Preparation method and application of iron-zinc co-doped graphene-like wastewater self-purification catalyst

Abstract

The invention provides a preparation method and application of an iron-zinc co-doped graphene-like wastewater self-purification catalyst, and the method comprises the following steps: dissolving an iron metal salt and a zinc metal salt in deionized water, adjusting the pH value with ammonia water to form a solution A, adding melamine, stirring to form a dispersion liquid B, adding an organic complexing agent, stirring to form a dispersion liquid B, and filtering to obtain the iron-zinc co-doped graphene-like wastewater self-purification catalyst. The preparation method comprises the following steps: uniformly mixing the raw materials, stirring in a water bath kettle until the raw materials are dried, drying in an air dry oven, uniformly grinding the obtained product and sodium bicarbonate, calcining, and grinding to obtain a black solid which is the Fe0-FexCy-C catalyst. The preparation method is simple and low in equipment requirement, and the prepared Fe0-FexCy-C catalyst can effectively and rapidly remove organic pollutants such as bisphenol, ciprofloxacin and sulfamethoxazole in water under the condition that an oxidizing agent is not added; the catalyst has an excellent removal effect on organic pollutants which are difficult to biodegrade under a neutral room temperature condition, and is high in stability and very low in metal ion dissolution rate.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of water treatment catalysts, and particularly relates to a preparation method and application of an iron-zinc co-doped graphene wastewater self-purification catalyst. Background Art

[0002] The problem of water pollution is becoming increasingly serious, posing a great threat to human health and the ecological environment. In addition to traditional pollutants, some emerging pollutants have attracted wide attention due to their unique properties and potential hazards. Among emerging pollutants, endocrine disruptors, antibiotics, etc. are typical new water pollutants, and their widespread presence and potential hazards in the environment have become the focus of research and treatment.

[0003] To address this challenge, advanced oxidation processes (AOPs) have emerged as an efficient wastewater treatment method. AOPs can effectively degrade various organic pollutants by generating highly oxidizing hydroxyl radicals ( · OH). Common AOPs include ozone oxidation (O3), photocatalytic oxidation using hydrogen peroxide (H3O3) and ultraviolet light (UV), Fenton reaction (Fenton), electrochemical oxidation, etc. These technologies perform well in treating refractory organic pollutants, but they also have significant limitations, especially high energy consumption and the need to add chemical agents, which increases the operating cost and the risk of secondary pollution. Therefore, the technology of driving the self-degradation of pollutants on the catalyst surface by constructing a strong enough electric field on the catalyst surface to activate dissolved oxygen in water has gradually attracted attention. It does not require the addition of other chemical agents and can treat organic pollutants in wastewater with low energy consumption, reducing the cost of wastewater treatment. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of existing advanced oxidation technologies and provide a preparation method and application of an iron-zinc co-doped graphene wastewater self-purification catalyst.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a preparation method of an iron-zinc co-doped graphene wastewater self-purification catalyst, and the method includes the following steps:

[0007] (1) Dissolve a certain amount of iron metal salt and zinc metal salt in deionized water, and adjust the pH of the solution with ammonia water to form solution A;

[0008] (2) Add a certain amount of melamine to solution A and stir for 30 min to form dispersion B;

[0009] (3) Add a certain amount of organic complexing agent to dispersion liquid B, stir for 1 h, then stir in a water bath at 80 °C until dry, and then dry in a forced-air drying oven for 12 h;

[0010] (4) Grind the product obtained in step (3) and a certain amount of sodium bicarbonate evenly and then dry;

[0011] (5) Place the product obtained in step (4) in a quartz crucible, calcine it in a tubular furnace under a nitrogen atmosphere, and then grind to obtain Fe 0 -Fe x C y @C catalyst.

[0012] The preparation method of the iron-zinc co-doped graphene-like wastewater self-purification catalyst of the present invention can be classified into a two-step synthesis method: the first step is a simple heating and stirring precipitation method, and the second step is a calcination method. The prepared Fe 0 -Fe x C y @C catalyst has excellent catalytic performance for the degradation of organic pollutants in water.

[0013] Preferably, in step (1), the iron metal salt is one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, iron acetate, iron sulfate, and iron acetylacetonate, etc.; the zinc metal salt is one of zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate, etc.; the pH of the solution is adjusted to 7-10, preferably 9.

[0014] Further, the iron metal salt is ferric chloride hexahydrate, and the zinc metal salt is anhydrous zinc chloride; the amount of substance of ferric chloride hexahydrate is 0.5-6 mmol, and the amount of substance of anhydrous zinc chloride is 2-10 mmol.

[0015] Further, the amount of substance of ferric chloride hexahydrate is 3 mmol; the amount of substance of anhydrous zinc chloride is 6 mmol.

[0016] Preferably, in step (2), the mass of melamine is 3-15 g, preferably 6 g.

[0017] Preferably, in step (3), the organic complexing agent includes one of dopamine hydrochloride, tannic acid, pyrazole, and glucosamine hydrochloride, etc., and the mass is 0.5-5 g.

[0018] Further, in step (3), the organic complexing agent is glucosamine hydrochloride, and the mass is 1.2 g.

[0019] Preferably, in step (4), the mass of sodium bicarbonate is 1-6 g, preferably 4 g.

[0020] Preferably, in step (5), the heating rate of the tubular furnace is 5 °C / min, the temperature is maintained at 500 - 900 °C, preferably 900 °C; the residence time is 2 - 5 hours, preferably 2 hours.

[0021] The present invention also provides an Fe 0 -Fe x C y @C catalyst.

[0022] The Fe 0 -Fe x C y @C catalyst prepared by the above method is a black solid powder; its microstructure is a bamboo-jointed porous material. The structural composition of this catalyst is mainly nitrogen-doped graphene-coated iron-zinc metal; in the catalyst of the present invention, the metal is tightly coated by the nitrogen-doped graphene framework, and the metal content detected on the material surface is very low, which makes the catalytic performance of iron-zinc metal more stable and not easily dissolved in the water body. The material has a large specific surface area and numerous voids, and the aqueous solution enters the interior of the material through the voids to contact the iron-zinc metal and undergo an interfacial reaction.

[0023] On the other hand, the present invention also provides an application of an Fe 0 -Fe x C y @C catalyst prepared according to the above method in the degradation of organic pollutants in water, including the following steps:

[0024] Disperse the Fe 0 -Fe x C y @C catalyst evenly in the water containing organic pollutants; the organic pollutants include at least one of bisphenols (including bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AF, bisphenol AP, etc.), ciprofloxacin (CIP), and sulfamethoxazole (SMZ).

[0025] The beneficial effects of the present invention are as follows:

[0026] (1) The present invention provides a preparation method and application of an iron-zinc co-doped graphene wastewater self-purification catalyst, the preparation method is simple, and the equipment requirements are low;

[0027] (2) The Fe 0 -Fe x C y @C catalyst prepared according to the preparation method provided by the present invention, metallic iron (including zero-valent iron and various valence states) is coated within the carbonized organic framework, mainly playing a role in regulating the internal electron distribution of the material. Zero-valent iron, as the active center, does not directly react with pollutants, and iron is non-consumable with a small dissolution amount;

[0028] (3) The Fe 0 -Fe x C y @C catalyst can effectively and rapidly remove organic pollutants such as bisphenols (including bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AF, bisphenol AP, etc.), ciprofloxacin (CIP), sulfamethoxazole (SMZ), etc. in water, and the removal rate can reach 80% in 5 minutes;

[0029] (4) The above-mentioned Fe 0 -Fe x C y @C catalyst can have a good removal effect on recalcitrant organic pollutants without adding any oxidants, has excellent stability, and the metal ion leaching rate is very low. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 XRD spectrum of the Fe 0 -Fe x C y @C catalyst prepared in the embodiment of the present invention.

[0031] Figure 2 High-magnification scanning electron microscope (SEM) image of the Fe 0 -Fe x C y @C catalyst prepared in the embodiment of the present invention.

[0032] Figure 3 Transmission electron microscope (TEM) image of the Fe 0 -Fe x C y @C catalyst prepared in the embodiment of the present invention and the distribution of elements C, N, O, Fe, and Zn in the catalyst.

[0033] Figure 4 Evaluation result diagram of the catalytic degradation activity of the Fe 0 -Fe x C y @C catalyst for three pollutants, BPA, CIP, and SMZ.

[0034] Figure 5 Evaluation result diagram of the catalytic degradation activity of the Fe 0 -Fe x C y @C catalyst for various bisphenol pollutants.

[0035] Figure 6 The Fe 0 -Fe x Cy Activity evaluation results diagram of the cyclic reuse of @C catalyst for the degradation of BPA. Detailed implementation manners

[0036] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0037] Example 1

[0038] As a preparation method of an iron-zinc co-doped graphene wastewater self-purification catalyst according to an embodiment of the present invention, the method includes the following steps:

[0039] (1) Weigh 0.811 g of ferric chloride hexahydrate and 0.818 g of anhydrous zinc chloride, dissolve them in 25 mL of deionized water, and adjust the pH of the solution to 9 with ammonia water to form solution A;

[0040] (2) Add 6 g of melamine to solution A and stir for 30 min to form dispersion B;

[0041] (3) Add 1.2 g of glucosamine hydrochloride to dispersion B, stir for 1 h, then stir in a water bath at 80 °C until dry, and then place it in a blast drying oven and dry for 12 h;

[0042] (4) Grind the product obtained in (3) and 4 g of sodium bicarbonate evenly and then dry.

[0043] (5) Place the solid obtained in (4) in a quartz crucible, use a tube furnace to adjust the heating rate to 5 °C / min under argon atmosphere, heat up to 900 °C, and stay for 2 hours. After calcination, grind to obtain the Fe 0 -Fe x C y @C catalyst.

[0044] Characterize the Fe 0 -Fe x C y @C catalyst prepared in this example.

[0045] Figure 1 XRD spectrum of the Fe 0 -Fe x C y @C catalyst prepared in Example 1. It is found that the characteristic diffraction peaks (110), (200), and (211) are consistent with those of elemental iron by comparison with the standard card.

[0046] Figure 2 XRD spectrum of the Fe 0 -Fe x C yScanning electron microscopy (SEM) image of the @C catalyst. It can be observed from the figure that it is a bamboo-shaped porous material.

[0047] Figure 3 Fe prepared in Example 1 0 -Fe x C y Transmission electron microscopy (TEM) image of the @C catalyst. Through elemental analysis, it is found that the black nanoparticles in the figure are mainly iron in terms of content, followed by zinc.

[0048] Example 2

[0049] As an application of the Fe 0 -Fe x C y @C catalyst in the degradation of organic pollutants in water, the method includes the following steps:

[0050] Put 0.03 g of the Fe 0 -Fe x C y @C catalyst into 50 mL of a 10 mg / L organic pollutant solution, start the degradation reaction with continuous stirring at a water bath temperature of 35 °C, and sample and measure the pollutant concentration at different time points.

[0051] The organic pollutants are respectively:,, bisphenol A (BPA), ciprofloxacin (CIP), and sulfamethoxazole (SMZ).

[0052] The results of the degradation rate are as Figure 4 shown, which are the degradation curves of the Fe 0 -Fe x C y @C catalyst for BPA, CIP, and SMZ. At 5 minutes, the removal rates of the three organic pollutants all exceeded 80%.

[0053] Example 3

[0054] As an application of the Fe 0 -Fe x C y @C catalyst in the degradation of organic pollutants in water, the method includes the following steps:

[0055] Put 0.02 g of the Fe 0 -Fe x C y @C catalyst into 50 mL of a 10 mg / L organic pollutant solution, start the degradation reaction with continuous stirring at a water bath temperature of 35 °C, and sample and measure the pollutant concentration at different time points.

[0056] The (bisphenol) organic pollutants are: bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AF, and bisphenol AP.

[0057] The results of the degradation rate are as Figure 5 shown, which are the degradation curves of Fe 0 -Fe x C y @C catalyst for bisphenol A, bisphenol F, bisphenol S, bisphenol B, bisphenol AF, and bisphenol AP. At 15 minutes, the removal rates of the above six organic pollutants all exceeded 80%.

[0058] Example 4

[0059] As an application of the Fe 0 -Fe x C y @C catalyst of the present invention in degrading organic pollutants in water, the stability exploration method includes the following steps:

[0060] (1) Put 0.03 g of the Fe 0 -Fe x C y @C catalyst prepared in Example 1 into 50 mL of 10 mg / L BPA solution, and start the degradation reaction with continuous stirring in a water bath at 35 °C;

[0061] (2) After reacting for 30 min, detect the concentration of BPA;

[0062] (3) After the reaction in step (2), separate and dry the Fe 0 -Fe x C y @C catalyst, and take the dried catalyst to repeat steps (1)-(3).

[0063] Figure 6 is the cyclic reuse activity evaluation diagram of the Fe 0 -Fe x C y @C catalyst for BPA degradation. It can be observed from the figure that the degradation effect of the prepared catalyst on BPA does not significantly decrease after continuous cyclic reactions. In 6 repeated experiments, the removal effect can reach more than 85%.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an iron-zinc co-doped graphene-like wastewater self-purification catalyst, characterized in that: The method is a two-step synthesis method: the first step is a heating and stirring precipitation method, and the second step is a calcination method; The specific steps include: (1) dissolving a certain amount of iron metal salt and zinc metal salt in deionized water, and adjusting the pH of the solution with aqueous ammonia to form solution A; (2) adding a certain amount of melamine to solution A and stirring for 30 minutes to form dispersion B; (3) Add a certain amount of organic complexing agent to dispersion B, stir for 1 hour, stir in a water bath at 80°C until dry, and then place in a forced air drying oven to dry for 12 hours; (4) grinding the product obtained in step (3) and a certain amount of sodium bicarbonate uniformly and then drying; (5) The product obtained in step (4) was placed in a quartz cup, calcined in a tubular furnace under nitrogen conditions, and ground to obtain Fe 0 -Fe x C y @C Catalyst.

2. The method according to claim 1, characterized in that The iron metal salt in step (1) is one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, ferric acetate, ferric sulfate and ferric acetylacetonate, and is preferably ferric chloride hexahydrate; The zinc metal salt is one of zinc nitrate, zinc chloride, zinc acetate and zinc sulfate, and is preferably zinc chloride; The amount of the ferric chloride hexahydrate substance is 0.5-6 mmol, and the amount of the anhydrous zinc chloride substance is 2-10 mmol; The pH of the solution is adjusted to 7-10, preferably 9.

3. The method according to claim 1, characterized in that The mass of melamine in step (2) is 3-15g.

4. The method according to claim 1, characterized in that The organic complexing agent in step (3) includes one of dopamine hydrochloride, tannic acid, pyrazole and glucosamine hydrochloride, preferably glucosamine hydrochloride; the mass of the organic complexing agent is 0.5-5g.

5. The method according to claim 1, characterized in that The mass of the sodium bicarbonate in step (4) is 1-6g.

6. The method according to claim 1, characterized in that In step (5), the heating rate of the tubular furnace is 5°C / min, the temperature is maintained at 500-900°C, and the residence time is 2-5 hours.

7. Fe prepared according to any one of claims 1 to 6 0 -Fe x C y @C Catalyst.

8. Fe according to claim 7 0 -Fe x C y @C Application of catalysts in degradation of organic pollutants in water.

9. Fe according to claim 8 0 -Fe x C y The application of @C catalyst in degrading organic pollutants in water includes the following steps: The Fe 0 -Fe x C y @C The catalyst is evenly dispersed in water containing organic pollutants; The organic pollutants include at least one of bisphenol pollutants, ciprofloxacin, and sulfamethoxazole.

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