Preparation method and application of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material

Abstract

The invention discloses a preparation method and application of a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material. The preparation method comprises the following steps: mixing pretreated rectorite, water bloom algae mud and river and lake bottom mud in proportion to obtain powder, soaking the powder in an iron modifier solution, fully stirring, carrying out suction filtration, drying, placing the mixture in a tubular furnace, carbonizing under the protection of argon, and cooling to room temperature, so as to obtain the rectorite / water bloom algae mud / river and lake bottom mud composite material. The magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is obtained. The composite biochar material is prepared from natural clay mineral rectorite, lake water bloom algae mud and river and lake bottom mud, is wide in source and low in cost, has a good adsorption effect on different types of pollutants such as tetracycline (TC), lead ions (Pb < 2 + >) and phosphorus (P) in an aqueous solution, has a practical application prospect, and is suitable for industrial production. And meanwhile, a new strategy is provided for resource utilization of solid wastes.

Description

Technical Field

[0001] The present invention relates to the field of treatment and disposal of natural clay minerals, algae bloom mud, and river and lake bottom mud, and in particular to the preparation and application of magnetic rectorite / algae bloom mud / river and lake bottom mud composite biochar materials. The prepared composite biochar material has a good effect on tetracycline (TC) and lead ions (Pb 2+ ) and phosphorus (P) have good adsorption properties and can effectively remove such pollutants in the water environment. The magnetic material can also be recycled and reused, realizing the resource utilization of solid waste and has good practical application prospects. Background Art

[0002] In recent years, the presence of a variety of antibiotics has been widely detected in aquatic environments such as lakes and rivers, among which tetracyclines show a high detection rate. Tetracycline is widely used, but it cannot be completely metabolized in humans and animals, causing it to be released into the water environment, affecting the human living environment. Heavy metal pollution in water bodies mainly includes lead, cadmium, mercury, zinc, copper, etc. Lead is a toxic heavy metal that not only directly threatens the survival and reproduction of aquatic organisms and destroys the balance of aquatic ecosystems, but also accumulates lead ions through the food chain, posing a potential threat to higher-level organisms.

[0003] In addition, cyanobacteria blooms are also a major environmental problem facing my country's terrestrial aquatic systems such as lakes and reservoirs. Cyanobacteria blooms are not only the result of eutrophication of water bodies, but also aggravate pollution through positive and negative feedback mechanisms. If the excessive cyanobacteria in lakes are salvaged ashore and not handled in time, toxic and harmful substances will be produced, forming secondary pollution. Bottom mud is sediment accumulated at the bottom of the water body for a long time. A large amount of pollutants in the polluted water body are enriched in the bottom mud. When the water environment changes, the pollutants in the bottom mud will be released back into the water environment. Harmless treatment of river and lake bottom mud and resource utilization is a good pollution control technology. It can reduce the content of pollutants in the water body and achieve the purpose of dredging and bottom mud dredging.

[0004] Biochar has become an environmentally friendly material and has received extensive attention due to its low cost, wide sources, and rich functional groups. Rectorite is a natural layered clay mineral with a special structure. Its interlayer domain can serve as a good chemical reaction site and has the characteristics of interlayer exchange and adsorption. In recent years, it has been increasingly studied and applied in the field of environmental materials. The adsorption capacity of a single biochar is often limited, and the combination of carbon materials and rectorite can improve the pollutant removal performance. At present, iron-modified biochar has been widely used to remove pollutants from aqueous solutions, and transition metals and their oxides are introduced into the matrix to form magnetic biochar. In the iron modification process, modifiers with different valence states of iron are usually used as iron precursors, and the adsorption reaction mechanism varies with the valence state of iron. In short, the iron modification process can expand the surface area of ​​the resulting biochar and introduce a large number of oxygen-containing functional groups and iron oxides, which is beneficial to the adsorption performance of biochar.

[0005] Therefore, how to utilize natural clay mineral rectorite, natural water bloom algae mud and river and lake sediments to realize the resource utilization of solid waste; how to achieve the effective composite of ternary materials to make up for the limitations of single biochar materials in adsorption capacity; how to select ideal iron modifiers as iron precursors to improve the magnetic properties, reusability and stability of materials, and design and prepare new multifunctional composite biochar materials can provide ideas for the above problems. Summary of the invention

[0006] The present invention aims at the treatment of antibiotic pollution, heavy metal pollution, eutrophication of water bodies in aquatic environments such as lakes and rivers, and the reasonable disposal of solid wastes such as algae mud and bottom mud, and aims to provide a preparation method of a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material. Based on the concept of turning waste into treasure, treating waste with waste and the original intention of realizing the resource utilization of solid waste, the present invention uses natural rectorite as a carrier, algae mud and bottom mud as a carbon source, and an iron modifier as an iron precursor to prepare a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material by an impregnation pyrolysis method. The preparation method is low in price and easy to operate. The combination of magnetic particles and biochar matrix is ​​stable, which is conducive to maintaining the overall performance and long-term stability of the material. The material is a low-cost, recyclable, environmentally friendly new material that utilizes clay minerals, algae mud, and bottom mud as resources, has great advantages, provides a new idea for the treatment of lakes and the resource utilization of waste, and is expected to provide a reference for different valence iron sources suitable for pyrolysis of biomass raw materials to prepare magnetic materials.

[0007] Another object of the present invention is to provide a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material for use in removing antibiotic pollutants, heavy metal pollutants, and nutrient pollutants in water bodies. The prepared composite biochar material realizes the combination of ternary materials and effectively utilizes their respective inherent characteristics, thereby increasing their adsorption performance (see Table 1). Through iron modification, iron oxide particles are introduced into the composite biochar material, and more ordered pore structures are embedded in the original layered structure. Its large specific surface area and rich oxygen-containing functional groups-dominated chemical adsorption promote the removal of pollutants. At the same time, the prepared composite biochar material has excellent reusability and stability, and can be recycled and reused, and has good practical application value.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] The present invention uses rectorite as a carrier, algae mud and bottom mud as carbon sources, and an iron modifier as an iron precursor to prepare a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material through an impregnation pyrolysis method.

[0010] A method for preparing a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material comprises the following steps:

[0011] (1) Pretreatment of rectorite: Take rectorite mineral powder, soak and wash it with ultrapure water and anhydrous ethanol for 5 times, filter it, dry it at 60-80℃, and pass it through a 40-60 mesh sieve;

[0012] (2) Pretreatment of algae bloom mud: The algae water salvaged from Dianchi Lake is subjected to physical filtration and cyclone dehydration to obtain algae mud, which is centrifuged again at a speed of 3000-6000 rpm and repeatedly washed. The precipitate is placed in an oven at 60-80°C for drying, ground, and sieved through a 40-60 mesh sieve;

[0013] (3) Pretreatment of river and lake sediments: Take natural river and lake sediments, dehydrate and clean them by centrifugation at a speed of 3000-6000 rpm, dry them at 60-80°C, grind them, and pass them through a 40-60 mesh sieve;

[0014] (4) Mixing and treatment: 3-5 g of pretreated rectorite is added to deionized water, and stirred for the first time for 30-60 minutes to obtain a suspension solution. The pretreated water bloom algae mud and river and lake bottom mud are added to the suspension solution, and the mass ratio of the rectorite: water bloom algae mud: river and lake bottom mud is 1-2:0.5-2:1-3. The mixture is stirred again for 30-60 minutes until uniform, filtered, and dried at 60-80°C to obtain a primary mixture powder and an iron modifier in a mass ratio of 5:1-5 and dissolved in deionized water. The mixture is stirred for a third time for 4-6 hours and dried at 60-100°C to obtain a mixture. The mixture is then placed in a tubular furnace filled with argon, calcined and carbonized at 300-600°C, and the reaction is stopped after 2 hours. The mixture is taken out after the temperature drops to room temperature to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0015] Preferably, in step (1), the drying temperature is 60°C, and the powder is ground and passed through a 60-mesh sieve.

[0016] Preferably, in steps (2) and (3), the centrifugal speed is 3500 rpm, the drying temperature is 60°C, and the product is sieved through a 60-mesh sieve after grinding.

[0017] Preferably, the iron modifier in step (4) is ferrous sulfate heptahydrate FeSO4·7H2O, ferric chloride hexahydrate FeCl3·6H2O or potassium ferrate K2FeO4.

[0018] Preferably, in step (4), the stirring time of the suspension is 30 minutes, the mass ratio of rectorite, algae mud and bottom mud is 2:1:1, the mass ratio of the primary mixture powder to potassium ferrate (K2FeO4) is 5:3, the heating rate of the tubular furnace is 5°C / min, the calcination temperature is 500°C, and the calcination time is 2 hours. Through the above technical measures: using rectorite as a carrier, algae mud and bottom mud as carbon sources, and FeSO4·7H2O, FeCl3·6H2O or K2FeO4 as an iron precursor, a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is prepared, which can be used to remove antibiotic pollutants, heavy metal and nutrient pollutants in water bodies, respectively. Specific antibiotic pollutants include tetracycline (TC), heavy metal pollutants include lead ions (Pb 2+ ), nutrient pollutants include phosphorus (P).

[0019] Compared with the prior art, the present invention has the following advantages and effects:

[0020] (1) The magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material prepared by the present invention has the following advantages: the adsorbent raw materials used are rectorite, natural water bloom algae mud and river and lake bottom mud, which can be directly obtained from nature. The algae mud used in the composite biochar material is upgraded to "pressure wall breaking, flocculation sedimentation + high-efficiency flotation" during the algae water treatment process of the algae water separation station, and the dehydration method is spiral dehydration, achieving a moisture content of less than 90%. Algae mud comes from algae in natural water bodies and contains rich organic matter. These organic matter mainly comes from the cell composition and metabolites of algae, which not only provides rich nutrients for algae mud, but also makes it have certain biological activity and adsorption capacity. The drying temperature in the preparation process of the composite biochar material is 60°C, which ensures the drying efficiency while avoiding the damage of high temperature to the algae mud and bottom mud components and the influence of biochar quality. The composite biochar material is pyrolyzed at 500°C, which not only retains the special interlayer structure of rectorite, but also obtains the optimal carbonization structure of algae mud and bottom mud. Biochar particles from algae mud and sediment were successfully embedded on the surface and interlayer structure of rectorite, effectively utilizing the good properties of the ternary material to greatly increase the adsorption capacity and make up for the limitations of single biochar material in adsorption capacity.

[0021] (2) The magnetic rectorite / algae bloom mud / river and lake sediment composite biochar material prepared by the present invention has rich oxygen-containing functional groups and pore structure, and its specific surface area is much larger than that of single rectorite, algae mud biochar and sediment biochar. In the FeSO4·7H2O, FeCl3·6H2O and K2FeO4 modification, organic cations (Fe 2+ , Fe 3+ ) increases the interlayer space of clay minerals, effectively expanding the specific surface area of ​​biochar materials. In particular, the corrosion caused by KOH formed during the activation of K2FeO4 and the pore expansion effect of the introduced gas make it easier to form pores, so that the surface and interlayer of the material have a rich pore structure, which is conducive to providing more accessible active sites, thereby enhancing the adsorption capacity. The adsorption performance of the prepared magnetic composite biochar material is significantly better than that of the original rectorite, algae mud biochar, sediment biochar and other existing biochar materials.

[0022] (3) The preparation process of the magnetic rectorite / water bloom algae mud / river and lake mud composite biochar material prepared by the present invention is simple and easy to operate. The magnetization and pyrolysis are completed simultaneously in one process by the impregnation pyrolysis method, which greatly simplifies the preparation process. FeSO4·7H2O, FeCl3·6H2O and K2FeO4 are all precursors of magnetic iron oxide, among which K2FeO4 is a green oxidant with stronger oxidation ability than iron and ferrous compounds, and can be used as a superior precursor of magnetic iron oxide. The magnetic particles are formed by redox reaction and firmly loaded on the surface of the biochar matrix to form a stable bond, which makes the composite biochar material have excellent reusability and stability. At the same time, its strong magnetism facilitates the recovery and reuse of the material through an external magnetic field, further reducing the risk of environmental pollution.

[0023] (4) The composite biochar material of magnetic rectorite / bloom algae mud / river and lake mud prepared by the present invention has a wide range of raw material sources and low cost. On the one hand, the composite biochar material is a low-cost, recyclable, environmentally friendly new material that realizes the resource utilization of solid waste. On the other hand, the composite biochar material can effectively adsorb antibiotics, heavy metals and phosphorus in aqueous solutions (removal rates are 96.8%, 76.0% and 58.3% respectively), which has great advantages and provides a new strategy for the resource utilization of solid waste, and also provides a new idea for the eutrophication control of river and lake water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 SEM images of rectorite (a), algal mud biochar (b), sediment biochar (c), (non-magnetic) rectorite / algal bloom biochar / river and lake sediment composite biochar material (d) and magnetic rectorite / algal bloom biochar / river and lake sediment composite biochar material (e).

[0025] Figure 2 They are the XRD patterns of rectorite, algal mud biochar, sediment biochar, (non-magnetic) rectorite / algal bloom biochar / river and lake sediment composite biochar material, and magnetic rectorite / algal bloom biochar / river and lake sediment composite biochar material.

[0026] Figure 3 They are FT-IR images of rectorite, algal mud biochar, sediment biochar, (non-magnetic) rectorite / algal bloom biochar / river and lake sediment composite biochar material, and magnetic rectorite / algal bloom biochar / river and lake sediment composite biochar material.

[0027] Figure 4 This is the magnetization curve of the composite biochar material of magnetic rectorite / bloom algae mud / river and lake mud. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described below in conjunction with embodiments, but the embodiments of the present invention are not limited thereto.

[0029] Embodiment 1:

[0030] A method for preparing a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material comprises the following steps:

[0031] 1. Pretreatment of rectorite: Take 12g of rectorite powder, wash it with ultrapure water and anhydrous ethanol 5 times, filter it, and dry it at 60℃;

[0032] 2. Pretreatment of algae bloom mud: 10g of algae water salvaged from Dianchi Lake was taken and subjected to physical filtration and cyclone dehydration to obtain algae mud, which was centrifuged and dehydrated again for 3 times. The precipitate was dried in a 60℃ oven, ground and passed through a 60-mesh sieve;

[0033] 3. Pretreatment of river and lake algae mud: Take 10g of Yanxi Lake mud, dehydrate, wash, dry at 60℃, grind and pass through a 60-mesh sieve;

[0034] 4. Mixing and treatment: Place 3g of pretreated rectorite in a beaker containing 100mL of deionized water and stir thoroughly for 30mins to obtain a suspension solution, take 1.5g of pretreated algae mud and 1.5g of bottom mud and add them to the solution, stir thoroughly at 25°C, filter, and dry at 60°C; dissolve 5g of the above-mentioned primary mixture powder and 3g K2FeO4 in 100mL of deionized water, stir thoroughly with a magnetic stirrer for 6h, dry at 60°C, and then place the mixture in a tubular furnace and carbonize it under argon protection for 2h. The heating rate of the tubular furnace is 5°C / min, and the calcination temperature is 500°C. After the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0035] 5. Take 20 mg of the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material prepared in this embodiment for tetracycline adsorption experiment, the specific steps are: add 20 mg of the magnetic composite biochar material and 100 mL of tetracycline solution to a 250 mL conical flask, adjust the pH value of the solution to 6.5 with 0.1 mol / L HCl and NaOH, and oscillate on a constant temperature shaker in the dark. The initial concentration of the tetracycline solution is 20 mg / L, the reaction temperature is 25 ° C, and the reaction time is 60 mins. The experimental results show that the adsorption amount of tetracycline in aqueous solution by the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is 88.1 mg / g, and the removal rate is 96.8%.

[0036] Embodiment 2:

[0037] A method for preparing a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material comprises the following steps:

[0038] 1. Pretreatment of rectorite: Take 12g of rectorite powder, wash it with ultrapure water and anhydrous ethanol 5 times, filter it, and dry it at 60℃;

[0039] 2. Pretreatment of algae bloom mud: 10g of algae water salvaged from Dianchi Lake was taken and subjected to physical filtration and cyclone dehydration to obtain algae mud, which was centrifuged and dehydrated again for 3 times. The precipitate was dried in a 60℃ oven, ground and passed through a 60-mesh sieve;

[0040] 3. Pretreatment of river and lake sediments: Take 10g of Yanxi Lake sediment, dehydrate, wash, dry at 60℃, grind and pass through a 60-mesh sieve;

[0041] 4. Mixing and treatment: Place 3g of pretreated rectorite in a beaker containing 100mL of deionized water and stir thoroughly for 30mins to obtain a suspension solution, take 1.5g of pretreated algae mud and 0.75g of bottom mud and add them to the solution, stir thoroughly at 25°C, filter, and dry at 60°C; dissolve 5g of the above-mentioned primary mixture powder and 3g K2FeO4 in 100mL of deionized water, stir thoroughly for 6h with a magnetic stirrer, dry at 60°C, and then place the mixture in a tubular furnace and carbonize for 2h under argon protection. The heating rate of the tubular furnace is 5°C / min, and the calcination temperature is 500°C. After the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0042] 5. Take 20 mg of the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material prepared in this embodiment for tetracycline adsorption experiment, the specific steps are: add 20 mg of the magnetic composite biochar material and 100 mL of tetracycline solution into a 250 mL conical flask, adjust the pH value of the solution to 6.5 with 0.1 mol / L HCl and NaOH, and shake on a constant temperature shaker. The initial concentration of the tetracycline solution is 20 mg / L, the reaction temperature is 25 ° C, and the reaction time is 60 mins. The experimental results show that the adsorption amount of tetracycline in the aqueous solution by the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is 83.3 mg / g, and the removal rate is 90.8%.

[0043] Embodiment 3:

[0044] A method for preparing a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material comprises the following steps:

[0045] 1. Pretreatment of rectorite: Take 12g of rectorite powder, wash it with ultrapure water and anhydrous ethanol 5 times, filter it, and dry it at 60℃;

[0046] 2. Pretreatment of algae bloom mud: 10g of algae water salvaged from Dianchi Lake was taken and subjected to physical filtration and cyclone dehydration to obtain algae mud, which was centrifuged and dehydrated again for 3 times. The precipitate was dried in a 60℃ oven, ground and passed through a 60-mesh sieve;

[0047] 3. Pretreatment of river and lake sediments: Take 10g of Yanxi Lake sediment, dehydrate, wash, dry at 60℃, grind and pass through a 60-mesh sieve;

[0048] 4. Mixing and treatment: 3 g of pretreated rectorite was placed in a beaker containing 100 mL of deionized water and stirred for 30 min to obtain a suspension solution. 1.5 g of pretreated algae mud and 1.5 g of bottom mud were added to the solution, stirred evenly at 25 ° C, filtered, and dried at 60 ° C; 5 g of the above-mentioned primary mixture powder and 3 g of FeSO4·7H2O were dissolved in 100 mL of deionized water, stirred for 6 h with a magnetic stirrer, dried at 60 ° C, and then the mixture was placed in a tubular furnace for carbonization under argon protection for 2 h. The heating rate of the tubular furnace was 5 ° C / min, and the calcination temperature was 500 ° C. After the reaction stopped, it was taken out when the temperature dropped to room temperature to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0049] 5. Take 50 mg of the magnetic rectorite / algae bloom mud / river and lake mud composite biochar material prepared in this example and perform Pb 2+ The specific steps of the adsorption experiment are as follows: 50 mg of the magnetic composite biochar material and 100 mL of Pb 2+ The solution was added to a 250 mL conical flask, and the pH value of the solution was adjusted to 5.0 with 0.1 mol / L HCl and NaOH, and then shaken on a constant temperature shaker. 2+ The initial concentration of the solution was 50 mg / L, the reaction temperature was 30 °C, and the reaction time was 60 mins. The experimental results showed that the magnetic rectorite / bloom algae mud / river and lake sediment composite biochar material had an effective effect on the removal of Pb in aqueous solution. 2+ The adsorption capacity was 50.8 mg / g and the removal rate was 56.0%.

[0050] Embodiment 4:

[0051] A method for preparing a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material comprises the following steps:

[0052] 1. Pretreatment of rectorite: Take 12g of rectorite powder, wash it with ultrapure water and anhydrous ethanol 5 times, filter it, and dry it at 60℃;

[0053] 2. Pretreatment of algae bloom mud: 10g of algae water salvaged from Dianchi Lake was taken and subjected to physical filtration and cyclone dehydration to obtain algae mud, which was centrifuged and dehydrated again for 3 times. The precipitate was dried in a 60℃ oven, ground and passed through a 60-mesh sieve;

[0054] 3. Pretreatment of river and lake algae mud: Take 10g of Yanxi Lake mud, dehydrate, wash, dry at 60℃, grind and pass through a 60-mesh sieve;

[0055] 4. Mixing and treatment: Place 3g of pretreated rectorite in a beaker containing 100mL of deionized water and stir thoroughly for 30mins to obtain a suspension solution, take 1.5g of pretreated algae mud and 1.5g of bottom mud and add them to the solution, stir thoroughly at 25℃, filter, and dry at 60℃; dissolve 5g of the above-mentioned primary mixture powder and 3g FeCl3·6H2O in 100mL of deionized water, stir thoroughly for 6h with a magnetic stirrer, dry at 60℃, and then place the mixture in a tubular furnace for carbonization under argon protection for 2h. The heating rate of the tubular furnace is 5℃ / min, and the calcination temperature is 500℃. After the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0056] 5. Take 50 mg of the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material prepared in this embodiment for P adsorption experiment, the specific steps are: add 50 mg of the magnetic composite biochar material and 100 mL of phosphate solution into a 250 mL conical flask, adjust the pH value of the solution to 6.5 with 0.1 mol / L HCl and NaOH, and shake on a constant temperature shaker. The initial concentration of the phosphorus solution is 50 mg / L, the reaction temperature is 30 ° C, and the reaction time is 24 h. The experimental results show that the adsorption amount of P in the aqueous solution by the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is 46.2 mg / g, and the removal rate is 51.1%.

[0057] Example 5 (Comparative Experiment 1: Adsorption comparison experiment of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material and (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar, rectorite, algae mud biochar, and bottom mud biochar):

[0058] An application of a (non-magnetic) rectorite / algae bloom mud / river and lake bottom mud composite biochar material in removing antibiotic pollutants, heavy metals and nutrient pollution in water bodies, the steps of which are:

[0059] Preparation of algae mud biochar and bottom mud biochar: 5g of pretreated bloom algae mud and river and lake bottom mud were taken respectively, placed in a tubular furnace for carbonization under argon protection for 2h, the heating rate of the tubular furnace was 5℃ / min, the calcination temperature was 500℃, the reaction was stopped after 2h, and the temperature was taken out when it dropped to room temperature to obtain algae mud biochar and bottom mud biochar respectively. (The pretreatment method is the same as Example 4)

[0060] Preparation of (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar: Take 3g of pretreated rectorite and place it in a beaker containing 100mL of deionized water and stir it thoroughly for 30mins to obtain a suspended solution, take 1.5g of pretreated water bloom algae mud and 1.5g of pretreated river and lake bottom mud and add them to the solution, stir thoroughly at 25℃, filter, and dry at 60℃. The obtained powder is placed in a tubular furnace and carbonized under argon protection for 2h. The heating rate of the tubular furnace is 5℃ / min, and the calcination temperature is 500℃. After the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar.

[0061] The pretreated rectorite and the algae mud biochar, sediment biochar, (non-magnetic) rectorite / algae bloom mud / river and lake sediment composite biochar, and the magnetic rectorite / algae bloom mud / river and lake sediment composite biochar material prepared in Example 1 were used as adsorbents to perform tetracycline (TC), heavy metals (Pb 2+ ) and the nutrient phosphorus (P) adsorption comparison experiment. The specific steps are: 20 mg of the magnetic composite biochar material and 100 mL of tetracycline solution, Pb 2+ The solution and phosphate solution were added to a 250 mL conical flask, and the pH value of the solution was adjusted to 6.5 with 0.1 mol / L HCl and NaOH, and the solution was shaken on a thermostatic shaker in the dark. The reaction temperature was 25 °C, the reaction time was 60 mins, and TC, Pb 2+ The initial concentration of P was 20 mg / L.

[0062] Table 1 Adsorption rate data of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, rectorite, algae mud biochar, and bottom mud biochar

[0063]

[0064] As can be seen from Table 1, the adsorption rate of TC by the composite biochar material of magnetic rectorite / algae bloom mud / river and lake sediment is as high as 96.8%, which is higher than the adsorption efficiency of (non-magnetic) rectorite / algae bloom mud / river and lake sediment composite biochar material (69.5%), rectorite (33.1%), algae mud biochar (29.4%) and sediment biochar (24.3%). 2+The adsorption rate of P was 76.0%, which was higher than that of (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar material (58.2%), rectorite (42.7%), algae mud biochar (19.8%) and bottom mud biochar (23.6%). The adsorption rate of P by magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material was 58.3%, which was higher than that of (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar material (40.6%), rectorite (32.5%), algae mud biochar (18.4%) and bottom mud biochar (15.8%). It shows that the adsorption performance of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material is significantly improved compared with that of rectorite, single biochar and composite biochar before iron modification.

[0065] Example 6 (Comparative Experiment 2: Adsorption comparison experiment of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar materials prepared by different methods and (non-magnetic) rectorite / water bloom algae mud / river and lake bottom mud composite biochar, rectorite, algae mud biochar, and bottom mud biochar):

[0066] Preparation of algae mud biochar and bottom mud biochar: 5g of pretreated bloom algae mud and pretreated river and lake bottom mud were taken respectively, placed in a tubular furnace under argon protection for carbonization for 4h, the heating rate of the tubular furnace was 5℃ / min, the calcination temperature was 400℃, and after the reaction stopped, the temperature dropped to room temperature and was taken out to obtain algae mud biochar and bottom mud biochar respectively. (The pretreatment method is the same as in Example 4)

[0067] Preparation of (non-magnetic) rectorite / water bloom algae mud / river and lake sediment composite biochar: 3 g of pretreated rectorite, 1.5 g of pretreated algae mud, and 1.5 g of pretreated sediment were added into deionized water, stirred thoroughly at 25 °C, filtered, and dried at 60 °C. The obtained powder was placed in a tubular furnace under argon protection and carbonized for 4 h.

[0068] The furnace heating rate was 5°C / min, the calcination temperature was 400°C, and after the reaction stopped, the temperature dropped to room temperature and the biochar was taken out to obtain the rectorite / bloom algae mud / river and lake mud composite biochar.

[0069] Preparation of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material: take 3g of pretreated rectorite, 1.5g of pretreated water bloom algae mud, and 1.5g of pretreated river and lake bottom mud, add them to the solution, stir thoroughly at 25℃, filter, and dry at 60℃; dissolve 5g of the above-mentioned primary mixture powder and 3g FeCl3·6H2O in 100mL deionized water, stir thoroughly with a magnetic stirrer for 6h, dry at 60℃, and then place the mixture in a tubular furnace for carbonization under argon protection for 4h. The heating rate of the tubular furnace is 5℃ / min, the calcination temperature is 400℃, and after the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain the magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

[0070] The pretreated rectorite and the above algae mud biochar, sediment biochar, (non-magnetic) rectorite / algae bloom mud / river and lake sediment composite biochar, and magnetic rectorite / algae bloom mud / river and lake sediment composite biochar were used as adsorbents to test tetracycline (TC), heavy metals (Pb 2+ ) and nutrient phosphorus (P) adsorption experiment. The specific steps are: 20 mg of the magnetic composite biochar material and 100 mL of tetracycline solution, Pb 2+ The solution and phosphate solution were added to a 250 mL conical flask, and the pH value of the solution was adjusted to 6.5 with 0.1 mol / L HCl and NaOH, and the solution was shaken on a thermostatic shaker in the dark. The reaction temperature was 25 °C, the reaction time was 60 mins, and TC, Pb 2+ The initial concentration of P was 20 mg / L.

[0071] Table 2 Adsorption rate data of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, rectorite, algae mud biochar, and bottom mud biochar

[0072]

[0073]

[0074] It can be seen from Table 2 that the adsorption rates of TC by the composite biochar materials of magnetic rectorite / water bloom algae mud / river and lake sediment, the composite biochar materials of rectorite / water bloom algae mud / river and lake sediment, rectorite, algae mud biochar and sediment biochar were 75.5%, 58.4%, 33.1%, 22.5% and 19.8%, respectively. The adsorption rates of Pb by the composite biochar materials of magnetic rectorite / water bloom algae mud / river and lake sediment, the composite biochar materials of rectorite / water bloom algae mud / river and lake sediment, rectorite, algae mud biochar and sediment biochar were 75.5%, 58.4%, 33.1%, 22.5% and 19.8%, respectively. 2+The adsorption rates of P were 56.2%, 49.6%, 42.7%, 16.4% and 20.1% respectively. The adsorption rates of P by magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, rectorite / water bloom algae mud / river and lake bottom mud composite biochar material, rectorite, algae mud biochar and bottom mud biochar were 43.3%, 36.9%, 32.5%, 16.6% and 13.5% respectively. Although the adsorption rate of magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material was higher than that of rectorite, single biochar and composite biochar before iron modification, the adsorption rates of all biochars and composite biochar materials were lower than those of under the same conditions in Example 6, indicating that their adsorption performance was lacking.

[0075] The following is an experimental analysis of rectorite, algae mud biochar, sediment biochar, (non-magnetic) rectorite / water bloom algae mud / river and lake sediment composite biochar material and the magnetic rectorite / water bloom algae mud / river and lake sediment composite biochar material in Example 1.

[0076] Figure 1 The SEM images of rectorite, algae mud biochar, sediment biochar, (non-magnetic) rectorite / algae mud bloom / river and lake sediment composite biochar material, and magnetic rectorite / algae mud bloom / river and lake sediment composite biochar material are shown below. Figure 1 As shown in (a), the layers on the surface of the rectorite are tightly stacked, forming a unique layered texture. Figure 1 (b) and Figure 1 As shown in (c), the surface of algae mud biochar and sediment biochar is porous. Figure 1 As shown in (d), the surface structure of the (non-magnetic) rectorite / water bloom algae mud / river and lake sediment composite biochar material is uneven, and the biochar particles generated by pyrolysis of algae mud and sediment are dispersed on the surface and interlayer structure of the rectorite. Figure 1 As shown in (e), the iron-modified magnetic rectorite / bloom algae mud / river and lake mud composite biochar material becomes coarser, and more porous structures are embedded in the original layered structure, which is conducive to providing more accessible active sites.

[0077] Figure 2The XRD patterns of rectorite, algae mud biochar, sediment biochar, (non-magnetic) rectorite / water bloom algae mud / river and lake sediment composite biochar and magnetic rectorite / water bloom algae mud / river and lake sediment composite biochar materials are shown in Figure 2. The reflection peaks at 2θ=20.07°, 35.02° and 62.59° are characteristic peaks of rectorite. The reflection peaks at 2θ=20.85° and 26.65° in algae mud biochar, sediment biochar and (non-magnetic) rectorite / water bloom algae mud / river and lake sediment composite biochar materials are characteristic peaks of quartz. The diffraction peaks at 2θ=30.09°, 43.05° and 56.94° were found in the magnetic rectorite / water bloom algae mud / river and lake sediment composite biochar materials, which indicates that Fe3O4 is effectively loaded into the composite biochar materials.

[0078] Figure 3 FT-IR images of rectorite, algae mud biochar, sediment biochar, (non-magnetic) rectorite / algae bloom / river and lake sediment composite biochar material, and magnetic rectorite / algae bloom / river and lake sediment composite biochar material. Rectorite and rectorite / algae bloom / river and lake sediment composite biochar at 3642 cm -1 The peak at 1640 cm is the stretching vibration absorption peak of free hydroxyl -OH. -1 The peak at 1438 cm is attributed to the stretching vibration of C=O. -1 and 1035cm -1 The characteristic peaks at 3642cm belong to the absorption peaks of C=O and -CH2 respectively. -1 、3126cm -1 and 484cm -1 Absorption peaks were observed, which were the stretching vibration absorption peak of free hydroxyl group -OH, the stretching vibration peak of intermolecular hydrogen bond OH and the bending vibration peak of Si-O bond.

[0079] Figure 4 This is the magnetization curve of the composite biochar material of magnetic rectorite / water bloom algae mud / river and lake bottom mud. The saturation magnetism of the composite biochar material of magnetic rectorite / water bloom algae mud / river and lake bottom mud is 10.0emu / g, which makes it have good sedimentation and saturation magnetism in water, and can maintain its good magnetic properties and efficient adsorption performance in subsequent applications. In addition, with the help of an external magnetic field, the composite biochar material can be easily and quickly separated from the aqueous solution, which greatly simplifies separation operations such as filtration and centrifugation, thereby improving the processing efficiency.

Claims

1. A method for preparing a composite biochar material of magnetic rectorite / algae bloom mud / river and lake mud, characterized in that: The following steps are involved: 1) Pretreatment of rectorite: Take rectorite mineral powder, soak and wash it with ultrapure water and anhydrous ethanol, filter it, dry it at 60-80℃, and pass it through a 40-60 mesh sieve; 2) Pretreatment of algae mud from water blooms: take algae water from the water blooms, physically filter and dehydrate the algae mud, centrifuge and dehydrate again, wash, take the precipitate and dry at 60-80°C, grind, and pass through a 40-60 mesh sieve; 3) Pretreatment of river and lake sediments: Take natural river and lake sediments, dehydrate, clean, dry at 60-80℃, grind, and pass through a 40-60 mesh sieve; 4) Mixing and treatment: Take 3-5g of pretreated rectorite, add deionized water, stir for the first time for 30-60mins to obtain a suspension solution, add the pretreated water bloom algae mud and river and lake bottom mud to the suspension solution, the mass ratio of the rectorite: water bloom algae mud: river and lake bottom mud is 1-2:0.5-2:1-3; stir again for 30-60mins until uniform, filter, dry, grind and obtain the primary mixture powder and iron modifier in a mass ratio of 5:1-5 and dissolve in deionized water, stir for a third time for 4-6h, dry and carbonize the mixture at 300-600℃ under argon protection, after the reaction stops, wait for the temperature to drop to room temperature and take it out to obtain a magnetic rectorite / water bloom algae mud / river and lake bottom mud composite biochar material.

2. The method for preparing the composite biochar material of magnetic rectorite / bloom algae mud / river and lake mud according to claim 1, characterized in that: In the step 4), the first stirring time is 30 minutes, the second stirring time is 60 minutes, and the third stirring time is 6 hours; the mass ratio of rectorite, algae bloom mud, and river and lake bottom mud is 2:1:

1.

3. The method for preparing the composite biochar material of magnetic rectorite / bloom algae mud / river and lake mud according to claim 1, characterized in that: In the step 4), the mass ratio of the primary mixture powder to the iron modifier is 5:3, the heating rate of the tubular furnace is 5° C. / min, the calcination temperature is 500° C., and the calcination time is 2 h.

4. The method for preparing the composite biochar material of magnetic rectorite / bloom algae mud / river and lake mud according to claim 1, characterized in that: In the step 4), the iron modifier is a mixture of one or more of ferrous sulfate heptahydrate, ferric chloride hexahydrate or potassium ferrate.

5. A magnetic rectorite / bloom algae mud / river and lake mud composite biochar material prepared according to the preparation method according to any one of claims 1 to 4.

6. Use of the magnetic rectorite / bloom algae mud / river and lake mud composite biochar material according to claim 5 in removing antibiotic pollutants, heavy metals and nutrient pollutants in water environments.

7. The use according to claim 6, characterized in that: The antibiotic pollutant is tetracycline TC.

8. The use according to claim 6, characterized in that: The heavy metal is lead ion Pb 2+ .

9. The use according to claim 6, characterized in that: The nutrient pollutant is phosphorus P.

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