KR102262171B1 - Sillica-based entrapping agent for treating carbon dioxide containing radioactive carbon and system and method for treating carbon dioxide containing radioactive carbon using the same - Google Patents

Abstract

The present invention relates to a silica structure; and a silica-based collector for treating carbon dioxide containing radioactive carbon containing an alkaline earth metal impregnated in the silica structure, and a system and method for treating carbon dioxide containing radioactive carbon using the same.

Description

Silica-based trapping agent for radiocarbon-containing carbon dioxide treatment, and radiocarbon-containing carbon dioxide treatment system and method using the same

The present invention relates to a silica-based trapping agent for treating carbon dioxide containing radioactive carbon, and a system and method for treating carbon dioxide containing radioactive carbon using the same.

Among the various wastes generated from nuclear power facilities, the problem of treatment of carbon waste containing radioactive carbon (C-14) is becoming a serious problem. Not only is the amount of radiocarbon-containing carbon waste stored and stored in nuclear facilities significant, but the half-life of radiocarbon is also incredibly long, about 5730±40 years. Moreover, unlike other radionuclides, since radiocarbon can be substituted with organic matter, it has the potential to be very harmful to living things, so it must be treated in a stable form.

When carbon waste containing radiocarbon (C-14) is thermochemically treated, carbon dioxide containing radioactive carbon is generated, which requires a technology to capture it and make it into a form suitable for subsequent treatment. Accordingly, various methods have been developed to effectively capture radiocarbon-containing carbon dioxide. In order to make it suitable for subsequent treatment, it should be captured in the form of carbonate. However, since extreme conditions are mainly required to form the carbonate, it is not suitable in terms of stability and economical efficiency of radioactive waste when dealing with carbon dioxide containing radioactive carbon. Therefore, there is a need for a technology for capturing radiocarbon-containing carbon dioxide with high efficiency (fast reaction rate and high capture capacity) under mild reaction conditions.

Korean Patent Publication No. 10-0737697 (2007. 07. 03.)

The present invention is a technology for capturing radioactive carbon-containing carbon dioxide with high efficiency (fast reaction rate and high capture capacity) under mild reaction conditions, specifically, a silica-based collector for radiocarbon-containing carbon dioxide treatment, and radioactive carbon-containing carbon dioxide using the same It is intended to provide a processing system and method.

However, the technical problem to be achieved by the present invention is not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention relates to a silica structure; And it provides a silica-based trapping agent for treating carbon dioxide containing radioactive carbon comprising an alkaline earth metal impregnated in the silica structure.

In one embodiment of the present invention, a carbon dioxide gas cylinder for supplying carbon dioxide containing radioactive carbon; a carbon dioxide capture reactor for converting the supplied carbon dioxide into liquefaction and carbonate; and a carbon dioxide detector for detecting the generation of the non-captured carbon dioxide, wherein the carbon dioxide capture reactor includes the silica-based scavenger.

In another embodiment of the present invention, supplying carbon dioxide containing radioactive carbon to a carbon dioxide capture reactor to liquefy; converting the supplied carbon dioxide into carbonate by reacting with the silica-based scavenger; And it provides a method for treating carbon dioxide containing radioactive carbon, comprising the step of separating the silica-based trapping agent in which the carbonate is collected.

The silica-based trapping agent for the treatment of carbon dioxide containing radioactive carbon according to the present invention has a silica structure; and an alkaline earth metal impregnated in the silica structure. When the silica-based collector is dispersed in water, the silica-based collector may be in a gel state, and the alkaline earth metal is the silica structure. By forming an unstable ionic bond with oxygen, there is an advantage that the alkaline earth metal can easily react with carbon dioxide containing radioactive carbon even under mild conditions such as room temperature and atmospheric pressure. Therefore, it is possible to capture radiocarbon-containing carbon dioxide with high efficiency (fast reaction rate and high capture capacity).

1 is a molecular level schematic diagram showing the ionic bond between oxygen and strontium (Sr) in a silica structure in a silica-based trapping agent for treating carbon dioxide containing radioactive carbon according to an embodiment of the present invention.
2 is a schematic diagram showing a carbon dioxide treatment system containing radioactive carbon according to an embodiment of the present invention.
3 is a photograph comparing SEM images of the silica-based trapping agent according to Example 1 before (a) and after (b) reaction with carbon dioxide.
4 is a graph comparing the XRD patterns of the silica-based trapping agent according to Example 1 before and after reacting with carbon dioxide.
5 is a graph comparing the TGA curve of the silica-based trapping agent according to Example 1 before and after reacting with carbon dioxide.
6 (a) to (c) are graphs showing the carbon dioxide capture amount calculated from the silica-based scavenger according to Examples 1 to 3 after reacting with carbon dioxide according to the reaction time with carbon dioxide.
7 is a graph of measuring the concentration of ^{Sr 2+ in} an aqueous solution according to a reaction time with carbon dioxide.

According to the conventional method, there have been examples of using calcium oxide or the like as a method for capturing radiocarbon-containing carbon dioxide in the form of carbonate, but in the case of calcium oxide, calcium and oxygen are covalently linked, so it is a very stable mineral by itself. are treated Therefore, when using this, the mineralization (carbonation) reaction for capturing the radiocarbon-containing carbon dioxide in the form of carbonate hardly occurs under mild conditions such as room temperature and atmospheric pressure, or even if it occurs, there is a limit that the rate is very slow. The reaction must be carried out under extreme conditions such as high pressure. On the other hand, there is a problem in that a large amount of energy is required to set high temperature and high pressure conditions, and the process becomes complicated.

Accordingly, the present inventors prepared a silica-based collector for carbon dioxide treatment containing radioactive carbon in which the alkaline earth metal forms an unstable ionic bond with oxygen in the silica structure by impregnating the alkaline earth metal in the silica structure instead of the conventional method, and using this , confirmed that radiocarbon-containing carbon dioxide can be captured with high efficiency (fast reaction rate and high capture capacity) even under mild conditions such as room temperature and pressure, and completed the present invention.

As used herein, "radioactive carbon" is a type of carbon isotope, and generally refers to C-14. Radiocarbon also has an incredibly long half-life of about 5730±40 years. Moreover, radiocarbon, unlike other radionuclides, can be substituted with organic matter, so it has the potential to be very harmful to living things.

Hereinafter, the present invention will be described in detail.

Silica-based trapping agent for carbon dioxide treatment containing radioactive carbon

The present invention relates to a silica structure; And it provides a silica-based trapping agent for treating carbon dioxide containing radioactive carbon comprising an alkaline earth metal impregnated in the silica structure.

Optionally, as an additive for forming a glass material in the silica structure, any one or more of boron, sodium and potassium may be further impregnated.

First, the silica-based collector for treating carbon dioxide containing radioactive carbon according to the present invention refers to a glass material for collecting carbon dioxide containing radioactive carbon in the form of a carbonate, and the silica-based collector may be in a dispersed state in water. . When the silica-based trapping agent is dispersed in water, the surface of the silica-based trapping agent may be converted from a glass state to a gel state.

Specifically, the silica-based scavenger for treating carbon dioxide containing radioactive carbon according to the present invention includes a silica structure as a skeleton of a glass material. The silica structure refers to a form in which oxygen (O) is shared by two silicon (Si), and may be a network structure including both a crystalline structure and an amorphous structure.

In addition, the silica-based trapping agent for treating carbon dioxide containing radioactive carbon according to the present invention includes an alkaline earth metal impregnated in the silica structure. When the silica-based scavenger is dispersed in water, the alkaline earth metal may form an unstable ionic bond with oxygen in the silica structure. A molecular level schematic diagram showing the ionic bond between oxygen and strontium (Sr) in the silica structure is shown in FIG. 1 . Therefore, there is an advantage that the alkaline earth metal can easily react with carbon dioxide containing radioactive carbon even under mild conditions such as room temperature and atmospheric pressure.

More specifically, the alkaline earth metal may include at least one selected from the group consisting of strontium (Sr), calcium (Ca), barium (Ba), radium (Ra), magnesium (Mg), and beryllium (Be), Considering the radius size, it is preferable to include strontium (Sr) or calcium (Ca), and more preferably include strontium (Sr), but is not limited thereto.

On the other hand, the silica-based collector for treating carbon dioxide containing radioactive carbon according to the present invention is a glass material, silica: boron oxide, sodium oxide, potassium oxide or a mixture thereof: alkaline earth metal oxide 40: 30: 30 to 30: 20: It may be included in a molar ratio of 50, preferably included in a molar ratio of 37: 28: 35 to 32: 23: 45, but is not limited thereto.

In this case, the silica serves to constitute a skeleton of the glass material of the silica-based collector. In addition, in the boron oxide, sodium oxide or potassium oxide, oxygen reacts with the silica, and boron, sodium or potassium is impregnated in the silica structure to form a backbone, respectively, to form a glass material for lowering the viscosity and melting point It serves as an additive for At this time, when potassium is used instead of boron or sodium, it is determined that a larger space is occupied in the glass structure due to the large ionic radius of potassium. Therefore, when dispersed in water, potassium dissolves into the water and opens a way for alkaline earth metals (Sr, Ca, etc.) to escape. As a result, a faster reaction rate can be expected in the case of capturing radiocarbon-containing carbon dioxide. In addition, in the alkaline earth metal oxide, oxygen reacts with the silica, and the alkaline earth metal reacts with radioactive carbon-containing carbon dioxide in an impregnated state in the silica structure, and the alkaline earth metal oxide is preferably included in a molar ratio as high as possible. , when the molar ratio is too high, there is a problem in that the silica structure does not completely form the skeleton of the glass material.

Radiocarbon-containing carbon dioxide treatment system and method

The present invention is a carbon dioxide gas cylinder for supplying carbon dioxide containing radioactive carbon; a carbon dioxide capture reactor for converting the supplied carbon dioxide into liquefaction and carbonate; and a carbon dioxide detector for detecting the generation of the non-captured carbon dioxide, wherein the carbon dioxide capture reactor includes the silica-based scavenger.

First, the system for treating carbon dioxide containing radioactive carbon according to the present invention includes a carbon dioxide gas cylinder; carbon dioxide capture reactor; and a carbon dioxide detector, and optionally, a centrifuge, and each device may be connected via tubing.

2 is a schematic diagram showing a carbon dioxide treatment system containing radioactive carbon according to an embodiment of the present invention, a carbon dioxide gas cylinder 10; carbon dioxide capture reactor 20; and a carbon dioxide detector 30 .

Specifically, the system for treating carbon dioxide containing radioactive carbon according to the present invention includes a carbon dioxide gas cylinder, wherein the carbon dioxide gas cylinder serves to supply carbon dioxide containing radioactive carbon. A main valve, a regulator, and a needle valve may be further included sequentially at the rear end of the carbon dioxide gas cylinder.

To this end, the carbon dioxide gas cylinder may be charged with a carbon waste gas containing radioactive carbon and optionally a catalyst, which may be carried out under oxygen or air. In addition, the carbon dioxide gas cylinder needs to maintain temperature and pressure conditions for generating radioactive carbon-containing carbon dioxide from radioactive carbon-containing carbon waste gas, and a temperature of 40° C. to 200° C. and a pressure of ^{10 -1} Pa to 10 ^{5 Pa.} It is preferable to maintain the conditions, but is not limited thereto.

In addition, the radiocarbon-containing carbon dioxide treatment system according to the present invention includes a carbon dioxide capture reactor, wherein the carbon dioxide capture reactor serves to convert the supplied carbon dioxide into liquefaction and carbonate. A plurality of the carbon dioxide capture reactor may be connected in series.

The rate of carbon dioxide supplied to the carbon dioxide capture reactor may be 0.5 ml/min to 5.0 ml/min, preferably 0.5 ml/min to 2.0 ml/min, but is not limited thereto. At this time, when the speed of carbon dioxide supplied to the carbon dioxide capture reactor is increased compared to the above range, there is a problem in that excessive generation of uncollected carbon dioxide occurs.

In particular, the carbon dioxide trapping reactor includes the silica-based trapping agent, and the silica-based trapping agent may be dispersed in water. The carbon dioxide capture reactor may be equipped with a stirring device for dispersing the water and the silica-based collector. At this time, since the "silica-based collector", in particular, the "silica collector dispersed in water" has been described above, a redundant description thereof will be omitted.

The carbon dioxide trapping reactor may include 1 g to 10 g of the silica-based trapping agent with respect to 100 ml of the water, and preferably includes 2 g to 6 g of the silica-based trapping agent, but is not limited thereto. This is the content set to minimize the generation of excess carbon dioxide that is not captured.

Dispersion of the silica-based trapping agent in the carbon dioxide trapping reactor may be performed at 100 rpm to 1,000 rpm conditions, and preferably performed at 300 rpm to 1,000 rpm conditions, but is not limited thereto. Accordingly, the silica-based collector can be well dispersed in water.

Since the alkaline earth metal in the silica-based trapping agent has an advantage that it can easily react with carbon dioxide containing radioactive carbon, the carbon dioxide trapping reactor has sufficient advantages even when maintaining mild conditions such as room temperature and atmospheric pressure. Therefore, it is preferable that the carbon dioxide capture reactor maintain a temperature of 20° C. to 40° C. and a pressure condition of 0.5 atm to 1.5 atm, but is not limited thereto. In addition, the carbon dioxide capture reaction may be performed within 5 hours, preferably for 1 hour to 3 hours.

Optionally, it may further include a centrifuge for separating the carbonate (or the silica-based trapping agent in which the carbonate is collected) converted in the carbon dioxide capture reactor.

In addition, the radiocarbon-containing carbon dioxide treatment system according to the present invention includes a carbon dioxide detector, wherein the carbon dioxide detector serves to detect the generation of the excess carbon dioxide that is not captured. This can be checked continuously and in real time.

In addition, the present invention comprises the steps of supplying carbon dioxide containing carbon dioxide to the carbon dioxide capture reactor to liquefy; converting the supplied carbon dioxide into carbonate by reacting with the silica-based scavenger; And it provides a method for treating carbon dioxide containing radioactive carbon, comprising the step of separating the silica-based trapping agent in which the carbonate is collected. Alternatively, the above-described "radiocarbon-containing carbon dioxide treatment system" may be applied to the method.

As described above, the silica-based scavenger for the treatment of carbon dioxide containing radioactive carbon according to the present invention has a silica structure; and an alkaline earth metal impregnated in the silica structure. When the silica-based collector is dispersed in water, the silica-based collector may be in a gel state, and the alkaline earth metal is the silica structure. By forming an unstable ionic bond with oxygen, there is an advantage that the alkaline earth metal can easily react with carbon dioxide containing radioactive carbon even under mild conditions such as room temperature and atmospheric pressure. Therefore, it is possible to capture radiocarbon-containing carbon dioxide with high efficiency (fast reaction rate (1.7 mmol/gh or more) and high capture capacity (4.20 mmol/g or more)).

Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are only provided for easier understanding of the present invention, and the contents of the present invention are not limited by the following examples.

[Example]

Example 1

(1) SiO ₂ , B ₂ O ₃ , Na ₂ O and SrO were mixed in a molar ratio of 35: 20: 5: 40, and then placed in a platinum crucible. Thereafter, it was melted at 1350° C. for 2 hours, then quenched and pulverized, and then pulverized with a planetary mill, and recovered to a predetermined size through an auto sieve to prepare a silica-based trapping agent. At this time, the SEM image, XRD pattern, and TGA curve of the silica-based collector are confirmed through FIGS. 3 (a), 4 and 5 (a), respectively. Then, 50 ml of ultrapure water and 2 g of a silica-based trapping agent were added to the carbon dioxide trapping reactor 20, and then the reactor lid was closed. Thereafter, the silica-based trapping agent was well dispersed in ultrapure water by stirring at a high speed of 500 rpm using a stirring device provided in the carbon dioxide trapping reactor 20 .

(2) Instead of generating radioactive carbon-containing carbon dioxide by injecting radioactive carbon-containing carbon waste gas and platinum catalyst into the carbon dioxide gas cylinder 10 under oxygen or air, as a simulation experiment, carbon dioxide is introduced into the carbon dioxide gas cylinder 10 carbon dioxide was generated. By opening the main valve located at the rear end of the carbon dioxide gas cylinder 10, the generated carbon dioxide was moved along the plastic tubing at a rate of 1 ml/min to the regulator. Thereafter, a needle valve located at the rear end of the regulator was opened, and the moved carbon dioxide was supplied to the carbon dioxide capture reactor 20 along the plastic tubing.

(3) The supplied carbon dioxide was liquefied for 3 hours in the carbon dioxide capture reactor 20 maintaining a temperature of 25° C. and a pressure of 1 atm, and then a reaction of converting it into carbonate was carried out, and the reaction was carried out through droplets generated in the aqueous solution. Check whether this is going on.

(4) The generation of uncollected carbon dioxide was continuously and real-time confirmed through the carbon dioxide detector 30 .

(5) After the carbon dioxide capture reaction was completed, the silica-based collector and the aqueous solution in which the carbonate was collected were separated and recovered through a centrifugal separator (not shown), and the aqueous solution was diluted and used for concentration measurement, and the silica in which the carbonate was collected The system collector was completely dried and then used for quantitative and qualitative analysis. At this time, the SEM image, XRD pattern, and TGA curve of the silica-based collector in which the carbonate is collected are confirmed through FIGS. 3(b), 4 and 5(a)-(b), respectively. In addition, the carbon dioxide capture amount calculated from the silica-based trapping agent in which the carbonate is collected is confirmed through FIG. On the other hand, the aqueous solution was diluted for each time period and used for concentration measurement. At this time, ^{the concentration of Sr 2+ in} the aqueous solution is confirmed through FIG. 7 .

As shown in FIG. 3(a), the average particle size of the silica-based trapping agent according to Example 1 before reacting with carbon dioxide was found to be at a fine level of about 100 µm or less (about 75 µm), but FIG. 3(b) ), after reacting with carbon dioxide, the silica-based trapping agent according to Example 1 undergoes a mineralization (carbonation) reaction, and it is confirmed that a large number of _{SrCO 3 is generated.}

As shown in FIG. 4 , unlike the silica-based trapping agent according to Example 1 before reacting with carbon dioxide, the silica-based trapping agent according to Example 1 after reacting with carbon dioxide shows an XRD peak at the indicated portion, which is It is confirmed that this is due to the production of _{SrCO 3 .}

5, unlike the silica-based trapping agent according to Example 1 before reacting with carbon dioxide, the silica-based trapping agent according to Example 1 after reacting with carbon dioxide shows a sharp change in the TGA curve at 600°C. , this may be attributed to the thermal decomposition of carbonate.

As shown in FIG. 6(a), after reacting with carbon dioxide, the amount of carbon dioxide capture (CO ₂ capacity) from the silica-based scavenger according to Example 1 was calculated through the following formula:

CO ₂ capacity (mmol CO ₂ /g adsorbent) =

이고, A는 이산화탄소가 분해되기 시작하는 600 ℃의 온도에서 TGA로부터 획득된 중량 %이고, B는 TGA 곡선이 안정된 경우에 중량 %이다. where X is

, A is the weight % obtained from TGA at a temperature of 600° C. at which carbon dioxide begins to decompose, and B is the weight % when the TGA curve is stable.

As a result, it is confirmed that carbon dioxide can be captured with high efficiency (fast reaction rate (1.7 mmol/gh) and high capture capacity (4.26 mmol/g)).

As shown in FIG. 7 , before the reaction with carbon dioxide, Sr ²⁺ was leached from the silica-based trapping agent in the aqueous solution, and it was confirmed that the concentration of ^{Sr 2+ in the aqueous solution was very high.} However, as the reaction with carbon dioxide starts, it is confirmed that the concentration of ^{Sr 2+ in the aqueous solution is rapidly reduced.}

Example 2

A carbon dioxide capture reaction was performed in the same manner as in Example 1, except that _{K 2} O was used instead of _{Na 2 O.}

As shown in FIG. 6(b), after reacting with carbon dioxide, the amount of carbon dioxide capture (CO ₂ capacity) from the silica-based scavenger according to Example 2 was calculated through the above formula. As a result, the collection capacity (4.20 mmol/g) is somewhat lower than that of the silica-based collector according to Example 1 (4.26 mmol/g), but carbon dioxide is captured at a particularly fast reaction rate (2.1 mmol/gh). confirmed that it can be done.

Example 3

A carbon dioxide capture reaction was performed in the same manner as in Example 1, except that CaO was used instead of SrO.

As shown in FIG. 6(c) , after reacting with carbon dioxide, the carbon dioxide capture amount (CO ₂ capacity) from the silica-based scavenger according to Example 3 was calculated through the above formula. As a result, the efficiency and capture capacity are somewhat lowered compared to the silica-based collector according to Example 1, but carbon dioxide is still captured with high efficiency (fast reaction rate (1.476 mmol/gh) and high capture capacity (3.69 mmol/g)) confirmed that it can be done.

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims (13)

silica structure; and
a glass material comprising an alkaline earth metal impregnated in the silica structure;
Silica-based trapping agent for carbon dioxide treatment containing radioactive carbon.
According to claim 1,
The silica-based collector is a silica-based collector for the treatment of carbon dioxide containing radioactive carbon in a dispersed state in water.
The silica-based trapping agent for treating radiocarbon-containing carbon dioxide according to claim 2, wherein the silica-based trapping agent dispersed in water has a gel-like surface.
According to claim 1,
As an additive in the silica structure, at least one of boron, sodium and potassium is further impregnated, a silica-based scavenger for treating carbon dioxide containing radioactive carbon.
5. The method of claim 4,
The silica-based scavenger is silica: boron oxide, sodium oxide, potassium oxide or a mixture thereof: an alkaline earth metal oxide in a molar ratio of 40: 30: 30 to 30: 20: 50, radiocarbon-containing silica-based carbon dioxide treatment collector.
According to claim 1,
The alkaline earth metal forms an ionic bond with oxygen in the silica structure, a silica-based scavenger for treating carbon dioxide containing radioactive carbon.
According to claim 1,
The alkaline earth metal includes at least one selected from the group consisting of strontium (Sr), calcium (Ca), barium (Ba), radium (Ra), magnesium (Mg) and beryllium (Be), for carbon dioxide treatment containing radioactive carbon Silica-based trapping agent.
a carbon dioxide gas cylinder for supplying carbon dioxide containing radioactive carbon;
a carbon dioxide capture reactor for collecting the supplied carbon dioxide by converting it into liquefaction and carbonate; and
A carbon dioxide detector for detecting the generation of carbon dioxide not captured in the carbon dioxide capture reactor,
The carbon dioxide capture reactor comprises a silica-based scavenging agent according to any one of claims 1 to 7, a carbon dioxide treatment system containing radioactive carbon.
9. The method of claim 8,
The carbon dioxide capture reactor includes water, with respect to 100 ml of the water, 1 g to 10 g of the silica-based trapping agent is included, a radiocarbon-containing carbon dioxide treatment system.
delete 9. The method of claim 8,
The carbon dioxide capture reactor maintains a temperature of 20 ° C. to 40 ° C. and a pressure condition of 0.5 atm to 1.5 atm, a carbon dioxide treatment system containing radioactive carbon.
9. The method of claim 8,
A carbon dioxide treatment system containing radioactive carbon, further comprising a centrifuge for separating carbonate converted in the carbon dioxide capture reactor.
supplying carbon dioxide containing radioactive carbon to a carbon dioxide capture reactor and liquefying it;
converting the supplied carbon dioxide into carbonate by reacting it with the silica-based scavenger according to any one of claims 1 to 7; and
A method for treating carbon dioxide containing radioactive carbon, comprising the step of separating the silica-based scavenger in which the carbonate is collected.

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