Catalyst based on ozone photocatalytic oxidation coupling system and integrated sewage treatment equipment

Abstract

The invention provides a catalyst based on an ozone photocatalytic oxidation coupling system and integrated sewage treatment equipment, and relates to the field of environmental engineering, in particular to the field of advanced sewage treatment. According to the catalyst, the biochar with dual functions of adsorption and catalysis is mainly used as a catalyst carrier, an attachment condition is provided for in-situ growth of functionalized carbon nitride, and the catalytic capacity of the catalyst is improved. Integrated sewage treatment equipment comprises three core modules, namely a coagulating sedimentation chamber, a light-ozone synergistic catalytic reaction chamber and a central control chamber, and is small in occupied area and simple to operate. According to the invention, high-efficiency removal of traditional pollutants and new pollutants in sewage with different scales and different components can be realized through deep treatment, and a new scheme and thought are provided for upgrading and reconstruction projects of small and medium-sized sewage treatment plants.

Description

Technical Field

[0001] The present invention relates to the field of advanced sewage treatment, and particularly to a catalyst based on an ozone photocatalytic oxidation coupling system and an integrated sewage treatment device. Technical Background

[0002] In recent years, the country has continuously raised the requirements for water environment quality, and introduced a series of strict environmental protection policies and emission standards, which put forward higher requirements for the effluent quality of sewage treatment plants. Different sewage treatment plants have differences in water quality, water volume, emission standards, etc., and appropriate upgrading technologies need to be selected according to specific circumstances. However, small sewage treatment plants often face difficulties in technology selection, and problems such as small floor area, large capital investment, and shortage of technical personnel also bring many limitations. Therefore, we propose a catalyst based on an ozone photocatalytic oxidation coupling system and an integrated sewage treatment device, which synergistically couples ozone catalysis and photocatalysis, and uses an advanced treatment process to achieve efficient degradation of pollutants under complex water quality conditions, and solves the difficulties encountered by sewage treatment plants in upgrading. Summary of the Invention

[0003] The present invention aims to provide a catalyst based on an ozone photocatalytic oxidation coupling system and an integrated sewage treatment device. The application of the prepared biochar-based supported carbon nitride catalyst in the integrated sewage treatment device can effectively solve the problems of catalyst agglomeration, difficult separation, and inability to be recycled. The supporting integrated sewage treatment device can provide an application environment for the catalyst, can activate the catalyst by using sunlight, and can use solar power generation to supply the operation of the device.

[0004] One aspect of the present invention provides a preparation method of a biochar-based supported carbon nitride catalyst based on an ozone photocatalytic oxidation coupling system, which specifically includes the following steps:

[0005] S1. Preparation of functional group-doped carbon nitride:

[0006] Add a certain mass of melamine to water, ultrasonically heat until completely dissolved to obtain solution I; add a certain mass of cyanuric acid to water, ultrasonically heat until completely dissolved to obtain solution II; dropwise add solution II to solution I in a boiling water bath, and continue heating and stirring, wash with water to obtain precipitate I; carry out hydrothermal reaction of precipitate I with a certain volume of dopant in a hydrothermal reaction kettle, collect the obtained product after the reaction and freeze-dry to obtain precipitate II; calcine and react precipitate II in a nitrogen atmosphere to obtain functional group-doped carbon nitride.

[0007] S2. Preparation of molybdenum disulfide:

[0008] Weigh a certain mass of molybdenum trioxide and potassium thiocyanate, dissolve them in deionized water, and stir to dissolve to obtain Solution III; carry out hydrothermal reaction on Solution III in a hydrothermal reaction kettle, collect the product after the reaction and freeze-dry it to obtain molybdenum disulfide.

[0009] S3. Preparation of functional group-doped carbon nitride composite:

[0010] Mix a certain mass ratio of molybdenum disulfide and functional group-doped carbon nitride in an ethanol solution, perform ultrasonic treatment to mix evenly and then carry out magnetic stirring to achieve uniform dispersion, and obtain Precipitate III after drying treatment; calcine and react Precipitate III in a nitrogen atmosphere to obtain the functional group-doped carbon nitride composite.

[0011] S4. Preparation of alkali-modified biochar:

[0012] Grind the biomass and sieve it, then mix it with alkali in a certain mass ratio in an aqueous solution and soak it. After drying, carry out calcination reaction in a nitrogen atmosphere to obtain an alkali-modified product. After post-treatment, dry it to prepare alkali-modified green algae-based biochar.

[0013] S5. Preparation of biochar-based supported carbon nitride catalyst:

[0014] Disperse a certain mass ratio of alkali-modified biochar and functional group-doped carbon nitride composite in water and mix them to obtain Precipitate IV. Add a certain mass of support agent, binder, and pore-forming agent to it, mix evenly and stir into a mud-like state, and granulate it with a spherical mold and polystyrene foam balls. After freeze-setting, demold it and dry it at a certain temperature. Calcinate and react the dried material in a nitrogen atmosphere, and obtain the biochar-based supported carbon nitride catalyst after post-treatment.

[0015] As a preferred technical solution, in the step S1, the molar ratio of melamine to cyanuric acid is 1:0.5 - 1.5, and 0.0 - 0.05 mol of doping agent is added per 1 mol of melamine and cyanuric acid. The doping agent includes one or more of potassium thiocyanate, ammonium chloride, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0016] As a preferred technical solution, in the step S2, the molar ratio of molybdenum trioxide to potassium thiocyanate is 1:1 - 5.

[0017] As a preferred technical solution, in the step S3, the mass ratio of molybdenum disulfide to functional group-doped carbon nitride is 1:10 - 15.

[0018] As a preferred technical solution, in the step S4, the mass ratio of biomass to alkali is 1:1 - 6, the soaking time is 4 - 12 h, the biomass includes one or more of Enteromorpha prolifera, seaweed, straw, coconut shell, and sawdust, and the alkali includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0019] As a preferred technical solution, in the step S5, the mass ratio of the alkali-modified biochar and the functional group-doped carbon nitride composite is 4:1 - 4, and the mass ratio of the support agent, the binder, the pore-forming agent, and the precipitate Ⅳ is 1 - 6:1 - 4:1 - 4:1. The support agent includes one or more of diatomite, sepiolite, and zeolite. The binder includes one or more of epoxy resin, waterborne polyurethane, dextrin, cyclodextrin, and starch. The pore-forming agent includes one or more of ammonium bicarbonate, sodium bicarbonate, and sodium carbonate.

[0020] Further, in the step S4, the specific operation steps for grinding and sieving the biomass are as follows: After washing and drying the biomass, grind it into a powder, and sieve the obtained powder through a 100-mesh sieve for later use.

[0021] Further, in the steps S4 and S5, the specific post-treatment steps are as follows: Add the product to 1 - 5 mol / L hydrochloric acid for acid leaching for 1 - 3 h, then acid boil at 80 - 100 °C for 1 - 3 h. After natural cooling, wash it with ethanol 3 - 5 times, and finally wash it with deionized water until the solution is neutral.

[0022] Further, in the step S5, the mold is placed in a refrigerator for freezing and shaping for 1 - 3 h and then demolded, and the demolded product is dried at 160 - 180 °C for 2 - 5 h.

[0023] Further, in the steps S1, S3, and S4, the nitrogen gas flow rate is 2 - 5 mL / min, and the heating rate is 2 - 15 °C / min; in the step S1, the calcination reaction temperature is 300 - 600 °C, and the calcination reaction time is 2 - 8 h; in the step S3, the calcination reaction temperature is 300 - 500 °C, and the calcination reaction time is 1 - 5 h; in the step S4, the calcination reaction temperature is 400 - 800 °C, and the calcination reaction time is 1 - 5 h; in the step S5, the calcination reaction temperature is 300 - 500 °C, and the calcination reaction time is 1 - 5 h;

[0024] Further, in the step S1, the hydrothermal reaction temperature is 120 - 200 °C, and the hydrothermal reaction time is 4 - 10 h; in the step S2, the hydrothermal reaction temperature is 180 - 220 °C, and the hydrothermal reaction time is 18 - 24 h.

[0025] Further, in the steps S1 and S2, the ultrasonic time is 0.2 - 0.5 h, and the ultrasonic frequency is 20 - 60 kHz.

[0026] Further, in the step S1, the heating temperature is 60 - 90 °C; in the step S3, the drying temperature is 40 - 70 °C; in the step S4, the drying temperature is 40 - 70 °C.

[0027] Another aspect of the present invention provides an integrated sewage treatment device, specifically including the following:

[0028] An integrated sewage treatment device includes a box body (1), a coagulation sedimentation chamber (2), a photo-ozone synergistic catalytic reaction chamber (3), and a central control room (4);

[0029] Further, the coagulation sedimentation chamber (2) includes a chemical dosing pump (21), a first water pump (22), a first water quality sensor (23), a stirrer (24), a sludge discharge valve (25), a second water pump (26), and a second water quality sensor (27);

[0030] Further, the photo-ozone synergistic catalytic reaction chamber (3) includes a precision aeration disc (31), a transparent lamp cover (32), a light source (33), a catalytic chamber partition (34), a third water quality sensor (35), and a solar collector (36). The solar collector (36) includes a Fresnel lens (361), a light guide tube (362), and a diffuser (363);

[0031] Further, the central control room (4) includes a solar panel (41), a control panel (42), a storage battery (43), an integrated air source ozone generator (44), and an exhaust gas treatment device (45).

[0032] The solar panel (41) is connected to the storage battery (42), and can generate electricity using sunlight to supply power to the device;

[0033] The chemical dosing pump (21) can be used to add one or more of calcium hydroxide, sodium hydroxide, aluminum hydroxide, potassium alum, and polyacrylamide;

[0034] The light source in the light source (33) is one of a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, and a halogen lamp;

[0035] The catalytic chamber in the catalyst chamber partition (34) contains the biochar-based supported carbon nitride catalyst described in claim 1, and the diameter of the partition gap is smaller than the diameter of the biochar-based supported carbon nitride catalyst;

[0036] The solar collector (36) can be used to concentrate sunlight on sunny days to excite the catalyst, and the light source (33) provides the light source on cloudy days and at night;

[0037] The chemical dosing pump (21), the first water pump (22), the first water quality sensor (23), the stirrer (24), the second water pump (26), the second water quality sensor (27), the light source (33), the third water quality sensor (35), the storage battery (43), the integrated air source ozone generator (44), and the tail gas treatment device (45) are connected to the control panel (42), and the control panel is built with a control system, a display system, and a network system. The solar panel (11) is connected to the storage battery (43), and can use sunlight to generate electricity to supply power to the equipment.

[0038] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0039] 1. The biochar-based supported carbon nitride catalyst has excellent catalytic ozone oxidation performance and photocatalytic oxidation performance at the same time, and can realize the mutual activation and conversion of ozone and self-produced hydrogen peroxide to generate more reactive oxygen species, improving the degradation efficiency of pollutants. The central control spherical catalyst prepared with polystyrene foam balls as the hard template can realize the recycling and simple recovery of the catalyst, greatly reducing the practical application difficulty and application cost;

[0040] 2. The integrated sewage treatment equipment can deeply treat sewage with different scales and compositions. With the addition of solar panels and solar collectors, it can realize the efficient utilization of light energy and reduce the operating cost. The integrated equipment is easy to operate, convenient to move, occupies a small area, saves manpower, material resources and operation costs, and provides a new idea for the upgrading project of small and medium-sized sewage treatment plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a physical diagram of the catalyst

[0042] Figure 2 It is the degradation performance of the biochar-based supported carbon nitride catalyst under different systems

[0043] Figure 3 It is the degradation performance of the biochar-based supported carbon nitride catalyst for ozone-coupled photocatalytic actual wastewater

[0044] Figure 4 It is the integrated sewage treatment equipment DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0046] Embodiment 1

[0047] Melamine and cyanuric acid (molar ratio 1:1) were separately dissolved in aqueous solutions. The cyanuric acid solution was added dropwise to the melamine solution. After adding 0.2 mL of N,N-dimethylacetamide to the obtained precipitate, hydrothermal reaction was carried out at 180 °C for 8 h, and then the precipitate was collected and dried. Calcination reaction was carried out at 520 °C for 4 h under a nitrogen atmosphere (2 mL / min) to obtain functional group-doped carbon nitride; 100 mg of functional group-doped carbon nitride and 7.5 mg of molybdenum disulfide were fully mixed in ethanol, and after drying, calcination reaction was carried out at 300 °C for 1 h under a nitrogen atmosphere (2 mL / min) to obtain the preparation of functional group-doped carbon nitride composite materials; Enteromorpha was ground and passed through a 100-mesh sieve, and then mixed evenly with KOH in an aqueous solution at a mass ratio of 1:2 and soaked. After washing with water and drying, calcination reaction was carried out at 650 °C for 2 h under a nitrogen atmosphere (2 mL / min). The calcined product was added to 1 mol / L hydrochloric acid for acid leaching for 1 h and then acid boiling for 1 h. After natural cooling, it was washed with ethanol three times, and finally washed with deionized water until the solution was neutral to obtain alkali-modified biochar; The alkali-modified biochar and the functional group-doped carbon nitride composite material were dispersed in deionized water at a ratio of 4:1 to obtain a precipitate. Diatomite, dextrin, sodium carbonate, and the precipitate were mixed at a ratio of 5:3:2:1, stirred into a mud shape, granulated with a spherical mold and polystyrene foam balls (d = 2 mm), frozen and shaped, and then dried at 180 °C for 3 h. After drying, calcination reaction was carried out at 500 °C for 2 h under a nitrogen atmosphere (2 mL / min). The calcined product was washed with hydrochloric acid and water until neutral to obtain a biochar-based supported carbon nitride catalyst.

[0048] Example 2

[0049] Combined with the provided integrated sewage treatment equipment, it is characterized in that it includes a box body (1), a coagulation sedimentation chamber (2), a photo-ozone synergistic catalytic reaction chamber (3), and a central control room (4); the coagulation sedimentation chamber (2) includes a dosing pump (21), a first water pump (22), a first water quality sensor (23), a stirrer (24), a sludge discharge valve (25), a second water pump (26), and a second water quality sensor (27); the photo-ozone synergistic catalytic reaction chamber (3) includes a precision aeration disk (31), a transparent lamp cover (32), a light source (33), a catalytic chamber partition (34), a third water quality sensor (35), and a sunlight collector (36), and the natural light collector (36) includes a Fresnel lens (361), a light guide tube (362), and a diffuser (363); the central control room (4) includes a solar panel (41), a control screen (42), a storage battery (43), an integrated air source ozone generator (44), and a tail gas treatment device (45); the dosing pump (21) adds calcium hydroxide; the light source in the transparent lamp cover and the light source (32) is a xenon lamp; the catalyst in the catalyst chamber and the partition (33) is internally provided with the biochar-based supported carbon nitride catalyst prepared in Example 1, and the diameter of the partition gap is smaller than the diameter of the biochar-based supported carbon nitride catalyst.

[0050] The applicant declares that the above embodiments are used to illustrate the detailed operations and process flows of the present invention, but are not limited to the above detailed operations and process flows. Those skilled in the relevant technical fields should understand that the equivalent replacements of the raw materials and processes of the products of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

[0051] Experimental Example 1

[0052] The material prepared in Example 1 was subjected to experiments. The experiments used persistent organic pollutant PNP in new pollutants as the target pollutant, and tested its activity in ozone oxidation, ozone combined with visible light, ozone catalytic oxidation, and ozone catalytic oxidation combined with photocatalytic systems after slow adsorption. The results are as Figure 2 shown.

[0053] Experimental Example 2

[0054] The material prepared in Example 1 was subjected to experiments. The experiments used the reverse osmosis concentrate of an industrial park as the target pollutant, and tested its activity in the ozone catalytic oxidation combined with photocatalytic system after slow adsorption. The results are as Figure 3 shown.

Claims

1. A preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system, mainly comprising the following steps: S1. Preparation of functional group-doped carbon nitride: Add a certain mass of melamine into water, ultrasonically heat until completely dissolved to obtain solution I; add a certain mass of cyanuric acid into water, ultrasonically heat until completely dissolved to obtain solution II; dropwise add solution II into solution I in a boiling water bath, and continue heating and stirring, then wash with water to obtain precipitate I; carry out hydrothermal reaction on precipitate I and a certain volume of dopant in a hydrothermal reaction kettle, collect the obtained product after the reaction and freeze-dry to obtain precipitate II; calcine and react precipitate II in a nitrogen atmosphere to obtain functional group-doped carbon nitride. S2. Preparation of molybdenum disulfide: Weigh a certain mass of molybdenum trioxide and potassium thiocyanate, dissolve them in deionized water, stir to dissolve to obtain solution III; carry out hydrothermal reaction on solution III in a hydrothermal reaction kettle, collect the obtained product after the reaction and freeze-dry to obtain molybdenum disulfide. S3. Preparation of functional group-doped carbon nitride composite: Mix molybdenum disulfide and functional group-doped carbon nitride in a certain mass ratio in an ethanol solution, ultrasonically treat and mix evenly, then carry out magnetic stirring to achieve uniform dispersion, and obtain precipitate III after drying treatment; calcine and react precipitate III in a nitrogen atmosphere to obtain functional group-doped carbon nitride composite. S4. Preparation of alkali-modified biochar: Grind and sieve biomass, mix it with alkali in a certain mass ratio in an aqueous solution evenly and soak it, after drying, carry out calcination reaction in a nitrogen atmosphere to obtain an alkali-modified product, carry out post-treatment, and then dry to prepare alkali-modified biochar. S5. Preparation of biochar-based supported carbon nitride catalyst: Disperse alkali-modified biochar and functional group-doped carbon nitride composite in a certain mass ratio in water and mix to obtain precipitate IV, add a certain mass of support agent, binder, and pore-forming agent thereto, mix evenly and stir into a mud shape, and granulate with a spherical mold and polystyrene foam balls. Demold after freeze-setting, and dry at a certain temperature. Calcinate and react the dried material in a nitrogen atmosphere, and obtain a biochar-based supported carbon nitride catalyst after post-treatment.

2. The preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system according to claim 1, characterized in that, In the step S1, the molar ratio of melamine to cyanuric acid is 1:0.5 - 1.5; the ultrasonic time is 0.2 - 1.0 h, the ultrasonic frequency is 20 - 80 kHz; the heating temperature is 60 - 90 °C; for every 1 mol of melamine and cyanuric acid, 0.0 - 0.05 mol of dopant is added, and the dopant includes one or more of potassium thiocyanate, ammonium chloride, N,N-dimethylformamide, and N,N-dimethylacetamide; the hydrothermal reaction temperature is 120 - 200 °C, the hydrothermal reaction time is 4 - 10 h; the nitrogen flow rate is 2 - 5 mL / min, the calcination reaction temperature is 300 - 600 °C, the heating rate is 2 - 15 °C / min, and the calcination reaction time is 2 - 8 h.

3. The preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system according to claim 1, characterized in that, In the step S2, the molar ratio of molybdenum trioxide to potassium thiocyanate is 1:1 - 5; the hydrothermal reaction temperature is 180 - 220 °C, and the hydrothermal reaction time is 18 - 24 h.

4. The preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system according to claim 1, characterized in that, In the step S3, the mass ratio of molybdenum disulfide to functional group-doped carbon nitride is 1:10 - 15; the ultrasonic time is 0.2 - 0.5 h, and the ultrasonic frequency is 20 - 60 kHz; the drying temperature is 40 - 70 °C; the nitrogen flow rate is 2 - 5 mL / min, the calcination reaction temperature is 300 - 500 °C, the heating rate is 2 - 15 °C / min, and the calcination reaction time is 1 - 5 h.

5. The preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system according to claim 1, characterized in that, In the step S4, the biomass includes one or more of Enteromorpha prolifera, seaweed, straw, coconut shell, and wood chips, and the alkali includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate. The mass ratio of biomass to alkali is 1:1 - 6, and the soaking time is 4 - 12 h; the drying temperature is 40 - 90 °C; the nitrogen flow rate is 2 - 5 mL / min, the calcination reaction temperature is 400 - 800 °C, the heating rate is 2 - 15 °C / min, and the calcination reaction time is 1 - 5 h; the post-treatment includes acid leaching with 1 - 5 moL / L hydrochloric acid for 1 - 3 h, acid boiling at 80 - 100 °C for 1 - 3 h, alcohol washing 3 - 5 times, and water washing until the solution is neutral.

6. The preparation method of a catalyst based on an ozone photocatalytic oxidation coupling system according to claim 1, wherein, In the step S5, the mass ratio of alkali-modified biochar to functional group-doped carbon nitride composite is 4:1 - 4, and the mass ratio of the support agent, binder, pore-forming agent, and precipitate Ⅳ is 1 - 6:1 - 4:1 - 4:

1. The support agent includes one or more of diatomite, sepiolite, and zeolite, the binder includes one or more of epoxy resin, waterborne polyurethane, dextrin, cyclodextrin, and starch, and the pore-forming agent includes one or more of ammonium bicarbonate, sodium bicarbonate, and sodium carbonate; the mold is placed in the refrigerator for freezing and shaping for 1 - 3 h and then demolded; the demolded product is dried at 160 - 180 °C for 2 - 5 h; the nitrogen flow rate is 2 - 5 mL / min, the calcination reaction temperature is 300 - 500 °C, the heating rate is 2 - 15 °C / min, and the calcination reaction time is 1 - 5 h. The post-treatment includes acid leaching with 1 - 5 moL / L hydrochloric acid for 1 - 3 h, acid boiling at 80 - 100 °C for 1 - 3 h, alcohol washing 3 - 5 times, and water washing until the solution is neutral.

7. A catalyst and an integrated sewage treatment device based on an ozone photocatalytic oxidation coupling system for implementing the method according to claim 1, comprising a box body (1), a coagulation sedimentation chamber (2), a photo-ozone synergistic catalytic reaction chamber (3), and a central control chamber (4); The coagulation sedimentation chamber (2) includes a chemical dosing pump (21), a first water pump (22), a first water quality sensor (23), a stirrer (24), a sludge discharge valve (25), a second water pump (26), and a second water quality sensor (27); the chemical dosing pump (21) can be used to add one or more of calcium hydroxide, sodium hydroxide, aluminum hydroxide, potassium alum, and polyacrylamide; The photo-ozone synergistic catalytic reaction chamber (3) includes a precision aeration disk (31), a transparent lamp cover (32), a light source (33), a catalytic chamber partition (34), a third water quality sensor (35), and a solar collector (35). The solar collector (36) includes a Fresnel lens (361), a light guide tube (362), and a diffuser (363); the light source (33) includes one of a xenon lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, and a halogen lamp; below the catalytic chamber partition (34) is included the biochar-based supported carbon nitride catalyst as described in claim 1, and the diameter of the partition gap is smaller than the diameter of the catalyst; the solar collector (36) can be used to concentrate sunlight on sunny days to excite the catalyst, and on cloudy days and at night, the light source (33) provides the light source; The central control room (4) includes a solar panel (41), a control panel (42), a storage battery (43), an integrated air source ozone generator (44), and an exhaust gas treatment device (45); The dosing pump (21), the first water pump (22), the first water quality sensor (23), the stirrer (24), the second water pump (26), the second water quality sensor (27), the light source (33), the third water quality sensor (35), the storage battery (43), the integrated air source ozone generator (44), and the exhaust gas treatment device (45) are connected to the control panel (42). The control panel is built-in with a control system, a display system, and a network system. The solar panel (11) is connected to the storage battery (43), and can use sunlight to generate electricity to supply power to the equipment.

Images