CN111420706B - Cu 2 O/Bi 2 O 2 CO 3 Preparation method and application of semiconductor heterojunction composite silk fibroin fibrous membrane - Google Patents

Abstract

The invention discloses a preparation method and application of Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane. On the one hand, the present invention synthesizes a semiconductor heterojunction with excellent photocatalytic performance through a simple reducing solution chemical approach; The silk fibroin sponge is dissolved in formic acid according to a certain proportion and mixed evenly to prepare a silk fibroin-formic acid solution. Then, using silk fibroin as a carrier, the semiconductor heterojunction powders with different ratios were ultrasonically dispersed in the silk fibroin-formic acid solution to obtain a mixed spinning solution, and the electrospinning equipment was used to prepare the spinning solution under certain spinning conditions. Novel semiconductor material composite silk fibroin nanofiber membrane. The composite nano film of the invention has excellent photocatalytic degradation performance of chloramphenicol, and can be used for water treatment of organic pollution.

Description

Preparation of a Cu2O/Bi2O2CO3 Semiconductor Heterojunction Composite Silk Fibroin Fiber Membrane Method and application

technical field

The invention belongs to the technical field of composite nano functional materials, and in particular relates to a preparation method and application of a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane.

Background technique

At present, water pollution is becoming more and more serious. Traditional physical methods can only transfer pollutants but cannot degrade them. Chemical oxidation methods (such as oxidant oxidation method, photocatalytic method) can effectively degrade pollutants. Among them, the oxidant is expensive, while the photocatalyst has the characteristics of stability, high efficiency, low cost, and no pollution.

Cuprous oxide has a narrow band gap of about 2.1eV. It is a p-type semiconductor material with simple preparation method, low cost and no toxicity, so it has a bright prospect in the field of photocatalysis. However, studies have shown that pure cuprous oxide The photocatalytic efficiency is far below the ideal photocatalytic efficiency. Bismuth oxycarbonate has a bandgap of 2.8-3.5eV. It is an n-type semiconductor material. The wide bandgap limits its practical application to sunlight. Studies have shown that it can be made by combining it with narrow bandgap cuprous oxide. The heterojunction has significantly enhanced photocatalytic activity.

Silk fibroin is a natural biopolymer. Due to its biodegradability, good biocompatibility, high chemical reactivity, and excellent mechanical properties, it has attracted widespread attention in the development of new fiber materials in recent years. Attention, most of them are used in biomedical materials, and few people are used in photocatalytic research. As a cheap and easy-to-obtain natural polymer material, it is obvious that it can be used as an excellent carrier for powder photocatalysts through certain technologies.

Electrospinning is a simple, convenient, and effective technique for fabricating fibrous membranes. The preparation of fiber materials by electrospinning technology has the advantages of simple manufacturing equipment and easy control of process technology. The scaffold produced by it has a large surface area and a macroscopic sheet structure formed by ultra-long fibers, which can provide sufficient reaction for photocatalytic reactions. It also has the advantage of easy separation and recovery in water pollution treatment applications.

At present, there have been a large number of reports on semiconductor heterojunction materials. There are not many studies on heterojunctions made of cuprous oxide p-type semiconductors and bismuth oxycarbonate n-type semiconductors. It has not been reported that a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane is prepared by spinning. The present invention disperses the semiconductor heterojunction powder ultrasonically in the prepared silk fibroin fiber film of a certain concentration. _In the protein _{- formic acid} solution, it overcomes the characteristics that the powder photocatalyst is easy to scatter and is not easy to recycle. The effect is good.

Contents of the invention

The present invention aims to fill the gap in this technical field, and provides a preparation method and application of a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane.

The present invention is achieved through the following technical solutions:

A method for preparing a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane, comprising the following steps:

a. Put the shredded silkworm cocoons into a boiled aqueous solution of sodium carbonate with a mass concentration of 0.5%, the bath ratio is 1:30-1:50, boil for 30-60min, pick up, rinse with deionized water, repeat three times To carry out degumming treatment, the silk is air-dried at room temperature, loosened and packaged for later use;

b. Dissolve the degummed silk obtained in step a in 9mol/L lithium bromide aqueous solution at 40-60°C, and after 2-4 hours, place it in a constant temperature laboratory for 8-12 hours;

c. Inject the solution obtained in step b into a dialysis bag, perform dialysis with deionized water, keep stirring at low temperature, change the deionized water every 2-4 hours, and continue dialysis for 2-3 days;

d. Centrifuge the dialyzed solution in step c for 10-20 minutes to remove impurities, and obtain a silk fibroin solution;

e. Vacuum freeze-drying the silk fibroin solution obtained in step d to obtain a silk fibroin sponge;

f. dissolving the silk fibroin sponge obtained in step e in 98% formic acid organic solvent and mixing uniformly for subsequent use;

g. Prepare cuprous oxide/bismuth oxycarbonate semiconductor heterojunction according to the mass ratio of 1-5wt%. First, dissolve a certain amount of cetyltrimethylammonium bromide and ethylenediaminetetraacetic acid in distilled water, and then add A certain amount of prepared bismuth oxycarbonate is mixed evenly, and then different amounts of copper acetate are added to the solution for continuous magnetic stirring, and NaOH solution is added drop by drop under the stirring state, the solution appears blue suspension and continues to stir for 30-60min, Finally, ascorbic acid is slowly added dropwise to the solution and continuously stirred. In the above steps, the amount of copper acetate is first determined, and the molar ratio of hexadecyltrimethylammonium bromide: ethylenediaminetetraacetic acid: copper acetate=2: 3: 5 -2 : 4 : 5; copper acetate: NaOH: ascorbic acid=1 : 5 : 10-1 : 30 : 20 Weigh the reagent, try to isolate the air during the operation; wash the obtained sample with distilled water several times, and then 60-70 ℃ , vacuum dried for 6-12h to obtain Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction samples;

h. dispersing the semiconductor heterojunction powder obtained in step g in a silk fibroin-formic acid solution to prepare a spinning solution;

i. Put the spinning solution described in step h in the syringe of the electrospinning device, connect the needle of the syringe to the positive pole of the high-voltage generator, connect the aluminum foil receiver to the negative pole of the high-voltage receiver, and perform electrospinning, and the fiber membrane produced by electrospinning On foil flat receivers;

j. Soak the fibrous membrane in step i in 90% methanol for 8-15 minutes, rinse it with deionized water, and air-dry it at room temperature to obtain an insoluble Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane.

Further, in step c, the flattened width of the dialysis bag is 44 mm, and the molecular weight cut-off is 7000.

Further, in step d, the centrifugal speed is 8000-12000r/min.

Further, in step e, the vacuum freeze-drying temperature is -40°C~-45°C, and the time is 2-3 days.

Further, in step f, the concentration of the solution prepared by dissolving the silk fibroin sponge in formic acid is 15%.

Further, in step g, the amount of bismuth oxycarbonate added is 0.3-0.5g, the amount of NaOH solution added is 20-40mL, and the amount of ascorbic acid added is 20-40mL; the prepared Bi ₂ O ₂ CO ₃ has a flower shape , The average nanometer particle size is about 200nm.

Further, in step h, the mass concentration of the semiconductor heterojunction powder added is 5-10 wt%.

Further, in step i, the inner diameter of the injector spinneret is 0.50 mm, the distance between the injector spinneret and the surface of the flat receiver is 8-15 cm, and the applied voltage is 15-25 kV.

Further, in step i, the advancing speed of the syringe is 0.06-0.10 mm∙min ⁻¹ , and the horizontal reciprocating movement distance of the injector injection is 30-40 mm, so as to ensure a uniform fiber membrane obtained by electrospinning.

Further, the application of the Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane prepared in step j in wastewater treatment.

The beneficial effects of the present invention are:

The composite nano-membrane prepared by the method of the invention has excellent photocatalytic degradation performance of chloramphenicol, and the prepared composite nano-membrane has a high surface area, provides enough sites for photocatalytic reaction, and is easy to separate and recycle. The composite nanometer membrane prepared by the invention can be used as a high-efficiency photocatalytic membrane and has broad application prospects in medical wastewater and the like.

Description of drawings

Fig. 1 is the transmission electron microscope figure of embodiment 1-3 of the present invention and the transmission electron microscope figure under the high resolution of embodiment 2;

Fig. 2 is the ultraviolet-visible spectrogram of the composite nanofibrous membrane prepared by the embodiment of the present invention 1-3;

Fig. 3 is the scanning electron micrograph of the composite nanofiber membrane prepared by the embodiment of the present invention 1-3 and the scanning electron micrograph under the high magnification of embodiment 2;

Fig. 4 is the effect diagram of the photocatalytic degradation of chloramphenicol of the composite nanofiber membrane prepared by the embodiment of the present invention 1-3;

Fig. 5 is a graph showing the antibacterial effect of the composite nanofiber membrane prepared in Example 1-3 of the present invention on Escherichia coli and Staphylococcus aureus.

detailed description

In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the electric radioactive pollution decontamination device and emergency support system of the present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

Example 1

(1) Put 20g of shredded cocoons into 1000ml of boiled 0.5% sodium carbonate (Na ₂ CO ₃ ) aqueous solution, boil for 30 minutes, pick up, rinse with a large amount of deionized water, repeat the above steps Three times to carry out degumming treatment, the silk is air-dried at room temperature, loosened and packaged for later use. Take 2g of degummed silk and dissolve it in 9mol/L lithium bromide (LiBr) aqueous solution at 40°C for 2 hours, place the obtained solution in a constant temperature laboratory for 10 hours, inject it into a dialysis bag with a molecular weight cut-off of 7000, and perform dialysis with deionized water. Stir continuously at low temperature, change the deionized water every 2 hours, centrifuge the obtained solution at a speed of 10000r/min for 15min to remove impurities after 3 days, and vacuum freeze-dry the obtained silk fibroin solution at -45°C for 3 days Obtain a regenerated silk fibroin sponge. Prepare 3 mL of silk fibroin-formic acid solution with a mass concentration of 15% (0.6459 g of regenerated silk fibroin sponge dissolved in 3 mL of 98% formic acid) for use;

(2) Cuprous oxide (Cu ₂ O)/bismuth oxycarbonate (Bi ₂ O ₂ CO ₃ ) (p/n) semiconductor heterojunction was prepared at a mass ratio of 1 wt%, and 0.022g CTAB and 0.026g EDTA were weighed and dissolved in 50mL of distilled water, then add 0.4g of the prepared bismuth oxycarbonate and mix evenly, then add 0.03g of copper acetate (Cu(Ac) ₂ ) to the solution for continuous magnetic stirring, and add 20mL of NaOH (0.225 mol/L) solution, the solution appeared blue suspension and kept stirring for 30 min, and finally slowly added 20mL ascorbic acid (AA, 0.15mol/L) dropwise to the solution and kept stirring, try to isolate the air during the operation. The obtained sample was washed several times with distilled water, and then dried in vacuum at 70°C for 6 hours to obtain a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction sample with a mass ratio of 1 wt%, referred to as C1B;

(3) Weighing 0.3 g of the prepared semiconductor heterojunction powder and dispersing it in the silk fibroin-formic acid solution to prepare spinning solution;

(4) The obtained spinning solution is contained in a medical syringe linked to the electrospinning high-voltage device. The inner diameter of the spinneret of the syringe is 0.50 mm, the propulsion speed is 0.07 mm∙min ^-1 , and the horizontal reciprocating movement distance of the push column is 35 mm , with a distance of 8 cm from the surface of the roller receiver, and an adjustment voltage of 22kV, for electrospinning, and the electrospun fiber membrane was carried on a flat receiver based on aluminum foil.

Example 2

Keep steps (1), (3), and (4) in Example 1 unchanged, and prepare cuprous oxide (Cu ₂ O)/bismuth oxycarbonate (Bi ₂ O ₂ CO ₃ ) (p/n) semiconductor heterojunction, weigh 0.044g CTAB and 0.053g EDTA and dissolve in 50mL distilled water, then add 0.4g prepared bismuth oxycarbonate and mix well, then add 0.06g copper acetate (Cu (Ac) ₂ ) Continue magnetic stirring, dropwise add 20mL NaOH (0.45mol/L) solution under stirring state, the solution appears blue suspension and keep stirring for 30 min, finally slowly add 20mL ascorbic acid into the solution (AA, 0.3mol/L) and keep stirring, try to isolate the air during the operation. The obtained sample was washed several times with distilled water, and then dried in vacuum at 70°C for 6 hours to obtain a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction sample with a mass ratio of 3 wt%, referred to as C3B.

Example 3

Keep steps (1), (3), and (4) in Example 1 unchanged, and prepare cuprous oxide (Cu ₂ O)/bismuth oxycarbonate (Bi ₂ O ₂ CO ₃ ) (p/n) semiconductor heterojunction, weigh 0.058g CTAB and 0.073g EDTA and dissolve in 50mL distilled water, then add 0.4g prepared bismuth oxycarbonate and mix well, then add 0.08g copper acetate (Cu (Ac) ₂ ) Continue magnetic stirring, dropwise add 20mL NaOH (0.6mol/L) solution under stirring state, the solution appears blue suspension and keep stirring for 30 min, finally slowly add 20mL ascorbic acid into the solution (AA, 0.4mol/L) and keep stirring, try to isolate the air during the operation. The obtained sample was washed several times with distilled water, and then dried in vacuum at 70°C for 6 hours to obtain a Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction sample with a mass ratio of 5 wt%, referred to as C5B.

Example 4

The photocatalytic activity experiment of the Cu2O/ _Bi2O2CO3 semiconductor heterojunction composite silk fibroin fiber film that embodiment ₁ , example ₂ , example ₃ make:

Photocatalytic activity experiments were performed under a 300 W Xe lamp equipped with a 420 nm filter. Using chloramphenicol as the target pollutant, the prepared nanofibers were cut into a 4× ⁴ cm square sample and added to the target solution (50 mL, 20 mg/L). Stir the solution for 30 minutes in the dark to achieve the adsorption-desorption equilibrium between the organic macromolecules and the catalyst surface. After reaching the equilibrium, turn on the equipment and irradiate with ultraviolet light for 3 hours to carry out the photocatalytic degradation experiment. Take 1 mL of the reaction solution at intervals of 30 minutes for 0.22 Filter and store with a μm filter, and then analyze the water sample by high performance liquid chromatography (HPLC) to obtain the photolysis of chloramphenicol by the Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction composite silk fibroin fiber membrane efficiency.

Figure 1 is the TEM image of Examples 1-3 and the TEM image of Example 2 under high resolution. Bi ₂ O ₂ CO ₃ is composed of many nanosheets with a 1-2 μm three-dimensional flower-like structure, and Cu ₂ O nanometer The particles are uniformly distributed _on the surface _{of Bi2O2CO3} nanosheets.

Fig. 2 is the ultraviolet-visible spectrum of the composite nanofiber membrane prepared in Example 1-3. Compared with Bi ₂ O ₂ CO ₃ , the utilization rate of visible light absorption by the semiconductor heterojunction is significantly improved.

Figure 3 is the scanning electron micrograph of the composite nanofiber membrane prepared in Example 1-3 and the scanning electron micrograph at high magnification in Example 2, the Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction is wrapped in silk fibroin protein fibers, thus endowing the composite membrane with photocatalytic activity.

Fig. 4 is an effect diagram of the photocatalytic degradation of chloramphenicol by the composite nanofiber membrane prepared in Example 1-3. Compared with the pure silk fibroin film, the photocatalytic activity of the film was significantly enhanced by adding Cu ₂ O/Bi ₂ O ₂ CO ₃ semiconductor heterojunction, and the film incorporating the C3B heterojunction showed the highest photocatalytic degradation The ability of chloramphenicol, the degradation rate of the composite film to chloramphenicol reached 98.33% when visible light was irradiated for 30 minutes.

Fig. 5 is the antibacterial effect diagram of the composite nanofibrous membrane prepared in Example 1-3 to Escherichia coli and Staphylococcus aureus, the prepared composite membrane has better antibacterial activity, and the antibacterial rate varies with the _Cu2O increase and increase.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and those skilled in the art should understand that any person skilled in the art should be aware of any disclosure in the present invention Within the technical scope, easily conceivable changes or substitutions all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. Cu ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: the method comprises the following steps:

a, placing the cut silkworm cocoons into a boiled sodium carbonate aqueous solution with the mass concentration of 0.5%, boiling for 0-60min at a bath ratio of 1;

b. b, dissolving the degummed silk obtained in the step a in 9mol/L lithium bromide aqueous solution at the temperature of 40-60 ℃, and standing for 8-12 hours in a constant temperature laboratory after 2-4 hours;

c, injecting the solution obtained in the step b into a dialysis bag, dialyzing with deionized water, continuously stirring at a low temperature, changing the deionized water every 2-4 hours, and dialyzing for 2-3 days;

d, centrifuging the solution dialyzed in the step c for 10-20min to remove impurities to obtain a silk fibroin solution;

e, performing vacuum freeze drying on the silk fibroin solution obtained in the step d to obtain silk fibroin sponge;

f, dissolving the silk fibroin sponge obtained in the step e in 98% formic acid organic solvent, and uniformly mixing for later use;

g, preparing the cuprous oxide/bismuth oxycarbonate semiconductor heterojunction according to the mass ratio of 1-5 wt%, firstly, mixing a certain amount of hexadecyl trimethyl ammonium bromide anddissolving ethylene diamine tetraacetic acid in distilled water, adding a certain amount of prepared bismuthyl carbonate, uniformly mixing, then adding different amounts of copper acetate into the solution, continuously performing magnetic stirring, dropwise adding NaOH solution under the stirring state, allowing the solution to generate blue suspension, continuously stirring for 30-60min, and finally slowly adding ascorbic acid into the solution, and continuously stirring, wherein the amount of copper acetate is determined according to the molar ratio of hexadecyl trimethyl ammonium bromide to copper acetate = 5-2; weighing the following reagents in parts by weight, wherein the reagents comprise copper acetate, naOH and ascorbic acid =1 = 10-1; washing the obtained sample with distilled water for several times, and vacuum drying at 60-70 deg.C for 6-12h to obtain Cu ₂ O/Bi ₂ O ₂ CO ₃ A semiconductor heterojunction sample;

h. dispersing the semiconductor heterojunction powder obtained in the step g in a silk fibroin-formic acid solution to prepare a spinning solution;

i, the spinning solution in the step h is contained in an injector of an electrostatic spinning device, the needle head of the injector is connected with the positive electrode of a high-voltage generator, an aluminum foil receiver is connected with the negative electrode of the high-voltage receiver for electrospinning, and a fiber membrane obtained by electrostatic spinning is connected to an aluminum foil flat receiver;

j, soaking the fiber membrane in 90% methanol for 8-15 minutes, washing with deionized water, and air-drying at room temperature to obtain insoluble Cu ₂ O/Bi ₂ O ₂ CO ₃ The semiconductor heterojunction is compounded with the silk fibroin fibrous membrane.

2. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in step c, the dialysis bag was flattened to a width of 44mm and had a molecular weight cutoff of 7000.

3. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in the step d, the centrifugal speed is 8000-12000r/min.

4. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fiber membrane is characterized by comprising the following steps: in the step e, the temperature of vacuum freeze drying is-40 ℃ to-45 ℃ for 2-3 days.

5. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in step f, the concentration of the solution prepared by dissolving the silk fibroin sponge in formic acid is 15%.

6. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in the step g, the adding amount of the bismuthyl carbonate is 0.3-0.5g, the adding amount of the NaOH solution is 20-40mL, and the adding amount of the ascorbic acid is 20-40mL; prepared Bi ₂ O ₂ CO ₃ The appearance is flower-shaped, and the average nano-particle size is 200nm.

7. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in the step h, the mass concentration of the added semiconductor heterojunction powder is 5-10 wt%.

8. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: in the step i, the inner diameter of the spinneret of the injector is 0.50mm, the distance between the spinneret of the injector and the surface of the flat receiver is 8-15 cm, and the applied voltage is 15-25kV.

9. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ Semiconductor heterojunction recombinationThe preparation method of the silk fibroin fiber membrane is characterized by comprising the following steps: in step i, the injector propulsion speed is 0.06-0.10mm ∙ min ^-1 The horizontal reciprocating distance of the injector bolus is 30-40 mm.

10. Cu according to claim 1 ₂ O/Bi ₂ O ₂ CO ₃ The preparation method of the semiconductor heterojunction composite silk fibroin fibrous membrane is characterized by comprising the following steps: cu prepared in step j ₂ O/Bi ₂ O ₂ CO ₃ The semiconductor heterojunction composite silk fibroin fiber membrane is used as a photocatalytic material in the wastewater treatment.

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