KR100680582B1 - Removal process of iodine mixture using a pyrite - Google Patents

Abstract

 The present invention relates to a method for removing them from an aqueous solution or wastewater containing at least one selected from iodine and iodic ions, and more particularly, reacting iodine or iodide ions or both present in the aqueous solution or wastewater with pyrite. The iodine mixture (iodine, iodide ion and iodine ion) is simultaneously removed by converting the iodine ion and the original iodine ion into a strong basic anion exchange resin by changing the iodine ion to the iodine ion as shown in Scheme 1 below. The present invention as described above has the advantage that the processing speed is relatively fast and the process is simple and continuous operation is possible.

 Scheme 1

FeS ₂ FeS ₂

^{_{2IO 3 - ---- → I 2 ----}} → 2I -

Iodine, Iodide ion, Iodine ion, pyrite, pyrite, organic strong basic anion exchange resin

Description

Removal process of iodine mixture using a pyrite

1 is a schematic diagram showing a process for removing them from an aqueous solution or wastewater containing at least one selected from iodine and iodide ions according to the method of the present invention.

<Explanation of symbols for the main parts of the drawings>

1 --- pyrite filling tower 2 --- ion exchange resin filling tower

The present invention relates to a method for removing an iodine mixture in water using pyrite (Pyrite, FeS ₂ ), and more particularly, from the aqueous solution or wastewater containing any one or more selected from iodine or iodic ions to the iodine ion by pyrite The present invention relates to a method of reducing and finally removing iodine ions using organic strong basic organic ion exchange.

Iodine is usually present in the form of iodine (I ₂ ), iodide ions (IO ₃ ⁻ ) and iodine ions (I ⁻ ). These various forms of chemistry make it difficult to remove iodine mixtures from aqueous solutions or waste waters, especially from radioactive wastewater from nuclear power plants, reprocessing plants operating in advanced foreign countries, and other radioisotopes. Removing iodine is a big problem.

Various iodine compounds in radioactive wastewater exist as isotopic compounds of various iodine elements with mass 127, 129, 131, 132, 133, etc. These have the same chemical behavior, but iodine elements with mass 129, 131, 132, 133 are radioactive. Isotopes are radioactive. Here, the radioactive iodine elements (iodine-132, 133) having masses 132 and 133 have relatively short half-lives of 2.3 hours and 20.8 hours, respectively, so that radioactivity can be completely attenuated by standing for a certain period of time. The half-life of iodine-131 is 8.02 days, although the half-life is not long. However, if the initial radiation concentration is high, it may need to be left for several months in order to lower the concentration of radiation to the emission allowance. In addition, iodine-129 has a half-life of 1.57 × 10 ⁷ years, which is almost impossible to attenuate if left alone, and if it is ingested in humans, it is concentrated in specific organs and continues to emit radiation, causing great detoxification.

Therefore, various methods for removing radioactive iodine have been devised as described above. The most commonly used iodine removal method is an organic strong base anion exchange resin. Usually, since iodine, iodic ions and iodine ions are called iodine without distinguishing them, the iodine removal method here means strictly the removal method of the iodine mixture. An organic strong basic anion exchange resin is a method in which an aqueous solution or wastewater containing an iodine mixture is left for a long time or warmed, so that most of the poorly soluble iodine is blown off by a gas, and the remaining iodine ions or iodine ions are converted into organic anion exchange resins. How to remove. However, in this method, iodine ions are not removed by anion exchange resin as well as iodine ions, and since iodine may exist in some aqueous solution or waste water, it is not completely removed by organic anion exchange resin. As a result, there is a problem that the removal efficiency for the entire iodine mixture, that is, iodine + iodide ion + iodine ion, is reduced.

On the other hand, a method of removing an iodine mixture using activated carbon is known. Since the activated carbon exhibits little removal performance on ionic materials such as iodine ions and iodide ions, there is little effect except removal of iodine in an aqueous solution or waste water. It is rarely used, and there is only a possibility of use as an auxiliary means of organic anion exchange resin treatment method.

In addition, Korean Patent Application No. 1986-0001581, entitled "Method for Removing Iodide Compounds from Non-Aqueous Organic Media," is a strong acid cation exchange resin having a macroreticular structure that is stable in an organic medium. A method for removing an iodide compound from a non-aqueous organic medium consisting of contacting an ion exchange resin characterized in that% active moiety is converted to silver or mercury form.

Moreover, the invention with regard to the recently proposed removal of the iodine mixture is for example U.S. Patent 5,352,367. In the present invention, a reducing agent such as sodium sulfite (Na ₂ SO ₃ ) is injected into radioactive wastewater containing iodine ions to reduce iodine ions to iodine ions, and then silver nitrate is added to iodide ions. A method of removing iodine ions and iodide ions by precipitation with silver (Agl) is disclosed. However, the method is very difficult to continuous process, takes a lot of time to settle, as well as measures to ensure the removal of the sediment, if the removal of the sediment reliably removes the overall iodine removal efficiency, in particular the method It is disadvantageous because it is not economical because expensive silver compounds are used.

In addition, as one of the inventors recently developed a technology for removing the iodine mixture, Korean Patent No. 0266982 discloses iodine ions or iodine ions present in an aqueous solution or waste water, or both, to iodine by the reaction of Scheme 2 below. A method of simultaneously removing iodine, iodic ions and iodine ions by adsorbing activated iodine and then existing iodine using activated carbon is disclosed.

Scheme 2

_{^{5I - + IO 3 - + 6H}} + → 3I 2 + 3H 2 O

However, although the removal effect on the iodine mixture having a relatively constant method composition is excellent, it is inconvenient to adjust the reaction according to the composition change when the composition changes.

The present inventors have been trying to find a way to remove the iodine mixture more easily, the organic strong basic anion that was mainly used to remove iodine ions or iodine ions to iodine ions using pyrite The present invention was completed by finding that the iodine mixture can be removed simply and quickly using an exchange resin.

It is an object of the present invention to provide a method for more easily removing the iodine and iodide ions from an aqueous solution or wastewater containing at least one selected from iodine and iodic ions.

In order to achieve the above object, the present invention reacts iodine or iodide ions present in an aqueous solution or waste water with pyrite to change to iodine ions, as shown in Scheme 1 below, thereby producing iodine ions and original iodine ions. Provided is a method of simultaneously removing iodine mixtures (iodine, iodide ions and iodine ions) by ion exchange using a strong basic anion exchange resin.

     Scheme 1

FeS ₂ FeS ₂

^{_{2IO 3 - ---- → I 2 ----}} → 2I -

According to another configuration of the present invention, the reaction of the aqueous solution or wastewater and pyrite containing the iodine or iodide ions or both is reacted by passing the aqueous solution or wastewater through a column filled with pyrite at a constant flow rate.

According to the present invention, the flow rate of the column through the aqueous solution or the wastewater can be adjusted to the time that the aqueous solution or the wastewater can sufficiently react with pyrite, preferably the reaction time is adjusted to 10 minutes to 20 minutes. If the flow rate is made too fast and the reaction time is less than 10 minutes, there is a disadvantage that the reaction is not fully converted to iodine ions due to insufficient reaction, and if it is 20 minutes or more, there is a disadvantage in that the treatment speed is lowered.

As described above, the iodine and iodide ions contained in the aqueous solution or the waste water are reduced to iodine ions by pyrite, and finally the iodine ions can be easily removed using an organic strong basic organic ion exchange resin. Will be.

Hereinafter, the present invention will be described in more detail.

Pyrite is a relatively widely distributed mineral on Earth and its main component is FeS ₂ . Until now, experiments have been conducted to adsorb and remove iodine ions using pyrite, but the effect is known to be insignificant. In addition, M. Fuhrman et al. (Applied Geochemistry, Vol. 13. pp127-141, 1998) reported that iodine ions react with pyrite to produce iodine, and some of the iodine adsorbed on the pyrite surface. . However, in the present invention, it was confirmed for the first time that both iodine ions and iodine react with pyrite, and both materials finally change to iodine ions.

Particularly, pyrite can be adjusted to a particle size by pulverization, so that the granules are 0.2 to 0.8 mm in size and filled into the column container, and continuously passed through an aqueous solution or wastewater containing at least one selected from iodine and iodide ions. A process for converting iodine and iodide ions into iodine ions is possible.

As described above, after changing the iodine and iodine ions in aqueous solution or wastewater by pyrite into iodine ions in accordance with the present invention, the iodine mixture ( Removal efficiency and process efficiency of iodine, iodide ion and iodine ion) can be greatly improved compared to the existing methods. An example of the treatment process of the iodine mixture according to the present invention is shown in FIG. 1 .

As shown in FIG . 1 , an aqueous solution or wastewater containing iodine mixtures (iodine, iodine ions and iodine ions) is passed through a pyrite packed column 1 filled with a quantity of pyrite to convert the contained iodine mixture into iodine ions. The iodine mixture is completely removed from the discharged water discharged through the packed tower 2 by adsorbing iodine ions through the packed tower 2 filled with the organic strong basic anion exchange resin.

Hereinafter, the present invention will be described in detail with reference to the following examples. The following examples are merely illustrative of the present invention, of course, the present invention is not limited by the examples.

<Example 1>

2 g of pyrite powder was added to a 1,000 mL aqueous solution containing 10 mg / L of iodine ions and stirred with a stirrer. After about 6 hours, about 99% of the iodine ions were converted to iodine ions. Ion chromatography and iodine ion It could be confirmed using the selection electrode.

<Example 2>

Except that the reaction time was 4 hours as in Example 1, the measurement of iodine ions was confirmed that only about 75% conversion to iodine ions.

<Example 3>

2 g of pyrite powder was added to a 1,000 mL aqueous solution containing 10 mg / L of iodine and stirred with a stirrer. After about 1 hour, it was confirmed by using an iodine ion selective electrode that about 99% of iodine was changed to iodine ions.

<Example 4>

Except that the reaction time was 30 minutes, the iodine ion was measured in the same manner as in Example 3, and it was confirmed that only about 65% of the iodine ion was converted.

Example 5

2 g of pyrite powder was added to a 1,000 mL aqueous solution containing 5 mg / L of iodine ions and iodine, and stirred with a stirrer. After about 6 hours, about 99% of iodine ions and iodine were changed to iodine ions. It could be confirmed using an ion selective electrode.

<Example 6>

Except that the reaction time was 4 hours, the iodine ions were measured in the same manner as in Example 5, and it was confirmed that about 85% of the iodine ions were converted.

<Example 7>

Fill a glass column with 20 mL of pyrite with an average particle diameter of 0.3 mm, then pass a 1,000 mL aqueous solution containing 10 mg / L of iodide ion at a flow rate of 1.5 mL / min (reaction time 15 minutes) and As a result of measuring the concentrations of iodine ions and iodine ions, it was confirmed that more than 99% of the iodine ions were changed to iodine ions.

<Example 8>

The concentration of iodine ions and iodine ions was measured in the same manner as in Example 7, except that the flow rate was 4 mL / min (reaction time 5 minutes). As a result, 80% of the iodine ions were changed to iodine ions.

Example 9

The concentration of iodine ions and iodine ions was measured in the same manner as in Example 7, except that the flow rate was 2 mL / min (reaction time 10 minutes). As a result, 90% of the iodine ions were changed to iodine ions.

<Example 10>

The concentration of iodine ions and iodine ions was measured in the same manner as in Example 4 except that the flow rate was 1 mL / min (reaction time 20 minutes). As a result, 99% of the iodine ions were changed to iodine ions.

<Example 11>

The same procedure as in Example 7 was carried out except that a 1,000 mL aqueous solution containing 5 mg / L of iodine ion and 5 mg / L of iodine ion was passed through. As a result, the same results as in Example 7 were obtained.

<Example 12>

An aqueous solution of iodine ions obtained by passing pyrite in Example 7 was passed through a glass column filled with Amberlite IRN 78, a strongly basic organic ion exchange resin from Rohm & Haas, to ion exchange iodine ions with -OH groups of the organic ion exchange resin. Iodine ions were completely removed from the aqueous solution.

The method for removing iodine in water using pyrite of the present invention constituted as described above is to remove iodine or iodide ions present in an aqueous solution or wastewater with pyrite to reduce the iodine ions and then completely remove them with an organic strong base anion exchange resin. This method has the advantage that the reaction speed is relatively fast and the process is simple and continuous operation is possible. In addition, the method of the present invention can remove all iodine mixtures regardless of the molar ratio of iodine ions and iodide ions present in the original aqueous solution or waste water, and handles iodine, including radioactive wastewater treatment generated in various nuclear industries. It can be usefully applied to industrial fields.

Claims (5)

In the method for removing the iodine and iodide ions from an aqueous solution or wastewater containing any one or more selected from iodine (I ₂ ) and iodide ions (IO ₃ ⁻ ), iodine or iodide ions or both is reacted with pyrite the aqueous solution or waste water to an iodine ion (I ^-) by ion exchange using an ion exchange resin, the iodine ion was the iodine ion and originally present generation was changed to the elimination of iodine, iodate ion, and iodine ion A method for removing an iodine mixture in water using pyrite. The method of claim 1, wherein the reaction of the aqueous solution or wastewater containing pyrite and iodine or iodic ions or both and pyrite reacts by passing the aqueous solution or wastewater through a column filled with pyrite at a constant flow rate. Method of removing the used iodine mixture in water. The method of claim 1, wherein the ion exchange resin is an organic strong basic anion ion exchange resin. 3. The method of claim 2, wherein the flow rate of the column through the aqueous solution or the wastewater is controlled to allow the reaction of the aqueous solution or the wastewater and pyrite to be 10 minutes to 20 minutes. 5. The method of claim 4, wherein the flow rate of the column through the aqueous solution or the wastewater is controlled such that the reaction of the aqueous solution or the wastewater with pyrite is 15 minutes.

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