Method for preparing supported FeOOH fenton catalyst by using attapulgite to purify white water waste liquid and application thereof

Abstract

The application discloses a method for preparing a supported FeOOH Fenton-like catalyst by using attapulgite for purification of whitening waste liquid and application thereof. The method comprises the following steps: impregnating iron ions in the attapulgite clay whitening waste liquid, and forming the preparation method of the attapulgite loaded FeOOH after calcination, and using the same as a Fenton-like catalyst to degrade methylene blue wastewater. The attapulgite ore has low grade, and the waste liquid generated in the attapulgite whitening process contains a large amount of iron ions, so that direct discharge causes pollution. The iron ions in the whitening waste liquid are used as an iron source, and the iron ions are loaded on the attapulgite ore by the impregnation method. The natural attapulgite ore is rich in a large amount of iron ions, and is a good Fenton-like catalyst, so that a large amount of iron ions are contained in the inside and outside of the attapulgite structure after the impregnation and loading, and the reaction active sites of the catalyst are increased. The application realizes the utilization of the whitening waste liquid, can efficiently degrade the methylene blue wastewater, and is simple, easy to operate and low in cost.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment, and in particular to a method for preparing and using a Fenton-like catalyst. Background Technology

[0002] Attapulgite clay is a porous, layered, hydrous magnesium silicate clay mineral, specifically a dioctahedral clay mineral. Due to its zeolite-like nanopores, numerous internal channels, and interlaced basic structural units, attapulgite possesses a unique structure with a large specific surface area and numerous adsorption and catalytic active sites, giving it excellent adsorption, colloidal, and support properties. Attapulgite clay from Gansu province, despite its low purity, contains a large amount of iron ions and exhibits excellent support structure, making it a promising Fenton-like catalyst material.

[0003] With the rapid development of my country's industrialization process, the printing and dyeing industry has flourished, and my country's annual dye production ranks first in the world. However, the dye wastewater generated by the printing and dyeing industry has caused serious impacts on human health and the ecological environment. Methylene blue is a common dyeing agent, widely used in the dyeing of paper, hemp, silk fabrics and bamboo and wood, and is widely present in printing and dyeing wastewater. Methylene blue wastewater is an alkaline solution that is toxic and harmful to humans and can cause irreversible damage to humans and animals. At present, the methods for degrading methylene blue wastewater mainly include physical methods, biological methods, chemical methods and advanced oxidation technologies. Advanced oxidation technologies have been widely used due to their high efficiency and low cost. The Fenton reaction is the most common method of advanced oxidation technology. The traditional Fenton method has the following two disadvantages: (1) The optimal reaction conditions for the Fenton reaction are acidic conditions with a pH of about 3, which will cause certain corrosion to the equipment. When the pH is greater than 3, iron ions begin to form complexes or precipitates, thus reducing efficiency. (2) The discharge of a large amount of iron ions in the solution will cause secondary pollution to the environment.

[0004] To address the shortcomings of traditional homogeneous Fenton reactions, researchers have developed heterogeneous Fenton catalysts. These catalysts improve the local effective pH and protect iron ions from complexation or deactivation. However, they still have the following problems: (1) The large amount of catalyst required for treating polluted wastewater leads to high catalyst preparation costs. (2) Catalyst preparation is difficult; some catalysts have complex preparation processes and low efficiency. (3) The catalyst structure is unstable; although heterogeneous catalysts can effectively reduce the dissolution of iron ions, the catalyst is difficult to recover and reuse as iron ions continue to dissolve.

[0005] Therefore, it is essential to develop heterogeneous Fenton catalysts that are simple, efficient, easy to prepare, low in cost, and structurally stable. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a FeOOH-based Fenton catalyst supported on attapulgite powder and its application in the degradation of methylene blue wastewater. This method is simple to implement, low in cost, produces a stable material structure, and has achieved good results in the degradation of methylene blue wastewater.

[0007] The technical solution of the present invention is as follows:

[0008] Gansu attapulgite clay, due to its low purity, requires further whitening and purification. This process generates a large amount of whitening wastewater containing high levels of iron ions. Direct discharge of this wastewater would result in resource waste and environmental pollution. Attapulgite clay itself contains significant structural iron, making its direct use as a Fenton-like catalyst for the degradation of methylene blue wastewater generally ineffective. To address this issue, the inventors utilized attapulgite clay to load the iron ions from the whitening wastewater, resulting in a high concentration of iron ions both within and outside the attapulgite clay structure, thereby increasing the number of active sites on the catalyst.

[0009] A method for preparing supported FeOOH-based Fenton catalysts using attapulgite purification and whitening waste liquid includes the following steps:

[0010] (1) After crushing the attapulgite clay, pass it through an 80-mesh sieve. Add the raw attapulgite powder to hydrochloric acid, heat it at 70-90℃ and stir it magnetically for 8-12 hours. Then, separate the waste liquid containing iron ions by centrifugation.

[0011] (2) Adjust the pH of the waste liquid obtained in step (1) to 2-3 with NaOH solution, then add the raw attapulgite powder to the waste liquid, ultrasonically impregnate for 30-60 minutes, and then separate the solid powder by centrifugation.

[0012] (3) Place the solid powder obtained in step (2) into an oven and keep it at 100-120℃ for 2-3 hours.

[0013] (4) Place the dried solid powder from step (3) into a muffle furnace and keep it at 200-300℃ for 2-3 hours.

[0014] According to the preferred embodiment of the present invention, the attapulgite in step (1) is selected from attapulgite clay with high iron content in Baiyin area of ​​Gansu Province.

[0015] According to a preferred embodiment of the present invention, the concentration of hydrochloric acid in step (1) is 0.5-1.5 mol·L⁻¹. -1 The solid-liquid mass ratio of attapulgite powder and hydrochloric acid is 1:30-50.

[0016] According to a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution in step (2) is 0.5-1 mol·L⁻¹. -1 The solid-liquid mass ratio of attapulgite powder to waste liquid is 1:50-70.

[0017] According to the preferred embodiment of the present invention, the centrifuge rotation speed during separation in steps (1) and (2) is 8000-10000 r / min, and the time is 3-5 min.

[0018] According to the preferred embodiment of the present invention, the heating rate of the muffle furnace roasting in step (2) is 5°C / min.

[0019] The advantages of this invention are as follows:

[0020] 1. The iron ions in the wastewater were used as an iron source for the catalyst, thus realizing the utilization of waste.

[0021] 2. The attapulgite-supported FeOOH prepared in this invention has excellent catalytic performance. When the initial concentration of methylene blue is 100 mg / L, the temperature is 50℃, the pH is 3, the concentration of attapulgite-supported FeOOH is 0.5 g / L, and the concentration of H2O2 is 20 mmol / L, methylene blue can be completely degraded within 10 min.

[0022] 3. The material prepared by this invention has a structure of natural iron-containing attapulgite loaded with FeOOH, which makes the attapulgite structure contain iron both inside and out. This coupling effect of iron inside and outside the structure makes the structure stable (with less iron dissolution) and can be recycled.

[0023] 4. The raw materials used in this invention are inexpensive and environmentally friendly. Attached Figure Description

[0024] Figure 1 This is an X-ray diffraction pattern comparing FeOOH-loaded attapulgite and raw attapulgite powder prepared in Example 1.

[0025] Figure 2 In Figure a, scanned electron microscope (SEM) image of raw attapulgite powder is shown; in Figure b, scanned electron microscope (SEM) image of attapulgite loaded with FeOOH prepared in Example 1 is shown.

[0026] Figure 3 This is a comparison chart of the performance of Example 2 and Example 3 in degrading methylene blue wastewater.

[0027] Figure 4 This is a graph showing the iron ion leaching concentration during the reaction of FeOOH supported on attapulgite prepared in Example 1 under the conditions of Example 2.

[0028] Figure 5 Degradation performance of FeOOH supported on attapulgite prepared in Example 1 after 5 cycles under the conditions of Example 1. Detailed Implementation

[0029] Example 1

[0030] After crushing the attapulgite clay, pass it through an 80-mesh sieve. Weigh 1g of the sieved attapulgite powder and add it to 50ml of 1mol·L⁻¹ solution. -1 The pH was adjusted to 3 with hydrochloric acid. 1g of attapulgite powder was weighed and added to 30ml of the aforementioned waste liquid with pH=3. The mixture was ultrasonically impregnated at room temperature for 30min. After impregnation, the mixture was centrifuged at 10000r / min for 5min. The resulting solid powder was dried in a 120℃ oven for 2h, and then calcined in a muffle furnace at a heating rate of 5℃ / min for 2h at 300℃ to obtain the final product, attapulgite-supported FeOOH.

[0031] Figure 1 The images show the XRD patterns of FeOOH loaded on attapulgite and raw attapulgite powder, indicating that FeOOH was successfully loaded onto attapulgite. Figure 2 The images show SEM images of the obtained attapulgite loaded with FeOOH and raw attapulgite powder. Table 1 shows the XRF elemental analysis of the attapulgite loaded with FeOOH and raw attapulgite powder. The elemental analysis shows that the iron ions in the waste liquid were successfully impregnated and loaded onto the attapulgite.

[0032] Table 1 Comparison of FeOOH elemental content in raw attapulgite powder and attapulgite-loaded powder analyzed by XRF.

[0033]

[0034] Example 2

[0035] Prepare 100ml of solution with an initial concentration of 50mg·L. -1 Methylene blue was used as a simulated wastewater in a 250 ml beaker for degradation experiments, using 1 mol·L⁻¹ water. -1 H2SO4 and 1 mol·L -1 Adjust the pH of the NaOH solution to 3. Once the pH is adjusted to approximately 3, add 0.5 g·L⁻¹ of NaOH solution while heating at 50°C. -1 In Example 1, the attapulgite-loaded FeOOH was magnetically stirred and equilibrated for 30 min. After equilibration, a 30% hydrogen peroxide solution was added, with the amount of hydrogen peroxide in the wastewater being 20 mmol·L⁻¹. -1 During the degradation experiment, 3 ml of waste liquid was sampled at different time points and centrifuged. The absorbance of the separated solution was then measured at a wavelength of 664 nm to calculate the degradation rate of methylene blue.

[0036] Example 3

[0037] Replace the FeOOH loaded on the attapulgite with raw attapulgite powder, and keep the other experimental conditions and operating procedures the same as in Example 2. Figure 3 This is a performance comparison chart of raw attapulgite powder and attapulgite loaded with FeOOH. The experimental results show that raw attapulgite powder, due to its inherent structural iron content, has a 55% degradation rate for methylene blue, while attapulgite loaded with FeOOH can achieve a 100% degradation rate within 15 minutes. Figure 4 The graph shows the change in iron ion dissolution concentration during the degradation reaction of FeOOH supported on attapulgite at pH=3. The results show that the iron ion dissolution is low, proving that the catalyst structure is stable. Figure 5 The graph shows the performance of FeOOH supported on attapulgite in five cycles of degradation of methylene blue. The results demonstrate that the catalyst has a stable structure and maintains high activity after multiple cycles.

Claims

1. A method for preparing supported FeOOH-based Fenton catalysts from attapulgite-purified wastewater, comprising the following steps: (1) After crushing the attapulgite clay, pass it through an 80-mesh sieve to obtain raw attapulgite powder. Add the raw attapulgite powder to a hydrochloric acid solution, heat and magnetically stir at 70-90℃ for 8-12 hours, and then separate the solution by centrifugation to obtain a waste liquid containing iron ions; the concentration of the hydrochloric acid is 0.5-1.5 mol·L. -1 The solid-liquid mass ratio of attapulgite powder and hydrochloric acid is 1:30-50. (2) Adjust the pH of the waste liquid obtained in step (1) to 2-3 with NaOH solution, then add the raw attapulgite powder to the waste liquid, and after ultrasonic impregnation for 30-60 min, separate it with a centrifuge to obtain solid powder; the concentration of NaOH solution is 0.5-1 mol·L -1 The solid-liquid mass ratio of attapulgite powder to waste liquid is 1:50-70. (3) Place the solid powder obtained in step (2) into an oven and keep it at 100-120℃ for 2-3 hours; (4) Place the dried solid powder from step (3) into a muffle furnace and keep it at 200-300℃ for 2-3 hours with a heating rate of 5-10℃ / min.

2. A supported FeOOH-type Fenton catalyst prepared by the method described in claim 1.

3. The application of the supported FeOOH-type Fenton catalyst as described in claim 2 in the degradation of methylene blue wastewater.

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