A silica microsphere-coated stainless steel particle composite material, its preparation method and application

Abstract

The application discloses a kind of silica microsphere coated stainless steel particle composite material and its preparation method and application.Hydrochloric acid dopamine, trihydroxy methyl aminomethylane, polyethylene imine are dispersed in anhydrous ethanol solution by stirring and ultrasonic, and tetraethyl orthosilicate is added drop by drop, after tetraethyl orthosilicate hydrolysis, stainless steel particles are added, after constant temperature oscillation, it is washed with deionized water, and silica microsphere coated stainless steel particle composite material is obtained.The application has the advantages of simple preparation method, low energy consumption in preparation process and cheap raw materials, the obtained composite material is wrapped by silica with excellent hydrophilicity and adsorption, which significantly improves the hydrophilicity and pollutant removal capacity of the composite material, and the composite material has high softening efficiency, fast softening speed, reusability and good regeneration when applied to three-dimensional particle electrode electrochemical method for softening drinking water, and has great application prospect in water treatment field.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, and in particular to a silica microsphere-coated stainless steel particle composite material, its preparation method, and its application. Background Technology

[0002] In recent years, drinking water hardness has become a major concern regarding water quality indicators. Although the hardness of water leaving water treatment plants is generally below the standard limit (450 mg / L) stipulated in the "Standards for Drinking Water Quality" (GB5749-2022), problems such as aging water supply networks mean that the hardness of drinking water delivered to households often exceeds the standard. This results in poor taste, limescale buildup, and health hazards, significantly impacting user experience and contradicting the current emphasis on "smart water management." Limescale is formed during the boiling process by the combined action of calcium and magnesium ions and alkalinity. When the water temperature is not elevated, the HCO3- in the water... 3- Ca 2+ Mg 2 + OH- is in a state of dissolution equilibrium. When the water temperature rises, OH- reacts with HCO3-. 3- The reaction produces CO3 2- CO3 2- With Ca 2+ CaCO3 and OH are formed. - With Mg 2+ Mg(OH)₂ is formed. As the water temperature rises further, the solubility product of calcium carbonate and magnesium hydroxide decreases, causing scale to precipitate. Although scale settles on the container walls, some fine particles remain that cannot be effectively precipitated. These particles enter the body with drinking water, where calcium carbonate decomposes into calcium carbonate in an acidic environment. 2+ If absorbed by the human body and consumed for extended periods, high-hardness water can lead to serious health problems such as kidney failure and kidney stones. Furthermore, studies have shown that calcium ions can cause bioaccumulation, increasing the concentration of heavy metal ions in water and harming human health; magnesium hydroxide decomposes into Mg in acidic environments. 2+ Once absorbed by the body, magnesium toxicity often manifests with an amplified effect. In cases of hypocalcemia or uremia, magnesium toxicity is enhanced, potentially leading to neurological disorders.

[0003] In recent years, research on reducing drinking water hardness has increased significantly. Among the more widely used methods are lime softening, ion exchange softening, membrane softening, and electrochemical softening. Lime softening effectively reduces water hardness, but the long-term addition of chemicals is highly corrosive to water supply pipes and may introduce new harmful substances into the water. Ion exchange softening requires regeneration of the ion exchange resin, making the process complex and costly. Membrane softening requires additional pressure, resulting in high costs and low hardness, but it can corrode pipes. Electrochemical softening of drinking water is currently a hot research topic. It is simple to operate, requires no chemical addition, avoids secondary pollution, produces disinfectant in the effluent, and requires little space, making it a promising area for application in the field of electrochemical water softening.

[0004] Electrochemical water softening primarily involves redox reactions at the anode and cathode. During electrolysis, oxidation occurs at the anode, producing oxygen and chlorine, while reduction occurs at the cathode, generating hydrogen and hydroxide ions. These hydroxide ions combine with bicarbonate ions in the water to form carbonate ions, which in turn combine with hardness ions to form precipitates, reducing hardness. However, electrochemical softening methods suffer from several drawbacks: low electrochemical deposition load, poor long-term operational stability, and slow softening speed. Therefore, developing electrochemical softening reaction systems with high deposition load and high softening efficiency is of great significance. A higher deposition load can be achieved by adding conductive particles to the cathode to form a three-dimensional electrode; current experimental data indicate that the three-dimensional particle electrode method can achieve a high hardness removal rate, but it requires a large current and a long softening time.

[0005] Therefore, it is urgent to develop a particle electrode that is simple to prepare, has low material cost, fast reaction speed, good conductivity, and good renewability. Summary of the Invention

[0006] To address the problems of low deposition load, easy cathode deactivation, slow softening speed, and high energy consumption in existing electrochemical methods for softening drinking water, this invention provides a silica microsphere-coated stainless steel particle composite material, its preparation method, and its application. The method described in this invention first dissolves dopamine hydrochloride, tris(hydroxymethyl)aminomethane, and polyethyleneimine in anhydrous ethanol. Then, tetraethyl silicate is added dropwise to complete the hydrolysis of tetraethyl silicate. Finally, the silica microspheres generated by the hydrolysis and condensation are attached to stainless steel particles by shaking, resulting in the silica microsphere-coated stainless steel particle composite material. Furthermore, the invention also provides the application of this composite material in electrochemical softening of drinking water, which offers advantages such as rapid softening speed, high deposition load, and good regenerability.

[0007] The first objective of this invention is to provide a silica microsphere-coated stainless steel particle composite material, wherein the silica microsphere-coated stainless steel particle composite material has a core-shell structure, with stainless steel particles as the core and silica microspheres as the shell, and the surface of the silica microspheres contains silanol groups.

[0008] In one embodiment of the present invention, the stainless steel particles have a particle size of 1.5 mm; the thickness of the silica microsphere layer is 80-150 nm.

[0009] The second objective of this invention is to provide a method for preparing the aforementioned silica microsphere-coated stainless steel particle composite material, comprising the following steps:

[0010] (1) Tris(hydroxymethyl)aminomethane, dopamine hydrochloride and polyethyleneimine are mixed and added to an ethanol mixture solution, and ultrasonically dispersed to obtain a mixture of dopamine hydrochloride and ethanol;

[0011] (2) Add tetraethyl silicate to the mixture obtained in step (1), stir and hydrolyze to obtain a solution of tetraethyl silicate hydrolysis;

[0012] (3) Add stainless steel particles to the solution of tetraethyl silicate hydrolysis obtained in step (2), and oscillate at a constant temperature to obtain the silica microsphere-coated stainless steel particle composite material.

[0013] In this invention, dopamine hydrochloride serves to provide adhesion, enabling the silica microspheres generated by hydrolysis to adhere to the surface of stainless steel particles.

[0014] In one embodiment of the present invention, in step (1), at least one or more of the following conditions are satisfied:

[0015] The mass ratio of the tris(hydroxymethyl)aminomethane, dopamine hydrochloride, and polyethyleneimine is (3.6:2.4:1)-(3:1:1).

[0016] The ethanol mixture is composed of ethanol, water, and ammonia; the volume ratio of ethanol, water, and ammonia is (20:6:1) to (20:2:1); further, the water is preferably ultrapure water; and the ethanol is preferably anhydrous ethanol.

[0017] In one embodiment of the present invention, the ultrasonic dispersion time is 30-75 min.

[0018] In one embodiment of the present invention, in step (2), the mass ratio of the mixture to tetraethyl silicate is 30:1-15:1.

[0019] In one embodiment of the present invention, in step (2), the hydrolysis time is 3-8 min.

[0020] In one embodiment of the present invention, in step (3), the temperature of the isothermal oscillation is 15-25°C, the rotation speed is 110-130 rpm, and the oscillation lasts for 4-12 hours.

[0021] A third objective of this invention is to provide the application of the aforementioned silica microsphere-coated stainless steel particle composite material in water softening.

[0022] In one embodiment of the present invention, the water softening process includes an electrode reactor; the electrode reactor uses the silica microsphere-coated stainless steel particle composite material as a three-dimensional particle electrode, a titanium electrode as a cathode, and a ruthenium-based coated titanium as an anode.

[0023] In a specific embodiment of the present invention, a silica microsphere-coated stainless steel particle composite material is placed on the cathode, and hard water passes sequentially from bottom to top through the cathode, the composite material, and the anode; wherein a titanium mesh (50 mm in diameter) is used as the cathode, and ruthenium-coated titanium (50 mm in diameter) is used as the anode, and a through-flow reactor is set up. Electrochemical softening is performed, and the hardness of the influent water is 500 ppm (calculated as calcium carbonate).

[0024] Furthermore, the operating current density is 50-300 A / m 2 The reaction time is 5-30 minutes.

[0025] The technical solution of the present invention has the following advantages compared with the prior art:

[0026] (1) In this invention, silica microspheres with good dispersibility were prepared by hydrolysis and condensation of tetraethyl silicate in an alkaline environment. Then, the silica microspheres were tightly bonded to stainless steel particles by the adhesive properties of dopamine hydrochloride, forming a silica microsphere-coated stainless steel particle composite material. The silanol groups of the silica microspheres have an adsorption effect on hardness ions, and the electrochemical process further improves the softening efficiency.

[0027] (2) The raw materials of the present invention are cheap and readily available, the preparation method is simple and the preparation process has low energy consumption.

[0028] (3) Compared with existing electrochemical softening technologies, the composite material synthesized in this invention has a fast electrochemical softening speed, high efficiency, and good renewability, and has great application prospects in the treatment of electrochemically softened drinking water. Attached Figure Description

[0029] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0030] Figure 1 The image shows the 10-minute hardness removal effect of the composite materials synthesized in Examples 1-3 of this invention.

[0031] Figure 2 The image shows the 15-minute hardness removal effect of the composite materials synthesized in Examples 1-3 of this invention.

[0032] Figure 3 This is a SEM characterization image of the composite material synthesized in Example 1 of the present invention.

[0033] Figure 4 This is a SEM characterization image of the composite material synthesized in Example 2 of the present invention.

[0034] Figure 5 This is a SEM characterization image of the composite material synthesized in Example 3 of the present invention. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0036] Example 1:

[0037] This embodiment provides a method for preparing and applying a silica microsphere-coated stainless steel particle composite material, as detailed below:

[0038] (1) Preparation method: 10 ml of ultrapure water and 5 ml of ammonia (mass concentration of 28%) were added to 100 ml of anhydrous ethanol. Then, 1.8 g of tris(hydroxymethyl)aminomethane, 1.2 g of dopamine hydrochloride, and 0.5 g of polyethyleneimine were added to the above mixed solution. The mixture was then ultrasonically dispersed for 60 min. 7 ml of tetraethyl silicate solution was added dropwise to the above mixed solution, and the mixture was stirred and hydrolyzed for 5 min. After the tetraethyl silicate was hydrolyzed, 24 g of 304 stainless steel particles were added to the solution. The mixture was self-assembled in a constant temperature shaking oven for 8 hours to obtain a silica microsphere-coated stainless steel particle composite material. The structure of the obtained material was characterized, and the results are shown in the figure. Figure 3 .

[0039] (2) Application: 12g of the silica microsphere-coated stainless steel particle composite material prepared in (1) was placed on the cathode. Hard water passed from bottom to top through the cathode, the composite material, and the anode. A through-type reactor was set up with a titanium mesh (50mm in diameter) as the cathode and a ruthenium-coated titanium (50mm in diameter) as the anode. Electrochemical softening was performed with an influent water hardness of 500ppm (calculated as calcium carbonate) and a working current density of 300A / m³. 2 The reaction time is 15 minutes. The first 10 minutes remove hardness as... Figure 1 As shown, the hardness removal in the first 15 minutes is as follows: Figure 2As shown, when silica microsphere-coated stainless steel particle composite material is used as a three-dimensional electrode in a through-flow reactor, it can reduce the hardness of the influent to 250 ppm (calculated as calcium carbonate) in a short time, meeting the hardness requirements of drinking water. Electrochemical softening for 10 minutes removes 224 ppm of hardness, and softening for 15 minutes removes 250 ppm of hardness.

[0040] Example 2:

[0041] This embodiment provides a method for preparing a silica microsphere-coated stainless steel particle composite material and its application, as detailed below:

[0042] (1) Preparation method: 10 ml of ultrapure water and 5 ml of ammonia (mass concentration of 28%) were added to 100 ml of anhydrous ethanol. Then, 1.8 g of tris(hydroxymethyl)aminomethane, 1.2 g of dopamine hydrochloride, and 0.5 g of polyethyleneimine were added to the above mixed solution. The mixture was then ultrasonically dispersed for 60 min. 7 ml of tetraethyl silicate solution was added dropwise to the above mixed solution, and the mixture was stirred and hydrolyzed for 5 min. After the tetraethyl silicate was hydrolyzed, 24 g of stainless steel particles were added to the solution. The mixture was self-assembled in a constant temperature shaking oven for 8 hours to obtain a silica microsphere-coated stainless steel particle composite material. The structure of the obtained material was characterized, and the results are shown in the figure. Figure 4 .

[0043] (2) Application: 12g of silica microspheres coated with stainless steel particles were placed on the cathode. Hard water was passed from bottom to top through the cathode, the composite material, and the anode. A through-flow reactor was used with a titanium mesh (50mm in diameter) as the cathode and ruthenium-coated titanium (50mm in diameter) as the anode. Electrochemical softening was performed with an influent water hardness of 500ppm (calculated as calcium carbonate) and an operating current density of 300A / m³. 2 The reaction time is 15 minutes. The first 10 minutes remove hardness as... Figure 1 As shown, the hardness removal in the first 15 minutes is as follows: Figure 2 As shown, the silica microsphere-coated stainless steel particle composite material, when used as a three-dimensional electrode in a through-flow reactor, can reduce the hardness of the influent to 250 ppm (calculated as calcium carbonate) in a short time, meeting the hardness requirements for drinking water. Electrochemical softening for 10 minutes removes 157 ppm of hardness, and softening for 15 minutes removes 236 ppm of hardness.

[0044] Example 3:

[0045] This embodiment provides a method for preparing a silica microsphere-coated stainless steel particle composite material and its application, as detailed below:

[0046] (1) Preparation method: 10 ml of ultrapure water and 5 ml of ammonia (mass concentration of 28%) were added to 100 ml of anhydrous ethanol. Then, 1.8 g of tris(hydroxymethyl)aminomethane, 1.2 g of dopamine hydrochloride, and 0.5 g of polyethyleneimine were added to the above mixed solution. The mixture was then ultrasonically dispersed for 60 min. 7 ml of tetraethyl silicate solution was added dropwise to the above mixed solution, and the mixture was stirred and hydrolyzed for 5 min. After the tetraethyl silicate was hydrolyzed, 24 g of stainless steel particles were added to the solution. The mixture was self-assembled in a constant temperature shaking oven for 12 hours to form a silica microsphere-coated stainless steel particle composite material. The structure of the obtained material was characterized, and the results are shown in the figure. Figure 5 .

[0047] (2) Application: 12g of silica microspheres coated with stainless steel particles were placed on the cathode. Hard water was passed from bottom to top through the cathode, the composite material, and the anode. A through-flow reactor was used with a titanium mesh (50mm in diameter) as the cathode and ruthenium-coated titanium (50mm in diameter) as the anode. Electrochemical softening was performed with an influent water hardness of 500ppm (calculated as calcium carbonate) and an operating current density of 300A / m³. 2 The reaction time is 15 minutes. The first 10 minutes remove hardness as... Figure 1 As shown, the hardness removal in the first 15 minutes is as follows: Figure 2 As shown, the silica microsphere-coated stainless steel particle composite material, when used as a three-dimensional electrode in a through-flow reactor, can reduce the hardness of the influent to 250 ppm (calculated as calcium carbonate) in a short time, meeting the hardness requirements for drinking water. Electrochemical softening for 10 minutes removes 107 ppm of hardness, and softening for 15 minutes removes 200 ppm of hardness.

[0048] Comparative Example 1:

[0049] This comparative example provides a method for electrochemical water softening. The application of this method is the same as in the examples, except that silica microspheres are not attached to the surface of the stainless steel particles. The effect of the method obtained in this comparative example on electrochemical water softening is shown in Table 1.

[0050] Comparative Example 2:

[0051] This comparative example provides a method for electrochemical water softening. The application of this method is the same as in the examples, except that stainless steel particles are not added to the reactor. The effect of the method obtained in this comparative example on electrochemical water softening is shown in Table 1.

[0052] Table 1 compares the softening effects of Examples 1-3 and Comparative Examples 1-2 over 15 minutes.

[0053]

[0054]

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a composite material of silica microspheres coated stainless steel particles, characterized by: The method comprises the following steps: (1) mixing trimethylolamine, dopamine hydrochloride and polyethyleneimine, adding an ethanol mixed solution, and ultrasonic dispersion to obtain a mixture of dopamine hydrochloride and ethanol; (2) adding tetraethyl silicate to the mixture obtained in step (1), stirring and hydrolyzing to obtain a tetraethyl silicate hydrolysis solution; (3) adding stainless steel particles to the tetraethyl silicate hydrolysis solution obtained in step (2), constant temperature oscillation to obtain the silica microsphere coated stainless steel particle composite material; The silica microsphere coated stainless steel particle composite material has a core-shell structure, wherein the stainless steel particle is the core, the silica microsphere layer is the shell, and the surface of the silica microsphere layer contains silicon hydroxyl groups. The thickness of the silica microsphere layer is 80-150 nm. In step (1), the mass ratio of trimethylolamine, dopamine hydrochloride and polyethyleneimine is (3.6:2.4:1)-(3:1:1).

2. The production method according to claim 1, characterized by, In step (1), the ethanol mixed solution is composed of ethanol, water and ammonia water; the volume ratio of ethanol, water and ammonia water is (20:6:1)-(20:2:1). The ultrasonic dispersion time is 30-75 min.

3. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of the mixture to tetraethyl silicate is 30:1-15:

1.

4. The method of claim 1, wherein, In step (2), the hydrolysis time is 3-8 min.

5. The preparation method according to claim 1, characterized in that, In step (3), the constant temperature oscillation temperature is 15-25℃, the rotation speed is 110-130 rpm, and the oscillation time is 4-12 hours.

6. The application of the preparation method of the silica microsphere coated stainless steel particle composite material in claim 1 in water softening.

7. Use according to claim 6, characterized in that, The water softening process comprises an electrode reactor; the electrode reactor uses the silica microsphere coated stainless steel particle composite material as a three-dimensional particle electrode, a titanium electrode as a cathode, and a ruthenium coated titanium as an anode.

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