JP5437589B2 - Heavy metal insolubilizing agent and soil purification method using the same. - Google Patents

Description

  The present invention relates to a heavy metal insolubilizer and a soil purification method using the same, and in particular, a heavy metal insolubilizer capable of solidifying and detoxifying the heavy metal present in soil contaminated with heavy metals, and using the same. The present invention relates to a soil purification method.

  Many heavy metals such as hexavalent chromium are toxic to living organisms, and are bioaccumulative and difficult to discharge. In recent years, soil contamination by such heavy metals has become serious, and from the viewpoint of environmental conservation, methods for purifying harmful heavy metals present in soil have been studied.

  There are (1) a method for removing contaminated soil from the contaminated area and (2) a method for preventing the diffusion of heavy metals from the contaminated soil, but the former method is enormous. In addition to being expensive, there was a drawback that it was difficult to manage the soil that was carried out.

  On the other hand, in the latter method, the contaminated soil is chemically treated by chemical introduction, that is, chemicals are introduced to prevent heavy metals from eluting and diffusing from the contaminated soil. To fix heavy metals in the soil in the chelate using a metal scavenger such as an agent, to utilize the reduction action of sulfur, to neutralize the pH of the soil by adding lime, and to deactivate the heavy metals Alternatively, a method of making a heavy metal hardly soluble by adding a phosphate fertilizer is known, but the effect is insufficient.

  Therefore, development of a new heavy metal insolubilizer capable of more completely detoxifying contaminated soil has been desired.

  On the other hand, the ground injection material using colloidal silica has been used for the purpose of conventional construction method, liquefaction prevention, etc., but colloidal silica has been used from the viewpoint of detoxification of soil contaminated with heavy metals. It was never done.

Accordingly, a first object of the present invention is to provide a heavy metal insolubilizing agent capable of detoxifying the heavy metal present in soil contaminated with heavy metal at low cost and efficiency.
The second object of the present invention is to provide a soil purification method capable of treating soil contaminated with heavy metals at a low cost, preventing environmental destruction, and increasing the value of the land.

  As a result of intensive studies to achieve the above object, the present inventor has found that heavy metals can be easily insolubilized by using a combination of colloidal silica and a specific chelating agent. Through application, it was found that soil contaminated with heavy metals can be made inexpensive and completely detoxified, and the present invention has been achieved.

That is, the present invention includes (A) colloidal silica , ( B) at least one chelating agent selected from tannic acid, amines, and diphenols , and (C) chloride, sodium aluminate, and phosphoric acids. A heavy metal insolubilizing agent comprising at least one gelling agent selected from the above , and a soil purification method using the heavy metal insolubilizing agent. In addition, it is particularly preferable to use tannic acid as the chelating agent. Moreover, it is preferable that the usage-amount of the chelating agent of the said (B) component is 0.01-10 mass parts with respect to 100 mass parts of colloidal silica of the said (A) component. Definitive to the present invention (C) the amount of the components of the gelling agent is preferably from 0.1 to 10 parts by mass with respect to the (A) colloidal silica 100 parts by weight of the component.

  Since the heavy metal insolubilizing agent of the present invention can easily solidify heavy metals in the soil and thereby easily detoxify the soil contaminated by heavy metals, the soil purification method of the present invention is extremely Useful.

  Hereinafter, the heavy metal insolubilizing agent of the present invention and the soil purification method using the same will be described in detail.

  As the (A) component colloidal silica used in the present invention, general-purpose colloidal silica can be used, and aqueous colloidal silica is particularly suitable. Examples of commercially available aqueous colloidal silica include Adelite AT-30 (manufactured by ADEKA Corporation; average particle size 12.5 ± 2.5 nm, silica solid content 30% by mass), Adelite AT-30S (Co., Ltd.) Made by ADEKA; average particle size 8.5 ± 1.5 nm, silica solid content 30% by mass), Adelite AT-40 (manufactured by ADEKA Corporation; average particle size 17.5 ± 2.5 nm, silica solid content 40% by mass) Adelite AT-50 (manufactured by ADEKA Corporation; average particle size 25 ± 5 nm, silica solid content 50% by mass), Adelite AT-30A (manufactured by ADEKA Corporation; average particle size 12.5 ± 2.5 nm, silica solid content) 30% by mass), Adelite AT-20 (manufactured by ADEKA Corporation; average particle size 12.5 ± 2.5 nm, silica solid content 20% by mass) and the like. .

  Examples of the chelating agent for component (B) used in the present invention include tannic acid, amines, diphenols and the like. In the present invention, tannic acid exhibits an excellent effect among them, and is preferably used. used.

  In the heavy metal insolubilizing agent of the present invention, it is preferable to use 0.01 to 10 parts by mass of component (B) with respect to 100 parts by mass of component (A), and particularly 0.1 to 5 parts by mass in combination. Is preferred. When this range is exceeded, the effect of insolubilizing heavy metals may be insufficient.

The component (C) gelling agent used in the present invention is usually selected from at least one selected from chlorides such as potassium chloride, sodium aluminate, and phosphoric acids.

The amount of the gelling agent used is 0.1 to 10 parts by mass with respect to 100 parts by mass of the component (A) colloidal silica.

  In the present invention, if necessary, water can be added as appropriate, and the amount used thereof is not particularly limited, but from the viewpoint of handling, it is 10 to 100 parts by mass of the (A) component colloidal silica. It is preferably 1000 parts by mass.

Heavy metal insolubilizing agent of the present invention, (A) is the component colloidal silica, (B) a chelating agent is a component, and a gelling agent as essential components as the component (C) were charged water as needed It can manufacture easily by mixing.

  In the soil purification method of the present invention, the heavy metal insolubilizer of the present invention is brought into contact with the heavy metal in the contaminated soil in the soil contaminated with heavy metal to solidify and detoxify the heavy metal.

  The method for bringing the heavy metal insolubilizing agent of the present invention into contact with the heavy metal in the contaminated soil is not particularly limited. For example, it can be carried out using a general-purpose ground injection method, and when a wide area is targeted, it may be spread using a spreader. Moreover, you may mix with a mixer etc. if it is only surface layer vicinity. When spraying, it is reasonable to use an aqueous solution containing a heavy metal insolubilizing agent.

  Hereinafter, although the heavy metal insolubilizer of this invention and the soil purification method using the same are demonstrated in detail according to an Example, this invention is not limited by these.

  A simulated contaminated soil contaminated with hexavalent chromium was prepared by adding and mixing 0.1 g of potassium dichromate with 1000 g of Toyoura standard sand. The amount of hexavalent chromium eluted from this contaminated soil was measured and found to be 4.3 mg / l.

As heavy metal solidifying and insolubilizing agents, Adelite AT-30 (30% by weight colloidal silica solution) from ADEKA, potassium chloride, and TANNEX from AJINOMOTO-TAKARA
EX-20 (tannic acid-based chelating agent) was blended, solidification due to gelation was confirmed, and the elution amount of hexavalent chromium was measured. Confirmation of the solidification / insolubilization was carried out by preparing a sand gel using a solidification / insolubilization agent prepared from the contaminated sand according to the formulation shown in the following recipe, and filling the voids of the sand 100%. The composition and each result are as shown in Table 1.

  As is clear from the results in Table 1, it was confirmed that the solidified / insolubilized chemical solution of the present invention gelled easily when mixed with the contaminated sand and solidified the contaminated sand. Further, when the elution amount of hexavalent chromium in the sand gel was measured, in the comparative example in which the tannic acid-based chelating agent was not added, hexavalent chromium was detected at 2.8 mg / l, whereas in the examples of the present invention, it was not detected. As a result, solidification and insolubilization of heavy metals were confirmed.

  The heavy metal insolubilizing agent of the present invention is extremely useful because it can easily solidify heavy metals in the soil, thereby easily detoxifying the soil contaminated with heavy metals. In addition, the soil purification method of the present invention is less expensive than conventional methods and can completely prevent contamination by heavy metals, so that it can sufficiently cope with a wide contamination range, thereby restoring the value of the land. It is also very useful industrially.

Claims (6)

(A) at least one chelating agent selected from colloidal silica , ( B) tannic acid, amines, diphenols , and (C) at least selected from chloride, sodium aluminate, phosphoric acids A heavy metal insolubilizing agent comprising one type of gelling agent.   The heavy metal insolubilizing agent according to claim 1, wherein at least tannic acid is contained as a chelating agent as component (B).   The heavy metal insolubilizing agent according to claim 1 or 2, wherein an amount of the chelating agent used as the component (B) is 0.01 to 10 parts by mass with respect to 100 parts by mass of the colloidal silica as the component (A). The heavy metal insolubilizing agent described in any one of Claims 1-3 whose usage-amount of the said gelatinizer is 0.1-10 mass parts with respect to 100 mass parts of colloidal silica of the said (A) component . A soil remediation method comprising bringing the heavy metal in the soil contaminated with heavy metal into contact with the heavy metal insolubilizer according to any one of claims 1 to 4, and solidifying the heavy metal to render it harmless . The soil purification method according to claim 5, wherein the contact between the heavy metal insolubilizer and the heavy metal is performed by spraying an aqueous solution containing a heavy metal insolubilizer on the contaminated soil surface .