Steel slag and calcium thioglycolate modified charcoal composite material as well as preparation method and application thereof

Abstract

The invention discloses a steel slag and calcium thioglycolate modified charcoal material as well as a preparation method and application thereof. The preparation method comprises the following steps: by taking rice straw powder as a raw material, firstly, carrying out anaerobic pyrolysis to obtain original biochar, then mixing steel slag and calcium thioglycolate treated by dilute nitric acid and hydrogen peroxide with the original biochar, and carrying out ball milling to obtain the steel slag and calcium thioglycolate modified biochar material. The steel slag and calcium thioglycolate modified biochar material has a developed pore structure, iron mineral particles in the steel slag are uniformly distributed on the biochar, a sulfydryl functional group is introduced to the biochar, organic matter and heavy metal combined pollution in the environment can be efficiently removed, the preparation steps are simple, the cost is low, and the method is suitable for industrial production. Waste resource utilization and large-scale production of materials are facilitated, and remarkable economic, environmental and social effects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental remediation materials, and particularly relates to a steel slag and calcium thioglycolate modified biochar material, a preparation method thereof and an application thereof. Background Art

[0002] Pollutants in soil are mostly associated and comprehensive, that is, multiple pollutants coexist to form combined pollution, resulting in the gradual emergence of combined pollution of heavy metals and antibiotics in farmland soil. Moreover, it has been found in research that the combined pollution of heavy metals and antibiotics in soil will produce stronger ecological toxicity and higher abundance of resistance genes than single pollutants, thus posing a greater threat to the soil environment. There is an urgent need to develop green and efficient combined pollution remediation technologies.

[0003] Biochar is a new type of carbonaceous adsorbent with high efficiency and economy. Due to its unique physical and chemical properties, such as high specific surface area, rich porous structure, etc., it has the potential to enhance the adsorption and fixation of coexisting heavy metals and antibiotics in soil, alleviate and control the combined pollution of heavy metals and antibiotics in soil. However, the surface active sites of raw biochar are limited and the adsorption capacity is limited. There is an urgent need for effective means to improve the adsorption performance of biochar. Heavy metals and antibiotics may also have competitive / synergistic and other interaction effects on biochar, which affects the adsorption performance of biochar for coexisting heavy metals and antibiotics. The problem of competitive adsorption of combined pollution needs to be solved urgently.

[0004] At present, the cumulative inventory of steel slag in China is nearly 2 billion tons. The main chemical components of steel slag are oxides of calcium, iron, aluminum and manganese, and the iron content is 10-30%. And the cost of steel slag is low, it has a large specific surface area, rich porous structure, and contains a variety of functional groups, which can be used as an excellent adsorbent to improve the adsorption performance of biochar; at the same time, steel slag contains rich iron minerals. By using the ball milling method, the iron minerals can be evenly loaded on the surface of biochar, which can improve the ability of biochar to oxidize and degrade antibiotics. At the same time, ball-milled biochar will have a more developed pore structure than non-ball-milled biochar, thereby improving the removal ability of biochar for heavy metals and organic matter. At the same time, adding calcium thioglycolate can introduce thiol functional groups and improve the adsorption efficiency of the material for heavy metals. Modifying biochar by combining it with steel slag using ball milling technology can not only improve the remediation ability of biochar for combined pollution in soil, but also realize the resource utilization of waste. This modification method has great application value. Summary of the Invention

[0005] In view of the limitations of current heavy metal and antibiotic combined pollution remediation technologies, the present invention provides a steel slag and calcium thioglycolate modified biochar material, its preparation method and application. The steel slag and calcium thioglycolate modified biochar material prepared by a simple ball milling method has the advantages of uniform dispersion and strong stability. The prepared steel slag and calcium thioglycolate modified biochar material has the ability to simultaneously oxidize and degrade antibiotics and adsorb heavy metals.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] I. A steel slag and calcium thioglycolate modified biochar material

[0008] The steel slag and calcium thioglycolate modified biochar material is prepared by ball milling steel slag, calcium thioglycolate and biochar.

[0009] The steel slag is blast furnace slag with a size of 0.075 mm;

[0010] The biochar precursor is rice straw.

[0011] II. A preparation method of a steel slag and calcium thioglycolate modified biochar material, comprising the following steps:

[0012] Step 1) Dry the rice straw powder and transfer it to a tubular furnace. Pyrolyze it under nitrogen conditions. After cooling to room temperature, wash the obtained material with deionized water multiple times and place it in an oven to dry to obtain biochar (BC);

[0013] Step 2) Mix the steel slag with deionized water evenly. Under stirring conditions, slowly drip the diluted concentrated nitric acid and hydrogen peroxide solution into the steel slag particles. After full reaction, wash the obtained material with deionized water and perform centrifugation. After suction filtration, place it in an oven to dry to obtain pretreated steel slag (SS);

[0014] Step 3) Fully mix the biochar obtained in Step 1) with the pretreated steel slag and calcium thioglycolate in Step 2), place it in a ball milling tank, set the rotation speed and ball milling time of the ball mill so that the biochar, the pretreated steel slag, calcium thioglycolate and the zirconia beads in the ball milling tank are in full contact; after the ball milling program ends, take out the material and screen it to obtain the steel slag and calcium thioglycolate modified biochar material (BCSS-SH);

[0015] In Step 1), the pyrolysis temperature of the straw is 700 °C, the nitrogen atmosphere, the heating rate is 10 °C / min, and the pyrolysis time is 2 h.

[0016] In Step 2), the mass of the steel slag is 25 g, the concentration of the dilute nitric acid is 5 mol / L, 35 mL is titrated and added, the stirring time is 24 h, the mass fraction of hydrogen peroxide is 15%, 17.5 mL is titrated and added, and the stirring time is 24 h.

[0017] In step 3), the ball milling medium is zirconia beads with a diameter range of 2 - 5 mm.

[0018] In step 3), the mass ratio of the biochar, steel slag, and calcium thioglycolate is 8:4:3; the ball milling speed is 300 rpm; the ball milling time is 12 h, and the sieve size is 100 mesh.

[0019] III. Application of the steel slag and calcium thioglycolate modified biochar material

[0020] The steel slag and calcium thioglycolate modified biochar material is applied to the treatment of composite polluted wastewater; the steel slag and calcium thioglycolate modified biochar material simultaneously removes tetracycline and cadmium.

[0021] The key to the technical solution of the present invention lies in loading the steel slag on the biochar, which increases the specific surface area of the biochar, introducing iron minerals to improve the oxidation and degradation ability of the biochar against antibiotics, enhancing the stability and reaction activity of the biochar, and at the same time recycling the waste steel slag; the added calcium thioglycolate introduces thiol functional groups to improve the heavy metal adsorption ability of the biochar.

[0022] Beneficial effects of the present invention:

[0023] (1) The present invention utilizes waste steel slag to achieve resource recycling; it has great economic benefits, and the cost of pretreating steel slag is 0.04878 yuan / g;

[0024] (2) The steel slag and calcium thioglycolate modified biochar material provided by the present invention simultaneously achieves the purpose of dual-functional modification of the biochar, which not only increases the specific surface area of the biochar to introduce thiol functional groups to adsorb heavy metals, but also introduces iron minerals to react with oxygen to provide oxidizing reactive oxygen species, effectively promoting the removal of tetracycline;

[0025] (3) The steel slag and calcium thioglycolate modified biochar material of the present invention can efficiently remove tetracycline and cadmium simultaneously;

[0026] (4) The preparation method of the steel slag and calcium thioglycolate modified biochar material provided by the present invention is simple, environmentally friendly, and can be synthesized on a large scale. Description of the drawings

[0027] Figure 1 For the examples of the present invention under the condition of 20 mg / L tetracycline, the removal effects of five materials (biochar (BC), pretreated steel slag (SS), and steel slag and calcium thioglycolate modified biochar materials with different ratios) on tetracycline;

[0028] Figure 2For the embodiments of the present invention, under the condition of 20 mg / L tetracycline, the removal change curves of tetracycline by three materials (biochar (BC), pretreated steel slag (SS), and steel slag and calcium thioglycolate modified biochar material (BCSS-SH));

[0029] Figure 3 For the embodiments of the present invention, under the conditions of 20 mg / L tetracycline and 20 mg / L cadmium ions, the removal change curves of tetracycline by three materials (biochar (BC), pretreated steel slag (SS), and steel slag and calcium thioglycolate modified biochar material (BCSS-SH));

[0030] Figure 4 For the embodiments of the present invention, under the condition of 20 mg / L cadmium ions, the removal change curves of cadmium ions by three materials (biochar (BC), pretreated steel slag (SS), and steel slag and calcium thioglycolate modified biochar material (BCSS-SH));

[0031] Figure 5 For the embodiments of the present invention, under the conditions of 20 mg / L tetracycline and 20 mg / L cadmium ions, the removal change curves of cadmium ions by three materials (biochar (BC), pretreated steel slag (SS), and steel slag and calcium thioglycolate modified biochar material (BCSS-SH));

[0032] Figure 6 XRD pattern of the material of the present invention. Detailed implementation manners

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. The following specific implementation manners further describe the present invention.

[0034] Unless otherwise specified, the reagents, materials, instruments, etc. used in the present invention can be obtained from commercial channels.

[0035] I. Preparation examples

[0036] Example 1

[0037] Dry the rice straw powder and transfer it to a tube furnace. Pyrolyze it under nitrogen conditions with a heating rate of 10 °C / min, a pyrolysis temperature of 700 °C, and a pyrolysis time of 2 h. After cooling to room temperature, wash the obtained material with deionized water multiple times and dry it in an oven to obtain biochar (BC).

[0038] Example 2

[0039] Mix 25 g of steel slag evenly with deionized water. Under stirring conditions, add 35 mL of 5 mol / L dilute nitric acid and 17.5 mL of 15% hydrogen peroxide solution to the steel slag particles in batches and drop them slowly, and react for 24 h respectively. After the reaction is complete, wash the obtained material with deionized water and perform centrifugation. After suction filtration, place it in an oven to dry to obtain pretreated steel slag (SS).

[0040] Example 3

[0041] Fully mix 2 g of biochar, 1 g of pretreated steel slag, and 0.75 g of calcium thioglycolate, place them in a ball mill tank, set the rotation speed of the ball mill to 300 rpm, and the ball milling time (including 6 h of forward rotation and 6 h of reverse rotation) to ensure that the biochar, pretreated steel slag, calcium thioglycolate, and zirconia beads in the ball mill tank are in full contact; after the ball milling program is completed, take out the material and sieve it through 100 mesh to obtain a steel slag and calcium thioglycolate modified biochar material (BCSS-SH) with a ratio of 8:4:3;

[0042] Example 4

[0043] Fully mix 2 g of biochar, 1 g of pretreated steel slag, and 1 g of calcium thioglycolate, place them in a ball mill tank, set the rotation speed of the ball mill to 300 rpm, and the ball milling time (including 6 h of forward rotation and 6 h of reverse rotation) to ensure that the biochar, pretreated steel slag, calcium thioglycolate, and zirconia beads in the ball mill tank are in full contact; after the ball milling program is completed, take out the material and sieve it through 100 mesh to obtain a steel slag and calcium thioglycolate modified biochar material with a ratio of 2:1:1;

[0044] Example 5

[0045] Fully mix 2 g of biochar, 1 g of pretreated steel slag, and 0.5 g of calcium thioglycolate, place them in a ball mill tank, set the rotation speed of the ball mill to 300 rpm, and the ball milling time (including 6 h of forward rotation and 6 h of reverse rotation) to ensure that the biochar, pretreated steel slag, calcium thioglycolate, and zirconia beads in the ball mill tank are in full contact; after the ball milling program is completed, take out the material and sieve it through 100 mesh to obtain a steel slag and calcium thioglycolate modified biochar material with a ratio of 4:2:1;

[0046] II. Application Examples

[0047] Application Example 1

[0048] Taking tetracycline as the target pollutant, a removal kinetics experiment was carried out. A 20 mg / L tetracycline solution was prepared. 20 mL of the solution was taken and placed in a brown bottle. 20 mg of the materials prepared in different examples, as well as biochar and pretreated steel slag, were added and mixed evenly. Then it was placed in a shaker at 260 rpm. Samples were taken at intervals, filtered through a membrane, and then placed in liquid-phase vials. The tetracycline concentration was measured using a high-performance liquid chromatograph. The mobile phase was acetonitrile and 0.01 mol / L oxalic acid (20:80, v / v), the flow rate was 1 mL / min, the column temperature was 25 °C, and the ultraviolet detection wavelength was 360 nm.

[0049] As Figure 1 shown, when the material ratio is 8:4:3, the effect is the best. The removal efficiencies of the materials in Example 4 and Example 5 are both below 60%. As Figure 2 shown, within 24 hours, the removal efficiency of BCSS-SH for tetracycline reaches more than 80%.

[0050] Application Example 2

[0051] Taking cadmium as the target pollutant, a removal kinetics experiment was carried out. A 20 mg / L cadmium ion solution was prepared. 20 mL of the solution was taken and placed in a brown bottle. 20 mg of the materials prepared in different examples, as well as biochar and pretreated steel slag, were added and mixed evenly. Then it was placed in a shaker at 260 rpm. Samples were taken at intervals, filtered through a membrane, and then transferred to a 2 mL centrifuge tube. It was diluted with a 2% nitric acid solution to below 0.2 mg / L in gradient. The cadmium ion concentration was measured using an inductively coupled plasma-mass spectrometer.

[0052] As Figure 4 shown, within about 2 hours, the removal efficiency of cadmium ions can reach 60%. Within 24 hours, the removal efficiency of cadmium ions can reach 90%.

[0053] Application Example 3

[0054] Taking tetracycline and cadmium as the target pollutants, a removal kinetics test was carried out. A mixed solution of 20 mg / L tetracycline and 20 mg / L cadmium ions was prepared. 20 mL of the solution was placed in a brown bottle. 20 mg of the materials prepared in different examples, as well as biochar and pretreated steel slag, were added and mixed evenly. Then it was placed in a shaker at 260 rpm. Samples were taken at intervals, filtered through a membrane, and then transferred to a liquid-phase vial and a centrifuge tube respectively. The concentrations of tetracycline and cadmium were measured using high-performance liquid chromatography and an inductively coupled plasma-mass spectrometer.

[0055] As Figure 3 and Figure 5 shown, in the composite pollution system, within 24 hours, the removal efficiency of tetracycline can reach about 80%, and the removal efficiency of cadmium ions can reach more than 85%. It can be seen that the steel slag and calcium thioglycolate-modified biochar materials prepared by the present invention have a high removal efficiency for tetracycline and cadmium.

Claims

1. A biochar material modified by steel slag and calcium thioglycolate, characterized in that: The steel slag and calcium thioglycolate modified biochar material is prepared from steel slag, calcium thioglycolate and biochar by ball milling.

2. The biochar material modified by steel slag and calcium thioglycolate according to claim 1, characterized in that: The steel slag is blast furnace slag, and the size is 0.075mm; The biochar precursor is rice straw.

3. A method for preparing a biochar material modified by steel slag and calcium thioglycolate according to any one of claims 1 to 2, characterized in that: The steps include: Step 1) washing the rice straw biomass raw material with deionized water to remove residual minerals, then drying the water, crushing it with a high-speed grinder, and sieving it for later use; taking the dried and sieved rice straw powder and placing it in a tubular furnace, pyrolyzing it under nitrogen conditions, cooling it to room temperature, washing it with deionized water for multiple times, and then drying it to obtain biochar; Step 2) the steel slag is uniformly mixed with deionized water, and under stirring conditions, diluted concentrated nitric acid and hydrogen peroxide solution are slowly added dropwise to the steel slag particles in sequence. After sufficient reaction, the steel slag is washed with deionized water for multiple times and then dried to obtain pretreated steel slag; Step 3) The biochar obtained in step 1) is fully mixed with the steel slag obtained in step 2) and calcium thioglycolate, and placed in a ball mill. The ball mill speed and ball milling time are set. After the ball milling process is completed, the material is taken out and sieved to obtain a steel slag and calcium thioglycolate modified biochar material.

4. The method for preparing the biochar material modified by steel slag and calcium thioglycolate according to claim 3, characterized in that: In the step 1), the pyrolysis temperature is 700° C., the heating rate is 10° C. / min, and the pyrolysis time range is 2 h.

5. The method for preparing the biochar material modified by steel slag and calcium thioglycolate according to claim 3, characterized in that: In the step 2), the mass of the steel slag is 25 g, the concentration of dilute nitric acid is 5 mol / L, 35 mL is titrated and the stirring time is 24 h, the mass fraction of hydrogen peroxide is 15%, 17.5 mL is titrated and the stirring time is 24 h.

6. The method for preparing biochar material modified by steel slag and calcium thioglycolate according to claim 3, characterized in that: In the step 1) and the step 2), the drying temperature is 80° C., the drying time is 24 hours, the washing medium is deionized water, and the washing times are at least three times.

7. The method for preparing biochar material modified by steel slag and calcium thioglycolate according to claim 3, characterized in that: In the step 3), the mass ratio of biochar, steel slag and calcium thioglycolate in the steel slag and calcium thioglycolate modified biochar material is 8:4:3; the ball milling speed is 300 rpm, the ball milling time is 12 hours, and the ball milling medium is zirconia beads with a diameter range of 2 to 5 mm.

8. The method for preparing biochar material modified by steel slag and calcium thioglycolate according to claim 3, characterized in that: In the step 3), the size of the sieve is 100 mesh.

9. The use of the biochar material modified by steel slag and calcium thioglycolate according to any one of claims 1 to 2, characterized in that: Biochar materials modified with steel slag and calcium thioglycolate are used in the treatment of composite polluted wastewater. Biochar materials modified with steel slag and calcium thioglycolate can simultaneously remove tetracycline and cadmium from composite polluted wastewater.

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