Preparation method and application of CN (at) rGO / RCH high-efficiency catalyst

Abstract

The invention belongs to the technical field of composite materials, and relates to a preparation method of a red mud enhanced anaerobic digestion biogas residue charcoal loaded and coated reduced graphene oxide layer carbon nitride (CN (at) rGO / RCH) efficient catalyst, which comprises the following steps: fully stirring CN and GO, ultrasonically dispersing in deionized water, and carrying out hydrothermal reaction on a solid-liquid mixture at 160-200 DEG C for 12-24 hours to obtain CN (at) GO; the method comprises the following steps: fully mixing CN-coated GO and RCH, dispersing in deionized water, and carrying out oscillation ultrasonic treatment in a gas bath constant-temperature oscillation box; and centrifugally drying, heating to 700-900 DEG C in inert gas, pyrolyzing for 2-4 hours, and cooling to room temperature, thereby obtaining the product. The prepared catalyst is used for activating persulfate to degrade tetracycline in water. The preparation process is simple, controllable and environment-friendly, the red mud enhanced anaerobic digestion biogas residues are subjected to anaerobic high-temperature pyrolysis and hydrochloric acid modification, and then the carbon nitride coated with the reduced graphene oxide layer is loaded, so that the solid waste harmful to the environment generated by anaerobic digestion is recycled, and the purpose of rapidly degrading tetracycline in water is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials and relates to a biochar catalyst, and in particular to a preparation method and application of a high-efficiency catalyst of red mud enhanced anaerobic digestion sludge biochar loaded with reduced graphene oxide layer-coated carbon nitride (CN@rGO / RCH). Background Art

[0002] Red mud is bauxite slag produced during the refining of alumina, which is rich in metal minerals. Due to its toxicity, strong alkalinity, complex composition and high yield, it is considered a hazardous industrial waste. Using red mud to pretreat food waste can improve the biodegradability of food waste, while alleviating the acid inhibition problem during anaerobic digestion, thereby improving the performance and stability of the anaerobic digestion system. However, sludge mixed with red mud after anaerobic digestion has become a new type of solid hazardous waste, which may pose a more serious threat to the ecological environment. Therefore, the disposal of these new sludges needs to be solved urgently.

[0003] At present, antibiotics have been widely used in medicine and animal husbandry, not only to protect the health of humans and livestock, but also to be added to feed to promote the growth and development of livestock. Organisms can only effectively utilize 10% to 20% of antibiotics, and the remaining antibiotics enter the water environment through animal feces and other pathways, causing antibiotic pollution in water bodies. my country's use of antibiotics ranks among the highest in the world, and tetracycline (TC) is a broad-spectrum antibiotic with a basic tetracene skeleton, ranking first in production and usage. Tetracycline has the characteristics of long retention time and wide spread. It is very easy to enrich in water bodies and soil, which will pose a serious threat to the ecological environment and human health. Therefore, it is of great significance to seek economical, efficient and sustainable TC treatment methods and technologies.

[0004] Biochar prepared from biogas residues from red mud enhanced anaerobic digestion has the characteristics of developed pore structure, large specific surface area and rich functional groups. Biogas residue biochar prepared by simple pyrolysis shows excellent activation effect on persulfate and has good application potential. In particular, red mud as a metal source can further improve the performance of biochar.

[0005] Based on this, the present invention discloses a method for recycling and utilizing red mud enhanced anaerobic digestion residue with high added value, namely, preparing the residue into a new biochar catalyst through pyrolysis and hydrochloric acid modification, and then activating peroxydisulfate (PDS) to degrade TC, thereby realizing the environmentally friendly back-end treatment of red mud enhanced anaerobic digestion residue and the efficient degradation of TC in water. Summary of the invention

[0006] In view of the problem that the traditional disposal method of biogas residue from enhanced anaerobic digestion of red mud easily causes environmental pollution, the present invention discloses a method for preparing a CN@rGO / RCH high-efficiency catalyst.

[0007] Technical Solution

[0008] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0009] a) fully stirring carbon nitride (CN) and graphene oxide (GO) and ultrasonically dispersing them in deionized water, hydrothermally reacting the solid-liquid mixture at 160-200° C. for 12-24 h, preferably at 180° C. for 20 h, centrifugally drying the obtained solid to obtain graphene oxide-coated carbon nitride (CN@GO), wherein the material ratio of CN, GO and deionized water is 0.1-0.3 g: 0.02-0.1 g: 40-70 mL, preferably 0.1 g: 0.02 g: 50 mL;

[0010] b) The graphene oxide-coated carbon nitride (CN@GO) and the hydrochloric acid-modified red mud enhanced anaerobic digestion residue biochar (RCH) are fully mixed and dispersed in deionized water, placed in an air bath constant temperature oscillation box for oscillation for 1 to 3 hours and ultrasonicated for 0.5 to 1.5 hours, preferably oscillated for 3 hours and ultrasonicated for 1 hour, and the oscillation box temperature is 25±1°C, wherein the material ratio of CN@GO, RCH and deionized water is 0.02 to 0.1 g: 0.05 to

[0011] 0.2g:40~70mL, preferably 0.02~0.1g:0.1g:50mL;

[0012] c) After the mixture is centrifugally dried, it is heated to 700-900° C. in an inert gas for pyrolysis for 2-4 h, preferably 700° C. for 2 h, with a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0013] In a preferred embodiment of the present invention, in step a), the carbon nitride (CN) is prepared by a conventional method, for example, 7.5 g of urea is placed in a crucible, calcined at 520° C. for 4 h at a heating rate of 2° C. / min, and naturally cooled to room temperature.

[0014] According to a preferred embodiment of the present invention, in step a), the graphene oxide (GO) is a few-layer graphene oxide.

[0015] In a preferred disclosed example of the present invention, in step b), the particle size of the hydrochloric acid-modified red mud enhanced anaerobic digestion biochar (RCH) is 200-250 meshes, and the preparation method thereof is:

[0016] 1) adding 1-10% by mass of red mud, preferably 5%, to organic waste, setting the temperature to 35-55° C., and the SRT to 22-50 d, to perform high-solid anaerobic digestion, drying the biogas residue obtained after the anaerobic digestion reaction at 80° C. overnight, cooling to room temperature, and then grinding and sieving to obtain 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0017] 2) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 600-900° C. for 1-3 h, preferably at 700° C. for 2 h, with a heating rate of 5° C. / min, and cooling to room temperature to obtain red mud enhanced anaerobic digestion residue biochar powder (RC);

[0018] 3) The RC powder is soaked and shaken in 1.2-3.6 wt.% hydrochloric acid for 30-90 min, preferably in 1.8 wt.% hydrochloric acid for 30 min, with an oscillation rate of 200 rpm, the powder is collected, washed with deionized water until the pH of the filtrate is neutral, dried again, ground and sieved to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH).

[0019] In a preferred embodiment of the present invention, in step 1), the solid content of the high-solid anaerobic digestion system is 8-20%.

[0020] In a preferred embodiment of the present invention, in step 2), the inert gas is nitrogen.

[0021] In a preferred disclosed example of the present invention, in step 3), the concentration of the RC powder after being soaked in hydrochloric acid is 4 g / L.

[0022] In a preferred embodiment of the present invention, in step c), the inert gas is nitrogen.

[0023] The material prepared by the method of the present invention has sludge biochar as the base, and irregular particles formed by surface deposition of inorganic substances in red mud and sludge and flaky reduced graphene oxide-coated carbon nitride are unevenly distributed on the base, and the material as a whole presents a fluffy porous structure.

[0024] The present invention prepares biochar by strengthening anaerobic digestion of biogas residue raw materials through high-temperature pyrolysis of red mud in an anaerobic environment, and adopts hydrochloric acid impregnation activation method to effectively increase the specific surface area of ​​the material and efficiently elute the ash contained therein, and successfully loads reduced graphene oxide layer coated with carbon nitride to obtain CN@rGO / RCH high-efficiency catalyst.

[0025] Another object of the present invention is to apply the prepared CN@rGO / RCH high-efficiency catalyst to the degradation of antibiotics, especially to activate persulfate to degrade tetracycline (TC) in water.

[0026] The laboratory simulated persulfate oxidation test to remove TC from water, the steps are as follows:

[0027] At room temperature, a 100 mL conical flask was used as the reaction flask; 15 mg CN@rGO / RCH catalyst was added to TC solution (50 mL, 20 mg / L), and after adding peroxydisulfate (PDS), it was placed in an air bath constant temperature oscillating box and reacted at a speed of 200 rpm. During the reaction, 3 mL of the solution was taken at regular intervals, and the catalyst was filtered through a 0.22 μm filter membrane, and its absorbance was measured using a UV-1801 ultraviolet-visible spectrophotometer.

[0028] The TC removal rate is calculated according to the following formula:

[0029] R(%)=(1-C / C0)×100%=(1-A / A0)×100%

[0030] Where R, C, C0, A, and A0 represent the TC removal rate, TC concentration at the time of sampling, initial TC concentration, absorbance of the water sample at the time of sampling, and absorbance of the initial water sample, respectively.

[0031] The reagents used in the present invention are all commercially available analytically pure.

[0032] Beneficial Effects

[0033] The preparation process of the present invention is simple, controllable and environmentally friendly, and the catalyst / PDS system can achieve efficient degradation of TC in water. By subjecting the anaerobic digestion residue of red mud to anaerobic high-temperature pyrolysis and hydrochloric acid modification and then loading and coating the reduced graphene oxide layer with carbon nitride, the environmentally harmful solid waste generated by anaerobic digestion is recycled and reused, achieving the purpose of resource utilization of hazardous waste and rapid degradation of TC in water. The results of experimental simulation of catalytic oxidation of TC in water show that the catalyst / PDS system has a TC removal rate of about 90% in 20 minutes of reaction, providing reliable theoretical and practical support for practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 .Scanning electron microscope photo of CN@rGO / RCH prepared in Example 3 (left: magnification 20000×, right: magnification 10000×);

[0035] Figure 2 .Removal rate of tetracycline by catalyst / PDS system, where tetracycline solution concentration: 20 mg / L; tetracycline solution volume: 50 mL; PDS addition concentration: 0.5 mM. DETAILED DESCRIPTION

[0036] The present technology is described in detail below in conjunction with embodiments so that those skilled in the art can better understand the present technology, but the present technology is not limited to the following embodiments.

[0037] The red mud enhanced anaerobic digestion sludge used in the embodiment is obtained by adding 5% by mass red mud to organic waste, setting the temperature at 35-55°C, setting the SRT at 22-50d, and performing high-solid anaerobic digestion with a solid content of 10w.t.%, which is obtained after the anaerobic digestion reaction is completed.

[0038] Example 1

[0039] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0040] a) drying the biogas residue from anaerobic digestion with red mud in an oven at 80° C. overnight, cooling it to room temperature, and then grinding and sieving it to obtain a 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0041] b) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 700° C. for 2 h at a heating rate of 5° C. / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder;

[0042] c) 0.2 g of the powder obtained in step b) was placed in 50 mL of 1.8 wt.% hydrochloric acid and immersed in the solution and shaken for 30 min at a shaking speed of 200 rpm;

[0043] d) collecting the powder obtained in step c), washing the powder with deionized water for several times until the pH of the filtrate is neutral, and then drying it again, grinding and sieving it to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH);

[0044] e) placing 7.5 g of urea in several crucibles and calcining them at high temperature in a muffle furnace for 4 hours at a temperature of 520° C. and a heating rate of 2° C. / min, and cooling to obtain carbon nitride (CN);

[0045] f) 0.1 g CN and graphene oxide (GO) were mixed in a mass ratio of 1:0.2 in several 100 mL beakers with 50 mL of deionized water, stirred for 3 h and ultrasonicated for 1 h, and then the solid-liquid mixture was transferred to a 100 mL reactor for hydrothermal reaction at a temperature of 180 ° C and a hydrothermal time of 20 h. After the hydrothermal reaction, the obtained solid was centrifuged and dried to obtain graphene oxide-coated carbon nitride (CN@GO);

[0046] g) CN@GO obtained in step f) and RCH obtained in step d) were mixed in a mass ratio of 0.2:1 in several 150 mL conical flasks to which 50 mL of deionized water was added, and then the conical flasks were placed in an air bath constant temperature oscillating box for 3 h and ultrasonicated for 1 h, the oscillating box temperature was 25±1° C., and the rotation speed was 200 rpm;

[0047] h) The mixture obtained in step g) is centrifugally dried, pyrolyzed at 700° C. for 2 h in an inert gas at a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0048] The removal rate of tetracycline by the high-efficiency catalyst prepared in Example 1, CN@rGO / RCH / PDS system, is as follows: Figure 2 As shown, when the dosage of biochar catalyst is 0.3 g / L and the dosage of PDS is 0.5 mM, the removal rate of tetracycline can reach about 90% on average.

[0049] Example 2

[0050] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0051] a) drying the biogas residue from anaerobic digestion with red mud in an oven at 80° C. overnight, cooling it to room temperature, and then grinding and sieving it to obtain a 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0052] b) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 700° C. for 2 h at a heating rate of 5° C. / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder;

[0053] c) 0.2 g of the powder obtained in step b) was placed in 50 mL of 1.8 wt.% hydrochloric acid and immersed in the solution and shaken for 30 min at a shaking speed of 200 rpm;

[0054] d) collecting the powder obtained in step c), washing the powder with deionized water for several times until the pH of the filtrate is neutral, and then drying it again, grinding and sieving it to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH);

[0055] e) placing 7.5 g of urea in several crucibles and calcining them at high temperature in a muffle furnace for 4 hours at a temperature of 520° C. and a heating rate of 2° C. / min, and cooling to obtain carbon nitride (CN);

[0056] f) 0.1 g CN and graphene oxide (GO) were mixed in a mass ratio of 1:0.2 in several 100 mL beakers with 50 mL of deionized water, stirred for 3 h and ultrasonicated for 1 h, and then the solid-liquid mixture was transferred to a 100 mL reactor for hydrothermal reaction at a temperature of 180 ° C and a hydrothermal time of 20 h. After the hydrothermal reaction, the obtained solid was centrifuged and dried to obtain graphene oxide-coated carbon nitride (CN@GO);

[0057] g) CN@GO obtained in step f) and RCH obtained in step d) were mixed in a mass ratio of 0.5:1 in several 150 mL conical flasks to which 50 mL of deionized water was added, and then the conical flasks were placed in an air bath constant temperature oscillating box for 3 h and ultrasonicated for 1 h, the oscillating box temperature was 25±1° C., and the rotation speed was 200 rpm;

[0058] h) The mixture obtained in step g) is centrifugally dried, pyrolyzed at 700° C. for 2 h in an inert gas at a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0059] The removal rate of tetracycline by the high-efficiency catalyst prepared in Example 2, CN@rGO / RCH / PDS system, is as follows: Figure 2 As shown, when the biochar catalyst dosage is 0.3 g / L and the PDS dosage is 0.5 mM, the removal rate of tetracycline can reach an average of more than 85%.

[0060] Example 3

[0061] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0062] a) drying the biogas residue from anaerobic digestion with red mud in an oven at 80° C. overnight, cooling it to room temperature, and then grinding and sieving it to obtain a 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0063] b) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 700° C. for 2 h with a heating rate of 5° C. / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder;

[0064] c) 0.2 g of the powder obtained in step b) was placed in 50 mL of 1.8 wt.% hydrochloric acid and immersed in the solution and shaken for 30 min at a shaking speed of 200 rpm;

[0065] d) collecting the powder obtained in step c), washing the powder with deionized water for several times until the pH of the filtrate is neutral, and then drying it again, grinding and sieving it to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH);

[0066] e) placing 7.5 g of urea in several crucibles and calcining them at high temperature in a muffle furnace for 4 hours at a temperature of 520° C. and a heating rate of 2° C. / min, and cooling to obtain carbon nitride (CN);

[0067] f) 0.1 g CN and graphene oxide (GO) were mixed in a mass ratio of 1:0.2 in several 100 mL beakers with 50 mL of deionized water, stirred for 3 h and ultrasonicated for 1 h, and then the solid-liquid mixture was transferred to a 100 mL reactor for hydrothermal reaction at a temperature of 180 ° C and a hydrothermal time of 20 h. After the hydrothermal reaction, the obtained solid was centrifuged and dried to obtain graphene oxide-coated carbon nitride (CN@GO);

[0068] g) CN@GO obtained in step f) and RCH obtained in step d) were mixed in a mass ratio of 1:1 in several 150 mL conical flasks to which 50 mL of deionized water was added, and then the conical flasks were placed in an air bath constant temperature oscillating box for 3 h and ultrasonicated for 1 h, the oscillating box temperature was 25±1° C., and the rotation speed was 200 rpm;

[0069] h) The mixture obtained in step g) is centrifugally dried, pyrolyzed at 700° C. for 2 h in an inert gas at a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0070] The removal rate of tetracycline by the high-efficiency catalyst prepared in Example 3, CN@rGO / RCH / PDS system, is as follows: Figure 2 As shown, when the dosage of biochar catalyst is 0.3 g / L and the dosage of PDS is 0.5 mM, the removal rate of tetracycline can reach about 90% on average.

[0071] As attached Figure 1 As shown, inorganic substances from red mud and sludge form irregular particles through surface deposition, which increases the roughness of the biochar surface. At the same time, the carbon nitride coated with flaky reduced graphene oxide is tightly combined with the biochar substrate, and the catalyst as a whole has a fluffy porous structure.

[0072] Example 4

[0073] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0074] a) drying the biogas residue from anaerobic digestion with red mud in an oven at 80° C. overnight, cooling it to room temperature, and then grinding and sieving it to obtain a 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0075] b) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 700° C. for 2 h at a heating rate of 5° C. / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder;

[0076] c) 0.2 g of the powder obtained in step b) was placed in 50 mL of 1.8 wt.% hydrochloric acid and immersed in the solution and shaken for 30 min at a shaking speed of 200 rpm;

[0077] d) collecting the powder obtained in step c), washing the powder with deionized water for several times until the pH of the filtrate is neutral, and then drying it again, grinding and sieving it to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH);

[0078] e) placing 7.5 g of urea in several crucibles and calcining them at high temperature in a muffle furnace for 4 hours at a temperature of 520° C. and a heating rate of 2° C. / min, and cooling to obtain carbon nitride (CN);

[0079] f) 0.1 g CN and graphene oxide (GO) were mixed in a mass ratio of 1:0.5 in several 100 mL beakers with 50 mL of deionized water, stirred for 3 h and ultrasonicated for 1 h, and then the solid-liquid mixture was transferred to a 100 mL reactor for hydrothermal reaction at a temperature of 180 ° C and a hydrothermal time of 20 h. After the hydrothermal reaction, the obtained solid was centrifuged and dried to obtain graphene oxide-coated carbon nitride (CN@GO);

[0080] g) CN@GO obtained in step f) and RCH obtained in step d) were mixed in a mass ratio of 0.2:1 in several 150 mL conical flasks to which 50 mL of deionized water was added, and then the conical flasks were placed in an air bath constant temperature oscillating box for 3 h and ultrasonicated for 1 h, the oscillating box temperature was 25±1° C., and the rotation speed was 200 rpm;

[0081] h) The mixture obtained in step g) is centrifugally dried, pyrolyzed at 700° C. for 2 h in an inert gas at a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0082] The removal rate of tetracycline by the high-efficiency catalyst prepared in Example 4, CN@rGO / RCH / PDS system, is as follows: Figure 2 As shown, when the dosage of biochar catalyst is 0.3 g / L and the dosage of PDS is 0.5 mM, the removal rate of tetracycline can reach about 90% on average.

[0083] Example 5

[0084] A method for preparing a CN@rGO / RCH high-efficiency catalyst comprises the following steps:

[0085] a) drying the biogas residue from anaerobic digestion with red mud in an oven at 80° C. overnight, cooling it to room temperature, and then grinding and sieving it to obtain a 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder;

[0086] b) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 700° C. for 2 h with a heating rate of 5° C. / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder;

[0087] c) 0.2 g of the powder obtained in step b) was placed in 50 mL of 1.8 wt.% hydrochloric acid and immersed in the solution and shaken for 30 min at a shaking speed of 200 rpm;

[0088] d) collecting the powder obtained in step c), washing the powder with deionized water for several times until the pH of the filtrate is neutral, and then drying it again, grinding and sieving it to obtain 200-250 mesh hydrochloric acid modified red mud enhanced anaerobic digestion residue biochar (RCH);

[0089] e) placing 7.5 g of urea in several crucibles and calcining them at high temperature in a muffle furnace for 4 hours at a temperature of 520° C. and a heating rate of 2° C. / min, and cooling to obtain carbon nitride (CN);

[0090] f) 0.1 g CN and graphene oxide (GO) were mixed in a mass ratio of 1:1 in several 100 mL beakers with 50 mL deionized water, stirred for 3 h and ultrasonicated for 1 h, and then the solid-liquid mixture was transferred to a 100 mL reactor for hydrothermal reaction at a temperature of 180 ° C and a hydrothermal time of 20 h. After the hydrothermal reaction, the obtained solid was centrifuged and dried to obtain graphene oxide-coated carbon nitride (CN@GO);

[0091] g) CN@GO obtained in step f) and RCH obtained in step d) were mixed in a mass ratio of 0.2:1 in several 150 mL conical flasks to which 50 mL of deionized water was added, and then the conical flasks were placed in an air bath constant temperature oscillating box for 3 h and ultrasonicated for 1 h, the oscillating box temperature was 25±1° C., and the rotation speed was 200 rpm;

[0092] h) The mixture obtained in step g) is centrifugally dried, pyrolyzed at 700° C. for 2 h in an inert gas at a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

[0093] The removal rate of tetracycline by the highly efficient catalyst prepared in Example 5, CN@rGO / RCH / PDS system, is as follows: Figure 2 As shown, when the dosage of biochar catalyst is 0.3 g / L and the dosage of PDS is 0.5 mM, the removal rate of tetracycline can reach an average of more than 90%.

[0094] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a CN@rGO / RCH high-efficiency catalyst, characterized in that: The steps include: a) fully stirring carbon nitride CN and graphene oxide GO, ultrasonically dispersing them in deionized water, hydrothermally reacting the solid-liquid mixture at 160-200° C. for 12-24 h, centrifugally drying the obtained solid, and obtaining graphene oxide-coated carbon nitride CN@GO, wherein the material ratio of CN, GO and deionized water is 0.1-0.3 g: 0.02-0.1 g: 40-70 mL; b) CN@GO and RCH, a biochar obtained by anaerobic digestion of red mud modified with hydrochloric acid, are fully mixed and dispersed in deionized water, and placed in an air bath constant temperature oscillating box for 1 to 3 hours and ultrasonicated for 0.5 to 1.5 hours. The temperature of the oscillating box is 25±1°C, wherein the material ratio of CN@GO, RCH and deionized water is 0.02 to 0.1 g: 0.05 to 0.2 g: 40 to 70 mL, preferably 0.02 to 0.1 g: 0.1 g: 50 mL; c) After the mixture is centrifugally dried, it is heated to 700-900° C. in an inert gas for pyrolysis for 2-4 h, preferably 700° C. for 2 h, with a heating rate of 5° C. / min, and cooled to room temperature to obtain CN@rGO / RCH.

2. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 1, characterized in that: In step a), the solid-liquid mixture is hydrothermally reacted at 180° C. for 20 h.

3. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 1, characterized in that: In step a), the material ratio of CN, GO and deionized water is 0.1 g:0.02 g:50 mL.

4. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 1, characterized in that: In step b), the hydrochloric acid-modified red mud enhanced anaerobic digestion biochar RCH has a particle size of 200-250 meshes, and the preparation method thereof is as follows: 1) adding 1-10% by mass of red mud to organic waste, setting the temperature to 35-55° C., setting the SRT to 22-50 d, and performing high-solid anaerobic digestion. The biogas residue obtained after the anaerobic digestion reaction is dried at 80° C. overnight, cooled to room temperature, and then ground and sieved to obtain 200-250 mesh red mud enhanced anaerobic digestion biogas residue powder; 2) placing the red mud enhanced anaerobic digestion residue powder in an inert gas at 600-900°C for 1-3h at a heating rate of 5°C / min, and cooling to room temperature to obtain the red mud enhanced anaerobic digestion residue biochar powder RC; 3) The RC powder is placed in 1.2-3.6wt.% hydrochloric acid and immersed in an oscillation for 30-90min at an oscillation rate of 200rpm, the powder is collected, washed with deionized water until the pH of the filtrate is neutral, dried again, and ground and sieved to obtain 200-250 mesh hydrochloric acid-modified red mud enhanced anaerobic digestion residue biochar RCH.

5. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 4, characterized in that: In step 1), 5% by mass of red mud is added to the organic waste.

6. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 4, characterized in that: In step 2), the red mud enhanced anaerobic digestion residue powder is placed in an inert gas and pyrolyzed at 700° C. for 2 h.

7. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 4, characterized in that: In step 3), the RC powder was immersed in 1.8 wt. % hydrochloric acid and shaken for 30 min.

8. The method for preparing the CN@rGO / RCH high-efficiency catalyst according to claim 1, characterized in that: In step b), CN@GO and the hydrochloric acid-modified red mud enhanced anaerobic digestion residue biochar RCH are fully mixed and dispersed in deionized water, and placed in an air bath constant temperature oscillation box for oscillation for 3 hours and ultrasonication for 1 hour.

9. The CN@rGO / RCH high efficiency catalyst prepared according to any one of claims 1 to 8, characterized in that: The catalyst uses biochar from sludge as a substrate, and irregular particles formed by surface deposition of inorganic substances in red mud and sludge and carbon nitride coated with flaky reduced graphene oxide are unevenly distributed on the substrate, and the material as a whole presents a fluffy porous structure.

10. An application of the CN@rGO / RCH high-efficiency catalyst as claimed in claim 9, characterized in that: The catalyst is applied to degrading antibiotics, especially activating persulfate to degrade tetracycline in water.

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