Modified biochar, preparation method, application and preparation equipment thereof

Abstract

The present application relates to the field of environmental protection and industrial emission reduction technology, and discloses a modified biochar, a preparation method, application and preparation equipment thereof.The modified biochar comprises a first modified biochar and a second modified biochar; the first modified biochar is a biochar modified by hydrochloric acid and has a particle size of 100-200 meshes; and the second modified biochar is a biochar loaded with iron oxide modified by microwaves and has a particle size of 250-500 meshes.The first modified biochar with a particle size of 100-200 meshes and the second modified biochar with a particle size of 250-500 meshes are used together, and the synergistic effect between the two is utilized to improve the adsorption effect of petroleum hydrocarbons in wastewater.

Description

Technical Field

[0001] This invention relates to the fields of environmental protection and industrial emission reduction technology, and in particular to a modified biochar, its preparation method, application and preparation equipment. Background Technology

[0002] Petroleum hydrocarbons, as common organic pollutants, readily combine with organic matter in soil, making them challenging to treat. Thermal desorption technology, a non-combustion technique, involves heating organic pollutants in the soil to a sufficient temperature through direct or indirect heat exchange under vacuum conditions or with a carrier gas. This allows the organic pollutants to volatilize or separate from the contaminated medium and enter the gas treatment system. Due to its advantages such as a wide range of pollutant treatment capabilities, mobile equipment, and the ability to reuse the remediated soil, it is widely used for the remediation of petroleum hydrocarbon-contaminated soils.

[0003] Steam extracted from soil using thermal desorption technology is condensed to form thermal desorption tailwater, which contains a large amount of petroleum hydrocarbons. Therefore, it is urgent to treat this petroleum hydrocarbon-containing wastewater. Commonly used remediation methods include biological, chemical, and physical methods. Among them, biological and chemical methods have problems such as secondary pollution, long cycle, complex operation, and high cost. In contrast, physical adsorption methods are widely used due to their advantages such as stable treatment effect, simple treatment process, and low cost.

[0004] Commonly used adsorbents include activated carbon, fly ash, diatomaceous earth, and zeolite; however, these substances have relatively low adsorption and separation capabilities, and their adsorption capacity needs further improvement. Although studies have explored ways to improve the adsorption effect of adsorbents through physical, chemical, and biological modifications, the effectiveness of modified adsorbent materials in treating petroleum hydrocarbons in wastewater still requires further enhancement. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a modified biochar, its preparation method, application, and preparation equipment for the efficient removal of petroleum hydrocarbons from wastewater.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing modified biochar includes the following steps: Step a: Mix biochar with hydrochloric acid solution, then heat and stir, wash, and filter to obtain the first modified biochar; Step b: Add biochar to iron ion solution, then add NaOH solution for co-precipitation reaction, filter, heat to decompose, and obtain biochar loaded with iron oxide; Step c: Microwave the iron oxide-loaded biochar at 2-3 GHz and 850-900 W for 3-5 min to obtain the second modified biochar; Step d: Mix the first modified biochar and the second modified biochar evenly to obtain the modified biochar; The particle size of the first modified biochar is 100-200 mesh. The particle size of the second modified biochar is 250-500 mesh.

[0007] Compared with the prior art, the present invention uses a first modified biochar with a particle size of 100-200 mesh and a second modified biochar with a particle size of 250-500 mesh in combination. The biochar modified with hydrochloric acid has a larger pore volume and specific surface area. The biochar loaded with iron oxides exhibits a better adsorption effect on petroleum hydrocarbons after microwave modification. By utilizing the synergistic effect between the two, the removal efficiency of petroleum hydrocarbons in wastewater is improved.

[0008] Optionally, the biochar is prepared by pyrolyzing at least one of corn, wheat, rice straw or rice husk at 650-750°C for 0.5-2.0 h in an inert atmosphere to obtain biochar.

[0009] Biochar prepared at pyrolysis temperatures of 650~750℃ has a larger specific surface area and more micropores, thus enhancing its adsorption capacity for petroleum hydrocarbons.

[0010] Optionally, in step d, the mass ratio of the first modified biochar to the second modified biochar is 5~15:1.

[0011] By limiting the mass ratio of the first modified biochar to the second modified biochar, the synergistic effect between the two is further improved, ensuring the removal efficiency of petroleum hydrocarbons from wastewater.

[0012] Optionally, in step a, the particle size of the first modified biochar is 140-150 mesh.

[0013] Optionally, in step b, the particle size of the second modified biochar is 300-325 mesh.

[0014] Optionally, in step a, the concentration of the hydrochloric acid solution is 1.0~2.0 mol / L.

[0015] Optionally, in step a, the heating and stirring temperature is 65~75℃ and the time is 2~3h.

[0016] Optionally, in step b, the iron ion solution is a mixed solution of FeCl2 and FeCl3.

[0017] Optionally, in step b, the molar ratio of FeCl2 to FeCl3 in the iron ion solution is 0.5 to 2:1.

[0018] Optionally, in step b, the coprecipitation reaction is carried out at 40-60°C for 20-40 minutes.

[0019] Optionally, in step b, the heating decomposition is performed at 200~500℃ for 0.5~2.0h.

[0020] Optionally, the inert atmosphere is at least one of nitrogen, helium, neon, or argon.

[0021] Optionally, the modified biochar can be washed with an acid solution of pH 1-2 after use and reused.

[0022] A second aspect of the present invention provides a modified biochar prepared by the above-described method for preparing modified biochar.

[0023] A third aspect of the present invention provides the application of the above-mentioned modified biochar in the treatment of petroleum hydrocarbon-containing wastewater.

[0024] The fourth aspect of the present invention provides an apparatus for preparing the above-mentioned modified biochar, comprising a first heating and stirring apparatus, a washing apparatus, a first filtering apparatus, a second heating and stirring apparatus, a second filtering apparatus, a pyrolysis apparatus, a microwave processing apparatus, and a stirring apparatus.

[0025] The modified biochar preparation equipment provided by this invention is easy to connect, making the modified biochar preparation process smooth and uninterrupted, which can effectively improve production efficiency. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] To better illustrate the present invention, further examples are provided below.

[0028] Example 1 This embodiment provides a method for preparing modified biochar, including the following steps: (1) Preparation of the first modified biochar: Corn stalks were pyrolyzed at 700℃ in a nitrogen atmosphere, then ground and passed through 140-mesh and 150-mesh sieves in sequence. The portion that passed through the 140-mesh sieve and did not pass through the 150-mesh sieve was taken as the first biochar. The first biochar was mixed with 1.5 mol / L hydrochloric acid solution, and then stirred at 70℃ for 2.5 h. After washing and filtration, the first modified biochar was obtained.

[0029] (2) Preparation of the second modified biochar: Corn stalks were pyrolyzed at 700℃ in a nitrogen atmosphere, then ground and passed through 300-mesh and 325-mesh sieves in sequence. The portion that passed through the 300-mesh sieve but not through the 325-mesh sieve was taken as the second biochar. 50g of the second biochar was dispersed in 300mL of 1mol / L FeCl3 and FeCl2 solution, and 100mL of 3mol / L NaOH solution was added. The mixture was reacted at 50℃ for 30min, filtered, and then reacted at 350℃ for 1.0h to obtain the second biochar loaded with iron oxides. The second biochar loaded with iron oxides was microwaved at 2.5GHz and 880W for 4min to obtain the second modified biochar.

[0030] (3) Take 150g of the first modified biochar and 15g of the second modified biochar and mix them to obtain modified biochar.

[0031] Example 2 This embodiment provides a method for preparing modified biochar, including the following steps: (1) Preparation of the first modified biochar: Wheat straw was pyrolyzed at 450℃ in an argon atmosphere, then ground and passed through 100-mesh and 115-mesh sieves in sequence. The portion that passed through the 100-mesh sieve and did not pass through the 115-mesh sieve was taken as the first biochar. The first biochar was mixed with 1.0 mol / L hydrochloric acid solution, and then stirred at 65℃ for 3 h. After washing and filtration, the first modified biochar was obtained.

[0032] (2) Preparation of the second modified biochar: Wheat straw was pyrolyzed at 700℃ in an argon atmosphere, then ground and passed through 250-mesh and 270-mesh sieves in sequence. The portion that passed through the 250-mesh sieve and did not pass through the 270-mesh sieve was taken as the second biochar. 50g of the second biochar was dispersed in 300mL of 0.5mol / L FeCl3 and FeCl2 solution, and 100mL of 1.5mol / L NaOH solution was added. The mixture was reacted at 40℃ for 40min, filtered, and then reacted at 200℃ for 2.0h to obtain the second biochar loaded with iron oxides. The second biochar loaded with iron oxides was microwaved at 2GHz and 850W for 5min to obtain the second modified biochar.

[0033] (3) Take 100g of the first modified biochar and 20g of the second modified biochar and mix them to obtain modified biochar.

[0034] Example 3 This embodiment provides a method for preparing modified biochar, including the following steps: (1) Preparation of the first modified biochar: Rice husks were pyrolyzed at 500℃ in a nitrogen atmosphere, then ground and passed through 180-mesh and 200-mesh sieves in sequence. The portion that passed through the 180-mesh sieve but did not pass through the 200-mesh sieve was taken as the first biochar. The first biochar was mixed with 2.0 mol / L hydrochloric acid solution, stirred at 75℃ for 2 h, washed, and filtered to obtain the first modified biochar.

[0035] (2) Preparation of the second modified biochar: Rice straw was pyrolyzed at 800℃ in a nitrogen atmosphere, then ground and passed through 400-mesh and 500-mesh sieves in sequence. The portion that passed through the 400-mesh sieve but not through the 500-mesh sieve was taken as the second biochar. 50g of the second biochar was dispersed in 210mL of 1.0mol / L FeCl3 and FeCl2 solution, and 70mL of 3.0mol / L NaOH solution was added. The mixture was reacted at 60℃ for 20min, filtered, and then reacted at 500℃ for 0.5h to obtain the second biochar loaded with iron oxides. The second biochar loaded with iron oxides was microwaved at 3GHz and 900W for 3min to obtain the second modified biochar.

[0036] (3) Take 150g of the first modified biochar and 10g of the second modified biochar and mix them to obtain modified biochar.

[0037] Example 4 This embodiment provides the above-mentioned modified biochar preparation equipment, including a first heating and stirring device, a washing device, a first filtering device, a second heating and stirring device, a second filtering device, a pyrolysis device, a microwave processing device, and a stirring device; The first heating and stirring device is connected to the washing device, the washing device is connected to the first filtering device, the first filtering device is connected to one connection port of the stirring device, the second heating and stirring device is connected to the second filtering device, the second filtering device is connected to the pyrolysis device, the pyrolysis device is connected to the microwave device, and the microwave processing device is connected to the other connection port of the stirring device.

[0038] Comparative Example 1 This comparative example provides a method for preparing modified biochar, including the following steps: Corn stalks were pyrolyzed at 700℃ in a nitrogen atmosphere, then ground and passed through 140-mesh and 150-mesh sieves. The portion that passed through the 140-mesh sieve but not the 150-mesh sieve was taken as the first biochar. The first biochar was mixed with a 1.5 mol / L hydrochloric acid solution, stirred at 70℃ for 2.5 h, washed, and filtered to obtain modified biochar.

[0039] Comparative Example 2 This comparative example provides a method for preparing modified biochar, including the following steps: Corn stalks were pyrolyzed at 700℃ under a nitrogen atmosphere, then ground and passed through 300-mesh and 325-mesh sieves sequentially. The portion passing through the 300-mesh sieve but not through the 325-mesh sieve was collected as the second biochar. 50g of the second biochar was dispersed in 300mL of 1mol / L FeCl3 and FeCl2 solutions, and 100mL of 3mol / L NaOH solution was added. The mixture was reacted at 50℃ for 30min, filtered, and then reacted at 350℃ for 1.0h to obtain the second biochar loaded with iron oxides. The second biochar loaded with iron oxides was microwaved at 2.5GHz and 880W for 4min to obtain modified biochar.

[0040] Comparative Example 3 This comparative example provides a method for preparing modified biochar, including the following steps: (1) The preparation method of the first modified biochar is the same as that in the example, and will not be repeated here.

[0041] (2) Preparation of the second modified biochar: Corn stalks were pyrolyzed at 700℃ in a nitrogen atmosphere, then ground and passed through 300-mesh and 325-mesh sieves in sequence. The portion that passed through the 300-mesh sieve and did not pass through the 325-mesh sieve was taken as the second biochar. 50g of the second biochar was dispersed in 300mL of 1mol / L FeCl3 and FeCl2 solution, and 100mL of 3mol / L NaOH solution was added. The mixture was reacted at 50℃ for 30min, filtered, and then reacted at 350℃ for 1.0h to obtain the second modified biochar.

[0042] (3) Take 150g of the first modified biochar and 15g of the second modified biochar and mix them to obtain modified biochar.

[0043] The modified biochar prepared in Examples 1-3 and Comparative Examples 1-3 were used to conduct experiments on the treatment of petroleum hydrocarbon-containing wastewater. The specific steps were as follows: 1.0 g of modified biochar was weighed and placed in a 100 mL Erlenmeyer flask. 10 mL of gasoline and 40 mL of water were added. The flask was placed in a shaker with a rotation speed of 135 r / min and a controlled temperature of 25 °C. Samples were taken after 10 min and 60 min, and the petroleum hydrocarbon removal rate in the samples was measured and calculated. The data are detailed in Table 1. Analysis of Table 1 shows that the biochar composite material provided by this invention can efficiently remove petroleum hydrocarbons from wastewater.

[0044] Table 1 The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing modified biochar, characterized in that, The process includes the following steps: Step a: Mix biochar with hydrochloric acid solution, then heat and stir, wash, and filter to obtain the first modified biochar; Step b: Add biochar to iron ion solution, then add NaOH solution for co-precipitation reaction, filter, heat to decompose, and obtain biochar loaded with iron oxide; Step c: Microwave the iron oxide-loaded biochar at 2-3 GHz and 850-900 W for 3-5 min to obtain the second modified biochar; Step d: Mix the first modified biochar and the second modified biochar evenly to obtain the modified biochar; The first modified biochar has a particle size of 100-200 mesh, and the second modified biochar has a particle size of 250-500 mesh.

2. The method for preparing modified biochar as described in claim 1, characterized in that, The biochar is prepared by pyrolyzing at least one of corn, wheat, rice straw or rice husk at 650-750℃ for 0.5-2.0h in an inert atmosphere to obtain biochar.

3. The method for preparing modified biochar as described in claim 1, characterized in that, In step d, the mass ratio of the first modified biochar to the second modified biochar is 5~15:

1.

4. The method for preparing modified biochar as described in claim 1, characterized in that, In step a, the particle size of the first modified biochar is 140-150 mesh; and / or In step b, the particle size of the second modified biochar is 300-325 mesh.

5. The method for preparing modified biochar as described in claim 1, characterized in that, In step a, the concentration of the hydrochloric acid solution is 1.0~2.0 mol / L; and / or In step a, the heating and stirring temperature is 65~75℃, and the time is 2~3h.

6. The method for preparing modified biochar as described in claim 1, characterized in that, In step b, the iron ion solution is a mixed solution of FeCl2 and FeCl3; and / or In step b, the molar ratio of FeCl2 to FeCl3 in the iron ion solution is 0.5 to 2:

1.

7. The method for preparing modified biochar as described in claim 1, characterized in that, In step b, the coprecipitation reaction is carried out at 40-60°C for 20-40 min; and / or In step b, the heating decomposition is performed at 200~500℃ for 0.5~2.0h.

8. A modified biochar, characterized in that, It is prepared by the method for preparing modified biochar according to any one of claims 1-7.

9. The application of the modified biochar according to any one of claims 8 in the treatment of petroleum hydrocarbon-containing wastewater.

10. An apparatus for preparing modified biochar according to claim 8, characterized in that, It includes a first heating and stirring device, a washing device, a first filtering device, a second heating and stirring device, a second filtering device, a pyrolysis device, a microwave processing device, and a stirring device; The first heating and stirring device is connected to the washing device, the washing device is connected to the first filtering device, the first filtering device is connected to one connection port of the stirring device, the second heating and stirring device is connected to the second filtering device, the second filtering device is connected to the pyrolysis device, the pyrolysis device is connected to the microwave device, and the microwave processing device is connected to the other connection port of the stirring device.

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