JPS6361057B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a collection agent that rapidly reacts with volatile ruthenium tetroxide to collect it and prevents ruthenium tetroxide from flowing out from handling equipment or facilities. It is something.

Compounds of ruthenium, a metal in the platinum group, have extremely unique properties, and many industrial applications are being actively developed to take advantage of these properties. One of its unique properties is that although ruthenium tetroxide is a heavy metal oxide, it has a low boiling point, evaporates even at room temperature, and is known to be toxic to the human body. Because ruthenium tetroxide has a low boiling point that is significantly different from that of many other metals, it is frequently used in industrial and analytical chemistry to separate other metals. In addition, ruthenium tetroxide is formed from many ruthenium compounds with various oxidizing agents, or even in the absence of oxidizing agents when heated in the air, making it an extremely common ruthenium compound. .

Nuclear fission of uranium and other substances produces large amounts of radioactive ruthenium, some of which have quite long half-lives and emit gamma rays and strong beta rays. As mentioned above, the chemical properties of ruthenium are both unique and complex, making it the biggest obstacle during nuclear fuel reprocessing and the treatment and disposal of radioactive waste. If radioactive ruthenium were accidentally released from these facilities, it is known to be dangerous and contaminate the environment and the human body.

Among these, radioactive ruthenium tetroxide is usually used in nuclear fuel reprocessing as a nitric acid solution, and high temperatures are often used to treat and dispose of waste.
It is generated at each stage, and if it leaks, it can cause gaseous contamination of the human body, so it is considered particularly dangerous and requires sufficient protection. In the past, it has been known that these countermeasures have not been sufficient, resulting in radioactive contamination of facilities and laboratories, as well as accidents involving contamination of humans.

Although ruthenium tetroxide is a metal oxide, it is more soluble in organic solvents such as carbon tetrachloride than in water and has strong covalent bonding properties, so the ionic bonding property is small and the covalent bonding properties are strong. It was discovered that it reacts well with rubber compounds and quickly and completely fixes it as a non-volatile compound, and based on this discovery, it was found that it can be used as a scavenger for rubbers.

It is already known that ruthenium tetroxide reacts with rubber to deposit a black substance, and it has been reported that it can be used to examine the microstructure of rubber using optical and electron microscopes. In this case, only a portion of the ruthenium tetroxide present in the air is used by reacting with it over time, and no attention is paid to what happens to most of the ruthenium tetroxide. Therefore, it is different from the content of the present invention.

An industrial method to collect the volatilized radioactive ruthenium tetroxide is to pass the vapor through a refractory brick containing iron oxide heated to about 600°C and cause the reaction RuO ₄ →RuO ₂ ↓＋O ₂ ↑ to occur. Collect. It is said that the reaction temperature can be lowered by using silica gel containing iron oxide or other silica gel as a scavenger.

In any case, these collection methods require heating the collection agent to a certain temperature range, which not only causes a loss of heat, but also requires a large-scale device, making it difficult to use for small-scale devices or experimental equipment. is difficult to use.

The present invention improves these points and uses rubber or its composition, which is a readily available product, to easily and completely collect ruthenium tetroxide at room temperature. Since the reaction is carried out at room temperature, the present invention can be similarly used for collecting and removing ruthenium tetroxide in an aqueous solution. Note that since all rubbers are solid, they are easy to handle.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A natural rubber product was cut into small pieces to form particles of 1 to 2 mm ³ , and the particles were collected by filling a rubber tube with an inner diameter of 8 mm with one end filled with a fine-mesh wire mesh, etc. to a height of 200 mm. Use it as a tube.

It is difficult to quantify ruthenium compounds, and there is no good analytical method for ruthenium compounds, especially those fixed in collection agents.
103) and quantified using its gamma rays.

The experimental equipment consists of an air filtration device followed by a glass reaction vessel, in which an oxidizing agent is used to generate ruthenium tetroxide. The reaction vessel can be heated to a constant temperature by means of a water bath. Next, the above collection tube is placed, a second collection device is connected to the rear of the collection tube, the rear of the second collection device is connected to a third collection tube, and the rear of the second collection device is connected to the third collection tube, and the rear part of the collection tube is connected to the third collection tube. It is connected to a device that draws air at a constant rate. A common glass joint is used for each connector up to the third collection tube, and the connections are airtight.

In the experiment, first a certain amount of radioactive ruthenium dissolved in dilute hydrochloric acid is placed in a reaction vessel, and an oxidizing agent and dilute sulfuric acid are added to generate radioactive ruthenium tetroxide. At the same time, the rear intake device is operated to send the generated ruthenium tetroxide together with air to the collection tube, where the radioactive ruthenium is reacted and collected.

After a certain period of time, the collection tube is removed and cut into several predetermined lengths, the cut ends are sealed with adhesive, etc., and used as samples for radioactivity measurement. This measurement sample is placed at a certain distance above a germanium semiconductor detector in which lithium is diffused and surrounded by lead bricks, and the radioactivity is measured using a pulse height analyzer. In this case, the radioactivity value of ruthenium-103, that is, the amount of collected ruthenium, can be determined from the magnitude of the 497 keV energy peak obtained in a fixed measurement time.

Figure 1 extrapolates this measurement result to the collection tube length of 0 cm, and calculates this value to 10 ⁵ counts/100 seconds.
It is standardized as cm and graphed. It is known that in such a reaction trapping device, if the temperature of the device is constant, the trapping efficiency is affected by the speed of the air passing through it. In this experiment, when the air velocity is 50 c.c./min (curve 1),
In the case of 100 c.c./min (curve 2), the latter collection curve becomes a little flat, but in both cases, 99% is obtained in a layer of 2 to 3 cm.
The above shows that more than 99.999% of ruthenium can be collected in a 10cm layer. Furthermore, almost no ruthenium radioactivity was detected from the second and third collection devices.

When natural rubber is used as a collecting agent in this way, ruthenium tetroxide can be efficiently collected at room temperature.

Example 2 A chloroprene rubber product was cut into particles similar to those in Example 1, packed in the same equipment, using the same amount of ruthenium-103, and using an air flow rate of 50 c.c./min.
The experiment was otherwise conducted under the same conditions as in Example 1. A good collection curve between curves 1 and 2 in FIG. 1 was obtained from the radioactivity measurements.

Example 3 A silicone rubber product was cut into pieces and an experiment was conducted under the same conditions as in Example 2. From the measured values of the radioactivity of the scavenger, a good scavenging curve almost identical to the curve 1 in FIG. 1 was obtained.

Example 4 A nitrile butadiene rubber product was cut into pieces and an experiment was conducted under the same conditions as in Example 2. From the measured values of the radioactivity of the scavenger, a good scavenging curve between curves 1 and 2 in FIG. 1 was obtained.

Example 5 Small volume boiling point measuring device (written by Seitaro Yamaguchi, Pharmaceutical Journal)
434, p. 252, 1918), the boiling point of ruthenium tetroxide (non-radioactive) was measured. As the heating progressed, the ozone odor characteristic of ruthenium tetroxide was felt, and as the heating progressed, the ozone odor peculiar to ruthenium tetroxide was present, and as the time passed, It will now turn nearby objects black.

In order to improve this unpleasant and unsanitary situation, we conducted an experiment by connecting a piece of natural rubber (commonly known as Ame-rubber) made of natural rubber with an inner diameter of 5 mm and a length of 300 mm to the opening of the device. Only the inside of the tank turned black; there was no ozone odor outside, and nearby appliances did not darken.

[Brief explanation of drawings]

Figure 1 shows the collection curve of radioactive ruthenium tetroxide using natural rubber particles, and the vertical axis is the collection tube length of 1 cm.
The counted value of radioactivity for 100 seconds is expressed on a logarithmic scale, and the horizontal axis is the distance from the leading end of the collecting agent expressed in cm on a diagonal scale. Curve 1 (black circle) in the figure is for an air flow rate of 50c.c./min.
Curve 2 (white circle) is the result when the flow rate was also 100 c.c./min.

Claims (1)

[Claims] 1. A ruthenium tetroxide collector made of rubber. 2 Claim 1 in which the rubber is natural rubber
Collection agent described in section. 3. The collecting agent according to claim 1, wherein the rubber comprises chloroprene rubber. 4. The collecting agent according to claim 1, wherein the rubber is made of silicone rubber. 5. The scavenger according to claim 1, wherein the rubber comprises nitrile butadiene rubber.