Bimetal magnetic manganese ferrite / bismuth oxychloride composite material as well as preparation method and application thereof

Abstract

The invention discloses a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material as well as a preparation method and application thereof. The preparation method of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material comprises the following steps: dissolving an iron source and a manganese source in deionized water, heating and stirring to obtain a mixed solution, adjusting the pH value, cooling to obtain a precipitate, cleaning, drying to obtain a precursor, and heating the precursor at 500-600 DEG C in an air atmosphere to obtain manganese ferrite nanoparticles; the preparation method comprises the following steps: dissolving a bismuth source in glacial acetic acid, adding methanol, uniformly mixing, adding glucosamine hydrochloride and manganese ferrite nanoparticles to obtain a dispersion liquid, reacting the dispersion liquid at 170-190 DEG C under a certain pressure, cooling, washing, and drying to obtain the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material. The removal rate of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material to CFX is 86.5%, and the removal rates of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material to parachlorophenol and rhodamine B are both 99% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental functional materials and water treatment, and specifically relates to a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material and a preparation method and application thereof. Background Art

[0002] The use of antibiotics is widespread in modern society, but their overuse leads to the discharge of antibiotics into natural waters at concentrations higher than natural background levels (208 ng / L to 5.6 μg / L). The antibiotic cephalexin (CFX) is a difficult-to-degrade and slightly toxic organic pollutant in wastewater treatment. It is widely present in wastewater, and due to its bioaccumulation and anti-degradation stability in the environment, it may cause problems such as kidney damage and hemolytic anemia, which have adverse effects on human health. Therefore, many countries have listed cephalexin as one of the toxic pollutants to be controlled with priority.

[0003] Photocatalysis is a green technology that utilizes intermittent sunlight that is ubiquitous and is considered to be the most promising pollution control technology. Photocatalysis uses photocatalysts to absorb photons in the presence of light, thereby generating a large number of active free radical ions (such as ·OH and ·O2-, etc.), which degrade cephalosporin antibiotic pollutants through free radical pathways. It acts on cephalexin macromolecules, splitting them into small molecular intermediates that are eventually mineralized. However, the use of photocatalysts to remove cephalosporin antibiotic pollutants has been hampered by low efficiency and secondary pollution, and photocatalysts also have problems such as easy shedding and difficulty in recycling. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material.

[0005] Another object of the present invention is to provide a method for preparing a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, wherein the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material is obtained by compounding manganese ferrite nanoparticles during the process of generating bismuth oxychloride by reacting bismuth nitrate pentahydrate and glucosamine hydrochloride.

[0006] Another object of the present invention is to provide a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material for use in the degradation of antibiotics.

[0007] The purpose of the present invention is achieved through the following technical solutions.

[0008] A bimetallic magnetic manganese ferrite / bismuth oxychloride composite material comprises bismuth oxychloride and manganese ferrite nanoparticles loaded on the surface of the bismuth oxychloride.

[0009] A method for preparing a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material comprises the following steps:

[0010] Step 1, dissolving an iron source and a manganese source in deionized water, heating and stirring at 80-100° C. for 1-2 hours to obtain a mixed solution, adjusting the pH of the mixed solution at 80-100° C. to 10.5-11.5, cooling to obtain a precipitate, washing, and drying to obtain a precursor, and heating the precursor at 500-600° C. for 4-6 hours in an air atmosphere to obtain manganese ferrite nanoparticles, wherein the ratio of iron in the iron source to manganese in the manganese source is (2-2.5):1 in terms of molar mass.

[0011] In step 1, the iron source is ferric chloride hexahydrate (FeCl3·6H2O) or ferric chloride, and the manganese source is manganese sulfate (MnSO4).

[0012] In step 1, the ratio of the amount of iron in the iron source to the volume of deionized water is (0.2-0.25):(100-150), the unit of the amount of iron is mol, and the unit of the volume is mL.

[0013] Step 2: dissolving the bismuth source in glacial acetic acid, adding methanol to mix evenly, then adding glucosamine hydrochloride and manganese ferrite nanoparticles to obtain a dispersion, and 6 ~2.0×10 6 Pa pressure, reacting the dispersion at 170-190° C. for 4-6 hours (solvothermal method), cooling to room temperature, washing and drying to obtain a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, wherein the ratio of iron in the iron source to bismuth in the bismuth source is 1: (7.5-8.7) in terms of molar fractions.

[0014] Preferably, the ratio of iron in the iron source to bismuth in the bismuth source is 1:(8-8.5) in terms of molar fractions.

[0015] In step 2, the ratio of the mass fraction of the bismuth source, the volume fraction of glacial acetic acid and the mass fraction of glucosamine hydrochloride is 2.425:(15-20):0.75, the unit of the mass fraction is g, and the unit of the volume fraction is mL.

[0016] In step 2, the ratio of glacial acetic acid to methanol is (15-20):60 by volume.

[0017] In the step 2, the bismuth source is bismuth nitrate pentahydrate (Bi(NO3)3·5H2O).

[0018] In step 2, the washing operation includes: centrifuging at least three times with anhydrous ethanol and deionized water respectively.

[0019] In the above technical solution, the centrifugal speed is 5000-7000 rpm, and the centrifugal time is 8-10 min.

[0020] In step 1 and step 2, the drying temperature is 60 to 80° C., and the drying time is 10 to 15 hours.

[0021] Application of the above bimetallic magnetic manganese ferrite / bismuth oxychloride composite material in the degradation of antibiotics.

[0022] In the above technical solution, the antibiotics are preferably degraded at pH=5-9.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared by the present invention has a removal rate of more than 72.4% for cephalexin when the pH value is 5 to 9, and the highest removal rate of cephalexin is 86.5%. It can achieve extremely high removal rates for p-chlorophenol and rhodamine B, with the removal rates all being more than 99%. It is used in actual water bodies and for the removal of different types of antibiotics, and can be directly used in actual applications.

[0025] (2) The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared by the present invention can decompose and mineralize antibiotics, and the mineralization rate of cephalexin is 51.5%.

[0026] (3) The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared by the present invention is recyclable and can still maintain the best performance after 4 cycles, with the removal rate only decreasing by 3.2%. In addition, in practical application, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material is firmly combined together, and the content of heavy metal shedding and leaching is far lower than the Chinese national standard, and will not cause secondary pollution to the environment.

[0027] (4) The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared by the present invention has magnetism and can still maintain good magnetism after 4 cycles. It can be easily recycled through the electromagnetic conversion effect and has practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 SEM images of (ab) the metal material prepared in Comparative Example 1 and (cd) the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 at different scales;

[0029] Figure 2 FT-IR spectra of the metal material prepared in Comparative Example 1 and the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 before and after the pollutant removal experiment in Example 8;

[0030] Figure 3 X-ray diffraction patterns of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal materials prepared in Comparative Examples 1-2;

[0031] Figure 4 (a) UV-visible diffuse reflectance spectrum and (b) Kubelka-Munk curve of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal materials prepared in Comparative Examples 1-2;

[0032] Figure 5 The removal effects of the metal materials prepared in Comparative Examples 1 to 2 and the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 at different dosages on cephalexin;

[0033] Figure 6 The removal effects of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal materials prepared in Comparative Examples 1-2 on cephalexin at different pH values;

[0034] Figure 7 The removal rate of cephalexin by the bimetallic magnetic manganese ferrite / bismuth oxychloride composite materials prepared in Examples 1 to 6 and the metal materials prepared in Comparative Examples 1 to 2;

[0035] Figure 8 The removal effect of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material on cephalexin prepared in Example 1 under different water environments;

[0036] Fig. 9 The removal effect of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 on different pollutants;

[0037] Fig.10 The mass spectra (a-c) and total organic carbon (d) of the pollutant wastewater in the pollutant removal experiment of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 of Example 8, wherein (a) is the pollutant wastewater at 0 hours, (b) is the pollutant wastewater at 1 hour, and (c) is the pollutant wastewater at 2 hours;

[0038] Fig.11 It is the cleavage and mineralization process of cephalexin;

[0039] Fig.12 (a) is the removal rate of cephalexin by the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 under different quenchers, Fig.12 (b) is the electron paramagnetic resonance spectrum of OH. Fig.12 (c) is ·O2 - Electron paramagnetic resonance spectroscopy;

[0040] Fig.13The removal effect of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 after four cycles of pollutant removal experiments;

[0041] Fig.14 The hysteresis loops of the metal material prepared in Comparative Example 1 and the bimetallic magnetic manganese ferrite / bismuth oxychloride composite materials prepared in Examples 1-2. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0043] In the following examples, the reagents used and their suppliers are shown in Table 1. All the reagents in Table 1 were of analytical grade.

[0044] Table 1

[0045] Reagents Molecular formula supplier Bismuth nitrate pentahydrate <![CDATA[Bi(NO3)3·5H2O]]> Aikang Biopharmaceuticals R&D Co., Ltd. (Jiangsu, China) Ferric chloride hexahydrate <![CDATA[FeCl3·6H2O]]> Kmart (Tianjin) Chemical Technology Co., Ltd. Manganese sulfate <![CDATA[MnSO4]]> Aikang Biopharmaceuticals R&D Co., Ltd. (Jiangsu, China) Ethanol <![CDATA[C2H6O2]]> Kmart (Tianjin) Chemical Technology Co., Ltd. Methanol <![CDATA[CH3OH]]> Kmart (Tianjin) Chemical Technology Co., Ltd. glacial acetic acid <![CDATA[C2H4O2]]> Tianjin Solomon Biotechnology Co., Ltd. Glucosamine hydrochloride <![CDATA[C6H 13 NO5·HCl]]> Tianjin Solomon Biotechnology Co., Ltd. Acetic acid <![CDATA[CH3COOH]]> Kmart (Tianjin) Chemical Technology Co., Ltd. Sodium hydroxide NaOH Shanghai Aladdin Biochemical Technology Co., Ltd. hydrochloric acid HCl Tianjin Bohai Chemical Reagent Co., Ltd.

[0046] In the following examples, during ultrasound, the volume of anhydrous ethanol used per 1 mL of precipitate was 5 mL.

[0047] Examples 1 to 6

[0048] A method for preparing a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material comprises the following steps:

[0049] Step 1, dissolving an iron source (the iron source is ferric chloride hexahydrate (FeCl3·6H2O)) and a manganese source (the manganese source is manganese sulfate (MnSO4)) in deionized water, heating and stirring at 90°C for 1 hour to obtain a mixed solution, adding a sodium hydroxide aqueous solution (the concentration of NaOH in the sodium hydroxide aqueous solution is 0.1 mol / L) dropwise to the 90°C mixed solution to adjust the pH to 11, cooling to room temperature to obtain a precipitate, and centrifuging the precipitate three times with anhydrous ethanol and deionized water at a speed of 5000 rpm, The centrifugation time for each time is 10 minutes. The precipitate after centrifugation is ultrasonicated in anhydrous ethanol for 10 minutes. After ultrasonication, the precipitate is dried at 80°C for 10 hours to obtain a precursor. The precursor is heated at 600°C for 4 hours in an air atmosphere to obtain manganese ferrite nanoparticles, wherein the ratio of iron in the iron source to manganese in the manganese source is 2:1 in terms of molar fraction, the ratio of the molar fraction of iron in the iron source to the volume fraction of deionized water is 0.2:100, the unit of the molar fraction is mol, and the unit of the volume fraction is mL.

[0050] Step 2: dissolving a bismuth source (the bismuth source is bismuth nitrate pentahydrate (Bi(NO3)3·5H2O)) in glacial acetic acid, adding methanol to mix evenly, then adding glucosamine hydrochloride and manganese ferrite nanoparticles to obtain a dispersion, placing the dispersion in a 100 mL autoclave, and reacting at 180° C. for 5 h (the pressure generated in the autoclave at 180° C. is 1.78×106 The invention relates to a method for preparing a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material. The method comprises the steps of: preparing the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material by mixing with anhydrous ethanol and deionized water for three times at a rotation speed of 5000 rpm, the centrifugation time for each time being 10 min, and drying at 80° C. for 10 hours to obtain a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, wherein the ratio of iron in the iron source to bismuth in the bismuth source is W, the ratio of the mass fraction of the bismuth source, the volume fraction of glacial acetic acid and the mass fraction of glucosamine hydrochloride is 2.425:15:0.75, the unit of mass fraction is g, the unit of volume fraction is mL, and the ratio of glacial acetic acid to methanol is 15:60 by volume.

[0051] The W of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite materials prepared in Examples 1 to 6 is shown in Table 2.

[0052] Table 2

[0053] Example W Example 1 1：8.3 Example 2 1：2.79 Example 3 1：1.67 Example 4 1.83：1 Example 5 3.05：1 Example 6 1：18.5

[0054] Comparative Example 1

[0055] A metal material (number: MnFe2O4), which is the manganese ferrite nanoparticles in Example 1.

[0056] Comparative Example 2

[0057] A preparation method of a metal material (code: BiOCl) comprises dissolving a bismuth source (the bismuth source is bismuth nitrate pentahydrate) in glacial acetic acid, adding methanol to mix evenly, and then adding glucosamine hydrochloride to obtain a dispersion, placing the dispersion in a 100 mL autoclave, and reacting at 180° C. for 5 h (the pressure generated in the autoclave at 180° C. is 1.78×10 6 Pa), cooled to room temperature, centrifuged three times with anhydrous ethanol and deionized water at a speed of 5000 rpm, each centrifugation time is 10 min, and dried at 80° C. for 10 hours to obtain a metal material (number: BiOCl), wherein the ratio of the mass fraction of bismuth source, the volume fraction of glacial acetic acid and the mass fraction of glucosamine hydrochloride is 2.425:15:0.75, the unit of mass fraction is g, the unit of volume fraction is mL, and the ratio of glacial acetic acid to methanol is 15:60 by volume.

[0058] Figure 1 The SEM images of the metal material prepared in (ab) Comparative Example 1 and (cd) the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 under different scales are shown in FIG. Figure 1From (ab), it can be seen that the metal material prepared in Comparative Example 1 has a typical clear and regular spinel structure with uniform grain size distribution (about 62nm). According to the literature (Spinel structured MFe2O4 (M=Fe, Co, Ni, Mn, Zn) and their composites for microwave absorption: A review, Chemical Engineering Journal 428 (2022) 131160), this unique spinel structure provides excellent chemical stability and electron transfer properties. Figure 1 (c) shows that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared by the solvothermal method in Example 1 exhibits BiOCl nanoflower structures of different sizes. Figure 1 (d) shows that there are manganese ferrite nanoparticles on the surface of the nanoflower structure, which indicates that the preparation method of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material is non-destructive and will not destroy the stable and unique spiny structure of manganese ferrite nanoparticles. On the contrary, it will be firmly loaded on the surface of BiOCl nanoflowers.

[0059] Figure 2 FT-IR spectra of the metal material prepared in Comparative Example 1 and the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 before and after the pollutant removal experiment in Example 8. Figure 2 It can be seen that in the FT-IR spectrum of the metal material prepared in Comparative Example 1, at 424 cm -1 The absorption peak at 540cm is the Mn-O absorption peak. -1 The absorption peak at 1668 cm-1 is the Fe-O absorption peak. The Mn-O absorption peak proves the existence of a tetrahedral spinel structure, and the Fe-O absorption peak proves the existence of an octahedral spinel structure. In the FT-IR spectrum of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1, the Mn-O absorption peak and the Fe-O absorption peak also appear, proving the successful loading of manganese ferrite nanoparticles in the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1. Compared with the manganese ferrite nanoparticles prepared in Comparative Example 1, the -1 The C=O stretching vibration at 1420 cm -1 The antisymmetric stretching vibration of C–H (CH3) saturated hydrocarbon (C–H3) at 1318 cm -1 The antisymmetric stretching vibration of C–H (CH3) saturated hydrocarbon (C–H3) at 3606 cm -1The -OH stretching vibration at the position is significantly enhanced. This may be due to the introduction of bismuth oxychloride (BiOCl) and the increase in the surface area of ​​the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material during the preparation process. In addition, compared with the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 without removal experiment ( Figure 2 Compared with the "Example 1 (fresh)" in Example 1, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material ( Figure 2 In the FT-IR spectrum of "Example 1 (used)" in FIG. 1 , the peaks are flattened and the peak areas are reduced, indicating that the functional group content is reduced. This may be because these functional groups are involved in the entire adsorption-desorption equilibrium and photocatalytic degradation process.

[0060] X-ray diffraction was performed on the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal materials prepared in Comparative Examples 1-2. The test results are as follows: Figure 3 As shown by Figure 3 It can be seen that in the X-ray diffraction pattern of the metal material prepared in Comparative Example 1, diffraction peaks at 17.2°, 29.7°, 34.9°, 42.5°, 56.2° and 61.5° correspond to the planes (111), (220), (311), (400), (511) and (440) of the cubic MnFe2O4 (JCPDS Card No. 10-0319) standard card, respectively. In the X-ray diffraction pattern of the metal material prepared in Comparative Example 2, diffraction peaks at 12.0°, 25.8°, 32.5°, 33.4°, 46.6° and 54.1° correspond to the planes (001), (101), (110), (102), (200) and (211) of the BiOCl (JCPDS Card No. 06-0249) standard card, respectively. In the X-ray diffraction diagram of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1, its diffraction peaks correspond to the standard cards of BiOCl (JCPDS Card No. 06-0249) and cubic MnFe2O4 (JCPDS Card No. 75-0035), respectively, and the diffraction peaks have similar diffraction angles to the diffraction peaks of the metal material prepared in Comparative Example 2, which may be due to the fact that the BiOCl crystal structure has not changed. Compared with the metal materials prepared in Comparative Examples 1 to 2, the diffraction peak intensity is weaker and the peak width is larger. In summary, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 is successfully prepared.

[0061] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal materials prepared in Comparative Examples 1 to 2 were subjected to ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS) analysis. The test results are as follows: Figure 4 As shown in (a), Figure 4 (a) shows that in the 200-600nm wavelength region, compared with the metal materials prepared in Comparative Examples 1 to 2, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has a high response intensity to light, which indicates that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 can effectively improve the utilization efficiency of light, reduce light reflection, generate more electron-hole pairs by light excitation, and enhance the separation of electron-hole pairs, delay the recombination of carriers, and enhance its photocatalytic activity.

[0062] according to Figure 4 The Kubelka-Munk curve is plotted against the wavelength and the intensity of the response to light in (a) to determine the band gap energy (Eg). Figure 4 As shown in (b), Figure 4 (b) shows that the band gap energy of the metal material prepared in Comparative Example 2 is 2.9 eV, the band gap energy of the metal material prepared in Comparative Example 1 is 3.1 eV, and the band gap energy of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 is 2.2 eV. The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has a lower band gap energy, which means that its electrons are more easily excited by photons, broadening the light response range and being more sensitive to sunlight.

[0063] Example 6

[0064] Pollutant removal experiment:

[0065] The catalyst (dosages were 3 mg, 5 mg, 7.5 mg, 10 mg and 12 mg, respectively) was dispersed in 10 mL of polluted sewage to obtain a test solution, which was placed in a photocatalytic reaction tube, and a photoreaction chemistry instrument (PhchemIII, Beijing Newbit Technology Co., Ltd., Beijing, China) was turned on for magnetic stirring. The reaction was carried out at room temperature and in the dark for 60 min to reach adsorption-desorption equilibrium, and then the photocatalytic reaction was carried out under irradiation of a 300 W xenon lamp for 2.5 h. The catalyst was a bimetallic magnetic manganese ferrite / bismuth oxychloride composite prepared in Examples 1 to 6. The material and one of the metal materials prepared in comparative examples 1 to 2, the pollutant wastewater is a mixture of pollutants and deionized water, the initial concentration (C0) of the pollutants in the pollutant wastewater is 10 mg / L, the pollutants are one of cephalexin (CFX), sulfonamide (SNM), para-chlorophenol (4-CP), phenol (PE), methyl orange (MO) and rhodamine B (RhB), the pH of the pollutant wastewater is 3, 5, 7, 9, and 11, respectively, and the pH is adjusted by 0.01 mol / L hydrochloric acid or by 0.01 mol / L sodium hydroxide aqueous solution.

[0066] Before the adsorption-desorption equilibrium, the test liquid was taken every 30 minutes. When the xenon lamp was irradiated, the test liquid was taken once at T min, Tmin = 30min, 60min, 120min and 150min. 4mL of the test liquid was taken each time and filtered with a 0.22μm nylon syringe filter. The concentration C (261nm wavelength) of the pollutants in the test liquid was detected by an ultraviolet-visible spectrophotometer (model: UV-1801, Beijing Fenrui Analytical Instrument Co., Ltd.), and the removal rate of the pollutants by the catalyst at T = 120min was calculated. The removal rate formula is as follows:

[0067]

[0068] In the pollutant removal experiments of Examples 7 to 10 below, the concentration of pollutants in the test liquid when the xenon lamp was irradiated for T = 120 min was selected as C. Analysis and removal rate calculation.

[0069] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 (dosages were 3 mg, 5 mg, 7.5 mg, 10 mg and 12 mg respectively) and the metal material prepared in Comparative Examples 1-2 (dosage was 10 mg) were used as "catalysts" to remove pollutants from polluted wastewater (the pollutant was cephalexin, pH was 7). The test results are as follows: Figure 5 As shown, when the catalyst is the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1, the addition amount is 3 mg, and the result is as follows Figure 5 As shown in "Example 1-3mg", the result of adding 5mg is as follows Figure 5 As shown in "Example 1-5mg", the result of adding 7.5mg is as follows Figure 5 As shown in "Example 1-7.5mg", the result of adding 10mg is as follows Figure 5 As shown in "Example 1-10mg", the result of adding 12mg is as follows Figure 5 As shown in "Example 1-12mg", by Figure 5 It can be seen that different dosages of catalyst have a greater effect on the removal of cephalexin. When the dosage is 10 mg (concentration is 1 g / L), the removal rate of the metal material prepared in Comparative Example 1 is 11.7%, and the removal rate of the metal material prepared in Comparative Example 2 is 50.3%. The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has the highest removal rate of cephalexin (CFX), which is 85.3%. Therefore, a dosage of 10 mg is selected for the following experiments.

[0070] The removal capacity of cephalexin per gram of catalyst was calculated according to the concentration of cephalexin. Compared with the removal capacity of the metal material prepared in Comparative Example 2 (5.03 mg / g), the removal capacity of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 for cephalexin was increased to 10.27 mg / g, indicating that loading manganese ferrite nanoparticles on the surface of BiOCl nanoflowers can significantly improve the removal capacity of CFX.

[0071] Example 7

[0072] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal material prepared in Comparative Examples 1-2 (dosage of 10 mg) were used as "catalysts" to remove pollutants from polluted wastewater (the pollutant was cephalexin, and the pH values ​​were 3, 5, 7, 9, and 11, respectively). The test results are as follows: Figure 6 As shown by Figure 6 It can be seen that when the pH is 5 to 9, the removal rate of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 for cephalexin is above 72.4%. This may be due to the fact that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material is negatively charged, and cephalexin is a typical amphoteric compound. When pH=2.56 to 6.88, it is electrically neutral. When pH>6.88, CFX is negatively charged. Therefore, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has a strong adsorption capacity for cephalexin, which is conducive to the photocatalytic degradation of CFX. In natural water bodies, such as river water or lake water, the pH value is usually in the range of 5 to 9, so it can be directly used in practical applications. In addition, the functional groups (-OH and C=O, etc.) present on the surface of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 can cause CFX to form hydrogen bonds with it to form a more stable adsorption state.

[0073] Example 8

[0074] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite materials prepared in Examples 1 to 6 and the metal materials prepared in Comparative Examples 1 to 2 (dosage of 10 mg) were used as "catalysts" to remove pollutants from polluted wastewater (the pollutant was cephalexin, pH 7), and the removal rate ( Figure 7 middle column) and photoreaction efficiency ( Figure 7 The result is as follows Figure 7 As shown in Table 3, Figure 7 As shown in Table 3, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 significantly improves the removal rate of CFX, and its removal rate is the best.

[0075] Table 3

[0076]

[0077]

[0078] The Langmuir-Hinshelwood model was used to study the kinetic rate constants of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal material prepared in Comparative Example 2. The kinetic rate constant of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 was 0.00922 min -1 , is the metal material prepared in Example 2 (0.00319min -1 ) is 2.89 times.

[0079] Example 9

[0080] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and the metal material prepared in Comparative Examples 1-2 (dosage of 10 mg) were used as "catalysts" to remove pollutants from polluted wastewater (the pollutant was cephalexin, pH 7). The test results are as follows: Figure 8 As shown in "Di", the laboratory deionized water in the polluted sewage was replaced with lake water (pH 8.1) and tap water (pH 7.5) to carry out the above pollutant removal experiment. The test results of lake water are as follows: Figure 8 As shown in "Lake" in the figure, the test results of tap water are as follows Figure 8 As shown in "Tap", Figure 8 It can be seen that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has a removal rate of 85.3% for CFX in laboratory deionized water, a removal rate of 58.5% for CFX in tap water, and a removal rate of 45.7% for CFX in lake water. In different water environments, the actual pretreatment methods for antibiotic pollution in water are usually limited. The coexistence of various organic pollutants and inorganic substances has an inhibitory effect on active free radicals and competes with CFX for available active sites. At present, the existing degradation materials are relatively poor in actual water use, so this removal rate is already a good removal effect.

[0081] Example 10

[0082] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 (dosage: 10 mg) was used as a "catalyst" to remove pollutants from polluted wastewater (the pollutants used are shown in Table 4, and the pH is 7). The pollutant test results are as follows: Fig. 9 As shown in Table 4, Fig. 9 As shown in Table 4, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has a good removal effect on different pollutants, and can achieve extremely high removal rates for p-chlorophenol and rhodamine B, with the removal rates both being above 99%, which has certain practical application significance for the removal of composite antibiotic pollution in water bodies.

[0083] Table 4

[0084]

[0085]

[0086] Embodiment 11

[0087] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 of Example 8 was used as a "catalyst" to remove pollutants from the wastewater at 0 h, 1 h and 2 h of photocatalytic reaction in the pollutant removal experiment. The test results are as follows: Fig.10 As shown in (a~c), Fig.10 From (a), we can see that at 0h of photocatalytic reaction, the CFX characteristic peak (m / z=348) can be observed, and there are no other obvious characteristic peaks. After 1h of photocatalytic reaction, Fig.10 From (b), it can be seen that in addition to the characteristic peak of CFX, other characteristic peaks are observed, indicating that many CFZ degradation intermediates have appeared after 1 hour of photocatalytic reaction, indicating that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 can indeed cause CFX to crack and produce different intermediates under light. Fig.10 (c) shows that the photocatalytic reaction lasts for 2h (by Figure 5 It can be seen that the CFX concentration at this time is consistent with that at 2.5h, that is, the photocatalytic reaction ends after 2h). Only a small amount of characteristic peaks remain in the mass spectrum, which are intermediate products that are not completely mineralized. This shows that CFX has been highly mineralized, but some characteristic peaks of CFX are still retained. This is due to the incomplete degradation of pollutants in the pollutant wastewater, which is consistent with the removal rate results in Example 8. The intermediate products that may be produced by CFX cracking are summarized and analyzed. The results are as follows Fig.11 As shown, it is further illustrated that CFX is gradually decomposed by the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 and is finally mineralized.

[0088] For the above photocatalytic reaction 0h( Fig.10 "before reaction") and 2h( Fig.10 The pollutant wastewater at the time of "Afterreaction" was tested for total organic carbon (TOC), and the results were as follows Fig.10 As shown in (d), according to Fig.10 The mineralization rate of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material for CFX prepared in Example 1 was calculated based on the total organic carbon content of (d), which was 51.5%.

[0089] Example 12

[0090] No quenching experiment: The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 (dosage of 10 mg) was used as a "catalyst" to remove pollutants from polluted wastewater (the pollutant was cephalexin, pH 7). Nitrogen was introduced before the photoreaction chemical instrument was turned on to eliminate the influence of dissolved oxygen on the experiment. The concentration of the pollutant in the test liquid when the xenon lamp was irradiated for 120 minutes was selected as C for calculation of the removal rate. The removal rate is as follows: Fig.12 (a) is shown as “Baseline”;

[0091] Quenching experiment: The quenching experiment is basically the same as the non-quenching experiment, except that the test liquid, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 (dosage is 10 mg) and the quencher are dispersed in the pollutant wastewater to obtain the test liquid, wherein the concentration of the quencher in the pollutant wastewater is 2 mM, and the quencher is one of oxalic acid (AO), superoxide dismutase (SOD), tert-butanol (TBA), L-histidine (L-Histidine) and dimethyl sulfoxide (DMSO).

[0092] Quenching by oxalic acid + , superoxide dismutase quenching·O2 - , tert-butyl alcohol quenching · OH, L-histidine quenching 1 O2 and DMSO quenching - To explore the role of active free radicals in the photocatalytic removal of CFX by bimetallic magnetic manganese ferrite / bismuth oxychloride composites, the test results are as follows Fig.12 As shown in (a), Fig.12 As shown in (a), DMSO and L-histidine have little inhibition on the removal rate of CFX, and the removal rate slightly decreases from 85.4% to 75.5% and 78.4%, respectively, indicating that e - and 1 O2 is not the main factor affecting the removal rate. SOD, TBA and AO significantly inhibited the degradation of CFX. AO reduced the removal rate of CFX by bimetallic magnetic manganese ferrite / bismuth oxychloride composite material to 65.1%, TBA reduced the removal rate of CFX by bimetallic magnetic manganese ferrite / bismuth oxychloride composite material to 52.8%, and SOD reduced the removal rate of CFX by bimetallic magnetic manganese ferrite / bismuth oxychloride composite material to 35.2%. This result shows that O2 - , OH and h + The contribution of free radicals to CFX degradation decreases in order, ·O2 - and ·OH are the main reasons for the low removal efficiency of CFX.

[0093] 5,5-Dimethyl-1-pyrrolidine N-oxide (DMPO) was used as a free radical scavenger to detect the O2 in polluted wastewater after 10 minutes of photocatalytic reaction. -and OH radicals, the results are as follows Fig.12 As shown in (bc), Fig.12 From (bc), we can see that Fig.12 In (b), a typical 1:2:2:1 characteristic signal peak of ·OH can be observed. Fig.12 In (c), 6 O2 - The characteristic peaks of the photocatalytic reaction indicate that after 10 minutes, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 produced ·O2 - and ·OH active free radicals, and act on CFX to cause it to crack and then be carbonized.

[0094] Embodiment 13

[0095] The bimetallic magnetic manganese ferrite / bismuth oxychloride composite material (dosage of 10 mg) prepared in Example 1 was used as a "catalyst" to conduct a pollutant removal experiment on pollutant wastewater (the pollutant was cephalexin, pH 7). The test liquid was taken once at the adsorption-desorption equilibrium. When irradiated with a xenon lamp, the test liquid was taken once at T min, Tmin = 30min, 60min, 90min, 120min and 150min, and the concentration of pollutants in the test liquid at T = 120min was selected to calculate the removal rate. After the pollutant removal experiment, the catalyst was immersed in an acidic aqueous solution (the acidic aqueous solution was hydrochloric acid, and the pH of the acidic aqueous solution was 2.5) and stirred for 12h. After stirring, it was washed with deionized water, and then dried at 80°C to constant weight, and it was used as a catalyst again to conduct a pollutant removal experiment. Repeat the above steps for 4 times, and the test results are as follows: Fig.13 As shown ( Fig.13 The time of each cycle is 3.5 h, including the time of adsorption-desorption under dark conditions and xenon lamp irradiation. Fig.13 It can be seen that after 4 repeated cycles of pollutant removal experiments, the removal rate of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 was slightly reduced, but the removal efficiency was only reduced from 85.5% to 82.3%, and the removal rate was only reduced by 3.2%, which still maintained a high efficiency. In addition, it can be seen from the experiment that the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 cannot restore its optimal removal effect without acid activation, indicating that under acidic conditions, H + The ions activated the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1, so that its surface active free radicals were activated again, and finally the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material returned to its original state. Therefore, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 can be recycled.

[0096] Embodiment 13

[0097] Inductively coupled plasma (ICP) testing was performed on the pollutant wastewater in the pollutant removal experiment using the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 in Example 8 as a "catalyst". The Mn content in the pollutant wastewater after the pollutant removal experiment was 0.2 mg / L, which is much lower than the Mn emission required by the Chinese national standard (Comprehensive Sewage Discharge Standard GB 8978-1996) ([Mn] <2 mg / L), which indicates that the leaching and desorption of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 will not bring new pollution to the environment.

[0098] Embodiment 14

[0099] The magnetic properties of the metal material prepared in Comparative Example 1 and the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Examples 1 and 2 were measured by a vibrating sample magnetometer. The test results are as follows: Fig.14 As shown by Fig.14 It can be seen that at room temperature and an external magnetic field (H) of -2.0 to 2.0 T, the magnetization intensity of the metal material prepared in Comparative Example 1 is 40.0 emu / g, the magnetization intensity of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 is 8.9 emu / g, and the magnetization intensity of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 2 is 3.4 emu / g. Compared with the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 2, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 has better magnetism, and after 4 cycles, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 still has good magnetism for pollutants. Therefore, the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 can be easily recovered by its magnetism.

[0100] In the above different embodiments, the degradation rate of the same pollutant by the same catalyst is slightly different, which is the error of multiple parallel experiments. For example, in Example 6, "the removal rate of cephalexin (CFX) by the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 is 85.3%", and in Table 3 of Example 8, "the removal rate of cephalexin (CFX) by the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material prepared in Example 1 is as high as 86.5%.

[0101] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, characterized in that: include: Bismuth oxychloride and manganese ferrite nanoparticles loaded on the surface of bismuth oxychloride.

2. A method for preparing a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, characterized in that: The following steps are involved: Step 1, dissolving an iron source and a manganese source in deionized water, heating and stirring at 80-100° C. for 1-2 hours to obtain a mixed solution, adjusting the pH of the mixed solution at 80-100° C. to 10.5-11.5, cooling to obtain a precipitate, washing, and drying to obtain a precursor, and heating the precursor at 500-600° C. for 4-6 hours in an air atmosphere to obtain manganese ferrite nanoparticles, wherein the ratio of iron in the iron source to manganese in the manganese source is (2-2.5):1 in terms of molar fraction; Step 2: dissolving the bismuth source in glacial acetic acid, adding methanol and mixing evenly, then adding glucosamine hydrochloride and manganese ferrite nanoparticles to obtain a dispersion, and 6 ~2.0×10 6 Pa pressure, reacting the dispersion at 170-190° C. for 4-6 hours, cooling to room temperature, washing and drying to obtain a bimetallic magnetic manganese ferrite / bismuth oxychloride composite material, wherein the ratio of iron in the iron source to bismuth in the bismuth source is 1:(7.5-8.7) in terms of the amount of substance.

3. The preparation method according to claim 2, characterized in that: The iron source is ferric chloride hexahydrate or ferric chloride, and the manganese source is manganese sulfate.

4. The preparation method according to claim 2, characterized in that: The ratio of the amount of iron in the iron source to the volume of deionized water is (0.2-0.25): (100-150), the unit of the amount of iron is mol, and the unit of the volume is mL.

5. The preparation method according to claim 2, characterized in that: The ratio of the mass fraction of the bismuth source, the volume fraction of glacial acetic acid and the mass fraction of glucosamine hydrochloride is 2.425: (15-20): 0.75, the unit of mass fraction is g, and the unit of volume fraction is mL.

6. The preparation method according to claim 2, characterized in that: The ratio of glacial acetic acid to methanol is (15-20):60 by volume.

7. The preparation method according to claim 2, characterized in that: The bismuth source is bismuth nitrate pentahydrate.

8. The preparation method according to claim 2, characterized in that: The washing operation includes: centrifuging at least three times with anhydrous ethanol and deionized water respectively; The centrifugal speed is 5000-7000 rpm, and the centrifugal time is 8-10 min; The drying temperature is 60-80° C., and the drying time is 10-15 hours.

9. Use of the bimetallic magnetic manganese ferrite / bismuth oxychloride composite material as claimed in claim 1 in the degradation of antibiotics.

10. The use according to claim 9, characterized in that: Degrade antibiotics at pH = 5-9.

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