Copper-doped R-P phase perovskite type catalyst and preparation method and application thereof

Abstract

The invention belongs to the technical field of treatment of organic pollutants in water by persulfate (PMS), and particularly discloses a copper-doped R-P phase perovskite type catalyst as well as a preparation method and application of the copper-doped R-P phase perovskite type catalyst. Through synergistic Jahn-Teller distortion and B-site redox cycle, Cu doping induces anisotropic lattice strain and improves oxygen vacancy density, so that a double-free-radical (. OH / . O2-) and non-free-radical (1O2 / electron transfer process (ETP) pathway is realized. The density functional theory reveals that the adsorption energy of the catalyst to PMS is optimized while the center of a d band of a Cu-mediated Ni 3d orbit moves downwards. The catalyst keeps the efficiency of 90% after running for 100 h, and shows pH elasticity (3-11) and anti-interference performance (LVFX removal efficiency gt under the humic acid condition of 20mg / L); 85%).

Description

Technical Field

[0001] The present invention relates to the technical field of treating organic pollutants in water with persulfate (PMS), in particular to a copper-doped R-P phase perovskite-type catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] The global abuse of antibiotics has become a non-negligible anthropogenic pollution source in the water ecosystem, posing a major threat to public health safety and ecological integrity. Fluoroquinolone antibiotics, with their broad-spectrum bactericidal properties, have shown excellent efficacy in combating a variety of pathogenic microorganisms. As a representative of the third-generation fluoroquinolone drugs, levofloxacin (LVFX) exhibits significant antibacterial activity against both Gram-positive and Gram-negative bacteria. However, the continuous detection of LVFX residues in various water bodies such as surface water, groundwater, and drinking water exposes the limitations of traditional biological treatment technologies. Due to its environmental persistence characteristics such as high water solubility, chemical stability, and anti-biodegradability, it is difficult for conventional water treatment processes to completely remove this pollutant. The above technical bottlenecks need to be broken through urgently, and new and efficient water body restoration technologies are urgently needed to achieve the effective degradation of LVFX.

[0003] Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) have shown important application potential in the field of treating trace organic pollutants because they can generate reactive oxygen species (ROS) through efficient activation pathways. The unique asymmetric structure of the PMS molecule and the bond length characteristics of the peroxy bond (O-O) endow it with a stronger activation tendency, and it can generate hydroxyl radicals (·OH), sulfate radicals (SO 4· - ), singlet oxygen ( 1 O 2 ) and superoxide radicals (·O 2 - ) and other diverse ROS. Although traditional homogeneous activation systems (such as Fe 2+ / Co 2+ ) have been proven to have the ability to activate PMS, their inherent defects - difficult separation of metal ions, difficulty in recovering catalysts, and the risk of secondary pollution caused by metal leaching - severely restrict their practical environmental applications. This situation has promoted the rapid development of heterogeneous catalytic systems with cost-effectiveness, ecological compatibility, and high PMS activation performance.

[0004] Perovskite oxides (ABO 3 ) have shown potential in the field of PMS activation due to their adjustable electronic structure and high redox activity. However, traditional perovskites have defects such as low specific surface area and limited active sites, and it is difficult for a single B-site metal to synergistically optimize the adsorption and activation processes of PMS. Ruddlesden-Popper (R-P) layered perovskites (A 2 BO4 ) Due to its unique two-dimensional structure (alternating stacked ABO 3 layers and AO layers, Figure 1 a), more active crystal planes can be exposed by interlayer strain regulation, and the oxygen vacancy concentration and metal valence state distribution can be flexibly adjusted by means of A / B-site multi-element doping. As the key active site, oxygen vacancies can not only act as electron donors to promote PMS adsorption and O-O bond cleavage, but also directly participate in the surface redox cycle to regulate the generation path and selectivity of ROS. Research shows that the introduction of transition metals (Co, Fe, Mn, Cu, etc.) can significantly enhance the heterogeneous cleavage efficiency of PMS by improving the electron mobility and surface Lewis acidity. More importantly, the rapid electron transfer ability between different valence state metal cations at the B-site endows it with strong redox activity, which is beneficial to PMS activation. For example, materials such as LaCo 1-x Mn x O 3 +δ, LaCo x Fe 1-x O 3 +δ and Cu-LaMnO 3 etc. can effectively induce the generation of oxygen vacancies, realizing ROS regulation and performance improvement of PMS activation. However, the influence mechanism of the metal doping strategy in R-P perovskite on its PMS activation path still needs to be further studied. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a copper-doped R-P phase perovskite-type catalyst, its preparation method and application.

[0006] To achieve the above object, the present invention is implemented according to the following technical scheme:

[0007] One of the technical solutions of the present invention is a preparation method of a copper-doped R-P phase perovskite-type PMS catalyst, comprising the following steps:

[0008] S1. Take La with a molar ratio of 0.6:0.8:1-(0.1-0.5):(0.1-0.5) 2 O 3 , Sr(NO 3 ) 2 , Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·3H 2 O and dissolve them in 60 mL of deionized water in sequence, and then add citric acid as a chelating agent, and the molar ratio of the citric acid to all metal ions is 1.5:1;

[0009] S2. Then, adjust the pH value of the above mixture to 7. After continuously stirring for 2 hours, then transfer the mixture to an evaporating dish, heat to evaporate the water while continuing to stir until it becomes a viscous gel;

[0010] S3. Subsequently, ignite and burn the gel to generate a precursor, then place the precursor in an alumina crucible and calcine it in air at 900 °C for 3 h, and naturally cool it to room temperature;

[0011] S4. Finally, wash, dry, and grind the product to obtain a copper-doped R-P phase perovskite-type catalyst LSNC x , 0.1 ≤ x ≤ 0.5.

[0012] Further, in the step S2, NH 3 H 2 O is used to adjust the pH value of the mixture.

[0013] Preferably, the molar ratio of La 2 O 3 , Sr(NO 3 ) 2 , Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·3H 2 O is 0.6:0.8:0.7:0.3, and finally a copper-doped R-P phase perovskite-type catalyst LSNC 0.3 is obtained.

[0014] The second technical solution of the present invention is a copper-doped R-P phase perovskite-type catalyst prepared by the above method.

[0015] The third technical solution of the present invention is an application of a copper-doped R-P phase perovskite-type catalyst in activating PMS to degrade antibiotic wastewater. The addition amount of PMS in the antibiotic wastewater is 0.3 g / L, the addition amount of the catalyst is 0.2 g / L, the initial pH of the antibiotic wastewater is 7, and the treatment temperature is 30 °C.

[0016] Preferably, the antibiotic is one or more of levofloxacin, enrofloxacin, ciprofloxacin, tetracycline, carbamazepine, and sulfamethoxazole; more preferably, the antibiotic is levofloxacin, and LSNC 0.3 exhibits the highest catalytic performance for the degradation of levofloxacin.

[0017] Compared with the prior art, when the copper-doped R-P phase perovskite catalyst prepared by the present invention is used to activate PMS for the catalytic degradation of the antibiotic levofloxacin, through the synergistic Jahn-Teller distortion and B-site redox cycle, Cu doping induces anisotropic lattice strain and increases the oxygen vacancy density, thereby realizing the dual-radical (·OH / ·O 2 - ) and non-radical ( 1 O 2 / electron transfer process (ETP)) pathways. Density functional theory reveals that while the Cu-mediated downward shift of the d-band center of the Ni 3d orbitals optimizes the adsorption energy of the catalyst for PMS. The catalyst maintains 90% efficiency after 100 h of operation, showing pH flexibility (3 - 11) and anti-interference ability (LVFX removal efficiency > 85% under the condition of 20 mg / L humic acid). Description of the Drawings

[0018] Figure 1 :(a) Structure diagrams of ABO3 perovskite (left) and R-P phase perovskite (right); (b) Schematic diagram of the synthesis process of LSNC x (x = 0.1, 0.2, 0.3, 0.4, 0.5); (c) XRD refined pattern of LSNC 0.3 (R pf , R wp , R exp and χ 2 represent the profile factor, weighted profile factor, expected weighted profile factor, and reduced chi-square, respectively); (d) XRD pattern of the catalyst; (e) Peak comparison of LSNC x (x = 0.1, 0.2, 0.3, 0.4, 0.5) in the range of 2θ from 27 - 29°; (f) Peak comparison of LSNC x (x = 0.1, 0.2, 0.3, 0.4, 0.5) in the range of 2θ from 32 - 34°; (g) SEM image of LSNC 0.3 ; (h) TEM image of LSNC 0.3 ; (i) HRTEM image of LSNC 0.3 ; (j) SEAD pattern of LSNC 0.3 .

[0019] Figure 2 : XPS spectra of LSNO and LSNC0.3: (a) Ni 3p; (b) Cu 2p; (c) O 1s; (d) Schematic diagram of the crystal structure change after Cu doping of LSNO; (e) EPR spectra of LSNO and LSNC0.3; Comparison of the electrochemical test results of LSNO and LSNC0.3: (f) CV curve; (g) EIS Nyquist curve; (h) Tafel polarization curve.

[0020] Figure 3 : (a) Degradation curves of LVFX removed by different catalysts; (b) Comparison of degradation kinetics of LVFX in recently reported catalysts; (c) Pseudo-first-order kinetic model of degradation data of LVFX in the catalyst / PMS system; (d) Influence of water environment on LVFX degradation in the LSNC 0.3 / PMS system; (e) Influence of initial pH value on LVFX degradation in the LSNC 0.3 / PMS system; (f) Influence of HA concentration on LVFX degradation in the LSNC 0.3 / PMS system; (g) Continuous flow experiment of LVFX removal by the LSNC 0.3 / PMS system; (h) Cycling test (test conditions: [C 0 = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7).

[0021] Figure 4 Degradation curves of LVFX removed by different catalysts (LSNC X (x = 0.1, 0.2, 0.4, 0.5)) (conditions: [C 0 = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7).

[0022] Figure 5 Degradation of various antibiotics by the LSNC0.3 / PMS system (conditions: [Co] = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7).

[0023] Figure 6 XRD patterns of fresh and used LSNC0.3 catalysts.

[0024] Figure 7 Influence of environmental temperature on LVFX degradation by the LSNC0.3 / PMS system (conditions: [Co] = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7).

[0025] Figure 8 Influence of the LSNC0.3 / PMS system on LVFX degradation: (a) Catalyst dosage, (B) PMS concentration, (c) Coexisting anions (conditions: [C 0 = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7).

[0026] Figure 9 By fitting the XPS spectra of LSNC 0.3 and LSNO, the surface average valence states of cations (Mn+) in different valence states and the B-site cation n(B) were obtained.

[0027] Figure 10 XPS spectra of LSNO and LSNC 0.3 catalysts: (a) La 3d; (B) Sr 3d.

[0028] Figure 11 : (a) SEM image of LSNO; (b) particle size distribution of LSNO, obtained by statistical analysis of the SEM image; (c) LSNC 0.3 Particle size distribution of the catalyst, obtained by statistical analysis of the SEM image.

[0029] Figure 12 Effect of quencher on the degradation of LVFX in LSNC0.3 / PMS and LSNO / PMS systems: (a) degradation curves; (b) fitted rate constant k; (c) contributions of various reactive species; (d) DMPO-·O2- and TEMP- 1 O 2 and EPR spectra of DMPO-·OH; (e) LSV curves under different test conditions (f) i-t curve of LSNC0.3 (g) in-situ Raman spectra before and after PMS reaction XPS spectra of fresh and used LSNC0.3: (h) Ni 3p (i) Cu 2p (j) O 1s.

[0030] Figure 13 For the comparison of electrochemical test results of LSNO and LSNC 0.3 : (a) CV curves, (B) EIS Nyquist curves, (c) Tafel polarization curves, (d) LSV curves under different conditions. XPS spectra of fresh and used LSNC0.3 catalysts: (e) high-resolution spectra of Ni 2p of fresh and used LSNC0.3 catalysts; (f) high-resolution spectra of Cu 2p of fresh and used LSNC0.3 catalysts; (g) high-resolution spectra of O1S of fresh and used LSNC0.3 catalysts; (h) changes in valence state contents of Ni and Cu.

[0031] Figure 13 LSV curves of LSNO under different conditions.

[0032] Figure 14 For the i-t curve of LSNC 0.3

[0033] Figure 15 For LSNC 0.3 / PMS system on the degradation of LVFX: (a) K 2 Cr 2 O 7 ; (b) DMSO (conditions: [C0]=5mg / L, [PMS]=0.3g / L, [catalyst]=0.2g / L, T = 30 °C, initial pH = 7).

[0034] Figure 16 XPS spectra of fresh and used LSNC 0.3 catalyst: (a) measured spectrum; (b) La 3d; (c) Sr 3d.

[0035] Figure 17 : (a) LSNC 0.3 / PMS system degradation mechanism of LVFX; (b) structure of LVFX; (c) ESP spectrum of LVFX, (d) HOMO energy level of LVFX, (e) LUMO energy level of LVFX, (f) four possible degradation pathways A, B, C, D of LVFX in LSNC0.3 / PMS system; (g) toxicity of LVFX and degradation intermediates estimated based on six indicators of T.E.S.T.

[0036] Figure 18 For Fukui function index: f - , f + , f 0 and CDD.

[0037] Figure 19 For Fukui function values.

[0038] Figure 20 3D EEMS fluorescence spectra of LVFX solution when adding PMS: (a) 0 min; (b) 5 min; (c) 30 min. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further details the present invention in combination with embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the invention.

[0040] All chemical reagents used in the following embodiments are commercially available unless otherwise specified.

[0041] Example 1

[0042] 1) Take La with a molar ratio of 1:1:1:0.1 2 O 3 , Sr(NO 3 ) 2, Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·3H 2 O were successively dissolved in 60 mL of deionized water, and then citric acid was added as a chelating agent. The molar ratio of the citric acid to all metal ions was 1.5:1;

[0043] 2) Then, the pH value of the above mixture was adjusted to 7 with NH 3 H 2 O. After continuously stirring for 2 hours, the mixture was then transferred to an evaporating dish, and the water was heated and evaporated while continuing to stir until it became a viscous gel;

[0044] 3) Subsequently, the gel was ignited and burned to generate a precursor, and then the precursor was placed in an alumina crucible and calcined in air at 900 °C for 3 h and naturally cooled to room temperature;

[0045] 4) Finally, the product was washed, dried, and ground to obtain a copper-doped R-P phase perovskite-type catalyst LSNC 0.1 , and the specific preparation process was as shown in (a) in Figure 1 .

[0046] Example 2

[0047] 1) Take La 2 O 3 , Sr(NO 3 ) 2 , Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·3H 2 O with a molar ratio of 1:1:1:0.2 and successively dissolve them in 60 mL of deionized water, and then add citric acid as a chelating agent. The molar ratio of the citric acid to all metal ions was 1.5:1;

[0048] 2) Then, the pH value of the above mixture was adjusted to 7 with NH 3 H 2 O. After continuously stirring for 2 hours, the mixture was then transferred to an evaporating dish, and the water was heated and evaporated while continuing to stir until it became a viscous gel;

[0049] 3) Subsequently, the gel was ignited and burned to generate a precursor, and then the precursor was placed in an alumina crucible and calcined in air at 900 °C for 3 h and naturally cooled to room temperature;

[0050] 4) Finally, wash, dry, and grind the product to obtain the copper-doped R-P phase perovskite catalyst LSNC 0.2 , as specifically shown in (a) of Figure 1 .

[0051] Example 3

[0052] 1) Take La, Sr(NO 2 O 3 ), Ni(NO 3 ), and Cu(NO 2 ), Ni(NO 3 ), and Cu(NO 2 ·6H 2 O and Cu(NO 3 ), and Cu(NO 2 ·3H 2 O and dissolve them in 60 mL of deionized water in sequence. Then, add citric acid as a chelating agent, and the molar ratio of citric acid to all metal ions is 1.5:1;

[0053] 2) Then, use NH 3 H 2 O to adjust the pH value of the above mixture to 7. After continuously stirring for 2 hours, then transfer the mixture to an evaporating dish, heat to evaporate the water, and continue stirring until it becomes a viscous gel;

[0054] 3) Subsequently, ignite and burn the gel to generate a precursor, and then place the precursor in an alumina crucible and calcine it in air at 900 °C for 3 h, and naturally cool it to room temperature;

[0055] 4) Finally, wash, dry, and grind the product to obtain the copper-doped R-P phase perovskite catalyst LSNC 0.4 , as specifically shown in (a) of Figure 1 .

[0056] Example 4

[0057] 1) Take La, Sr(NO 2 O 3 ), Ni(NO 3 ), and Cu(NO 2 ), Ni(NO 3 ), and Cu(NO 2 ·6H 2 O and Cu(NO 3 ), and Cu(NO 2 ·3H 2 O and dissolve them in 60 mL of deionized water in sequence. Then, add citric acid as a chelating agent, and the molar ratio of citric acid to all metal ions is 1.5:1;

[0058] 2) Then, use NH3 H 2 Adjust the pH value of the above mixture to 7. After continuously stirring for 2 hours, then transfer the mixture to an evaporating dish, heat to evaporate the water while continuing to stir until it becomes a viscous gel;

[0059] 3) Subsequently, ignite and burn the gel to generate a precursor, then place the precursor in an alumina crucible and calcine it in air at 900 °C for 3 h, and naturally cool it to room temperature;

[0060] 4) Finally, wash, dry, and grind the product to obtain a copper-doped R-P phase perovskite-type catalyst LSNC 0.5 , and the specific preparation process is as shown in (a) of Figure 1 .

[0061] Example 5

[0062] 1) Take La with a molar ratio of 1:1:1:0.3 2 O 3 , Sr(NO 3 ) 2 , Ni(NO 3 ) 2 ·6H 2 O and Cu(NO 3 ) 2 ·3H 2 O and dissolve them in 60 mL of deionized water in sequence, then add citric acid as a chelating agent, and the molar ratio of the citric acid to all metal ions is 1.5:1;

[0063] 2) Then, use NH 3 H 2 O to adjust the pH value of the above mixture to 7. After continuously stirring for 2 hours, then transfer the mixture to an evaporating dish, heat to evaporate the water while continuing to stir until it becomes a viscous gel;

[0064] 3) Subsequently, ignite and burn the gel to generate a precursor, then place the precursor in an alumina crucible and calcine it in air at 900 °C for 3 h, and naturally cool it to room temperature;

[0065] 4) Finally, wash, dry, and grind the product to obtain a copper-doped R-P phase perovskite-type catalyst LSNC 0.3 , and the specific preparation process is as shown in (a) of Figure 1 .

[0066] Comparative Example 1

[0067] 1) Take La with a molar ratio of 1:1:1 2 O 3 , Sr(NO 3 )2 and Ni(NO 3 ) 2 ·6H 2 O were successively dissolved in 60 mL of deionized water, and then citric acid was added as a chelating agent. The molar ratio of the citric acid to all metal ions was 1.5:1;

[0068] 2) Then, the pH value of the above mixture was adjusted to 7 with NH 3 H 2 O. After continuously stirring for 2 hours, the mixture was then transferred to an evaporating dish, and the water was heated and evaporated while continuing to stir until it became a viscous gel;

[0069] 3) Subsequently, the gel was ignited and burned to form a precursor, and then the precursor was placed in an alumina crucible and calcined in air at 900 °C for 3 h and naturally cooled to room temperature;

[0070] 4) Finally, the product was washed, dried, and ground to obtain the R-P phase perovskite-type catalyst LSNO.

[0071] The catalytic performance of the catalysts prepared in Examples 1-5 and Comparative Example 1 was evaluated by evaluating the pollutant removal rate after activating PMS. The specific operation process was as follows:

[0072] An aqueous solution of LVFX with an initial concentration of 5 mg / L was prepared with deionized water, and the initial pH was adjusted to 7 and T = 30 °C. 20 mg of the catalyst was added to a glass beaker containing 100 mL of the aqueous solution of LVFX. After stirring for 30 min, the mixed solution reached the adsorption equilibrium of the catalyst and the target pollutant. Subsequently, 30 mg of PMS was added to initiate the degradation process of LVFX, and vigorous stirring was performed to ensure complete mixing of the solution. At a predetermined time, 2 ml of the mixed suspension was extracted using a syringe, filtered through a 0.45 μm microporous membrane, and added to a centrifuge tube containing 1 mL of methanol to terminate the catalytic oxidation reaction. Finally, high performance liquid chromatography (HPLC) was used with a C18 separation column as the separation column to detect the drug concentration. The column temperature was controlled at 25 °C, the wavelength of the UV detector was set at 292 nm, the flow rate ratio of the mobile phase was adjusted to A (0.1% formic acid aqueous solution):B (acetonitrile) = 80:20, and the flow rate was 1.0 mL min -1 , and the injection volume and retention time of LVFX were set at 20 μL and 5 min respectively, and the concentration of LVFX was measured; the test results were as Figure 2 、 Figure 3 shown.

[0073] As Figure 2 shown in (a) of 0.3Under individual action, the degradation rates of LVFX within 30 min were 13.6% and 20.8% respectively. However, compared with the 58.0% degradation rate of the LSNO / PMS system, the degradation rate of LVFX by the LSNC 0.3 / PMS system was significantly improved, reaching 94.0%, and the reaction rate constant k reached the maximum value (0.0853 min -1 ). However, with the further increase of copper content, the degradation rate and reaction rate of LVFX decreased slightly (see Figure 3 and Figure 2 for (c)), which may be because copper overload led to the collapse of the perovskite structure, resulting in more metal leaching in the catalytic reaction. In addition, taking the k value and the catalyst dosage as evaluation indexes, the removal effect of the LSNC 0.3 / PMS system on LVFX was compared with that of the heterogeneous catalyst / PMS systems reported recently. As shown in (b) of Figure 2 , LVFX degradation had the highest reaction rate, highlighting the excellent catalytic performance of LSNC 0.3 for PMS activation. More importantly, the LSNC 0.3 / PMS system showed good applicability in the aqueous solution of LVFX (see (d) of Figure 2 ). Therefore, the subsequent examples mainly studied LSNC 0.3 .

[0074] For comparison, referring to Figure 4 , this example also used five other antibiotics, enrofloxacin, ciprofloxacin, tetracycline, carbamazepine, and sulfamethoxazole, to evaluate the applicability of LSNC 0.3 . As shown from top to bottom in Figure 4 are enrofloxacin, ciprofloxacin, tetracycline, carbamazepine, sulfamethoxazole, and levofloxacin. Test conditions: [Co] = 5 mg / L, [PMS] = 0.3 g / L, [catalyst] = 0.2 g / L, T = 30 °C, initial pH = 7; It can be seen from Figure 4 that the LSNC 0.3 / PMS system achieved good removal efficiency for all antibiotics, demonstrating the excellent applicability of the LSNC 0.3 catalyst.

[0075] Furthermore, after adjusting the initial pH value of the aqueous solution of LVFX (pH values were 3, 5, 7, 9, and 11 respectively), the effect of LSNC 0.3 on the removal efficiency of LVFX was studied. It can be seen from (e) of Figure 2 that LSNC 0.3The / PMS system has good tolerance to the pH environment, but it will be affected in a strong alkaline environment (pH = 11). Since excessive OH may cause the catalyst surface to carry a negative charge, restricting the interaction between the catalyst and PMS, this is another important reason for the decrease in the LVFX removal rate in a strong alkaline environment. In addition, LSNC 0.3 The / PMS system shows strong tolerance to HA (see Figure 2 (f) in). More importantly, LSNC 0.3 The catalyst has been proven to have strong stability through a 100-hour long-term test and four-cycle experiments (see Figure 2 (g) in - Figure 2 (h) in). For the cycle test, the used LSNC 0.3 was collected after the reaction, washed 6 times alternately with absolute ethanol and deionized water, and then dried in an oven at 60 °C. The XRD patterns before and after the reaction (see Figure 5 ) show that the characterization results of the catalyst reused 4 times have no significant difference from those of the fresh LSNC 0.3 catalyst, indicating that the crystal structure of the catalyst remains stable after the reaction. LSNC 0.3 The catalyst also exhibits good catalytic performance at different temperatures due to its stable structure (see Figure 6 ).

[0076] In some embodiments, other factors are also considered to prove the catalytic performance and stability of LSNC 0.3 catalyst. When the catalyst dosage increases from 0.2 g / L to 0.4 g / L, the removal rate of LVFX drops to 88.9%, and the k value drops to 0.0624 min -1 (see Figure 7 (a) in). This may be due to the aggregation caused by excessive catalyst, resulting in a decrease in the utilization rate of active sites. In addition, as the PMS concentration increases from 0.1 g / L to 0.3 g / L, both the removal rate of LVFX and the k value increase. When the catalyst dosage increases from 0.2 g / L to 0.4 g / L, the removal rate of LVFX drops to 88.9%, and the k value drops to 0.0624 min -1 (see Figure 7 (b) in). This may be due to the aggregation caused by excessive catalyst, resulting in a decrease in the utilization rate of active sites. In addition, as the PMS concentration increases from 0.1 g / L to 0.3 g / L, both the removal rate of LVFX and the k value increase. However, the removal rate of LVFX and the reaction rate constant slightly decrease from 0.3 g / L to 0.4 g / L (see Figure 7 (b) in). This may be due to LSNC 0.3There are limited active sites for generating free radicals on the surface, and excessive PMS may quench free radicals and form SO with a lower oxidation level 5 - free radicals. Finally, the effects of common anions (HCO 3 - , Cl - , SO 4 2- and H 2 PO 4 - , all with a concentration of 5 mM) on the removal of LVFX were investigated (see (c) in Figure 7 ). The LSNC 0.3 / PMS system operates stably in C l- and SO 4 2- environments, but HCO 3 - and H 2 PO 4 - have a greater impact on the removal of LVFX. This is because the introduction of HCO 3 - will cause a rapid increase in the pH value of the solution, inhibiting the interaction between reaction systems. At the same time, HCO 3- will react with active substances to generate free radical species with relatively weak oxidation ability (HCO 3 - , CO 3 - ). H 2 PO 4 - can also react with SO 4 - and ·OH in the system to generate free radicals with weaker activity (SO 4 2- , ·OH-). The LSNC 0.3 catalyst has good environmental adaptability and stability and has good application potential in environmental pollution treatment.

[0077] Therefore, it is finally determined that when the copper-doped R-P phase perovskite-type catalyst activates PMS to degrade antibiotic wastewater, the optimal dosage of PMS in the antibiotic wastewater is 0.3 g / L, the optimal dosage of the catalyst is 0.2 g / L, the optimal initial pH of the antibiotic wastewater is 7, and the optimal treatment temperature is 30 °C.

[0078] Furthermore, one or more of the catalysts prepared in Examples 1 - 5 and Comparative Example 1 were characterized, and the specific operations were as follows: The crystallinity and purity of the obtained catalysts were detected by X-ray diffraction (XRD) using a Rigaku D / max 2500 X-ray diffractometer (Cu Kα = 0.15406 nm), and the test angle was 10° - 80°; The morphology and microstructure of the samples were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM); The chemical valence states of 5 surface elements of the samples were determined by X-ray photoelectron spectroscopy (XPS), and no pretreatment was required for all samples; Three-dimensional excitation-emission matrix fluorescence spectroscopy (3D EEMs) was performed on a Fluoromax fluorescence spectrophotometer; Electron spin resonance (ESR) signals of sulfate radicals, hydroxyl radicals, superoxide anions, and singlet oxygen were studied using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and 2,2,6,6-tetramethylpiperidine (TEMP) on a JES-FA-200 electron spin resonance spectrometer; The characterization results are as Figure 1 shown.

[0079] The prior art knows that LSNO has a K 2 NiF 4 structure and has I4 / mmm space group symmetry. Figure 1 The XRD refinement results in (b) of 0.3 show that LSNC 2 also has a K 4 NiF 0.3 structure and has I4 / mmm space group symmetry, and reliable parameters ensure the accuracy. The refinement results of LSNC 0.3 show that the d-spacing of some crystal planes in LSNC 0.3 is more significant than that of LSNO, while the d-spacing of some crystal planes is smaller than that of LSNO. The crystal plane spacing of LSNC Figure 1 (c) in Figure 1 shows the XRD patterns of LSNO samples doped with different doses of Cu. It is worth noting that as the Cu content increases, the (004) and (110) planes of the catalyst shift to lower and higher angles respectively (see (d) - Figure 1 in (e)), and the degree of shift is positively correlated with the Cu content, indicating that the octahedral coordination distortion caused by the partial substitution of Cu for Ni leads to the deformation of the irregular structure of the catalyst. The increase in the bond length between cations and oxygen ions weakens the interaction between them, making them more likely to break and lose oxygen ions, thus forming oxygen vacancies. The SEM and TEM results (see (f) - Figure 1 in (g)) show that LSNC Figure 1 ​0.3 The powder presents irregular spherical particles (40 - 240 nm, see Figure 10 (a)-(b) in Figure 10 ) that are smaller than those of LSNO (50 - 350 nm, see Figure 1 (a)-(b) in ), endowing it with more active sites and promoting the occurrence of catalytic reactions. The SAED results (see (i) in 0.3 ) further confirm that LSNC0.3 has good crystallinity, corresponding to the lattice planes of (008), (112), (215), and (310) with lattice spacings of 1.58, 2.46, 1.42, and in Figure 1 (h) in Figure 1 ). Compared with LSNO (PDF 01 - 089 - 8313), the d - value spacings between these four lattice planes are 1.57, 2.48, 1.41, and 0.3 respectively. High - resolution TEM shows that the d - spacing of the (004) lattice plane in LSNC 0.3 is

[0080] Table 1

[0081]

[0082]

[0083] As Figure 1 (k) in 0.3 shows, the full - scan XPS spectra indicate that, compared with LSNO, LSNC 0.3 contains La, Sr, Ni, Cu, and O elements, indicating that Cu has been successfully doped into LSNO, which is consistent with the SEM EDS images. The high - resolution spectra of La3d, Sr 3d, Ni 2p, Cu 2p, and O1S of the LSNO and LSNC Figure 9 catalysts are shown in Figure 1 (a)-(b) and 0.3 (l)-(n) in0.3 The binding energies of La-O-La, Sr-O-Sr, and Ni-O-Ni bonds are lower than those in LSNO, making them more prone to breakage and loss of oxygen atoms, thus forming OVs. Meanwhile, the introduction of low-valent copper ions (Cu + ) effectively reduces the average valence state of B-site ions in LSNC 0.3 from 2.57 to 2.35 (for LSNO, see Figure 8 ). Based on the charge compensation mechanism of the perovskite structure, the lattice oxygen content of LSNC 0.3 decreases, which is conducive to the formation of OVs. The equivalent ionic radius (EIR) of the B-site cations in LSNC 0.3 is while that of LSNO is (see SI). According to the above analysis, the introduction of Cu into LSNO enhances the interaction between B-site ions, causes lattice distortion and expansion (( Figure 1 ), reduces the binding energy of cations, and thus generates more oxygen vacancies, which may improve the catalytic activity of the catalyst.

[0084] To further confirm the additional oxygen vacancies generated in LSNC 0.3 , O1S spectra and EPR tests were used. As shown in Figure 1 (n) and Table 2.

[0085] Table 2

[0086]

[0087] As can be seen from Figure 1 and Table 2, there are four different oxygen species on the catalyst surface: lattice oxygen (O lattice ), highly oxidative oxygen species (O - / O 2 2- ), surface hydroxyl or adsorbed oxygen (-OH / O 2 ), and adsorbed water (H 2 O). Among them, the highly oxidative oxygen species (O - / O 2 2- ) are closely related to the surface oxygen vacancy content of LSNC0.3 and LSNO. The lattice oxygen content of LSNC 0.3 is lower (7.5%) than that of LSNO (9.0%). The content of highly oxidative oxygen species (O 0.3 / O - / O 2 2-) The relative content (19.9%) is higher than that in LSNO (13.3%), indicating that Cu doping introduces more oxygen vacancies in LSNO. The results of the EPR experiment ( Figure 1 (o) in 0.3 further confirmed this. The EPR signal (g = 2.003) of LSNC

[0088] is significantly higher than that of LSNO, indicating that Cu doping is a feasible method to increase the number of oxygen vacancies in LSNO.

[0089] 1. Identification of main reactive oxygen species

[0090] The existence of free radical and non-free radical oxidation pathways endows PMS with excellent catalytic performance in AOP. In this study, ESR and quenching experiments were used to verify that the main reactive oxygen species in the LSNC 0.3 / PMS and LSNO / PMS systems are involved. Ethanol (EtOH), tert-butanol (TBA), p-benzoquinone (p-BQ), and furfuryl alcohol (FFA) were used as scavengers for SO 4 ·- and ·OH, ·OH, ·O 2- and 1 O 2 respectively. As shown in (a)-(b) of Figure 11 , in the LSNC 0.3 / PMS system, after adding FFA, the removal rate of LVFX decreased by 40.2% and the k value decreased to 0.0186, indicating that 1 O 2 is the main ROS in the LSNC 0.3 / PMS system. After using ethanol or TBA as scavengers, the degradation rate of LVFX decreased significantly, and the inhibitory effect of ethanol was slightly stronger than that of TBA, indicating that ·OH exists in the system while SO 4 ·- may not exist. After adding p-BQ, the removal rate of LVFX only decreased by 16%, indicating that ·O2- has a relatively small effect on the removal of LVFX. It should be noted that in the LSNO / PMS system, ·OH plays a minor role in the degradation reaction. The contributions of ·OH, SO 4 · - O 2 - and 1 O 2 were quantitatively determined. The reaction rate constants after TBA, EtOH, p-BQ, and FFA were denoted as k1, k2, k3, and k4 respectively, and the initial reaction rate constant without quencher was k0. The contributions of ·OH, SO4 · - 、·O 2 - and 1 O 2 contributions.

[0091]

[0092]

[0093] Among them, λ(·OH), λ(SO 4 · - ), λ(·O 2 - ) and λ( 1 O 2 ) are the contributions of ·OH, SO 4 - 、·O 2 - and 1 O 2 to the degradation of LVFX; through calculation, in the LSNC0.3 / PMS system, 1 O 2 、·OH、·O 2- and SO 4 ·- The relative contributions to the removal of LVFX are 78.2%, 70.2%, 55.0% and 2.2% respectively, while in the LSNO / PMS system they are 91.9%, 10.8%, 52.2% and 1.8% (see (c) in Figure 11 ). It should be noted that there are multiple reactive free radicals in the advanced oxidation reaction, and there are complex transformation relationships among these active components. Adding a quencher can not only quench specific free radicals, but also affect their subsequent transformation processes, resulting in a contribution rate exceeding 100%. The above results show that Cu-doped LSNO can effectively promote the generation of ·OH free radicals. This may be due to the introduction of copper causing irregular distortion of the perovskite structure, resulting in more active metal sites being exposed to interact with PMS, and the effective direct electron transfer between the two causes the O-O bond of the PMS molecule to break, thus realizing the generation of more ·OH.

[0094] Subsequently, ESR was used to verify the results of the quenching experiment. Figures Figure 11 (d)-(f) in show the ESR signals of ROS in the LSNC 0.3 / PMS and LSNO / PMS systems. After the reaction started, 4 characteristic peaks of DMPO-·OH appeared in both systems, and their intensity ratio was 1:2:2:1, DMPO·SO 4 -The signal is almost non-existent, indicating that SO may not exist in the two systems 4 - , which is consistent with the quenching experiment. The generation of ·O 2- also has a similar pattern, with six characteristic peaks of DMPO-·O 2- appearing. It is thus speculated that ·OH and ·O 0.3 exist in the LSNC 2- / PMS and LSNO / PMS systems. In addition, three characteristic peaks with an intensity ratio of 1:1:1 were identified in the LSNC 0.3 / PMS and LSNO / PMS systems, confirming the formation of 1 O 2 within the system. It is worth noting that the intensity of the reactive oxygen species signal observed in the LSNO / PMS system is significantly lower than that in the LSNC 0.3 / PMS system. This indicates that Cu doping enhances the electron transfer ability of LSNO, enhances the activation ability of PMS, and promotes the generation of more reactive oxygen species, especially ·OH radicals. During the activation of PMS by metal-based catalysts, high-valent metal oxide species are easily formed. To eliminate their influence, dimethyl sulfoxide (DMSO) is used because it can react with high-valent metals to form dimethyl sulfone (DMSO 2 ). Adding a quantitative amount of DMSO did not significantly affect the degradation rate of LVFX (see Figure 7 (a)), indicating that the participation of high-valent metal oxide substances in the system is relatively small.

[0095] 2. Surface electron transfer process (ETP)

[0096] The catalyst directly transfers electrons to PMS, resulting in the cleavage of the O-O bond in PMS and the generation of ROS. Therefore, the electron transfer ability of the catalyst is crucial for PMS activation and the degradation of organic pollutants. As can be seen from Figure 12 (a), the cyclic voltammetry (CV) curve shows that LSNC 0.3 has a higher current density and stronger reduction ability compared to undoped LSNO, indicating that Cu doping enhances the electron transfer between R-P perovskite and PMS. In addition, the Nyquist curve of electrochemical impedance spectroscopy (EIS) was used to compare the electron transfer resistance between the two. Generally, the diameter of the semicircle of the curve is positively correlated with the charge transfer resistivity of the catalyst. The arc radius of LSNC 0.3 is smaller than that of LSNO (see Figure 12 (f)), indicating that LSNC 0.3 has a lower electron transfer resistance. The LSNC 0.3Whether the activation of PMS has a faster electron transfer rate. The results show that LSNC 0.3 has a smaller slope and higher corrosion current than LSNO, confirming that LSNC 0.3 activates PMS faster than LSNO. ((g) in Figure 12 ), due to the introduction of more OVs by Cu doping, which reduces the lattice constraint of R-P perovskite and enhances the electron transfer between PMS and the catalyst. The LSV curves are as shown in Figure 12 (b) in Figure 13 and 0.3 The current density of the LSNC 0.3 / PMS / LVFX system is higher than that of the bare LSNC 0.3 system and the LSNC 0.3 / PMS system, indicating that the electron transfer-mediated non-radical pathway only exists in the LSNC 0.3 / PMS / LVFX system. The i-t curve was used to further reveal the contribution of electron transfer to PMS activation. The electron transfer between different molecules LSNC Figure 14 ), PMS, and LVFX was studied. A rapid current response was generated 100 s after the injection of PMS, indicating that a strong electron transfer between PMS and the catalyst surface produced a metastable reactive catalyst-PMS complex. Then LVFX was added around 300 s, and a partial current rebound occurred, indicating the electron transfer of LVFX to the catalyst-PMS complex. In addition, the current density of the LSNC 0.3 / PMS / LVFX system was significantly higher than that of the LSNO / PMS / LVFX system, indicating that the LSNC 0.3 catalyst has a higher electron transfer ability than LSNO. In this system, electrons rapidly transfer from LVFX to PMS through the metastable reaction complex formed by the interaction between LSNC 0.3 and PMS. To further prove the existence of ETP in the catalytic process, Cr 2 O 7 - was used to quench the electrons present in the system. After adding 1 mM Cr 2 O 7 - , the removal rate of LVFX was inhibited to 46.9% ((b) in Figure 15 ), indicating that electron transfer plays an important role in the LSNC 0.3 / PMS system.

[0097] The surface element composition and oxidation state of LSNC 0.3 before and after the reaction were analyzed by XPS to further explore LSNC 0.3Previous studies have noted that La and Sr at the A site contribute to the structural stability of the perovskite structure and do not participate in the catalytic reaction. Figure 16 As shown in (a), the La 3d spectrum remains unchanged after the reaction, confirming that La does not contribute to the activation of PMS. However, a significant shift to higher binding energy is observed in the characteristic peak positions of the Sr 3d spectra of the samples used ( Figure 16 At the same time, SrCO 3 The ratio of SrO to H increased from 0.34 to 0.73 during the reaction. This is attributed to the fact that Sr, as an alkaline earth metal, is easily carbonized in the exposed atmospheric environment. The increase in SrO indicates that the generated H + With SrCO 3 Ni and Cu, as active metals, become the reaction sites for PMS activation. Figure 12 Zhonge- Figure 12 As shown in f, in the Ni 2p spectrum, Ni 2+ and Ni 3+ The contents of Cu and Cu changed from 35.6% and 64.4% to 48.0% and 52.0%, respectively. The characteristic peaks shifted to higher binding energies, indicating the existence of active redox cycles during PMS activation. + With Cu 2+ The ratio of Cu + The electron transfer between PMS promotes the generation of free radicals ( Figure 12 (h) in the figure.

[0098] LSNC before and after reaction 0.3 The XPS spectrum of O1S is shown in Figure 12 (g) and Table S3.

[0099] Table 3

[0100]

[0101] In contrast, O lattice , O - / O 2 2- , OH / O 2 and H 2 O changed from 7.5%, 19.9%, 57.1% and 15.5% to 13.4%, 14.9%, 57.0% and 14.7% respectively. - / O 2 2-The decrease in content means that the concentration of oxygen vacancies after the reaction decreases, indicating that oxygen vacancies may participate in the activation of PMS to generate ROS. Previous studies have shown that oxygen vacancies can serve as adsorption sites for PMS, extend the O-O bond, and promote the redox cycle of surrounding active metal ions, making them effective Lewis acid sites to enhance the interaction between the catalyst and PMS. In this work, oxygen vacancies act as electron donors to activate PMS, while promoting the ETP between PMS and the Ni / Cu bimetallic material, accelerating the Ni / Cu redox process, and further activating PMS.

[0102] Based on the above results and discussions, LSNC0.3 effectively activates PMS and generates free radicals (·OH, ·O 2- ), and non-free radicals ( 1 O 2 ), achieving the effective removal of LVFX. Since E Θ Ni(III) / Ni(II) = 1.84V and E Θ Cu(II) / Cu(I) = 0.17V, E Θ HSO5- / SO4·- = 2.6 - 3.1V, normal redox reactions can proceed smoothly.

[0103]

[0104] Cu(I)+Ni(III)→Cu(II)+Ni(II) (4)

[0105] Therefore, the contents of Ni(II) and Cu(II) after the reaction will increase (Equations (1)-(4)), which is consistent with the XPS results. Among them, SO 4 - mainly reacts with OH- in this system to generate ·OH (Equation (3)). The increase in the content of low-valent Ni and Cu in LSNC 0.3 promotes the electron transfer process between the catalyst and PMS, which is beneficial to the generation of ·OH. Oxygen vacancies with unpaired electrons have the ability to accept and provide electrons, thus establishing an electron transfer channel throughout the catalyst. More importantly, due to their excellent electron transfer ability, oxygen vacancies can reduce catalyst passivation, accelerate the electron transfer between metals, and promote the metal redox cycle. At the same time, OVs can also serve as adsorption sites for PMS, provide electrons for the activation process of PMS, and generate ·OH and SO 4 - (Equations (5)-(6)). In addition, the local electrons of oxygen vacancies can activate oxygen molecules to generate superoxide ions, such as Equation (7). Due to the low dissolved oxygen content in water, the superoxide ions generated in this step are limited. At the same time, ·O 2- can also be oxidized by PMS to H 2H generated from O and ·OH 2 O 2 Further transformation occurs through equations (8) - (12). 1 O 2 It can be generated through the transformation of ·O 2- and the self - decomposition of PMS (equations (13) - (15)). These active substances gradually oxidize LVFX to intermediates CO 2 and H 2 O (see (a) in Figure 17 . The doping of Cu not only changes the perovskite structure, promotes the generation of reactive oxygen species, but also accelerates the electron transfer rate between active metals, improving the activation performance of the catalyst for PMS, thus generating more reactive oxygen species.

[0106]

[0107] ·OH + ·OH → H 2 O 2 (9)

[0108] Ni(III) / 3Cu(I) + H 2 O 2 → H + + HO 2 - + Ni(II) / Cu(II) (10)

[0109] H 2 O 2 + ·OH → HO 2 - + H 2 O (11)

[0110]

[0111] 3. Reaction site calculation and possible degradation pathways of LVFX molecules

[0112] DFT calculations were used to predict the reaction centers of LVFX to preliminarily explore the degradation process of LVFX. Figure 17 (b) in Figure 17 shows the molecular structure optimization model of LVFX, including HOMO and LUMO orbitals. HOMO and LUMO orbitals are used to evaluate the ability to gain and lose electrons. Specifically, the HOMO orbital tends to undergo electrophilic reactions, while the LUMO orbital tends to undergo nucleophilic reactions. At the same time, the electron cloud density on the surface of LVFX was calculated by ESP, as shown inAs shown in (c), where electrons are mainly concentrated on O15 and O17, and de-electron reactions mainly occur at this position on the surface. Based on the HOMO, LUMO orbitals and ESP analysis of LVFX, the Fukui function is used to further confirm the reactive tendency sites of LVFX. The Fukui function has been widely used to predict the reaction sites of electrophilic, nucleophilic and radical attacks. Specifically, the Fukui function is defined as:

[0113]

[0114] In the formula, π(π) represents the electron density at point r in space, N is the number of electrons in this system, and the constant term v in the partial derivative is the external electric potential.

[0115] In this study, the multiwfn_3.8 software was used to visualize the Fukui function to analyze the wave function of the LVFX molecule. The condensed Fukui function (CFF) is determined based on atomic populations, which represent the electron density distribution around each atom. CFF can be calculated for three different scenarios, and its explicit definitions are as follows:

[0116] Nucleophilic attack: f k + = q N k - q N+1 k ;

[0117] Electrophilic attack: f k - = q N-1 k - q N k ;

[0118] Radical attack: f k 0 =(q N-1 k - q N+1 k ) / 2;

[0119] In the formula, k represents the Hirshfeld charge number of atom k in the corresponding state. The Fukui function provides information about different sites within the molecule. Sites with stronger reactivity are usually associated with higher CFF values compared to other regions. In this study, ·OH, ·O 2- , 1 O 2 and direct electron transfer are the main attacking species. Therefore, CFF nucleophilic attack, electrophilic attack and radical attack are used to analyze the regioselectivity during the LVFX degradation process, as Figure 18(a)-(d) in and Figure 19 As shown, generally, the higher the f0 value in the LVFX structure, the more vulnerable this site is to free radical attack, while f- and f+ are respectively proportional to the degrees of electrophilic and nucleophilic attacks. When certain atoms tend to undergo electrophilic and nucleophilic attacks simultaneously, CDD can be used to evaluate the reaction potential of these atoms under ROS attack. The results show that C4, C9, O15, O17, and N20 of LVFX are more vulnerable to attack, which is consistent with the above discussion. Finally, liquid chromatography-mass spectrometry (LC-MS) technology was used to detect potential intermediates during the degradation of LVFX. Based on the Fukui function, 15 possible reaction intermediates (see Table 4) and 4 reaction pathways were proposed in this study.

[0120] Table 4

[0121]

[0122]

[0123]

[0124] As Figure 17 shown in (f), in Pathway A, first, P1 (M / Z = 352) is obtained through demethylation, depiperazinization, and oxidation of LVFX. Then, the O17 and O18 atoms of P1 are attacked for decarboxylation reaction to remove the piperazine residue, resulting in P2 (M / Z = 235). Finally, P2 undergoes dequinoline and dehydroxylation to obtain P3 (M / Z = 233) and P4 (M / Z = 102). In Pathway B, LVFX is decarboxylated by ·O 2- attack to produce P5 (M / Z = 318). As the reaction proceeds, the piperazine moiety is gradually converted to amino group, generating P6 (M / Z = 293) and P7 (M / Z = 236). Eventually, the loss of methyl and amino groups leads to the intermediate product P8 (M / Z = 206). In the degradation Pathway C, the highly active N20 and N21 atoms on LVFX are attacked, undergoing deprotonation and decomposition to produce P9 (M / Z = 336). Subsequently, P9 further decomposes into P10 (M / Z = 322), P11 (M / Z = 279), and P12 (M / Z = 264). In Pathway D, similar to Pathway B, LVFX is first attacked by ·O2- to decarboxylate to form P5. Then, the piperazine ring of P5 is opened and oxidized to form P13 (M / Z = 278). Finally, the two highly active N atoms on the piperazine ring are attacked and oxidized to form P14 (M / Z = 263) and P15 (M / Z = 178). These intermediate products will further decompose into small molecule substances and be partially mineralized into CO 2 and H 2 O.

[0125] In addition, 3D EEMs was applied to verify LSNC 0.3 / PMS system for the time trend of LVFX degradation degree ( Figure 20 ). Due to the presence of conjugated heterocyclic structures in LVFX, two main peaks representing humic acid could be detected in the original solution, located at Ex / Em = (300 - 375) / (400 - 575) nm and Ex / Em = (250 - 300) / (425 - 575) nm. Meanwhile, after adding PMS to initiate the catalytic oxidation reaction, the areas of the two peaks gradually decreased, indicating that the conjugated heterocyclic structures on the surface of LVFX were destroyed. Finally, after 30 minutes of reaction, LVFX molecules were completely oxidized and decomposed into smaller molecules, and partially mineralized into CO 2 and H 2 O. The T.E.S.T toxicity assessment software was used to predict the toxicity of LVFX and its degradation intermediates P1 - P15. As Figure 17 (g) shown, six toxicity indicators were investigated, including developmental toxicity, mutagenicity, Pimephales promelas LIGUC 50, Daphnia magna LC 50, rat oral LD 50, and bioconcentration factor. Although the potential ecological risks of some degradation intermediates cannot be ignored, the toxicity of most intermediates is lower than that of LVFX because P4, P8, P12, and P15 are the final reaction monomers with overall reduced toxicity. Therefore, LSNC 0.3 / PMS system can effectively remove LVFX while reducing its negative impact on organisms.

[0126] In summary, the catalyst LSNC prepared by the present invention 0.3 has the best degradation effect on LVFX, with a removal rate of 94% within 30 min and a k value of 0.083 min -1 . The doping of Cu makes the chemical bonds between cations in the LNSO perovskite structure easier to break, reduces the average valence state of its B-site ions, introduces more oxygen vacancies, and provides more adsorption sites for the interaction between PMS and the catalyst. Meanwhile, in the presence of oxygen vacancies, the introduction of Cu accelerates the conversion of Ni(III) to Ni(II), promotes the formation of a two-electron cycle pair, promotes a rapid charge transfer process, and effectively enhances its ability to catalyze PMS. Under the combined action of the Ni / Cu catalyst and the oxygen vacancy redox process, PMS is activated to generate various reactive oxygen species (·OH, ·O 2- and 1 O 2 ), among which 1 O 2 plays a dominant role. The toxicity evaluation results show that the toxicity during the LVFX degradation process decreases.

[0127] The technical solution of the present invention is not limited to the limitations of the above specific embodiments. Any technical deformation made according to the technical solution of the present invention falls within the protection scope of the present invention.

Claims

1. A method for preparing a copper-doped RP phase perovskite catalyst, characterized in that: The following steps are involved: S1, La2O3, Sr(NO3)2, Ni(NO3)2·6H2O and Cu(NO3)2·3H2O with a molar ratio of 0.6:0.8:1:(0.1-0.5) were dissolved in 60 mL of deionized water, and then citric acid was added as a chelating agent, and the molar ratio of citric acid to all metal ions was 1.5:1; S2, then, adjusting the pH value of the mixture to 7, stirring continuously for 2 hours, and then transferring the mixture to an evaporating dish, heating to evaporate water, while continuing to stir until it becomes a viscous gel; S3, then, igniting and burning the gel to generate a precursor, and then placing the precursor in an alumina crucible, calcining it at 900° C. for 3 h in air, and naturally cooling it to room temperature; S4. Finally, the product is washed, dried, and ground to obtain the copper-doped RP phase perovskite catalyst LSNC. x , 0.1≤x≤0.

5.

2. The method for preparing a copper-doped RP phase perovskite catalyst according to claim 1, characterized in that: In the step S2, the pH value of the mixture is adjusted with NH3H2O.

3. The method for preparing a copper-doped RP phase perovskite catalyst according to claim 1, characterized in that: The molar ratio of La2O3, Sr(NO3)2, Ni(NO3)2·6H2O and Cu(NO3)2·3H2O is 0.6:0.8:0.7:0.3, and finally the copper-doped RP phase perovskite PMS catalyst LSNC is obtained. 0.3 .

4. A copper-doped RP phase perovskite catalyst prepared by the method according to any one of claims 1 to 3.

5. Use of the copper-doped RP phase perovskite catalyst as claimed in claim 4 in activating PMS to degrade antibiotic wastewater.

6. The use of the copper-doped RP phase perovskite catalyst according to claim 5 in activating PMS to degrade antibiotic wastewater, characterized in that: The amount of PMS added to the antibiotic wastewater is 0.3 g / L, the amount of catalyst added is 0.2 g / L, the initial pH of the antibiotic wastewater is 7, and the treatment temperature is 30°C.

7. The use of the copper-doped RP phase perovskite catalyst according to claim 5 in activating PMS to degrade antibiotic wastewater, characterized in that: The antibiotic is one or more of levofloxacin, enrofloxacin, ciprofloxacin, tetracycline, carbamazepine and sulfamethoxazole.

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