Modified coal gangue / biochar composite adsorption material and preparation method thereof

Abstract

The invention belongs to the technical field of solid waste resource utilization, and discloses a modified coal gangue / charcoal composite adsorption material and a preparation method thereof.The preparation method comprises the steps that S1, coal gangue powder is fired at high temperature, and activated coal gangue powder is obtained after natural cooling; s2, immersing the biochar in a concentrated sulfuric acid solution for activating treatment, and cleaning and drying after treatment to obtain activated biochar; s3, immersing the activated coal gangue powder and the activated biochar in a ferric salt solution in proportion, then heating for 30 minutes under 280W microwave radiation, taking out a sample, cleaning and drying to obtain the modified coal gangue / biochar composite adsorption material. In conclusion, the micron-sized coal gangue is loaded on the surface and in pores of the corncob activated carbon by utilizing a microwave hydrothermal method, so that the prepared modified coal gangue / biochar composite adsorption material can give full play to the advantages of the biochar material and the coal gangue, the adsorption capacity of the modified coal gangue / biochar composite adsorption material is improved, and the basic physical properties of the material are enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to a modified coal gangue / biochar composite adsorption material and a preparation method thereof. Background Art

[0002] The amount of gangue waste generated in the coal production process will also increase day by day, and gangue itself is a natural resource that can be developed and utilized, so the resource utilization of gangue is very important. According to existing research, gangue contains silicon, aluminum, iron and other elements, which can easily form a stable three-dimensional skeleton structure, making it hard and wear-resistant, and able to adapt to a variety of environments.

[0003] Biochar is different from traditional charcoal, which is generally used as fuel. It is produced by pyrolysis of biomass in a low-air environment. The biochar produced by the reaction has a certain pore structure, functional groups and surface interface reaction. Therefore, biochar can be used in various fields such as soil remediation, wastewater treatment, and chemical recycling. However, for biochar prepared from lignocellulosic plants as biomass sources, due to its own brittleness and porosity, the material has the defect of poor compressive strength.

[0004] In summary, the applicant proposes in the present invention a composite adsorption material capable of comprehensively utilizing coal gangue and biochar and a preparation method thereof. Summary of the invention

[0005] In view of this, in order to solve the problems raised in the above background technology, the purpose of the present invention is to provide a modified coal gangue / biochar composite adsorption material and a preparation method thereof.

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

[0007] A method for preparing a modified gangue / biochar composite adsorption material, comprising:

[0008] S1. sintering coal gangue powder at high temperature and obtaining activated coal gangue powder after natural cooling;

[0009] S2. immersing the biochar in a concentrated sulfuric acid solution for activation treatment, and washing and drying the biochar to obtain activated biochar;

[0010] S3. Immerse activated gangue powder and activated biochar in an iron salt solution in proportion, and then heat them under 280 W microwave radiation for 30 minutes. Take out the sample, wash it, and dry it to obtain a modified gangue / biochar composite adsorption material.

[0011] Preferably, the step of obtaining the coal gangue powder comprises: washing the coal gangue with distilled water for 2 to 3 times, baking in an oven at 45° C. for 24 hours, crushing, passing through a 2000-mesh sieve, and taking the sieve-through as the coal gangue powder.

[0012] Preferably, the high temperature firing comprises: placing the coal gangue powder in a muffle furnace at 600° C. and firing for 2 hours.

[0013] Preferably, the step of obtaining the biochar comprises:

[0014] The corncob biomass was cleaned, baked in an oven at 45°C for 24 h, and then placed in a pyrolysis reactor to obtain corncob biochar;

[0015] The corncob biochar with a particle size of 2 to 5 mm was crushed and screened for drying and storage.

[0016] Preferably, the pyrolysis firing temperature of the pyrolysis reactor is 650° C., and the pyrolysis firing time is 2 hours.

[0017] Preferably, the concentration of the concentrated sulfuric acid solution is 18 mol / L, the activation treatment temperature of the biochar is 40° C., and the activation treatment time is 2 h.

[0018] Preferably, after the activation treatment, the biochar is washed with ultrapure water for 2 to 3 times, and then placed in a 45° C. oven for baking for 24 hours to obtain activated biochar.

[0019] Preferably, in step S3:

[0020] Activated coal gangue powder and activated biochar were immersed in an iron salt solution at a mass ratio of 1:2;

[0021] The solution was added to a hydrothermal reactor and then placed in a microwave reactor;

[0022] The samples were taken out after heating under microwave radiation at 280 W for 30 min;

[0023] The sample was rinsed with distilled water for 2 to 3 times and then baked in an oven at 45°C for 24 h to obtain a modified coal gangue / biochar composite adsorption material.

[0024] Preferably, the iron salt solution is a mixed solution of ferric chloride and ferrous chloride in a molar ratio of 1:1, and the concentrations of the ferric chloride and ferrous chloride solutions are both 0.5 mol / L.

[0025] The present invention also provides a modified coal gangue / biochar composite adsorption material prepared by the above preparation method.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention utilizes a microwave hydrothermal method to load micron-sized coal gangue on the surface and pores of corn cob activated carbon, thereby enabling the prepared modified coal gangue / biochar composite adsorption material to give full play to the advantages of biochar materials and coal gangue, improve its adsorption capacity and enhance the basic physical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The SEM photos of activated biochar and modified gangue / biochar composite adsorption materials at different magnifications;

[0029] Figure 2 This is the mapping diagram of iron and aluminum elements for the modified coal gangue / biochar composite adsorption material;

[0030] Figure 3 This is a table of pore structure parameters of biochar and modified coal gangue / biochar composite adsorption materials;

[0031] Figure 4 This is the isothermal adsorption fitting diagram of biochar and modified coal gangue / biochar composite adsorption material. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] A method for preparing a modified gangue / biochar composite adsorption material, comprising:

[0034] S1. Rinse the gangue with distilled water for 2 to 3 times, bake in an oven at 45°C for 24 hours, crush, pass through a 2000-mesh sieve, and take the sieve residue as gangue powder;

[0035] S2. The gangue powder is placed in a muffle furnace at 600°C, fired for 2h, and then naturally cooled to obtain activated gangue powder;

[0036] S3. Wash the corn cob biomass, bake it in an oven at 45°C for 24 hours, and then place it in a pyrolysis reactor and burn it at 650°C for 2 hours to obtain corn cob biochar; crush and select the corn cob biochar with a particle size of 2 to 5 mm for drying and storage;

[0037] S4. The dried biochar was immersed in a concentrated sulfuric acid solution with a concentration of 18 mol / L, heated to 40°C for 2 hours for activation treatment, washed with ultrapure water 2 to 3 times after treatment, and then placed in a 45°C oven for 24 hours to obtain activated biochar;

[0038] S5. Prepare an iron salt solution by mixing 0.5 mol / L ferric chloride solution with 0.5 mol / L ferrous chloride solution;

[0039] S6. Immerse activated gangue powder and activated biochar in an iron salt solution at a mass ratio of 1:2; add the solution into a hydrothermal reactor and then put it into a microwave reactor; take out the sample after heating under 280 W microwave radiation for 30 minutes; rinse the sample with distilled water 2 to 3 times and bake it in an oven at 45°C for 24 hours to obtain a modified gangue / biochar composite adsorption material.

[0040] (1) The activated biochar and modified gangue / biochar composite adsorption materials prepared above were analyzed as follows:

[0041] Figure 1 The SEM photos of activated biochar and modified gangue / biochar composite adsorption materials at different magnifications. Among them, a and b are SEM photos of activated biochar, and c and d are SEM photos of modified gangue / biochar composite adsorption materials. It can be seen from the figure that there are many tiny particles attached to the surface of the modified gangue / biochar composite adsorption material, which shows that the gangue powder has completed the attachment to the surface of the activated biochar.

[0042] Figure 2 This is the mapping diagram of the iron and aluminum elements of the modified gangue / biochar composite adsorption material. As can be seen from the figure, the distribution of Fe and Al elements on the surface of the modified gangue / biochar composite adsorption material is dispersed, and no obvious aggregated particles are seen, which is conducive to increasing the adsorption points and thus improving the adsorption capacity. Among them, Al is the main component of gangue, which further shows that gangue is loaded on the surface of biochar.

[0043] Figure 3 The pore structure parameter table of biochar and modified gangue / biochar composite adsorption material. As can be seen from the figure, the total specific surface area of ​​the modified gangue / biochar composite adsorption material is 3.8 times higher than that of corn cob biochar (CCBC), and the total pore volume is 3.3 times higher, and the total specific surface area is 1.5 times higher than that of activated biochar (Fe@CCBC), and the total pore volume is 1.4 times higher. It can be seen that the modification of metal salts and acids greatly increases the specific surface area and total pore volume of carbon, making it have a developed pore structure and creating a large number of adsorption sites on the surface of the material.

[0044] (2) Isothermal adsorption experiments on biochar and modified gangue / biochar composite adsorption materials:

[0045] 0.1 g corn cob biochar (CCBC), activated biochar (Fe@CCBC) and modified coal gangue / biochar composite adsorption material (coal gangue / Fe@CCBC) were weighed into 6 experimental bottles respectively, and 100 mL of six gradient mixed solutions were added in sequence. The mixture was oscillated at constant temperature for 12 h under the conditions of pH = 7, T = 25 °C, and speed = 180 r / min. The As and F ion concentrations in the filtrate were filtered, diluted and determined.

[0046] The following table 1 shows six gradient mixed solutions:

[0047] Solution concentration gradient As concentration (mg / L) F concentration (mg / L) 1 1 5 2 5 25 3 10 50 4 20 100 5 30 150 6 50 200

[0048] The following table 2 shows the isothermal adsorption test results of As ions

[0049]

[0050] The following table 3 shows the isothermal adsorption test results of F ions

[0051]

[0052] Based on Tables 2 and 3 above, it can be seen that the adsorption of As and F by each material is: gangue / Fe@CCBC>Fe@CCBC>CCBC. This shows that gangue / Fe@CCBC has a large specific surface area and total pore volume, a small average pore size, and more adsorption sites on the surface, so the adsorption capacity is the highest. The maximum unit adsorption capacity of gangue / Fe@CCBC for As and F is 20.25 mg / g and 31.53 mg / g.

[0053] in addition, Figure 4 The adsorption isotherms of the original biochar (CCBC) and two modified biochars (Fe@CCBC and gangue / Fe@CCBC) are fitted using the Langmuir model and the Freundlich model. It can be clearly seen from the figure that among the three materials, gangue / Fe@CCBC has the best adsorption effect. The R 2 Both are greater than the R after fitting using the Freundlich model 2 This indicates that the material's adsorption process for arsenic and fluorine is more inclined to single-layer adsorption, which is an adsorption process that is uniformly adsorbed on the surface.

[0054] (3) Conduct isothermal adsorption experiments on existing materials

[0055] Table 4 shows the adsorption capacity of As and F ions by different existing adsorption materials.

[0056]

[0057]

[0058] Based on Tables 2, 3 and 4 above, it can be seen that the modified gangue / biochar composite adsorption material (gangue / Fe@CCBC) has a good adsorption effect on As and F, especially under the premise of composite adsorption of As and F, it shows a good comprehensive performance of removing both As and F pollutants at the same time.

[0059] The data in Table 4 above refer to<Anchoring Al-andor Mg-oxides to magnetic biochars forCo-uptake of> ,<Novel aluminium(hydr)oxide-functionalized activated carbonderived> ,<One-step synthesis of zirconium dioxide-biochar derived fromCamellia> ,<Removal of arsenic and fluoride from aqueous solution by biomassbased> , <As(Ⅲ) adsorption performance and mechanism of natural iron-containing manganese ore with different Mn_Fe ratios>, <Enhanced defluorination effect of simulated wastewater by aluminum-cerium loaded sludge biochar>, <Study on the adsorption characteristics of arsenic and cadmium by lanthanum modified biochar>, <Study on the adsorption effect and mechanism of arsenic by iron-based modified coconut shell biochar> and other literature.

[0060] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a modified gangue / biochar composite adsorption material, characterized in that: include: S1. sintering coal gangue powder at high temperature and obtaining activated coal gangue powder after natural cooling; S2. immersing the biochar in a concentrated sulfuric acid solution for activation treatment, and washing and drying the biochar to obtain activated biochar; S3. Immerse activated gangue powder and activated biochar in an iron salt solution in proportion, and then heat them under 280 W microwave radiation for 30 minutes. Take out the sample, wash it, and dry it to obtain a modified gangue / biochar composite adsorption material.

2. The method for preparing the modified gangue / biochar composite adsorption material according to claim 1, characterized in that: The steps of obtaining the coal gangue powder include: Rinse the gangue with distilled water for 2 to 3 times, bake in an oven at 45°C for 24 hours, crush, pass through a 2000-mesh sieve, and take the material under the sieve as gangue powder.

3. The method for preparing the modified gangue / biochar composite adsorption material according to claim 2, characterized in that: The high temperature firing comprises: The coal gangue powder was placed in a muffle furnace at 600° C. and fired for 2 hours.

4. The method for preparing the modified gangue / biochar composite adsorption material according to claim 1, characterized in that: The steps of obtaining the biochar include: The corncob biomass was cleaned, baked in an oven at 45°C for 24 h, and then placed in a pyrolysis reactor to obtain corncob biochar; The corncob biochar with a particle size of 2 to 5 mm was crushed and screened for drying and storage.

5. The method for preparing the modified gangue / biochar composite adsorption material according to claim 4, characterized in that: The pyrolysis firing temperature of the pyrolysis reactor is 650° C., and the pyrolysis firing time is 2 hours.

6. The method for preparing the modified gangue / biochar composite adsorption material according to claim 1, characterized in that: The concentration of the concentrated sulfuric acid solution is 18 mol / L, the activation treatment temperature of the biochar is 40° C., and the activation treatment time is 2 h.

7. The method for preparing the modified gangue / biochar composite adsorption material according to claim 6, characterized in that: After the activation treatment, the biochar was washed with ultrapure water for 2 to 3 times, and then placed in a 45° C. oven for baking for 24 hours to obtain activated biochar.

8. The method for preparing the modified gangue / biochar composite adsorption material according to claim 1, characterized in that: Activated coal gangue powder and activated biochar were immersed in an iron salt solution at a mass ratio of 1:2; The solution was added to a hydrothermal reactor and then placed in a microwave reactor; The samples were taken out after heating under microwave radiation at 280 W for 30 min; The sample was rinsed with distilled water for 2 to 3 times and then baked in an oven at 45°C for 24 h to obtain a modified coal gangue / biochar composite adsorption material.

9. The method for preparing the modified gangue / biochar composite adsorption material according to claim 8, characterized in that: The iron salt solution is a mixed solution of ferric chloride and ferrous chloride in a molar ratio of 1:1, and the concentrations of the ferric chloride and ferrous chloride solutions are both 0.5 mol / L.

10. A modified coal gangue / biochar composite adsorption material prepared by the preparation method according to any one of claims 1 to 9.

Images