Sulfidized micron zero-valent iron, and preparation method and application thereof

Abstract

The application discloses sulfidized micron zero-valent iron, a preparation method and application thereof. The preparation method of the sulfidized micron zero-valent iron comprises the following steps: mixing sodium hyposulfite and iron powder and performing dry ball milling, so as to obtain the sulfidized micron zero-valent iron. The sulfidized micron zero-valent iron has high adsorption efficiency and large adsorption capacity for metal oxygen-containing anions, and has the advantages of simple preparation process, low production cost and environmental friendliness, and has a very wide application prospect in the field of heavy metal contaminated wastewater treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of heavy metal contaminated wastewater treatment, and in particular to sulfided micron zero-valent iron, a preparation method thereof, and an application thereof. Background Art

[0002] Zero-valent iron (ZVI) has the advantages of low price, strong reactivity, and environmental friendliness, and has attracted widespread attention in the field of heavy metal contaminated wastewater treatment. However, the surface of pure zero-valent iron is prone to form a dense oxide film (mainly composed of FeO, Fe3O4, Fe2O3 and FeOOH), which greatly hinders the electron transfer between ZVI and electron acceptors (such as O2, H + Compared to zero-valent iron, iron sulfide (FeS has a band gap of 0.10 eV, while FeS2 has a band gap of 0.95 eV) compared to iron oxide (Fe2O3 has a band gap of 2.2 eV). Therefore, the presence of iron sulfide can reduce the barrier to electron transfer, significantly improving the reactivity, selectivity, and long-term stability of zero-valent iron, and achieving better removal of pollutants from the environment.

[0003] There are two main methods for the sulfidation of microscale ZVI: mechanochemical ball milling and hydrochemical coprecipitation. Mechanochemical ball milling offers advantages such as simplicity, low cost, environmental friendliness, and the absence of byproducts, making it more practical than hydrochemical coprecipitation. Previous studies have reported the production of zero-valent iron sulfide by ball milling elemental sulfur and zero-valent iron under the protection of the inert gas argon for 24 hours. However, this method suffers from long milling times, high argon gas consumption, and high preparation costs. Furthermore, for flammable and explosive materials like elemental sulfur, mechanical ball milling at high temperatures can easily lead to safety hazards, making this method difficult to fully meet practical application requirements.

[0004] Therefore, it is of great significance to develop a simple, safe, inexpensive and high-yield method for preparing zero-valent iron sulfide and to prepare zero-valent iron sulfide with excellent performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a sulfide micron zero-valent iron and a preparation method and application thereof.

[0006] The technical solution adopted by the present invention is:

[0007] A preparation method of sulfided micron zero-valent iron comprises the following steps: mixing sodium dithionite and iron powder and performing dry ball milling to obtain sulfided micron zero-valent iron.

[0008] Preferably, the molar ratio of sulfur in the sodium dithionite to iron in the iron powder is 0.01 to 0.50:1.

[0009] More preferably, the molar ratio of sulfur in the sodium dithionite to iron in the iron powder is 0.01 to 0.20:1.

[0010] Preferably, the iron powder is at least one of elemental iron powder, reduced iron powder, cast iron powder, pig iron powder, and industrial scrap iron containing zero-valent iron.

[0011] Further preferably, the iron powder is reduced iron powder.

[0012] Preferably, the mass percentage of zero-valent iron in the iron powder is greater than 75%.

[0013] Preferably, the particle size of the iron powder is 10 μm to 100 μm.

[0014] Preferably, the diameter of the ball milling medium used in the dry ball milling is 0.1 mm to 10 mm, and the mass ratio of the ball milling medium to the material is 10 to 50:1.

[0015] Preferably, the ball milling medium is at least one of steel balls, silicon nitride beads, and zirconium oxide beads.

[0016] Preferably, the dry ball milling is carried out at a ball mill speed of 100 rpm to 1000 rpm, and the ball milling time is 0.5 h to 12 h.

[0017] Further preferably, the dry ball milling is carried out at a ball mill speed of 250 rpm to 500 rpm, and the ball milling time is 1 h to 4 h.

[0018] Preferably, the dry ball milling is performed in an air atmosphere, a nitrogen atmosphere or an argon atmosphere.

[0019] Further preferably, the dry ball milling is carried out in an air atmosphere.

[0020] Preferably, the ball milling equipment used in the dry ball milling is one of a planetary ball mill, a vibrating ball mill and a sand mill.

[0021] Sulfided micron zero-valent iron is prepared by the above preparation method.

[0022] A method for treating heavy metal contaminated wastewater comprises the following steps: adding the above-mentioned micron zero-valent iron sulfide into the heavy metal contaminated wastewater to adsorb heavy metal ions.

[0023] Preferably, the dosage of the sulfide micron zero-valent iron in the heavy metal contaminated wastewater is 0.05 g / L to 1.00 g / L.

[0024] Preferably, the heavy metal ions in the heavy metal-contaminated wastewater are at least one of arsenic (III), antimony (III), and antimony (V).

[0025] Preferably, the pH value of the heavy metal contaminated wastewater is 1-10.

[0026] Preferably, the adsorption time is 1h-12h.

[0027] Preferably, the adsorption is carried out under mechanical oscillation conditions, and the rotation speed of the oscillation device is 100r / min-200r / min.

[0028] The sulfidized micron zero-valent iron has high adsorption efficiency and large adsorption capacity for metal oxyanions, and has simple preparation process, low production cost and environmental friendliness, and has very broad application prospect in the field of heavy metal contaminated wastewater treatment.

[0029] Specifically:

[0030] 1) The sulfidized micron zero-valent iron of the present application enhances the amorphous divalent iron on the surface of the zero-valent iron by introducing sulfur atoms, greatly improves the removal capacity of the zero-valent iron for arsenic and antimony in wastewater, has fast adsorption rate and large adsorption capacity for arsenic and antimony, and has high efficiency in treating heavy metal contaminated wastewater.

[0031] 2) The sulfidized micron zero-valent iron of the present application can be prepared in an air atmosphere and for a short ball milling time, and the process is simple and easy to realize large-scale production. Compared with the existing mechanical chemical ball milling method, the preparation time is shortened, and there is no special atmosphere environment, no waste liquid is produced, no dangerous gas is produced, and no pollution to the environment.

[0032] 3) The sulfidizing agent used in the present application is sodium hyposulfite, which has the advantages of low price, high safety, easy storage and transportation compared with sodium sulfide, sodium sulfite and elemental sulfur (sodium sulfide and sodium sulfite are easy to absorb water, unstable, and elemental sulfur powder is flammable and explosive). BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Sulfidized micron zero-valent iron of Example 3 bm SEM and EDS spectra of Na2S2O4.

[0034] Figure 2 Sulfidized micron zero-valent iron of Example 3 bm Zero-valent iron of Comparative Example 1 bm Sulfidized zero-valent iron of Comparative Example 2 bm S 0 Sulfidized zero-valent iron of Comparative Example 3 bm XPS Fe 2p spectrum of Na2S2O3.

[0035] Figure 3This is a diagram showing the removal effect of Sb(III) by the sulfided micron zero-valent iron of Examples 1 to 5 and the zero-valent iron of Comparative Example 1.

[0036] Figure 4 This is a diagram showing the removal effect of Sb(V) by the sulfided micron zero-valent iron of Examples 1 to 5 and the zero-valent iron of Comparative Example 1.

[0037] Figure 5 Graph showing the As(III) removal effects of the sulfided micronized zero-valent iron of Example 3, the zero-valent iron of Comparative Example 1, and the sulfided zero-valent iron of Comparative Examples 2-3.

[0038] Figure 6 This is a diagram showing the removal effect of As(III) by the sulfided micron zero-valent iron of Example 3 and the sulfided zero-valent iron of Comparative Example 4. DETAILED DESCRIPTION

[0039] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0040] Example 1:

[0041] A sulfide micron zero-valent iron, the preparation method of which is as follows:

[0042] 0.07793 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.01:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill, stirred and mixed, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 hour, and the zirconia beads and the product are sieved to separate, thereby obtaining sulfide micron zero-valent iron (denoted as sulfide zero-valent iron). bm -Na2S2O4).

[0043] Example 2:

[0044] A sulfide micron zero-valent iron, the preparation method of which is as follows:

[0045] 0.1948 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.025:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill, stirred and mixed, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 hour, and the zirconia beads and the product are separated by sieving to obtain sulfide micron zero-valent iron (denoted as sulfide zero-valent iron). bm-Na2S2O4).

[0046] Example 3:

[0047] A sulfide micron zero-valent iron, the preparation method of which is as follows:

[0048] 0.3896 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.05:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill, stirred and mixed, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 hour, and the zirconia beads and the product are separated by sieving to obtain sulfide micron zero-valent iron (denoted as sulfide zero-valent iron). bm -Na2S2O4).

[0049] The scanning electron microscope (SEM) image and energy dispersive X-ray spectroscopy (EDS) image of the sulfide micron zero-valent iron in this embodiment are as follows: Figure 1 shown.

[0050] Depend on Figure 1 It can be seen that the surface of zero-valent iron becomes rough after sulfidation, and sulfur elements are evenly attached to the surface of zero-valent iron, indicating that FeS x Compounds, due to sulfur FeS x The compound has a lower band gap than iron oxide, so FeS x The presence of can reduce the barrier of electron transfer, thereby significantly improving the reactivity of zero-valent iron and increasing the efficiency of zero-valent iron in removing pollutants.

[0051] Example 4:

[0052] A sulfide micron zero-valent iron, the preparation method of which is as follows:

[0053] 0.7793 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.1:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill, stirred and mixed, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 hour, and the zirconia beads and the product are separated by sieving to obtain sulfide micron zero-valent iron (denoted as sulfide zero-valent iron). bm -Na2S2O4).

[0054] Example 5:

[0055] A sulfide micron zero-valent iron, the preparation method of which is as follows:

[0056] 1.1689 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.15:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill and stirred to mix. Then, 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 h, and the zirconia beads and the product are separated by sieving to obtain sulfide micron zero-valent iron (denoted as sulfide zero-valent iron). bm -Na2S2O4).

[0057] Comparative Example 1:

[0058] A zero-valent iron, the preparation method of which is as follows:

[0059] 5 g of reduced iron powder (the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) is added to a ball mill, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 h, and the zirconia beads and the product are separated by sieving to obtain zero-valent iron (denoted as zero-valent iron). bm ).

[0060] Comparative Example 2:

[0061] A zero-valent iron sulfide, the preparation method of which is as follows:

[0062] 0.1435 g of elemental sulfur powder and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.05:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill and stirred to mix. Then, 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mixture is ground in an air atmosphere at room temperature and pressure for 1 h, and the zirconia beads and the product are separated by sieving to obtain zero-valent iron sulfide (denoted as zero-valent iron sulfide). bm -S 0 ).

[0063] Comparative Example 3:

[0064] A zero-valent iron sulfide, the preparation method of which is as follows:

[0065] 0.3538 g of sodium thiosulfate (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.05:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a ball mill, stirred and mixed, and then 100 g of zirconia beads (composed of zirconia beads with a diameter of 3 mm and zirconia beads with a diameter of 6 mm in a mass ratio of 7:3) are added and sealed. The ball mill is then placed in a planetary ball mill, and the speed of the planetary ball mill is adjusted to 250 rpm. The mill is ground in an air atmosphere at room temperature and pressure for 1 h, and the zirconia beads and the product are separated by sieving to obtain zero-valent iron sulfide (denoted as zero-valent iron sulfide). bm -Na2S2O3).

[0066] Comparative Example 4:

[0067] A zero-valent iron sulfide, the preparation method of which is as follows:

[0068] 0.3896 g of sodium dithionite (anhydrous) and 5 g of reduced iron powder (the molar ratio of sulfur to iron is 0.05:1; the mass percentage of zero-valent iron in the reduced iron powder is greater than 75%) are added to a polytetrafluoroethylene bottle, and then 100 mL of deoxymorpholineethanesulfonic acid buffer solution (concentration is 50 mmol / L, pH value = 6.0) is added. The mixture is reacted at room temperature and stirred at a speed of 30 rpm for 24 hours, and then centrifuged. The solid obtained by centrifugation is washed with deionized water and freeze-dried for 24 hours to obtain zero-valent iron sulfide (denoted as zero-valent iron sulfide). lm -Na2S2O4).

[0069] Performance testing:

[0070] 1) Sulfurized micron zero-valent iron of Example 3 bm -Na2S2O4, zero-valent iron of Comparative Example 1 bm , Comparative Example 2: Sulfurized zero-valent iron bm -S 0 and the sulfide zero-valent iron of comparative example 3 bm -Na2S2O3 X-ray photoelectron spectroscopy (XPS) Fe 2p diagram Figure 2 shown.

[0071] Depend on Figure 2 It can be seen that: zero-valent iron bm The presence of Fe(0), Fe(II) and Fe(III) peaks indicates the presence of iron oxide and hydroxide (Fe2O3 and FeOOH) on the surface, while the sulfide micronized zero-valent iron bm -Na2S2O4, zero-valent iron sulfide bm -S 0 and zero-valent iron sulfide bm -Na2S2O3 Fe(0) peak disappears, indicating that the sulfur precursor reacts with zero-valent iron to generate FeS xCompounds; Sulfurized micronized zero-valent iron obtained by sulfurization with different sulfur sources bm -Na2S2O4, zero-valent iron sulfide bm -S 0 and zero-valent iron sulfide bm -Na2S2O3 surface Fe(II) strength is enhanced, the Fe(II) content is ranked as follows: Sulfide micron zero-valent iron bm -Na2S2O4>Zerovalent Iron Sulfide bm -S 0 >Zerovalent Iron Sulfide bm -Na2S2O3>Zerovalent Iron bm , it can be seen that the sulfide micron zero-valent iron bm -Na2S2O4 has the best performance.

[0072] 2) 30 mg of the sulfided micronized zero-valent iron of Examples 1 to 5 or the zero-valent iron of Comparative Example 1 was added to 30 mL of a 5 mg / L Sb(III) solution (simulating heavy metal-contaminated wastewater) with a pH of 6±0.1. The solution was then shaken at 150 rpm in a constant temperature shaker at 25°C±5°C. After reacting for 2 hours, the supernatant was filtered through a 0.22 μm polyethersulfone filter and diluted to determine the Sb(III) concentration of the solution. The Sb(III) removal efficiency is shown in Tables 1 and 2. Figure 3 As shown:

[0073] Table 1 Sb(III) removal effect test results

[0074] Test item Concentration before reaction (mg / L) Concentration after reaction (mg / L) Removal rate (%) Example 1 5 1.60 68.0 Example 2 5 1.50 70.0 Example 3 5 1.27 74.6 Example 4 5 1.12 77.6 Example 5 5 1.09 78.2 Comparative Example 1 5 4.41 11.8

[0075] From Table 1 and Figure 3 It can be seen that the sulfided micronized zero-valent iron of Examples 1 to 5 has a significantly improved Sb(III) removal effect compared to the zero-valent iron of Comparative Example 1, and has an excellent Sb(III) removal effect.

[0076] 3) 30 mg of the sulfided micronized zero-valent iron of Examples 1 to 5 or the zero-valent iron of Comparative Example 1 was added to 30 mL of a 5 mg / L Sb(V) solution (simulating heavy metal-contaminated wastewater) at a pH of 6±0.1. The solution was then shaken at 150 rpm in a constant temperature shaker at 25°C±5°C. After reacting for 2 hours, the supernatant was filtered through a 0.22 μm polyethersulfone filter and diluted to determine the Sb(V) concentration of the solution. The Sb(V) removal results are shown in Tables 2 and 3. Figure 4 As shown:

[0077] Table 2 Sb(V) removal effect test results

[0078]

[0079]

[0080] From Table 2 and Figure 4 It can be seen that the sulfided micronized zero-valent iron of Examples 1 to 5 has a significantly improved Sb(V) removal effect compared to the zero-valent iron of Comparative Example 1, and has an excellent Sb(V) removal effect.

[0081] 4) 20 mg of the sulfided micronized zero-valent iron of Example 3, the zero-valent iron of Comparative Example 1, or the zero-valent iron of Comparative Examples 2-4 were added to 100 mL of a 20 mg / L As(III) solution (simulating heavy metal-contaminated wastewater) at a pH of 7±0.1. The mixture was then shaken at 150 rpm in a constant temperature shaker at 25°C±5°C. After a certain reaction time, the supernatant was filtered through a 0.22 μm polyethersulfone filter and diluted to test the As(III) concentration of the solution. The As(III) removal effects obtained are shown in Table 3. Figure 5 and Figure 6 As shown:

[0082] Table 3 As(III) removal effect test results (reaction 30min)

[0083] Test item Concentration before reaction (mg / L) Concentration after reaction (mg / L) Removal rate (%) Example 3 20 0.25 98.75 Comparative Example 1 20 14.98 25.10 Comparative Example 2 20 3.26 83.70 Comparative Example 3 20 8.62 56.90 Comparative Example 4 20 15.49 22.55

[0084] From Table 3, Figure 5 and Figure 6 It can be seen that:

[0085] a) The sulfided micronized zero-valent iron of Example 3 significantly improves the As(III) removal effect compared to the zero-valent iron of Comparative Example 1 and the sulfided zero-valent iron of Comparative Examples 2 to 4, and has excellent As(III) removal effect;

[0086] b) The sulfide of the micronized zero-valent iron in Example 3 significantly improves the As(III) removal efficiency compared to the zero-valent iron sulfide in Comparative Examples 2-3. This indicates that the zero-valent iron sulfide prepared using sodium dithionite as a sulfiding agent is more active than the zero-valent iron sulfide prepared using elemental sulfur and sodium thiosulfate as sulfur sources, significantly improving the As(III) removal efficiency. This is because the zero-valent iron sulfide prepared using sodium dithionite as a sulfiding agent has a higher content of amorphous divalent iron, which can be converted more quickly under aerobic conditions, producing iron minerals with a higher specific surface area, thereby significantly enhancing the As(III) removal efficiency.

[0087] c) The sulfide micronized zero-valent iron of Example 3 significantly improves the As(III) removal efficiency compared to the zero-valent iron sulfide of Comparative Example 4, indicating that the zero-valent iron sulfide prepared by mechanical ball milling is more active than the zero-valent iron sulfide prepared by traditional sulfidation methods, and has a significantly improved As(III) removal efficiency.

[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for treating heavy metal contaminated wastewater, characterized in that: The following steps are involved: Adding sulfide micronized zero-valent iron into heavy metal-contaminated wastewater to adsorb heavy metal ions; The sulfide micron zero-valent iron is prepared by a preparation method comprising the following steps: mixing sodium dithionite and iron powder and dry ball milling to obtain the sulfide micron zero-valent iron; the molar ratio of sulfur in the sodium dithionite to iron in the iron powder is 0.01 to 0.50:1; the particle size of the iron powder is 10 μm to 100 μm; the diameter of the ball milling medium used in the dry ball milling is 0.1 mm to 10 mm, and the mass ratio of the ball milling medium to the material is 10 to 50:1; the dry ball milling is carried out at a ball mill speed of 100 rpm to 1000 rpm and a ball milling time of 0.5 h to 12 h; and the heavy metal ion is at least one of Sb(III), Sb(V), and As(III).

2. The method for treating heavy metal contaminated wastewater according to claim 1, wherein: The iron powder is reduced iron powder.

3. The method for treating heavy metal contaminated wastewater according to claim 1, wherein: The mass percentage of zero-valent iron in the iron powder is greater than 75%.

4. The method for treating heavy metal contaminated wastewater according to claim 1, wherein: The dry ball milling is performed in an air atmosphere, a nitrogen atmosphere or an argon atmosphere.

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