A steel slag-based bifunctional material, a preparation method and application thereof

Abstract

This invention discloses a dual-functional material based on steel slag, its preparation method, and its application, belonging to the field of solid waste resource utilization and environmental pollution control technology. The method uses steel slag, a solid waste from the iron and steel industry, as raw material, and prepares an iron-rich catalyst and a calcium-rich adsorbent through selective leaching. The iron-rich catalyst efficiently activates PMS in a photocatalytic persulfate (PMS) system to degrade tetracycline antibiotics in water; simultaneously, the calcium-rich adsorbent can capture CO2 generated during antibiotic degradation in situ, thus achieving multiple objectives of solid waste resource utilization and pollution and carbon reduction. This invention utilizes widely available and inexpensive raw materials and employs a simple process, effectively improving the high-value-added resource utilization level of steel slag and overcoming the carbon emission problems associated with traditional advanced oxidation technologies, providing a new approach for synergistic technologies of wastewater treatment and carbon reduction.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and environmental pollution control technology, specifically to a dual-functional material based on steel slag, its preparation method, and its application. Background Technology

[0002] Antibiotic pollutants in water bodies, especially tetracyclines, are persistent and bioaccumulative, posing a serious threat to ecosystems and human health. Currently, advanced oxidation technologies (AOPs) are widely used to treat these recalcitrant pollutants, with persulfate (PMS)-based systems attracting significant attention due to their strong oxidizing power and wide pH applicability. However, this technology has significant drawbacks: the mineralization of organic pollutants releases large amounts of carbon dioxide, exacerbating carbon emissions. Existing research primarily focuses on improving pollutant degradation efficiency, often neglecting the control of CO2 emissions accompanying mineralization, leading to new environmental problems arising from the treatment process.

[0003] The steel industry generates a large amount of steel slag annually. This industrial solid waste has a complex composition, rich in valuable elements such as iron, calcium, and silicon, and possesses the potential for high-value utilization. However, most steel slag is disposed of through landfill or used as low-value building materials, resulting in serious waste. Moreover, during long-term storage or use, its inherent high alkalinity and potential presence of trace heavy metals pose an environmental risk of leaching and contaminating soil and groundwater. Due to the complexity of steel slag composition, most technical approaches can only target the extraction or functional development of one type of component to prepare materials with specific uses, leading to low comprehensive utilization efficiency and becoming a major technical bottleneck for achieving large-scale, high-economic-efficiency resource recovery.

[0004] Therefore, developing a technology that can achieve high-value conversion of steel slag, efficient degradation of antibiotics, and simultaneous CO2 capture is of great significance for solving solid waste pollution, water pollution, and carbon emission problems. Summary of the Invention

[0005] To address the issues of carbon emission pollution from advanced oxidation technologies and the low value and limited functionality of steel slag resource utilization pathways, this invention aims to provide a method for preparing bifunctional materials based on steel slag, specifically including the following steps: (1) Steel slag pretreatment: The raw steel slag is ground, dried and sieved to obtain steel slag powder.

[0006] (2) Acid leaching separation: Steel slag powder is mixed with acetic acid aqueous solution and leaching reaction is carried out under heating and stirring conditions. After the reaction is completed, solid-liquid separation is carried out to obtain solid residue and leachate.

[0007] (3) Preparation of SS-Fe catalyst: The solid residue obtained in step (2) is washed and dried to obtain SS-Fe catalyst.

[0008] (4) Preparation of SS-Ca adsorbent: The leachate obtained in step (2) is dried to obtain a solid precursor; the solid precursor is calcined to obtain SS-Ca adsorbent.

[0009] Preferably, the drying conditions in step (1) of the present invention are: drying at 80-110℃ for 20-30 hours; and the sieving conditions are: passing through a 100-200 mesh sieve.

[0010] Preferably, the concentration of the acetic acid aqueous solution in step (2) of the present invention is 1.0-3.0 mol / L.

[0011] Preferably, in step (2) of the present invention, the solid-liquid ratio of steel slag powder to acetic acid aqueous solution is 0.05-0.15g:1mL.

[0012] Preferably, the leaching reaction temperature in step (2) of the present invention is 25-75℃, and the reaction time is 1-3h.

[0013] Preferably, the washing conditions in step (3) of the present invention are: washing until the pH of the washing solution is neutral; the drying conditions are: drying at 80-110℃ for 20-30 hours.

[0014] Preferably, the drying temperature in step (4) of the present invention is 80-110℃ and the drying time is 20-30h.

[0015] Preferably, in step (4) of the present invention, the calcination temperature is 800-1000℃, the calcination time is 1-3h, and the heating rate is 3-10℃ / min.

[0016] Another object of the present invention is to provide an SS-Fe catalyst and an SS-Ca adsorbent prepared by the method described in the present invention.

[0017] Another object of the present invention is to provide an application of SS-Fe catalyst and SS-Ca adsorbent in the removal of tetracycline from water.

[0018] This invention provides a bifunctional material based on steel slag, its preparation method, and its application, which has the following beneficial effects: (1) This invention successfully realizes the high-value utilization of steel slag, a solid waste from the iron and steel industry. It separates the same steel slag source and prepares two high-value environmental materials: SS-Fe catalyst and SS-Ca adsorbent. It realizes the green circular concept of "treating waste with waste and turning waste into treasure". The process is mild and clean, and only acetic acid is used as the leaching agent, with no secondary pollution.

[0019] (2) The materials prepared by the present invention exhibit excellent performance: the SS-Fe catalyst has a degradation efficiency of up to 99.4% for tetracycline, which is better than that of MnO2; the SS-Ca adsorbent has an adsorption capacity of up to 3464.46 ppm for CO2 and can be stably solidified into CaCO3 through mineral carbonization.

[0020] (3) This invention creatively constructs a degradation-adsorption synergistic system, which can achieve a three-in-one synergistic effect of high-value utilization of steel slag, efficient degradation of antibiotics, and simultaneous in-situ capture of CO2 during the mineralization process. SS-Fe catalyst and SS-Ca adsorbent are prepared using raw steel slag. SS-Fe efficiently activates persulfate to degrade organic pollutants under photo-assisted conditions, while SS-Ca is used to capture and fix CO2 generated during the mineralization process in situ, cleverly solving the problem of secondary carbon emissions associated with advanced oxidation technologies. This system maintains good adaptability in various actual water bodies (such as tap water, lake water, and wastewater treatment plant effluent), demonstrating broad engineering application prospects and providing a practical and feasible technical path for industrial solid waste resource utilization and carbon-neutral wastewater treatment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the preparation process of the SS-Fe catalyst and SS-Ca adsorbent of the present invention.

[0022] Figure 2 The diagram shows the degradation and CO2 adsorption capacity of TC under different reaction systems of this invention; (a) TC degradation performance diagram, (b) degradation kinetic constant, (c) degradation efficiency of TC in SS-Fe and SS-Fe / SS-Ca systems, and (d) CO2 production amount corresponding to SS-Fe and SS-Fe / SS-Ca systems.

[0023] Figure 3 The images show the XRD patterns of the SS used in Example 1 of this invention and the prepared SS-Fe and SS-Ca.

[0024] Figure 4 The images show the TG-DTG curves of the SS-Ca adsorbent prepared in Example 1 of this invention before and after use. (a) is the TG curve, and (b) is the DTG curve.

[0025] Figure 5 This is a schematic diagram of the operation of the SS-Fe / SS-Ca synergistic system of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1 The preparation of a bifunctional material includes the following steps: (1) Steel slag pretreatment: Steel slag from a steel plant in Hubei Province was ground for 30 minutes using a planetary ball mill (ball-to-material ratio of 10:1), and then dried in a 95℃ forced-air drying oven for 20 hours. After cooling, it was sieved to obtain 100-200 mesh steel slag powder, which was sealed for later use. After sieving, the steel slag particle size was concentrated in 75-150μm to ensure the uniformity of the subsequent leaching reaction.

[0028] (2) Acid leaching separation: Steel slag powder and acetic acid aqueous solution (the concentration of acetic acid aqueous solution is 2.0 mol / L) are mixed at a solid-liquid ratio of 0.15:1 and leached at 75℃ for 2 hours. After the reaction is completed, the solid and liquid are separated by vacuum filtration (filter membrane pore size 0.45 μm) to obtain solid residue and leachate.

[0029] (3) Preparation of SS-Fe catalyst: The solid residue obtained in step (2) was repeatedly washed with ultrapure water until the pH of the washing solution was 7. The washed solid was then dried in a 95℃ drying oven for 20 h. After grinding, the SS-Fe catalyst was obtained and sealed for storage. Based on the nitrogen adsorption-desorption isotherm, the specific surface area of ​​SS-Fe was calculated to be 8.540 m² using the BET (Brunauer-Emmett-Teller) equation. 2 / g, the characteristic peaks of FeO in the XRD pattern were significantly enhanced ( Figure 3 ).

[0030] (4) Preparation of SS-Ca adsorbent: The leachate obtained in step (2) was dried in a 95℃ drying oven for 20 h to obtain a white solid precursor; the white solid precursor was transferred to a quartz boat, placed in a tube furnace, and calcined at 900℃ for 2 h in an air atmosphere at a heating rate of 5℃ / min; after natural cooling to room temperature, it was ground to obtain SS-Ca adsorbent and sealed for storage. Based on the nitrogen adsorption-desorption isotherm, the specific surface area of ​​SS-Ca was calculated to be 11.16 m² using the BET equation. 2 / g, strong characteristic peaks of Ca(OH)2 appeared in the XRD pattern ( Figure 3 ).

[0031] Example 2 The preparation of a bifunctional material includes the following steps: (1) Steel slag pretreatment: Steel slag from a steel plant in Hubei Province was ground for 30 minutes using a planetary ball mill (ball-to-material ratio of 10:1), and then dried in a 110℃ forced-air drying oven for 25 hours. After cooling, it was passed through a 100-200 mesh sieve to obtain steel slag powder, which was sealed for later use. After sieving, the steel slag particle size was concentrated in 75-150μm to ensure the uniformity of the subsequent leaching reaction.

[0032] (2) Acid leaching separation: Steel slag powder and acetic acid aqueous solution (the concentration of acetic acid aqueous solution is 1.0 mol / L) are mixed at a solid-liquid ratio of 0.1:1 and leached at 25°C for 3 hours. After the reaction is completed, the solid and liquid are separated by vacuum filtration (filter membrane pore size 0.45 μm) to obtain solid residue and leachate.

[0033] (3) Preparation of SS-Fe catalyst: The solid residue obtained in step (2) was repeatedly washed with ultrapure water until the pH of the washing solution was 7. The washed solid was placed in a drying oven at 110℃ and dried for 25 hours. After grinding, the SS-Fe catalyst was obtained and sealed for storage.

[0034] (4) Preparation of SS-Ca adsorbent: The leachate obtained in step (2) was dried in a drying oven at 110℃ for 25h to obtain a white solid precursor; the white solid precursor was transferred to a quartz boat, placed in a tube furnace, and heated to 800℃ at a heating rate of 10℃ / min in an air atmosphere, and calcined for 3h; after naturally cooling to room temperature, it was ground to obtain SS-Ca adsorbent and sealed for storage.

[0035] The performance of the SS-Fe catalyst and SS-Ca adsorbent prepared in this embodiment is similar to that in Example 1.

[0036] Example 3 The preparation of a bifunctional material includes the following steps: (1) Steel slag pretreatment: Steel slag from a steel plant in Hubei Province was ground for 30 minutes using a planetary ball mill (ball-to-material ratio of 10:1), and then dried in an 80℃ forced-air drying oven for 30 hours. After cooling, it was passed through a 100-200 mesh sieve to obtain steel slag powder, which was sealed for later use. After sieving, the steel slag particle size was concentrated in 75-150μm to ensure the uniformity of the subsequent leaching reaction.

[0037] (2) Acid leaching separation: Steel slag powder and acetic acid aqueous solution (the concentration of acetic acid aqueous solution is 3.0 mol / L) are mixed at a solid-liquid ratio of 0.05:1 and leached at 50℃ for 1 h. After the reaction is completed, the solid and liquid are separated by vacuum filtration (filter membrane pore size 0.45 μm) to obtain solid residue and leachate.

[0038] (3) Preparation of SS-Fe catalyst: The solid residue obtained in step (2) was repeatedly washed with ultrapure water until the pH of the washing solution was 7. The washed solid was placed in an 80℃ drying oven and dried for 30 hours. After grinding, the SS-Fe catalyst was obtained and sealed for storage.

[0039] (4) Preparation of SS-Ca adsorbent: The leachate obtained in step (2) was dried in an 80℃ drying oven for 30h to obtain a white solid precursor; the white solid precursor was transferred to a quartz boat, placed in a tube furnace, and heated to 1000℃ at a heating rate of 3℃ / min in an air atmosphere, and calcined for 1h; after naturally cooling to room temperature, it was ground to obtain SS-Ca adsorbent and sealed for storage.

[0040] The performance of the SS-Fe catalyst and SS-Ca adsorbent prepared in this embodiment is similar to that in Example 1.

[0041] 1. The degradation performance of SS-Fe catalyst on tetracycline was tested, including the following steps: (1) Prepare a tetracycline solution with a concentration of 30 mg / L (the solvent is deionized water).

[0042] (2) Add the SS-Fe catalyst prepared in Example 1 to the tetracycline solution (the amount of SS-Fe catalyst added is 0.15 g / L), turn on the stirring (200 rpm), and stir in the dark for 30 min to reach the adsorption-desorption equilibrium. This process can eliminate the interference of adsorption on the subsequent degradation rate calculation.

[0043] (3) Add PMS (the amount of PMS added is 0.45 g / L), turn on a 300W xenon lamp (wavelength 200-800 nm, lamp distance 10 cm from the liquid surface) to irradiate and start the degradation reaction.

[0044] (4) Take 3 mL samples at 0, 1, 3, 5, 10, 20, 30, 60, 120, 150 and 180 min respectively, add excess 0.1 mol / L Na2S2O3 solution (volume ratio 1:1) to quench the reaction, and filter through a 0.22 μm organic filter membrane.

[0045] (5) The concentration of tetracycline in the filtrate was determined by high performance liquid chromatography (HPLC, Agilent 1260 Infinity II). The chromatographic conditions were as follows: C18 column (4.6 mm × 150 mm, 5 μm), column temperature 25 °C, mobile phase was methanol-0.1% phosphoric acid aqueous solution (volume ratio of methanol and phosphoric acid aqueous solution was 3:7), flow rate 1.0 mL / min, and detection wavelength 355 nm.

[0046] (6) Calculate the tetracycline degradation rate.

[0047] The tetracycline degradation rate results are as follows: Figure 2As shown, Figure 2 As shown in (a) and (b), the SS-Fe catalyst achieved a degradation rate of 99.4% within 180 min, with an apparent rate constant of 0.041 min. -1 In the comparative experiment, the degradation rate using MnO2 (with the same dosage) was 88%, and the apparent rate constant was 0.017 min. -1 This indicates that the SS-Fe catalyst has good catalytic activity.

[0048] 2. The SS-Fe catalyst and SS-Ca adsorbent prepared in Example 1 were placed in the same reactor to test their synergistic performance in removing pollutants and capturing CO2, including the following steps: (1) In the degradation system for testing the degradation performance of SS-Fe catalyst on tetracycline, 30 mg of SS-Ca adsorbent was added, and other conditions remained unchanged.

[0049] (2) The CO2 concentration during the reaction was detected by gas chromatography (GC, Shimadzu GC-2014). The chromatographic conditions were: TDX-01 column, column temperature 80℃, detector temperature 200℃, injection port temperature 150℃, and carrier gas N2 (flow rate 30mL / min). A standard curve was plotted by external standard method to calculate the actual CO2 concentration in the system.

[0050] (3) Record the changes in CO2 concentration, such as Figure 2 As shown in (c) and (d), near-complete pollutant removal was achieved within 180 min, indicating that the introduction of SS-Ca did not weaken the catalytic degradation efficiency. The SS-Fe catalytic system produced a maximum CO2 concentration of 5286.46 ppm, while under the same conditions, the SS-Fe / SS-Ca system produced only 1822.33 ppm; this demonstrates that SS-Ca can effectively capture CO2 generated during pollutant mineralization. This invention constructs an integrated degradation-adsorption pathway.

[0051] (4) XRD was performed on the SS-Ca adsorbent after the reaction. Figure 3 ) and TG-DTG ( Figure 4 Characterization: The XRD pattern showed a characteristic peak of CaCO3, while the intensity of the Ca(OH)2 peak decreased significantly; the TG curve showed a CaCO3 decomposition weight loss peak (weight loss rate 11.67%) at 600-750℃, which was significantly different from the newly prepared SS-Ca adsorbent (which only showed a Ca(OH)2 decomposition weight loss peak at 350-450℃, with a weight loss rate of 5.16%), confirming that the SS-Ca adsorbent can achieve CO2 capture.

[0052] Figure 1This is a process flow diagram of the present invention. As can be seen from the diagram, after the raw steel slag is leached with acetic acid and subjected to simple solid-liquid separation, it is successfully prepared into two products: a solid residue for catalytic degradation (SS-Fe catalyst) and a calcination product for capturing CO2 (SS-Ca adsorbent). This clearly demonstrates the core idea of ​​the present invention: waste diversion and high-value utilization.

[0053] Figure 5 This is a schematic diagram of the working principle of the synergistic system of the present invention. As can be seen from the figure, the SS-Fe catalyst is responsible for activating PMS to degrade pollutants and release CO2, while the SS-Ca adsorbent captures and fixes these CO2, which vividly summarizes the complete process of the synergistic work of the entire system.

[0054] In summary, this invention establishes a waste resource utilization strategy that transforms steel slag waste into a bifunctional catalytic-adsorption material, providing a sustainable path for the high-value utilization of solid waste and the synergistic realization of wastewater treatment and carbon emission reduction.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a bifunctional material based on steel slag, characterized in that, Specifically, the following steps are included: (1) Steel slag pretreatment: The raw steel slag is ground, dried and sieved to obtain steel slag powder; (2) Acid leaching separation: Steel slag powder is mixed with acetic acid aqueous solution and leaching reaction is carried out under heating and stirring conditions. After the reaction is completed, solid-liquid separation is carried out to obtain solid residue and leachate; (3) Preparation of SS-Fe catalyst: The solid residue obtained in step (2) is washed and dried to obtain SS-Fe catalyst; (4) Preparation of SS-Ca adsorbent: The leachate obtained in step (2) is dried to obtain a solid precursor; the solid precursor is calcined to obtain SS-Ca adsorbent.

2. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The drying conditions in step (1) are: drying at 80-110℃ for 20-30 hours; the sieving conditions are: passing through a 100-200 mesh sieve.

3. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The concentration of the acetic acid aqueous solution in step (2) is 1.0-3.0 mol / L.

4. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The solid-liquid ratio of the steel slag powder to the acetic acid aqueous solution in step (2) is 0.05-0.15 g: 1 mL.

5. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The leaching reaction in step (2) is carried out at a temperature of 25-75℃ for 1-3 hours.

6. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The washing conditions in step (3) are: washing until the pH of the washing solution is neutral; the drying conditions are: drying at 80-110℃ for 20-30 hours.

7. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The drying temperature in step (4) is 80-110℃ and the drying time is 20-30h.

8. The method for preparing bifunctional materials based on steel slag according to claim 1, characterized in that, The calcination temperature in step (4) is 800-1000℃, the calcination time is 1-3h, and the heating rate is 3-10℃ / min.

9. The SS-Fe catalyst and SS-Ca adsorbent prepared by the method according to any one of claims 1 to 8.

10. The use of the SS-Fe catalyst and SS-Ca adsorbent prepared by the method according to any one of claims 1 to 8 in the removal of tetracycline from water.

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