Copper slag derived microsphere composite catalyst and application thereof in catalytic degradation of oxytetracycline hydrochloride

Abstract

The invention discloses a copper slag derived microsphere composite catalyst which is prepared by the following steps: crushing and screening dried copper slag, mixing copper chloride and the copper slag, adding the mixture into an oxalic acid solution, uniformly stirring and mixing to obtain slurry, dropwise adding the slurry into silicone oil, stirring to form balls, aging at 55-65 DEG C for 12 hours, collecting the balls, and calcining at 500-600 DEG C for 2-4 hours to obtain the copper slag derived microsphere composite catalyst. And putting the calcined product into a thioacetamide-ethylene glycol solution, uniformly mixing, carrying out a hydrothermal reaction at 150-170 DEG C for 12 hours, carrying out solid-liquid separation, and drying the solid, the catalyst disclosed by the invention shows excellent PMS activation and degradation effects on oxytetracycline hydrochloride, tetracycline hydrochloride, chlortetracycline hydrochloride, methylene blue and methyl orange; the invention provides a new solution for solving the problem of secondary pollution caused by the copper slag and the problem of water environment pollution caused by antibiotic organic pollutants.

Description

Technical Field

[0001] This invention relates to a copper slag-derived microsphere composite catalyst and its application in the catalytic degradation of oxytetracycline hydrochloride, belonging to the fields of solid waste resource utilization and advanced oxidation. Background Technology

[0002] With the rapid development of my country's economy and technology, copper consumption has continued to rise, leading to increasingly serious problems in the treatment of smelting solid waste. Copper slag (CS), a byproduct of pyrometallurgical copper smelting, has an annual output exceeding ten million tons. The traditional disposal method for this solid waste is mainly open-air stockpiling, which poses potential environmental risks in three main aspects: First, the risk of heavy metal migration, as toxic elements such as arsenic (As) and lead (Pb) contained in the slag can lead to soil-groundwater system pollution through rainwater leaching; Second, dust diffusion pollution, as fine particulate matter with a particle size of less than 75μm during dry stockpiling can easily cause PM2.5 / PM10 pollution; Third, the problem of resource waste, as typical copper slag contains 35-42% Fe (in the form of iron olivine Fe2SiO4 and magnetite Fe3O4), and the Cu content is between 0.8-3.0% (mainly in the form of chalcocite Cu2S and copper oxide CuO), while also containing considerable amounts of SiO2 (25-35%), Al2O3 (3-8%), and alkaline earth metal oxides.

[0003] With the global overuse of antibiotics in medicine, agriculture, and animal husbandry, antibiotic pollution in aquatic environments continues to worsen. Tetracycline antibiotics (TCs), a broad-spectrum antibacterial agent with an annual global production exceeding 100,000 tons, can reach wastewater concentrations in the μg / L to mg / L range. These pollutants are difficult to biodegrade in natural water bodies, can induce oxidative stress damage in aquatic organisms, and seriously threaten public health and safety. Advanced oxidation processes (AOPs) based on free radical chemistry, due to their strong oxidizing properties (oxidation potential: •OH = 1.8-2.7 V, •SO4), offer a solution. − =2.5-3.1 V) and broad-spectrum degradation ability have become key technologies for solving the problem of antibiotic pollution. Among them, persulfate (HSO5) − The PMS activation system has attracted much attention due to its combination of homogeneous / heterogeneous reaction pathways, wide pH adaptability, and free radical-non-free radical synergistic mechanism.

[0004] Fe2O3, as a type of metal oxide, exhibits excellent performance in the activation of PMS, but its degradation efficiency is low due to its high electron-hole recombination rate. Summary of the Invention

[0005] To address the problems of existing technologies, this invention provides a copper slag-derived microsphere composite catalyst. The process involves crushing and sieving dried copper slag, mixing copper chloride with the copper slag, adding the mixture to an oxalic acid solution, stirring to obtain a slurry, adding the slurry dropwise to silicone oil, stirring to form spheres, aging at 55-65℃ for 12 hours, collecting the spheres, and then calcining them at 500-600℃ for 2-4 hours. The calcined product is then placed in a thioacetamide-ethylene glycol solution, mixed, and subjected to a hydrothermal reaction at 150-170℃ for 12 hours. Solid-liquid separation is then performed, and the solid is dried to obtain the final catalyst. The catalyst prepared by this invention solves the problems of slow charge transfer and high recombination rate of photogenerated electrons and holes in Fe2O3. Furthermore, the catalyst particle size is controllable, it is magnetic, and this facilitates separation, recovery, and recycling.

[0006] The mass ratio of copper chloride to copper slag is 1:2-8; the mass ratio of copper slag to oxalic acid is 1:1-1.5; and the mass ratio of copper slag to thioacetamide is 1-3:1.

[0007] The stirring speed for forming the balls is 800-1000 rpm.

[0008] Another objective of this invention is to apply the above-mentioned copper slag-derived microsphere composite catalyst to the catalytic degradation of oxytetracycline hydrochloride, tetracycline hydrochloride, chlortetracycline hydrochloride, methylene blue, and methyl orange, with permonosulfate (PMS) added during the degradation process.

[0009] Compared with the prior art, the advantages of the present invention are: This invention constructs a copper slag-derived microsphere composite catalyst with Fe-OS and Cu-S-Fe interfacial chemical bonds via suspension polymerization-oxidative calcination and solvothermal methods. Compared with metal oxides, the metal sulfide catalyst of this invention exhibits higher carrier mobility and better Fermi level matching characteristics; in the metal sulfide, S... 2- Electron transfer to active sites is facilitated through Fe-S and Cu-S bonds, thereby enhancing Cu 2+ / Cu + and Fe 3+ / Fe 2+ The cycle efficiency, and Cu 2+ / Cu + The redox potential (E0=0.16) is higher than that of Fe. 3+ / Fe 2+ The catalyst exhibits a low redox potential (E0 = 0.77), which is thermodynamically favorable for electron transfer. It is particularly effective in activating PMS to degrade OTC, achieving a reduction in OTC (50 mg·L⁻¹) within 20 min. −1 The degradation rate is 100%, and it has excellent activation properties; FeS2 contains abundant ferrous ions, which can be activated by a series of methods. 3+ / Fe2+ The active centers accelerate the reaction rate; they possess advantages such as long-lasting activity, high activation efficiency, and ease of separation and recovery; CuS is a p-type photocatalyst with a narrow band gap, exhibiting transmissivity in the infrared region, low reflectivity in the visible region, and high reflectivity in the near-infrared region. It also boasts advantages such as high redox activity, low cost, good stability, and low toxicity; therefore, both are ideal materials for preparing activated persulfate catalysts. The catalyst prepared by this invention is microsphere-shaped with controllable particle size, magnetic properties, and is easier to separate, recycle, and reuse. Furthermore, the preparation process is simple, the experimental raw material copper slag is readily available, and the cost is low, enabling the high-value utilization of copper slag. Attached Figure Description

[0010] Figure 1 The catalysts used in Example 1 were 0.5-(Fe-Cu)S, in Comparative Example 1 it was 0.5-Fe-Cu, and in Comparative Example 2 it was FeS. x XRD pattern; Figure 2 Here is a SEM image of the catalyst 0.5-(Fe-Cu)S from Example 1; Figure 3 The figures show the removal effects of Examples 1-3, Comparative Examples 1-2, and commercially available Fe2O3 on oxytetracycline hydrochloride; Figure a shows the comparison of removal rates; Figure b shows the catalytic degradation data fitted by the first-order kinetic equation. Figure 4 The degradation rate of various organic pollutants by the catalyst 0.5-(Fe-Cu)S in Example 1 is shown. Detailed Implementation

[0011] To better understand the specific content of this invention, the following specific examples are provided to illustrate the invention in detail, but the scope of protection of this invention is not limited to the following content; The main components of the copper slag in the following examples are shown in the table below:

[0012] Example 1: Preparation of copper slag-derived microsphere composite catalyst 1. After drying the copper slag, grind it using a drum ball mill and pass it through a 200-mesh sieve; 2. Mix 0.5g of copper chloride monohydrate and 4g of copper slag powder, add to an oxalic acid aqueous solution (prepared by mixing 5g of oxalic acid and 3.1g of deionized water), stir evenly to obtain a slurry, use a syringe to draw up the slurry and drop it into silicone oil, stir it into pellets at 900 rpm using a disperser, age in a 60℃ oven for 12 hours, filter, collect the pellets, and then calcine at 500℃ for 3 hours to obtain Fe-Cu microspheres; the XRD pattern of Fe-Cu microspheres is shown in [reference needed]. Figure 1As can be seen from the figure, the main peak of Fe2O3 (JCPDS 39-1346) is observed at the diffraction peaks corresponding to the crystal planes (220), (311), (400), (422), (511) and (440), indicating that Cu doping is present. 2+ It will not destroy the Fe2O3 crystal lattice; 2. Fe-Cu microspheres and a thioacetamide solution (prepared by dissolving 2g of thioacetamide in 40mL of ethylene glycol for 30min) were added together to a polyethylene reactor, mixed thoroughly, and then hydrothermally reacted at 160℃ for 12h. The mixture was filtered, and the solid was dried in an oven at 60℃ to obtain the copper slag-derived microsphere composite catalyst (0.5-(Fe-Cu)S). The XRD pattern of the catalyst is shown in the figure. Figure 1 As shown, diffraction peaks were observed for three crystals: Fe2O3, FeS2, and CuS. Their macroscopic morphologies are as follows. Figure 2 As shown, the nanosheet-like structure (CuS) embedded on the microspheres can be clearly seen, proving the successful synthesis of the (Fe-Cu)S composite material.

[0013] Example 2: Preparation of copper slag-derived microsphere composite catalyst The catalyst preparation method in this embodiment is the same as in Example 1, except that the amount of copper chloride monohydrate added is 1g, and catalyst 1-(Fe-Cu)S is obtained.

[0014] Example 3: Preparation of copper slag-derived microsphere composite catalyst The catalyst preparation method in this embodiment is the same as in Example 1, except that the amount of copper chloride monohydrate added is 2g, and catalyst 2-(Fe-Cu)S is obtained.

[0015] Comparative Example 1: The Fe-Cu microspheres prepared in step 1 of Example 1 were used as the catalyst (0.5-Fe-Cu) for Comparative Example 1.

[0016] Comparative Example 2: FeS x Preparation 4g of copper slag powder was added to an oxalic acid aqueous solution (prepared by mixing 5g of oxalic acid and 3.1g of deionized water), stirred evenly to obtain a slurry, and the slurry was drawn up with a syringe and added dropwise to silicone oil. The mixture was stirred into pellets at 900rpm using a disperser, aged in a 60℃ oven for 12h, filtered, and the pellets were collected. Then, the pellets were calcined at 500℃ for 3h. The calcined product was added to a thioacetamide solution (prepared by dissolving 2g of thioacetamide in 40mL of ethylene glycol for 30min), mixed evenly, and then hydrothermally reacted at 160℃ for 12h. The mixture was filtered, and the solid was dried in a 60℃ oven to obtain the composite material FeS. x Its XRD pattern is as follows: Figure 1 As shown, in 2 θThe main peak of FeS2 was observed at 32.976°, 37.001°, 40.681°, 47.328°, 56.153°, and 64.141°, while at 2 θ The main peaks of Fe2O3 were still observed at 30.241° and 62.925°, indicating that FeS x Successful synthesis of composite materials.

[0017] Example 4: Treatment of Oxytetracycline Hydrochloride (OTC) Wastewater under Irradiation with Catalysts from Examples 1-3 and Comparative Examples 1-2 and Commercially Available Fe2O3. Catalysts from Examples 1-3 and Comparative Examples 1-2, and commercially available Fe2O3 were placed in 40 mL of a 50 mg / L OTC solution at a ratio of 1 g / L. After mixing thoroughly, 3 mM PMS was quickly added, and the reaction was carried out in a photocatalytic instrument at 25 ± 1 °C. Every 5, 10, 15, and 20 min, 3 mL of the reaction product was taken using a syringe, filtered through a 0.45 μm PTFE membrane, and the filtrate was poured into a cuvette. The absorbance was measured at a wavelength of 430 nm using a UV-Vis spectrophotometer, and the degradation rate of OTC was calculated.

[0018] The results are as follows Figure 3 As shown in the left figure, the copper slag-derived microsphere composite catalysts of Examples 1-3, after Cu doping and sulfidation, have significantly better OTC removal efficiency than the catalysts of Comparative Examples 1-2 and commercially available Fe2O3. Among them, the catalyst of Example 1 has the best effect, reaching a removal rate of 100% in 10 minutes.

[0019] The catalytic degradation data were fitted using first-order kinetic equations for the catalysts 0.5-Fe-Cu and FeS. x A more comprehensive analysis was conducted on the catalytic activity of 0.5-(Fe-Cu)S; as shown in the right figure, the 0.5-(Fe-Cu)S catalyst exhibits the highest rate constant (k = 0.3167 min). -1 This indicates that doping and sulfidation significantly improve the photodegradation rate of the catalyst.

[0020] To further evaluate the versatility of the (Fe-Cu)S catalyst, 0.5-(Fe-Cu)S catalyst from Example 1 was placed at a ratio of 1 g / L into 40 mL of solutions containing tetracycline hydrochloride (TC) at a concentration of 20 mg / L, chlortetracycline hydrochloride (CTC) at a concentration of 25 mg / L, methylene blue (MB) at a concentration of 50 mg / L, and methyl orange (MO) at a concentration of 20 mg / L. After complete dispersion, 3 mM PMS was quickly added, and the reaction was carried out in a photocatalytic instrument at 25 ± 1 °C. Samples were taken at intervals, and the absorbance was measured using a UV-Vis spectrophotometer to calculate the removal rate.

[0021] The results are as follows Figure 4 As shown, except for CTC, the removal rate of other pollutants reached almost 100% within 20 minutes, indicating that the (Fe-Cu)S / Light / PMS system has great removal potential for organic pollutants such as antibiotics and dyes.

Claims

1. A copper-slag derived microspheres composite catalyst, characterized in that: After the dry copper residue is crushed and sieved, copper chloride and copper residue are mixed and added to oxalic acid solution, and the slurry is prepared after stirring and mixing. The slurry is added dropwise to silicone oil, stirred into balls, aged at 55-65℃ for 12h, the balls are collected, then calcined at 500-600℃ for 2-4h, the calcined product is placed in a solution of thioacetamide-ethylene glycol, mixed, and then hydrothermal reaction is carried out at 150-170℃ for 12h, solid-liquid separation is carried out, and the solid is dried to obtain a copper residue-derived microsphere composite catalyst.

2. The copper-slag derived microspheres composite catalyst according to claim 1, characterized in that: The mass ratio of copper chloride to copper residue is 1:2-8; the mass ratio of copper residue to oxalic acid is 1:1-1.

5.

3. The copper-slag derived microspheres composite catalyst according to claim 1, characterized in that: The mass ratio of copper residue to thioacetamide is 1-3:

1.

4. The copper-slag derived microspheres composite catalyst according to claim 1, wherein: The stirring speed for stirring into balls is 800-1000 rpm.

5. The use of the copper residue-derived microsphere composite catalyst according to any one of claims 1-4 in catalytic degradation of oxytetracycline hydrochloride, tetracycline hydrochloride, aureomycin hydrochloride, methylene blue, and methyl orange.

6. Use according to claim 5, characterized in that: Peroxydisulfate is added during the degradation process.

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