Self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane, preparation method thereof and application of self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane in Cr (VI) degradation

Abstract

The invention belongs to the technical field of photocatalytic materials, and particularly relates to a self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane, a preparation method thereof and application of the photocatalytic membrane to Cr (VI) degradation. The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane disclosed by the invention comprises more than two layers of titanium meshes and a TiO2 / oxygen vacancy-containing Bi4Ti3O12 composite material loaded on the surface of each layer of titanium mesh. The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane has more than two layers of titanium meshes, can promote the mass transfer process of pollutants, is convenient to recycle, and has certain mechanical strength. The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O12 photocatalytic membrane disclosed by the invention has a relatively good Cr (VI photocatalytic degradation capability under the condition that a cocatalyst is not added.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The application relates to a photocatalytic film, a preparation method thereof and application of the photocatalytic film in degradation of Cr(Ⅵ). BACKGROUND

[0002] Chromium (Cr) and its heavy metal compounds, as important industrial raw materials, play a key role in the fields of national economy such as electroplating, leather manufacturing and textile. However, the Cr(Ⅵ)-containing wastewater generated in the industrial production process has strong toxicity and carcinogenicity, which poses an irreversible threat to human health and the ecological environment. At present, although technologies such as physical adsorption, membrane separation and traditional chemical reduction can partially remove Cr(Ⅵ), there are still some bottlenecks such as complex secondary treatment of adsorbents and high operation cost. Photocatalytic technology, with its green sustainability, has shown unique advantages in the degradation of antibiotics, organic dyes and heavy metal ions, and is considered as a promising solution. However, the actual efficiency of photocatalytic technology is highly dependent on the design of the reaction system, and the form of the catalyst and the mass transfer characteristics of the reactor directly determine its application feasibility.

[0003] Traditional photocatalytic reactors are mainly divided into slurry systems and fixed systems. Among them, the slurry reactor relies on powder catalysts, and although it can achieve high light utilization rate, the separation and recovery of the catalysts are difficult, which greatly increases the actual application cost. Therefore, developing recyclable photocatalytic materials suitable for fixed reactors has become a research hotspot. However, the design of fixed reactors faces two major challenges: first, the mass transfer efficiency in the reaction process is limited, and the contact between pollutants and active sites on the catalyst surface is insufficient, resulting in slow degradation kinetics; second, the existing immobilized catalysts generally have low separation efficiency of photo-generated carriers and poor cycle stability, which restricts their large-scale application.

[0004] Therefore, it is necessary to provide an improved technical solution to overcome the above-mentioned deficiencies of the prior art. SUMMARY

[0005] The application aims to provide a self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The application relates to a photocatalytic film, a preparation method thereof and application of the photocatalytic film in degradation of Cr(Ⅵ).

[0006] To achieve the above-mentioned purpose, the application provides the following technical solution: a self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The application relates to a photocatalytic film, a preparation method thereof and application of the photocatalytic film in degradation of Cr(Ⅵ). 12The photocatalytic membrane comprises two or more layers of titanium mesh and TiO2 / oxygen vacancy Bi4Ti3O 12 Composite material.

[0007] Preferably, the number of layers of the titanium mesh is 2-4 layers; the pore size of the titanium mesh is 40-100 mesh.

[0008] Preferably, the number of layers of the titanium mesh is two layers, the pore sizes of the two layers of the titanium mesh are different, wherein the pore size of one layer of the titanium mesh is 40-60 mesh; the pore size of the other layer of the titanium mesh is 80-100 mesh; or, the number of layers of the titanium mesh is four layers, the pore sizes of the four layers of the titanium mesh are the same.

[0009] Preferably, the method comprises the following steps: (1) anodizing and performing first annealing treatment on the titanium mesh to obtain a titanium mesh loaded with TiO2nanotubes; (2) immersing the titanium mesh loaded with TiO2nanotubes in an alkaline solution of bismuth salt, performing hydrothermal reaction, drying the obtained solid after the hydrothermal reaction, and performing second annealing treatment to obtain a titanium mesh loaded with TiO2 / Vo-Bi4Ti3O 12 Composite material titanium mesh.

[0010] Preferably, in step (1), the anodizing time is 0.9-2.1 h, the anodizing voltage is 49-51 V; the first annealing temperature is 440-460 ℃, the first annealing time is 1.9-2.1 h; the first annealing is performed in an air atmosphere.

[0011] Preferably, the anodizing is performed in an electrolyte, the anode is the titanium mesh, the cathode is platinum, and the power source is direct current.

[0012] More preferably, the components of the electrolyte include NH4F, deionized water and ethylene glycol; the concentration of NH4F in the electrolyte is 2-2.5 mg / mL, and the volume ratio of deionized water to ethylene glycol is 1:(48.5-49.5).

[0013] Further preferably, the method further comprises a step of cleaning the titanium mesh with an acid cleaning solution before the anodizing; and / or, the method further comprises a step of cleaning and drying the titanium mesh after the anodizing.

[0014] Preferably, in step (2), the hydrothermal reaction temperature is 170-190 ℃, the hydrothermal reaction time is 17.9-18.1 h; the second annealing temperature is 340-360 ℃, the second annealing time is 2.9-3.1 h; the second annealing is performed in a nitrogen or noble gas atmosphere.

[0015] Preferably, in step (1), the titanium mesh obtained through the anodic oxidation treatment is placed in an annealing treatment device and then heated to the temperature of the first annealing; and / or, in step (2), the titanium mesh obtained through the hydrothermal reaction treatment is placed in an annealing treatment device and then heated to the temperature of the second annealing.

[0016] Preferably, in step (2), the bismuth salt in the alkaline solution of the bismuth salt is bismuth nitrate, and the mass ratio of bismuth nitrate to the amount of the titanium mesh is 2-10 mg / 4 cm 2 The titanium mesh; the alkali in the alkaline solution of the bismuth salt is NaOH, and the concentration of NaOH is 20 mg / mL.

[0017] The application further provides the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Application of the photocatalytic film, which adopts the technical scheme that the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Application of the photocatalytic film in degrading Cr(Ⅵ).

[0018] The application further provides a photocatalytic reactor, which adopts the technical scheme that the photocatalytic reactor comprises the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic film.

[0019] Preferably, the photocatalytic reactor comprises a circulating container, the circulating container has an inner cavity, and the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film is arranged in the inner cavity, and the inner cavity is configured to enable the sewage to flow in the circulating container in a circulating manner; the circulating container is at least partially transparent, and the light source can be directed to the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic film.

[0020] Preferably, the circulating container comprises an inlet portion and an outlet portion, the inner cavities of the inlet portion and the outlet portion are in communication, and the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film is arranged between the inlet portion and the outlet portion, and the material of the inlet portion is quartz glass.

[0021] Beneficial effects: (1) The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film has two or more layers of titanium meshes, can promote the mass transfer process of pollutants, is convenient to recycle, and has certain mechanical strength. The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film has good photocatalytic degradation ability of Cr(Ⅵ) without adding a catalyst.

[0022] (2) The preparation method of the application makes the prepared self-supporting TiO2 / oxygen vacancy containing Bi4Ti3O 12 The photocatalytic film can only be damaged by strong mechanical external force; the self-supporting TiO2 / oxygen vacancy containing Bi4Ti3O 12 The preparation method of the photocatalytic film makes the TiO2 / oxygen vacancy containing Bi4Ti3O 12 The composite material has good film forming property on the titanium mesh surface, can be used in a large area, and has good application prospect.

[0023] (3) In the self-supporting TiO2 / oxygen vacancy containing Bi4Ti3O 12 The preparation method of the photocatalytic film makes the TiO2 / oxygen vacancy containing Bi4Ti3O 12 (Vo-Bi4Ti3O 12 ) nanostructure is obtained by in-situ growth on the surface of the TiO2 nanotube through a hydrothermal method, the lattice matching degree between the two structures is high, the interface transfer resistance is small, and the migration of photo-generated carriers is facilitated; and due to the ferroelectricity of Vo-Bi4Ti3O 12 , a piezoelectric polarization field is generated under the pressure of water flow flushing in the photocatalytic reaction process, further promoting the separation of the electron-hole pairs; in addition, the existence of the oxygen vacancy also pins the piezoelectric polarization field generated by Vo-Bi4Ti3O 12 , thereby improving the cycle stability of the TiO2 / Vo-Bi4Ti3O 12 composite material.

[0024] (4) In the preparation process of the self-supporting TiO2 / oxygen vacancy containing Bi4Ti3O 12 photocatalytic film, the equipment and raw materials used are cheap, the experimental steps are simple and easy to operate, the product yield and production rate are high, the obtained product has good performance and high stability. BRIEF DESCRIPTION OF DRAWINGS

[0025] The drawings accompanying the specification of the present application serve to provide further understanding of the present application, and the schematic embodiments of the present application and the description thereof serve to explain the present application, and do not constitute improper limitations on the present application. Among them: Figure 1 The self-supporting TiO2 / oxygen vacancy containing Bi4Ti3O 12 photocatalytic film is an embodiment of the present application; Figure 2 The cross-sectional structure schematic diagram of the photocatalytic reactor is an embodiment of the present application; Figure 3 The structure schematic diagram of the photocatalytic reactor is another embodiment of the present application; Figure 4Industrial titanium mesh and self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic membrane (left) and self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic membrane (right); Figure 5 TiO2 / Vo-Bi4Ti3O loaded on the surface of titanium mesh of examples 2 and 3 12 Micro-morphology of the composite material; (a) and (b) are TiO2 / Vo-Bi4Ti3O loaded on the surface of titanium mesh of example 2 12 SEM of the composite material, (c) and (d) are TiO2 / Vo-Bi4Ti3O loaded on the surface of titanium mesh of example 3 12 SEM of the composite material; Figure 6 TiO2 / Vo-Bi4Ti3O loaded on the surface of titanium mesh of example 1 12 TiO2 / Bi4Ti3O loaded on the surface of titanium mesh of comparative example 2 12 Performance test results of the composite material; (a) is the piezoelectric response amplitude curve of TiO2 / Vo-Bi4Ti3O 12 and TiO2 / Bi4Ti3O 12 (b) is the UV-Vis diffuse reflectance absorption test results of TiO2 / Vo-Bi4Ti3O 12 and TiO2 / Bi4Ti3O 12 (c) is the amplitude test results of TiO2 / Vo-Bi4Ti3O 12 (d) is the phase response diagram of TiO2 / Vo-Bi4Ti3O 12 ; Figure 7 Self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Test results of photocatalytic degradation of Cr(Ⅵ) performance of photocatalytic membrane of self-supporting TiO2 / oxygen vacancy Bi4Ti3O Figure 8 Self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Cyclic stability test results of photocatalytic membrane.

[0026] Reference signs: 1 - circulating container; 11 - liquid outlet; 111 - liquid outlet; 112 - liquid outlet pipe; 12 - liquid inlet; 121 - liquid inlet; 122 - liquid inlet pipe; 123 - liquid inlet valve; 13 - flange; 14 - rubber gasket; 2 - self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12Photocatalytic membrane; 3 - light source; 4 - sewage container; 41 - water pump. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0028] The present application will be described in detail below with reference to the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0029] The present application aims at the poor effect of photocatalytic removal of Cr(Ⅵ) at present, and provides a self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic membrane.

[0030] For mass transfer limitation, studies have shown that a high-porosity reticular substrate (such as a titanium mesh) can strengthen mass transfer by inducing turbulent flow and at the same time reduce reaction pressure drop, and is an ideal choice for optimizing the structure of a fixed reactor. However, existing studies have focused on the design of substrate topography, but have ignored the potential of using fluid kinetic energy (such as water pressure) in the reaction system. In recent years, the synergistic regulation strategy of piezoelectric materials and defect engineering has provided a new idea for breaking through the above bottleneck: by introducing a piezoelectric effect, the built-in electric field can be enhanced using water flow mechanical energy to promote carrier separation; and the construction of oxygen vacancies can not only broaden the light absorption range, but also improve the material stability by pinning the polarization electric field.

[0031] The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic membrane of the present application. 12 The photocatalytic membrane includes two or more layers of titanium mesh and TiO2 / Vo-Bi4Ti3O 12 composite material loaded on the surface of each layer of titanium mesh. The photocatalytic membrane is helpful for making full use of water flow pressure and improving the photocatalytic degradation performance of the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 Photocatalytic membrane includes two or more layers of titanium mesh (each layer of titanium mesh surface is loaded with TiO2 / Vo-Bi4Ti3O 12 composite material), which is helpful for making full use of water flow pressure and improving the photocatalytic degradation performance of the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 photocatalytic membrane of the present application.

[0032] Preferably, in the TiO2 / Vo-Bi4Ti3O 12 composite material, TiO2 is loaded on the surface of the titanium mesh in a nanotube structure; and Vo-Bi4Ti3O12 Nanoparticles are uniformly dispersed on TiO2 nanotubes. Specifically, TiO2 / oxygen-vacancy Bi4Ti3O supported on the surface of a titanium mesh. 12 In composite materials, oxygen-containing vacancies Bi4Ti3O 12 (Abbreviated as Vo-Bi4Ti3O) 12 The Cr(VI) is uniformly distributed on TiO2, and the tubular structure of TiO2 is conducive to the adsorption of Cr(III) and the dissociation of Cr(VI); the dispersed Vo-Bi4Ti3O 12 It possesses piezoelectric properties and can utilize the kinetic energy of water flow to generate a piezoelectric polarization field under water pressure, promoting the separation of photogenerated carriers. Additionally, Bi4Ti3O... 12 Oxygen vacancies in the material make domain wall inversion difficult, pinning the piezoelectric polarization field of the material and thus improving its photocatalytic degradation performance.

[0033] The self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O of the present invention 12 The photocatalytic membrane exhibits strong photocatalytic degradation performance without the addition of any sacrificial agents (e.g., it can be used for the photocatalytic degradation of hexavalent chromium). Furthermore, the self-supporting TiO2 / oxygen-vacancy Bi4Ti3O of this invention... 12 Photocatalytic membranes have self-supporting properties, making them easy to recycle.

[0034] The self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O of the present invention 12 In a preferred embodiment of the photocatalytic membrane, the titanium mesh has 2-4 layers and a pore size of 40-100 mesh. However, if the number of titanium mesh layers is too small, it cannot fully utilize the water flow pressure; if the number of layers is too large, it will hinder photon propagation and reduce catalytic efficiency. If the pore size of the titanium mesh is too large, the turbulent kinetic energy of the pollutants will be low, resulting in a reduced mass transfer rate and a decreased reaction rate; if the pore size of the titanium mesh is too small, the mechanical strength of the industrial titanium mesh will decrease, leading to subsequent clogging by pollutants.

[0035] The self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O of the present invention 12 In a preferred embodiment of the photocatalytic membrane, the titanium mesh consists of two layers with different pore sizes: one layer has a pore size of 40-60 mesh, and the other has a pore size of 80-100 mesh. By creating these different pore sizes, a hierarchical pore structure is formed, which helps to promote the mass transfer process in the reaction and thus improves the photocatalytic degradation effect.

[0036] The self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O of the present invention 12 In a preferred embodiment of the photocatalytic membrane, the titanium mesh consists of four layers, all with identical pore sizes. Having four layers with the same pore size helps to achieve better photocatalytic degradation results.

[0037] The application further provides a self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 A preparation method of the photocatalytic film, the self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 The preparation method of the photocatalytic film comprises the following steps: (1) performing anodic oxidation and first annealing treatment on the titanium mesh to obtain the titanium mesh loaded with TiO2 nanotubes; (2) immersing the titanium mesh loaded with TiO2 nanotubes into an alkaline solution of a bismuth salt, performing hydrothermal reaction, drying (for example, the titanium mesh loaded with TiO2 nanotubes after drying is light yellow) and second annealing treatment on the obtained solid after the hydrothermal reaction, and obtaining the titanium mesh loaded with TiO2 / Vo-Bi4Ti3O 12 The titanium mesh of the composite material.

[0038] In step (2), the Bi4Ti3O 12 (in the alkaline solution of the bismuth salt, the bismuth salt is used to provide a bismuth source; the alkaline environment can play a role in dissolving TiO2) is generated in situ on the TiO2 through the second annealing treatment (which is helpful to make the crystallinity of the product better and introduce oxygen vacancies), and the titanium mesh loaded with TiO2 / Vo-Bi4Ti3O 12 The titanium mesh of the composite material. 12 The structure is obtained by growing in situ on the surface of the TiO2 nanotube through a hydrothermal method, the lattice matching degree between the two structures is high, the interface transfer resistance is small, and the migration of photo-generated carriers is facilitated. In addition, the Vo-Bi4Ti3O 12 has ferroelectric properties, can generate a piezoelectric polarization field under water flow pressure, and promotes the separation of photo-generated carriers. In addition, the oxygen vacancies in the Vo-Bi4Ti3O 12 make the domain wall difficult to reverse and pin the piezoelectric polarization field of the material, so that the TiO2 / Vo-Bi4Ti3O 12 composite material has high cycle stability and photocatalytic degradation performance.

[0039] In addition, the method of the application makes the TiO2 / Vo-Bi4Ti3O 12 composite material loaded on the surface of the titanium mesh have good film-forming properties, can be damaged only under strong mechanical external force, can be used in a large area, and has good application prospects. The equipment and raw materials used in the method of the application are cheap, the experimental steps are simple and easy to operate, the product yield and production rate are high, the obtained product has good performance and high stability.

[0040] The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12In a preferred embodiment of the method for preparing the photocatalytic film, the following steps are further included: the multi-layer titanium mesh (two or more layers of titanium mesh) treated by steps (1) and (2) are laminated together, thereby obtaining the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film. For example, the titanium mesh treated by steps (1) and (2) are laminated together, thereby obtaining the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film.

[0041] The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 In a preferred embodiment of the method for preparing the photocatalytic film, in step (1), the anodization time is 0.9-2.1 h (for example, 0.9 h, 1.2 h, 1.5 h, 1.9 h, 2.0 h or 2.1 h), the anodization voltage is 49-51 V (for example, 49 V, 50 V or 51 V), the first annealing temperature is 440-460 ℃ (for example, 440 ℃, 450 ℃ or 460 ℃), and the first annealing time is 1.9-2.1 h (for example, 1.9 h, 2.0 h or 2.1 h). The first annealing is performed in an air atmosphere. If the anodization time is too short, it is not sufficient to form TiO2nanotubes; if the anodization time is too long, it will lead to a decrease in carrier transport efficiency. If the anodization voltage is too small, it will lead to a long oxidation time and cause energy consumption; if the anodization voltage is too high, it will lead to the rupture of industrial titanium mesh and the failure to continue the preparation of nanotubes; if the first annealing temperature is too low, it will lead to poor crystallinity of TiO2nanotubes; and if the first annealing temperature is too high, it will lead to the phase transition of TiO2, which is not worth the cost.

[0042] The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 In a preferred embodiment of the method for preparing the photocatalytic film, the anodization is performed in an electrolyte, the anode is the titanium mesh, the cathode is platinum, and the power source is direct current.

[0043] The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 In a preferred embodiment of the method for preparing the photocatalytic film, the electrolyte comprises NH4F, deionized water and ethylene glycol. Preferably, the concentration of NH4F in the electrolyte is 2-2.5 mg / mL (for example, 2 mg / mL, 2.1 mg / mL, 2.2 mg / mL, 2.3 mg / mL, 2.4 mg / mL or 2.5 mg / mL), and the volume ratio of deionized water to ethylene glycol is (48.5-49.5) (for example, 1:48.5, 1:49 or 1:49.5).

[0044] The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 In a preferred embodiment of the preparation method of the photocatalytic film, before the anodization, the titanium mesh is further cleaned with an acid cleaning solution; and / or, after the anodization, the titanium mesh is further cleaned (for example, with deionized water) and dried.

[0045] Preferably, the components of the acid cleaning solution include HNO3 and HF.

[0046] The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 In a preferred embodiment of the preparation method of the photocatalytic film, in step (2), the hydrothermal reaction temperature is 170-190℃ (for example, 170℃, 175℃, 180℃, 185℃ or 190℃), the hydrothermal reaction time is 17.9-18.1 h (for example, 17.9 h, 18.0 h or 18.1 h); the second annealing temperature is 340-360℃ (for example, 340℃, 345℃, 350℃, 355℃ or 360℃), and the second annealing time is 2.9-3.1 h (for example, 2.9 h, 3.0 h or 3.1 h); wherein, if the hydrothermal temperature is too low, impurities are easily formed; if the hydrothermal temperature is too high, excessive energy consumption is caused; if the hydrothermal time is too short, Bi4Ti3O 12 is not formed; if the hydrothermal time is too long, Bi4Ti3O 12 is too large, which is not conducive to the reaction; if the second annealing temperature is too low, the crystallization of Bi4Ti3O 12 is poor, and it is not easy to form oxygen vacancies; if the second annealing temperature is too high, Bi4Ti3O 12 easily forms impurities; if the second annealing time is too short, the number of oxygen vacancies is too small, which is not enough to pin the oxygen vacancies; if the second annealing time is too long, the structure of Bi4Ti3O 12 is easily collapsed, which is not conducive to the reaction, and the second annealing is carried out in a nitrogen or rare gas (preferably argon) atmosphere.

[0047] The self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 In a preferred embodiment of the preparation method of the photocatalytic film, the bismuth salt in the alkaline solution of the bismuth salt is bismuth nitrate, and the mass ratio of the bismuth nitrate to the amount of the titanium mesh is 2-10 mg / 4 cm 2 of the titanium mesh (for example, 2 mg / 4 cm 2 of the titanium mesh, 3 mg / 4 cm 2 of the titanium mesh, 4 mg / 4 cm 2 of the titanium mesh, 5 mg / 4 cm 2 of the titanium mesh, 6 mg / 4 cm 2Titanium mesh, 7mg / 4 cm 2 Titanium mesh, 8mg / 4 cm 2 Titanium mesh, 9mg / 4 cm 2 Titanium mesh or 10mg / 4 cm 2 (Titanium mesh); the alkali in the alkaline solution of bismuth salt is sodium hydroxide, with a concentration of 19-21 mg / mL (e.g., 19 mg / mL, 19.5 mg / mL, 20 mg / mL, 20.5 mg / mL, or 21 mg / mL). If the proportion of bismuth salt used is too small, the Bi source will be insufficient to form Bi₄Ti₃O₃. 12 Nanostructures, if the proportion of bismuth salt is too high, will generate larger Bi4Ti3O. 12 The nanostructure exhibits severe carrier recombination. If the alkali concentration is too low (pH too low), Bi2Ti2O7 will be formed; if the alkali concentration is too high (pH too high), TiO2 will be over-dissolved, reducing the catalytic performance of the material.

[0048] Preferably, the pH of the alkaline solution of the bismuth salt is 12.8-13.2 (e.g., 12.8, 12.9, 13.0, 13.1 or 13.2).

[0049] This invention also proposes a self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O structure as described above. 12 Application of photocatalytic membranes, in this embodiment of the invention, a self-supporting TiO2 / oxygen-vacancy Bi4Ti3O 12 Application of photocatalytic membrane degradation of Cr(VI).

[0050] This invention also proposes a photocatalytic reactor, wherein the photocatalytic reactor of this embodiment comprises the self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O as described above. 12 Photocatalytic membrane.

[0051] like Figures 2-3 ( Figure 3 As shown by the arrow (indicated by the direction of light), in a preferred embodiment of the photocatalytic reactor of the present invention, the photocatalytic reactor is used for photocatalytic degradation of wastewater; the photocatalytic reactor includes a circulation container 1, the circulation container 1 having an inner cavity, a photocatalytic membrane 2 disposed in the inner cavity, the inner cavity being configured to allow wastewater to circulate within the circulation container 1; the circulation container 1 is at least partially transparent, allowing the light source to be directed towards the self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O 12 2. Photocatalytic membrane.

[0052] In a preferred embodiment of the photocatalytic reactor of the present invention, the circulation container 1 includes an inlet section 12 and an outlet section 11, the inner cavities of the inlet section 12 and the outlet section 11 are connected, and a self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O 12The photocatalytic film 2 is arranged between the liquid inlet part 12 and the liquid outlet part 11; the material of the liquid inlet part 12 is quartz glass. The quartz glass material of the liquid inlet part 12 has good light transmittance, which helps to ensure that the light source can better irradiate the self-supporting TiO2 / vo-Bi4Ti3O 12 The surface of the photocatalytic film 2 ensures the photocatalytic effect of the photocatalytic reactor of the application.

[0053] Preferably, the material of the liquid outlet part 11 is PMMA (polymethyl methacrylate). PMMA is inexpensive, which helps to reduce the manufacturing cost of the photocatalytic reactor of the application.

[0054] Preferably, the liquid inlet part 12 and the liquid outlet part 11 are connected through the flange 13.

[0055] More preferably, the liquid inlet part 12 and the liquid outlet part 11 are further provided with a rubber gasket 14 (which helps to ensure the sealing of the connection between the liquid inlet part and the liquid outlet part).

[0056] Preferably, the liquid inlet part 12 is provided with a liquid inlet port 121, the liquid outlet part 11 is provided with a liquid outlet port 111, the liquid outlet port 111 is provided with a liquid outlet pipe 112, one end of the liquid outlet pipe 112 away from the liquid outlet port 111 is connected with the sewage container 4; the liquid inlet port 121 is provided with a liquid inlet pipe 122, one end of the liquid inlet pipe 122 away from the liquid inlet port 121 is connected with the water pump 41, and the water pump 41 is arranged in the sewage container 4. The sewage container 4 is filled with sewage. The sewage container 4 can be used to take samples from the sewage container 4 during use of the photocatalytic reactor of the application, so as to sample and detect the concentration of pollutants in the sewage and realize real-time monitoring of the photocatalytic degradation effect of the pollutants.

[0057] More preferably, the liquid inlet pipe 122 is provided with a liquid inlet valve 123.

[0058] The self-supporting TiO2 / vo-Bi4Ti3O 12 The photocatalytic film, the preparation method thereof and the application of the photocatalytic film in degrading Cr(Ⅵ) are described in detail.

[0059] In the following examples, the raw materials used are commercially available unless otherwise specified; the sources of the main raw materials are shown in Table 1: Table 1

[0060] Example 1 The self-supporting TiO2 / vo-Bi4Ti3O 12 The preparation method of the thin film includes the following steps: (1) Preparation of TiO2 nanotube array, comprising the following steps: A1. Prepare 15 mL, 5 mL and 80 mL of high purity HNO3, HF (99.99%) and deionized water respectively to prepare an acid pickling solution, then pickling a titanium mesh (industrial titanium mesh; the size of the titanium mesh is 2x2 cm 2 ) for 20 s, and then rinsing with deionized water; A2. Weigh 0.2031 g of NH4F, and prepare 1.8 mL, 88.2 mL of deionized water and ethylene glycol respectively to prepare an electrolyte, then place the pickled titanium mesh as an anode and Pt as a cathode in the electrolyte, and oxidize by a direct current power supply (voltage is 50V); if the titanium mesh is a 40 mesh titanium mesh, the oxidation time is 2h; if the titanium mesh is an 80 mesh titanium mesh, the oxidation time is 1h; the setting of the above oxidation time helps to load the same specific surface area of TiO2 nanotubes on the surface of the 40 mesh titanium mesh and the 80 mesh titanium mesh; A3. After the oxidation of the titanium mesh is completed, it is washed and dried with deionized water, and then placed in a tube furnace, heated from room temperature to 450℃ at a rate of 2℃ / min in an air atmosphere, and annealed for 2h (first annealing), to obtain a titanium mesh loaded with TiO2 nanotubes.

[0061] (2) Preparation of self-supporting TiO2 / Vo-Bi4Ti3O 12 thin film with hierarchical pore structure, comprising the following steps: B1. Weigh 5 mg of Bi(NO3)3, 1 g of NaOH and 50 mL of deionized water, and mix them uniformly to obtain a bismuth salt alkaline solution; B2. Immerse the titanium mesh loaded with TiO2 nanotubes in the bismuth salt alkaline solution, and place it in the inner liner of the reaction kettle; B3. Keep the high-temperature test box at 180℃, and hydrothermal reaction for 18h; B4. After the hydrothermal reaction is completed, the titanium mesh is taken out and dried at 50℃ for 12h; B5. Place the dried titanium mesh in a tube furnace, select argon as a protective gas, heat the tube furnace from room temperature to 350℃ and anneal for 3h (second annealing), and then take it out and seal it for preservation.

[0062] (3) The 40 mesh titanium mesh (size is 2x2 cm 2 ) obtained by steps (1)-(2) and the 80 mesh titanium mesh (size is 2x2 cm 2 ) obtained by steps (1)-(2) are pasted together, to obtain the self-supporting TiO2 / Vo-Bi4Ti3O 12 photocatalytic film of the present embodiment (self-supporting TiO2 / Vo-Bi4Ti3O 12The photocatalytic film comprises two layers of titanium mesh.

[0063] (4) Product storage The prepared self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film is stored in a sample bag and sealed to prevent moisture, acid, alkali and salt erosion, and light. The storage temperature is 25 DEG C and the relative humidity is 10%.

[0064] Wherein, Figure 1 The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The preparation flow chart of the photocatalytic film is correct and in order.

[0065] The morphology and structure of the photocatalytic film prepared in this example are analyzed: Figure 4 The left figure is the industrial titanium mesh and the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The right figure is the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The TiO2 / Vo-Bi4Ti3O 12 The micro-morphology of the composite material; from Figure 4 It can be seen that: Vo-Bi4Ti3O 12 The nanoparticles are uniformly dispersed on the TiO2 nanotube, which can generate a strong piezoelectric polarization field to promote the separation of photo-generated electron-hole pairs when the pollutants pass through, and also broaden the light absorption range of the film and improve its practical value.

[0066] Example 2 The difference between this example and example 1 is only that in step (2), the amount of Bi (NO3) 3 is 2 mg; the rest is the same as example 1.

[0067] Example 3 The difference between this example and example 1 is only that in step (2), the amount of Bi (NO3) 3 is 10 mg; the rest is the same as example 1.

[0068] Example 4 The difference between this example and example 1 is only that the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film is composed of 4 layers of titanium mesh (the pore size of the 4 layers of titanium mesh is 40 / 40 / 80 / 80 mesh in turn), and the rest is the same as example 1. The 4 layers of titanium mesh treated by steps (1)-(2) are pasted together to obtain the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 photocatalytic film.

[0069] Example 5 The difference between this example and Example 1 is only that the self- supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 The photocatalytic film was composed of 4 layers of titanium mesh (the pore sizes of the 4 layers of titanium mesh were 40 / 40 / 40 / 40 mesh in turn), and the rest were consistent with Example 1. The 4 layers of titanium mesh obtained after steps (1)-(2) were pasted together to obtain the self-supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 photocatalytic film.

[0070] Example 6 The difference between this example and Example 1 is only that the self- supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 The photocatalytic film was composed of 4 layers of titanium mesh (the pore sizes of the 4 layers of titanium mesh were 80 / 80 / 80 / 80 mesh in turn), and the rest were consistent with Example 1. The 4 layers of titanium mesh obtained after steps (1)-(2) were pasted together to obtain the self-supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 photocatalytic film.

[0071] Example 7 The difference between this example and Example 1 is only that two 40-mesh titanium meshes obtained after steps (1)-(2) were pasted together to obtain the self-supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 photocatalytic film; and the rest were consistent with Example 1.

[0072] Example 8 The difference between this example and Example 1 is only that two 80-mesh titanium meshes obtained after steps (1)-(2) were pasted together to obtain the self-supported TiO2 / oxygen vacancy-containing Bi4Ti3O 12 photocatalytic film; and the rest were consistent with Example 1.

[0073] Comparative Example 1 The difference between this comparative example and Example 1 is only that in step (1), the anodized titanium mesh was directly placed in a tube furnace at 450°C for annealing for 2 h under an air atmosphere (compared with Example 1, the process of raising the temperature of the tube furnace from room temperature to 450°C after placing the anodized titanium mesh in the tube furnace was omitted); and the rest were consistent with Example 1.

[0074] Comparative Example 2 The difference between this comparative example and Example 1 is only that in step (2), the step of annealing at 350°C for 2 h under an argon atmosphere was omitted (i.e., the second annealing was omitted); and the rest were consistent with Example 1.

[0075] Comparative Example 3 The difference between this comparative example and Example 2 is only that in step (1), the anodized titanium mesh is directly placed in a tube furnace at 450°C and annealed for 2h under air atmosphere (compared with Example 1, the process of placing the anodized titanium mesh into the tube furnace and then heating the tube furnace from room temperature to 450°C is omitted); the rest is consistent with Example 2.

[0076] Comparative Example 4 The difference between this comparative example and Example 2 is only that in step (2), the step of annealing at 350°C for 2h under argon atmosphere is omitted; the rest is consistent with Example 2.

[0077] Comparative Example 5 The difference between this comparative example and Example 3 is only that in step (1), the anodized titanium mesh is directly placed in a tube furnace at 450°C and annealed for 2h under air atmosphere (compared with Example 1, the process of placing the anodized titanium mesh into the tube furnace and then heating the tube furnace from room temperature to 450°C is omitted); the rest is consistent with Example 3.

[0078] Comparative Example 6 The difference between this comparative example and Example 3 is only that in step (2), the step of annealing at 350°C for 2h under argon atmosphere is omitted; the rest is consistent with Example 3.

[0079] Comparative Example 7 The difference between this comparative example and Example 1 is only that a 40-mesh titanium mesh treated by steps (1)-(2) is used; the rest is consistent with Example 1.

[0080] Comparative Example 8 The difference between this comparative example and Example 1 is only that a 80-mesh titanium mesh treated by steps (1)-(2) is used; the rest is consistent with Example 1.

[0081] Experimental Example 1. SEM test: The SEM images of Example 2 and Example 3 are shown in Figure 5 ; Among them, (a) and (b) are the SEM images of the TiO2 / Vo-Bi4Ti3O 12 composite material loaded on the surface of the titanium mesh of Example 2, and (c) and (d) are the SEM images of the TiO2 / Vo-Bi4Ti3O 12 composite material loaded on the surface of the titanium mesh of Example 3. It can be seen from Figure 5 that when the amount of Bi(NO3)3 is small, agglomerated Bi4Ti3O 12Particles hinder the light absorption of TiO2 nanotubes; when the amount of Bi(NO3)3 is too large, excessively large Bi4Ti3O particles will form. 12 Particles reduce the transport rate of charge carriers.

[0082] 2. Piezoelectric response amplitude, UV-Vis diffuse reflection and absorption, and amplitude and phase response tests: Example 1: TiO2 / Vo-Bi4Ti3O loaded on the surface of a titanium mesh 12 The composite material and the titanium mesh surface supported on TiO2 / Bi4Ti3O in Comparative Example 2 12 The test results of the piezoelectric response amplitude of the composite material are as follows: Figure 6 As shown in Figure (a); it can be seen from this figure that: with TiO2 / Bi4Ti3O 12 Compared to TiO2 / Vo-Bi4Ti3O 12 The phase transition point is significantly delayed, which indicates a larger coercive electric field (Ec) and confirms the stabilizing effect of oxygen vacancy pinning domain walls.

[0083] TiO2 / Vo-Bi4Ti3O 12 and TiO2 / Bi4Ti3O 12 The test results of UV-Vis diffuse reflectance absorption are as follows: Figure 6 As shown in Figure (b), both samples exhibit strong absorption in the ultraviolet region, while the in-situ grown Bi4Ti3O4 shows a weaker absorption. 12 Imparting TiO2 / Vo-Bi4Ti3O 12 It exhibits the strongest absorption intensity in the visible light region. Furthermore, TiO2 / Vo-Bi4Ti3O 12 The redshift absorption edge is likely due to oxygen vacancies introducing new defect levels within the band gap, thereby narrowing the band gap and expanding the visible light absorption range.

[0084] TiO2 / Vo-Bi4Ti3O 12 The test results of amplitude and phase response are as follows Figure 6 As shown in (c)-(d), the amplitude signal of the catalyst is relatively weak in the absence of an external electric field. The introduction of oxygen vacancies, however, enhances the performance of TiO2 / Vo-Bi4Ti3O. 12 It exhibits a clear phase contrast, reflecting that it has ferroelectric domains with uniform polarization orientation.

[0085] 3. Photocatalytic degradation performance test: The self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O of the above embodiment 12The photocatalytic film and the photocatalytic film of the comparative example are used for photocatalytic degradation of Cr(Ⅵ) (photocatalytic degradation of Cr(Ⅵ) into Cr(Ⅲ)), and the photocatalytic degradation experiment is carried out in the photocatalytic reactor of the application; the specific process is as follows: (1) As shown in Figures 2-3 , the material of the feed part 12 of the photocatalytic reactor is quartz glass (the material of the discharge part 11 is PMMA), and before starting the degradation of heavy metal pollutants, a light source 3 is placed on one side of the feed part 12.

[0086] (2) When the degradation experiment is carried out using the photocatalytic reactor, a rubber gasket 14 is added in the middle of the feed part 12 and the discharge part 11 to ensure the sealing of the photocatalytic reactor 1, and a plurality of screws and nuts are used to tightly connect the two through the flange 13.

[0087] (3) Turn on the xenon lamp (500 W) light source 3 to enable the light to irradiate on the photocatalytic film 2, and continue to illuminate for 1.5 h to carry out the photocatalytic degradation of Cr(Ⅵ) reaction (during the reaction process, the sewage containing Cr(Ⅵ) circulates between the feed part 12 and the discharge part 11; specifically, the sewage (the initial concentration of Cr(Ⅵ) sewage is 5 mg / L, and the volume is 150 mL) in the sewage container 4 can flow from the inlet 121 into the inlet part 12, then pass through the photocatalytic film 2 into the outlet part 11, and then flow out from the outlet 111 of the outlet part 11 into the sewage container 4; repeat this process to realize the circulation of the sewage (the experiment is maintained for 1.5 h); as shown in Figure 3 ).

[0088] (4) During the reaction process, a certain amount of pollutants is taken at intervals (for example, sampling can be carried out from the sewage container 4; as shown in Figure 3 ) and the absorbance is measured by the ultraviolet spectrophotometer, and then the reaction kinetic constant is obtained.

[0089] The experimental results of the reaction kinetic constant are shown in Figure 7 and Table 2 below: Table 2

[0090] The self-supporting TiO2 / containing oxygen vacancy Bi4Ti3O 12 The photocatalytic film can photocatalytically degrade Cr(Ⅵ) (converts hexavalent chromium into trivalent chromium) in the absence of a sacrificial agent, and the reaction kinetic constant is large; Comparative examples 1, 2 and 3. The performance of example 1 reaches the highest, because the change of the raw material ratio will cause the change of the micro-morphology of Bi4Ti3O 12 , so that example 1 can retain the morphology of TiO2 nanotubes and will not form too large Bi4Ti3O 12Particle size. Compared with examples 2, 3, it is more conducive to the separation and transmission of photo-generated carriers, and compared with example 4, the backscattering rate of photons is low, the utilization rate of sunlight is high, so it has better photocatalytic degradation of Cr(Ⅵ) performance.

[0091] Examples 7, 8, compared with example 1, the photocatalytic performance also decreased. The reason is that: the two layers of titanium mesh in example 1 have different pore sizes, forming a stepped pore structure, and the stepped pore structure of the titanium mesh can introduce more turbulent energy; compared with the same mesh of two layers of titanium mesh (which cannot form a stepped pore structure), the mass transfer process is accelerated, so that the pollutants can reach the catalyst surface faster, so the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film has better photocatalytic degradation of Cr(Ⅵ) performance. 12 The photocatalytic film has better photocatalytic degradation of Cr(Ⅵ) performance.

[0092] Examples 4-6 of self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film contains 4 layers of titanium mesh, but the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film has better photocatalytic degradation of Cr(Ⅵ) performance.

[0093] The photocatalytic film prepared by comparative examples 1, 3, 5 is applied to the photocatalytic degradation of Cr(Ⅵ): it is found that the degradation rate is low. The reason is that: comparative examples 1-3, in the first annealing, directly place the anodized titanium mesh in the tube furnace at 450℃ for annealing (relative to the corresponding example, the process of heating from room temperature to 450℃ is omitted), so that the crystallinity of TiO2 is poor, which hinders the separation and transmission of photo-generated carriers in space, so the photocatalytic degradation of Cr(Ⅵ) performance is poor. 12 The photocatalytic film prepared by comparative examples 1, 3, 5 is applied to the photocatalytic degradation of Cr(Ⅵ): it is found that the degradation rate is low. The reason is that: comparative examples 1-3, in the first annealing, directly place the anodized titanium mesh in the tube furnace at 450℃ for annealing (relative to the corresponding example, the process of heating from room temperature to 450℃ is omitted), so that the crystallinity of TiO2 is poor, which hinders the separation and transmission of photo-generated carriers in space, so the photocatalytic degradation of Cr(Ⅵ) performance is poor.

[0094] Comparative examples 2, 4, 6, compared with examples 1, 2, 3, the photocatalytic degradation performance also decreased. The reason is that: the TiO2 / Vo-Bi4Ti3O 12 The thin film contains oxygen vacancies, which on the one hand improves the light absorption capacity of the material, and on the other hand pins the piezoelectric polarization field of the ferroelectric material, which continuously drives the carrier transmission; and comparative examples 2, 4 and 6 omit the second annealing step, and do not contain oxygen vacancies, so the photocatalytic degradation of Cr(Ⅵ) performance is decreased.

[0095] Compared with Example 1, Comparative Examples 7 and 8 showed a decrease in photocatalytic performance. This is because the single-layer titanium mesh cannot provide a greater water flow pressure, which reduces the piezoelectric polarization field of the material and worsens the carrier separation ability. Therefore, its photocatalytic degradation performance of Cr(VI) decreases.

[0096] 4. Stability Test: The stability of Example 1 was tested according to the above-described method for testing photocatalytic degradation performance. The test results are as follows: Figure 8 As shown: Depend on Figure 8 It can be seen that the self-supporting TiO2 / oxygen-containing vacancy Bi4Ti3O in Example 1 12 After four cycles of testing, the photocatalytic membrane maintained its photocatalytic performance for Cr(VI) essentially unchanged, demonstrating good stability.

[0097] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 A photocatalytic film characterized by, The self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 The photocatalytic film comprises two or more layers of titanium mesh and TiO2 / oxygen vacancy Bi4Ti3O loaded on the surface of each layer of the titanium mesh 12 Composite material.

2. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 A photocatalytic film characterized by comprising a porous film and a photocatalytic layer, The titanium mesh has 2-4 layers; the titanium mesh has a pore size of 40-100 mesh; Preferably, the titanium mesh has two layers, the pore size of the two layers of the titanium mesh is different, wherein the pore size of one layer of the titanium mesh is 40-60 mesh, and the pore size of the other layer of the titanium mesh is 80-100 mesh; or, the titanium mesh has four layers, the pore size of the four layers of the titanium mesh is the same.

3. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Process for the production of a photocatalytic film, characterized in that, The method comprises the following steps: (1) anodizing and performing first annealing treatment on the titanium mesh to obtain a titanium mesh loaded with TiO2 nanotubes; (2) immersing the titanium mesh loaded with TiO2 nanotubes into an alkaline solution of bismuth salt, hydrothermal reaction, drying and second annealing treatment to the obtained solid after the hydrothermal reaction, to obtain TiO2 / Vo-Bi4Ti3O12 nanotube composite material loaded titanium mesh 12 Titanium mesh of composite material.

4. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Process for the production of a photocatalytic film, characterized in that, In step (1), the anodizing time is 0.9-2.1 h, and the anodizing voltage is 49-51 V; The first annealing temperature is 440-460 ℃, and the first annealing time is 1.9-2.1 h; the first annealing is performed in an air atmosphere; Preferably, the anodizing is performed in an electrolyte, the anode is the titanium mesh, the cathode is platinum, and the power source is direct current; More preferably, the electrolyte comprises NH4F, deionized water and ethylene glycol; the concentration of NH4F in the electrolyte is 2-2.5 mg / mL, and the volume ratio of deionized water to ethylene glycol is 1:(48.5-49.5); Further preferably, the method further comprises a step of cleaning the titanium mesh with an acid cleaning solution before the anodizing; and / or, the method further comprises a step of cleaning and drying the titanium mesh after the anodizing.

5. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Process for the production of a photocatalytic film, characterized in that, In step (2), the hydrothermal reaction temperature is 170-190 ℃, and the hydrothermal reaction time is 17.9-18.1 h; The second annealing temperature is 340-360 ℃, and the second annealing time is 2.9-3.1 h; the second annealing is performed in a nitrogen or noble gas atmosphere.

6. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 A method for producing a photocatalytic film, characterized by In step (1), the titanium mesh obtained after the anodizing treatment is placed in an annealing treatment device and then heated to the first annealing temperature; and / or, In step (2), the titanium mesh obtained after the hydrothermal reaction treatment is placed in an annealing treatment device and then heated to the second annealing temperature.

7. The self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Process for the production of a photocatalytic film, characterized in that, In step (2), the bismuth salt in the alkaline solution of the bismuth salt is bismuth nitrate, and the mass ratio of bismuth nitrate to the amount of titanium mesh is 2-10 mg / 4 cm 2 titanium mesh; The base in the alkaline solution of the bismuth salt is NaOH, and the concentration of NaOH is 20 mg / mL.

8. The self-supported TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Application of photocatalytic membranes to degrade Cr(VI).

9. A photocatalytic reactor, characterized by, The photocatalytic reactor comprises a self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Photocatalytic membrane.

10. The photocatalytic reactor of claim 9, wherein, The photocatalytic reactor comprises a circulating container having an inner cavity, the self-supporting TiO2 / oxygen vacancy Bi4Ti3O 12 A photocatalytic membrane is disposed in the inner cavity, which is configured to enable the circulating flow of sewage within the circulating container; The circulation container is at least partially transparent, enabling a light source to be directed at the self-supporting TiO2 / oxygen-vacancy-containing Bi4Ti3O 12 Photocatalytic film; Preferably, the circulation container comprises a liquid inlet part and a liquid outlet part, inner cavities of the liquid inlet part and the liquid outlet part are communicated, the self-supporting TiO2 / oxygen vacancy-containing Bi4Ti3O 12 A photocatalytic film is arranged between the liquid inlet part and the liquid outlet part, and the material of the liquid inlet part is quartz glass.

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