A composite material of active carbon loaded with nano zero-valent iron and nano silver bimetal and a preparation method and application thereof

Abstract

The application discloses a kind of supported nanometer zero-valent iron and nanometer silver bimetallic activated carbon composite material and its preparation method and application: 1) take activated carbon powder and add acid solution to be stirred sufficiently, and acidification treatment is carried out to activated carbon, after solid-liquid separation, the obtained solid is washed with deionized water to pH value unchanged, then drying is carried out, and acidification treatment activated carbon is obtained;2) with volume percentage 30-60% ethanol aqueous solution as solvent, mixed solution, the concentration of iron nitrate nonahydrate is 66.5~335g / L, and the concentration of silver acetate is 0.8~5g / L, add acidification treatment activated carbon, mix evenly, after sufficient reaction, impregnate under vacuum condition at 25-85 DEG C for 7-13h, and obtain impregnated activated carbon;3) impregnated activated carbon is calcined under inert gas condition at 300-950 DEG C for 2-4h, and supported nanometer zero-valent iron and nanometer silver activated carbon composite material is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental pollution control materials, in particular to a composite material of loaded nano zero-valent iron and nano silver bimetallic activated carbon, and a preparation method and application thereof. BACKGROUND

[0002] Arsenic (As) pollution in water environment is a global environmental problem. Long-term drinking of water containing arsenic can cause cancer of skin, kidney, lung, bladder and other organs, or cause changes in human pigmentation, skin aging, nerve disorders, muscle atrophy, loss of appetite, nausea and other symptoms. Arsenic in water mainly exists in the form of trivalent (As 3+ , arsenite) and pentavalent (As 5+ , arsenate), and the toxicity of As(III) is greater than that of As(V). Currently, the removal techniques of arsenic in water mainly include ion exchange method, chemical precipitation method, membrane separation method, and adsorption method, etc. Among them, the adsorption method has the advantages of simple operation and good removal effect.

[0003] Activated carbon is a commonly used adsorption material for water pollution control, and is widely used in terminal water purification equipment for drinking water. It can effectively adsorb macromolecular organic matter and heavy metal cations in water body. However, due to the electronegativity and hydrophobicity of activated carbon, the adsorption effect of activated carbon on As(III) and other anions is poor. In addition, the adsorbed microorganisms on the surface of activated carbon can easily multiply and form a microbial membrane, causing secondary pollution to the water body. Therefore, it is imperative to modify activated carbon.

[0004] Activated carbon loaded with nano zero-valent iron combines the strong adsorption of activated carbon and the high surface reactivity of zero-valent iron, which is beneficial to enhance the adsorption of As(III). The addition of silver forms a bimetallic system with zero-valent iron, which can further improve the reactivity and accelerate the removal of pollutants. In addition, the high antibacterial effect of nano silver enhances the reliability of water purification.

[0005] Chinese patent application CN110559990A discloses a preparation method of zero-valent iron and silver loaded activated carbon. The method uses liquid phase reduction method, and sodium borohydride as a reducing agent to load zero-valent iron and silver on activated carbon. However, the crystallinity of zero-valent iron in the composite material obtained by this method is not high, and the loaded iron and silver may be easily lost during water purification. In addition, the iron and silver metal loaded by liquid phase reduction method is difficult to form a close combination with activated carbon, and the metal is easy to be lost into water, causing secondary pollution. SUMMARY

[0006] The application aims to provide a nanometer zero-valent iron and nanometer silver bimetallic activated carbon composite material, a preparation method and application thereof, to solve the problem of low arsenic removal efficiency of existing activated carbon, ensure the stability of the loaded material, reduce the loss of metal iron and silver, and avoid secondary pollution.

[0007] The first aspect of the application provides a preparation method of a nanometer zero-valent iron and nanometer silver bimetallic activated carbon composite material, comprising the following steps:

[0008] 1) Take activated carbon powder and add it to an acid solution for sufficient stirring to perform acidification treatment on the activated carbon, then perform solid-liquid separation, wash the obtained solid with deionized water until the pH value is unchanged, and then perform drying to obtain acidification-treated activated carbon;

[0009] 2) Take an ethanol aqueous solution with a volume percentage of 30-60% as a solvent, add iron nitrate nonahydrate and silver acetate to prepare a mixed solution, the concentration of the iron nitrate nonahydrate in the mixed solution is 66.5-335 g / L, and the concentration of the silver acetate is 0.8-5 g / L, take the prepared mixed solution and add it to the acidification-treated activated carbon in step 1), mix uniformly, perform sufficient reaction, then perform vacuum impregnation at 25-85°C for 7-13 h, perform cleaning, and perform drying to obtain impregnated activated carbon;

[0010] 3) Perform calcination on the impregnated activated carbon prepared in step 2) under inert gas conditions at 300-950°C for 2-4 h to obtain a nanometer zero-valent iron and nanometer silver activated carbon composite material.

[0011] Preferably, the particle size of the activated carbon powder in step 1) is 50-250 mesh; and the acid solution is a nitric acid solution with a concentration of 15-40%, preferably a nitric acid solution with a concentration of 25-35%.

[0012] The mass-volume ratio of the activated carbon to the acid solution is 1 g: 30-100 mL.

[0013] Preferably, the stirring time of the activated carbon powder in the acid solution in step 1) is 15-25 h, the obtained solid is washed with deionized water until the pH value is unchanged, and then the solid is dried at 90-110°C for 9-15 h after the solid-liquid separation.

[0014] Preferably, the particle size of the activated carbon powder in step 1) is 50-250 mesh, and the activated carbon is coconut shell activated carbon.

[0015] The concentration of the iron nitrate nonahydrate in the mixed solution in step 2) is 150-335 g / L, 180-335 g / L, 180-250 g / L, or 180-220 g / L, and the concentration of the silver acetate is 1.0-4 g / L, 1.5-4 g / L, 2-4 g / L, or 2-3 g / L.

[0016] Preferably, the volume ratio of the mixed solution to the activated carbon after acidification treatment in step 2) is 10-20 mL: 1 g, the mixed solution and the activated carbon are mixed and stirred at room temperature for 1.5-3 h, vacuum impregnation is performed in a 75℃ vacuum drying oven for 8-12 h, the impregnated activated carbon is washed with deionized water and anhydrous ethanol for 2-4 times respectively, and is dried at 55-65℃ for 20-28 h.

[0017] Preferably, the calcination in step 3) is performed at 300-950℃ for 2.5-3.5 h, preferably at 850-950℃ for 2.8-3.2 h.

[0018] Preferably, the impregnated activated carbon prepared in step 2) is placed in a tube furnace, and is calcined at 850-950℃ with a temperature rising rate of 8-12℃ / min under the condition of a nitrogen flow of 65-105 mL / min.

[0019] The second aspect of the present application provides a composite material of activated carbon loaded with nano zero-valent iron and nano silver bimetal, which is prepared by any of the above preparation methods.

[0020] The third aspect of the present application provides an application of the above composite material of activated carbon loaded with nano zero-valent iron and nano silver bimetal in removing As pollution in the environment.

[0021] The application is preferably an application of the composite material of activated carbon loaded with nano zero-valent iron and nano silver bimetal in removing As(III) pollution in the water environment.

[0022] Preferably, the concentration of As(III) in the wastewater to be treated is 0.1-200 mg / L, the dosage of the composite material is 0.5-2.0 g / L, and preferably the dosage is 0.8-1.3 g / L; the composite material is put in and adsorbed for more than 6 h, preferably more than 8 h, and further preferably for 8-20 h or 8-15 h.

[0023] The present application has the following advantages:

[0024] 1. The nano zero-valent iron and nano silver on the surface of the composite material of activated carbon loaded with nano zero-valent iron and nano silver have good crystallinity, and the addition of silver helps to reduce the size of the zero-valent iron and prevent significant aggregation. The composite material has a large specific surface area, strong reactivity, and strong adaptability; has a fast adsorption rate and high removal efficiency; is non-toxic and recyclable; has stable metal loading and low loss, and will not cause secondary pollution to the water body.

[0025] 2. The composite material of activated carbon loaded with nano zero-valent iron and nano silver has simple preparation steps, short preparation time, does not use chemical reducing agents, and has low cost, which has the potential for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the specific surface area of the composite material prepared in Example One calculated using the BET six-point method.

[0027] Figure 2 is the XRD pattern of the composite material prepared in Example One.

[0028] Figure 3 is the SEM pattern of the composite material prepared in Example One.

[0029] Figure 4 is the specific surface area of the composite material prepared in Example Two calculated using the BET six-point method.

[0030] Figure 5 is the XRD pattern of the composite material prepared in Example Two.

[0031] Figure 6 is the SEM pattern of the composite material prepared in Example Two.

[0032] Figure 7 is the specific surface area of the composite material prepared in Example Three calculated using the BET six-point method.

[0033] Figure 8 is the XRD pattern of the composite material prepared in Example Three.

[0034] Figure 9 is the SEM pattern of the composite material prepared in Example Three.

[0035] Figure 10 is the specific surface area of the composite material prepared in Example Four calculated using the BET six-point method.

[0036] Figure 11 is the XRD pattern of the composite material prepared in Example Four.

[0037] Figure 12 is the SEM pattern of the composite material prepared in Example Four.

[0038] Figure 13 is the XRD pattern of the composite material prepared in Example Five.

[0039] Figure 14 is the XRD pattern of the composite material prepared in Example Six.

[0040] Figure 15 is the high resolution xps peak fitting pattern of As 3d orbitals in the composite material after the composite material of Example Three treated As(III) solution.

[0041] Figure 16The removal effect of As(III) of the composite materials prepared in Examples 1 to 6 and untreated raw activated carbon is compared.

[0042] Figure 17 The silver loss amount analysis chart in the water purification process of the composite materials prepared in Examples 2 to 6. DETAILED DESCRIPTION

[0043] The application will be further described in conjunction with the examples, but the application is not limited by the examples.

[0044] In the following examples, the experimental methods are conventional methods unless otherwise specified.

[0045] Main materials and reagent sources:

[0046] Activated carbon: coconut shell activated carbon, purchased from Fujian Xinsen Carbon Co., Ltd. (particle size of about 200 mesh) Product parameters: BET specific surface area 903.512 m 2 / g, ash content ≤7%, and pH of 6-10.

[0047] 30wt% nitric acid solution: dilute 68% nitric acid (AR) to 30% with deionized water.

[0048] Iron nitrate nonahydrate: Fe(NO3)3·9H2O, CAS#7782-61-8.

[0049] Silver acetate: CAS#563-63-3.

[0050] Example 1, composite material of activated carbon loaded with nano zero-valent iron

[0051] A preparation method of a composite material of activated carbon loaded with nano zero-valent iron, according to the following steps:

[0052] 1) Screen the activated carbon with a particle size of 200 mesh, and add it to a 30wt% nitric acid solution at a solid-liquid ratio of 1g:50mL, stir for 20h, filter, then wash with deionized water until the pH value is constant, and dry at 105℃ for 12h to obtain the acid-treated activated carbon.

[0053] 2) Mix anhydrous ethanol and ultrapure water at a volume ratio of 1:1 to obtain a solvent, add iron nitrate nonahydrate to prepare a solution with a concentration of 200g / L of iron nitrate nonahydrate, take 30mL of the prepared iron nitrate nonahydrate solution, add 2g of the acid-treated activated carbon of step 1), mix uniformly, fully stir at 25℃ for 2h, vacuum impregnate in a 75℃ vacuum drying oven for 10h, wash with deionized water and anhydrous ethanol for 3 times respectively, and dry at 60℃ for 24h to obtain the impregnated activated carbon.

[0054] 3) The impregnated activated carbon prepared in step 2) is placed in a tube furnace and calcined at 900℃ for 3h at a temperature rising rate of 10℃ / min under the condition of nitrogen flow of 75mL / min, to obtain the composite material of activated carbon loaded with nano zero-valent iron and nano silver.

[0055] Figure 1 The specific surface area of the composite material prepared in this example is 623.186m 2 / g, measured by BET six-point method.

[0056] Figure 2 The XRD pattern of the composite material prepared in this example, the activated carbon composite material prepared in this example is loaded with nano zero-valent iron with high crystallinity.

[0057] Figure 3 The SEM pattern of the composite material prepared in this example, in the composite material prepared in this example, nano zero-valent iron is aggregated in spherical form on the surface and in the pores of activated carbon, and the particle size of most nano zero-valent iron particles is between 200-300nm.

[0058] Example Two, Composite Material of Activated Carbon Loaded with Nano Zero-Valent Iron and Nano Silver

[0059] A method for preparing a composite material of activated carbon loaded with nano zero-valent iron and nano silver, according to the following steps:

[0060] 1) Activated carbon with particle size of 200 mesh is selected and added to a 30wt% nitric acid solution at a solid-liquid ratio of 1g:50mL, stirred (180r / min) for 20h, then filtered, washed with deionized water until the pH value is constant, and dried at 105℃ for 12h, to obtain acid-treated activated carbon.

[0061] 2) Anhydrous ethanol and ultrapure water are mixed at a volume ratio of 1:1 to serve as a solvent, and iron nitrate nonahydrate and silver acetate are added to prepare a mixed solution, the concentration of iron nitrate nonahydrate in the mixed solution is 66.5g / L, and the concentration of silver acetate is 2g / L, 30mL of the prepared mixed solution is added to 2g of the acid-treated activated carbon of step 1), mixed uniformly, and stirred at 25℃ for 2h, then placed in a 75℃ vacuum drying oven for vacuum impregnation for 10h, washed with deionized water and anhydrous ethanol for 3 times respectively, and dried at 60℃ for 24h, to obtain impregnated activated carbon.

[0062] 3) The impregnated activated carbon prepared in step 2) is placed in a tube furnace and calcined at 900℃ for 3h at a temperature rising rate of 10℃ / min under the condition of nitrogen flow of 75mL / min, to obtain the composite material of activated carbon loaded with nano zero-valent iron and nano silver.

[0063] Figure 4is the composite material of low-nanometer zero-valent iron and nanometer silver supported activated carbon prepared in the present example. The specific surface area of the composite material is 586.752 m2 / g measured by BET six-point method. 2 / g.

[0064] Figure 5 is the XRD pattern of the composite material prepared in the present example. The activated carbon composite material prepared in the present example is loaded with nanometer zero-valent iron and nanometer elemental silver of high crystallinity.

[0065] Figure 6 is the SEM pattern of the composite material prepared in the present example. In the composite material prepared in the present example, nanometer zero-valent iron and nanometer silver are uniformly dispersed on the surface and in the pores of activated carbon in spherical form. The particle size of most nanometer zero-valent iron and nanometer silver is between 10-30 nm. The addition of silver significantly reduces the particle size.

[0066] Example Three-Eight

[0067] A composite material of nanometer zero-valent iron and nanometer silver supported activated carbon is prepared. The preparation method has the same steps as Example Two, except that the concentration of iron nitrate nonahydrate and silver acetate in the mixed solution prepared in step 2) is different, and the calcination temperature in step 3) is different. The preparation steps of the composite material in Examples One to Eight have specific process parameters as shown in Table 1:

[0068] Table 1

[0069]

[0070]

[0071] Figures 7-9 is the characterization pattern of the composite material of Example Three: Figure 7 is the composite material of low-nanometer zero-valent iron and nanometer silver supported activated carbon prepared in the present example. The specific surface area of the composite material is 586.752 m2 / g measured by BET six-point method. 2 / g. Figure 8 is the XRD pattern of the composite material prepared in the present example. The activated carbon composite material prepared in the present example is loaded with nanometer zero-valent iron and nanometer elemental silver of high crystallinity. Figure 9 is the SEM pattern of the composite material prepared in the present example. In the composite material prepared in the present example, nanometer zero-valent iron and nanometer silver are uniformly dispersed on the surface and in the pores of activated carbon in spherical form. The particle size of most nanometer zero-valent iron and nanometer silver is between 10-30 nm. The addition of silver significantly reduces the particle size.

[0072] Figures 10-12 is the characterization pattern of the composite material of Example Four: Figure 10The specific surface area of the composite material prepared in this embodiment is 357.142 m2 / g, which is measured by BET six-point method. 2 / g. Figure 11 The XRD pattern of the composite material prepared in this embodiment is shown in the figure. The composite material prepared in this embodiment is loaded with nanometer zero-valent iron and nanometer elemental silver with high crystallinity. Figure 12 The SEM image of the composite material prepared in this embodiment is shown in the figure. In the composite material prepared in this embodiment, nanometer zero-valent iron and nanometer silver are aggregated in the form of spheres on the surface and in the pores of the activated carbon, and the particle size of most of the nanometer zero-valent iron and nanometer silver is between 10-30 nm.

[0073] Figure 13 The XRD pattern of the composite material prepared in Example Five is shown in the figure. It can be seen from the figure that the composite material is loaded with ferroferric oxide and diiron trioxide.

[0074] Figure 14 The XRD pattern of the composite material prepared in Example Six is shown in the figure. It can be seen from the figure that the composite material is loaded with ferroferric oxide with high crystallinity.

[0075] The composite materials prepared in Examples One to Eight were preliminarily detected for their removal performance on As(III). An As(III) solution with a concentration of 10.0 mg / L to be treated was prepared, and the composite materials prepared in Examples One to Eight were added to the solution respectively, the composite material dosage was 1.0 g / L, the solution pH was 7.0, T was 25±1℃, and the adsorption time was 8 h. After the adsorption time, the total arsenic content in the treated solution was measured by inductively coupled plasma optical emission spectrometer (ICP-OES), the arsenic removal amount in the solution was calculated, and the results are shown in Table 1. The removal amount results in Table 1 represent the amount of arsenic removed per gram of composite material (mg / g) after the initial concentration of 10.0 mg / L As(III) solution was treated. It can be seen from the results in Table 1 that the arsenic removal amount of the composite material prepared at a calcination temperature of 900℃ is significantly higher than that of the composite material prepared at a calcination temperature of 300℃ and 600℃; and under the condition of a certain silver acetate concentration, a too low concentration of iron nitrate nonahydrate (66.5 g / L) will cause a significant decrease in the arsenic removal amount of the composite material.

[0076] The composite material after adsorbing the initial concentration of 10 mg / L As(III) solution was characterized by xps, and the high-resolution xps peak fitting results of the As3d orbit of the material are shown in Figure 15 The results show that arsenic exists in the form of pentavalent arsenic on the reacted composite material, indicating that the prepared composite material oxidizes As(III) to As(V).

[0077] Example Nine, Removal Performance of Composite Material on As(III) in Water

[0078] Static adsorption experiments were conducted to investigate the removal performance of the composite materials prepared in Examples 1 to 6 for different concentrations of As(III) in aqueous solution. The experimental conditions were: composite material dosage 1.0 g / L, solution pH 7.0, T 25 ± 1 °C, and adsorption time 8 h for all samples. After the adsorption time, the total arsenic content in the treated solution was determined using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0079] Figure 16 This is a comparison chart showing the removal efficiency of As(III) by the composite materials prepared in Examples 1 to 6 and the untreated original activated carbon. Figure 16 The x-axis represents the solutions to be treated with different As(III) concentrations, and the y-axis represents the amount of arsenic removed per gram of the composite material (mg / g). Unmodified coconut shell activated carbon adsorbed <2 mg / g of As(III), while the composite material of nano-zero valent iron and nano-silver bimetallic activated carbon adsorbed over 60 mg / g of As(III) under the same conditions. Calculations showed that the arsenic removal rate for an initial As(III) concentration of 5 mg / L was as high as 100%, significantly improving the removal efficiency compared to untreated activated carbon. Furthermore, the removal amount of As(III) was further improved compared to nano-zero valent iron-loaded activated carbon. Figure 15 It can be seen that the concentration of ferric nitrate nonahydrate in the mixed solution in step 2) and the calcination temperature in step 3) have a significant impact on the As(III) removal effect of the composite material. When the calcination temperature is 300℃ and 600℃, under the same concentration of ferric nitrate nonahydrate and silver acetate, the amount of As(III) removed by the composite material is lower than that when the calcination temperature is 900℃. When the concentration of ferric nitrate nonahydrate is lower (Example 2), the amount of As(III) removed by the composite material is lower than that when the concentration of ferric nitrate nonahydrate is lower. When the concentration of ferric nitrate nonahydrate increases (Example 3), the amount of As(III) removed by the composite material increases. The composite material in Example 3 has the highest amount of As(III) removed. However, when the concentration of ferric nitrate nonahydrate increases to a certain amount, the amount of As(III) removed by the composite material decreases (Example 4).

[0080] Combination Figures 1-14 As can be seen, the main crystalline phases of the samples prepared at different temperatures differ from each other. For the sample heated to 300℃, the peak of iron oxide (Fe2O3) is dominant; for the sample heated to 600℃, magnetite (Fe3O4) is dominant; at 900℃, the peak of iron oxide essentially disappears and is replaced by elemental iron (Fe2O3). 0 The peak corresponding to this temperature replaces the α-Fe, and samples prepared at or above this temperature mainly contain α-Fe. 0 Ag appeared at a temperature of 900℃ 0characteristic peak, indicating Ag 0 was present at this preparation temperature, meaning that when the preparation temperature was 900℃, Fe 0 and Ag 0 were present at the same time. The high reactivity characteristics of zero-valent iron and the coordination of iron-silver bimetallic were fully exerted at this preparation temperature, achieving the effect of high-efficiency arsenic removal.

[0081] The XRD pattern of the composite material prepared in step 2) with different concentrations of Fe(NO3)3·9H2O (900℃) is shown in the figure. It can be seen from the figure that there is a clear diffraction peak at 2θ = 44.67°, two relatively strong diffraction peaks at 65.02° and 82.39°. These three peaks correspond to the (110), (200) and (211) crystal faces of cubic crystal α-Fe 0 (PDF #87-0721), the diffraction peak at 2θ = 44.67° is strong and narrow, indicating that the zero-valent iron particles loaded on the activated carbon have good crystallinity. Moreover, as the concentration of Fe(NO3)3·9H2O in the mixed solution increases, the characteristic peak becomes more obvious. In addition, the Fe2O3 diffraction peak at 2θ = 43.61° becomes smaller and disappears as the concentration of Fe(NO3)3·9H2O in the mixed solution increases. When the concentration of Fe(NO3)3·9H2O in the mixed solution increases to 200 g / L, the iron in the material almost exists in the form of α-Fe 0 , the content of zero-valent iron increases, which is beneficial to increase the removal amount of arsenic. However, when the concentration of Fe(NO3)3·9H2O in the mixed solution further increases, although the loading amount of zero-valent iron is further increased, it also leads to a further decrease in the specific surface area (S BET ) of AC, and the increase in the number of loaded particles leads to the blockage of the pore channels of activated carbon, which reduces the physical adsorption and mass transfer efficiency of activated carbon and leads to a decrease in the arsenic removal performance. This is also proved by the scanning electron microscopy (SEM) characterization results. When the concentration of Fe(NO3)3·9H2O in the mixed solution increases to 333.3 g / L, the pore channels of activated carbon are seriously blocked. As can be seen from the scanning electron microscopy (SEM) characterization, the zero-valent iron on the surface of the activated carbon in Example One is seriously aggregated, the particle size is large, and the pore channels of activated carbon are almost completely occupied. Compared with the activated carbon composite material loaded with single zero-valent iron, the addition of a small amount of silver in Example Three significantly reduces the particle size of nano zero-valent iron, and the particles are uniformly distributed and not aggregated, which effectively avoids the phenomenon of particle aggregation and blockage of the pore channels, which increases the contact area between the pollutants and the metals on the surface of activated carbon, and also ensures the integrity of the porous structure of activated carbon, which does not affect the adsorption and mass transfer.

[0082] Example Ten, Study on the Anti-silver Loss Performance of the Composite Material in Water Purification

[0083] The embodiment is to study the anti-silver loss performance of the nanoscale zero-valent iron and nanosilver double-metal active carbon composite material in the water purification process, so as to ensure the safety and reliability of water purification.

[0084] In the constant temperature oscillation test, the composite material with a dosage of 1.0 g / L is added to deionized water, and the silver concentration in the water is detected at T=25±1℃ under the conditions of 0.1d, 0.5d, 1d, 2d, 3d, 4d, 5d, 6d, 7d. The total silver content in the treated solution is determined by inductively coupled plasma optical emission spectrometer (ICP-OES).

[0085] Figure 17 The silver loss amount analysis chart of the composite material prepared in examples 2 to 6 in the water purification process can be seen from the chart. The silver loss amount of the nanoscale zero-valent iron and nanosilver double-metal active carbon composite material prepared in examples 2 to 4 increases rapidly in the first 3d water purification process, but the maximum elution amount is not more than 5 μg / L, and the silver concentration in the solution does not increase after 3d water purification, and the silver in the material is no longer eluted. Compared with the active carbon loaded with iron oxide and metal silver prepared in examples 5 and 6, the silver outflow amount is greatly reduced, indicating that the composite material is safe and reliable for water purification. The silver loss amount of the composite material of examples 5 and 6 with low calcination temperature is high.

Claims

1. Application of a composite material of loaded nano zero-valent iron and nano silver bimetallic activated carbon in removing As pollution in the environment, characterized in that: The preparation method of the composite material of the active carbon loaded with nano zero-valent iron and nano silver bimetallic material comprises the following steps: ​ 1) acidification treatment of the active carbon powder by adding the active carbon powder into an acid solution and stirring thoroughly, washing the obtained solid with deionized water until the pH value is constant, and then drying to obtain the acid-treated active carbon; 2) preparation of a mixed solution by adding iron nitrate nonahydrate and silver acetate into an ethanol aqueous solution with a volume percentage of 30-60%, the concentration of the iron nitrate nonahydrate in the mixed solution being 200 g / L and the concentration of the silver acetate being 2-4 g / L, adding the prepared mixed solution into the acid-treated active carbon obtained in step 1), the ratio of the amount of the mixed solution to the amount of the acid-treated active carbon being 10-20 mL:1 g, mixing uniformly, and then impregnating at 25-85 ℃ under vacuum for 7-13 h after sufficient reaction, washing, and drying to obtain the impregnated active carbon; 3) calcination of the impregnated active carbon obtained in step 2) at 900 ℃ under inert gas for 2-4 h to obtain the composite material of the active carbon loaded with nano zero-valent iron and nano silver bimetallic material.

2. Use according to claim 1, characterized in that: In step 1), the particle size of the active carbon powder is 50-250 mesh; the acid solution is a nitric acid solution with a concentration of 15-40%; and the mass-volume ratio of the active carbon to the acid solution is 1 g:30-100 mL.

3. Use according to claim 1 or 2, characterized in that: In step 1), the active carbon powder is stirred in the acid solution for 15-25 h, and then the obtained solid is washed with deionized water until the pH value is constant, and then dried at 90-110 ℃ for 9-15 h.

4. Use according to claim 1, characterized in that: In step 1), the active carbon is coconut shell active carbon.

5. The use according to claim 1, characterized in that: In step 2), the mixed solution and the active carbon are mixed and stirred at room temperature for 1.5-3 h, vacuum impregnated in a vacuum drying box at 75 ℃ for 8-12 h, washed with deionized water and anhydrous ethanol for 2-4 times respectively, and dried at 55-65 ℃ for 20-28 h to obtain the impregnated active carbon.

6. Use according to claim 1, characterized in that: In step 3), the calcination is performed at 900 ℃ for 2.5-3.5 h.

7. Use according to claim 1, characterized in that: In step 3), the impregnated active carbon obtained in step 2) is placed in a tube furnace, and heated to 900 ℃ at a heating rate of 8-12 ℃ / min under the condition that the nitrogen flow is 65-105 mL / min.

8. The use according to claim 1, characterized in that: The composite material of the active carbon loaded with nano zero-valent iron and nano silver bimetallic material is used for removing As(III) pollution in a water environment, the concentration of As(III) in the wastewater to be treated is 0.1-200 mg / L, the dosage of the composite material is 0.5-2.0 g / L, and the composite material is allowed to adsorb for more than 6 h after being put into the wastewater.

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