JPH0433516B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a filter for filtering purified water, and particularly to a filter for removing mutagenic substances contained in purified water such as city tap water. It has been reported at academic conferences that purified water, especially chlorinated municipal tap water, contains substances that are mutagenic or carcinogenic.
Its removal is desired. For example, this is also stated in "Matagenicity level of urban tap water" (Nunoshiba et al.) in Doshisha University Faculty of Science and Engineering Research Report, Vol. 24, No. 3, p. 61; contained in water
CHCl ₃ , CHBrCl ₂ , CHBr ₂ Cl, CHBr ₃ , CCl ₄ ,
CH ₂ Cl−CH ₂ Cl, CHCl=CHCl, NH ₂ Cl, o−
Trihalomethane-based substances such as dichlorobenzene and p-dichlorobenzene have been described, and all of these substances have been reported to have mutagenicity or carcinogenicity according to the Ames Test, and are not included in municipal tap water. Reducing or eliminating harmful substances, mainly trihalomethanes, is currently a major problem. Traditionally, sedges contained in urban tap water,
The use of activated carbon has been proposed as a method for removing odors, and is actually installed in the form of cartridges in municipal tap water faucets. However, these do not actively remove mutagenic or carcinogenic substances such as trihalomethanes. As a result of intensive research into filters that remove mutagenic substances from these city water supplies, the present inventors discovered that mutagenic substances can be removed by using chitin as a filtering material, and have arrived at the present invention. be. That is, the present invention is a filter for filtering purified water such as urban water supply, which contains chitin within the filter. Chitin as used in the present invention refers to poly(N-acetyl-D-glucosamine) or its derivatives obtained by treating crustaceans, insects, etc. with hydrochloric acid and caustic soda to separate and purify protein and calcium components. means. Examples of chitin derivatives include so-called chitosan in which some or all of the acetylamino groups of chitin are deacetylated, chitin etherified products, esterified products, carboxymethylated products, hydroxyethylated products, o-ethylated products, etc. Something that has been metamorphosed can be mentioned. The filter for purified water filtration of the present invention is made by packing chitin in a solid state into a container such as a column so that water can flow through it. To create the filter of the present invention, for example, chitin powder may be used as it is or chitin may be dissolved in a solvent to form various molded objects such as fibers, films, and non-woven fabrics, and then packed in a column or the like. . In the case of chitin in the narrow sense with many acetylglucosacin groups, the specific method for producing the molded article is to use a mixed solution of trichloroacetic acid and a halogenated hydrocarbon, or a mixture of lithium chloride and N-methylpyrrolidone or dimethylacetamide. One method is to make a dope by dissolving chitin in a mixed solution with aqueous acetic acid, and then coagulating this dope with water, alcohol, ketones, etc. In the case of chitin, so-called chitosan, which has many glucosamine groups, chitosan is dissolved in an acetic acid aqueous solution. An example of this method is to prepare a dope and coagulate the dope in water or an alcohol solution containing an alkali. The filter of the present invention can be attached to a municipal water tap or the like and used to filter water, and can adsorb mutagenic substances as the water passes through it. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1, Comparative Examples 1 and 2 Chitin powder was treated with a 40% caustic soda aqueous solution at 95° C. for 3 hours to produce chitosan powder.
This powdered chitosan was sufficiently washed with water and dried, and then dissolved in a 0.1 acetic acid aqueous solution to prepare a chitosan dope having a concentration of 8% by weight. This dope was transported by a gear pump, extruded from a nozzle into methanol containing 5% by weight of caustic soda, and wet-spun to obtain a multifilament with a single denier of 2d. After thoroughly washing and drying this filament, it was cut into a length of 30 mm, and the fibers were opened to form a cotton-like shape. 5 g of this cotton was packed into a cylindrical column with an inner diameter of 2 cm and a height of 5 cm, and after flowing city tap water chlorinated with sodium hypochlorite at a rate of about 2 m ² /hr for one week, the cotton was removed from the column. was taken out, thoroughly washed with distilled water, and dried. For comparison, commercially available 1.8 denier rayon yarn (Comparative Example 1) and activated carbon (GP60 manufactured by KITARA Industries) were used.
(Comparative Example 2) was taken in 5g portions and packed into the same cylindrical column as in Example 1, and city tap water was poured under the same conditions as in Example 1. After drying, the cotton, yarn or activated carbon is finely ground and then dispersed in dimethyl sulfoxide.
I did the Ames test. Salmonella as a strain
The number of mutagenic colonies was determined using TA-100. The results were as shown in Table 1. As is clear from Table 1, both Salmonella TA-98 and TA-100 strains dispersed in the cotton of Example 1 produced a large number of colonies with mutations compared to the control, whereas Comparative Examples 1 and 2 In the case of , there was no significant difference from the control, and it was determined that the mutagenic substance was adsorbed in the sample of Example 1.

[Table] Example 2 Chitin powder was ground into 100 meshes and 1N-HC1
The chitin powder was treated at 4° C. for 1 hour, and further heated at 90° C. for 3 hours in a 3% NaOH solution to remove calcium and protein contained in the chitin powder, followed by repeated washing with water and drying. The chitin thus obtained was dissolved at room temperature in a dimethylacetamide solution containing 7% by weight of lithium chloride to a concentration of 7% by weight. The obtained solution was filtered through 800 mesh gold steel, left to defoam, and then poured into a tank.
Transported by gear pump under pressure, diameter 0.07mm
It was extruded into coagulating liquid water through a nozzle with φ, 200 holes, solidified, and wound on a perforated bobbin at a speed of 10 m/min. When this bobbin was thoroughly washed with warm water and dried, chitin fibers with a single yarn denier of 1.5 d were obtained. 5g of this chitin fiber was placed in the same column as in Example 1.
After filling and flowing chlorinated city tap water at a rate of about 2 m ² /hr for one week, the fibers were removed from the column, washed with methanol, and dried. The dried fibers were pulverized, dispersed in dimethyl sulfoxide, and subjected to the Ames test in the same manner as in Example 1. The results shown in Table 2 were obtained.

[Table] As is clear from Table 2, in the case of Example 2 as well, it was found that mutagenic substances in city tap water were adsorbed in the same manner as in Example 1.

Claims (1)

[Claims] 1. A filter for filtering purified water such as city tap water, which contains chitin within the filter.