Preparation method of isomorphous substitution catalytic ozonation nano-catalyst Fe (at) CeO2-x / MgO

Abstract

The preparation method comprises the following steps: dissolving MgSO4. 7H2O, Ce (NO3) 3.6 H2O and FeCl2. 4H2O in deionized water, adjusting the pH value of the obtained mixed solution to 8.8-9.0 by using dilute ammonia water, standing and aging for 60 minutes, centrifuging, washing by using deionized water until the pH does not change any more, and drying to obtain Fe (OH) 2 / Ce (OH) 3 / Mg (OH) 2 mixed powder; the Fe (OH) 2 / Ce (OH) 3 / Mg (OH) 2 mixed powder is ground and placed in a crucible to be calcined for 2 hours in the air atmosphere of 700 DEG C, Fe (at) CeO2-x / MgO powder is obtained, the obtained isomorphic substitution catalytic ozonation nano-catalyst has rich oxygen vacancies and Lewis acid sites, ozone can be adsorbed, generation of active oxygen species is promoted, the preparation method is simple, the prepared catalyst is high in catalytic efficiency, and the catalyst can be applied to the field of catalytic ozonation catalysis. New tetracycline antibiotic pollutants can be effectively degraded and mineralized, and the generation potential of disinfection by-products of tetracycline can be synchronously and remarkably controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental remediation and pollution control, and more specifically relates to an isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO 2-x The invention discloses a preparation method of MgO / MgO and its application. The catalyst is used to mineralize residual antibiotics in water under an ozone system and simultaneously control the generation potential of disinfection by-products of antibiotics. Background Art

[0002] In recent years, the frequent detection of various antibiotic contaminants in water environments has garnered worldwide attention for the emergence of drug-resistant bacteria and resistance genes. Antibiotics such as tetracycline are also precursors of disinfection byproducts, generating chloroform and haloacetic acids during chlorination. Commonly used technologies for antibiotic remediation include photocatalytic oxidation, ozone (catalytic) oxidation, and adsorption.

[0003] Compared with other antibiotic treatment technologies, ozone-based advanced oxidation technology has the advantages of less secondary pollution, strong oxidation ability, and easy engineering application. However, conventional ozone oxidation technology has problems such as low ozone utilization rate, low hydroxyl radical production, insufficient mineralization capacity for pollutants, and inability to simultaneously control the generation potential of disinfection by-products, which seriously restrict its development prospects. On the other hand, variable valence metal oxides (such as Fe, Mn, Ce, Cu) are easy to achieve Me due to their outer electron structure. n+ with me (n+m)+ The valence state cycling between metals can promote the generation of active species such as hydroxyl radicals. Introducing this into ozone oxidation can effectively mineralize difficult-to-degrade organic pollutants. However, this also presents challenges such as unstable metal ion performance, ion dissolution, and high electron transport resistance. Isomorphous substitution is one strategy used to address this issue, as it can generate OVs in situ and induce lattice distortion. These properties greatly enhance electron transport in variable-valence metals, significantly increasing catalyst activity and generating abundant active species for the mineralization of organic matter in water.

[0004] CeO2, as a typical catalyst, has good catalytic performance. However, due to the limited active sites and high electron transfer resistance, the wide application of CeO2 is restricted. If variable valence metal elements are isomorphously substituted into the CeO2 structure, multiple active sites such as oxygen-rich vacancies and Lewis acid sites can be introduced and the electron transfer resistance can be greatly reduced, thereby effectively improving the oxygen / ozone utilization rate, active species yield and catalytic performance of CeO2.

[0005] The invention application with application number 202011465302.8 discloses a low-cost, long-life CeO2-SiO2 nanocomposite catalyst that can be used for industrial water treatment, and applies the nanocomposite catalyst to the mineralization of bisphenol A, an organic pollutant. The invention obtains a CeO2-SiO2 nanocomposite catalyst by hydrogen heat treatment, and uses catalytic ozone oxidation to mineralize bisphenol A. However, the catalyst uses flammable and explosive gases and high temperature conditions during the synthesis process, which greatly increases energy consumption and thus increases the cost of catalyst synthesis. In addition, the uncontrollable formation of surface oxygen vacancies will cause large differences in the performance of the catalyst.

[0006] Invention application number 201810159692.2 discloses a method for preparing a Co-doped CeO2 nanotube-chitosan catalyst. This invention utilizes a hydrothermal method to prepare the Co-doped CeO2 nanotube-chitosan ozone oxidation catalyst. By adjusting the mass ratio of Co-doped CeO2 nanotubes to chitosan, the catalytic activity of the prepared catalyst is optimized, enabling the ozone oxidation of Reactive Orange 16 wastewater. However, the leakage of heavy metal Co ions may cause secondary problems in water bodies.

[0007] Invention application number 201910043247.4 discloses a mixed metal oxide catalyst of CeO2, MnO2, CuO, and V2O5, its preparation method, and application. This invention utilizes carbonization and activation to prepare a supported catalyst for COD removal from refinery wastewater. However, the material preparation method is complex and energy-intensive. Furthermore, the composition is unclear, making it difficult to replicate and mass-produce.

[0008] Therefore, it is an urgent problem for technicians in this field to develop an isomorphous substitution catalytic ozone oxidation nanocatalyst that has a simple preparation method, can be applied to water environments, has a controllable particle size, and can introduce active sites to reduce electron transfer resistance, thereby quickly and efficiently mineralizing organic pollutants. Summary of the Invention

[0009] In view of this, the present invention provides a simple Fe@CeO2 that can improve the catalytic performance of CeO2 and simultaneously maintain efficient and rapid mineralization of pollutants. 2-x Preparation method and application of / MgO isomorphous substitution ozone oxidation nanocatalyst.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] 1. An isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO 2-x The preparation method of / MgO comprises the following steps:

[0012] (1) MgSO4·7H2O, Ce(NO3)3·6H2O and FeCl2·4H2O were dissolved in deionized water to obtain a mixed solution 1, the pH value of the obtained mixed solution 1 was adjusted to 8.8-9.0 with dilute ammonia water, the mixed solution 1 was allowed to stand for 60 minutes, centrifuged, washed with deionized water until the pH value no longer changed, and dried to obtain a Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder;

[0013] (2) The obtained Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder was ground and placed in a crucible and calcined in an air atmosphere at 700°C for 2 hours, and then naturally cooled to obtain the Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst.

[0014] 2. In step (1), the molar fraction of the dilute ammonia solution is 26.09-29.16%, and the pH is adjusted to 8.8-9.0.

[0015] 3. In step (1), the standing aging time is 60 min, and the aging temperature is a constant temperature of 30°C in a water bath.

[0016] 4. In step (1), FeCl2·4H2O accounts for 0, 1.96%, 5.67%, 9.09%, 12.28% and 16.67% of the total molar amount of catalyst metal atoms, respectively, and the rest is MgSO4·7H2O and Ce(NO3)3·6H2O. The atomic molar ratio of Mg to Ce is fixed at 4:1. According to the different molar amounts of Fe atoms, they are named CeO2 / MgO, 0.1Fe@CeO 2-x / MgO、0.3Fe@CeO 2-x / MgO、0.5Fe@CeO 2-x / MgO、0.7Fe@CeO 2-x / MgO、1.0Fe@CeO 2-x / MgO

[0017] 5. In step (2), the calcination atmosphere is air.

[0018] 6. In step (2), the calcination temperature is 700°C, and the heating program is as follows: heating rate 5°C / min to 450°C, and then 8°C / min to 700°C.

[0019] 7. In step (2), the calcination time is 2 hours.

[0020] 8. The Fe@CeO 2-xThe steps of mineralizing tetracycline hydrochloride catalytic ozone oxidation using a nano-catalyst for catalytic ozone oxidation using isomorphous substitution of MgO include: preparing Fe@CeO with different molar amounts of FeCl2·4H2O. 2-x The / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst is added into wastewater containing tetracycline hydrochloride, ozone is introduced, and the reaction system is used for catalytic oxidation.

[0021] 9. The Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst mineralizes tetracycline hydrochloride in a closed system;

[0022] and / or the 0.5Fe@CeO 2-x / MgO concentration in the reaction system is 0.25g / L-1.5g / L;

[0023] and / or the concentration of ozone in the reaction system is 0.74 mg / L-6.4 mg / L;

[0024] and / or the concentration of tetracycline hydrochloride in the reaction system is 10 mg / L-40 mg / L;

[0025] and / or the pH of the reaction system is 4-10;

[0026] 10. A 0.5Fe@CeO 2-x 0.5Fe@CeO prepared by the preparation method of / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst 2-x The application of / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst in mineralized organic pollutants is characterized by the fact that while degrading mineralized tetracycline, it can simultaneously and efficiently reduce the formation potential of tetracycline's chlorination disinfection byproducts, including chloroform, dichloroacetonitrile, and dichloroacetic acid.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention prepared Fe@CeO by co-precipitation and calcination synthesis 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst has a simple synthesis method, and the catalyst is rich in oxygen vacancies and Lewis acid sites, which enhances ozone adsorption and decomposition.

[0029] 2. Fe@CeO of the present invention 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst showed excellent catalytic activity in the mineralization process of high concentration tetracycline solution (20 mg / L), and could achieve a mineralization efficiency of more than 65% within 60 minutes.

[0030] Furthermore, in step (1), 24.647 g of MgSO4·7H2O, 10.856 g of Ce(NO3)3·6H2O, and 0-4.97 g of FeCl2·4H2O were added to every 150 mL of the aqueous solution.

[0031] The beneficial effect of adopting the above further technical solution is that the mixed ions can be easily mixed evenly.

[0032] Furthermore, in step (1), the molar fraction of the dilute ammonia aqueous solution is 26.09-29.16%, and the pH is adjusted to 8.8-9.0.

[0033] The beneficial effects of adopting the above further technical solution are: adjusting the pH of the solution and promoting the formation of isomorphous substitution precipitates.

[0034] Furthermore, in step (1), the above-mentioned standing aging time is 60 minutes, and the aging temperature is a constant temperature of 30° C. in a water bath.

[0035] Furthermore, in step (1), the precipitate is centrifuged and then washed with deionized water until the pH does not change, the drying temperature is 100° C., and the drying time is 6 h.

[0036] Furthermore, in step (2), the calcination atmosphere is air.

[0037] Furthermore, in step (2), the calcination temperature is 700°C, and the heating program is as follows: the heating rate is 5°C / min to 450°C, and then continues to rise to 700°C at 8°C / min.

[0038] Furthermore, in step (2), the calcination time is 2 hours.

[0039] The beneficial effects of adopting the above-mentioned further technical solution are: an appropriate amount of Fe isomorphous substitution is beneficial to the lattice distortion of CeO2, reducing the electron transfer resistance, while increasing the content of oxygen vacancies and Lewis acid active sites, enhancing the adsorption of ozone and decomposition to produce active oxygen species.

[0040] The present invention also provides the above-mentioned Fe@CeO 2-x The application of / MgO isomorphous substitution catalytic ozone oxidation nanocatalysts to mineralize antibiotics in ozone systems is applied to the catalytic ozone mineralization degradation of the antibiotic tetracycline, thereby significantly reducing the generation potential of disinfection by-products with tetracycline hydrochloride as a precursor. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0042] Figure 1 TEM image (a) of CeO2 / MgO and HRTEM image (b) of CeO2 / MgO in comparative example 1, and 0.5Fe@CeO in example 3. 2-x TEM image (c) and HRTEM image (d) of / MgO;

[0043] Figure 2 The CeO2 / MgO in Comparative Example 1 and the 0.5Fe@CeO in Example 3 2-x Oxygen temperature-programmed desorption spectrum of / MgO;

[0044] Figure 3 The CeO2 / MgO in Comparative Example 1 and the 0.5Fe@CeO in Example 3 2-x / MgO XRD pattern;

[0045] Figure 4 The CeO2 / MgO in Comparative Example 1 and the 0.5Fe@CeO in Example 3 2-x Pyridine infrared adsorption spectrum of / MgO;

[0046] Figure 5 The CeO2 / MgO in Comparative Example 1 and the 0.1Fe@CeO in Examples 1-5 are 2-x / MgO、0.3Fe@CeO 2-x / MgO、0.5Fe@CeO 2-x / MgO、0.7Fe@CeO 2-x / MgO、1.0Fe@CeO 2-x Schematic diagram of the mineralization efficiency of TCH by / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst;

[0047] Figure 6 This is a graph showing the effect of different catalyst dosages on the mineralization of tetracycline hydrochloride in the system;

[0048] Figure 7 This is a graph showing the effect of different ozone concentrations on the mineralization of tetracycline hydrochloride in the system;

[0049] Figure 8 This is a graph showing the effect of different initial tetracycline hydrochloride concentrations on the mineralization of tetracycline hydrochloride in the system;

[0050] Figure 9This is a graph showing the effect of different initial pH on the mineralization of tetracycline hydrochloride in the system;

[0051] Figure 10 It is 0.5Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst reduces the generation potential of three disinfection by-products: trichloromethane (TCM), dichloroacetonitrile (DCAN), and dichloroacetic acid (DCAA). DETAILED DESCRIPTION

[0052] Example 1

[0053] This embodiment provides a 0.1Fe@CeO 2-x The preparation method of a nanocatalyst for catalytic ozone oxidation using isomorphous substitution of MgO comprises the following steps:

[0054] 24.647 g of MgSO4·7H2O, 10.856 g of Ce(NO3)3·6H2O, and 0.497 g of FeCl2·4H2O were dissolved in deionized water to obtain a mixed solution 1, and the pH value of the obtained mixed solution 1 was adjusted to 8.8-9.0 with dilute ammonia water. The mixed solution 1 was allowed to stand and age for 60 minutes, centrifuged, washed with deionized water until the pH no longer changed, and dried to obtain a Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder; the obtained Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder was ground and placed in a crucible under an air atmosphere at 700°C for calcination for 2 hours, and naturally cooled to obtain the 0.1Fe@CeO2 / MgO nanocatalyst.

[0055] Example 2

[0056] This embodiment provides a 0.3Fe@CeO 2-x The preparation method of the nanocatalyst for catalytic ozone oxidation by isomorphous substitution of / MgO is different from that in Example 1, in that the mass of the added FeCl2·4H2O is 1.491 g, and the other steps and conditions are the same as those in Example 1.

[0057] Example 3

[0058] This embodiment provides a 0.5Fe@CeO 2-x The preparation method of the nanocatalyst for catalytic ozone oxidation by isomorphous substitution of / MgO is different from that in Example 1, in that the mass of the added FeCl2·4H2O is 2.485 g, and the other steps and conditions are the same as those in Example 1.

[0059] Example 4

[0060] This embodiment provides a 0.7Fe@CeO 2-xThe preparation method of the nanocatalyst for catalytic ozone oxidation by isomorphous substitution of / MgO is different from that in Example 1, in that the mass of the added FeCl2·4H2O is 3.479 g, and the other steps and conditions are the same as those in Example 1.

[0061] Example 5

[0062] This embodiment provides a 1.0Fe@CeO 2-x The preparation method of the nanocatalyst for catalytic ozone oxidation by isomorphous substitution of / MgO is different from that in Example 1, in that the mass of the added FeCl2·4H2O is 4.970 g, and the other steps and conditions are the same as those in Example 1.

[0063] Comparative Example 1

[0064] This embodiment provides a method for preparing a CeO2 / MgO nanocatalyst, comprising the following steps:

[0065] 24.647 g of MgSO4·7H2O and 10.856 g of Ce(NO3)3·6H2O were dissolved in deionized water to obtain a mixed solution 1, the pH value of the obtained mixed solution 1 was adjusted to 8.8-9.0 with dilute ammonia water, the mixed solution 1 was allowed to stand and age for 60 minutes, centrifuged and then washed with deionized water until the pH no longer changed, and dried to obtain a Ce(OH)3 / Mg(OH)2 mixed powder; the obtained Ce(OH)3 / Mg(OH)2 mixed powder was ground and placed in a crucible under an air atmosphere at 700°C for calcination for 2 hours, and naturally cooled to obtain the CeO2 / MgO nanocatalyst.

[0066] Test Example 1

[0067] The 0.5Fe@CeO 2-x The TEM characterization of the nano-catalyst of ozone oxidation catalyzed by isomorphous substitution of CeO2 / MgO and the undoped Fe CeO2 / MgO of comparative example 1 was performed. Figure 1 It can be seen that the prepared CeO2 / MgO powder is a layered structure composed of nanosheets, the lattice spacing of CeO2 is 0.319nm, and the 0.5Fe@CeO 2-x It can be clearly observed that the lattice spacing of CeO2 is 0.302nm in the / MgO composite material. The isomorphous substitution of Fe causes the lattice spacing of CeO2 to shrink, reducing the electron transmission resistance, which is beneficial to the absorption of ozone, organic matter and 0.5Fe@CeO 2-x / MgO electron transfer.

[0068] Test Example 2

[0069] The 0.5Fe@CeO 2-xThe / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst and the undoped Fe CeO2 / MgO of comparative example 1 were characterized by oxygen temperature programmed desorption. Figure 2 It can be seen that 0.5Fe@CeO 2-x The surface lattice oxygen desorption temperature of CeO2 / MgO (491 °C) is significantly lower than that of CeO2 / MgO, which improves the mobility of surface oxygen and makes it easier to replenish and activate more lattice oxygen.

[0070] Test Example 3

[0071] The 0.5Fe@CeO 2-x The XRD characterization of the nano-catalyst of ozone oxidation catalyzed by isomorphous substitution of CeO2 / MgO and the undoped Fe CeO2 / MgO of comparative example 1 was carried out. Figure 3 It can be seen that all peaks of CeO2 / MgO are consistent with the standard card (PDF#43-1002), indicating that CeO2 / MgO nanomaterials were successfully prepared. 2-x / MgO, obvious Fe2O3 characteristic diffraction peaks were observed at 2θ = 24.1°, 33.1°, 35.6°, 49.5°, 54.1°, 62.4° and 64.0°, indicating that Fe was successfully introduced into CeO2.

[0072] Test Example 4

[0073] The 0.5Fe@CeO 2-x Pyridine infrared adsorption spectrum analysis was performed on the CeO2 / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst and the undoped Fe CeO2 / MgO of comparative example 1. Figure 4 Compared with CeO2 / MgO, 0.5Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst has stronger Lewis acid active sites.

[0074] Experimental Example 1

[0075] The performance evaluation experiment of the prepared catalytic material for catalytic ozone oxidation mineralization of tetracycline hydrochloride (TCH) includes the following methods:

[0076] The 0.1Fe@CeO prepared in Examples 1-5 and Comparative Example 1 2-x / MgO,0.3Fe@CeO 2-x / MgO,0.5Fe@CeO 2-x / MgO,0.7Fe@CeO 2-x / MgO,1.0Fe@CeO 2-x / MgO and CeO2 / MgO nanocatalysts were used to mineralize tetracycline (TCH). 2L of 20mg / L TCH solution with a pH of 6 was prepared and placed in a reaction device. 500mg of 0.1Fe@CeO 2-x / MgO,0.3Fe@CeO 2-x / MgO,0.5Fe@CeO 2-x / MgO,0.7Fe@CeO 2-x / MgO,1.0Fe@CeO 2-x / MgO and CeO2 / MgO nanocatalysts, 4.25 mg / L ozone was prepared using an ozone generator and introduced into the reactor through a titanium alloy aeration head. The total organic carbon residual concentration was measured every 15 minutes. The TCH mineralization effect in the ozone system within 60 minutes was as follows: Figure 5 As shown, compared with CeO2 / MgO, 0.5Fe@CeO 2-x The degradation performance of nanomaterials catalyzed by ozone oxidation with MgO was the most improved, with the mineralization rate and mineralization rate of TCH reaching 68.5% and 0.0103 min, respectively. -1 , while the mineralization rate and mineralization rate of CeO2 / MgO were only 61.5% and 0.0204min respectively. -1 The above results show that 0.5Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst has the best demineralization ability and can mineralize pollutants quickly and efficiently.

[0077] Experimental Example 2: Effect of Catalyst Concentration on TCH Mineralization

[0078] This experimental example uses the 0.5Fe@CeO 2-x / MgO was used to conduct an experiment on the effect of catalyst concentration on TCH mineralization. Except for the different catalyst dosage, the rest of the operation was the same as that of Experimental Example 1. 2-x The concentrations of / MgO are 0 mg / L, 250 mg / L, 500 mg / L, 1000 mg / L, and 1500 mg / L, respectively.

[0079] like Figure 6 As shown in the figure, total organic carbon removal significantly increased when the catalyst dosage increased from 250 mg / L to 500 mg / L. However, further increasing the catalyst dosage to 1500 mg / L only slightly improved the total organic carbon removal rate. Increased catalyst exposure increases the total number of active sites, thereby accelerating the reaction process. However, due to the limited amount of oxidant added, catalytic activity does not increase indefinitely with increasing catalyst exposure. Therefore, the optimal catalyst dosage was determined to be 500 mg / L.

[0080] Experimental Example 3: Effect of ozone concentration on TCH mineralization

[0081] This experimental example uses the 0.5Fe@CeO 2-x The effect of catalyst concentration on TCH mineralization effect was tested using MgO / MgO. Except for the different ozone concentration, the rest of the operations were the same as those in Experimental Example 1, where the ozone concentrations were 0 mg / L, 0.74 mg / L, 2.96 mg / L, 4.25 mg / L, and 6.40 mg / L, respectively.

[0082] like Figure 7 As shown in the figure, as the liquid ozone concentration increased from 0.74 mg / L to 6.40 mg / L, the mineralization rate of TCH increased from 13% to 80%. Since the difference in total organic carbon removal efficiency between ozone dosages of 4.25 mg / L and 6.40 mg / L was not significant, the optimal ozone dosage was determined to be 4.25 mg / L.

[0083] Experimental Example 4: Effect of TCH initial concentration on TCH mineralization effect

[0084] This experimental example uses the 0.5Fe@CeO 2-x The effect of catalyst concentration on TCH mineralization effect was tested using MgO / MgO. Except for the different initial TCH concentrations from the experimental example, the rest of the operations were the same as those in Experimental Example 1, where the initial TCH concentrations were 10 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L, respectively.

[0085] like Figure 8 As shown in the figure, low concentrations of TCH will quickly enter the mineralization stage, while high concentrations of TCH require more oxidants to be converted into small molecules. Therefore, the result is that low concentrations of TCH are mineralized quickly, while high concentrations of TCH enter the mineralization stage slowly.

[0086] Experimental Example 5: Effect of pH on TCH mineralization

[0087] This experimental example uses the 0.5Fe@CeO 2-x / MgO was used to conduct an experiment on the effect of catalyst concentration on the mineralization effect of tetracycline hydrochloride. Except for the initial pH, the other operations were consistent with those in Experimental Example 1, where the initial pH was 4, 6, 8, and 10, respectively.

[0088] like Figure 9As shown in the figure, the effect of pH on ozone, catalyst and TCH will lead to changes in the mineralization removal rate. First, ozone is very unstable in alkaline solution, and hydroxide will trigger ozone to form hydroxyl radicals, which will then react with ozone. The decomposition products of ozone are conducive to the mineralization of TCH, so at pH = 10 and 8, the total organic carbon removal rate is accelerated. When the solution pH is less than the zero charge of the catalyst, the surface hydroxyl is protonated and positively charged, otherwise, the surface hydroxyl is deprotonated and negatively charged. When the catalyst surface is neutral or positively charged, the generation of free radicals will be enhanced. Due to the 0.5Fe@CeO 2-x The zero-point charge of / MgO is 4.30, so the removal rate of total organic carbon at pH = 4 is slightly faster than that at pH = 6.

[0089] Experimental Example 6

[0090] The 0.5Fe@CeO prepared in Example 3 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst was used to mineralize tetracycline (TCH) and at the same time weaken the formation potential of three disinfection by-products: TCM, DCAN, and DCAA. 2L of 20mg / L TCH solution with a pH of 6 was prepared and placed in the reaction device. During the experiment, 500mg0.5Fe@CeO 2-x / MgO, 4.25mg / L ozone was prepared by an ozone generator and introduced into the reactor through a titanium alloy aeration head, and samples were taken every 15 minutes. 2L of 20mg / L TCH solution was prepared and placed in the reaction device, and 500mg 0.5Fe@CeO 2-x / MgO nanoparticles, ozone was prepared using an ozone generator and introduced into the reactor through a titanium alloy aeration head. Samples were taken every 15 minutes to measure the concentrations of TCM, DCAN, and DCAA. Within 60 minutes, the concentrations of TCM, DCAN, and DCAA in the ozone system were as follows: Figure 10 (a) Figure 10 (b) Figure 10 As shown in (c), 0.5Fe@CeO 2-x / MgO catalytic ozone oxidation nanomaterials can significantly reduce the generation potential of TCM, DCAN, and DCAA disinfection by-products by 55%, 34%, and 86%, respectively.

Claims

1. An isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO 2-x The preparation method of / MgO comprises the following steps: (1) MgSO4·7H2O, Ce(NO3)3·6H2O and FeCl2·4H2O were dissolved in deionized water to obtain a mixed solution 1, the pH value of the obtained mixed solution 1 was adjusted to 8.8-9.0 with dilute ammonia water, the mixed solution 1 was allowed to stand for 60 minutes, centrifuged, washed with deionized water until the pH value no longer changed, and dried to obtain a Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder; (2) The Fe(OH)2 / Ce(OH)3 / Mg(OH)2 mixed powder was ground and placed in a crucible and calcined in an air atmosphere at 700°C for 2 hours, and the Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst, x represents the oxygen vacancy content.

2. An isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (1), the molar fraction of the dilute ammonia water is 26.09-29.16%, and the pH is adjusted to 8.8-9.

0.

3. The isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (1), the standing aging time is 60 minutes, and the aging temperature is a constant temperature of 30° C. in a water bath.

4. The isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (1), FeCl2·4H2O accounts for 0, 1.96%, 5.67%, 9.09%, 12.28%, and 16.67% of the total molar amount of catalyst metal atoms, respectively. The rest is MgSO4·7H2O and Ce(NO3)3·6H2O. The atomic molar ratio of Mg to Ce is fixed at 4:

1. According to the different molar amounts of Fe atoms, they are named CeO2 / MgO, 0.1Fe@CeO, and 0.1Fe@CeO. 2-x / MgO、0.3Fe@CeO 2-x / MgO、0.5Fe@CeO 2-x / MgO、0.7Fe@CeO 2-x / MgO、1.0Fe@CeO 2-x / MgO, the incorporation of iron elements can prepare catalysts rich in different oxygen vacancy contents.

5. The isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (2), the calcination atmosphere is air.

6. The isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (2), the calcination temperature is 700° C. The heating program is as follows: heating rate of 5° C. / min to 450° C., and then heating rate of 8° C. / min to 700° C.

7. The isomorphous substitution catalytic ozone oxidation nanocatalyst Fe@CeO according to claim 1 2-x / MgO preparation method, characterized in that, In step (2), the calcination time is 2 hours.

8. The use according to any one of claims 1 to 7, characterized in that Fe@CeO 2-x The steps of mineralizing tetracycline hydrochloride catalytic ozone oxidation using a nano-catalyst for catalytic ozone oxidation using isomorphous substitution of MgO include: preparing Fe@CeO with different molar amounts of FeCl2·4H2O. 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst is added into wastewater containing tetracycline hydrochloride, ozone is introduced, and catalytic oxidation is performed using the reaction system.

9. The use according to claim 8, characterized in that The Fe@CeO 2-x / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst mineralizes tetracycline hydrochloride in a closed system; and / or the 0.5Fe@CeO 2-x / MgO concentration in the reaction system is 0.25g / L-1.5g / L; and / or the concentration of ozone in the reaction system is 0.74 mg / L-6.4 mg / L; and / or the concentration of tetracycline hydrochloride in the reaction system is 10 mg / L-40 mg / L; And / or the pH of the reaction system is 4-10.

10. A 0.5Fe@CeO 2-x 0.5Fe@CeO prepared by the preparation method of / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst 2-x Application of / MgO isomorphous substitution catalytic ozone oxidation nanocatalyst in controlling the generation potential of disinfection by-products, characterized in that, While degrading mineralized tetracycline, it can also effectively reduce the generation potential of tetracycline's chlorination disinfection by-products, including chloroform, dichloroacetonitrile, and dichloroacetic acid.

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