environmentally friendly and can be controlled to release the oxidant only selectively to the pollutant while minimizing the loss of nonspecific oxidant until the movement to the pollutant in the soil. .

The present invention

(a) mixing the solid oxidant particles into the molten paraffin wax;

(b) dropping the mixture obtained in step (a) into water to prepare core-shell bulk particles; And

(c) milling the core-shell bulk particles to produce a micro core-shell solid oxidant powder;

It includes a method for producing a solid oxidant powder of a micro core-shell structure comprising a.

Hereinafter, the content of the present invention will be described in detail.

The core material constituting the solid core oxidant particles of the microcore-shell structure according to the present invention is a solid oxidant capable of treating various organic pollutants. That is, the solid oxidizing agent usable in the present invention can decompose organic substances such as, for example, carbon tetrachloride, benzene, chloroform, tetrachloroethylene (PCE), hexane, cyclohexane, or TCE, preferably TCE and PCE. And, preferably, permanganate (for example, KMnO ₄ ).

The core material may have an irregular shape such as spherical shape, elliptical shape or rod shape, and preferably has an average particle diameter of 10 to 20 μm, more preferably 12 to 16 μm. If the average particle size is less than 10 μm, the sustainability may decrease with an increase of the loss amount at an excessively fast dissolution rate. If the average particle size is more than 20 μm, the dissolution rate may be slow, so that it is difficult to efficiently process contaminants.

The shell (shell) constituting the core-shell structure of the present invention can be dissolved in the contaminants to be treated and must be inert with the core material and exist in a solid state at room temperature. It is also a biodegradable substance that can be decomposed in the natural environment and at the same time it is required to be insoluble in water in water treatment applications. Materials that meet this requirement are suitable materials which are solid at room temperature and consist of 80-90% by weight of straight hydrocarbons, preferably paraffin wax.

In particular, paraffin waxes are solid at room temperature and are soluble in many organic pollutants, including chlorides such as TCE and PCE, but are substantially insoluble in water and relatively inert to the oxidation of potassium permanganate. Furthermore, paraffin wax is an environmentally friendly material that can be degraded by various microorganisms, for example, Pseudomonas, Mycobartum, Nocadia, Corynebacterium, and micrococcus microorganisms.

In the present invention, as the mass fraction of the solid oxidant which becomes the core in the solid oxidant of the core-shell structure increases, the solid oxidant particles fixed (or embedded) on the surface of the shell increase to have a rough surface. When contacted with water, it may dissolve and form voids in the matrix, causing the initial release rate to be too high. On the other hand, as the mass fraction of the solid oxidant decreases, the oxidant particles are completely sequestered in the matrix (shell), so that the release rate of the oxidant is significantly lowered.

In consideration of such circumstances, the mass fraction of the matrix (shell) and the solid oxidant constituting the solid oxidant particles of the microcore-shell structure according to the present invention is preferably set in the range of 1: 1 to 5: 1. According to a preferred embodiment of the present invention, when the matrix is selected from paraffin wax and the endothelium is selected from potassium permanganate, the time at which 90% of the solid oxidant is released from the paraffin wax matrix in water within the mass fraction is 10, 36, 128 days is considered very appropriate.

The solid oxidant powder of the microcore-shell structure according to the present invention as described above may be prepared as follows.

1. The grinding process of the bulk solid oxidant:

First, the bulk solid oxidizing agent purchased from a company using a grinder is first pulverized so that the average size of a particle size may be 10-20 micrometers.

In this case, if the continuous grinding is performed for a long time, a problem arises in that the size of the pulverized particles is agglomerated in the heated state, thereby increasing the size. Thus, the solid oxidant powder is sufficiently pulverized in a pulverizer and cooled to room temperature, and then the process is repeated several times. It is good to carry out. Preferably about 50 to about 6 minutes, preferably about 5 minutes of grinding at a rate of 15,000 to 25,000 RPM, preferably approximately 20,000 RPM, in a grinder of approximately 200 liters based on 50 g of solid oxidizer powder After cooling down to room temperature for at least 6 hours, preferably 6 hours or more, it is good to repeat this process at least four times.

The solid oxidant powder pulverized through the above process is preferably stored in a vacuum dryer at room temperature until it is added to the next process in order to prevent the oxidizing power of the oxidant from lowering humidity.

2. Manufacturing process of paraffin wax melt :

In order to efficiently and safely melt the paraffin wax present in the solid state at room temperature, a predetermined amount of the solid paraffin wax is placed in a heat-resistant container of a suitable size and placed on a heating device (for example, a hot plate sheeter) that can be controlled in temperature. It is then important to maintain the final temperature of the heating device below 80 ° C. by heating gradually.

In this case, when the temperature is gradually heated on the heating apparatus, it is necessary to adjust the temperature so that it can be raised to about 8 to 12 ° C per minute. If the temperature rise of the paraffin wax is out of the above range, or if the temperature for melting the paraffin wax is 80 ° C. or higher, there is a risk that the formation of the desired core-shell structure itself is impossible, and the risk of explosion This is concerned and undesirable.

At this time, the formation of the solid core particles of the microcore-shell structure, which is finally obtained by inserting a Teflon-coated magnet pole to homogeneously completely melt the paraffin wax and mixing on a plate at a suitable speed, preferably 200 to 500 RPM, is achieved. It can be done smoothly.

3. Manufacturing Process of Bulk Particles with Core-Shell Structure :

The paraffin wax melt obtained through the above process was infused with an appropriate amount of the permanganate particles powdered to a micro size in an appropriate amount, and kept homogeneously mixed in the paraffin wax suspension.

The paraffin wax suspension prepared as described above may be dropped into clean water immediately after taking a certain amount using a tool such as a glass dropper to recover the core-shell structured bulk particles.

After removing water from the epidermis of the core-shell structured bulk particles obtained by the above process, it is completely dried using a vacuum dryer or the like for a predetermined time.

4. Manufacturing process of solid oxidant powder of micro core-shell structure :

The dry bulk core-shell particles as described above are pulverized with a impact grinder in contact with dry ice at a rotational speed of 15,000 to 25,000 RPM, preferably about 20,000 RPM, for about 1 minute to 3 minutes or less. You get a shell powder. Deviation from the above conditions makes it difficult to obtain a solid oxidant powder having a desired microcore-shell structure. The powder thus obtained is preferably stored in a vacuum dryer at room temperature until use.

The microcore-shell solid oxidant obtained by a series of processes according to the present invention, once introduced into underground soil or groundwater, migrates by diffusion or advection to reach an interface with contaminants, and the oxidant contacts water during the migration period. This prevents the loss of oxidant due to nonspecific release.

As shown in FIG. 1, when the coated solid oxides (EPPs) reach the interface with the organic pollutants in the ground by diffusion or advection (DNAPLs), the matrix is melted by the organic pollutants and water penetrates into the interior. MnO ₄ ^- is discharged through the matrix in the form of a) can be completely removed by contact with the organic contaminants. Thus, the solid oxidant delivery system according to the present invention can be controlled so that the oxidant is released only to the contaminant selectively, while minimizing the loss of nonspecific oxidant until migration to the contaminant.

Hereinafter, the content of the present invention will be described in more detail with reference to Examples. However, these examples are only presented to understand the content of the present invention, and the scope of the present invention should not be construed as being limited to these embodiments.

Example 1 Preparation of Solid Oxidizer Powder of Micro-Core Shell Structure

For the experiment KMnO ₄ (particle size, -325 US mesh; purity, 97%) was purchased from Aldrich and paraffin wax with a melting point of 50-55 ° C. was purchased from Fluka. Reagent grade water was prepared by distilled water purified by reverse osmosis and Bronsted NANOpure II deionization system (Ω = 18.0 MΩ / cm).

50 g of commercially available oxidant powder was pulverized in a 200 L pulverizer at a speed of 20,000 RPM for about 5 minutes using a batch impact pulverizer, and cooled to room temperature for at least 6 hours. Repeated times. The pulverized micro powder was stored in a vacuum dryer at room temperature until it was introduced to the next process in order to prevent the oxidizing power of the oxidizing agent due to humidity inflow.

10g of solid paraffin wax at room temperature was placed in a 1L pyrex glass beaker, placed on a temperature-controlled hotplate sheeter, and adjusted to rise by 10 degrees per minute to maintain the final temperature of the heating apparatus below 80 ° C.

Teflon-coated magnetic sticks were placed and mixed at 300 RPM on a plate to homogeneously melt the wax completely. 10 g of the micropowdered potassium permanganate particles were slowly added thereto and mixed homogeneously in the paraffin wax suspension.

About 0.5 mL of the paraffin wax suspension was taken with a glass dropper and immediately dropped into clean water. The core-shell bulk oxidant particles thus prepared were recovered. Then, the moisture was removed from the epidermis using a vacuum filter and dried in a vacuum dryer at room temperature for 24 hours.

Through the above process, the dried bulk core-shell particles were pulverized for 1 minute at a rotational speed of 20,000 RPM with an impact mill in contact with dry ice, thereby obtaining a solid core powder of a microcore-shell structure. The powder obtained was stored in a vacuum dryer at room temperature until use.

Comparative Example Preparation of Solid Oxide Powder of Micro-Core Shell Structure

The experiment was carried out by the same procedure as in Example 1 except changing only the conditions shown in Table 1.

TABLE 1

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Wax heating temperature 80 ℃ 85 ℃ Same as Example Same as Example Grinding Conditions for Bulk Core-Shell Particles Same as Example Same as Example 15,000 RPM (3 minutes) 25,000 RPM (3 minutes) Final product Bad Poor (explosion) Bad Bad

Experimental Example

Experiment method

Particle size distribution and average particle size were determined using Beckman Coulter LS 230. Approximately 0.15 g of test substance was placed in a sample container with 20 mL of toluene (for UPPs) or isopropyl alcohol (EPPs) as a suspension. Samples were sonicated at 45 W for 5 minutes in a water bath to prevent aggregation.

Thermal properties of the samples were measured using a DSC 2920 system. As the fuzz gas, 35 mL / min of nitrogen was used, and the initial temperature was set at 20 ° C with a gradient of 10 ° C per minute up to 140 ° C.

The extraction process was performed to determine the actual mass of potassium permanganate in the paraffin wax and the recovery rate of potassium permanganate loaded on EPPs. EPPs were placed in a 25 mL volumetric flask containing 20 mL cyclohexane, capped and placed on a rotary wheel shaker for 24 hours to completely dissolve paraffin wax. The suspension was transferred to a 1.0 L volumetric flask and potassium permanganate was extracted by adding reagent grade water. The aqueous layer and the organic layer were mixed vigorously for about 1 hour and kept in contact for an additional hour to separate the organic and water phases. The concentration of permanganate ions in the water phase was measured by absorbance at 552 nm using a UV-visible spectrophotometer, and manganese with an electron absorption spectrophotometer (AAS, Varian SpectrAA-20 Plus) equipped with a graphite tube atomizer. Was determined by measuring. The molar absorbance of permanganate ions at a wavelength of 522 nm is 2221 M ^-1 cm ^-1 .

In order to uniformly mix EPPs (mass ratio of paraffin wax / potassium permanganate at 0.30, 0.15 and 0.10 g, respectively 5: 1, 2: 1, and 1: 1, respectively), the reagents were mixed at a constant temperature of 200 RPM at room temperature by mechanical stirring. Introduced in 1.0 L of water. Take 40 mL of the aqueous sample at 1,2,3,4,5,10,20,30,60,120,800, and 1200 minutes using a glass syringe equipped with a stainless steel needle, taking special care to prevent particle inhalation. Was transferred to a 7 mL glass vial. In another experiment, EPPs were transferred to pure PCE and confirmed that the paraffin wax shell quickly decomposed when in contact with the desired contaminant. 0.10 g of EPPs with varying W / P (wax / potassium permanganate) ratios were poured into 5 mL of pure PCE and shaken for 1 minute in an orbit shaker at 200 RPM at room temperature. The concentration of permanganate ions in the aqueous solution was determined by measuring absorption at 552 nm using a UV-visible spectrophotometer. The release of potassium permanganate from UMPPs into reagent grade water was measured as a control experiment.

Experiment result

After decomposition of the paraffin wax shell, recovery of potassium permanganate in aqueous solution reached 100%. SEM images and size distribution of UPPs are shown in FIGS. 2A and 2B. UPPs have very irregular shapes, including ellipses or rods, with sharp edges and different particle distributions. Referring to Figure 2a, it can be seen from the comparison of the two images before (A) and after (B) grinding of the particles that the grinding significantly reduces the size of the UPPs. As shown in the particle size distribution measurement results in Figure 2b, it was confirmed that the average particle size (± standard deviation) was reduced from 152 (± 222) to 15 (± 9) ㎛ after grinding for 20 minutes. However, as can be seen in FIGS. 2A and 2B, particles much smaller than the average diameter were observed in each batch.

Optical photographs of particles of potassium permanganate coated with paraffin wax are shown in FIG. 2. Figure 3 (A) is an optical photograph when paraffin wax (W): potassium permanganate (P) = 1: 1, (B) is an optical photograph when W: P = 2: 1, respectively, viewed from above The average diameter was about 0.5 to 5 mm in the photograph and the side view.

Encapsulated potassium permanganate granules (EPGs) with this diameter were ground to make smaller particles, as shown in FIG. 4A. (A) and (B) of FIG. 4A are ESEM images and partial enlarged images of particles having W: P = 1: 1 after powdering for 3 minutes, respectively, and (C) and (D) are respectively W: P = 2. Show ESEM images of particles with 1: and particles with W: P = 5: 1. These ESEM images show that the multinucleated and micronized potassium permanganate particles are randomly trapped in the paraffin wax substrate, and the EPPs (50% at 1: 1 W / P) with high mass fraction of potassium permanganate are embedded in the surface of potassium permanganate. It can be seen that it contains more particles and has a rougher surface than when the mass fraction is small (33.3% at 2: 1 W / P). There was no significant difference in mean diameter for the other mass ratios W / P.

EPPs particle distribution for the 2: 1 W / P can be seen that the average particle diameter of 874 ± 377㎛ follows the bimodal curve (Bimodal) as shown in Figure 4b. The particle size distribution curves are shown in pairs. The particle size distribution was found to be relatively reproducible even when randomly sampling the powder as well as the speed change in the loop system module used in this experiment. The sum of deviations from all data points of the double samples was 17.2% (vol%) for 100% total volume.

In addition, according to Figure 4b it can be seen that some EPPs are aggregated. Paraffin wax is very adhesive and shows a second peak at a particle diameter of 1700 μm.

DSC data shows the melting behavior of paraffin wax before and after the modified MSC process. It can be seen from Figure 5 that the potassium permanganate particles and paraffin wax are inert to each other over a temperature range. Most paraffin oils contain about 0.5% residual oil and do not typically have sharp melting points. Two distinct melting ranges were observed for paraffin wax with small peaks at 30-50 ° C. and large peaks at 50-70 ° C. The presence of potassium permanganate does not provide a significant difference in the melting point of the wax. It is believed that the solid potassium permanganate does not react with the paraffin wax over the temperature range during the MSC process. This fact indicates that significant oxidation of paraffin waxes exposed to oxidants does not occur up to 93 ° C. and requires at least 121 days of 3 days. Thus, it can be seen that paraffin wax does not cause nonspecific loss of potassium permanganate upon delivery and migration of particles.

6 shows the elution characteristics of potassium permanganate from EPPs to reagent grade water. Dissolution of UPPs was immediate (within 1 minute) while EPPs were significantly slowed. However, in the case of EPPs, 10-30% of potassium permanganate was released over a week. It can be seen that the release of solid oxidant from the particles into the water is biphase, exhibiting early rapid release (less than 10 minutes) followed by delayed release behavior. Early rapid release is due to the dissolution of partially coated oxidant particles that are uncoated or buried on or near the surface of the EPPs. This dissolution of the oxidant on the surface of EPPs can be seen in FIG. 7 shows as an example when W: P = 5: 1, the solid oxidant particles embedded in the matrix surface are dissolved and released after 4 days of continuous contact with water to form grooves on the surface of the paraffin wax matrix. You can see that.

These results are consistent with previous reports that high hydrophilic core materials such as potassium chloride exhibit a biphasic release pattern. Fast stirring reactors provide large disturbance conditions, and therefore the measured release rate into water is considered to be the upper limit. The release rate of EPPs is slowed in environments with relatively less turbulent properties, such as groundwater flow.

As a result of predicting the 90% emission time experimentally for EPPs while changing the value of W / P, the following equation was predicted. It was judged that the potassium permanganate fraction was sufficiently sequestered in the paraffin wax substrate as it was 36 days and 128 days, so that the water was difficult to access and the rate of water penetration or diffusion into the wax was sufficiently delayed.

M _t = k ₀ t + C, t _{90 %} = (0.9M ₀ -C) / k ₀

In the above formula, M _t and M ₀ represent the mass of the solid oxidant at time t and 0, respectively, C is a constant and k ₀ represents the normal release rate (g / day).

TABLE 1

W: P (mass) Steady release rate, k _o (g / day) 90% emission estimation time, t _{90 %} (days) 1: 1 3.34 × 10 ^-3 (r ² = 0.999) 10 2: 1 1.07 × 10 ^-3 (r ² = 0.093) 36 5: 1 3.20 × 10 ^-4 (r ² = 0.993) 128

The results show that the release rate is proportional to the mass fraction of UPPs and inversely proportional to the mass fraction of paraffin wax.

As a result of performing the decomposition test of paraffin wax in PCE, all three cases confirmed that paraffin wax was completely decomposed within 3 minutes. This means that potassium permanganate can be released rapidly when EPPs come in contact with the desired contaminant.

8 shows how EPPs behave in water in the presence of PCE droplets before and after shaking the suspension. EPPs aggregate at the interface of the free phase PCE because of the affinity of paraffin wax for PCE. EPPs gathered at the interface between the free phase PCE and water represent a local increase in oxidant concentration in the bulk solution.

This confirms that the paraffin wax used as the matrix material of solid potassium permanganate is suitable as a coating material. Furthermore, paraffin waxes are solid at room temperature and consist of 80 to 90% by weight of straight hydrocarbons. Paraffin waxes are also soluble in many organic pollutants, including chlorides such as TCE and PCE. However, it is practically insoluble in water and relatively inert to the oxidation of potassium permanganate. Moreover, paraffin wax is a biodegradable material that can be decomposed by various microorganisms, which is very suitable in that it is an environmentally friendly material.

As described above, the method for producing a solid oxidant powder according to the present invention does not require special equipment, scales up easily, does not require an organic solvent, and has a very high coating efficiency of potassium permanganate. It was confirmed that it can be provided by excellent means.

As described above, it has been described with reference to a preferred embodiment of the present invention, but those skilled in the art various modifications and changes of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Figure 1 is a schematic diagram showing the delivery process during treatment to the soil contaminants of the solid oxidant powder according to the present invention.

2 shows SEM images and size distributions of uncoated permanganate salts (UPPs) according to the present invention.

3 is a photograph of particles of encapsulated potassium permanganate prepared according to the present invention.

4 is an ESEM image of microparticles obtained by grinding encapsulated potassium permanganate granules (EPGs) according to the present invention.

FIG. 5 shows the results of DSC analysis of (A) paraffin wax, (B) physical mixture of paraffin wax and uncoated potassium permanganate particles, and (C) potassium permanganate particles (1: 1 W / P) of core-shell structure.

6 is an experimental result showing the dissolution characteristics of potassium permanganate from EPPs to reagent grade water.

Figure 7 is an ESEM image showing the surface of the potassium permanganate particles of the core-shell structure prepared according to the present invention.

8 is an experimental result showing that the core-shell structure of potassium permanganate particles prepared according to the present invention by comparing the behavior in water in the presence of PCE droplets (A: before shaking, B: 10 minutes after shaking for 1 minute).

Claims (7)

(a) pulverizing permanganate first and cooling down to room temperature, and then repeating this process several times to an average particle diameter of 10 to 20 μm and storing in an atmosphere from which humidity is removed; (b) mixing the permanganate particles in a molten paraffin wax maintained at less than 80 ° C. while raising the temperature to 8-12 ° C. per minute; (c) dropping the reactant obtained in step (b) into water to prepare core-shell bulk particles; And (d) removing moisture from the surface of the core-shell bulk particles obtained in step (c) and vacuum drying at room temperature; And (e) pulverizing the coreshell bulk particles in a mill of 15,000 to 25,000 RPM for 1 to 3 minutes to produce a micro core-shell solid oxidant powder; Method of producing a solid oxidant powder of the micro core-shell structure comprising a. A solid oxidant powder having a micro core-shell structure which can be prepared by claim 1. delete delete delete delete delete

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