A method for efficiently degrading various FQs in water based on in-situ synthesis of carbon-coated copper iron perovskite
By preparing carbon-encapsulated perovskite C-LaCuFeO to activate persulfate, the problem of removing various FQs from water bodies was solved, achieving efficient and stable degradation and avoiding metal leaching and persulfate residue.
Patent Information
- Application Number
- CN202311184553.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-13
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2043-09-13
AI Technical Summary
Existing technologies are insufficient for efficiently removing various fluoroquinolone antibiotics (FQs) from water, and traditional transition metal catalysts suffer from problems such as metal leaching and persulfate residues.
Carbon-encapsulated perovskite C-LaCuFeO was used as a degrading agent. It was prepared by EDTA chelation sol-gel method and calcined at 800℃ in N2 atmosphere to form core-shell structured C-LaCuFeO perovskite, which was used to activate persulfate degradation of FQs.
It achieves efficient degradation of various FQs in water over a wide pH range, with low metal leaching, making it suitable for complex water bodies, and maintaining high degradation efficiency during multiple cycles.
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Figure CN117326662B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a method for efficiently degrading various FQs in water based on in-situ synthesis of carbon-coated copper iron perovskite, and belongs to the technical field of water treatment. BACKGROUND
[0002] Fluoroquinolone antibiotics (FQs) are a kind of broad-spectrum antibacterial drugs, which are stable in chemical properties, have a long half-life and are difficult to be degraded by microorganisms, and are a kind of emerging organic pollutants in water bodies. Although the detection concentration of FQs is low, the detection rate is high, FQs can be accumulated along the biological chain in the environment, and there is a potential environmental risk. Moreover, in actual water bodies, the components are complex, and various pollutants coexist, making it more difficult to remove FQs. Therefore, an efficient method for degrading mixed fluoroquinolone pollutants in water bodies is urgently needed.
[0003] The persulfate (PS) advanced oxidation technology is a technology for efficiently removing organic pollutants in wastewater by activating persulfate to generate sulfate radicals (SO4 .- ) with strong oxidizing properties. A large number of studies have shown that the persulfate advanced oxidation system not only exists in the form of strong oxidizing free radicals, but also can activate non-free radical pathways according to the physical and chemical properties of the catalyst. In recent years, the electron transfer pathway has also been reported to exist in the persulfate advanced oxidation system. This coexistence of multiple free radical pathways provides a possibility for the removal of refractory macromolecular organic pollutants in water bodies. At present, the activation modes of persulfate include photo / electro-activation, thermal activation, and external catalyst activation.
[0004] Transition metal-based catalysts exhibit excellent activation performance and are widely studied. Studies have shown that transition metal (Co 2 + , Fe 2+ , Cu 2+ , etc.) catalysts can efficiently degrade organic pollutants by activating PS, but the metal dissolution of these transition metal catalysts will cause secondary pollution to water bodies, limiting their application. In addition, the persulfate advanced oxidation process needs to add a large amount of persulfate, and part of the unreacted persulfate will remain in the water body, causing the content of persulfate in the effluent to be too high, resulting in secondary pollution. Therefore, an efficient, stable and environmentally friendly treatment method is urgently needed to degrade fluoroquinolone drugs in complex water bodies. SUMMARY
[0005] TECHNICAL PROBLEM
[0006] In view of the above problems that the ordinary advanced oxidation technology is not suitable for efficient treatment of various refractory organic matters such as FQs in water bodies, and the non-homogeneous catalysts have high metal dissolution and stability problems, the application provides an efficient, environmentally friendly method for degrading various FQs in complex water bodies.
[0007] Technical scheme:
[0008] The application provides a method for degrading multiple FQs in water, which is a method for degrading multiple FQs in water by using carbon-coated perovskite C-LaCuFeO as a degrading agent.
[0009] The carbon-coated perovskite is prepared by the following method:
[0010] (1) The LaCuFeO perovskite intermediate product is prepared by EDTA chelated gel sol method: soluble copper salt, soluble iron salt, soluble lanthanum salt, and EDTA and citric acid are dispersed and dissolved in water, mixed uniformly to obtain a mixed system; then the pH is adjusted to neutral, heated to produce a gel, and then the gel is dried and ground to obtain the LaCuFeO perovskite intermediate product.
[0011] (2) The obtained LaCuFeO perovskite intermediate product is calcined, then acid washed and dried to obtain the carbon-coated perovskite C-LaCuFeO.
[0012] In an embodiment of the application, in step (1), the soluble copper salt can be selected from copper nitrate or its hydrate, copper sulfate or its hydrate, and copper chloride or its hydrate; specifically, copper nitrate trihydrate.
[0013] In an embodiment of the application, in step (1), the soluble iron salt can be selected from iron nitrate or its hydrate, iron sulfate or its hydrate, and iron chloride or its hydrate; specifically, iron nitrate nonahydrate.
[0014] In an embodiment of the application, in step (1), the soluble lanthanum salt can be selected from lanthanum nitrate or its hydrate; specifically, lanthanum nitrate hexahydrate.
[0015] In an embodiment of the application, in step (1), the molar ratio of the lanthanum salt, the copper salt and the iron salt in the mixed system is 2:1:1.
[0016] In an embodiment of the application, in step (1), the molar ratio of EDTA to the lanthanum salt in the mixed system is 2:1.
[0017] In an embodiment of the application, in step (1), the addition amount of EDTA relative to the mixed system is 0.1-0.5 mol / L.
[0018] In an embodiment of the application, in step (1), the addition amount of citric acid relative to the mixed system is 0.2-0.8 mol / L.
[0019] In an embodiment of the application, step (1) specifically comprises the following process:
[0020] The soluble copper salt, the soluble iron salt and the soluble lanthanum salt are dispersed and dissolved in water to obtain a metal salt solution; the EDTA and the citric acid are respectively dispersed and dissolved in water, and then mixed to obtain a mixed solution; the metal salt solution is added dropwise into the mixed solution, and then the pH is adjusted to neutral, heated to generate a gel, and then the gel is dried and ground to obtain a LaCuFeO perovskite intermediate product.
[0021] In an embodiment of the present application, in step (1), the temperature for heating to gel is 80-100℃, and specifically 90℃ can be selected.
[0022] In an embodiment of the present application, in step (2), the calcination is performed at 800℃ for 2h under N2 atmosphere.
[0023] In an embodiment of the present application, in step (2), the pickling is performed by using 5% hydrochloric acid solution for 30min.
[0024] In an embodiment of the present application, the method further comprises adding a persulfate for combined degradation treatment.
[0025] In an embodiment of the present application, the FQs are two coexisting of ofloxacin (OFX) and ciprofloxacin (CIP).
[0026] The present application also provides a method for simultaneously degrading ofloxacin (OFX) and ciprofloxacin (CIP) in water, which comprises adding a carbon-coated perovskite (C-LaCuFeO) and a persulfate into the water body for degradation treatment.
[0027] In an embodiment of the present application, the dosage of the C-LaCuFeO perovskite relative to the water body is 0.1-0.5g / L; and further 0.2g / L can be selected.
[0028] In an embodiment of the present application, the persulfate is sodium peroxodisulfate and / or potassium peroxodisulfate; and sodium peroxodisulfate is preferred.
[0029] In an embodiment of the present application, the dosage of the persulfate relative to the water body is 0.3-1mM; and specifically 0.5mM can be selected.
[0030] In an embodiment of the present application, the degradation treatment is adjusting the pH to 3-11; and further 5-11 is preferred; and most preferably 7-8.
[0031] In an embodiment of the present application, the experimental concentration of the target pollutant FQs is 5-20ppm, and considering the possible concentration of BPA in the actual sewage plant effluent and the degradation rate, the most suitable FQs concentration is 10ppm.
[0032] Advantages:
[0033] (1) The C-LaCuFeO perovskite prepared by in-situ calcination of the copper-iron perovskite intermediate has a core-shell structure and is coated with carbon, can activate peroxysulfate (PDS), and efficiently degrades various FQs in water (the degradation rate reaches 100% within 30 minutes).
[0034] (2) The C-LaCuFeO perovskite prepared by the present application can efficiently remove FQs in water without adding PDS (the degradation rate of OFX reaches 86% and the degradation rate of CIP reaches 91% within 60 minutes).
[0035] (3) The C-LaCuFeO perovskite has stable structure, and the metal dissolution amount (Cu 2+ : 0.32 ppm; Fe 2+ : 0.09 ppm) is far lower than the A-level standard of the Water Quality Control Project for Discharge of Sewage into Urban Sewers.
[0036] (4) After the system is repeated four times, the degradation rate of CIP in the system is more than 92%, and the degradation rate of OFX in the system is more than 93%, which is efficient and environmentally friendly.
[0037] (5) The reaction system can degrade more than 100% of CIP and more than 100% of OFX in the system when the pH is 3-9, and is suitable for removing some organic pollutants in actual water. BRIEF DESCRIPTION OF DRAWINGS
[0038] Figure 1 Figure 1 is a graph showing the effect of FQs concentration on the degradation effect of the PDS-free system in Example 1 (a is CIP; b is OFX).
[0039] Figure 2 Figure 2 is a graph showing the effect of FQs concentration on the degradation effect of the system in Example 1 (a is CIP; b is OFX).
[0040] Figure 3 Figure 3 is a graph showing the effect of pH on the degradation effect of the system in Example 3 (a is CIP; b is OFX).
[0041] Figure 4 Figure 4 is a graph showing the degradation rate of the C-LaCuFeO perovskite in the recycling use in Example 4 (a is CIP; b is OFX).
[0042] Figure 5 Figure 5 is a graph showing the comparison of FQs removal results of the perovskite materials obtained under different calcination temperatures and before and after acid treatment in Comparative Example 1 (a is CIP; b is OFX).
[0043] Figure 6 The image shows the XRD pattern of the C-LaCuFeO perovskite catalyst obtained in Example 1.
[0044] Figure 7 The catalyst obtained in Example 1 . SEM image of C-LaCuFeO perovskite. Detailed Implementation
[0045] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited to these examples.
[0046] The degradation rate of FQs involved in this invention is equal to the concentration of FQs after degradation, C. t / Initial FQs concentration C0*100%.
[0047] The Cu involved in this invention 2+ Fe 2+ Dissolution amount refers to the content of free Cu and Fe ions in the system.
[0048] Example 1
[0049] The specific steps for preparing carbon-coated perovskite C-LaCuFeO are as follows:
[0050] (1) Preparation of LaCuFeO perovskite intermediate by EDTA chelation sol method: Weigh 0.0025 mol copper nitrate trihydrate, 0.0025 mol ferric nitrate nonahydrate, and 0.005 mol lanthanum nitrate hexahydrate, add 50 mL of deionized water to dissolve and obtain metal salt solution; Dissolve 0.01 mol EDTA and 0.02 mol citric acid in 10 mL and 30 mL of deionized water respectively and mix to obtain mixed solution; Add the metal salt solution dropwise to the above mixed solution and adjust the pH to about 7 with ammonia water to obtain mixture;
[0051] (2) Transfer the above homogeneous mixture to a water bath at 90°C and stir to evaporate until gel is formed; then place the gel in an oven at 240°C for 5 hours to obtain a fluffy intermediate product.
[0052] (3) The LaCuFeO perovskite intermediate product was placed in a tube furnace and calcined at 800°C under N2 atmosphere. The calcined product was etched in 5% hydrochloric acid solution for 30 min, and then washed and dried with deionized water. The resulting product was carbon-coated perovskite (C-LaCuFeO), denoted as C-LCFO.
[0053] The XRD and SEM images of the obtained C-LCFO perovskite are as follows: Figure 6 , 7 As shown.
[0054] In a typical system without PDS (C-LCFO perovskite 0.2 g / L, pH 7), different concentrations of FQs solution (10, 15, 30 ppm) were added with magnetic stirring. Samples were taken at regular time intervals, the reaction was quenched with an equal volume of ethanol solution, and the mixture was filtered. The concentration of FQs in the solution was determined by high-performance liquid chromatography (HPLC). The degradation rates of FQs in the above systems are shown in Table 1. Figure 1 .
[0055] Table 1. Degradation rate (%) of different FQs concentrations in the PDS-free system
[0056] FQs concentration (ppm) 10 15 30 CIP 91 88 72 OFX 86 76 54
[0057] From Table 1 and Figure 1 The results showed that as the concentration of FQs in the composite solution system increased from 10 ppm to 30 ppm, the CIP degradation rate decreased from 91% to 72% after 60 min, and the OFX degradation rate decreased from 86% to 54%. The OFX degradation rate decreased significantly with increasing FQs concentration; at an FQs concentration of 30 ppm, only 54% of the system was degraded after 60 min.
[0058] A small amount of PDS (0.5 mM) was added to the above system, along with FQs solutions of different concentrations (10, 20, and 30 ppm), and the mixture was magnetically stirred. Samples were taken at regular time intervals, and the reaction was quenched by adding an equal volume of ethanol solution and then filtered. The concentration of FQs in the solution was detected using high-performance liquid chromatography (HPLC). The FQs degradation rates in the above systems are shown in Table 2. Figure 2 .
[0059] Table 2. Degradation rate (%) of systems with different FQs concentrations
[0060] FQs concentration (ppm) 10 20 30 CIP 100 91 83 OFX 100 95 90
[0061] From Table 2 and Figure 2 The results showed that as the concentration of FQs in the composite solution system increased from 10 ppm to 30 ppm, the CIP degradation rate decreased from 100% to 83% and the OFX degradation rate decreased from 100% to 90% after 30 min. The increase in FQs concentration had little effect on OFX, only a slight decrease; even at an FQs concentration of 30 ppm, the system still achieved 90% degradation after 30 min. The core-shell structure of C-LaCuFeO perovskite confines FQs and active species within a nanoscale space, accelerating the reaction rate, and the activated PDS system for FQs degradation can handle a relatively wide range of pollutant concentrations.
[0062] Example 2: Effect of different initial pH values on degradation capacity
[0063] In a typical system (C-LCFO perovskite 0.2 g / L, PDS concentration 0.5 mM, FQs concentration 10 ppm), the initial pH of the solution was changed to 3, 5, 7, and 9, and magnetic stirring was added. Samples were taken at regular intervals, the reaction was quenched with an equal volume of ethanol solution, and the solution was filtered. The concentration of FQs in the solution was detected by high-performance liquid chromatography (HPLC). The reaction solution was filtered and recovered for analysis, and the concentration of metal ions in the solution was detected by atomic absorption spectrophotometry. The degradation rate of FQs in the above systems is shown in Table 3. Figure 3 .
[0064] Table 3. Degradation rate (%) of systems with different FQs concentrations
[0065] System initial pH 3 5 7 9 CIP 100 100 100 100 OFX 100 100 100 100
[0066] Note: Degradation rate = (C t / C0)*100%(C t C0: Concentration of FQs in the system at time t; C0: Initial concentration of FQs
[0067] From Table 3 and Figure 3 The results showed that the system is applicable over a wide pH range. The degradation rate was significantly accelerated under acidic conditions. However, for OFX, it achieved excellent degradation performance across all pH ranges. The system achieved 100% degradation of both CIP and OFX coexisting in the water after 30 minutes. This indicates that the C-LCFO perovskite-activated PDS degradation system for FQs is suitable for a wide range of water pH conditions.
[0068] To determine the optimal pH for the system, the concentration of metal ions in the system after the reaction was measured. The concentrations of metal ions after the reaction at different pH values are shown in Table 4.
[0069] Table 4. Concentration of metal ions in the solution after the reaction.
[0070] Solution initial pH 3 5 7 9 Cu 2+ (ppm) 0.43 0.33 0.32 0.13 Fe 2+ (ppm) 0.12 0.11 0.09 0.07
[0071] As can be seen from Table 4, C-LCFO perovskite can activate PDS to degrade FQs under a wide range of water pH conditions, and Cu 2+ Fe 2+ The amount of ion dissolution decreases with increasing pH, and almost no dissolution occurs under neutral conditions. It meets the Class A standard of the "Water Quality Control Project for Wastewater Discharge into Urban Sewerage Systems" within a pH range of 3–9. This catalyst exhibits good degradation performance within a pH range of 7–9.
[0072] Example 3: C-LaCuFeO Perovskite Recyclability Test
[0073] In a typical system (C-LCFO perovskite 0.2 g / L, PDS concentration 0.5 mM, FQs concentration 10 ppm, pH 7), magnetic stirring was applied. Samples were taken at regular intervals, and the reaction was quenched by adding an equal volume of ethanol solution and filtered. The concentration of FQs in the solution was detected by high performance liquid chromatography. The catalyst was recovered after the reaction and washed alternately with ethanol and deionized water and dried. The above experiment was repeated 4 times using the recovered catalyst. The degradation rate of the cyclic test system is shown in Table 5. Figure 4 .
[0074] Table 5. Degradation rate (%) in cyclic testing
[0075] Cycle number 1st 2nd 3rd 4th CIP 100 95 94 92 OFX 100 100 100 93
[0076] Note: Degradation rate = (C t / C0)*100%(C t C0: Concentration of FQs in the system at time t; C0: Initial concentration of FQs
[0077] From Table 5 and Figure 4 The results show that after four cycles of C-LCFO perovskite recycling, the OFX degradation rate in the system remained above 93% for 30 minutes, and the CIP degradation rate remained above 92%. This indicates that C-LCFO perovskite can not only efficiently degrade coexisting FQs in water but also maintain a certain degree of stability, making this reaction system conducive to recycling.
[0078] Comparative Example 1: The degradation ability and stability of the perovskite materials obtained before and after different calcination temperatures and acid treatments. The modified perovskite was prepared by the EDTA-chelated sol-gel method:
[0079] (1) Weigh out a certain amount of copper nitrate trihydrate, ferric nitrate nonahydrate, and lanthanum nitrate hexahydrate, and dissolve them in an appropriate amount of deionized water; weigh out a certain amount of EDTA and dissolve it in ammonia water; weigh out a certain amount of citric acid and dissolve it in deionized water.
[0080] (2) Pour the EDTA aqueous solution into the citric acid solution, and add the above mixed metal salt solution dropwise. Adjust the pH to about 7 with ammonia.
[0081] (3) Transfer the above homogeneous mixture to a water bath at 90°C and stir to evaporate until gel is formed; then place the gel in an oven at 240°C for 5 hours to obtain a fluffy intermediate product.
[0082] (4) The above intermediate product was ground and calcined in a muffle furnace. The temperature was preheated to 450℃ for 2 hours, and then further increased to 700℃ for 6 hours. The resulting product was washed alternately with ethanol and deionized water and dried in an oven overnight to obtain LaCu. x Fe 1-xO3 perovskite (x=0.5), abbreviated as LCFO-1:1.
[0083] (5) The above-mentioned fluffy intermediate product was ground and placed in a tube furnace and calcined at 700℃ and 800℃ for 2 hours under N2 atmosphere. After calcination, the product was washed and dried alternately with ethanol and deionized water. The obtained products were denoted as C-700 and C-800.
[0084] (6) Take an appropriate amount of C-700 powder and treat it with 5% hydrochloric acid aqueous solution for 30 min. After washing with water until neutral, dry it. The resulting product is called C-700-H.
[0085] In a typical system (catalyst 0.2 g / L, PDS concentration 0.5 mM, FQs concentration 10 ppm, pH 7), equal amounts of various modified copper-iron perovskites were added with magnetic stirring. Samples were taken at regular intervals, and the reaction was quenched by adding an equal volume of ethanol solution and filtered. The concentration of FQs in the solution was detected by high-performance liquid chromatography (HPLC). The FQs degradation rates in the above systems are shown in Table 6. Figure 5 .
[0086] From Table 6 and Figure 5 The results show that, under the same experimental conditions, after 30 minutes, LCFO-1:1 can degrade 59% of CIP and 74% of OFX. The catalyst carbonized at 800℃ showed a 60% removal rate of CIP and a 73% removal rate of OFX in water, significantly better than the catalyst carbonized at 700℃. However, the degradation rates of OFX by these four perovskites were significantly weaker than those of C-LCFO, and none could simultaneously achieve efficient degradation of both CIP and OFX in the composite solution. The prepared C-LCFO-activated PDS can simultaneously and effectively degrade 100% of CIP and 100% of OFX within 30 minutes.
[0087] Table 6. FQs degradation rate (%) in different perovskite systems
[0088] Catalyst system LCFO-1 : 1 C-700 C-700-H C-800 C-LCFO CIP 59 40 24 60 100 OFX 74 47 25 73 100
[0089] Note: Degradation rate = (C t / C0)*100%(C t C0: Concentration of FQs in the system at time t; C0: Initial concentration of FQs.
[0090] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined in the claims of this invention.
Claims
1. A method for simultaneously degrading ofloxacin and ciprofloxacin in water, characterized in that, The method uses carbon-encapsulated perovskite C-LaCuFeO as a degradation agent without adding persulfate. The carbon-encapsulated perovskite C-LaCuFeO was prepared by the following method: (1) LaCuFeO perovskite intermediate was prepared by EDTA chelation sol method: soluble copper salt, soluble iron salt, soluble lanthanum salt, EDTA and citric acid were dispersed and dissolved in water, mixed well to obtain a mixed system; then the pH was adjusted to neutral, heated to produce gel, and then the gel was dried and ground to obtain LaCuFeO perovskite intermediate. (2) The obtained LaCuFeO perovskite intermediate product was calcined at 800℃ for 2h under N2 atmosphere, then acid washed and dried to obtain carbon-coated perovskite C-LaCuFeO.
2. The method according to claim 1, characterized in that, In step (1), the soluble copper salt can be copper nitrate or its hydrate, copper sulfate or its hydrate, or copper chloride or its hydrate; the soluble iron salt can be ferric nitrate or its hydrate, ferric sulfate or its hydrate, or ferric chloride or its hydrate; and the soluble lanthanum salt can be lanthanum nitrate or its hydrate.
3. The method according to claim 1, characterized in that, In the mixed system described in step (1), the molar ratio of lanthanum salt, copper salt, and iron salt is 2:1:1; the molar ratio of EDTA to lanthanum salt is 2:
1.
4. The method according to claim 1, characterized in that, The addition amount of EDTA relative to the mixed system is 0.1-0.5 mol / L; the addition amount of citric acid relative to the mixed system is 0.2-0.8 mol / L.
5. The method according to claim 1, characterized in that, In step (2), the pickling is performed by etching and washing in a 5% hydrochloric acid solution for 30 minutes.
6. The method according to claim 1, characterized in that, The method also includes the addition of persulfate for combined degradation treatment.
Citation Information
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