Zn for removing tetracycline in wastewater3In2S6/g-C3N4Composite photocatalyst and preparation method thereof
阅读说明：本技术 用于去除废水中四环素的Zn3In2S6/g-C3N4复合光催化剂及其制备方法 (Zn for removing tetracycline in wastewater3In2S6/g-C3N4Composite photocatalyst and preparation method thereof ) 是由 李育珍 霍浩浩 刘康慨 李厚芬 谭思洋 王少杰 李鑫 易思远 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种用于去除废水中四环素的Zn-(3)In-(2)S-(6)/g-C-(3)N-(4)复合光催化剂的制备方法及应用。首先锌源、氯化铟(InCl-(3)·4H-(2)O)和柠檬酸钠(C-(6)H-(5)Na-(3)O-(7)·2H-(2)O)按3:2:3的化学计量比加入到水和乙二醇的溶液中,然后超声分散,获得分散均匀的溶液；然后将g-C-(3)N-(4)加入上述溶液中,在室温下搅拌；此外,按照化学计量比在上述溶液中加入硫源,并继续在室温下搅拌；最后将得到分散液倒入高压釜中反应；将得到的产物分别用蒸馏水和无水乙醇洗涤,将所得沉淀物分散在含无水乙醇的培养皿中并烘干,得到Zn-(3)In-(2)S-(6)/g-C-(3)N-(4)粉末。本发明原料廉价易得、操作简便；在环境治理方面表现出广泛的应用前景。(The invention discloses Zn for removing tetracycline in wastewater 3 In 2 S 6 /g‑C 3 N 4 A preparation method and application of the composite photocatalyst. Firstly, a zinc source and indium chloride (InCl) 3 •4H 2 O) and sodium citrate (C) 6 H 5 Na 3 O 7 •2H 2 O) adding the mixture into a solution of water and glycol according to the stoichiometric ratio of 3:2:3, and then carrying out ultrasonic dispersion to obtain a uniformly dispersed solution; then g-C is added 3 N 4 Adding into the above solution, stirring at room temperature; in addition, adding a sulfur source into the solution according to the stoichiometric ratio, and continuously stirring at room temperature; finally, pouring the obtained dispersion into a high-pressure kettle for reaction; washing the obtained product with distilled water and anhydrous ethanol respectively, dispersing the obtained precipitate in a culture dish containing anhydrous ethanol, and drying to obtain Zn 3 In 2 S 6 /g‑C 3 N 4 And (3) powder. The raw materials are cheap and easy to obtain, and the operation is simple and convenient; has wide application prospect in the aspect of environmental management.)
1. Zn for removing tetracycline in wastewater3In2S6/g-C3N4The composite photocatalyst is characterized in that the composite material is Zn3In2S6/g-C3N4(ii) a Wherein Zn is3In2S6And g-C3N4The mass ratio of (A) to (B) is 20-100: 100.
2. zn for removing tetracycline in wastewater according to claim 13In2S6/g-C3N4Composite photocatalyst, characterized in that Zn3In2S6And g-C3N4The mass ratio of (A) to (B) is 80: 100.
3. zn for removing tetracycline in wastewater as claimed in claim 1 or 23In2S6/g-C3N4The preparation method of the composite photocatalyst is characterized by comprising the following steps:
(1) mixing a zinc source and indium chloride InCl3•4H2O and sodium citrate C6H5Na3O7•2H2Adding O into a mixed solvent of water and ethylene glycol according to a stoichiometric ratio of 3:2:3, and then carrying out ultrasonic dispersion for 30-60 min, obtaining a uniformly dispersed solution;
(2) the prepared g-C3N4Adding the mixture into the solution, and stirring at room temperature for 30-60 min;
(3) adding a sulfur source into the solution, and continuously stirring at room temperature for 30-60 min; obtaining a dispersion liquid;
(4) pouring the obtained dispersion into an autoclave, and keeping the temperature of the autoclave at 120-160 ℃ for 12 hours;
(5) washing the product obtained in the step (4) with distilled water and absolute ethyl alcohol for 3-6 times respectively, then dispersing the obtained precipitate in a culture dish containing absolute ethyl alcohol, and placing the culture dish in an oven for drying to obtain Zn3In2S6/g-C3N4And (3) powder.
4. Zn for removing tetracycline in wastewater according to claim 33In2S6/g-C3N4The preparation method of the composite photocatalyst is characterized by comprising the following steps: the volume ratio of the water to the ethylene glycol is 5: 1.
5. Zn for removing tetracycline in wastewater according to claim 33In2S6/g-C3N4The preparation method of the composite photocatalyst is characterized by comprising the following steps: and (2) in the step (1), the zinc source is one of zinc chloride or zinc nitrate.
6. Zn for removing tetracycline in wastewater according to claim 33In2S6/g-C3N4The preparation method of the composite photocatalyst is characterized by comprising the following steps: the sulfur source in the step (3) is one of thioacetamide or thiourea, and the dosage of the sulfur source is three times of the molar quantity of the indium chloride.
7. Zn according to claim 1 or 23In2S6/g-C3N4The application of the composite photocatalyst in removing tetracycline in wastewater.
8. Use according to claim 7, characterized in that: the dosage of the catalyst is 0.2-0.48 g/L of wastewater.
9. The use of claim 7, wherein the concentration of tetracycline in the wastewater is 5-30 mg/L.
10. Use according to claim 7, characterized in that:
adding Zn to a 20mg/L tetracycline solution3In2S6/g-C3N4The concentration of the photocatalyst is 0.2-0.48 g/L; performing ultrasonic dispersion for 15 min in dark, placing in a dark box, and magnetically stirring for 40 min to reach adsorption balance; a 300W xenon lamp with a 420 nm cut-off filter is used as a visible light source, the reaction time is 150 min, and 20 mL of solution is taken every 20 min; centrifuging at 10000 rpm for 5 min each time, and filtering the supernatant with 0.45 μm filter membrane; taking the filtrate to test the absorbance; the tetracycline removal rate can be obtained according to the removal rate formula (1):
（1）
wherein: c0Is the initial concentration of tetracycline, mg.L-1；
CtIs the concentration of tetracycline after time t, mg. L-1。
Technical Field
The invention relates to Zn for removing tetracycline in wastewater3In2S6/g-C3N4A composite photocatalyst and a preparation method thereof belong to the technical field of photocatalysts and preparation thereof.
Background
In recent years, with the vigorous development of Chinese science and technology and industry and the vigorous development of the pharmaceutical industry, more and more new drugs are developed and used for medical treatment. However, the vigorous development of the medical industry brings convenience to people, and the pollution condition of medical wastewater cannot be ignored.
Antibiotics are common contaminants in medical wastewater. If the using method is improper, serious damage can be caused to the society and the environment. Antibiotics entering the environment not only can destroy the activity of microorganisms and destroy the balance of an ecological system, but also can affect the survival and growth of animals and plants, and further affect a biological chain and human beings. Statistically, about 50% of the world's antibiotics do not exert their correct value every year, and more seriously, this is the case in china. The abuse of antibiotics brings stronger drug resistance to pathogenic bacteria, produces some super pathogenic bacteria and brings huge challenges to the continuance of social environment.
The photocatalytic technology is an efficient and environment-friendly pollutant decomposition measure which is started in recent years, and the main principle is that substances with strong oxidizability are generated under illumination, and the substances can react with pollutants in a water body to finally purify water quality. The photocatalysis technology is carried out at normal temperature and normal pressure, has the characteristic of no secondary pollution, and is a new technology in the field of wastewater treatment.
Wherein the graphite-like or graphite-phase carbon nitride material (g-C)3N4) The compound is the most stable carbon nitride compound at normal temperature and normal pressure, and is easy to synthesize, so that the compound is widely researched and applied. Graphite phase g-C3N4Is a mid-gap semiconductor (-2.7 eV) with good visible light response. The graphite phase carbon nitride has excellent thermal stability and chemical stability, and has the characteristics of no toxicity, low raw material price, easy preparation, good biocompatibility and the like. However, the g-C is limited by the higher rate of recombination of photo-generated electron-hole pairs, the narrower photoresponse range and the lower specific surface area3N4The photocatalytic performance of the catalyst is further influenced. Therefore, the development of a photocatalytic material with wide-spectrum response and high photocatalytic efficiency is a precondition and a key for promoting the wide application of a photocatalytic technology in the field of antibiotic wastewater.
Disclosure of Invention
The invention aims to provide Zn for removing tetracycline in wastewater3In2S6/g-C3N4The preparation method and the application of the composite photocatalyst have low cost and mild operation condition, and solve the problem of g-C3N4The photocatalyst has the problems of high recombination rate of photo-generated electron-hole pairs and low quantum efficiency. The invention adopts ternary metal sulfide Zn3In2S6For g-C3N4Is modified, Zn3In2S6The ternary metal sulfide has the advantages that the ternary metal sulfide has the band gap energy of 2.8 eV, has the characteristics of proper conduction band and valence band positions, sufficient oxidation-reduction potential and the like, and becomes a popular photocatalyst in recent years; the invention is prepared byZn3In2S6And g-C3N4And (3) constructing a semiconductor heterojunction, so as to promote the separation of photogenerated electrons and holes, thereby enhancing the photocatalytic performance of the semiconductor photocatalyst.
The invention provides Zn3In2S6/g-C3N4The preparation method of the composite photocatalyst comprises the following steps:
(1) zinc source ZnCl2Indium chloride InCl3•4H2O and sodium citrate C6H5Na3O7•2H2Adding O into a mixed solvent of water and ethylene glycol according to a stoichiometric ratio of 3:2:3, and then carrying out ultrasonic dispersion for 30-60 min to obtain a uniformly dispersed solution;
(2) g to C3N4Adding the mixture into the solution, and stirring at room temperature for 30-60 min;
(3) adding a sulfur source with the molar weight three times that of indium chloride into the solution, and continuously stirring at room temperature for 30-60 min;
(4) pouring the obtained dispersion into an autoclave, and keeping the temperature at 120 ℃ for 12 hours;
(5) washing the product obtained in the step (4) with distilled water and absolute ethyl alcohol for 3-6 times respectively, then dispersing the obtained precipitate in a culture dish containing absolute ethyl alcohol, and placing the culture dish in an oven for drying to obtain Zn3In2S6/g-C3N4Powder;
in the preparation method, the zinc source is one of zinc chloride or zinc nitrate.
In the preparation method, the sulfur source is one of thioacetamide and thiourea.
In the preparation method, the solvent is a mixed solvent of water and glycol, and the volume ratio of the water to the glycol is 5: 1.
In the above production method, the Zn3In2S6Is in the g-C range3N4The mass fraction of (A) is 20-100%.
In the preparation method, in the step (4), the reaction temperature is 120-160 ℃, and the reaction time is 12 hours.
The invention provides Zn prepared by the preparation method3In2S6/g-C3N4A composite photocatalyst is provided.
The present invention provides the above Zn3In2S6/g-C3N4The application of the composite photocatalyst in photocatalytic degradation of tetracycline in wastewater.
The application comprises the step of adding 0.2-0.48 g/L of Zn into 20mg/L of tetracycline solution3In2S6/g-C3N4The catalyst is ultrasonically dispersed for 15 min under dark conditions, and then is placed in a dark box and is magnetically stirred for 40 min to achieve adsorption balance; A300W xenon lamp with a 420 nm cut-off filter is used as a visible light source, the reaction time is 150 min, and 20 mL of solution is taken every 20 min. Two centrifugations were carried out at 10000 rpm for 5 min each, and then the supernatant was filtered with a 0.45 μm filter. The filtrate was taken to test absorbance. The tetracycline removal rate can be obtained according to the removal rate formula (1).
（1）
Wherein: c0Is the initial concentration of tetracycline, mg.L-1；
CtIs the concentration of tetracycline after time t, mg. L-1。
The invention has the beneficial effects that:
(1) the preparation method is simple and convenient, easy to operate, low in reaction temperature and low in price and availability of raw materials; zn can be prepared by a solvothermal method3In2S6/g-C3N4A photocatalytic material;
(2) by solvothermal method of Zn3In2S6Incorporation of g-C3N4On one hand, the problem of photo-corrosion of the catalyst in the process of photocatalysis is effectively solved, and the stability of the photocatalyst is improved; on the other hand, the formation of heterojunction is utilized to promote the separation of photo-generated electron-hole pairs, thereby improving the photocatalytic activityAnd (4) sex.
(3) Zn of the invention3In2S6/g-C3N4The preparation method has the advantages of low reaction temperature, simple process flow and convenient operation. Has wide application prospect in the field of environmental management.
Drawings
FIG. 1 is an XRD pattern (a: g-C) of a sample prepared in example 1 of the present invention3N4, b: Zn3In2S6And c 80% Zn3In2S6/g-C3N4）；
FIG. 2 is a graph of 80% Zn of samples prepared in example 1 of the present invention3In2S6/g-C3N4SEM picture of (1);
FIG. 3 is a DRS map of a sample prepared in example 1 of the present invention; wherein a is g-C3N4, b: Zn3In2S6，c: 80% Zn3In2S6/g-C3N4；
FIG. 4 is a band gap diagram of a sample prepared in example 1 of the present invention; wherein a is g-C3N4, b: Zn3In2S6，c: 80% Zn3In2S6/g-C3N4；
FIG. 5 is a graph showing the degradation of tetracycline (20mg/L) by visible light for the samples prepared in example 1 of the present invention; wherein a is g-C3N4，0.2 g/L；b: 80% Zn3In2S6/g-C3N4，0.2 g/L。
Detailed Description
The present invention is further illustrated by, but is not limited to, the following examples.
The required starting materials were prepared according to the methods of the prior literature:
(1) monomers g to C3N4The preparation process is as follows: preparation of monomers g-C by thermal polymerization3N4. Firstly, putting weighed precursor urea into an alumina crucible with a cover, heating to 550 ℃ at a heating rate of 5 ℃/min in an electric furnace, and keeping for 4 h.After the reaction was completed, it was cooled to room temperature to obtain a pale yellow powder, which was ground and collected for storage.
（2）g-C3N4Preparing a nano sheet: weighing a predetermined amount of the above g-C3N4The powder was added to a covered alumina crucible and heated to 520 ℃ in an electric furnace at a heating rate of 5 ℃/min for 2 h. After cooling to room temperature, the resulting pale yellow powder was collected and stored, and the sample was designated g-C3N4。
Example 1:
the preparation of the binary photocatalytic material comprises the following steps:
(1) adding 1.94 mmol of zinc chloride, 1.29 mmol of indium chloride and 1.94 mmol of sodium citrate into a solution of which the volume ratio of water to ethylene glycol is 5:1, wherein the total volume of the solution is 60 mL, and then carrying out ultrasonic dispersion for 30 min to obtain a uniformly dispersed solution;
(2) 0.50 g of g-C3N4Adding into the above solution, and stirring at room temperature for 30 min;
(3) adding 3.88 mmol thioacetamide into the solution, and continuing stirring at room temperature for 30 min;
(4) pouring the obtained dispersion into an autoclave, and keeping the temperature at 120 ℃ for 12 hours;
(5) washing the obtained product with distilled water and anhydrous ethanol for 6 times, respectively, dispersing the obtained precipitate in a culture dish containing anhydrous ethanol, placing the culture dish in an oven at 60 deg.C, and oven drying for 12 hr to obtain 80% Zn3In2S6/g-C3N4Powder;
application test:
two 250 mL 20mg/L tetracycline solutions were prepared and then 0.05g g-C was added separately3N4And 80% Zn3In2S6/g-C3N4And catalysts for carrying out photocatalytic reactions, respectively. Performing ultrasonic dispersion for 15 min in dark, placing in a dark box, and magnetically stirring for 40 min to reach adsorption balance; then, a 300W xenon lamp with a 420 nm cut-off filter is used as a visible light source, the reaction time is 150 min, and 20 mL of solution is taken every 20 min. In 1Two centrifugations were carried out at 0000 rpm for 5 min each, and then the supernatant was filtered through a 0.45 μm filter. The filtrate was taken to test absorbance. Then the time (t) is taken as the abscissa, C/C0The curve is plotted for the ordinate as shown in fig. 5.
FIG. 1 is an XRD pattern (a: g-C) of a sample prepared in example 1 of the present invention3N4, b: Zn3In2S6And c 80% Zn3In2S6/g-C3N4). As can be seen from the figure, the sample was clearly observed to have good crystal phase growth and a strong and sharp diffraction peak. Monomers g to C3N4The diffraction peaks at 13.04 ° and 27.40 ° correspond to the (001) and (002) crystal planes, respectively, corresponding to the standard card JCPDS number 87-1526. In binary complex 80% Zn3In2S6/g-C3N4In (b), may be g-C3N4A diffraction peak at 27.40 ℃ with Zn was found3In2S6The diffraction peaks at 27.15 ° overlap, thus leading to a broadening of the peaks there, and are furthermore visible as being assigned to Zn3In2S6The (110), (022) and (212) crystal planes of (A) illustrate Zn3In2S6And g-C3N4The composition is good.
FIG. 2 is a graph of 80% Zn of samples prepared in example 1 of the present invention3In2S6/g-C3N4SEM picture of (1), from which petal-shaped spherical Zn can be observed3In2S6Dispersed in stacked g-C3N4And (4) nano-chips.
FIG. 3 is a DRS map of a sample prepared in example 1 of the present invention (a: g-C)3N4, b: Zn3In2S6And c 80% Zn3In2S6/g-C3N4). It is found from the figure that the monomers g-C are compared3N4In terms of binary complex 80% Zn3In2S6/g-C3N4Has an enlarged visible light absorption edge (increasing from the previous 450 nm to 460 nm).
FIG. 4 shows an embodiment of the present inventionExample 1 hv plot of prepared samples (a: g-C)3N4, b: Zn3In2S6And c 80% Zn3In2S6/g-C3N4). The forbidden band width is correspondingly reduced (from the previous g-C)3N42.71 eV is reduced to 80% Zn3In2S6/g-C3N42.64 eV), thereby effectively reducing the forbidden bandwidth and accelerating the separation of the photo-generated electron-hole pairs.
FIG. 5 degradation of tetracycline (20mg/L) under visible light for samples prepared in example 1 of the present invention (a: g-C)3N40.2 g/L) and b 80% Zn3In2S6/g-C3N40.2 g/L); the comparative experiment shows that: after 150 min of visible light irradiation, the monomers g-C3N4The degradation rate of the tetracycline solution is 63.7 percent, and the binary compound is 80 percent of Zn3In2S6/g-C3N4The degradation rate of the tetracycline solution is 85.7%.
Example 2
The preparation of the binary photocatalytic material comprises the following steps:
(1) adding 0.97 mmol of zinc nitrate, 0.645 mmol of indium chloride and 0.97 mmol of sodium citrate into a solution of which the volume ratio of water to ethylene glycol is 5:1, wherein the total volume of the solution is 60 mL, and then carrying out ultrasonic dispersion for 40 min to obtain a uniformly dispersed solution;
(2) 0.50 g of g-C3N4Adding into the above solution, and stirring at room temperature for 40 min;
(3) adding 1.94 mmol of thiourea into the solution according to the stoichiometric ratio, and continuing stirring at room temperature for 40 min;
(4) pouring the obtained dispersion into a 80 mL autoclave, and keeping the temperature at 140 ℃ for 12 h;
(5) washing the obtained product with distilled water and anhydrous ethanol for 5 times, respectively, dispersing the obtained precipitate in a culture dish containing anhydrous ethanol, placing the culture dish in an oven at 80 deg.C, and oven drying for 8 hr to obtain 40% Zn3In2S6/g-C3N4Powder;
application test:
two 250 mL 20mg/L tetracycline solutions were prepared and then 0.05g g-C was added separately3N4And 40% Zn3In2S6/g-C3N4And catalysts for carrying out photocatalytic reactions, respectively. Performing ultrasonic dispersion for 15 min in dark, placing in a dark box, and magnetically stirring for 40 min to reach adsorption balance; then, a 300W xenon lamp with a 420 nm cut-off filter is used as a visible light source, the reaction time is 150 min, and 20 mL of solution is taken every 20 min. Two centrifugations were carried out at 10000 rpm for 5 min each, and then the supernatant was filtered with a 0.45 μm filter. The filtrate was taken to test absorbance. However 40% Zn3In2S6/g-C3N4The degradation rate of the tetracycline solution is 84%.
Example 3
The preparation of the binary photocatalytic material comprises the following steps:
(1) adding 2.43 mmol of zinc chloride, 1.62 mmol of indium chloride and 2.43 mmol of sodium citrate into a solution of which the volume ratio of water to ethylene glycol is 5:1, wherein the total volume of the solution is 60 mL, and then carrying out ultrasonic dispersion for 40 min to obtain a uniformly dispersed solution;
(2) 0.50 g of g-C3N4Adding into the above solution, and stirring at room temperature for 50 min;
(3) adding 4.85 mmol of thiourea into the solution according to the stoichiometric ratio, and continuing stirring at room temperature for 50 min;
(4) pouring the obtained dispersion into an 80 mL autoclave, and keeping the temperature at 160 ℃ for 12 hours;
(5) washing the obtained product with distilled water and anhydrous ethanol for 3 times, respectively, dispersing the obtained precipitate in a culture dish containing anhydrous ethanol, placing the culture dish in an oven at 60 deg.C, and oven drying overnight to obtain 100% Zn3In2S6/g-C3N4Powder;
application test:
two 250 mL 20mg/L tetracycline solutions were prepared and then 0.05g g-C was added separately3N4And 100% Zn3In2S6/g-C3N4And catalysts for carrying out photocatalytic reactions, respectively. Performing ultrasonic dispersion for 15 min in dark, placing in a dark box, and magnetically stirring for 40 min to reach adsorption balance; then, a 300W xenon lamp with a 420 nm cut-off filter is used as a visible light source, the reaction time is 150 min, and 20 mL of solution is taken every 20 min. Two centrifugations were carried out at 10000 rpm for 5 min each, and then the supernatant was filtered with a 0.45 μm filter. The filtrate was taken to test absorbance. Then the time (t) is taken as the abscissa, C/C0Curves are plotted for the ordinate. Experiments show that: binary complex 100% Zn3In2S6/g-C3N4The degradation rate of the tetracycline solution is 83.8%.