Preparation method and application of self-destructing latex double-liquid foam for density control of heavy organic pollutants

Abstract

The present invention belongs to the field of environmental engineering technology, and more specifically, relates to a preparation method and application of a self-demulsifying colloidal two-liquid foam for density control of heavy organic pollutants. The present invention uses an oxidant solution as a water film and a non-water-soluble light organic solvent as a core to form a self-demulsifying "oxidation film" colloidal two-liquid foam. After the colloidal two-liquid foam comes into contact with a variety of heavy organic pollutants, it will self-demulsify and release the light organic solvent inside to dissolve with the pollutants without adding any additional demulsifier, thereby reducing the density of the pollutants and achieving the floating and efficient removal of heavy organic pollutants. This realizes the self-demulsification density control and repair of heavy organic pollutants, avoids the introduction of demulsifiers, and improves the efficiency of density control.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental engineering, and more particularly relates to a preparation method and application of a self-destructing latex double-liquid foam for density control of heavy organic pollutants. Background Art

[0002] Chlorinated organic compounds are widely used in the metal industry, machinery manufacturing and electronics industry. However, due to improper storage and disposal during pipeline transportation, large amounts of chlorinated organic compounds can be released into the underground environment. The resulting heavy organic pollutants (DNAPL) contamination in groundwater is one of the most challenging environmental remediation problems.

[0003] Most DNAPLs have high density, low water solubility, low biodegradability, and high toxicity, posing a serious threat to health and the ecological environment. Surfactant flushing is an effective method for remediating DNAPL-contaminated groundwater. However, this technique can reduce the interfacial tension between the contaminant and water during the remediation process, leading to vertical migration of DNAPL and widespread contamination. In situ density-modulated remediation techniques can enhance the buoyancy of DNAPL by reducing its own density or increasing the density of the aqueous phase, preventing its migration into uncontaminated aquifers and effectively flushing and remediating contaminated aquifers.

[0004] Common in-situ density-controlled remediation techniques primarily rely on upward hydrodynamic flushing or the addition of high-density salt solutions or low-density alcohol solutions to prevent the downward migration of DNAPL during the flushing and remediation process. However, researchers have combined upward hydrodynamic flushing with the use of surfactants to flush tetrachloroethylene (PCE), finding that downward movement of PCE is only controlled under conditions of a high upward hydraulic gradient. This method, when applied, requires the provision of stable and high upward hydraulic gradient conditions at the actual contaminated site, which are difficult to control in practice. The density control of DNAPL by salt solutions relies on a high salt concentration in water; once the concentration is diluted, DNAPL still faces the risk of downward migration. Low-density alcohol solutions are miscible with DNAPL, causing it to expand in volume and reduce its density. However, alcohol solutions have limited migration capacity within aquifers, making them ineffective for remediating actual contaminated aquifers.

[0005] To address the aforementioned density-controlled remediation issues, relevant scholars have proposed using colloidal two-liquid foam for density-controlled remediation of DNAPL contaminants. Colloidal two-liquid foam is a special liquid / liquid colloidal dispersion system with a foam-like structure formed by fully stirring and emulsifying two different surfactants (oil-soluble and water-soluble) and two solvents (organic solvent and water). Colloidal two-liquid foam possesses excellent stability and mobility, making it effectively applicable to the remediation of contaminated aquifers. Density-controlled technology based on colloidal two-liquid foam involves injecting the foam near the DNAPL contamination source. Then, measures are taken to rupture it, releasing the organic solvent inside to dissolve in the DNAPL, reducing the density of the DNAPL, preventing its migration to uncontaminated aquifers, and effectively flushing and repairing the contaminated aquifer. This technology has the advantages of low remediation costs and high site applicability, and has been highly favored in recent years. However, most of the current colloidal two-liquid foams have a non-polar solvent as their core and have extremely high stability. During the application process, demulsifiers need to be added separately, and the effective contact and reaction between the demulsifier and the colloidal two-liquid foam must be controlled to make the colloidal two-liquid foam burst and play the role of density regulation and repair. However, there are problems such as low density regulation efficiency and the demulsifier easily causing secondary pollution to the aquifer, which limits its application in actual groundwater remediation projects. Summary of the Invention

[0006] The purpose of the present invention is to provide a preparation method and application of a self-breaking emulsion two-liquid foam for density control of heavy organic pollutants. More specifically, it relates to a method for preparing a self-breaking emulsion two-liquid foam and controlling its density to repair heavy organic pollutants. It provides a technology for the repair of contaminated groundwater to solve the problems existing in the above-mentioned prior art.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is to provide a method for preparing a self-breaking emulsion double-liquid foam, comprising the following steps:

[0009] A water-soluble oxidant is added to the anionic surfactant solution, and a uniform and fine gas foam system containing an oxide film is obtained by stirring. Subsequently, an oil-soluble surfactant solution is added dropwise to the gas foam system under stirring to obtain the self-breaking emulsion-state two-liquid foam.

[0010] Furthermore, the anionic surfactant in the anionic surfactant solution is sodium dodecyl sulfate (SDS) or sodium dodecyl sulfonate (SLS).

[0011] Furthermore, the concentration of the anionic surfactant solution is 3-5 g / L.

[0012] Furthermore, the concentration of the water-soluble oxidant in the gas foam system is 0.1-12 g / L.

[0013] Furthermore, the water-soluble oxidant includes sodium persulfate or potassium permanganate.

[0014] Optionally, when the water-soluble oxidant is sodium persulfate, the concentration of the water-soluble oxidant in the gas foam containing the oxide film is 4-12 g / L.

[0015] Optionally, when the water-soluble oxidant is potassium permanganate, the concentration of the water-soluble oxidant in the gas foam containing the oxide film is 100-500 mg / L.

[0016] Furthermore, the oil-soluble surfactant in the oil-soluble surfactant solution is isopropyl palmitate (IPP) or dodecyl alcohol polyoxyethylene triether (AEO-3), the solvent is a non-water-soluble organic solvent, and the concentration is 1-2% (v / v).

[0017] Optionally, the water-insoluble organic solvent is n-heptane or n-octane.

[0018] Optionally, the volume ratio of the non-water-soluble organic solvent to the anionic surfactant solution is 6:1.

[0019] The second technical solution of the present invention is to provide a self-breaking emulsion-state two-liquid foam, which is prepared by the above-mentioned preparation method.

[0020] The third technical solution of the present invention is to provide a method for controlling the density of heavy organic pollutants, comprising the following steps:

[0021] The self-destructing latex double-liquid foam is used to control the density of heavy organic pollutants.

[0022] Furthermore, the volume ratio of the self-breaking emulsion double-liquid foam to the heavy organic pollutants is 3-24:4-9.

[0023] The fourth technical solution of the present invention is to provide an application of the above-mentioned self-breaking emulsion double-liquid foam or the above-mentioned method for controlling the density of heavy organic pollutants in the remediation of contaminated groundwater.

[0024] The present invention adds an oxidant to the aqueous phase of a colloidal two-liquid foam to create an "oxidation film" colloidal two-liquid foam. The oxidation reaction between the oxidant and the contaminant in the foam's aqueous phase automatically ruptures the foam and breaks the emulsion, achieving self-demulsification, density-controlled repair of DNAPL. Upon contact with DNAPL, the colloidal two-liquid foam automatically ruptures, releasing an internal organic solvent that dissolves in the DNAPL, directly converting the DNAPL into a light organic liquid (LNAPL) for flushing and repair. This avoids the risk of secondary contamination from demulsifier injection, improves repair efficiency, shortens the repair process, and effectively density-controlled repair of DNAPL-contaminated aquifers.

[0025] The present invention discloses the following technical effects:

[0026] The present invention provides a preparation and use method of a self-demulsifying "oxide film" colloidal two-liquid foam for density control of heavy organic pollutants. The self-demulsifying "oxide film" colloidal two-liquid foam uses an oxidant solution as a water film and a non-water-soluble light organic solvent as a core. After the colloidal two-liquid foam comes into contact with a variety of heavy organic pollutants, it will self-demulsify and release the internal light organic solvent to dissolve with the pollutants without adding any additional demulsifier, thereby reducing the density of the pollutants, achieving the floating and efficient removal of the heavy organic pollutants, realizing the self-demulsifying density control and repair of the heavy organic pollutants, avoiding the introduction of demulsifiers, and improving the density control efficiency.

[0027] The present invention uses an oxidant solution as a water film and a non-water-soluble light organic solvent as a core to prepare a self-demulsifying "oxidation film" colloidal two-liquid foam. After the colloidal two-liquid foam comes into contact with heavy organic pollutants, it will self-demulsify and release the light organic solvent inside to dissolve in the pollutants, thereby reducing the density of the heavy organic pollutants and achieving the floating and efficient removal of the heavy organic pollutants.

[0028] The self-destructing latex double-liquid foam of the present invention has simple and easily available components, low cost, and a safe and simple preparation method.

[0029] The self-breaking latex double-liquid foam of the present invention has a good density control effect on various heavy organic pollutants and has good universality.

[0030] The self-destructing latex double-liquid foam of the present invention has good migration and transmission performance and can be effectively applied to underground aquifers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0032] Figure 1These are microscope photos of the self-breaking emulsion double-liquid foams prepared in Examples 1-8, wherein a is Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, f is Example 6, g is Example 7, and h is Example 8.

[0033] Figure 2 These are microscope photos of the self-breaking emulsion-state two-liquid foams prepared in Examples 9-12, where a is Example 9, b is Example 10, c is Example 11, and d is Example 12.

[0034] Figure 3 Schematic diagram of the structure of self-breaking latex double-liquid foam.

[0035] Figure 4 The self-demulsification density of self-demulsification colloidal two-liquid foam is regulated for different heavy organic pollutants.

[0036] Figure 5 The zeta potential of the self-breaking latex double-liquid foam prepared in Examples 1-8. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] The raw materials and reagents used in the specific embodiments of the present invention are all commercially available products.

[0043] The preparation steps of the self-breaking emulsion double liquid foam include:

[0044] S1. Place 5 mL of a 3-5 g / L anionic surfactant (SDS or SLS) solution into a beaker, then add 0.02-0.06 g of sodium persulfate or 0.5-2.5 mg of potassium permanganate to the beaker, and stir at high speed using a magnetic stirrer until a uniform, fine, stable gas foam system containing an oxide film is formed;

[0045] S2. Add an oil-soluble surfactant solution (AEO-3 or IPP) to a water-insoluble organic solvent (n-heptane or n-octane) (1-2% (v / v)), and then add it dropwise to the gas foam system of step S1, controlling the volume ratio of the water-insoluble organic solvent to the anionic surfactant solution to be 6, and maintaining high-intensity stirring during the dropwise addition process to ensure sufficient mixing and dispersion between the two phases, thereby preparing a self-breaking emulsion-state two-liquid foam ("oxide film" colloidal two-liquid foam).

[0046] Examples 1-12

[0047] The selection of raw materials and reagents is shown in Table 1.

[0048] Table 1

[0049]

[0050] Figure 1 These are microscope photos of the self-breaking emulsion double-liquid foams prepared in Examples 1-8, wherein a is Example 1, b is Example 2, c is Example 3, d is Example 4, e is Example 5, f is Example 6, g is Example 7, and h is Example 8.

[0051] Figure 2 These are microscope photos of the self-breaking emulsion-state two-liquid foams prepared in Examples 9-12, where a is Example 9, b is Example 10, c is Example 11, and d is Example 12.

[0052] Figure 3 The schematic diagram of the structure of self-breaking latex double liquid foam. Figure 3 It can be seen that in the structural diagram, the outer layer of the "oxide film" colloidal two-liquid foam is a water-soluble anionic surfactant and a water-soluble oxidant film, the inner core is a non-water-soluble light organic solvent and an oil-soluble surfactant is dissolved inside.

[0053] Test Example 1

[0054] The efficiency of the "oxide film" colloidal two-liquid foam in regulating the density of heavy organic pollutants refers to the efficiency of the "oxide film" colloidal two-liquid foam in converting heavy organic liquid into light organic liquid after being uniformly mixed with the heavy organic pollutants.

[0055] In this test example, the density of the heavy organic liquid was adjusted to 1 g / cm 3 The boundary conditions after regulation are set. According to the density and relative molecular mass of n-heptane and n-octane in the heavy organic liquid and the “oxidation film” colloidal two-liquid foam, the volume ratio of the self-demulsification colloidal two-liquid foam to the pollutant is calculated as follows: (density of pollutant - 1) / (1-density of n-heptane / octane) × 1.167. The minimum ratio of the self-demulsification density regulation of the “oxidation film” colloidal two-liquid foam for different heavy organic pollutants can be calculated. The specific volume ratios are shown in Table 2. The self-demulsification density can be obtained. During the regulation, the minimum volume ratios of the "oxide film" colloidal two-liquid foam with n-heptane as the core to nitrobenzene, dichloromethane, trichloroethylene, carbon tetrachloride and tetrachloroethylene pollutants were 3:4, 11:5, 15:7, 21:5 and 22:7 respectively; the minimum volume ratios of the "oxide film" colloidal two-liquid foam with n-octane as the core to nitrobenzene, dichloromethane, trichloroethylene, carbon tetrachloride and tetrachloroethylene pollutants were 4:5, 12:7, 15:6, 21:3 and 24:9 respectively.

[0056] Table 2

[0057]

[0058] Test Example 2

[0059] The "oxide film" colloidal two-liquid foam with n-heptane as the core, isopropyl palmitate as the oil-soluble surfactant, and an aqueous solution of sodium dodecylsulfonate and sodium persulfate as the outer water film is used as a representative self-demulsifying colloidal two-liquid foam. The self-demulsifying density of five heavy organic pollutants with different densities is regulated by using this "oxide film" colloidal two-liquid foam. The regulation process is carried out in a sealed tube with a scale. Referring to the ratio in Table 2, different volumes of heavy organic pollutants and "oxide film" colloidal two-liquid foam are added to the sealed tube. The tube is placed in a constant temperature shaker at 20°C and shaken at 150 rpm for 10 hours, and then allowed to stand for 10 minutes. The density change of the heavy organic pollutants in the lower layer is observed. The specific results are shown in [1]. Figure 4 .

[0060] Figure 4 The self-demulsification density of self-demulsification colloidal two-liquid foam for different heavy organic pollutants is controlled by Figure 4 It can be seen that after the "oxide film" colloidal two-liquid foam comes into contact with heavy organic pollutants, it can self-demulsify and release the light organic solvent inside to dissolve with the heavy organic pollutants, quickly reducing the density of heavy organic pollutants, making the density of nitrobenzene, dichloromethane, trichloroethylene, carbon tetrachloride and tetrachloroethylene pollutants reduced to 0.986g / cm 3 , 0.991g / cm 3 , 0.994g / cm 3 , 0.989g / cm 3 and 0.995g / cm 3 .

[0061] Test Example 3

[0062] The determination of Zeta potential is helpful to clarify the electrical properties of the “oxide film” colloidal two-liquid foam, which has an important influence on its migration and distribution in the aquifer. Therefore, the Zeta potential of the different types of “oxide film” colloidal two-liquid foams listed in Table 1 was tested. The results are shown in the figure below. Figure 5 shown.

[0063] Figure 5 The zeta potential of the self-breaking emulsion two-liquid foam prepared in Examples 1-8 (Foam 1 to Foam 8 in the figure correspond to Examples 1 to 8, respectively). As can be seen from the figure, the zeta potential of different types of "oxide film" colloidal two-liquid foams are all negative, namely -58.47mV, -75.23mV, -65.90mV, -80.67mV, -78.97mV, -72.63mV, -68.09mV and -74.88mV, respectively. Under normal circumstances, underground aquifer media are negatively charged. The "oxide film" colloidal two-liquid foam with the same charge can migrate and be transmitted to a longer distance, expanding the scope of influence, which is conducive to its application in the remediation of contaminated aquifers.

[0064] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0065] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a self-breaking latex double-liquid foam, characterized in that the steps include: A water-soluble oxidant is added to a water-soluble anionic surfactant solution, and the mixture is stirred to obtain a gas foam system containing an oxide film, and then an oil-soluble surfactant solution is added dropwise to the gas foam system under stirring to obtain the self-breaking emulsion-state two-liquid foam; The solvent of the oil-soluble surfactant solution is a water-insoluble light organic solvent.

2. The preparation method according to claim 1, wherein The water-soluble anionic surfactant in the water-soluble anionic surfactant solution is SDS or SLS; and / or the concentration of the water-soluble anionic surfactant solution is 3-5 g / L.

3. The preparation method according to claim 1, wherein The water-soluble oxidant includes sodium persulfate or potassium permanganate; and / or the concentration of the water-soluble oxidant in the gas foam system is 0.1-12 g / L.

4. The preparation method according to claim 3, wherein When the water-soluble oxidant is sodium persulfate, the concentration of the water-soluble oxidant in the gas foam containing the oxide film is 4-12 g / L; and / or, when the water-soluble oxidant is potassium permanganate, the concentration of the water-soluble oxidant in the gas foam containing the oxide film is 100-500 mg / L.

5. The preparation method according to claim 1, wherein The oil-soluble surfactant in the oil-soluble surfactant solution is IPP or AEO-3, and the concentration is 1-2% (v / v).

6. The preparation method according to claim 1, wherein The water-insoluble light organic solvent is n-heptane or n-octane; and / or the volume ratio of the water-insoluble light organic solvent to the water-soluble anionic surfactant solution is 6:

1.

7. A self-breaking latex double-liquid foam, characterized in that: The self-destructing emulsion-state two-liquid foam is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for controlling the density of heavy organic pollutants, characterized in that the steps include: The self-breaking emulsion double-liquid foam according to claim 7 is used to control the density of heavy organic pollutants.

9. The method according to claim 8, wherein The volume ratio of the self-breaking emulsion two-liquid foam to the heavy organic pollutants is 3-24:4-9.

10. Use of the self-destructing emulsion two-liquid foam according to claim 7 or the method for controlling the density of heavy organic pollutants according to any one of claims 8 to 9 in the remediation of contaminated groundwater.

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