A Prussian blue-nano zero-valent iron composite material, its preparation method and application

Abstract

This invention discloses a Prussian blue-nano zero-valent iron composite material, its preparation method, and its application, belonging to the field of nanomaterials and thallium removal. The method uses sodium borohydride reduction to synthesize the Prussian blue (PB)-nano zero-valent iron (nZVI) composite material (PB@nZVI) at room temperature. Compared with Prussian blue and nano zero-valent iron alone, the prepared PB@nZVI exhibits high removal rate and high selectivity for Tl(I). It can be used as an effective adsorbent for Tl(I) pollution in water bodies for the treatment of heavy metal pollution in water bodies.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and thallium removal, specifically relating to a Prussian blue-nano zero-valent iron composite material (PB@nZVI) and its preparation method and application. Background Technology

[0002] Thallium (Tl) is an extremely toxic heavy metal element, far more harmful to mammals than conventional heavy metals such as mercury, arsenic, cadmium, lead, and antimony. Thallium exhibits both lithophile and chalcophile properties, often occurring as an associated mineral in pyrite, lead-zinc ore, and other minerals. my country is rich in thallium resources, boasting the world's largest reserves. Thallium concentrations in natural water bodies are generally low: 0.001-0.41 μg / L in lakes, 0.013-1.35 μg / L in rivers, and 0.001-0.55 μg / L in groundwater. However, thallium levels are significantly higher in surface water and groundwater surrounding mining and smelting plants. With the development of my country's smelting industry, thallium pollution incidents occur frequently. The national and Guangdong provincial governments have successively issued strict standards for the discharge of thallium pollutants into industrial wastewater.

[0003] Thallium in the aquatic environment mainly exists in the forms of Tl(I) and Tl(III). In natural water bodies and industrial wastewater, most Tl exists in the form of Tl(I). Tl(I) has high solubility, stability, and fluidity in water, making it difficult to adsorb and form hydroxides, thus more difficult to treat than Tl(III). As the impact of thallium pollution on the environment and human health continues to expand, the search for efficient and economical wastewater thallium pollution treatment technologies is urgent. Currently, Tl(I) treatment mainly includes chemical precipitation, ion exchange, solvent extraction, and adsorption. However, chemical precipitation, solvent extraction, and ion exchange methods have drawbacks, such as low selectivity in the presence of competing ions and the potential for secondary pollution. Therefore, solid-phase adsorption materials utilizing carbon materials and Al, Ti, Fe, or Mn-based adsorption to remove Tl(I) have attracted much attention due to their convenience, ease of operation, high efficiency, stability, and low cost. Among these adsorbents, titanium peroxide, nano-manganese dioxide (nMnO2), nano-zero-valent iron (nZVI), and iron-manganese composite oxides showed excellent removal performance of Tl in water with low levels of coexisting ions in laboratory tests.

[0004] nZVI possesses a high specific surface area and high reactivity, exhibiting magnetic properties for easy separation and is widely used in the treatment of heavy metals. However, its tendency to aggregate and be easily deactivated by oxidation limits its applications. Furthermore, in real-world water / wastewater environments, coexisting ions (such as Ca2+)... 2+ Mg 2+ K +The concentration of Tl(I) is typically hundreds or even thousands of times higher than that of Tl. At this concentration, the removal efficiency of adsorbents such as nZVI for Tl(I) deteriorates, indicating low selectivity. Therefore, developing adsorbents with high selectivity and large adsorption capacity is of great significance for treating Tl-polluted wastewater.

[0005] For many years, Prussian blue (PB, Fe4[Fe(CN))6]3) has been considered an antidote for thallium poisoning in animals and humans, demonstrating its safety, high selectivity, and effectiveness. Studies have shown that the application of PB and its analogues (PBAs) is considered a feasible method for the selective removal of Tl(I) from wastewater containing coexisting ions. However, in large-scale treatment of Tl(I)-containing wastewater, systems involving PB or PBA nano / micro particles face challenges in separating and recovering them from the treated wastewater, and the residual PB or PBA in the water poses a risk of secondary pollution. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing treatment technologies for Tl(I) contaminated water by providing a Prussian blue-nano zero-valent iron composite material, its preparation method, and a method for highly selectively removing monovalent thallium from water. By utilizing the Prussian blue-nano zero-valent iron composite material (PB@nZVI) to treat the heavy metal Tl(I), it efficiently removes Tl(I) through adsorption, significantly reducing the mobility of Tl(I) in water, thereby achieving the goal of remediating groundwater and surface water in contaminated sites. This method is low-cost, simple in process, and the resulting material exhibits high reactivity, good stability, and strong selectivity, making it suitable for industrial production.

[0007] The objective of this invention is achieved through the following technical solutions.

[0008] A method for preparing a Prussian blue-nano zero-valent iron composite material includes the following steps:

[0009] NaBH4 was added to K4[Fe(CN)6]·3H2O solution to form a mixed solution, and then FeCl3 solution was added dropwise. The mixture was stirred until it was fully reacted, and then the precipitate was collected by centrifugation and washed to obtain the Prussian blue-nano zero-valent iron composite material, labeled PB@nZVI.

[0010] Preferably, the molar ratio of NaBH4 to FeCl3 is 3:1 to 3.5:1.

[0011] Preferably, the molar ratio of FeCl3 to K4[Fe(CN)6]·3H2O is 4:3 to 8:3.

[0012] Preferably, the molar ratio of NaBH4 to FeCl3 is 3:1, and the deionized water used in the synthesis process is purged with N2 for 25 minutes before use to remove dissolved oxygen.

[0013] A Prussian blue-nano zero-valent iron composite material prepared by any of the above preparation methods.

[0014] The application of the Prussian blue-nano zero-valent iron composite material described above in the removal of Tl(I) from wastewater includes the following steps:

[0015] Prussian blue-nano zero-valent iron composite material was added to wastewater containing Tl(I), and the mixture was subjected to constant temperature shaking. The concentration of Tl(I) in the solution after the reaction was then measured.

[0016] Preferably, the pH of the Tl(I)-containing wastewater is 3-11, and more preferably 3-9.

[0017] Preferably, the initial concentration of Tl(I) in the wastewater is in the range of 1-100 mg / L, and more preferably 1-20 mg / L.

[0018] Preferably, the amount of the Prussian blue-nano zero-valent iron composite material added to wastewater containing Tl(I) is 0.1-0.5 g / L, and more preferably 0.2-0.5 g / L.

[0019] Preferably, the isothermal oscillation reaction temperature is 25±0.2℃, the reaction time is 4h, and the rotation speed is 250r / min.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0021] The PB@nZVI of this invention is a modified nano-zero-valent iron. Compared with nano-zero-valent iron materials, the prepared PB@nZVI has higher selectivity, increasing the efficiency of treating Tl(I) pollution in water bodies. The PB@nZVI of this invention improves the antioxidant properties, stability, and selectivity of nano-zero-valent iron particles, and has a high removal capacity for Tl(I) environmental pollutants, making it suitable as an adsorbent material for the treatment of heavy metal pollution in water environments. Attached Figure Description

[0022] Figure 1 X-ray powder diffraction (XRD) analysis results for PB@nZVI, nZVI, and PB.

[0023] Figure 2 This is a scanning electron microscope (SEM) image of PB@nZVI.

[0024] Figure 3A comparison chart of the removal rates of Tl(I) by PB@nZVI, nZVI, and PB.

[0025] Figure 4 , Figure 5 , Figure 6 The figure shows the degradation of Tl(I) by PB@nZVI. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0027] Example 1

[0028] PB@nZVI was prepared by sodium borohydride reduction. 0.6446 g of NaBH4 was added to 50 mL of 42.6 mmol / L K4[Fe(CN)6]·3H2O solution to form a mixed solution. This solution was then added dropwise to 400 mL of 14.2 mmol / L FeCl3 solution. The solution was stirred at 300 rpm with an electric stirrer. After the addition was complete, stirring continued for 10 min to ensure complete reaction. The precipitate was collected by centrifugation and washed twice alternately with deionized water and anhydrous ethanol to obtain PB@nZVI. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) analyses are shown below. Figure 1 , Figure 2 All washed materials were sealed with anhydrous ethanol and stored in a refrigerator at 4°C until use.

[0029] Batch experiments were conducted using 50 mL centrifuge tubes as reactors. 25 mL of a 20 mg / L Tl(I) solution was introduced, and dissolved oxygen was removed by purging with N2 for 5 min. Then, 0.005 g of PB@nZVI, nZVI, and PB were added, and the tubes were sealed. The reaction was carried out in a shaker at room temperature (25 ± 0.2 °C) and 250 rpm. After 4 h of reaction, the solution was filtered through a 0.22 μm pinhole filter into 10 mL centrifuge tubes. The concentration of Tl(I) in the solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). All experimental samples were tested in triplicate, and the average value was taken. The reaction product was obtained by centrifuging the centrifuge tubes at 8000 rpm for 5 min, washing twice with deionized water and anhydrous ethanol, respectively. The solid product was then obtained by vacuum drying for 24 h.

[0030] Depend on Figure 3 It can be seen that PB@nZVI has a much higher removal rate of Tl(I) than nZVI and PB. At a dosage of 0.1 g / L, PB@nZVI has a removal rate of more than 90% for Tl(I), while nZVI and PB have removal rates of approximately 40% and 64%, respectively. When the dosage reaches 0.2 g / L, the removal rate of PB@nZVI reaches 99%.

[0031] Example 2

[0032] A 50 mL centrifuge tube was used as the reactor to treat Tl(I) at a concentration of 1 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 7.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0033] Example 3

[0034] A 50 mL centrifuge tube was used as the reactor to treat Tl(I) at a concentration of 5 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 7.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0035] Example 4

[0036] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 10 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 7.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0037] Example 5

[0038] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 20 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 7.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0039] Example 6

[0040] A 50 mL centrifuge tube was used as the reactor to treat Tl(I) at a concentration of 100 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 7.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0041] The specific results are shown in Table 1 and... Figure 4 As shown.

[0042] Table 1 Removal rates of five initial concentrations of Tl(I)

[0043]

[0044] From Table 1 and Figure 4 It can be seen that the removal rate of Tl(I) first increases and then decreases with the increase of the initial concentration.

[0045] Example 7

[0046] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 20 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 3.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0047] Example 8

[0048] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 20 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 5.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0049] Example 9

[0050] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 20 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 9.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0051] Example 10

[0052] A 50 mL centrifuge tube was used as the reactor to treat a Tl(I) concentration of 20 mg / L. 25 mL of wastewater containing Tl(I) was measured, and the pH was adjusted to 11.0 using 0.1 mol / L nitric acid and 0.1 mol / L sodium hydroxide. N2 was bubbled through the water for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the Tl(I) concentration was determined by ICP-OES.

[0053] The specific results are shown in Table 2 and Figure 5 As shown.

[0054] Table 2 Removal rates of Tl(I) at five different pH values

[0055]

[0056] From Table 2 and Figure 5 It can be seen that when the pH value is 3-9, the removal rate of Tl(I) changes little, and more than 97% of Tl(I) is removed; when pH=11, 49% of Tl(I) is removed.

[0057] Example 11

[0058] A 50ml centrifuge tube was used as the reactor to process 20mg / L Tl(I) and 10mg / L coexisting ions (K). + Ni 2+ Pb 2+ Zn 2+ Ca 2+ Mg 2+ Cd 2+ Cu 2+A mixed solution containing Tl(I) was prepared. 25 mL of the mixed solution was taken, and N2 was bubbled through it for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0059] Example 12

[0060] A 50ml centrifuge tube was used as the reactor to process 20mg / L Tl(I) and 100mg / L coexisting ions (K). + Ni 2+ Pb 2+ Zn 2+ Ca 2+ Mg 2+ Cd 2+ Cu 2+ A mixed solution containing Tl(I) was prepared. 25 mL of the mixed solution was taken, and N2 was bubbled through it for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0061] Example 13

[0062] A 50ml centrifuge tube was used as the reactor to process 20mg / L Tl(I) and 1000mg / L coexisting ions (K). + Ni 2+ Pb 2+ Zn 2+ Ca 2+ Mg 2+ Cd 2+ Cu 2+ A mixed solution containing Tl(I) was prepared. 25 mL of the mixed solution was taken, and N2 was bubbled through it for 5 min to remove dissolved oxygen. 0.005 g of PB@nZVI was added, and the reactor was placed on a constant-temperature shaker at 25 ± 0.2 °C and 250 r / min for 4 h. The solution was filtered, and the concentration of Tl(I) in the solution was determined by ICP-OES.

[0063] Specific results are as follows Figure 6 As shown. K + Ni 2+ Pb 2+ Zn 2+ Ca 2+ Mg 2+ Cd 2+The effect of PB@nZVI on the removal of Tl(I) is relatively small (removal rate > 95%), Cu 2+ The effect of PB@nZVI on the removal of Tl(I) is quite significant, but the removal rate still reaches 80%, showing excellent selectivity.

[0064] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. Use of Prussian blue-nanoscale zero-valent iron composite for the removal of Tl(I) from wastewater, characterized in that, The method comprises the following steps: The Prussian blue-nano zero-valent iron composite material is added into the Tl(I)-containing wastewater, constant temperature oscillation is carried out, and then the concentration of Tl(I) in the solution after reaction is detected; The pH of the Tl(I)-containing wastewater is 3-11; The initial concentration of Tl(I) in the wastewater is 1-100 mg / L; The adding amount of the Prussian blue-nano zero-valent iron composite material in the Tl(I)-containing wastewater is 0.1-0.5 g / L; The preparation method of the Prussian blue-nano zero-valent iron composite material comprises the following steps: NaBH4 is added into a K4[Fe(CN)6]·3H2O solution to form a mixed solution, then the mixed solution is added dropwise into a FeCl3 solution, stirring is carried out to fully react, then the precipitate is collected by centrifugation and washed to obtain the Prussian blue-nano zero-valent iron composite material, which is marked as PB@nZVI; The molar ratio of NaBH4 to FeCl3 is 3:1-3.5:1; The molar ratio of FeCl3 to K4[Fe(CN)6]·3H2O is 4:3-8:

3.

2. The use of a Prussian blue-nanoscale zero-valent iron composite material according to claim 1 for removing Tl(I) from wastewater, characterized in that, The pH of the Tl(I)-containing wastewater is 3-9; the initial concentration of Tl(I) in the wastewater is 1-20 mg / L; and the adding amount of the Prussian blue-nano zero-valent iron composite material in the Tl(I)-containing wastewater is 0.2-0.5 g / L.

3. Use of a Prussian blue-nanoscale zero-valent iron composite material according to claim 1 for removing Tl(I) from wastewater, characterized in that, The reaction temperature of the constant temperature oscillation is 25±0.2 ℃, the reaction time is 4 h, and the rotation speed is 250 r / min.

Images