KR20100030250A - Removal method of iodine mixtures from aqueous solution - Google Patents

Abstract

PURPOSE: A method for eliminating an iodine mixture from an aqueous solution is provided to effectively remove the iodine without a separate oxidation or reduction reaction process for making the iodine mixture into a single ion state and to completely eliminate the iodine from radioactive waste liquid. CONSTITUTION: A method for eliminating an iodine mixture from an aqueous solution includes a step of adsorbing a mixture selected from iodide ion(I^-), iodate ion(IO3^-) and iodine using an adsorbate selected from activated alumina, the activated alumina in which Ag are dipped, and activated charcoal. The method comprises the following steps: a step of absorbing the iodate ion from acidic activated alumina and the acidic activated alumina in which Ag are dipped; step of absorbing the iodide ion selected from basic activated alumina and the basic activated alumina in which Ag are dipped; and a step of absorbing the iodine using the activated charcoal.

Description

Removal method of iodine mixtures from aqueous solution

The present invention provides a single iodine mixture containing one or more species selected from iodine ions (I ⁻ ), iodate ions (IO ₃ ⁻ ), and iodine (iodine, I ₂ ) present in an aqueous solution. The present invention relates to a method for completely adsorption and removal using activated aluminum oxide and activated carbon without a separate oxidation or reduction reaction to make it into an ionic state.

Because they do not easily and presented in a form of iodine (I _2), that this removal / concentration of iodine effectively present in the various chemical forms of iodine in the aqueous solution is an iodine ion (I ^{- -),} iodate ion (IO ₃₎ Complete removal of iodine from radioactive wastewater from nuclear power plants, reprocessing plants, and other radioactive isotope applications without environmental hazards is very important, but there is a significant problem in practical removal.

Iodine exists as an isotope compound of various iodine elements having masses of 127, 129, 131, 132, and 133. Their chemical behavior is the same, but iodine elements with mass 129, 131, 132, and 133 are radioisotopes. It is radioactive. The half-life of most radioactive iodine isotopes is relatively short, ranging from hours to days, which can be attenuated by months of neglect, but iodine with a mass of 129 has a half-life of 1.57 x 10 ⁷ years. Not only is this impossible, but if it comes into contact with the human body, it is concentrated in certain organs and continues to emit radiation, causing great detoxification. Therefore, there is an urgent need for a technique that can effectively remove even small concentrations.

In general, the most widely used treatment method for removing iodine is organic anion exchange resin or activated carbon. Republic of Korea, etc. Registration No. 10-0680582 discloses a method of removing iodine there is a mixture of an organic anion exchange resin are posted, i.e. ions form, iodide ion at the time of removing the iodine mixture, using organic anion exchange sujieul iodine (I ^-), different from the efficiency of removal by the anion exchange resin according to the type of which an iodine ion (I ^{-) -} iodate ion (IO ₃₎ ^- the response characteristics of the ion exchange with the anion exchange resin, iodate ion (IO ₃₎ Because they do not match completely. As a result, an iodine ion (I ^-) in comparison iodate ion (IO ₃ ^-), as well as have the difficult to eliminate the problem, not removing the iodine (I ₂₎ that the organic anion exchange resin is present a part in an aqueous solution as There is a problem of discharge. Therefore, when treated with an anion exchange resin, there is a limit to completely remove them from an aqueous solution containing iodine, iodine ions and iodide ions, etc. A separate chemical treatment process is required to make and remove it. However, certain chemical form of the waste water in a quantitative amount of the complex medium of many samples that is, an iodine ion (I ^-) to make it virtually impossible for the complete removal of iodine with organic anion exchange resins is limited. In particular, in the case of wastewater containing various interfering substances due to the characteristics of wastewater, iodine may be almost impossible to remove, and the reduction degree of iodine ion concentration must be accurately analyzed to achieve complete reduction and then passed through the ion exchange resin to remove the trace amount In the case of concentration it is also very difficult to check the degree of reduction.

The method of removing iodine using activated carbon is effective in removing iodine (I ₂ ) in aqueous solution, but activated carbon is hardly exhibited in the ionic state of iodine ion (I ⁻ ) and iodide ion (IO ₃ ⁻ ). Use alone has no effect. Accordingly, an iodine ion (I ^-), iodate ion (IO ₃ ^-) by applying a separate oxidation processing method to a conversion to a state of iodine (I _2), but then removed method devised by adsorption by activated carbon, such The method has a problem of acidification by adding acid to the wastewater solution, and in case of a large amount of wastewater, there is an additional problem of causing secondary pollution and treating and neutralizing again. In addition, the molar ratio of iodine ion and iodide ion should be exactly 5: 1, which is actually a difficult task in the field, and if a small proportion is changed, it can be discharged without being removed. . In addition, if the ratio is not 5: 1, an additional amount of iodine must be added, and it is not efficient to add iodine to be removed. It must be added in volume, which is actually a difficult method. And since there are many other ions in the wastewater solution to be treated, there is a concern that more interference causes problems. The most problematic point is that iodine (I ₂ ) is solubility in aqueous solution, so it does not dissolve in water and is especially volatile as a sublimable material. Therefore, in the case of radioactive waste water, it is open to radioactive materials. There is a possibility of volatilization, which can be rather dangerous. Although a method for using the waste water is added to the silver ions (Ag ⁺⁾ removed to induce the following precipitate which yield the compound of silver iodide (AgI), in this case iodate ion (IO ₃ ^-) will improve it, because it does not be done, the precipitation The intended method has been devised. This invention provides an iodine ion (I ^-), iodate ion (IO ₃ ^-) iodate ion (IO ₃ ^-) by the addition of silver nitrate to the mixing radioactive sodium sulfite and the precipitating agent as a reducing agent in the waste water are mixed, and then for 72 hours in an iodine ion (I ^-) was reduced to the next has been designed in a way to remove the precipitated silver iodide. However, this method is not effective because of its limitation in practical application such as excessive reduction and precipitation time, and thus iodine ions (I ⁻ ), iodine ions (IO ₃ ⁻ ) and iodine ( There is no technology developed to use the mixture of I ₂ ) in the field without a separate complicated process.

The present inventors have tried to solve the problems of the conventional method of removing the iodine mixture, and as a result, the active aluminum oxide modified surface with Ag, silver, which is supported by Ag (silver) is used for the iodine ion and the iodide ion. It has been found that the present invention is very effective in the removal, thus completing the present invention. That is, it is an object of the present invention to provide a method for efficiently and completely removing various types of iodine mixtures present in aqueous solutions such as radioactive and general industrial wastewater.

The present invention for solving the above-mentioned problem is iodide (iodide ion, I ^-), iodate ion (iodate ion, IO ₃ ^-) and iodine (iodine, I ₂₎ of aluminum oxide and the mixture discontinued or two or more kinds selected from the active The present invention provides a method for removing an iodine mixture from an aqueous solution by using one or two or more kinds of adsorbents selected from activated aluminum oxide and activated carbon carrying Ag.

Such a method for removing the iodine mixture of the present invention is capable of effectively removing and concentrating iodine without a separate oxidation or reduction reaction to make the iodine mixture into a single ion state, using nuclear power plants, reprocessing plants, and other radioisotopes. Iodine can be completely removed from the radioactive wastewater generated by the organs without environmental hazards.

The present invention described above will be described in detail below. First, as used herein, the term iodine mixture refers to one or two or more selected from iodine ions (I ⁻ ), iodate ions (IO ₃ ⁻ ), and iodine (I ₂ ). do.

The present invention relates to a method for removing an iodine mixture from an aqueous solution, wherein one or two species selected from iodine ions (I ⁻ ), iodate ions (IO ₃ ⁻ ), and iodine (I ₂ ) The above mixture is characterized by using one or two or more kinds of adsorbents selected from activated aluminum oxide, activated aluminum oxide and Ag-supported activated carbon.

In the present invention, the active aluminum oxide and Ag-supported active aluminum oxide may be used an acidic or basic active aluminum oxide, more specifically, the acidic active aluminum oxide and Ag-supported acid when removing the iodide ion It is preferable to use one or two species selected from active aluminum oxides, and it is preferable to use one or two species selected from basic activated aluminum oxide or basic active aluminum oxide carrying Ag when removing iodine ions. The active aluminum oxide is an amorphous porous aluminum oxide obtained by heat-treating aluminum hydroxide to remove moisture, and has a specific surface area of 100 to 300 m ² / g, and has an external porosity of 40 to 50%, depending on the surface state. It is prepared in neutral, acidic, weakly acidic form, and in the present invention for removing iodine, the surface state shows basic and acidic properties, and the average particle size is 3.5 mm or less, preferably 0.05 mm to 3.5 mm of active aluminum oxide. Can be used. In addition, the acidic active aluminum oxide is one or two selected from the specific surface area of 100 ~ 300 m ² / g and 3.5 mm or less, preferably 0.05 mm ~ 3.5 mm average particle size depending on the concentration and amount of wastewater to be treated The above can be used efficiently, and the basic active aluminum oxide also has a specific surface area of 100 to 300 m ² / g and an average particle size of 3.5 mm or less, preferably 0.05 mm to 3.5 mm, depending on the concentration and amount of wastewater to be treated. One or two or more selected from the size can be used efficiently. Here, if the average particle size of the active aluminum oxide containing basic, acidic, silver-supported basic or silver-supported acidic active aluminum oxide is less than 0.05 mm, the adsorption removal rate is increased when the iodine mixture is removed from the aqueous solution using a packed column. However, because the flow rate is too slow, the processing time takes excessively long, and when the thickness exceeds 3.5 mm, the specific surface area of aluminum oxide becomes smaller, which may cause a problem of lowering the treatment efficiency, thereby having an average particle size within the above range. It is good.

Next, the activated carbon is used to remove iodine, and activated carbon is classified into vegetable, coal, and petroleum according to raw materials. The activated carbon is carbonized by immobilizing these raw materials, and the surface is heated at high temperature with gas or chemicals. Activated carbon is used to develop surface area and pores, and in the present invention, it has a specific surface area of 500-1500 m ² / g and 35-40% external porosity and activated carbon of 0.5 to 3.5 mm granular coal to facilitate filtration of aqueous solution. Can be used.

The present invention can be removed at the same time or sequentially iodine mixtures, regardless of the removal order, but the following describes a method for removing sequentially.

The present invention various types of iodine mixture That is, iodide ion, using the compound treatment system of the activated aluminum with activated carbon oxidized in the radioactive waste water and industrial waste water containing the iodide mixture (I ^-), iodate ion (IO ₃ ^-), and A method for removing iodine (I ₂ ) batchwise or continuously, the present invention provides

From an aqueous solution containing one or more species selected from iodine ion (I ⁻ ), iodide ion (IO ₃ ⁻ ) and iodine (I ₂ ),

A first step of adsorbing and removing iodic ions with one or two selected from acidic active aluminum oxide and Ag-supported acidic active aluminum oxide;

A second step of adsorbing and removing iodine ions with one or two selected from basic active aluminum oxide or basic active aluminum oxide carrying Ag; And

And a third step of adsorbing and removing iodine with activated carbon.

The first to third steps are illustrated in FIG. 1 as an example of the present invention, and the present invention is not particularly limited thereto.

The method of removing the iodine mixture of the present invention is a removal reaction by adsorption which does not require activated redox reactions as well as activated carbon as well as the surface area of the activated carbon, it is delayed for several minutes to several hours as a separate reaction time. It is a very effective method because there is no reason to do it, and it does not have a separate reaction process that converts various types of iodine in aqueous solution into specific ionic forms, thereby improving inefficient processes such as separate pollution and consumption of working time, and at the same time. In addition, by providing a method for effectively removing iodine ions and iodine ions, the removal of the iodine mixture and the efficiency of the process can be greatly improved compared to the existing methods.

Hereinafter, the present invention will be described in more detail based on examples. However, the scope of the present invention is not limited by the following examples.

Example 1

0.50 ㎎ / L concentration of iodide ion (I ^-) containing the basic active aluminum oxide Ag is supported on 100 mL of (basic activated aluminum oxide, US Merck's particle size 0.063mm ~ 0.2 mm, a specific surface area of 200 ~ 220 m ² / g and 0.2 g of aluminum oxide having 43 to 45% external porosity), and then uniformly adsorbed, filtered and analyzed by ICP / MS, and the concentration of iodine ion (I ⁻ ) remaining in the filtrate after adsorption was 0.004. Mg / L or less.

Example 2

0.50 ㎎ / L concentration of iodate ion (IO ₃ ^-) acidic active aluminum oxide in an aqueous solution of 100 mL containing (US Merck's particle size 0.063 mm ~ 0.2 mm, a specific surface area of 200 ~ 220 m ² / g and 43 to 0.1 g of aluminum oxide having 45% external porosity and 0.1 g of acidic activated aluminum oxide (silver nitrate prepared by adding 5-50 g of active aluminum oxide to a solution of 0.01% to 5% concentration) and uniform The mixture was adsorbed, adsorbed, and analyzed by ICP / MS. As a result, the concentration of iodine ions (IO ₃ ⁻ ) remaining in the filtrate after adsorption was 0.002 mg / L or less.

Example 3

0.05 g of activated carbon was added to a 100 mL aqueous solution containing 0.50 mg / L of iodine (I _2, prepared by oxidizing iodine ions), followed by adsorption. The filtrate was analyzed to be 0.003 mg / L or less.

Example 4

A mixed solution of 0.50 mg / L of iodine ion (IO ₃ ⁻ ), 0.50 mg / L of iodine ion (I ⁻ ) and 0.50 mg / L of iodine (I ₂ ) was added to an acidic activated aluminum oxide. The total concentration of iodine ions, iodine ions, and iodine remaining in the water after passing through the packed column followed by silver packed column of basic activated aluminum oxide, followed by adsorption 0.004 mg / L or less.

Example 5

After adsorbing and removing the mixed solution of 10 mg / L of iodine ion (IO ₃ ⁻ ), 10 mg / L of iodine ion (I ⁻ ) and 10 mg / L of iodine (I ₂ ) in the same manner as in Example 4 above, The total concentration of iodine ions, iodine ions and iodine remaining in the passage water was less than 0.009 mg / L.

Comparative Example 1

In the same manner as in Example 4, the active aluminum oxide of the basic active aluminum oxide on which the acidic active aluminum oxide and silver are supported was used having an average particle size of 4 to 5 mm, specific surface area of 75 m ² / g, The total concentration of iodine ions, iodine ions and iodine remaining in the passage water was 0.150 mg / L.

As described above, the removal method of the present invention carried out in Examples 1 to 5 has a very high adsorption and removal efficiency of iodine ions, iodic ions and iodine, so that the residual concentration of iodine mixtures after treatment is very low, Comparative Example In the case of 1, the removal efficiency is lower due to the particle size and specific surface area than Examples 1 to 5, it was confirmed that the residual concentration of the iodine mixtures. As described above, the method for removing the iodine mixture from the aqueous solution of the present invention relates to a method in which the process is very simple and the reaction rate is not only fast, but also does not undergo a separate chemical treatment, so that the next separate contamination does not occur. It is also very useful in the field of treatment of radioactive and industrial wastewater contaminated with iodine.

1 is a schematic diagram of a process for sequentially removing them from a wastewater solution containing an iodine mixture according to the present invention.

Claims (7)

Iodide ion (I ^-), iodate ion (IO ₃ ^-) and iodine (I ₂₎ from aluminum, discontinued, or two or more kinds selected from the group consisting of activated aluminum and activated carbon oxidation Ag is supported active oxide selected discontinued or as mixtures of two or more thereof Adsorbing with adsorbent to remove iodine mixture from aqueous solution. The method of claim 1, wherein the iodine ion is adsorbed with an acidic active aluminum oxide single or two kinds of adsorbents supported with acidic aluminum oxide and Ag to remove the iodine mixture from the aqueous solution. The method of claim 1, wherein the iodine ion is adsorbed with a basic activated aluminum oxide single or two adsorbents carrying basic activated aluminum oxide and Ag to remove the iodine mixture from the aqueous solution. The method of claim 1 wherein said iodine is adsorbed with activated carbon to remove the iodine mixture from the aqueous solution. The method of claim 1, A first step of adsorbing and removing iodic ions with one or two selected from acidic active aluminum oxide and Ag-supported acidic active aluminum oxide; A second step of adsorbing and removing iodine ions by one or two selected from basic activated aluminum oxide and basic activated aluminum oxide carrying Ag; And A third step of adsorbing and removing iodine with activated carbon; Method for removing the iodine mixture from an aqueous solution comprising a. The method of removing an iodine mixture from an aqueous solution according to any one of claims 1 to 5, wherein the active aluminum oxide has a specific surface area of 100 to 300 m ² / g and an external porosity of 40 to 50%. . The method of claim 1, wherein the active aluminum oxide has an average particle size of 0.05 mm to 3.5 mm.

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