KR102065312B1 - Method of purifying soil contaminated with persistent organic pollutants - Google Patents

Abstract

The present invention relates to a method for purifying soil contaminated with residual organic pollutants by incineration after mixing a composition for an eluent. To this end, the method comprises the following steps: (step 1) injecting a composition for an eluent containing hydrogen peroxide, persulfate, a surfactant, an antioxidant and an organic solvent in the contaminated soil and then stirring the same; (step 2) separating the composition for an eluent from contaminated soil; and (step 3) incinerating the contaminated soil from which the composition for an eluent is separated.

Description

Method of purifying soil contaminated with persistent organic pollutants

The present invention relates to a method of purifying soil contaminated with residual organic pollutants by incineration after mixing the composition for the eluent.

Soil pollution refers to a phenomenon in which pollutants penetrate underground, and contaminate the lipids, and refers to a phenomenon in which not only soil but also groundwater or underground air exist in the lipid. Recently, the importance of the soil environment, which is affected by the development project, is increasing due to the severity of soil and groundwater pollution caused by waste and harmful chemicals caused by population growth and industrial development around the world.

Conventionally, the method of purifying contaminated soil can be classified into incineration method, advanced oxidation treatment method, biological treatment method and basic alkali treatment method.

Among them, the incineration treatment method incinerates contaminated soil at a high temperature of about 800 ° C. or more to decompose contaminants contained in the soil, and thus has an advantage of high treatment efficiency. However, there is a problem that it is almost impossible to transfer thermal energy to all pollutants when the amount of purified soil is increased or when the temperature in the incinerator is low.

In addition, the advanced oxidation treatment method, such as Fenton reaction, Photo assisted Fenton, photocatalytic reaction, and the like to produce and decompose the most powerful oxidizer hydroxyl group in this regard in the Republic of Korea Patent No. 10-1275378 and the hydrogen peroxide, persulfate and Disclosed is a method for purifying complex soil using a reactant containing an organic acid. This method has a disadvantage in that the process proceeds rapidly and shows excellent decomposition efficiency, but consumes a large amount of hydrogen peroxide due to rapid generation of hydroxide radicals, and thus requires a lot of chemicals.

In order to solve the drawbacks of the incineration method and advanced oxidation treatment method, the present inventors prepared a composition for the eluent comprising a surfactant, antioxidant and organic solvent and incineration to inject it into the soil, hydrogen peroxide By stabilizing the water and controlling the reaction rate, we have developed a method of purifying contaminated soil that reduces hydrogen peroxide consumption and further penetrates the eluent composition to deep pores in soil particles and completely removes organic pollutants in the pores. .

Republic of Korea Patent Application Publication No. 10-2012-0070283 (Invention name: Method and treatment agent for contaminated soil using quasi-Fenton reaction with stabilizer, Applicant: Kwangwoon University Industry-Academic Cooperation Foundation, Publication Date: June 29, 2012) Republic of Korea Patent No. 10-1275378 (Invention name: Hybrid purification method using in situ complex soil stirring, Applicant: Kolon Water & Energy Co., Ltd., registered date: June 10, 2013)

An object of the present invention is to provide a composition for the eluent which can reduce the consumption of hydrogen peroxide by controlling the rate of generation of hydroxyl radicals by the Fenton reaction.

In addition, another object of the present invention is to provide a method for purifying soil contaminated with persistent organic pollutants that can remove the organic pollutants remaining in the soil void by incineration after the composition for the eluent containing the organic solvent. It's there.

The method of purifying soil contaminated with the residual organic pollutants of the present invention includes (1 step) adding and stirring a composition for the eluent comprising hydrogen peroxide, persulfate, a surfactant, an antioxidant, and an organic solvent to the contaminated soil;

(Step 2) separating the eluent composition from the contaminated soil; And

(Step 3) incineration of the contaminated soil in the composition for the eluent; characterized in that it comprises a.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the composition for the eluent is 50 to 70 parts by weight of persulfate, based on 100 parts by weight of hydrogen peroxide, surfactant 1 ~ 10 Parts by weight, 0.5 to 5 parts by weight of antioxidant and 100 to 200 parts by weight of organic solvent may be mixed.

In this case, the persulfate may be at least one selected from the group consisting of sodium persulfate, potassium persulfate and ammonium persulfate.

The surfactant may be an anionic surfactant, preferably the anionic surfactant is sodium lauryl sulfate, sodium lauryl ether sulfate, linear alkylbenzene sulfonate, monoalkyl phosphate, acyl isionate, alkyl glycerol It may be one or more selected from the group consisting of arylethersulfonate, acyl glutamate, acyl taurate and fatty acid metal salts.

The antioxidant may be octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

The organic solvent is methanol, ethanol, isopropanol, tetrahydrofuran, N-methylpyrrolidinone, cyclohexylpyrrolidinone, N-octylpyrrolidinone, N-phenylpyrrolidinone, methyl formate, dimethyl formamide , Dimethyl sulfoxide, diethyl ether, phenoxy-2-propanol, propriophenone, ethyl lactate, ethyl acetate, ethyl benzoate, acetonitrile, acetone, ethylene glycol, propylene glycol, dioxane It may be at least one member selected from the group consisting of saline, butyryl lactone, butylene carbonate, ethylene carbonate, propylene carbonate and dipropylene glycol.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the composition for the eluent may be mixed 200 to 300 parts by weight based on 100 parts by weight of contaminated soil.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the agitation may be performed for 1 to 3 hours.

In the above three steps of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, incineration may be performed at 800 ~ 1200 ℃.

Hereinafter, the present invention will be described in detail.

In order to achieve the above object, the method of purifying soil contaminated with persistent organic pollutants of the present invention includes (1 step) an eluent composition comprising hydrogen peroxide, persulfate, surfactant, antioxidant and organic solvent in contaminated soil. Dosing and stirring;

(Step 2) separating the eluent composition from the contaminated soil; And

(Step 3) incineration of the soil contaminated with the composition for the eluent; includes.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the contaminated soil may be soil contaminated with general persistent organic pollutants, for example, polychlorinated biphenyl ( Polychlorinated biphenyls (PCBs), organochlorine pesticides, hexachlorobenzene, dioxins, poly aromatic hydrocarbons (PAHs) and the like may be contaminated with, but are not limited thereto.

In the first step of the method of purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the hydrogen peroxide is a compound having a strong oxidation power of a compound of hydrogen and oxygen to weaken by dissociating hydrogen ions in aqueous solution. It has an acidic nature. It is a strong oxidant and at the same time has a weak reducing agent function. Hydrogen peroxide has the property of generating free radicals in the presence of neutral or acidic low oxidizing metal ions. Oxidation process using hydrogen peroxide is a kind of Advanced Oxidation Process (AOP). When hydrogen peroxide is activated, OH radicals (hydroxyl radicals) are generated, and they have a very high redox potential to oxidize hardly decomposable organics. In other words, hydrogen peroxide injected into the contaminated soil reacts with metal salts in the soil to produce hydroxyl radicals and metal oxides (Fenton's oxidation reactants) .The resulting hydroxyl radicals are very powerful oxidants, which oxidize and decompose organic pollutants. do. On the other hand, the resulting metal oxide reacts with the surfactant contained in the composition for the eluent to form a complex.

The persulfate serves as an oxidizing agent, and the persulfate may be at least one selected from the group consisting of sodium persulfate, potassium persulfate, and ammonium persulfate. . The persulfate may generate SO ₄ radicals having strong oxidizing power by light, metal, etc., in addition to heat, thereby oxidizing organic pollutants. In addition, the persulfate may include 50 to 70 parts by weight based on 100 parts by weight of hydrogen peroxide. If the content of persulfate is less than 50 parts by weight with respect to 100 parts by weight of hydrogen peroxide, the organic pollutant purification effect from the soil is insufficient, if it exceeds 70 parts by weight it is not preferable because the stability can be reduced due to excessive radical generation.

Surfactants are generally amphoteric substances with hydrophilic and hydrophobic groups in their molecules. These surfactants not only lower the free energy of the interface, but also dramatically change the properties of the interface and are chemically capable of dissolving substances with low solubility in water in a thermodynamically stable state. It is a substance. Such surfactants are categorized into cationic surfactants, anionic surfactants, nonionic surfactants and amphoteric surfactants according to the type of hydrophilic functional group. The surfactants included in the eluent composition of the present invention are preferably anionic surfactants. It may be an activator. The anionic surfactants can be used without limitation as long as they are generally used anionic surfactant compounds. Carboxylate compounds such as soaps, higher alcohols, higher alkyl ethers, sulfate ester compounds sulphated olefins, sulfate compounds including alkylbenzensulfonate, higher Alcohol phosphate compounds may be, but are not limited to, sodium lauryl sulfate (SLS), sodium lauryl sulfate (SLES), linear alkylbenzenesulfonate (linear) alkylbenzene sulforlate (LAS), mono alkyl phosphate (MAP), acyl isethionate (SCI), alkyl glyceryl ether sulfonate (AGES), acyl glutamate , Acyl taurate and fatty acid metal salt may be one or more selected from the group consisting of Preferably sodium lauryl sulfate, sodium lauryl ether sulfate, linear alkylbenzene sulfonate or acyl isethionate. When the hydrogen peroxide is treated in the presence of the anionic surfactant, as described above, the fenton oxide reactant forms a complex with the anionic surfactant, and the formed complex delays the reaction rate of the hydrogen peroxide and the metal salt. In other words, by delaying the decomposition rate of hydrogen peroxide, it serves as a stabilizer to lower the consumption rate of hydrogen peroxide, thereby preventing the rapid generation of hydroxyl radicals. Therefore, it is possible to prevent the rapid consumption of hydrogen peroxide, and the overall pollution treatment process is stabilized by improving the stability of hydrogen peroxide, it is possible to maintain the contaminant decomposition effect for a longer time. The surfactant may be included in 1 to 10 parts by weight based on 100 parts by weight of hydrogen peroxide. When the content of the surfactant is less than 1 part by weight based on 100 parts by weight of hydrogen peroxide, the effect of delaying the decomposition rate of hydrogen peroxide is insignificant, and when it exceeds 10 parts by weight, it is not preferable because it is disadvantageous in terms of economy.

Antioxidants prevent attack by the hydroxyl radicals produced by hydrogen peroxide, and increase the stability of hydrogen peroxide and control the rate of hydroxyl radical formation. As such antioxidants, aryl esters, benzoates, phenols, and amine compounds are known. However, the antioxidants of the present invention are excellent in octadecyl-3- (3,5). -Di-tert-butyl-4-hydroxyphenyl) propionate is preferably used. In addition, the antioxidant may be contained 0.5 to 5 parts by weight based on 100 parts by weight of hydrogen peroxide. If the amount of antioxidant is less than 0.5 parts by weight based on 100 parts by weight of hydrogen peroxide, the stabilizing effect of hydrogen peroxide is lowered, there is a problem that the consumption of hydrogen peroxide is increased due to the generation of excessive radicals, and if it exceeds 5 parts by weight of organic pollutants and residual It is not desirable that the antioxidants compete with each other in the radical reaction, and thus the efficiency of treating organic pollutants can be reduced.

The organic solvent is to improve the absorption of the eluent composition into the soil by moistening the surface of the contaminated soil, and also to penetrate the eluent composition into the soil pores, the organic solvent is methanol, ethanol, isopropanol , Tetrahydrofuran, N-methylpyrrolidinone, cyclohexylpyrrolidinone, N-octylpyrrolidinone, N-phenylpyrrolidinone, methyl formate, dimethyl formamide, dimethyl sulfoxide, diethyl ether, Phenoxy-2-propanol, propriophenone, ethyl lactate, ethyl acetate, ethyl benzoate, acetonitrile, acetone, ethylene glycol, propylene glycol, dioxane, butyryl lactone, butylene carbonate It may be at least one selected from the group consisting of ethylene carbonate, propylene carbonate and dipropylene glycol. In addition, the organic solvent may include 100 to 200 parts by weight based on 100 parts by weight of hydrogen peroxide. If the content of the organic solvent is less than 100 parts by weight with respect to 100 parts by weight of hydrogen peroxide, it is difficult to evenly penetrate the composition for the eluent in the soil voids, and if it exceeds 200 parts by weight it is economical because it requires a lot of energy when incineration treatment Unfavorable in terms of disadvantage.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the composition for the eluent may be injected by underground injection or spraying, but is not limited thereto. Depending on the characteristics of the appropriate method can be selected by injection. The underground injection method is to dig the soil contaminated with the residual organic pollutants to a certain depth and embed the pipe to inject the composition for the eluent, and then the composition is directly injected into the soil through the pipe, and the spraying method is to spray the liquid. The device can be used to spread the composition for the eluent on contaminated soil.

In the first step of the method for purifying soil contaminated with residual organic pollutants according to an embodiment of the present invention, the composition for the eluent is preferably injected 200 ~ 300 parts by weight based on 100 parts by weight of contaminated soil. If the composition for the eluent is less than 200 parts by weight based on 100 parts by weight of contaminated soil, the composition for the eluent is not sufficiently supplied to the soil, and if it exceeds 300 parts by weight, it requires a lot of energy when incinerated due to excessive solution. It is not preferable to disadvantage in economic terms.

In the first step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the stirring is to maximize the contact between the contaminated soil and the composition for the eluent for the eluent to deep pores in the soil particles Most organic pollutants in the soil may be transferred to the composition for the eluent through the stirring to move the composition. Such agitation may be performed in situ (In-Situ) underground stirring, but is not limited thereto. The stirring is preferably performed for 1 to 3 hours. When the stirring time is less than 1 hour, the composition for the eluent may not be moved to the pores in the soil particles, and thus organic contaminants may not be completely removed.

In the second step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the composition for the eluent may be separated from the contaminated soil through a supernatant separation technique or a filter technique, separation method Is not limited thereto. In this case, the composition for the eluent not separated from the organic pollutants that have not yet been removed may remain in the soil.

In the third step of the method for purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention, the incineration is to completely treat the organic pollutants remaining in the soil, and is delivered to the inside of the pores of the soil. The organic solvent is burned due to the high heat, and the residual organic pollutants remaining in the surrounding area are also incinerated to completely remove the remaining organic pollutants and the eluent composition in the soil. Such incineration is preferably performed at 800 to 1200 ° C. for 0.5 to 1 hour. If the incineration temperature is less than 800 ° C. or the execution time is less than 0.5 hour, the organic solvent is not sufficiently burned so that the organic pollutants remaining in the soil are completely treated. If the incineration temperature exceeds 1200 ℃ or the running time exceeds 1 hour, it is not preferable because it is disadvantageous in terms of economics.

By including a surfactant and an antioxidant through the method of purifying soil contaminated with the persistent organic pollutants of the present invention, it is possible to stabilize the hydrogen peroxide and control the rate of radical generation of radicals, thereby reducing the consumption of hydrogen peroxide. Can be disassembled.

In addition, the method of purifying soil contaminated with the residual organic pollutants of the present invention is a process of incineration after inputting the composition for the eluent containing the organic solvent can be added to the composition for the eluent to the deep pores of the contaminated soil. In addition, it is possible to remove organic pollutants remaining in the deep voids, and thus to clean up more than 99% of the contaminated soil.

1 is a flow chart showing a method of purifying soil contaminated with persistent organic pollutants according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, it is provided to fully convey the spirit of the present invention to those skilled in the art so that the contents introduced herein are thoroughly and completely.

[Production Examples 1 to 4 and Comparative Production Examples 1 to 3]

Hydrogen peroxide, sodium persulfate as persulfate, sodium lauryl sulfate as anionic surfactant, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as antioxidant and hexane as organic solvent To prepare a composition for the eluent by mixing, the content of each component was prepared with reference to Table 1 below.

Hydrogen peroxide
(g) Persulfate
(g) Surfactants
(g) Antioxidant
(g) Organic solvent
(g) Preparation Example 1 100 60 One 5 154 Preparation Example 2 100 50 10 5 155 Preparation Example 3 100 70 10 5 100 Preparation Example 4 100 50 One 0.5 200 Comparative Production Example 1 100 100 10 5 50 Comparative Production Example 2 100 60 One 0.1 160 Comparative Production Example 3 100 65 0.5 5 149.5

[Comparative Production Example 4]

Prepare a composition for the eluent in the same manner as in Preparation Example 1, but using benzoate instead of octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate as an antioxidant The composition for the preparation was prepared.

Example 1

Contaminated soil production: First, 2 g of sand (WHITE QUARTZ, -50 + 70 MESH) was added to a 40 ml volume borosilicate glass vial, and then 500 ppm of hexane was added to the prepared sand. 0.5 ml of dissolved PAH (phenanthrene) solution was injected and contaminated, and the resultant was left at room temperature for about 24 hours to evaporate all hexane to produce artificially contaminated soil.

Eluent composition input and stirring: 200 g of the eluent composition of Preparation Example 1 was added to 100 g of the artificially prepared contaminated soil, followed by stirring for 2 hours.

Separation and incineration of the composition for the eluent: After separating the eluent composition from the contaminated soil through the supernatant separation technique, heat of 1000 ° C. is removed to remove the organic contaminants and the composition for the eluent not yet removed in the soil. Incineration was performed for 30 minutes.

[Examples 2 to 6 and Comparative Examples 1 to 8]

Purifying soil in the same manner as in Example 1, but was carried out with reference to the detailed conditions of Table 2.

pollution
soil
(g) Eluent Composition (g) Stirring
time
(hr) incineration
Temperature
(℃) Production Example Comparative Production Example One 2 3 4 One 2 3 4 Example 1 100 200 - - - - - - - 2 1000 Example 2 100 250 - - - - - - - 2 1000 Example 3 100 300 - - - - - - - 2 1000 Example 4 100 - 250 - - - - - - 2 1000 Example 5 100 - - 250 - - - - - 2 1000 Example 6 100 - - - 250 - - - - 2 1000 Comparative Example 1 100 - - - - 250 - - - 2 1000 Comparative Example 2 100 - - - - - 250 - - 2 1000 Comparative Example 3 100 - - - - - - 250 - 2 1000 Comparative Example 4 100 - - - - - - - 250 2 1000 Comparative Example 5 100 150 - - - - - - - 2 1000 Comparative Example 6 100 350 - - - - - - - 2 1000 Comparative Example 7 100 250 - - - - - - - 0.5 1000 Comparative Example 8 100 250 - - - - - - - 2 500

[Evaluation Example. Pollutant concentration measurement]

The concentrations of the contaminants (PAH) contained in the soils purified in Examples 1 to 6 and Comparative Examples 1 to 8 were measured through high performance liquid chromatography (HPLC), respectively. The concentration of PAH, which is a contaminant, was injected into a small amount of acetone into the test body, and the PAH was extracted with acetone by applying vibration to the test body using an ultrasonic cleaner, and the concentration was measured by HPLC. It was measured in a way that. More specifically, 19 mL of acetone was added to a contaminated vial to make a total volume of 20 mL, and diluted 20 times. After the vibration was applied for 2 hours with an ultrasonic cleaner, PAH was extracted with acetone, and measured by HPLC for about 5 minutes. The results are shown in Table 3 below. At this time, the initial concentration of contaminants in the contaminated soil used in Examples and Comparative Examples was 125 mg / kg.

PAH concentration (mg / kg) Example 1 0.98 Example 2 0.95 Example 3 0.94 Example 4 0.85 Example 5 0.97 Example 6 0.81 Comparative Example 1 16.84 Comparative Example 2 11.23 Comparative Example 3 15.56 Comparative Example 4 9.23 Comparative Example 5 32.47 Comparative Example 6 10.58 Comparative Example 7 29.10 Comparative Example 8 25.62

Referring to Table 3, it is confirmed that the soil purified by the embodiment of the present invention is almost no contaminants compared to Comparative Examples 1 to 8.

In particular, in Comparative Example 1, Comparative Example 5 and Comparative Example 7, the eluent composition was not uniformly supplied into the soil, and contaminants remaining in the pores were detected. In Comparative Examples 2 to 4, hydrogen peroxide was exhausted at the beginning of the reaction. Contaminants were not sufficiently reduced. In addition, in Comparative Examples 6 and 8, due to the excessive composition of the eluent or less than the incineration temperature, the eluent composition remaining in the soil was not sufficiently incinerated and contaminants could not be completely removed.

Accordingly, the present invention can be economically decomposed organic pollutants due to the low consumption of hydrogen peroxide, and can remove 99% or more of organic pollutants remaining in the pores.

Claims (11)

(Step 1) adding and stirring the composition for the eluent containing hydrogen peroxide, persulfate, anionic surfactant, antioxidant and organic solvent to the contaminated soil;
(Step 2) separating the eluent composition from the contaminated soil; And
(Step 3) incineration of the soil contaminated with the composition for the eluent; includes;
The eluent composition is characterized in that 50 to 70 parts by weight of persulfate, 1 to 10 parts by weight of anionic surfactant, 0.5 to 5 parts by weight of antioxidant and 100 to 200 parts by weight of organic solvent are mixed based on 100 parts by weight of hydrogen peroxide. With
The antioxidant is octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate,
The anionic surfactants include sodium lauryl sulfate, sodium lauryl ether sulfate, linear alkylbenzene sulfonate, monoalkyl phosphate, acyl isionate, alkyl glyceryl ether sulfonate, acyl glutamate, acyl taurate and fatty acid metal salts. A method for purifying soil contaminated with persistent organic pollutants that is one or more selected from the group consisting of: The method of claim 1,
The persulfate is a method for purifying soil contaminated with persistent organic pollutants, characterized in that at least one selected from the group consisting of sodium persulfate, potassium persulfate and ammonium persulfate. delete delete delete The method of claim 1,
The organic solvent is methanol, ethanol, isopropanol, hexane, tetrahydrofuran, N-methylpyrrolidinone, cyclohexylpyrrolidinone, N-octylpyrrolidinone, N-phenylpyrrolidinone, methyl formate, dimethyl Formamide, dimethylsulfoxide, diethyl ether, phenoxy-2-propanol, propriophenone, ethyl lactate, ethyl acetate, ethyl benzoate, acetonitrile, acetone, ethylene glycol, propylene glycol And dioxane, butyryl lactone, butylene carbonate, ethylene carbonate, propylene carbonate and dipropylene glycol. The method of purifying soil contaminated with persistent organic pollutants, characterized in that at least one member. delete The method of claim 1,
The method of claim 1, wherein the composition for the eluent is 200 to 300 parts by weight based on 100 parts by weight of contaminated soil, characterized in that the cleaning method of soil contaminated with persistent organic pollutants. The method of claim 1,
Stirring in the first step is a method for purifying soil contaminated with persistent organic pollutants, characterized in that performed for 1 to 3 hours. The method of claim 1,
Incineration in the third step is a method for purifying soil contaminated with persistent organic pollutants, characterized in that carried out at 800 ~ 1200 ℃. The method of claim 1,
Incineration in step 3 is a method for purifying soil contaminated with persistent organic pollutants, characterized in that performed for 0.5 to 1 hour.

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