Preparation method and application of porous geopolymer microsphere photothermal catalyst for copper smelting slag

Abstract

This invention discloses a method for preparing a porous geopolymer microsphere photothermal catalyst from copper smelting slag. The method uses copper slag as raw material, employs suspension polymerization to prepare ferrous oxalate microspheres, followed by reduction calcination to prepare carbon-coated Fe3O4 geopolymer microspheres. Then, MoS2 is generated on the surface of the carbon-coated Fe3O4 microspheres via a hydrothermal method. This material solves the problems of insufficient catalytic active sites, poor stability, and low conductivity of Fe3O4. When applied to the degradation of antibiotics, this photothermal catalyst not only exhibits excellent photothermal Fenton catalytic performance for antibiotics, but its porous microsphere structure also allows for sufficient adsorption of light through multiple light reflections between the micropores, and it also demonstrates excellent magnetic recovery capabilities. The degradation rate of chlortetracycline is 83.3%–94%, effectively reducing the environmental harm caused by organic pollutants.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying a porous geopolymer microsphere photothermal catalyst for copper smelting slag, belonging to the fields of resource utilization of solid waste and photothermal Fenton catalysis technology. Background Technology

[0002] In recent years, various solid wastes emitted during factory production have caused serious harm to the global ecological environment. China is the world's largest producer of refined copper, with a production of 10.49 million tons in 2021, accounting for 42.54% of global production. Approximately 2-3 tons of copper smelting slag (hereinafter referred to as copper slag) are emitted for every ton of refined copper produced. Therefore, my country emits approximately 20-30 million tons of copper slag annually. Copper slag contains large amounts of iron and silicon, with its main mineral phases being magnetite (Fe3O4) and fir olivine (Fe2SiO4). It is mainly composed of oxides such as Fe2O3, SiO2, Al2O3, and CaO, with Fe2O3 content reaching as high as 55.72% and SiO2 content reaching 32.24%. Comprehensive recycling of copper slag is difficult and costly; small particulate dust pollutes the atmosphere and harms health; and its stockpiling not only occupies valuable land resources but also causes secondary pollution, impacting the ecological environment. If copper slag can be recycled and utilized, it can not only solve the environmental problems it causes, but also generate huge economic benefits.

[0003] Since the discovery of penicillin in 1929, the global use of antibiotics has steadily increased. They are widely used in various fields such as daily healthcare, disease treatment, aquaculture, and animal husbandry. However, only 20%-40% of tetracyclic antibiotics are absorbed by humans and livestock, meaning that 60%-80% are excreted and released into soil and water sources. Tetracyclic antibiotics include tetracycline hydrochloride (TC), chlortetracycline (CTC), and oxytetracycline (OTC). Large quantities of antibiotics have been found in the biosphere, soil, and water. Antibiotics have the ability to bind with heavy metals to form sedimentary organic matter and have a strong affinity for sediments, making them difficult to degrade effectively. The accumulation of antibiotics in the environment can have direct destructive effects on humans and microorganisms, causing varying degrees of damage to human organs and leading to decreased immunity. Their migration into water exacerbates environmental pressures, thereby disrupting the ecological balance. Therefore, it is urgent to eliminate antibiotics from the aquatic environment.

[0004] Fenton technology, as a type of advanced oxidation process (AOP), is widely used in wastewater treatment to degrade recalcitrant organic pollutants due to its wide applicability, simplicity, and high efficiency. In particular, heterogeneous Fenton processes have been established to overcome the limitations of traditional homogeneous Fenton systems, such as pH range limitations, iron sludge formation, and insufficient H2O2 utilization. Because of the introduction of clean and sustainable solar energy, electrons and holes can be generated simultaneously, allowing photocatalysts to simultaneously achieve oxidation and reduction in a single reaction system. Photo-Fenton processes, which integrate photocatalysis and the Fenton process into a single system, are particularly promising. 2+ / Fe 3+ The cycle generates free radicals ·OH and ·O2. - and h + They can all degrade organic pollutants, but they still have problems such as insufficient catalytic activity and low electron transport efficiency. Summary of the Invention

[0005] To address the secondary pollution problems caused by copper smelting slag and the environmental pollution problems caused by tetracycline antibiotics, this invention provides a method for preparing a porous geopolymer microsphere photothermal catalyst from copper smelting slag. This method uses copper slag as raw material, employs suspension polymerization to prepare ferrous oxalate microspheres, followed by reduction calcination to prepare carbon-coated Fe3O4 geopolymer microspheres. Then, MoS2 is generated on the surface of the carbon-coated Fe3O4 microspheres via a hydrothermal method. This material solves the problems of insufficient catalytic active sites, poor stability, and low conductivity of Fe3O4. When this photothermal catalyst is applied to the degradation of antibiotics, it not only exhibits excellent photothermal Fenton catalytic performance for antibiotics, but the porous microsphere structure also allows for sufficient adsorption of light through multiple light reflections between the micropores, and it also demonstrates excellent magnetic recovery capabilities. Compared to reaction slag, the microspheres are easier to collect and recover, and the carbon coating further improves electron transport efficiency, significantly expands photoadsorption capacity, and increases photothermal conversion capacity.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] (1) Add copper slag powder to oxalic acid solution and mix well to obtain slurry;

[0008] The copper slag powder is obtained by grinding dry copper slag through a 200-mesh sieve, with a sieve residue of less than 5%; the main components of the copper slag are: Fe2O3 55-60wt%, SiO2 30-35wt%, MgO 1-2wt%, Al2O3 5-6wt%, CaO 2-3wt%, ZnO 2-3wt%.

[0009] (2) Under stirring conditions, the slurry was dropped into dimethyl silicone oil at 50-60℃ and formed into balls under the action of stirring mechanical force. Then the mixture was aged at 55-65℃ for 12h, solid-liquid separation was performed, ferrous oxalate microspheres were collected and placed in a tube furnace for calcination to obtain carbon-coated Fe3O4 microspheres.

[0010] The mass ratio of oxalic acid to copper slag powder is 1-2:1, and the mass ratio of oxalic acid to deionized water is 1-3:1; the stirring speed is 700-900 rpm; and the calcination temperature is 500-600℃.

[0011] (3) Place ammonium molybdate and carbon-coated Fe3O4 microspheres in deionized water and sonicate for 25-35 min. Then add thiourea and continue sonicating for 25-35 min. Then hydrothermally react at 150-200℃ for 14-18 h. Separate the solid and liquid. Wash the solid with deionized water until neutral and dry to obtain the copper smelting slag porous geopolymer microsphere photothermal catalyst.

[0012] The mass ratio of ammonium molybdate to carbon-coated Fe3O4 microspheres is 1:0.4-2, and the mass ratio of ammonium molybdate to thiourea is 1:0.6-2.5.

[0013] Another objective of this invention is to apply the porous geopolymer microsphere photothermal catalyst for copper smelting slag prepared by the above method to the removal of chlortetracycline hydrochloride from wastewater.

[0014] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0015] 1. The preparation method of this composite material is acid-activated suspension polymerization-hydrothermal synthesis, which is simple to operate, has low production cost, and uses readily available raw materials. Fe ions are derived from copper slag. Oxalic acid is used to leach Fe ions from the copper slag, and suspension polymerization is used to form ferrous oxalate microspheres. Calcination generates carbon-coated Fe3O4 microspheres. Ultrasonication is used to pre-anchor Mo ions on the surface of the microspheres. Then, thiourea-structured defect MoS2 is added, and hydrothermal synthesis is used to grow MoS2 in situ and anchor it on the copper slag-based Fe3O4 microspheres. The constructed heterojunction can accelerate the growth of Fe ions. 3+ / Fe 2+ The conversion generates more ·OH, which can effectively improve photothermal catalytic performance. In this process, carbon coating can also improve electron transport efficiency, increase photothermal conversion capacity, and promote the degradation of organic matter.

[0016] 2. Due to its porous spatial structure, the Fe3O4 microspheres coated with C can fully adsorb light through multiple light reflections between the micropores, which makes it more likely to activate H2O2 through non-free radical pathways and has higher reactivity. In addition, the structure and magnetism of the microspheres are also conducive to recycling.

[0017] 3. The catalyst prepared by the method of this invention can not only accelerate electron transfer, but also accelerate photogenerated electrons (e... - The reaction between iron ions and redox reactions can also enhance electron transfer capabilities, resulting in higher electron utilization.

[0018] 4. The carbon-coated Fe3O4 microspheres supported on MoS2 photothermal catalyst derived from copper slag-based polymers, which have high redox performance and reactivity, are used as photo-Fenton catalysts for the removal of chlortetracycline. The degradation rate of chlortetracycline is 83.3% to 94%, which can effectively reduce the harm of organic pollutants to the environment. Attached Figure Description

[0019] Figure 1 The XRD patterns are of carbon-coated Fe3O4 microspheres (C@Fe3O4) derived from copper slag-based polymers, pure MoS2, and MoS2 photothermal catalyst supported on carbon-coated Fe3O4 microspheres derived from copper slag-based polymers (MoS2 / C@Fe3O4) in Example 1.

[0020] Figure 2 SEM image of the porous geopolymer microsphere photothermal catalyst of copper smelting slag in Example 1;

[0021] Figure 3 The UV-Vis diffuse reflectance (left) and bandgap (right) plots of carbon-coated Fe3O4 microspheres (C@Fe3O4) derived from copper slag-based polymers, pure MoS2, and MoS2 photothermal catalyst supported on carbon-coated Fe3O4 microspheres (MoS2 / C@Fe3O4) derived from copper slag-based polymers are shown in Example 1.

[0022] Figure 4 The photoluminescence spectra of carbon-coated Fe3O4 microspheres (C@Fe3O4) derived from copper slag-based polymers, pure MoS2, and MoS2 photothermal catalyst (MoS2 / C@Fe3O4) supported on carbon-coated Fe3O4 microspheres derived from copper slag-based polymers in Example 1 are shown.

[0023] Figure 5 The image shows the removal effect of carbon-coated Fe3O4 microspheres (C@Fe3O4) derived from copper slag substrate polymers, pure MoS2, and MoS2 photothermal catalyst supported on copper slag substrate polymer-coated Fe3O4 microspheres (MoS2 / C@Fe3O4) on chlortetracycline hydrochloride in Example 1. Detailed Implementation

[0024] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention. The main components of the copper slag used in the embodiments are: Fe2O3 55.72wt%, SiO2 32.24wt%, MgO 1.26wt%, Al2O3 5.17wt%, CaO 2.20wt%, ZnO 2.66wt%.

[0025] Example 1:

[0026] Weigh 3.5g of copper slag, 5g of oxalic acid and 2.5g of deionized water. After adding oxalic acid to deionized water and stirring evenly, add copper slag and react with it until it reaches a slurry state. Quickly use a syringe to draw up the mixture and inject it into dimethyl silicone oil at 50℃. Stir with a disperser (stirring speed of 800rpm) for 4min to form spheres. Then place it in a 60℃ oven to age for 12h. After solid-liquid separation, ferrous oxalate microspheres are obtained and placed in a tube furnace to calcine at 500℃ for 5h to obtain carbon-coated Fe3O4 microspheres.

[0027] 0.1845g of ammonium molybdate and 0.25g of carbon-coated Fe3O4 microspheres were placed in a polyethylene tetroxide liner containing 70mL of deionized water and sonicated for 30min. Then, 0.402g of thiourea was added and sonicated for another 30min. Finally, the mixture was hydrothermally reacted at 180℃ for 16h. The mixture was filtered, and the filter residue was washed with deionized water until neutral. The residue was then dried in an oven at 60℃ for 12h to obtain a porous geopolymer microsphere photothermal catalyst for copper smelting slag.

[0028] The crystal structure of the photothermal catalyst prepared in this embodiment is shown below. Figure 1 As can be seen from the figure, the copper slag (C@Fe3O4) after reduction roasting is mainly composed of Fe3O4. After the in-situ growth of amorphous MoS2 by hydrothermal synthesis, the crystal structure of the composite material (MoS2 / C@Fe3O4) changed, and the corresponding peak shape of MoS2 appeared, indicating that crystalline MoS2 was successfully grown on C@Fe3O4 microspheres. In addition, the composite material also showed a SiO2 crystal structure.

[0029] The macroscopic morphology of porous geopolymer microsphere photothermal catalysts in copper smelting slag is as follows: Figure 2 As shown in the figure, after MoS2 is grown in situ on carbon-coated Fe3O4 microspheres derived from copper slag polymers, MoS2 grows in the form of nanorods on the surface of the microspheres, and the inside of the microspheres has a network structure.

[0030] The optical properties of the prepared photothermal catalyst, carbon-coated Fe3O4 microspheres (C@Fe3O4), and pure MoS2 were studied using ultraviolet-visible diffuse reflectance analysis. The results are as follows: Figure 3As shown in the figure, all three catalysts exhibit light absorption capabilities across the entire spectral range, including the UV, Vis, and NIR regions. MoS2 shows relatively low light absorption in the near-infrared region, which may be attributed to its inherent band gap transition. Carbon-coated Fe3O4 microspheres exhibit relatively higher light absorption capabilities than MoS2, due to the strong light absorption capacity of C. In-situ growth of MoS2 significantly enhances the absorbance of MoS2 / C@Fe3O4, enabling it to fully utilize sunlight and greatly improve its light absorption performance.

[0031] Photoluminescence (PL) spectroscopy was used to characterize the separation efficiency of photogenerated electrons and holes in the composite material; the higher the separation efficiency, the weaker the PL emission peak intensity. The photoluminescence spectra of carbon-coated Fe3O4 microspheres, pure MoS2, and copper slag-derived carbon-coated Fe3O4 microspheres supported on MoS2 photothermal catalysts are shown below. Figure 4 As shown, from Figure 4 It can be seen that the C@Fe3O4 microspheres exhibit a strong emission peak in the 500-700 nm range, indicating that they generate electrons through photoemission. — and h + The recombination rate was the highest. When nanorod-shaped MoS2 was grown in situ on C@Fe3O4 microspheres, MoS2 / C@Fe3O4 showed the best photogenerated electron-hole separation efficiency. This may be due to the formation of a heterojunction between C@Fe3O4 and MoS2, which accelerates the transfer of charge carriers and greatly improves the photogenerated electron-hole separation efficiency.

[0032] The copper slag-based polymer-derived carbon-coated Fe3O4 microspheres supported on MoS2 photothermal catalyst, carbon-coated Fe3O4 microspheres, and pure MoS2 prepared in this embodiment were used in a photo-Fenton reaction to remove chlortetracycline. The catalyst dosage was 1 g / L, the H2O2 dosage was 0.2 mL, and the chlortetracycline hydrochloride solution was 40 mL. The initial pH was 4.1, and the concentration was 50 mg / L. The treatment was carried out for 30 min under natural light and dark conditions, respectively. The results are shown in [Figure number missing]. Figure 5 ,from Figure 5 It can be seen that when MoS2 is loaded onto carbon-coated copper slag-based Fe3O4 microspheres, the removal rate of chlortetracycline hydrochloride by the composite material is significantly improved. The degradation rate of chlortetracycline hydrochloride is 92.3% after 10 min and the final degradation rate is 94%. However, when carbon-coated copper slag-based Fe3O4 microspheres are used as catalysts, the degradation rate of chlortetracycline hydrochloride is 60.8% after 10 min and the final degradation rate is 78.3%.

[0033] Example 2:

[0034] Weigh 3.5g of copper slag, 5g of oxalic acid and 2.5g of deionized water. After adding oxalic acid to deionized water and stirring evenly, add copper slag and react with it until it reaches a slurry state. Quickly use a syringe to draw up the mixture and inject it into dimethyl silicone oil at 50℃. Stir with a disperser (stirring speed of 800rpm) for 4min to form spheres. Then place it in a 60℃ oven to age for 12h. After solid-liquid separation, ferrous oxalate microspheres are obtained and placed in a tube furnace to calcine at 500℃ for 5h to obtain carbon-coated Fe3O4 microspheres.

[0035] 0.618 g of ammonium molybdate and 0.25 g of carbon-coated Fe3O4 microspheres were placed in a polyethylene tetroxide liner containing 70 mL of deionized water and sonicated for 30 min. Then, 1.340 g of thiourea was added and sonicated for another 30 min. Finally, the mixture was hydrothermally reacted at 180 °C for 16 h. The mixture was filtered, and the filter residue was washed with deionized water until neutral. The residue was then dried in an oven at 60 °C for 12 h to obtain a porous geopolymer microsphere photothermal catalyst for copper smelting slag.

[0036] The catalyst prepared in this example was placed in 40 mL of a chlortetracycline hydrochloride solution with a concentration of 50 mg / L and a pH of 4.1. The amount of catalyst used was 1 g / L and the amount of H2O2 used was 0.2 mL. After treatment under natural light for 30 min, the removal rate of chlortetracycline hydrochloride was 83.3%.

[0037] Example 3:

[0038] Weigh 3.5g of copper slag, 5g of oxalic acid and 2.5g of deionized water. After adding oxalic acid to deionized water and stirring evenly, add copper slag and react with it until it reaches a slurry state. Quickly use a syringe to draw up the mixture and inject it into dimethyl silicone oil at 50℃. Stir with a disperser (stirring speed of 800rpm) for 4min to form spheres. Then place it in a 60℃ oven to age for 12h. After solid-liquid separation, ferrous oxalate microspheres are obtained and placed in a tube furnace to calcine at 500℃ for 5h to obtain carbon-coated Fe3O4 microspheres.

[0039] 0.618 g of ammonium molybdate and 0.25 g of carbon-coated Fe3O4 microspheres were placed in a polyethylene tetroxide liner containing 70 mL of deionized water and sonicated for 30 min. Then, 0.402 g of thiourea was added and sonicated for another 30 min. Finally, the mixture was hydrothermally reacted at 180 °C for 16 h. The mixture was filtered, and the filter residue was washed with deionized water until neutral. The residue was then dried in an oven at 60 °C for 12 h to obtain a porous geopolymer microsphere photothermal catalyst for copper smelting slag.

[0040] The catalyst prepared in this example was placed in 40 mL of a chlortetracycline hydrochloride solution with a concentration of 50 mg / L and a pH of 4.1. The amount of catalyst was 1 g / L and the amount of H2O2 was 0.2 mL. After treatment under natural light for 30 min, the removal rate of chlortetracycline hydrochloride was 91.6%.

[0041] Example 4:

[0042] Weigh 3.5g of copper slag, 5g of oxalic acid and 2.5g of deionized water. After adding oxalic acid to deionized water and stirring evenly, add copper slag and react with it until it reaches a slurry state. Quickly use a syringe to draw up the mixture and inject it into dimethyl silicone oil at 50℃. Stir with a disperser (stirring speed of 800rpm) for 4min to form spheres. Then place it in a 60℃ oven to age for 12h. After solid-liquid separation, ferrous oxalate microspheres are obtained and placed in a tube furnace to calcine at 500℃ for 5h to obtain carbon-coated Fe3O4 microspheres.

[0043] 0.618 g of ammonium molybdate and 0.25 g of carbon-coated Fe3O4 microspheres were placed in a polyethylene tetroxide liner containing 70 mL of deionized water and sonicated for 30 min. Then, 0.804 g of thiourea was added and sonicated for another 30 min. Finally, the mixture was hydrothermally reacted at 180 °C for 16 h. The mixture was filtered, and the filter residue was washed with deionized water until neutral. The residue was then dried in an oven at 60 °C for 12 h to obtain a porous geopolymer microsphere photothermal catalyst for copper smelting slag.

[0044] The catalyst prepared in this example was placed in 40 mL of a chlortetracycline hydrochloride solution with a concentration of 50 mg / L and a pH of 4.1. The amount of catalyst was 1 g / L and the amount of H2O2 was 0.2 mL. After treatment under natural light for 30 min, the removal rate of chlortetracycline hydrochloride was 86.9%.

[0045] Example 5:

[0046] Weigh 3.5g of copper slag, 5g of oxalic acid and 2.5g of deionized water. After adding oxalic acid to deionized water and stirring evenly, add copper slag and react with it until it reaches a slurry state. Quickly use a syringe to draw up the mixture and inject it into dimethyl silicone oil at 50℃. Stir with a disperser (stirring speed of 800rpm) for 4min to form spheres. Then place it in a 60℃ oven to age for 12h. After solid-liquid separation, ferrous oxalate microspheres are obtained and placed in a tube furnace to calcine at 500℃ for 5h to obtain carbon-coated Fe3O4 microspheres.

[0047] 0.3708 g of ammonium molybdate and 0.25 g of carbon-coated Fe3O4 microspheres were placed in a polyethylene tetroxide liner containing 70 mL of deionized water and sonicated for 30 min. Then, 0.804 g of thiourea was added and sonicated for another 30 min. Finally, the mixture was hydrothermally reacted at 180 °C for 16 h. The mixture was filtered, and the filter residue was washed with deionized water until neutral. The residue was then dried in an oven at 60 °C for 12 h to obtain a porous geopolymer microsphere photothermal catalyst for copper smelting slag.

[0048] The catalyst prepared in this example was placed in 40 mL of a chlortetracycline hydrochloride solution with a concentration of 50 mg / L and a pH of 4.1. The amount of catalyst was 1 g / L and the amount of H2O2 was 0.2 mL. After treatment under natural light for 30 min, the removal rate of chlortetracycline hydrochloride was 91.5%.

Claims

1. A method for preparing a porous geopolymer microsphere photothermal catalyst from copper smelting slag, characterized in that, The steps are as follows: (1) Add copper slag powder to oxalic acid solution and mix well to obtain slurry; (2) Under stirring conditions, the slurry was dropped into dimethyl silicone oil at 50-60℃ and formed into balls under the action of stirring mechanical force. Then the mixture was aged at 55-65℃ for 12h, solid and liquid were separated, ferrous oxalate microspheres were collected and placed in a tube furnace for calcination under N2 atmosphere to obtain carbon-coated Fe3O4 microspheres. (3) Place ammonium molybdate and carbon-coated Fe3O4 microspheres in deionized water and sonicate for 25-35 min. Then add thiourea and continue sonicating for 25-35 min. Then, perform hydrothermal reaction at 150-200℃ for 14-18 h. Separate the solid and liquid, wash the solid with deionized water until neutral, and dry to obtain the copper smelting slag porous geopolymer microsphere photothermal catalyst.

2. The method for preparing the porous geopolymer microsphere photothermal catalyst of copper smelting slag according to claim 1, characterized in that: The mass ratio of oxalic acid to copper slag powder is 1-2:

1.

3. The method for preparing the porous geopolymer microsphere photothermal catalyst of copper smelting slag according to claim 1, characterized in that: The mass ratio of ammonium molybdate to carbon-coated Fe3O4 microspheres was 1:0.4-2, and the mass ratio of ammonium molybdate to thiourea was 1:0.6-2.

5.

4. The method for preparing the porous geopolymer microsphere photothermal catalyst of copper smelting slag according to claim 1, characterized in that: The stirring speed in step (2) is 700-900 rpm.

5. The method for preparing the porous geopolymer microsphere photothermal catalyst of copper smelting slag according to claim 1, characterized in that: Copper slag powder is obtained by grinding dried copper slag through a 200-mesh sieve, with a residue of less than 5%.

6. The application of the copper smelting slag porous geopolymer microsphere photothermal catalyst prepared by the method of any one of claims 1-5 in the removal of chlortetracycline hydrochloride.

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