Preparation method and application of biomass ash-based zeolite molecular sieve adsorbent

Abstract

The invention provides a preparation method and application of a biomass ash-based zeolite molecular sieve adsorbent, and relates to the field of solid waste utilization. The preparation method of the biomass ash-based zeolite molecular sieve adsorbent comprises the following steps: crushing and grinding biomass ash, uniformly mixing with sodium hydroxide, roasting in a muffle furnace to obtain biomass ash clinker, mixing the biomass ash clinker with deionized water, stirring, and aging to obtain aged slurry; carrying out hydrothermal reaction on the aged slurry, separating out solid precipitate, and drying to finally obtain the biomass ash-based zeolite molecular sieve adsorbent. The method overcomes the defects in the prior art, the ash of a biomass power plant is used as a raw material, the zeolite molecular sieve with excellent adsorption performance is prepared through alkali fusion roasting activation and hydrothermal synthesis, and the zeolite molecular sieve has good lead ion adsorption performance.

Description

Technical Field

[0001] The invention relates to the field of solid waste utilization, and in particular to a preparation method and application of a biomass ash-based zeolite molecular sieve adsorbent. Background Art

[0002] Biomass ash is the main residue after biomass combustion or pyrolysis, mainly from the combustion process of biomass power plants, agricultural waste (such as straw, rice husk) and forestry waste. With the rapid development of biomass energy utilization, the amount of biomass ash generated has increased year by year, and the current consumption of biomass ash is not enough to completely absorb its generation. Therefore, exploring the resource utilization of biomass ash is of great significance for environmental protection and sustainable development.

[0003] Zeolite molecular sieve is a kind of porous crystalline material with regular pore structure, mainly composed of silicon, aluminum, oxygen and other elements, and can separate and purify molecules through ion exchange, adsorption or catalysis. It has a regular pore structure and can selectively adsorb according to molecular size, polarity, shape, etc., and is widely used in petrochemical, environmental protection (such as gas adsorption), detergent and other fields. However, although the synthesis of zeolite with chemicals can obtain zeolite with higher purity, its cost is expensive, and some methods (such as solvothermal method) use organic solvents, which may produce wastewater or waste gas and require additional treatment. Zeolite is usually composed of silicon and aluminum elements, and the silicon and aluminum content in biomass ash is relatively high, which is a potential raw material for the preparation of zeolite. At present, there is no product that uses biomass ash to prepare zeolite molecular sieves. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a preparation method and application of a biomass ash-based zeolite molecular sieve adsorbent, and uses biomass ash as a raw material to prepare a NaX type zeolite molecular sieve. It is applied to the adsorption of lead ions in a solution to purify lead-containing wastewater, and can also broaden the resource utilization of biomass ash.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented through the following technical solutions:

[0006] A method for preparing a biomass ash-based zeolite molecular sieve adsorbent, the preparation method comprising the following steps:

[0007] (1) crushing and grinding the biomass ash and then mixing it with sodium hydroxide, and then roasting them together in a muffle furnace to obtain biomass ash clinker;

[0008] (2) mixing the biomass ash clinker with deionized water, stirring and aging to obtain an aged slurry for later use;

[0009] (3) subjecting the aged slurry to a hydrothermal reaction, separating and drying the solid precipitate after the reaction, and obtaining a biomass ash-based zeolite molecular sieve adsorbent.

[0010] Preferably, in step (1), the biomass ash is crushed and ground to a size of 200 mesh or more.

[0011] Preferably, in step (1), the mass ratio of biomass ash to sodium hydroxide is 1:0.25-2.

[0012] Preferably, the calcination temperature in step (1) is 400-800° C., and the calcination time is 0.5-3 h.

[0013] Preferably, in step (2), the ratio of biomass ash clinker to deionized water is 1 mL: 5-20 g.

[0014] Preferably, the stirring aging time in step (2) is 1-8 hours.

[0015] Preferably, the temperature of the hydrothermal reaction in step (3) is 80-120° C., and the reaction time is 16-30 h.

[0016] Preferably, the method of separating the solid in step (3) is centrifugation or filtration.

[0017] Preferably, the drying method in step (3) is at a temperature of 80-120° C. for 8-16 hours.

[0018] The biomass ash-based zeolite molecular sieve adsorbent is used for adsorbing lead ions.

[0019] The present invention provides a preparation method of a biomass ash-based zeolite molecular sieve adsorbent and its application, which has the following advantages over the prior art:

[0020] (1) The present invention uses biomass ash as raw material, and prepares a zeolite molecular sieve adsorbent with a large specific surface area and excellent adsorption performance through alkali fusion roasting activation and hydrothermal synthesis, thereby simplifying the traditional preparation process;

[0021] (2) The present invention uses industrial solid waste biomass ash as raw material, reduces the amount of chemical raw materials used in zeolite preparation, reduces costs, and also reduces the emission of harmful substances in traditional processes, which is in line with the concept of green chemistry. It broadens the resource utilization of biomass ash and alleviates the pressure of management and disposal of biomass ash;

[0022] (3) The zeolite molecular sieve prepared by the present invention can be applied to the fields of environmental catalysis and adsorption. The prepared biomass ash-based zeolite molecular sieve has excellent lead ion adsorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The process flow chart of the preparation of the zeolite molecular sieve adsorbent of the present invention;

[0024] Figure 2 is the X-ray diffraction pattern of the zeolite molecular sieve adsorbent in Example 1 of the present invention;

[0025] Figure 3 is a scanning electron microscope image of the zeolite molecular sieve adsorbent in Example 1 of the present invention;

[0026] Figure 4 is the nitrogen adsorption-desorption curve of the zeolite molecular sieve adsorbent in Example 1 of the present invention;

[0027] Figure 5 This is a pore size distribution diagram of the zeolite molecular sieve adsorbent in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0029] Embodiment 1:

[0030] Preparation method of biomass ash-based zeolite molecular sieve:

[0031] (1) crushing and grinding the biomass ash, passing it through a 200-mesh sieve, taking 5 g of the crushed and ground biomass ash, mixing the biomass ash with sodium hydroxide (NaOH) in a mass ratio of 1:1, placing the mixture in a nickel crucible, and calcining the mixture in a muffle furnace at 550° C. for 1 h to obtain biomass ash clinker;

[0032] (2) Transfer the biomass ash clinker to a beaker, add 50 mL of deionized water, and age it for 4 h using magnetic stirring to obtain an aged slurry;

[0033] (3) The aged slurry was transferred to a hydrothermal reactor and placed in an oven for hydrothermal reaction at 90°C for 24 hours. After the reaction, the reactor was cooled to room temperature, the solid product was separated by centrifugation, and dried in an oven at 105°C for 12 hours to obtain a biomass ash-based zeolite molecular sieve.

[0034] The zeolite molecular sieve adsorbent prepared in this example was subjected to X-ray diffraction detection, and the results were as follows: Figure 2 As shown in the figure, it can be seen that under X-ray diffraction detection, the zeolite molecular sieve adsorbent prepared in this example has obvious characteristic peaks, indicating that the zeolite molecular sieve is successfully prepared.

[0035] The zeolite molecular sieve adsorbent prepared in this example was examined by scanning electron microscopy, and the electron microscope image thereof is as follows: Figure 3 As shown in the figure, it can be seen that the biomass ash-based zeolite molecular sieve adsorbent prepared in this embodiment presents an octahedral shape.

[0036] The zeolite molecular sieve adsorbent prepared in this example was subjected to nitrogen adsorption and desorption tests. Figure 4 and Figure 5 are nitrogen adsorption-desorption curve and pore size distribution diagram, respectively. Figure 4 and Figure 5 It can be seen that the zeolite molecular sieve contains a large number of microporous structures with a pore volume of 0.387 cm 3 / g, specific surface area is 281.023m 2 / g

[0037] Embodiment 2:

[0038] Referring to the preparation method of Example 1 above, the ratio of biomass ash to sodium hydroxide in step (1) is controlled as shown in Table 1 below to prepare different groups of biomass ash-based zeolite molecular sieves:

[0039] Table 1

[0040]

[0041] Detection:

[0042] The adsorption of lead ions by the biomass ash-based zeolite molecular sieves prepared in Example 1 and Experimental Groups 1-5 was tested:

[0043] The obtained biomass ash-based zeolite molecular sieve was used to adsorb lead ions in the solution. When the initial concentration of lead ions was 100 mg / L, various adsorbents were added at 0.5 g / L, stirred and mixed, and the adsorbents were separated. The lead ion concentration in the solution was detected, and the removal rate of lead ions and the adsorption amount of lead ions by the biomass ash-based zeolite molecular sieve were calculated. The specific results are shown in Table 2 below:

[0044] Table 2

[0045] Group Lead ion removal rate (%) Adsorption capacity of lead ions by molecular sieve (mg / g) Example 1 98.53％ 197.06mg / g Experimental Group 1 89.43％ 178.12mg / g Experimental Group 2 98.26％ 196.51mg / g Experimental Group 3 98.55％ 197.11mg / g Experimental Group 4 98.56％ 197.11mg / g Experimental Group 5 98.47％ 196.93mg / g

[0046] It can be seen from the above table that each group of biomass ash-based zeolite molecular sieves has a good adsorption effect on lead ions in the solution.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a biomass ash-based zeolite molecular sieve adsorbent, characterized in that: The preparation method comprises the following steps: (1) crushing and grinding the biomass ash and then mixing it with sodium hydroxide, and then roasting them together in a muffle furnace to obtain biomass ash clinker; (2) mixing the biomass ash clinker with deionized water, stirring and aging to obtain an aged slurry for later use; (3) subjecting the aged slurry to a hydrothermal reaction, separating and drying the solid precipitate after the reaction, and obtaining a biomass ash-based zeolite molecular sieve adsorbent.

2. The preparation method according to claim 1, characterized in that: In the step (1), the biomass ash is crushed and ground to a size of 200 mesh or more.

3. The preparation method according to claim 1, characterized in that: In the step (1), the mass ratio of biomass ash to sodium hydroxide is 1:0.25-2.

4. The preparation method according to claim 1, characterized in that: The calcination temperature in step (1) is 400-800° C., and the calcination time is 0.5-3 h.

5. The preparation method according to claim 1, characterized in that: In the step (2), the ratio of biomass ash clinker to deionized water is 1 mL: 5-20 g.

6. The preparation method according to claim 1, characterized in that: The stirring aging time in the step (2) is 1-8 hours.

7. The preparation method according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (3) is 80-120° C., and the reaction time is 16-30 hours.

8. The preparation method according to claim 1, characterized in that: The method of separating the solid in step (3) is centrifugation or suction filtration.

9. The preparation method according to claim 1, characterized in that: The drying method in step (3) is to dry at a temperature of 80-120° C. for 8-16 hours.

10. Use of the biomass ash-based zeolite molecular sieve adsorbent prepared by the preparation method according to any one of claims 1 to 9 in lead ion adsorption.

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