Soil Cleaning Agent

Abstract

To provide a detergent for soil that can efficiently clean oils from oil-contaminated soil.SOLUTION: A detergent for soil, containing a component (A) represented by a formula (a-1), and a component (B) represented by a formula (b-1) or (b-2), wherein a mass ratio (A) / (B) is 50 / 50 or more and 95 / 5 or less, and the components (A) and (B) are used in an amount in total of 0.5 mass% or more. R1a-CH(R2a)-O-(EO)x1-H ... (a-1), R1b-CH(R2b)-O-(EO)x2-H ... (b-1), and R3b-CH(R4b)-O-(EO)x3(PO)y1-H ...(b-2) (wherein R1a-2a and R1b-4b represent an alkyl group, the sum of carbons of R in each formula is 9 or more and 15 or less, a difference between carbons of R1a and R2a is 0 or more and 3 or less, the number of carbons of R1b-4b is 1 or more and 14 or less, x1 is 1 or more and 6 or less, x2 and x3 are more than 6 but less than 17, and y1 is more than 0 but less than 6).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a soil washing agent and a method for treating soil. [Background technology]

[0002] In recent years, there have been many cases of serious soil contamination in a variety of situations, including illegal dumping of industrial waste, waste disposal in factories, and accidental leakage of hazardous substances from final disposal sites, as well as accidental or long-term leakage of various oils at the sites or former sites of petroleum refineries, gas stations, chemical plants, etc.

[0003] Conventionally, methods for remediating such contaminated soil have included incineration after excavation, solidification / fixation, containment, bioremediation, soil washing, and other techniques, but among these, technologies that remove contaminants from the soil and purify it are becoming mainstream.

[0004] In particular, compared to other methods, the soil washing method is highly versatile because it can purify different types of contaminants (oil, heavy metals), can be used as a pretreatment process for bioremediation, etc., can treat a large amount of contaminated soil, and has the potential to reduce overall purification costs.

[0005] Patent Documents 1 and 2 disclose soil washing agent compositions containing polyoxyethylene secondary alkyl ether and an organic amine compound. Patent Document 3 discloses a soil washing agent containing a nonionic surfactant and a polycarboxylic acid polymer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-132905 A [Patent Document 2] JP 2011-144223 A [Patent Document 3] JP 2003-119495 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a soil washing agent having excellent detergency capable of efficiently washing oil from soil contaminated with oil. [Means for solving the problem]

[0008] The present invention relates to an oil-based composition comprising: (A) a nonionic surfactant represented by the following general formula (a-1) (hereinafter referred to as component (A)); and (B) a nonionic surfactant represented by the following general formula (b-1) or (b-2) (hereinafter referred to as component (B)), The mass ratio of the component (A) to the component (B), (A) / (B), is 95 / 5 or less and 50 / 50 or more, When used, the total concentration of components (A) and (B) is 0.5% by mass or more. This relates to soil cleaning agents. R 1a -CH(R 2a )-O-(EO) x1 -H (a-1) (In the formula, R 1a , R 2a are each an alkyl group, and R 1a and R 2a The sum of the carbon numbers of R is 9 to 15. 1a and R 2a The difference in the number of carbon atoms between these is 0 or more and 3 or less, EO represents an oxyethylene group, x1 represents the average number of moles of oxyethylene groups added, and x1 is a number of 1 or more and 6 or less. R 1b -CH(R 2b )-O-(EO) x2 -H (b-1) R 3b -CH(R 4b )-O-(EO) x3 (PO) y1 -H (b-2) (In formulas (b-1) and (b-2), R 1b , R 2b, R 3b and R 4b Each represents an alkyl group having 1 to 14 carbon atoms, and R 1b and R 2b The sum of the carbon numbers and R 3b and R 4b The sum of the carbon numbers of each of the above is 9 or more and 15 or less, EO represents an oxyethylene group, PO represents an oxypropylene group, x2 and x3 represent the average number of moles of oxyethylene groups added, each being a number greater than 6 and not greater than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the condition greater than 0 and less than 6, (EO) x3 (PO) y1 can be block or random.)

[0009] The present invention also provides a method for treating soil, comprising contacting soil with a treatment solution containing the soil washing agent, the method comprising the steps of: The total concentration of the (A) component and the (B) component in the treatment liquid is 0.5% by mass or more. This relates to a method for treating soil. Effect of the Invention

[0010] According to the present invention, it is possible to provide a soil washing agent having excellent detergency capable of efficiently washing oil from soil contaminated with oil. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The inventors have discovered that a soil cleaner in which the alkyl structure of the nonionic surfactant is branched rather than linear and which contains two types of nonionic surfactants with different average added mole numbers of oxyethylene groups (EO) in a specified ratio has excellent cleaning power. The reason why such an effect occurs is not entirely clear, but is presumed to be as follows. It is believed that nonionic surfactants with branched alkyl structures are more compatible with oils in soil than linear structures with bulky structures, and that among the compatible branched structures, nonionic surfactants with a low average number of EO added moles have a modifying effect that acts on oils in soil to modify the soil into dirt that is easier to remove, while nonionic surfactants with a high average number of EO added moles have an emulsification-promoting effect that diffuses oils in soil into water. It is believed that by including a nonionic surfactant with a branched structure but a low average number of EO added moles and a nonionic surfactant with a high average number of EO added moles in a specified ratio, the detergency of the soil cleaner will be improved by the synergistic effect of the modifying effect and the emulsification-promoting effect.

[0012] The soil washing agent of the present invention contains (A) a nonionic surfactant represented by the following general formula (a-1) (hereinafter referred to as component (A)) and (B) a nonionic surfactant represented by the following general formula (b-1) or (b-2) (hereinafter referred to as component (B)). The soil washing agent of the present invention may be a soil washing agent comprising a combination of the components (A) and (B).

[0013] The component (A) is a compound represented by the general formula (a-1). As the component (A), one compound selected from the compounds represented by the general formula (a-1) can be used alone, or two or more compounds can be used in combination. R 1a -CH(R 2a )-O-(EO) x1 -H (a-1) (In the formula, R 1a , R 2a are each an alkyl group, and R 1a and R 2a The sum of the carbon numbers of R is 9 to 15. 1a and R 2a The difference in the number of carbon atoms between these is 0 or more and 3 or less, EO represents an oxyethylene group, x1 represents the average number of moles of oxyethylene groups added, and x1 is a number of 1 or more and 6 or less.

[0014] R 1a and R 2aFrom the viewpoint of affinity with oils in the soil, the sum of the carbon numbers is 9 or more, more preferably 10 or more, even more preferably 11 or more, and even more preferably 12 or more, and from the viewpoint of stability in the detergent, it is 15 or less, more preferably 14 or less.

[0015] R 1a and R 2a From the viewpoint of alkyl chain balance that facilitates affinity with oils in soil, the difference in the number of carbon atoms is 0 or more and 3 or less, preferably 0 or more and 2 or less, more preferably 0 or 1, and even more preferably 0.

[0016] The average number of moles of oxyethylene groups added x1 is 1 or more, preferably 3 or more, more preferably 4 or more, and 6 or less, preferably 5 or less, from the viewpoint of affinity with oils in the soil.

[0017] As the component (A), an alcohol alkoxylate is preferred, and a branched chain alcohol ethoxylate is more preferred.

[0018] In the present invention, components (A) having an HLB value of 7 or more and 11 or less can be preferably used from the viewpoint of compatibility with oils in the soil. Here, the HLB value is based on the Griffin method (HLB=20×sum of formula weights of hydrophilic parts / molecular weight). Hereinafter, unless otherwise specified, the HLB of a compound is based on the Griffin method. Examples of such components (A) include a 3-mol adduct of branched secondary alcohol ethoxylate (HLB=7.9) and a 5-mol adduct of branched secondary alcohol ethoxylate (HLB=10.5).

[0019] The component (B) is a compound represented by the following general formula (b-1) or (b-2): The component (B) may be a single compound selected from the compounds represented by general formula (b-1) or (b-2), or a combination of two or more compounds. R 1b -CH(R 2b )-O-(EO) x2 -H (b-1) R 3b -CH(R 4b )-O-(EO) x3 (PO) y1 -H (b-2) (In formulas (b-1) and (b-2), R 1b , R 2b , R 3b and R 4b Each represents an alkyl group having 1 to 14 carbon atoms, and R 1b and R 2b The sum of the carbon numbers and R 3b and R 4b The sum of the carbon numbers of each of the above is 9 or more and 15 or less, EO represents an oxyethylene group, PO represents an oxypropylene group, x2 and x3 represent the average number of moles of oxyethylene groups added, each being a number greater than 6 and not greater than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the range of greater than 0 and less than 6, (EO) x3 (PO) y1 can be block or random.)

[0020] R 1b , R 2b , R 3b and R 4b From the viewpoint of the emulsification-promoting effect of diffusing oils in soil into water, the carbon number of each is 1 or more, preferably 3 or more, and more preferably 5 or more, and from the viewpoint of preventing redeposition of removed oils on the soil, the carbon number of each is 14 or less, preferably 10 or less, more preferably 7 or less, and even more preferably 6 or 7.

[0021] R 1b and R 2b The sum of the carbon numbers of R 3b and R 4b From the viewpoint of the emulsification-promoting effect of diffusing oils in the soil into water, the sum of the carbon numbers of each is 9 or more, preferably 10 or more, more preferably 11 or more, and even more preferably 12 or more, and from the viewpoint of preventing the removed oils from re-adhering to the soil, the sum of the carbon numbers of each is 15 or less, preferably 14 or less.

[0022] The average added mole numbers x2 and x3 of oxyethylene groups are each more than 6, and preferably 7 or more, from the viewpoint of an emulsification-promoting action for diffusing oils in soil into water, and each is 17 or less, and preferably 13 or less, and more preferably 9 or less, from the viewpoint of preventing redeposition of removed oils on soil.

[0023] The average added mole number y1 of oxypropylene groups is more than 0, preferably 2 or more, more preferably 3 or more, from the viewpoint of the emulsification-promoting effect of diffusing oils in the soil into water, and is less than 6, preferably 5 or less, from the viewpoint of preventing the removed oils from re-adhering to the soil.

[0024] As the component (B), an alcohol alkoxylate is preferred, and a branched chain alcohol alkoxylate is more preferred.

[0025] In the present invention, components (B) having an HLB value of 7 or more and less than 16 can be preferably used from the viewpoint of the emulsification promoting action of diffusing oils in soil into water. Here, the HLB value is based on the Griffin method. Examples of such components (B) include branched secondary alcohol ethoxylate 9 mol adduct (HLB=13.3), branched secondary alcohol alkoxylate (ethylene oxide: 7 mol, propylene oxide: 4.5 mol adduct) (HLB=8.0), etc.

[0026] The soil washing agent of the present invention may contain one or more copolymers selected from (C) copolymers of maleic acid and one selected from olefins having from 4 to 8 carbon atoms (hereinafter referred to as component (C)). Component (C) may contain monomers other than the olefin and maleic acid.

[0027] From the standpoint of the formulation required to form a concentrated product, component (C) is more preferably a diisobutylene / maleic acid copolymer.

[0028] The weight average molecular weight of component (C) is preferably 5,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more from the viewpoint of preventing redeposition of peeled oils and assisting the cleaning power of the nonionic surfactant, and is preferably 30,000 or less, more preferably 28,000 or less, and even more preferably 26,000 or less from the viewpoint of formulation. This weight average molecular weight is measured in terms of polyethylene glycol by gel permeation chromatography.

[0029] The weight average molecular weight of the component (C) can be measured by the following method. Standard material: Standard polyethylene oxide manufactured by Tosoh Corporation Standard polyethylene glycol manufactured by GL Sciences Column: Tosoh G4000PWXL+G2500PWXL Two-piece Detection: RI ·Flow rate: 1.0mL / min. ·Injection volume: 200μL ·Temperature: 40℃ Eluent: 0.2M phosphate buffer / acetonitrile = 70 / 30 (volume ratio)

[0030] Component (C) works to loosen clumps of soil and prevent the reattachment of removed oil, while also enhancing the oil-removing and emulsifying effects of the nonionic surfactant. Component (C) can be a copolymer or a salt thereof composed of 10 mol % to 90 mol % of maleic acid monomer. In particular, from the standpoint of preventing reattachment of oil and emulsifying effect, it is preferable that 30 mol % to 70 mol % of the total monomer is maleic acid.

[0031] The molar ratio of olefin having 4 to 8 carbon atoms (preferably diisobutylene) / maleic acid in component (C) is preferably 2 / 8 to 8 / 2, more preferably 3 / 7 to 7 / 3, and even more preferably 4 / 6 to 6 / 4.

[0032] The soil washing agent of the present invention may contain water. The remainder of the soil washing agent of the present invention, excluding the components (A), (B) and (C), may be water.

[0033] From the viewpoints of cleaning performance and reducing the amount of cleaning solution required for cleaning, the soil cleaner of the present invention is used in an amount such that the total content of components (A) and (B) in the soil cleaner is 0.5% by mass or more, preferably 0.8% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more, and from the viewpoints of cleaning performance and not increasing the cost of the cleaner, the soil cleaner is used in an amount such that the total content of components (A) and (B) in the soil cleaner is 0.5% by mass or more, more preferably 0.8% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more. From the viewpoints of cleaning performance and not increasing the cost of the cleaner, the soil cleaner is used in an amount such that the total content of components (A) and (B) in the soil cleaner is 100% by mass or less, more preferably 70% by mass or less, even more preferably 50% by mass or less, even more preferably 30% by mass or less, even more preferably 15% by mass or less, even more preferably 12% by mass or less, even more preferably 10.0% by mass or less, even more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0034] In addition, the soil cleaner of the present invention has a total content of components (A) and (B) of preferably 30% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more in terms of transportation costs to the site, and from the viewpoints of transparent uniform mixing and long-term storage stability, the total content is preferably 100% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, even more preferably 85% by mass or less, and even more preferably 80% by mass or less. The total content of components (A) and (B) may be the total content of the soil cleaner of the present invention when formulated.

[0035] The mass ratio (A) / (B) of the content of the component (A) to the content of the component (B) is 95 / 5 or less, preferably 90 / 10 or less, and more preferably 85 / 15 or less, from the viewpoint of enhancing the emulsification-promoting effect of diffusing oils in the soil into water, and is 50 / 50 or more, preferably 60 / 40 or more, and more preferably 75 / 25 or more, from the viewpoint of enhancing affinity with oils in the soil.

[0036] Among the soil washing agents of the present invention, those having an HLB value based on the combined ratio of components (A) and (B), i.e., a weighted average of the HLB values ​​of component (A) and (B) of 9.5 or more and less than 12.0, can be preferably used from the viewpoint of efficient oil removal from soil contaminated with oil. The HLB value based on the combined ratio of components (A) and (B) (weighted average of HLB values) is the sum of the product of the content (mass) of component (A) and the HLB value of component (A) according to the Griffin method and the product of the content (mass) of component (B) and the HLB value of component (B) according to the Griffin method, divided by the total content (mass) of components (A) and (B).

[0037] When the soil cleaner of the present invention contains component (C), from the viewpoints of preventing redeposition of peeled oils and of assisting the cleaning power of the nonionic surfactant, the content of component (C) in the soil cleaner at the time of use is preferably 0.03 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.07 mass% or more; and from the viewpoint of reducing the cost of the cleaner, it is preferably 0.3 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less.

[0038] When the soil washing agent of the present invention contains component (C), from the viewpoint of the cleaning power due to the combined effect of components (A) and (B) with component (C) and their emulsifying power, the mass ratio (A+B) / C of the total content of components (A) and (B) to the content of component (C) is preferably 7.5 or more, more preferably 15 or more, and is preferably 30 or less, more preferably 19 or less.

[0039] The pH of the soil washing agent of the present invention at 20°C is preferably 6 or more, more preferably 6.5 or more, and is preferably 8 or less, more preferably 7.5 or less, from the viewpoint of preventing elution of heavy metals and other contaminants from soil.

[0040] From the viewpoint of elution of heavy metals and the like assumed to be complex contaminants from soil, the pH of the soil washing agent of the present invention when used is preferably 6 or more, more preferably 6.5 or more, and is preferably 8 or less, more preferably 7.5 or less. The pH of the soil washing agent of the present invention when used may be the pH at the temperature during use.

[0041] The soil washing agent of the present invention may contain, as optional components, surfactants other than the components (A) and (B), antifoaming agents, one-component agents, preservatives, and the like.

[0042] Examples of surfactants other than the components (A) and (B) include anionic surfactants.

[0043] From the viewpoint of cleaning performance, the soil cleaner of the present invention preferably has a total content (mass%) of components (A) and (B) in the entire surfactant of 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and preferably 100 mass% or less. The soil cleaner of the present invention may be a soil cleaner in which the total content of components (A) and (B) in the entire surfactant is 100 mass%, i.e., the surfactant is composed of components (A) and (B).

[0044] The present invention provides a method for producing a soil cleaning agent, comprising the step of blending (A) a nonionic surfactant represented by general formula (a-1) and (B) a nonionic surfactant represented by general formula (b-1) or (b-2) in a mass ratio of component (A) to component (B), (A) / (B), of 95 / 5 or less and 50 / 50 or more. R 1a -CH(R 2a )-O-(EO) x1 -H (a-1) (In the formula, R 1a , R 2a are each an alkyl group, and R 1a and R 2a The sum of the carbon numbers of R is 9 to 15. 1a and R 2aThe difference in the number of carbon atoms between these is 0 or more and 3 or less, EO represents an oxyethylene group, x1 represents the average number of moles of oxyethylene groups added, and x1 is a number of 1 or more and 6 or less. R 1b -CH(R 2b )-O-(EO) x2 -H (b-1) R 3b -CH(R 4b )-O-(EO) x3 (PO) y1 -H (b-2) (In formulas (b-1) and (b-2), R 1b , R 2b , R 3b and R 4b Each represents an alkyl group having 1 to 14 carbon atoms, and R 1b and R 2b The sum of the carbon numbers and R 3b and R 4b The sum of the carbon numbers of each of the above is 9 or more and 15 or less, EO represents an oxyethylene group, PO represents an oxypropylene group, x2 and x3 represent the average number of moles of oxyethylene groups added, each being a number greater than 6 and not greater than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the condition greater than 0 and less than 6, (EO) x3 (PO) y1 can be block or random.)

[0045] In the method for producing a soil cleaner of the present invention, component (C) may be optionally blended. The matters described for the soil cleaner of the present invention can be appropriately applied to components (A), (B) and (C) in the method for producing a soil cleaner of the present invention. Specific examples and preferred examples of components (A), (B) and (C) of the soil cleaner are the same as those of the soil cleaner described above. In addition, the contents in the soil cleaner can be applied by replacing them with the blending amounts.

[0046] The present invention provides a method for treating soil by contacting a treatment solution containing the soil washing agent of the present invention with the soil, the total concentration of components (A) and (B) in the treatment solution being 0.5 mass% or more. The treatment solution of the present invention may be the soil washing agent of the present invention or the soil washing agent of the present invention diluted with a solvent such as water. That is, the soil washing agent of the present invention can be used directly or after diluting with a solvent such as water.

[0047] In the soil treatment method of the present invention, the treatment solution to be contacted with the soil contains component (A) and component (B), and the mass ratio of the content of component (A) to the content of component (B), (A) / (B), may be 95 / 5 or less and 50 / 50 or more.

[0048] The soil treatment method of the present invention can be applied, for example, to in-situ washing, which washes soil without moving the soil, and excavation and removal washing, which washes excavated soil, etc. Specific examples, preferred examples, and contents at the time of use of components (A), (B) and (C) of the treatment solution used in the soil treatment method of the present invention are the same as those of the soil washing agent described above.

[0049] In soil washing, the treatment liquid of the present invention is brought into contact with the soil to wash the soil. For example, the treatment liquid is sprayed on the contaminated soil, or the treatment liquid is circulated or passed through the soil to bring the treatment liquid into contact with the soil, thereby washing the soil. When the treatment liquid is circulated or passed through, a part of the flow path through which the treatment liquid circulates or passes may be the soil to be washed. For example, in the case of in-situ washing, the treatment liquid is circulated through the contaminated soil to wash the soil. More specifically, the treatment liquid is injected into the soil, and the injected treatment liquid is pumped up, so that the treatment liquid flows through the contaminated soil to wash the soil.

[0050] Alternatively, a method can be used in which a soil washing agent or a combination of a solvent and a soil washing agent is added to the target soil, mixed thoroughly, and then the washed soil is separated and dried.

[0051] The soil washing agent of the present invention can be suitably used for water-passing and pumping washing, because the components (A) and (B) that are compatible with oils can efficiently strip the oil and emulsify and disperse it in the washing solution even under washing conditions where no mechanical force is applied. Therefore, the soil washing agent of the present invention can be suitably used for in-situ washing, in which the treatment solution of the present invention is injected into soil, the injected treatment solution is pumped up, and the treatment solution is passed through the soil to perform a washing treatment.

[0052] In the treatment solution used for treating soil, the total concentration of component (A) and component (B) is, from the viewpoints of cleanability and reducing the amount of cleaning solution required for cleaning, 0.5% by mass or more, preferably 0.8% by mass or more, more preferably 1.0% by mass or more, even more preferably 1.2% by mass or more, and even more preferably 1.5% by mass or more; and, from the viewpoints of cleanability and not increasing the cost of the cleaning agent, it is preferably 100% by mass or less, more preferably 70% by mass or less, even more preferably 50% by mass or less, even more preferably 30% by mass or less, even more preferably 15% by mass or less, even more preferably 12% by mass or less, even more preferably 10.0% by mass or less, even more preferably 5.0% by mass or less, and even more preferably 3.0% by mass or less.

[0053] The treatment solution used in soil treatment has a mass ratio of component (A) to component (B), (A) / (B), of 95 / 5 or less, preferably 90 / 10 or less, and more preferably 85 / 15 or less, from the viewpoint of enhancing the emulsification-promoting effect of diffusing oils in the soil into water, and from the viewpoint of enhancing affinity with oils in the soil, the mass ratio is 50 / 50 or more, preferably 60 / 40 or more, and more preferably 75 / 25 or more.

[0054] The content of component (C) in the treatment solution used for treating soil is preferably 0.03 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.07 mass% or more, from the viewpoint of preventing redeposition of peeled oils and assisting the cleaning power of the nonionic surfactant, and from the viewpoint of reducing the cost of the cleaning agent, is preferably 0.3 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less.

[0055] The contaminants that can be cleaned by the present invention are various poorly water-soluble organic compounds, particularly crude oil and its processed petroleum-based hydrocarbons (gasoline, kerosene, light oil, heavy oil, fuel oil, machine oil). In particular, the soil cleaner of the present invention has excellent cleaning properties for light oil, and can be suitably used for cleaning soil contaminated with light oil. Note that heavy oil also includes light oil, so it is believed that the effects of the present invention can also be obtained with heavy oil and other petroleum-based hydrocarbons that include light oil.

[0056] Target soils include soil from oil leaks at gas stations or former factory sites, soil contaminated by illegal dumping of industrial waste, former airport sites that were frequently polluted by jet fuel leaks, soil and beaches contaminated by leakage from oil tankers, etc. The soil washing agent of the present invention is used for washing organic soil, sandy soil, clayey soil, etc., and is particularly suitable for washing sandy soil. EXAMPLES

[0057] Details of the components (A) and (B) used in the examples and comparative examples are shown in Tables 1 and 2, respectively. Components (A') and (B') are comparative components of components (A) and (B), respectively. 1a , R 2a and R in Table 2 1b~4b are each a straight-chain alkyl group.

[0058] [Table 1]

[0059] [Table 2]

[0060] (C) Component C-1 Diisobutylene / maleic acid copolymer (sodium salt) (molecular weight: 25,000, diisobutylene / maleic acid molar ratio: 50 mol% / 50 mol%) (active ingredient content of 25% by mass was used; active ingredient concentration is shown in the table.)

[0061] Using component (A) in Table 1, component (B) in Table 2, or component (C) above, the treatment solutions shown in Table 3 or Table 4 were prepared and washing tests were conducted using model contaminated soil. Note that the balance in the treatment solutions of the Examples and Comparative Examples was water. In addition, in Tables 3 and 4, when the treatment solution contained component (A') or component (B'), the components (A') and (B') were regarded as the components (A) and (B), respectively, and (A)+(B) and (A) / (B) were calculated.

[0062] (1) Model contaminated soil The simulated contaminated silica sand was prepared by adding 1% by mass of diesel to No. 7 silica sand (manufactured by Mikawa Silica Co., Ltd.) and stirring and mixing the sand until it was sufficiently homogenous using a handheld mixer.

[0063] (2) Water flow cleaning test method A 30 ml injection syringe (Terumo syringe) was filled with simulated contaminated silica sand (20 g) and compressed by pressing it with the piston part of the syringe. The outlet of the tube pump was connected to the needle of a syringe filled with simulated contaminated silica sand, and the treatment liquid was injected into the syringe at a constant rate from the inlet of the tube pump. The flow rate of the treatment liquid from the tube pump was adjusted to 2.5 ml per hour during the test. In the water-passing cleaning test, the time it takes for the treatment liquid to be injected into the voids in the silica sand is 2.5 hours, so the time for one injection was set to 2.5 hours. The number of injections of the treatment liquid was not counted until the treatment liquid was stored in the voids in the silica sand, but after it had passed through the silica sand. In the water-passing cleaning test, the cleaning rate shown in the evaluation method in (3) below was calculated after one injection, and the cleaning power was evaluated.

[0064] (3) Evaluation method The residual light oil was extracted from the silica sand after the water-flow cleaning test with dichloromethane, and the TPH concentration (total petroleum hydrocarbon concentration) of the residual light oil was measured using gas chromatography (Agilent Technologies, Inc., 6850A). In addition, the TPH concentration of simulated contaminated silica sand (20 g) that had not been subjected to the water-flow cleaning test was measured in the same manner as for the silica sand after the water-flow cleaning test, and this was used as the TPH concentration of the light oil before cleaning. The cleaning rate (%) was then calculated from the TPH concentration (ppm) of the residual light oil and the TPH concentration (ppm) of the light oil before cleaning, based on the following formula. The results are shown in Tables 3 and 4. The higher the cleaning rate, the better the cleaning power of the soil cleaner. Cleaning rate (%) = [(TPH concentration of diesel before cleaning - TPH concentration of residual diesel) / TPH concentration of diesel before cleaning] x 100

[0065] [Table 3]

[0066] [Table 4]

Claims

1. The composition comprises: (A) a nonionic surfactant represented by the following general formula (a-1) (hereinafter referred to as component (A)); and (B) a nonionic surfactant represented by the following general formula (b-1) or (b-2) (hereinafter referred to as component (B)), The total content of the components (A) and (B) in the total surfactants contained in the soil cleaner is 80 mass% or more, the mass ratio (A) / (B) of the content of the component (A) to the content of the component (B) is 95 / 5 or less and 50 / 50 or more; When used, the total concentration of the (A) component and the (B) component is 0.5% by mass or more. A cleaning agent for soil contaminated with oil. 2 １ａ -C((2 ２ａ )---(5) ｘ１ -2 (1-1) (In the formula, R １ａ , R ２ａ are each an alkyl group, and R １ａ and R ２ａ The sum of the carbon numbers of R is 9 or more and 15 or less. １ａ and R ２ａ The difference in the number of carbon atoms between the groups is 0 or more and 3 or less, EO represents an oxyethylene group, x1 represents the average number of moles of the oxyethylene group added, and x1 is a number of 1 or more and 6 or less. 2 １ｂ -C((2 ２ｂ )---(5) ｘ２ -2 (1-1) 2 ３ｂ -C((2 ４ｂ )---(5) ｘ３ (0) ｙ１ -(b-2) (In formulas (b-1) and (b-2), R １ｂ , R ２ｂ , R ３ｂ and R ４ｂ Each represents an alkyl group having 1 to 14 carbon atoms, and R １ｂ and R ２ｂ The sum of the carbon numbers of R ３ｂ and R ４ｂ The sum of the carbon numbers of each of the above is 9 or more and 15 or less, EO represents an oxyethylene group, PO represents an oxypropylene group, x2 and x3 represent the average number of moles of oxyethylene groups added, each of which is a number greater than 6 and less than 17, y1 represents the average number of moles of oxypropylene groups added, and y1 is a number that satisfies the condition of greater than 0 and less than 6, (EO) ｘ３ (PO) ｙ１ may be block or randomly added.)

2. The cleaning agent for soil contaminated with oils as described in claim 1, further containing (C) a copolymer of one selected from olefins having 4 to 8 carbon atoms and maleic acid (hereinafter referred to as component (C)).

3. 3. The cleaning agent for soil contaminated with oils according to claim 2, wherein component (C) is a diisobutylene / maleic acid copolymer.

4. 4. The cleaning agent for soil contaminated with oils according to claim 1, wherein the HLB of component (A) is 7 or more and 11 or less, as determined by the Griffin method.

5. The cleaning agent for soil contaminated with oils according to any one of claims 1 to 4, wherein the HLB of component (B) is 7 or more and less than 16 according to the Griffin method.

6. 6. The cleaning agent for soil contaminated with oils according to claim 1, wherein the weighted average of the HLB of component (A) and the HLB of component (B) is 9.5 or more and less than 12.

0.

7. A cleaning agent for soil contaminated with oils described in any one of claims 1 to 6, wherein the soil includes sandy soil.

8. A method for treating soil contaminated with oil, comprising contacting a treatment liquid containing the oil-contaminated soil washing agent according to any one of claims 1 to 7 with soil contaminated with oil, The total concentration of the component (A) and the component (B) in the treatment liquid is 0.5% by mass or more. How to treat the soil.

9. The method for treating soil according to claim 8 , wherein the treatment liquid is contacted with the soil by circulating the treatment liquid.

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