Method for Remediating Groundwater Petroleum Hydrocarbon Pollution by Utilizing Nano-Bubbles to Enhance Cl - / PMS

Abstract

The present invention discloses a method for utilizing nano-bubbles to enhance the remediation of petroleum hydrocarbon-contaminated groundwater by Cl<supgt;‑< / supgt> / PMS: a certain amount of nano-bubbles, an inorganic salt containing Cl<supgt;‑< / supgt>, and peroxymonosulfate (PMS) are added to the groundwater contaminated with petroleum hydrocarbons. The present invention utilizes the mass transfer efficiency and bursting energy of nano-bubbles to induce and promote the activation of PMS by Cl<supgt;‑< / supgt>, generating more reactive chlorine and reactive oxygen species to rapidly and efficiently degrade petroleum hydrocarbon pollutants. Moreover, this enhancement method is very suitable for the remediation of groundwater in coastal areas with high chloride salt content, without the need for additional chlorine salt addition, saving costs. The remediation method provided by the present invention has low cost, simple operation, and strong universality, and is suitable for application in large-scale petroleum hydrocarbon-contaminated groundwater remediation projects.

Description

Technical Field

[0001] The present invention belongs to the field of groundwater pollution remediation applications, and specifically relates to a method for using nano-bubbles to enhance the activation of PMS for the remediation of petroleum hydrocarbon pollution in groundwater. - Technical Background

[0002] Groundwater is the most important water source in the world, and approximately one-third of the population directly depends on drinking water from groundwater. The presence of petroleum hydrocarbon pollution in groundwater can induce various cancers in humans and greatly affect human health. Currently, globally, the pollution of groundwater by petroleum hydrocarbons is a widespread problem. Due to its relatively high efficiency, in-situ persulfate advanced oxidation technology has received much attention in the remediation of petroleum hydrocarbon-polluted groundwater. Persulfates include persulfate (PDS) and peroxymonosulfate (PMS). Due to its asymmetric molecular structure, PMS has higher reactivity than PDS. In addition, the presence of groundwater background components (such as Cl - and HCO3 - ) makes the remediation efficiency of PMS superior to that of PDS in some cases. The reaction of PMS with natural nucleophiles increases the yield of SO4· - and generates secondary non-radical oxidants and reactive halogen species (such as HOX, X·, X2· - , where X is a halogen element); for PDS, the complex groundwater matrix acts as a radical scavenger. Therefore, PMS has become a promising oxidant for remediating petroleum hydrocarbon-polluted groundwater.

[0003] In addition, PMS can be enhanced for pollutant degradation through energy activation (heat, ultraviolet light), transition metal activation (Co(II), Fe(II)), and carbonaceous material activation (carbon nanotubes, graphene). Existing PMS activation methods have various problems. For example, energy activation requires persistent energy supply and is impractical for field-scale applications. Although metal activation is carried out at normal temperature and pressure, the introduced metal ions can cause secondary pollution; the preparation processes of carbonaceous materials such as carbon nanotubes and graphene are complex and costly, limiting large-scale production applications. Therefore, choosing a suitable activation method is crucial. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for using nano-bubbles to enhance the Cl - / PMS remediation of petroleum hydrocarbon pollution in groundwater.

[0005] The present invention is achieved through the following technical methods: adding a certain amount of nano-bubbles, an inorganic salt containing Cl - and PMS to groundwater containing petroleum hydrocarbon pollution, thereby achieving the function of enhancing the remediation of petroleum hydrocarbon pollution. ​

[0006] The key to the technical solution of the present invention lies in utilizing the mass transfer efficiency, high Zeta potential, and bursting energy of nanobubbles to induce and promote Cl - to activate PMS, generating more reactive chlorine and reactive oxygen species to attack target pollutants.

[0007] As a further preference, the concentration of the nanobubbles is 1 to 5×10 7 per mL, and the size is 100 nm to 200 nm.

[0008] As a further preference, the nanobubble gas source is at least one of air, nitrogen, carbon dioxide, and oxygen.

[0009] As a further preference, the concentration of Cl - is greater than 2 mM.

[0010] As a further preference, the inorganic salt containing Cl - is one or more of NaCl, KCl, and CaCl2.

[0011] As a further preference, when the concentration of Cl - in groundwater exceeds 2 mM, only nanobubbles and PMS need to be added, and there is no need to additionally add inorganic salts containing Cl - .

[0012] As a further preference, the concentration of PMS is greater than 3 mM.

[0013] As a further preference, the PMS is provided by potassium monopersulfate compound salt.

[0014] The present invention utilizes the mass transfer efficiency and bursting energy of nanobubbles to induce and promote Cl - to activate PMS, generating more reactive chlorine and reactive oxygen species to rapidly and efficiently degrade petroleum hydrocarbon pollutants. Moreover, this synergistic method is very suitable for the remediation of groundwater in coastal areas with a high chloride salt content, without the need to additionally add chloride salts, saving costs. The remediation method provided by the present invention has low costs, is simple to operate, has strong universality, and is suitable for application in large-scale groundwater remediation projects contaminated by petroleum hydrocarbons.

[0015] The present invention provides an innovative remediation method for remediating groundwater contaminated by petroleum hydrocarbons by enhancing the efficiency of Cl - to activate PMS. The peroxy bond in PMS is asymmetric, and the peroxy bond attached to hydrogen is positively charged, so non-polar PMS is easily attacked by nucleophilic substances. Therefore, Cl - can be used to activate PMS to generate reactive chlorine and reactive oxygen species, but alone Cl -There are problems such as slow PMS decomposition rate and low utilization rate of chloride salts during activation. Nanobubbles have excellent characteristics such as small diameter, large specific surface area, high mass transfer efficiency, high Zeta potential, and no secondary pollution. When nanobubbles burst, energy is released. On the one hand, ·OH will be generated, which has a direct oxidation effect on petroleum hydrocarbon pollutants; on the other hand, high-temperature and high-pressure conditions will be locally generated instantaneously when the bubbles burst, inducing further activation of PMS, increasing the yield of active substances, and enhancing the degradation of petroleum hydrocarbon pollutants. By utilizing the characteristics of nanobubbles, the present invention enhances the activation of Cl - on PMS, generating more active species. The present invention provides an environmentally friendly, efficient, and economical technology for the remediation of groundwater polluted by petroleum hydrocarbons.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. In the present invention, PMS is a solid particle, which is convenient for transportation; the chloride salt in the scheme is inexpensive and can stably activate PMS for a long time, so it has strong operability in the actual remediation of groundwater.

[0018] 2. The nanobubbles of the present invention have a large specific surface area, no pollution, long existence time, and high Zeta potential, expanding the contact probability with pollutants in water and improving the oxidation efficiency.

[0019] 3. The nanobubbles of the present invention have high mass transfer efficiency and can enhance the activation of Cl - on PMS, generating more active chlorine and active oxygen species. Compared with traditional advanced oxidation technologies, the activation method of the present invention is simple, has stronger oxidation ability, and a wider action range.

[0020] 4. Most of the groundwater pollution sites treated by the present invention have a high salt content. Especially in coastal areas, there is a large amount of Cl - present in the groundwater. Therefore, there is no need to add additional chloride salts, and the salt content in the groundwater can also be reduced. This method has a unique advantage in treating groundwater with a high salt content. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a comparative graph of the degradation efficiency of phenol under the conditions of 5 mM NaCl, 7 mM PMS, and the presence or absence of air nanobubbles in Example 1;

[0022] Figure 2 It is a graph of the degradation rate of phenol under the conditions of 5×10 7 air nanobubbles / mL, 5 mM NaCl, and different oxidants (7 mM PMS or 7 mM PS or 7 mM H2O2) in Example 2;

[0023] Figure 3 It is in Example 3 under the condition of 5×10 7Degradation rate curve of phenol under the conditions of 5×10

[0024] Figure 4 For Example 4, under the conditions of 5×10 7 air nano - bubbles / mL, 5 mM NaCl and different concentrations of PMS;

[0025] Figure 5 For Example 5, under the conditions of 5×10 7 air nano - bubbles / mL, 5 mM NaCl and 7 mM PMS for typical petroleum hydrocarbon pollutants naphthalene (NAP) and o - phenylphenol (OPP);

[0026] Figure 6 For Example 6, under the conditions of 5×10 7 air nano - bubbles / mL and 7 mM PMS for the degradation rate curve of phenol pollutants in natural coastal groundwater. Detailed implementation mode

[0027] The present invention provides a method for using nano - bubbles to enhance the remediation of petroleum hydrocarbon - contaminated groundwater by Cl - / PMS. The present invention will be further described below in conjunction with the accompanying drawings and specific implementation modes, but the present invention is not limited thereto.

[0028] Example 1

[0029] (1) Nano - bubble preparation:

[0030] In the example, nano - bubble water is prepared with air as the gas source and pure water as the water source. The number of bubbles is 5×10 7 bubbles / mL, and the bubble size is 100 nm - 200 nm.

[0031] (2) Selection of Cl - :

[0032] In the example, the selected inorganic salt containing Cl - is NaCl.

[0033] (3) Selection of PMS:

[0034] In the example, the selected persulfate ion is potassium monopersulfate compound salt.

[0035] (4) The specific reaction process is implemented according to the following steps:

[0036] 5 mM NaCl and 7 mM PMS were added to the phenol solution with or without nano-bubble water. The total volume of the solution was 100 mL, and the concentration of the target pollutant phenol was 10 mg / L. Then it was placed in a constant temperature shaking incubator and shaken well at 60 rpm and 20 °C. Within the set time, 1 mL of the reaction solution was taken and quenched in 1 mL of absolute ethanol, and the degradation rate of phenol was detected by high performance liquid chromatography.

[0037] As Figure 1 shown, in this example, in the system containing nano-bubble water, the degradation rate of phenol was as high as 94% in 60 min; while in the system without nano-bubble water, the degradation rate of phenol was only 70% in 60 min. This indicates that nano-bubbles can significantly enhance the degradation of phenol by Cl - activated PMS.

[0038] Example 2

[0039] (1) Nano-bubble preparation:

[0040] In the example, nano-bubble water was prepared using air as the gas source and pure water as the water source. The number of bubbles was 5×10 7 per mL, and the bubble size was 100 nm - 200 nm.

[0041] (2) Selection of Cl - :

[0042] In the example, the selected Cl - -containing inorganic salt was NaCl.

[0043] (3) Selection of oxidants:

[0044] In the example, the selected oxidants were potassium monopersulfate compound salt (PMS), persulfate (PS), and hydrogen peroxide (H2O2).

[0045] (4) The specific reaction process was carried out according to the following steps:

[0046] 5 mM NaCl was added to the phenol solution containing nano-bubbles, and then different oxidants 7 mM PMS, 7 mM PS, and 7 mM H2O2 were added respectively. The total volume of the solution was 100 mL, and the concentration of the target pollutant phenol was 10 mg / L. Then it was placed in a constant temperature shaking incubator and shaken well at 60 rpm and 20 °C. Within the set time, 1 mL of the reaction solution was taken and quenched in 1 mL of absolute ethanol, and the degradation rate of phenol was detected by high performance liquid chromatography.

[0047] As Figure 2As shown, in this embodiment, in the system with PMS as the oxidant added, the degradation rate of phenol is as high as 94% in 60 minutes; while in the systems with PS and H2O2 added, the degradation rates of phenol are only 10% and 8% respectively in 60 minutes. This is because the asymmetric molecular structure of PMS makes its reactivity the highest, and nanobubbles can effectively induce and promote Cl - to activate PMS to generate more active substances.

[0048] Example 3

[0049] (1) Nanobubble preparation:

[0050] In the example, nanobubble water is prepared with air as the gas source and pure water as the water source. The number of bubbles is 5×10 7 per mL, and the bubble size is 100 nm to 200 nm.

[0051] (2) Selection of Cl - :

[0052] In the example, the inorganic salt containing Cl - selected is NaCl.

[0053] (3) Selection of PMS:

[0054] In the example, the persulfate ion selected is potassium monopersulfate compound salt.

[0055] (4) The specific reaction process is implemented according to the following steps:

[0056] 7 mM PMS and different concentrations of NaCl (3 mM, 5 mM, 7 mM, 9 mM) are added to the phenol solution containing nanobubbles. The total volume of the solution is 100 mL, and the concentration of the target pollutant phenol is 10 mg / L. Then it is placed in a constant temperature shaking incubator and shaken at 60 rpm and 20 °C. At the set time, 1 mL of the reaction solution is taken and quenched in 1 mL of absolute ethanol, and the degradation rate of phenol is detected by high performance liquid chromatography.

[0057] As Figure 3 shown, in this embodiment, the degradation rate of phenol at 60 minutes increases with the increase of the NaCl concentration (3 mM, 5 mM, 7 mM, 9 mM), which are 63%, 94%, 100%, and 100% respectively.

[0058] Example 4

[0059] (1) Nanobubble preparation:

[0060] In the example, nanobubble water is prepared with air as the gas source and pure water as the water source. The number of bubbles is 5×10 7 per mL, and the bubble size is 100 nm to 200 nm.

[0061] (2) Selection of Cl - :

[0062] In the examples, the selected Cl - inorganic salt is NaCl.

[0063] (3) Selection of PMS:

[0064] In the examples, the selected persulfate ion is potassium monopersulfate compound salt.

[0065] (4) The specific reaction process is implemented according to the following steps:

[0066] 5 mM NaCl and different concentrations of PMS (5 mM, 7 mM, 9 mM) were added to the phenol solution containing nanobubbles. The total volume of the solution was 100 mL, and the concentration of the target pollutant phenol was 10 mg / L. Then it was placed in a constant temperature shaking incubator and shaken well at 60 rpm and 20 °C. At the set time, 1 mL of the reaction solution was taken and quenched in 1 mL of absolute ethanol, and the degradation rate of phenol was detected by high performance liquid chromatography.

[0067] As Figure 4 shown, in this example, the degradation rate of phenol at 60 min increased with the increase of the PMS concentration (5 mM, 7 mM, 9 mM), which were 84%, 94%, and 100% respectively.

[0068] Example 5

[0069] (1) Preparation of nanobubbles:

[0070] In the examples, nanobubble water was prepared using air as the gas source and pure water as the water source. The number of bubbles was 5×10 7 bubbles / mL, and the bubble size was 100 nm - 200 nm.

[0071] (2) Selection of Cl - :

[0072] In the examples, the selected Cl - inorganic salt is NaCl.

[0073] (3) Selection of PMS:

[0074] In the examples, the selected persulfate ion is potassium monopersulfate compound salt.

[0075] (4) The specific reaction process is implemented according to the following steps:

[0076] 5 mM NaCl and 7 mM PMS were added to the aqueous solution of nanobubbles containing naphthalene (NAP) or o-phenylphenol (OPP), with the total volume of the solution being 100 mL in both cases, and the concentration of the target pollutants NAP or OPP being 10 mg / L. Then, it was placed in a thermostatic shaking incubator and shaken at 60 rpm and 20 °C. At the set time, 1 mL of the reaction solution was taken and placed in 1 mL of absolute ethanol to quench the reaction, and the degradation rates of NAP and OPP were detected by high-performance liquid chromatography.

[0077] As Figure 5 shown, in this example, the degradation rates of NAP and OPP at 60 min were 97% and 93% respectively.

[0078] Example 6

[0079] (1) Nanobubble preparation:

[0080] In the example, nanobubble water was prepared using air as the gas source and natural groundwater as the water source. The number of bubbles was 2×10 7 per mL, and the bubble size was 100 nm to 200 nm.

[0081] (2) Selection of PMS:

[0082] In the example, the selected persulfate ion was potassium monopersulfate compound salt.

[0083] (3) Selection of groundwater:

[0084] In the example, the selected natural groundwater was from Pudong New Area, Shanghai. The concentration of Cl - in the natural groundwater was 510 mg / L.

[0085] (4) The specific reaction process was carried out according to the following steps:

[0086] 7 mM PMS was added to the aqueous solution of nanobubble groundwater containing phenol pollutants. The total volume of the solution was 100 mL, and the concentration of the target pollutant phenol was 10 mg / L. Then, it was placed in a thermostatic shaking incubator and shaken at 60 rpm and 20 °C. At the set time, 1 mL of the reaction solution was taken and placed in 1 mL of absolute ethanol to quench the reaction, and the degradation rate of phenol was detected by high-performance liquid chromatography.

[0087] As Figure 6 shown, in this example, without additional Cl - addition, the degradation rate of phenol by natural groundwater at 60 min was as high as 82%, indicating that the nanobubble-enhanced Cl - / PMS system has broad application prospects in the remediation of groundwater pollution in coastal areas.

Claims

1. A method for using nano - bubbles to enhance Cl - / PMS to repair petroleum hydrocarbon pollution in groundwater, which is characterized in that: Adding a certain amount of nanobubbles, inorganic salts containing Cl - and peroxymonosulfate (PMS) to groundwater contaminated with petroleum hydrocarbons, so as to achieve the function of enhancing the remediation of petroleum hydrocarbon pollution; The concentration of the nano-bubbles is 1 - 5×10 7 per mL, and the size is 100 nm - 200 nm; The nano-bubble gas source is at least one of air, nitrogen, carbon dioxide and oxygen; The PMS is provided by potassium monopersulfate compound salt.

2. Method for enhancing Cl - / PMS for repairing petroleum hydrocarbon pollution in groundwater according to claim 1, characterized in that The concentration of said Cl - is greater than 2 mM.

3. Method for enhancing the remediation of petroleum hydrocarbon contaminated groundwater by Cl - / PMS using nanobubbles, characterized in that The inorganic salt containing Cl - is one or more of NaCl, KCl, and CaCl2.

4. Method for enhancing the remediation of petroleum hydrocarbon contaminated groundwater by Cl - / PMS using nanobubbles, characterized in that, When the Cl concentration in groundwater - exceeds 2 mM, only nanobubbles and PMS need to be added, and there is no need to additionally add inorganic salts containing Cl - .

5. Method for enhancing Cl - / PMS to repair petroleum hydrocarbon pollution in groundwater according to claim 1, characterized in that The concentration of the PMS is greater than 3 mM.

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