A sulfurized nano-zero-valent iron material, its preparation method and application

Abstract

The present invention discloses a sulfurized nano zero-valent iron material, its preparation method and application, including: a core-shell structure sulfurized nano zero-valent iron material and a preparation method, the inner core of the sulfurized nano zero-valent iron is zero-valent iron, and the outer shell is Fe9S 10 , calculated by the mass of the sulfurized nano zero-valent iron, the mass percentage of zero-valent iron is 70-80%, and the mass percentage of the iron sulfide is 20-30%; the preparation method includes: placing iron powder in an H2S gas atmosphere for calcination, after the calcination is completed, cooling to room temperature to obtain the sulfurized nano zero-valent iron material. This material can be used for in-situ remediation of chlorinated hydrocarbon organic pollutants in groundwater. Compared with the prior art, the prepared sulfurized nano zero-valent iron is less likely to be oxidized and can overcome the problem of rapid passivation of nano zero-valent iron during the remediation process.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental remediation, and particularly relates to a sulfurized nano zero-valent iron material, a preparation method thereof, and an application thereof. Background Art

[0002] For more than two decades, the in-situ groundwater remediation technology based on zero-valent iron has received extensive attention and in-depth research at home and abroad. Due to its strong reducibility (Fe 2+ +2e - →Fe(s), E 0 =-0.44V), and its abundant source and low price, it has been widely used in the field of environmental remediation to remove and degrade organic or inorganic pollutants. However, there are many technical defects in current zero-valent iron. For example, nano zero-valent iron is prone to aggregate into large particles due to its magnetism and high surface energy, losing its underground fluidity; its activity is very high but its lifespan is very short, and it cannot continuously degrade pollutants; the surface of zero-valent iron is hydrophilic, and its binding property with hydrophobic organic pollutants is poor; an oxide film will form on the surface of zero-valent iron, greatly hindering the contact between the active component and the target pollutant, and thus reducing the activity of zero-valent iron, etc.

[0003] In recent years, sulfidation modification of the surface of zero-valent iron has gradually become a new type of zero-valent iron modification method. Research shows that after sulfidation modification of the surface of zero-valent iron, it can have the following advantages:

[0004] (1) A sulfide layer can be formed on the surface of zero-valent iron to replace the original oxide layer. Since the sulfide is a semiconductor material, compared with the original iron oxide layer on the surface of zero-valent iron, it has excellent electron conductivity and is conducive to transferring the electrons given by the zero-valent iron core.

[0005] (2) The sulfide also has good hydrophobicity, which is conducive to the attachment of chlorinated hydrocarbon oily organic matters, thereby promoting the contact between pollutants and their active sites, and then being degraded.

[0006] (3) The sulfur element in the sulfide can inhibit H3O + from obtaining electrons, and then forming hydrogen gas, thereby greatly inhibiting the competition of H3O + for electrons with the target pollutant.

[0007] Currently, the existing methods for preparing sulfurized nano zero-valent iron mainly include chemical aqueous phase synthesis method and ball milling method. However, there are the following deficiencies:

[0008] (1) The aqueous phase chemical synthesis method is relatively cumbersome. During the process, zero-valent iron and sulfide are extremely easy to be oxidized, and a large amount of high-salinity wastewater is generated during the synthesis process.

[0009] (2) For the ball milling synthesis method, the energy consumption is relatively high, and it is difficult to reach the nanoscale.

[0010] Therefore, in combination with the above technical means, it is necessary to explore a new preparation method of sulfided nano zero-valent iron to solve the above technical problems. Gas-phase sulfidation modification of nano zero-valent iron to meet the needs of practical engineering is one of the solutions. Summary of the Invention

[0011] The present invention discloses a sulfided nano zero-valent iron material, its preparation method and application. This material is more resistant to oxidation compared with the existing sulfided nano zero-valent iron, and the prepared sulfided nano zero-valent iron has a high removal efficiency for chlorinated hydrocarbon organic pollutants. The preparation method is not only simple to operate but also has a short preparation period.

[0012] The specific technical solutions are as follows:

[0013] A sulfided nano zero-valent iron material has a core-shell structure. The core of the sulfided nano zero-valent iron material is zero-valent iron, and the shell is Fe9S 10 ; Based on the mass of the sulfided nano zero-valent iron, the mass percentage of the zero-valent iron is 70-80%, and the mass percentage of the iron sulfide is 20-30%.

[0014] The present invention also provides a preparation method of a sulfided nano zero-valent iron material, including:

[0015] Placing iron powder in an H2S gas atmosphere for calcination. After the calcination is completed, it is cooled to room temperature to obtain a sulfided nano zero-valent iron material. Further, the iron powder is zero-valent iron powder or iron filings, and its particle size is 20nm-500nm;

[0016] Preferably, its particle size is 100nm. Under this condition, the relative content of zero-valent iron inside the generated sulfided nano zero-valent iron is appropriate, and the sulfided nano zero-valent iron has a better removal effect on chlorinated hydrocarbon organic pollutants.

[0017] Further, the volume concentration of the H2S gas is 0.5%-5%, and the gas flow rate is 10-100mL / min;

[0018] Further, in the preparation method of the sulfided nano zero-valent iron material, the iron powder is first placed in an inert gas atmosphere, and then the inert gas is replaced with H2S gas; the inert gas includes one of nitrogen, argon or helium.

[0019] Further, the calcination temperature is 400-500°C, the heating rate is 3-10°C / min, and the calcination time is 60-120min.

[0020] Preferably, the calcination temperature is 400°C and the calcination time is 60min. Under this condition, the relative content of zero-valent iron inside the generated sulfided nano zero-valent iron is appropriate, and the sulfided nano zero-valent iron has a better removal effect on chlorinated hydrocarbon organic pollutants.

[0021] Under heating conditions, H2S can react with the oxide layer (Fe x O y ) on the surface of zero-valent iron particles or with a part of the inner core Fe 0 to form an iron sulfide layer, which can then replace the surface oxide of zero-valent iron particles. Iron sulfide is a semiconductor that can accelerate the rate of electron transfer from the inner core of zero-valent iron to target pollutants. Moreover, iron sulfide has good hydrophobicity and strong affinity for hydrophobic pollutants such as chlorinated hydrocarbons, thereby enhancing its performance in degrading target pollutants. On the other hand, the presence of iron sulfide can inhibit the hydrogen evolution reaction between zero-valent iron materials and water molecules, that is, weaken the competition for electrons between water molecules and pollutants, and thus increase its electron efficiency. However, if the iron sulfide layer is too thick, although the electron efficiency can be close to 100%, it will lead to a decrease in the relative content of zero-valent iron inside the material particles. And the zero-valent iron inside the particles is the only electron donor for degrading pollutants. Too low a content of zero-valent iron will also affect its reaction activity. Therefore, in the parameter settings of the sulfidation process: the calcination temperature, calcination time, heating rate, hydrogen sulfide content, and particle size of zero-valent iron will all affect the thickness of the iron sulfide layer. For example, too long a calcination time, too fast a heating rate, too small a particle size of zero-valent iron particles, and too high a hydrogen sulfide content will all lead to excessive sulfidation, resulting in a decrease in the content of zero-valent iron inside the particles. Although the electron efficiency can be increased, the rate of degrading pollutants will be affected.

[0022] The present invention also provides an application of a sulfidated nano zero-valent iron material or a sulfidated nano zero-valent iron material prepared by the above preparation method in in-situ remediation of groundwater containing chlorinated hydrocarbon organic pollutants.

[0023] Further, the chlorinated hydrocarbon organic pollutants are one or more of vinyl chloride, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, dichloromethane, tetrachloroethane, chloroform, carbon tetrachloride, hexachlorobutadiene, and trichloropropane.

[0024] Preferably, the chlorinated hydrocarbon organic pollutant is trichloroethylene, and the sulfidated nano zero-valent iron has a better removal effect on trichloroethylene.

[0025] Further, the application of the sulfidated nano zero-valent iron material in in-situ remediation of groundwater containing chlorinated hydrocarbon organic pollutants includes: adding the sulfidated nano zero-valent iron material to the groundwater containing chlorinated hydrocarbon organic pollutants to remove the chlorinated hydrocarbon organic pollutants in the groundwater.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention prepares a sulfurized nano-zero-valent iron material by using zero-valent iron and H2S gas under heating conditions. A stable iron sulfide compound is formed on the surface of the material, which is more resistant to oxidation and has higher electron efficiency compared with the nano-zero-valent iron prepared by the existing liquid-phase ball milling method, and can overcome the problem of rapid passivation of nano-zero-valent iron during the repair process;

[0028] (2) The method of the present invention is simple to operate, has a short preparation period, has a high removal efficiency for chlorinated organic pollutants, and reduces and converts them into pollution-free ethane, acetylene, ethylene, etc., and is suitable for in-situ remediation of groundwater. Description of the Drawings

[0029] Figure 1 It is a transmission electron microscope image of the sulfurized nano-zero-valent iron prepared by gas-phase chemical thermal synthesis in Example 1.

[0030] Figure 2 It is an XRD pattern of the sulfurized nano-zero-valent iron prepared by gas-phase chemical thermal synthesis in Example 1. Detailed Embodiments

[0031] The present invention will be further described below in conjunction with specific embodiments. The following are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto.

[0032] Example 1

[0033] (1) Preparation of the sulfurized nano-zero-valent iron material

[0034] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tube furnace. An inert gas is introduced from one side of the tube furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance gas is 98% nitrogen), the gas flow rate is 50 mL / min, heat up to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0035] Characterize the sulfurized nano-zero-valent iron material prepared in this example, and the results are as Figure 1 、 2 shown; Figure 1 is a transmission electron microscope photograph of the sulfurized nano-zero-valent iron prepared in Example 1. The results show that the sulfurized nano-zero-valent iron prepared by this gas-phase thermal synthesis method is a typical core-shell structure, with its inner core being zero-valent iron and the outer shell being iron sulfide; the XRD spectrum shows that the sulfurization form of iron is Fe9S 10 , which is different from the iron sulfide of sulfurized nano-zero-valent iron synthesized by other liquid-phase methods or ball milling methods, such as FeS or Fe7S8, etc.; from Figure 1 、 Figure 2It can be concluded that H2S gas and zero-valent iron can react under high-temperature conditions to form iron sulfide on the particle surface, and finally nano-zero-valent iron sulfide is prepared. Based on the mass of the nano-zero-valent iron sulfide material, the mass percentage of zero-valent iron is 74%, and the mass percentage of iron sulfide is 26%.

[0036] To evaluate the utilization efficiency of electrons provided by zero-valent iron in the nucleus during the degradation of pollutants by the material, we use electron efficiency for evaluation. That is, for a reaction system such as anaerobic-zero-valent iron-TCE-water (where there are only two oxidants, water and the target pollutant in the system), two types of efficiency (or selectivity) are defined here: that is, in the reaction system, the Fe consumed for degrading TCE 0 or the Fe consumed for HER 0 accounts for the proportion of the total amount of zero-valent iron contained in the initially added material;

[0037]

[0038] In Equation (1) and are the contents of Fe in the initial and final material particles in the reaction system 0 ; the other is the electron utilization efficiency (ε e ), that is, the amount of electrons consumed for degrading TCE (provided by Fe in the material 0 ) accounts for the proportion of the total amount of electrons released by Fe in the material 0 ; to calculate the electron efficiency during the degradation reaction, assumptions are made about the stoichiometric coefficients of the following half-reactions.

[0039] Fe 0 →Fe 2+ +2 e - (2)

[0040] Chlorinated hydrocarbon + n·e - + m·H + →Products + g·Cl - (3)

[0041] 2H+ + 2e- → H2↑ (4)

[0042] In Equation (3), the values of n, m, and g can be determined according to the form of the product. The calculation method of the overall n value during the TCE dechlorination process is as follows:

[0043]

[0044] In Equation (5), n i is the stoichiometric coefficient in reaction (3) when TCE is dechlorinated and degraded to product i, and p i is the number of moles of product i. Generally speaking, the electron efficiency (εe ) Calculate using the following formula:

[0045]

[0046] In Equation (6), is the number of moles of hydrogen gas generated during the TCE degradation process.

[0047] According to existing research reports, after mixing nano zero-valent iron powder and elemental sulfur powder in HEPES buffer solution and reacting for 24 h, sulfurized nano zero-valent iron is obtained, denoted as Material I; nano zero-valent iron is prepared by adding sodium borohydride to an Fe 3+ solution, reacting for 20 min, and adding sodium thiosulfate for sulfidation to prepare sulfurized nano zero-valent iron, denoted as Material II; nano zero-valent iron powder and elemental sulfur powder are mixed and sealed in a ball milling jar under an argon atmosphere; using a planetary ball mill, after milling for 20 hours, a ball-milled sulfurized nano zero-valent iron material is obtained, denoted as Material III; a comparison is made between the sulfurized nano zero-valent iron prepared by the ball milling method and the liquid phase method and the sulfurized nano zero-valent iron prepared by this method for the degradation and removal of organic pollutants in water.

[0048] (2) Degradation and removal of organic pollutants in water

[0049] Using trichloroethylene as the target pollutant, the activities of the sulfurized nano zero-valent iron material, Material I, Material II, and Material III prepared by this method were investigated; the specific implementation steps were as follows: add 0.026 g of sulfurized nano zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water blown with nitrogen for 1 h), the mass concentration of sulfurized nano zero-valent iron is 1 g / L, tighten the lid with a Teflon septum, and then inject 15 μL of trichloroethylene working solution (17.9 mg / L) using a syringe. The initial concentration of trichloroethylene is 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that when the sulfurized nano zero-valent iron material prepared by this method was added and reacted for 6 h, the degradation and removal rate of trichloroethylene was 97%, and the electron efficiency reached 95%; when Material I was added and reacted for 6 h, the degradation and removal rate of trichloroethylene was 30%, and the electron efficiency was 70%; when Material II was added and reacted for 6 h, the degradation and removal rate of trichloroethylene was 50%, and the electron efficiency was 30%; when Material III was added and reacted for 6 h, the degradation and removal rate of trichloroethylene was 40%, and the electron efficiency was 24%.

[0050] In this embodiment, the degradation and removal rate of trichloroethylene by the sulfidated nano-zero-valent iron prepared by this method is higher than that of the sulfidated nano-zero-valent iron prepared by the ball milling method and the liquid phase method, and the electron efficiency is also higher than that of the sulfidated nano-zero-valent iron prepared by the ball milling method and the liquid phase method. It can be concluded that the sulfidated nano-zero-valent iron prepared by this method has obvious advantages over the sulfidated nano-zero-valent iron prepared by the prior art in terms of both the degradation and removal rate of the target pollutant and the electron efficiency.

[0051] Example 2

[0052] (1) Preparation of sulfidated nano-zero-valent iron material

[0053] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tubular furnace. Pass an inert gas into one side of the tubular furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 0.5%, balance 99.5% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0054] (2) Degradation and removal of organic pollutants in water

[0055] Using trichloroethylene as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfidated nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h), with the mass concentration of sulfidated nano-zero-valent iron being 1 g / L. Seal it tightly with a lid with a Teflon septum, and then inject 15 μL of trichloroethylene stock solution (17.9 mg / L) using a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored at regular intervals using gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene was 92% and the electron efficiency was 90%.

[0056] Example 3

[0057] (1) Preparation of sulfidated nano-zero-valent iron material

[0058] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tubular furnace. Pass an inert gas into one side of the tubular furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 3 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0059] (2) Degradation and removal of organic pollutants in water

[0060] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, followed by 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The bottle was tightly capped with a lid equipped with a Teflon septum, and then 15 μL of trichloroethylene working solution (17.9 mg / L) was injected using a syringe. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L, and the initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored at regular intervals using gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene was 96.5%, and the electron efficiency was 95.5%.

[0061] Example 4

[0062] (1) Preparation of sulfidated nano-zero-valent iron material

[0063] 1 g of zero-valent iron powder (particle size 100 nm) was separately placed in the furnace tube of a tubular furnace. An inert gas was introduced from one side of the tubular furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, H2S gas (content 2%, balance 98% nitrogen) was switched in, and the gas flow rate was 50 mL / min. The temperature was increased to 450 °C (denoted as S-nZVI-450@ROR-1 °C / min-60) and 500 °C (denoted as S-nZVI-500@ROR-1 °C / min-60) at a heating rate of 5 °C / min respectively. After calcination for 60 min, it was cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0064] (2) Degradation and removal of organic pollutants in water

[0065] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water blown with nitrogen for 1 h) was added. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid with a Teflon septum, and then 15 μL of trichloroethylene working solution (17.9 mg / L) was injected with a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene by S-nZVI-450@ROR-1℃ / min-60 was 95%, and the electron efficiency was 97%; the degradation and removal rate of trichloroethylene by S-nZVI-500@ROR-1℃ / min-60 was 90%, and the electron efficiency was 97.2%. When the temperature was raised to 450 °C and 500 °C, although the electron efficiency was higher than that at 400 °C in Example 1, the removal effect of trichloroethylene was lower than that at 400 °C. The reason was that too high a calcination temperature would make the iron sulfide layer too thick, reducing the relative proportion of zero-valent iron, thereby affecting the reaction activity and resulting in a decrease in the removal rate.

[0066] Example 5

[0067] (1) Preparation of sulfidated nano-zero-valent iron material

[0068] 1 g of zero-valent iron powder (particle size 100 nm) was respectively placed in the furnace tube of a tube furnace. An inert gas was introduced from one side of the tube furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, the H2S gas (content 2%, balance 98% nitrogen) was switched, and the gas flow rate was 50 mL / min. The temperature was raised to 400 °C at a heating rate of 5 °C / min and calcined for 90 min (denoted as S-nZVI-400@ROR-5℃ / min-90) and 120 min (denoted as S-nZVI-400@ROR-15℃ / min-120) respectively, and then cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0069] (2) Degradation and removal of organic pollutants in water

[0070] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, followed by 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid equipped with a Teflon septum, and then 15 μL of trichloroethylene stock solution (17.9 mg / L) was injected using a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored at regular intervals using gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene by S-nZVI-400@ROR-5℃ / min-90 was 92%, and the electron efficiency was 97%; the degradation and removal rate of trichloroethylene by S-nZVI-400@ROR-5℃ / min-120 was 90%, and the electron efficiency was 97.5%. When the calcination time was 90 min and 120 min, although the electron efficiency was higher than that in Example 1 with a calcination time of 60 min, the removal effect on trichloroethylene was lower than that with a calcination time of 60 min. The reason was that too long a calcination time would result in too thick a layer of iron sulfide, reducing the relative proportion of zero-valent iron and thus affecting the reaction activity and causing a decrease in the removal rate.

[0071] Example 6

[0072] (1) Preparation of sulfidated nano-zero-valent iron material

[0073] 1 g of zero-valent iron powder (particle size 100 nm) was placed in the furnace tube of a tube furnace. An inert gas was introduced from one side of the tube furnace and exhausted from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, the gas was switched to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. The temperature was raised to 400 °C at a heating rate of 5 °C / min. After calcination for 60 min, it was cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0074] (2) Degradation and removal of organic pollutants in water

[0075] Using tetrachloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, followed by 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid equipped with a Teflon septum, and then 15 μL of tetrachloroethylene stock solution (17.9 mg / L) was injected using a syringe. The initial concentration of tetrachloroethylene was 10 mg / L. The concentration of tetrachloroethylene in the reagent bottle was monitored at regular intervals using gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of tetrachloroethylene was 92%, and the electron efficiency was 94.5%.

[0076] Example 7

[0077] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0078] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tube furnace. Pass an inert gas into one side of the tube furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0079] (2) Degradation and Removal of Organic Pollutants in Water

[0080] Using carbon tetrachloride as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfurized nano-zero-valent iron was 1 g / L. Tighten the lid with a Teflon septum, and then inject 15 μL of carbon tetrachloride working solution (17.9 mg / L) using a syringe. The initial concentration of carbon tetrachloride was 10 mg / L. The concentration of carbon tetrachloride in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of carbon tetrachloride was 100%, and the electron efficiency was 94.6%.

[0081] Example 8

[0082] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0083] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tube furnace. Pass an inert gas into one side of the tube furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0084] (2) Degradation and Removal of Organic Pollutants in Water

[0085] Using hexachlorobutadiene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano zero-valent iron was 1 g / L. It was tightly capped with a lid with a Teflon septum, and then 15 μL of hexachlorobutadiene stock solution (17.9 mg / L) was injected with a syringe. The initial concentration of hexachlorobutadiene was 10 mg / L. The concentration of hexachlorobutadiene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of hexachlorobutadiene was 94%, and the electron efficiency was 94.7%.

[0086] Example 9

[0087] (1) Preparation of sulfidated nano zero-valent iron material

[0088] 1 g of zero-valent iron powder (particle size 100 nm) was placed in the furnace tube of a tube furnace. An inert gas was introduced from one side of the tube furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, H2S gas (content 2%, balance 98% nitrogen) was switched, and the gas flow rate was 50 mL / min. It was heated to 400 °C at a heating rate of 5 °C / min, calcined for 60 min, and then cooled to room temperature to obtain the sulfidated nano zero-valent iron material.

[0089] (2) Degradation and removal of organic pollutants in water

[0090] Using 1,2,3-trichloropropane as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano zero-valent iron was 1 g / L. It was tightly capped with a lid with a Teflon septum, and then 15 μL of 1,2,3-trichloropropane stock solution (17.9 mg / L) was injected with a syringe. The initial concentration of 1,2,3-trichloropropane was 10 mg / L. The concentration of 1,2,3-trichloropropane in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of 1,2,3-trichloropropane was 90%, and the electron efficiency was 94%.

[0091] Example 10

[0092] (1) Preparation of sulfidated nano zero-valent iron material

[0093] Place 1 g of zero-valent iron powder (particle size 100 nm) in the furnace tube of a tube furnace. Pass an inert gas into one side of the tube furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen). The gas flow rate is 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min. After calcining for 60 min, cool it to room temperature to obtain the sulfurized nano zero-valent iron material.

[0094] (2) Degradation and removal of organic pollutants in water

[0095] Using cis-1,2-dichloroethylene as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfurized nano zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfurized nano zero-valent iron was 1 g / L. Tighten the lid with a Teflon septum, and then inject 15 μL of cis-1,2-dichloroethylene stock solution (17.9 mg / L) with a syringe. The initial concentration of cis-1,2-dichloroethylene was 10 mg / L. Use gas chromatography to regularly monitor the concentration of cis-1,2-dichloroethylene in the reagent bottle. The results showed that after reacting for 6 h, the degradation and removal rate of cis-1,2-dichloroethylene was 79%, and the electron efficiency was 93%.

[0096] Example 11

[0097] (1) Preparation of sulfurized nano zero-valent iron material

[0098] Place 1 g of zero-valent iron powder (particle size 100 nm) in the furnace tube of a tube furnace. Pass an inert gas into one side of the tube furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen). The gas flow rate is 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min. After calcining for 60 min, cool it to room temperature to obtain the sulfurized nano zero-valent iron material.

[0099] (2) Degradation and removal of organic pollutants in water

[0100] Using trans-1,2-dichloroethylene as the target pollutant, the activity of the above materials was investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid with a Teflon septum, and then 15 μL of a trans-1,2-dichloroethylene stock solution (17.9 mg / L) was injected with a syringe. The initial concentration of trans-1,2-dichloroethylene was 10 mg / L. The concentration of trans-1,2-dichloroethylene in the reagent bottle was monitored at regular intervals by gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of trans-1,2-dichloroethylene was 78%, and the electron efficiency was 90%.

[0101] Example 12

[0102] (1) Preparation of sulfidated nano-zero-valent iron material

[0103] 1 g of zero-valent iron powder (particle size 100 nm) was placed in the furnace tube of a tube furnace. An inert gas was introduced from one side of the tube furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, H2S gas (content 2%, balance 98% nitrogen) was switched in. The gas flow rate was 50 mL / min, and the temperature was raised to 400 °C at a heating rate of 5 °C / min. After calcination for 60 min, it was cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0104] (2) Degradation and removal of organic pollutants in water

[0105] Using vinyl chloride as the target pollutant, the activity of the above materials was investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid with a Teflon septum, and then 15 μL of a vinyl chloride stock solution (17.9 mg / L) was injected with a syringe. The initial concentration of vinyl chloride was 10 mg / L. The concentration of vinyl chloride in the reagent bottle was monitored at regular intervals by gas chromatography. The results showed that after 6 h of reaction, the degradation and removal rate of vinyl chloride was 76%, and the electron efficiency was 95%.

[0106] Example 13

[0107] (1) Preparation of sulfidated nano-zero-valent iron material

[0108] Place 1 g of zero-valent iron powder (particle size 100 nm) into the furnace tube of a tubular furnace. Pass an inert gas into one side of the tubular furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0109] (2) Degradation and removal of organic pollutants in water

[0110] Using chloroform as the target pollutant, investigate the activity of the above material. The specific implementation steps are as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfurized nano-zero-valent iron is 1 g / L. Seal it tightly with a lid with a Teflon septum, and then inject 15 μL of chloroform working solution (17.9 mg / L) using a syringe. The initial concentration of chloroform is 10 mg / L. Use gas chromatography to periodically monitor and track the concentration of chloroform in the reagent bottle. The results show that after 6 h of reaction, the degradation and removal rate of chloroform is 100%, and the electron efficiency is 94%.

[0111] Example 14

[0112] (1) Preparation of sulfurized nano-zero-valent iron material

[0113] Place 1 g of zero-valent iron powder (particle size 100 nm) into the furnace tube of a tubular furnace. Pass an inert gas into one side of the tubular furnace and discharge the inert gas from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0114] (2) Degradation and removal of organic pollutants in water

[0115] Using dichloromethane as the target pollutant, investigate the activity of the above material. The specific implementation steps are as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfurized nano-zero-valent iron is 1 g / L. Seal it tightly with a lid with a Teflon septum, and then inject 15 μL of dichloromethane working solution (17.9 mg / L) using a syringe. The initial concentration of trichloroethane is 10 mg / L. Use gas chromatography to periodically monitor and track the concentration of dichloromethane in the reagent bottle. The results show that after 6 h of reaction, the degradation and removal rate of dichloromethane is 99%, and the electron efficiency is 93.9%.

[0116] Example 15

[0117] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0118] Take 1 g of zero-valent iron powder (particle size 100 nm) and place it in the furnace tube of a tubular furnace. Inert gas is introduced from one side of the tubular furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0119] (2) Degradation and Removal of Organic Pollutants in Water

[0120] Using tetrachloroethane as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfurized nano-zero-valent iron was 1 g / L. Tighten the lid with a Teflon septum, and then inject 15 μL of dichloromethane working solution (17.9 mg / L) with a syringe. The initial concentration of tetrachloroethane was 10 mg / L. The concentration of tetrachloroethane in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of tetrachloroethane was 90%, and the electron efficiency was 94%.

[0121] Example 16

[0122] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0123] Take 1 g of zero-valent iron powder with particle sizes of 20 nm, 50 nm, 200 nm, and 500 nm respectively and place them in the furnace tube of a tubular furnace. Inert gas is introduced from one side of the tubular furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. Heat it to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0124] (2) Degradation and Removal of Organic Pollutants in Water

[0125] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, followed by 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h). The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid equipped with a Teflon septum, and then 15 μL of trichloroethylene stock solution (17.9 mg / L) was injected using a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored at regular intervals using gas chromatography. The results showed that after 6 h of reaction, when the particle size was 20 nm, the degradation and removal rate of trichloroethylene was 85%, and the electron efficiency was 97%; when the particle size was 50 nm, the degradation and removal rate of trichloroethylene was 87%, and the electron efficiency was 97%; when the particle size was 200 nm, the degradation and removal rate of trichloroethylene was 92%, and the electron efficiency was 92%; when the particle size was 500 nm, the degradation and removal rate of trichloroethylene was 90%, and the electron efficiency was 90.3%. Compared with Example 1, although the electron efficiency was the same as that at a particle size of 100 nm when the particle sizes were 20 nm and 50 nm, the degradation and removal rates of trichloroethylene were lower than those at a particle size of 100 nm.

[0126] Comparative Example 1

[0127] (1) Preparation of sulfidated nano-zero-valent iron material

[0128] 1 g of zero-valent iron powder (particle size 100 nm) was placed in the furnace tube of a tubular furnace. An inert gas was introduced from one side of the tubular furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, the gas was switched to H2S gas (content 2%, balance 98% nitrogen), with a gas flow rate of 50 mL / min. The temperature was raised to 600 °C at a heating rate of 5 °C / min and calcined for 60 min, and then cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0129] (2) Degradation and removal of organic pollutants in water

[0130] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid with a Teflon septum, and then 15 μL of trichloroethylene working solution (17.9 mg / L) was injected using a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene was 60%, and the electron efficiency was 95%. Compared with Example 1, the degradation and removal rate of trichloroethylene was not good. The reason was that when the calcination temperature was higher than 500 °C, the reaction between H2S and Fe was too intense, resulting in excessive sulfidation, too low content of residual zero-valent iron in the particles, and thus affecting the degradation and removal rate of trichloroethylene.

[0131] Comparative Example 2

[0132] (1) Preparation of sulfidated nano-zero-valent iron material

[0133] 1 g (particle size 100 nm) of zero-valent iron powder was placed in the furnace tube of a tube furnace. An inert gas was introduced from one side of the tube furnace and discharged from the other side. After the oxygen content in the furnace tube was lower than 100 ppm, H2S gas (content 2%, balance 98% nitrogen) was switched in. The gas flow rate was 50 mL / min, and the temperature was raised to 300 °C at a heating rate of 5 °C / min. After calcination for 60 min, it was cooled to room temperature to obtain the sulfidated nano-zero-valent iron material.

[0134] (2) Degradation and removal of organic pollutants in water

[0135] Using trichloroethylene as the target pollutant, the activities of the above materials were investigated. The specific implementation steps were as follows: 0.026 g of sulfidated nano-zero-valent iron was added to a 50 mL reagent bottle, and 26 mL of anaerobic water (deionized water purged with nitrogen for 1 h) was added. The mass concentration of sulfidated nano-zero-valent iron was 1 g / L. The bottle was tightly capped with a lid with a Teflon septum, and then 15 μL of trichloroethylene working solution (17.9 mg / L) was injected using a syringe. The initial concentration of trichloroethylene was 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that after 6 h of reaction, the degradation and removal rate of trichloroethylene was 30%, and the electron efficiency was 5%. Compared with Example 1, the degradation and removal rate of trichloroethylene was not good. The reason was that when the calcination temperature was lower than 400 °C, the reaction between H2S and Fe was difficult, resulting in insufficient sulfidation and not enough to form an iron sulfide layer on the particle surface, and thus affecting the degradation and removal rate of trichloroethylene.

[0136] Comparative Example 3

[0137] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0138] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tube furnace. An inert gas is introduced from one side of the tube furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance gas is 98% nitrogen), the gas flow rate is 50 mL / min, heat up to 400 °C at a heating rate of 5 °C / min, calcine for 180 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0139] (2) Degradation and Removal of Organic Pollutants in Water

[0140] Using trichloroethylene as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water blown with nitrogen for 1 h), the mass concentration of sulfurized nano-zero-valent iron is 1 g / L, tighten the lid with a Teflon septum, and then inject 15 μL of trichloroethylene stock solution (17.9 mg / L) with a syringe. The initial concentration of trichloroethylene is 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that: after reacting for 6 h, the degradation and removal rate of trichloroethylene was 45%, and the electron efficiency was 97%. Compared with Example 1, the degradation and removal rate of trichloroethylene was not good. The reason was that when the calcination time was higher than 120 min, the reaction time of H2S and Fe was too long, resulting in too high a degree of sulfidation, excessive consumption of zero-valent iron in the particles, and too low content of remaining zero-valent iron in the particles, thus affecting the degradation and removal rate of trichloroethylene.

[0141] Comparative Example 4

[0142] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0143] Take 1 g (particle size 100 nm) of zero-valent iron powder and place it in the furnace tube of a tube furnace. An inert gas is introduced from one side of the tube furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 2%, balance gas is 98% nitrogen), the gas flow rate is 50 mL / min, heat up to 400 °C at a heating rate of 5 °C / min, calcine for 30 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0144] (2) Degradation and Removal of Organic Pollutants in Water

[0145] The activity of the above materials was investigated with trichloroethylene as the target pollutant. The specific implementation steps are as follows: 0.026g of sulfide nano zero-valent iron was added to a 50mL reagent bottle, 26mL of oxygen-free water (deionized water was stripped by nitrogen for 1h), the mass concentration of sulfide nano zero-valent iron was 1g / L, and the bottle was tightly covered with a lid with a Teflon septum, and then 15μL of trichloroethylene solution (17.9mg / L) was injected with a needle syringe, the initial concentration of trichloroethylene was 10mg / L, and the concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography. The results showed that after 6h of reaction, the degradation removal rate of trichloroethylene was 35%, and the electronic efficiency was 6%. Compared with Example 1, the degradation removal rate of trichloroethylene was not good. The reason was that when the calcination time was less than 60min, H2S and Fe would not react sufficiently, and no iron sulfide layer was formed on the surface of the particles, thereby affecting the degradation removal rate of trichloroethylene.

[0146] Comparative Example 5

[0147] (1) Preparation of sulfide nano zero-valent iron materials

[0148] Take 1g (particle size 100nm) of zero-valent iron powder and place it in the furnace tube of a tubular furnace. Inert gas is introduced into one side of the tubular furnace and then discharged from the other side. After the oxygen content in the furnace tube is lower than 100ppm, switch to H2S gas (content 6%, the rest is 94% nitrogen) with a gas flow rate of 50mL / min. Heat to 400℃ at a heating rate of 5℃ / min. After calcination for 60min, cool to room temperature to obtain sulfide nano zero-valent iron material.

[0149] (2) Degradation and removal of organic pollutants in water

[0150] The activity of the above materials was investigated with trichloroethylene as the target pollutant. The specific implementation steps are as follows: 0.026g of sulfide nano zero-valent iron was added to a 50mL reagent bottle, 26mL of oxygen-free water (deionized water was stripped by nitrogen for 1h), the mass concentration of sulfide nano zero-valent iron was 1g / L, and the bottle was tightly covered with a lid with a Teflon septum, and then 15μL of trichloroethylene solution (17.9mg / L) was injected with a needle syringe, the initial concentration of trichloroethylene was 10mg / L, and the concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography. The results showed that after 6h of reaction, the degradation removal rate of trichloroethylene was 56%, and the electronic efficiency was 98%. Compared with Example 1, the degradation removal rate of trichloroethylene was not good. The reason was that when the H2S gas content was higher than 5%, the reaction between H2S and Fe was too intense, resulting in too high a degree of sulfidation, excessive consumption of zero-valent iron in the particles, and too low a remaining zero-valent iron content in the particles, which in turn affected the degradation removal rate of trichloroethylene.

[0151] Comparative Example 6

[0152] (1) Preparation of Sulfurized Nano-Zero-Valent Iron Material

[0153] Take 1 g of zero-valent iron powder (particle size 100 nm) and place it in the furnace tube of a tubular furnace. Inert gas is introduced from one side of the tubular furnace and discharged from the other side. After the oxygen content in the furnace tube is lower than 100 ppm, switch to H2S gas (content 0.2%, balance gas is 99.8% nitrogen), the gas flow rate is 50 mL / min, heat it up to 400 °C at a heating rate of 5 °C / min, calcine for 60 min, and then cool to room temperature to obtain the sulfurized nano-zero-valent iron material.

[0154] (2) Degradation and Removal of Organic Pollutants in Water

[0155] Using trichloroethylene as the target pollutant, the activity of the above material was investigated. The specific implementation steps were as follows: Add 0.026 g of sulfurized nano-zero-valent iron to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water blown with nitrogen for 1 h), the mass concentration of sulfurized nano-zero-valent iron is 1 g / L, cover it tightly with a lid with a Teflon septum, and then inject 15 μL of trichloroethylene stock solution (17.9 mg / L) with a syringe. The initial concentration of trichloroethylene is 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that: after reacting for 6 h, the degradation and removal rate of trichloroethylene was 65%, and the electron efficiency was 56%. Compared with Example 1, the degradation and removal rate of trichloroethylene was not good. The reason was that when the content of H2S gas was lower than 0.2%, the reaction between H2S and Fe was insufficient, resulting in the failure to form a layer of iron sulfide on the particle surface, thereby affecting the degradation and removal rate of trichloroethylene.

[0156] Comparative Example 7

[0157] The experiment was carried out by using unsulfurized zero-valent iron material to replace the sulfurized nano-zero-valent iron in Example 1. Using trichloroethylene as the target pollutant, the activity of the above material was investigated.

[0158] The specific implementation steps were as follows: Add 0.026 g of zero-valent iron material to a 50 mL reagent bottle, add 26 mL of anaerobic water (deionized water blown with nitrogen for 1 h), cover it tightly with a lid with a Teflon septum, and then inject 15 μL of trichloroethylene stock solution (17.9 mg / L) with a syringe. The initial concentration of trichloroethylene is 10 mg / L. The concentration of trichloroethylene in the reagent bottle was monitored by gas chromatography at regular intervals. The results showed that: after reacting for 6 h, the degradation and removal rate of trichloroethylene was only 12%, and the electron efficiency was 3%. Compared with Example 1, the degradation and removal rate of trichloroethylene was not good. The reason was that when the zero-valent iron material was not sulfurized, there was no iron sulfide layer on its particle surface, thereby affecting the degradation and removal rate of trichloroethylene.

Claims

1. A sulfurized nano zero-valent iron material, which is a core-shell structure, is characterized in that, The core of the sulfurized nano zero-valent iron material is zero-valent iron, and the shell is Fe9S 10 ; calculated by the mass of the sulfurized nano zero-valent iron, the mass percentage of the zero-valent iron is 70-80%, and the mass percentage of the Fe9S 10 is 20-30%; The preparation method of the sulfided nano zero-valent iron material comprises: calcining iron powder in an H2S gas atmosphere, and after the calcination is completed, cooling to room temperature to obtain the sulfided nano zero-valent iron material.

2. The sulfurized nano zero-valent iron material according to claim 1, wherein The iron powder is zero-valent iron powder or iron filings, and its particle size is 20 nm to 500 nm.

3. The sulfurized nano zero-valent iron material according to claim 1, characterized in that, The volume concentration of the H2S gas is 0.5% to 5%, and the gas flow rate is 10 to 100 mL / min.

4. The sulfurized nano zero-valent iron material according to claim 1, characterized in that, The iron powder is first placed in an inert gas atmosphere, and then the inert gas is replaced with H2S gas; the inert gas includes one of nitrogen, argon or helium.

5. The sulfurized nano zero-valent iron material according to claim 1, wherein The temperature of the calcination is 400 to 500 °C, and the heating rate is 3 to 10 °C / min; the calcination time is 60 to 120 min.

6. The application of the sulfided nano zero-valent iron material according to any one of claims 1 to 5 in in-situ remediation of groundwater containing chlorinated hydrocarbon organic pollutants.

7. The application according to claim 6, characterized in that, The chlorinated hydrocarbon organic pollutants are one or more of vinyl chloride, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, dichloromethane, tetrachloroethane, chloroform, carbon tetrachloride, hexachlorobutadiene, and trichloropropane.

8. The application according to claim 6, wherein It includes: Adding the sulfided nano zero-valent iron material to the groundwater containing chlorinated hydrocarbon organic pollutants to remove the chlorinated hydrocarbon organic pollutants in the groundwater.

Images