JP7575857B2 - Separation method, separation device, and production method - Google Patents

Description

The present invention relates to a separation method, a separation device, and a production method .

For example, Patent Document 1 discloses a tritium separation system that performs adsorption treatment of tritium by bringing tritium-containing water into contact with a tritium adsorbent containing hydrogen- or lithium-containing manganese oxide having a spinel crystal structure.

JP 2017-15543 A

Currently, there is a demand for a new method for separating heavy hydrogen (an isotope of light hydrogen) such as tritium, other than that described in Patent Document 1. There is also a demand for a method for producing water containing deuterium.

The present invention aims to provide a new method and apparatus for separating deuterium, and a new method and apparatus for producing water containing deuterium.

(1) In order to achieve the above object, a separation method and a separation apparatus according to a first aspect of the present invention comprise:
By exposing graphite to a gas mixture containing hydrogen and deuterium, the deuterium is bonded to the graphite, and the deuterium is separated from the gas mixture.

(2) In order to achieve the above object, a separation method and a separation apparatus according to a second aspect of the present invention are as follows:
By exposing graphite bonded to hydrogen to a mixed gas containing hydrogen and deuterium, the hydrogen bonded to the graphite is replaced with the deuterium contained in the mixed gas, and the deuterium is separated from the mixed gas.

(3) In order to achieve the above object, a generating method and a generating device according to a third aspect of the present invention include:
exposing the graphite to a gas mixture containing hydrogen and deuterium to bond the deuterium to the graphite, and separating the deuterium from the gas mixture;
The deuterium bound to the graphite is reacted with oxygen to produce water containing the deuterium.

(4) In order to achieve the above object, a generating method and a generating device according to a fourth aspect of the present invention include:
exposing the graphite bonded to hydrogen to a mixed gas containing hydrogen and deuterium, thereby replacing the hydrogen bonded to the graphite with the deuterium contained in the mixed gas, and separating the deuterium from the mixed gas;
The substituted deuterium is reacted with oxygen to produce water containing the deuterium.

(5) An example of the deuterium is ditium or tritium. An example of graphite is graphene. An example of graphene includes coronene (C ₂₄ H ₁₂ ). An example of graphite bound to protium is graphane (graphene bound to protium). An example of graphane includes tetracosahydrocoronene (C ₂₄ H ₃₆ ). Graphene, graphane, graphite, etc. may be macroscopic or nanosized.

According to the present invention, a new separation method, separation device, production method, or production device can be provided.

FIG. 1 illustrates an example of a separation system according to an embodiment of the present invention.

As shown in FIG. 1 , a separation system 1 according to an embodiment of the present invention includes an electrolysis section 11, a reaction processing section 12, and a graphane processing section 13.

The electrolysis unit 11 is supplied with treated water to be treated. The treated water is water containing tritium (T), specifically, a mixture of water molecules (H ₂ O) and tritium water molecules (T ₂ O, THO). The electrolysis unit 11 electrolyzes the treated water. Tritium has the same properties as hydrogen (H). Therefore, the electrolysis method can be the same as the various methods for decomposing water (H ₂ O) into hydrogen and oxygen. By such electrolysis, the treated water is decomposed into a mixed gas consisting of hydrogen and tritium, and oxygen. The electrolyzed mixed gas is supplied to the reaction processing unit 12 via a pipe or the like.

The reaction processing unit 12 exposes graphene (carbon arranged two-dimensionally) to the mixed gas electrolyzed in the electrolysis unit 11, thereby reacting the graphene with the mixed gas. Tritium is more likely to bond with graphene (carbon) than hydrogen. This is because the zero-point vibrational energy of each atom is different. Therefore, in this reaction, tritium atoms can be preferentially bonded with graphene. This bond allows tritium to be separated from the mixed gas preferentially over hydrogen.

The conditions for exposing graphene to the mixed gas may be the same as those for bonding graphene and hydrogen to generate graphane ( _{CmHn )} . As described above, tritium is an isotope of hydrogen and has similar properties to hydrogen, so that such conditions are expected to bond graphene and tritium. As an example, the mixed gas is converted into a plasma state together with argon under low pressure, and graphene is exposed to the mixed gas in the plasma state (graphene is exposed to hydrogen/tritium-argon mixed plasma under low pressure).

In the reaction between graphene and a mixed gas, one hydrogen atom (including hydrogen isotopes such as tritium atoms) is bonded to one carbon atom of graphene, so the amount of tritium separated from the mixed gas can be controlled by the area of graphene reacted with the mixed gas. For example, if the area of graphene is large compared to the amount of tritium in the mixed gas, all of the tritium can be separated from the mixed gas. At this time, light hydrogen may be bonded to the graphene. On the other hand, if the area of graphene is small compared to the amount of tritium in the mixed gas, all of the tritium cannot be separated from the mixed gas, but the amount of tritium in the mixed gas can be reduced and only tritium out of light hydrogen and tritium can be bonded to the graphene. In this case, by using multiple sheets of graphene, much (or all) of the tritium can be separated from the mixed gas. Here, graphene bonded to at least tritium out of light hydrogen and tritium is also called graphane.

In graphane, in which hydrogen and tritium are bonded to carbon, hydrogen is replaced with tritium (to be stable as a substance). Therefore, when it is considered that graphene and hydrogen are bonded (when the area of graphene is large, for example), the above-mentioned replacement may be caused by exposing the graphane containing hydrogen to a new mixed gas (a gas containing tritium). The following conditions may be considered as conditions for exposing the graphane containing hydrogen to a new mixed gas (theoretically, the replacement occurs even if the two are only brought into contact with each other). For example, as in the above, the new mixed gas is made into a hydrogen/tritium-argon mixed plasma state under low pressure. For example, a voltage is applied to the graphane, the mixed gas is stirred, or the graphane or the mixed gas is heated (any combination of these may be used). By replacing hydrogen in the graphane with tritium, the proportion of tritium contained in the graphane can be increased, and tritium can be captured efficiently.

The amount of tritium contained in the graphane can be determined by analyzing the vibration spectrum of the graphane. Therefore, a measuring device that measures the vibration spectrum and a control unit (computer, etc.) that determines whether the vibration spectrum measured by the measuring device satisfies a predetermined condition prepared in advance may be provided. In this case, when it can be determined that the predetermined condition is satisfied, the control unit determines that the ratio of tritium in the graphane (the ratio to protium + tritium) has become sufficiently large, and instructs the graphane to be removed, etc.

The graphane processing unit 13 exposes the graphane generated in the reaction processing unit 12 to oxygen to dehydrogenate it (including removing hydrogen isotopes such as tritium). The oxygen (oxygen gas) used in the dehydrogenation can be oxygen decomposed in the electrolysis unit 11. The following conditions can be considered when exposing the graphane to oxygen (theoretically, the reaction occurs just by contacting the two). For example, oxygen is made into a plasma gas, a voltage is applied to the graphane, oxygen gas is stirred, or the oxygen gas or graphane is heated (any combination of these may be used). The graphane can be returned to graphene by the dehydrogenation, and the returned graphene can be used again in the reaction processing unit 12. Tritium water is also generated by the dehydrogenation. The graphane processing unit 13 may perform dehydrogenation by heating the graphane in an argon atmosphere or the like without using oxygen.

According to the above configuration, it is possible to efficiently separate tritium from treated water or mixed gas. For example, tritium can be efficiently separated from contaminated water (T ₂ O, THO) containing tritium produced by nuclear fission. In addition, graphene can be reused. Furthermore, tritium water in which tritium is more concentrated than in treated water can be obtained. In particular, when only tritium can be bound to graphene, 100% tritium water can be obtained.

This invention is not limited to the above-mentioned embodiment, and the above-mentioned embodiment may be modified. Modifications of the above-mentioned embodiment are exemplified below, but at least a part of each modification can be combined as long as no contradiction occurs. Note that any configuration of the above-mentioned embodiment or the following modification can be omitted regardless of whether it is related to the above-mentioned "problem to be solved by the invention" or the like (in that case, it may become a different invention).

The reaction processing unit 12 may use graphane instead of graphene, and expose the graphane to the mixed gas to cause replacement of tritium in the mixed gas with hydrogen in the graphane, and separate the tritium from the mixed gas. Conditions for exposing the graphane to the mixed gas may be, for example, similar to the replacement described above. For example, as described above, the new mixed gas is made into a hydrogen/tritium-argon mixed plasma state under low pressure. For example, a voltage is applied to the graphane, the mixed gas is stirred, or the graphane or the mixed gas is heated (any combination of these may be used). In such a case, the graphane processing unit 13 dehydrogenates the graphane after replacement in the same manner as described above, and bonds hydrogen to the graphane (graphene) after dehydrogenation (a normal graphane manufacturing method can be adopted).

Tritium may be replaced with ditium (D). In this case, the treated water and the mixed gas contain ditium. The priority order of bonding with graphene (carbon) is ditium, followed by protium, in order of decreasing priority. Protium in graphene is replaced with ditium. Therefore, when the treated water contains ditium, ditium can be easily separated, and ditium (D ₂ O) can be obtained by the graphene processing unit 13. Similarly, tritium may be replaced with tetratium, etc. Since ditium, tetratium, etc. are isotopes of hydrogen like tritium, the above description of tritium can also be applied to ditium, tetratium, etc.

Natural water contains a certain amount of dideuterium. Therefore, for example, high purity dideuterium (water composed only of water molecules consisting of dideuterium and oxygen) can be obtained by the following method. For example, graphene (or graphane) is exposed to a mixed gas (gas containing dideuterium) obtained by electrolyzing natural water, and dideuterium and protium (the amount of dideuterium that is lacking) are bonded to the graphene (in the case of graphane, substitution with dideuterium occurs). Graphane (graphene bonded with dideuterium and protium) obtained by this bonding (or substitution) is exposed to another mixed gas (gas containing dideuterium obtained by electrolyzing other water in nature), and protium is replaced with dideuterium of the other mixed gas. By repeating such substitution (sequentially exposing graphane to other mixed gases), the proportion of protium in graphane can be reduced and the proportion of dideuterium can be increased instead. Therefore, if the number of times of repeating the substitution is set to a predetermined number or more, for example, graphane bonded only with dihydrogen can be obtained, and by reacting this graphane with oxygen, dihydrogen water (D ₂ O) with high purity can be obtained. The amount of deuterium bonded may be determined by the vibration spectrum as described above. Also, by making graphene (or graphane) small and exposing it to a mixed gas, all atoms bonded to the graphene are converted to dihydrogen, and by reacting a plurality of graphanes (CmDn) thus obtained with oxygen, dihydrogen water with high purity can be obtained.

The treated water and mixed gas may contain tritium and ditium. The priority order of bonding with graphene (carbon) is tritium, ditium, and protium, in descending order of priority (the more neutrons there are, the heavier the protium is, and the higher the reaction priority is). Protium in graphene is replaced by ditium or tritium. Ditium is replaced by tritium. For these reasons, tritium can be preferentially separated by using graphene or graphene.

The above-mentioned bonding between heavy hydrogen (dihydrogen, tritium, etc. are collectively referred to as heavy hydrogen) and carbon, and the substitution with heavy hydrogen are considered to be applicable to carbon in general, and the idea of the above-mentioned embodiment is considered to be extendable not only to graphene, but also to graphite in general (for example, graphene stacked in two or three layers). As described above, by utilizing the difference in the priority (energy) of bonds with carbon for hydrogen isotopes (including hydrogen and deuterium) (the above-mentioned substitution also arises from this difference), separation of hydrogen isotopes can be easily realized without special processing (under the same conditions as bonding hydrogen and carbon).

The method for decomposing the treated water into a mixed gas of protium and deuterium and oxygen may be a method other than electrolysis.

The mixed gas to be treated may contain protium and deuterium, and the mixed gas may be obtained by any method.

When hydrogen (which may be protium or deuterium) contained in graphane reacts (combines) with oxygen to generate water (which may be normal water or heavy water), heat is generated. Therefore, the following heat generating device is also conceivable. A heat generating device that reacts (combines) hydrogen (which may be protium or deuterium) contained in graphane with oxygen to generate heat. In such a heat generating device, the graphane after the reaction becomes graphene, and the graphane can be reused by combining hydrogen with the graphene.

The graphane reaction section 13 may be omitted. The graphane containing deuterium may be discarded or processed as it is.

Exposing graphane or graphene to a gas (mixed gas or oxygen) includes supplying graphane or graphene to a mixed gas or oxygen atmosphere, and flowing the mixed gas or oxygen gas into a space in which graphane or graphene is arranged.

1 ... separation system, 11 ... electrolysis section, 12 ... reaction processing section, 13 ... graphane reaction section

Claims (5)

a separation step of exposing graphene to a mixed gas containing protium molecules formed by bonding protium atoms together and deuterium molecules formed by bonding deuterium atoms together or deuterium atoms and protium atoms together to bond the deuterium atoms to the graphene, and separating the deuterium atoms from the mixed gas.
Isolation method. The graphene exposed to the mixed gas is bonded to hydrogen atoms to form graphane,
In the separation step, the protium atoms bonded to the graphene are replaced with the deuterium atoms contained in the mixed gas, thereby bonding the deuterium atoms to the graphene, and separating the deuterium atoms from the mixed gas.
The method of claim 1. The method further includes a decomposition step of decomposing the water containing deuterium atoms into the mixed gas and oxygen,
In the separation step, the graphene is exposed to the mixed gas decomposed in the decomposition step.
The method for separation according to claim 1 or 2. A method for separating a sample according to any one of claims 1 to 3,
a generating step of reacting the deuterium atoms bonded to the graphene in the separating step with oxygen to generate water containing the deuterium atoms;
A method for generating the same. a separation unit that exposes graphene to a mixed gas containing protium molecules formed by bonding protium atoms together and deuterium molecules formed by bonding deuterium atoms together or deuterium atoms and protium atoms together to bond the deuterium atoms to the graphene, and separates the deuterium atoms from the mixed gas.
Separation device.

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