Soil cleaning method

Abstract

To provide a soil cleaning method that delivers superior efficacy in cleaning the soil affected by oxidatively degraded oils.SOLUTION: A soil cleaning method includes bringing the soil affected by oxidatively degraded oils into contact with a liquid detergent composition at 65°C or higher and 100°C or lower, containing (a) an alkylene oxide adduct of aliphatic alcohol and water.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for washing soil and a method for producing regenerated 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] 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 the overall cost of purification. Usually, soil washing uses a cleaning agent that contains a surfactant.

[0005] Patent Document 1 discloses a soil purification agent composition containing (A1) a specific nonionic surfactant and (B) an organic amine compound. Furthermore, Patent Document 2 discloses a soil washing agent containing a nonionic surfactant and a polycarboxylic acid polymer (A). [Prior art documents] [Patent documents]

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

[0007] However, oxidatively deteriorated oils have an increased number of polar groups (carbonyl groups) in the molecule, which tends to strongly interact with soil such as hydrophilic aggregates, making cleaning difficult. Therefore, there is a demand for improved cleaning effects for soil contaminated by oxidatively deteriorated oils, particularly oxidatively deteriorated heavy oil and other oils. Patent Documents 1 and 2 do not mention anything about the cleaning properties of soil contaminated with oxidatively deteriorated oils. The present invention provides a soil washing method that is highly effective in washing soil having oxidatively deteriorated oils attached thereto, and a method for producing regenerated soil using said soil washing method. [Means for solving the problem]

[0008] The present invention relates to a method for cleaning soil, comprising contacting soil having oxidatively deteriorated oils attached thereto with a liquid cleaning composition having a temperature of 65°C or higher and 100°C or lower, the liquid cleaning composition comprising (a) an alkylene oxide adduct of an aliphatic alcohol (hereinafter referred to as component (a)) and water.

[0009] The present invention also relates to a method for producing regenerated soil, which includes the steps of: contacting soil having oxidatively deteriorated oils attached thereto with (a) a liquid cleaning composition at 65°C or higher and 100°C or lower, which contains an alkylene oxide adduct of an aliphatic alcohol and water, thereby transferring the oxidatively deteriorated oils attached to the soil from the soil to the liquid cleaning composition; and separating the liquid cleaning composition containing the oxidatively deteriorated oils that have been transferred from the soil from the soil to obtain regenerated soil. Effect of the Invention

[0010] According to the present invention, there are provided a soil washing method which is highly effective in washing soil having oxidatively deteriorated oils attached thereto, and a method for producing regenerated soil using said soil washing method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The reason why the soil washing method of the present invention has an excellent washing effect on soil having oxidized and deteriorated oils attached thereto is not clear, but is presumed to be as follows. It is believed that oxidatively deteriorated oils, such as heavy oil, have an increased number of polar groups (carbonyl groups, carboxyl groups, etc.) in their molecules, which strongly interact with hydrophilic soils (for example, aggregates), making cleaning more difficult. It is also believed that the polar interaction between soil and oils is temperature dependent, weakening at high temperatures. Nonionic surfactants contain oxygen atoms that have a high affinity for soil, but it is presumed that if the interaction between the nonionic surfactant and water molecules is strong, it becomes difficult for the nonionic surfactant to have an affinity for the soil interface. In the soil cleaning method of the present invention, a liquid cleaning composition containing a specified nonionic surfactant, component (a), is applied to contaminated soil at a specified temperature, and the balance between the effect of weakening the polar interaction between the soil and oxidatively deteriorated oils and the effect of weakening the interaction between the nonionic surfactant and water molecules makes it possible to efficiently remove the coating of oxidatively deteriorated oils from the soil, and it is presumed that this effectively achieves a remarkable cleaning effect on soil contaminated with oxidatively deteriorated oils. In addition, it is presumed that the inclusion of a nonionic surfactant containing an unsaturated bond in component (a) provides a superior cleaning effect against oxidized and deteriorated oils that contain many aromatic groups or unsaturated structures. The soil washing method of the present invention and the method for producing regenerated soil of the present invention are not limited to the above-mentioned mechanism of action.

[0012] <Liquid detergent composition> First, the liquid detergent composition used in the soil washing method according to the present invention (hereinafter, referred to as the liquid detergent composition according to the present invention) will be described in detail. The liquid detergent composition according to the present invention may be a liquid detergent composition for soil. The liquid detergent composition according to the present invention contains (a) an alkylene oxide adduct of an aliphatic alcohol (hereinafter referred to as "component (a)") and water.

[0013] <Component (a)> The component (a) is an alkylene oxide adduct of an aliphatic alcohol. The aliphatic alcohol may be a linear saturated or unsaturated aliphatic alcohol. The carbon number of the aliphatic alcohol is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, even more preferably 14 or more, even more preferably 18 or more, from the viewpoint of affinity with oils such as oxidatively deteriorated heavy oil, and is preferably 26 or less, more preferably 24 or less, even more preferably 22 or less, even more preferably 20 or less, from the viewpoint of stability in an aqueous solution. The alkylene oxide may be an alkylene oxide having 2 to 4 carbon atoms, and is preferably at least one selected from ethylene oxide and propylene oxide.

[0014] Examples of component (a) include polyoxyethylene alkyl ethers, polyoxyethylene alkenyl ethers, and polyoxyethylene polyoxypropylene alkyl ethers. The average number of moles of alkylene oxide added is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, even more preferably 8 or more, and even more preferably 10 or more, from the viewpoint of improving affinity to the soil (e.g., aggregate) surface, and is preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less, from the viewpoint of affinity with oils such as oxidized and deteriorated heavy oil.

[0015] Examples of component (a) include polyoxyethylene octyl ether, polyoxyethylene dodecyl ether, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene palmityl ether, polyoxyethylene stearyl ether, polyoxyethylene arachidyl ether, polyoxyethylene behenyl ether, polyoxyethylene oleyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene myristyl ether, etc. Component (a) is preferably one of these compounds in which the average number of moles of oxyethylene etc. added is within the range of the average number of moles of alkylene oxide added.

[0016] The component (a) is preferably at least one compound selected from the compounds represented by the following general formula (a1). R 1a -O-(A 1a O) n -H(a1) [In the formula, R 1a is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, 1a The O group is at least one selected from alkyleneoxy groups having 2 to 4 carbon atoms. 1a The average number of moles of O groups added is 2 or more and 20 or less.

[0017] In general formula (a1), R 1a From the viewpoint of affinity with oils such as oxidatively deteriorated heavy oil, the number of carbon atoms is preferably 8 or more, more preferably 10 or more, even more preferably 12 or more, even more preferably 14 or more, even more preferably 18 or more, and from the viewpoint of stability in an aqueous solution, the number of carbon atoms is preferably 26 or less, more preferably 24 or less, even more preferably 22 or less, even more preferably 20 or less. R 1a is an aliphatic hydrocarbon group, preferably a group selected from an alkyl group and an alkenyl group, more preferably an alkenyl group. R 1a may be linear or branched, preferably linear.

[0018] In general formula (a1), A 1a The O group is at least one selected from alkyleneoxy groups having from 2 to 4 carbon atoms, preferably at least one selected from alkyleneoxy groups having from 2 to 3 carbon atoms, more preferably an ethyleneoxy group. 1a When the O group comprises a plurality of different alkyleneoxy groups, the different alkyleneoxy groups may be bonded in blocks or in a random manner.

[0019] In general formula (a1), n ​​is preferably 2 or more, more preferably 4 or more, even more preferably 6 or more, even more preferably 8 or more, and even more preferably 10 or more from the viewpoint of improving affinity to the soil (e.g., aggregate) surface, and is preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less from the viewpoint of affinity with oils such as oxidized and deteriorated heavy oil.

[0020] The component (a) effectively interacts with both oils such as oxidized and deteriorated heavy oil and the soil surface, and from the viewpoint of enhancing the cleaning ability, R 1a The carbon number of A is 18 to 26. 1a One or more nonionic surfactants selected from compounds in which the O group contains an ethyleneoxy group, a propyleneoxy group, or both, and n is 10 or more and 20 or less, are preferred.

[0021] <Composition, etc.> The liquid detergent composition of the present invention contains component (a) in an amount of preferably 1.0 mass % or more, more preferably 1.5 mass % or more, and even more preferably 2.0 mass % or more from the viewpoint of improving soil cleaning power, and in an amount of preferably 10 mass % or less, more preferably 8 mass % or less, and even more preferably 6 mass % or less from the viewpoint of the stability of the liquid detergent composition. In addition, the liquid detergent composition of the present invention contains, per 100 parts by mass of the liquid detergent composition, preferably 1.0 part by mass or more, more preferably 1.5 parts by mass or more, and even more preferably 2.0 parts by mass or more of component (a) from the viewpoint of improving soil cleaning power, and preferably 10 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 6 parts by mass or less from the viewpoint of the stability of the liquid detergent composition.

[0022] The liquid detergent composition according to the present invention contains water. Examples of water include distilled water, tap water, groundwater, lake water, and river water. Water can be used in an amount such that the composition as a whole is 100% by mass, as the balance other than component (a) and the optional components described below. From the viewpoint of detergency, the liquid detergent composition according to the present invention contains water in an amount of preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less.

[0023] The liquid detergent composition according to the present invention may contain any inorganic base compound or organic base compound within a range that does not impair the effects of the present invention. Examples of inorganic base compounds include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, sodium hydroxide, and potassium hydroxide. Examples of organic base compounds include alkylamines such as ethylamine, diethylamine, triethylamine, propylamine, n-butylamine, di-n-butylamine, and tert-butylamine, alkanolamines such as monoethanolamine, diethanolamine, triethanolamine, and methanolamine, and polyethyleneamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

[0024] The temperature of the liquid cleaning composition of the present invention, which is to be brought into contact with soil contaminated with oil, is 65°C or higher, preferably 70°C or higher, more preferably 75°C or higher, even more preferably 80°C or higher, and even more preferably 85°C or higher, from the viewpoint of increasing the affinity between oils such as oxidatively deteriorated heavy oil and component (a), and is 100°C or lower, preferably 98°C or lower, more preferably 95°C or lower, and even more preferably 90°C or lower, from the viewpoint of workability. The liquid cleaning composition of the present invention may have any temperature within the above range when it is brought into contact with soil, and is preferably heated so as to maintain the above temperature range during the soil cleaning step.

[0025] The pH of the liquid detergent composition according to the present invention at 25°C is preferably 5 or more, more preferably 5.0 or more, still more preferably 6.0 or more, from the viewpoint of detergency, and preferably 14.0 or less, more preferably 13.0 or less, still more preferably 12.0 or less, from the viewpoint of detergency. The pH of the liquid detergent composition according to the present invention at the temperature during soil washing (hereinafter referred to as the washing temperature) is preferably within the above range. If the pH at 25°C is within the above range, it can be said that the pH at the washing temperature also maintains the above range.

[0026] <pH measurement method> Specifically, the pH of the liquid detergent composition according to the present invention at 25°C is measured by the following pH measurement method. Connect a combined pH electrode for measurement (for example, a glass sliding sleeve type manufactured by Horiba, Ltd.) with the internal liquid of the pH electrode being a saturated potassium chloride aqueous solution (3.33 mol / L) to a pH meter (for example, pH / Ion Meter F-23 manufactured by Horiba, Ltd.). Next, fill 100 mL beakers with a pH 4.01 standard solution (phthalate standard solution), a pH 6.86 (neutral phosphate standard solution), and a pH 9.18 standard solution (borate standard solution), respectively, and immerse them in a constant temperature bath at 25°C for 30 minutes. Immerse the pH measurement electrode in the temperature-adjusted standard solution for 3 minutes, and perform a calibration operation in the order of pH 6.86 → pH 9.18 → pH 4.01. Adjust the liquid detergent composition according to the present invention to be measured to 25°C, immerse the electrode of the above pH meter in this liquid detergent composition, and measure the pH after 1 minute. Note that the pH of the liquid detergent composition according to the present invention at the washing temperature can be measured by the same method as above, by reading "25°C" as "washing temperature" in the above description.

[0027] In the liquid detergent composition according to the present invention, the ratio of the component (a) to the active ingredients contained in the composition [(a) / (active ingredient)] is preferably 85 mass% or more, more preferably 87 mass% or more, even more preferably 90 mass% or more, and preferably 100 mass% or less, from the viewpoint of detergency. The liquid detergent composition according to the present invention may be a liquid detergent composition in which the ratio [(a) / (active ingredient)] is 100 mass%, that is, the liquid detergent composition according to the present invention contains the component (a) as an active ingredient. In this specification, the active ingredient may be a component other than water contained in the liquid detergent composition of the present invention, and further a compound that has a cleaning effect on oxidized and deteriorated oils excluding water contained in the liquid detergent composition of the present invention. In other words, in the liquid detergent composition of the present invention, the proportion of component (a) in the components other than water contained in the composition [(a) / (components other than water contained in the liquid detergent composition)] is, from the viewpoint of detergency, preferably 85 mass% or more, more preferably 87 mass% or more, even more preferably 90 mass% or more, and preferably 100 mass% or less.

[0028] In addition, in the liquid detergent composition according to the present invention, the content ratio of the component (a) in the surfactants contained in the composition [(a) / (surfactant)] is preferably 85 mass% or more, more preferably 87 mass% or more, even more preferably 90 mass% or more, and preferably 100 mass% or less, from the viewpoint of detergency. The ratio [(a) / (surfactant)] may be 100 mass%, that is, the liquid detergent composition according to the present invention may be a liquid detergent composition containing the component (a) as a surfactant. Examples of the surfactant other than component (a) include anionic surfactants, nonionic surfactants other than those corresponding to component (a), cationic surfactants, and amphoteric surfactants. The total content of surfactants in the liquid detergent composition according to the present invention may be the total content of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants.

[0029] The liquid detergent composition according to the present invention is for cleaning oxidatively deteriorated oils, and may be for cleaning soil contaminated with petroleum-based compounds. That is, the liquid detergent composition according to the present invention may be a liquid detergent composition for cleaning oily stains such as petroleum-based compounds in soil. In order to better exert the effects of the present invention, it is preferable that the oxidatively deteriorated oils have an n-heptane insoluble matter content per 100 parts by mass of the oxidatively deteriorated oil of preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and preferably 40 parts by mass or less, more preferably 30 parts by mass or less. The oil may be an oily stain such as a petroleum-based compound, or may be an oily stain containing an aromatic hydrocarbon compound from the viewpoint of further exerting the effects of the present invention. Therefore, the oil may be a petroleum-based compound or even an aromatic hydrocarbon compound. The n-heptane insoluble content per 100 parts by mass of the oil is determined according to ASTM Standard D3279: Asphaltene content and heptane insoluble content.

[0030] Examples of such oils include oxidatively deteriorated C heavy oil (15 to 40 parts by mass), asphalt (15 to 25 parts by mass), and oxidatively deteriorated asphalt (15 to 40 parts by mass). The numbers in parentheses in the specific examples of these oils indicate the n-heptane insoluble content per 100 parts by mass of the oil (the same applies to the C heavy oil below). Therefore, the liquid cleaning composition of the present invention may be a liquid cleaning composition for soil that cleans soil having one or more oils selected from oxidatively deteriorated C heavy oil, asphalt, and oxidatively deteriorated asphalt attached thereto. The oxidatively deteriorated C heavy oil has a larger amount of n-heptane insoluble matter than C heavy oil (2 parts by mass to 10 parts by mass), and is a contaminant that is difficult to wash off.

[0031] The soil to be cleaned with the liquid cleaning composition of the present invention is not particularly limited, but from the viewpoint of better exerting the effects of the present invention, the fraction passing through a 75 μm sieve is preferably 15 mass % or less, more preferably 13 mass % or less, even more preferably 10 mass % or less, and preferably 0 mass % or more of aggregate. The liquid detergent composition according to the present invention may be used for washing one or more types of soil selected from fine aggregate, coarse aggregate, and filler. Here, the fine aggregate may be, for example, soil with a particle size of 75 μm to 2.36 mm, the coarse aggregate may be soil with a particle size of 2.36 mm to 26.5 mm, and the filler may be soil with a particle size of 75 μm or less. The particle size is measured according to JIS A1204 "Soil Grain Size Testing Method."

[0032] More specifically, the soil to be cleaned by the liquid detergent composition according to the present invention may be aggregate used in construction or road paving. Examples of the aggregate include aggregates selected from fine aggregates and coarse aggregates. The aggregate preferably includes fine aggregate. Examples of the fine aggregate include those specified by number 2311 in JIS A0203-2014. Examples of the fine aggregate include river sand, land sand, mountain sand, sea sand, lime sand, silica sand, and crushed sand thereof, screenings, crushed stone dust, silica sand, casting sand, blast furnace slag fine aggregate, ferronickel slag fine aggregate, lightweight fine aggregate (artificial and natural), and recycled fine aggregate. Examples of the coarse aggregate include those specified by number 2312 in JIS A0203-2014. For example, examples of coarse aggregate include river gravel, land gravel, mountain gravel, sea gravel, limestone gravel, crushed stones thereof, blast furnace slag coarse aggregate, ferro-nickel slag coarse aggregate, lightweight coarse aggregate (artificial and natural), recycled coarse aggregate, etc. Different types of fine aggregate and coarse aggregate may be mixed and used, or a single type may be used.

[0033] <How to wash soil> The present invention provides a method for cleaning soil, which comprises contacting soil having oxidatively deteriorated oils attached thereto with a liquid cleaning composition having a temperature of 65°C or higher and 100°C or lower, which contains (a) an alkylene oxide adduct of an aliphatic alcohol [component (a)] and water. Examples of the method for adjusting the temperature of the liquid detergent composition to 65° C. or higher and 100° C. or lower include a method of heating a cleaning container with a heating means such as a heater, hot water, or steam, a method of introducing a heating means such as a heater into the liquid detergent composition, etc. In addition to the heating means, a cooling means may be used in combination.

[0034] The method for washing soil according to the present invention may be a method for washing soil, which comprises stirring and mixing a mixture of the soil having oils attached thereto and the liquid detergent composition. The soil washing method according to the present invention may be a method for washing soil by contacting the liquid detergent composition with soil having oils attached thereto. The liquid detergent composition is preferably the liquid detergent composition according to the present invention. Examples of the method for contacting the liquid detergent composition with soil having oils attached thereto include a method of immersing soil in the liquid detergent composition, a method of spraying the liquid detergent composition on soil, and a method of passing the liquid detergent composition through soil. In the soil washing method of the present invention, preferred aspects of the liquid cleaning composition used for washing soil, such as component (a) and its content, and preferred aspects of the temperature and pH of the liquid cleaning composition, are the same as the preferred aspects described for the liquid cleaning composition of the present invention. In addition, the soil washing method of the present invention can effectively remove oxidized and deteriorated oils from soil contaminated with petroleum compounds and / or oils described in the liquid detergent composition of the present invention by washing the soil. Therefore, the preferred embodiments of the oils and soil to be washed in the soil washing method of the present invention are the same as those described in the liquid detergent composition of the present invention.

[0035] In the method for washing soil according to the present invention, a washing method for stirring and mixing a mixture of the soil to which the oil is attached and the liquid detergent composition can be specifically classified and washed. In addition, a method can be used in which the liquid detergent composition is added to the target soil, mixed well, and then the washed soil is separated and dried. Alternatively, a method can be used in which the soil is crushed into powder or fine granules when the soil is in a lump shape, or the soil is put into a suitable container as it is, immersed in the liquid detergent composition, and stirred or vibrated.

[0036] In addition, the soil washing method of the present invention can be preferably applied to a soil excavation and washing method in which soil is excavated and the excavated soil obtained is washed, and a soil washing method in which soil is washed by injecting a liquid detergent composition as a washing liquid into the soil.

[0037] In the method for washing soil according to the present invention, the soil may be washed at the location where the soil exists (on-site), or at a location different from the original location (outside the site). For example, the soil may be washed in a washing facility installed at a location different from the site. In this case, for example, soil collected from the site by excavation may be transferred to a washing facility installed at a location different from the site and washed. The washing facility is preferably installed near the site. For example, soil may be collected at a predetermined location (on-site) within a certain area, and the washing facility may be installed at a location different from the collection location within the same area. In this way, the washing facility may be installed as a so-called on-site plant to wash the soil. The washed soil may be reused by filling it back in the location where it was collected or at another location.

[0038] In addition, in the method for washing soil according to the present invention, for example, the liquid detergent composition according to the present invention or a washing solution obtained by diluting the liquid detergent composition with water can be adjusted to 65°C or higher and 100°C or lower and injected into the soil for washing without excavation. In the method for washing soil according to the present invention, for example, the liquid detergent composition or the like can be injected into contaminated soil at a predetermined position, passed through the contaminated soil, and then the liquid detergent composition or the like can be recovered at a position different from the predetermined position. In this way, the contaminants in the soil, which are oxidized and deteriorated oils, can be taken in and recovered by the liquid detergent composition passing through the soil. The recovery of the liquid detergent composition or the like can be performed by a pumping method or the like, specifically, by a pumping means such as a pump. Then, the contaminants such as oxidized and deteriorated oils can be separated from the recovered liquid detergent composition or the like.

[0039] <How to manufacture regenerated soil> The present invention relates to a process for transferring the oxidatively deteriorated oils adhering to the soil from the soil to the liquid detergent composition, comprising: a process for transferring the oxidatively deteriorated oils adhering to the soil from the soil to the liquid detergent composition; and The present invention provides a method for producing regenerated soil, which comprises a step (hereinafter referred to as step 2) of separating the soil from the liquid cleaning composition containing the oxidatively deteriorated oils that have migrated from the soil to obtain regenerated soil. In the method for producing regenerated soil of the present invention, preferred aspects of component (a), preferred aspects of the liquid detergent composition, and preferred aspects of the target soil and oxidatively degraded oils are the same as the preferred aspects described in the liquid detergent composition of the present invention or the soil cleaning method of the present invention.

[0040] In the method for producing regenerated soil according to the present invention, first, step 1 is carried out. Step 1 is a step of washing soil to which oxidatively deteriorated oils are attached by the soil washing method according to the present invention. Step 1 produces a mixture containing the washed soil and a liquid detergent composition containing the oxidatively deteriorated oils removed from the soil. In the method for producing regenerated soil according to the present invention, step 2 is then carried out. In step 2, the regenerated soil is separated by a separation means from a mixture containing the liquid detergent composition containing the oxidatively deteriorated oils removed from the soil and the washed soil. Examples of the separation means include a method in which the soil is allowed to settle and the liquid detergent composition is removed as a supernatant, and a method in which the liquid detergent composition and the soil are separated by filtration. The liquid detergent composition can also be removed by rinsing the soil with water or the like. From the viewpoint of storage, transportation, and utilization of the reclaimed soil in civil engineering works, etc., it is preferable to dry the soil to remove moisture after separating the liquid detergent composition from the soil. The regenerated soil obtained can be used as soil for remediating contaminated soil sites, as building aggregate, and the like. In addition, in steps 1 and 2, a cleaning liquid prepared by diluting the liquid detergent composition with water can be used instead of the liquid detergent composition. EXAMPLES

[0041] <Composition ingredients> In the examples and comparative examples in Table 1, the following components were used. <Component (a)> The numerical value in parentheses for component (a) indicates the average number of moles of oxyethylene or oxypropylene groups added, or the number of carbon atoms in the alkyl group. Polyoxyethylene (13) oleyl ether: Kao Corporation Polyoxyethylene (6) polyoxypropylene (1.5) alkyl (C12-14) ether: manufactured by Kao Corporation Polyoxyethylene (20) alkyl (C20) ether: manufactured by Kao Corporation Polyoxyethylene (5) lauryl ether: Kao Corporation Polyoxyethylene (5) lauryl ether + diethanolamine: A mixture containing polyoxyethylene (5) lauryl ether and diethanolamine in a mass ratio of 1:0.2 <Component (a')> Sorbitan monolaurate: manufactured by Kao Corporation Sodium dodecyl sulfate: Sodium dodecyl sulfate, manufactured by Tokyo Chemical Industry Co., Ltd. Dodecyltrimethylammonium chloride: manufactured by Tokyo Chemical Industry Co., Ltd. <Water> Distilled water

[0042] <Preparation of oiled soil> (1) Soil The following materials were used to prepare the oil-contaminated soil: Soil B is a soil with a high content of fine powder and a higher mass passing through a 75 μm sieve than Soil A. The particle size distribution of soil A and soil B indicates the mass (mass%) that passed through a sieve of each mesh size when soil A or soil B was placed on the sieve and shaken for 2 minutes with a sieve shaker. <Soil A> No. 6 crushed stone 40.0 parts by weight No. 7 crushed stone 13.0 parts by weight Crushed sand 10.0 parts by mass Coarse sand 22.0 parts by mass Mountain sand 10.0 parts by mass Stone powder 5.0 parts by mass <Particle size distribution of soil A> Sieve size 19.0mm: 100% by mass Sieve size 9.50mm: 80.1% by mass Sieve size 4.75mm: 59.4% by mass Sieve size 2.36mm: 43.4% by mass Sieve size 1.18mm: 29.1% by mass Sieve size 600μm: 18.9% by mass Sieve size 300μm: 11.7% by mass Sieve size 150μm: 7.6% by mass Sieve size 75μm: 5.2% by mass <Soil B> Crushed sand 21.3 parts by mass Coarse sand 41.8 parts by mass Mountain sand 21.3 parts by mass Stone powder 10.6 parts by mass Fine aggregate powder 5.0 parts by mass <Particle size distribution of soil B> Sieve size 4.75mm: 100.0% by mass Sieve size 2.36mm: 95.5% by mass Sieve size 1.18mm: 66.7% by mass Sieve size 600μm: 45.1% by mass Sieve size 300μm: 29.9% by mass Sieve size 150μm: 21.1% by mass Sieve size 75μm: 16.2% by mass

[0043] (2) Preparation method of oil-contaminated soil The oil-adhered soil was prepared as follows: The mixture ratio of soil and oil was adjusted when the soil and oil were first mixed, so that the mass ratio of soil and oil in the mixture after the oxidative degradation treatment was uniform. (2-1) Degraded heavy oil C Commercially available heavy oil C was heated to 90°C, and soil A or soil B was mixed with heavy oil C at 90°C in a mass ratio of soil:heavy oil C = 94.3:5.7. Heavy oil C and soil were mixed using a heated spatula until a uniform coating was formed. The mixture of heavy oil C and soil was then heated in an oven at 160°C for one day to cause oxidation degradation, and a mixture of degraded heavy oil C and soil was obtained. (2-2) Aged Asphalt (Aged Asphalt) Straight asphalt (manufactured by Mitsubishi Corporation Energy Co., Ltd.) was heated to 160°C, and soil A and straight asphalt were mixed at 160°C to a mass ratio of soil:asphalt = 94.5:5.5. The mixture of asphalt and soil was then heated in an oven at 160°C for one day to cause oxidative deterioration, resulting in a mixture of aged asphalt and soil.

[0044] <Measurement of n-heptane insoluble matter in oils> The n-heptane insoluble matter in aged C heavy oil and aged asphalt was measured by the following method. 100 g of the mixture of soil and deteriorated C heavy oil or 100 g of the mixture of soil and deteriorated asphalt prepared in (2) of <Preparation of soil with oil> above was mixed with 300 mL of dichloromethane to extract the deteriorated C heavy oil or deteriorated asphalt from the mixture. The extraction process was repeated until the dichloromethane solution became colorless and transparent. The obtained extracts were concentrated together using a rotary evaporator, and the dichloromethane was removed by evaporation. The n-heptane insoluble content in the obtained oil was then measured according to ASTM D3279. The higher the n-heptane insoluble content in the oil, the greater the amount of oil that has undergone oxidative deterioration.

[0045] <Evaluation of soil cleaning ability of liquid cleaning composition> A 5 cm stirring bar was placed in a 500 mL glass beaker, and 200 g of component (a) or (a') and water in total were added so that the mass ratio of component (a) or (a') to water was the mass part ratio in Table 1. The mixture was stirred (500 rpm) and heated using a water bath stirrer (manufactured by AS ONE Corporation) until the temperature in Table 1 was reached, thereby preparing a liquid detergent composition. Here, the proportion of component (a) among the components other than water contained in the composition was 100 mass%. After the temperature of the liquid detergent composition reached the specified temperature, 50 g of the soil having oil attached thereto prepared in (2) of <Preparation of soil having oil attached thereto> was added to the liquid detergent composition, and the soil was washed by stirring at 500 rpm for 30 minutes while maintaining the specified temperature. After the soil washing, the beaker was left to stand for 1 hour, and the color of the cleaning solution, which was the supernatant after the soil washing, was visually observed. This cleaning solution was the liquid cleaning composition after the soil washing (hereinafter the same). The darker the color of the cleaning solution, the more deteriorated oils have migrated to the cleaning solution, and the higher the cleaning ability of the liquid cleaning composition. In addition, 5 mL of the cleaning solution, which is the supernatant after standing after the soil washing, was collected and diluted with 50 mL of a freshly prepared liquid cleaning composition, and the absorbance at 350 nm was measured using an ultraviolet-visible spectrophotometer (UV2700, UV-VIS SPECTROPHOTOMETER, manufactured by SHIMAZU). The liquid cleaning composition used for dilution had the same composition as the liquid cleaning composition used for washing the soil. The larger the absorbance value, the greater the amount of oxidatively deteriorated oils contained in the cleaning liquid, and the liquid cleaning composition has excellent cleaning properties against oxidatively deteriorated oils.

[0046] [Table 1]

[0047] As shown in Table 1, when soil was washed with the liquid detergent compositions of Examples 1-1 to 1-10, the color of the washing liquid after washing was black, brown, or light yellow, and the oils that had been oxidized and deteriorated had migrated to the washing liquid after washing, and the oils that had adhered to the soil had been removed from the soil by washing. On the other hand, in Comparative Examples 1-1 to 1-6, the washing liquid after washing was colorless and transparent, and it can be seen that the soil was hardly washed at all. The darker the color of the cleaning solution, the more oxidized and deteriorated oils it contains, and therefore the darker the color of the cleaning solution, the better the cleaning ability of the liquid detergent composition can be evaluated. The color intensity of the cleaning solution correlates with the absorbance at 350 nm of the cleaning solution, and it can be seen that the higher the absorbance value, the better the cleaning properties. In addition, by separating the soil from the washing solution, which contains the washed soil to which oxidized and deteriorated oils have migrated, using separation means such as filtration or sedimentation, it was possible to produce soil that has been regenerated by washing (regenerated soil).

Claims

1. Soil contaminated with oxidized and degraded oils, (a) A liquid detergent composition containing an alkylene oxide adduct of an aliphatic alcohol [hereinafter referred to as component (a)] and water, with a temperature of 65°C to 100°C, Make contact, Methods for washing soil.

2. The soil washing method according to claim 1, wherein the oxidatively degraded oils contain 15 parts by mass or more of n-heptane insoluble material per 100 parts by mass of the oxidatively degraded oils.

3. The soil cleaning method according to claim 1 or 2, comprising stirring and mixing a mixture of soil to which the oxidized and degraded oils are attached and the liquid cleaning agent composition.

4. (a) The soil washing method according to claim 1 or 2, wherein the component is one or more compounds selected from those represented by the following general formula (a1). R １ａ -O-(A) １ａ O) ｎ -H (a1) [In the formula, R １ａ A is an aliphatic hydrocarbon group having 8 to 26 carbon atoms, １ａ The O group is one or more alkylene oxy groups with 2 to 4 carbon atoms. n is A １ａ This is the average number of O groups added, and is between 2 and 20.

5. In general formula (a1), R １ａ The method for washing soil according to claim 4, wherein is an alkenyl group.

6. In general formula (a1), R １ａ The soil washing method according to claim 4, wherein the carbon number of is 18 or more and 26 or less.

7. The soil washing method according to claim 4, wherein in the general formula (a1), n ​​is 10 or more and 20 or less.

8. The method for washing soil according to claim 1 or 2, wherein the liquid cleaning agent composition has a proportion of component (a) among the components other than water contained in the composition [(a) / (components other than water contained in the liquid cleaning agent composition)] of 85% by mass or more.

9. The soil washing method according to claim 1 or 2, wherein the oils are aromatic hydrocarbon compounds.

10. The soil washing method according to claim 1 or 2, wherein the soil is aggregate with a pass-through rate of 15% by mass or less through a 75 μm sieve.

11. The process involves bringing soil to which oxidized and degraded oils are attached, and (a) a liquid cleaning agent composition containing an alkylene oxide adduct of an aliphatic alcohol and water at a temperature of 65°C to 100°C, thereby transferring the oxidized and degraded oils attached to the soil from the soil to the liquid cleaning agent composition. A step of separating the liquid cleaning agent composition containing oxidized and degraded oils that have migrated from the soil from the soil to obtain regenerated soil, Having, A method for producing recycled soil.