A β-FeOOH material and preparation method thereof

Abstract

The present invention discloses a β-FeOOH material and a preparation method thereof, and belongs to the field of functional materials and their preparation technology. The present invention dissolves an iron salt in water to obtain an iron salt solution, then adds an organic base solution to stir, and obtains a mixed solution; after aging the mixed solution, a hydrothermal reaction is carried out, followed by centrifugal washing and drying to obtain a β-FeOOH material. The present invention replaces an inorganic base with an organic base to prepare β-FeOOH, utilizes the groups present in the organic base structure to increase the steric effect, and participates in the reaction as an alkali source, which not only plays the role of a certain dispersant, but also effectively solves the problem that β-FeOOH particles are easily aggregated with each other, and can also enhance the stability of β-FeOOH itself, with a high degree of crystallinity and better adsorption performance.

Description

Technical Field

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

[0002] my country is a major producer and consumer of dyes, and the treatment of dye wastewater has gradually become a key focus of industrial wastewater treatment. Dye wastewater, due to its high organic matter concentration, dark chroma, poor biodegradability, high biotoxicity, wide variability in water quality and quantity, complex composition, and stable chemical properties, is ineffective with traditional wastewater treatment methods, making it a major wastewater treatment challenge.

[0003] Currently, 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), widely present in nature, is an important class of iron oxides characterized by a unique tunnel structure, relatively stable physical and chemical properties, a high specific surface area, and an ultrafine granular structure. The surface of β-FeOOH contains a large number of hydroxyl groups, which exhibits strong adsorption properties under both acidic and alkaline conditions. Furthermore, the electronic state, bond state, and atomic coordination of the β-FeOOH surface differ significantly from those within the particle, increasing the number of surface active sites and thus possessing a strong catalytic function.

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

[0006] In view of the above 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 an iron salt in water to obtain an iron salt solution, then adding an organic base solution and stirring to obtain a mixed solution; aging the mixed solution, performing a hydrothermal reaction, and then centrifuging, 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 1-3 hours.

[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 protection for 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 an 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 as a dispersant, effectively solving the problem that β-FeOOH particles are prone to aggregation, but also can enhance the stability of β-FeOOH itself and improve the crystallinity and adsorption performance of 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 uniform. 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 a hydrothermal reaction of 3 h. After the reaction was completed, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3 to 5 times with deionized water at a speed of 4000 rpm for 20 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TMAH-β-FeOOH.

[0020] XRD analysis showed that the β-FeOOH crystal peak of the obtained product was 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 aqueous solution of tetrabutylammonium hydroxide and stir until the mixture is uniform. Transfer the mixture to a 100 ml polytetrafluoroethylene-lined autoclave and age it for 2 h.

[0024] (2) The reactor was placed in a forced air drying oven at 90°C for a hydrothermal reaction of 3 h. After the reaction was complete, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3–5 times with deionized water at 4500 rpm for 15 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The resulting product was dried at 70°C and sealed for storage. The material was designated as TBAOH-β-FeOOH.

[0025] XRD analysis showed that the β-FeOOH crystal peak of the obtained product was 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 a hydrothermal reaction of 3 h. After the reaction was complete, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3–5 times with deionized water at 5000 rpm for 10 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as ChOH-β-FeOOH.

[0030] XRD analysis showed that the β-FeOOH crystal peak of the obtained product was 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 1.0 mol / L tetraethylammonium hydroxide aqueous solution and stir until it is evenly 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 forced air drying oven at 90°C for a hydrothermal reaction for 3 h. After the reaction was completed, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3 to 5 times with deionized water at a speed of 5000 rpm for 10 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TEAH-β-FeOOH.

[0035] XRD analysis shows that the peak of the obtained product β-FeOOH is weaker than that of Examples 1-3, reflecting that the degree of crystallinity 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 uniform. 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 a hydrothermal reaction of 3 h. After the reaction was complete, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3 to 5 times with deionized water at 5000 rpm for 10 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as TPAOH-β-FeOOH.

[0040] XRD analysis shows that the peak of the obtained product β-FeOOH is weaker than that of Examples 1-3, reflecting that the degree of crystallinity 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 evenly 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 a hydrothermal reaction of 3 h. After the reaction was complete, the reactor was removed, the supernatant was discarded, and the precipitate was retained. The precipitate was washed 3 to 5 times with deionized water at 4000 rpm for 20 min, and the supernatant was discarded until the precipitate had a pH of ≈7. The obtained product was dried at 70°C and sealed for storage. The material was recorded as NaOH-β-FeOOH.

[0045] XRD analysis 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 Examples

[0047] The β-FeOOH prepared in the examples and comparative examples was used to photocatalytically degrade methylene blue, as follows: 6 portions of 100 ml of a 60 mg / L methylene blue solution were placed in 100 ml beakers, labeled, and three control groups were set up for each group. 100 mg of β-FeOOH was added sequentially, the pH was adjusted to 8, and the mixture was stirred on a magnetic stirrer at 350 rpm under natural light. Samples were taken at intervals of 0, 10, 20, 30, 40, 50, 60, 80, 100, and 120 minutes, filtered through a 0.22 μm water filter membrane, and the absorbance of the methylene blue was measured at 664 nm using an ultraviolet spectrophotometer. The degradation rate D was calculated according to the formula: D = (A0-A0) / A0×100% (where A0 is the absorbance of the initial methylene blue solution; A is the absorbance of the solution after a certain reaction time and after filtering through the filter membrane). After 120 min of degradation, the performance 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 catalytic methylene blue, its degradation efficiency remains basically unchanged, so it can be reused to photocatalytically degrade 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 accompanied by a small amount of Fe leaching. The structural stability is relatively poor, and the material cannot be reused multiple times. In addition, the β-FeOOH prepared in Comparative Example 3 is structurally unstable. After a photocatalytic removal of organic matter, the Fe in the β-FeOOH material leaches, resulting in structural instability, which in turn leads to unstable performance of the material and the inability to recycle the material.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing β-FeOOH material, characterized in that: The method comprises the following steps: dissolving an iron salt in water to obtain an iron salt solution, then adding an organic base 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; the organic base is one of tetramethylammonium hydroxide, tetrabutylammonium hydroxide and choline hydroxide.

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

4. The method for preparing the β-FeOOH material according to claim 1, wherein: The aging time is 1-3 hours.

5. The method for preparing the β-FeOOH material according to claim 1, wherein: 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 claim 1 .

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