JPS6019762B2 - Chitosan-iodo adduct - Google Patents

Description

[Detailed description of the invention] The present invention relates to novel chitosaniodine adducts.

The invention further relates to the production and use of such novel chitosaniodine adducts. According to the research conducted by the present inventors, it has been found that iodine binds extremely specifically to chitosan, a natural product, to give a product different from either of the two.

Formation of a product by such an interaction between chitosaso and iodine has not been known at all. Chitosan has the following structure and has a structure similar to starch. Chitosan is obtained by heating and hydrolyzing chitin (acetyl-chitosan), which forms the skeleton of shellfish such as shrimp and crabs, with caustic soda, etc. The degree of polymerization varies depending on the hydrolysis conditions, but is usually about 2000. It is said that the molecular weight is 200,000~
It is said to be 400,000.

The degree of deacetylation due to hydrolysis also varies depending on the reaction conditions, but if about 50% is deacetylated, the product becomes soluble in acidic solutions. Such deacetylated chitin is known as chitosan. The inventors have discovered that when some chitosan is contacted with iodine, it gives a product in which both are tightly bound.

This product of chitosan and iodine is not a mere mixture, as shown in the attached X-ray diffraction diagram, when comparing the X-ray diffraction patterns of chitosan and iodine alone with that of the chitosan-iodine product according to the present invention. , the above two each have a crystal plane (the X-ray diffraction diagram has a large peak), whereas the latter has an amorphous X-ray diffraction diagram (the X-ray diffraction diagram is almost a straight line with a peak). This is supported by the fact that Regarding the bonding mode of the chitosaniodine adduct according to the present invention, it is thought that chitosan and iodine form an inclusion compound. Here, the term "clathrate compound" is used synonymously with the so-called clathrate compound.
For example, when comparing the infrared absorption spectra (KBd removal) of the chitosaniodine adduct and chitosan alone, the shapes of the two completely match, and there is no change in the absorption part of the amino group (1N Buddha), which is the active group of the chitosan molecule. I can't accept it. This suggests that iodine atoms are probably incorporated into the lattice matrix provided by the chitosan molecule. The formation of chitosaniodine adducts according to the invention is accomplished almost instantaneously, for example, by contacting chitosan with an iodine solution (which may contain iodine) in any solvent.

Chitosan is originally white, but when it forms a chitosan-iodide adduct, it turns black, while the iodine solution loses its black-brown color. Therefore, the iodine uptake of chitosan can be brought to a saturated state by bringing iodine into contact with the iodine solution until a dark brown color remains. Quite surprisingly, chitosan can interact with iodine to form chitosan-iodine adducts, whereas natural chitin does not. The medium for bringing the chitosan and iodine solution into contact is suitably water, lower alcohol, or a mixture thereof. Iodine ions, such as potassium iodo, may be present to assist in dissolving iodine. Although the contact between chitosan and the iodine solution can be carried out at any temperature, it is convenient to contact the chitosan with the iodine solution at or around room temperature. After contact, the chitosaniodine adduct can be directly separated from the medium as a solid. Even when this material was washed with water, its black color did not easily disappear, indicating that iodine was reliably captured by the molecular structure of chitosan. The chitosan-iodine adduct thus formed exhibits the general shape of chitosan, ie, a scaly morphology, and is a nearly black solid.

When kept at a temperature of 8,000°C or higher, especially 100°C or higher, iodine rapidly evaporates and returns to the original white chitosan.

Furthermore, when the temperature is raised to 200q○ or more, it does not melt,
Gradually carbonizes. When immersed in alkaline water solution at room temperature, iodine is rapidly released and the original white chitosan is obtained. When soaked in a dilute monobasic acid solution, it gradually dissolves to form a brownish solution, but when this solution is left for a long time, a precipitate forms. When soaked in neutral water, it gradually releases a certain amount of iodine and takes on a light yellowish brown color. The apparent specific gravity of this product is approximately 0.2. Furthermore, even if left as a solid, it has almost no volatility at room temperature, and is almost odorless with no irritating odor of iodine. According to one aspect of the present invention, the acquisition of essential iodine can be achieved using the chitosaniodine adduct-forming action disclosed by the present invention. For example, one of the methods for producing iodine from natural citrus water, which currently contains a certain amount of iodine (approximately 10 degrees of iodine), uses an anion exchange resin, but it is possible to use chitosan instead of this ion exchange resin. You can also do it. In particular, in the case of water containing iodine, which is ranked No. 2, the amount of adsorption is small compared to ion exchange resins.
However, it is also characterized by its excellent adsorption power. For example, Chiba Prefecture's natural underground water currently contains about 70 to 12 capes of iodine, and ion exchange resin Am is used to recover this iodine.
Although rlite K-400 is used commercially, the iodine recovery limit in this case hardly exceeds 80%.

On the other hand, the use of the chitosaniodine adduct-forming effect of the present invention is extremely advantageous in that it is possible to further recover iodine from the eel water after treatment with the ion photoconversion resin. In addition, the chitosaniodine adduct according to the present invention can hold iodine in a stable form and gradually release active iodine into the surrounding environment as necessary, so that active iodine can be used in applications such as deodorants, disinfectants, etc. It is useful in all fields. In one application, chitosaniodine adducts in the form of scaly crystals of appropriate particle size are charged in a container with a string hole and water is passed through the container at an appropriate rate to produce drinking water, dishwashing liquid water, and pool water. It can be used as a disinfectant. For example, chitosan, which is the base of chitosaniodine, is extremely soluble in neutral water, so by wrapping chitosaniodine in cloth or the like and soaking it in a bathtub, or soaking it in the fresh water tank of a flush toilet, you can It is also possible to sterilize purified water by liberating a certain amount of iodine. In such a usage mode, chitosan, which is a natural product, remains after performing the bactericidal or deodorizing action, and this is a major advantage from an ecological standpoint. That is, as long as the chitosaniodine adduct according to the present invention is used, there is no risk of it lacking in safety as seen in chemically synthesized products. Example 1 The raw material, chitosan, is made by soaking crab shells such as crab and king crab in dilute caustic soda (3-%) overnight to dissolve and remove the protein, oil, etc. contained in the crab shells, and then soaking them in dilute hydrochloric acid (3%). Refined chicken, which has been soaked in water to remove calcium carbonate, is soaked in several times the amount of concentrated caustic soda solution (45% or more), kept at 80-100 ℃ for several hours, and then washed with water. This is dried and has 3%
When dissolved in acetic acid solution, the viscosity at 20 qo at a concentration of 0.5% is 200-80 ratio. p. It is s.

The obtained chitosan was soaked for a day and a night in 40' solution containing 4 parts of iodine and 4 parts of iodopotassium, then heated in the oven, the adhering mother liquor was removed by washing with a small amount of water, and then heated at a temperature of 30 degrees or less. The mixture was dried through ventilation to obtain 14.5 black scale-like chitosanodide adducts.

This product was found to contain approximately 3.4 hours of iodine by measuring the iodine separated by furnace and the residual iodine in the iodopotassium solution (including washing water). Example 2 This example demonstrates the recovery of iodine from dilute iodine-containing surf water using chitosan.

Satosan 100 yen (approx. 1 yen, apparent specific gravity 0.1) with a diameter of 1
2 Fill a cylinder with a height of 1.5 rudders, and add 200
When the blood-containing water (after adding the corresponding amount of chlorine) with 10 iodine is passed through at a rate of 100 min, about 9 iodine of iodine is adsorbed on chitosan by 100 min, and the iodine content of the passing water is 8 ~
There will be 12 blood.

Next, when a 6% caustic soda solution is passed through the iodine-adsorbed chitosan at 150 ml, the adsorbed iodine is dissolved in the caustic soda solution according to the following formula, and the chitosan returns to its original white color. Thigh aOH + 9Nal+Nal03
10 days 20 13 days 2 S04 → 312 10 days 20 This is filtered to obtain about 9 days of crude iodine.

The white chitosan is used again for the next iodine adsorption. Example 3 It is known that iodine has a bactericidal effect on Escherichia coli and the like in water at a concentration of about one leg.

This example demonstrates that such bactericidal effective concentrations can be achieved utilizing the chitosaniodine adducts of the present invention. 'a - Chitosa soyodo adduct with a yodo content of about 30% 200
Evening (apparent capacity approximately 1 evening), diameter 12 skins and height 1.1m
If water is passed through the cylinder at a rate of 10 per minute, the iodine content in the passing water will be 1 to 3 feet per minute.

'B - Wrap 10 pieces of chitosaniodine adduct with about 30% iodine content in a cloth, immerse it in water, and slowly immerse it in water.The iodine concentration in the water will increase over time, After about 0.7 legs, after 15 minutes it reaches 2.2 legs, and after 20 to 25 minutes it reaches 3 legs, and has sufficient bactericidal efficacy.

[Brief explanation of the drawing]

In the accompanying drawings, FIG. 1 is an X-ray diffraction diagram of chitosan, FIG. 2 is an iodine diagram, and FIG. 3 is an X-ray diffraction diagram of the chitosan-iodine adduct of the present invention. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A chitosan-iodine adduct characterized in that iodine is encapsulated by chitosan. 2. It is characterized by bringing chitosan into contact with an iodine-containing solution. A method for producing a chitosan-iodine adduct in which iodine is encapsulated by chitosan. 3. The method of item 2 above, wherein the iodine-containing solution is an iodine-containing natural brine, whereby iodine is recovered from the brine. 4. A deodorizing disinfectant containing as an active ingredient a chitosan-iodine adduct in which iodine is encapsulated by chitosan.