JP7640253B2 - Soil Cleaning Agent - Google Patents

Description

The present invention relates to a soil cleaning agent and a method for treating soil.

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.

Traditionally, methods for remediating such contaminated soil have involved 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.

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.

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.

JP 2009-132905 A JP 2011-144223 A JP 2003-119495 A

The present invention aims to provide a soil cleaner that has excellent cleaning power and can efficiently clean oil from soil contaminated with oil.

The present invention 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 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 the (A) component and the (B) component 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 and R ^2a each represent an alkyl group, the sum of the carbon numbers of R ^1a and R ^2a is 9 or more and 15 or less, the difference between the carbon numbers of R ^1a and R ^2a 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.)
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 represent an alkyl group having 1 to 14 carbon atoms, and the sum of the carbon numbers of R ^1b and R ^2b and the sum of the carbon numbers of R ^3b and R ^4b each represent 9 to 15, 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 equal to or less than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the range greater than 0 and less than 6, and (EO) _x3 (PO) _y1 may be block addition or random addition.)

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 component (A) and the component (B) in the treatment liquid is 0.5% by mass or more.
This relates to a method for treating soil.

The present invention provides a soil cleaner that has excellent cleaning power and can efficiently clean oil from soil contaminated with oil.

The present inventors have discovered that a soil cleaner containing a nonionic surfactant having a branched, rather than linear, alkyl structure and two types of nonionic surfactants having 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 a branched alkyl structure are more compatible with oils in soil than linear ones with a bulky structure, and that among the compatible branched types, nonionic surfactants with a low average number of added moles of EO have a modifying effect that acts on oils in soil to modify them into dirt that is easier to remove, while nonionic surfactants with a high average number of added moles of EO have an emulsification-promoting effect that diffuses oils in soil into water. It is believed that by containing a nonionic surfactant with a branched structure but a low average number of added moles of EO and a nonionic surfactant with a high average number of added moles of EO in a specified ratio, the detergency of the soil cleaner is improved by the synergistic effect of the modifying effect and the emulsification-promoting effect.

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 mixture of the components (A) and (B).

The component (A) is a compound represented by general formula (a-1). As the component (A), one compound selected from the compounds represented by 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 and R ^2a each represent an alkyl group, the sum of the carbon numbers of R ^1a and R ^2a is 9 or more and 15 or less, the difference between the carbon numbers of R ^1a and R ^2a 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.)

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

The difference in the number of carbon atoms between R ^1a and R ^2a is from the viewpoint of an alkyl chain balance that facilitates affinity with oils in soil, and is from 0 to 3, preferably from 0 to 2, more preferably 0 or 1, and even more preferably 0.

From the viewpoint of affinity with oils in the soil, 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.

As component (A), alcohol alkoxylates are preferred, and branched alcohol ethoxylates are more preferred.

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 x sum of formula weights of hydrophilic parts / molecular weight). Unless otherwise specified below, 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).

The component (B) is a compound represented by the following general formula (b-1) or (b-2). As the component (B), one compound selected from the compounds represented by general formula (b-1) or (b-2) can be used alone, or two or more compounds can be used in combination.
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 represent an alkyl group having 1 to 14 carbon atoms, and the sum of the carbon numbers of R ^1b and R ^2b and the sum of the carbon numbers of R ^3b and R ^4b each represent 9 to 15, 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 equal to or less than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the relationship greater than 0 and less than 6, and (EO) _x3 (PO) _y1 may be block addition or random addition.)

The carbon numbers of R ^1b , R ^2b , R ^3b and R ^4b are each 1 or more, preferably 3 or more, and more preferably 5 or more, from the viewpoint of the emulsification-promoting action of diffusing oils in soil into water, and each is 14 or less, preferably 10 or less, more preferably 7 or less, and even more preferably 6 or 7, from the viewpoint of preventing the removed oils from re-adhering to the soil.

The sum of the carbon numbers of R ^1b and R ^2b and the sum of the carbon numbers of R ^3b and R ^4b are each 9 or more, preferably 10 or more, more preferably 11 or more, and even more preferably 12 or more, from the viewpoint of an emulsification-promoting action for diffusing oils in soil into water, and each is 15 or less, preferably 14 or less, from the viewpoint of preventing the removed oils from reattaching to the soil.

The average number of moles of oxyethylene groups added, x2 and x3, are each more than 6, preferably 7 or more, from the viewpoint of promoting emulsification to diffuse oils in the soil into water, and each are each 17 or less, preferably 13 or less, more preferably 9 or less, from the viewpoint of preventing redeposition of removed oils on the soil.

The average number of moles of oxypropylene groups added, y1, is greater than 0, preferably greater than 2, more preferably greater than 3, from the viewpoint of promoting emulsification that diffuses oils in the soil into water, and is less than 6, preferably less than 5, from the viewpoint of preventing redeposition of removed oils on the soil.

As component (B), alcohol alkoxylates are preferred, and branched chain alcohol alkoxylates are more preferred.

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 effect of diffusing oils in soil into water. Here, the HLB value is determined by the Griffin method. Examples of such components (B) include branched secondary alcohol ethoxylate 9 mole adduct (HLB = 13.3), branched secondary alcohol alkoxylate (ethylene oxide: 7 moles, propylene oxide: 4.5 moles adduct) (HLB = 8.0), etc.

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

From the viewpoint of the formulation required to form a concentrated product, component (C) is preferably a diisobutylene/maleic acid copolymer.

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 supporting 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.

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: G4000PWXL + G2500PWXL manufactured by Tosoh Corporation
2-wire connection/detection: RI
・Flow rate: 1.0mL/min.
Injection volume: 200 μL
Temperature: 40°C
Eluent: 0.2M phosphate buffer/acetonitrile = 70/30 (volume ratio)

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

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.

The soil cleaner of the present invention may contain water. The soil cleaner of the present invention may be water, excluding the components (A), (B), and (C).

From the viewpoint of cleaning performance and reducing the amount of cleaning solution required for cleaning, the soil cleaner of the present invention is used at a total content of components (A) and (B) of 0.5% by mass or more in the soil cleaner, 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 viewpoint of cleaning performance and not increasing the cost of the cleaner, it is preferably used at 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.

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 at the time of formulation of the soil cleaner of the present invention.

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 strengthening 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 strengthening compatibility with oils in the soil.

Among the soil cleaners of the present invention, those in which the HLB based on the combined ratio of components (A) and (B), i.e., 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, can be preferably used from the viewpoint of efficient oil removal from soil contaminated with oil. The HLB based on the combined ratio of components (A) and (B) (weighted average of HLB) is the sum of the product of the content (mass) of component (A) and the HLB of component (A) according to the Griffin method and the product of the content (mass) of component (B) and the HLB of component (B) according to the Griffin method, divided by the total content (mass) of components (A) and (B).

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

When the soil cleaner 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 the 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.

The pH of the soil cleaner 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 elution from soil of heavy metals and the like that are assumed to be complex contaminants.

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

The soil cleaner of the present invention may contain, as optional components, other surfactants besides components (A) and (B), defoamers, one-liquid agents, preservatives, etc.

Examples of surfactants other than components (A) and (B) include anionic surfactants.

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 have a total content of components (A) and (B) in the entire surfactant of 100 mass%, i.e., the surfactant may be composed of components (A) and (B).

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 and R ^2a each represent an alkyl group, the sum of the carbon numbers of R ^1a and R ^2a is 9 or more and 15 or less, the difference between the carbon numbers of R ^1a and R ^2a 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.)
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 represent an alkyl group having 1 to 14 carbon atoms, and the sum of the carbon numbers of R ^1b and R ^2b and the sum of the carbon numbers of R ^3b and R ^4b each represent 9 to 15, 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 equal to or less than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the range greater than 0 and less than 6, and (EO) _x3 (PO) _y1 may be block addition or random addition.)

In the method for producing a soil cleaner of the present invention, component (C) may be optionally blended. The matters described in the soil cleaner of the present invention can be applied as appropriate 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 content in the soil cleaner can be applied by replacing it with the blending amount.

The present invention provides a method for treating soil, which comprises contacting soil with a treatment liquid containing the soil cleaner of the present invention, in which the total concentration of components (A) and (B) in the treatment liquid is 0.5 mass% or more. The treatment liquid of the present invention may be the soil cleaner of the present invention or the soil cleaner of the present invention diluted with a solvent such as water. In other words, the soil cleaner of the present invention can be used directly or after diluting with a solvent such as water.

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

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. Specific examples, preferred examples, and amounts 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.

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 onto 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, 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.

Another method that can be used is to add a soil cleaner or a solvent and a soil cleaner to the target soil, mix well, and then separate and dry the washed soil.

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

In the treatment solution used in treating the soil, the total concentration of components (A) and (B) 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, from the viewpoints of washability and reducing the amount of washing solution required for washing, and 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, from the viewpoints of washability and not increasing the cost of the washing agent.

The mass ratio (A)/(B) of the treatment solution used in treating soil 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 compatibility with oils in the soil.

In the treatment solution used for treating soil, the content of component (C) is preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.07% by 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, it is preferably 0.3% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less.

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, so it can be suitably used to clean soil contaminated with light oil. Note that heavy oil also contains 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 contain light oil.

Target soils include soil from oil leaks at gas stations and former factory sites, soil contaminated by illegal dumping of industrial waste, former airport sites that were frequently contaminated by jet fuel leaks, and soil and beaches contaminated by leaks from oil tankers. The soil cleaner of the present invention is used to clean organic soil, sandy soil, clayey soil, etc., and is particularly suitable for cleaning sandy soil.

Details of 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. R ^1a and R ^2a in Table 1 and R ^{1b to 4b} in Table 2 are each linear alkyl groups.

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

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 cleaning tests were conducted using model contaminated soil. Note that the balance in the treatment solutions of the Examples and Comparative Examples is water. In addition, in Tables 3 and 4, when the treatment solution contains 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.

(1) Model contaminated soil: 1% by mass of diesel was added to No. 7 silica sand (manufactured by Mikawa Silica Co., Ltd.), and the mixture was stirred and mixed using a handy mixer until sufficiently uniform, and used as the model contaminated silica sand.

(2) Water-passing 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 from the inlet of the tube pump at a constant rate. 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 for the treatment liquid to be injected into the voids in the silica sand was 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.

(3) Evaluation method The residual light oil was extracted from the silica sand after the water-passing cleaning test with dichloromethane, and the TPH concentration (total petroleum hydrocarbon concentration) of the residual light oil was measured using gas chromatography (6850A manufactured by Agilent Technologies, Inc.). In addition, the TPH concentration of simulated contaminated silica sand (20 g) that had not been subjected to the water-passing cleaning test was measured in the same manner as for the silica sand after the water-passing cleaning test, and this was taken as the TPH concentration of the light oil before cleaning. Then, based on the following formula, the cleaning rate (%) was calculated from the TPH concentration (ppm) of the residual light oil and the TPH concentration (ppm) of the light oil before cleaning. 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

Claims (9)

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 .
R ^1a -CH(R ^2a )-O-(EO) _x1 -H (a-1)
(In the formula, R ^1a and R ^2a each represent an alkyl group, the sum of the carbon numbers of R ^1a and R ^2a is 9 or more and 15 or less, the difference between the carbon numbers of R ^1a and R ^2a 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.)
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 represent an alkyl group having 1 to 14 carbon atoms, and the sum of the carbon numbers of R ^1b and R ^2b and the sum of the carbon numbers of R ^3b and R ^4b each represent 9 to 15, 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 equal to or less than 17, y1 represents the average number of moles of oxypropylene groups added, y1 being a number that satisfies the range greater than 0 and less than 6, and (EO) _x3 (PO) _y1 may be block addition or random addition.) 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. The cleaning agent for oil-contaminated soil according to claim 2, wherein component (C) is a diisobutylene/maleic acid copolymer. 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. 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. 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. The cleaning agent for soil contaminated with oils according to any one of claims 1 to 6, wherein the soil includes sandy soil. 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 the 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. The method for treating soil according to claim 8 , wherein the treatment liquid is contacted with the soil by circulating the treatment liquid.