Method for preparing mesoporous silica by using yellow phosphorus slag

Abstract

The invention relates to the technical field of heavy metal ion adsorption materials, and discloses a method for preparing mesoporous silica by using yellow phosphorus slag, and the method comprises the following steps: S1, firstly, sieving crushed raw materials to ensure that the granularity of the raw materials is uniform; s2, the first material is subjected to multiple times of acid pickling according to the proportion, and impurities in the raw materials are removed; s3, after acid pickling, washing with distilled water for multiple times, and performing suction filtration to ensure that residual acid is removed; and drying the cleaned raw materials, removing moisture, and calcining at high temperature to form mesoporous silica. The mesoporous silica material prepared by adopting an acid precipitation method has good heavy metal ion adsorption performance.

Description

Technical Field

[0001] The invention relates to the technical field of adsorbents, and in particular to a method for preparing mesoporous silica by utilizing yellow phosphorus slag. Background Art

[0002] Yellow phosphorus slag is an industrial solid waste generated in the production process of yellow phosphorus. When industrially producing 1 ton of yellow phosphorus, 8 to 10 tons of waste slag will be generated.

[0003] The accumulation of yellow phosphorus slag cannot be quickly processed, resulting in a large amount of P and F and other elements seeping from the slag to the ground, polluting groundwater and water sources under the soil and land, and causing serious ecological problems in the accumulation area. Radioactive contamination may also occur during the storage process, affecting plant growth and human health.

[0004] Therefore, it is urgent to transform yellow phosphorus slag into practical materials, which can not only develop the economy but also eliminate the impact of this waste slag on the environment. The main component of yellow phosphorus slag is SiO2, which can be used to produce SiO2 products. The extraction of high-value components of yellow phosphorus slag can not only reduce the environmental pollution caused by the accumulation of yellow phosphorus slag, but also improve the utilization rate and value of yellow phosphorus slag. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing mesoporous silica using yellow phosphorus slag. In order to solve the shortcomings of the prior art, the prepared mesoporous silica has excellent adsorption properties and has broad development space in the direction of improving soil quality.

[0006] The scheme of the present invention is:

[0007] A method for preparing mesoporous silica using yellow phosphorus slag, characterized in that it comprises the following steps:

[0008] S1, air-drying, grinding and sieving the yellow phosphorus slag to obtain material 1;

[0009] S2, acid-washing material 1, and stirring for 6 to 8 hours to obtain material 2;

[0010] S3. Wash the material 2 with distilled water for multiple times and filter it; dry the washed raw material to remove moisture; and calcine it at a high temperature to form a preliminary structure of mesoporous silica.

[0011] As a preferred technical solution, the acid solution used in the pickling in the S2 step is one or both of hydrochloric acid and nitric acid, and the mass ratio of the material 1 to the acid solution is 1:4 to 10.

[0012] As a preferred technical solution, the temperature of the preparation process of the material 2 in the step S2 is controlled below 75°C.

[0013] As a preferred technical solution, the cleaning in S3 is centrifugal cleaning, and the centrifugal cleaning includes the following steps:

[0014] 1) First, material 2 is centrifuged and washed with deionized water for 7 to 10 times;

[0015] 2) The supernatant is centrifuged and washed until the pH value is neutral, thereby obtaining block-shaped silica.

[0016] As a preferred technical solution, the raw material after cleaning in S3 is block silicon dioxide, the block silicon dioxide is vacuum dried at 60-100°C for 10-19 hours, and finally calcined at 300-600°C for 3-6 hours to obtain dry mesoporous silicon dioxide solid.

[0017] As a preferred technical solution, the block of silicon dioxide is subjected to vacuum drying treatment at 80-100° C. for 12 hours, and finally calcined at 300° C. for 3 hours to obtain dry mesoporous silicon dioxide solid.

[0018] As a preferred technical solution, the stirring in S2 is magnetic stirring, and the stirring speed is 200-600prm.

[0019] Advantages of the present invention:

[0020] 1. The preparation method of mesoporous silica proposed in the present invention is easy to operate, low in cost, and conducive to industrial production.

[0021] 2. The mesoporous silica prepared by the present invention is a material with a highly ordered pore structure, a large number of pore structures and a large specific surface area, which enables it to provide more adsorption sites, thereby increasing the ability to adsorb heavy metal ions.

[0022] 3 During the pickling process, other impurities are completely removed through acid-base neutralization reaction or complex reaction with hydrochloric acid, nitric acid or a mixture of the two, leaving only the porous silica structure. In addition, the appropriate temperature can modify the surface of silica with hydroxyl groups, carboxylic acid groups and other groups to further improve the adsorption performance of porous silica. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the XRD pattern of silicon dioxide obtained in Example 2 of the present invention;

[0024] Figure 2 The BET and pore size distribution diagram of silicon dioxide obtained in Example 2 of the present invention;

[0025] Figure 3 This is a scanning electron microscope image of silicon dioxide obtained in Example 2 of the present invention.

[0026] Figure 4 This is a graph showing the effect of the amount of silica added on the adsorption of lead and cadmium obtained in Example 2 of the present invention;

[0027] Figure 5 This is a diagram showing the effect of different concentrations of silica contaminated soil on the adsorption of lead and cadmium obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments.

[0029] Example 1

[0030] A method for preparing a mesoporous silica material comprises the following steps:

[0031] S1. Crush 5.0719 g of yellow phosphorus slag and pass it through a 80-mesh sieve to obtain material 1;

[0032] S2, adding 20.2041 g of aqua regia to material 1 for acid washing twice, stirring for 6 hours for standby treatment, to obtain material 2;

[0033] S3. Filter the material, wash it, and dry it in a vacuum oven at 80° C. for 12 h, then calcine it at 500° C. for 3 h to finally obtain a mesoporous silica material.

[0034] The prepared mesoporous silica material can be used to adsorb soil heavy metal ions and alleviate heavy metal ion pollution.

[0035] Example 2

[0036] A method for preparing a mesoporous silica material comprises the following steps:

[0037] S1. Grind 8.2112 g of yellow phosphorus slag in a mortar for 30 min, and then pass through a 100-mesh sieve to obtain powder material 1;

[0038] S2, pour 30g of aqua regia into material 1, repeat acid washing 3 times, and stir for 8h to obtain solution material 2;

[0039] S3. The material was filtered, washed and dried in a vacuum oven at 70°C for 10 hours, then calcined at 300°C for 3 hours, ground into fine powder, and finally obtained a silica sample.

[0040] The prepared mesoporous silica material was experimentally characterized, and the results are shown below.

[0041] Depend on Figure 1It can be seen that the characteristic peak of the prepared pure silicon dioxide XRD is a large bulge, which is an amorphous silicon dioxide;

[0042] Depend on Figure 2 It can be seen that the BET specific surface area of ​​the material is 106.7m 2 / g, which indicates that the material has a higher surface area, which is very beneficial for increasing the contact area between the material and the adsorbed ions. The existence of hierarchical pores means that the material has pores at different size scales, which can provide more surface area and higher adsorption capacity. Hierarchical pore structure can provide additional advantages for materials, such as improving mass transport and providing more reaction sites.

[0043] Depend on Figure 3 It can be seen that under low-resolution SEM, as shown in Figures a, b and c, the silicon dioxide is in block form with particles attached to the surface. Under high-resolution SEM, as shown in Figure d, silicon dioxide spheres can be clearly seen, with a size of about 50nm.

[0044] To verify the performance of the above mesoporous silica, 5 g of 400 mg·L -1 Pb 2+ 、Cd 2+ For the contaminated soil, add 0.1g, 0.3g, 0.5g, 0.7g and 0.9g of mesoporous silica adsorbent respectively, oscillate in a constant temperature oscillator for 180min, and take out and sieve after the adsorption to determine the ion concentration.

[0045] The experimental results are as follows Figure 4 As shown in the figure, with the increase of silica dosage, the effect of silica on Pb 2+ 、Cd 2+ The removal rate of ions increased, and the change in adsorption amount was the same. This is due to the increase in the amount of adsorbent, which increases the surface area of ​​the silica adsorbent and the active sites available for adsorption. The adsorption effect of the mesoporous silica prepared in the experiment is better than that of the commercial silica sample. In addition, when the silica dosage is 0.5g, the silica has a significant effect on Pb 2+ 、Cd 2+ The removal rate and adsorption amount of ions were 35.31%, 22.20% and 0.97 mg·g -1 , 0.44mg·g -1 When the amount of silica added exceeds 0.5g, the effect of silica on Pb 2+ 、Cd 2+ The increase in the removal rate of Pb is significantly slowed down because most of the Pb 2+ 、Cd 2+The ions have already interacted with the adsorption sites, and the adsorption has reached equilibrium. It is meaningless to increase the amount of adsorbent. Therefore, considering the factors of adsorption effect and economic cost, the optimal dosage of mesoporous silica in this experiment is determined to be 0.5g. Take 5g and prepare 200, 400, 600, 800, 1000mg·L -1 Pb 2+ 、Cd 2+ Add 0.5 g of silica adsorbent to each conical flask of the contaminated soil, oscillate in a constant temperature oscillator for 180 min, and take out the soil after the adsorption is completed, sieve it and determine the ion concentration.

[0046] Take 5g and prepare 200, 400, 600, 800, 1000mg·L -1 Pb 2+ 、Cd 2+ Add 0.5 g of silica adsorbent to each conical flask of the contaminated soil, oscillate in a constant temperature oscillator for 180 min, and take out the soil after the adsorption is completed, sieve it and determine the ion concentration.

[0047] The experimental results are as follows Figure 5 As shown, the effect of silicon dioxide on Pb 2+ 、Cd 2+ The adsorption amount of ions increases with the increase of concentration. -1 Increase to 600mg·L -1 When SiO2 2+ 、Cd 2+ The adsorption of Pb ions increased significantly. This is because at low concentrations, 2+ 、Cd 2+ The ratio of ions to adsorbent surface area is low, and as the concentration increases, Pb 2+ 、Cd 2+ The difference between the concentration of ions and the binding sites on the adsorbent surface increases, generating a greater driving force for adsorption, which increases the unit adsorption capacity of the adsorbent. -1 The reason why the increase is greatly reduced is that the adsorption of heavy metals by silica gradually approaches saturation, the increase in adsorption amount decreases, and the corresponding removal rate decreases.

[0048] Example 3

[0049] A method for preparing a mesoporous silica material comprises the following steps:

[0050] S1. Grind 8.2112 g of yellow phosphorus slag in a mortar for 30 min, and then pass through a 100-mesh sieve to obtain powder material 1;

[0051] S2, pour 30g of aqua regia into material 1, repeat acid washing 3 times, and stir for 8h to obtain solution material 2;

[0052] S3. The material was filtered, washed, and dried in a vacuum oven at 70°C for 10 hours, then calcined at 400°C for 3 hours, ground into fine powder, and finally obtained a silica sample.

[0053] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing mesoporous silica using yellow phosphorus slag, characterized in that: The following steps are involved: S1, air-drying, grinding and sieving the yellow phosphorus slag to obtain material 1; S2, acid-washing material 1, and stirring for 6 to 8 hours to obtain material 2; S3. Wash the material 2 with distilled water for multiple times and filter it; dry the washed raw material to remove moisture; and calcine it at a high temperature to form a preliminary structure of mesoporous silica.

2. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 1, characterized in that: The acid solution used for pickling in the step S2 is one or both of hydrochloric acid and nitric acid, and the mass ratio of the material 1 to the acid solution is 1:4-10.

3. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 1, characterized in that: The temperature of the preparation process of the material 2 in the step S2 is controlled below 75°C.

4. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 1, characterized in that: The cleaning in S3 is centrifugal cleaning, and the centrifugal cleaning includes the following steps: 1) First, material 2 is centrifuged and washed with deionized water for 7 to 10 times; 2) The supernatant is centrifuged and washed until the pH value is neutral, thereby obtaining block-shaped silica.

5. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 1, characterized in that: The cleaned raw material in S3 is block silicon dioxide, which is vacuum dried at 60-100° C. for 10-19 hours, and finally calcined at 300-600° C. for 3-6 hours to obtain dry mesoporous silicon dioxide solid.

6. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 5, characterized in that: The blocky silicon dioxide is subjected to a vacuum drying treatment at 80-100° C. for 12 hours, and finally calcined at 300° C. for 3 hours to obtain a dry mesoporous silicon dioxide solid.

7. A method for preparing mesoporous silica using yellow phosphorus slag as claimed in claim 1, characterized in that: The stirring in S2 is magnetic stirring, and the stirring speed is 200-600prm.

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