JPS6323829B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a metal ion adsorbent that selectively and efficiently adsorbs metal ions such as Cr ions and U ions from an aqueous liquid. Wastewater such as industrial wastewater and mine wastewater contains Cr ions,
They often contain toxic heavy metal ions such as Mn ions, and their treatment requires great effort. Various materials have been developed to adsorb these heavy metal ions, such as ion exchange resins, low-molecular chelating agents, chelating exchange resins, diatomaceous earth, zeolites, and crown ethers, but they are expensive to manufacture and have poor performance. However, it was not possible to find an adsorbent that exhibited sufficient effectiveness. Furthermore, in recent years, attempts have been made to adsorb and concentrate valuable resources such as uranium and rare earth elements contained in trace amounts in seawater, and a number of adsorbents have been proposed for this purpose as well. However, since trace amounts of metals are recovered from large amounts of seawater, the adsorbent must have extremely high selective adsorption ability, especially at low concentrations, but it is still not sufficiently effective. Not mentioned. Conventionally, attempts have been made to use protein fibers such as wool, hair, and feathers, or processed products thereof, as adsorbents for metal ions. For example, JP-A-48-
Publication No. 7891 proposes to adsorb mercury vapor by using chlorinated hair, feathers, etc. as an adsorbent filling material for mercury removal masks. Also Tokkai Akira
No. 49-16693 attempts to use reduced animal fibers such as wool and silk as a heavy metal trapping material. Furthermore, JP-A-52-63190,
Japanese Unexamined Patent Publication No. 52-64151 discloses an attempt to use a non-woven fabric made by mechanically processing wool as a mercury adsorption sheet;
Publication No. 89987 attempts to use a keratin-containing component such as feathers as an arsenic trapping material. Although each of these prior art techniques exhibits the effect of adsorbing metal ions, they have the following drawbacks. In other words, when natural protein fibers such as wool, silk, and feathers are immersed in an aqueous liquid and allowed to adsorb metal ions, a sufficient adsorption effect cannot be achieved, although it is unclear whether this is due to the dense structure of the fiber surface. . On the other hand, the chemically treated protein fibers have good contact with aqueous media, but
The swelling becomes extremely large, ultimately resulting in poor contact with the aqueous medium, and a sufficient adsorption effect cannot be achieved. The present invention changes from the conventional concept of using organized protein fibers produced by living organisms to adsorb metal ions using non-fibrous proteins. That is, the present invention is a metal ion adsorbent made of a hybrid polymer of protein and a vinyl monomer, particularly a protein-acrylonitrile hybrid polymer. The adsorbent of the present invention exhibits superior adsorption capacity compared to conventional adsorbents. The protein-vinyl monomer hybrid polymer of the present invention is a polymer in which a part of the protein is graft-polymerized with the protein, and the other part is a homogeneous mixture of the protein and the vinyl monomer. It can be used in an aqueous medium in any form such as solid, film, powder, or similar granules. The metal ion adsorbent may be dispersed in a medium or applied in a fixed bed. Proteins used in the adsorbent of the present invention include various proteins such as soybean protein, milk protein, gelatin, collagen, egg white, feather protein, silk fibroin, silk sericin, and wool decomposition products. As the vinyl monomer, one or more of acrylonitrile, acrylamide, acrylic acid, vinyl chloride, etc. can be used. Particularly preferred is acrylonitrile or a mixture of acrylonitrile and a small amount of other vinyl monomer. A suitable mixing ratio of protein and vinyl monomer is 10:1 to 1:50 by weight. To explain the method for producing a hybrid polymer using a protein-acrylonitrile hybrid polymer as an example, 50% to 70%
Mix protein and acrylonitrile in an aqueous solution of zinc chloride so that the ratio is preferably 3:1 to 1:20, add a small amount of peroxide such as persulfate or cumene peroxide, and polymerize. Make it react. After polymerization, this polymerization solution is used by forming into fibers, films, granules, etc. The above adsorbent may be used in combination with other metal ion adsorbents. There is also a means of using the adsorbent carrier of the present invention. For example, there is a method of adhering the adsorbent to the surface of water-insoluble fibers, films, etc., and there is also a method of using the adsorbent by holding it inside a porous body. Metal ions to which the adsorbent of the present invention can be applied include:
Contains all metal elements in the periodic table except group Ia. It is particularly effective against heavy metals such as mercury, cadmium, chromium gold, cobalt, nickel, manganese, and arsenic, yttrium, rare earth metals such as samarium, lanthanum, and scandium, and radioactive metals such as uranium, radium, and plutonium. The aqueous medium used as the adsorption treatment medium includes 100% water and mixtures with other organic solvents (aqueous solutions, aqueous emulsions, etc.), but water accounts for at least 5% of the total, preferably at least 10%. It is included. Normally, in adsorption treatment, the pH of the treatment liquid often has a large effect, but the adsorbent of the present invention can be used as long as it is not particularly strongly acidic or alkaline. The metals targeted by the present invention often exist in neutral or acidic conditions, but the adsorbent of the present invention sufficiently exhibits its ability even under acidic treatment conditions. Next, the present invention will be explained with reference to examples. Example 1 2.2 parts by weight of milk casein and 5 parts by weight of acrylonitrile were dissolved in 43 parts by weight of a 60% zinc chloride aqueous solution, 0.06 parts by weight of ammonium persulfate was added thereto, and polymerization was carried out at 20°C for 2 hours. The polymer conversion rate of acrylonitrile was 99.5%. After degassing the polymer solution thus obtained, it was spun through a spinneret into a 30% by weight zinc chloride coagulation bath at 0°C.
The formed coagulation system is washed with water, and then the system is
16% after stretching 7 times in heated steam at 120℃
It was dried while giving the same shrinkage and was wound up as a single yarn of 2 denier. Separately, the yarn immediately after washing with water was sampled as an undrawn yarn, thoroughly washed under running water, and then air-dried. On the other hand, as a model for a solution containing iron ions, aqueous solutions of ferric chloride were prepared at concentrations of 0.1 to 0.00001 mol, and in 100 c.c. of each of these solutions, the above protein-
1 g each (absolute dry weight) of drawn yarn and undrawn yarn of an acrylonitrile hybrid polymer were added, and after being left at room temperature for 60 minutes, the mixture was separated using a filter, and the resulting liquid was analyzed for iron ion concentration. The results are shown in Table 1. For comparison, commercially available acrylic fibers subjected to scouring treatment and commercially available wool fibers subjected to scouring treatment were similarly subjected to adsorption treatment. The results were entered according to Table 1.

[Table] As is clear from Table 1, the adsorbent of the present invention
It shows strong adsorption power for Fe, which is far superior to commercially available acrylic fibers and commercially available wool fibers. It is also clear that the adsorption power is especially excellent at low concentrations. Example 2 A chromium ion adsorption test was conducted using a protein-acrylonitrile hybrid polymer fiber prepared in the same manner as in Example 1. A standard reagent for chromium ion atomic absorption spectrometry analysis (1000 ppm) was diluted with water to prepare an aqueous solution with a predetermined concentration. Add 1 g (absolute dry weight) of the above protein-acrylonitrile hybrid polymer fiber to 100 c.c. of this liquid.
After the mixture was added and left at room temperature for 60 minutes, it was filtered using a filter, and the filtrate was analyzed for metal ion concentration by atomic absorption spectrometry. The results are summarized in Table 2.

[Table] As is clear from Table 2, the adsorbent of the present invention
It can be seen that it has an extremely excellent adsorption ability for Cr ⁶⁺ . Example 3 Soybean protein was used instead of milk casein in Example 1, and polymerization was carried out according to the recipe of Example 1. The polymer conversion rate of acrylonitrile was 99.0%.
The obtained polymer solution was defoamed in the same manner as in Example 1, and then spun. Fe ⁺⁺⁺ for the obtained undrawn yarn and drawn yarn,
Table 3 shows the results of treating a mixed solution containing 10 ppm each of Cr ⁶⁺ and Cd ⁺⁺ for 60 minutes at room temperature, showing effective adsorption behavior for each ion.

[Table] Example 4 Two types of aqueous solutions containing 10 ppm of uranyl acetate in terms of uranium were prepared using pure water or seawater, and each solution was prepared in the same manner as in Example 1 in 500 c.c. 1 g each (absolute dry weight) of drawn and undrawn milk casein-polyacrylonitrile polymer yarns were added thereto, and the mixture was left at 30° C. for 3 days. Thereafter, the mixture was separated using a filter, and the resulting liquid was analyzed by oxychloroform extraction. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. A metal ion adsorbent comprising a hybrid polymer of protein and vinyl monomer. 2. The metal ion adsorbent according to claim 1, wherein the mixing ratio of protein and vinyl monomer is 10:1 to 1:50 by weight. 3. The metal ion adsorbent according to claim 1 or 2, wherein the vinyl monomer is acrylonitrile.