Method for preparing zero-valent iron with quantitative specific surface area

Abstract

The invention provides a method for preparing zero-valent iron with quantitative specific surface area, which comprises the following specific steps: S1, adding zero-valent iron powder and absolute ethyl alcohol into a container, and uniformly stirring to form slurry to be ground; s2, filling a wet ball mill with grinding beads, and grinding the to-be-ground slurry to obtain slurry; s3, taking out the slurry and separating; and S4, the separated zero-valent iron particles are dried, the grinding time ranges from 10 min to 200 min, the size of grinding beads ranges from 0.4 mm to 2.0 mm, the filling amount of the grinding beads ranges from 0.25 kg to 0.75 kg, the rotating speed of a stirring shaft of the wet ball mill ranges from 1000 rpm to 2000 rpm, and the specific surface area of the zero-valent iron obtained through ball milling is controlled by controlling the ball milling time, the size of the ball milling beads, the filling amount of the ball milling beads and the rotating speed of the stirring shaft of the wet ball mill.

Description

Technical Field

[0001] The invention relates to the technical field of particle refinement, and in particular to a method for preparing zero-valent iron with a quantitative specific surface area. Background Art

[0002] As an efficient reducing agent, zero-valent iron (ZVI) has been widely used in the field of pollution control, especially in the treatment of industrial wastewater and groundwater. The treatment efficiency of ZVI is closely related to its specific surface area (SSA). A larger specific surface area can provide more reactive sites, thereby significantly improving its ability to degrade pollutants. Therefore, how to prepare ZVI with a high and quantitative specific surface area has become a core issue in technology research and development.

[0003] Traditionally, researchers have explored a variety of methods to increase the specific surface area of ​​ZVI, including reducing the particle size to the nanoscale, introducing sponge-like or porous structures, and processing the particles into flakes by mechanical grinding. Ball milling has attracted much attention because it can significantly increase the specific surface area of ​​ZVI, especially in the wet ball milling process, which uses grinding media to apply mechanical force to ZVI particles, causing them to undergo plastic deformation or breakage, thereby significantly increasing their surface area.

[0004] However, the existing ball milling technology faces some challenges in practical applications, the most prominent of which are high energy consumption and low ball milling efficiency. Ball milling equipment usually needs to run at high speed for a long time, and most of the friction and impact force generated during the rotation process are lost in the form of heat energy and sound energy, resulting in low energy conversion efficiency. In addition, due to the toughness and ductility of ZVI, how to effectively control the deformation and crushing degree of particles during the ball milling process to obtain ZVI with a specific specific surface area is also a technical problem that needs to be solved urgently.

[0005] The invention patent with application number 202311190186.7 discloses a green and economical ball milling reduction of micro-sodium zero-valent iron and its application. It mainly studies a green and economical ball milling reduction method for preparing high-purity zero-valent iron, including a green and economical ball milling reduction process, the preparation of high-purity zero-valent iron, and how to reduce energy consumption and carbon emissions.

[0006] However, the above patent is mainly aimed at improving the purity of the final product, and no in-depth research has been conducted on the regulation of the specific surface area of ​​zero-valent iron and the influence of the surface area on the final performance. Summary of the invention

[0007] The present invention is made to solve the above-mentioned problem, and its purpose is to provide a method for preparing zero-valent iron with a quantitative specific surface area. By precisely controlling the specific surface area, the zero-valent iron material can be customized according to different application requirements.

[0008] The present invention provides a method for preparing zero-valent iron with a quantitative specific surface area, which has the following characteristics. The preparation method is specifically as follows: S1, adding zero-valent iron powder and anhydrous ethanol into a container, stirring evenly to form a slurry to be ground; S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain a slurry, and using a cooling system to keep the temperature stable during the grinding process; S3, taking out the slurry from the wet ball mill, and placing the slurry into a magnetic separation device for separation; and S4, placing the separated zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C, wherein the grinding time is 10-200 min, the size of the grinding beads is 0.4-2.0 mm, the filling amount of the grinding beads is 0.25-0.75 kg, and the stirring shaft speed of the wet ball mill is 1000-2000 rpm.

[0009] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following characteristics: wherein the specific surface area of ​​the zero-valent iron obtained by ball milling is controlled by controlling the ball milling time, the ball milling bead size, the ball milling bead filling amount and the stirring shaft speed of the wet ball mill, and the relationship between the specific surface area of ​​the zero-valent iron and the parameters in the ball milling process is: Y=-0.021+0.423×A+0.024×B+0.421×C-0.240×D-0. 461×A×A+0.222×B×B+0.267×C×C+0.543×D×D+0.299×A×B+0.190×A×C+0.004×A×D-0.465×B×C+0.004×B×D-0.165×C×D-0.410×A×B×C-0.055×A×B×D+0.304×A×C×D+0.135×B×C×D, where Y represents the specific surface area (m 2 / g), A represents the ball milling time (min), B represents the ball milling bead size (mm), C represents the ball milling bead filling amount (kg), and D represents the stirring shaft speed of the wet ball mill (rpm).

[0010] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following feature: wherein the grinding beads are zirconium oxide grinding beads.

[0011] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following characteristics: wherein the size of the grinding beads is 0.4-0.8 mm.

[0012] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following characteristics: wherein the grinding time is 180-200 minutes.

[0013] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following characteristics: wherein the filling amount of the grinding beads is 0.6-0.65 kg.

[0014] The method for preparing zero-valent iron with a quantitative specific surface area provided by the present invention may also have the following feature: wherein the rotation speed of the wet ball mill is 1900-2000 rpm.

[0015] Functions and Effects of the Invention According to the method for preparing zero-valent iron with a quantitative specific surface area involved in the present invention, the present invention can control and quantitatively produce zero-valent iron with a specific specific surface area by optimizing key process parameters such as ball milling time, grinding bead size, grinding bead quality, and stirring shaft speed of a wet ball mill. This innovation ensures the performance stability and predictability of zero-valent iron products in different application scenarios, so that the material can be customized according to specific application requirements, and the material properties can be flexibly adjusted according to the needs of different fields. At the same time, it can also have higher activity and more stable performance in chemical reactions; in addition, the present invention does not involve the use of sulfide solutions or other harmful chemical reagents. The entire process is completed in an environmentally friendly medium, which reduces environmental risks and operational difficulties. The method has low energy consumption, high efficiency, and is more green and environmentally friendly, meeting the requirements of modern industry for sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the wet ball mill of the present invention. DETAILED DESCRIPTION

[0017] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0018] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following examples and accompanying drawings specifically illustrate the method for preparing zero-valent iron with quantitative specific surface area of ​​the present invention.

[0019] The method for preparing zero-valent iron with a quantitative specific surface area in this embodiment specifically includes the following steps: S1, adding zero-valent iron powder and anhydrous ethanol into a container, and stirring evenly to form a slurry to be ground.

[0020] S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, using a cooling system to keep the temperature stable during the grinding process, the grinding time is 10-200 min, the size of the grinding beads is 0.4-2.0 mm, the filling amount of the grinding beads is 0.25-0.75 kg, and the rotation speed of the wet ball mill is 1000-2000 rpm.

[0021] S3, taking out the slurry from the wet ball mill, and placing the slurry into a magnetic separation device for separation.

[0022] S4, placing the separated zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

[0023] Figure 1 Schematic diagram of the structure of the wet ball mill 100 of the present invention.

[0024] like Figure 1 As shown, the wet ball mill used in the above method of the present invention comprises a reactor housing 10, a rotor 20, an end cover 30 and a driving mechanism 40. The driving mechanism 40 is used to drive the rotor 20 to rotate, and comprises a main shaft 42, a bearing seat 41, and a pulley 45.

[0025] The reactor shell 10 is generally cylindrical, and has a cavity formed inside, which is the reaction chamber 11. The reactor shell 10 is provided with a feed port 12 and a discharge port 13 connected to the reaction chamber 11, which are used to allow the slurry to enter and flow out of the reaction chamber 11, respectively.

[0026] In the reactor shell 10, a cooling water chamber 14 is formed around the reaction chamber 11 and is not connected to the reaction chamber 11, and is used to contain cooling water for cooling the reaction chamber 11. The cooling water can enter the cooling water chamber through the cooling water inlet 15 and flow out of the cooling water chamber from the cooling water outlet 16.

[0027] The rotor 20 is disposed in the reaction chamber 11 and is columnar with a plurality of annular sheets on the circumference. The surface of the rotor is covered with a layer of polyurethane material to reduce the wear of the ball milling beads on the rotor body.

[0028] The end cover 30 is disposed at one end of the reactor housing 10 , and a middle end cover 31 is installed on the end of the end cover 30 away from the reactor housing 10 .

[0029] The bearing seat 41 is disposed on the other side of the middle end cover 31 relative to the end cover 30 .

[0030] The main shaft 42 is installed in the bearing seat 41 through the bearing 43, and one end of the main shaft 42 passes through the middle end cover 31 and the end cover 30 in sequence and extends into the reaction chamber 11. This end is connected to the rotor 20, so that the main shaft 42 can drive the rotor 20 to rotate.

[0031] A mechanical seal assembly 44 is also provided in the end cover 30 . The mechanical seal assembly 44 is sleeved on the main shaft 42 and is located close to the reaction chamber 11 . The mechanical seal assembly 44 is used to form a seal on the main shaft 42 to prevent the liquid in the reaction chamber 11 from leaking to the bearing seat 41 and other parts.

[0032] The other end of the main shaft 42 extends to the outside of the bearing seat 41, and is fixed by a locking nut 46 and a bearing cover plate 47, and a main pulley 45 is fixed on this end. The driving mechanism 40 drives the pulley 45 to rotate through the belt transmission mechanism, so that the main shaft 42 rotates and drives the rotor 20 to rotate in the reaction chamber 11. When there is slurry containing ball milling beads in the reaction chamber 11, the high-speed rotation of the rotor 20 can strongly stir the slurry, so that the slurry can undergo a mechanochemical reaction under the action of the ball milling beads; a large amount of heat will be generated in the process, and the heat can be taken away by cooling water.

[0033] Example 1 S1, adding zero-valent iron powder and anhydrous ethanol into a container, and stirring evenly to form a slurry to be ground.

[0034] S2, loading zirconium oxide grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, using a cooling system to keep the temperature stable during the grinding process, the grinding time is 10 minutes, the size of the grinding beads is 0.4 mm, the filling amount of the grinding beads is 0.25 kg, and the rotation speed of the wet ball mill is 1000 rpm.

[0035] S3, taking out the slurry from the wet ball mill, and placing the slurry into a magnetic separation device for separation.

[0036] S4, placing the separated zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C.

[0037] The specific surface area of ​​zero-valent iron obtained in Example 1 is 8.567 m 2 / g.

[0038] Example 2 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 10 min, the size of the grinding beads of 0.8 mm, the filling amount of the grinding beads of 0.4 kg, and the speed of the wet ball mill of 1200 rpm.

[0039] The specific surface area of ​​zero-valent iron obtained in Example 2 is 9.21 m 2 / g.

[0040] Example 3 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 10 min, the size of the grinding beads of 1 mm, the filling amount of the grinding beads of 0.5 kg, and the speed of the wet ball mill of 1500 rpm.

[0041] The specific surface area of ​​zero-valent iron obtained in Example 3 is 10.756 m 2 / g.

[0042] Example 4 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 10 min, the size of the grinding beads of 1.6 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 1800 rpm.

[0043] The specific surface area of ​​zero-valent iron obtained in Example 4 is 10.773 m 2 / g.

[0044] Example 5 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 10 min, the size of the grinding beads of 2 mm, the filling amount of the grinding beads of 0.75 kg, and the speed of the wet ball mill of 2000 rpm.

[0045] The specific surface area of ​​zero-valent iron obtained in Example 5 is 11.382 m 2 / g.

[0046] Example 6 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 30 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.4 kg, and the speed of the wet ball mill of 1500 rpm.

[0047] The specific surface area of ​​zero-valent iron obtained in Example 6 is 11.074 m 2 / g.

[0048] Example 7 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 30 min, the size of the grinding beads of 0.8 mm, the filling amount of the grinding beads of 0.5 kg, and the speed of the wet ball mill of 1800 rpm.

[0049] The specific surface area of ​​zero-valent iron obtained in Example 7 is 14.076 m 2 / g.

[0050] Example 8 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 30 min, the size of the grinding beads of 1 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm.

[0051] The specific surface area of ​​zero-valent iron obtained in Example 8 is 15.078 m 2 / g.

[0052] Example 9 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 30 min, the size of the grinding beads of 1.6 mm, the filling amount of the grinding beads of 0.75 kg, and the speed of the wet ball mill of 1000 rpm.

[0053] The specific surface area of ​​zero-valent iron obtained in Example 9 is 15.679 m 2 / g.

[0054] Example 10 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 30 min, the size of the grinding beads of 2 mm, the filling amount of the grinding beads of 0.25 kg, and the speed of the wet ball mill of 1200 rpm.

[0055] The specific surface area of ​​zero-valent iron obtained in Example 10 is 12.655 m 2 / g.

[0056] Embodiment 11 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 60 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.5 kg, and the speed of the wet ball mill of 2000 rpm.

[0057] The specific surface area of ​​zero-valent iron obtained in Example 11 is 14.756 m 2 / g.

[0058] Example 12 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 60 min, the size of the grinding beads of 0.8 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 1000 rpm.

[0059] The specific surface area of ​​zero-valent iron obtained in Example 12 is 10.841 m 2 / g.

[0060] Embodiment 13 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 60 min, the size of the grinding beads of 1 mm, the filling amount of the grinding beads of 0.75 kg, and the speed of the wet ball mill of 1200 rpm.

[0061] The specific surface area of ​​zero-valent iron obtained in Example 13 is 16.008 m 2 / g.

[0062] Embodiment 14 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 60 min, the size of the grinding beads of 1.6 mm, the filling amount of the grinding beads of 0.25 kg, and the speed of the wet ball mill of 1500 rpm.

[0063] The specific surface area of ​​zero-valent iron obtained in Example 14 is 11.746 m 2 / g.

[0064] Embodiment 15 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 60 min, the size of the grinding beads of 2 mm, the filling amount of the grinding beads of 0.4 kg, and the speed of the wet ball mill of 1800 rpm.

[0065] The specific surface area of ​​zero-valent iron obtained in Example 15 is 15.987 m 2 / g.

[0066] Example 16 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 100 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 1200 rpm.

[0067] The specific surface area of ​​zero-valent iron obtained in Example 16 is 14.965 m 2 / g.

[0068] Embodiment 17 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 100 min, the size of the grinding beads of 0.8 mm, the filling amount of the grinding beads of 0.75 kg, and the speed of the wet ball mill of 1500 rpm.

[0069] The specific surface area of ​​zero-valent iron obtained in Example 17 is 15.663 m 2 / g.

[0070] Embodiment 18 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 100 min, the size of the grinding beads of 1 mm, the filling amount of the grinding beads of 0.25 kg, and the speed of the wet ball mill of 1800 rpm.

[0071] The specific surface area of ​​zero-valent iron obtained in Example 18 is 12.664 m 2 / g.

[0072] Embodiment 19 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 100 min, the size of the grinding beads of 1.6 mm, the filling amount of the grinding beads of 0.4 kg, and the speed of the wet ball mill of 2000 rpm.

[0073] The specific surface area of ​​zero-valent iron obtained in Example 19 is 13.665 m 2 / g.

[0074] Embodiment 20 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 100 min, the size of the grinding beads of 2 mm, the filling amount of the grinding beads of 0.5 kg, and the speed of the wet ball mill of 1000 rpm.

[0075] The specific surface area of ​​zero-valent iron obtained in Example 20 is 15.767 m 2 / g.

[0076] Embodiment 21 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.75 kg, and the speed of the wet ball mill of 1800 rpm.

[0077] The specific surface area of ​​zero-valent iron obtained in Example 21 is 13.667 m 2 / g.

[0078] Embodiment 22 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 200 min, the size of the grinding beads of 0.8 mm, the filling amount of the grinding beads of 0.25 kg, and the speed of the wet ball mill of 2000 rpm.

[0079] The specific surface area of ​​zero-valent iron obtained in Example 22 is 8.651 m 2 / g.

[0080] Embodiment 23 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 200 min, the size of the grinding beads of 1 mm, the filling amount of the grinding beads of 0.4 kg, and the speed of the wet ball mill of 1000 rpm.

[0081] The specific surface area of ​​zero-valent iron obtained in Example 23 is 10.687 m 2 / g.

[0082] Embodiment 24 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 200 min, the size of the grinding beads of 1.6 mm, the filling amount of the grinding beads of 0.5 kg, and the speed of the wet ball mill of 1200 rpm.

[0083] The specific surface area of ​​zero-valent iron obtained in Example 24 is 11.921 m 2 / g.

[0084] Embodiment 25 Based on Example 1, the grinding time of 200 min, the size of the grinding beads of 0.4 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 2000 rpm were replaced by: the grinding time of 200 min, the size of the grinding beads of 2 mm, the filling amount of the grinding beads of 0.625 kg, and the speed of the wet ball mill of 1500 rpm.

[0085] The specific surface area of ​​zero-valent iron obtained in Example 25 is 13.993 m 2 / g.

[0086] Based on the significance analysis of the experimental results of Examples 1-25, the following key conclusions can be obtained: Ball milling time: Ball milling time is the most important factor affecting the specific surface area of ​​ZVI. Experiments show that with the increase of ball milling time, the specific surface area increases significantly. At 200 minutes, the specific surface area of ​​ZVI reaches its maximum value, and further extension of the time will no longer significantly increase the specific surface area.

[0087] Bead size: Bead size also has a significant effect on specific surface area. Smaller beads (0.4 mm and 0.8 mm) are more effective in increasing specific surface area, especially at longer milling times. Larger beads (2.0 mm) are more effective in breaking up particles, but have a relatively small effect on increasing specific surface area.

[0088] Ball milling bead filling amount: The effect of ball milling bead filling amount on specific surface area cannot be ignored. Experiments show that when the filling amount is 0.625 kg, the specific surface area of ​​ZVI is the largest. Too high or too low filling amount will reduce the grinding efficiency, thus affecting the specific surface area.

[0089] The effect of the stirring shaft speed of the wet ball mill on the specific surface area is that a higher speed (2000 rpm) is more conducive to the increase of the specific surface area. However, too high a speed may cause excessive particle crushing, which in turn affects the physical properties of the material.

[0090] The influence of the above four factors on the specific surface area is in the order of ball milling time > rotation speed > bead size > bead mass.

[0091] A variance analysis was performed based on the experimental results of Examples 1-25, and the analysis results are shown in the following table.

[0092] Table 1 Variance analysis table Table 1 is a variance analysis table of the experimental results of Examples 1-25.

[0093] Among them, the F value is a statistic used to test whether the joint impact of all independent variables on the dependent variable is significant. The P value is mainly used to test the significance of the regression coefficient. The smaller the P value, the stronger the significance.

[0094] According to the above table, ball milling time has a very significant effect on the specific surface area (P<0.01), shaft speed has a slightly significant effect on the specific surface area (P<0.05), and bead size and bead mass have no significant effect on the specific surface area (P>0.05).

[0095] MATLAB (Matrix Laboratory) was used to fit and extract the discrete experimental data, and the regression equation was used to represent the functional relationship between the specific surface area of ​​zero-valent iron ball milling for 200 min and the ball milling parameters. Specifically, the first step was to normalize the data (1): (1) Then assume the regression equation (2): (2) in =1 is the bias term. The loss equation is shown in (3: (3) The updated regression equation (4) is obtained by using the gradient descent method: (4) In the formula, is the learning rate.

[0096] When performing regression analysis, 80% of the experimental data set was selected to build the model, 20% of the data set was used to verify the model, the learning rate was set to 0.01, and the number of iterations was 3000.

[0097] Table 2 Normalized model data table Table 2 is a table of specific surface area data detected after 65 experiments with different process parameters. A regression model is established based on the above data.

[0098] Table 3 Regression model Table 3 shows the regression model established to determine the effects of ball milling time, ball milling bead size, ball milling bead filling amount, and rotation speed on specific surface area, where A represents the ball milling time, B represents the ball milling bead size, C represents the ball milling bead filling amount, and D represents the stirring shaft speed of the wet ball mill.

[0099] R 2 It is used to measure the strength of the relationship between the model and the dependent variable. For the training set and the test set, R 2 They are 94.5% and 92.0%, respectively, indicating that the established model can guide the modulation of parameters to accurately prepare zero-valent iron with a certain specific surface area, thereby realizing customized production of materials.

[0100] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and 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, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing zero-valent iron with a quantitative specific surface area, characterized in that: The preparation method is as follows: S1, adding zero-valent iron powder and anhydrous ethanol into a container, and stirring evenly to form a slurry to be ground; S2, loading grinding beads into a wet ball mill, adding the slurry to be ground into the wet ball mill for grinding to obtain slurry, and using a cooling system to keep the temperature stable during the grinding process; S3, taking out the slurry from the wet ball mill, and placing the slurry into a magnetic separation device for separation; as well as S4, placing the separated zero-valent iron particles in a vacuum drying oven and drying them at a temperature below 40°C, The grinding time is 10-200 min, the size of the grinding beads is 0.4-2.0 mm, the filling amount of the grinding beads is 0.25-0.75 kg, and the stirring shaft speed of the wet ball mill is 1000-2000 rpm.

2. The method for preparing zero-valent iron with a quantitative specific surface area according to claim 1, characterized in that: in, The specific surface area of ​​zero-valent iron obtained by ball milling is controlled by controlling the ball milling time, ball milling bead size, ball milling bead filling amount and stirring shaft speed of the wet ball mill. The relationship between the specific surface area of ​​zero-valent iron and the parameters in the ball milling process is: Y=-0.021+0.423×A+0.024×B+0.421×C-0.240×D-0.461×A×A+0.222×B×B+0. 267×C×C+0.543×D×D+0.299×A×B+0.190×A×C+0.004×A×D-0.465×B×C+0.004×B×D-0.165×C×D-0.410×A×B×C-0.055×A×B×D+0.304×A×C×D+0.135×B×C×D, where Y represents the specific surface area (m 2 / g), A represents the ball milling time (min), B represents the ball milling bead size (mm), C represents the ball milling bead filling amount (kg), and D represents the stirring shaft speed of the wet ball mill (rpm).

3. The method for preparing zero-valent iron with quantitative specific surface area according to claim 1, characterized in that: in, The grinding beads are zirconium oxide grinding beads.

4. The method for preparing zero-valent iron with a quantitative specific surface area according to claim 2, characterized in that: in, The size of the grinding beads is 0.4-0.8 mm.

5. The method for preparing zero-valent iron with quantitative specific surface area according to claim 1, characterized in that: in, The grinding time is 180-200 min.

6. The method for preparing zero-valent iron with a quantitative specific surface area according to claim 1, characterized in that: in, The filling amount of the grinding beads is 0.6-0.65 kg.

7. The method for preparing zero-valent iron with a quantitative specific surface area according to claim 1, characterized in that: in, The rotation speed of the wet ball mill is 1900-2000 rpm.

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