A method for repairing soil contaminated by petroleum hydrocarbons

Abstract

The present invention discloses a method for repairing soil contaminated by petroleum hydrocarbons, comprising: S1. mixing the contaminated soil containing petroleum hydrocarbons to be treated with a mixed surfactant, and eluting by initial oscillation; S2. adding a petroleum hydrocarbon separating agent, and performing secondary oscillation elution; S3. repeating multiple oscillation elutions, so that the oil in the soil is stripped from the soil and floats to the surface of the solution; S4. washing and settling, and repeating the operation until the content of petroleum hydrocarbons in the soil reaches the national control standard for soil for construction land. The present invention utilizes fluorocarbon surfactants and bio-based degradable foam materials to jointly repair soil contaminated by petroleum hydrocarbons. It is a low-cost and efficient treatment technology. It utilizes the adsorption effect of bio-based degradable foam materials, and combines mixed surfactants to enhance the solubilization of petroleum hydrocarbon organic pollutants in the soil, and improves the solubility of soil pollutants in the water phase, so as to improve the efficiency of soil remediation. It has the characteristics of low investment, low cost, simple operation and large-scale promotion.

Description

Technical Field

[0001] The invention relates to a method for repairing contaminated soil, in particular to a method for repairing soil contaminated by petroleum hydrocarbons. Background Art

[0002] With the advancement of ecological civilization construction, the environment of mountains, rivers, forests, fields, lakes, grasslands and sands has received more and more attention. Soil is the core carrier of the ecological environment system. Organic pollutants in the soil (such as pesticides, petroleum hydrocarbons, polychlorinated biphenyls, etc.) will destroy the normal operation of the soil-plant system, thereby affecting the functional degradation and ecological safety of the entire food chain. Therefore, it is necessary to develop practical technologies for economical, efficient and safe soil pollution remediation to ensure the safety of the ecosystem with soil as the carrier and realize the sustainable use of land resources.

[0003] For soil contaminated by petroleum hydrocarbons, the environmental stress level is very high, and there is a huge practical need to restore its ecological functions and reuse it. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for repairing soil contaminated by petroleum hydrocarbons. The method uses bio-based degradable foam materials and mixed surfactants to jointly repair soil contaminated by petroleum hydrocarbons, which is of great significance to the prevention and control of soil petroleum hydrocarbon pollution and soil ecological safety, and the management and repair of such soils.

[0005] To achieve the above object, the present invention provides a method for repairing petroleum hydrocarbon contaminated soil, comprising the following steps:

[0006] S1. The contaminated soil containing petroleum hydrocarbons to be treated is mixed with a mixed surfactant and initially oscillated and eluted;

[0007] S2. Add petroleum hydrocarbon separation agent and perform secondary oscillation elution;

[0008] S3. Repeat the oscillation elution several times so that the oil in the soil is stripped from the soil and floats to the surface of the solution;

[0009] S4. After washing and sedimentation, the operation is repeated until the petroleum hydrocarbon content in the soil reaches the national control standard for soil for construction land.

[0010] Furthermore, the mixed surfactant is a mixture of a low interfacial tension surfactant and a fluorocarbon surfactant.

[0011] Furthermore, the mixing ratio of the low interfacial tension surfactant to the fluorocarbon surfactant is 1:1.8.

[0012] Furthermore, the usage amount of the mixed surfactant relative to the weight of the soil is 60-80 mg / kg.

[0013] Furthermore, the mixed surfactant is applied to the 0-20 cm surface soil of the contaminated soil.

[0014] Furthermore, the petroleum hydrocarbon separation agent is a mixture of a surfactant and a bio-based degradable foam.

[0015] Furthermore, the usage amount of the bio-based degradable foam is 0.1 kg / m2.

[0016] Furthermore, during the remediation process of the contaminated soil, the moisture content of the topsoil is maintained at 60-65%.

[0017] Furthermore, the bio-based degradable foam is made from lignin as a raw material.

[0018] Furthermore, the elution experiment was carried out by reciprocating oscillation in a constant temperature water bath oscillator to allow the contaminated soil and the mixed surfactant to be fully contacted and mixed.

[0019] The present invention utilizes fluorocarbon surfactants and bio-based degradable foam materials to jointly repair petroleum hydrocarbon contaminated soil. It is a low-cost, high-efficiency treatment technology that utilizes the adsorption effect of bio-based degradable foam materials and combines mixed surfactants to enhance the solubilization of petroleum hydrocarbon organic pollutants in the soil, thereby increasing the solubility of soil pollutants in the water phase to improve soil remediation efficiency. It has the characteristics of low investment, low cost, simple operation and the ability to be promoted over a large area. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the surface tension test diagram of mixed surfactants;

[0021] Figure 2 The removal rate of petroleum hydrocarbons in soil treated by mixed surfactants and degradable foam materials. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0026] like Figure 1 , Figure 2 As shown, the present invention provides a method for repairing petroleum hydrocarbon contaminated soil, which uses ex situ elution repair to treat the petroleum hydrocarbon contaminated soil, including the following process:

[0027] S1. The contaminated soil containing petroleum hydrocarbons to be treated is mixed with a mixed surfactant and initially oscillated and eluted;

[0028] A mixed surfactant is applied to the 0-20 cm surface soil of the contaminated soil, and the amount of the mixed surfactant used relative to the weight of the soil is 60-80 mg / kg.

[0029] 2. The mixed surfactant is a mixture of a low interfacial tension surfactant and a fluorocarbon surfactant. The low interfacial tension surfactant is a phospholipid surfactant with an interfacial tension of less than 10-3mN / m, and is composed of a hydrophilic head group, an amphiphilic glycerol lipid and a hydrophobic alkyl group; the specific component of the fluorocarbon surfactant is a fluorocarbon tail olefin compound. Among them, the mixing ratio of the low interfacial tension surfactant to the fluorocarbon surfactant is 1:1.8.

[0030] S2. Add petroleum hydrocarbon separation agent and perform secondary oscillation elution;

[0031] The petroleum hydrocarbon separation agent is a mixture of surfactant and bio-based degradable foam. Among them, the surfactant is a phospholipid surfactant, the interfacial tension is less than 10-3mN / m, and it is composed of a hydrophilic head group, an amphiphilic glycerol lipid and a hydrophobic alkyl group; the specific component of the mixture of bio-based degradable foam is lignin-based polyurethane foam. The usage of bio-based degradable foam is 0.1kg / m 2 .

[0032] S3. Repeat the oscillation elution several times so that the oil in the soil is stripped from the soil and floats to the surface of the solution;

[0033] S4. During the treatment process, according to the soil moisture characteristic curve, the moisture content of the topsoil is maintained at 60-65%. The moisture content of the topsoil is easy for petroleum hydrocarbons to separate from the soil adsorption floccules. The content of petroleum hydrocarbons in the soil is monitored regularly. After half a month, the above operation can be repeated according to the monitoring results. After multiple washing and sedimentation, the operation is repeated until the content of petroleum hydrocarbons in the soil reaches the national control standard for soil for construction land.

[0034] Example: Remediation of petroleum hydrocarbon contaminated soil in oil well operation area

[0035] The specific implementation steps are as follows:

[0036] 1) Prepare degradable foam material. The degradable foam material uses lignin as the main raw material, is degradable, and has a formation unit of 8-10g / kg.

[0037] The bio-based degradable foam is made of lignin as a raw material. Lignin-based polyurethane foam is first synthesized, and then polydopamine particles are deposited on the foam surface by in-situ polymerization under weak alkaline conditions to increase its surface roughness. The foam is then modified with phytic acid to achieve surface super-hydrophilicity and underwater super-oleophobicity.

[0038] 2) preparing a mixed surfactant, wherein the mixed surfactant used is a mixture of a low interfacial tension surfactant and a fluorocarbon surfactant, and the mixing ratio thereof is 1:1.8.

[0039] 3) The experimental site is the Gaoyang mining area of ​​the North China Oilfield. The experimental area is set to 2m*2m. Petroleum hydrocarbon-containing soil is collected, and the content of petroleum hydrocarbons is 145-1680mg / kg. The mixed surfactant is quantitatively added into a 150mL glass conical bottle, and the elution experiment is carried out by reciprocating oscillation in a constant temperature water bath oscillator to make the contaminated soil and the mixed surfactant fully contact and mix. After 60 minutes of oscillation, it is allowed to stand and settle for 12 hours, so that the crude oil in the soil is stripped from the soil and floats to the surface of the solution. After washing and settling, the material is transferred into a 100mL centrifuge tube and centrifuged at a speed of 5000r / min for 10 minutes. After that, the material is allowed to stand to remove the liquid phase solution.

[0040] The solid soil at the bottom of the centrifuge tube was taken out and placed in a drying oven, and dried at 105°C. The petroleum hydrocarbon content in the eluted soil was analyzed by infrared method, and the petroleum hydrocarbon removal rate was calculated at the same time. After the mixed surfactant and degradable foam material were combined, the petroleum hydrocarbon removal rate was as follows: Figure 2 shown.

[0041] The main components of the mixed surfactant are a mixture of low interfacial tension surfactant and fluorocarbon surfactant, with a mixing ratio of 1:1.8, and the surface tension reaches the best effect; under the combined action of surfactant and degradable foam material, the removal rate of petroleum hydrocarbons in the soil gradually decreases with the increase of treatment time (1h, 2h, 4h, 8h, 12h, 24h), and reaches the highest removal rate of 92.3% after 4 hours of treatment. By controlling the elution time, the soil contaminated by oil sludge is eluted. The experimental results show that the longer the elution time, the better the effect. On the contrary, as the elution time increases, the petroleum hydrocarbons solubilized in the surfactant micelles will escape back into the soil solid phase, which reduces the elution efficiency.

[0042] Judging from the residual petroleum hydrocarbons in the treated soil, the appropriate dosage of surfactant is 60-80 mg / kg and that of degradable foam material is 10 g / kg.

[0043] Figure 1 This is the surface tension test diagram of the mixed surfactant. The removal rate of petroleum hydrocarbons in the soil treated by the mixed surfactant and degradable foam material is shown in Figure 2 Taking into account the restoration effect and cost, the bio-based degradable foam material and the mixed surfactant were used to repair the petroleum hydrocarbon contaminated soil. In this embodiment, after 4 hours of elution treatment, the surfactant dosage was within the range of 60-80 mg / kg and the degradable foam material dosage was 8-10 g / kg, reaching the highest removal rate of 92.3%.

[0044] The advantages and effects of the present invention are:

[0045] The method for repairing petroleum hydrocarbon-contaminated soil by combining a degradable foam material and a mixed surfactant adopted by the present invention utilizes the adsorption effect of the degradable foam material on petroleum hydrocarbons and combines the solubilization effect of the mixed surfactant on pollutants. The efficiency enhancement after compounding the degradable foam material is most significant, and the elution efficiency is increased by 21.5% compared with the case of a single action, thereby achieving the purpose of removing petroleum hydrocarbons in the soil, saving the subsequent oily wastewater treatment cost, and avoiding a large amount of sewage discharge. The method is particularly suitable for oil fields or remote areas far away from supporting infrastructure, has the advantages of low cost, rapid adsorption, strong operability, and good repair effect, has important theoretical and practical significance for the prevention and control of soil petroleum hydrocarbon pollution and the functional guarantee of the soil ecological environment, and has important guiding significance for the management and repair of such soil in my country.

Claims

1. A method for remediating soil contaminated by petroleum hydrocarbons, characterized in that: The method comprises the following steps: S1. The contaminated soil containing petroleum hydrocarbons to be treated is mixed with a mixed surfactant and initially oscillated and eluted; S2. Add petroleum hydrocarbon separation agent and perform secondary oscillation elution; S3. Repeat the oscillation elution several times so that the oil in the soil is stripped from the soil and floats to the surface of the solution; S4. After washing and settling, the operation is repeated until the petroleum hydrocarbon content in the soil reaches the national control standard for construction land soil; The mixed surfactant is a mixture of a low interfacial tension surfactant and a fluorocarbon surfactant, the low interfacial tension surfactant is a phospholipid surfactant, and the interfacial tension is less than 10-3mN / m; the specific component of the fluorocarbon surfactant is a fluorocarbon tail olefin compound; Wherein, the mixing ratio of the low interfacial tension surfactant to the fluorocarbon surfactant is 1:1.8; The petroleum hydrocarbon separation agent is a mixture of a surfactant and a bio-based degradable foam; The bio-based degradable foam is made from lignin as a raw material.

2. The method for remediating petroleum hydrocarbon contaminated soil according to claim 1, characterized in that: The usage amount of the mixed surfactant relative to the weight of the soil is 60-80 mg / kg.

3. The method for remediating petroleum hydrocarbon contaminated soil according to claim 1, characterized in that: The mixed surfactant is applied to the 0-20 cm topsoil of the contaminated soil.

4. The method for remediating petroleum hydrocarbon contaminated soil according to claim 1, characterized in that: The bio-based degradable foam is used in an amount of 0.1 kg / m².

5. The method for remediating petroleum hydrocarbon contaminated soil according to claim 3, characterized in that: During the remediation process of the contaminated soil, the moisture content of the topsoil is maintained at 60-65%.

6. The method for remediating petroleum hydrocarbon contaminated soil according to claim 1, characterized in that: The elution experiment was carried out by reciprocating oscillation in a constant temperature water bath oscillator to ensure that the contaminated soil and the mixed surfactants were fully contacted and mixed.

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