A carbon nitride-based supported photocatalytic material and device for combined photoelectrochemical oxidation of wastewater

Abstract

This invention provides a carbon nitride-based supported photocatalytic material and its device for combined photoelectrocatalysis, belonging to the field of environmental engineering, particularly in the field of wastewater catalytic oxidation and purification. It overcomes the shortcomings of traditional photocatalysis and electrocatalysis, such as high energy consumption and incomplete treatment. The preparation method of the carbon nitride-based supported photocatalytic material specifically includes the following steps: melamine and molybdenum disulfide are ultrasonically heated in water until the melamine is completely dissolved, obtaining solution I; cyanuric acid is ultrasonically heated in water until completely dissolved, obtaining solution II; solution II is added dropwise to solution I in a boiling water bath, ultrasonically treated and continuously stirred, and cooled to obtain precipitate I; precipitate I is subjected to a hydrothermal reaction to obtain precipitate II; precipitate II is calcined to obtain product I; product I is mixed with a conductive agent in aqueous polyurethane, ultrasonically stirred until completely mixed, coated onto the surface of a lightweight carrier, and dried to obtain the carbon nitride-based supported photocatalytic material.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering, and more particularly to the field of wastewater catalytic oxidation purification, specifically to a carbon nitride-based supported photocatalytic material and its device for wastewater photoelectric combined catalytic oxidation. Background Technology

[0002] In recent years, the requirements for wastewater treatment effluent standards have been continuously increasing. Due to the poor biodegradability of new pollutants, traditional biological treatment processes, such as the A2O process, cannot effectively remove them. Therefore, it is necessary to upgrade traditional treatment processes to improve effluent standards.

[0003] Advanced oxidation technologies are effective means of addressing new pollutant pollution. Changes in catalytic materials, equipment, and reaction conditions can all affect wastewater treatment effectiveness and efficiency. Photocatalysis and electrocatalysis are commonly used advanced oxidation technologies. However, photocatalysis relies on redox reactions between the valence and conduction bands of excited-state photocatalysts to directly degrade pollutants or generate free radicals. Commonly used industrial catalysts, such as TiO2, suffer from problems such as easy recombination of photogenerated carriers and poor light absorption range. Electrocatalysis relies on direct oxidation at the anode and activation of oxygen molecules at the cathode, converting them into hydrogen peroxide to achieve pollutant degradation. However, its performance is limited by low energy utilization and low hydrogen peroxide conversion rate.

[0004] Therefore, how to utilize photoelectro-photonic synergistic catalysis technology to achieve efficient and low-consumption upgrading of wastewater treatment has become a difficult problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon nitride-based supported photocatalytic material and its device for combined photoelectrocatalytic oxidation of wastewater. The combined photoelectrocatalytic effect of the prepared carbon nitride-based supported photocatalytic material in the combined photoelectrocatalytic device can overcome the defects of high energy consumption and incomplete treatment of traditional photocatalysis and electrocatalysis.

[0006] One aspect of the present invention provides a method for preparing a carbon nitride-based supported photocatalytic material for combined photoelectrochemical oxidation of wastewater, specifically comprising the following steps:

[0007] Melamine and molybdenum disulfide were added to water and ultrasonically heated until the melamine was completely dissolved to obtain solution I.

[0008] Add cyanuric acid to water and heat it ultrasonically until it is completely dissolved to obtain solution II;

[0009] Solution II was added dropwise to solution I in a boiling water bath, and the mixture was sonicated and stirred continuously. After cooling, precipitate I was obtained.

[0010] After reacting precipitate I in a hydrothermal reactor, the product obtained was collected and freeze-dried to obtain precipitate II.

[0011] Calcine precipitate II to obtain product I;

[0012] Product I was mixed with a conductive agent in waterborne polyurethane, ultrasonically stirred until completely mixed, coated on the surface of a lightweight carrier, and dried to obtain a carbon nitride-based supported photocatalytic material.

[0013] As a preferred technical solution, the mass ratio of melamine to molybdenum disulfide is 1:0.02-0.1;

[0014] As a preferred technical solution, the ultrasonic heating temperature is 60-80 degrees Celsius;

[0015] As a preferred technical solution, the molar ratio of melamine to cyanuric acid is 1:0.5-1.5;

[0016] As a preferred technical solution, the hydrothermal temperature is 140-220 degrees Celsius;

[0017] As a preferred technical solution, the calcination temperature is 480-600 degrees Celsius;

[0018] As a preferred technical solution, the mass ratio of the precipitate I to the waterborne polyurethane is 1:2-8;

[0019] As a preferred technical solution, the conductive agent is one or more of carbon nanotubes, graphene, and biochar, and the mass ratio of the conductive agent to product I is 1:0.02-0.12;

[0020] As a preferred technical solution, the ultrasonic time is 0.2-0.5 hours and the ultrasonic frequency is 20-60 kHz;

[0021] As a preferred technical solution, the drying temperature is 40-70 degrees Celsius;

[0022] Another aspect of the present invention provides a photoelectrocatalytic co-catalysis device, specifically comprising the following:

[0023] A photoelectrocatalytic device includes a housing (1), an electrode anode (2), a photocathode (3), an electrode support column (4), an electrode fixing plate (5), a power supply (6), a stirring paddle (7), a water inlet motor (8), a water inlet sensor (9), a water inlet pipe (10), a water outlet sensor (11), a water outlet pipe (12), and a power supply line (13).

[0024] The photocathode (3) includes an electrode cathode (31), a photocatalytic support tray (32), and a photocatalytic chamber (33). The photocatalytic support tray (32) includes a lamp source (321) and an aeration port (322). The photocatalytic chamber (33) includes the carbon nitride-based supported photocatalytic material as described in claim 1.

[0025] The light source (321) is one or more of xenon lamp, high-pressure mercury lamp, low-pressure mercury lamp, and halogen lamp, and the gas emitted from the aeration port (322) is one or more of oxygen, air, and ozone;

[0026] The photocatalytic chamber (33) is surrounded by chamber columns (331), and the spacing between the chamber columns (331) is smaller than the radius of the carbon nitride-based supported photocatalytic material;

[0027] The electrode support column (4) is hollow inside, and the power supply line (13) is connected to the electrode anode (2), electrode cathode (31), and lamp source (321) through the inside of the electrode support column (4).

[0028] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0029] 1. In the preparation process of the carbon nitride-based supported photocatalytic material of the present invention, molybdenum disulfide is incorporated into the precursors of melamine and cyanuric acid and calcined together to achieve uniform loading of molybdenum disulfide on the surface of carbon nitride, which effectively improves the generation and separation efficiency of photogenerated carriers and improves photocatalytic performance. Using waterborne polyurethane as a support binder and supplemented with a conductive agent can effectively maintain the catalytic performance of the carbon nitride-based photocatalytic material.

[0030] 2. The anode electrode directly electrocatalytically oxidizes organic pollutants in wastewater, while the cathode electrode converts oxygen-containing gas introduced through the aeration port into hydrogen peroxide and hydroxyl radicals through electrocatalysis. In the photocatalytic chamber, the carbon nitride-based supported photocatalytic material further converts the hydrogen peroxide that is not fully utilized by the cathode electrode into hydroxyl radicals through photocatalysis, achieving photoelectric synergy and completing the efficient catalytic oxidation of wastewater. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the photoelectric co-catalytic device of the present invention;

[0032] Figure 2 This is a schematic diagram of a photocathode;

[0033] Figure 3 This is a schematic diagram of the photocatalytic chamber;

[0034] In the diagram: 1. Shell, 2. Electrode anode, 3. Photocathode, 31. Electrode cathode, 32. Photocatalytic support tray, 321. Lamp source, 322. Aeration port, 33. Photocatalytic chamber, 331. Chamber column, 4, 5. Electrode fixing plate, 6. Power supply, 7. Stirring paddle, 8. Water inlet motor, 9. Water inlet sensor, 10. Water inlet pipe, 11. Water outlet sensor, 12. Water outlet pipe, 13. Power supply line. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Embodiment 1 of the present invention provides a method for preparing a carbon nitride-based supported photocatalytic material for combined photoelectric and photocatalytic oxidation of wastewater, specifically including the following steps:

[0037] S1: Melamine and molybdenum disulfide are added to water and ultrasonically heated until the melamine is completely dissolved to obtain solution I;

[0038] Add cyanuric acid to water and heat it ultrasonically until it is completely dissolved to obtain solution II;

[0039] Solution II was added dropwise to solution I in a boiling water bath, and the mixture was sonicated and stirred continuously. After cooling, precipitate I was obtained.

[0040] In this step, melamine and cyanuric acid will quickly produce a white precipitate after being dissolved in water and mixed. Mixing molybdenum disulfide with melamine in advance can make the molybdenum disulfide evenly distributed in the white precipitate, which is in preparation for the next step of uniform hydrothermal treatment.

[0041] S2: After reacting precipitate I in a hydrothermal reactor, the product obtained is collected and freeze-dried to obtain precipitate II;

[0042] Calcine precipitate II to obtain product I;

[0043] In this step, precipitate I will gradually grow into an unstable rod-shaped structure by relying on van der Waals forces during the hydrothermal process. At this time, high-temperature calcination and thermal exfoliation of it can make the carbon nitride-based photocatalytic material smaller in size and larger in specific surface area.

[0044] S3: Product I and the conductive agent are mixed in water-based polyurethane, ultrasonically stirred until completely mixed, coated on the surface of a lightweight carrier, and dried to obtain a carbon nitride-based supported photocatalytic material.

[0045] In this step, because waterborne polyurethane has a low density, product I and the conductive agent can be quickly and completely dispersed within it, avoiding clumping.

[0046] In a preferred embodiment of the present invention, the mass ratio of melamine to molybdenum disulfide is 1:0.02-0.1, and the molar ratio of melamine to cyanuric acid is 1:0.5-1.5. To ensure sufficient photocatalytic effect, the mass ratio of melamine to molybdenum disulfide is 1:0.02-0.1, and any ratio within this range is acceptable, such as 1:0.02, 1:0.05, 1:0.07, 1:0.1, etc. Within this range, the photocatalytic efficiency of the two is high. Similarly, the molar ratio of melamine to cyanuric acid is 1:0.5-1.5, and any ratio within this range is acceptable, such as 1:0.5, 1:0.75, 1:1, 1:1.25, 1:1.5, etc.

[0047] In a preferred embodiment of the present invention, the conductive agent is one or more of carbon nanotubes, graphene, and biochar, and the mass ratio of the conductive agent to product I is 1:0.02-0.12. Regarding the conductive agent, it is understood that commonly used conductive agents in the art can be used in the above steps. Because waterborne polyurethane has poor conductivity, too little conductive agent will lead to a decrease in the electron transport rate during the photocatalytic reaction, thus reducing photocatalytic activity. Conversely, too much conductive agent, due to its poor photocatalytic performance, will shield the active sites of product I, causing a decrease in photocatalytic activity.

[0048] Embodiment 2 of the present invention provides a photoelectrocatalytic co-catalysis device, specifically including the following:

[0049] A photoelectrocatalytic device includes a housing (1), an electrode anode (2), a photocathode (3), an electrode support column (4), an electrode fixing plate (5), a power supply (6), a stirring paddle (7), a water inlet motor (8), a water inlet sensor (9), a water inlet pipe (10), a water outlet sensor (11), a water outlet pipe (12), and a power supply line (13).

[0050] The photocathode (3) includes an electrode cathode (31), a photocatalytic support tray (32), and a photocatalytic chamber (33). The photocatalytic support tray (32) includes a lamp source (321) and an aeration port (322). The photocatalytic chamber (33) includes the carbon nitride-based supported photocatalytic material as described in claim 1.

[0051] The photocatalytic chamber (33) is surrounded by chamber columns (331), and the spacing between the chamber columns (331) is smaller than the radius of the carbon nitride-based supported photocatalytic material;

[0052] The electrode support column (4) is hollow inside, and the power supply line (13) is connected to the electrode anode (2), electrode cathode (31), and lamp source (321) through the inside of the electrode support column (4).

[0053] In the preferred embodiment of the present invention, the lamp source (321) is one or more of xenon lamp, high-pressure mercury lamp, low-pressure mercury lamp, and halogen lamp. Different lamp sources have different wavelengths and energy consumption, and the corresponding photocatalytic performance of carbon nitride-based supported photocatalytic materials is different. Therefore, the lamp source needs to be selected according to the specific water quality to be treated.

[0054] In the preferred embodiment of the present invention, the aeration port (322) emits one or more of oxygen, air, and ozone. The purpose of aeration is to provide oxygen for photocatalysis and electrocatalysis to accelerate the catalytic reaction. Generally, the different aeration efficiencies are ozone > oxygen > air. Therefore, the aeration type needs to be selected according to the specific water quality to be treated.

[0055] Example 1

[0056] Add 0.1 mol (12.61 g) of melamine and 0.63 g of molybdenum disulfide to water, and sonicate at 60 degrees Celsius until the melamine is completely dissolved to obtain solution I;

[0057] Add 0.1 mol (12.91) of cyanuric acid to water and sonicate at 60 degrees Celsius until completely dissolved to obtain solution II;

[0058] Solution II was added dropwise to solution I in a boiling water bath, and the mixture was sonicated at 50 kHz for 0.5 hours with constant stirring. After cooling, precipitate I was obtained.

[0059] After reacting precipitate I in a hydrothermal reactor at 180 degrees Celsius, the product was collected and freeze-dried to obtain precipitate II.

[0060] Precipitate II was calcined at 520 degrees Celsius to obtain product I;

[0061] 1g of product I and 0.02g of conductive agent were mixed in 5g of waterborne polyurethane, ultrasonically stirred until completely mixed, coated on the surface of a lightweight carrier, and dried to obtain carbon nitride-based supported photocatalytic material.

[0062] Example 2

[0063] The provided photoelectrocatalytic device is characterized by comprising a housing (1), an electrode anode (2), a photocathode (3), an electrode support column (4), an electrode fixing plate (5), a power supply (6), a stirring paddle (7), a water inlet motor (8), a water inlet sensor (9), a water inlet pipe (10), a water outlet sensor (11), a water outlet pipe (12), and a power supply line (13); the photocathode (3) comprises an electrode cathode (31), a photocatalytic support tray (32), and a photocatalytic chamber (33), and the photocatalytic support tray (32) comprises a lamp source. (321) Aeration port (322), photocatalytic chamber (33) contains the carbon nitride-based supported photocatalytic material prepared in Example 1; the lamp source (321) is a xenon lamp, and the air outlet (322) is air; the photocatalytic chamber (33) is surrounded by chamber columns (331), and the spacing between the chamber columns (331) is smaller than the radius of the carbon nitride-based supported photocatalytic material; the electrode support column (4) is hollow inside, and the power supply line (13) is connected to the electrode anode (2), electrode cathode (31), and lamp source (321) through the inside of the electrode support column (4). When the influent COD concentration is 60-100 mg / L, the effluent COD can be reduced to below 30 mg / L.

Claims

1. A method for preparing a carbon nitride-based supported photocatalytic material for combined photoelectrochemical oxidation of wastewater, characterized in that, Specifically, the steps include the following: Melamine and molybdenum disulfide were added to water and ultrasonically heated until the melamine was completely dissolved to obtain solution I. Add cyanuric acid to water and heat ultrasonically until completely dissolved to obtain solution II; Solution II was added dropwise to solution I in a boiling water bath, and the mixture was sonicated and stirred continuously. After cooling, precipitate I was obtained. The ultrasonic heating temperature of the melamine and cyanuric acid is 60-80 degrees Celsius, and the mass ratio of melamine to molybdenum disulfide is 1:0.02-0.

1. After reacting precipitate I in a hydrothermal reactor, the resulting product was collected and freeze-dried to obtain precipitate II. The hydrothermal temperature is 140-220 degrees Celsius; Calcine precipitate II to obtain product I; The calcination temperature is 480-600 degrees Celsius; Product I was mixed with a conductive agent in waterborne polyurethane, ultrasonically stirred until completely mixed, coated on the surface of a lightweight carrier, and dried to obtain a carbon nitride-based supported photocatalytic material.

2. The method for preparing the carbon nitride-based supported photocatalytic material according to claim 1, characterized in that, The molar ratio of melamine to cyanuric acid is 1:0.5-1.5; The mass ratio of precipitate I to waterborne polyurethane is 1:2-8; The conductive agent is one or more of carbon nanotubes, graphene, and biochar, and the mass ratio of the conductive agent to product I is 1:0.02-0.

12. The ultrasonic stirring time is 0.2-0.5 hours, and the ultrasonic stirring frequency is 20-60 kHz; The drying temperature is 40-70 degrees Celsius.

3. A photoelectrocatalytic device, comprising a housing (1), an electrode anode (2), a photocathode (3), an electrode support column (4), an electrode fixing plate (5), a power supply (6), a stirring paddle (7), a water inlet motor (8), a water inlet sensor (9), a water inlet pipe (10), a water outlet sensor (11), a water outlet pipe (12), and a power supply line (13); The photocathode (3) comprises an electrode cathode (31), a photocatalytic support tray (32), and a photocatalytic chamber (33). The photocatalytic support tray (32) comprises a lamp source (321) and an aeration port (322). The photocatalytic chamber (33) comprises the carbon nitride-based supported photocatalytic material prepared by the method of claim 1. The light source (321) is one or more of xenon lamp, high-pressure mercury lamp, low-pressure mercury lamp, and halogen lamp, and the gas emitted from the aeration port (322) is one or more of oxygen, air, and ozone; The photocatalytic chamber (33) is surrounded by chamber columns (331), and the spacing between the chamber columns (331) is smaller than the radius of the carbon nitride-based supported photocatalytic material; The electrode support column (4) is hollow inside, and the power supply line (13) is connected to the electrode anode (2), electrode cathode (31), and lamp source (321) through the inside of the electrode support column (4).

4. The photoelectrocatalytic co-catalysis device according to claim 3, characterized in that, After being powered on, the anode (2) directly electrocatalytically oxidizes organic pollutants in wastewater, and the cathode (31) electrocatalyzes the oxygen-containing gas introduced through the aeration port (322) into hydrogen peroxide and hydroxyl radicals. The carbon nitride-based supported photocatalytic material in the photocatalytic chamber (33) further converts the hydrogen peroxide that is not fully utilized by the cathode (31) into hydroxyl radicals through photocatalysis, thereby achieving efficient catalytic oxidation of wastewater.

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