Vulcanized nano zero-valent iron as well as preparation method and application thereof

Abstract

The invention relates to the technical field of nano materials, and discloses vulcanized nano zero-valent iron as well as a preparation method and application thereof. The method comprises the following steps: (1) mixing iron-containing metal salt with polyol to obtain a mixture A; wherein relative to 1kg of the metal salt, the dosage of the polyhydric alcohol is 1-50L; (2) mixing a reducing agent and a vulcanizing agent to obtain a mixture B; and (3) adding the mixture A and the mixture B into a supergravity machine, and reacting under a supergravity condition. The vulcanized nano zero-valent iron material prepared by the method disclosed by the invention is high in reaction activity, good in stability and uniform in particle size distribution, and can be used for degrading different types of chlorine-containing organic pollutants in underground water, and the degradation rate is greater than 90%; the remediation requirements of underground water polluted by organic chlorine-containing compounds around petroleum and petrochemical enterprises or waste land parcels can be met.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically to a sulfide nano-zero valent iron, its preparation method, and its application. Background Technology

[0002] Nano-zero valent iron (nZVI) particles are magnetic and tend to aggregate, leading to increased particle size. They are also easily oxidized in air, forming an inert layer that hinders efficient electron transfer and significantly reduces the reactivity of zero-valent iron. In recent years, a novel composite material—sulfide nano-zero valent iron—composed of Fe(O) cores and FeS shells or interspersed with sheet-like FeS within nZVI, has attracted increasing attention due to its faster degradation efficiency and good antioxidant capacity for trichloroethylene (TCE). A new material combining ferrous sulfide and nano-zero valent iron can simultaneously exhibit the strong reducing power of zero-valent iron and the conductivity and stability of ferrous sulfide, thus accelerating the reaction rate. Existing technology first prepares nano-zero valent iron particles by reacting ferrous salts and sodium borohydride, then coats the nano-zero valent iron particles with elemental sulfur powder as a sulfur source to prepare elemental sulfur-coated nano-zero valent iron particles, which are then used for the degradation of tetrabromobisphenol A in water. This technology prepares sulfide nano-zero-valent iron in a two-step process, which is relatively complex. In the first step, the nano-zero-valent iron particles are prone to aggregation and oxidation, leading to decreased activity. Furthermore, the final product is elemental sulfur-coated nano-zero-valent iron, rather than ferrous sulfide-coated nano-zero-valent iron, which is more readily electron-transferring. Additionally, this technology involves adding a sodium borohydride reducing agent solution dropwise to a ferrous salt solution while simultaneously mixing the two reactants with stirring. This dropwise addition process can result in locally high concentrations of the reducing agent in the ferrous salt solution. Since the reduction of ferric ions by borohydride to form zero-valent metallic iron is a rapid precipitation reaction, while traditional stirring and mixing methods have low molecular-scale transport and mixing rates, the time required for microscopic mixing of the reactants is much longer than the nucleation time of liquid-phase reduction precipitation. This results in a non-uniform environment at the molecular scale during the nucleation and growth of zero-valent iron crystals, leading to larger and unevenly distributed zero-valent iron particles.

[0003] Therefore, it is necessary to improve the existing methods for preparing sulfide nano-zero valent iron and develop a simple, easily scalable, economically feasible method for preparing sulfide nano-zero valent iron with high degradation activity, so that the prepared sulfide nano-zero valent iron particles have both small particle size and large specific surface area, as well as good stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of uneven particle size distribution, poor material stability, and low degradation activity in the existing technology for preparing sulfide nano-zero valent iron, and to provide a method for preparing sulfide nano-zero valent iron.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing sulfide nano-zero valent iron, the method comprising:

[0006] (1) Mixing an iron-containing metal salt with a polyol yields a mixture A; wherein, relative to 1 kg of metal salt, the amount of the polyol used is 1-50 L;

[0007] (2) Mixture B is obtained by mixing the reducing agent and the vulcanizing agent;

[0008] (3) Add mixture A and mixture B into the hypergravity machine to allow them to react under hypergravity conditions.

[0009] A second aspect of the present invention provides a sulfide nano-zero valent iron, wherein the sulfide nano-zero valent iron is the sulfide nano-zero valent iron prepared by the above method;

[0010] Alternatively, the average particle size of the sulfide nano-zero valent iron is 1-20 nm, the proportion of particles with a particle size range of 1-10 nm in the total number of particles is ≥95%, and the specific surface area is ≥100 m². 2 / g.

[0011] A third aspect of the present invention provides sulfide nano-zero valent iron prepared by the above method or the application of the above sulfide nano-zero valent iron in degrading polluted groundwater.

[0012] A fourth aspect of the present invention provides a method for degrading polluted groundwater, the method comprising: adding the above-mentioned sulfide nano-zero valent iron to the polluted groundwater;

[0013] The amount of sulfide nano-zero valent iron added to the polluted groundwater is 0.1-5 g / L.

[0014] The above technical solution can achieve at least the following beneficial effects:

[0015] (1) The sulfide nano-zero valent iron material prepared by the method of the present invention has high reactivity, good stability and uniform particle size distribution.

[0016] (2) The sulfide nano-zero-valent iron prepared by the method of the present invention degrades different types of chlorine-containing organic pollutants in groundwater with a degradation rate of more than 90%, which can meet the remediation requirements of groundwater contaminated by organic chlorine compounds around oil and petrochemical enterprises or abandoned sites.

[0017] (3) The method provided by the present invention can prepare sulfide nano-zero valent iron materials in only one step, which has the advantages of being simple, fast, easy to scale up and low cost. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] The first aspect of this invention provides a method for preparing sulfide nano-zero valent iron, the method comprising:

[0020] (1) Mixing an iron-containing metal salt with a polyol yields a mixture A; wherein, relative to 1 kg of metal salt, the amount of the polyol used is 1-50 L;

[0021] (2) Mixture B is obtained by mixing the reducing agent and the vulcanizing agent;

[0022] (3) Add mixture A and mixture B into the hypergravity machine to allow them to react under hypergravity conditions.

[0023] In this invention, preferably, in step (1), the amount of the polyol used relative to 1 kg of metal salt is 2-20 L (for example, it can be any two values ​​from 2 L, 3 L, 4 L, 5 L, 6 L, 7 L, 8 L, 9 L, 10 L, 11 L, 12 L, 13 L, 14 L, 15 L, 16 L, 17 L, 18 L, 19 L, 20 L to form a range and the value within the range).

[0024] In this invention, preferably, in step (1), the metal salt can be an iron salt or a mixture of iron salt and other metal salts, more preferably a mixture of iron salt and other metal salts.

[0025] In this invention, preferably, the iron salt is selected from at least one of ferrous sulfate, ferrous chloride, ferrous nitrate, ferric sulfate, ferric chloride, and ferric nitrate; the other metal salt is selected from at least one of sulfates, nitrates, and chlorides of nickel, copper, manganese, cobalt, and zirconium.

[0026] In this invention, preferably, in the mixture of iron salt and other metal salts, the mass ratio of iron salt (calculated as iron element) to other metal salts (calculated as other metal elements) is 1:0.01-0.2, more preferably 1:0.05-0.1 (for example, it can be any two ratios from 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.1 forming a range and ratios within the range).

[0027] In this invention, preferably, in step (1), the polyol may be selected from C2-C8 diols and / or C3-C8 triols.

[0028] In this invention, more preferably, the diol may be selected from at least one of ethylene glycol, 1,2-propanediol, 1,3-propanediol and 1,4-butanediol.

[0029] In this invention, more preferably, the triol is selected from at least one of glycerol, butylene glycerol, and 1,2,5-pentanetriol.

[0030] In this invention, preferably, the mixing in step (1) can be a mixing method commonly used in the art, such as mechanical stirring. The mechanical stirring rate can be 100-500 rpm (for example, it can be any two values ​​formed by 100 rpm, 120 rpm, 150 rpm, 180 rpm, 200 rpm, 220 rpm, 250 rpm, 280 rpm, 300 rpm, 330 rpm, 350 rpm, 370 rpm, 400 rpm, 430 rpm, 450 rpm, 480 rpm, 500 rpm, forming a range and values ​​within the range), and the mechanical stirring time can be 10-150 min (for example, it can be any two values ​​formed by 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, forming a range and values ​​within the range).

[0031] In this invention, the reducing agent can be a substance commonly used in the art that can reduce iron. Preferably, in step (2), the reducing agent can be a borohydride, more preferably at least one of sodium borohydride, potassium borohydride, lithium borohydride, calcium borohydride and magnesium borohydride.

[0032] In this invention, the sulfiding agent can be a substance commonly used in the art that can sulfidize metallic iron atoms into ferrous sulfide. Preferably, in step (2), the sulfiding agent can be a metal sulfide and / or dithionite, more preferably at least one of sodium sulfide, potassium sulfide, sodium dithionite and potassium dithionite.

[0033] In this invention, preferably, the mixture B further includes water; preferably, the amount of water used is 1-50L relative to 1kg of metal salt.

[0034] It is understood that the amount of water used in step (2) can be maintained at a 1:1 ratio with the amount of polyol used in step (1).

[0035] In this invention, preferably, the molar ratio of the metal salt, the reducing agent and the sulfiding agent (calculated as iron) is 1:1-5:0.02-0.2, more preferably 1:1.5-3:0.03-0.1.

[0036] In this invention, preferably, in step (3), the hypergravity conditions include: a rotational speed of 400-4000 rpm, preferably 2000-3000 rpm (for example, it can be any two values ​​from 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm, 2800 rpm, 2900 rpm, 3000 rpm, and the range thereof); a temperature of 20-25℃ (for example, it can be any two values ​​from 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, and the range thereof); and a time of 0.1-2h, preferably 0.5-1h (for example, it can be any two values ​​from 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, and the range thereof).

[0037] In this invention, preferably, the filler in the supergravity machine is selected from at least one of wire mesh, porous corrugated plate, plastic porous plate and disc.

[0038] In this invention, preferably, the ratio of the rates at which the mixture A and the mixture B are added to the hypergravity machine is 1:0.5-1.5, more preferably 1:0.8-1.2 (for example, it can be any two ratios from 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, forming a range or ratio within that range).

[0039] In this invention, preferably, the feed rate of mixture A or mixture B is controlled to be 100-1000 mL / min relative to 10 L of mixture A or mixture B, more preferably 200-600 mL / min (for example, it can be any two values ​​formed by 200 mL / min, 250 mL / min, 300 mL / min, 350 mL / min, 400 mL / min, 450 mL / min, 500 mL / min, 550 mL / min, 600 mL / min, and values ​​within the range).

[0040] In this invention, preferably, the method further includes: performing solid-liquid separation on the product after the reaction is completed, and washing and drying the solid product.

[0041] In this invention, preferably, the solid-liquid separation can be carried out using a solid-liquid separation method commonly used in the art, such as magnetic separation, centrifugal separation, or natural sedimentation.

[0042] In this invention, preferably, the detergent can be deionized water and / or anhydrous ethanol.

[0043] A second aspect of the present invention provides a sulfide nano-zero valent iron, wherein the sulfide nano-zero valent iron is the sulfide nano-zero valent iron prepared by the above method;

[0044] Alternatively, the average particle size of the sulfide nano-zero valent iron is 1-20 nm, the proportion of particles with a particle size range of 1-10 nm in the total number of particles is ≥95%, and the specific surface area is ≥100 m². 2 / g.

[0045] In this invention, preferably, the average particle size of the sulfide nano-zero valent iron is 1.5-10 nm (for example, it can be any two values ​​formed by 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 5.5 nm, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, and 10 nm, or values ​​within that range), and the specific surface area is 110-220 m² / g. 2 / g (for example, it can be 110m) 2 / g、120m 2 / g、130m 2 / g, 140m 2 / g, 150m 2 / g、160m 2 / g、170m 2 / g、180m 2 / g、190m 2 / g、200m 2 / g、210m 2 / g、220m 2 (The range formed by any two values ​​in / g and the values ​​within that range).

[0046] A third aspect of the present invention provides sulfide nano-zero valent iron prepared by the above method or the application of the above sulfide nano-zero valent iron in degrading polluted groundwater.

[0047] A fourth aspect of the present invention provides a method for degrading polluted groundwater, the method comprising: adding the above-mentioned sulfide nano-zero valent iron to the polluted groundwater;

[0048] The amount of sulfide nano-zero valent iron added to the polluted groundwater is 0.1-5 g / L.

[0049] In this invention, preferably, the contaminated groundwater may include at least one of the following: carbon tetrachloride (CT), trichloroethylene (TCE), tetrachloroethylene (PCE), hexachloroethane (HCA), polychlorinated biphenyls, chlorophenol, polybrominated diphenyl ethers, and organochlorine pesticides.

[0050] In this invention, the organochlorine pesticide can be a chlorinated organic compound commonly used as a pesticide in the art. Preferably, the organochlorine pesticide may include at least one of the following: hexachlorobenzene, hexachlorocyclohexane, heptachlor, aldrin, chlordane oxide, heptachlor epoxide, chlordane, 2,4'-DDE, 4,4'-DDE, nonachlor, endosulfan, dieldrin, isodrin, 2,4'-DDT, 4,4'-DDT, and methyl parathion.

[0051] In this invention, preferably, the content of pollutants in the polluted groundwater is greater than the Class III groundwater quality indicators and limits specified in GB / T14848-2017.

[0052] In this invention, preferably, the method does not include adjusting the pH value.

[0053] In this invention, preferably, the polluted groundwater is groundwater in which at least one organic pollutant fails to meet the Class III groundwater quality indicators and limits specified in GB / T 14848-2017.

[0054] The present invention will be described in detail below through embodiments. In the following embodiments,

[0055] Degradation rate = (C0 - C) t ) / C0×100, where C0 is the initial pollutant concentration in the polluted groundwater, C t The concentration of pollutants in groundwater after degradation time t.

[0056] Example 1

[0057] (1) Mix 500g FeSO4·7H2O and 22.49g NiSO4·6H2O (mass ratio of FeSO4·7H2O to NiSO4·6H2O) 2+ :Ni 2+ =1:0.05) was added to 10L of ethylene glycol and mechanically stirred for 60min (stirring speed of 200rpm) to obtain mixed solution A;

[0058] (2) According to the molar ratio Fe 2+ :BH4 - :S 2- The ratios of NaBH4 and Na2S·9H2O (1:2:0.033) were added to 10 L of deionized water and dissolved to obtain mixed solution B.

[0059] (3) Turn on the centrifuge, adjust the temperature to 20℃, and the speed to 2500rpm until it is stable. Then, add the two mixed solutions A and B to the centrifuge at the same time at a feed rate of 300mL / min. After the feed is finished, continue the reaction for 0.5h. After the reaction is finished, discharge the material from the outlet of the centrifuge.

[0060] (4) The reaction products discharged from the outlet of the centrifuge were separated by magnetic separation. The reaction products were washed three times with deionized water and anhydrous ethanol, respectively. After vacuum drying, sulfide nano-zero valent iron was obtained. The particle size distribution and specific surface area are shown in Table 1.

[0061] Example 2

[0062] (1) Mix 500g FeSO4·7H2O and 42.9g NiSO4·6H2O (mass ratio of Fe... 2+ :Ni 2+ =1:0.1) was added to 10 L of 1,2-propanediol and mechanically stirred for 60 min (stirring speed of 200 rpm) to obtain mixed solution A;

[0063] (2) According to the molar ratio Fe 2+ :BH4 - :S 2- A mixture of NaBH4 and Na2S·9H2O in a ratio of 1:1.5:0.05 was dissolved in 10 L of deionized water to obtain mixed solution B.

[0064] (3) Turn on the centrifuge, adjust the temperature to 25℃, and the speed to 2000rpm until it is stable. Then, add the two mixed solutions A and B to the centrifuge at the same time at a feed rate of 600mL / min. After the feed is finished, continue the reaction for 0.5h. After the reaction is finished, discharge the material from the outlet of the centrifuge.

[0065] (4) The reaction products discharged from the outlet of the centrifuge were separated by magnetic separation. The reaction products were washed three times with deionized water and anhydrous ethanol, respectively. After vacuum drying, sulfide nano-zero valent iron was obtained. The particle size distribution and specific surface area are shown in Table 1.

[0066] Example 3

[0067] (1) Mix 500g FeCl3·6H2O and 46.14g Mn(NO3)2·6H2O (mass ratio of FeCl3·6H2O) 3+ :Mn 2+ =1:0.07) was added to 10L of glycerol and mechanically stirred for 60min (stirring speed 200rpm) to obtain mixed solution A;

[0068] (2) According to the molar ratio Fe 3+ :BH4 -:S 2- KBH4 and K2S in a ratio of 1:3:0.1 were dissolved in 10 L of deionized water to obtain mixed solution B;

[0069] (3) Turn on the centrifuge, adjust the temperature to 22℃, and the speed to 3000rpm until it is stable. Then, add the two mixed solutions A and B to the centrifuge at the same time at a feed rate of 200mL / min. After the feed is finished, continue the reaction for 0.5h. After the reaction is finished, discharge the material from the outlet of the centrifuge.

[0070] (4) The reaction products discharged from the outlet of the centrifuge were separated by magnetic separation. The reaction products were washed three times with deionized water and anhydrous ethanol, respectively. After vacuum drying, sulfide nano-zero valent iron was obtained. The particle size distribution and specific surface area are shown in Table 1.

[0071] Example 4

[0072] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that Mn(NO3)2·6H2O was not added. The particle size distribution and specific surface area are shown in Table 1.

[0073] Example 5

[0074] Sulfide nano-zero valent iron was prepared according to the method of Example 3, except that in step (1), Fe... 3+ With Mn 2+ The mass ratio was 1:0.2. The particle size distribution and specific surface area are shown in Table 1.

[0075] Example 6

[0076] Sulfide nano-zero valent iron was prepared according to the method in Example 3, except that in step (1), Mn(NO3)2·6H2O was replaced with Zn(SO4)2·7H2O, so that Fe 3+ With Zn 2+ The mass ratio remains at 1:0.07. The particle size distribution and specific surface area are shown in Table 1.

[0077] Example 7

[0078] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that the molar ratio of Fe was [not specified]. 3+ :BH4 - :S 2- = 1:2:0.02. Particle size distribution and specific surface area are shown in Table 1.

[0079] Example 8

[0080] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that the molar ratio of Fe was [not specified]. 3+ :BH4 -:S 2- = 1:2:0.2. Particle size distribution and specific surface area are shown in Table 1.

[0081] Example 9

[0082] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that mixed solution A was simultaneously added to the centrifuge at a feed rate of 200 mL / min and mixed solution B at a feed rate of 100 mL / min. The particle size distribution and specific surface area are shown in Table 1.

[0083] Example 10

[0084] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that the rotation speed of the centrifuge was 4000 rpm. The particle size distribution and specific surface area are shown in Table 1.

[0085] Example 11

[0086] Sulfide nano-zero-valent iron was prepared according to the method in Example 3, except that 60 L of glycerol was added. The particle size distribution and specific surface area are shown in Table 2.

[0087] Comparative Example 1

[0088] (1) Dissolve 500g FeSO4·7H2O in 10L of deionized water to obtain mixed solution A;

[0089] (2) The molar ratio of Fe 2+ :BH4 - :S 2- The ratios of NaBH4 and Na2S·9H2O (1:2:0.033) were added to 10 L of deionized water and dissolved to obtain mixed solution B.

[0090] (3) Add mixed solution B dropwise to mixed solution A under mechanical stirring (stirring speed of 200 rpm);

[0091] (4) The reaction products were separated by magnetic separation, and washed three times with deionized water and anhydrous ethanol, respectively. After vacuum drying, sulfide nano-zero valent iron was obtained. The particle size distribution and specific surface area are shown in Table 2.

[0092] Comparative Example 2

[0093] Sulfide nano-zero valent iron was prepared according to the method in Example 3, except that in step (1), glycerol was replaced with deionized water. The particle size distribution and specific surface area are shown in Table 2.

[0094] Comparative Example 3

[0095] Sulfide nano-zero valent iron was prepared according to the method in Example 3, except that in step (3), a centrifugal reactor was not used for the reaction. Instead, mixed solution B was added dropwise to mixed solution A under mechanical stirring (stirring speed of 200 rpm) for 0.5 h. After the addition was completed, the reaction continued for another 0.5 h. The particle size distribution and specific surface area are shown in Table 2.

[0096] Table 1

[0097]

[0098]

[0099] Table 2

[0100]

[0101] The particle size ranges in Tables 1 and 2 do not include the right end point.

[0102] Test Example 1

[0103] The products obtained from the examples and comparative examples were added to contaminated groundwater at a concentration of 1 g / L, where the tetrachloroethylene content in the contaminated groundwater was 20,000 μg / L. The degradation rate of tetrachloroethylene in the contaminated groundwater after a certain period is shown in Tables 3 and 4.

[0104] Table 3

[0105]

[0106]

[0107] Table 4

[0108]

[0109] Test Example 2

[0110] The products obtained from the examples and comparative examples were added to contaminated groundwater at a concentration of 1 g / L, where the trichloroethylene content in the contaminated groundwater was 20,000 μg / L. The degradation rate of trichloroethylene in the contaminated groundwater after a certain period is shown in Tables 5 and 6.

[0111] Table 5

[0112]

[0113]

[0114] Table 6

[0115]

[0116] Test Example 3

[0117] The products obtained in the examples and comparative examples were dried and placed in air for one month before being added to contaminated groundwater. The concentration of the product in the water was 1 g / L, while the tetrachloroethylene content in the contaminated groundwater was 20,000 μg / L. The degradation rate of tetrachloroethylene in the contaminated groundwater after a certain period of degradation is shown in Table 7.

[0118] Table 7

[0119]

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing nano-zero-valent iron sulfide, characterized in that, The method includes: (1) Mixing an iron-containing metal salt with a polyol yields a mixture A; wherein, relative to 1 kg of metal salt, the amount of the polyol used is 1-50 L; (2) Mixture B is obtained by mixing the reducing agent and the vulcanizing agent; (3) Add mixture A and mixture B into the hypergravity machine to allow them to react under hypergravity conditions.

2. The method according to claim 1, wherein, In step (1), the amount of the polyol used is 2-20L relative to 1kg of metal salt; And / or, the metal salt is an iron salt or a mixture of iron salt and other metal salts, preferably a mixture of iron salt and other metal salts; Preferably, the iron salt is selected from at least one of ferrous sulfate, ferrous chloride, ferrous nitrate, ferric sulfate, ferric chloride, and ferric nitrate; Preferably, the other metal salt is selected from at least one of the sulfates, nitrates and chlorides of nickel, copper, manganese, cobalt and zirconium; Preferably, in the mixture of iron salt and other metal salts, the mass ratio of iron salt (calculated as iron element) to other metal salts (calculated as other metal elements) is 1:0.01-0.2, more preferably 1:0.05-0.

1.

3. The method according to claim 1 or 2, wherein, In step (1), the polyol is selected from C2-C8 diols and / or C3-C8 triols; Preferably, the diol is selected from at least one of ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol; Preferably, the triol is selected from at least one of glycerol, butylene glycerol, and 1,2,5-pentanetriol; And / or, the mixing time in step (1) is 10-150 min.

4. The method according to claim 1, wherein, In step (2), the reducing agent is a borohydride, preferably at least one of sodium borohydride, potassium borohydride, lithium borohydride, calcium borohydride and magnesium borohydride; And / or, the sulfiding agent is a metal sulfide and / or a dithionite, preferably at least one of sodium sulfide, potassium sulfide, sodium dithionite and potassium dithionite; And / or, the mixture B also includes water; Preferably, the amount of water used is 1-50L relative to 1kg of metal salt.

5. The method according to any one of claims 1, 2, and 4, wherein, The molar ratio of the metal salt, reducing agent and sulfurizing agent (calculated as iron) is 1:1-5:0.02-0.2, preferably 1:1.5-3:0.03-0.

1.

6. The method according to claim 1, wherein, In step (3), the hypergravity conditions include: a rotational speed of 400-4000 rpm, preferably 2000-3000 rpm; a temperature of 20-25℃; and a time of 0.1-2 h, preferably 0.5-1 h. And / or, the filler in the supergravity machine is selected from at least one of wire mesh, porous corrugated plate, plastic porous plate and disc; And / or, the ratio of the rates at which mixture A and mixture B are added to the hypergravity machine is 1:0.5-1.5, preferably 1:0.8-1.2; And / or, relative to 10L of mixture A or mixture B, the feed rate of mixture A or mixture B is controlled to be 100-1000mL / min, preferably 200-600mL / min.

7. A sulfide nano-zero-valent iron, characterized in that, The sulfidated nano-zero valent iron is the sulfidated nano-zero valent iron prepared by the method described in any one of claims 1-6; Alternatively, the average particle size of the sulfide nano-zero valent iron is 1-20 nm, the proportion of particles with a particle size range of 1-10 nm in the total number of particles is ≥95%, and the specific surface area is ≥100 m². 2 / g.

8. The application of the sulfide nano-zero valent iron prepared by the method of any one of claims 1-6 or the sulfide nano-zero valent iron of claim 7 in the degradation of polluted groundwater.

9. A method for degrading polluted groundwater, characterized in that, The method includes: adding the sulfide nano-zero valent iron according to claim 7 into polluted groundwater; The amount of sulfide nano-zero valent iron added to the polluted groundwater is 0.1-5 g / L.

10. The method according to claim 9, wherein, The contaminated groundwater includes at least one of the following: carbon tetrachloride, trichloroethylene, tetrachloroethylene, hexachloroethane, polychlorinated biphenyls, chlorophenol, polybrominated diphenyl ethers, and organochlorine pesticides; And / or, the content of pollutants in the polluted groundwater is greater than the Class III groundwater quality indicators and limits specified in GB / T 14848-2017; And / or, the method does not include adjusting the pH value.

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