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

Abstract

The application discloses a metal-carboxyl dual-ion shielding type carbon nitride material applied to an ozone catalytic oxidation coupling photocatalysis process for treating petrochemical wastewater reverse osmosis concentrated water and a reaction device, belongs to the technical field of water pollution treatment, and particularly relates to the field of advanced oxidation and purification of sewage, and can effectively solve the problems of high salt ion concentration and catalyst surface scaling in petrochemical wastewater reverse osmosis concentrated water. The designed ozone catalytic oxidation coupling photocatalysis device can remove part of easily precipitated ions in a precipitation area, simultaneously soften water quality, and effectively purify sewage in an ozone-photocatalysis reactor. The prepared metal-carboxyl dual-ion shielding type carbon nitride material has ozone catalytic oxidation, photocatalytic oxidation and ozone catalytic oxidation coupling photocatalytic activity, generates active free radicals in response to the light source provided by the air inlet and the lamp tube in the water treatment process, degrades pollutants, meanwhile, 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] This invention relates to the field of water pollution control technology, and more particularly to the field of ozone catalytic synergistic photocatalytic technology treatment. Specifically, it relates to a method and apparatus for preparing a metal-carboxyl dual-ion shielded carbon nitride material for ozone catalytic oxidation coupled with photocatalysis in reverse osmosis concentrate. Background Technology

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

[0003] Ozone catalytic oxidation coupled with photocatalysis operates by responding to surface stimuli such as ozone and light sources, generating highly oxidizing free radicals like hydroxyl radicals and superoxide radicals. These effectively treat pollutants in wastewater. Simultaneously, the metal cations in the catalyst suppress the impact of high salt ions on degradation efficiency and reduce scaling on the catalyst surface, thus extending its lifespan. The research and application of ozone catalytic oxidation coupled with photocatalysis materials and devices can improve degradation efficiency, extend catalyst lifespan, and promote the development of ozone catalytic oxidation coupled with photocatalysis technology in the field of water pollution treatment. Summary of the Invention

[0004] The purpose of this invention is to address key challenges faced by reverse osmosis concentrate, and to provide a metal-carboxyl dual-ion shielded carbon nitride material, its preparation method, and apparatus for ozone catalytic oxidation coupled with photocatalysis in reverse osmosis concentrate. The prepared catalyst has ozone catalytic oxidation, photocatalysis, and ozone catalytic oxidation coupled with photocatalysis activities. It can respond to ozone and light source surface stimulation during operation, generating highly oxidizing active free radicals to purify wastewater.

[0005] To achieve the above objectives, this invention provides a method for preparing a metal-carboxyl dual-ion shielded carbon nitride material for use in reverse osmosis concentrate ozone catalytic oxidation coupled with photocatalysis, the specific steps of which are as follows:

[0006] S1. Melamine, anhydrous oxalic acid and a certain amount of metal salt are mixed and ground thoroughly. The metal salt is manganese chloride, potassium chloride and sodium chloride. The mixed powder is heated under air-isolated conditions to obtain carbon nitride powder I.

[0007] S2. Mix carbon nitride powder I with concentrated nitric acid and stir to obtain precursor I. Filter precursor I using a vacuum decompression filtration device, wash it three times with ethanol and deionized water until the pH of the washing solution 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), the molar ratio of melamine to metal salt is 5-20:1, and the metal salt is manganese chloride, potassium chloride, or sodium chloride; the calcination reaction temperature is 400-600 ℃, the heating rate is 3-15 ℃ / min, and the calcination reaction time is 2-6 h.

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

[0010] Another aspect of the present invention provides an ozone catalytic oxidation coupled photocatalytic device and method supported on a metal-carboxyl dual-ion shielded carbon nitride material, the details of which are as follows:

[0011] An ozone catalytic oxidation coupled photocatalytic device supported on a metal-carboxyl dual-ion shielded carbon nitride material is characterized by comprising: a sedimentation device shell (1), an inlet valve I (2), a sedimentation device cover plate (3), a sawtooth overflow weir (4), a stirring rod (5), a stirring paddle (6), a drain outlet I (7), a sludge outlet (8), a water outlet I (9), a plug-type catalyst feed outlet (10), an exhaust outlet (11), a tail gas collection device (12), a water outlet II (13), four packing plates (14), a light source (15), a lamp cover (16), an ozone-photocatalytic reactor shell (17), an aeration disc (18), an air inlet (19), an ozone-photocatalytic reactor cover plate (20), a water 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 four components of the sedimentation device, including the cover plate (3), stirring rod (5), stirring paddle (6), plug-type catalyst feed port (10), and packing plate (14), as well as the light source (15), lamp cover (16), aeration disc (18), and ozone-photocatalytic reactor cover plate (20), are all easy-to-disassemble parts and are easy to replace.

[0013] Preferably, the main material in the packing plate (14) is a metal-carboxyl dual-ion shielded carbon nitride material prepared by the preparation method, including one or more of immobilized packing, membrane support and magnetic catalyst; the air intake of the aeration disc (18) is one or more of ozone, oxygen and air; the light source (15) can be one or more of ultraviolet lamp, xenon lamp, LED lamp and mercury lamp; the precipitating agent in the precipitation device is one or more of quicklime, sodium carbonate and sodium bicarbonate.

[0014] A method for an ozone-catalytic oxidation coupled photocatalytic device is characterized in that wastewater is continuously fed into the inlet valve I (2) via an external peristaltic pump. After a preliminary reaction with a precipitating agent added in the stirring zone, the wastewater overflows from the sawtooth overflow weir (4) to the sedimentation zone, then overflows through the overflow weir to the outlet I (9), and then through the peristaltic pump (22) to the inlet II (21) of the ozone-photocatalytic device. When the wastewater stays in the ozone-photocatalytic reaction device, the catalyst in the packing plate (14) stimulates the light source (15), the ozone and other gases in the mixed liquid, and the feed surface, generating active species such as hydroxyl radicals, which decompose and mineralize pollutants near the packing plate and can effectively inhibit the reaction. The effects of high chloride ions in the permeate concentrate and the reduction of the scaling effect of calcium and magnesium ions; the treated water enters the outlet II (13) for detection and discharge; the sludge generated during the sedimentation process can be discharged through the drain outlet I (7) and the sludge discharge outlet (8); 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 the ozone concentration is monitored in real time by the ozone monitor (26). The ozone is transmitted to the aeration plate (18) through the air inlet (19), and the gas after the reaction enters the tail gas collection device (12) through the exhaust outlet (11) and is discharged; the plug-type catalyst feed port (10) is used for the upgrading 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. The preparation process of the metal-carboxyl dual-ion shielded carbon nitride material of the present invention simultaneously introduces metal ions and active functional groups into the carbon nitride material, resulting in diverse chemical properties such as charge distribution, band structure, and surface potential. Simultaneously, the introduction of metal can mitigate catalyst scaling problems caused by calcium and magnesium ion precipitation in reverse osmosis concentrate; the introduction of carboxyl functional groups can effectively resist free radical quenching caused by high chloride ions in the concentrate. The introduction of metal and functional groups can further enhance the electron generation and transport rate of the carbon nitride material, thereby effectively promoting the generation rate of active free radicals on the surface of the metal-carboxyl dual-ion shielded carbon nitride material and improving wastewater purification efficiency.

[0017] 2. Compared with existing processes, the precipitation device in this invention can precipitate and soften some calcium and magnesium ions and dissolved solids in the reverse osmosis concentrate. Simultaneously, the ozone catalytic oxidation coupled with photocatalytic materials and devices can respond to surface stimuli such as ozone and light sources. Furthermore, the ozone, light source, and influent flow rate during the reaction process can all be adjusted, enabling continuous wastewater purification. During device operation, the ozone catalytic oxidation coupled with photocatalysis can proceed fully, achieving synergistic degradation through ozone catalysis and photocatalysis, resulting in highly efficient catalytic oxidation of wastewater. Attached Figure Description

[0018] Figure 1 is a physical image of the metal-carboxyl dual-ion shielding carbon nitride material prepared in Example 1;

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

[0020] Figure 3 shows a physical image of the ozone catalytic oxidation coupled with photocatalysis device (the packing plate was not installed for easy observation).

[0021] Figure 4 is a schematic diagram of an ozone catalytic oxidation coupled photocatalytic device, in which the main view shows the precipitation device and the ozone-photocatalytic device as the main components, and the top view is a cross-sectional view of the main view (the cover plate is not shown).

[0022] In the diagram: 1-Sedimentation device shell, 2-Inlet valve I, 3-Sedimentation device cover plate, 4-Serrated overflow weir, 5-Agitator rod, 6-Agitator paddle, 7-Drain outlet I, 8-Sludge discharge outlet, 9-Outlet I, 10-Plug-type catalyst feed port, 11-Exhaust port, 12-Tail gas collection device, 13-Outlet II, 14-Four packing plates, 15-Light source, 16-Lamp cover, 17-Ozone-photocatalytic reactor shell, 18-Aeration disc, 19-Air inlet, 20-Ozone-photocatalytic reactor cover plate, 21-Inlet II, 22-Peristaltic pump, 23-Gas cylinder, 24-Ozone generator, 25-Gas flow meter, 26-Ozone monitor. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments. The described embodiments are only some embodiments of the present invention, not all embodiments. The following embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Those skilled in the art should understand that all other embodiments obtained without creative effort are within the scope of protection of the present invention.

[0024] The technical solution of the embodiments of this invention is to solve the above problems, and the overall idea is as follows:

[0025] This invention provides a method and apparatus for preparing a metal-carboxyl dual-ion shielded carbon nitride material for ozone catalytic oxidation coupled with photocatalysis in reverse osmosis concentrate. The prepared catalyst has ozone catalytic oxidation, photocatalysis, and ozone catalytic oxidation coupled with photocatalysis activities. It can respond to surface stimuli such as ozone and light sources during operation, generating highly oxidizing active free radicals such as hydroxyl and superoxide radicals to purify wastewater. The metal-carboxyl dual-ion shielded carbon nitride material is prepared through the optimization of modified carbon nitride materials.

[0026] This invention also provides an ozone catalytic oxidation coupled photocatalytic process device. After the wastewater enters the device, it is mixed with the precipitating agent, then enters the sedimentation zone and overflows. It is then pumped into the ozone-photocatalytic reactor by a peristaltic pump and mixed with the intake air for treatment. During the treatment process, under the coupling effect of the lamp tube, the intake air, and the feed, the material generates a stimulation response, generates active free radicals, decomposes and mineralizes the surrounding pollutants, and achieves the purification of wastewater. During operation, the intake air, feed, and lamp tube can be adjusted according to the wastewater quality to promote continuous and stable operation of the reaction. Example

[0027] One embodiment of this application provides a metal-carboxyl dual-ion shielded carbon nitride material and its preparation method, comprising the following steps:

[0028] Melamine, oxalic acid (melamine to oxalic acid mass ratio of 5:1) and manganese chloride (melamine to manganese chloride molar ratio of 10:1) were thoroughly ground, and the ground powder was calcined at 500 °C for 4 h (5 °C / min) under a nitrogen atmosphere (2 mL / min) to obtain carbon nitride powder I.

[0029] Mix 1 g of carbon nitride powder I with 20 mL of concentrated nitric acid (15 mol / L), stir at 25 °C for 2 h, then filter through a vacuum filtration device, wash three times with ethanol and deionized water respectively until the pH of the filtrate is greater than 6, then collect the filtered powder, dry, grind and store. Example

[0030] One embodiment of this application provides an ozone catalytic oxidation coupled with photocatalysis, comprising the following parts:

[0031] Sedimentation device shell (1), inlet valve I (2), sedimentation device cover plate (3), sawtooth overflow weir (4), stirring rod (5), stirring paddle (6), drain outlet I (7), sludge outlet (8), water outlet I (9), plug-type catalyst feed port (10), exhaust port (11), tail gas collection device (12), water outlet II (13), packing plate (14) (four pieces in total), light source (15), lamp cover (16), ozone-photocatalytic reactor shell (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), ozone monitor (26);

[0032] The four components of the sedimentation device, including the cover plate (3), stirring rod (5), stirring paddle (6), plug-type catalyst feed port (10), and packing plate (14), as well as the light source (15), lamp cover (16), aeration disc (18), and ozone-photocatalytic reactor cover plate (20), are all easy-to-disassemble parts and are easy to replace.

[0033] The main material in the packing plate (14) is a metal-carboxyl dual-ion shielded carbon nitride material, including one or more of immobilized packing, membrane-supported materials and magnetic catalysts; the air intake of the aeration disc (18) is one or more of ozone, oxygen and air; the light source (15) can be one or more of ultraviolet lamp, xenon lamp, LED lamp and mercury lamp; the precipitating agent in the precipitation device is one or more of quicklime, sodium carbonate and sodium bicarbonate.

[0034] Working principle: Wastewater is continuously fed into the inlet valve I (2) via an external peristaltic pump. After the initial reaction of the precipitating agent added in the mixing zone, it overflows from the sawtooth overflow weir (4) to the sedimentation zone, and then overflows through the overflow weir to the outlet I (9). After that, it is pumped by the peristaltic pump (22) to the inlet II (21) of the ozone-photocatalytic device. When the wastewater stays in the ozone-photocatalytic reaction device, the catalyst in the packing plate (14) stimulates the light source (15), the ozone and other gases in the mixed liquid, and the feed surface, generating active species such as hydroxyl radicals, which decompose and mineralize pollutants near the packing plate, and can effectively inhibit the high chloride ion concentration in the reverse osmosis concentrate. The scale formation effect of calcium and magnesium ions is reduced; after treatment, the water enters the outlet II (13) for detection and discharge; the sludge and other sediments generated during the sedimentation process can be discharged through the drain outlet I (7) and the sludge discharge outlet (8); 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 the ozone concentration is monitored in real time by the ozone monitor (26). The ozone is transmitted to the aeration plate (18) through the air inlet (19), and the gas after the reaction enters the tail gas collection device (12) through the exhaust outlet (11) and is discharged; the plug-type catalyst feed port (10) is used for the upgrading of subsequent reaction processes and sampling.

Claims

1. A preparation method of a metal-carboxyl dual-ion shielding carbon nitride material applied to an ozone catalytic oxidation coupled photocatalytic process of reverse osmosis concentrated water, characterized in that, The metal-carboxyl double ion shielding type carbon nitride material has ozone catalytic oxidation, photocatalytic oxidation, ozone catalytic oxidation coupled with photocatalytic oxidation multifunctional catalytic activity, and the removal of pollutants is realized by adding ozone and light sources; the preparation method of the metal-carboxyl double ion shielding type carbon nitride material specifically comprises the following steps: S1, melamine, anhydrous oxalic acid and a certain amount of metal salt are mixed and fully ground, the metal salt is manganese chloride, potassium chloride or sodium chloride; and the mixed powder is heated under air isolation conditions to obtain carbon nitride powder I; S2, the carbon nitride powder I and concentrated nitric acid are mixed and stirred to obtain a precursor I, the precursor I is filtered by a vacuum reduced pressure filtration device, washed with ethanol and deionized water for 3 times until the pH value of the washing liquid is greater than 6, and the precipitate is dried, ground and collected to obtain powder II.

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

3. The metal-carboxylate dual-ion-shielded carbon nitride material supported catalytic ozonation and photocatalysis device prepared by the method of claim 1, wherein, Mainly including: precipitate The device shell (1), the water inlet valve I (2), the precipitate device cover plate (3), the sawtooth overflow weir (4), the stirring rod (5), the stirring paddle (6), the drain I (7), the sludge discharge port (8), the water outlet I (9), the plug type catalyst feeding port (10), the exhaust port (11), the tail gas collection device (12), the water outlet II (13), the filler plate (14) four pieces, the light source (15), the lampshade (16), the ozone-light catalytic reactor shell (17), the aeration disc (18), the air inlet (19), the ozone-light catalytic reactor cover plate (20), the water inlet II (21), the peristaltic pump (22), the gas cylinder (23), the ozone generator (24), the gas flow meter (25), and the ozone monitor (26); The precipitate device cover plate (3), the stirring rod (5), the stirring paddle (6), the plug type catalyst feeding port (10), the filler plate (14) four pieces, the light source (15), the lampshade (16), the aeration disc (18), and the ozone-light catalytic reactor cover plate (20) are all easily detachable parts, which are convenient to replace; The main body material in the filler plate (14) is the metal-carboxyl double ion shielding type carbon nitride material prepared by the preparation method in claim 1, and the types include one or more of immobilized filler, membrane loading and magnetic catalyst; the aeration disc (18) inlet gas is one or more of ozone, oxygen and air; the light source (15) is one or more of ultraviolet lamp, xenon lamp, LED lamp and mercury lamp; and the precipitating agent in the precipitating device is one or more of slaked lime, sodium carbonate and sodium bicarbonate.

4. The ozone catalytic oxidation coupled photocatalytic device according to claim 3, wherein Sewage is pumped to the water inlet valve I (2) by the external peristaltic pump to realize continuous water inlet. After adding the precipitation reagent in the stirring zone and preliminary reaction, the sewage overflows from the serrated overflow weir (4) to the sedimentation zone, and then overflows from the overflow weir to the water outlet I (9), and then is pumped to the ozone-light catalytic device water inlet II (21) by the peristaltic pump (22). When the sewage stays in the ozone-light catalytic reaction device, the catalyst in the filler plate (14) responds to the light source (15) and the dissolved ozone, oxygen and feed surface in the mixed solution to generate active free radicals, which decompose and mineralize the pollutants near the filler plate, and can effectively inhibit the influence of high chloride ions in reverse osmosis concentrated water and weaken the scaling effect of calcium and magnesium ions. After treatment, the water enters the water outlet II (13) for detection and discharge. The sludge produced in the sedimentation process is discharged through the drain I (7) and the sludge discharge port (8). Ozone, oxygen and air are generated by the gas cylinder (23) and the ozone generator (24), the flow rate is controlled by the gas flow meter (25), the ozone concentration is monitored in real time by the ozone monitor (26), and then transmitted to the aeration disc (18) through the gas inlet (19). The gas after reaction enters the tail gas collection device (12) through the exhaust port (11) and is discharged. The embolization type catalyst feeding port (10) is used for upgrading the subsequent reaction process and sampling.

5. The ozone catalytic oxidation coupled photocatalytic device according to any one of claims 3-4, wherein the filler plate (14) has ozone catalytic oxidation, photocatalytic oxidation, ozone catalytic oxidation coupled photocatalytic multifunctional catalytic activity; the light source (15) can provide a light source during the reaction process to promote the catalyst to realize sewage purification; the aeration disc (18) and the gas inlet (19) can realize gas-liquid mixing during the reaction process to ensure the stability of the reaction process; and the peristaltic pump (22) can realize continuous water inlet between reactors to ensure sufficient hydraulic retention time and guarantee the efficiency of sewage purification.

6. The metal-carboxyl dual ion shielding type carbon nitride material prepared by the preparation method according to any one of claims 1-2.

7. Application of the ozone catalytic oxidation coupled photocatalytic device according to any one of claims 3-4 in the field of water treatment.

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