JPS58110402A - Recovering method for iodine - Google Patents

Abstract

PURPOSE:To recover iodine efficiently from an aqueous soln. contg. iodine ions by using strongly basic anion exchange fibers having a specified average diameter as an ion exchanger. CONSTITUTION:Fibers such as synthetic polyvinyl alcohol fibers having 0.1- 30mum average diameter are subjected to quat. amination, treatment for providing a hydrophobic property, or other treatment to prepare strongly basic anion exchange fibers. The exchange fibers are optionally knitted or woven and packed into a column. By passing an aqueous soln. contg. iodine ions through the column, iodine contained in the soln. is allowed to be adsorbed on the exchange fibers. The iodine adsorbed on the fibers is then eluted with an eluting soln. such as an aqueous soln. of sodium hydroxide, and it is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently recovering iodine from an aqueous solution containing iodine ions using a fibrous ion exchanger.

Conventionally, activated carbon adsorption methods have been known as methods for recovering iodine from natural gas acupuncture water containing iodine ions, etc., but in recent years improvements have been made to effectively adsorb and elute iodine using granular anion exchange resins. The method is, for example, Japanese Patent Publication No. 53-28038,
It has been proposed in Japanese Patent Publication No. 54-10357. In this case, from the viewpoint of ease of handling, a resin having a rice grain diameter of about 50 to 20 G mesh is often used.

The present inventors have been conducting research to more effectively recover iodine using a fibrous ion exchanger that has a large surface area and can be modularized in many ways. The inventors discovered that the purpose could be achieved by using exchange fibers and completed the present invention.

That is, in the present invention, the average diameter of fibers as an ion exchanger is 0.
This is a method for efficiently recovering iodine by using strongly basic anion exchange fibers with a thickness of 1 to 30 μm, preferably FilO μm to 0.1 μm.

According to the method of the present invention, the adsorption rate and adsorption rate of iodine and the elution rate of adsorbed iodine are extremely high, and iodine can be recovered industrially and more advantageously.

The strongly basic anion exchange fiber used in the present invention has a diameter of 30 μm or more. , the iodine adsorption rate decreases,
In addition, ultrafine fibers with a diameter of 0.1 μm or less have an increased moisture content, resulting in a decrease in mechanical strength and an increase in liquid passage resistance, making them difficult to handle and making it difficult to fully achieve the purpose of the present invention. Become.

The ion exchange groups of the strongly basic anion exchange fibers used in the present invention are not particularly limited, but for example, strongly basic anion exchange fibers having a quaternary amino group bring about favorable results suitable for this purpose. .

Further, as the method for introducing this ion exchange group, it is possible to employ a commonly used method for introducing the ion exchange group.

The ion exchange capacity of the fiber depends on the amount of ion exchange groups introduced, but an exchange capacity equivalent to or slightly lower than that of the ion exchange resin is sufficient, and excessive ion exchange capacity should not be avoided. do not need.

The strong basic anion exchange fiber used in the present invention can be processed into any shape, such as a ring or a woven fabric, so it is possible to reduce the resistance to liquid flow by selecting the shape, and it is possible to recover using methods other than the packed bed method. Application to devices is also possible.

Hereinafter, the effects of the present invention will be explained in detail through experimental examples and examples.

Experimental example: Strongly basic anion exchange fibers (0, 0,
5% cut fiber) and commercially available strong basic anion exchange resin (
12.71//1 of iodine under strong stirring
．． The sample was put into a solution with a concentration of 16.6 #7 tons of potassium iodine (bath ratio 1:100), samples were taken out at regular intervals, and the adsorbed iodine was measured. The results are shown in Figure 1. Further, the amount of adsorbed iodine when iodine was saturated adsorbed was as shown in Table 1.

The results in Figure 1 and Table 1 show that the ion-exchange fiber of the present invention adsorbs iodine extremely quickly from a dilute iodine bath solution, and the saturated adsorption capacity is surprisingly more than twice the ion-exchange trough. I understand.

It has been confirmed that the large amount of absorption is due to ion exchange reactions and physical adsorption.

Ion exchange fiber with saturated adsorption of iodine (NQ5 in Table 1)
Sample) and ion exchange resin (NQ7 sample in Table 1) were each put into a 2N-NaOH aqueous solution under stirring (bath ratio 1).
Figure 2 shows the results of observing the relationship between elution time and elution rate when iodine was eluted. In addition, iodine in the eluent was obtained by filling a column with an inner diameter of 259 mm with 10.9 g of each of the same saturated absorption samples and eluting it by passing a 2N-NaOH water bath solution in a downward flow at a flow rate of 12011 j/min. The amount was measured at regular intervals.

The results are shown in Figure 3.

As shown in the experimental results shown in Figures 2 and 3, the iodine adsorbed into the ion-exchange fiber of the present invention has an extremely fast elution rate, and is almost completely eluted with an eluent of 1 less charge. , it can be seen that there are great industrial advantages in this aspect as well.

FIG. 4 shows the measurement results of the relationship between the average diameter, water permeability, and water absorption rate of ion exchange fibers (samples listed in Table 1).

Water permeability was determined by filling a column with a diameter of zs% with 311 samples (packing density 0.32N/WLt) and 0.3kp/cyy.
It is expressed as the amount of water passed per minute when water is passed under + pressure. The water absorption rate is (weight after dehydration ÷ dry type 1i) x 100/
Expressed as dry weight.

From FIG. 4, it can be seen that as the average diameter of the ion exchange fibers decreases, the water absorption rate of the fibers increases, the water permeability decreases, and it becomes difficult to handle.

As shown in the above results, ion-exchange fibers with an average fiber diameter of 10 μm or less, particularly preferably about 11 μm and 0.2 μm, are suitable for recovering iodine, and together with their moldability, they have high industrial utility value. I know it's expensive.

Example 1 45 parts of PVA with an average degree of polymerization of 1200 and an average molecular weight of jl13
55 parts of polyethylene oxide (PEO) with a concentration of 35% was mixed and dissolved by heating to form a spinning stock solution with a concentration of 35%. ′
This was dry spun using a conventional method to obtain a fineness of 150 d/30 f.
, the yarn had a softening point in water of 88°C. 20 pieces of this thread
0 T/M heating, washing in string form with water, and dissolving and removing the PEO component, the threads became fibrillated and became PVA-based fibers.

After acetalizing this ultrafine fiber with chloroacetaldehyde, it was cross-treated with ethylenediamine, and then trimethyla,
Min treatment and neutral salt exchange'6it 2.2meq/i
, Softening point in water: 114℃, Water absorption rate at 49℃: 180%,
A strong base anion exchange fiber with an average fineness of 05 μm was used.

This fiber was cut into 0.7-length pieces and 5.0 g was packed into a column with a diameter of 59-mm. The filling volume in this case was 20σ1. This includes iodine ions.

Acupuncture containing 75 ppm - 50 ppm chlorine gas in water
The injection rate was 1,240/* at a flow rate of 50j/H. No date was accumulated in the effluent.

Next, 50°C (010% NaOH aqueous solution 2001 was poured down for 1 minute, and then 1091NaC/aqueous solution 40% at 50°C was poured down.
01L6 was flowed down in 2 minutes. Iodine ions in the flowing liquid are 71.211/2001u and 12 and 51, respectively.
/ 4 G 01+4 was included.

Example '2゜ The yarn with a fineness of 150 d/30 f, which was dry spun in Example 1, was knitted into a cylindrical knitted fabric with a valley diameter of 4 inches and 200 needles, and washed with water to remove the fineness in the yarn. The PEO component was dissolved and removed to obtain ultrafine PVA fibers.

This was etherified with epichlorohydrin, then acetalized with formaldehyde, and then 7minated with trimethylamine, resulting in a neutral salt exchange capacity of 1.8 meq/G,
It was made into a strong anion exchange fiber with a softening point in water of ITO°C, a water absorption rate of 220% at 40°C, and an average fineness of 1 μm.

This knitted exchange fiber 10JI was mixed with 75 iodine ions.
Contains ppm [50 ppm of chlorine gas in water]
It was immersed in the added material 20j for 3 hours. This operation was repeated 12 times, but the iodide ion concentration in the residue up to the 11th time was less than 10 ppm, but the 12th time II'
i40 ppm.

Next, this stockinette was immersed in 200 ml of a 10% NaOH water bath solution at 50°C for 05 hours, and further soaked in 10% NaCl.
The procedure of immersion in an aqueous solution of 200 ru for 0.5 hours and centrifugal dehydration was repeated twice to elute l&shield iodine. fiber g
The yield of iodine per unit was 1.55#.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between iodine adsorbed by an ion exchanger and time, and Figure 2 is a graph showing the relationship between iodine absorption and time.
Graph showing the relationship between 11 and elution rate, Figure 3 is a graph showing the relationship between iodine electrons in the eluent and time, and Figure 4 is a graph showing the relationship between the average diameter of ion exchange fibers and water permeability and water absorption rate. It is. 1 person for patents Nichipi Co., Ltd. agent Yoshiryu Dokimura, patent attorney

Claims (1)

[Claims] A method for recovering iodine, which comprises using strongly basic anion exchange fibers having an average diameter in the range of 0.1 to 30 μm as an ion exchanger.