JPS6046042B2 - Method for producing iodine from natural can water - Google Patents

Description

Detailed Description of the Invention The present invention uses a solution containing sodium hypochlorite to oxidize iodine ions in natural gun water to liberate iodine, and then collects iodine using an anion exchange resin or the like. The present invention relates to a method for producing iodine, which improves the efficiency of iodine collection by adding an appropriate amount of mineral acid during the operation.

Conventionally, the method for producing iodine from natural cancer water uses chlorine, chlorine water, and hypochlorite as oxidizing agents to liberate the iodine ions in natural cancer water as molecular iodine, and then uses activated carbon, ion exchange resin, etc. Attempts have been made to use methods such as adsorption methods and air expulsion methods.

Among these methods, natural gun water is made acidic with mineral acids;
In the method of oxidizing with chlorine gas, etc., the free iodine produced is relatively stable, and iodine can be efficiently adsorbed and collected using activated carbon or ion exchange resin without producing iodate ions, which are peroxides. However, the amount of mineral acid required to make natural gun water acidic is large, and the amount of alkaline agent required to neutralize the gun water after iodine extraction (hereinafter referred to as waste gun water) is also large. It has its drawbacks.

In addition, the method of adding chlorine gas without adjusting the pH of natural gun water is that the iodate ion in peroxide is
Occurs in 5% or more. It is difficult to collect these iodate ions, and most of the iodate ions are transferred directly to waste gun water, so the method of directly adding chlorine gas to natural gun water has the disadvantage of low collection efficiency. When adding chlorine gas to a portion of waste gun water to prepare chlorine water, which has weaker oxidizing power than chlorine, the generation rate of iodate ions is approximately 5%.
It is practically used in ion exchange resin method, air expulsion method, etc.

However, in the case of this method, when the effective chlorine concentration is increased, the generation rate of iodate ions increases, so the chlorine used is usually adjusted to 1 da/1-kan water or less.

Therefore, the amount of water required to adjust the chlorinated water is enormous, and although a portion of waste gun water is normally used, this amount of water is equal to the amount of natural cancer water containing iodine ions (hereinafter referred to as raw cancer water) that is to be collected and processed. It has the disadvantage of reducing the efficiency of collection operations.

In addition, as a result of adjustment using waste gun water, chlorine is consumed by ammonia ions, etc. contained in the waste gun water, and the amount of chlorine is approximately 1 to 3 times the theoretically required amount of iodine ions in the original gun water. ．． It has the disadvantage of requiring a large amount of chlorine. In addition, chlorine is a hazardous substance and requires 100% safety management.

In other words, there is always a danger involved. On the other hand, sodium hypochlorite solution has weaker oxidizing power than chlorine water, and the gas generated when it decomposes is oxygen, so it is highly safe, so commercially available sodium hypochlorite solution with 12% available chlorine can be used as is. Therefore, the amount added is approximately 0.03 of the amount of raw gun water.
%, and the efficiency of the iodine collection operation is 100%.
It has the advantage of being close. The present invention has put into practical use the advantages of a solution containing sodium hypochlorite, while eliminating the disadvantages of chlorinated water.

Another advantage of using a solution containing sodium hypochlorite is that the generation rate of iodate ions is less than 2%, making it possible to extract nearly 100% of the iodine ions in natural gun water. be.

The rate of generation of iodate ions does not depend on the effective chlorine concentration of sodium hypochlorite, but rather on the stirring and mixing conditions when added to natural gun water. However, when iodine is liberated using a solution containing sodium hypochlorite, the decomposition is faster than in the case of chlorine water, as shown in Table 1.

If the processing time of the iodine collection operation is shortened, the change over time will be small and not a problem, but there is an essential difference between the two in the iodine collection operation. JOVIl7, day nse Shrine Go Harm → Ren) t Mi no To Hiroh So 7P6) D
■'→In the case of sodium hypochlorite solution, on the other hand, the pH increases, albeit very slightly. Such a pH increase occurs not only when using a commercially available sodium hypochlorite solution with an effective chlorine concentration of 12%, but also when hypochlorite is generated by non-diaphragm electrolysis using seawater, waste gun water, salt water, etc. A similar phenomenon occurs when a solution containing sodium chloride or a solution containing sodium hypochlorite produced by combining the catholyte and anolyte produced by diaphragm electrolysis are used. This phenomenon is mainly caused by sodium hydroxide, a by-product of the oxidation reaction, which seems to interfere with the iodine extraction operation.

The iodine ions in natural gun water are oxidized with a solution containing sodium hypochlorite to liberate an appropriate amount of iodine (hereinafter referred to as reaction gun water). If you try to collect iodine by passing the liquid through a column filled with chlorine, the adsorption effect will be significantly lower than when using chlorinated water, and its practical value will decrease. That is, in the case of chlorinated water, the adsorption yield is usually obtained in the range of 90% to 95%, whereas in the case of sodium hypochlorite, the adsorption yield is 80% to 85%, which is about a 10% difference. Be looked at. The present inventor has discovered that this problem can be prevented by adding an appropriate amount of mineral acid to natural gun water, and that sodium hypochlorite can be practically used as an oxidizing agent.

The mineral acid may be added to the natural gun water before or after adding the solution containing sodium hypochlorite to the natural gun water, or it may be added at the same time.

The amount of mineral acid added is determined to neutralize the amount of alkali caused by the solution containing sodium hypochlorite used, and to reduce the P of gun water.
The amount necessary to reduce H by 0.1 or more is desirable. That is, (PH of raw gun water) - (PH of waste gun water)≧0.1.

Even if the pH of waste gun water is lowered by 1.0 or more than the pH of raw gun water, the iodine extraction efficiency will not increase proportionally even though the amount of mineral acid used will increase. The amount of addition is preferably in the range of 1.0≧(raw gun water PH)−(waste gun water PH)≧0.1.

However, as long as the pH of the waste gun water does not exceed the neutral range, this does not preclude adding the mineral acid in an amount exceeding the above range. An example of the PH change of each gun water when mineral acid is added is shown in Table 2. (Note) Waste gun water is gun water after iodine has been collected using Amperlite IRA-400.

The amount of 12% sodium hypochlorite solution added is 1
250 mt per d.

This mineral acid addition method can be applied to the case where commercially available sodium hypochlorite with an effective chlorine concentration of 12% is used, or to any liquid containing sodium hypochlorite. Example Natural gun water containing about 90 ppm of iodine ions was added to 17T1.
Anion exchange resin Amperlite IRA at a flow rate of /hour
-400 (trade name) Approximately 40e In order to pass the liquid through the adsorption tower, a commercially available sodium hypochlorite solution with an effective chlorine concentration of 12% was added to natural gun water at a flow rate of approximately 250 mt/hour. of iodine was liberated, and the solution was continuously passed for 24 hours.

The average iodine content in the waste gun water was 14.4 ppm. That is, the average adsorption yield between the two fences was 84.0%. Next, 70% sulfuric acid was added at a rate of 90 ml/hour to the above-mentioned natural gun water 1 d/hour, and then the above-mentioned sodium hypochlorite solution was added at the same rate of 250 ml/hour, and the above-mentioned adsorption Subsequently, liquid was continuously passed through the tower between two mounds.

Claims (1)

[Claims] 1. In a method for producing iodine in which iodine in natural kan water is oxidized using a solution containing sodium hypochlorite to liberate iodine, and iodine is adsorbed by an ion exchange resin method, prior to performing the above ion exchange resin method. Mineral acid is added to natural citrus water, and the pH of the natural citrus water after iodine adsorption by an ion exchange resin is 0.1 to 1 from the pH of the original natural citrus water.
．． A method for producing iodine from natural kansui, characterized by reducing the amount to 0.