JP5888877B2 - Chemical substance decomposition agent composition and chemical substance decomposition treatment method using the same - Google Patents

Description

  The present invention relates to a chemical substance decomposing agent composition capable of efficiently decomposing a chemical substance when added to soil contaminated with the chemical substance, and a chemical substance decomposing method using the same.

  Conventionally, chemical substances such as organic chlorine compounds have been widely used as cleaning agents in semiconductor factories and cleaning shops (factories), but their use has been refrained in recent years due to their large environmental impact. However, these chemical substances that have already been used are often mixed in soil and groundwater, and this is a major social problem when reusing land. Therefore, attempts have been made to purify such contaminated soil and contaminated water by various means.

  There are known methods for physically removing contaminated soil and contaminated water, and methods for biologically or chemically decomposing pollutants. Physical methods include secondary treatment of removed contaminated soil, etc. There is a drawback that is required. In addition, the method of biologically decomposing pollutants has the advantage of having little impact on the environment, but is difficult to apply to highly degradable compounds such as high-concentration pollutants and organic chlorine compounds. On the other hand, the chemical decomposition method does not require secondary treatment because it is possible to decompose pollutants on the site, and further to high-concentration pollutants and refractory compounds such as organochlorine compounds. Is also possible.

  As a method of chemically decomposing, a method of oxidatively decomposing pollutants using hydrogen peroxide or persulfate is known. As a decomposition method, a method of injecting into the ground is common, but hydrogen peroxide is unstable and decomposes quickly, so when it is injected into the ground, it is immediately decomposed and there is a disadvantage that the range to be purified becomes extremely narrow. . On the other hand, since persulfate is stable, an activator such as a catalyst is required for use as an oxidizing agent. As such a catalyst, it is known to use metal ions such as iron ions, and in order to cope with a wider pH range, or to prevent the iron ions of the catalyst from becoming insoluble substances such as iron oxyhydroxide. Therefore, it is known to use a chelating agent such as citric acid or gluconic acid together (for example, see Patent Documents 1 and 2). In the composition containing the persulfate and the catalyst, the decomposition efficiency and decomposition rate of the oxidative decomposition of the contaminant can be controlled within a certain range by using the chelating agent. In recent years, decomposition treatment of pollutants by a composition containing persulfate has been actively studied.

JP 2010-082600 A JP 2011-020108 A

However, a composition containing a persulfate and a catalyst has an extremely low decomposition efficiency when the amount of the catalyst is small. On the other hand, when the amount of the catalyst is increased, the decomposition efficiency increases, but the persulfate is consumed in a large amount in a short time, and the effect of decomposing the pollutant before the composition containing the persulfate and the catalyst diffuses into the soil. Disappears in a short time, so there is a drawback that only a small range of pollutants in the soil can be decomposed.
Accordingly, an object of the present invention is to provide a chemical substance decomposing agent composition having high chemical substance decomposition efficiency and capable of maintaining the decomposition ability for a long period of time without consuming persulfate in a short time. To do.

  Thus, as a result of intensive studies, the present inventors have found a composition having a high chemical substance decomposition efficiency and maintaining the decomposition ability over a long period of time, and have reached the present invention. That is, this invention is a chemical substance decomposition agent composition characterized by containing persulfate (A), a bivalent or trivalent iron ion (B), and ascorbic acid (C).

  ADVANTAGE OF THE INVENTION According to this invention, the decomposition efficiency of a chemical substance is high, and the chemical substance decomposition agent composition which can maintain decomposition | disassembly capability for a long term, without persulfate being consumed for a short time can be provided.

The chemical substance decomposing agent composition of the present invention is a composition containing three components of persulfate (A), divalent or trivalent iron ion (B) and ascorbic acid (C).
The chemical substance to be decomposed is not limited as long as it is organic, for example, aliphatic hydrocarbon compounds such as hexane and petroleum ether; aromatics such as benzene, toluene, xylene, naphthalene, anthracene, phenanthrene, pyrene and chrysene Petroleum products such as kerosene, light oil, heavy oil, gasoline, light oil, lubricating oil; dichloromethane, chloroform, carbon tetrachloride, bromotrifluoromethane, bromochlorodifluoromethane, dibromodifluoromethane, dibromotetrafluoroethane, tribromo Fluoromethane, tetrachloroethylene, trichloroethylene, 1,1-dichloroethylene, 1,2-dichloroethylene, chloroethylene, hexachloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1-dichloro Tan, 1,2-dichloroethane, 1,2-dichlorotetrafluoroethane, 1,3-dichloropropene, and a 2-chloro-1,3-butadiene. Examples of the halogenated alicyclic compound include 1,2,3,4,5,6-hexachlorocyclohexane, aldodrine, dieldrin, endrin, chlordane, heptachlor. , Mirex, and Toxaphene. Examples of the halogenated aromatic compound include dichlorodiphenyltrichloroethane (DDT), 2,4-dichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, and polychlorinated biphenyls. (PCB), organic halogen compounds such as dioxins, and the like. The chemical substance decomposing agent composition of the present invention can be effectively used for an organic halogen compound known to be hardly decomposable.

  The chemical substance decomposing agent composition of the present invention is used for the purpose of purifying the object mixed with the above chemical substances. Examples of such objects include soil, sludge, factory effluent, domestic effluent, and river water. , Lake water, groundwater, etc.

  Examples of the persulfate of the component (A) used in the chemical substance decomposing agent composition of the present invention include lithium persulfate, sodium persulfate, and potassium persulfate. Among these, sodium persulfate and potassium persulfate are preferable, and sodium persulfate that is economically inexpensive and highly water-soluble is more preferable. The persulfate described above may be used alone or in combination of two or more.

  The component (B) used in the chemical substance decomposer composition of the present invention is a divalent or trivalent iron ion. The ion source of these iron ions is not particularly limited as long as it dissolves or disperses in water, but it is preferable to use an iron salt because of its good solubility in water. Examples of such iron salts include iron (II) chloride, iron (III) chloride, iron (II) perhydrochloride, iron (III) perhydrochloride, iron (II) bromide, iron (III) bromide, and iodide. Iron (II), iron (III) iodide, iron (II) nitrate, iron (III) nitrate, iron (II) thiocyanate, iron (III) thiocyanate, iron (II) acetate, iron (III) oxalate , Ammonium iron (II) sulfate, iron (III) sulfate, potassium iron (III) sulfate, iron (II) sulfate, iron (III) sulfate, sodium ferrocyanide, sodium ferricyanide, potassium ferrocyanide, potassium ferricyanide, ferrocyanide Ammonium chloride, ammonium ferricyanide and the like, and from the viewpoint of the decomposition rate and economic efficiency of organic substances, iron (II) chloride, iron (III) chloride, iron (II) nitrate, Iron (III) acid, iron (II) sulfate, and iron (III) sulfate are preferable, iron chloride (II), iron (II) nitrate, and iron (II) sulfate are more preferable, and iron (II) chloride and iron sulfate ( II) is most preferred. These iron salts may be anhydrous salts or hydrates, and may be appropriately selected in consideration of ease of dissolution or dispersion in water. In the present invention, the hydrate refers to a salt having water of crystallization. For example, iron (II) sulfate is monohydrate, tetrahydrate, pentahydrate and heptahydrate in addition to anhydrous salts. Things are known. The above iron ion source may be used alone or in combination of two or more.

  The component (C) used in the chemical substance decomposer composition of the present invention is ascorbic acid. Ascorbic acid has two optical isomers, L-form and D-form, but L-ascorbic acid is preferred because it is highly safe and inexpensive. In addition, the (B) component and the (C) component may be combined to form, for example, ascorbic acid iron salt.

  Although the compounding ratio of the component (A), the component (B) and the component (C) used in the chemical substance decomposing agent composition of the present invention is not particularly defined, the component (A) is used because it efficiently decomposes the chemical substance. The component (B) is added in an amount of 0.1 to 1 mol, preferably 0.2 to 0.8 mol, more preferably 0.3 to 0.7 mol, and the component (C) is added to 0 mol. 0.005 to 0.1 mol, preferably 0.01 to 0.05 mol, more preferably 0.01 to 0.03 mol. If the amount of the component (B) is less than 0.1 mol, the decomposition of the chemical substance may not proceed. If the amount exceeds 1 mol, the component (A) is consumed in a short time and the sustainability is impaired. You may not get the appropriate effect. Further, if the amount of the component (C) is less than 0.005 mol, the decomposition of the chemical substance may not proceed, and if the amount exceeds 0.1 mol, the component (A) may be consumed in a short time and the sustainability may be impaired. .

The chemical substance decomposition method of the present invention comprises contacting the chemical substance decomposition agent composition of the present invention (hereinafter referred to as “the present drug”) with soil or water contaminated with a chemical substance, and decomposing the chemical substance. It is a method to do.
When purifying contaminated water such as industrial wastewater and groundwater contaminated with chemical substances, add this chemical to the contaminated water, and then mix by stirring. The drug is preferably in the form of an aqueous solution because it is quickly dispersed in the contaminated water after addition. The addition amount of this drug may be appropriately determined depending on the type and amount of the chemical substance. Specifically, the persulfate as component (A) in this drug is 5 to 50 mol per 1 mol of the chemical substance. It is preferable to add so that it may become, 8-30 mol is more preferable, and 10-20 mol is still more preferable. When the amount of persulfate is less than 5 mol, the decomposition of the chemical substance may not be completed completely, and when it exceeds 50 mol, the effect corresponding to the addition amount may not be obtained. In addition, even if the addition amount of persulfate is less than 5 mol, it is possible to decompose the chemical substance by additionally adding the necessary amount of the drug thereafter. After the addition of this drug, stirring may be continued or left as long as the additive is uniformly dispersed. Furthermore, the polluted water is periodically sampled and the pollutant is monitored, and the decomposition process ends when the concentration of the chemical substance reaches a target value or less. If the concentration of the chemical substance does not reach the target value or less, a certain amount of the drug may be added to the contaminated water.

  Next, the case where the soil contaminated with the chemical substance is purified will be described. In order to purify the contaminated soil, the contaminated soil may be dug up, and water may be added to the soil to form a slurry, followed by decomposition treatment. Alternatively, the drug is directly injected into the contaminated soil for decomposition. It may be processed. The purification method using slurry has problems such as the cost of purification due to the need for excavation and soil agitation, and the need for countermeasures for soil weakening due to soil particle structural changes and increased porosity due to soil slurrying. is there. Therefore, as a purification method for contaminated soil, it is preferable to inject this drug directly into the soil from the viewpoint of purification cost and ground stability. In addition, when inject | pouring this chemical | medical agent directly into soil, you may inject | pour each component which comprises this chemical | medical agent separately into soil.

The drug to be injected into the soil is preferably in the form of an aqueous solution because it easily spreads in the soil after the injection. Specifically, the drug is prepared so that the persulfate as the component (A) is an aqueous solution of 1 to 20% by mass. Aqueous solution of this drug so that persulfate as component (A) in this drug diluted with water is 0.5-50 kg with respect to 1 m ^{3 of} soil to be purified by diluting the drug with water Is preferably added, more preferably 1 to 40 kg, and still more preferably 2 to 20 kg. If the persulfate is less than 0.5 kg, the decomposition rate of the chemical substance may be slow, or the decomposition may not be completed completely. If it exceeds 50 kg, the environment may be adversely affected, or the effect commensurate with the amount added May not be obtained. Moreover, it is also possible to inject | pour into the soil each component which comprises this chemical | medical agent separately, In this case, the density | concentration of the sum total of the solution A of 1-20 mass% aqueous solution of persulfate, and an iron ion and ascorbic acid is A solution B of 0.05 to 30% by mass aqueous solution is prepared, and the solution A and the solution B may be separately poured into the soil. However, in order to efficiently decompose the chemical substance, the solution B is first and then the solution. It is preferable to inject into the soil in the order of A. However, in the case of injecting separately, since it is necessary to adjust and inject so that the ratio of each component falls within the scope of the present invention, a method of directly injecting the present drug that does not require such adjustment is preferable.

  When inject | pouring this chemical | medical agent into soil, the well for injection | pouring which reaches the depth of contamination is installed, for example at intervals of about 1 to 20 m, preferably about 1.5 to 5 m. In order to promote the diffusion of the drug, it is preferable to install a well for pumping water and inject the drug used for the decomposition treatment method of the present invention while pumping up groundwater. An observation well should be installed between the injection wells, periodically sampling groundwater or soil, monitoring the decomposition rate of chemical substances, and stopping the injection when the concentration of chemical substances falls below the target value.

Hereinafter, the present invention will be specifically described by way of examples.
In accordance with the following test method, a TCE decomposition test was conducted using a chemical on a model-contaminated soil containing ground and dried soil and trichlorethylene (TCE).

<Test method>
In a 120 ml light-shielding vial, 10 g of ground and dried soil and 50 g of an aqueous solution having a TCE of 200 mg / l were placed. Each component is blended in the molar ratios described in Table 1 and Table 2, and diluted with water so that the concentration of persulfate is 6000 mg / l. Each drug (Examples 1-8 and Comparative Examples 1-7) Was prepared. 50 g of these chemicals were added to each of the light-shielding vials containing the soil and the TCE aqueous solution. Thereafter, the light-shielding vial was shaken up and down to make the contents uniform, and left in a constant temperature bath at 25 ° C. The TCE concentration at this point (before decomposition) is 100 mg / l.
After standing for 2 days, 10 ml of the supernatant water in the light-shielding vial was collected, and the residual TCE amount and the residual persulfate amount were measured using gas chromatography. The conditions for gas chromatography are as follows. In addition, about the comparative example 2 and the comparative example 3, decomposition | disassembly was continued until the amount of residual persulfate became 0% (7 days still standing). The data after 2 days of standing are shown in Tables 1 and 2, and the data of Comparative Example 2 and Comparative Example 3 after 7 days of standing are shown in Table 3.

<Gas chromatography conditions>
Equipment: GC-2014 (manufactured by Shimadzu Corporation)
Column: InterCap1 (inner diameter 0.25 mm, length 30 m, film thickness 1.5 μm; manufactured by GL Science)
Column temperature: 40 ° C to 200 ° C (5 ° C / min)
Injection temperature: 200 ° C
Detector temperature: 250 ° C
Injection volume: 0.1ml
Split ratio: 1:50

  In the following Tables 1 and 2, the numbers of the respective components are molar ratios, and are the number of moles of other compounds added relative to 1 mole of sodium persulfate or potassium persulfate.

  From the above results, it can be seen that all of the drugs of the Examples have the TCE concentration lowered to less than 1 mg / l, and the degradation ability of the drug of the present invention is high. Further, in the examples, a certain amount or more of the persulfate remains, and it can be seen that the decomposition ability is maintained even after 2 days. On the other hand, none of the drugs of Comparative Examples could reduce the TCE concentration to less than 1 mg / l. In the comparative example, the TCE concentration did not reach less than 1 mg / l even when the test was continued until the remaining amount of persulfate reached 0%. Therefore, between the drug of the present invention and the drug of the comparative example, It was confirmed that there was a big difference in decomposition ability.

Claims (4)

  A chemical substance decomposing agent composition comprising a persulfate (A), a divalent or trivalent iron ion (B) and ascorbic acid (C).   It is an aqueous solution containing 0.1 to 1 mol of divalent or trivalent iron ion (B) and 0.005 to 0.1 mol of ascorbic acid (C) with respect to 1 mol of persulfate (A). The chemical substance decomposer composition according to claim 1.   The persulfate (A) is sodium persulfate or potassium persulfate, the ion source of divalent or trivalent iron ions (B) is iron sulfate, and ascorbic acid (C) is L-ascorbic acid. The chemical substance decomposing agent composition according to claim 1 or 2.   The chemical substance decomposition agent composition according to any one of claims 1 to 3, wherein the chemical substance is decomposed by bringing the chemical substance decomposition agent composition into contact with soil or water contaminated with the chemical substance. Processing method.