A method for degrading bisphenol organic pollutants

Abstract

The application discloses a degradation method of bisphenol organic pollutants, and relates to a preparation method of rare earth doped manganese iron spinel with a particle structure and application of the manganese iron spinel and persulfate in degradation of bisphenol organic pollutants through a hydrodynamic cavitation technology. The application mainly relates to a combination of a Fenton-like oxidation technology of the rare earth doped manganese iron spinel with a particle structure and persulfate and a hydrodynamic cavitation technology. The method comprises the following steps: under the condition of hydrodynamic cavitation, the prepared rare earth doped manganese iron spinel with a particle structure activates persulfate through electron transfer between surface defects and rare earth elements, thereby generating a large number of superoxide free radicals to degrade bisphenol organic pollutants. In combination with abundant gas-liquid interfaces provided by nanobubbles generated by the hydrodynamic cavitation, the method increases the contact opportunity of active oxygen species and pollutant molecules, thereby improving the reaction rate and degradation efficiency. The method realizes efficient degradation of bisphenol organic pollutants, and provides a green and efficient solution for water treatment.

Description

Technical Field

[0001] This invention belongs to the field of advanced oxidation technology, and specifically provides a method for degrading bisphenol organic pollutants by using rare earth-doped particulate manganese-iron spinel and persulfate in synergistic hydrocavitation technology. Background Technology

[0002] The widespread presence of endocrine disruptors such as bisphenol A (BPA) and other organic pollutants poses a serious threat to the ecological environment and human health, making the development of efficient water treatment technologies particularly important. Advanced oxidation technologies, as an effective water treatment method, can degrade organic pollutants by generating highly oxidizing free radicals. Among them, persulfate (PMS) activation technology has attracted much attention due to its ability to generate various reactive oxygen species (ROS). However, using PMS alone for oxidation treatment suffers from low efficiency and high energy consumption.

[0003] Manganese-iron spinel (MnFe2O4), as a composite metal oxide catalyst, has shown potential in PMS activation technology. Rare earth element doping, as an effective modification method, can enhance the catalytic activity of manganese-iron spinel by altering its crystal structure and electronic properties. The introduction of rare earth elements can increase the number of active sites on the catalyst, promote electron transfer, lower the energy barrier for PMS activation, and thus improve the ROS generation efficiency.

[0004] Furthermore, hydrocavitation (HC) technology can promote chemical reactions by generating a localized high-temperature and high-pressure environment. Combined with PMS activation technology, it can further improve the degradation efficiency of organic pollutants. The microjets and shock waves generated during hydrocavitation can disrupt the catalyst surface structure, forming surface defects. These defects serve as active sites, promoting PMS activation. Simultaneously, the nanobubbles generated by hydrocavitation provide abundant gas-liquid interfaces, increasing the contact opportunities between ROS and pollutant molecules, thereby improving the reaction rate and degradation efficiency. Summary of the Invention

[0005] To improve the activation efficiency of persulfate (PMS) and the degradation efficiency of bisphenol pollutants, this invention synthesizes a rare earth-doped particulate manganese iron spinel (Ce-MnFe2O4) using the sol-gel method, and combines it with hydrocavitation technology to achieve efficient synergistic degradation.

[0006] The technical solution adopted in this invention is:

[0007] A method for degrading bisphenol-based organic pollutants is disclosed. The degradation reaction is carried out in a hydraulic cavitation device. Rare-earth-doped granular manganese-iron spinel is mixed with an aqueous solution containing bisphenol-based organic pollutants. After adsorption-desorption equilibrium is reached, persulfate is added, and the hydraulic cavitation device is activated to initiate the degradation reaction. The synergistic effect of hydraulic cavitation and the activation of persulfate by the rare-earth-doped granular manganese-iron spinel achieves highly efficient degradation of bisphenol-based organic pollutants.

[0008] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the initial concentration of the aqueous solution containing bisphenol organic pollutants is 10-50 mg / L, preferably 20 mg / L.

[0009] Furthermore, in the above-mentioned method for degrading bisphenol-based organic pollutants, the amount of rare earth-doped granular manganese-iron spinel added is 0.05-0.3 g / L, preferably 0.15 g / L.

[0010] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the amount of persulfate added is 0.2-1.0 mM, preferably 0.6 mM.

[0011] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the pH value of the reaction system is 3-11, preferably 7.

[0012] Furthermore, in the above-mentioned method for degrading bisphenol-based organic pollutants, the adsorption-desorption equilibrium time is 30 min.

[0013] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the hydraulic cavitation device consists of a centrifugal pump, a constant temperature water tank, a water valve, a pressure gauge, and a Venturi tube cavitation device.

[0014] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the Venturi tube cavitation device has a length of 100 mm and a diameter of 18.2 mm; a throat length of 2 mm and a diameter of 1.7 mm; a contraction section length of 20 mm and a contraction angle of 22°; and a diffusion section length of 70 mm and an expansion angle of 6°.

[0015] Furthermore, in the above-mentioned method for degrading bisphenol organic pollutants, the inlet pressure of the Venturi tube cavitation device is 1-4 bar, preferably 3 bar.

[0016] The method for degrading bisphenol-based organic pollutants according to any one of the above methods, wherein the method for preparing the rare earth-doped particulate manganese-iron spinel includes the following steps:

[0017] 1) Cerium nitrate hexahydrate, manganese acetate tetrahydrate, ferric nitrate nonahydrate and citric acid are dissolved in deionized water and stirred at 80°C to form a sol. The metal ions are hydrolyzed and condensed through the sol-gel reaction.

[0018] 2) Place the sol in an oven and dry at 105°C for 3-5 hours to remove the solvent and form a dry gel;

[0019] 3) The dry gel is heated to 520℃ at a heating rate of 2-5℃ / min and calcined at this temperature for 2 hours to obtain manganese iron spinel with good crystallinity and granular structure.

[0020] Furthermore, in the above-mentioned method for preparing rare earth-doped granular manganese-iron spinels, in step 1), the molar ratio of cerium nitrate hexahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate is manganese:iron:cerium = 1:2:0.03-0.07, preferably 1:2:0.05.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. By doping with the rare earth element Ce, the Ce-MnFe2O4 catalyst of this invention enhances the PMS activation ability, enabling more effective generation of reactive oxygen species such as superoxide radicals (·O2-) under the synergistic effect of hydraulic cavitation, thereby significantly improving the degradation efficiency of BPA. Compared with other advanced oxidation processes, this invention significantly improves degradation efficiency and reactive oxygen species generation, achieving a higher pollutant removal rate under the same conditions.

[0023] 2. Hydrocavitation technology, as a novel advanced oxidation process, has lower energy consumption compared to other advanced oxidation processes. Combined with the Ce-MnFe2O4 catalyst of this invention, the system can achieve efficient BPA degradation with lower energy input, thereby reducing operating costs. Furthermore, the stability and reusability of the Ce-MnFe2O4 catalyst further reduce long-term operating costs.

[0024] 3. The system of this invention achieves a greener and more environmentally friendly water treatment process by reducing the consumption of chemical oxidants and lowering energy consumption. Simultaneously, the ease of recovery and regeneration of the Ce-MnFe2O4 catalyst reduces secondary pollution to the environment. Attached Figure Description

[0025] Figure 1 These are X-ray diffraction (XRD) spectra of Ce-MnFe2O4 catalysts with different molar ratios.

[0026] Figure 2 Here are SEM images of Ce-MnFe2O4 ((a) 2 μm, (b) 500 nm).

[0027] Figure 3 These are schematic diagrams (a) of a hydraulic cavitation degradation device and (b) of a venturi tube cavitation device. In the diagrams, 1-centrifugal pump, 2-constant temperature water tank, 3-water valve, 4-pressure gauge, 5-venturi tube cavitation device, 6-contraction section, 7-diffuser section, and 8-throat.

[0028] Figure 4 The optimal conditions for the degradation method in the examples are selected, where (a) is the selection of Ce-MnFe2O4 catalyst dosage, (b) is the selection of persulfate dosage, (c) is the selection of ambient pH value, (d) is the selection of Venturi tube cavitation inlet pressure, and (e) is the selection of BPA concentration.

[0029] Figure 5 This is a removal curve of the degradation reaction under different degradation conditions.

[0030] Figure 6 This is a removal curve diagram of different bisphenol organic pollutants. Detailed Implementation

[0031] The embodiments of the present invention will be described in further detail below.

[0032] Example 1

[0033] This embodiment provides a method for degrading bisphenol organic pollutants by combining persulfate Fenton oxidation technology with hydraulic cavitation technology, which includes the following steps:

[0034] 1) Preparation of rare-earth-doped particulate manganese-iron spinel (Ce-MnFe2O4): 0.217 g of cerium nitrate hexahydrate, 2.45 g of manganese acetate tetrahydrate, and 8.08 g of ferric nitrate nonahydrate (molar ratio, manganese:iron:cerium = 1:2:0.05) were dissolved in an appropriate amount of deionized water in a beaker. The resulting mixture was stirred until a homogeneous solution was formed, and then heated to 80 °C. Separately, 12.6 g of citric acid was dissolved in an appropriate amount of deionized water in a beaker to prepare a homogeneous solution, and this solution was added to the aforementioned homogeneous solution. The suspension was then stirred at 80 °C until a sol was formed. The obtained sol was then dried at 105 °C until all water was evaporated, yielding a dry gel. The obtained dry gel was ground, and the ground sample was calcined at 520℃ (heated to 520℃ at a heating rate of 2-5℃ / min) for 2h to obtain Ce-MnFe2O4 product (Ce 5%).

[0035] In addition, cerium nitrate hexahydrate was added to a mixed solution at four different molar ratios to manganese acetate tetrahydrate: 1:0.03 (0.130 g), 1:0.05 (0.217 g), 1:0.07 (0.304 g), and 1:0.1 (0.434 g) to prepare Ce-MnFe2O4 products (3%, 5%, 7%, and 10%).

[0036] Figure 1 X-ray diffraction (XRD) spectra of Ce-MnFe2O4 catalysts with different molar ratios, and standard cards for MnFe2O4 (JCPDS No. 01-0319) and CeO2 (JCPDS No. 43-1002). The Ce doping concentration threshold was determined based on the XRD analysis results. For the prepared Ce-MnFe2O4 nanocatalysts, the Ce / MnFe2O4 molar ratio should be controlled at <0.07, with a preferred ratio of 0.05 for successful synthesis of cerium-doped manganese-iron spinel. Figure 2 The images show SEM images of Ce-MnFe2O4 ((a) 2 μm, (b) 500 nm). The images clearly show a three-dimensional stacked nanoparticle structure, which provides more active sites to promote PMS activation. This structure also exhibits resistance to hydrocavitation impacts, making it suitable for use in co-located systems.

[0037] 2) The dosage of Ce-MnFe2O4 catalyst and persulfate, the ambient pH value, and the inlet pressure of the Venturi tube cavitation device were screened. The degradation device uses a closed-loop hydraulic cavitation system. Figure 3 These are schematic diagrams of the degradation device and the dimensions of the Venturi tube cavitation device. Figure 4These are the optimal conditions for the degradation method in the examples. Based on the screening results, in a hydraulic cavitation device (consisting of a centrifugal pump, a constant temperature water tank, a water valve, a pressure gauge, and a Venturi tube cavitation device), Ce-MnFe2O4 catalyst at a concentration of 0.15 g / L was mixed with an initial concentration of 20 mg / L BPA aqueous solution, and stirred for 30 min to reach adsorption / desorption equilibrium. Subsequently, PMS (0.6 mM) was added to the mixture, and the hydraulic cavitation device was started. The inlet pressure of the Venturi tube cavitation device (100 mm in length, 18.2 mm in diameter; 2 mm in throat length, 1.7 mm in diameter; 20 mm in contraction section length, 22° in contraction angle; 70 mm in diffusion section length, 6° in expansion angle) was adjusted to 3 bar to initiate the degradation reaction. Before the experiment began, the removal performance of PMS / Ce-MnFe2O4 / HC for BPA obtained in this embodiment was measured using the following method: The peak area of ​​the BPA solution was measured using high-performance liquid chromatography (HPLC), and converted to concentration using a BPA standard curve. The initial peak area of ​​the bisphenol contaminant solution was determined using HPLC, and converted to concentration using a bisphenol contaminant standard curve, recorded as the initial concentration C0 (20 mg / L). Subsequently, the degradation reaction was initiated, and after a certain time interval, the peak area of ​​the BPA solution was measured again and converted to concentration, recorded as C. The degradation rate was calculated as (C0 - C) / C0 × 100%. Figure 4 This is a graph showing the removal curves of the degradation reaction under different degradation conditions. At a BPA concentration of 20 mg / L, a PMS dosage of 0.6 mM, a Ce-MnFe2O4 dosage of 0.15 g / L, a temperature of 25 ± 5℃, and a pH of 7, the synergistic removal efficiency of the PMS / Ce-MnFe2O4 / HC system for BPA can reach 99%. Figure 5 This is a graph showing the removal curves of the degradation reaction under different degradation conditions. The results show that the PMS / Ce-MnFe2O4 / HC system has a better degradation effect on BPA compared with the standalone Fenton-like system and the hydrocavitation system.

[0038] 3) To verify the degradation effect of the PMS / Ce-MnFe2O4 / HC system on bisphenol pollutants, a series of experiments were designed in this embodiment. The specific steps are as follows: Ce-MnFe2O4 catalyst was added to an aqueous solution containing 20 mg / L of bisphenol organic pollutants, and stirred for 30 min to reach adsorption / desorption equilibrium, while maintaining the Ce-MnFe2O4 dosage at 0.15 g / L and the temperature at 25 ± 5 °C. The selected bisphenol substances were bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF), bisphenol AF (BPAF), and bisphenol S (BPS). After reaching adsorption / desorption equilibrium, PMS (0.6 mM) was added to the mixture, and the inlet pressure of the hydraulic cavitation device was adjusted to 3 bar to initiate the degradation reaction. The initial peak area of ​​the bisphenol pollutant solution was determined using high performance liquid chromatography, and converted into concentration using the bisphenol pollutant standard curve, which was recorded as the initial concentration C0. Subsequently, the degradation reaction was initiated, and after a certain time interval, the peak area of ​​the BPA solution was measured again and converted into concentration, denoted as C. The degradation rate was calculated as (C0-C) / C0×100% to evaluate the degradation effect. Figure 6 This is a removal curve diagram for different bisphenol organic pollutants. The results show that the PMS / Ce-MnFe2O4 / HC system maintains a degradation efficiency of over 98% for bisphenol pollutants, fully demonstrating the excellent degradation performance of the PMS / Ce-MnFe2O4 / HC system for bisphenol pollutants.

[0039] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for degrading bisphenol-based organic pollutants, characterized in that, The degradation reaction is carried out in a hydraulic cavitation device. Rare earth-doped granular manganese-iron spinel is mixed with an aqueous solution containing bisphenol organic pollutants. After adsorption-desorption equilibrium is reached, persulfate is added, and the hydraulic cavitation device is started to carry out the degradation reaction. The initial concentration of the aqueous solution containing bisphenol organic pollutants is 10-50 mg / L, the amount of rare earth-doped granular manganese-iron spinel added is 0.05-0.3 g / L, and the amount of persulfate added is 0.2-1.0 mM. The preparation method of the rare earth-doped granular manganese-iron spinel includes the following steps: 1) Cerium nitrate hexahydrate, manganese acetate tetrahydrate, ferric nitrate nonahydrate, and citric acid are dissolved in deionized water and stirred at 80°C to form a sol. The molar ratio of cerium nitrate hexahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate is manganese:iron:cerium = 1:2:0.03-0.

07. 2) Place the sol in an oven and dry at 105℃ for 3-5 hours to form a dry gel; 3) The dry gel is heated to 520℃ at a heating rate of 2-5℃ / min and calcined at this temperature for 2 hours to obtain manganese iron spinel with good crystallinity and granular structure.

2. The method for degrading bisphenol-based organic pollutants according to claim 1, characterized in that, The initial concentration of the aqueous solution containing bisphenol organic pollutants was 20 mg / L, the amount of rare earth-doped granular manganese iron spinel added was 0.15 g / L, and the amount of persulfate added was 0.6 mM.

3. The method for degrading bisphenol organic pollutants according to claim 1, characterized in that, The pH value of the reaction system is 3-11.

4. The method for degrading bisphenol organic pollutants according to claim 3, characterized in that, The pH value of the reaction system is 7.

5. The method for degrading bisphenol organic pollutants according to claim 1, characterized in that, The adsorption-desorption equilibrium time is 30 min.

6. The method for degrading bisphenol organic pollutants according to claim 1, characterized in that, The hydraulic cavitation device consists of a centrifugal pump, a constant temperature water tank, a water valve, a pressure gauge, and a Venturi tube cavitation device. The Venturi tube cavitation device has a length of 100 mm and a diameter of 18.2 mm; a throat length of 2 mm and a diameter of 1.7 mm; a contraction section length of 20 mm and a contraction angle of 22°; and a diffusion section length of 70 mm and an expansion angle of 6°.

7. A method for degrading bisphenolic organic pollutants according to claim 6, characterized in that, The inlet pressure of the Venturi tube cavitation device is 1-4 bar.

8. The method for degrading bisphenolic organic pollutants according to claim 7, characterized in that, The inlet pressure of the Venturi tube cavitation device is 3 bar.

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