Preparation method and application of self-breaking emulsion state double-liquid foam for density regulation and control of heavy organic pollutants

Abstract

The invention belongs to the technical field of environmental engineering, and particularly relates to a preparation method and application of self-breaking emulsion state double-liquid foam for density regulation and control of heavy organic pollutants. The self-demulsification oxidation film colloidal double-liquid foam with the oxidant solution as a water film and the non-water-soluble light organic solvent as an inner core is adopted, after the colloidal double-liquid foam makes contact with various heavy organic pollutants, the light organic solvent in the colloidal double-liquid foam can be released through self-demulsification under the condition that no extra demulsifier is added, and the light organic solvent and the pollutants are mutually soluble, so that the pollution to the pollutants is avoided. According to the method, the density of the pollutants is reduced, floating and efficient removal of the heavy organic pollutants are achieved, self-demulsification density regulation and repair of the heavy organic pollutants are achieved, introduction of a demulsifier is avoided, and the density regulation and control efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental engineering, and more specifically 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, chlorinated organic compounds can be released into the underground environment in large quantities. The resulting heavy organic pollutants (DNAPL) contamination in groundwater is one of the most challenging environmental remediation problems.

[0003] Most DNAPLs have the characteristics of high density, low water solubility, low biodegradability and high toxicity, which pose a serious threat to health and the ecological environment. Surfactant flushing remediation is one of the effective remediation methods for DNAPL-contaminated groundwater, but this technology will cause a decrease in the interfacial tension between pollutants and water during the remediation process, leading to problems such as vertical downward migration of DNAPL and expansion of the pollution range. In-situ density regulation remediation technology can increase the buoyancy of DNAPL by reducing the density of DNAPL itself or increasing the density of the water phase, thereby preventing DNAPL from migrating to uncontaminated aquifers and effectively flushing and repairing contaminated aquifers.

[0004] Common in-situ density control remediation technologies mainly prevent the downward migration of DNAPL during the flushing and remediation process by upward hydrodynamic flushing or adding high-density salt solutions and low-density alcohol solutions. However, relevant scholars combined the upward hydrodynamic flushing method and used surfactants to flush tetrachloroethylene (PCE). They found that the downward movement of PCE would only be controlled under high upward hydraulic gradient conditions. This method requires stable and high upward hydraulic gradient conditions to be provided at the actual contaminated site during application. These conditions are difficult to control at the actual site. The density control of DNAPL by salt solution depends on the high concentration of salt in water. Once the concentration is diluted, DNAPL still has the risk of downward migration. Low-density alcohol solution will dissolve with DNAPL, causing the volume of DNAPL to expand and the density to decrease. However, the migration capacity of alcohol solution in aquifers is limited, and the remediation effect on actual contaminated aquifers is poor.

[0005] In response to the above-mentioned density-controlled remediation problem, relevant scholars proposed using colloidal double-liquid foam to perform density-controlled remediation of DNAPL pollutants. Colloidal double-liquid foam is a special liquid / liquid colloidal dispersion system with a structure similar to foam, which is formed by fully stirring and emulsifying two different surfactants (oil-soluble and water-soluble) and two solvents (organic solvent and water). Colloidal double-liquid foam itself has good stability and mobility, which can be effectively used in the remediation of contaminated aquifers. The density control technology based on colloidal double-liquid foam is to inject the colloidal double-liquid foam into the vicinity of the DNAPL pollution source, and then take certain measures to make it rupture and release the internal organic solvent to be miscible with DNAPL, thereby reducing the density of DNAPL, avoiding the migration of DNAPL to uncontaminated aquifers, and effectively flushing and repairing contaminated aquifers. It has the advantages of low remediation cost and high site applicability, and has been favored in recent years. However, most of the current colloidal two-liquid foams have a non-polar solvent as the 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 need to 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 demulsifiers easily causing secondary pollution to aquifers, which limits their application in actual groundwater remediation projects. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing and applying a self-breaking emulsion-like two-liquid foam for density control of heavy organic pollutants, and more specifically to a method for preparing a self-breaking emulsion-like two-liquid foam and using its density control to repair heavy organic pollutants, providing 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 latex double-liquid foam, the steps comprising:

[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 latex double-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 water-insoluble 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 water-insoluble 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, wherein the self-breaking emulsion-state two-liquid foam 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, the steps comprising:

[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 latex 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 water phase of the colloidal two-liquid foam to construct an "oxidation film" colloidal two-liquid foam, and utilizes the oxidation reaction between the oxidant and the pollutant in the foam water phase to automatically break the foam and demulsify, thereby realizing the self-demulsification density control repair of DNAPL. After contacting DNAPL, the colloidal two-liquid foam can automatically break to release the internal organic solvent and dissolve it in DNAPL, directly converting DNAPL into light organic liquid (LNAPL) and flushing and repairing it, avoiding the risk of secondary pollution caused by the injection of demulsifiers and improving the repair efficiency, shortening the repair process, and effectively controlling the density to repair 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 has an oxidant solution as a water film and a non-water-soluble light organic solvent as an inner 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 be miscible with the pollutants without adding an 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 water-insoluble 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-breaking latex double-liquid foam of the present invention has simple and easy-to-obtain 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 constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0032] Figure 1These are microscope photographs of the self-breaking latex 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 latex double-liquid foams prepared in Examples 9-12, wherein 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-demulsified colloidal two-liquid foam is regulated for different heavy organic pollutants.

[0036] Figure 5 It is 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 should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

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

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation 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 a conflict with any incorporated document, the content 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 of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary 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 anionic surfactant (SDS or SLS) solution with a concentration of 3-5 g / L into a beaker, then add 0.02-0.06 g of sodium persulfate or 0.5-2.5 mg of potassium permanganate into the beaker, and then stir at high speed using a magnetic stirrer until a uniform, fine and 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 drop it into the gas foam system of step S1, control the volume ratio of the water-insoluble organic solvent to the anionic surfactant solution to be 6, and maintain high-intensity stirring during the dropping process to ensure sufficient mixing and dispersion between the two phases, thereby preparing a self-breaking emulsion double-liquid foam ("oxide film" colloidal double-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 photographs of the self-breaking latex 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 latex double-liquid foams prepared in Examples 9-12, wherein 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 the self-breaking latex double liquid foam is shown in Figure 1. 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 water-insoluble 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 ratio is 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 dodecyl sulfate and sodium persulfate as the outer water film is used as a representative self-demulsifiable colloidal two-liquid foam. The "oxide film" colloidal two-liquid foam is used to regulate the self-demulsification density of 5 heavy organic pollutants with different densities. The regulation process is carried out in a sealed tube with a scale. Different volumes of heavy organic pollutants and "oxide film" colloidal two-liquid foam are added to the sealed tube with reference to the proportion in Table 2. The tube is placed in a constant temperature shaker at 20°C and fully shaken at 150 rpm for 10 hours and then allowed to stand for 10 minutes to observe the density change of the heavy organic pollutants in the lower layer. The specific results are shown in Figure 4 .

[0060] Figure 4 The self-demulsification density of the self-demulsified colloidal double liquid foam for different heavy organic pollutants is regulated by Figure 4 It can be seen that after the "oxide film" colloidal double 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 different types of “oxide film” colloidal two-liquid foams in Table 1 was tested. The results are shown in Figure 5 shown.

[0063] Figure 5 The Zeta potential of the self-breaking latex two-liquid foam prepared in Examples 1-8 (Foam 1 to Foam 8 in the figure correspond to Examples 1 to 8, respectively). It can be seen from the figure that 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. In general, the underground aquifer medium is negatively charged, and the "oxide film" colloidal two-liquid foam with the same charge can migrate and be transmitted to a farther distance, thereby expanding the scope of influence, which is conducive to its application in the repair 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 enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a self-destructing latex double-liquid foam, characterized in that the steps include: A water-soluble oxidant is added to an anionic surfactant solution, and a gas foam system containing an oxide film is obtained by stirring. Subsequently, an oil-soluble surfactant solution is dripped into the gas foam system under stirring conditions to obtain the self-breaking emulsion-state two-liquid foam.

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

3. The preparation method according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: The oil-soluble surfactant in the oil-soluble surfactant solution is IPP or AEO-3, the solvent is a water-insoluble organic solvent, and the concentration is 1-2% (v / v).

6. The preparation method according to claim 5, characterized in that: The water-insoluble organic solvent is n-heptane or n-octane; and / or the volume ratio of the water-insoluble organic solvent to the 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 described in any one of claims 1-6.

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

9. The method according to claim 8, characterized in that The volume ratio of the self-destructing latex double-liquid foam to the heavy organic pollutants is 3-24:4-9.

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

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