Pyrite-reinforced Fenton system and method for removing polycyclic aromatic hydrocarbon in underground water by using pyrite-reinforced Fenton system

Abstract

The invention relates to the technical field of water treatment, and provides a pyrite-reinforced Fenton system and a method for removing polycyclic aromatic hydrocarbon in underground water by using the pyrite-reinforced Fenton system. The pyrite reinforced Fenton system comprises hydrogen peroxide, ferrous iron and pyrite, wherein the adding amount ratio of the hydrogen peroxide to the ferrous iron to the pyrite is (0.1-5.0) mmol: (0.06-3.0) mmol: (0.5-1.0) g. The method for removing the polycyclic aromatic hydrocarbon in the underground water by adopting the pyrite-reinforced Fenton system comprises the following steps that ferrous iron, pyrite and hydrogen peroxide are sequentially added into an underground water solution polluted by the polycyclic aromatic hydrocarbon, treated underground water is obtained after the reaction is finished, the molar ratio of the ferrous iron to the polycyclic aromatic hydrocarbon is 0.6-30: 1, the molar ratio of the hydrogen peroxide to the polycyclic aromatic hydrocarbon is 1-50: 1, and the molar ratio of the pyrite to the polycyclic aromatic hydrocarbon is 1-20: 1. The mass concentration ratio of the pyrite to the polycyclic aromatic hydrocarbon is (35-80): 1. The pyrite is the most common iron sulfide mineral in the earth crust, raw materials are easy to obtain and environmentally friendly, and the pyrite can serve as a reducing agent to promote reduction of Fe (III) into Fe (II), increase the concentration of dissolved Fe (II), reduce generation of iron mud, increase the utilization rate of agents and promote continuous degradation of pollutants.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental treatment, relates to groundwater treatment technology, and specifically relates to a pyrite-enhanced Fenton system and a method for removing polycyclic aromatic hydrocarbons in groundwater by using the system. Background Art

[0002] With the promulgation and implementation of a series of laws and regulations, the investigation and remediation of contaminated sites have received more and more attention from people from all walks of life. Since the early industrial enterprises did not pay enough attention to environmental protection, the process of urbanization has led to a large number of abandoned or relocated old petrochemical plants, pesticide plants, coking plants, gas plants and other enterprises, leaving behind many industrial contaminated sites. Among them, polycyclic aromatic hydrocarbons (PAHs) are one of the main characteristic pollutants in the contaminated sites of the above-mentioned enterprises.

[0003] PAHs are formed by two or more benzene rings sharing a carbon atom. They enter the soil and groundwater environment through chemical production, incomplete combustion of coal and petroleum fuels, etc., causing serious site pollution. PAHs are semi-volatile, persistent, difficult to degrade and highly toxic, and have strong carcinogenic, teratogenic and mutagenic effects. my country's Ministry of Ecology and Environment has included 7 PAHs, including naphthalene (NAP), fluoranthene, and benzo[a]pyrene, in the list of priority controlled pollutants. Among them, NAP has good solubility in water, which leads to its frequent detection in contaminated groundwater, causing serious harm to the environment. Therefore, establishing efficient PAHs-contaminated groundwater remediation technology and methods, especially how to efficiently treat NAP-contaminated groundwater, is the key to solving groundwater PAHs pollution and is a priority issue that needs to be urgently addressed in my country's current contaminated sites.

[0004] At present, the remediation of PAHs-contaminated groundwater is mainly divided into in-situ remediation technology and ex-situ remediation technology. Due to the large amount of ex-situ remediation engineering, the disturbance to the underground environment, and the risk of exposure and diffusion of pollutants in the ground environment, more and more researchers tend to prefer more environmentally friendly in-situ remediation technology. In-situ remediation technology mainly includes in-situ thermal desorption, chemical oxidation, bioremediation and other technologies. Thermal desorption technology is one of the commonly used in-situ remediation technologies for PAHs, but it has the disadvantages of high energy consumption, high remediation cost, and continuous heating during the remediation process will damage the original ecological environment and geological environment of the remediation area; bioremediation technology has problems such as PAHs difficult degradation, low mineralization rate, long remediation cycle, and the need to add enhanced bacterial agents. In-situ chemical oxidation technology (ISCO) has obvious advantages such as rapidity, high efficiency, and moderate economy, and has become the fastest-growing and most widely used contaminated groundwater remediation technology.

[0005] ISCO commonly used oxidants include potassium permanganate, hydrogen peroxide (H2O2), persulfate, calcium peroxide, etc. 2 O 2 The Fenton system has the characteristics of high efficiency, rapid reaction, thorough treatment, and easy operation. 2 O 2 After being catalyzed by Fe(II), it can produce hydroxyl radicals with strong oxidizing properties, which can then oxidize and remove most organic matter, making it a widely used treatment technology. However, in the actual remediation of PAHs-contaminated sites, the Fenton system has problems such as a narrow pH range, poor circulation of Fe(II) and Fe(III) in the system, low reagent utilization, and greater impact from water quality and environment, which in turn affects its effectiveness in practical applications. Summary of the invention

[0006] The present invention aims to overcome the shortcomings of existing in-situ chemical oxidation technology in the practice of contaminated groundwater remediation, and to improve the existing H 2 O 2 The Fenton system is improved to provide a pyrite-enhanced Fenton system and a method for removing polycyclic aromatic hydrocarbons in groundwater, thereby achieving efficient and lasting treatment of pollutants and reducing the cost of groundwater remediation in contaminated sites.

[0007] The technical principle of the present invention is as follows: the conventional Fenton system has good oxidation performance and can quickly and efficiently remove most organic pollutants at room temperature. However, in actual groundwater, due to the high pH and the presence of a large amount of inorganic ions, it is not conducive to the degradation of polycyclic aromatic hydrocarbons by the Fenton system. Pyrite is the most common iron sulfide mineral in the earth's crust, with a chemical composition of FeS2, and has good environmental friendliness. On the one hand, FeS2 can act as an electron donor to react with Fe(III) to accelerate the Fe(II) / Fe(III) cycle. Since Fe(III) is easier to precipitate than Fe(II), it can reduce the generation of iron mud and improve the utilization rate of the reagent. On the other hand, FeS2 can also slowly release Fe(II) to avoid excessive Fe(II) consuming active oxygen species, resulting in poor pollutant degradation effect. In addition, pyrite itself is a product of nature, and its addition will not cause secondary pollution to the underground environment. Therefore, it is promising to use pyrite as an enhancer to promote the traditional Fenton system to treat PAH-contaminated groundwater. The present invention introduces pyrite into the traditional Fenton system to reduce Fe(III), promote the regeneration of Fe(II), and reduce the generation of iron sludge, thereby overcoming the limitations of the existing traditional Fenton system and achieving efficient and durable degradation of PAHs in groundwater.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a pyrite-enhanced Fenton system for removing polycyclic aromatic hydrocarbons in groundwater, comprising hydrogen peroxide, ferrous iron and pyrite. The dosage ratio of hydrogen peroxide, ferrous iron and pyrite is 0.1-5.0 mmol: 0.06-3.0 mmol: 0.5-1.0 g.

[0010] Furthermore, the dosage ratio of hydrogen peroxide, ferrous iron and pyrite is 0.5-5.0 mmol: 0.3-3.0 mmol: 0.5-1.0 g; the ferrous iron is ferrous sulfate heptahydrate.

[0011] In a second aspect of the present invention, a method for removing polycyclic aromatic hydrocarbons in groundwater using the above-mentioned pyrite-enhanced Fenton system is provided: divalent iron, pyrite and hydrogen peroxide are sequentially added to a groundwater solution contaminated with polycyclic aromatic hydrocarbons, and treated groundwater is obtained after the reaction is completed, wherein the molar ratios of divalent iron, hydrogen peroxide and polycyclic aromatic hydrocarbons are 0.6-30:1 and 1-50:1 respectively, and the mass concentration ratio of pyrite to polycyclic aromatic hydrocarbons is 35-80:1.

[0012] Preferably, the polycyclic aromatic hydrocarbons are one or more of fluoranthene, naphthalene and phenanthrene, and the concentration range of fluoranthene, naphthalene and phenanthrene is 0.1-30 mg / L.

[0013] Preferably, the pH value of the PAH-contaminated groundwater solution is adjusted to 3 to 9 before treatment. Experimental results show that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater with an initial pH of 3 to 9, while the traditional Fenton system can usually only efficiently degrade pollutants when the initial pH is 3, effectively improving the suitable treatment range of contaminated water.

[0014] Preferably, the reaction temperature during wastewater treatment is 20±5°C (room temperature reaction), and stirring is performed during the reaction. The stirring method is preferably magnetic stirring, and the speed is 500-700 r·min -1 , the reaction time is 1 to 2 hours.

[0015] Preferably, the PAH-contaminated groundwater solution of the present invention can contain one or more of inorganic anions and humus. - ), sulfate ion (SO 4 2- ) and nitrate ions (NO 3 - ), and humic acid was added to simulated polluted water in another experiment. The results showed that the technology of the present invention has a good adaptability to inorganic anions and humic acid in aqueous solution and does not affect the effective removal of polycyclic aromatic hydrocarbons.

[0016] The beneficial protection and effects of the present invention are as follows:

[0017] Compared with the prior art, the positive effects of the present invention are as follows: ① pyrite is the most common iron sulfide mineral in the earth's crust. Not only is the raw material easy to obtain, but its addition will not cause secondary pollution to the underground environment; ② pyrite can be used as a reducing agent to promote the reduction of Fe(III) to Fe(II), increase the concentration of dissolved Fe(II), reduce the generation of iron mud, improve the utilization rate of reagents, and promote the continuous degradation of pollutants; ③ pyrite can slowly release Fe(II), avoiding excessive Fe(II) consuming active oxygen substances, resulting in poor pollutant degradation effect; ④ the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater with an initial pH of 3 to 9, while the traditional Fenton system can usually only efficiently degrade pollutants when the initial pH is 3, effectively improving the suitable treatment range of contaminated water. ⑤ The technical operation steps of the present invention are simple, the cost is low, and the treatment effect is remarkable. It can efficiently and durably treat groundwater contaminated by polycyclic aromatic hydrocarbons containing inorganic anions and humus. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The removal rate of naphthalene in different systems in simulated groundwater varies with time in Example 1;

[0019] Figure 2 The figure is a graph showing the change of the removal rate of naphthalene of different concentrations in simulated groundwater over time in Example 2;

[0020] Figure 3 The removal rate of naphthalene in simulated groundwater under different initial pH conditions in Example 3 changes with time;

[0021] Figure 4 The figure is a graph showing the change in removal rate of naphthalene in simulated groundwater containing different chloride ion concentrations over time in Example 4;

[0022] Figure 5 is a graph showing the change in removal rate of naphthalene in simulated groundwater containing different sulfate ion concentrations over time in Example 5;

[0023] Figure 6 is a graph showing the change in removal rate of naphthalene in simulated groundwater containing different nitrate ion concentrations over time in Example 6;

[0024] Figure 7 is a graph showing the change in removal rate of naphthalene in simulated groundwater containing different organic matter concentrations over time in Example 7;

[0025] Figure 8 The removal rate of naphthalene in actual groundwater varies with time in Example 8;

[0026] Fig. 9This is a diagram showing the removal effect of different polycyclic aromatic hydrocarbons in actual groundwater by the pyrite-enhanced Fenton system in Example 9. DETAILED DESCRIPTION

[0027] The implementation of the present invention is described in detail below in conjunction with the embodiments of the present invention. The following embodiments are implemented on the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Example 1 Pyrite-enhanced Fenton system can effectively remove naphthalene

[0029] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0030] The method for removing polycyclic aromatic hydrocarbons in groundwater by using the above-mentioned pyrite-enhanced Fenton system is as follows: 250 mL of an aqueous solution containing an initial concentration of 12.8 mg / L of naphthalene is prepared to simulate groundwater contaminated by naphthalene, and 0.3 mmol of FeSO 4 7H 2 O and 1.0 g / L pyrite, 0.5 mmol hydrogen peroxide was added to start the reaction, the speed was controlled at 600 rpm, the reaction temperature was room temperature, the reaction time was 120 min, and samples were taken and analyzed at 0, 1, 5, 10, 30, 60 and 120 min, respectively.

[0031] The experimental results are as follows Figure 1 As shown, after 120 minutes of reaction, the removal rate of naphthalene in the pyrite-enhanced Fenton system reached 89.4% (the calculation formula of the removal rate is removal rate = naphthalene concentration at a given sampling time point / initial naphthalene concentration, the same below), indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene.

[0032] Comparative Example 1: Treatment of PAH-contaminated water by traditional Fenton system

[0033] A method for removing polycyclic aromatic hydrocarbons from groundwater using a traditional Fenton system is as follows: 250 mL of an aqueous solution containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) is prepared to simulate groundwater contaminated with naphthalene, and 0.3 mmol of FeSO is first added. 4 7H 2 O, then add 0.5mmol hydrogen peroxide to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, the reaction time to 120min, and sample analysis at 0, 1, 5, 10, 30, 60 and 120min respectively. The experimental results are shown in Figure 1As shown, after 120 min of reaction, the removal rate of naphthalene in the traditional Fenton system was only 56.4%.

[0034] By comparing Example 1 with Comparative Example 1, it can be seen that: under the same treatment object and other experimental conditions, the addition of pyrite increases the removal rate of naphthalene by 33.0%, and in the absence of pyrite, the degradation reaction of naphthalene in the Fenton system is rapid, and basically reaches equilibrium at 5 minutes, while in the Fenton system enhanced by pyrite, the degradation reaction of naphthalene continues, and basically reaches equilibrium at 120 minutes. The above results show that the Fenton system enhanced by pyrite provided by the present invention has high efficiency and durability in removing naphthalene.

[0035] Example 2 Pyrite-enhanced Fenton system can effectively remove different concentrations of naphthalene

[0036] This example explores the removal effect of the pyrite-enhanced Fenton system on naphthalene of different concentrations.

[0037] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratios of the hydrogen peroxide, Fe(II) and pyrite are 0.1mmol:0.06mmol:1.0g / L, 0.5mmol:0.3mmol:1.0g / L and 1.0mmol:0.6mmol:1.0g / L.

[0038] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: three portions of 250 mL aqueous solution containing initial naphthalene concentrations of 2.56 mg / L (0.02 mmol), 12.8 mg / L (0.1 mmol) and 25.6 mg / L (0.2 mmol) are prepared to simulate groundwater contaminated with naphthalene. In this embodiment, due to different initial concentrations of pollutants, different doses of hydrogen peroxide and Fe (II) are added to ensure that the molar ratio of oxidant / Fe (II) / pollutant is controlled to be 5 / 3 / 1. 0.06 mmol of FeSO 4 7H 2 O, 0.3 mmol FeSO 4 7H 2 O and 0.6 mmol FeSO 4 7H 2 O, then 1.0 g / L pyrite was added to the three simulated groundwater, and finally 0.1 mmol hydrogen peroxide, 0.5 mmol hydrogen peroxide and 1.0 mmol hydrogen peroxide were added respectively to start the reaction. The speed was controlled at 600 rpm, the reaction temperature was room temperature, the reaction time was 120 min, and samples were taken and analyzed at 0, 1, 5, 10, 30, 60 and 120 min, respectively.

[0039] The experimental results are as follows Figure 2 As shown, after 120 minutes of reaction, the removal rates of naphthalene with different initial concentrations (0.02 mmol, 0.1 mmol and 0.2 mmol) in the pyrite-enhanced Fenton system were 88.4%, 89.4% and 92.8%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene with different initial concentrations.

[0040] Example 3 Pyrite-enhanced Fenton system has excellent removal effect on naphthalene-contaminated groundwater with an initial pH of 3 to 9

[0041] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene under different simulated groundwater initial pH conditions.

[0042] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0043] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: five 250 mL aqueous solutions containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) are prepared to simulate groundwater contaminated with naphthalene, wherein the initial pH values ​​of four of the simulated groundwaters are adjusted to 3, 5, 7 and 9 respectively by adding 0.1 mmol of sulfuric acid or 0.1 mmol of sodium hydroxide, and the initial pH of the other simulated groundwater is not adjusted (the initial pH is 5.71). 0.3 mmol of FeSO 4 7H 2 O and 1.0g / L pyrite, then add 0.5mmol hydrogen peroxide to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, and the reaction time to 120min. The experimental results are as follows Figure 3 As shown, after 120 minutes of reaction, the removal rates of naphthalene under different initial pH conditions (3, 5, 5.71, 7 and 9) in the pyrite-enhanced Fenton system were 92.1%, 88.9%, 89.4%, 90.8% and 90.5%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater with an initial pH of 3 to 9, while the traditional Fenton system can usually only efficiently degrade pollutants when the initial pH is 3.

[0044] Example 4 Chloride ions have no effect on the removal effect

[0045] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene at different chloride ion concentrations.

[0046] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0047] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: four 250 mL aqueous solutions containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) are prepared to simulate groundwater contaminated with naphthalene, wherein 1.0 mmol, 10 mmol and 100 mmol of sodium chloride are added to three of the simulated groundwaters, respectively, and no sodium chloride is added to the other simulated groundwater as a control group. 0.3 mmol of FeSO 4 7H 2 O and 1.0g / L pyrite, then add 0.5mmol hydrogen peroxide to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, and the reaction time to 120min. The experimental results are as follows Figure 4 As shown, after 120 minutes of reaction, the removal rates of naphthalene at different chloride ion concentrations (0, 1.0 mmol, 10 mmol and 100 mmol) in the pyrite-enhanced Fenton system were 89.4%, 88.0%, 85.7% and 91.1%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater containing an initial chloride ion concentration of 0 to 100 mmol, and the system has good tolerance to common chloride ions in actual groundwater.

[0048] Example 5 Sulfate ions have no effect on the removal effect

[0049] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene at different sulfate ion concentrations.

[0050] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0051] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: four 250 mL aqueous solutions containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) are prepared to simulate groundwater contaminated with naphthalene, wherein 1.0 mmol, 10 mmol and 100 mmol of sodium sulfate are added to three of the simulated groundwaters, respectively, and no sodium sulfate is added to the other simulated groundwater as a control group. 0.3 mmol of FeSO 4 7H 2 O and 1.0g / L pyrite, then add 0.5mmol hydrogen peroxide to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, and the reaction time to 120min. The experimental results are as follows Figure 5 As shown, after 120 minutes of reaction, the removal rates of naphthalene at different sulfate ion concentrations (0, 1.0 mmol, 10 mmol and 100 mmol) in the pyrite-enhanced Fenton system were 89.4%, 86.5%, 86.9% and 85.6%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater containing an initial sulfate ion concentration of 0 to 100 mmol, and the system has good tolerance to sulfate ions commonly found in actual groundwater.

[0052] Example 6 Nitrate ions have no effect on the removal effect

[0053] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene at different nitrate ion concentrations.

[0054] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0055] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: four 250 mL aqueous solutions containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) are prepared to simulate groundwater contaminated with naphthalene, wherein 1.0 mmol, 10 mmol and 100 mmol of sodium nitrate are added to three of the simulated groundwaters, respectively, and no sodium nitrate is added to the other simulated groundwater as a control group. 0.3 mmol of FeSO 4 7H 2 O and 1.0 g / L pyrite, and then 0.5 mmol hydrogen peroxide was added to start the reaction, the speed was controlled at 600 rpm, the reaction temperature was room temperature, and the reaction time was 120 min.

[0056] The experimental results are as follows Figure 6 As shown, after 120 minutes of reaction, the removal rates of naphthalene at different nitrate ion concentrations (0, 1.0 mmol, 10 mmol and 100 mmol) in the pyrite-enhanced Fenton system were 89.4%, 88.8%, 87.7% and 89.5%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater containing an initial concentration of 0 to 100 mmol nitrate ions, and the system has good tolerance to common nitrate ions in actual groundwater.

[0057] Example 7 Organic matter has no effect on removal effect

[0058] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene at different organic matter concentrations.

[0059] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 0.5 mmol:0.3 mmol:1.0 g / L.

[0060] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: four 250 mL aqueous solutions containing an initial naphthalene concentration of 12.8 mg / L (0.1 mmol) are prepared to simulate groundwater contaminated with naphthalene, wherein 1.0 mg / L, 10 mg / L and 100 mg / L of humus are added to three of the simulated groundwaters, respectively, and no humus is added to the other simulated groundwater as a control group. 0.3 mmol of FeSO 4 7H 2 O and 1.0g / L pyrite, add 0.5mmol hydrogen peroxide to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, and the reaction time to 120min. The experimental results are as follows Figure 7 As shown, after 120 minutes of reaction, the removal rates of naphthalene at different organic matter concentrations (0, 1.0 mg / L, 10 mg / L and 100 mg / L) in the pyrite-enhanced Fenton system were 89.4%, 88.1%, 89.4% and 87.0%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene-contaminated groundwater containing an initial organic matter concentration of 0 to 100 mg / L, and the system has good tolerance to common organic matter in actual groundwater.

[0061] In combination with Examples 3, 4, 5, 6 and 7, it is proved that the pyrite-enhanced Fenton system provided by the present invention has a good effect on the removal of naphthalene in a complex water quality environment, with a removal rate of more than 80%, and is applicable to a complex groundwater quality environment.

[0062] Example 8 Actual naphthalene-contaminated groundwater treatment

[0063] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on naphthalene in actual groundwater.

[0064] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratios of hydrogen peroxide, Fe(II) and pyrite are 0.5mmol:0.3mmol:1.0g / L and 5.0mmol:3.0mmol:1.0g / L.

[0065] A method for removing polycyclic aromatic hydrocarbons from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: Take two 250 mL portions of groundwater from Minhang District, Shanghai, which contains 12.8 mg / L (0.1 mmol) of naphthalene. Add 0.3 mmol of FeSO 4 7H 2 O and 3.0 mmol FeSO 4 7H 2 O, then add 1.0g / L pyrite to both actual groundwater, and finally add 0.5mmol hydrogen peroxide and 5.0mmol hydrogen peroxide respectively to start the reaction, control the speed to 600rpm, the reaction temperature to room temperature, the reaction time to 120min, and sample analysis at 0, 1, 5, 10, 30, 60 and 120min respectively. The experimental results are shown in Figure 8 As shown, after 120 minutes of reaction, the removal rates of naphthalene in the two groups of pyrite-enhanced Fenton systems were 12.5% ​​and 82.3%, respectively. This is because the actual groundwater has a strong buffering capacity, which makes soluble iron easy to precipitate, and it is necessary to adjust the reagent dosage ratio to achieve efficient removal of pollutants. In addition, the above results also show that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on naphthalene in actual groundwater.

[0066] Example 9 Treatment of different PAHs in actual groundwater

[0067] This example explores the removal effect of a pyrite-enhanced Fenton system provided by the present invention on different polycyclic aromatic hydrocarbons in actual groundwater.

[0068] The pyrite-enhanced Fenton system provided in this embodiment includes hydrogen peroxide, Fe(II) and pyrite, and the dosage ratio of the hydrogen peroxide, Fe(II) and pyrite is 5.0 mmol:3.0 mmol:1.0 g / L.

[0069] A method for removing PAHs from groundwater based on the above-mentioned pyrite-enhanced Fenton system is as follows: three portions of 250 mL of groundwater from Minhang District, Shanghai, containing 12.8 mg / L (0.1 mmol) of naphthalene (NAP), 1.0 mg / L (5.6 μmol) of phenanthrene (PHE), and 0.2 mg / L (1.0 μmol) of fluoranthene (FLT), respectively. 3.0 mmol of FeSO 4 7H 2 O and 1.0g / L pyrite, and finally added 5.0mmol hydrogen peroxide to start the reaction, the speed was controlled at 600rpm, the reaction temperature was room temperature, the reaction time was 120min, and samples were taken and analyzed at 0, 1, 5, 10, 30, 60 and 120min. The experimental results are shown in Fig. 9 As shown, after 120 minutes of reaction, the removal rates of naphthalene, phenanthrene and fluoranthene in the pyrite-enhanced Fenton system were 82.3%, 99.1% and 97.2%, respectively, indicating that the pyrite-enhanced Fenton system provided by the present invention has a good removal effect on polycyclic aromatic hydrocarbons in actual groundwater.

[0070] From the above experimental results, it can be seen that the pyrite-enhanced Fenton system can achieve a higher PAH removal rate and broaden the pH range of contaminated groundwater; adjusting the pH of the contaminated water to be treated to 3-9 before treatment helps to enhance the treatment effect; at the same time, the technology of the present invention has a good adaptability to inorganic anions and humic acid in aqueous solution and does not affect the effective removal of PAHs.

[0071] The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A pyrite-enhanced Fenton system, characterized in that: The invention is used for removing polycyclic aromatic hydrocarbons in groundwater, and comprises hydrogen peroxide, ferrous iron and pyrite, wherein the dosage ratio of hydrogen peroxide, ferrous iron and pyrite is 0.1-5.0 mmol: 0.06-3.0 mmol: 0.5-1.0 g.

2. The pyrite-enhanced Fenton system according to claim 1, characterized in that: in, The divalent iron is ferrous sulfate heptahydrate.

3. The pyrite-enhanced Fenton system according to claim 1, characterized in that: in, The dosage ratio of hydrogen peroxide, divalent iron and pyrite is 0.5-5.0 mmol: 0.3-3.0 mmol: 0.5-1.0 g.

4. A method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system, characterized in that: Divalent iron, pyrite and hydrogen peroxide are added sequentially to a groundwater solution contaminated with polycyclic aromatic hydrocarbons, and treated groundwater is obtained after the reaction is completed, wherein the molar ratios of divalent iron, hydrogen peroxide and polycyclic aromatic hydrocarbons are 0.6-30:1 and 1-50:1 respectively, and the mass concentration ratio of pyrite to polycyclic aromatic hydrocarbons is 35-80:

1.

5. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 4, characterized in that: in, The polycyclic aromatic hydrocarbons are one or more of fluoranthene, naphthalene and phenanthrene, The concentration ranges of fluoranthene, naphthalene and phenanthrene are all 0.1 to 30 mg / L.

6. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 4, characterized in that: in, Before treatment, the pH value of the PAH-contaminated groundwater solution is adjusted to 3-9.

7. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 4, characterized in that: in, The reaction temperature is 20±5°C, stirring is performed during the reaction, and the reaction time is 60 to 120 minutes.

8. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 7, characterized in that: in, The stirring method is magnetic stirring, and the speed is 500-700 r·min -1 .

9. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 4, characterized in that: in, Groundwater contaminated by PAHs may contain one or more types of inorganic anions and humus.

10. The method for removing polycyclic aromatic hydrocarbons from groundwater using a pyrite-enhanced Fenton system according to claim 9, characterized in that: in, The inorganic anions are selected from one or more of chloride ions, sulfate ions and nitrate ions.

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