Preparation method and application of boron-doped vulcanized nano zero-valent iron material

Abstract

The invention relates to a preparation method and application of a boron-doped vulcanized nano zero-valent iron material. The lattice distortion is regulated and controlled on the basis of vulcanized nano zero-valent iron by regulating and controlling the type, the dosage and the like of the boron reagent, the passivation resistance of the material is enhanced, the defect that nano zero-valent iron is prone to inactivation is overcome, meanwhile, the electron transfer capacity and the Fe < 3 + > / Fe < 2 + > circulation capacity of the material are enhanced due to the fact that boron is doped as an electron donor, and the service life of the material is prolonged. The degradation-resistant organic matter DDT in soil and water can be efficiently removed. The synthesis method provided by the invention is easy to operate, can optimize the performance of the material, and can be applied to soil and water body remediation.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of functional nanomaterials. Background Art

[0002] Nano zero-valent iron (nZVI) materials are widely used for in-situ remediation in groundwater and soil due to their high reducibility. nZVI has a high specific surface area and nano-effects, and has strong reactivity towards heavy metals, antibiotics, pesticides, etc. However, the characteristics of easy oxidation and easy aggregation on the surface of nZVI lead to unstable degradation effects of actual groundwater and soil pollutants.

[0003] Regarding the defects of nano zero-valent iron, currently, single-atom doping (such as S, N, and metal atoms, etc.) or using a loading material to disperse nano zero-valent iron is mainly adopted to improve the surface oxidation and aggregation of the material. Among them, sulfidated nano zero-valent iron (S-nZVI) forms a ferrous sulfide shell layer through surface passivation, which can both relieve the oxidation of the material by dissolved oxygen and reduce aggregation, thereby increasing the material lifespan and degrading pollutants for a long time. And boron element, as a good electron donor, can promote the Fe 3 + / Fe 2+ cycle reaction, and can also activate sulfur elements and improve the material lattice structure to further enhance the electron transport performance. Therefore, in this patent, boron-doped sulfidated nano zero-valent iron materials are prepared by incorporating boron elements based on sulfidated nano zero-valent iron. This material retains the antioxidant and anti-aggregation abilities of sulfidated nano zero-valent iron. On this basis, the electron transport ability is enhanced through lattice distortion, and the incorporation of boron can further enhance the anti-passivation ability on the material surface; at the same time, the present invention responds to the concept of green environmental protection and will not cause additional pollution due to the introduction of boron. Summary of the Invention

[0004] The purpose of the present invention is to first propose a preparation method and application of boron-doped sulfidated nano zero-valent iron in view of the deficiencies of the prior art.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] In the first aspect, the present invention provides a preparation method of boron-doped sulfidated nano zero-valent iron, and the method includes the following steps:

[0007] (1) Take 0.1 - 2 grams of sulfur reagent and 5 - 10 grams of sodium borohydride, add them to 200 milliliters of deionized water to dissolve to obtain a sulfur solution, and aerate with nitrogen for 30 minutes to remove dissolved oxygen;

[0008] (2) Take 10 - 15 grams of iron reagent and 0.2 - 2 grams of boron reagent, add them to 250 milliliters of deionized water to dissolve to obtain a boron-iron solution, and aerate with nitrogen for 30 minutes to remove dissolved oxygen;

[0009] (3) Under the condition of nitrogen atmosphere and mechanical stirring at 100 - 500 revolutions per minute, the sulfur solution in step (1) is added dropwise to the ferroboron solution in step (2) at a rate of 5 - 30 milliliters per minute, and stirring is continued for 0.5 - 1 hour after the addition is completed;

[0010] (4) After the stirring ends, solid - liquid separation is carried out by magnetic adsorption. The solid is washed 3 times with anaerobic deionized water and anaerobic ethanol respectively, and vacuum - dried at - 60 °C for 6 - 12 hours to obtain a dry solid;

[0011] (5) The dry solid in step (4) is ground into a powder to obtain boron - doped sulfur - containing nano - zero - valent iron, denoted as BS - nZVI;

[0012] Furthermore, the sulfur reagent in step (1) includes sodium thiosulfate, sodium dithionite or sodium sulfide.

[0013] Furthermore, the iron reagent in step (2) includes ferrous sulfate and ferric chloride.

[0014] Furthermore, the boron reagent in step (2) includes sodium tetraborate, boron oxide or boric acid.

[0015] In a second aspect, the present invention provides a boron - doped sulfur - containing nano - zero - valent iron material prepared by the above method.

[0016] In a third aspect, the present invention provides an application of the boron - doped sulfur - containing nano - zero - valent iron material, and the boron - doped sulfur - containing nano - zero - valent iron material is used for the removal of DDT in soil and water bodies.

[0017] Furthermore, this application includes two directions, namely the remediation of DDT - contaminated soil and the remediation of DDT - polluted water bodies. First, for the remediation of DDT - contaminated soil, it includes the following characteristics:

[0018] (1) The boron - doped sulfur - containing nano - zero - valent iron is fully mixed with the DDT - contaminated soil, and anaerobic water is added to submerge the soil by 1 - 5 cm, and shaken to form a soil solution;

[0019] (2) The mixed soil solution of the materials and pollutants in step (1) is oscillated to ensure sufficient reaction for 1 - 20 days;

[0020] (3) Furthermore, the concentration of the DDT - contaminated soil in step (1) is 0.1 - 20 milligrams per gram of soil, and the types of the contaminated soil include soil, river - lake bottom mud, etc.

[0021] Secondly, for the remediation of DDT - polluted water bodies, it includes the following characteristics:

[0022] (1) Add the boron-doped sulfurized nano zero-valent iron to the DDT-contaminated water in step (1), and mix well by shaking.

[0023] (2) Oscillate the mixture containing the material and the pollutant in step (1) to ensure sufficient reaction for 1 to 20 days.

[0024] (3) Further, the concentration of the DDT-contaminated water in step (1) is 0.1 to 20 mg per gram of soil, and the types of the contaminated water bodies include groundwater, surface water, and sewage, etc.

[0025] Further, in the remediation step (2) of the DDT-contaminated soil and the DDT-contaminated water body, the dosages of the boron-doped sulfurized nano zero-valent iron are 0.1 to 10 grams per gram of soil and 0.1 to 10 grams per liter respectively.

[0026] Even further, in the remediation step (2) of the DDT-contaminated soil and the DDT-contaminated water body, the reaction temperature is 0 to 35 degrees Celsius.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) The boron-doped sulfurized nano zero-valent iron is prepared by a one-step method, and the operation is simple.

[0029] (2) This method can realize the doping of boron in the sulfurized nano zero-valent iron. As an electron donor and an anti-passivation agent, boron increases the effect and service life of the material.

[0030] (3) This method can change the lattice structure of the material and significantly improve the electron transfer performance.

[0031] (4) This method will not introduce new pollution due to boron.

[0032] (5) This material can efficiently remediate the DDT-contaminated soil and the contaminated water body. Description of the Drawings

[0033] Figure 1 is the X-ray diffraction pattern of the boron-doped sulfurized nano zero-valent iron;

[0034] Figure 2 is the scanning electron microscope picture (SEM) of the sulfurized nano zero-valent iron;

[0035] Figure 3 is the water contact angle diagram of the material;

[0036] Figure 4 is the Tafel slope diagram of the sulfurized nano zero-valent iron material;

[0037] Figure 5 is the diagram of the change of the DDT concentration with time in the soil reaction system;

[0038] Figure 6 It is a graph showing the change of DDT concentration over time in the water reaction system;

[0039] Figure 7 It is a graph showing the change of DDT concentration over time in the water reaction system. Specific implementation manners

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts are within the protection scope of the present invention.

[0041] In the following embodiments, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0042] The present invention provides the preparation of 4 kinds of boron-doped sulfurized nano-zero-valent iron materials with different ratios, which is characterized in that the doping amount of boron is changed by regulating the types and dosages of boron reagents.

[0043] Example 1 Preparation of a kind of boron-doped sulfurized nano-zero-valent iron (B / Fe = 0.05)

[0044] The main implementation steps include:

[0045] (1) Take 0.16 grams of sodium sulfide nonahydrate and 6.77 grams of sodium borohydride, add them to 200 milliliters of deionized water to dissolve to obtain a sulfur solution, and aerate with nitrogen for 30 minutes to remove dissolved oxygen;

[0046] (2) Take 12.45 grams of ferrous sulfate heptahydrate and 0.21 grams of sodium tetraborate decahydrate, add them to 250 milliliters of deionized water to dissolve to obtain a boron-iron solution, and aerate with nitrogen for 30 minutes to remove dissolved oxygen;

[0047] (3) Under the condition of nitrogen atmosphere and mechanical stirring at 300 revolutions per minute, slowly add the sulfur solution in step (1) to the boron-iron solution in step (2) at a speed of 5 milliliters per minute, and continue stirring for 0.5 hour after the addition is completed;

[0048] (4) After the stirring is completed, solid-liquid separation is carried out by magnetic adsorption. The solid is washed 3 times with anaerobic deionized water and anaerobic ethanol respectively, and vacuum-dried at -60 °C for 12 hours to obtain a dried solid.

[0049] Example 2 Preparation of a kind of boron-doped sulfurized nano-zero-valent iron (B / Fe = 0.1)

[0050] (1) Take 0.16 g of sodium sulfide nonahydrate and 6.77 g of sodium borohydride, add them to 200 mL of deionized water and dissolve to obtain a sulfur solution. Pass nitrogen gas through it for aeration for 30 minutes to remove dissolved oxygen;

[0051] (2) Take 12.45 g of ferrous sulfate heptahydrate and 0.43 g of sodium tetraborate decahydrate, add them to 250 mL of deionized water and dissolve to obtain a boron-iron solution. Pass nitrogen gas through it for aeration for 30 minutes to remove dissolved oxygen;

[0052] (3) Under a nitrogen atmosphere and with mechanical stirring at 300 revolutions per minute, slowly add the sulfur solution in step (1) to the boron-iron solution in step (2) at a rate of 5 mL per minute, and continue stirring for 0.5 hours after the addition is complete;

[0053] (4) After the stirring is completed, perform solid-liquid separation by magnetic adsorption. Wash the solid three times each with anaerobic deionized water and anaerobic ethanol, and vacuum dry it at -60 °C for 12 hours to obtain a dried solid.

[0054] Example 3 Preparation of boron-doped sulfidated nano-zero-valent iron (B / Fe = 0.21)

[0055] (1) Take 0.16 g of sodium sulfide nonahydrate and 6.77 g of sodium borohydride, add them to 200 mL of deionized water and dissolve to obtain a sulfur solution. Pass nitrogen gas through it for aeration for 30 minutes to remove dissolved oxygen;

[0056] (2) Take 12.45 g of ferrous sulfate heptahydrate and 0.9 g of sodium tetraborate decahydrate, add them to 250 mL of deionized water and dissolve to obtain a boron-iron solution. Pass nitrogen gas through it for aeration for 30 minutes to remove dissolved oxygen;

[0057] (3) Under a nitrogen atmosphere and with mechanical stirring at 300 revolutions per minute, slowly add the sulfur solution in step (1) to the boron-iron solution in step (2) at a rate of 5 mL per minute, and continue stirring for 0.5 hours after the addition is complete;

[0058] (4) After the stirring is completed, perform solid-liquid separation by magnetic adsorption. Wash the solid three times each with anaerobic deionized water and anaerobic ethanol, and vacuum dry it at -60 °C for 12 hours to obtain a dried solid.

[0059] Example 4 Preparation of boron-doped sulfidated nano-zero-valent iron (B / Fe = 0.3)

[0060] (1) Take 0.16 g of sodium sulfide nonahydrate and 6.77 g of sodium borohydride, add them to 200 mL of deionized water and dissolve to obtain a sulfur solution. Pass nitrogen gas through it for aeration for 30 minutes to remove dissolved oxygen;

[0061] (2) Weigh 12.45 g of ferrous sulfate heptahydrate and 1.28 g of sodium tetraborate decahydrate, add them to 250 mL of deionized water to dissolve and obtain a boron-iron solution, and aerate with nitrogen for 30 minutes to remove dissolved oxygen;

[0062] (3) Under a nitrogen atmosphere and with mechanical stirring at 300 rpm, slowly add the sulfur solution in step (1) to the boron-iron solution in step (2) at a rate of 5 mL / min, and continue stirring for 0.5 h after the addition is completed;

[0063] (4) After the stirring is completed, perform solid-liquid separation by magnet adsorption. The solid is washed 3 times with anaerobic deionized water and anaerobic ethanol respectively, and then vacuum dried at -60 °C for 12 h to obtain a dried solid.

[0064] Application Example 1 X-ray Diffraction Test Experiment

[0065] Prepare the comparative materials nano zero-valent iron (nZVI) and sulfurized nano zero-valent iron (S-nZVI) without adding sodium sulfide and sodium tetraborate under the same synthesis conditions, and prepare the comparative material sulfurized nano zero-valent iron (S-nZVI) without adding sodium tetraborate under the same synthesis conditions. Perform X-ray diffraction tests on the comparative materials nano zero-valent iron (nZVI), sulfurized nano zero-valent iron (S-nZVI), and the material boron-doped sulfurized nano zero-valent iron (BS-nZVI) in Example 3. The test results are as Figure 1 shown.

[0066] It can be seen from Figure 1 that for the boron-doped sulfurized nano zero-valent iron (BS-nZVI) prepared in Example 3, the characteristic crystal form peaks of Fe 0 are retained, and the corresponding peak positions of the 110 crystal plane are shifted relatively, indicating that boron is doped into the lattice of sulfurized sodium zero-valent iron, and the material is successfully synthesized.

[0067] Application Example 2 Scanning Electron Microscope Experiment

[0068] Perform scanning electron microscope tests on the comparative materials nano zero-valent iron (nZVI), sulfurized nano zero-valent iron (S-nZVI), and the material boron-doped sulfurized nano zero-valent iron (BS-nZVI) in Example 3. The test results are as Figure 2 shown.

[0069] It can be seen from Figure 1 that for the boron-doped sulfurized nano zero-valent iron (BS-nZVI) material prepared in Example 3, the size is reduced compared to sulfurized nano zero-valent iron, increasing the reaction contact area.

[0070] Application Example 3 Hydrophobicity Experiment

[0071] The contact angle tests were respectively carried out on the comparative materials nano zero-valent iron (nZVI), sulfide nano zero-valent iron (S-nZVI), and the material boron-doped sulfide nano zero-valent iron (BS-nZVI) involved in Example 3. The water contact angles of each material are as Figure 3 shown. Although the hydrophobicity of the synthesized material is weakened compared with that of sulfide nano zero-valent iron, it still retains a certain degree of hydrophobicity, which is related to the overall performance improvement brought by the enhanced electron transfer performance it obtained.

[0072] Application Example 4 Electrochemical Experiment

[0073] Respectively take the material in Example 3 (BS-nZVI), nano zero-valent iron (nZVI) prepared according to the same steps as in Example 3 without adding sodium sulfide and sodium tetraborate, and sulfide nano zero-valent iron (S-nZVI) prepared according to the same steps as in Example 3 without adding sodium tetraborate, disperse them into an ethanol solution containing 50 μL of 5% Nafion and ultrasonicate for 30 minutes to form a uniform suspension; then drop 5 μL of the suspension onto the surface of a glassy carbon electrode respectively. After natural drying, linear sweep voltammetry (LSV) electrochemical tests are carried out in a three-electrode cell with 500 mmol / L sodium sulfate as the electrolyte. The test results are as Figure 4 shown. The results show that the impedance of the boron-doped sulfide nano zero-valent iron material is significantly reduced compared with that of nano zero-valent iron and sulfide nano zero-valent iron, indicating that the electron transfer performance of the material is significantly improved after boron doping. According to the peak position shift described in Application Example 1, it can be explained that it is caused by the lattice distortion due to boron doping.

[0074] Application Example 5 DDT Removal Experiment in Soil

[0075] After adding the prepared DDT solution to the collected uncontaminated soil, stirring it well and drying it in a cool place, the pollutant concentration of the contaminated soil is made to be 20 mg / g of contaminated soil. 5 g of DDT-contaminated soil is respectively mixed with 0.05 g of the boron-doped sulfide nano zero-valent iron (BS-nZVI) in Example 3 and the comparative materials (nZVI, S-nZVI) described in Application Example 1, and 5 mL of deionized water is added. After shaking well to form a soil solution, samples are taken after reacting for 0, 12, 24, 48, and 72 hours in a shaking environment. After extraction, gas chromatography is used to determine the degradation of DDT in the soil by various materials. The degradation effect of DDT in the soil is as Figure 5 shown. From Figure 5 it can be seen that the effects of nano zero-valent iron (nZVI) and sulfide nano zero-valent iron (S-nZVI) in the soil are limited, while the degradation of DDT in the soil by nano zero-valent iron (BS-nZVI) is relatively good.

[0076] Application Example 6 DDT Removal Experiment in Water

[0077] Prepare a DDT-contaminated solution with a concentration of 2 mg / L. Mix 5 mL of the DDT solution with 0.05 g of the boron-doped sulfurized nano zero-valent iron (BS-nZVI) in Example 3 and the comparative materials (nZVI, S-nZVI) in Application Example 1 respectively, and shake well to form a soil solution. Samples are taken after reacting for 0, 12, 24, 48, and 72 hours in a shaking environment. After extraction, gas chromatography is used to determine the degradation of DDT in the soil by various materials. The degradation effect on DDT in water is as Figure 6 shown. As Figure 6 can be seen, the degradation rates of nano zero-valent iron (nZVI), sulfurized nano zero-valent iron (S-nZVI), and boron-doped sulfurized nano zero-valent iron (BS-nZVI) for DDT in the soil are 86.75%, 87.68%, and 90.21% respectively. Compared with the comparative materials, the effect of the boron-doped sulfurized nano zero-valent iron involved in the present invention has been significantly improved.

[0078] Application Example 7 Removal experiment of four kinds of boron-doped sulfurized nano zero-valent iron for DDT in soil

[0079] Add the prepared DDT solution to the collected uncontaminated soil, stir well, and dry it in a cool place to make the pollutant concentration of the contaminated soil 20 mg / g of contaminated soil. Mix 5 g of DDT-contaminated soil with 0.05 g of four kinds of boron-doped sulfurized nano zero-valent iron (B / Fe = 0.05, B / Fe = 0.1, B / Fe = 0.21, B / Fe = 0.3) with boron-iron ratios of 0.05, 0.1, 0.21, and 0.3 in Examples 1-4 respectively, and add 5 mL of deionized water. Shake well to form a soil solution. Samples are taken after reacting for 0, 12, 24, 48, and 72 hours in a shaking environment. After extraction, gas chromatography is used to determine the degradation of DDT in the soil by various materials. The degradation effect on DDT in the soil is as Figure 7 shown. Figure 7 It shows that boron-doped sulfurized nano zero-valent iron with different boron-iron ratios can all have a good degradation effect on DDT in the soil. The group with the worst effect, B / Fe = 0.1, also has a significant improvement compared with the comparative materials. The best degradation rate of the four kinds of boron-doped sulfurized nano zero-valent iron (B / Fe = 0.05, B / Fe = 0.1, B / Fe = 0.21, B / Fe = 0.3) for DDT in the soil even reaches 90%.

[0080] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, decorations, equivalent replacements, improvements, etc. made by any relevant person within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing boron-doped sulfide nano zero-valent iron, characterized in that: The following steps are involved: (1) 0.1-2 g of sulfur reagent and 5-10 g of sodium borohydride are added to 200 ml of deionized water to dissolve to obtain a sulfur solution, and nitrogen is aerated for 30 minutes to remove dissolved oxygen; (2) taking 10-15 g of an iron reagent and 0.2-2 g of a boron reagent, adding them to 250 ml of deionized water to dissolve to obtain a boron iron solution, and introducing nitrogen gas for aeration for 30 minutes to remove dissolved oxygen; (3) under a nitrogen atmosphere and with mechanical stirring at 100 to 500 rpm, the sulfur solution in step (1) is added dropwise to the ferroboron solution in step (2) at a rate of 5 to 30 ml / min, and stirring is continued for 0.5 to 1 hour after the addition is completed; (4) after the stirring is completed, the solid-liquid separation is performed by magnetic adsorption, the solid is washed with oxygen-free deionized water and oxygen-free ethanol three times each, and vacuum dried at -60 degrees Celsius for 6 to 12 hours to obtain a dry solid; (5) grinding the dried solid in step (4) into a powder to obtain boron-doped sulfide nano-zero-valent iron, denoted as BS-nZVI; The sulfur reagent in step (1) includes sodium thiosulfate, sodium dithionite or sodium sulfide; The iron reagent in step (2) includes ferrous sulfate or ferric chloride; The boron reagent in step (2) includes sodium tetraborate, boric oxide or boric acid.

2. Boron-doped sulfide nanometer zero-valent iron prepared by the method of claim 1.

3. The use of the boron-doped sulfide nano zero-valent iron according to claim 2, characterized in that: The boron-doped sulfide nano zero-valent iron is used for dechlorinating DDT in soil or water.

4. The use according to claim 3, characterized in that: The following steps are involved: (1) mixing the boron-doped nano-zero-valent iron sulfide with DDT-contaminated soil, adding oxygen-free water to submerge the soil by 1 to 5 cm, and shaking to form a soil solution; the boron-doped nano-zero-valent iron sulfide is added in an amount of 0.1 to 10 g per gram of soil and 0.1 to 10 g per liter, respectively; (2) mixing the material and the pollutant in step (1) into a soil solution and subjecting the mixture to an oscillating reaction for 1 to 20 days at a reaction temperature of 0 to 35 degrees Celsius; The concentration of DDT contaminated soil in step (1) is 0.1 to 20 mg per gram of soil, and the contaminated soil type includes soil or river and lake sediment.

5. The use according to claim 3, characterized in that: The following steps are involved: (1) adding the boron-doped nano-zero-valent iron sulfide to the DDT-contaminated water in step (1), and mixing by shaking; the amount of the boron-doped nano-zero-valent iron sulfide added is 0.1 to 10 grams per liter of water; (2) shaking the mixture containing the material and the pollutant in step (1) and reacting for 1 to 20 days at a temperature of 0 to 35 degrees Celsius; The concentration of DDT-contaminated water in step (1) is 0.1 to 20 mg / g soil, and the types of contaminated water include groundwater, surface water or sewage.

Images