Preparation and application of a titanium dioxide-iron hydroxyl oxide composite material

Abstract

This invention discloses a method for preparing a titanium dioxide-iron hydroxide (TiO2 / FeOOH) composite material. The composite material uses ferric chloride hexahydrate (FeCl3∙6H2O) as the Fe source and P25 as the Ti source. TiO2 is treated with oxalic acid under hydrothermal conditions to increase surface defects, and then the TiO2 / FeOOH composite material is prepared by impregnation. The composite material exhibits uniform particle distribution, and the combination of FeOOH and TiO2 improves the effective separation of photogenerated electron-hole pairs, resulting in good visible light photocatalytic performance. Experiments show that when the concentration of FeCl3∙6H2O is 0.05 mmol / L, the TiO2 / FeOOH composite material achieves a 99.99% removal rate of 10 mg / L phenol, exhibiting optimal photocatalytic performance.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a titanium dioxide-iron hydroxyl oxide (TiO2 / FeOOH) composite material, belonging to the field of photocatalytic composite material technology. Background Technology

[0002] Benzene compounds (such as phenol and toluene) are important chemical raw materials widely used in building materials, textiles, and other industries. The significant threat posed by low concentrations of benzene compounds in air and industrial wastewater to public health cannot be ignored. Photocatalysis utilizes sunlight to drive photocatalysts to produce highly oxidizing active species, gradually degrading recalcitrant organic matter into non-toxic and harmless carbon dioxide and water. It boasts advantages such as mild reaction conditions, long-lasting performance, and thorough degradation, making it considered one of the ideal technologies for environmental pollution control. TiO2, as a photocatalytic material, is non-toxic, inexpensive, chemically stable, and resistant to photocorrosion. Furthermore, TiO2 has a valence band position of approximately 2.91 eV, a conduction band position of -0.19 eV, and a band gap of 3.2 eV, exhibiting strong oxidizing power compared to most photocatalysts. However, TiO2's visible light response range is below 400 nm, meaning that visible light, which accounts for approximately 43% of sunlight energy, cannot excite TiO2, greatly limiting its practical application. Therefore, constructing a Z-shaped heterojunction can effectively separate photogenerated electron-hole pairs, improving the photocatalytic efficiency of TiO2 materials. Iron hydroxyl oxide not only possesses excellent photoelectrochemical properties but also stable physicochemical properties. In particular, β-FeOOH can be excited to generate photogenerated carriers under visible light, and its surface contains abundant active sites that can adsorb a large number of organic pollutants. Combining FeOOH and TiO2 can promote the separation of photogenerated electron-hole pairs, contributing to improved visible light photocatalytic performance of the material. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing TiO2 / FeOOH composite material, and to improve the visible light photocatalytic performance of TiO2 / FeOOH by combining FeOOH with TiO2, so as to degrade organic pollutants in water.

[0004] I. Preparation of TiO2 / FeOOH composite materials

[0005] (1) Preparation of TiO2 nanoparticles: P25 was dispersed in oxalic acid solution, and after hydrothermal reaction, washing and drying, oxygen-defective TiO2 nanoparticles (TiO2NPs) were obtained.

[0006] The hydrothermal reaction temperature was 90-110℃, and the reaction time was 10-15h; the concentration of the oxalic acid solution was 1.0 mol / L, and the amount of P25 added was 1.00 g / 60mL of oxalic acid solution.

[0007] (2) Preparation of TiO2 / FeOOH composite material: The TiO2 NPs obtained in step (1) were dispersed in deionized water, FeCl3·6H2O was added, and after standing for reaction, the mixture was washed and dried to obtain TiO2 / FeOOH composite material;

[0008] The concentration of FeCl3·6H2O in the reaction system was 0.025~2.0 mM, the mass ratio of FeCl3·6H2O to TiO2 NPs was 1:1.8~1:136.4, the static reaction time was 6 h, and the reaction temperature was room temperature.

[0009] TiO2 / FeOOH composite materials were obtained by using FeCl3∙6H2O concentrations of 0.025 mM, 0.05 mM, 0.5 mM, 1.0 mM, and 2.0 mM in the reaction system. These composite materials were named TiO2 / FeOOH-0.025, TiO2 / FeOOH-0.05, TiO2 / FeOOH-0.5, TiO2 / FeOOH-1.0, and TiO2 / FeOOH-2.0, respectively.

[0010] II. Structure and Properties of TiO2 / FeOOH Composite Materials

[0011] 1. X-ray diffraction (XRD)

[0012] A Philips Xpert PRO powder diffractometer was used. The test conditions were Cu Kα rays, tube voltage of 40 kV, tube current of 100 mA, scanning range of 5-80°, and step size of 2° / min.

[0013] Depend on Figure 1It can be seen that when 2θ is 25.28°, 36.93°, 37.79°, 38.50°, 48.05°, 53.83°, 55.01°, 62.69°, 68.80°, 70.27°, and 75.05°, they correspond to the (101), (103), (004), (112), (200), (105), (211), (204), (116), (220), and (215) crystal planes of anatase, respectively; while when 2θ is 27.40°, 36.03°, 41.23°, and 54.31°, they correspond to the (110), (101), (111), and (211) crystal planes of rutile, respectively. Meanwhile, it can be seen that both TiO2 and TiO2 / FeOOH contain anatase and rutile phase TiO2. Furthermore, with the increase of FeCl3∙6H2O content, the proportion of rutile phase TiO2 in the TiO2 / FeOOH composite material increases slightly, indicating that FeOOH has a certain influence on the crystal phase formation of TiO2. Due to the low FeOOH content, there are no obvious FeOOH diffraction peaks in the composite material.

[0014] 2. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM) testing

[0015] TEM was performed using a FEI Talos F200x transmission electron microscope from the United States, with an accelerating voltage of 200kV. Figure 2 The TEM images of TiO2 and TiO2 / FeOOH show that different FeOOH contents did not change the morphology and particle size of the composite material. When the FeCl3∙6H2O concentration increased from 0.05mM to 2.0mM, the FeOOH nanoparticles were still uniformly distributed. Since the FeOOH content in TiO2 / FeOOH-0.05 was low, its diffraction peaks could not be observed in the XRD spectrum. However, the lattice fringes of TiO2 could be clearly observed in the high-magnification transmission electron microscope image. The spacing was 0.355nm, corresponding to the (101) crystal plane of anatase. The lattice spacing of β-FeOOH was 0.332nm, corresponding to the (310) crystal plane of β-FeOOH. Meanwhile, HR-TEM of TiO2 / FeOOH-2.0 also revealed lattice fringes of β-FeOOH with a spacing of 0.189 nm, corresponding to the (440) crystal plane of β-FeOOH, indicating that β-FeOOH was successfully grown on the TiO2 surface. However, the lattice fringes of β-FeOOH were not very clear, indicating that the crystallinity of β-FeOOH was not very good.

[0016] Figure 3 and Figure 4These are mapping images of TiO2 / FeOOH-0.05 and TiO2 / FeOOH-2.0. In TiO2 / FeOOH-0.05, O and Ti are evenly distributed, while Fe is not very prominent due to its low content. In TiO2 / FeOOH-2.0, however, the even distribution of O, Ti, and Fe is clearly visible. This result is consistent with the TEM results, indicating that FeOOH has been successfully grown on the TiO2 surface.

[0017] 3. Photoluminescence spectrum (PL)

[0018] Figure 5 To excitation wavelength (λ) ex The figure shows the photoluminescence (PL) spectra of TiO2 and the TiO2 / FeOOH-0.05 composite material at 360 nm. As can be seen from the figure, TiO2 has a significant fluorescence emission peak at 423 nm, while the fluorescence emission peak of the TiO2 / FeOOH-0.05 composite material is at 435 nm, shifting towards longer wavelengths. Furthermore, the peak intensity of the TiO2 / FeOOH-0.05 composite material is significantly lower than that of TiO2, indicating that an appropriate amount of FeOOH and TiO2 form a heterojunction, promoting the separation of photogenerated electrons and holes, reducing the recombination rate of photogenerated electrons and holes, and improving the photocatalytic activity of the composite material.

[0019] 4. Degradation performance of p-phenol

[0020] Figure 6 The visible light photocatalytic performance of TiO2 / FeOOH composite materials and TiO2 materials for phenol was shown in the figure under different FeCl3∙6H2O concentrations. As can be seen from the figure, an appropriate amount of FeOOH can promote the visible light photocatalytic degradation of phenol by TiO2. The TiO2 / FeOOH-0.05 composite material achieved a 100% degradation rate of phenol, higher than pure TiO2 (94.77%), exhibiting the best visible light photocatalytic activity. Further increasing the FeCl3∙6H2O concentration led to a decrease in the phenol removal rate of the prepared TiO2 / FeOOH-1.0 and TiO2 / FeOOH-2.0 composite materials, indicating that an appropriate amount of FeOOH combined with TiO2 materials helps to improve the visible light photocatalytic activity of TiO2.

[0021] In summary, this invention uses ferric chloride hexahydrate (FeCl3∙6H2O) as the Fe source and P25 as the Ti source. TiO2 is treated with oxalic acid under hydrothermal conditions to increase surface defects, and then a TiO2 / FeOOH composite material is prepared via impregnation. This composite material exhibits uniform particle distribution, and the combination of FeOOH and TiO2 improves the effective separation of photogenerated electron-hole pairs, resulting in good visible light photocatalytic performance. In this composite material, FeOOH is uniformly loaded on the TiO2 surface, significantly enhancing visible light absorption and photogenerated carrier separation efficiency, achieving a 100% degradation rate for phenol. This invention features a simple and low-cost process, suitable for the efficient photocatalytic degradation of organic pollutants in industrial wastewater. Attached Figure Description

[0022] Figure 1 The XRD patterns are of TiO2 and TiO2 / FeOOH composite materials.

[0023] Figure 2 TEM and HR-TEM images of TiO2 (Fig. a, Fig. b), TiO2 / FeOOH-0.05 (Fig. c, Fig. d) and TiO2 / FeOOH-2.0 (Fig. e, Fig. f).

[0024] Figure 3 The mapping diagram is for TiO2 / FeOOH-0.05.

[0025] Figure 4 This is a mapping diagram of TiO2 / FeOOH-2.0.

[0026] Figure 5 The PL spectra are for TiO2 and TiO2 / FeOOH.

[0027] Figure 6 The photocatalytic performance of TiO2 and TiO2 / FeOOH composite materials on phenol was studied. Detailed Implementation

[0028] The preparation and properties of the TiO2 / FeOOH composite material of the present invention will be further explained below through specific embodiments.

[0029] Example 1

[0030] (1) Weigh 1.0000g of P25 and disperse it in 60mL of 1.0mol / L oxalic acid solution. Stir for 10min and sonicate for 10min. Transfer the solution to a 100mL high-pressure reactor with a polytetrafluoroethylene liner. Heat the reactor to 100℃ at a rate of 2℃ / min and perform a hydrothermal reaction for 12h. After the reaction is complete and cooled to room temperature, filter the product and wash it with deionized water 3-5 times until neutral. After drying at 60℃ for 12h, grind the product to obtain white TiO2 nanoparticles, labeled as TiO2NPs. The visible light photocatalytic degradation rate of TiO2 NPs in 10mg / L phenol solution is 94.77%.

[0031] (2) Weigh 150 mg TiO2NPs, disperse them in 150 mL of deionized water, stir for 10 min, sonicate for 10 min, add 0.0011 g FeCl3∙6H2O (the molar concentration of FeCl3∙6H2O in the reaction system is 0.025 mM), maintain the temperature at 20 °C, let stand for 6 h, after the reaction is complete, filter, and wash with deionized water 3-5 times. After drying at 60 °C for 12 h, grind to obtain a light yellow TiO2 / FeOOH nanocomposite material, labeled as TiO2 / FeOOH-0.025, which has a visible light photocatalytic degradation rate of 99.95% for 10 mg / L phenol solution.

[0032] Example 2

[0033] The remaining conditions were the same as in Example 1, except that the amount of FeCl3∙6H2O added was 0.0021 g (the molar concentration of FeCl3∙6H2O in the reaction system was 0.05 mM), and the final product was labeled as TiO2 / FeOOH-0.05, which had a visible light photocatalytic degradation rate of 10 mg / L phenol solution of 100%.

[0034] Example 3

[0035] The remaining conditions were the same as in Example 1, except that the amount of FeCl3∙6H2O added was 0.0203 g (the molar concentration of FeCl3∙6H2O in the reaction system was 0.5 mM), and the final product was labeled as TiO2 / FeOOH-0.5, which had a visible light photocatalytic degradation rate of 99.93% for 10 mg / L phenol solution.

[0036] Example 4

[0037] The remaining conditions were the same as in Example 1, except that the amount of FeCl3∙6H2O added was 0.0407 g (the molar concentration of FeCl3∙6H2O in the reaction system was 1.0 mM), and the final product was labeled as TiO2 / FeOOH-1.0, which had a visible light photocatalytic degradation rate of 99.75% for 10 mg / L phenol solution.

[0038] Example 5

[0039] The remaining conditions were the same as in Example 1, except that the amount of FeCl3∙6H2O added was 0.0813 g (the molar concentration of FeCl3∙6H2O in the reaction system was 2.0 mM), and the final product was labeled as TiO2 / FeOOH-2.0, which had a visible light photocatalytic degradation rate of 99.06% for 10 mg / L phenol solution.

Claims

1. A method for preparing a titanium dioxide-iron hydroxyl oxide composite material, characterized in that, Includes the following steps: (1) Preparation of TiO2 nanoparticles: Titanium dioxide P25 was dispersed in oxalic acid solution, and after hydrothermal reaction, washing and drying, TiO2 nanoparticles TiO2 NPs with oxygen defects were obtained; (2) Preparation of TiO2 / FeOOH composite material: The TiO2 NPs obtained in step (1) were dispersed in deionized water, FeCl3·6H2O was added, and after standing for reaction, the mixture was washed and dried to obtain TiO2 / FeOOH composite material.

2. The preparation method of the titanium dioxide-iron hydroxyl oxide composite material according to claim 1, characterized in that, In step (1), the hydrothermal reaction temperature is 90-110℃ and the time is 10-15h.

3. The preparation method of the titanium dioxide-iron hydroxyl oxide composite material according to claim 1, characterized in that, In step (1), the concentration of oxalic acid solution is 1.0 mol / L, and the amount of titanium dioxide P25 added is 1.00 g / 60mL of oxalic acid solution.

4. The preparation method of the titanium dioxide-iron hydroxyl oxide composite material according to claim 1, characterized in that, In step (2), the concentration of FeCl3·6H2O in the reaction system is 0.025~2.0 mM, and the mass ratio of FeCl3·6H2O to TiO2 NPs is 1:1.8~1:136.

4.

5. The method for preparing the titanium dioxide-iron hydroxyl oxide composite material according to claim 1, characterized in that, In step (2), the static reaction time is 6 h and the reaction temperature is room temperature.

6. The application of a titanium dioxide-iron hydroxyl oxide composite material prepared by the method described in claim 1 in the photocatalytic degradation of organic pollutants.

7. The application according to claim 6, characterized in that: The organic pollutants include phenol and toluene.

8. The application according to claim 6, characterized in that: The composite material exhibits a phenol degradation rate of ≥99% under visible light irradiation.

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