A method for remediating organic polluted soil by ball milling activated persulfate

Abstract

The invention discloses a method for remediating organic polluted soil by ball milling activated persulfate, and belongs to the technical field of soil remediation. The invention adopts persulfate and soil to be remediated to be ball milled together, and the mass transfer efficiency of persulfate is improved while the persulfate is efficiently activated. The ball milling causes the persulfate and soil to be fully mixed and heat generated through collision and friction, and the full mixing ensures the mass transfer of persulfate and improves the reaction probability of sulfate radicals with organic pollutants; the ball milling generates heat to activate the persulfate to produce sulfate radicals, and the sulfate radicals oxidize and degrade organic pollutants, thereby improving the reaction activity of persulfate and promoting the efficient removal of organic pollutants. The whole process does not require the addition of an activator and will not cause secondary pollution. The method enriches the thermal activation pathway of persulfate and solves the defects of low heat transfer efficiency and low persulfate mass transfer efficiency in the existing thermal activation persulfate soil remediation technology.

Description

Technical Field

[0001] The invention belongs to the technical field of soil remediation, and in particular relates to a method for remediating organic polluted soil using ball-milled activated persulfate. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] The relocation sites of pesticide, coal chemical, petrochemical and other industries are the hardest hit areas of soil pollution. High concentrations of polycyclic aromatic hydrocarbons, halogenated hydrocarbons, petroleum hydrocarbons and other organic pollutants in the soil will threaten the environment and human health. They need to be harmlessly treated to ensure the safe reuse of land resources. Persulfate is a commonly used chemical remediation agent for organically contaminated soil, but the persulfate ionized by itself has a low redox potential and is less effective in treating organic pollutants. It needs to be activated to produce sulfate free radicals with a higher redox potential to efficiently oxidize organic pollutants.

[0004] Traditional methods of activating persulfate can be mainly divided into physical activation and chemical activation. Chemical activation methods include: transition metal oxide activation, alkali activation, phenol activation, etc. Although chemical activation has a high efficiency, transition metal oxides are very prone to metal ion leakage in an acidic environment system, leading to secondary pollution problems, and the strong alkaline conditions of alkali activation itself have created a new environmental burden to a certain extent and increased treatment costs. Physical activation mainly includes thermal activation, electrical activation, ultraviolet radiation, etc. Thermal activation is one of the most widely used methods for activating persulfate. It can destroy the oxygen-oxygen bond of persulfate through high temperature to produce sulfate radicals. It is simple to operate, has high activation efficiency, does not require the addition of chemical reagents, and will not cause secondary pollution, but has the problem of high energy consumption and requires a large amount of external energy input. For example, patent CN110918632A discloses a method for remediating organic contaminated soil by electrothermal activation of persulfate, in which the electric field in the electrode heating system drives the oxidant to be controllably distributed in the soil, and the electric thermal field formed in the electrode heating system is used to activate the persulfate, thereby achieving efficient removal of organic pollutants. However, there are problems such as low heat transfer efficiency and low persulfate mass transfer efficiency in the remediation process, resulting in long remediation time and high remediation cost.

[0005] In summary, the conventional method of thermally activating persulfate has problems such as low heat transfer efficiency and low persulfate mass transfer efficiency. Therefore, developing a new method of thermally activating persulfate with high heat transfer efficiency and high persulfate mass transfer efficiency is a technical problem to be solved in the art. Summary of the invention

[0006] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a method for ball milling activated persulfate to repair organic contaminated soil. The method provided by the present invention overcomes the defects of low heat transfer efficiency and low persulfate mass transfer efficiency in the existing thermally activated persulfate soil remediation technology.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] In a first aspect of the present invention, a method for remediating organic contaminated soil by ball milling activated persulfate is provided, the method comprising the following steps:

[0009] After adding persulfate to the soil to be repaired, ball milling is performed, and the ball-to-material ratio, ball-to-cavity ratio, ball milling speed and ball milling time are controlled so that the heat generated by ball milling activates the persulfate and degrades the organic pollutants in the soil to be repaired.

[0010] Preferably, the soil to be repaired is soil contaminated by organic pollutants, and the moisture content of the soil to be repaired is 20% to 30%.

[0011] Preferably, the organic pollutants include one or more of polycyclic aromatic hydrocarbons, halogenated hydrocarbons, and petroleum hydrocarbons.

[0012] Preferably, the persulfate is hydrogen persulfate or persulfate, and the dosage of the persulfate is: the molar ratio of persulfate or hydrogen persulfate to total organic carbon in the soil is 3:4 to 3:2.

[0013] Preferably, the persulfate includes sodium persulfate, sodium hydrogen persulfate or potassium persulfate, preferably sodium persulfate.

[0014] Preferably, the ball milling is carried out in a ball mill, and the ball mill is selected from a planetary mill, a vibrating ball mill or a stirring ball mill, preferably a planetary ball mill.

[0015] Preferably, the ball-to-material ratio is 50:1 to 10:1, preferably 25:1.

[0016] Preferably, the ball-to-cavity ratio is 1:12 to 1:6, preferably 1:8.

[0017] Preferably, the ball milling speed is 600 r / min to 6000 r / min.

[0018] Preferably, the ball milling time is 10 min to 60 min.

[0019] The beneficial effects of the present invention are:

[0020] The present invention discloses a method of ball milling persulfate and soil to be repaired, which can efficiently activate persulfate and improve the mass transfer efficiency of persulfate. The present invention promotes the full mixing of persulfate and soil through collision and friction and generates heat through ball milling. The full mixing ensures the mass transfer of persulfate and increases the reaction probability of sulfate radicals with organic pollutants. At the same time, the heat generated by ball milling activates persulfate to produce sulfate radicals, which oxidize and degrade organic pollutants, thereby increasing the reaction activity of persulfate, promoting the efficient removal of organic pollutants, and realizing the efficient repair of organic polluted soil. And the ball milling activation process of the present invention does not need to add an activator, and will not cause secondary pollution. It can be seen that the method for ball milling activation of persulfate provided by the present invention not only enriches the thermal activation pathway of persulfate, but also solves the problems of low heat transfer efficiency and low persulfate mass transfer efficiency in the existing thermally activated persulfate soil repair technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings in the specification, which constitute 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 improper limitations on the present invention.

[0022] Figure 1 It is the degradation rate of organic pollutants in Example 1, Example 2 and Example 3 of the present invention. DETAILED DESCRIPTION

[0023] In view of the defects of low heat transfer efficiency and low persulfate mass transfer efficiency in the existing thermally activated persulfate soil remediation technology, the present invention proposes a method for remediating organic contaminated soil by ball milling activated persulfate.

[0024] A typical embodiment of the present invention provides a method for remediating organic contaminated soil by ball milling activated persulfate, the method comprising the following steps:

[0025] After adding persulfate to the soil to be repaired, ball milling is performed, and the ball-to-material ratio, ball-to-cavity ratio, ball milling speed and ball milling time are controlled so that the heat generated by ball milling activates the persulfate and degrades the organic pollutants in the soil to be repaired.

[0026] The present invention promotes the full mixing of persulfate and soil through collision and friction and generates heat through ball milling, and the full mixing ensures the mass transfer of persulfate and increases the reaction probability of sulfate radicals with organic pollutants; at the same time, the heat generated by ball milling activates persulfate to generate sulfate radicals, and the sulfate radicals oxidize and degrade organic pollutants, thereby increasing the reaction activity of persulfate, promoting the efficient removal of organic pollutants, and realizing the efficient restoration of organic polluted soil. In addition, the ball milling activation process of the present invention does not require the addition of an activator and will not cause secondary pollution.

[0027] In some examples of this embodiment, the soil to be repaired is soil contaminated by organic pollutants, and the moisture content of the soil to be repaired is 20% to 30%, by mass percentage. The moisture in the soil can accelerate ion transfer and improve the mass transfer efficiency of persulfate. The soil moisture content is controlled at 20% to 30% by adding water based on the organic matter content of the soil.

[0028] In some examples of this embodiment, the organic pollutants include one or more of polycyclic aromatic hydrocarbons, halogenated hydrocarbons, and petroleum hydrocarbons.

[0029] In some examples of this embodiment, the organic pollutant includes one or more of atrazine, norfloxacin or 2,4-dichlorophenoxyacetic acid (2,4D).

[0030] In some examples of this embodiment, the persulfate is hydrogen persulfate or persulfate, and the dosage of the persulfate is: the molar ratio of persulfate or hydrogen persulfate to total organic carbon (TOC) in the soil is 3:4 to 3:2.

[0031] In some examples of this embodiment, the persulfate includes sodium persulfate, sodium hydrogen persulfate or potassium persulfate, preferably sodium persulfate.

[0032] In some examples of this embodiment, the ball milling is performed in a ball mill, and the ball mill is selected from a planetary mill, a vibrating ball mill or a stirring ball mill, preferably a planetary ball mill.

[0033] In some examples of this embodiment, the ball-to-material ratio is 50:1-10:1, preferably 25:1.

[0034] In some examples of this embodiment, the ball-to-cavity ratio is 1:12 to 1:6, preferably 1:8.

[0035] In some examples of this embodiment, the ball milling rotation speed is 600 r / min to 6000 r / min.

[0036] In some examples of this embodiment, the ball milling time is 10 min to 60 min.

[0037] The present invention promotes full mixing of persulfate and soil through collision and friction and generates heat through ball milling, and the full mixing ensures the mass transfer of persulfate and increases the reaction probability of sulfate radicals with organic pollutants; at the same time, the heat generated by ball milling activates persulfate to generate sulfate radicals, and the sulfate radicals oxidize and degrade organic pollutants, thereby increasing the reaction activity of persulfate, promoting the efficient removal of organic pollutants, and realizing the efficient restoration of organic polluted soil.

[0038] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0039] The raw materials and reagents used in the following examples are all commercially available or homemade.

[0040] Example 1

[0041] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0042] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of atrazine was 83%.

[0043] Example 2

[0044] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0045] 0.01 g of sodium persulfate was added to 0.5 kg of soil with a norfloxacin concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of norfloxacin was 69%.

[0046] Example 3

[0047] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0048] 0.01 g of sodium persulfate was added to 0.5 kg of soil with a 2,4-D concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of 2,4-D was 76%.

[0049] Example 4

[0050] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0051] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg.) and placed in a ball mill with a ball-to-material ratio of 50:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of atrazine was 82%.

[0052] Example 5

[0053] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0054] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 10:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, a ball milling time of 30 min, and an atrazine degradation rate of 75%.

[0055] Example 6

[0056] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0057] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:12, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of atrazine was 72%.

[0058] Example 7

[0059] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0060] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 25%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:6, a ball mill speed of 1000 r / min, a ball milling time of 30 min, and an atrazine degradation rate of 80%.

[0061] Example 8

[0062] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0063] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 20%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, a ball milling time of 30 min, and the degradation rate of atrazine was 68%.

[0064] Example 9

[0065] This embodiment provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0066] 0.01 g of sodium persulfate was added to 0.5 kg of soil with an atrazine concentration of 0.5 mg / kg (moisture content: 30%; TOC: 0.5 mg) and placed in a ball mill with a ball-to-material ratio of 25:1, a ball-cavity ratio of 1:8, a ball mill speed of 1000 r / min, and a ball milling time of 30 min. The degradation rate of atrazine was 86%.

[0067] Comparative Example 1

[0068] This comparative example provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0069] The difference from Example 1 is that the ball-to-material ratio is 5:1, and the remaining steps are exactly the same as those of Example 1.

[0070] After testing, the degradation rate of atrazine was 56%.

[0071] Comparative Example 2

[0072] This comparative example provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0073] The difference from Example 1 is that the ball-to-cavity ratio is 1:15, and the remaining steps are exactly the same as those of Example 1.

[0074] After testing, the degradation rate of atrazine was 62%.

[0075] Comparative Example 3

[0076] This comparative example provides a method for ball milling activated persulfate to repair organic contaminated soil, the specific steps are as follows:

[0077] The difference from Example 1 is that the soil moisture content is 15%, and the remaining steps are completely consistent with Implementation 1.

[0078] After testing, the degradation rate of atrazine was 34%.

[0079] As can be seen from the above examples, the present invention provides a method for efficiently repairing organic pollution in soil. The present invention fully mixes persulfate with soil through ball milling, thereby ensuring mass transfer of persulfate and increasing the probability of reaction with organic pollutants. At the same time, ball milling generates heat to activate persulfate to produce persulfate radicals, thereby increasing the reaction activity of persulfate and promoting efficient removal of organic pollutants.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for remediating organic contaminated soil by ball milling activated persulfate, characterized in that: The method comprises the following steps: After adding persulfate to the soil to be repaired, ball milling is performed, and the ball-to-material ratio, ball-to-cavity ratio, ball milling speed and ball milling time are controlled so that the heat generated by ball milling activates the persulfate and degrades the organic pollutants in the soil to be repaired; The moisture content of the soil to be remediated is 25% or 30%; The ball-to-material ratio is 25:1; the ball-to-cavity ratio is 1:8; the ball milling speed is 1000 r / min; and the ball milling time is 30 min.

2. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The soil to be remediated is soil contaminated by organic pollutants.

3. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The organic pollutants include one or more of polycyclic aromatic hydrocarbons, halogenated hydrocarbons, and petroleum hydrocarbons.

4. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The persulfate is hydrogen persulfate or persulfate, and the dosage of the persulfate is: the molar ratio of persulfate or hydrogen persulfate to total organic carbon in the soil is 3:4 to 3:

2.

5. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The persulfate includes sodium persulfate, sodium hydrogen persulfate or potassium persulfate.

6. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The persulfate is sodium persulfate.

7. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The ball milling is carried out in a ball mill, and the ball mill is selected from a planetary mill, a vibrating ball mill or a stirring ball mill.

8. The method for remediating organic contaminated soil by ball milling activated persulfate according to claim 1, characterized in that: The ball mill is a planetary ball mill.

Images