JPS6012121A - Removal of arsenic component in gaseous phase - Google Patents

Abstract

PURPOSE:To effectively perform the removal or recovery of the arsenic component in a gaseous phase generated in various industries, by bringing gas containing arsenic or an arsenic compound into contact with a solution layer containing an oxidizing agent while introducing the same into said solution layer. CONSTITUTION:Manganese peroxide or bichromate is used as an oxidizing agent to be dissolved in water or a solvent in a concn. of about 3.0% or more while the resulting solution is supported by iron, silicon or activated carbon to form an oxidizing layer and aresenic or an arsenic compound is brought into contact with the oxidizing layer while introduced into said layer. In this case, the holding amount of the oxidizing agent solution to the carrier is set to about 0.01- 0.5cm<3> per 1cm<3> of the layer. By this method, the arsenic component in a gaseous phase is effectively removed. Further, the carrier used in the removal of arsenic can be regenerated through the contact with water or an alkali solution and, in this case, the arsenic component can be recovered as a concn. liquid.

Description

[Detailed description of the invention] The present invention relates to a method for removing arsenic components in a gas phase.

Conventional methods for treating mixed gases containing arsenic include passing the mixed gas into a solution of copper sulfate to precipitate the arsenic as copper arsenide, or passing the mixed gas through a quartz tube heated to high temperatures, then cooling it to form metallic arsenic. A method of solidifying the arsenic, a method of introducing a mixed gas onto heated copper, iron, nickel, or cobalt, causing the arsenic to react with the metal, and diffusing the reaction product into the metal are known. However, all of these methods are incomplete as methods for removing arsenic, and in order to sufficiently reduce the arsenic concentration in the processing gas, complicated and large equipment is required. The reaction is carried out under extremely high heat, and the process is dangerous and consumes a large amount of energy. Furthermore, since it is difficult to re-separate arsenic from the reaction product with arsenic, the reaction product must be removed from the treatment system and disposed of, making it impossible to reuse it.

In view of the above-mentioned current situation, the Ministry of Invention and others has already filed a patent application
No. 3876 and lIf! fG in Application No. 58-27014
Although we have not yet proposed a method for removing arsenic components in the gas phase that is characterized by the combination of titanic acid particles and an oxidizing agent solution, we believe that further studies will show that this method can be applied to the oxidizing agent solution alone or other methods. The present invention was achieved based on the discovery that the present invention is applicable to a system in which an oxidizing agent solution is contained in the carrier and a system in which an oxidizing agent solution is used alone.

That is, the present invention relates to a method for removing arsenic components in a gas phase, which is characterized by introducing a gas containing arsenic or an arsenic compound into an oxidizing agent solution layer and bringing it into contact with the oxidizing agent solution layer.

In the present invention, any known substance can be used as the oxidizing agent, such as permanganic acid and its salts, dichromic acid and its salts, sulfuric acid and peroxide. Water is usually used as the solvent for the oxidizing agent solution, but it is also possible to use an organic solvent that does not react with the oxidizing agent.

If the oxidizing agent concentration in the oxidizing agent solution is 0.1% or more, it is effective for removing arsenic components in the gas phase.

It is preferable that it is 3.0 inches or more in order to improve removal ability.

The contact time of the gas with the oxidizing agent solution is 5 seconds or more, and if the contact efficiency is low, the contact time needs to be longer.

In the present invention, the oxidizing agent solution layer may be a layer consisting only of the oxidizing agent solution, but from the viewpoint of contact efficiency, it is preferable to use a layer formed by holding the oxidizing agent solution on a carrier (hereinafter referred to as a packed layer). In the case of a preferred filling layer9, for example, if the optical filling layer length is 10 cm and the ventilation rate is 7 minutes at 10-100, the contact time will be 6 seconds to 1 minute.

In the present invention, it is more preferable that the carrier forming the packed bed has the ability to adsorb arsenic compounds by itself, but it is not necessarily limited to having the ability to adsorb the arsenic compound. Rather, catalytic aluminum, titanium, zirconium, which helps oxidize arsenic components,
The packed bed can be formed in the form of a substance whose main component is an oxide or hydrated oxide of lead, calcium, magnesium, etc., activated carbon, anion/exchange resin, flake, sheet, etc. Particularly from the viewpoint of operability, granular materials are desirable, and granular materials such as porous pumice and porous glass are preferred.

be.

The amount of oxidant solution retained on the carrier is 1crIL8/9
0.01 to 0.5 cm". If the removal effect is less than 0.01 an", the removal effect is poor, and if it is more than eO,5 an", the ventilation resistance increases. As a method for retaining the additive solution, the entire packed bed is immersed in the oxidizing agent solution. Any method can be used, such as a temporary immersion method or a method of spraying an oxidizing agent solution onto the packed bed.Also, as the arsenic component is removed by the packed bed, the oxidizing agent is consumed. Otherwise, the oxidant solution evaporates, so that in the case of long-term use, it is necessary to replenish it continuously or intermittently by suitable methods.

In the present invention, the oxidizing agent solution layer is a method for removing arsenic components using only an oxidizing agent solution.

The arsenic component is absorbed into the solution and removed, which is effective in removing the arsenic component, but in this case, it is necessary to take measures to increase the efficiency of contact with the gas component.

Generally speaking, the removal efficiency tends to be lower than when using a packed bed.

In the present invention, the main arsenic component in the gas phase to be removed can be simple arsenic or oxidizable substances such as hydrogen arsenide, but in addition to these substances, arsenic oxide etc. may coexist. It can also be applied to systems with

The packed bed used for arsenic removal in the present invention can be regenerated by contacting it with water, an alkaline solution, etc., and in this case, the arsenic component is recovered as a concentrated liquid.

The present invention is effective for removing or recovering arsenic components in the gas phase generated in various industries including manufacturing processes of semiconductors, photosensitive agents, catalysts, etc.

This will be explained below using examples.

Example 1-4 Various granular compositions shown in Table 1-62, OJ'.

(Potassium permanganate 5.0/10 concentrated nitric acid 3.0+
After soaking in an oxidizing agent solution consisting of 100 mJ of water for 24 hours, it was taken out and filled into a gFf conduit into an apparatus (Fig. 1) according to the arsenic analysis method shown in JIS-KOIOI-1979. I suppressed it.

The glass wool on the gas introduction side was previously impregnated with lead acetate. In the Erlenmeyer flask (for 100-),
Arsenic acid solution 40ml 1. Hydrochloric acid, potassium iodide, tin chloride (I
I) and zinc were added to generate hydrogen arsenide (AsHl). The generated tr gas containing hydrogen arsenide passed through the packed bed and was then introduced into the absorption liquid of silver diethyldithiocarbamate.

Since hydrogen arsenide that was not removed in the packed bed was absorbed by the absorption liquid, the amount of arsenic absorbed was determined by measuring the absorbance of the absorption liquid, and the amount of arsenic removed was calculated from this. The amount of hydrogen arsenide generated was set at 0.19 arsenic per batch, and this process was repeated. For each composition, we calculated the amount of arsenic removed until the temperature-absorbing liquid slightly changed color, and the values shown in the right column of Table 1 were obtained. I understand.

Comparative Examples 1 to 4 The compositions used in Examples 1 to 4 were filled into a conduit in the same manner as in Example 1 without retaining the oxidizing agent solution, and the amount of hydrogen arsenide removed was calculated, and the results are shown in Table 2. As shown, results were obtained in which almost no arsenic component was removed.

Table 1 Table 2 Example 5 As shown in Figure 2 (potassium permanganate 2.51
A gas injection tube with a porous glass tube tip was placed in a test tube (for 100 m) containing an oxidizing agent solution consisting of 1.5 g of Tono nitric acid + 50 g of water.

A hydrogen arsenide-containing gas generated under the same conditions as in Example 1 was passed through the oxidant solution and then introduced into the silver diethyldithiocarbamate absorption solution.

As for the amount of hydrogen arsenide generated, each batch was made to contain 0.1 square meters of arsenic, and when this process was repeated five times, the amount of arsenic removed for each batch showed the values shown in Table 3. Although the removal rate for each batch is inferior compared to Examples 1 to 4, the removal rate is about 90%,
It can be seen that it is effective in removing arsenic.

Comparative Example 5 Put 50 g of water in place of the oxidizing agent solution in a test tube, and
When one batch was tested under the same conditions as in Example 5, the arsenic component was not removed at all.

Table 3

[Brief explanation of the drawing]

FIGS. 1 and 2 show an example of a method for removing arsenic components in a gas phase using pressure to carry out the method of the present invention. l Hydrogen arsenide generating liquid 2 Glass school 3 Oxidizing agent solution impregnated granules 4 Glass conduit 5 Hydrogen arsenide absorbing liquid 7 Gas injection pipe 8 Oxidizing agent solution

Claims (1)

[Claims] 1. A method for removing arsenic components in a gas phase, which is characterized by introducing a gas containing arsenic or an arsenic compound into an oxidizing agent solution layer and bringing the gas into contact with the oxidizing agent solution layer. The method for removing arsenic components in a gas phase according to claim 1, characterized in that the layer is held on a carrier.