A ceramsite-zeolite composite high-performance adsorption material and its preparation method

Abstract

The present invention provides a ceramsite-zeolite composite high-performance adsorption material and a preparation method thereof. Specifically, fly ash and coal gangue are used as raw materials, and pulverized coal is used as a foaming agent. In the first step, sintering is carried out to prepare ceramsite. Then, the calcined ceramsite and sodium carbonate decahydrate are ground and mixed and directly placed into a reaction kettle, and a ceramsite-zeolite composite high-performance adsorption material is synthesized by sealing and standing at a certain temperature. The synthesized zeolitized ceramsite of the present invention has far higher adsorption performance than conventional ceramsite, has good adsorption effect on heavy metals in wastewater, and no alkaline wastewater is generated during the zeolitization process of ceramsite, and the synthesis process is more environmentally friendly. The present invention uses fly ash and coal gangue as raw materials and adopts a "two-step method" of sintering-solvent-free crystallization to prepare a ceramsite-zeolite composite high-performance adsorption material. The process is simple, the zeolitization process is green and environmentally friendly, and the application range is wide. It can not only alleviate the environmental problems brought by fly ash and coal gangue, but also realize the high-value utilization of fly ash and coal gangue.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of high-performance adsorption materials, and particularly relates to a ceramsite-zeolite composite high-performance adsorption material prepared from fly ash and coal gangue as raw materials and a preparation process adopting a "two-step method" of sintering-solvent-free crystallization. Background Art

[0002] At present, with the continuous strengthening of the national environmental protection policy and the proposal of the national sustainable development policy, experimental research on the comprehensive utilization of bulk industrial solid wastes has received more support. The treatment of industrial solid wastes has changed from simply stacking to comprehensive utilization and resource utilization. Fly ash mainly comes from thermal power plants fueled by coal and is the main solid waste discharged from coal-fired power plants. The chemical components in fly ash are mainly (28.5-66.0 wt.%) SiO2 and (12.5-55.0 wt.%) Al2O3, and contain a certain amount of metal compounds and unburned organic matter. Coal gangue is a solid waste discharged during the coal mining process and coal washing process. It is a black-gray rock with a lower carbon content and harder than coal that is associated with coal seams during the coal formation process, including heading gangue during the roadway driving process, gangue mined from the roof, floor and interlayers during the mining process, and washed gangue picked out during the coal washing process. The main components of coal gangue are (45-60 wt.%) SiO2 and (20-30 wt.%) Al2O3, which exist in the forms of quartz, kaolinite, etc., and there are also a small amount of metal oxides. Fly ash and coal gangue both have great application value in the field of environmental remediation. Research shows that some components such as SiO2 and Al2O3 in fly ash and coal gangue have strong adsorption effects on phosphates, heavy metals, etc. in sewage. Therefore, at present, many studies use fly ash and coal gangue as raw materials for preparing ceramsite to realize their resource utilization.

[0003] Ceramsite has uniform morphology and composition, and has the advantages of low density, high strength, wear resistance, and multiple pores inside. It has excellent properties such as light weight, high strength, sound absorption, acid and alkali resistance, corrosion resistance, earthquake resistance, frost resistance, impermeability, and good chemical stability. Therefore, it is widely used as an adsorbent in the field of water treatment. Changing the proportion of fly ash in the firing raw materials can affect the properties of ceramsite. When the proportion of fly ash is 10%-20%, ultra-light ceramsite can be fired. When the proportion of fly ash is 20%-50%, light ceramsite can be fired. Grain It is found that when fly ash is incorporated into the process of preparing glass, as the incorporation amount increases, the leaching concentration of most heavy metals is below 1 mg / L. In the process of preparing ceramsite from coal gangue, when the mixing ratio of coal gangue and shale is 4:1 and appropriate auxiliary materials are incorporated, the strength of the finally fired ceramsite clinker is relatively high, reaching 800 grade. When the ratio of coal gangue, fly ash and additives is 78:15:7, the bulk density of the ceramsite clinker is 785 kg / m 3, the cylinder compressive strength is 5.9 MPa and the water absorption rate is 3.5%. However, the pore size distribution of ordinary ceramsite is mainly dominated by large pores, which will lead to a decrease in its adsorption capacity and adsorption rate, seriously affecting its industrial application.

[0004] Zeolite molecular sieve material is an aluminosilicate crystal of alkali metal or alkaline earth metal containing crystal water, which is filled with fine pores and channels inside and has very good adsorption performance. Currently, zeolites are all prepared from chemical reagents, industrial solid wastes, and agricultural solid wastes. Among them, the preparation of zeolites from solid wastes is a current research hotspot. However, the preparation of zeolites from solid wastes requires activation treatment to meet the raw material requirements for zeolite preparation. The activation process often requires high-temperature roasting, alkali fusion activation, acid leaching for impurity removal and other processes. Moreover, the synthesized zeolite has a single zeolite crystal structure, which is difficult to meet the treatment requirements of current complex and multi-component composite pollutants, and has drawbacks such as a single application structure and poor applicability. At the same time, the currently prepared zeolites all exist in the form of powders and must undergo forming operations (such as spherical, cylindrical, strip-shaped particles, etc.) before entering the reactor in application, resulting in problems such as complex processes, low material strength, and poor reuse efficiency.

[0005] Through analyzing the existing problems in the utilization of current ceramsite and zeolite, this study proposes a ceramsite-zeolite composite high-performance adsorption material. By giving full play to the characteristics of ceramsite with high strength, rich pore channels, a large pore size range, easy separation, as well as excellent adsorption performance and large specific surface area of zeolite, a new type of solid waste-based composite material is developed. By adjusting the dosages of fly ash and coal gangue, the silicon-aluminum ratio of the ceramsite-zeolite composite high-performance adsorption material is adjusted, providing a new idea for the high-value utilization of fly ash and coal gangue. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art and to solve the above problems, the present invention proposes a new process for preparing a ceramsite-zeolite composite high-performance adsorption material. The ceramsite zeolitization process adopts a solvent-free method, and the synthesis process is more environmentally friendly. Moreover, using fly ash and coal gangue as raw materials can not only alleviate the environmental problems brought by fly ash and coal gangue, but also realize the high-value utilization of fly ash and coal gangue.

[0007] Using fly ash and coal gangue as raw materials, since the silicon and aluminum substances in the raw materials mainly exist stably in the form of crystals in fly ash and coal gangue and cannot directly undergo crystallization reaction, the present invention proposes a "two-step method" of sintering-solvent-free crystallization to prepare a ceramsite-zeolite composite high-performance adsorption material, which can well solve this problem. The ceramsite sintering process can well stimulate the activity of the raw materials and provide conditions for further zeolitization.

[0008] A preparation method of a ceramsite-zeolite composite high-performance adsorption material, characterized in that: using fly ash and coal gangue as raw materials, a certain amount of pulverized coal is proportioned for the ceramsite firing process, and the ceramsite is further subjected to zeolitization treatment by a solvent-free method to obtain a ceramsite-zeolite composite high-performance adsorption material.

[0009] The preparation method of the ceramsite-zeolite composite high-performance adsorption material as described above specifically includes the following steps:

[0010] Step 1: Firing of ceramsite: Grind fly ash and coal gangue through a 100-mesh sieve; mix fly ash, coal gangue and pulverized coal in a certain proportion; add water accounting for 5-8% of the total mass of the powder to the well-mixed raw materials and further mix, and after mixing evenly, make green balls with a diameter of 8-10 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat up to 500-550 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat up to 1100-1150 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace, and the sample cools with the furnace.

[0011] Step 2: Zeolitization of ceramsite: Grind and mix the ceramsite obtained in Step 1 with sodium carbonate decahydrate in a certain proportion, heat up to 150-180 °C, and crystallize for 8-12 hours. After the reaction is over, wash the sample with deionized water and then dry it to obtain a ceramsite-zeolite composite high-performance adsorption material.

[0012] Preferably, the mass ratio of fly ash, coal gangue and pulverized coal is 8:1.5:0.5.

[0013] Furthermore, the mass ratio of the ceramsite to sodium carbonate decahydrate is 1:(0.15-0.45), and the grinding time is 5 min.

[0014] The present invention also provides a use of the ceramsite-zeolite composite high-performance adsorption material for adsorbing lead in heavy metal wastewater.

[0015] Furthermore, the adsorption conditions are: temperature 25 °C, pH = 4, dosage 0.2 g / 100 mL, 180 r / min.

[0016] The zeolitized sample still maintains the original morphology (spherical) of the ceramsite, but the enamel on the surface of the ceramsite fades after zeolitization, and the roughness increases. Inside the pore channels of the modified ceramsite, a symbiotic state of various zeolite structures appears, and faujasite and hydroxycancrinite can provide Na + 、Ca 2+ 、K + and other ions, as well as OH for complexation and self-oxidation-reduction -The group can achieve multiple adsorption mechanisms of ceramsite for pollutants, greatly improving the application scope and effect of ceramsite in the fields of adsorption and degradation.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention provides a new method for the preparation of ceramsite-zeolite composite high-performance adsorption materials. After the ceramsite undergoes crystallization reaction, it not only contains a conventional macroporous structure, but also has mesoporous and microporous structures at the same time. Therefore, the ceramsite-zeolite composite adsorption material synthesized by this method has better adsorption performance than conventional ceramsite.

[0019] (2) The solvent-free method is adopted in the process of ceramsite zeolitization, and water is not required as a reaction medium during the process. Therefore, not only can the space utilization rate of the reaction kettle be improved, but also no alkaline waste liquid will be produced.

[0020] (3) When preparing the ceramsite-zeolite composite high-performance adsorption material according to the method of the present invention, the raw materials used are fly ash and coal gangue. Therefore, the present invention can not only alleviate the environmental problems brought by fly ash and coal gangue, but also realize the resource utilization of fly ash and coal gangue, turning waste into treasure. Description of the Drawings

[0021] Figure 1 It is the X-ray diffraction (XRD) pattern of the ceramsite-zeolite composite high-performance adsorption material prepared by the "two-step method" of sintering-solvent-free for Example 3;

[0022] Figure 2 It is the physical picture and scanning electron microscope (SEM) picture of the sample in Example 3;

[0023] Figure 3 It is the adsorption effect picture at different adsorption times before and after the ceramsite zeolitization modification in Example 3. Detailed Embodiments

[0024] In order to better illustrate the present invention and facilitate the understanding of the technical solution of the present invention, the technical solution of the present invention will be further described below with specific embodiments.

[0025] The present invention is a method for the preparation of a ceramsite-zeolite composite high-performance adsorption material, and the method specifically includes the following steps:

[0026] Step 1: Sintering to prepare ceramsite

[0027] Grind fly ash and coal gangue and sieve them through a 100-mesh sieve; mix fly ash, coal gangue and pulverized coal in a certain proportion; add water accounting for 5-8% of the total mass of the powder to the well-mixed raw materials and further mix them. After mixing evenly, form green balls with a diameter of about 8-10 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat them up to 500-550 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat them up to 1100-1150 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace and let the sample cool with the furnace.

[0028] Step 2: Preparation of ceramsite-solvent-free crystallized ceramsite-zeolite composite high-performance adsorbent material

[0029] Mix the ceramsite obtained in Step 1 with sodium carbonate decahydrate in a certain proportion, heat up to 150-180 °C, and crystallize for 8-12 hours. After the reaction ends, wash the sample with deionized water and then dry it to obtain the ceramsite-zeolite composite high-performance adsorbent material.

[0030] The following further describes the present invention with reference to specific embodiments. The following embodiments are only simple examples of the present invention and do not represent or limit the scope of the claimed rights of the present invention. The scope of protection of the present invention is subject to the claims.

[0031] Example 1

[0032] Using fly ash and coal gangue as raw materials, weigh 5.00 g of fly ash, 0.94 g of coal gangue and 0.31 g of pulverized coal respectively. After mixing them evenly, add 0.31 g of water and further mix them. After mixing evenly, form green balls with a diameter of about 10 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat them up to 500 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat them up to 1100 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace and let the sample cool with the furnace. Finally, take 5 g of the calcined ceramsite and grind it with 1.5 g of sodium carbonate decahydrate for 5 min, then put it into a 50 mL stainless steel autoclave, heat up to 150 °C, and crystallize at autogenous pressure for 12 hours. After the reaction ends, wash the sample with deionized water and then dry it to obtain the ceramsite-zeolite composite high-performance adsorbent material.

[0033] Example 2

[0034] Using fly ash and coal gangue as raw materials, weigh 5.00 g of fly ash, 0.94 g of coal gangue and 0.31 g of pulverized coal respectively. After mixing them evenly, add 0.31 g of water and mix further. After mixing evenly, make green balls with a diameter of about 10 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat up to 500 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat up to 1100 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace, and the sample cools with the furnace. Finally, take 5 g of the calcined ceramsite and grind it with 0.75 g of sodium carbonate decahydrate for 5 min, then put it into a 50 mL stainless steel autoclave, heat up to 150 °C, and crystallize for 12 hours. After the reaction is over, wash the sample with deionized water and then dry it to obtain a ceramsite-zeolite composite high-performance adsorption material.

[0035] Example 3

[0036] Using fly ash and coal gangue as raw materials, weigh 5.00 g of fly ash, 0.94 g of coal gangue and 0.31 g of pulverized coal respectively. After mixing them evenly, add 0.31 g of water and mix further. After mixing evenly, make green balls with a diameter of about 10 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat up to 500 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat up to 1100 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace, and the sample cools with the furnace. Finally, take 5 g of the calcined ceramsite and grind it with 2.25 g of sodium carbonate decahydrate for 5 min, then put it into a 50 mL stainless steel autoclave, heat up to 150 °C, and crystallize for 12 hours. After the reaction is over, wash the sample with deionized water and then dry it to obtain a ceramsite-zeolite composite high-performance adsorption material. The X-ray diffraction (XRD) pattern of the sample is as Figure 1 shown, and the physical picture and scanning electron microscope (SEM) picture are as Figure 2 shown. The zeolitized ceramsite and ordinary ceramsite are used to adsorb lead in heavy metal wastewater. The adsorption conditions are: temperature 25 °C, pH = 4, dosage 0.2 g / 100 mL, stirring rate 180 r / min. The results are as Figure 3 shown, and it can be seen that the adsorption property and adsorption capacity of the zeolitized ceramsite are significantly improved.

[0037] Example 4

[0038] Using fly ash and coal gangue as raw materials, weigh 5.00 g of fly ash, 0.94 g of coal gangue and 0.31 g of pulverized coal respectively. After mixing them evenly, add 0.5 g of water and mix further. After mixing evenly, make green balls with a diameter of about 8 mm, and dry them at 105 °C for 1 hour; put the dried green balls into a muffle furnace, heat them to 550 °C at a heating rate of 10 °C / min, preheat for 10 min, and then heat them to 1150 °C at a heating rate of 10 °C / min for sintering. After 20 min, turn off the muffle furnace, and let the sample cool with the furnace. Finally, take 5 g of the calcined ceramsite and grind it with 1.5 g of sodium carbonate decahydrate for 5 min, then put it into a 50 mL stainless steel autoclave, heat it to 180 °C, and crystallize for 8 hours. After the reaction is over, wash the sample with deionized water and then dry it to obtain the ceramsite-zeolite composite high-performance adsorbent material.

[0039] The above-mentioned embodiments only represent several implementation modes of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A preparation method of a ceramsite-zeolite composite high-performance adsorption material, characterized in that, It includes the following steps: Step (1): Firing of ceramsite: After grinding and sieving fly ash and coal gangue, they are mixed with pulverized coal in a certain proportion. After adding a certain amount of water to the mixed raw materials, further mixing is carried out to make green balls, which are then dried. Then, they are put into a muffle furnace, preheated to 500 - 550 °C, and then heated to 1100 - 1150 °C for sintering for a certain time, after which the muffle furnace is turned off and the samples are cooled with the furnace; Step (2): Zeolitization of ceramsite: The ceramsite obtained in Step 1 is ground and mixed with sodium carbonate decahydrate in a certain proportion, heated to 150 - 180 °C, and crystallized for 8 - 12 hours. After the reaction ends, the samples are washed with deionized water and then dried to obtain a ceramsite-zeolite composite high-performance adsorption material; The mass ratio of the fly ash, coal gangue, and pulverized coal is 8:1.5:0.

5.

2. The preparation method of a ceramsite-zeolite composite high-performance adsorption material according to claim 1, characterized in that, The addition amount of water in Step (1) is 5 - 8% of the total mass of the powder.

3. The preparation method of a ceramsite-zeolite composite high-performance adsorption material according to claim 1, characterized in that, The diameter of the green balls prepared in Step (1) is 8 - 10 mm.

4. The preparation method of a ceramsite-zeolite composite high-performance adsorption material according to claim 1, characterized in that, The drying temperature in Step (1) is 105 °C, and the drying time is 1 h.

5. The preparation method of a ceramsite-zeolite composite high-performance adsorption material according to claim 1, characterized in that, The heating rate in Step (1) is 10 °C / min.

6. The preparation method of a ceramsite-zeolite composite high-performance adsorption material according to claim 1, characterized in that, The mass ratio of the ceramsite to sodium carbonate decahydrate is 1:(0.15 - 0.45), and the grinding time is 5 min.

7. A ceramsite-zeolite composite high-performance adsorption material obtained by the method according to any one of claims 1-6.

8. A use of the ceramsite-zeolite composite high-performance adsorption material according to claim 7 for adsorbing lead in heavy metal wastewater.

9. The use according to claim 8, characterized in that, The adsorption conditions: temperature 25 °C, pH = 4, dosage 0.2 g / 100 mL, stirring rate 180 r / min.

Images