Metal-carboxyl double-ion shielding type carbon nitride material applied to reverse osmosis concentrated water ozone catalytic oxidation coupling photocatalysis, preparation method and device

Abstract

The invention discloses a metal-carboxyl double-ion shielding type carbon nitride material for treating reverse osmosis concentrated water of petrochemical wastewater by a catalytic ozonation coupling photocatalysis process and a reaction device, belongs to the technical field of water pollution treatment, and particularly relates to the field of advanced oxidation purification of sewage. The problems of high salt ion concentration, catalyst surface scaling and the like in the petrochemical wastewater reverse osmosis concentrated water can be effectively solved. The designed catalytic ozonation coupling photocatalytic reaction device can remove part of ions easy to precipitate in the precipitation area, soften water and effectively purify sewage in the ozone-photocatalytic reactor. The prepared metal-carboxyl double-ion shielding type carbon nitride material has catalytic ozonation, photocatalytic oxidation and catalytic ozonation coupled photocatalytic activity, can generate stimulus response to inlet air of ozone and the like and a light source provided by a lamp tube in the water treatment process, generates active free radical groups of hydroxyl and the like, degrades pollutants, and meanwhile, can be used for preparing a water treatment agent. The introduced metal cations can weaken the scaling effect of calcium and magnesium ions in the reverse osmosis concentrated water, and the introduced carboxyl functional groups can repel chloride ions, so that the catalyst can effectively remove organic pollutants in the concentrated water.

Description

Technical Field

[0001] The present invention relates to the technical field of water pollution control, in particular to the field of ozone catalysis and photocatalysis technology treatment, and specifically to a metal-carboxyl double ion shielded carbon nitride material, a preparation method and a device for ozone catalytic oxidation coupled photocatalysis of reverse osmosis concentrated water. Background Art

[0002] The reverse osmosis concentrate in the petrochemical industry has the characteristics of high salinity, high toxicity, and difficulty in degradation. Its complex water quality makes it difficult to achieve deep removal of pollutants using traditional processes. Ozone catalytic oxidation coupled with photocatalytic technology is an advanced oxidation technology that significantly improves the treatment efficiency of difficult-to-degrade organic pollutants through synergistic effects and is often used to treat difficult-to-degrade organic wastewater. However, its application in reverse osmosis concentrate still faces many challenges: high concentrations of salt ions cause deactivation of catalyst active sites and structural instability, and free radical quenching leads to attenuation of pollutant degradation efficiency.

[0003] During operation, the ozone catalytic oxidation coupled photocatalytic system responds to surface stimuli such as ozone and light sources, producing hydroxyl radicals, superoxide radicals and other free groups with strong oxidizing properties, effectively treating pollutants in sewage. At the same time, the metal cations in the catalyst can inhibit the effect of high salt ions on the degradation efficiency, and reduce the scaling problem on the catalyst surface to increase the service life of the catalyst. The research and development and application of ozone catalytic oxidation coupled photocatalytic materials and devices can improve degradation efficiency, extend catalyst life, and promote the development of ozone catalytic oxidation coupled photocatalytic technology in the field of water pollution treatment. Summary of the invention

[0004] The purpose of the present invention is to solve the key challenges faced by reverse osmosis concentrate, and to provide a metal-carboxyl double ion shielded carbon nitride material, a preparation method and a device for ozone catalytic oxidation coupled with photocatalysis of reverse osmosis concentrate. The prepared catalyst has ozone catalytic oxidation, photocatalysis, photo-Fenton and ozone catalytic oxidation coupled with photocatalytic activity, and can respond to surface stimuli such as ozone and light source during operation to produce strong oxidizing active free groups such as hydroxyl and superoxide radicals to purify sewage.

[0005] To achieve the above objectives, the present invention provides a metal-carboxyl double ion shielded carbon nitride material and a preparation method for ozone catalytic oxidation coupled photocatalysis of reverse osmosis concentrated water, and the specific steps are as follows:

[0006] S1, mixing melamine, anhydrous oxalic acid and a certain amount of metal salt and grinding them thoroughly, and heating the mixed powder in an air-tight condition to obtain carbon nitride powder I;

[0007] S2. Mix the carbon nitride powder I and concentrated nitric acid, and stir to obtain the precursor I. Filter the precursor I using a vacuum decompression filtration device, wash it three times with ethanol and deionized water until the pH value of the washing liquid is greater than 6, and dry, grind, and collect the precipitate to obtain powder II.

[0008] Preferably, the mass ratio of melamine to anhydrous oxalic acid is 2-5:1 (g:g), and the molar ratio of melamine to metal salt is 5-20:1; the types of metal salts are manganese chloride, potassium chloride, and sodium chloride; the calcination reaction temperature is 400-600 °C, the heating rate is 3-15 °C / min, and the calcination reaction time is 2-6 h.

[0009] Preferably, the concentration of concentrated nitric acid in step S2 is 10-16 mol / L; the stirring temperature is 20-40 °C, and the stirring time is 1-6 h.

[0010] On the other hand, the present invention provides a metal-carboxyl double-ion shielded carbon nitride material-loaded ozone catalytic oxidation coupled photocatalysis device and method, and the specific content is as follows:

[0011] A metal-carboxyl double-ion shielded carbon nitride material-loaded ozone catalytic oxidation coupled photocatalysis device, which is characterized by mainly including: a precipitation device housing (1), an inlet valve I (2), a precipitation device cover (3), a serrated overflow weir (4), a stirring rod (5), a stirring paddle (6), a drain port I (7), a sludge discharge port (8), an outlet I (9), a plug-type catalyst feeding port (10), an exhaust port (11), a tail gas collection device (12), an outlet II (13), four packing plates (14), a light source (15), a lamp shade (16), an ozone-photocatalysis reactor housing (17), an aeration disk (18), an air inlet (19), an ozone-photocatalysis reactor cover (20), an inlet II (21), a peristaltic pump (22), a gas cylinder (23), an ozone generator (24), a gas flow meter (25), and an ozone monitor (26);

[0012] The components (3), (5), (6), (10), (14), (15), (16), (18), and (20) are all detachable parts and are easy to replace;

[0013] Preferably, the main material of the packing plate (14) is the metal-carboxyl double-ion shielded carbon nitride material described in claim 1, and the types include one or more of immobilized packing, membrane loading, and magnetic catalyst; the air inlet of the aeration disk (18) is one or more of ozone, oxygen, and air; the light source (15) can be one or more of ultraviolet lamps, xenon lamps, LED lamps, and mercury lamps; the precipitation agent in the precipitation device is one or more of slaked lime (calcium hydroxide), sodium carbonate, and sodium bicarbonate.

[0014] An ozone catalytic oxidation coupled with photocatalysis device and method, characterized in that sewage is continuously fed through an external peristaltic pump to inlet I (2). After adding a precipitation agent in the stirring area for preliminary reaction, it overflows from the serrated overflow weir (4) to the precipitation area, and then overflows through the overflow weir to outlet I (9). Then it is pumped by a peristaltic pump (22) to ozone-photocatalysis device inlet II (21). When the sewage stays in the ozone-photocatalysis reaction device, the catalyst in the packing plate (14) generates a stimulus response to the light source (15), gases such as ozone in the mixed liquid, and the feed surface, generating active species such as hydroxyl radicals, decomposing and mineralizing pollutants near the packing plate, and being able to effectively inhibit the influence of high chloride ions in reverse osmosis concentrate and weaken the scaling effect of calcium and magnesium ions; the treated water enters outlet II (13) for detection and discharge; sludge and other precipitates generated during the precipitation process can be discharged through the drain port (7) and the sludge discharge port (9); gases such as ozone are generated by a gas cylinder (23) and an ozone generator (24), the flow rate is controlled by a gas flow meter (25), and then the ozone concentration is monitored in real time by an ozone monitor (26), and is transmitted to the aeration disc (18) through the air inlet (19). The gas after the reaction enters the tail gas collection device (12) through the exhaust port (11) and is then discharged; the feed port (10) is used for the upgrade of subsequent reaction processes and sampling.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0016] 1. In the preparation process of the metal-carboxyl double-ion shielded carbon nitride material of the present invention, metal ions and active functional groups are simultaneously introduced into the carbon nitride material, obtaining diverse chemical properties such as charge distribution, energy band structure, and surface potential. At the same time, the introduction of metal can weaken the catalyst fouling problem caused by the precipitation of calcium and magnesium ions in reverse osmosis concentrate; the introduction of carboxyl functional groups can effectively resist the free radical quenching problem caused by high chloride ions in the concentrate. The introduction of metal and functional groups can further enhance the electron generation and transmission rate of the carbon nitride material, thereby effectively promoting the generation rate of surface active free radicals of the metal-carboxyl double-ion shielded carbon nitride material and improving the sewage purification effect.

[0017] 2. Compared with the existing processes, the precipitation device part in the present invention can precipitate and soften some calcium and magnesium ions and dissolved solids in reverse osmosis concentrate. At the same time, the ozone catalytic oxidation coupled with photocatalysis material and device can respond to surface stimuli such as ozone and light source, and during the reaction process, ozone, light source, and water inflow can all be adjusted, enabling continuous purification of sewage. During the operation of the device, the ozone catalytic oxidation coupled with photocatalysis reaction can proceed fully, realizing the synergistic degradation of ozone catalysis and photocatalysis and completing the efficient catalytic oxidation of sewage. Description of the Drawings

[0018] Figure 1Photograph of the metal-carboxyl dual-ion shielded carbon nitride material prepared in Example 1;

[0019] Figure 2 Performance graph of the metal-carboxyl dual-ion shielded carbon nitride material prepared in Example 1 for degrading 20 mg / L p-nitrophenol containing different concentrations of salt ions.

[0020] Figure 3 Photograph of the ozone catalytic oxidation coupled photocatalysis device (the packing plate is not installed for easy observation);

[0021] Figure 4 Schematic diagram of the ozone catalytic oxidation coupled photocatalysis process device, where the precipitation device and the ozone-photocatalysis device in the front view are the main components, and the top view is a sectional view of the front view (the cover plate is not drawn);

[0022] In the figure: 1 - precipitation device housing, 2 - inlet valve I, 3 - precipitation device cover plate, 4 - serrated overflow weir, 5 - stirring rod, 6 - stirring paddle, 7 - drain port I, 8 - sludge discharge port, 9 - outlet port I, 10 - plug-type catalyst feeding port, 11 - exhaust port, 12 - tail gas collection device, 13 - outlet port II, 14 - four packing plates in total, 15 - light source, 16 - lamp shade, 17 - ozone-photocatalysis reactor housing, 18 - aeration disc, 19 - inlet port, 20 - ozone-photocatalysis reactor cover plate, 21 - inlet port II, 22 - peristaltic pump, 23 - gas cylinder, 24 - ozone generator, 25 - gas flow meter, 26 - ozone monitor. Detailed implementation manners

[0023] The following further illustrates the present invention with specific embodiments. The described embodiments are only partial embodiments of the present invention, not all embodiments. The following embodiments are used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Those of ordinary skill in the art should understand that all other embodiments obtained without creative efforts fall within the protection scope of the present invention.

[0024] The overall idea of the technical solution of the embodiment of the present invention application to solve the above problems is as follows:

[0025] The present invention provides a metal-carboxyl dual-ion shielded carbon nitride material, a preparation method and a device for ozone catalytic oxidation coupled photocatalysis of reverse osmosis concentrate. The prepared catalyst has ozone catalytic oxidation, photocatalysis, photo-Fenton and ozone catalytic oxidation coupled photocatalytic activities, and can respond to surface stimuli such as ozone and light source during operation to generate strongly oxidizing active free radicals such as hydroxyl radicals and superoxide radicals to purify sewage. The metal-carboxyl dual-ion shielded carbon nitride material is prepared by optimizing the modification of the carbon nitride material;

[0026] The present invention also provides an ozone catalytic oxidation coupled with photocatalysis process device. After the sewage enters the device, it is mixed with a precipitation agent, then enters the precipitation area and overflows, and enters the ozone-photocatalytic reactor through a peristaltic pump, where it is mixed and treated with the inlet gas. During the treatment process, under the coupling action of the lamp tube with the inlet gas, feed, etc., the material generates a stimulus response, generating active substances such as hydroxyl radicals, decomposing and mineralizing the surrounding pollutants, and realizing the purification of sewage. During the operation process, the inlet gas, feed, and lamp tube can be adjusted according to the sewage quality to promote the continuous and stable operation of the reaction.

[0027] Example 1

[0028] An embodiment of the present application provides a metal-carboxyl dual-ion shielded carbon nitride material and a preparation method, including the following steps:

[0029] Melamine, oxalic acid (the mass ratio of melamine to oxalic acid is 5:1), and manganese chloride (the molar ratio of melamine to manganese chloride is 10:1) are fully ground. The ground powder is calcined and reacted at 500 °C for 4 h (5 °C / min) in an atmosphere of nitrogen (2 mL / min) to obtain carbon nitride powder I;

[0030] 1 g of carbon nitride powder I and 20 mL of concentrated nitric acid (15 mol / L) are mixed, stirred at 25 °C for 2 h, then filtered through a vacuum decompression filtration device, rinsed 3 times with ethanol and deionized water respectively until the pH of the filtrate is greater than 6, and then the filtered powder is collected, dried, ground, and stored.

[0031] Example 2

[0032] An embodiment of the present application provides an ozone catalytic oxidation coupled with photocatalysis treatment device, including the following parts:

[0033] Precipitation device housing (1), inlet valve I (2), precipitation device cover (3), serrated overflow weir (4), stirring rod (5), stirring paddle (6), drain port I (7), sludge discharge port (8), outlet I (9), plug-type catalyst feeding port (10), exhaust port (11), tail gas collection device (12), outlet II (13), four packing plates (14), light source (15), lamp shade (16), ozone-photocatalytic reactor housing (17), aeration disc (18), inlet port (19), ozone-photocatalytic reactor cover (20), inlet port II (21), peristaltic pump (22), gas cylinder (23), ozone generator (24), gas flow meter (25), ozone monitor (26);

[0034] The components (3), (5), (6), (10), (14), (15), (16), (18), (20) are all detachable parts and are easy to replace;

[0035] The main material in the packing plate (14) is a metal-carboxyl bionic ion shielded carbon nitride material, and the types include but are not limited to immobilized packing, membrane loading, and magnetic catalysts; the gas inlet of the aeration disk (18) is one or more of ozone, oxygen, and air; the light source (15) can be one or more of ultraviolet lamps, xenon lamps, LED lamps, and mercury lamps; the precipitation agent in the precipitation device is one or more of slaked lime (calcium hydroxide), sodium carbonate, and sodium bicarbonate.

[0036] Working principle: Sewage is continuously fed through an external peristaltic pump to the water inlet I (2). After the precipitation agent is added in the stirring area for preliminary reaction, it overflows from the serrated overflow weir (4) to the precipitation area, and then overflows through the overflow weir to the water outlet I (9). Then, it goes through the peristaltic pump (22) to the water inlet II (21) of the ozone-photocatalysis device. When the sewage stays in the ozone-photocatalysis reaction device, the catalyst in the packing plate (14) generates a stimulus response to the light source (15), ozone and other gases in the mixed liquid, and the feed surface, generating reactive species such as hydroxyl radicals, decomposing and mineralizing the pollutants near the packing plate, and effectively inhibiting the influence of high chloride ions in the reverse osmosis concentrate and weakening the scaling effect of calcium and magnesium ions; the treated water enters the water outlet II (13) for detection and discharge; the sludge and other precipitates generated during the precipitation process can be discharged through the drain port (7) and the sludge discharge port (9); ozone and other gases are generated by the gas cylinder (23) and the ozone generator (24), the flow rate is controlled by the gas flow meter (25), and then the ozone concentration is monitored in real time by the ozone monitor (26), and is transmitted to the aeration disk (18) through the air inlet (19). The gas after the reaction enters the tail gas collection device (12) through the exhaust port (11) and is then discharged; the feed port (10) is used for the upgrade of the subsequent reaction process and sampling.

Claims

1. A metal-carboxyl double-ion shielded carbon nitride material and preparation method applied to an ozone catalytic oxidation coupled photocatalysis process for reverse osmosis concentrated water, characterized in that, The metal-carboxyl double ion shielded carbon nitride material has multifunctional catalytic activity such as ozone catalytic oxidation, photocatalytic oxidation, ozone catalytic oxidation coupled with photocatalytic oxidation, and can remove pollutants by adding ozone, light source, etc.; the preparation method of the metal-carboxyl double ion shielded carbon nitride material used in the photocatalytic coupled ozone catalytic process specifically includes the following steps: S1, mixing melamine, anhydrous oxalic acid and a certain amount of metal salt and grinding them thoroughly, and heating the mixed powder in an air-tight condition to obtain carbon nitride powder I; S2. Mix carbon nitride powder I and concentrated nitric acid, stir to obtain precursor I, filter precursor I using a vacuum decompression filtration device, wash with ethanol and deionized water three times until the pH value of the washing liquid is greater than 6, and dry, grind and collect the precipitate to obtain powder II.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of melamine to anhydrous oxalic acid is 2-5:1 (g:g), and the molar ratio of melamine to metal salt is 5-20:1; the types of metal salts are manganese chloride, potassium chloride, and sodium chloride; the calcination reaction temperature is 400-600°C, the heating rate is 3-15°C / min, and the calcination reaction time is 2-6h. In step S2, the concentration of concentrated nitric acid is 10-16 mol / L; the stirring temperature is 20-40° C., and the stirring time is 1-6 h.

3. A metal-carboxyl double-ion shielded carbon nitride material-supported ozone catalytic oxidation coupled photocatalytic device for implementing the method according to claim 1, characterized in that, Mainly includes: precipitation Device housing (1), water inlet valve I (2), sedimentation device cover plate (3), serrated overflow weir (4), stirring rod (5), stirring paddle (6), water outlet I (7), mud outlet (8), water outlet I (9), plug-type catalyst feed port (10), exhaust port (11), tail gas collection device (12), water outlet II (13), four packing plates (14), light source (15), lampshade (16), ozone-photocatalytic reactor housing (17), aeration plate (18), air inlet (19), ozone-photocatalytic reactor cover plate (20), water inlet II (21), peristaltic pump (22), gas cylinder (23), ozone generator (24), gas flow meter (25), and ozone monitor (26); The components (3), (5), (6), (10), (14), (15), (16), (18), and (20) are all detachable parts and can be easily replaced; The main material in the filler plate (14) is the metal-carboxyl dual ion shielded carbon nitride material as described in claim 1, and its types include but are not limited to fixed fillers, membrane loads and magnetic catalysts; the air intake of the aeration plate (18) is one or more of ozone, oxygen, and air; the light source (15) can be one or more of ultraviolet lamps, xenon lamps, LED lamps, and mercury lamps; the precipitation agent in the precipitation device is one or more of slaked lime (calcium hydroxide), sodium carbonate, and sodium bicarbonate.

4. An ozone catalytic oxidation coupled photocatalytic device as described in claim 3, characterized in that, The sewage is continuously fed through an external peristaltic pump to the inlet I (2). After preliminary reaction with the precipitation agent added in the stirring area, it overflows from the serrated overflow weir (4) to the precipitation area, and then overflows to the outlet I (9) through the overflow weir, and then is sent to the inlet II (21) of the ozone-photocatalysis device through the peristaltic pump (22). When the sewage stays in the ozone-photocatalysis reaction device, the catalyst in the packing plate (14) generates a stimulus response to the light source (15), gases such as ozone in the mixed liquid, and the feed surface, generating active species such as hydroxyl radicals, decomposing and mineralizing the pollutants near the packing plate, and being able to effectively inhibit the influence of high chloride ions in the reverse osmosis concentrate and weaken the scaling effect of calcium and magnesium ions; the treated water enters the outlet II (13) for detection and discharge; the sludge and other precipitates generated during the precipitation process can be discharged through the drain port (7) and the sludge discharge port (9). Gases such as ozone are generated by the gas cylinder (23) and the ozone generator (24), the flow rate is controlled by the gas flowmeter (25), and then the ozone concentration is monitored in real time by the ozone monitor (26), and is transmitted to the aeration disk (18) through the air inlet (19). The gas after the reaction enters the tail gas collection device (12) through the exhaust port (11) and then is discharged; the feed port (10) is used for the upgrade of the subsequent reaction process and sampling.

5. An ozone catalytic oxidation coupled photocatalytic reaction device as described in claims 3-4, wherein the packing plate (14) has multifunctional catalytic activities such as ozone catalytic oxidation, photocatalytic oxidation, and ozone catalytic oxidation coupled with photocatalysis; the component (15) can provide a light source during the reaction process to promote the catalyst to purify the sewage; the aeration disk (18) and the air inlet (19) can realize gas-liquid mixing during the reaction process to ensure the stability of the reaction process; the peristaltic pump (22) can realize continuous water inlet between the reactors, ensure sufficient hydraulic retention time, and ensure the efficiency of sewage purification.

6. A metal-carboxyl double-ion shielded carbon nitride material prepared by the preparation method as described in any one of claims 1-2.

7. An application of an ozone catalytic oxidation coupled photocatalytic reaction device as described in claims 3-4 in the field of water treatment.

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