Beta-FeOOH material and preparation method thereof

Abstract

The invention discloses a beta-FeOOH material and a preparation method thereof, and belongs to the technical field of functional materials and preparation thereof. The method comprises the following steps: dissolving ferric salt in water to obtain a ferric salt solution, adding an organic alkali solution, and stirring to obtain a mixed solution; and aging the mixed solution, performing hydrothermal reaction, and then performing centrifugal washing and drying to obtain the beta-FeOOH material. According to the preparation method, inorganic alkali is replaced by organic alkali to prepare beta-FeOOH, groups existing on the structure of the organic alkali are utilized to increase the steric hindrance effect, and the beta-FeOOH serves as an alkali source to participate in the reaction, so that the effect of a certain dispersing agent is achieved, the problem that beta-FeOOH particles are prone to mutual aggregation is effectively solved, the stability of the beta-FeOOH can be enhanced, and the stability of the beta-FeOOH is improved. The crystallization degree is high; the adsorption performance is relatively excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of functional materials and preparation thereof, and specifically relates to a β-FeOOH material and a preparation method thereof. Background Art

[0002] my country is a major dye production and consumption country, and the treatment of dye wastewater has gradually become the focus of industrial wastewater treatment. Dye wastewater has the characteristics of high organic matter concentration, deep chromaticity, poor biodegradability, high biological toxicity, large changes in water quality and quantity, complex composition, and stable chemical properties, which leads to poor treatment effects of traditional sewage treatment methods and has become a major problem in sewage treatment.

[0003] At present, adsorption and chemical oxidation are effective ways to treat printing and dyeing wastewater. The adsorption method can recycle dyes, saving dye costs while purifying water. The chemical method can break down difficult-to-degrade dye molecules into small molecules and eventually even mineralize them into CO2 and H2O, reducing harm to the environment.

[0004] Iron oxyhydroxide (FeOOH) is widely present in nature and is an important type of iron oxide with special tunnel structure, relatively stable physical and chemical properties, high specific surface area and ultrafine granular structure. The surface of β-FeOOH contains a large number of hydroxyl groups, which has strong adsorption properties under acidic and alkaline conditions. In addition, the electronic state, bond state and atomic coordination of the surface of β-FeOOH are quite different from those inside the particles, and the active sites on the surface are increased, so it has a strong catalytic function.

[0005] However, the ferric hydroxide prepared by using inorganic base and iron salt is easy to agglomerate due to its small particle size, and the ferric hydroxide has low crystallinity and poor stability. Summary of the invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a β-FeOOH material and a preparation method thereof.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing β-FeOOH material, comprising the following steps: dissolving iron salt in water to obtain an iron salt solution, then adding an organic alkali solution and stirring to obtain a mixed solution; aging the mixed solution, performing a hydrothermal reaction, and then centrifugally washing and drying to obtain β-FeOOH.

[0008] As a preferred embodiment of the present invention, the iron salt is ferric chloride hexahydrate, and the concentration of the iron salt solution is 60-200 g / L; the organic base is one of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and choline hydroxide, and the concentration of the organic base solution is 0.5-1 mol / L.

[0009] More preferably, the organic base is tetramethylammonium hydroxide.

[0010] As a preferred embodiment of the present invention, the aging time is 1-3h.

[0011] As a preferred embodiment of the present invention, the temperature of the hydrothermal reaction is 80-100° C. and the time is 3 hours.

[0012] The present invention also claims to protect the β-FeOOH material prepared by the preparation method of the β-FeOOH material.

[0013] Compared with the prior art, the present invention has the following beneficial effects: the present invention replaces the inorganic base with the organic base to prepare β-FeOOH, and utilizes the groups existing in the structure of the organic base to increase the steric hindrance effect. When participating in the reaction as an alkali source, it not only plays a certain role of a dispersant, effectively solving the problem that the β-FeOOH particles are easy to aggregate with each other, but also can enhance the stability of the β-FeOOH itself, and improve the crystallinity and adsorption performance of the β-FeOOH. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The XRD patterns of β-FeOOH prepared in Examples 1-3 and Comparative Examples 1-3 are shown. DETAILED DESCRIPTION

[0015] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0016] Example 1

[0017] A method for preparing β-FeOOH using an organic base comprises the following steps:

[0018] (1) Weigh 1.5 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add 0.5 mol / L tetramethylammonium hydroxide aqueous solution and stir until the mixture is uniformly mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 1 h.

[0019] (2) The reactor was placed in a forced air drying oven at 80°C for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was left. It was washed 3 to 5 times with deionized water at a speed of 4000 rpm for 20 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TMAH-β-FeOOH.

[0020] XRD detection shows that the β-FeOOH crystal peak of the obtained product is significant and obvious, showing good crystallinity.

[0021] Example 2

[0022] A method for preparing β-FeOOH using an organic base comprises the following steps:

[0023] (1) Weigh 3 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add a 1.0 mol / L tetrabutylammonium hydroxide aqueous solution and stir until the mixture is uniformly mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 2 h.

[0024] (2) The reactor was placed in a 90°C forced air drying oven for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was left. It was washed 3 to 5 times with deionized water at a speed of 4500 rpm for 15 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TBAOH-β-FeOOH.

[0025] XRD detection shows that the β-FeOOH crystal peak of the obtained product is significant and obvious, showing good crystallinity.

[0026] Example 3

[0027] A method for preparing β-FeOOH using an organic base comprises the following steps:

[0028] (1) Weigh 5 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add 0.5 mol / L choline hydroxide solution and stir until it is evenly mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 3 h.

[0029] (2) The reactor was placed in a forced air drying oven at 100°C for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was left. It was washed 3 to 5 times with deionized water at a speed of 5000 rpm for 10 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as ChOH-β-FeOOH.

[0030] XRD detection shows that the β-FeOOH crystal peak of the obtained product is significant and obvious, showing good crystallinity.

[0031] Comparative Example 1

[0032] A method for preparing β-FeOOH using an organic base comprises the following steps:

[0033] (1) Weigh 3 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add a 1.0 mol / L tetraethylammonium hydroxide aqueous solution and stir until the mixture is uniformly mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 3 h.

[0034] (2) The reactor was placed in a 90°C forced air drying oven for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was left. It was washed 3 to 5 times with deionized water at a speed of 5000 rpm for 10 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TEAH-β-FeOOH.

[0035] XRD detection shows that the peak of the obtained product β-FeOOH is weaker than that of Examples 1-3, reflecting that the degree of crystallization of β-FeOOH is not high.

[0036] Comparative Example 2

[0037] A method for preparing β-FeOOH using an organic base comprises the following steps:

[0038] (1) Weigh 5 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add a 1.0 mol / L tetrapropylammonium hydroxide aqueous solution and stir until the mixture is uniformly mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 1 h.

[0039] (2) The reactor was placed in a forced air drying oven at 100°C for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was left. It was washed 3 to 5 times with deionized water at a speed of 5000 rpm for 10 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TPAOH-β-FeOOH.

[0040] XRD detection shows that the peak of the obtained product β-FeOOH is weaker than that of Examples 1-3, reflecting that the degree of crystallization of β-FeOOH is not high.

[0041] Comparative Example 3

[0042] A method for preparing β-FeOOH comprises the following steps:

[0043] (1) Weigh 1.5 g of ferric chloride hexahydrate and add it to 25 ml of deionized water. Stir on a magnetic stirrer for 5 min until it is completely dissolved. Then slowly add 0.5 mol / L sodium hydroxide solution and stir until it is well mixed. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 1 h.

[0044] (2) The reactor was placed in a forced air drying oven at 80°C for hydrothermal reaction for 3 hours. After the reaction was completed, the reactor was taken out, the supernatant was poured out, and the precipitate was kept. It was washed 3 to 5 times with deionized water at a speed of 4000 rpm for 20 minutes in a centrifuge, and the supernatant was discarded until the pH of the precipitate was ≈ 7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as NaOH-β-FeOOH.

[0045] XRD detection shows that the crystal peak of the obtained product β-FeOOH is the weakest compared with Examples 1-3 and Comparative Examples 1-2, reflecting that the crystallinity of NaOH-β-FeOOH is poor.

[0046] Effect example

[0047] The β-FeOOH prepared in the embodiment and the comparative example is used for photocatalytic degradation of methylene blue, and the steps are as follows: take 6 portions of 100 ml of 60 mg / L methylene blue solution, put them into 100 ml beakers respectively, write labels, and set three control groups for each group. Put 100 mg β-FeOOH in turn, adjust pH≈8, put it on a magnetic stirrer under natural light and stir it at a speed of 350 rpm, take samples at intervals of 0, 10, 20, 30, 40, 50, 60, 80, 100, and 120 min, filter it through a 0.22 μm water filter membrane, measure the absorbance of methylene blue at 664 nm in an ultraviolet spectrophotometer, and calculate the degradation rate D according to the formula: D=(A0-A) / A0×100% (where A0 is the absorbance of the initial methylene blue solution; A is the absorbance of the solution after sampling and filtering the membrane after a certain reaction time). After 120 min of degradation, the performance study of β-FeOOH in catalytic degradation of methylene blue under light conditions is shown in Table 1.

[0048] Table 1

[0049] Degradation rate Example 1 92.6％ Example 2 89.7％ Example 3 90.4％ Comparative Example 1 72.0％ Comparative Example 2 78.0％ Comparative Example 3 67.1％

[0050] According to Table 1 and the XRD diagram, the β-FeOOH prepared by the three organic bases of tetramethylammonium hydroxide, tetrabutylammonium hydroxide and choline hydroxide not only has good crystallinity, but also has good photocatalytic degradation performance, and has a stable structure. After multiple cycles of catalysis of methylene blue, its degradation efficiency remains basically unchanged, so it can be reused for photocatalytic degradation of organic matter. However, the β-FeOOH prepared by other organic bases in Comparative Examples 1-2 has low crystallinity and low catalytic degradation efficiency. After two cycles of use, the degradation efficiency begins to decrease, and is also accompanied by a small amount of Fe leaching. The structural stability is relatively poor, and the material cannot be reused many times. In addition, the β-FeOOH prepared in Comparative Example 3 is structurally unstable. After a photocatalytic removal of organic matter, Fe in the β-FeOOH material is leached, resulting in structural instability, which in turn leads to unstable performance of the material, and the material cannot be recycled.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing β-FeOOH material, characterized in that: The method comprises the following steps: dissolving iron salt in water to obtain an iron salt solution, then adding an organic alkali solution and stirring to obtain a mixed solution; aging the mixed solution, performing a hydrothermal reaction, then centrifugally washing and drying to obtain beta-FeOOH.

2. The method for preparing the β-FeOOH material according to claim 1, characterized in that: The iron salt is ferric chloride hexahydrate, and the concentration of the iron salt solution is 60-200 g / L; the organic base is one of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, and choline hydroxide, and the concentration of the organic base solution is 0.5-1 mol / L.

3. The method for preparing the β-FeOOH material according to claim 1, characterized in that: The organic base is tetramethylammonium hydroxide.

4. The method for preparing the β-FeOOH material according to claim 1, characterized in that: The aging time is 1-3h.

5. The method for preparing the β-FeOOH material according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 80-100° C. and the time is 3 hours.

6. The β-FeOOH material prepared by the method for preparing the β-FeOOH material according to any one of claims 1 to 5.

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