Volatilization inhibitor and volatilization inhibition method for 1,4-dioxane

Abstract

To provide novel volatilization inhibitors and volatilization inhibition methods for 1,4-dioxane.SOLUTION: A volatilization inhibitor for 1,4-dioxane contains water and a nonionic surfactant.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a volatilization inhibitor for 1,4-dioxane and a method for suppressing volatilization. [Background technology]

[0002] Known routes by which contaminants such as volatile organic compounds (hereinafter referred to as "VOCs") are ingested by humans from soil contaminated by such substances include the exposure route of drinking groundwater that contains contaminants eluted from the contaminated soil, and the exposure route of directly ingesting contaminated soil.

[0003] In recent years, in addition to these, risk assessments have been conducted regarding the exposure route in which pollutants volatilized from contaminated soil are ingested by inhalation. If it were possible to prevent contaminants such as VOCs from evaporating by covering the contaminated soil with soil cover or by providing shielding materials such as sealing materials, it would be possible to reduce the risk of health damage to workers near the contaminated soil or to nearby residents.

[0004] For example, Patent Document 1 discloses a method of adding a surfactant containing a fatty acid ester as a method for suppressing the volatilization of volatile harmful substances such as benzene, toluene, xylene, chlorobenzene, o-dichlorobenzene, trichloroethylene, and tetrachloroethylene. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-37095 A Summary of the Invention [Problem to be solved by the invention]

[0006] 1,4-dioxane is known to be acutely and chronically toxic to humans and other living organisms, and animal tests in which drinking water containing 1,4-dioxane was administered to rats and other animals revealed that it is carcinogenic, and the International Agency for Research on Cancer (IARC) has classified it as Group 2B, which may also be carcinogenic to humans. In Japan, 1,4-dioxane (standard value: 0.05 mg / L) was added to the drinking water quality standards in 2004 and to the environmental water quality standards in 2009.

[0007] Here, 1,4-dioxane is more soluble in water than the above-mentioned volatile organic compounds such as trichloroethylene, tetrachloroethylene, and chlorobenzene, and has completely different properties from the above-mentioned compounds in that it has the same boiling point as water and does not volatilize easily when dissolved in water. Also, unlike heavy metals and pesticides, 1,4-dioxane is highly hydrophilic and has low adsorption to soil particles, and is considered to hardly adsorb or concentrate on solids such as soil. However, due to its highly hydrophilic nature, there is concern that as soil particles contaminated with 1,4-dioxane dry out, 1,4-dioxane will volatilize from the soil along with the water. Furthermore, there is concern that a small amount of 1,4-dioxane will volatilize if the soil contaminated with 1,4-dioxane is excavated and exposed to the atmosphere for a long period of time. Therefore, a method of suppressing volatilization is necessary to prevent health damage caused by inhaling 1,4-dioxane that has volatilized from the soil. On the other hand, 1,4-dioxane has different properties from volatile organic compounds such as trichloroethylene, tetrachloroethylene, and chlorobenzene, for which methods of suppressing evaporation from soil have been developed. In order to suppress the evaporation of 1,4-dioxane from soil, a separate study will be necessary from conventional methods of suppressing evaporation.

[0008] In view of the above circumstances, an object of the present invention is to provide a novel volatilization inhibitor and a method for suppressing volatilization of 1,4-dioxane. [Means for solving the problem]

[0009] As a result of intensive research aimed at solving the above problems, the inventors have discovered that the volatilization of 1,4-dioxane can be effectively suppressed by adding water and a nonionic surfactant to soil containing 1,4-dioxane, and have thus completed the present invention.

[0010] That is, the present invention relates to the following inventions. [1] A volatility inhibitor for 1,4-dioxane containing water and a nonionic surfactant. [2] The volatility inhibitor for 1,4-dioxane according to [1], wherein the HLB value of the nonionic surfactant is 7 to 13. [3] A method for suppressing the volatilization of 1,4-dioxane, comprising adding water and a nonionic surfactant to soil containing 1,4-dioxane. [4] The method for suppressing evaporation of 1,4-dioxane according to [3], wherein the HLB value of the nonionic surfactant is 7 to 13. Effect of the Invention

[0011] According to the present invention, a novel volatilization inhibitor and a novel volatilization inhibitor for 1,4-dioxane can be provided. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a graph showing the concentration (ppm) of 1,4-dioxane contained in gas with a PV of 0.5 when water and each nonionic surfactant were added to the contaminated test soil. [Diagram 2] FIG. 2 is a graph showing the concentration (ppm) of 1,4-dioxane contained in PV3 gas when water and each nonionic surfactant was added to the contaminated test soil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Preferred embodiments of the present invention will be described in detail below, however, the present invention is not limited to the following embodiments.

[0014] [1.1,4-dioxane volatilization inhibitor] The volatility inhibitor for 1,4-dioxane according to this embodiment contains water and a nonionic surfactant.

[0015] [1-1.Wed] The water used in the present embodiment is not particularly limited, and any known and commonly used water can be used. Examples of water include tap water, deionized water, distilled water, and ion-exchanged water. The water content in the volatilization inhibitor of 1,4-dioxane according to this embodiment is not particularly limited, and can be appropriately set according to the concentration of 1,4-dioxane contained in the soil, the type and quality of the soil, the type of nonionic surfactant, etc. The water content is preferably 60 to 99 mass%, more preferably 70 to 98 mass%, and even more preferably 75 to 95 mass%, when the volatilization inhibitor is taken as 100 mass%.

[0016] [1-2. Nonionic surfactants] The nonionic surfactant used in this embodiment is not particularly limited, and any known and commonly used surfactant can be used as long as it has the effect of suppressing the volatilization of 1,4-dioxane. Examples of the nonionic surfactant include ether type, ester type, ether ester type, and nitrogen-containing type. The nonionic surfactant may be used alone or in combination of two or more types.

[0017] Examples of ether-type nonionic surfactants include polyethylene glycols such as PEG-200, PEG-300, PEG-400, and PEG-600; polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, and polyoxyethylene alkyl (C 12 -C 14) ether, polyoxyethylene myristyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tribenzyl phenyl ether, polyoxyethylene-polyoxyalkylene alkyl ethers and other polyoxyethylene-polyoxypropylene alkyl ethers.

[0018] Examples of ester-type and ether-ester-type nonionic surfactants include polyoxyethylene-polyoxypropylene fatty acid (di)esters, such as polyoxyethylene monolaurate, polyoxyethylene monostearate, polyethylene glycol distearate, polyethylene glycol diolate, and polypropylene glycol distearate; sorbitan fatty acid esters, such as sorbitan monolaurate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan trioleate; and fatty acid esters of polyoxyethylene-polyoxypropylene with glycerin and sorbitol, such as polyoxyethylene coconut fatty acid glyceryl, polyoxyethylene hydrogenated castor oil, polyoxyethylene castor oil, polyoxyethylene triisostearate, and polyoxyethylene sorbitol tetraoleate.

[0019] Examples of nitrogen-containing nonionic surfactants include polyoxyethylene laurylamine, polyoxyethylene (coconut) alkylamine, polyoxyethylene tallow alkylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine and other polyoxyethylene-polyoxypropylene amines.

[0020] The nonionic surfactant used in this embodiment preferably has an HLB value of 7 to 13, more preferably 7.5 to 12.8, and even more preferably 7.8 to 12, from the viewpoint of suppressing the volatilization of 1,4-dioxane. Here, HLB is an abbreviation of Hydrophilic-Lipholic Balance, and is used as a value that indicates the degree of affinity to water and oil. In this specification, the value of "HLB" means a value calculated by the Griffin method. When two or more nonionic surfactants are used in combination, it means the weighted average of the HLB values ​​of each nonionic surfactant.

[0021] When the nonionic surfactant used in this embodiment is polyethylene glycol, its average molecular weight is preferably 100-2,000, more preferably 150-1,000, and even more preferably 180-700.

[0022] When the nonionic surfactant used in the present embodiment is a polyoxyethylene fatty acid monoester, a polyoxyethylene fatty acid diester, a polyoxypropylene fatty acid monoester, or a polyoxypropylene fatty acid diester, the HLB value is preferably 6 to 11, more preferably 7 to 10.5, and even more preferably 7.5 to 10.

[0023] When the nonionic surfactant used in this embodiment is a polyoxyethylene alkyl ether, the HLB value is preferably 8-19, more preferably 10-14, and even more preferably 10.6-12.

[0024] The content of the nonionic surfactant in the volatilization inhibitor of 1,4-dioxane according to this embodiment is not particularly limited, and can be appropriately set according to the concentration of 1,4-dioxane contained in the soil, the type of soil, the soil quality, the type of nonionic surfactant, etc. The content of the nonionic surfactant is preferably 1 to 40 mass%, more preferably 2 to 30 mass%, and even more preferably 5 to 25 mass%, when the volatilization inhibitor is taken as 100 mass%.

[0025] [1-3. Mass ratio of water to nonionic surfactant] The mass ratio of water to nonionic surfactant contained in the volatilization inhibitor of 1,4-dioxane according to this embodiment is not particularly limited, and can be appropriately set according to the concentration of 1,4-dioxane contained in the soil, the type of soil, the soil quality, the type of nonionic surfactant used, etc. The mass ratio of water to nonionic surfactant is preferably 1-40:60-99, more preferably 2-30:70-98, and even more preferably 5-25:75-95.

[0026] [2. Methods for suppressing volatilization of 1,4-dioxane] The method for suppressing volatilization of 1,4-dioxane according to this embodiment is characterized in that water and a nonionic surfactant are added to soil containing 1,4-dioxane.

[0027] The method of adding water and a nonionic surfactant to soil containing 1,4-dioxane is not particularly limited, and examples thereof include a method of spraying a mixture of water and a nonionic surfactant on the soil all at once or in multiple batches, or mixing the mixture with the soil. Examples of the spraying method include a manual method using a watering can or bucket, and a mechanical method using a pump, sprinkler, or water truck. Examples of the method of mixing water and a nonionic surfactant with the soil include a method of mixing the mixture with a mixer.

[0028] Adding water and a nonionic surfactant to soil containing 1,4-dioxane can suppress the volatilization of 1,4-dioxane. The mechanism is unclear, but it is thought that 1,4-dioxane is held by the soil particles via the nonionic surfactant, making it difficult to volatilize. In addition, the boiling point of a nonionic surfactant is higher than that of water, so it is possible to suppress the volatilization of 1,4-dioxane for a longer period of time compared to adding only water. EXAMPLES

[0029] [Test example: Evaluation of the effect of nonionic surfactants in suppressing the volatilization of 1,4-dioxane] Water and various surfactants were added to soil containing 1,4-dioxane, and their effect on suppressing the volatilization of 1,4-dioxane was evaluated.

[0030] The soil used was black soil with a water content of 20% (≒ (weight of water / weight of solid) × 100 (%)). 2 ) and 3 mL of 1,4-dioxane reagent (concentration: 2500 ppm) was added to prepare contaminated soil for testing. Next, 2 L / m of each surfactant listed in Table 1 diluted 10-fold with water was added to the contaminated soil on the petri dish. 2 In other words, 14.4 mL of the contaminated soil was added to each of the above-mentioned test soils (Examples 1 to 25). As controls, either nothing was added to the contaminated soil for testing (Comparative Example 1) or 14.4 mL of water was added (Comparative Example 2).

[0031] [Table 1]

[0032] The petri dishes of Examples 1 to 25 and Comparative Examples 1 and 2 prepared above were placed on a stand in a desiccator with a capacity of 3.6 L. The desiccator was covered, and air was pumped through the side opening of the desiccator at 2 L / min, and the gas discharged from the top opening of the desiccator was collected. Gas was collected from the top opening of the desiccator at PV0.5 (0 to 1 min), where half the desiccator's capacity of air is replaced after the start of aeration, and at PV3 (5 to 6 min), where three times the desiccator's capacity of air is replaced.

[0033] The concentration of 1,4-dioxane in the collected gas was analyzed using a gas chromatograph mass spectrometer (GCMS-QP (registered trademark) 2010 Ultra, manufactured by Shimadzu Corporation). The concentration of 1,4-dioxane in the gas of PV0.5 is shown in Figure 1, and the concentration of 1,4-dioxane in the gas of PV3 is shown in Figure 2.

[0034] 1 shows that in Examples 1 to 25, the 1,4-dioxane concentration in the gas with PV0.5 was significantly reduced to about 21 to 45% (when the 1,4-dioxane concentration in Comparative Example 1 was taken as 100%) compared to Comparative Example 1. Also, from Fig. 2, it shows that in Examples 1 to 25, the 1,4-dioxane concentration in the gas with PV3 was reduced to 34 to 77% (when the 1,4-dioxane concentration in Comparative Example 1 was taken as 100%) compared to Comparative Example 1.

[0035] 1 shows that in Examples 1 to 23 and 25, excluding Example 24, the 1,4-dioxane concentration in the gas with PV0.5 was reduced by 47 to 82% (when the 1,4-dioxane concentration in Comparative Example 2 was taken as 100%) compared to Comparative Example 2. Also, from FIG. 2 shows that in Examples 1, 3 to 9, 11 to 22 and 25, excluding Examples 2, 10, 23 and 24, the 1,4-dioxane concentration in the gas with PV3 was reduced by 55 to 97% (when the 1,4-dioxane concentration in Comparative Example 2 was taken as 100%) compared to Comparative Example 2.

[0036] 1 and 2, comparing the polyethylene glycol (PEG-8) diolate of Example 1, the polyoxyethylene monooleate of Example 23, and the polyoxyethylene sorbitol tetraoleate of Example 24, it can be seen that, among the polyoxyethylene fatty acid monoesters and polyoxyethylene fatty acid diesters, those with an HLB value of 7.9 more effectively suppress the volatilization of 1,4-dioxane than those with an HLB value of 11.2 or 11.6.

[0037] Furthermore, from the results of the polyoxyethylene alkyl ethers of Examples 11 and 12 and the polyoxyethylene lauryl ethers of Examples 13 and 15 to 17, it can be seen from Figures 1 and 2 that in the polyoxyethylene alkyl ethers, when the HLB value is about 8.1 to 12, the volatilization of 1,4-dioxane can be more effectively suppressed.

[0038] In addition, it is clear from Figs. 1 and 2 that the polyethylene glycols 200 to 600 of Examples 6 to 9 all effectively suppress the volatilization of 1,4-dioxane.

[0039] From the above, it can be seen that the nonionic surfactants of Examples 1 to 25 have a 1,4-dioxane volatilization suppression effect equal to or greater than that of water, and since nonionic surfactants have a higher boiling point and are less likely to evaporate than water, they can be suitably used as 1,4-dioxane volatilization suppressants.

Claims

1. A volatility inhibitor for 1,4-dioxane containing water and a nonionic surfactant.

2. The volatilization inhibitor for 1,4-dioxane according to claim 1, wherein the HLB value of the nonionic surfactant is 7 to 13.

3. A method for suppressing the volatilization of 1,4-dioxane, comprising adding water and a nonionic surfactant to soil containing 1,4-dioxane.

4. The method for suppressing evaporation of 1,4-dioxane according to claim 3, wherein the HLB value of the nonionic surfactant is 7 to 13.

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