Soil cleaning method

Abstract

To provide a soil cleaning method characterized by superior cleaning efficacy and small environmental load.SOLUTION: A soil cleaning method involves bringing a soil cleaner composition into contact with the soil, wherein the soil cleaner composition includes (A) a polyoxyalkylene alkyl or alkenyl ether having a C8-20 alkyl group or alkenyl group, with an average number of added oxyalkylene moles of 3 to 20, (B) persulfate, and water.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a soil washing method, a soil washing composition, and a kit for producing a soil washing composition. [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] Conventional methods for remediating such contaminated soil include incineration after excavation, solidification / immobilization, containment, bioremediation, and methods for decomposing and removing contaminants. Also known are techniques for washing contaminated soil with a soil washing agent composition and techniques for decomposing and removing organic compounds and the like in soil using the Fenton reaction.

[0004] Patent Document 1 discloses a method for purifying soil or groundwater by adding persulfate to soil or groundwater contaminated with harmful organic compounds. Patent Document 2 discloses a soil washing agent composition for washing soil contaminated with petroleum-based compounds, which contains (A) a polyoxyethylene alkyl or alkenyl ether having an alkyl or alkenyl group with 10 or more and 18 or less carbon atoms and an average number of moles of ethylene oxide added of 3 or more and 10 or less, (B) an anionic surfactant having a molecular weight of 200 or more and 1,000 or less, and water in a specified ratio. Patent Document 3 discloses a soil purification method in which water containing persulfate and at a temperature higher than that of the contaminated soil, is injected into the contaminated soil in which sulfate-reducing bacteria exist, through an injection well provided in the contaminated soil, and the water is then pumped up through a pumping well provided in the contaminated soil. Patent Document 4 describes a surfactant containing an alkylbenzene sulfonate, Fe 2+ Source of Fe and addition of hydrogen peroxide to soil2+ The present invention discloses a soil purification method including an oxidative decomposition step of decomposing oil by hydroxyl radicals generated by the Fenton reaction between urea and hydrogen peroxide solution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-136961 A [Patent Document 2] Patent Publication No. 2022-7451 [Patent Document 3] JP 2020-93226 A [Patent Document 4] JP 2009-148702 A Summary of the Invention [Problem to be solved by the invention]

[0006] In soil washing, not only is there a need for an excellent soil washing method, but there is also a need for a soil washing method that has a reduced impact on the environment. The present invention provides a soil washing method, a soil washing composition, and a kit for producing a soil washing composition that has excellent cleaning properties and has a low environmental impact. [Means for solving the problem]

[0007] The present invention relates to a method for washing soil, which comprises contacting soil with a soil washing agent composition containing (A) a polyoxyalkylene alkyl or alkenyl ether having an alkyl or alkenyl group with 8 to 20 carbon atoms and an average number of oxyalkylene moles added of 3 to 20 [hereinafter referred to as component (A)], (B) a persulfate [hereinafter referred to as component (B)], and water.

[0008] The present invention also relates to a soil washing agent composition containing (A) a polyoxyalkylene alkyl or alkenyl ether having an alkyl or alkenyl group with a carbon number of 8 or more and 20 or less and an average number of moles of oxyalkylene added of 3 or more and 20 or less, (B) a persulfate salt, and water.

[0009] The present invention also relates to a kit for producing the above-mentioned soil washing agent composition, the kit including an agent containing component (A) and an agent containing component (B) in a state where they are not mixed with each other. Effect of the Invention

[0010] According to the present invention, there are provided a soil washing method, a soil washing composition, and a kit for producing a soil washing composition, which have excellent washing properties and cause little environmental impact. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The reason why the soil washing method of the present invention has excellent washing power for contaminated soil is not entirely clear, but is presumed to be as follows. In the soil washing method of the present invention, by using a surfactant (A) in combination with a persulfate (B), it is presumed that component (A) helps component (B) penetrate into the soil, while component (B) acts as a cleaning aid (builder), modifying the soil contaminants to be more easily washed by component (A). As a result, it is presumed that the soil washing method of the present invention improves soil washability compared to when components (A) and (B) are used alone. In addition, since component (B) turns into sulfate after washing the soil, the burden on the environment is reduced. In addition, since the aqueous solution of component (B) is weakly acidic to neutral, it is possible to wash the soil while suppressing the elution of heavy metals. Furthermore, by using components (A) and (B) in combination, excellent cleaning power can be obtained even when the amount of component (A) added is reduced, thereby reducing the burden of treating the washing wastewater after washing the soil. The soil washing method and soil washing composition of the present invention are not limited to the above-mentioned mechanism of action.

[0012] The soil washing method of the present invention relates to a soil washing method comprising contacting soil with a soil washing agent composition containing (A) a polyoxyalkylene alkyl or alkenyl ether having an alkyl or alkenyl group with 8 to 20 carbon atoms and an average number of oxyalkylene moles added of 3 to 20 [hereinafter referred to as component (A)], (B) a persulfate [hereinafter referred to as component (B)], and water.

[0013] <Soil Cleaning Agent Composition> First, the soil washing agent composition used in the soil washing method of the present invention will be described in detail. The soil washing agent composition of the present invention contains component (A), component (B) and water. The soil washing agent composition of the present invention may be a washing agent composition for soil contaminated with one or more selected from petroleum-based compounds, volatile organic compounds and heavy metals, which washes soil contaminated with one or more selected from petroleum-based compounds, volatile organic compounds and heavy metals, or may be a washing agent composition for soil contaminated with petroleum-based compounds, which washes soil contaminated with petroleum-based compounds.

[0014] <Component (A)> The component (A) is a polyoxyalkylene monoalkyl or alkenyl ether. Examples of the component (A) include polyoxyalkylene alkyl or alkenyl ethers in which the alkyl or alkenyl group has 8 to 20 carbon atoms and the average number of moles of oxyalkylene added is 3 to 20.

[0015] The number of carbon atoms in the alkyl or alkenyl group of the polyoxyalkylene alkyl or alkenyl ether of component (A) is 8 or more, preferably 10 or more, more preferably 12 or more, from the viewpoint of the permeability of component (B) into soil, and is 20 or less, preferably 18 or less, more preferably 16 or less, from the viewpoint of cleaning power at a low addition amount.

[0016] The average number of moles of oxyalkylene added in the polyoxyalkylene alkyl or alkenyl ether of component (A) is 3 or more, preferably 4 or more, and more preferably 5 or more, from the viewpoint of solubility in wash water, and is 20 or less, preferably 18 or less, more preferably 16 or less, and even more preferably 14 or less, from the viewpoint of detergency with a small addition amount. From the viewpoint of solubility in washing water, the oxyalkylene is preferably at least one selected from oxyethylene and oxypropylene, and more preferably oxyethylene.

[0017] The component (A) can be one or more compounds selected from the compounds represented by the following general formula (a1). R 1a O[(C 2 H 4 O) l / (C 3 H 6 O) m ]H(a1) [In the formula, R 1a represents a hydrocarbon group having 8 to 20 carbon atoms. l and m represent the average number of moles added, l represents a number that is 3 to 20, m represents a number that is 0 to 10, and l+m is 3 to 20. " / " represents that the oxyethylene groups and oxypropylene groups may be added randomly or in blocks, regardless of the order.

[0018] R in the above general formula (a1) 1a From the viewpoint of the permeability of the (B) component into soil, the carbon number is 8 or more, preferably 10 or more, and more preferably 12 or more, and from the viewpoint of cleaning power at a low addition amount, the carbon number is 20 or less, preferably 18 or less, and more preferably 16 or less. R 1a From the viewpoint of detergency, is preferably an alkyl group or an alkenyl group, and more preferably an alkyl group. Specific examples of the alkyl group include various octyl groups, various nonyl groups, various decyl groups, various undecyl groups, various dodecyl groups (lauryl groups), various tridecyl groups, various tetradecyl groups, various pentadecyl groups, various hexadecyl groups, various heptadecyl groups, and various octadecyl groups. Examples of alkenyl groups include various octanyl groups, various nonanyl groups, various decanyl groups, various undecanyl groups, various dodecanyl groups, various tridecanyl groups, various tetradecanyl groups, various pentadecanyl groups, various hexadecanyl groups, various heptadecanyl groups, and various octadecanyl groups (e.g., oleyl and linoleyl groups). Note that "various" refers to various isomers including n-, sec-, tert-, and iso-.

[0019] In the above general formula (a1), l and m are, from the viewpoint of solubility in wash water, 3 or more, preferably 4 or more, more preferably 5 or more, and from the viewpoint of detergency at a small addition amount, 20 or less, preferably 18 or less, more preferably 16 or less. Furthermore, in the above general formula (a1), 1 is 3 or more, preferably 5 or more, from the viewpoint of storage stability, and from the same viewpoint, 20 or less, preferably 18 or less, more preferably 16 or less. Moreover, m in the above general formula (a1) is 0 or more, preferably 1 or more, from the viewpoint of storage stability, and from the same viewpoint, is 10 or less, more preferably 5 or less.

[0020] The (A) component is preferably a polyoxyethylene alkyl ether in which the carbon number of the alkyl group is 8 or more, preferably 10 or more, and 20 or less, preferably 18 or less, and the average number of moles of oxyethylene groups added is 3 or more, preferably 4 or more, more preferably 5 or more, and 20 or less, preferably 18 or less, more preferably 16 or less. That is, the component (A) is represented by the general formula (a1) above, R 1ais an alkyl group having 8 or more, preferably 10 or more, and 20 or less, preferably 18 or less, carbon atoms; l is 3 or more, preferably 4 or more, more preferably 5 or more, and 20 or less, preferably 18 or less, more preferably 16 or less; and m is 0.

[0021] <(B) component> Component (B) is a persulfate. Examples of the persulfate of component (B) include alkali metal persulfates such as sodium persulfate and potassium persulfate, and alkaline earth metal persulfates. From the viewpoints of availability and economy, alkali metal persulfates are preferred, and sodium persulfate is more preferred.

[0022] The soil washing agent composition of the present invention contains water. The water may be tap water, groundwater, river water, lake water, well water, etc. The water may be the remainder of the composition excluding the component (A), the component (B), and the optional components described below, and for example, the content of water in the composition is 90% by mass or more and 99.9% by mass or less.

[0023] <Composition, optional ingredients, etc.> The soil washing composition of the present invention, i.e., the soil washing composition to be contacted with soil during soil washing, contains component (A) in an amount of preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and even more preferably 0.05 mass % or more from the viewpoint of the penetration of component (B) into the soil, and preferably 1.0 mass % or less, more preferably 0.5 mass % or less, and even more preferably 0.3 mass % or less from the viewpoint of washing wastewater treatment.

[0024] The soil washing composition of the present invention, i.e., the soil washing composition to be contacted with soil during soil washing, contains component (B) in an amount of preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and even more preferably 0.05 mass % or more from the viewpoint of the function as a washing aid (builder), and preferably 1.0 mass % or less, more preferably 0.8 mass % or less, and even more preferably 0.5 mass % or less from the viewpoints of the burden on the environment and economic efficiency.

[0025] In the soil washing agent composition of the present invention, the mass ratio (A) / (B) of the content of the component (A) to the content of the component (B) is preferably 10 / 90 or more, more preferably 15 / 85 or more, and even more preferably 20 / 80 or more, from the viewpoint of the permeability of the component (B) into the soil, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 60 / 40 or less, from the viewpoint of cleaning power.

[0026] <(C) component> The soil washing composition of the present invention may optionally contain (C) a nonionic polymeric compound having a weight average molecular weight of 3,000 or more and 1,000,000 or less (excluding component (A)) (hereinafter referred to as component (C)).

[0027] The component (C) may, for example, be a compound represented by the following general formula (c1).

[0028] [ka]

[0029] [wherein X is a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or >N-CH 2 -CH 2 -N< is a group represented by the formula: AO is one or more oxyalkylene groups selected from oxyalkylene groups having 2 to 3 carbon atoms; n is the average number of moles added, which is 20 to 23,000; s is a group bonded to X (AO) n is a number that is 1 or more and is equal to or less than the valence of X. When AO is two or more kinds of oxyalkylene groups, AO may be a random bond or a block bond.

[0030] In the general formula (c1), AO is preferably one or more oxyalkylene groups selected from oxyalkylene groups having 2 to 3 carbon atoms. n is preferably 50 or more, more preferably 70 or more, even more preferably 100 or more, and 23,000 or less, preferably 20,000 or less, more preferably 15,000 or less, even more preferably 5,000 or less, and even more preferably 1,000 or less. s is 1 or more and the valence of X or less, more preferably the valence of X. Specifically, when X is a hydroxyl group (valence 1), s is 1. When X is an alkylene group having 2 to 6 carbon atoms (valence 2), s is 1 or more and 2 or less, preferably 2, and when X is an alkoxy group having 1 to 6 carbon atoms (valence 1), s is 1 and X is >N-CH 2 -CH 2 When the group is represented by -N< (valence 4), s is 1 or more and 4 or less, and preferably 4.

[0031] An example of the component (C) in which X in general formula (c1) is a hydroxyl group is a compound represented by the following general formula (c2). The compound represented by general formula (c2) is a compound in which X in general formula (c1) is a hydroxyl group and s is 1. In general formula (c2), the preferred embodiments of AO, n, etc. are the same as those in general formula (c1).

[0032] [ka]

[0033] (In the formula, AO is one or more oxyalkylene groups selected from oxyalkylene groups having 2 to 3 carbon atoms. n is the average number of moles added, which is 20 to 23,000. When AO is two or more oxyalkylene groups, AO may be a random bond or a block bond.)

[0034] Examples of the component (C) in which X in general formula (c1) is a hydroxyl group include one or more nonionic polymers selected from polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene copolymers. From the viewpoints of improving cleaning properties and one-liquid stability, one or more nonionic polymer compounds selected from polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene block polymers are preferred, and one or more nonionic polymer compounds selected from polyethylene glycol and polyoxyethylene polyoxypropylene block polymers are more preferred.

[0035] Examples of the component (C) in which X in general formula (c1) is an alkoxy group having 1 to 6 carbon atoms include methoxypolyethylene glycol, ethoxypolyethylene glycol, butoxypolyethylene glycol, and methoxypolyethylenepolypropylene glycol.

[0036] In the general formula (c1), X is >N-CH 2 -CH 2 An example of component (C) which is a group represented by -N< is a polyoxyethylene-polyoxypropylene block polymer of ethylenediamine. Such component (C) is commercially available, for example, from ADEKA Corporation under the trade name ADEKA Pluronic TR (registered trademark) (e.g., TR-701, TR-704).

[0037] As the component (C), a compound having a polyoxyethylene group (EO) or a polyoxypropylene group (PO) is preferable. When the component (C) contains EO and PO, the EO and PO may be randomly bonded or block-bonded, and block-bonded is preferable. Examples of such compounds include EO-PO copolymers, EO-PO-EO copolymers, and PO-EO-PO copolymers.

[0038] The weight average molecular weight of the (C) component is 3,000 or more, preferably 5,000 or more, more preferably 8,000 or more, from the viewpoint of adsorption to soil, and 1,000,000 or less, preferably 750,000 or less, more preferably 600,000 or less, and even more preferably 100,000 or less, from the viewpoint of one-liquid stability. The weight average molecular weight of the (C) component can be measured by a gel permeation chromatography (GPC) method using high performance liquid chromatography. The measurement conditions for GPC are shown below.

[0039] *GPC conditions Equipment: GPC (HLC-8320GPC) manufactured by Tosoh Corporation Column: G4000PWXL + G2500PWXL (Tosoh Corporation) Eluent: 0.2M phosphate buffer / CH 3 CN=9 / 1 Flow rate: 1.0mL / min Column temperature: 40℃ Detection: RI Sample size: 0.2mg / mL Standard substance: Polyethylene glycol equivalent (monodisperse polyethylene glycol: molecular weight 250,000, 145,000, 87,500, 46,000, 24,000)

[0040] The soil washing composition of the present invention, i.e., the soil washing composition to be contacted with soil during soil washing, may contain component (C) in an amount of preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and even more preferably 0.03 mass % or more from the viewpoint of washing power, and preferably 1.0 mass % or less, more preferably 0.5 mass % or less, and even more preferably 0.3 mass % or less from the viewpoint of washing wastewater treatment.

[0041] When the soil washing composition of the present invention contains the component (C), the mass ratio (A) / (C) of the content of the component (A) to the content of the component (C) in the soil washing composition of the present invention is, from the viewpoint of cleaning power, preferably 30 / 70 or more, more preferably 40 / 60 or more, even more preferably 50 / 50 or more, and from the viewpoint of suppressing adsorption of the component (A) to the soil, preferably 99 / 1 or less, more preferably 95 / 5 or less, even more preferably 90 / 10 or less.

[0042] <(D) component> The soil washing composition of the present invention may optionally contain (D) an anionic surfactant (hereinafter referred to as component (D)). The component (D) may be one or more compounds selected from fatty acid salts, sulfate salts, sulfonates, and phosphate salts. The component (D) is preferably an anionic surfactant having a molecular weight of 200 or more and 1,000 or less.

[0043] The fatty acid salts include compounds in which the carbon number of the fatty acid is preferably from 10 to 18. Specific examples of the fatty acid salts include alkali metal salts and organic amine salts of capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, and mixtures thereof.

[0044] Examples of sulfate salts include sulfate salts having an alkyl or alkenyl group having 10 to 20 carbon atoms. Specific examples of sulfate salts include sulfate salts having an alkyl or alkenyl group having 10 to 20 carbon atoms (AS), polyoxyalkylene alkyl (or alkenyl) ether sulfate salts (AES) (for example, alkyl or alkenyl ether sulfate salts having an average added mole number of oxyalkylene having 2 to 4 carbon atoms of 0.5 to 10 moles and having a linear or branched alkyl or alkenyl group having 10 to 20 carbon atoms), polyoxyalkylene alkyl or alkenyl phenyl ether sulfate salts having a linear or branched alkyl or alkenyl group having 10 to 20 carbon atoms, and castor oil sulfate salts.

[0045] Specific examples of sulfonates include alkanesulfonates (SAS) having from 10 to 20 carbon atoms, linear or branched alkylbenzenesulfonates (LAS or ABS) having an alkyl group having from 8 to 18 carbon atoms, α-olefinsulfonates (AOS) having from 10 to 20 carbon atoms, di- or monoalkylsulfosuccinates (e.g., sodium di(2-ethylhexyl)sulfosuccinate (AOT)), saturated or unsaturated α-sulfofatty acids having from 8 to 20 carbon atoms or their methyl, ethyl or propyl ester salts.

[0046] Examples of the phosphate ester salt include salts of phosphate esters having an alkyl or alkenyl group having 10 to 20 carbon atoms. Specific examples of the phosphate ester salt include polyoxyalkylene alkyl ether phosphates, polyoxyalkylene alkyl phenyl ether phosphates, and long-chain alkyl phosphates. Examples of the phosphate ester salt that can be used include monoesters, diesters, and any mixture of monoesters and diesters (e.g., sesquiesters).

[0047] From the viewpoint of promoting the penetration of the component (B), the component (D) is preferably one or more anionic surfactants selected from sulfate ester salts (AS), polyoxyalkylene alkyl or alkenyl ether sulfate ester salts (AES), and alkylbenzene sulfonate salts (LAS). The component (D) is more preferably one or more anionic surfactants selected from sulfate ester salts (AS) and polyoxyalkylene alkyl or alkenyl ether sulfate ester salts (AES).

[0048] The (D) component is one or more anionic surfactants selected from alkyl sulfate salts, polyoxyethylene alkyl ether sulfate salts, and alkylbenzene sulfonates, preferably having a molecular weight of 200 or more and 1,000 or less, and more preferably having a molecular weight of 200 or more and 1,000 or less, selected from alkyl sulfate salts and polyoxyethylene alkyl ether sulfate salts.

[0049] From the viewpoint of improving cleaning properties, the alkyl sulfate is preferably an alkyl sulfate having an alkyl group having 10 or more and 18 or less carbon atoms. From the viewpoint of improving cleaning properties, the polyoxyethylene alkyl ether sulfate is preferably a polyoxyethylene alkyl ether sulfate having an alkyl group with 10 or more and 18 or less carbon atoms and an average added mole number of oxyethylene groups of 0.5 or more and 5.0 or less. From the viewpoint of improving cleaning properties, the alkylbenzenesulfonic acid is preferably an alkylbenzenesulfonate having an alkyl group with 10 or more and 14 or less carbon atoms.

[0050] Examples of the salt of the anionic surfactant of component (D) include alkali metal salts, alkaline earth metal salts, amine salts, ammonium salts, and alkanolamine salts. From the viewpoint of one-liquid stability, the salt of the anionic surfactant of component (D) is preferably a salt selected from alkali metal salts and alkanolamine salts, and more preferably a sodium salt or an alkanolamine salt. The alkanolamine salt is preferably a salt of an alkanolamine having 1 to 3 alkanol groups having 1 to 3 carbon atoms.

[0051] The soil washing agent composition of the present invention may contain the (D) component in an amount of preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more from the viewpoint of improving washing properties, and in an amount of preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less from the viewpoint of suppressing foaming.

[0052] When the soil washing composition of the present invention contains the component (D), the mass ratio (A) / (D) of the content of the component (A) to the content of the component (D) in the soil washing composition of the present invention is preferably 50 / 50 or more, more preferably 60 / 40 or more, and even more preferably 70 / 30 or more, from the viewpoint of cleaning power, and is preferably 99 / 1 or less, more preferably 98 / 2 or less, and even more preferably 95 / 5 or less, from the viewpoint of product stability.

[0053] <Other ingredients> The soil washing composition of the present invention may contain other optional components as appropriate depending on the purpose, within the range that does not impair the effects of the present invention. For example, the soil washing composition of the present invention may contain components such as gelling inhibitors, thickeners, fragrances, dyes, pigments, bactericides, preservatives, pH adjusters, pH buffers, and masking agents.

[0054] The soil washing agent composition of the present invention can wash soil contaminated with one or more selected from petroleum compounds, volatile organic compounds, and heavy metals. That is, the present invention can remove oily dirt such as petroleum compounds, volatile organic compounds, and heavy metals from soil. Examples of petroleum compounds include petroleum hydrocarbons. Examples of petroleum compounds may be gasoline, kerosene, light oil, heavy oil, and machine oil. Examples of volatile organic compounds may be benzene, toluene, xylene, and volatile organic chlorine compounds such as trichloroethylene, dichloromethane, tetrachloroethylene, and carbon tetrachloride. Examples of heavy metals may be lead, hexavalent chromium, cadmium, arsenic, mercury, and compounds thereof.

[0055] The soil washing composition of the present invention may be a soil washing composition comprising component (A), component (B), and water, for washing soil contaminated with one or more selected from petroleum compounds, volatile organic compounds, and heavy metals. The above-mentioned preferred embodiments can be appropriately applied to this soil washing composition. In addition, the contents of each of the above-mentioned components can be applied to this soil washing composition by replacing them with the blending amounts.

[0056] <Soil cleaning agent composition manufacturing kit> The present invention provides a soil washing composition production kit for producing the soil washing composition of the present invention, A kit is provided which contains an agent containing component (A) and an agent containing component (B) in a mutually unmixed state.

[0057] An example of the kit of the present invention is a kit composed of an agent containing component (A) but not component (B), and an agent containing component (B) but not component (A). In the kit of the present invention, it is preferable from the viewpoint of compound stability that the surfactant component (A) and the oxidizing component (B) are stored and supplied separately. Specific examples and preferred examples of the optional components such as component (A), component (B), and component (C) and component (D) are the same as those of the soil washing composition of the present invention. The matters described for the soil washing composition of the present invention can be appropriately applied to the kit of the present invention.

[0058] In each of the agents constituting the kit of the present invention, the contents of the (A) and (B) components may be, for example, amounts such that a soil washing agent composition of the present invention containing these components in the contents or mass ratios within the above-mentioned ranges can be prepared.

[0059] Each of the agents constituting the kit of the present invention may optionally contain component (C), component (D) and other optional components. The preferred embodiments are the same as those of the soil washing agent composition of the present invention. Although the components (C) and (D) may be different agents from the agent containing component (A) and the agent containing component (B), respectively, it is preferable that the components (C) and (D) are contained in an agent containing component (A) and not containing component (B).

[0060] When washing soil, multiple agents containing components selected from component (A), component (B), optionally component (C), and optionally component (D) are mixed together and either undiluted or diluted with water to prepare a specified soil washing agent composition. The soil washing composition producing kit of the present invention is suitably used for preparing the soil washing composition of the present invention.

[0061] The agent containing the component (A) preferably contains the component (A) in an amount of 3% by mass or more, further 5% by mass or more, further 25% by mass or more, and 100% by mass or less, further 90% by mass or less, and may contain 100% by mass of the component (A). Furthermore, the agent containing the (B) component preferably contains 5% by mass or more of the (B) component, further 10% by mass or more, further 20% by mass or more, and 100% by mass or less, further 90% by mass or less, and may contain 100% by mass of the (B) component. Furthermore, the agent containing the component (C) preferably contains the component (C) in an amount of 5% by mass or more, further 10% by mass or more, further 20% by mass or more, and 100% by mass or less, further 90% by mass or less, and may contain 100% by mass. Furthermore, the agent containing the component (D) preferably contains 5% by mass or more, further 10% by mass or more, further 20% by mass or more, and 100% by mass or less, further 90% by mass or less of the component (D), and may contain 100% by mass.

[0062] <How to wash soil> The soil washing method of the present invention is a method for washing soil, which comprises contacting soil with a soil washing agent composition containing (A) a polyoxyalkylene alkyl or alkenyl ether having an alkyl or alkenyl group with 8 or more and 20 or less carbon atoms and an average number of oxyalkylene moles added of 3 or more and 20 or less, (B) a persulfate salt, and water. The soil washing method of the present invention may be a soil washing method in which soil is contacted with a soil washing agent composition containing the above-mentioned component (A), component (B) and water, and then a part or all of the soil washing agent composition is removed from the mixture of the soil and the soil washing agent composition, the soil washing method being performed two or more times.

[0063] In addition, the soil washing method of the present invention may be a method for washing excavated soil, which comprises carrying out two or more soil washing steps of contacting excavated soil contaminated with one or more selected from petroleum-based compounds, volatile organic compounds, and heavy metals with the soil washing agent composition, and then removing a part or all of the soil washing agent composition from a mixture of the soil and the soil washing agent composition. The matters described in the soil washing composition of the present invention can be appropriately applied to the soil washing method of the present invention. For example, specific examples and preferred aspects of the components (A), (B), (C) and (D) in the soil washing method of the present invention are the same as those in the soil washing composition of the present invention. The soil washing method of the present invention can use the soil washing composition of the present invention and / or the kit for producing the soil washing composition of the present invention.

[0064] In the soil washing method of the present invention, soil and water can be mixed, and then the components (A) and (B) can be mixed therewith. Also, in the soil washing method of the present invention, soil, an agent containing the component (A), an agent containing the component (B), and water can be mixed.

[0065] In the soil washing method of the present invention, in the mixture of soil and soil washing composition, the ratio of the soil washing composition (liquid) to soil (solid) (liquid / solid mass ratio: liquid-solid ratio) is preferably 0.5 or more, more preferably 0.7 or more, and even more preferably 0.8 or more from the viewpoint of efficient washing, and is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.2 or less, from the viewpoint of reducing washing wastewater.

[0066] In the soil washing method of the present invention, the time for contacting the soil with the soil washing agent composition is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more, from the viewpoint of washing performance, and is preferably 24 hours or less, more preferably 16 hours or less, and even more preferably 10 hours or less, from the viewpoint of work efficiency. In the soil washing method of the present invention, the mixture obtained by mixing the soil and the soil washing agent composition may be stirred and mixed. The time for stirring and mixing the mixture is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more from the viewpoint of mixing uniformity, and is preferably 2 hours or less, more preferably 1 hour or less, and even more preferably 30 minutes or less from the viewpoint of energy consumption of the stirrer.

[0067] In the soil washing method of the present invention, the amount of component (A) relative to the soil and water mixture is preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and even more preferably 0.05 mass % or more, from the viewpoint of the permeability of component (B) into the soil, and is preferably 1.0 mass % or less, more preferably 0.5 mass % or less, and even more preferably 0.3 mass % or less, from the viewpoint of treatment of washing wastewater.

[0068] In the soil washing method of the present invention, the (B) component is used in an amount of preferably 0.01 mass % or more, more preferably 0.02 mass % or more, and even more preferably 0.05 mass % or more, based on the soil and water mixture from the viewpoint of the function as a washing aid (builder), and from the viewpoints of environmental load and economic efficiency, it is preferably 1.0 mass % or less, more preferably 0.8 mass % or less, and even more preferably 0.5 mass % or less.

[0069] In the soil washing method of the present invention, the total amount of components (A) and (B) is preferably 0.02 mass% or more, more preferably 0.05 mass% or more, and preferably 2.0 mass% or less, more preferably 1.0 mass% or less, based on the mixture of soil and water.

[0070] In the soil washing method of the present invention, the amount of component (C) can be preferably 0.005 mass % or more, more preferably 0.01 mass % or more, even more preferably 0.02 mass % or more, and even more preferably 0.03 mass % or more, based on the mixture of soil and water from the viewpoint of washing power, and from the viewpoint of washing wastewater treatment, preferably 1.0 mass % or less, more preferably 0.1 mass % or less.

[0071] In the soil washing method of the present invention, component (D) can be used in an amount of preferably 0.005 mass % or more, more preferably 0.01 mass % or more, and preferably 1.0 mass % or less, more preferably 0.1 mass % or less, relative to the mixture of soil and water.

[0072] In the soil washing method of the present invention, the soil is washed at least once, preferably at least twice, and more preferably at least three times from the viewpoint of efficient washing, and preferably not more than five times from the viewpoint of treatment of recovered water.

[0073] When soil washing is performed multiple times, the soil is mixed with the soil washing composition of the present invention to bring the soil into contact with the soil washing composition of the present invention, and then a part or all of the soil washing composition is removed from the mixture of the soil and the soil washing composition. In the soil washing method of the present invention, when soil washing is performed multiple times, a mixing step of mixing the soil with the soil washing composition and a step of removing a part or all of the soil washing composition from the mixture of the soil and the soil washing composition are performed as one soil washing step, and this step is repeated two or more times.

[0074] In the soil washing method of the present invention, a separation operation between the soil and the soil washing composition can be carried out in order to remove a part or all of the soil washing composition from a mixture of the soil and the soil washing composition. Examples of the separation operation include a procedure of precipitating the soil by leaving it to stand or by centrifugation, and removing the supernatant liquid which is the soil washing composition, and a procedure of separating the soil and the soil washing composition by filtration using a mesh or the like.

[0075] The amount of the soil washing agent composition removed from the mixture of soil and the soil washing agent composition is, from the viewpoint of recontamination, preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more of the soil washing agent composition mixed with the soil, and, from the viewpoint of dehydration, is 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less.

[0076] In the method for washing soil of the present invention, rinsing of the washed soil may or may not be performed. From the viewpoint of simplifying the process, etc., the rinsing step may not be performed in the present invention.

[0077] In the soil washing method of the present invention, the excavated soil may be washed at the location where the soil exists (on-site), or at a location other than the original location (outside the site). For example, the excavated soil can be washed in a washing facility installed in a location other than the site. In this case, for example, soil collected by excavation from the site can be transferred to a washing facility installed in a location other than the site and washed. The washing facility is preferably installed near the site. For example, soil can be collected at a specified location (on-site) in a certain area, and the washing facility can be installed in a location other than the collection location in the same area. In this way, the excavated soil can be washed by installing the washing facility as a so-called on-site plant. In addition, when washing in situ, for example, the soil washing composition can be added to an excavated area and easily stirred and washed with heavy machinery (such as a backhoe or a power shovel). In this case, groundwater can be used as a part of the water in the soil washing composition.

[0078] In the soil washing method of the present invention, it is preferable to centrifuge the soil in order to remove a part or all of the soil washing composition from the mixture of the soil and the soil washing composition. The conditions for centrifugation are, for example, a centrifugal acceleration of 100 G or more and 1200 G or less, and a treatment time of 1 minute or more and 10 minutes or less. Centrifugation promotes separation of the soil and the liquid phase, making it easy to recover and reuse (backfill) the soil. If a centrifuge is not available, the mixture can be allowed to settle naturally and only the supernatant liquid can be removed. The time for allowing the mixture to settle naturally is preferably 10 minutes or more, more preferably 15 minutes or more, and even more preferably 30 minutes or more.

[0079] After washing, the soil can be reused by backfilling it in the area where it was taken or in another location. EXAMPLES

[0080] The soil washing agent compositions shown in Tables 1 and 2 were prepared using the following components. <Component (A)> C12(EO)8: Polyoxyethylene alkyl ether having 12 carbon atoms in the alkyl group and an average added mole number of oxyethylene groups of 8, manufactured by Kao Corporation C12(EO)6: Polyoxyethylene alkyl ether having 12 carbon atoms in the alkyl group and an average added mole number of oxyethylene groups of 6, manufactured by Kao Corporation C12-13(EO)7: A mixture of alkyl group carbon numbers of 12 and 13, polyoxyethylene alkyl ether with an average added mole number of oxyethylene groups of 7, manufactured by Kao Corporation <(B) component> Sodium persulfate: Sodium peroxodisulfate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. <(C) component> PEG13000: Polyethylene glycol, weight molecular weight 13,000, manufactured by Sanyo Chemical Industries, Ltd. Pluronic F-68: Polyoxyethylene-polyoxypropylene block copolymer (weight average molecular weight 10,000), product name: ADEKA Pluronic F-68, manufactured by ADEKA Corporation <(D) component> ·C12OSO3·TEA: Triethanolamine salt of alkyl sulfate ester with 12 carbon atoms in the alkyl group, manufactured by Kao Corporation

[0081] [How to evaluate cleaning performance] (1) Cleaning test (1-1) Preparation of simulated contaminated sand Commercially available river sand (Akagi Engei sand from the Watarase River in Gunma Prefecture, which had been washed, de-bittered, sieved, and selected) was dried at 105°C for more than 24 hours and cooled to room temperature. Light oil was then added to the river sand at 0.5% by mass (5000 mg / kg), mixed with a hand mixer until uniform, and left to cure at room temperature for more than 7 days to prepare simulated contaminated sand. (1-2) Evaluation of cleaning ability 50 g of the soil washing agent composition was prepared to have the composition shown in the table. However, the soil washing agent composition was prepared as a kit consisting of 40 g of washing solution A and 10 g of washing solution B, and washing solution A and washing solution B were mixed for use during washing. Washing solution A contains component (A) and, if component (C) or (D) is included, component (C) and / or component (D), with the remainder being water, and washing solution B contains component (B) and the remainder being water. 50 g of the simulated contaminated sand prepared in (1-1) was placed in a 100 ml screw tube, 40 g of cleaning solution A was added to the screw tube, and then 10 g of cleaning solution B was added. The sand was stirred and washed for 10 minutes at 20 rpm using an end-over-end rotating mixer (Rota Mix (model: RKVSD), manufactured by Tokyo Glass Machinery Co., Ltd.). After stirring, the tube was left to stand for 30 minutes, and the supernatant was removed to obtain a sample that had been washed once. Separately, washing solution A and washing solution B were added to the screw tube from which the supernatant had been removed, and the same process of stirring, leaving the tube to stand, and removing the supernatant was repeated to obtain samples that had been washed twice and three times. After removing the supernatant, the 100 ml screw tube containing the contaminated sand was dried in a 40°C oven for 7 days. Next, 50 ml of dichloromethane was added to the 100 ml screw tube containing the sample, and the mixture was stirred with a pencil mixer for 1 minute and allowed to stand for 60 minutes. After the supernatant was transferred to a 50 ml screw tube, the dichloromethane was evaporated. After the evaporation, 30 ml of n-hexane was added, and the oil in the screw tube was dissolved in n-hexane. The n-hexane was then filtered through a 0.8 μm filter (ADVANTEC DISMIC25CS080AN), and the filtrate was transferred to a precisely weighed 30 ml screw tube. After the n-hexane was evaporated from the filtrate, it was dried in a 40°C dryer for 2 hours, and the 30 ml screw tube with the extracted oil remaining was precisely weighed. The quantitative results were used to calculate the amount of diesel fuel contained in 50 g of simulated contaminated sand, and the amount of diesel fuel remaining in the simulated contaminated sand (Total Petroleum Hydrocarbon: TPH (mg / kg)) was calculated. The lower the TPH value calculated after soil washing, the better the soil washing ability of the soil washing agent composition. In Comparative Example 1-3 in Table 1, the concentration of the surfactant (A) component was increased, but the TPH value did not decrease. This is thought to be because the surfactant contained in the pore water in the soil is calculated as TPH.

[0082] [Table 1]

[0083] [Table 2]

Claims

1. A method for cleaning soil, comprising contacting a soil cleaning agent composition containing: (A) a polyoxyalkylene alkyl or alkenyl ether in which the alkyl or alkenyl group has 8 to 20 carbon atoms and the average number of moles of oxyalkylene added is 3 to 20 (hereinafter referred to as component (A)), (B) a persulfate (hereinafter referred to as component (B)), and water, with the soil.

2. The method for cleaning soil according to claim 1, wherein a mixture of the soil and the soil cleaning agent composition is stirred and mixed.

3. The method for cleaning soil according to claim 1 or 2, wherein the mass ratio (A) / (B) of the content of component (A) to the content of component (B) is 10 / 90 or more and 90 / 10 or less.

4. The method for cleaning soil according to claim 1 or 2, wherein the soil cleaning agent composition contains component (A) in an amount of 0.01% by mass or more and 0.5% by mass or less.

5. The method for cleaning soil according to claim 1 or 2, wherein the soil cleaning agent composition contains component (B) in an amount of 0.01% by mass or more and 1.0% by mass or less.

6. The method for cleaning soil according to claim 1 or 2, further comprising (C) a nonionic polymer compound having a weight average molecular weight of 3,000 or more and 1,000,000 or less (excluding component (A)) (hereinafter referred to as component (C)).

7. The method for cleaning soil according to claim 6, wherein component (C) is one or more selected from polyethylene glycol, polypropylene glycol, and polyoxyethylene polyoxypropylene copolymer.

8. The method for cleaning soil according to claim 6, wherein the mass ratio (A) / (C) of the content of component (A) to the content of component (C) is 30 / 70 or more and 99 / 1 or less.

9. The method for cleaning soil according to claim 1 or 2, further comprising (D) an anionic surfactant.

10. Contacting the soil with the soil cleaning agent composition and removing part or all of the soil cleaning agent composition from the mixture of the soil and the soil cleaning agent composition, and performing the cleaning of the soil two or more times. The method for cleaning soil according to claim 1 or 2.

11. The soil is soil contaminated with one or more selected from petroleum-based compounds, volatile organic compounds, and heavy metals. The method for cleaning soil according to claim 1 or 2.

12. A soil cleaning agent composition containing (A) a polyoxyalkylene alkyl or alkenyl ether having an alkyl or alkenyl group with 8 to 20 carbon atoms and an average addition mole number of oxyalkylene of 3 to 20, (B) a persulfate, and water.

13. A kit for producing a soil cleaning agent composition for producing the soil cleaning agent composition according to claim 12, A kit containing an agent containing component (A) and an agent containing component (B) in a state where they are not mixed with each other.