Sulfur-doped CuFeO2 catalyst as well as preparation method and application thereof

Abstract

The invention relates to a sulfur-doped CuFeO2 catalyst as well as a preparation method and application thereof. According to the sulfur-doped CuFeO2 catalyst disclosed by the invention, the sulfur element exists in crystal lattices of CuFeO2 in the form of substitution sites or interstitial sites. The sulfur element is introduced, so that not only is the interaction between the catalyst and H2O2 enhanced by changing the electronic structure of CuFeO2, but also the generation and stability of active species are promoted by changing the surface properties of the catalyst; besides, sulfur doping improves the adsorption performance and the organic matter degradation efficiency of the catalyst by influencing charge distribution and a chemical environment on the surface of the catalyst, and the sulfur-doped CuFeO2 catalyst shows higher catalytic activity and cycling stability in activating H2O2 to degrade organic pollutants. The catalyst disclosed by the invention is wide in applicability, can be applied to degradation of organic pollutants such as antibiotics and dyes, and can still keep relatively high catalytic activity under the condition of containing inorganic anions.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and particularly relates to a sulfur-doped CuFeO 2 catalyst and its preparation method and application. Background Art

[0002] With the widespread use of antibiotics in the medical and agricultural fields, the problem of water pollution has become increasingly serious. Especially in the agricultural and pharmaceutical industries, the residues of antibiotics not only have a significant impact on the ecological environment but also pose a serious threat to human health. Antibiotics have poor biodegradability, and conventional physical, chemical, and biological treatment methods often have difficulty effectively removing antibiotics from water, resulting in the gradual accumulation of these antibiotics in the environment and further exacerbating the pollution problem. As typical representatives of antibiotics, sulfamethoxazole (SMX) and carbamazepine (CBZ) are difficult to be completely removed during the sewage treatment process. If not properly treated, SMX and CBZ may enter natural water bodies, thereby polluting water sources and affecting the safety of drinking water. This not only has a negative impact on the aquatic ecosystem but may also enter the human body through the food chain, increasing the human's antibiotic resistance and thus posing a threat to public health. Therefore, controlling and reducing the release of antibiotics in the water environment and finding efficient water treatment technologies to remove antibiotics from water are particularly important for protecting the ecological environment and public health.

[0003] Advanced oxidation processes (AOPs) have become a promising alternative method for pollutant treatment. Compared with traditional wastewater treatment methods, the effectiveness of AOPs in wastewater treatment has been fully verified, especially in removing pesticides, dyes, and antibiotics. In recent years, the use of hydrogen peroxide (H 2 O 2 ) for water treatment has gradually attracted attention. As an efficient and green oxidant, H 2 O 2 is easy to obtain and use and shows excellent degradation ability in environmental governance. It can rapidly decompose under relatively mild conditions to generate reactive oxygen species (such as hydroxyl radicals (HO • ), superoxide radicals (O 2 •− ), and singlet oxygen ( 1 O 2 ) etc.), thereby effectively degrading a variety of organic pollutants. However, some disadvantages of the Fenton reaction also restrict its application. For example, the catalytic activity and cyclic stability of the catalysts in the prior art still need to be further improved. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the present invention provides a sulfur-doped CuFeO 2Catalyst, its preparation method and application, which can improve the catalytic reaction activity of degrading organic matter and has good catalyst stability. 2 O 2 The catalytic reaction activity of degrading organic matter is improved and the catalyst has good stability.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] In the first aspect, the present application provides a sulfur-doped CuFeO 2 catalyst, characterized in that sulfur exists in the lattice of CuFeO 2 in a substitutional or interstitial position, and the molar fraction of sulfur is between 0.01 and 0.1.

[0007] In the second aspect, the present application also provides a preparation method of the sulfur-doped CuFeO 2 catalyst described in the first aspect, including the following steps:

[0008] 1) Dissolve copper acetate and iron nitrate in deionized water to obtain a mixed solution; add a sulfur source to the mixed solution, then adjust the pH value to 6.5 - 7.5, and then add a reducing agent to react at 70 - 90 °C for 5 - 8 h to obtain a precursor solution of sulfur-doped CuFeO 2 ;

[0009] 2) Dry the precursor solution of sulfur-doped CuFeO 2 and then perform high-temperature calcination to obtain the sulfur-doped CuFeO 2 catalyst.

[0010] Optionally, in step 2), drying is carried out by drying at 100 - 110 °C, and the high-temperature calcination conditions are calcination at 450 - 600 °C for 2 - 3 h.

[0011] Optionally, the reducing agent is citric acid.

[0012] Optionally, the molar ratio of the amount of copper acetate to iron nitrate used is 1:1.

[0013] Optionally, the sulfur source is sodium thiosulfate.

[0014] In the third aspect, the present application also provides an application of the sulfur-doped CuFeO 2 catalyst described in the first aspect in activating hydrogen peroxide to treat organic wastewater.

[0015] Optionally, use the sulfur-doped CuFeO 2 catalyst to activate hydrogen peroxide to degrade antibiotics and dyes in wastewater, and the antibiotics include sulfamethoxazole and carbamazepine.

[0016] Optionally, the organic wastewater contains inorganic anions.

[0017] Optionally, the inorganic anions include one or more of halogen ions, nitrate, phosphate, and bicarbonate.

[0018] Compared with the prior art, the present application has at least the following beneficial effects:

[0019] In the present invention, sulfur element is introduced into the lattice of CuFeO 2 , which not only enhances the interaction between the catalyst and H 2 O 2 by changing the electronic structure of CuFeO 2 , and promotes the generation and stability of active species by changing the surface properties of the catalyst; in addition, sulfur doping improves the adsorption performance and organic matter degradation efficiency of the catalyst by affecting the charge distribution and chemical environment on the catalyst surface. The sulfur-doped CuFeO 2 catalyst exhibits higher catalytic activity and cyclic stability in activating H 2 O 2 to degrade organic pollutants.

[0020] Cu and Fe in the catalyst of the present invention can form multiple oxidation states. Sulfur doping can increase the electron density of the material and improve the electron mobility; and CuFeO 2 has high thermal stability and chemical stability. After sulfur doping, it can still maintain good catalytic performance in high-temperature or acid-base corrosive environments.

[0021] The catalyst of the present invention has a wide applicability. It is not only applicable to degrade SMX and CBZ, but also can be applied to a variety of organic pollutants that are difficult to biodegrade, such as antibiotics and dyes. It can still maintain high catalytic activity under the condition of containing inorganic anions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is the XRD spectrum of the sulfur-doped CuFeO 2 catalyst obtained in Example 1 of the present application;

[0023] Figure 2 is the microscopic morphology diagram of the catalyst. Among them, (a) is the SEM image of CuFeO 2 and (b) is the SEM image of S / CuFeO 2 ; (c-e) are the TEM images of S / CuFeO 2 ; (f -i) are the EDS spectra of S / CuFeO 2 ;

[0024] Figure 3 is the degradation situation diagram of SMX in the first to fifth reaction systems in Application Example 1 of the present application;

[0025] Figure 4This is the degradation situation diagram of SMX in the fifth and sixth groups in Application Example 1 of this application;

[0026] Figure 5 is sulfur-doped CuFeO 2 Results of the catalyst recycling experiment, where (a) degradation situation of SMX; (b) mineralization rate of SMX;

[0027] Figure 6 is S / CuFeO in Application Example 2 of this application 2 -H 2 O 2 Degradation situation of different organic pollutants. Specific implementation manners

[0028] The present invention will be further described in detail below with reference to the accompanying drawings:

[0029] The experimental methods used in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0030] The reagent materials used in this example can be purchased conventionally. For the quantitative experiments involved in the embodiments, at least three repeated experiments are set, and the results are averaged.

[0031] Example 1

[0032] Dissolve 5 mmol of copper acetate and 5 mmol of iron nitrate in deionized water to prepare a mixed solution. Subsequently, add 2.0 g of sodium thiosulfate to the mixed solution, and adjust the pH value to 7.0 with 1.0 mol / L NaOH solution; then, introduce 10 mmol of citric acid reducing agent, and stir and react at 80 °C and 500 rpm for 6 hours to obtain a precursor solution of sulfur-doped CuFeO 2 Then, place the precursor solution of sulfur-doped CuFeO 2 under the condition of 100 °C for drying treatment to obtain a powdery catalyst; then calcine the powdery catalyst at 500 °C for 2 hours to obtain sulfur-doped CuFeO 2 catalyst.

[0033] Comparative Example 1

[0034] Dissolve 5 mmol of copper acetate and 5 mmol of iron nitrate in deionized water to prepare a mixed solution; adjust the pH value to 7.0 with 1.0 mol / L NaOH solution; then, introduce 10 mmol of citric acid reducing agent, and stir and react at 80 °C and 500 rpm for 6 hours to obtain a precursor solution of CuFeO 2 Then, sulfur-doped CuFeO 2The precursor solution was dried at 100 °C to obtain a powdered catalyst; then the powdered catalyst was calcined at 500 °C for 2 hours to obtain CuFeO 2 catalyst.

[0035] Comparative Example 2

[0036] 5 mmol of copper acetate and 2.0 g of sodium thiosulfate were dissolved in deionized water to obtain a mixed solution, which was then transferred to a high-pressure reactor and reacted at 180 °C for 24 h. After the reaction, it was cooled to room temperature, the precipitate was collected, washed with deionized water and ethanol, and then dried in vacuo at 60 °C. Finally, the dried sample was calcined in air at 400 °C for 2 hours to obtain an S / CuO catalyst.

[0037] Sulfur-doped CuFeO 2 catalyst (S / CuFeO 2 ) The XRD pattern is as Figure 1 shown, and typical diffraction peaks of CuFeO 2 can be observed. These peaks correspond to the characteristic crystal planes of CuFeO 2 , and sulfur doping may cause slight changes in the lattice constant of CuFeO 2 , resulting in a slight shift in the diffraction peak position; it can also be seen from the figure that the XRD patterns of the catalyst before and after the reaction change little, indicating that the sulfur-doped CuFeO 2 catalyst prepared in this application has good stability.

[0038] As Figure 2 shown in Fig. a, pure CuFeO 2 exhibits a nanosheet structure with a diameter of about 2 μM and serious agglomeration. For the S / CuFeO 2 catalyst ( Figure 2 Fig. b), an obvious flower-like structure can be observed and the dispersion is better. As Figure 2 shown in Figs. c-e, obvious lattice fringes can be observed for the S / CuFeO 2 catalyst, and the lattice spacings of 0.258 and 0.323 nm correspond to the CuFeO 2 crystal planes, which is consistent with the XRD results. In addition, the corresponding elemental distribution maps of the S / CuFeO 2 catalyst ( Figure 2 Figs. f-i) show that the four elements of Cu, Fe, O, and S are evenly distributed in the catalyst, confirming the successful preparation of the S / CuFeO 2 catalyst.

[0039] Application Example 1

[0040] Examine CuFeO2 , S / CuFeO 2 , H 2 O 2 , CuFeO 2 -H 2 O 2 , S / CuFeO 2 -H 2 O 2 and the degradation effects of S / CuO on the model pollutant SMX:

[0041] Group 1: Take 100 mg of CuFeO 2 catalyst and add it to a 50 mL reaction system containing 10 mg / L SMX.

[0042] Group 2: Take 100 mg of S / CuFeO 2 catalyst and add it to a 50 mL reaction system containing 10 mg / L SMX.

[0043] Group 3: A 50 mL reaction system containing 10 mg / L SMX and 1.0 mM H 2 O 2 .

[0044] Group 4: Take 100 mg of CuFeO 2 catalyst and add it to a 50 mL reaction system containing 10 mg / L SMX and 1.0 mM H 2 O 2 .

[0045] Group 5: Take 100 mg of S / CuFeO 2 catalyst and add it to a 50 mL reaction system containing 10 mg / L SMX and 1.0 mM H 2 O 2 .

[0046] Group 6: Take 100 mg of S / CuO catalyst and add it to a 50 mL reaction system containing 10 mg / L SMX and 1.0 mM H2O2.

[0047] Stir each reaction system at room temperature for 60 minutes, take samples at regular intervals, and measure the change in the concentration of organic pollutants. The results are as Figure 3 , Figure 4 shown.

[0048] Figure 3 shows the degradation of the reaction systems in Group 1 - Group 5. It can be seen from Figure 3 that CuFeO 2 , S / CuFeO 2has limited adsorption capacity for SMX, and the separate H 2 O 2 oxidation ability is also insufficient to effectively remove SMX. However, the CuFeO 2 -H 2 O 2 system can remove approximately 80% of the pollutants in the experimental system within 60 minutes, indicating that CuFeO 2 can activate H 2 O 2 to generate reactive species for degrading pollutants. In this application, the S / CuFeO 2 catalyst activates H 2 O 2 more effectively. Within the same reaction time, complete degradation of SMX is achieved. Evidently, the sulfur-doped catalyst can significantly improve the electronic structure of the catalyst, enabling more efficient activation of H 2 O 2 and generating more reactive species for degrading organic pollutants.

[0049] Figure 4 shows the degradation situations of the fifth and sixth groups. It can be seen that the S / CuFeO Figure 4 -H 2 -H 2 O 2 system can achieve complete degradation of SMX within 60 min, while the S / CuO-H 2 O 2 system only has a removal efficiency of 69.9% for SMX within 60 min. This indicates that S / CuFeO 2 has a higher activation efficiency for H 2 O 2 and generates more reactive species.

[0050] To test the recycling stability of the catalyst of this application, the S / CuFeO 2 catalyst is used to treat pollutants according to the reaction system in the fifth group. After 60 minutes, the catalyst is recovered and the experiment is conducted again; five consecutive recycling experiments are carried out, and the degradation situation and mineralization rate of SMX are tested.

[0051] The test results of the recycling experiment are shown in Figure 5 . After five cycles of use, 91.1% of SMX can still be removed. Evidently, the prepared S / CuFeO 2 catalyst of this application has good stability; in addition, the S / CuFeO 2 -H 2 O 2 system reaches a mineralization rate of 61.5% for SMX after five recycling experiments. The above results indicate that S / CuFeO 2 -H2 O 2 The system has good application prospects.

[0052] Application Example 2

[0053] Examine S / CuFeO 2 -H 2 O 2 Degradation of different organic pollutants:

[0054] Take 100 mg of S / CuFeO 2 catalyst and add it to a reaction system of 50 mL containing 10 mg / L of pollutant and 1.0 mM H 2 O 2 (the pollutant is one of SMX, CBZ, CIP, PE or IBU). After stirring the reaction for 60 minutes at room temperature, the degradation rates of various organic pollutants were tested. The test results are shown in Figure 6 . It can be seen from the results that the degradation rates of various organic pollutants all reach more than 90% within 60 minutes, indicating that the S / CuFeO 2 catalyst prepared in this application can efficiently remove various organic pollutants and has universality.

[0055] Application Example 3

[0056] Take 100 mg of S / CuFeO 2 catalyst and add it to a reaction system of 50 mL containing 10 mg / L of SMX pollutant and 1.0 mM H 2 O 2 . Add 2.0 mmol of nitrate, chloride, bicarbonate, and phosphate to the reaction system respectively, and test the degradation rates of pollutants in the four groups of systems. It was found through experiments that the sulfur-doped CuFeO 2 catalyst can still maintain high catalytic activity under the condition of containing inorganic anions, and the degradation rate of SMX remains above 85%.

[0057] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A sulfur-doped CuFeO2 catalyst, characterized in that: The sulfur element exists in the CuFeO2 lattice as a substitution or interstitial site, and the molar fraction of sulfur is between 0.01 and 0.

1.

2. A method for preparing the sulfur-doped CuFeO2 catalyst according to claim 1, characterized in that: The steps include: 1) dissolving copper acetate and ferric nitrate in deionized water to obtain a mixed solution; adding a sulfur source to the mixed solution, adjusting the pH value to neutral, adding a reducing agent and reacting at 70-90° C. for 5-8 h to obtain a sulfur-doped CuFeO2 precursor solution; 2) Drying the sulfur-doped CuFeO2 precursor solution and then calcining it at high temperature to obtain the sulfur-doped CuFeO2 catalyst.

3. The method for preparing the sulfur-doped CuFeO2 catalyst according to claim 1, characterized in that: In step 2), the drying is carried out at 100-110°C, and the high temperature calcination condition is calcination at 450-600°C for 2-3 h.

4. The method for preparing the sulfur-doped CuFeO2 catalyst according to claim 1, characterized in that: The reducing agent is citric acid.

5. The method for preparing the sulfur-doped CuFeO2 catalyst according to claim 1, characterized in that: The sulfur source is sodium thiosulfate.

6. The method for preparing the sulfur-doped CuFeO2 catalyst according to claim 1, characterized in that: The amount ratio of the copper acetate and ferric nitrate substances is 1:

1.

7. Use of the sulfur-doped CuFeO2 catalyst according to claim 1 in treating organic wastewater with activated hydrogen peroxide, characterized in that: Sulfur-doped CuFeO2 catalyst was used to activate hydrogen peroxide to degrade antibiotics and dyes in wastewater, including sulfamethoxazole and carbamazepine.

8. The use of the sulfur-doped CuFeO2 catalyst in treating organic wastewater with activated hydrogen peroxide according to claim 7, characterized in that: The organic wastewater contains inorganic anions.

9. The use of the sulfur-doped CuFeO2 catalyst in treating organic wastewater with activated hydrogen peroxide according to claim 8, characterized in that: The inorganic anions include one or more of halogen ions, nitrates, phosphates and bicarbonates.

Images