Preparation method of ternary composite semiconductor photocatalyst and intermittent flow photocatalysis pharmaceutical wastewater treatment device based on photocatalyst

Abstract

The invention discloses a preparation method of a ternary composite semiconductor photocatalyst and an intermittent flow photocatalysis pharmaceutical wastewater treatment device based on the photocatalyst, and aims to solve the problems that the light absorption and utilization rate of the conventional catalyst is low, and organic pollutants such as antibiotics in wastewater are difficult to remove. The preparation method comprises the following steps: 1, uniformly mixing nano boron carbide and melamine, and carrying out heat treatment; 2, adding the binary composite material and charcoal into deionized water containing polyvinylpyrrolidone, and carrying out hydrothermal reaction to obtain a ternary composite material; and 3, adding the ternary composite material and polyacrylonitrile into dimethylformamide to obtain a spinning solution, and spinning the spinning solution through an electrostatic spinning process. According to the intermittent flow photocatalytic pharmaceutical wastewater treatment device, photocatalytic supported fiber filler is hung between an upper supporting frame and a lower supporting frame. The metal-free semiconductor photocatalytic material is prepared through one-pot heat treatment and a hydrothermal method, a wastewater treatment device is optimized based on the photocatalytic material, and the degradation rate of SMZ reaches 90% or above.

Description

Technical Field

[0001] The invention belongs to the field of industrial wastewater treatment, and specifically relates to a method for preparing a ternary composite semiconductor photocatalyst, and an intermittent flow photocatalytic pharmaceutical wastewater treatment device based on the ternary composite semiconductor photocatalyst. Background Art

[0002] With the improvement of people's living standards and the advancement of medical conditions, the use of drugs is becoming more and more extensive. Antibiotics are currently the most consumed type in China. Most of them are biological products, that is, they are extracted through the fermentation process. They are compounds produced by microorganisms, plants, and animals in their life processes. They are chemical substances that have the ability to selectively inhibit or kill other microorganisms or tumor cells at low concentrations. They are important chemical drugs for humans to control infectious diseases, maintain physical health, and prevent and treat animal and plant diseases.

[0003] At present, there are still many technical difficulties in the screening and production, strain breeding and other aspects of antibiotic production, resulting in many problems such as low raw material utilization, low extraction purity, high residual antibiotic content in wastewater, etc., causing serious environmental pollution.

[0004] Photocatalytic oxidation technology has been widely used in the degradation of organic pollutants due to its mild reaction conditions, high oxidation capacity, non-selectivity, and no secondary pollution. At present, some studies have used pilot-scale solar photocatalytic technology to treat industrial wastewater. The increase in the ratio of biological oxygen demand to chemical oxygen demand has proved the feasibility of using solar photocatalytic pretreatment to improve the biodegradability of industrial wastewater, which makes photocatalytic technology have a future application prospect in industrial wastewater treatment. However, the low light absorption utilization rate of photocatalysts and the difficulty in scaling up photocatalytic reactors are the main reasons hindering the large-scale industrial application of photocatalytic technology. The design of photocatalysts and reactors is conducive to accelerating the industrial application of photocatalytic technology. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of low light absorption utilization rate of existing catalysts and difficulty in removing organic pollutants such as antibiotics in wastewater, and to prepare a semiconductor photocatalyst with high efficiency in degrading micropollutants in industrial wastewater, and to design an intermittent flow photocatalytic wastewater treatment device based on the photocatalyst.

[0006] The preparation method of the ternary composite semiconductor photocatalyst of the present invention is implemented by the following steps:

[0007] Step 1: mixing nano boron carbide (B4C) and melamine at a mass ratio of 1:10 to 1:1, putting them into a crucible, placing them in a muffle furnace, performing heat treatment at a temperature of 350 to 550° C., and grinding to obtain a binary composite material;

[0008] Step 2: Add the binary composite material and biochar (BC) to deionized water containing polyvinyl pyrrolidone (PVP), stir to obtain a suspension, then pour the suspension into a reactor, perform a hydrothermal reaction at a temperature of 160 to 200° C. for 12 to 18 hours, cool, filter, dry, and grind to obtain a ternary composite material;

[0009] Step 3: adding the ternary composite material and polyacrylonitrile (PAN) into dimethylformamide (DMF), stirring for 6 to 10 hours to obtain a spinning solution, spinning the spinning solution through an electrospinning process to obtain a fiber filler, soaking the fiber filler in an alkaline solution for 10 to 16 hours, washing and drying to obtain a ternary composite semiconductor photocatalyst;

[0010] The mass ratio of the binary composite material to biochar (BC) in step 2 is 99:1 to 95:5.

[0011] The intermittent flow photocatalytic pharmaceutical wastewater treatment device based on a ternary composite semiconductor photocatalyst of the present invention comprises a feed tank, a photocatalytic reactor, an upper support frame, a lower support frame, a light source, an aeration pipe, an air intake pipe and a photocatalytic fiber filler. An upper support frame and a lower support frame are respectively arranged at the upper part and the lower part of the photocatalytic reactor, and a photocatalytic loaded fiber filler is hung between the upper support frame and the lower support frame. The photocatalytic fiber filler is a fiber bundle formed by bundling the ternary composite semiconductor photocatalyst;

[0012] The light source is arranged on the upper support frame, the aeration pipe is fixedly installed on the lower support frame, one end of the air inlet pipe is connected to the aeration pipe, the other end of the air inlet pipe is connected to the air outlet of the aeration pump, the feed tank is connected to the photocatalytic reactor through a water pipe, and a water inlet pump is arranged on the water pipe.

[0013] The present invention connects the photocatalytic fiber filler to a stainless steel frame (support frame) in an inclined hanging form and places it in water, and transports the wastewater containing micro-pollutants in the feed tank to the photocatalytic main reactor through a water inlet pump. In addition, air is evenly exposed to the water body through an aeration pump, an aeration pipeline and an aeration head evenly distributed at the bottom of the reactor. The water quality is evened through the rising airflow, the fiber filler bundle is dispersed, and the loaded photocatalyst is fully contacted with the pollutant molecules. A plate-type LED irradiation lamp source is installed on the top of the reactor to form surface source illumination. The water after photocatalytic treatment is discharged through a water outlet pump.

[0014] The present invention prepares metal-free semiconductor photocatalytic materials through one-pot heat treatment and hydrothermal method. By compounding p-type semiconductor (boron carbide) and n-type semiconductor (carbon nitride) to form a heterojunction, the carriers are effectively separated, and biochar is introduced as a medium to accelerate the migration of electrons. Fiber fillers are formed through electrospinning process, and bundled into clustered fillers, which provide a large number of sites for the adsorption and degradation of pollutants. At the same time, the filler is tilted at a certain angle so that the photocatalyst thereon can receive light over a large area and fully contact with the incoming water. In addition, through aeration, air is evenly pumped into the water, the water quality is made uniform by the flow of air, and the fiber filler clusters are broken up, so that the pollutants and the catalyst are fully in contact. In addition, the increase in dissolved oxygen allows the solution to contain superoxide anions (·O2 - ) and other active species, thus improving the photocatalytic efficiency. The plate-type LED irradiation lamp source provides a larger area of ​​light irradiation while saving energy, reducing the blind spots of light in the reactor. The entire reactor has a good treatment effect on pollutants. For example, when the concentration of sulfamethoxazole (SMZ) in the water is 10 mg / L, after 4 hours of treatment by the system, the degradation rate of SMZ can reach more than 92%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a SEM image of the ternary composite material obtained in Example 1;

[0016] Figure 2 The degradation curve of SMZ (10 mg / L) by the ternary composite photocatalyst obtained in Example 1 in a small test suspension system;

[0017] Figure 3 This is a schematic diagram of the structure of the intermittent flow photocatalytic pharmaceutical wastewater treatment device in Example 2;

[0018] Figure 4 This is the degradation curve of SMZ (10 mg / L) by the ternary composite photocatalyst filler in the system in the example. DETAILED DESCRIPTION

[0019] Specific implementation method 1: The preparation method of the ternary composite semiconductor photocatalyst of this implementation method is implemented according to the following steps:

[0020] Step 1: mixing nano boron carbide (B4C) and melamine at a mass ratio of 1:10 to 1:1, putting them into a crucible, placing them in a muffle furnace, performing heat treatment at a temperature of 350 to 550° C., and grinding to obtain a binary composite material;

[0021] Step 2: Add the binary composite material and biochar (BC) to deionized water containing polyvinyl pyrrolidone (PVP), stir to obtain a suspension, then pour the suspension into a reactor, perform a hydrothermal reaction at a temperature of 160 to 200° C. for 12 to 18 hours, cool, filter, dry, and grind to obtain a ternary composite material;

[0022] Step 3: adding the ternary composite material and polyacrylonitrile (PAN) into dimethylformamide (DMF), stirring for 6 to 10 hours to obtain a spinning solution, spinning the spinning solution through an electrospinning process to obtain a fiber filler, soaking the fiber filler in an alkaline solution for 10 to 16 hours, washing and drying to obtain a ternary composite semiconductor photocatalyst;

[0023] The mass ratio of the binary composite material to biochar (BC) in step 2 is 99:1 to 95:5.

[0024] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that in step 1, the mass ratio of nano-boron carbide (B4C) to melamine is 1:5 to 1:1.

[0025] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that in step one, the temperature is raised to 350-550° C. at a heating rate of 5-10° C. / min, and the heat treatment time is 3-5 h.

[0026] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the content of nano boron carbide in the binary composite material in step 1 is 1 to 5 wt.%.

[0027] Specific implementation method 5: This implementation method is different from specific implementation methods 1 to 4 in that the stirring treatment time in step 2 is 4 to 8 hours.

[0028] Specific embodiment 6: This embodiment is different from any one of specific embodiments 1 to 5 in that the mass ratio of the ternary composite material to polyacrylonitrile (PAN) in step 3 is 8:1 to 4:1.

[0029] Specific embodiment 7: This embodiment is different from any one of specific embodiments 1 to 6 in that in step 3, the spinning voltage in the electrospinning process is controlled to be 18-20 kV, and the spinning solution ejection speed is 1 mL / h.

[0030] Specific implementation eight: This implementation differs from any one of specific implementations one to six in that the alkali solution in step three is a 1 mol / L NaOH solution.

[0031] Specific embodiment nine: In this embodiment, the intermittent flow photocatalytic pharmaceutical wastewater treatment device based on the ternary composite semiconductor photocatalyst includes a feed tank 1, a photocatalytic reactor 2, an upper support frame 3, a lower support frame 4, a light source 5, an aeration pipe 6, an air intake pipe 9 and a photocatalytic fiber filler 7. The upper support frame 3 and the lower support frame 4 are respectively arranged at the upper part and the lower part of the photocatalytic reactor 2. A photocatalytic loaded fiber filler 7 is hung between the upper support frame 3 and the lower support frame 4. The photocatalytic fiber filler 7 is a fiber bundle formed by bundling the ternary composite semiconductor photocatalyst;

[0032] The light source 5 is arranged on the upper support frame 3, the aeration pipe 6 is fixedly installed on the lower support frame 4, one end of the air intake pipe 9 is connected to the aeration pipe 6, and the other end of the air intake pipe 9 is connected to the air outlet of the aeration pump 10, and the feeding tank 1 is connected to the photocatalytic reactor 2 through a water pipe, and a water intake pump 8 is arranged on the water pipe.

[0033] The intermittent flow photocatalytic pharmaceutical wastewater treatment device of this embodiment is suitable for industrial scale-up application.

[0034] Specific embodiment ten: This embodiment is different from specific embodiment nine in that the photocatalytically supported fiber filler 7 is hung obliquely, and the angle between the photocatalytically supported fiber filler 7 and the ground is 50-60°.

[0035] Specific embodiment eleven: This embodiment is different from specific embodiment nine or ten in that the hydraulic retention time in the photocatalytic reactor 2 is controlled to be 60 to 120 minutes.

[0036] Embodiment 1: The preparation method of the ternary composite semiconductor photocatalyst of this embodiment is implemented by the following steps:

[0037] Step 1: Mix nano boron carbide (B4C) and melamine in a mass ratio of 1:5, put them into a 50 mL alumina crucible with a lid, place them in a muffle furnace, heat them to 550° C. at a heating rate of 5° C. / min for 4 h, and grind them to obtain a binary composite material (1 wt.% B4C content);

[0038] Step 2: Add the binary composite material and biochar (BC) to deionized water containing polyvinyl pyrrolidone (PVP) in a mass ratio of 98:2, stir for 6 hours to obtain a suspension, then pour the suspension into a stainless steel reactor lined with polytetrafluoroethylene, heat the temperature to 180°C at a heating rate of 4°C / min, react for 14 hours, cool to room temperature, filter the solution, put the powder obtained by filtration into a vacuum oven and dry it overnight, and grind it to obtain a ternary composite material;

[0039] Step 3. Add the ternary composite material and polyacrylonitrile (PAN) to dimethylformamide (DMF) at a mass ratio of 5:1, stir for 8 hours to obtain a spinning solution, and load the spinning solution into a needle tube for spinning by an electrospinning process. The spinning voltage is controlled to be 20 kV, the spinning solution spraying speed is 1 mL / h, the electrospinning roller speed is 50 rpm, and the distance from the needle tip to the receiving roller is 20 cm. The fiber filler is obtained by electrospinning, and the fiber filler is immersed in a 1 mol / L NaOH solution for 12 hours. After washing and drying, the ternary composite semiconductor photocatalyst is obtained.

[0040] Embodiment 2: The intermittent flow photocatalytic pharmaceutical wastewater treatment device based on the ternary composite semiconductor photocatalyst of this embodiment comprises a feed tank 1, a photocatalytic reactor 2, an upper support frame 3, a lower support frame 4, a light source 5, an aeration pipe 6, an air intake pipe 9 and a photocatalytic fiber filler 7, wherein the upper support frame 3 and the lower support frame 4 are respectively arranged at the upper part and the lower part of the photocatalytic reactor 2, and the photocatalytic loaded fiber filler 7 is hung between the upper support frame 3 and the lower support frame 4, and the photocatalytic fiber filler 7 is a fiber bundle formed by bundling the ternary composite semiconductor photocatalyst;

[0041] The light source 5 is arranged on the upper support frame 3, the aeration pipe 6 is fixedly installed on the lower support frame 4, one end of the air inlet pipe 9 is connected to the aeration pipe 6, and the other end of the air inlet pipe 9 is connected to the air outlet of the aeration pump 10. The feeding tank 1 is connected to the photocatalytic reactor 2 through a water pipe, and a water inlet pump 8 is arranged on the water pipe. A water outlet pump 11 is arranged on the water outlet pipe of the photocatalytic reactor 2.

[0042] The ternary composite semiconductor photocatalytic material obtained in this embodiment was used to carry out a small test of a suspension system, and the concentration of sulfamethoxazole SMZ in the simulated water body was 10 mg / L. 0.05 g of the ternary composite semiconductor photocatalytic material was weighed and put into 100 mL of simulated water body. After dark adsorption for 30 minutes, it was placed under simulated sunlight for photocatalytic degradation, and the concentration of SMZ in the water body was measured. After 120 minutes of illumination, the degradation rate of SMZ in the water body reached 95.4%, which was 2.98 and 1.62 times the degradation rate of SMZ by g-C3N4 and binary materials, greatly improving the degradation efficiency of micropollutants in water.

[0043] Figure 1 The appearance morphology shows that the ternary composite photocatalytic material is well composited. The biochar fibers and the uniform loading of the other two materials on the biochar can be clearly seen. The shape is irregular and many spherical structures appear. The smaller particles ensure the adsorption of pollutants by the catalyst and provide more photocatalytic active sites. Figure 2 It can be seen that the ternary composite material has great superiority in degradation effect over the mono- and binary materials. Figure 3The schematic diagram of the intermittent flow photocatalytic pharmaceutical wastewater treatment device reflects the composition and specific structure of the system. Figure 4 The degradation curves of different loaded catalysts. The loading of the catalyst prolongs the photocatalytic time to a certain extent, but the filler loaded with the ternary photocatalyst still has a good photocatalytic effect on SMZ (10 mg / L), and can degrade 92.6% of SMZ in water within 4 hours.

Claims

1. A method for preparing a ternary composite semiconductor photocatalyst, characterized in that The preparation method of the ternary composite semiconductor photocatalyst is achieved by the following steps: Step 1, mixing nano boron carbide and melamine in a mass ratio of 1:10 to 1:1, putting them into a crucible, placing them in a muffle furnace, performing heat treatment at a temperature of 350 to 550° C., and grinding to obtain a binary composite material; Step 2: adding the binary composite material and biochar into deionized water containing polyvinyl pyrrolidone, stirring to obtain a suspension, then pouring the suspension into a reactor, hydrothermally reacting at a temperature of 160 to 200° C. for 12 to 18 hours, cooling, filtering, drying, and grinding to obtain a ternary composite material; Step 3: adding the ternary composite material and polyacrylonitrile to dimethylformamide, stirring for 6 to 10 hours to obtain a spinning solution, spinning the spinning solution through an electrostatic spinning process to obtain a fiber filler, soaking the fiber filler in an alkaline solution for 10 to 16 hours, washing and drying to obtain a ternary composite semiconductor photocatalyst; The mass ratio of the binary composite material to the biochar in step 2 is 99:1 to 95:

5.

2. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that In step 1, the mass ratio of nano boron carbide to melamine is 1:5 to 1:

1.

3. The method for preparing the ternary composite semiconductor photocatalyst according to claim 1, characterized in that In step 1, the temperature is raised to 350-550° C. at a heating rate of 5-10° C. / min, and the heat treatment time is 3-5 hours.

4. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that In step 1, the content of nano boron carbide in the binary composite material is 1 to 5 wt.%.

5. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that The stirring treatment time in step 2 is 4 to 8 hours.

6. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that In step three, the mass ratio of the ternary composite material to polyacrylonitrile is 8:1 to 4:

1.

7. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that In step 3, the spinning voltage in the electrospinning process is controlled to be 18-20 kV, and the spinning solution ejection speed is 1 mL / h.

8. The method for preparing a ternary composite semiconductor photocatalyst according to claim 1, characterized in that The alkali solution in step 3 is 1 mol / L NaOH solution.

9. An intermittent flow photocatalytic pharmaceutical wastewater treatment device based on the ternary composite semiconductor photocatalyst as claimed in claim 1, characterized in that The intermittent flow photocatalytic pharmaceutical wastewater treatment device based on a ternary composite semiconductor photocatalyst comprises a feed tank (1), a photocatalytic reactor (2), an upper support frame (3), a lower support frame (4), a light source (5), an aeration pipe (6), an air intake pipe (9) and a photocatalytic fiber filler (7); an upper support frame (3) and a lower support frame (4) are respectively arranged at the upper part and the lower part of the photocatalytic reactor (2); a photocatalytic loaded fiber filler (7) is hung between the upper support frame (3) and the lower support frame (4); the photocatalytic fiber filler (7) is a fiber bundle formed by bundling the ternary composite semiconductor photocatalyst; The light source (5) is arranged on the upper support frame (3), the aeration pipe (6) is fixedly mounted on the lower support frame (4), one end of the air intake pipe (9) is connected to the aeration pipe (6), the other end of the air intake pipe (9) is connected to the air outlet of the aeration pump (10), the feed tank (1) is connected to the photocatalytic reactor (2) through a water pipe, and a water intake pump (8) is arranged on the water pipe.

10. The intermittent flow photocatalytic pharmaceutical wastewater treatment device based on ternary composite semiconductor photocatalyst according to claim 9 is characterized in that The hydraulic retention time in the photocatalytic reactor (2) is controlled to be 60 to 120 minutes.

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