Synthesis method and application of iron-aluminum co-doped catalyst

Abstract

The application discloses a kind of synthesis method and application of iron-aluminum co-doped catalyst, and its characteristics include the following steps: S1: aluminum metal salt and iron metal salt are dissolved in beaker containing deionized water, to obtain solution A;S2: phosphorus source is added to solution A, adjust pH, form suspension B;S3: biomass is added to suspension B and stirred for 30 min, to obtain solution C;S4: nitrogen source is added to solution C, the beaker is placed in water bath and dried;The obtained dry product is mixed with activating agent and then calcined under inert gas to obtain catalyst crude product;S5: catalyst crude product is ground, then washed with ethanol and deionized water, vacuum dried, to obtain iron-aluminum co-doped catalyst.The preparation method is simple, and the equipment requirement is low.The application discloses a new type of nitrogen-doped carbon-coated zero-valent iron nanoparticle catalyst, which can degrade pollutants by electron transfer between pollutants and catalyst without adding any oxidant.Under neutral room temperature conditions, the degradation of difficult biodegradable organic pollutants has good removal effect, and has good stability, and the iron ion dissolution rate is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of water treatment, and particularly relates to a synthesis method and application of an iron-aluminum co-doped catalyst. BACKGROUND

[0002] In recent years, emerging pollutants, such as antibiotics, drugs, personal care products, artificial sweeteners and endocrine disruptor chemicals, are widely detected in wastewater from pharmaceutical, dye, pesticide, papermaking and plastic industries. Even after treatment in sewage treatment plants, the concentration of emerging pollutants in water can reach ng / L to μg / L. Studies have shown that the concentration of emerging pollutants in untreated water in Asian regions is higher than that in some countries in Europe and North America. Extensive experiments have proved that the presence of these substances has adverse effects on aquatic ecosystems and human health. For example, antibiotics are widely used in the treatment of diseases in humans and animals. Through the vicious cycle of transformation and biological accumulation, antibiotics persist in the environment and spread widely through natural water systems. Antibiotic exposure promotes the generation of bacterial resistance, changes many basic physiological balances and promotes long-term diseases. At present, advanced oxidation technology has high processing cost, and biological treatment has poor effect and can produce antibiotic-resistant genes, which is harmful. Therefore, it is urgent to develop a low-energy and high-efficiency technology to treat organic pollutants in wastewater, reduce wastewater treatment cost and reduce the generation of antibiotic-resistant genes. SUMMARY

[0003] The present application aims to provide a synthesis method and application of an iron-aluminum co-doped graphene wastewater self-purification catalyst. The method uses cyclodextrin as an organic ligand, iron chloride hexahydrate as an iron source and urea as a nitrogen source to synthesize a precursor by copolymerization, and then synthesizes the target catalyst by pyrolysis under a nitrogen atmosphere.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] 1. A synthesis method of an iron-aluminum co-doped catalyst, comprising the following steps:

[0006] S1: dissolving an aluminum metal salt and an iron metal salt in a beaker containing deionized water to obtain a solution A;

[0007] S2: adding a phosphorus source to the solution A, adjusting the pH, and forming a suspension B;

[0008] S3: adding biomass to the suspension B and stirring for 30 min to obtain a solution C;

[0009] S4: adding a nitrogen source to the solution C, placing the beaker in a water bath to dry, mixing the obtained dry product with an activating agent, and then calcining under an inert gas to obtain a catalyst crude product;

[0010] S5: grinding the catalyst crude product, washing with ethanol and deionized water, vacuum drying to obtain the iron-aluminum co-doped catalyst.

[0011] Further, the metal iron salt in step S1 includes one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, ferric acetate, ferric sulfate and acetylacetone iron, with a mass of 0.5-3g; the metal aluminum salt includes one of aluminum chloride, aluminum nitrate and aluminum sulfate, and the molar ratio of iron to aluminum is (1-6):1.

[0012] Preferably, the metal iron salt is ferric chloride hexahydrate; and the metal aluminum salt is aluminum chloride.

[0013] Further, the phosphorus source in step S2 includes one of phosphate, phytic acid and triphenylphosphine, with a mass of 0.1-1g.

[0014] Preferably, the phosphate is sodium dihydrogen phosphate, sodium phosphate or the like, and is preferably phytic acid.

[0015] Further, the biomass in step S3 includes one of chitosan, cyclodextrin and corn cob, with a mass of 0.5-3g.

[0016] Preferably, the biomass is preferably cyclodextrin.

[0017] Further, the nitrogen in step S4 includes one of urea, melamine, dicyanediamine or the like, with a mass of 1-16g; and the activator includes one of zinc chloride, sodium bicarbonate and potassium hydroxide.

[0018] Preferably, the nitrogen is preferably urea, and the activator is preferably potassium hydroxide.

[0019] Further, in step S5, the solid product that is uniformly ground is calcined in a tube furnace under the protection of an inert gas, nitrogen, at a calcination temperature of 700-1000℃, a calcination time of 1-5h, a calcination temperature rising rate of 5℃ / min, and after natural cooling, the catalyst is obtained.

[0020] Preferably, the calcination temperature is 800℃, and the calcination time is 2h.

[0021] Further, in step S5, the washing process is performed using one of deionized water and anhydrous ethanol; the drying temperature is 30-60℃, and the drying time is 6-24h.

[0022] Preferably, the washing is performed three times, and the drying time is 24h.

[0023] The Fe0-FexOy(Al)@NC self-degradation catalyst is prepared according to the method of any one of claims 1-7.

[0024] The application of the Fe0-FexOy(Al)@NC self-degradation catalyst in claim 8 in degrading organic pollutants in water.

[0025] Further, the organic pollutants include one or more than two of BPA, 2,4-DCP, CIP, SMZ and TC.

[0026] Advantages

[0027] (1) The catalyst of the present application has good removal efficiency for organic pollutants in water without additional hydrogen peroxide, light and other experimental conditions in the experimental system.

[0028] (2) The catalyst of the present application has good removal efficiency for degradation of difficult biodegradable organic pollutants at neutral room temperature.

[0029] (3) The catalyst of the present application does not produce solid foreign matters such as iron mud during the reaction, and does not need foreign matter removing device.

[0030] (4) The present application has good stability in removing organic pollutants, and low metal ion leaching.

[0031] (5) The catalyst of the present application is a solid catalyst, which is easy to separate from water and recycle. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 、 2 SEM image of Fe 0 -Fe x O y (Al)@NC prepared in the examples.

[0033] Figure 3 XRD spectrum of Fe 0 -Fe x O y (Al)@NC prepared in the examples.

[0034] Figure 4 Degradation curve of Fe 0 -Fe x O y (Al)@NC for CIP, TC, CIP, SMZ, LEV, SMX and BPA, 2,4-DCP.

[0035] Figure 5 Fe Figure 4 Fe 0 -Fe x O y (Al)@NC, Fe 0 -Fex O y @NC, (Al)@NC, NC degradation curve of CIP;

[0036] Figure 6 Fe 0 -Fe x O y (Al)@NC repeated experiment activity evaluation diagram;

[0037] Figure 7 Fe 0 -Fe x O y (Al)@NC loaded on zeolite, continuous flow device residence time is 1 hour, repeated experiment activity evaluation diagram of continuous operation for 15 days;

[0038] Figure 8 Fe 0 -Fe x O y (Al)@NC loaded on zeolite, continuous flow device residence time is changed to 2h at the sixteenth day, repeated experiment activity evaluation diagram of continuous operation for 15 days. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] Embodiment: Preparation, characterization and application experiment of a Fe-Al co-doped graphene-like wastewater self-purification catalyst.

[0041] I. Preparation

[0042] Two materials will be prepared in this example, including a Fe 0 -Fe x O y (Al)@NC, Fe 0 -Fe x O y @NC and Al@NC and substrate material NC.

[0043] Fe 0 -Fe x O y (Al)@NC

[0044] (1) 1 g of iron chloride hexahydrate, 0.23317 g of aluminum chloride hexahydrate were dissolved in a beaker containing deionized water to obtain solution A;

[0045] (2) 0.5 g of phytic acid was added to solution A, and the pH was adjusted to 7 to form suspension B;

[0046] (3) 2 g of cyclodextrin was added to suspension B and stirred for 30 min;

[0047] (4) After 8 g of urea was added to the above solution, the beaker was placed in a water bath for drying;

[0048] (5) The obtained dried product was mixed with 1 g of potassium hydroxide, and then calcination was carried out in a tube furnace under the protection of nitrogen: the calcination temperature was 800°C, the calcination time was 2 h, the heating rate of calcination was 5°C / min, and the catalyst was obtained after natural cooling.

[0049] (6) The self-purification catalyst after natural cooling was washed with deionized water and ethanol for 2-3 times, and then was placed in a vacuum oven at 60°C for drying.

[0050] Comparative Example 1

[0051] Fe@NC was prepared according to the following steps: 0 -Fe x O y @NC

[0052] (1) 1 g of iron chloride hexahydrate was dissolved in a beaker containing deionized water to obtain solution A;

[0053] (2) 0.5 g of phytic acid was added to solution A, and the pH was adjusted to 7 to form suspension B;

[0054] (3) 2 g of cyclodextrin was added to suspension B and stirred for 30 min;

[0055] (4) After 8 g of urea was added to the above solution, the beaker was placed in a water bath for drying;

[0056] (5) The obtained dried product was mixed with 1 g of potassium hydroxide, and then calcination was carried out in a tube furnace under the protection of nitrogen: the calcination temperature was 800°C, the calcination time was 2 h, the heating rate of calcination was 5°C / min, and the catalyst was obtained after natural cooling.

[0057] (6) The self-purification catalyst after natural cooling was washed with deionized water and ethanol for 2-3 times, and then was placed in a vacuum oven at 60°C for drying.

[0058] Comparative Example 2

[0059] (Al)@NC was prepared according to the following steps:

[0060] (1) 0.23317 g of aluminum chloride hexahydrate was dissolved in a beaker containing deionized water to obtain solution A;

[0061] (2) 0.5 g of phytic acid was added to solution A, and the pH was adjusted to 7 to form suspension B;

[0062] (3) 2 g of cyclodextrin was added to suspension B and stirred for 30 min;

[0063] (4) After 8 g of urea was added to the above solution, the beaker was placed in a water bath for drying;

[0064] (5) After the obtained dried product was mixed with 1 g of potassium hydroxide, calcination was carried out in a tube furnace under the protection of nitrogen: the calcination temperature was 800°C, the calcination time was 2 h, the temperature rising rate of calcination was 5°C / min, and the self-purification catalyst was obtained after natural cooling.

[0065] (6) The self-purification catalyst after natural cooling was washed with deionized water and ethanol for 2-3 times, and then was placed in a vacuum oven at 60°C for drying.

[0066] Comparative Example 3

[0067] The NC was prepared according to the following steps

[0068] (1) 0.5 g of phytic acid was added to solution A, and the pH was adjusted to 7 to form suspension B;

[0069] (2) 2 g of cyclodextrin was added to suspension B and stirred for 30 min;

[0070] (3) After 8 g of urea was added to the above solution, the beaker was placed in a water bath for drying;

[0071] (4) After the obtained dried product was mixed with 1 g of potassium hydroxide, calcination was carried out in a tube furnace under the protection of nitrogen: the calcination temperature was 800°C, the calcination time was 2 h, the temperature rising rate of calcination was 5°C / min, and the self-purification catalyst was obtained after natural cooling.

[0072] (5) The self-purification catalyst after natural cooling was washed with deionized water and ethanol for 2-3 times, and then was placed in a vacuum oven at 60°C for drying.

[0073] II. Characterization

[0074] Figure 1 The Fe 0 -Fe x O y Low-magnification scanning electron microscope (SEM) image of the (Al)@NC. As can be seen from the figure, the catalyst has a scale-like porous structure. Figure 2Fe 0 -Fe x O y X-ray diffraction (XRD) patterns of (Al)@NC, which can determine the degree of graphitization and crystal structure of the biochar catalyst. In the figure, for the sample NC without Fe doping, the peak at 2θ = 24.2° corresponds to the peak of the carbon (002) crystal plane, while Fe 0 -Fe x O y The characteristic carbon (002) peak of (Al)@NC moves to 25.8°, and the peak shape becomes sharper, indicating that the introduced Fe enters the structure of the base material, changing the surface characteristics of the catalyst. Compared with the standard card, it is found that Fe 0 -Fe x O y Fe0, Fe3O4, etc. may be contained in the (Al)@NC catalyst.

[0075] III. Application experiment

[0076] 0.01 g of the above synthesized catalyst was put into 50 mL of the pollutant solution, the natural pH (about 6.5) was maintained, the constant temperature was 35°C, and the reaction was started with continuous stirring. At different time points (0, 5, 15, 30, 60 min), the concentration of pollutants was detected.

[0077] Figure 3 Fe 0 -Fe x O y Degradation curves of (Al)@NC for BPA, 2,4-DCP, CIP, SMZ and TC, etc.; the degradation rate of the above pollutants reached more than 90% in 60 minutes, and the degradation rate of CIP and LEV reached more than 99%. Figure 4 Fe 0 -Fe x O y (Al)@NC, Fe 0 -Fe x O y @NC, (Al)@NC, NC degradation curve of CIP. NC and (Al)@NC have poor degradation effect on CIP, Fe 0 -Fe x O y @NC and Fe 0 -Fe x O y (Al)@NC has a degradation rate of more than 90% for CIP, and Fe 0 -Fe x O y(A1)@NC can achieve more than 99% degradation of CIP.

[0078] Figure 5 Fe 0 -Fe x O y (A1)@NC for CIP degradation of the cycle repeated use of activity evaluation figure. As can be seen from the figure, the catalyst for continuous circulation operation several times, its degradation activity of CIP slightly decreased and stabilized, cycle use 4 times, CIP degradation rate still maintained at more than 90%. The above results fully embodies the Fe 0 -Fe x O y (A1)@NC than other Fenton catalysts with the stability advantage, can be applied to the actual micro-polluted water treatment.

[0079] Figure 6 Fe 0 -Fe x O y (A1)@NC for CIP degradation of the continuous flow device, namely the catalyst is loaded on the zeolite, in the case of residence time of 1h, continuous flow device in the continuous operation of 15 days, the degradation rate of 5mg / L of CIP still maintained at more than 60%, Figure 7 for example in the sixteenth day, the residence time is changed to 2h, the degradation rate of CIP from 60% to 80% after gradually decreased to 65% stable.

[0080] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing an iron-aluminum co-doped catalyst, Its features include the following steps: S1: Dissolve aluminum and iron metal salts in a beaker containing deionized water to obtain solution A; S2: Add the phosphorus source to solution A, adjust the pH, and form suspension B; S3: Add biomass to suspension B and stir for 30 min to obtain solution C; S4: Add a nitrogen source to solution C, and dry the beaker in a water bath; mix the obtained dried product with an activator and calcine it under an inert gas to obtain a crude catalyst product, wherein the activator includes one of zinc chloride, sodium bicarbonate and potassium hydroxide; S5: Grind the crude catalyst product, wash it with ethanol and deionized water, and dry it under vacuum to obtain an iron-aluminum co-doped catalyst.

2. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: In step S1, the metallic iron salt includes one of ferric chloride hexahydrate, ferric chloride, ferric nitrate nonahydrate, ferric acetate, ferric sulfate, and ferric acetylacetone, with a mass of 0.5–3 g; the metallic aluminum salt includes one of aluminum chloride, aluminum nitrate, and aluminum sulfate, with a molar ratio of iron to aluminum of (1-6):

1.

3. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: The phosphorus source in step S2 includes one of phosphate, phytic acid, and triphenylphosphine, with a mass of 0.1–1 g.

4. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: The biomass in step S3 includes one of chitosan, cyclodextrin, and corn cob, with a mass of 0.5–3 g.

5. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: The nitrogen in step S4 includes one of urea, melamine, and dicyandiamine, with a mass of 1–16 g.

6. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: In step S5, the uniformly ground solid product is calcined in a tube furnace under nitrogen protection at a temperature of 700-1000℃ for 1-5 h at a heating rate of 5℃ / min. After natural cooling, the catalyst is obtained.

7. The method for synthesizing an iron-aluminum co-doped catalyst according to claim 1, characterized in that: In step S5, the washing process is carried out using one of deionized water and anhydrous ethanol; the drying temperature is 30–60°C and the drying time is 6–24 h.

8. Fe prepared by the method according to any one of claims 1-7 0 -Fe x O y (Al)@NC self-degrading catalyst.

9. The Fe as described in claim 8 0 -Fe x O y Application of (Al)@NC self-degrading catalyst in the degradation of organic pollutants in water.

10. The Fe according to claim 9 0 -Fe x O y Application of (Al)@NC self-degrading catalyst in the degradation of organic pollutants in water, wherein the organic pollutants include one or more of BPA, 2,4-DCP, CIP, SMZ and TC.

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