A bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material, a preparation method and application thereof

Abstract

The application discloses a kind of bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite materials and preparation method and application thereof, method includes: Co (NO3) 2·6H2O is dissolved in organic solvent, single crystal Bi2Fe4O9 nanosheet is added, mixed stirring, obtain suspension, to the suspension drop isopropyl titanate, obtain mixed suspension;To the mixed suspension drop is ammonium bicarbonate aqueous solution, stirring is reacted, the reaction mixture obtained is centrifuged, after washing, drying to the obtained precipitate product is calcined in air atmosphere, obtain the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.The preparation method of the application is simple and environmental protection, reaction condition is mild, the structure stability and durability of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared are high, can be used to improve the activation efficiency and stability of PMS, efficiently degrades organic pollutants in water body, and has wide application prospect in the field of organic sewage treatment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts based on advanced oxidation processes, and particularly relates to a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material and a preparation method and application thereof. BACKGROUND

[0002] In recent years, environmental pollution has become a major problem faced by countries around the world. Among them, water pollution is the most serious form of pollution, mainly coming from industry, agriculture, urban life and other aspects. Traditional wastewater treatment methods include biological treatment, physical treatment, etc., but for some difficult-to-decompose organic pollutants, the traditional treatment method has low efficiency and is difficult to meet the required discharge standard. Therefore, developing new efficient methods for treating pollutants has become a hot research direction in the current environmental protection field.

[0003] The advanced oxidation process (AOPs) based on persulfate (PMS) is a widely studied and applied water treatment technology, which utilizes the activation of PMS to generate strong oxidizing free radicals (such as SO4· - and ·OH), thereby degrading organic pollutants. The advanced oxidation process based on sulfate radicals (SO4· - ) has been widely used in water treatment, and compared with the hydroxyl radicals (·OH) generated by the Fenton oxidation process, SO4· - shows higher standard reduction potential (2.6-3.1V), wider pH range and higher selectivity.

[0004] At present, Co ions are considered to be the most effective catalyst for activating PMS. The patent document with publication number CN112547078B discloses a method for preparing a nanoscale cobalt-based bismuthinite efficient photocatalyst at low temperature by solvent thermal method, which adopts a solvent thermal method to prepare a nanoscale cobalt-based bismuthinite efficient photocatalyst Bi 25 CoO 40 . The invention utilizes the precipitation of bismuth salt and cobalt salt in a specific lye system, and then performs solvent thermal reaction at a certain temperature and suitable time to prepare a nanoscale cobalt-based bismuthinite photocatalyst.

[0005] Although Co ions can efficiently activate PMS, Co is toxic and difficult to recover, and the excessive release of cobalt ions into the environment may have a negative impact on the ecosystem. At present, there are mainly two methods to overcome the leaching of Co ions, one is to synthesize more stable composite transition metal oxides such as CoTiO3, and the other is to combine transition metals with carriers. TiO2 is a typical transition metal oxide, which has the advantages of high stability, low cost, non-toxicity, abundant earth resources and other material advantages, and also shows ideal performance for Co ion deposition. TiO2 not only can well support the dispersion of Co, but also can promote the surface Co-OH- The formation of the complex improves the activation efficiency.

[0006] The patent document with the publication number CN109331831A discloses a preparation method of a high-efficiency visible light catalyst single crystal nanosheet, which comprises the following steps: Bi4Ti3O 12 The stoichiometric ratio of Bi, Co and Ti in BiCoO3 is weighed to obtain bismuth nitrate, cobalt nitrate and butyl titanate; the raw materials are dissolved in water, and then the anhydrous ethanol solution of butyl titanate is added, stirring is performed to uniformly mix the butyl titanate to obtain a solution A; NaOH is used as a precipitant and a water environment regulator, the NaOH is dissolved in water to obtain a solution B, the solution B is added to the solution A, and after stirring and waiting for the reaction to be completed, a gray-green suspension precursor is obtained; the suspension precursor is transferred to a hydrothermal reaction kettle, the reaction kettle is sealed and then placed in an oven, hydrothermal reaction is performed at 200 DEG C for 48-72 hours, and after the reaction, the target product is obtained through subsequent treatment.

[0007] Although the prior art has studied Co-based PMS activation materials to some extent, it is still of great significance to find a new method to prepare Co-based PMS activation materials which are more stable and have a stronger degradation effect on sewage. SUMMARY

[0008] To solve the problems in the prior art, the application provides a preparation method of a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0009] The preparation method of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material comprises the following steps:

[0010] S1, Co(NO3)2·6H2O is dissolved in an organic solvent, single crystal Bi2Fe4O9 nanosheets are added, stirring is performed, a suspension is obtained, and titanium isopropyl titanate is added dropwise into the suspension to obtain a mixed suspension;

[0011] S2, ammonium bicarbonate aqueous solution is added dropwise into the mixed suspension obtained in step S1, stirring is performed to react, the obtained reaction mixture is centrifuged and separated, and the obtained precipitate is washed and dried;

[0012] S3, the product after drying in step S2 is calcined in an air atmosphere to obtain the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0013] In the application, the hydrolysis-precipitation method is used to coat the cobalt titanate and the titanium dioxide on the surface of the single crystal Bi2Fe4O9 nanosheet to form the composite material. 2+ In the mixed solution of the titanium isopropyl titanate and the Bi2Fe4O9, when the ammonium bicarbonate aqueous solution is added dropwise, the Co 2+ The ammonium bicarbonate reacts to form basic cobalt carbonate nanoparticles, and the isopropyl titanate is rapidly hydrolyzed in water to form a film of TiO2 deposited on the surface of the Bi2Fe4O9, and the basic cobalt carbonate is fixed on the surface of the Bi2Fe4O9. The single-crystal Bi2Fe4O9 nanosheet is used as a carrier, and the TiO2 is coated to reduce the leaching of Co 2+ After calcination, the TiO2 undergoes phase transition, and the basic cobalt carbonate reacts with the coated TiO2 at high temperature to form cobalt titanate.

[0014] Preferably, in step S1, the ratio of Co(NO3)2·6H2O, organic solvent, single-crystal Bi2Fe4O9 nanosheet, and isopropyl titanate is 0.2-0.5 mmol:20 mL:0.1 g:100-300 μL.

[0015] Preferably, the organic solvent includes ethanol, N,N-dimethylformamide, or acetone.

[0016] Preferably, in step S1, the single-crystal Bi2Fe4O9 nanosheet is prepared by hydrothermal reaction using Bi(NO3)3·5H2O and Fe(NO3)3·9H2O as raw materials and NaOH as a mineralizer in a solution system of deionized water and acetic acid.

[0017] Preferably, the single-crystal Bi2Fe4O9 nanosheet is a nanoscale regular square sheet. The single-crystal Bi2Fe4O9 nanosheet has the advantages of small size, large specific surface area, high PMS activation activity, and easy recovery, and is a good carrier for composite materials.

[0018] Preferably, the preparation method of the single-crystal Bi2Fe4O9 nanosheet is as follows:

[0019] S11, Bi(NO3)3·5H2O and Fe(NO3)3·9H2O are added to a mixed solvent of water and acetic acid, the molar ratio of Bi 3+ to Fe 3+ is adjusted to 1:1.5-2, and stirring is performed to obtain a mixed suspension;

[0020] S12, NaOH is added to the mixed suspension to make the concentration of NaOH reach 9-11 mol / L, and stirring is performed to obtain a precursor suspension;

[0021] S13, the precursor suspension is subjected to hydrothermal reaction at 160-200℃ for 6-24h, after the reaction is completed, the reaction product is filtered, washed, and dried to obtain the single-crystal Bi2Fe4O9 nanosheet.

[0022] Preferably, in step S11, the Bi (NO3) 3·5H2O and water are added in a ratio of 0.8-1.2 mmol:30-40 mL.

[0023] Preferably, in step S2, the concentration of the ammonium bicarbonate aqueous solution is 0.1-0.5 M, the volume is 5-10 times that of the isopropyl titanate, and the dropping speed is 100-300 μL / min.

[0024] Preferably, in step S2, the reaction time is 2-4 h.

[0025] Preferably, in step S3, the calcination conditions are as follows: heating at a rate of 5-10 ℃ / min to 450-600 ℃, and holding for 1-2 h.

[0026] More preferably, in step S3, the calcination conditions are as follows: heating at a rate of 5 ℃ / min to 450 ℃, and holding for 2 h.

[0027] The application also provides a BiFeO3 / Cobalt titanate / TiO2 nanosheet composite material prepared by the above preparation method. The composite material has a nanosheet structure, a large specific surface area, high structural stability and durability, and high catalytic activity.

[0028] The application also provides the use of the BiFeO3 / Cobalt titanate / TiO2 nanosheet composite material in the field of organic wastewater treatment. The BiFeO3 / Cobalt titanate / TiO2 nanosheet composite material can be used to improve the activation efficiency and stability of PMS in advanced oxidation processes, efficiently degrades organic pollutants in water, and can completely degrade 20 mg / L of Rhodamine B (Rh B) in 1 min and degrade 95% of 200 mg / L of Rhodamine B in 9 min, and has a wide application prospect in the field of organic wastewater treatment.

[0029] Compared with the prior art, the application has the following advantages:

[0030] (1) The method of the application is simple, requires low equipment, has mild reaction conditions, and is easy to control.

[0031] (2) The BiFeO3 / Cobalt titanate / TiO2 nanosheet composite material prepared by the application has a nanosheet structure and a large specific surface area, and can provide more PMS activation sites.

[0032] (3) The BiFeO3 / Cobalt titanate / TiO2 nanosheet composite material prepared by the application has high structural stability and durability, can maintain good activity in multiple cycles, thereby prolonging the service life and stability of the degradation performance.

[0033] (4) The prepared bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material has strong activated PMS activity, and has strong degradation performance on rhodamine B solution with a concentration of 20-400 mg / L, and has a wide application prospect in the field of organic wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 (a) is an SEM picture of the single-crystal Bi2Fe4O9 nanosheet powder sample in Comparative Example 1; Figure 1 (b) is an SEM picture of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1; Figure 1 (c) and Figure 1 (d) are SEM images of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite materials prepared in Example 2 and Example 3, respectively.

[0035] Figure 2 is a TEM image of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1, wherein Figure 2 a is a transmission electron microscope image of Example 1 under a scale of 1 μm, Figure 2 b is Figure 2 a local enlarged view of a, Figure 2 c is a transmission electron microscope image of Example 1 under a scale of 500 nm, Figure 2 d is Figure 2 a local high-resolution transmission image of c.

[0036] Figure 3 is an EDS mapping element distribution of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1; a SEM image of the corresponding area Figure 3 a), and element distribution diagrams of Bi Figure 3 b), O Figure 3 c), Fe Figure 3 d), Ti Figure 3 e), and Co Figure 3 f).

[0037] Figure 4 is a degradation rate curve of the samples prepared in Comparative Example 1, Comparative Example 2, Example 1 and a commercial cobalt oxide for degrading or ultrasonic-activated PMS degrading 20 mg / L rhodamine B aqueous solution, in addition, the degradation performance of only adding PMS without adding any catalyst is taken as a control group.

[0038] Figure 5 is an XRD pattern of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 and a Bi2Fe409(JCPDS:25-0090) standard diffraction card. DETAILED DESCRIPTION

[0039] The application will be further clarified by a consideration of the following detailed description taken in connection with the accompanying drawings. It is understood that these examples are merely illustrative of the present application and should not be considered as limiting the scope of the application.

[0040] Example 1

[0041] (1) 0.5 mmol Co(N03)2-6H20 was dissolved in 20 mL of anhydrous ethanol, and then 0.1 g of the single-crystal Bi2Fe4O9 nanosheet prepared in Comparative Example 1 was added. After ultrasonic dispersion for 20 min, the mixture was continuously stirred for 6 h to form a uniformly dispersed suspension;

[0042] (2) 200 μL of isopropyl titanate was slowly added dropwise to the suspension obtained in step (1), and the mixture was continuously stirred for 1 h;

[0043] (3) 2 mL of a 0.5 M ammonium bicarbonate aqueous solution was slowly added dropwise to the solution obtained in step (2), and the mixture was vigorously stirred for 3 h;

[0044] (4) The precipitate in the solution was centrifugally separated, washed with anhydrous ethanol 3 times, and dried in a vacuum oven at 40 °C for 3 h.

[0045] (5) The powder obtained in step (4) was transferred to a muffle furnace, heated to 450 °C at a temperature increasing rate of 5 °C / min in an air atmosphere, maintained at 450 °C for 2 h, and naturally cooled to room temperature to obtain a Bi2Fe4O9 / cobalt titanate / titanium dioxide nanosheet composite.

[0046] Example 2

[0047] (1) 0.5 mmol Co(N03)2-6H20 was dissolved in 20 mL of anhydrous ethanol, and then 0.1 g of the single-crystal Bi2Fe4O9 nanosheet prepared in Comparative Example 1 was added. After ultrasonic dispersion for 20 min, the mixture was continuously stirred for 6 h to form a uniformly dispersed suspension;

[0048] (2) 100 μL of isopropyl titanate was slowly added dropwise to the suspension obtained in step (1), and the mixture was continuously stirred for 1 h;

[0049] (3) 1 mL of a 0.5 M ammonium bicarbonate aqueous solution was slowly added dropwise to the solution obtained in step (2), and the mixture was vigorously stirred for 3 h;

[0050] (4) The precipitate in the solution was centrifugally separated, washed with anhydrous ethanol 3 times, and dried in a vacuum oven at 40 °C for 3 h.

[0051] (5) The powder obtained in step (4) is transferred into a muffle furnace and heated to 450°C at a heating rate of 5°C / min in an air atmosphere, kept for 2h, and naturally cooled to room temperature to obtain a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0052] Example 3

[0053] (1) 0.5 mmol of Co(N03)2-6H20 is dissolved in 20 mL of anhydrous ethanol, and then 0.1 g of the single-crystal Bi2Fe40g nanosheet prepared in Comparative Example 1 is added. After ultrasonic dispersion for 20 min, sufficient stirring is continued for 6 h to form a uniformly dispersed suspension;

[0054] (2) 300 μL of isopropyl titanate is slowly added dropwise to the suspension obtained in step (1), and stirring is continued for 1 h;

[0055] (3) 3 mL of a 0.5 M aqueous ammonium bicarbonate solution is slowly added dropwise to the solution obtained in step (2), and vigorous stirring is continued for 3 h;

[0056] (4) The precipitate in the solution is centrifugally separated, washed with anhydrous ethanol 3 times, and dried in a vacuum oven at 40°C for 3 h.

[0057] (5) The powder obtained in step (4) is transferred into a muffle furnace and heated to 450°C at a heating rate of 5°C / min in an air atmosphere, kept for 2h, and naturally cooled to room temperature to obtain a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0058] Example 4

[0059] (1) 0.5 mmol of Co(N03)2-6H20 is dissolved in 20 mL of anhydrous ethanol, and then 0.1 g of the single-crystal Bi2Fe40g nanosheet prepared in Comparative Example 1 is added. After ultrasonic dispersion for 20 min, sufficient stirring is continued for 6 h to form a uniformly dispersed suspension;

[0060] (2) 200 μL of isopropyl titanate is slowly added dropwise to the suspension obtained in step (1), and stirring is continued for 1 h;

[0061] (3) 2 mL of a 0.1 M aqueous ammonium bicarbonate solution is slowly added dropwise to the solution obtained in step (2), and vigorous stirring is continued for 3 h;

[0062] (4) The precipitate in the solution is centrifugally separated, washed with anhydrous ethanol 3 times, and dried in a vacuum oven at 40°C for 3 h.

[0063] (5) The powder obtained in step (4) was transferred to a muffle furnace and heated to 450°C at a heating rate of 5°C / min in an air atmosphere, and kept for 2h to obtain a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0064] Example 5

[0065] (1) 0.2mmol Co(NO3)2·6H2O was dissolved in 20mL of anhydrous ethanol, and then 0.1g of the single-crystal Bi2Fe4O9 nanosheet prepared in Comparative Example 1 was added. After ultrasonic dispersion for 20min, the mixture was continuously stirred for 6h to form a uniformly dispersed suspension;

[0066] (2) 200μL of isopropyl titanate was slowly added dropwise to the suspension obtained in step (1), and the mixture was continuously stirred for 1h;

[0067] (3) 2mL of a 0.5M ammonium bicarbonate aqueous solution was slowly added dropwise to the solution obtained in step (2), and the mixture was vigorously stirred for 3h;

[0068] (4) The precipitate in the solution was centrifuged and washed with anhydrous ethanol three times, and dried in a vacuum oven at 40°C for 3h.

[0069] (5) The powder obtained in step (4) was transferred to a muffle furnace and heated to 450°C at a heating rate of 5°C / min in an air atmosphere, and kept for 2h to obtain a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

[0070] Comparative Example 1

[0071] (1) 1mmol Bi(NO3)3·5H2O and 2mmol Fe(NO3)3·9H2O were dissolved in a mixed solution of 37.5mL of deionized water and 2.5mL of glacial acetic acid, and magnetically stirred until completely dissolved to form a red transparent solution;

[0072] (2) 16g of NaOH powder was added to the solution of step (1) to form a brown-red mixed suspension, and the stirring was continued for 2h;

[0073] (3) The solution obtained in step (2) was subjected to hydrothermal reaction at 180°C for 12h, and then naturally cooled to room temperature. The reaction product was removed, washed with deionized water and ethanol three times each, and dried in an oven at 60°C for 12h to obtain a single-crystal Bi2Fe4O9 nanosheet powder sample as a first comparative sample.

[0074] Comparative Example 2

[0075] (1) 0.5 mmol of Co(N03)2-6H20 was dissolved in 20 mL of anhydrous ethanol, and then 0.1 g of the single-crystal Bi2Fe40g nanosheets prepared in Comparative Example 1 was added. After ultrasonic dispersion for 20 min, the mixture was continuously stirred for 6 h to form a uniformly dispersed suspension;

[0076] (2) 200 μL of isopropyl titanate was slowly added dropwise to the suspension obtained in step (1), and the mixture was continuously stirred for 1 h;

[0077] (3) 2 mL of deionized water was slowly added dropwise to the solution obtained in step (2), and the mixture was vigorously stirred for 3 h;

[0078] (4) The precipitate in the solution was centrifuged and washed with anhydrous ethanol for 3 times, and then dried in a vacuum oven at 40 °C for 3 h.

[0079] (5) The powder obtained in step (4) was transferred to a muffle furnace, heated to 450 °C at a heating rate of 5 °C / min in an air atmosphere, and kept for 2 h to obtain a Bi2Fe40g / cobalt oxide / titanium dioxide nanosheet composite.

[0080] Comparative Example 3

[0081] (1) 0.1 g of the single-crystal Bi2Fe40g nanosheets prepared in Comparative Example 1 was dispersed in 20 mL of anhydrous ethanol, and then ultrasonic dispersion was performed for 20 min. The mixture was continuously stirred for 6 h to form a uniformly dispersed suspension;

[0082] (2) 200 μL of isopropyl titanate was slowly added dropwise to the suspension obtained in step (1), and the mixture was continuously stirred for 1 h;

[0083] (3) 2 mL of a 0.5 M aqueous ammonium bicarbonate solution was slowly added dropwise to the solution obtained in step (2), and the mixture was vigorously stirred for 3 h;

[0084] (4) The precipitate in the solution was centrifuged and washed with anhydrous ethanol for 3 times, and then dried in a vacuum oven at 40 °C for 3 h.

[0085] (5) The powder obtained in step (4) was transferred to a muffle furnace, heated to 450 °C at a heating rate of 5 °C / min in an air atmosphere, and kept for 2 h to obtain a Bi2Fe40g / TiO2 nanosheet composite.

[0086] Sample analysis

[0087] Degradation of rhodamine B by activated PMS

[0088] The 5 mg of the composite prepared in Example 1 was dispersed into 50 mL of a rhodamine B solution with a concentration of 20-400 mg / L, and stirred for 30 min to reach adsorption-desorption equilibrium. Then, 0.5 mM PMS was added to the mixture to start the reaction, and the solution was kept at about 25°C during the whole process. At certain time intervals, an aliquot (2 mL) was taken and mixed with 50 mg of sodium thiosulfate (Na2S2O3) to quench the reaction. Next, the mixture was centrifuged at 4000 rpm to separate the solid catalyst. Then, the change in absorbance of the rhodamine B solution was recorded by a UV-Vis spectrophotometer.

[0089] It can be seen from Figure 1 Comparative Example 1 Figure 1 a) that the single-crystal Bi2Fe4O9nanosheet is a regular square flake with a side length of about 500-800 nm and a thickness of about 100-200 nm, and the surface is smooth; Figure 1 (b) is the Bi2Fe4O9nanosheet composite material prepared in Example 1, and it can be seen that a layer of mixed network composite material of cobalt titanate and titanium dioxide is tightly coated on the surface of the Bi2Fe4O9nanosheet. With the increase of the amount of isopropyl titanate (100 μL was added in Example 2, as shown in Figure 1 c; 300 μL was added in Example 3, as shown in Figure 1 d), the thickness and tightness of the coating layer also increase.

[0090] Figure 2 The transmission electron microscope images of the Bi2Fe4O9 / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 at different magnifications can be seen from Figure 2 a, Figure 2 b and Figure 2 c. It can be clearly observed that the Bi2Fe4O9nanosquare flake is coated with a layer of material, which is likely to be a composite cobalt titanate / titanium dioxide layer. Further analysis of the coating layer by high-resolution TEM, as shown in Figure 2 d, it can be observed that there are clear lattice fringes, from which lattice fringes corresponding to the (110) plane of rutile titanium dioxide, and lattice fringes belonging to the (400) and (220) planes of cobalt titanate can be found, indicating that the main components of the coating layer are cobalt titanate and titanium dioxide.

[0091] Figure 3 The EDS mapping element distribution diagram of the Bi2Fe4O9 / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 is shown. The composite material mainly contains Bi, O, Fe, Ti and Co elements, and the distribution of each element is uniform. The atomic ratio of each element in the composite material is shown in Table 1.

[0092] Table 1 is the atomic ratio of each element (EDS mapping) in the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1

[0093] Element At. No. Mass Norm. [%] Atom [%] Abs. error [%] (1 sigma) O 8 27.51 69.20 1.83 Fe 26 28.47 20.52 0.53 Bi 83 40.89 7.87 0.87 Ti 22 1.68 1.41 0.06 Co 27 1.46 1.00 0.07 100.00 100.00

[0094] Figure 4 The concentration change graph of Example 1 and different comparative materials activating PMS to degrade 20 mg / L rhodamine B can be seen that Example 1 has very strong ability to activate PMS to degrade rhodamine B, and can completely degrade rhodamine B in 60 s, while the degradation rate of Comparative Example 1, Comparative Example 2 and commercial cobalt oxide is obviously lower, and it takes more than 200 s to completely degrade, so it can be confirmed that the prepared bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material has significantly improved PMS activation efficiency.

[0095] Figure 5 The XRD pattern of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 can be seen that the main diffraction peaks of the composite material coincide with Bi2Fe409(JCPDS:25-0090); since the content of TiO2 and CoTiO3 is low, only weak diffraction peaks belonging to TiO2 and CoTiO3 can be observed, so the XRD pattern can assist to prove the existence of TiO2 and CoTiO3 in the composite material.

[0096] Table 2 is the experimental conditions and degradation of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 activating PMS to degrade different concentrations of Rh B.

[0097] Rh B concentration PMS concentration pH Catalyst dosage Degradation time Average removal rate 20 mg / L 0.5 mM about 4.9 0.1 g / L about 1 min 100％ 50 mg / L 0.5 mM about 4.7 0.1 g / L about 3 min 100％ 200 mg / L 0.5 mM about 4.4 0.1 g / L about 9 min 95％ 400 mg / L 0.5 mM about 4.2 0.1 g / L about 70 min 91％

[0098] From Table 2, it can be seen that the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material prepared in Example 1 has high degradation efficiency in different concentrations of rhodamine B solution, and the removal rate can reach 100% in low concentration of rhodamine B (20-50 mg / L); in high concentration of rhodamine B (200-400 mg / L), it can also degrade more than 90%.

[0099] In summary, the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material technology for activating PMS to degrade pollutants has many advantages such as high efficiency, environmental friendliness, high durability, wide adaptability and low cost. The application potential of this technology is broad, and it is expected to become an important means to solve the treatment of organic pollutants and environmental protection.

[0100] The above embodiments of the present application are described in detail, it should be understood that the above described are only specific embodiments of the present application, and are not intended to limit the present application, any modification, supplement or similar way of substitution made within the principle range of the present application, should be included in the protection scope of the present application.

Claims

1. Application of a bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite in the field of activated PMS treatment of organic wastewater, characterized in that, The preparation method of the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material comprises the following steps: S1, Co(NO3)2·6H2O is dissolved in an organic solvent, Bi2Fe4O9 nanosheets are added, mixed and stirred to obtain a suspension, and isopropyl titanate is added dropwise to the suspension to obtain a mixed suspension, wherein the ratio of Co(NO3)2·6H2O, organic solvent, Bi2Fe4O9 nanosheets and isopropyl titanate is 0.2-0.5mmol:20mL:0.1g:100-300μL; S2, ammonium bicarbonate aqueous solution is added dropwise to the mixed suspension obtained in step S1, and stirring is carried out to react, and the obtained reaction mixture is centrifuged, and the obtained precipitate is washed and dried, wherein the concentration of the ammonium bicarbonate aqueous solution is 0.1-0.5M, the volume is 5-10 times the volume of isopropyl titanate, and the dropwise addition speed is 100-300μL / min; S3, the product after drying in step S2 is calcined in an air atmosphere to obtain the bismuth ferrite / cobalt titanate / titanium dioxide nanosheet composite material.

2. Use according to claim 1, characterized in that, In step S1, the Bi2Fe4O9 nanosheet is prepared by hydrothermal reaction using Bi(NO3)3·5H2O and Fe(NO3)3·9H2O as raw materials and NaOH as a mineralizer in a solution system of deionized water and acetic acid.

3. Use according to claim 2, characterized in that, The Bi2Fe4O9 nanosheet is a regular nanosheet.

4. Use according to claim 3, characterized in that, The preparation method of the Bi2Fe4O9 nanosheet is as follows: S11. Add Bi(NO3)3·5H2O and Fe(NO3)3·9H2O to a mixed solvent of water and acetic acid to adjust Bi... 3+ with Fe 3+ The molar ratio is 1:1.5-2. Stir to obtain a mixed suspension. S12, NaOH is added to the mixed suspension to make the concentration of NaOH reach 9-11mol / L, and stirring is carried out to obtain a precursor suspension; S13, the precursor suspension is subjected to hydrothermal reaction at 160-200℃ for 6-24h, and after the reaction is completed, the reaction product is filtered, washed and dried to obtain the Bi2Fe4O9 nanosheet.

5. The use according to claim 1, characterized in that, In step S2, the reaction time is 2-4h.

6. Use according to claim 1, characterized in that, In step S3, the calcination conditions are as follows: heating at a heating rate of 5-10℃ / min to 450-600℃, and holding for 1-2h.

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