A method for preparing a magnetic Pb(II) adsorbent from coal slime

Abstract

The application belongs to the field of solid waste resource utilization and environmental protection, and particularly relates to a method for preparing a magnetic Pb(II) adsorbent from coal slime. The method comprises the following steps: mixing coal slime and red mud at a certain ratio, and then performing high-temperature carbonization under a nitrogen atmosphere to obtain the magnetic Pb(II) adsorbent. The method uses coal slime and red mud as raw materials, can realize efficient resource utilization of the coal slime and the red mud, and provides a new way for low-cost and efficient preparation of the magnetic Pb(II) adsorbent.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and environmental protection, and particularly relates to a method for preparing magnetic Pb(II) adsorbent using coal slime. Background Technology

[0002] my country has abundant coal resources, and coal slime is a solid waste generated during coal mining. Due to its high ash content and low calorific value, coal slime is difficult to use as a high-quality fuel. Currently, the conventional methods of disposal are combustion and stockpiling; however, combustion produces large amounts of CO2 and NO. X Red mud pollutes the atmosphere and contaminates soil and groundwater when piled up. On the other hand, as a major alumina producer in the world, my country's alumina industry has seen a surge in red mud production, a byproduct of alumina manufacturing. Red mud is complex in composition and possesses strong alkalinity and slight toxicity; its storage not only occupies land resources but also pollutes the environment. Therefore, achieving efficient and clean utilization of coal slime and red mud is crucial.

[0003] Red mud itself can be modified into adsorbent materials. For example, Chinese invention patent application CN110721655A discloses a method for preparing adsorbent materials by modifying red mud with acid treatment and iron salt solution. However, this method only uses red mud as raw material and iron from it as the iron source. Since the ash content of red mud usually exceeds 50% and the fixed carbon content is low, the prepared adsorbent has disadvantages such as excessively high ash content, unstable carbon structure, and a small number of active groups, making it difficult to become a highly efficient and multifunctional adsorbent. Because red mud is rich in iron and aluminum, it is one of the ideal raw materials for modified adsorbents. Chinese invention patent application CN113750962A discloses a method for preparing modified biochar by co-pyrolysis of red mud and Napier grass straw, and its application in treating heavy metal pollution in soil. This method involves mixing red mud and Napier grass straw, placing them in a high-temperature pyrolysis furnace, and obtaining a porous carbon material after high-temperature pyrolysis. This method is used to passivate heavy metals in soil but does not involve heavy metals in water bodies.

[0004] In summary, there is an urgent need to develop a method for the efficient synergistic utilization of coal slime and red mud to prepare an adsorbent for adsorbing heavy metals in water. Summary of the Invention

[0005] Based on the above background technology, the present invention provides a method for preparing magnetic Pb(II) adsorbents by synergistic use of coal slime (CS) and red mud (RM), in order to solve the current problems of high cost in preparing carbon materials and difficulty in resource utilization of coal slime and red mud.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention provides a method for preparing magnetic Pb(II) adsorbent using coal slime, which involves mixing coal slime and red mud in a certain proportion and then carbonizing them at high temperature under a nitrogen atmosphere to obtain magnetic Pb(II) adsorbent.

[0008] Furthermore, the mass ratio of coal slime to red mud is 1:10-10:1.

[0009] Furthermore, the high-temperature carbonization temperature is 400–900℃, the heating rate is 5℃ / min, and the time is 1–2h.

[0010] Furthermore, the nitrogen flow rate is 200 mL / min.

[0011] In another aspect, the present invention provides a magnetic Pb(II) adsorbent prepared by the aforementioned method.

[0012] In another aspect, the present invention provides the application of the magnetic Pb(II) adsorbent prepared by the aforementioned method in the treatment of wastewater containing Pb(II) ions.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] This invention uses coal slime and red mud to prepare a magnetic Pb(II) adsorbent, which can effectively utilize industrial waste, achieving both waste reduction and resource recovery, and realizing the goal of "treating waste with waste". The iron source for the preparation of traditional magnetic materials is mostly iron salts and other chemical agents, which is costly. Taking advantage of the high iron mineral content in red mud, the magnetic Pb(II) adsorbent prepared from red mud avoids the need for an external iron source, thus reducing costs. Combined with the high carbon content in coal slime, coal slime and red mud can be pyrolyzed at high temperature in an oxygen-free environment to form a new type of magnetic Pb(II) adsorbent. Its iron element is mostly in the form of magnetite, which is magnetic and conducive to recycling and reuse in environmental pollution control. Attached Figure Description

[0015] Figure 1 XRD patterns of carbonization products of coal slime:red mud = 3:1 at 400-900℃;

[0016] Figure 2 XPS plots of the adsorbent prepared in Example 1, (a) C1s, (b) Fe2p;

[0017] Figure 3 FTIR spectra of the adsorbents prepared in Example 1 and Comparative Example 1;

[0018] Figure 4 This is a comparison chart of the VSM of the adsorbents prepared in Example 1 and Comparative Example 1.

[0019] Figure 5The graph shows a comparison of the adsorption effects of the adsorbents prepared in Examples 1-6 and Comparative Examples 1-6 on Pb(II). Detailed Implementation

[0020] To facilitate understanding of the present invention, a more complete description will be given below in conjunction with embodiments and accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0021] Example 1

[0022] After mixing coal slime and red mud in a 3:1 ratio, the mixture was placed in a quartz boat and then placed in a high-temperature tube furnace. Under a nitrogen atmosphere (nitrogen flow rate of 200 mL / min), the temperature was increased to 800℃ at a rate of 5℃ / min, and the carbonization reaction was carried out for 1 hour. After the reaction was completed, the mixture was cooled to room temperature and removed to obtain the modified magnetic Pb(II) adsorbent material, denoted as R1C3-C8(60).

[0023] Examples 2-6

[0024] The preparation method is the same as in Example 1, except that the carbonization reaction temperatures are 400℃, 500℃, 600℃, 700℃ and 900℃ respectively, and the materials obtained are denoted as R1C3-C4(60), R1C3-C5(60), R1C3-C6(60), R1C3-C7(60) and R1C3-C9(60) respectively.

[0025] The adsorbents prepared in Examples 1-6 were subjected to XRD tests, such as... Figure 1 As shown, under conditions of 600℃, 700℃ and 800℃, the XRD spectra of the adsorbent material were compared with the standard XRD spectra of magnetite (ICDD-01-088-0315). It was found that four typical characteristic peaks appeared at 2θ=30.3°, 35.6°, 57.5° and 62.8°, which are basically consistent with the characteristic peak positions in the standard XRD spectra of magnetite, proving the presence of magnetite.

[0026] The adsorbent prepared in Example 1 was subjected to XPS analysis for C1s and Fe2p: as follows Figure 2 As shown in (a), the C in the adsorbent exists in the forms of C=O, C—O / C—O—C, and C—C; as Figure 2 As shown in (b), Fe3O4 is present in the adsorbent.

[0027] Comparative Example 1

[0028] Coal slime was placed in a quartz boat and placed in a high-temperature tube furnace. Under a nitrogen atmosphere (nitrogen flow rate of 200 mL / min), the temperature was increased to 800℃ at a heating rate of 5℃ / min and the pyrolysis reaction was carried out for 1 hour at a heating rate of 5℃ / min. After the reaction was completed, the mixture was cooled to room temperature to obtain the coal slime magnetic Pb(II) adsorbent material, denoted as C10-C8(60).

[0029] The adsorbents prepared in Comparative Example 1 and Example 1 were analyzed by FTIR: Figure 3 Infrared spectra of Example 1 and Comparative Example 1 showed similar overall trends and the positions of characteristic peaks, indicating that their basic frameworks and structural units are essentially the same. The main functional groups include -OH, C≡C, C=O, C=C, and CO, which is consistent with C1s spectrum analysis; 1050-990 cm⁻¹ -1 Exhibits Si-O stretching vibrations; at 800 and 458 cm⁻¹ -1 These correspond to the symmetric and torsional vibrations of the Si-O-Si bond, respectively; Example 1 was performed at 563 cm⁻¹. -1 It exhibits characteristic peaks of Fe-O stretching vibration.

[0030] The adsorbents prepared in Comparative Example 1 and Example 1 were subjected to hysteresis loop tests: (e.g.) Figure 4 As shown, the addition of red mud can enhance magnetism.

[0031] Comparative Examples 2-6

[0032] The preparation method is the same as that of Comparative Example 1, except that the carbonization reaction temperatures are 400℃, 500℃, 600℃, 700℃ and 900℃ respectively, and the materials obtained are denoted as C10-C4(60), C10-C5(60), C10-C6(60), C10-C7(60) and C10-C9(60) respectively.

[0033] Take 0.025 g of each of the adsorbent materials from Comparative Examples 1-6 and Examples 1-6, and place them together with 25 mL of a Pb(II) ion solution in an Erlenmeyer flask. The initial Pb(II) ion concentration is 100 mg / L, and the pH is 4.5. Then place the Erlenmeyer flask in a constant temperature shaker at T = 25°C, r = 200 rpm, and shake for t = 120 min. Remove the flask and centrifuge the mixture, collecting the supernatant.

[0034] The supernatant was collected and the Pb(II) content in the liquid was determined according to GB 37883-2019. The Pb(II) removal rate (η) and adsorption capacity (q) were also measured. e, (mg / g) is calculated according to the following formula:

[0035]

[0036]

[0037] Where: C0, C t The initial mass concentration of Pb(II) ions in the solution and the remaining mass concentration at adsorption time t are respectively (mg / L); V is the solution volume (L); and m is the mass of the adsorbent (g).

[0038] Depend on Figure 5 It can be seen that the adsorbent prepared in Comparative Example 1 achieved a Pb(II) removal rate of 44.96%, with an adsorption capacity of 42.11 mg / g; the adsorbent prepared in Example 1 achieved a Pb(II) removal rate of 73.58%, with an equilibrium adsorption capacity of 69.19 mg / g. These results indicate that the addition of red mud can improve the Pb(II) adsorption performance of the adsorbent compared to adsorbent materials prepared from pure coal slime.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. The application of magnetic Pb(II) adsorbent in the treatment of wastewater containing Pb(II) ions, characterized in that, The preparation method of the magnetic Pb(II) adsorbent includes: mixing coal slime and red mud in a certain proportion, and then carbonizing them at high temperature under a nitrogen atmosphere to obtain the magnetic Pb(II) adsorbent. The mass ratio of coal slime to red mud is 1:10-10:1; The high-temperature carbonization temperature is 400~900℃, the heating rate is 5℃ / min, and the time is 1~2h; The nitrogen flow rate is 200 mL / min.

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