阅读说明：本技术 一种复合光催化剂及其制备方法和应用 (Composite photocatalyst and preparation method and application thereof ) 是由 夏兵 卢耀斌 栾天罡 于 2021-09-13 设计创作，主要内容包括：本发明提供一种复合光催化剂及其制备方法和应用,利用光电催化来实现纳米基底/锰系氧化物复合光催化剂制备,制备方法工序简单易操作,不需要添加任何试剂,不造成环境污染。将本发明制得的光催化剂或复合光催化剂应用于污水处理,所能降解的有机物种类多,使用范围广,相较于污水中有机物的生物处理而言,本发明的处理方法所需要的周期短,操作简单。(The invention provides a composite photocatalyst and a preparation method and application thereof, the preparation of the nano-substrate/manganese oxide composite photocatalyst is realized by utilizing photoelectrocatalysis, the preparation method has simple and easy operation process, no reagent is required to be added, and no environmental pollution is caused. When the photocatalyst or the composite photocatalyst prepared by the invention is applied to sewage treatment, the degradable organic matters are various, the application range is wide, and compared with the biological treatment of the organic matters in the sewage, the treatment method of the invention has the advantages of short required period and simple operation.)

1. A method for preparing a photocatalyst is characterized in that: the method comprises the following steps: under the irradiation of light, the photocatalyst is prepared by using a nano material substrate as an anode and electrolyzing a solution containing divalent manganese.

2. The method for producing a photocatalyst according to claim 1, characterized in that: the nano material comprises at least one of titanium dioxide, carbon-based nano material, nitrogen-based nano material, cobalt metal oxide, nickel metal oxide, tungsten metal oxide, bismuth-based photocatalyst, molybdenum-based photocatalyst, manganese-based oxide, zinc oxide and cadmium sulfide.

3. The method for producing a photocatalyst according to claim 1, characterized in that: the divalent manganese-containing solution comprises at least one of manganese sulfate, manganese nitrate, manganese carbonate, manganese chloride, manganese oxalate, manganese acetate and manganese phosphate.

4. The method for producing a photocatalyst according to claim 1, characterized in that: the light irradiation adopts visible light or weak ultraviolet light; preferably weak ultraviolet light.

5. The method for producing a photocatalyst according to claim 1, characterized in that: the preparation method of the photocatalyst further comprises the following steps: electrolyzing under the condition of electrifying direct current; preferably, the direct current is 0.2mA/cm²～2.0mA/cm²。

6. The method for producing a photocatalyst according to claim 1, characterized in that: the electrolysis time is 5 min-200 min.

7. The photocatalyst prepared by the preparation method according to any one of claims 1 to 6, preferably, the photocatalyst comprises at least one of manganous oxide, manganese dioxide and manganese oxyhydroxide.

8. A preparation method of a composite photocatalyst comprises the following steps: and under the irradiation of light or no light, performing electro-corrosion by using the photocatalyst prepared by the preparation method of any one of claims 1 to 6 as a cathode to prepare the composite photocatalyst.

9. A composite photocatalyst prepared by the preparation method of claim 8; preferably, the composite photocatalyst comprises at least one of manganous oxide, manganous oxide and manganese oxyhydroxide.

10. Use of the photocatalyst of claim 7 and/or the composite photocatalyst of claim 9 for removing organic substances from wastewater.

Technical Field

The invention belongs to the technical field of sewage treatment, and particularly relates to a composite photocatalyst as well as a preparation method and application thereof.

Background

Photocatalysis is an advanced oxidation technology for effectively treating pollutants, and the photocatalyst is the key point for efficiently and smoothly carrying out photocatalytic reaction. Photocatalysts such as TiO2, carbon nanotubes, C₃N₄、ZnO、Fe₂O₃、ZrO₂、V₂O₅、WO₃And Bi₂O₃Separation of photo-generated holes and electron pairs under the excitation of light, and photo-generated holesHas extremely high oxidation potential (2.7eV), is a substance with extremely strong oxidizing property, and simultaneously generates a large number of electrons with certain reducing capability.

However, the single-phase photocatalyst also has some problems during the use process, including that the photogenerated hole electron pair needs higher energy to be excited, such as ultraviolet light, and the recombination rate of the generated hole and electron is high, which does not produce the ideal catalytic oxidation effect. To solve these problems, many researchers have started to prepare two-phase or even three-phase photocatalysts, which on the one hand want to excite materials with visible light and on the other hand can also inhibit the recombination of holes and electrons to a limited extent. An important and effective method is element doping, which is to incorporate a dopant into the crystal lattice of the original catalytic material, to change the elemental composition and atomic arrangement of the material, thereby changing the electronic structure of the material, and the common element doping can be divided into two types, one is the doping of metals or transition metal elements, for example, it has been proved by research that Fe³⁺、Mo⁵⁺、Ru³⁺、Os³⁺、Re⁵⁺、V⁴⁺And Rh³⁺The doping will significantly increase the TiO content₂Photocatalytic redox activity; secondly, doping of non-metal elements such as N, S, C, B, P, I, F. However, the preparation of these materials is complicated and requires the use of many chemicals and procedures.

Mn is a transition metal which widely exists in nature, is environment-friendly and is easy to obtain, and manganese oxide has good catalytic oxidation performance and is widely used for treating underground water pollution. In addition, the manganese oxide has a plurality of forms, including manganous oxide, manganic oxide, manganese dioxide and the like, and many researchers are dedicated to the application of the manganese oxide in the photocatalyst for degrading organic matters, ammonia nitrogen and the like, and have attracted great attention of the scientific community. For example, C prepared by hydrothermal method is available to scholars₄N₄-MnO₂The photocatalyst is used for degrading rhodamine B, and the degradation efficiency is obviously enhanced. However, the process of synthesizing the photocatalyst by the hydrothermal method is complicated, many reagents are required to be added, and harsh operating conditions are required to be operated, which also causes environmental pollution in the catalyst preparation stage.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a preparation method of the photocatalyst, which utilizes photoelectrocatalysis to realize the preparation of the nano-substrate/manganese oxide composite photocatalyst, and the preparation method has simple and easy operation process, does not need to add any reagent, and does not cause environmental pollution.

The second aspect of the present invention provides a photocatalyst produced by the above-mentioned method for producing a photocatalyst.

The third aspect of the invention provides a preparation method of the composite photocatalyst.

The fourth aspect of the invention provides a composite photocatalyst prepared by the preparation method of the composite photocatalyst.

A fifth aspect of the invention provides a use of the above photocatalyst and/or the above composite photocatalyst.

According to a first aspect of the present invention, a method for preparing a photocatalyst is provided, comprising the steps of: under the irradiation of light, the photocatalyst is prepared by using a nano material substrate as an anode and electrolyzing a solution containing divalent manganese.

In some embodiments of the invention, the nanomaterial comprises at least one of titanium dioxide, a carbon-based nanomaterial, a nitrogen-based nanomaterial, a cobalt metal oxide, a nickel metal oxide, a tungsten metal oxide, a bismuth-based photocatalyst, a molybdenum-based photocatalyst, a manganese-based oxide, zinc oxide, cadmium sulfide; preferably titanium dioxide.

In some preferred embodiments of the present invention, the divalent manganese-containing solution comprises at least one of manganese sulfate, manganese nitrate, manganese carbonate, manganese chloride, manganese oxalate, manganese acetate, manganese phosphate; manganese sulfate is preferred.

In some more preferred embodiments of the present invention, the concentration of manganese ions in the divalent manganese-containing solution applies to all concentrations of divalent manganese-containing solutions; preferably, the concentration of the manganese ions in the divalent manganese-containing solution is 0.1 mg/L-500 mg/L. In the invention, the concentration of manganese ions in different divalent manganese-containing solutions is controlled, and the surface morphology, valence state and proportion of manganese oxides with different valence states of the prepared photocatalyst are different.

In some more preferred embodiments of the present invention, the light irradiation employs visible light or weak ultraviolet light; preferably weak ultraviolet light; more preferably, the wavelength of the weak ultraviolet light is 320nm to 400 nm.

In some more preferred embodiments of the present invention, the method for preparing the photocatalyst further comprises performing electrolysis under direct current.

In some more preferred embodiments of the invention, the direct current is 0.2mA/cm²～2.0mA/cm². In the invention, different electrolytic currents are controlled, and the surface morphology, valence state and proportion of manganese oxides with different valence states of the prepared photocatalyst are different.

In some more preferred embodiments of the present invention, the time of the electrolysis is 5min to 200 min; preferably 10min to 120 min. In the invention, different electrolysis time is controlled, and the surface shape, valence state and proportion of manganese oxides with different valence states of the prepared photocatalyst are different.

According to a second aspect of the present invention, there is provided a photocatalyst produced by the above-mentioned method for producing a photocatalyst.

In some embodiments of the invention, the photocatalyst comprises at least one of manganous oxide, manganese dioxide, manganese oxyhydroxide.

According to a third aspect of the present invention, there is provided a preparation method of a composite photocatalyst, comprising the following steps: under the irradiation of light or no light, the photocatalyst is used as a cathode for electro-corrosion, and the composite photocatalyst is prepared.

In some embodiments of the invention, the light irradiation employs visible light or weak ultraviolet light; preferably weak ultraviolet light; more preferably, the wavelength of the weak ultraviolet light is 320nm to 400 nm.

In some more preferred embodiments of the present invention, the preparation method of the composite photocatalyst further comprises performing galvanic corrosion under the condition of passing direct current.

In some more preferred embodiments of the invention, the direct current is 0.2mA/cm²～2.0mA/cm²。

In some preferred embodiments of the present invention, the electrolyte used for the electro-etching is sodium sulfate.

In some preferred embodiments of the present invention, the time for the electroetching is 5min to 200 min; preferably 10min to 120 min; more preferably 20 to 60 min.

According to a fourth aspect of the present invention, a composite photocatalyst is provided, and the composite photocatalyst is prepared by the preparation method of the composite photocatalyst.

In some embodiments of the present invention, the composite photocatalyst comprises at least one of manganous oxide, and manganous oxyhydroxide.

According to a fifth aspect of the present invention, there is provided a use of the above photocatalyst and/or the above composite photocatalyst for removing organic substances in wastewater.

In some embodiments of the invention, the organic matter comprises at least one of decabromodiphenyl ether, hexabromobenzene, polychlorinated biphenyl, decabromodiphenyl ethane, polychlorinated diphenyl sulfide, polyfluorinated dibenzo-p-dioxin, pentafluorophenol, pentachlorophenol, pentabromophenol, benzylchlorophenol, triclosan, or tetrabromobisphenol a; preferably, the organic substance is triclosan.

The invention has the beneficial effects that:

1. in the invention, the surface morphology, valence state and proportion of manganese oxides with different valence states of the generated photocatalyst or composite photocatalyst can be controlled by photoelectrolysis time, current and manganese ion concentration.

2. The photocatalyst or composite photocatalyst prepared by the invention is easy to separate from water, can be recycled for 10-12 times, and has low use cost.

3. The preparation method is simple, the prepared photocatalyst or composite photocatalyst component widely exists in the environment, the leaching rate of metal ions is extremely low, and secondary pollution is avoided.

4. When the photocatalyst or the composite photocatalyst prepared by the invention is applied to sewage treatment, the degradable organic matters are various, the application range is wide, and compared with the biological treatment of the organic matters in the sewage, the treatment method of the invention has the advantages of short required period and simple operation.

5. The invention belongs to the photocatalysis range, has small energy requirement when degrading organic pollutants and conforms to the sustainable development trend of energy sources.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is an SEM image of a nano titanium dioxide array prepared by a hydrothermal method.

FIG. 2 is an SEM photograph of the photocatalyst prepared in example 1 of the present invention.

FIG. 3 is an SEM photograph of the photocatalyst prepared in example 2 of the present invention.

FIG. 4 is an SEM image of a composite photocatalyst prepared in example 3 of the present invention.

FIG. 5 is a diagram showing the ratio of manganese ions in different valence states in the photocatalysts prepared in example 4 with different photoelectrolysis times and the composite photocatalysts prepared with different photoelectrolysis times.

FIG. 6 is a graph showing the degradation rate of triclosan for example 5 and comparative examples.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

In the following examples, the titanium dioxide prepared by a hydrothermal method is used as the photo-anode for the nanomaterial substrate, and the specific preparation process is as follows: mixing titanium butoxide (or butyl titanate, tetrabutyl titanate) with cleaned conductive glass, placing in a high-pressure reaction kettle, reacting at 150 deg.C for 5h, and cooling toAt room temperature, the surface of the conductive glass is observed to turn white, namely the nano TiO₂And (4) array. And finally, washing the nano titanium dioxide array with distilled water, naturally drying, and placing the nano titanium dioxide array in an alumina crucible to react for 3 hours at the temperature of 550 ℃ to obtain the nano titanium dioxide array.

The SEM image of the prepared nano titanium dioxide array is shown in figure 1. As can be seen from FIG. 1, the nano-titania array prepared by the hydrothermal method grows uniformly in a rod shape, and the brightness of the surface shows that the surface is smooth.

Example 1

The embodiment prepares a photocatalyst, and the specific process is as follows:

the photocatalyst of trivalent manganese oxide, quadrivalent manganese oxide and titanium dioxide in a certain proportion can be obtained by taking a nano titanium dioxide array as a photo-anode, preparing a mixed solution of 20mg/L manganese sulfate and 100mmol/L sodium sulfate as an electrolyte, and electrolyzing for 20min under the conditions of 50W and 385nm ultraviolet irradiation and 1.6mA micro current.

The SEM image of the prepared photocatalyst is shown in FIG. 2. As can be seen in fig. 2, there is a deposition of particulate oxides of manganese on top of the titanium dioxide and a significant entanglement growth of the flocs around the titanium dioxide.

Example 2

The embodiment prepares a photocatalyst, and the specific process is as follows:

the photocatalyst of tetravalent manganese oxide and titanium dioxide can be obtained by using a nano titanium dioxide array as a photoanode, preparing a mixed solution of 20mg/L manganese sulfate and 100mmol/L sodium sulfate as an electrolyte, and electrolyzing for 80min under the conditions of 50W and 385nm ultraviolet irradiation and 1.6mA micro current.

The SEM image of the prepared photocatalyst is shown in FIG. 3. As can be seen from fig. 3, clusters with large particle sizes are formed due to the continuous deposition and growth of manganese oxide, completely covering the titanium dioxide.

Example 3

The embodiment prepares the composite photocatalyst, and the specific process is as follows:

the photocatalyst of tetravalent manganese oxide and titanium dioxide prepared in example 2 is used as a cathode, a 100mmol/L sodium sulfate solution is prepared as an electrolyte, and the composite photocatalyst of manganese oxyhydroxide and titanium dioxide can be obtained by electrolysis for 40min under the conditions of visible light irradiation and 0.3mA micro current.

The SEM image of the prepared composite photocatalyst is shown in figure 4. As can be seen from FIG. 4, the manganese oxide in the composite photocatalyst has a blocky structure with distinct edges and corners, and forms a completely different structure from the photoelectrolysis process.

Example 4

The embodiment prepares a photocatalyst, and the specific process is as follows:

a photocatalyst was prepared by photo-electrolysis according to the method of example 1, which is different from example 1 in that the photo-electrolysis time was 0min, 10min, 40min, 80min, respectively, and the valence state of manganese ions in the prepared photocatalyst was detected;

the composite photocatalyst is prepared by photo-electro corrosion according to the method of example 3, which is different from example 3 in that the photo-electro corrosion time is 0min, 10min, 40min and 80min, respectively, and the valence state of manganese ions in the prepared composite photocatalyst is detected, and the result is shown in fig. 5.

As can be seen from FIG. 5, the photoelectrolysis time and the photoelectrolysis time are different, and the ratio of trivalent manganese to quadrivalent manganese in the prepared catalyst is different.

Example 5

In this embodiment, the photocatalyst prepared in example 1 is used to degrade triclosan, and the specific process is as follows:

the photocatalyst prepared in example 1 was mixed with triclosan at concentrations of 0.5mg/mL, 1mg/mL, 2mg/mL, and 5mg/mL, respectively, the apparent concentrations of the photocatalysts were all 40mg/L, and the photocatalysts were degraded under visible light irradiation for 100min, respectively.

Comparative example

The comparative example adopts a nano titanium dioxide array prepared by a hydrothermal method to degrade triclosan, and the specific process comprises the following steps:

mixing the nano titanium dioxide array prepared by a hydrothermal method with triclosan with the concentration of 0.5mg/mL, 1mg/mL, 2mg/mL and 5mg/mL respectively, wherein the apparent concentration of the nano titanium dioxide array is 40mg/L, and degrading for 100min respectively.

The degradation rate of example 5 and the comparative example on triclosan is shown in fig. 6, and it can be seen from fig. 6 that the degradation rate of the photocatalyst prepared by the method of the present invention on triclosan can reach 80%, which is much higher than the degradation rate of the nano titanium dioxide array on triclosan.

Test examples

This test example 10 times of repeated experiments were conducted on the degradation experiment of triclosan of example 5 at a concentration of 2mg/mL, and the degraded solution was sampled and the concentration of manganese ions was measured by potassium periodate ultraviolet spectrophotometry, which was zero; and sampling the solution after 10 times of repeated experiments, and measuring the residual concentration of the triclosan by using high performance liquid chromatography, wherein the result shows that the degradation rate of the photocatalyst to the triclosan can still be kept above 80% of the initial degradation rate.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.