Stainless steel dust resource recycling catalyst material and preparation method thereof

Abstract

The application belongs to the technical field of inorganic nonmetallic materials, and discloses a stainless steel dust resource recycling and regenerating catalytic material and a preparation method thereof, which comprises the following steps: S1, placing the stainless steel powder in an H2SO4 solution for purification, separating solid precipitates, washing, and drying; S2, adding the purified sample into an etching solution for etching treatment, washing, and drying; wherein the etching solution is an FeCl3 solution, an NaOH solution, or a CuCl2 solution; and S3, placing the etched sample in a muffle furnace for heat treatment; the stainless steel solid waste is prepared into a heterogeneous catalytic material with activated persulfate performance, the preparation method is simple, the cost is low, the catalytic performance of the prepared catalytic material is good, the material is applied to harmless treatment of refractory organic pollutant wastewater, and the dual goals of "waste treatment with waste" and "resource recycling and regeneration" are realized.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials technology, specifically to a catalytic material for the resource-based regeneration of stainless steel dust and its preparation method. Background Technology

[0002] With the progress of human society and the continuous upgrading of industrial technology, the market demand for stainless steel hardware products has shown a significant growth trend. However, in the process of its vigorous production and manufacturing, two types of pollutants that pose a serious challenge to the ecological environment are inevitably generated: solid waste and organic pollutant wastewater. These pollutants, when discharged into the environment without effective treatment, pose an increasingly serious potential risk to water bodies and soil, becoming a major bottleneck restricting the green and sustainable development of the industry.

[0003] In stainless steel production, solid waste mainly exists in two forms: stainless steel slag and stainless steel dust. Stainless steel dust, as a key byproduct of core processes such as smelting and refining, typically has a lower gangue content than stainless steel slag. Stainless steel dust has a complex composition and is rich in high-value metallic elements, particularly iron oxide, with a grade even exceeding that of some natural iron ores. Furthermore, it is enriched with strategic metal resources such as chromium (Cr) and nickel (Ni), which have significant economic value and environmental sensitivity. This indicates that stainless steel dust possesses enormous resource recovery potential. However, current disposal methods for these solid wastes, especially stainless steel dust, primarily involve stockpiling or landfilling. This not only occupies land resources but also poses a risk of leaching and migration of soluble heavy metals, creating long-term environmental hazards. In the deep processing of stainless steel, such as the coloring of cups and kettles, large amounts of organic pigments and dyes are used, resulting in high-color, recalcitrant organic dye wastewater. Simultaneously, the oily cutting fluid wastewater used in machining processes such as cutting and grinding is also a significant concern. These wastewaters share common characteristics: high concentrations of emulsified oil, metal shavings, surfactants, and a large amount of complex, highly toxic organic pollutants. Their total organic carbon (TOC) and chemical oxygen demand (COD) levels, characteristic of their pollution load, are extremely high. Traditional biological treatment processes have limited efficiency in treating this type of high-concentration, recalcitrant organic wastewater. Highly efficient and deep purification technologies are urgently needed.

[0004] Based on sulfate free radicals (SO4) •- The persulfate advanced oxidation technology has shown great promise in the deep removal of recalcitrant organic pollutants. Its core mechanism lies in utilizing transition metal catalytic activation of persulfate, which decomposes to produce SO4 through an electron transfer mechanism. •-This technology can achieve efficient oxidative decomposition and even mineralization of stubborn persistent organic pollutants in industrial and medical wastewater. However, the preparation of efficient transition metal catalysts (such as cobalt, noble metal-based materials, or complex metal oxide / composite materials) is usually complex, requires harsh conditions, and is costly, which severely restricts the widespread application of this technology. Furthermore, the recovery and regeneration of the catalyst after the reaction are difficult, making it challenging to achieve both large-scale production and cost-effective engineering applications. Summary of the Invention

[0005] This invention aims to provide a catalytic material for the resource-based regeneration of stainless steel dust and its preparation method. Stainless steel solid waste is purified, etched, and heat-treated to prepare a heterogeneous catalytic material with persulfate-activating properties. The preparation method is simple and low-cost, and the prepared catalytic material exhibits good catalytic performance. When applied to the harmless treatment of recalcitrant organic pollutant wastewater, this material can effectively activate persulfate to generate strong oxidizing free radicals, achieving efficient degradation of organic matter and realizing the dual goals of "waste treatment" and "resource recycling."

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a catalytic material for the resource-based regeneration of stainless steel dust includes the following steps:

[0008] S1. Stainless steel powder is placed in H2SO4 solution for purification. After purification, the solid precipitate is separated by centrifugation, and the impurities in the precipitate are washed with deionized water and anhydrous ethanol. The sample is then dried to obtain the purified sample.

[0009] S2. Add the purified sample to the etching solution, stir it at a preset temperature using hydrothermal method, and perform etching treatment. After etching is completed, wash it with deionized water and anhydrous ethanol, and dry it to obtain the etched sample. The etching solution is FeCl3 solution, NaOH solution or CuCl2 solution.

[0010] S3. The etched sample is placed in a muffle furnace for heat treatment to obtain stainless steel regenerated catalyst material.

[0011] Further, in S1, the purification steps are as follows: heat the 0.5~1.5 mol / L H2SO4 solution to 40~50℃ in a water bath, and then place the stainless steel powder in the H2SO4 solution and let it stand for 12~24 h.

[0012] Furthermore, in S1, stainless steel includes 304 stainless steel, 316 stainless steel and 410 stainless steel.

[0013] Furthermore, in S2, the concentration of the etching solution is 0.5~1.5 mol / L; the preset temperature is 50~70℃; and the etching time is 2~3h.

[0014] Furthermore, in S3, the heat treatment temperature is 300~600℃.

[0015] The stainless steel dust resource recycling catalyst material is prepared according to the above-described method.

[0016] The beneficial effects of the technical solution are:

[0017] This invention treats stainless steel solid waste (especially stainless steel dust rich in iron, chromium, nickel, etc.) as a valuable "secondary resource." Through a green and efficient resource-based regeneration process, including purification, etching, and heat treatment, a heterogeneous catalytic material with persulfate-activating properties is prepared. The preparation method is simple, low-cost, and yields a catalytic material with good catalytic performance and high degradation rate. This material can be applied to the harmless treatment of recalcitrant organic pollutant wastewater (such as dye wastewater and cutting fluid wastewater), effectively activating persulfate to generate strong oxidizing free radicals (SO4). •- This method utilizes hydroxyl groups (such as hydroxyl groups and hydroxyl groups) to achieve efficient degradation of organic matter. It not only provides a high-value utilization pathway for stainless steel solid waste but also develops an innovative method for treating high-concentration organic wastewater at a high efficiency and low cost, essentially achieving the dual goals of "treating waste with waste" and "resource recycling."

[0018] Specifically, this invention uses XRD, SEM, XPS, VSM, and BET analytical techniques to qualitatively analyze the catalytic materials. The experiments used Rhodamine B, methyl orange dye, and tetracycline hydrochloride as target pollutants. Persulfate was activated using stainless steel regenerated catalytic materials to construct a degradation reaction system. The catalytic performance of the stainless steel regenerated catalytic materials was evaluated by the degradation rate of the target pollutants. The degradation experiment results showed that among the three types of stainless steel slag, the 410 stainless steel slag etched with CuCl2 exhibited excellent catalytic degradation performance. In the Rhodamine B degradation experiment, its degradation efficiency reached 99.5% after 30 min. In the subsequent methyl orange degradation experiment, the degradation efficiency reached 99% after 5 min and 99% after 30 min. In the tetracycline hydrochloride (TCH) degradation experiment, the degradation efficiency reached 83% after 30 min. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the stainless steel dust resource recycling catalytic material of the present invention.

[0020] Figure 2The figures show the XRD patterns of stainless steel powder and its derivatives; in the figures, (a) is the XRD pattern of 304 stainless steel powder and its derivatives; (b) is the XRD pattern of 316 stainless steel powder and its derivatives; and (c) is the XRD pattern of 410 stainless steel powder and its derivatives.

[0021] Figure 3 SEM images of stainless steel powder and its purified and heat-treated samples are shown. In the image, (a) is sample Initial-304, (b) is sample Purified-304, (c) is sample CP-304, (d) is sample CPHT-304-T300, (e) is sample CPHT-304-T600, (f) is sample Initial-316, and (g) is sample Purified-304-T600. d-316, (h) is the designation CP-316, (i) is the designation CPHT-316-T300, (j) is the designation CPHT-316-T600, (k) is the designation Initial-410, (l) is the designation Purified-410, (m) is the designation CP-410, (n) is the designation CPHT-410-T300, and (o) is the designation CPHT-410-T600;

[0022] Figure 4 The XPS full spectrum of the present invention sample CPHT-410-T300;

[0023] Figure 5 The figure shows the fine XPS spectrum of the CPHT-410 sample of the present invention; in the figure, (a) is the fine XPS spectrum of C1s orbital, (b) is the fine XPS spectrum of O1s orbital, (c) is the fine XPS spectrum of Cu2p orbital, and (d) is the fine XPS spectrum of Fe2p orbital.

[0024] Figure 6 The N2 adsorption / desorption isotherm and pore size distribution of the CPHT-410-T300 sample of this invention;

[0025] Figure 7 This invention illustrates the effects of purification treatment and etching solution type on the degradation performance of stainless steel powder. In the figure, (a) compares the degradation performance of 304, 316, and 410 stainless steel raw materials; (b) shows the effect of purification treatment on the degradation performance of the three stainless steel raw materials; (c) shows the effect of CuCl2 etching treatment on the degradation performance of the three stainless steel raw materials; (d) shows the effect of FeCl3 etching treatment on the degradation performance of the three stainless steel raw materials; (e) shows the effect of NaOH etching treatment on the degradation performance of the three stainless steel raw materials; and (f) shows the effect of different etchants on the degradation performance of 410 stainless steel.

[0026] Figure 8This invention illustrates the effect of heat treatment temperature on the degradation performance of CPHT-410 series samples.

[0027] Figure 9 This invention is used to evaluate the performance of different degradation systems.

[0028] Figure 10 This invention evaluates the degradation performance of the CPHT-410-T300 / PMS system for different organic pollutants.

[0029] Figure 11 The VSM hysteresis loop is the stainless steel powder raw material and its regenerated catalytic material of this invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments:

[0031] In related technologies, those based on sulfate radicals (SO4• - The persulfate advanced oxidation technology has shown great promise in the deep removal of recalcitrant organic pollutants. Its core mechanism lies in utilizing transition metal catalytic activation of persulfate, which decomposes to produce SO4•- through an electron transfer mechanism. - SO4• - It possesses advantages such as high standard oxidation potential (2.5~3.1 V vs. NHE), long half-life, and wide pH adaptability, enabling efficient oxidative decomposition and even mineralization of stubborn persistent organic pollutants in industrial and medical wastewater. However, the preparation of highly efficient transition metal catalysts (such as cobalt, noble metal-based materials, or complex metal oxide / composite materials) is usually complex, requires harsh conditions, and is costly, severely restricting the widespread application of this technology. Furthermore, the recovery and regeneration of the catalyst after the reaction are difficult, making it challenging to achieve both large-scale production and cost-effective engineering applications.

[0032] To address the two major challenges of resource utilization of stainless steel solid waste and deep treatment of organic wastewater, this invention creatively proposes a synergistic solution: treating stainless steel solid waste (especially stainless steel dust rich in iron, chromium, nickel, etc.) as a valuable "secondary resource," and preparing it into a heterogeneous catalytic material with persulfate activation properties through a green and efficient resource recycling process. This material, when applied to the harmless treatment of recalcitrant organic pollutant wastewater (such as dye wastewater, cutting fluid wastewater, etc.), can effectively activate persulfate to generate strong oxidizing free radicals (SO4•-). - This technology utilizes organic matter such as hydroxyl groups (OH, etc.) to achieve efficient degradation of organic matter. This approach not only provides a high-value utilization method for stainless steel solid waste, but also develops an innovative method for treating high-concentration organic wastewater at high efficiency and low cost, essentially achieving the dual goals of "treating waste with waste" and "resource recycling".

[0033] The preparation method of stainless steel dust resource recycling catalytic material includes the following steps:

[0034] S1. Heat 0.5~1.5 mol / L H2SO4 solution to 40~50℃ in a water bath, then place stainless steel powder in H2SO4 solution and let it stand for 12~24 h for purification. After purification, centrifuge to separate the solid precipitate, and wash the impurities in the precipitate with deionized water and anhydrous ethanol. Dry the sample to obtain the purified sample.

[0035] S2. Add the purified sample to the etching solution and place it in a water bath at 50~70℃. Keep stirring continuously for 2~3 hours for etching. After etching is completed, wash with deionized water and anhydrous ethanol, and dry to obtain the etched sample. The etching solution is FeCl3 solution, NaOH solution or CuCl2 solution, and the concentration of the etching solution is 0.5~1.5mol / L.

[0036] S3. Place the samples from S2 into a muffle furnace and heat-treat them at 300 ℃~600 ℃ in air atmosphere for 1.5~3 h to obtain stainless steel regenerated catalyst materials.

[0037] This invention is based on commercially available 304, 316, and 410 stainless steel powders, the chemical compositions of which are shown in Table 1:

[0038] Table 1. Chemical composition (mass fraction) of 304, 316 and 410 stainless steel powders

[0039]

[0040] The above-mentioned method for preparing regenerated catalytic materials from stainless steel dust (purification, etching, and heat treatment processes) regenerates persulfate catalytic materials for the catalytic degradation of organic pollutants in metal shavings wastewater and industrial wastewater. The preparation process is as follows: Figure 1 As shown, the specific preparation method is as follows:

[0041] (1) First, the three types of stainless steel powders were purified. 100 mL of H2SO4 solution (1 mol / L) was heated to 40°C in a water bath, and then the 304, 316, and 410 stainless steel powders were placed in the H2SO4 solution and allowed to stand for 24 h. After purification, the solid precipitate was separated by centrifugation, and impurities were washed with deionized water and anhydrous ethanol. After drying, the resulting products were named Purified-304, Purified-316, and Purified-410, respectively.

[0042] (2) A certain mass (1.0 g) of Purified-304, Purified-316, and Purified-410 samples were weighed and added to 100 mL of CuCl2 solution (1 mol / L). The solutions were placed in a 60℃ water bath and continuously stirred for 2 h for etching. After the reaction was complete, the samples were washed with deionized water and anhydrous ethanol, and dried. The resulting samples were named CP-304, CP-316, and CP-410, respectively. Furthermore, as comparative analysis samples, the Purified-304, Purified-316, and Purified-410 samples were etched using FeCl3 and NaOH solutions (1 mol / L), respectively, following a similar process. After FeCl3 etching, the resulting samples were named FP-304, FP-316, and FP-410. After etching with NaOH, the obtained samples were named NP-304, NP-316 and NP-410.

[0043] (3) After etching, the above samples were placed in a muffle furnace and heat-treated for 2 h at 300 ℃~600 ℃ in air atmosphere. Finally, persulfate catalyst materials regenerated from stainless steel powder were obtained and named CPHT-304, CPHT-316, CPHT-410, FPHT-304, FPHT-316, FPHT-410, NPHT-304, NPHT-316 and NPHT-410.

[0044] Qualitative analysis of the catalytic materials was performed using XRD, SEM, XPS, VSM, and BET methods. The effects of different types of stainless steel slag raw materials, etching solutions, and heat treatment temperatures on the phase composition, microstructure, and surface chemical state of the regenerated catalytic materials were investigated. Rhodamine B, methyl orange dye, and tetracycline hydrochloride were used as target pollutants. Persulfate was activated using the stainless steel regenerated catalytic materials to construct a degradation reaction system. The catalytic performance of the stainless steel regenerated catalytic materials was evaluated by the degradation rate of the target pollutants. The analytical results are as follows:

[0045] 1. Phase composition analysis:

[0046] The phase composition of 304, 316, and 410 stainless steel powders and their regenerated catalysts was characterized and analyzed using XRD. Figure 2As shown in (a), the XRD pattern of the Initial-304 sample exhibits sharp diffraction peaks at 2θ = 43.6º, 50.8º, and 74.7º. Comparison with the standard PDF No. 47-1405 card reveals that these peaks correspond to the (111), (200), and (220) crystal planes of the FeNi alloy phase, belonging to the cubic crystal system Fm-3m space group. The XRD pattern of the Purified-304 sample showed no significant change after purification, indicating that no phase transformation occurred during the purification process. Furthermore, after CuCl2 etching and heat treatment, no Cu-related phases were introduced into the CP-304, CPHT-304-T300, and CPHT-304-T300 samples.

[0047] like Figure 2 As shown in (b), obvious diffraction peaks appeared at 2θ=43.6º, 50.8º, and 74.7º in the XRD pattern of Initial-316 sample. Combined with the chemical composition analysis shown in Table 1, there was no significant difference in the phase composition between Initial-316 sample and Initial-304, and its phase composition did not change significantly after etching and heat treatment. Figure 3 (c) shows the XRD patterns of the 410 stainless steel powder and its regenerated catalyst. The Initial-410 sample exhibits distinct diffraction peaks at 2θ = 44.6º and 64.9º. Comparison with standard card PDF No. 06-0696 confirms that the Initial-410 sample is predominantly ferrite, belonging to the cubic crystal system, space group Im-3m. After purification, the phase structure did not change significantly. However, after CuCl2 etching, a new phase appeared. Heat treatment at 300℃ reduced the unstable crystalline phase and decreased the degree of crystallinity. When the heat treatment temperature was increased to 600℃, new diffraction peaks appeared, which may be related to CuCl2 oxidation fixation.

[0048] 2. Microscopic morphology analysis:

[0049] To investigate the effects of different processing steps on the microstructure of 304, 316, and 410 stainless steel and their regenerated catalysts, the microstructure of the prepared samples was analyzed using SEM. For example... Figure 3 As shown in (a), the Initial-304 samples all exhibited an irregular granular microstructure with a smooth surface and a particle size of approximately 30 μm. Figure 3 As shown in (b), the microstructure of the Purified-304 sample did not change significantly after purification. However, after CuCl2 etching, the CP-304 surface became passivated, which can be seen from... Figure 3(c) shows coarse particles and a fine porous structure. Furthermore, after heat treatment ( Figure 3 (d) and Figure 3 (e)) This surface retains its porous structure.

[0050] Furthermore, as shown in the SEM image of Initial-316 sample ( Figure 3 (f) The microstructure of Initial-316 sample is similar to that of Initial-304 sample, but after purification treatment ( Figure 3 (g) The Purified-316 sample was corroded by H2SO4 solution, resulting in a rough particle surface. After CuCl2 etching, a wrinkled structure was formed on the surface. Figure 3 (h)). After heat treatment, the CPHT-316 sample ( Figure 3 (i) and Figure 3 The microstructure of (j) is consistent with that of the CP-316 sample.

[0051] SEM images of the Initial-410 sample are as follows: Figure 3 As shown in (k), the particle size of the Initial-410 sample is approximately 50 μm. After purification ( Figure 3 (l) A noticeable open-pore structure appeared on the surface of the Purified-410 sample. After etching, the particle size of the CP-410 sample was significantly reduced. Figure 3 (m)). Image of the CPHT-410 sample after heat treatment ( Figure 3 (n) and Figure 3 The particle size of (o) gradually becomes uniform (5~10μm).

[0052] 3. Surface elemental chemical state analysis

[0053] X-ray photoelectron spectroscopy was used to analyze the chemical state of each element on the surface of the CPHT-410 sample. Figure 4 The image shows the XPS full spectrum of the CPHT-410 sample, where characteristic signals of Cu, Fe, C, and O can be observed. Other characteristic signals may be due to elements such as Cr, Mn, S, and P, but the specific reasons for these remain to be determined.

[0054] Figure 5 (a) is the fine XPS spectrum of the C1s orbital of the CPHT-410 sample. The binding energy peaks at 284.6 eV and 288.4 eV correspond to C-C bonds and C=O bonds, respectively. This indicates that inorganic carbon and adsorbed CO2 may exist on the surface of the CPHT-410 sample. Figure 5(b) is the fine XPS spectrum of the O1s orbital of the CPHT-410 sample. The binding energy peak at 531.6 eV is a characteristic peak of the MO bond, indicating that the surface metal of the CPHT-410 sample was oxidized to form metal oxide after heat treatment. Figure 5 (c) shows the fine XPS spectrum of the Cu2p orbitals of the CPHT-410 sample. After deconvolution fitting and comparison with standard spectra, it was found that the surface Cu is... + Cu 2+ and zero-valent copper (Cu) 0 Cu ions exist in the form of CuCl2. After etching with CuCl2, the surface of 410 stainless steel powder contains chemically or physically adsorbed Cu ions. After heat treatment, the Cu ions are fixed on the surface of the CPHT-410 sample and may undergo redox reactions with Fe or C to form Cu. + and Cu 0 . Figure 5 (d) shows the fine XPS spectrum of the Fe2p orbitals of the CPHT-410 sample. After deconvolution fitting, it was found that the Fe on the surface of the CPHT-410 sample is mainly in the form of zero-valent iron (Fe2pF ... 0 The presence of Cu in this form is likely due to the surface Cu layer preventing Fe oxidation during heat treatment. XPS spectra reveal the chemical states of C, O, Cu, and Fe on the CPHT-410 sample surface, providing corroboration for the XRD results. Furthermore, Cu... + Cu 2+ Cu 0 and Fe 0 They can serve as active sites, and their synergistic effect helps to improve the activation efficiency of persulfate, thereby enhancing the degradation performance of the CPHT-410 / PMS system.

[0055] 4. Specific surface area and pore size analysis

[0056] Figure 6The N2 adsorption / desorption isotherms of the CPHT-410 sample are shown. Judging from the shape of the isotherm, the curve is basically a typical Type IV isotherm, and a significant hysteresis loop appears in the high relative pressure (P / P0) range, which fully demonstrates that the CPHT-410 sample has a rich pore structure. The separation of the adsorption and desorption branches is due to capillary aggregation. Combined with the 1-10 μm particles shown by SEM, it can be seen that the material is composed of micron-sized particles, and its pores originate from the surface pore structure and the stacked pores between particles. The pore size distribution map further confirms that the pore volume distribution of the CPHT-410 sample is scattered, with mesopores (2-50 nm) and mesopores (50-500 nm). In addition, the specific surface area was calculated by the multi-point BET method and the pore volume was calculated by the BJH method, and the results are shown in Table 2. Combined with the SEM results, after etching and heat treatment, the particle size of the 410 stainless steel powder is reduced and the surface is roughened, which increases its specific surface area and provides a large number of active sites for the activation reaction. When applied to activated persulfate (PMS / PDS), these mesopores serve as the primary reaction sites, significantly promoting the contact between persulfate and active metal centers such as Fe and Cu on the material surface, thereby efficiently generating sulfuric acid free radicals (SO4). •⁻ ).

[0057] Table 2 Comparison of BET specific surface area, pore size and pore volume of Initial-410, CP-410 and CPHT-410-T300 samples

[0058]

[0059] 5. Performance Evaluation of Stainless Steel Powder Regeneration Catalyst Material

[0060] (1) Comparative analysis of degradation performance

[0061] To investigate the performance of different types of stainless steel powder regeneration catalysts in activating persulfate and to analyze the influence of treatment processes on its catalytic oxidation performance, a degradation experiment was conducted using Rhodamine B as the target pollutant.

[0062] like Figure 7 As shown in (a), within 30 min, the degradation efficiency of RhB by the catalytic oxidation system composed of the three stainless steel raw materials (Initial-304, Initial-316, and Initial-410) and PMS was only about 25%. After purification, the catalytic oxidation performance did not show a significant improvement. Figure 7 As shown in (b), after etching, the three stainless steel materials exhibited differences in catalytic oxidation performance. Figure 7As shown in (c), the CP-410 sample after CuCl2 etching treatment can effectively activate PMS within 30 min, promoting the efficient degradation of RhB with a degradation rate of 99.5%, and its catalytic oxidation performance is significantly better than that of the CP-304 and CP-316 samples. Furthermore, the effect of FeCl3 on the 410 type stainless steel is also significant. Figure 7 (d) The FP-410 sample etched with FeCl3 and the catalytic oxidation system composed of PMS also achieved a degradation rate of 99.0% for RhB.

[0063] like Figure 7 As shown in (e), the catalytic oxidation systems of NP-304, NP-316, and NP-410 samples with PMS achieved degradation efficiencies of 85%, 79%, and 34% for RhB, respectively. (Comparison) Figure 7 (c) Figure 7 (d) and Figure 7 The results in (e) clearly show that CuCl2 and FeCl3 etching treatments have a significant impact on the catalytic oxidation performance of 410 stainless steel powder. NaOH can effectively improve the catalytic oxidation performance of 304 and 316 stainless steel powders, but has a negative effect on 410 stainless steel powder. The catalytic oxidation performance of CPHT-410-T300, FPHT-410 T300, and NPHT-410 T300 samples was compared and analyzed, and the results are as follows: Figure 7 As shown in (f), after heat treatment, the catalytic oxidation performance of CPHT-410 did not change significantly, while the catalytic oxidation performance of FPHT-410 decreased. The reason for this still needs further investigation.

[0064] Therefore, this invention conducts an in-depth study using CPHT-410 stainless steel powder. Firstly, the effect of heat treatment temperature on CPHT-410 samples was compared and analyzed, and the results are as follows: Figure 8 As shown, the catalytic oxidation performance of the CPHT-410 series samples initially increases and then decreases with increasing temperature. When the heat treatment temperature exceeds 400 °C, the Cu on the surface may be gradually oxidized, reducing the number of low-valence active species and leading to a decline in catalytic oxidation performance. The heat treatment temperatures of 300 °C and 400 °C have no significant effect on the CPHT-410 series samples. Therefore, to save energy consumption, the subsequent heat treatment temperature was determined to be 300 °C.

[0065] To confirm the positive effect of CPHT-410-T300 on PMS activation, the degradation efficiency of RhB was compared between PMS-only, CPHT-410-T300-only, and the CPHT-410-T300 / PMS catalytic oxidation system. The results are as follows: Figure 9As shown, when only PMS is present in the reaction system, the degradation rate of RhB is approximately 17%, because PMS can slowly and spontaneously decompose to produce a small amount of active oxide species. When only CPHT-410-T300 is present in the reaction system, the removal rate of RhB is less than 10%, indicating that CPHT-410-T300 has almost no adsorption effect. When CPHT-410-T300 and PMS form a complete catalytic oxidation system, RhB can be completely degraded almost within 30 minutes. The above experimental results confirm that CPHT-410-T300 lowers the energy barrier for the decomposition of PMS to produce active oxide species through a chemical reaction, rather than simple physical or chemical adsorption.

[0066] Furthermore, this invention investigated the adaptability of the CPHT-410-T300 / PMS system to persistent organic pollutants such as cationic dyes, anionic dyes, and neutral antibiotics. Figure 10 As shown, the CPHT-410-T300 / PMS system achieved a degradation rate of over 99% for methyl orange (MO) and RhB within 30 min, and a degradation rate of 83% for tetracycline hydrochloride (TCH), while the degradation rates for 1,2-benzisothiazolin-3-one (BIT) and ofloxacin were only 42% and 17%, respectively.

[0067] (2) Evaluation of magnetic properties

[0068] Figure 11 The VSM analysis results for Initial-304, Initial-316, Initial-410, CPHT-304-T300, CPHT-316-T300, and CPHT-410-T300 are presented. These confirm that they are soft magnetic materials, easily magnetized and demagnetized. All the above samples exhibit typical soft magnetic characteristics; the saturation magnetization and coercivity indices indicate that they are easily magnetized and demagnetized, and solid-liquid separation can be achieved under an external magnetic field, improving the ease of recovery of the catalytic material. Among them, the Initial-410 sample has a saturation magnetization as high as approximately 146.62 emu / g, indicating that the material can achieve high magnetization under a strong magnetic field; the remanent magnetization is low, approximately 1.4258 emu / g, reflecting a rapid decrease in magnetization after demagnetization; and the coercivity is only about 13.341 Oe. However, after CuCl2 etching and heat treatment at 300℃, the magnetism of CPHT-410-T300 underwent a significant change: the saturation magnetization dropped sharply to 15.68 emu / g, while the coercivity increased to 37 Oe. This indicates that the magnetic properties of the material have changed from typical soft magnetism to semi-hard magnetism, which may be due to changes in phase composition caused by the processing or etching of the surface ferromagnetic phase.

[0069] In summary, this invention treats stainless steel solid waste (especially stainless steel dust rich in iron, chromium, nickel, etc.) as a valuable "secondary resource." Through a green and efficient resource-based regeneration process, including purification, etching, and heat treatment, a heterogeneous catalytic material with persulfate-activating properties is prepared. The preparation method is simple, low-cost, and yields a catalytic material with good catalytic performance and high degradation rate. This material can be applied to the harmless treatment of recalcitrant organic pollutant wastewater (such as dye wastewater and cutting fluid wastewater), effectively activating persulfate to generate strong oxidizing free radicals (SO4). •- This research utilizes persulfate (PS) to achieve efficient degradation of organic matter, including hydroxyl groups (OH, etc.). It not only provides a high-value utilization pathway for stainless steel solid waste but also develops an innovative method for treating high-concentration organic wastewater at a high efficiency and low cost, essentially achieving the dual goals of "treating waste with waste" and "resource recycling." It opens up new avenues for the high-value resource utilization of solid waste such as stainless steel dust, significantly improving the level of the circular economy. It provides a low-cost, high-efficiency persulfate activation technology based on solid waste-derived catalysts, which is expected to overcome the limitations of existing advanced oxidation technologies in terms of catalytic material cost and application scale, providing a practical solution for the deep degradation of persistent organic pollutants. This research and application highly integrates knowledge from multiple fields such as solid waste resource utilization, environmental catalysis, synthesis and application of inorganic materials (non-metallic catalytic materials), and water treatment engineering. It provides an important research foundation and practical experience for promoting the innovative application of inorganic non-metallic catalytic materials in environmental remediation and promoting the comprehensive cross-disciplinary integration of multiple disciplines (materials, environment, chemical engineering, metallurgy). It will have a profound impact on improving the environmental and economic benefits of related industries and achieving green manufacturing.

[0070] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a catalytic material for the resource-based regeneration of stainless steel dust, characterized in that, Includes the following steps: S1. Stainless steel powder is placed in H2SO4 solution for purification. After purification, the solid precipitate is separated by centrifugation, and the impurities in the precipitate are washed with deionized water and anhydrous ethanol. The sample is then dried to obtain the purified sample. S2. Take the purified sample and add it to the etching solution. Stir the sample at a preset temperature using a hydrothermal method to perform etching. After etching is completed, wash the sample with deionized water and anhydrous ethanol, and dry it to obtain the etched sample. The etching solution can be any one of FeCl3 solution, NaOH solution and CuCl2 solution. S3. The etched sample is placed in a muffle furnace for heat treatment to obtain stainless steel regenerated catalyst material.

2. The preparation method of a stainless steel dust resource recycling catalytic material according to claim 1, characterized in that: In S1, the purification steps are as follows: heat the 0.5~1.5 mol / L H2SO4 solution to 40~50℃ in a water bath, and then place the stainless steel powder in the H2SO4 solution and let it stand for 12~24 h.

3. The preparation method of a stainless steel dust resource recycling catalytic material according to claim 1, characterized in that: In S1, stainless steel includes 304 stainless steel, 316 stainless steel and 410 stainless steel.

4. The preparation method of a stainless steel dust resource recycling catalytic material according to claim 1, characterized in that: In S2, the concentration of the etching solution is 0.5~1.5 mol / L; the preset temperature is 50~70℃; and the etching time is 2~3h.

5. The preparation method of a stainless steel dust resource recycling catalytic material according to claim 1, characterized in that: In S3, the heat treatment temperature is 300~600℃.

6. The stainless steel dust resource recycling catalytic material prepared by the method according to any one of claims 1 to 5.

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