CN107570194B - A kind of Fe/Co-Nx/TiO2 photocatalyst and its preparation method and application - Google Patents

Abstract

The invention discloses a Fe/Co-Nx/TiO ₂ photocatalyst, which contains Fe/Co-Nx chelate on a crystal face of TiO ₂ {001 }.

Description

A kind of Fe/Co-Nx/TiO2 photocatalyst and its preparation method and application

technical field

The invention relates to a Fe/Co-Nx/ _TiO2 photocatalyst, and also relates to a preparation method and application of the Fe/Co-Nx/ _TiO2 photocatalyst, belonging to the technical field of photocatalysts.

Background technique

In recent decades, sulfonamides have gradually become one of the most widely used antibacterial agents in human and animal medicine. Researchers have detected the presence of such substances in surface water, groundwater and rivers. However, because such pollutants are not only persistent but also easily destroy the DNA and nucleus of bacteria, the biodegradation method is greatly limited. In recent years, Fenton's reagent is considered to be an effective catalyst for degrading sulfonamides, but due to its requirement for the amount of H ₂ O ₂ , its cost increases and it cannot be put into practical application. Although TiO ₂ can degrade antibiotics well under ultraviolet light conditions, TiO ₂ cannot respond to visible light, which greatly limits its application.

DFT theoretical calculations show that the {001} crystal plane is the most active crystal plane of _TiO2 . Since Yang et al. prepared anatase TiO ₂ with 47% {001} crystal planes, the research on TiO ₂ (001) has been increasing, but most of the researches are only on the regulation of the proportion of {001} crystal planes, namely Increase the proportion of its {001} crystal facet, but few people have studied its photocatalytic performance after modification.

Contents of the invention

Purpose of the invention: the technical problem to be solved by this invention is to provide a kind of Fe/Co-Nx/ _TiO2 photocatalyst, this photocatalyst has excellent catalytic degradation performance to the antibiotic sulfathiazole in the water body under visible light and ultraviolet light .

The technical problem to be solved in the present invention is to provide the preparation method of the above-mentioned Fe/Co-Nx/ _TiO2 photocatalyst.

The final technical problem to be solved by the present invention is to provide the application of the above-mentioned Fe/Co-Nx/ _TiO2 photocatalyst in catalytic degradation of sulfathiazole in water under visible light.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

An Fe/Co-Nx/TiO ₂ photocatalyst, the photocatalyst contains Fe/Co-Nx chelate on the TiO ₂ {001} crystal plane.

The preparation method of the above-mentioned Fe/Co-Nx/TiO ₂ photocatalyst, the desired mass ratio of Fe/CoPcS and TiO ₂ nanosheets are placed in a high temperature pyrolysis reaction, and the TiO ₂ {001} crystal surface containing Fe/Co -Nx chelates of Fe/Co-Nx/TiO ₂ nanomaterials. Fe/Co-Nx/TiO ₂ has a flake nanostructure.

Wherein, the ratio of the {001} crystal plane contained in the TiO ₂ is 70%-80%.

Wherein, the temperature of the pyrolysis reaction is 600-800°C.

Above-mentioned Fe/Co-Nx/ _TiO The preparation method of photocatalyst, specifically comprises the steps:

Step 1, preparing Fe/CoPcS: adding the required amount of sulfonated cobalt phthalocyanine and ferrous sulfate heptahydrate into methanol, ultrasonicating for a period of time, and calcining the mixed material in _N2 atmosphere for a period of time to obtain Fe/CoPcS;

Step 2, preparing _TiO2 nanosheets with a high proportion of {001} crystal facets: mixing the required amount of butyl titanate, hydrofluoric acid and water in a certain proportion and then reacting at a certain temperature, and centrifuging the reacted product processing, centrifuging, cleaning, drying and grinding to obtain _TiO2 nanosheets with a high {001} crystal plane ratio;

Step 3, the Fe/CoPcS that step 1 makes and the TiO that step ₂ makes Nanosheets are added in the methanol according to the required mass ratio, after ultrasonication, the mixed material is placed at high temperature for pyrolysis reaction, and the pyrolysis reaction The final product is ground to obtain Fe/Co-Nx/TiO ₂ nanomaterials.

Wherein, in step 1, the mass ratio of the sulfonated cobalt phthalocyanine and ferrous sulfate is 3:2.

Wherein, in step 2, the mixing volume ratio of butyl titanate, hydrofluoric acid and water is 5:1:1, the reaction temperature is 170-180° C., and the reaction time is 20-24 hours.

Wherein, in step 3, the mass ratio of Fe/CoPcS to TiO ₂ nanosheets is 1:4.

Wherein, in step 3, the pyrolysis reaction temperature is 600-800° C., and the pyrolysis reaction time is 2-3 hours.

The application of the above-mentioned Fe/Co-Nx/ _TiO2 photocatalyst in the catalytic degradation of sulfathiazole in water under visible light.

The preparation principle of the modified TiO ₂ of the present invention: Fe/CoPcS forms Fe/Co-Nx active centers (Fe/Co-Nx active centers) under pyrolysis conditions (above 600°C) and forms a heterojunction with TiO ₂ To reduce the band gap of TiO ₂ and broaden its response to visible light; because Fe/Co-Nx can elongate the bond length of O ₂ and reduce its bond energy, oxygen molecules are more easily attacked by electrons to generate superoxide free At the same time, due to the formation of heterojunction, the separation of electron-hole pairs is promoted, and water molecules are oxidized to hydroxyl radicals by holes on the {001} crystal plane. Sulfathiazole is finally oxidized to metabolites under the action of hydroxyl radicals and superoxide radicals.

Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

The modified Fe/Co-Nx/ _TiO photocatalyst of the present invention all has high degradability to the sulfathiazole in the water body under visible light and ultraviolet light, and the product after degradation has lower toxicity simultaneously; The preparation method has easy-to-obtain raw materials, low cost and is suitable for industrial production.

Description of drawings

Fig. 1 is Fe/Co-Nx/ _TiO of the present invention The process flow diagram of photocatalyst preparation method;

Fig. 2 is the comparative figure of each material to the degradation experiment result of sulfathiazole under visible light;

Fig. 3 is Fe/Co-Nx/ _TiO of the present invention The structural principle diagram of photocatalyst;

Fig. 4 is the structural characterization diagram (SEM) of _TiO with high {001} crystal plane ratio of the present invention;

Fig. 5 is a structure characterization diagram (SEM) of the Fe/Co-Nx/TiO ₂ photocatalyst of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, but the scope of protection claimed by the present invention is not limited thereto.

The preparation method of the Fe/Co-Nx/TiO2 photocatalyst of the present invention: dissolve FeSO ₄ 7H ₂ O and sulfonated cobalt phthalocyanine (CoPcS) in methanol for a certain period of time, and then place it under a tube furnace for calcination to form Fe /CoPcS; TiO ₂ with a high proportion of {001} crystal planes was synthesized by hydrothermal method; Fe/Co-Nx/TiO ₂ (001) was synthesized by loading Fe/CoPcS on TiO ₂ {001} crystal planes ) nano photocatalyst.

Example 1

Fe/Co-Nx/ _TiO of the present invention The preparation method of photocatalyst specifically comprises the following steps:

Step 1, preparation of Fe/Co-Nx nanoparticles: Weigh 0.4g ferrous sulfate heptahydrate and 0.6g sulfonated cobalt phthalocyanine and place it in 4ml methanol for ultrasonication for 10min, place the resulting mixture in a tube furnace, and place the mixture under N ₂ Calcination under the protection of atmosphere for 2 hours, the calcination temperature is 300 ° C, and Fe/CoPcS is obtained after grinding;

Step 2: Take 25mL of butyl titanate, 5mL of hydrofluoric acid and 5mL of deionized water respectively, place them in a polytetrafluoroethylene container, mix and stir evenly, and then react in the reactor at 180°C for 24h; centrifuge the obtained product Finally, wash with deionized water and absolute ethanol 3 times, dry, and grind to obtain TiO ₂ (001) nanosheets;

Step 3, weigh 50 mg Fe/CoPcS and 200 mg TiO ₂ (001) nanosheets and place them in 10 mL of methanol. After ultrasonication for 15 min, the mixture is placed in a tube furnace and pyrolyzed at 600 ° C for 2 h, then ground to obtain Fe/Co- Nx/TiO ₂ (001).

Example 2

Fe/Co-Nx/ _TiO of the present invention The preparation method of photocatalyst specifically comprises the following steps:

Step 1, preparation of Fe/Co-Nx nanoparticles: Weigh 0.4g ferrous sulfate heptahydrate and 0.6g sulfonated cobalt phthalocyanine and place it in 4ml methanol for ultrasonication for 10min, place the resulting mixture in a tube furnace, and place the mixture under N ₂ Calcination under the protection of atmosphere for 2 hours, the calcination temperature is 300 ° C, and Fe/CoPcS is obtained after grinding;

Step 2: Take 25mL of butyl titanate, 5mL of hydrofluoric acid and 5mL of deionized water respectively, place them in a polytetrafluoroethylene container, mix and stir evenly, and then react in the reactor at 170°C for 20h; centrifuge the obtained product Finally, wash with deionized water and absolute ethanol 3 times, dry, and grind to obtain TiO ₂ (001) nanosheets;

Step 3, weigh 50mg of Fe/CoPcS and 200mg of TiO ₂ (001) nanosheets and place them in 10mL of methanol. After ultrasonication for 15min, the mixture is placed in a tube furnace and pyrolyzed at 800°C for 3h, then ground to obtain Fe/Co- Nx/TiO ₂ (001).

Comparative Example 1

A preparation method of TiO ₂ (001) nanosheets, the specific operation method is: measure 25mL butyl titanate, 5mL hydrofluoric acid and 5mL deionized water respectively, place them in a polytetrafluoroethylene container, mix and stir evenly, and then React in a reaction kettle at 180° C. for 24 hours; centrifuge the obtained product, wash it with deionized water and absolute ethanol three times, dry it, and grind it to obtain TiO ₂ (001) nanosheets.

Under visible light, measure the voluntary degradation ability of sulfathiazole under the condition of no catalyst respectively _; The obtained TiO ₂ (001) photocatalyst is to the degradability of sulfathiazole in the solution _; : The measurement results are shown in Figure 2.

Take 100mL of sulfathiazole solution with an initial concentration of 10mg/L, and place it under a 300w xenon lamp for 18h irradiation (into air). Samples were taken every 3 hours, filtered through a 0.45-micron filter head, diluted 20 times, and the concentration of sulfathiazole was measured by LC-MS/MS.

Get 100mL initial concentration and be the sulfathiazole solution of 10mg/L, add the _TiO2 (001) photocatalyst that 50mg comparative example 1 makes in the solution, after stirring for 30min to reach adsorption-desorption equilibrium, place the xenon lamp of 300w to irradiate for 18h ( into the air). Samples were taken every 3 hours, filtered through a 0.45-micron filter head, diluted 20 times, and the concentration of sulfathiazole was measured by LC-MS/MS.

Get 100mL of sulfathiazole solution whose initial concentration is 10mg/L, add 50mg of Fe/Co-Nx/ _TiO2 (001) photocatalyst that embodiment 1 makes in the solution, after stirring for 30min to reach adsorption-desorption equilibrium, place in 300w Irradiated under xenon lamp for 18h (into air). Samples were taken every 3 hours, filtered through a 0.45-micron filter head, diluted 20 times, and the concentration of sulfathiazole was measured by LC-MS/MS.

Take 100mL of sulfathiazole solution with an initial concentration of 10mg/L, add 0.1g of Fe/Co-Nx/ _TiO2 (001) photocatalyst prepared in Example 1 to the solution, stir for 30min to reach adsorption-desorption equilibrium, and place in 300w Irradiated under a xenon lamp for 18h (passing N ₂ ). Samples were taken every 3 hours, filtered through a 0.45 micron filter head, diluted 20 times, and the concentration of sulfathiazole was measured by LC-MS/MS. as shown in picture 2.

It can be seen from Figure 2 that sulfathiazole is almost not degraded under the condition of no catalyst. When TiO ₂ (001) nanosheets are added, the degradation rate is only 10%, while using the modified photocatalyst Fe/Co-Nx/TiO ₂ (001) can make the removal rate as high as 84.5%, which shows that the Fe/Co-Nx/TiO ₂ (001) nanosheet photocatalyst of the present invention has a very strong degradation ability for the antibiotic drug sulfathiazole in water. When continuously feeding N ₂ , although the degradation rate of Fe/Co-Nx/TiO ₂ (001) photocatalyst to sulfathiazole is much lower than that of feeding air, it is also higher than that of TiO ₂ (001) photocatalyst High, indicating that the Fe/Co-Nx/TiO ₂ (001) photocatalyst can activate oxygen molecules in water to a certain extent.

See Table 1 for the degradation test results of sulfathiazole for each substance under visible light.

Table 1

.

The Fe/Co-Nx/TiO ₂ photocatalyst of the present invention firstly synthesizes Fe/CoPcS, and then composites it on the surface of TiO ₂ with a high proportion of {001} crystal planes by pyrolysis, and under high temperature conditions, the {001} crystal The active center Fe/Co-Nx is formed on the surface to obtain Fe/Co-Nx/TiO ₂ (001) photocatalyst. The modified photocatalyst Fe/Co-Nx/TiO ₂ (001) greatly promotes the activation of oxygen molecules in solution and the separation of electron-hole pairs, and enhances the electron transfer rate on the catalyst surface under photocatalytic reaction conditions. A large number of hydroxyl radicals and superoxide radicals are thus formed, thereby improving the degradation of sulfathiazole by the photocatalyst under visible light.

Apparently, the above-mentioned embodiments are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And these obvious changes or modifications derived from the spirit of the present invention are still within the protection scope of the present invention.

Claims (8)

1. A Fe/Co-Nx/ _TiO photocatalyst, characterized in that: the photocatalyst contains Fe/Co-Nx chelate on the _TiO {001} crystal plane; The photocatalyst is prepared by the following method: put Fe/CoPcS and TiO ₂ nanosheets with the required mass ratio under high temperature for pyrolysis reaction, and obtain TiO ₂ {001} crystal surface containing Fe/Co-Nx chelated Fe/Co-Nx/TiO ₂ nanomaterials; wherein, the temperature of the pyrolysis reaction is 600-800°C. 2. The Fe/Co-Nx/TiO ₂ photocatalyst according to claim 1, characterized in that: the proportion of {001} crystal planes in the TiO ₂ is 70%-80%. 3. Fe/Co-Nx/TiO according to claim 1 ₂ photocatalysts, it is characterized in that, specifically adopt the following method to prepare: Step 1, preparing Fe/CoPcS: adding the required amount of sulfonated cobalt phthalocyanine and ferrous sulfate heptahydrate into methanol, ultrasonicating for a period of time, and calcining the mixed material in _N2 atmosphere for a period of time to obtain Fe/CoPcS; Step 2, preparing _TiO2 nanosheets with a high proportion of {001} crystal facets: mixing the required amount of butyl titanate, hydrofluoric acid and water in a certain proportion and then reacting at a certain temperature, and centrifuging the reacted product processing, centrifuging, cleaning, drying and grinding to obtain _TiO2 nanosheets with a high {001} crystal plane ratio; Step 3, the Fe/CoPcS that step 1 makes and the TiO that step ₂ makes Nanosheets are added in the methanol according to the required mass ratio, and after ultrasonication, the mixed material is placed at a high temperature for pyrolysis reaction, and the pyrolysis reaction The final product is ground to obtain Fe/Co-Nx/TiO ₂ nanometer material; the pyrolysis reaction temperature is 600-800°C. 4. Fe/Co-Nx/ _TiO2 photocatalyst according to claim 3 is characterized in that: in step 1, the adding mass ratio of described sulfonated cobalt phthalocyanine and ferrous sulfate heptahydrate is 3: 2 . 5. Fe/Co-Nx/ _TiO2 photocatalyst according to claim 3 is characterized in that: in step 2, the mixing volume ratio of described butyl titanate, hydrofluoric acid and water is 5: 1: 1 , the reaction temperature is 170-180°C, and the reaction time is 20-24h. 6. The Fe/Co-Nx/TiO ₂ photocatalyst according to claim 3, characterized in that: in step 3, the mass ratio of Fe/CoPcS to TiO ₂ is 1:4. 7. The Fe/Co-Nx/TiO ₂ photocatalyst according to claim 3, characterized in that in step 3, the pyrolysis reaction time is 2-3 hours. 8. The application of the Fe/Co-Nx/ _TiO2 photocatalyst in claim 1 in catalytic degradation of sulfathiazole in water under visible light.