Diatomite modified biochar catalyst as well as preparation method and application thereof

Abstract

The invention discloses a diatomite modified biochar catalyst and a preparation method and application thereof, and belongs to the technical field of sewage treatment.The method comprises the steps that persimmon branches are smashed, ground and sieved to obtain persimmon branch powder, the persimmon branch powder, diatomite and phosphate are mixed and stirred for the first time, and modified biochar is obtained after calcination; and carrying out secondary mixing and stirring on the diatomite and urea, and drying to obtain the diatomite modified biochar catalyst. According to the method, the high adsorption performance of the kieselguhr and the rich functional groups and the surface area of the persimmon branch biochar are combined, sulfate free radicals with strong oxidizing property are generated by activating persulfate, efficient degradation of methyl orange dye is achieved, and the method has the advantages of being excellent in pollutant degradation capacity, efficient, environmentally friendly, simple in preparation and low in cost. The method is expected to become an effective means for sewage treatment and treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and particularly relates to a diatomite-modified biochar catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous development of industrialization, many non-degradable pollutants have been discharged into water bodies. As an indispensable resource for humans, once water resources are polluted by organic substances, it will not only have a great adverse impact on the water environment, but also pose a great harm to the human body. And because the organic substances existing in water bodies are difficult to dissipate and degrade, and their existence forms are relatively complex, how to efficiently and environmentally solve the pollutants in water bodies has become a major problem.

[0003] In the physical method, the membrane filtration method has the problems that the membrane is easily contaminated, resulting in a decline in its performance, and the operation and maintenance costs of membrane separation are high; a large amount of sludge produced by the coagulation method is difficult to treat, and the removal effect of hydrophilic dyes is poor; although the adsorption method can efficiently remove methyl orange, it only transfers methyl orange to the adsorbent and cannot completely degrade and remove it, and the subsequent treatment of the adsorbent is also a complex problem; the biological method mainly decomposes methyl orange in water into components of organisms through the metabolic process of microorganisms and finally converts it into harmless substances. The microbial method for repairing dye-containing wastewater is cost-effective and environmentally friendly, with the advantages of being clean and cheap, but the microbial reproduction speed and reaction speed of the biological method are relatively slow, the reaction management operation is relatively complex and the cycle is long, and it is easily affected by environmental factors; compared with the physical and biological methods, the chemical method has the advantages of fast reaction, wide application range, high efficiency and convenience, and has attracted much attention from scholars. In the process of sewage treatment, the advanced oxidation method shows good results. Among them, the persulfate advanced oxidation method has the characteristics of fast reaction speed, strong oxidizing property, good controllability, low operation cost, wide application range, and little secondary pollution. However, the traditional catalysts used for activation and catalysis have disadvantages such as high production cost, complex production process, easy secondary pollution, and great influence by pH or water quality. And biochar, as an economical and easily available carbon-containing material, has become a research hotspot. However, pure biochar often has disadvantages such as low catalytic efficiency, poor material stability, and difficulty in recycling. Therefore, studying how to modify biochar to improve the performance of activating persulfate has become the key.

[0004] In view of the deficiencies in the current methods for treating water pollutants, such as the easy fouling and high cost of membranes in the physical method, the difficult treatment of sludge and poor removal effect of hydrophilic dyes in the coagulation method, the incomplete degradation and complex subsequent treatment of adsorbents in the adsorption method, the slow reaction, complex management and operation, long cycle, and susceptibility to environmental factors in the biological method, and the various drawbacks of catalysts in the traditional persulfate advanced oxidation method, as well as the low catalytic efficiency, poor stability, and difficult recovery of pure biochar, there is an urgent need to find a new diatomite-modified biochar catalyst and its preparation method and application to effectively degrade pollutants in water bodies. Summary of the Invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a diatomite-modified biochar catalyst and its preparation method and application to solve the technical problems existing in the existing water pollutant treatment methods, such as high cost, poor treatment effect, slow reaction, susceptibility to the environment, poor catalytic performance, and difficult recovery. By modifying diatomite, the adsorption performance and catalytic activity of persimmon tree branch biochar are improved, and combined with the strong oxidation ability of persulfate, the effective degradation of pollutants in water bodies is realized.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention discloses a preparation method of a diatomite-modified biochar catalyst, including: After crushing, grinding, and sieving persimmon tree branches, persimmon tree branch powder is obtained, which is mixed and stirred with diatomite and phosphate for the first time. After calcination, modified biochar is obtained, and then it is mixed and stirred with urea for the second time. After drying, a diatomite-modified biochar catalyst is obtained.

[0007] Preferably, the mass ratio of persimmon tree branch powder, diatomite, and phosphate is (5 - 15):1:1; the phosphate is triple superphosphate.

[0008] Preferably, the time for the first mixing and stirring is 2 - 5 h; the heating rate of calcination is 10 °C / min; the temperature of calcination is 750 - 950 °C; the time of calcination is 75 - 95 min.

[0009] Preferably, the mass ratio of modified biochar to urea is 4:1.

[0010] Preferably, the time for the second mixing and stirring is 3 - 5 h.

[0011] The present invention also discloses a diatomite-modified biochar catalyst prepared by the above-mentioned preparation method of the diatomite-modified biochar catalyst.

[0012] The present invention also discloses the application of the diatomite-modified biochar catalyst prepared by the above preparation method in catalytically degrading water pollutants by persulfate. By adding the diatomite-modified biochar catalyst and persulfate to the simulated wastewater, and after oscillating reaction, the pollutants in the water are degraded.

[0013] Preferably, in every 100 ml of methyl orange polluted solution with a concentration of 20 mg / L, 0.02 - 0.1 g of diatomite-modified biochar catalyst and 0.3 - 0.8 mM of persulfate solution are added.

[0014] Preferably, the simulated wastewater is a methyl orange solution, and the concentration of the methyl orange solution is not more than 50 mg / L; the persulfate is at least one of potassium monopersulfate, sodium monopersulfate, potassium persulfate and sodium persulfate.

[0015] Preferably, the time of the oscillating reaction is 30 - 60 min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a preparation method of a diatomite-modified biochar catalyst. By combining diatomite with agricultural waste persimmon tree branches biochar, and utilizing the rich pore structure of diatomite and the large specific surface area of biochar, the specific surface area of the modified material and the metal active sites on the material surface are increased, and the adsorption capacity and catalytic performance of the biochar are improved. The raw materials required by this method are widely sourced. Persimmon tree branches, as agricultural waste, are low-cost and easy to obtain; diatomite is also a common natural inorganic material, and the preparation process is simple; there is no need for complex equipment and high-difficulty operation techniques, which greatly reduces the production cost and preparation difficulty, and is conducive to realizing large-scale industrial production. And compared with adsorption treatment, activating persulfate to degrade pollutants can make them completely degraded and removed. Diatomite has stable properties, is a natural inorganic material, has high thermal stability and chemical stability, can be stored for a long time, and is convenient for recycling; and no secondary pollution will be caused during this process, which is safe and environmentally friendly. The present invention uses diatomite-modified biochar, which can be combined with the persulfate advanced oxidation technology to play the synergistic effect between the two, providing an efficient and environmentally friendly treatment means.

[0017] The present invention also discloses a diatomite-modified biochar catalyst obtained by the above-mentioned preparation method. The catalyst exhibits excellent performance in catalytic reactions due to its large specific surface area and abundant metal active sites. It can react quickly and efficiently with oxidants such as persulfate, accelerate the degradation process of pollutants, greatly shorten the processing time, and improve the processing efficiency. Diatomite, as a natural inorganic material, has high thermal and chemical stability. This allows the modified biochar catalyst to maintain stable performance under various complex environmental conditions, is not prone to deterioration or failure, can effectively exert catalytic effects for a long time, and extend the service life of the catalyst. The stability and structural characteristics of the catalyst make it easy to recycle. After the catalytic reaction is completed, it can be recovered from the reaction system by a simple separation method and put into use again after appropriate treatment, thereby reducing the cost of the catalyst and improving resource utilization. No harmful byproducts are produced during use, and no secondary pollution is caused to the environment. It can effectively and completely degrade and remove pollutants in water bodies, achieving truly green and environmentally friendly management and meeting the requirements of sustainable development.

[0018] The present invention also discloses the use of a diatomite-modified biochar catalyst prepared by the above-mentioned preparation method in catalyzing the degradation of water pollutants with persulfate. By combining the high adsorption properties of diatomite with the rich functional groups and surface area of persimmon branch biochar, the catalyst activates persulfate to produce highly oxidizing sulfate radicals, achieving efficient degradation of methyl orange dye. During the catalytic process, the catalyst activates persulfate to produce highly oxidizing free radicals, which rapidly react with pollutants in the water, completely decomposing them into harmless substances, thereby achieving efficient degradation and removal of pollutants. It has a good degradation effect on various types of water pollutants, including organic pollutants and heavy metal ions. Whether it is industrial wastewater, domestic sewage, or agricultural non-point source pollution, this catalytic persulfate degradation technology can be used to treat water bodies, showing broad application prospects. Because the preparation method uses a wide range of raw materials, is inexpensive, and the catalyst is easily recyclable, the overall cost of catalytic persulfate degradation of water pollutants is relatively low. Compared with traditional physical and chemical treatment methods, this method has significant economic advantages and can provide a more economical solution for water pollution control. In practical applications, parameters such as catalyst dosage, persulfate concentration, and reaction conditions can be flexibly adjusted to achieve optimal treatment results based on varying water pollution levels and treatment requirements. This simple and flexible operation facilitates the promotion and application of this technology in practical projects. With its excellent pollutant degradation capabilities, high efficiency, environmental protection, and simple preparation, it is expected to become an effective means of wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1Graph showing the variation of the concentration ratio of the diatomite-modified biochar catalyst disclosed in Example 1-3 of the present invention and the pure persimmon tree branch biochar catalyst disclosed in Comparative Example 1 for the catalytic degradation of methyl orange wastewater with time; Figure 2 Graph showing the variation of the concentration ratio of the diatomite-modified biochar catalyst disclosed in Examples 2, 4 and 5 of the present invention at different calcination temperatures for the catalytic degradation of methyl orange wastewater with time; Figure 3 Graph showing the variation of the concentration ratio of the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention at different dosages (20mg, 40mg, 60mg, 80mg and 100mg) for the catalytic degradation of methyl orange wastewater with time; Figure 4 Graph showing the variation of the concentration ratio of the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention at different persulfate dosages (0.3mM, 0.4mM, 0.5mM, 0.6mM, 0.7mM and 0.8mM) for the catalytic degradation of methyl orange wastewater with time. Detailed implementation manners

[0020] The technical solutions of the present invention will be described clearly and completely below. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0021] In the present invention, if there is no special description, all the implementation manners and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0022] In the present invention, if there is no special description, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0023] In the present invention, if there is no special description, the percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0024] In the present invention, if there is no special description, the various components or their preferred components involved can be combined with each other to form a new technical solution.

[0025] In the present invention, unless otherwise stated, the numerical range "a~b" represents the abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been fully listed herein, and "6~22" is only the abbreviated representation of these numerical combinations.

[0026] The "range" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits respectively.

[0027] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the order. Preferably, the reaction method herein is carried out sequentially.

[0029] Unless otherwise indicated, the professional and scientific terms used herein are the same as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described content can also be applied to the present invention.

[0030] The present invention provides a method for preparing a diatomite-modified biochar catalyst, comprising the following steps: The persimmon branches are crushed, ground and sieved to obtain persimmon branch powder, which is then mixed with diatomaceous earth and phosphate in a mass ratio of (5-15):1:1, stirred in a magnetic stirrer for 2-5 hours, filtered, and then placed in a tubular furnace and heated to 750-950°C at 10°C / min for calcination and pyrolysis for 75-95 minutes to obtain modified biochar. The modified biochar is then mixed with urea in a mass ratio of 4:1 and stirred for 3-5 hours. After drying, a diatomaceous earth modified biochar catalyst can be obtained.

[0031] Among them, the phosphate is double superphosphate; the diatomaceous earth modified biochar catalyst is obtained by combustion and oxygen-limited cracking carbonization technology.

[0032] The present invention also provides an application of the above-mentioned diatomaceous earth modified biochar catalyst in catalyzing the degradation of pollutants in water by persulfate, comprising: adding the diatomaceous earth modified biochar catalyst and persulfate to simulated wastewater to obtain a mixed solution, and degrading the pollutants in the water after a shaking reaction.

[0033] The simulated wastewater is methyl orange-contaminated liquid. The methyl orange-contaminated liquid is diluted in a 100 ml conical flask and placed in a constant temperature shaking box for 3-8 minutes. The methyl orange concentration is not greater than 50 mg / L. For every 100 ml of methyl orange-contaminated liquid with a concentration of 20 mg / L, 0.02-0.1 g of diatomaceous earth-modified biochar catalyst and 0.3-0.8 mM persulfate solution are added. The persulfate is at least one of potassium peroxymonosulfate, sodium peroxymonosulfate, potassium peroxydisulfate, and sodium peroxydisulfate.

[0034] The mixed solution was placed in a constant temperature shaking box for 30-60 min.

[0035] The present invention combines the high adsorption performance of diatomite, the rich functional groups and surface area of persimmon tree branch biochar to generate strongly oxidizing sulfate radicals by activating persulfate, achieving the efficient degradation of methyl orange dye. The method proposed by the present invention has excellent pollutant degradation ability, high efficiency, environmental protection and simple preparation, and is expected to become an effective means for sewage treatment.

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components in the drawings and described in the embodiments of the present invention here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0037] The present invention combines branch biochar and diatomite to prepare a diatomite-modified biochar catalyst, and uses this diatomite-modified biochar catalyst to catalyze persulfate to completely degrade methyl orange in pollutants, effectively reducing secondary pollution. All raw materials used are commercially available products.

[0038] Example 1 A preparation method of a diatomite-modified biochar catalyst includes: Mix the treated persimmon tree branch powder, triple superphosphate and diatomite in a mass ratio of 5:1:1, place them on a magnetic stirrer and stir for 2 h, then filter and put them into a tube furnace, heat up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 7'5 min to obtain modified biochar, and then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomite-modified biochar can be obtained.

[0039] Add 0.04 g of the diatomite-modified biochar catalyst and 0.5 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 min, the pollutants in the water are degraded.

[0040] Example 2 A preparation method of a diatomite-modified biochar catalyst includes: Mix the processed persimmon tree branch powder, triple superphosphate and diatomite in a ratio of 10:1:1, place them on a magnetic stirrer and stir for 2 h. After suction filtration, put them into a tube furnace and heat up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 min to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomite-modified biochar can be obtained.

[0041] Add 0.04 g of the diatomite-modified biochar catalyst and 0.5 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 min, the pollutants in the water are degraded.

[0042] Example 3 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate and diatomite in a ratio of 15:1:1, place them on a magnetic stirrer and stir for 2 h. After suction filtration, put them into a tube furnace and heat up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 min to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomite-modified biochar can be obtained.

[0043] Add 0.04 g of the diatomite-modified biochar catalyst and 0.5 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 min, the pollutants in the water are degraded.

[0044] Example 4 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate and diatomite in a ratio of 10:1:1, place them on a magnetic stirrer and stir for 2 h. After suction filtration, put them into a tube furnace and heat up to 850 °C at a rate of 10 °C / min for pyrolysis treatment for 85 min to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomite-modified biochar can be obtained.

[0045] Add 0.04 g of the diatomite-modified biochar catalyst and 0.5 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 min, the pollutants in the water are degraded.

[0046] Example 5 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate, and diatomite in a ratio of 10:1:1, place the mixture on a magnetic stirrer and stir for 2 hours. After suction filtration, put it into a tube furnace and heat it up to 950 °C at a rate of 10 °C / min for pyrolysis treatment for 95 minutes to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 hours. After drying, the final diatomite-modified biochar can be obtained.

[0047] Add 0.04 g of diatomite-modified biochar catalyst and 0.5 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 minutes, the pollutants in the water are degraded.

[0048] Example 6 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate, and diatomite in a mass ratio of 5:1:1, place the mixture on a magnetic stirrer and stir for 3 hours. After suction filtration, put it into a tube furnace and heat it up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 minutes to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 3 hours. After drying, the final diatomite-modified biochar can be obtained.

[0049] Add 0.02 g of diatomite-modified biochar catalyst and 0.3 mM of potassium monopersulfate to 100 ml of methyl orange polluted solution with a concentration of 30 mg / L to obtain a mixed solution. After shaking and reacting for 30 minutes, the pollutants in the water are degraded.

[0050] Example 7 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate, and diatomite in a mass ratio of 5:1:1, place the mixture on a magnetic stirrer and stir for 4 hours. After suction filtration, put it into a tube furnace and heat it up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 minutes to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 4 hours. After drying, the final diatomite-modified biochar can be obtained.

[0051] Add 0.05 g of diatomite-modified biochar catalyst and 0.6 mM of sodium monopersulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 40 minutes, the pollutants in the water are degraded.

[0052] Example 8 A preparation method of a diatomite-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate, and diatomaceous earth in a mass ratio of 5:1:1, place them on a magnetic stirrer and stir for 5 h. After suction filtration, put them into a tube furnace and heat up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 min to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomaceous earth-modified biochar can be obtained.

[0053] Add 0.08 g of diatomaceous earth-modified biochar catalyst and 0.7 mM of potassium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 50 min, the pollutants in the water are degraded.

[0054] Example 9 A preparation method of a diatomaceous earth-modified biochar catalyst, comprising: Mix the processed persimmon tree branch powder, triple superphosphate, and diatomaceous earth in a mass ratio of 5:1:1, place them on a magnetic stirrer and stir for 2 h. After suction filtration, put them into a tube furnace and heat up to 750 °C at a rate of 10 °C / min for pyrolysis treatment for 75 min to obtain modified biochar. Then mix it with urea in a mass ratio of 4:1 and stir for 5 h. After drying, the final diatomaceous earth-modified biochar can be obtained.

[0055] Add 0.1 g of diatomaceous earth-modified biochar catalyst, 0.4 mM of potassium persulfate, and 0.4 mM of sodium persulfate to 100 ml of methyl orange polluted solution with a concentration of 20 mg / L to obtain a mixed solution. After shaking and reacting for 60 min, the pollutants in the water are degraded.

[0056] Comparative Example 1 A preparation method of pure persimmon tree branch biochar BC, comprising: Grind the dried persimmon tree branches into powder, pour them into a quartz boat and place it in a high-temperature tube furnace, heat up to 750 °C at a rate of 10 °C / min for calcination for 75 min, and wait for it to cool naturally to obtain pure persimmon tree branch biochar BC.

[0057] Figure 1Figure showing the variation of the concentration ratio of the diatomite-modified biochar catalyst disclosed in Examples 1-3 of the present invention and the pure persimmon tree branch biochar disclosed in Comparative Example 1 for the catalytic degradation of methyl orange wastewater with time; Table 1 shows the comparison of the degradation rates of the diatomite-modified biochar catalyst disclosed in Examples 1-3 of the present invention and the pure persimmon tree branch biochar disclosed in Comparative Example 1 for the catalytic degradation of methyl orange wastewater. It can be seen that the diatomite-modified biochar catalyst disclosed in Examples 1-3 has better degradation performance for methyl orange, and the degradation rate is 60%-70%, indicating that the modification of diatomite improves the catalytic degradation ability of the biochar material. This may be because the doping of diatomite provides more active sites, thereby improving the catalytic performance.

[0058] The specific method for calculating the degradation rate test is as follows: Dissolve 0.05 g of methyl orange in a 500 ml volumetric flask, and make up to 500 mL with ultrapure water. Then dilute the solution concentrations to 4, 8, 12, 16, and 20 mg / L respectively. Measure the absorbance of all samples at the maximum absorption wavelength of methyl orange using ultraviolet light, and then use the basic law of spectrophotometry, the Beer-Lambert Law, to obtain the concentration-absorbance standard curve of methyl orange. This curve shows a good linear relationship and a linear equation (Equations 1-2) can be obtained. The concentration can be analyzed by measuring the change in absorbance through Formula 1-1, the pollutant concentration can be calculated through 1-2, and finally the degradation rate can be calculated through Formula 1-3: (1-1) Where: A is the absorbance, T is the transmittance, c is the concentration of the absorbing substance, mg / L. K is the molar absorption coefficient, and b is the thickness of the absorption layer, cm.

[0059] Working curve: (1-2) Where: A is the absorbance, C is the pollutant concentration, mg / L, and B is a constant (1-3) Where: D is the degradation rate, / %; C is the pollutant concentration, mg / L; C 0 is the initial concentration of the pollutant, mg / L.

[0060] Figure 2It is a graph showing the variation of the concentration ratio of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Examples 2, 4, and 5 of the present invention at different calcination temperatures with time; Table 2 is a comparison of the degradation rates of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Examples 2, 4, and 5 of the present invention at different calcination temperatures. It can be seen that temperature has a certain influence on the degradation ability of the diatomite-modified biochar catalyst, and the degradation rate is 62%-72%. The modified biochar calcined at 950 °C has better degradation performance.

[0061] Figure 3 It is a graph showing the variation of the concentration ratio of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention (20mg, 40mg, 60mg, 80mg, and 100mg) with time; Table 3 is a comparison of the degradation rates of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention at different dosages. It can be seen that the degradation rate is 71%-77%. When the dosage of the diatomite-modified biochar catalyst is 60 mg, the degradation ability is the best.

[0062] Figure 4 It is a graph showing the variation of the concentration ratio of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention at different dosages of persulfate (0.3mM, 0.4mM, 0.5mM, 0.6mM, 0.7mM, and 0.8mM) with time; Table 4 is a comparison of the degradation rates of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Example 5 of the present invention at different dosages of persulfate. It can be seen that the degradation rate is 76%-81%. When the dosage of persulfate is 0.5 mM, the degradation ability is the best.

[0063] The biochar modified by diatomite has good catalytic ability for persulfate, its removal effect on methyl orange dye is significantly enhanced, and the reaction time is greatly shortened. [[ID=??]]

[0064] Table 1 Comparison of the degradation rates of methyl orange in wastewater by the diatomite-modified biochar catalyst disclosed in Examples 1-3 of the present invention and the pure persimmon tree branch biochar disclosed in Comparative Example 1.

[0065]

[0066] Table 2 Comparison of the degradation rates of methyl orange wastewater degraded by the diatomite-modified biochar catalyst disclosed in Examples 2, 4, and 5 of the present invention at different calcination temperatures

[0067] Table 3 Comparison of Degradation Rates of Methyl Orange Wastewater Catalyzed by the Diatomite-Modified Biochar Catalyst Disclosed in Example 5 of the Present Invention at Different Dosages

[0068] Table 4 Comparison of Degradation Rates of Methyl Orange Wastewater Catalyzed by the Diatomite-Modified Biochar Catalyst Disclosed in Example 5 of the Present Invention at Different Dosages of Persulfate

[0069] In summary, the diatomite-modified biochar catalyst disclosed in the present invention, through the organic combination of diatomite and persimmon branch biochar, significantly improves the specific surface area and metal active sites of the material, exhibits high catalytic performance and excellent stability, and is easy to recycle, safe, environmentally friendly and without secondary pollution; when it is applied to catalyze the degradation of water pollutants by persulfate, it can efficiently degrade various pollutants, has a wide application range, and at the same time has the advantages of low treatment cost, simple and flexible operation, etc., providing an efficient, economical and environmentally friendly solution for water pollution treatment.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a diatomite-modified biochar catalyst, characterized in that, Including: After crushing, grinding and sieving persimmon tree branches, persimmon tree branch powder is obtained, which is first mixed and stirred with diatomite and phosphate, and after calcination, modified biochar is obtained, and then secondarily mixed and stirred with urea, and after drying, diatomite-modified biochar catalyst is obtained.

2. The preparation method of the diatomite-modified biochar catalyst according to claim 1, wherein, The mass ratio of the persimmon tree branch powder, diatomite and phosphate is (5 - 15):1:1; the phosphate is triple superphosphate.

3. The preparation method of the diatomite-modified biochar catalyst according to claim 1, wherein, The time of the first mixing and stirring is 2 - 5 h; the heating rate of the calcination is 10 °C / min; the calcination temperature is 750 - 950 °C; the calcination time is 75 - 95 min.

4. The preparation method of the diatomite-modified biochar catalyst according to claim 1, characterized in that, The mass ratio of the modified biochar to urea is 4:

1.

5. The preparation method of the diatomite-modified biochar catalyst according to claim 1, wherein The time of the second mixing and stirring is 3 - 5 h.

6. A diatomite-modified biochar catalyst, characterized in that, Prepared by using the preparation method of the diatomite-modified biochar catalyst according to any one of claims 1 to 5.

7. Use of the diatomite-modified biochar catalyst prepared by the preparation method according to any one of claims 1 to 5 in catalytic degradation of water pollutants by persulfate, characterized in that, Adding the diatomite-modified biochar catalyst and persulfate to the simulated wastewater, and after shaking reaction, the pollutants in the water are degraded.

8. Use of the diatomite-modified biochar catalyst according to claim 7 in the catalytic degradation of water pollutants by persulfate, characterized in that, In every 100 ml of methyl orange polluted solution with a concentration of 20 mg / L, 0.02 - 0.1 g of diatomite-modified biochar catalyst and 0.3 - 0.8 mM persulfate solution are added.

9. Use of the diatomite-modified biochar catalyst according to claim 7 in catalytic degradation of water pollutants by persulfate, characterized in that, The simulated wastewater is a methyl orange solution, and the concentration of the methyl orange solution is not more than 50 mg / L; the persulfate is at least one of potassium monopersulfate, sodium monopersulfate, potassium persulfate and sodium persulfate.

10. Use of the diatomite-modified biochar catalyst according to claim 7 in catalytic degradation of water pollutants by persulfate, characterized in that, The time of the shaking reaction is 30 - 60 min.

Images