Method for preparing nano-siO2 / caSiO3 by using electroplating sludge and process for mineralizing and fixing carbon dioxide

Abstract

The present application relates to a kind of preparation of nanometer SiO2 / CaSiO3 Composite material using electroplating sludge and its carbon dioxide mineralization process. Nanometer SiO2 / CaSiO3 Composite material is prepared by using carbon dioxide assisted precipitation method and solid phase mixing method, realizes the high-value resource utilization of electroplating sludge, and optimizes the carbon fixation performance of CaSiO3. The carbon dioxide mineralization process provided in the present application is under lower temperature and pressure conditions, by water vapor wetting nanometer SiO2 / CaSiO3, so that carbon dioxide is quickly mineralized into stable carbonate, thereby realizing efficient capture and storage of carbon dioxide. The process is simple in operation, low in energy consumption and uses only a small amount of water, does not cause secondary pollution, is green and environmentally friendly, low in cost, suitable for large-scale development and application.

Description

Technical Field

[0001] This invention belongs to the field of waste resource utilization and carbon dioxide capture and storage technology, specifically involving a method for preparing nano-SiO2 / CaSiO3 composite materials using electroplating sludge and its mineralization and carbon dioxide fixation process. Background Technology

[0002] With the development of global industrialization, the excessive use of fossil fuels has led to massive greenhouse gas emissions. Among them, the increase in atmospheric carbon dioxide concentration has the greatest impact on global warming, resulting in more and more extreme weather events and environmental disasters, such as floods, droughts, and sea-level rise.

[0003] Currently, the main methods for large-scale capture and storage of carbon dioxide include geological sequestration, marine sequestration, and mineralization sequestration. Mineralization sequestration is the only known technology that can permanently fix carbon dioxide. It involves reacting carbon dioxide with alkaline substances containing calcium or magnesium, ultimately storing it in the thermodynamically stable form of carbonates. CaSiO3 is the main component of wollastonite, a natural mineral, used for carbon dioxide mineralization. Although the reaction between CaSiO3 and carbon dioxide can proceed spontaneously to form stable calcium carbonate, this process is extremely slow. This is essentially because the microscopic kinetic processes involved in the gas-solid interface reaction, such as mass transfer, crystallization, and interface passivation, are difficult to control.

[0004] Nano-SiO2 possesses characteristics such as large specific surface area, high porosity, and good thermal stability. Therefore, using nano-SiO2 as a carrier to prepare nano-SiO2 / CaSiO3 composite materials can provide channels for rapid mass transfer and diffusion of carbon dioxide through its rich and stable pore structure, which is beneficial to improving the mineralization and carbon fixation rate of CaSiO3 and enhancing the carbon fixation capacity. However, nano-SiO2 is currently generally synthesized using the sol-gel method, which has disadvantages such as high raw material costs and long synthesis time. The SiO2 content in electroplating sludge is usually 20-40 wt%, mainly existing in the form of quartz crystals and mullite, and is an inexpensive silicon-containing precursor. If electroplating sludge is used as a raw material to prepare nano-SiO2, it can not only effectively reduce production costs but also make resource utilization of electroplating sludge. However, there are currently no research reports on the direct preparation of nano-SiO2 from electroplating sludge.

[0005] Furthermore, to accelerate CaSiO3 mineralization and carbon fixation, current processes mainly include direct wet mineralization and indirect mineralization using sulfuric acid as a leaching medium. While direct wet mineralization is simple to operate, it requires high pressure (>1 MPa) and has low carbon fixation efficiency, hindering industrial application. Although Wen Jingjian et al. achieved carbon dioxide fixation at atmospheric pressure using sulfuric acid as a leaching agent, the difficulty in recovering and recycling sulfuric acid has hampered the large-scale application of this method (Publication No. CN109833745 A). Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing nano-SiO2 / CaSiO3 composite materials using electroplating sludge and a process for mineralizing and fixing carbon dioxide. This invention employs a carbon dioxide-assisted precipitation method and a solid-phase mixing method to prepare nano-SiO2 / CaSiO3 composite materials, aiming to achieve high-value resource utilization of electroplating sludge and optimize the carbon fixation performance of CaSiO3. The carbon dioxide mineralization and fixation process provided by this invention utilizes water vapor to wet nano-SiO2 / CaSiO3 under relatively low temperature and pressure conditions, rapidly mineralizing carbon dioxide into stable carbonates, thereby achieving efficient capture and storage of carbon dioxide. This process is simple to operate, consumes low energy, uses only trace amounts of water, does not generate secondary pollution, is environmentally friendly, low-cost, and suitable for large-scale implementation and application.

[0007] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0008] A method for preparing nano-SiO2 / CaSiO3 composite materials using electroplating sludge includes the following steps:

[0009] (1) The electroplating sludge was placed in a muffle furnace and calcined at high temperature to remove organic components, and then ball-milled and sieved.

[0010] (2) The electroplating sludge obtained by screening in step (1) is mixed with sodium hydroxide solution in a reaction vessel and stirred at a certain temperature to generate a mixture of desiliconized sludge and sodium silicate solution to achieve the extraction of silica from electroplating sludge.

[0011] (3) The mixed product obtained from step (2) is centrifuged to separate the solid product into desilication sludge and the supernatant into sodium silicate solution. The supernatant is then diluted in a volumetric flask to obtain an extract for the production of nano-SiO2.

[0012] (4) The extract obtained in step (3) is mixed with deionized water in a certain proportion and placed in a reaction vessel. Carbon dioxide gas is introduced into the reaction vessel and stirred under certain temperature conditions to obtain a mixed product of orthosilicic acid precipitate and sodium carbonate solution;

[0013] (5) The mixture obtained in step (4) is centrifuged and washed several times with deionized water. The resulting solid product is orthosilicic acid.

[0014] (6) The orthosilicic acid obtained in step (5) is dried in an oven at normal pressure to produce nano-SiO2;

[0015] (7) Mix the nano-SiO2 obtained in step (6) with CaSiO3 in a certain proportion and grind them evenly with an agate mortar;

[0016] (8) The nano-SiO2 and CaSiO3 mixture obtained in step (7) is placed in a muffle furnace and calcined at high temperature. After the mixture is naturally cooled, the nano-SiO2 / CaSiO3 composite material is obtained.

[0017] This invention also discloses a process for fixing carbon dioxide by mineralization using nano-SiO2 / CaSiO3, comprising the following steps:

[0018] (1) Take a certain amount of nano-SiO2 / CaSiO3 composite material into the sample stage built into the high-pressure reactor, add a small amount of deionized water droplets into the reactor, then heat to a certain temperature and maintain for a period of time to wet the nano-SiO2 / CaSiO3 with water vapor, and then cool down.

[0019] (2) When the temperature drops to the set reaction temperature, a certain amount of carbon dioxide is introduced into the reactor and the reactor is sealed for a period of time.

[0020] (3) After the reaction is complete, record the partial pressure of carbon dioxide, release the gas in the reactor, and after cooling to room temperature, take out the sample and put it into a vacuum drying oven to dry. Attached Figure Description

[0021] Figure 1 The image shows the XRD patterns of nano-SiO2 and nano-SiO2 / CaSiO3 composite materials in Example 1.

[0022] Figure 2 This invention provides a process flow diagram for fixing carbon dioxide using nano-SiO2 / CaSiO3 mineralization.

[0023] Figure 3 The XRD patterns are for the mineralized products corresponding to Examples 2, 3, and 4. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments.

[0025] Example 1

[0026] The method for preparing nano-SiO2 / CaSiO3 composite materials using electroplating sludge, as described above, includes the following specific steps:

[0027] (1) The electroplating sludge was placed in a muffle furnace and calcined at 800 °C for 2 hours to remove organic components. Then, the electroplating sludge was crushed using a planetary ball mill with a mass ratio of grinding balls to electroplating sludge of 2:1. The ball mill speed was 800 rpm and the ball milling time was 40 minutes. The electroplating sludge was then screened with a 200-mesh sieve to obtain electroplating sludge with a particle size of less than 74 μm for later use.

[0028] (2) Accurately weigh 10 g of electroplating sludge, 5 g of sodium hydroxide and 15 mL of deionized water, put them into a 50 mL polytetrafluoroethylene reactor, react at 110℃ for half an hour, and stir at 400 rpm.

[0029] (3) Centrifuge the mixed product obtained in step (2) at 5000 rpm for 10 minutes, wash it repeatedly with deionized water 3 times, and then dilute the sodium silicate supernatant to 100 mL in a volumetric flask to obtain the extract for the production of nano SiO2.

[0030] (4) Take 8.112 mL of extract and 11.888 mL of deionized water and add them to a 50 mL polytetrafluoroethylene reactor. Then, introduce carbon dioxide gas and wait until its partial pressure stabilizes at 0.3 MPa. Then, close the valve, set the stirring speed to 400 rpm, and react at 90 °C for 3 hours.

[0031] (5) The mixture obtained in step (4) is centrifuged at 9000 rpm for 10 minutes and washed three times with deionized water to obtain the solid product, which is orthosilicic acid;

[0032] (6) Orthosilicic acid is dried in an oven at 105°C under normal pressure for 2 hours to produce nano-SiO2;

[0033] (7) Accurately weigh 0.015 g of nano SiO2 and 0.15 g of CaSiO3, place them in an agate mortar and grind for 15 minutes to mix evenly;

[0034] (8) The nano-SiO2 and CaSiO3 mixture obtained in step (7) is placed in a muffle furnace and calcined at 950°C for 2 hours. After the mixture is naturally cooled, the nano-SiO2 / CaSiO3 composite material is obtained.

[0035] Example 2

[0036] 0.15 g of the nano-SiO2 / CaSiO3 composite material prepared in Example 1 was placed in the sample stage inside a 50 mL high-pressure reactor. 0.5 mL of deionized water was added dropwise to the bottom of the reactor. The reactor was heated at 100 °C for 1 hour to wet the nano-SiO2 / CaSiO3 with water vapor, and then cooled. When the temperature dropped to 50 °C, carbon dioxide gas was introduced into the reactor. When the partial pressure of carbon dioxide stabilized at 0.3 MPa, the valve was closed, and the reaction was allowed to proceed for 6 hours. After the reaction was complete, the partial pressure of carbon dioxide was recorded, the gas inside the reactor was released, and after cooling to room temperature, the product was removed and dried in a vacuum drying oven at 70 °C for 12 hours. Based on the change in carbon dioxide partial pressure, the carbon fixation amount was calculated to be 114 mg. CO2 g 纳米SiO2 / CaSiO3 .

[0037] Example 3

[0038] 0.15 g of the nano-SiO2 / CaSiO3 composite material prepared in Example 1 was placed in the sample stage inside a 50 mL high-pressure reactor. 0.5 mL of deionized water was added dropwise to the bottom of the reactor. The reactor was heated at 100 °C for 1 hour to wet the nano-SiO2 / CaSiO3 with water vapor, and then cooled. When the temperature dropped to 75 °C, carbon dioxide gas was introduced into the reactor. When the partial pressure of carbon dioxide stabilized at 0.4 MPa, the valve was closed, and the reaction was allowed to proceed for 6 hours. After the reaction was complete, the partial pressure of carbon dioxide was recorded, the gas inside the reactor was released, and after cooling to room temperature, the product was removed and dried in a vacuum drying oven at 70 °C for 12 hours. Based on the change in carbon dioxide partial pressure, the carbon fixation amount was calculated to be 216 mg. CO2 g 纳米SiO2 / CaSiO3 .

[0039] Example 4

[0040] 0.15 g of the nano-SiO2 / CaSiO3 composite material prepared in Example 1 was placed in the sample stage inside a 50 mL high-pressure reactor. 0.5 mL of deionized water was added dropwise to the bottom of the reactor. The reactor was heated at 100 °C for 1 hour to wet the nano-SiO2 / CaSiO3 with water vapor. Carbon dioxide gas was then introduced into the reactor. When the partial pressure of carbon dioxide stabilized at 0.5 MPa, the valve was closed, and the reaction was allowed to proceed for 6 hours. After the reaction, the partial pressure of carbon dioxide was recorded, the gas inside the reactor was released, and the product was cooled to room temperature. The product was then removed and dried in a vacuum drying oven at 70 °C for 12 hours. Based on the change in carbon dioxide partial pressure, the carbon fixation amount was calculated to be 198 mg. CO2 g 纳米SiO2 / CaSiO3 .

Claims

1. A method for preparing nano-SiO2 / CaSiO3 composite material by using electroplating sludge, characterized in that, The method steps are as follows: (1) The electroplating sludge was placed in a muffle furnace and calcined at high temperature to remove organic components, and then ball-milled and sieved. (2) The electroplating sludge obtained by screening in step (1) is mixed with sodium hydroxide solution in a reaction vessel and stirred at a certain temperature to generate a mixed product of desiliconized sludge and sodium silicate solution in order to extract silica from the electroplating sludge. (3) The mixed product obtained from step (2) is centrifuged to separate the solid product into desilication sludge and the supernatant into sodium silicate solution. The supernatant is then diluted in a volumetric flask to obtain an extract for the production of nano-SiO2. (4) The extract obtained in step (3) is mixed with deionized water in a certain proportion and placed in a reaction vessel. Carbon dioxide gas is introduced into the reaction vessel and stirred under a certain temperature condition to obtain a mixed product of orthosilicic acid precipitate and sodium carbonate solution. (5) Centrifuge the mixed product obtained in step (4) and wash it several times with deionized water. The resulting solid product is orthosilicic acid. (6) The orthosilicic acid obtained in step (5) is dried in an oven at normal pressure to produce nano-SiO2; (7) Mix the nano-SiO2 obtained in step (6) with CaSiO3 in a certain proportion and grind them evenly with an agate mortar; (8) The nano-SiO2 and CaSiO3 mixture obtained in step (7) is placed in a muffle furnace and calcined at high temperature. After the mixture is naturally cooled, the nano-SiO2 / CaSiO3 composite material is obtained.

2. The method according to claim 1, characterized in that, The calcination temperature in step (1) is 800~1000℃ and the time is 2~4 hours.

3. The method according to claim 1, characterized in that, The ball milling in step (1) uses a planetary ball mill. The grinding jar and grinding balls are made of zirconium oxide. The mass ratio of grinding balls to electroplating sludge is 2:

1. The ball mill speed is 700~800 rpm and the grinding time is 30~60 minutes.

4. The method according to claim 1, characterized in that, In step (1), the electroplating sludge is sieved using a 200-mesh sieve to obtain electroplating sludge with a particle size of less than 74 μm for later use.

5. The method according to claim 1, characterized in that, In step (2), the mass ratio of electroplating sludge to sodium hydroxide is (1~4):1, the concentration of sodium hydroxide solution is 10~35wt%, the reaction temperature is 50~150℃, the reaction time is 30~60 minutes, and the stirring speed is 200~500rpm.

6. The method according to claim 1, characterized in that, The centrifugation speed in step (3) is 3000~6000 rpm, the centrifugation time is 5~20 minutes, and the supernatant is diluted to 50 or 100 mL in a volumetric flask.

7. The method according to claim 1, characterized in that, In step (4), the volume ratio of the extract to deionized water is (0.1~4):1, the partial pressure of carbon dioxide is 0.1~1MPa, the reaction temperature is 50~100℃, the time is 2~5 hours, and the stirring speed is 200~500rpm.

8. The method according to claim 1, characterized in that, The centrifugation speed in step (5) is 7000~9000 rpm and the centrifugation time is 5~20 minutes.

9. The method according to claim 1, characterized in that, The drying temperature in step (6) is controlled at 100~120℃ and the drying time is 1~3 hours.

10. The method according to claim 1, characterized in that, In step (7), the mass ratio of nano-SiO2 to CaSiO3 is 1:10, and the grinding time is at least 10 minutes.

11. The method according to claim 1, characterized in that, The calcination temperature in step (8) is 900~1000℃ and the time is 2~3 hours.

12. A method for mineralizing and fixing carbon dioxide using nano-SiO2 / CaSiO3, characterized in that, The method steps are as follows: (1) Take a certain amount of the nano-SiO2 / CaSiO3 composite material prepared by any one of claims 1 to 11 into the sample stage built into the high-pressure reactor, add a small amount of deionized water droplets into the reactor, then heat to a certain temperature and maintain for a period of time to wet the nano-SiO2 / CaSiO3 with water vapor, and then cool down. (2) When the temperature drops to the set reaction temperature, a certain amount of carbon dioxide is introduced into the reactor and the reaction is sealed for a period of time. (3) After the reaction is complete, record the partial pressure of carbon dioxide, release the gas in the reactor, and after cooling to room temperature, take out the sample and put it into a vacuum drying oven to dry.

13. The method according to claim 12, characterized in that, In step (1), the mass of the nano-SiO2 / CaSiO3 composite material is 0.1~0.3g, the amount of deionized water added is 0.05~1mL, the heating temperature is 35~100℃, and the time is 1~2 hours.

14. The method according to claim 12, characterized in that, In step (2), the partial pressure of carbon dioxide is controlled at 0.2~0.5MPa, the reaction temperature is 35~100℃, and the time is 3~24 hours.

15. The method according to claim 12, characterized in that, The vacuum drying temperature in step (3) is 60~80℃ and the time is 12~24 hours.

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