Method for preparing a photo-fenton-like catalyst by co-pyrolysis of steel slag and orange peel and application thereof

Abstract

The application discloses a method for preparing a Fenton-like catalyst by co-pyrolysis of steel slag and orange peel and application thereof, and belongs to the technical field of catalytic materials. Biomass material is prepared by cleaning, drying, crushing and passing through a 100-mesh sieve, steel slag is prepared by crushing and passing through a 200-mesh sieve, the pretreated biomass powder and the steel slag powder are stirred and mixed according to different mass ratios, the obtained mixture is co-pyrolyzed at a high temperature of 600-900 DEG C, and then the co-pyrolysis product is cleaned, dried, ground and sieved to obtain a Fenton-like catalyst. The application uses cheap steel slag and orange peel as raw materials to prepare a composite material for a Fenton-like catalyst by co-pyrolysis, uses cheap orange peel as a modifier, strengthens the activation effect by introducing carbon material, fully utilizes beneficial components (such as metal oxides like iron oxides) in the steel slag, and fully improves the pore structure of the steel slag, so that a high-efficiency Fenton-like catalyst is prepared, and the purpose of treating waste with waste is achieved.

Description

Technical Field

[0001] This invention belongs to the field of catalytic materials technology, and relates to a method for preparing a photo-Fenton-like catalyst by co-pyrolysis of steel slag and orange peel, and its application in the treatment of organic wastewater such as dyeing and printing. Background Technology

[0002] Steel slag is an industrial solid waste generated during the steelmaking process. To achieve green and low-carbon development in China's steel industry, research and application of steel slag resource utilization technologies are urgently needed. Currently, steel slag is commonly used in building materials, road construction, and cement production, but the resource-based products formed by these traditional technologies have low intrinsic value and lack market competitiveness. Preliminary research and theoretical analysis have revealed that steel slag is rich in various metals (Fe, Mn, Al, etc.) and non-metallic oxides, making it a promising candidate for use as a photo-Fenton-like catalyst in wastewater treatment. However, steel slag as a photo-Fenton-like catalyst also suffers from problems such as a low number of highly active sites, a high content of alkaline components (CaO and MgO, etc.), and poor stability. This leads to low carrier migration and separation efficiency, easy recombination of photogenerated electron-hole pairs, and consequently, low catalytic activity, unsatisfactory effects, and poor stability.

[0003] Biochar is a black, carbon-rich, and porous solid material prepared through the thermochemical conversion of biomass under oxygen-deficient or oxygen-limited conditions. As a carbon material, biochar possesses a porous structure, large specific surface area, and strong electron transport capacity, which is beneficial for improving the pore structure of steel slag, increasing its specific surface area, and enhancing its catalytic activity (enhancing electron transport efficiency). Currently, biochar is widely used in advanced oxidation technologies, and its raw materials can often be agricultural and forestry waste. This not only enables large-scale resource utilization and even high-quality utilization of agricultural and forestry waste, reducing the potential harm of agricultural and forestry waste accumulation to the ecological environment and human health, but also, through biochar structure regulation (such as constructing defects, N doping, etc.), further constructing electron-rich active sites (graphite N, pyridine N, and pyrrole N, etc., which readily adsorb metal ions) and electron-deficient active sites (graphite C, which readily adsorbs negatively charged organic pollutants) in steel slag / biochar composite catalysts, effectively reducing the dissolution of metal elements and improving catalytic reaction efficiency. By co-pyrolyzing biomass (such as Gannan navel orange peel and grapefruit peel) with steel slag, the problems of low catalytic activity (slow electron migration rate), poor stability, and poor reusability of steel slag as a single catalyst can be effectively solved. This will resolve the difficulties that restrict the industrialization of steel slag-based catalysts, realize the resource utilization and even high-value utilization of steel slag, and achieve the goal of "treating waste with waste". Summary of the Invention

[0004] Given the current problems with using steel slag as a photo-Fenton-like catalyst: (1) steel slag has only a limited number of highly active (mineral) sites, resulting in low activity; (2) steel slag contains alkaline components (CaO and MgO, etc.), which easily undergo hydration reactions, leading to volume expansion and poor stability; this invention was proposed. Therefore, the purpose of this invention is to provide a photo-Fenton-like catalyst prepared by co-pyrolysis of biomass (navel orange peel, etc.) / steel slag and applied to the treatment of organic wastewater such as dyeing and printing, without the need for the addition of large amounts of chemical agents, resulting in low energy consumption and greatly improving the ability of the composite catalyst to activate persulfate.

[0005] To fully utilize the beneficial components in steel slag (such as iron oxides and other metal oxides) and effectively improve its pore structure (by co-pyrolysis generating CO2 and other gases to expand pores), this invention introduces biomass (orange peel, grapefruit peel, etc.) and performs a co-pyrolysis process to achieve efficient activation of persulfate. This invention uses biomass raw materials such as orange peel, grapefruit peel, and straw as modifiers and co-pyrolyzes them with steel slag to prepare a highly active photo-Fenton-like catalyst. To achieve the above-mentioned objectives, this invention employs the following technical means:

[0006] This invention discloses a method for preparing a photo-Fenton-like catalyst by co-pyrolysis of steel slag and orange peel, comprising:

[0007] (1) Biomass raw materials are washed with deionized water, dried, crushed and sieved to obtain biomass powder for use;

[0008] (2) The steel slag is crushed and sieved to obtain steel slag powder for later use;

[0009] (3) The biomass powder and steel slag powder are mixed and then subjected to high-temperature oxygen-deficient co-pyrolysis to obtain pyrolysis products;

[0010] (4) The pyrolysis products are washed (acid washing, water washing, etc.), dried, ground and sieved to obtain a kind of photo-Fenton catalyst.

[0011] Furthermore, the biomass raw materials mentioned in step (1) include, but are not limited to: (Gannan navel) orange peel, pomelo peel, straw, leaves and other agricultural and forestry waste.

[0012] Further, the drying temperature in step (1) is 40-105℃, the drying time is 4-12h, the optimal drying time is 12h, and the sieve is 60-200 mesh, with the optimal sieve being 100 mesh.

[0013] Furthermore, the sieving in step (2) is a 60-200 mesh sieve, with the optimal sieving being a 200 mesh sieve.

[0014] Furthermore, the co-pyrolysis in step (3) is performed using a tubular furnace, and N2 is introduced at a flow rate of 10-50 mL / min, with air venting time of 10-30 min.

[0015] Furthermore, the co-pyrolysis temperature in step (3) is 600–900°C, and the co-pyrolysis time is 1–3 h.

[0016] Furthermore, the optimal co-pyrolysis temperature is 800°C.

[0017] Furthermore, the mass ratio of biomass powder to steel slag powder in step (3) is 1:1-3, and the optimal mass ratio is 1:2.

[0018] The present invention also discloses a photo-Fenton-like catalyst prepared according to any of the above preparation methods.

[0019] This invention also discloses the application of the above-mentioned photo-Fenton-like catalyst in the photo-activated degradation of organic wastewater such as dyeing and printing wastewater.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) A highly efficient photo-Fenton-like catalyst was prepared by co-pyrolyzing inexpensive agricultural and forestry waste materials such as steel slag, orange peel, and straw with steel slag that urgently needed to be treated. This achieved the degradation treatment of organic wastewater such as dyeing and printing, and achieved the goal of "treating waste with waste".

[0022] (2) Using widely available agricultural and forestry waste (such as Gannan navel orange peel) as a modifier, the catalytic activity and surface pore structure of steel slag are improved by introducing biochar materials with excellent conductors, increasing surface catalytic sites, and enhancing the activation effect of persulfate. This further solves the problems of low catalytic activity (slow electron migration rate), poor stability and poor reusability of steel slag as a catalyst. Attached Figure Description

[0023] Figure 1 The effect of catalysts prepared at different mass ratios (orange peel powder and steel slag powder) on the degradation of Rhodamine B in the system is shown in the figure. Detailed Implementation

[0024] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly introduce some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0025] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0026] Example 1

[0027] A method for preparing a photo-Fenton-like catalyst by co-pyrolysis of steel slag and orange peel includes:

[0028] (1) Biomass raw material (Gannan navel orange peel) is washed with deionized water, dried at 40℃ for 12 hours, crushed and passed through a 60-mesh sieve to obtain biomass powder for later use.

[0029] (2) The steel slag is crushed and passed through a 100-mesh sieve to obtain steel slag powder for later use;

[0030] (3) Mix biomass powder and steel slag powder, wherein the mass ratio of orange peel powder to steel slag powder is 1:1 and 1:3 respectively. After loading into the corundum crucible, place it into a tube furnace, introduce N2 into the tube furnace at a rate of 20 mL / min, and exhaust air for 30 min. Then raise the temperature of the pyrolysis furnace to 700℃ at a rate of 10℃ / min and keep it constant for 1 h to obtain the pyrolysis product.

[0031] (4) The pyrolysis products are washed, dried, ground and sieved to obtain a photo-Fenton-like catalyst.

[0032] Example 2

[0033] A method for preparing a photo-Fenton-like catalyst by co-pyrolysis of steel slag and orange peel includes:

[0034] (1) Biomass raw material (grapefruit peel) is washed with deionized water, dried at 60℃ for 8 hours, crushed and passed through a 100-mesh sieve to obtain biomass powder for later use;

[0035] (2) The steel slag is crushed and passed through a 100-mesh sieve to obtain steel slag powder for later use;

[0036] (3) Mix biomass powder and steel slag powder in equal mass, put them into a corundum crucible and then put it into a tube furnace. Introduce N2 into the tube furnace at a rate of 40 mL / min and exhaust air for 15 min. Then raise the temperature of the pyrolysis furnace to 600℃ at a rate of 5℃ / min and keep it constant for 1 h to obtain the pyrolysis product.

[0037] (4) The pyrolysis products are washed, dried, ground and sieved to obtain a photo-Fenton-like catalyst.

[0038] Example 3

[0039] A method for preparing a photo-Fenton-like catalyst by co-pyrolysis of steel slag and orange peel includes:

[0040] (1) Biomass raw material (straw) is washed with deionized water, dried at 105℃ for 4 hours, crushed and passed through a 200-mesh sieve to obtain biomass powder for use;

[0041] (2) The steel slag is crushed and passed through a 100-mesh sieve to obtain steel slag powder for later use;

[0042] (3) Mix biomass powder and steel slag powder in equal mass, put them into a corundum crucible and then put it into a tube furnace. Introduce N2 into the tube furnace at a rate of 50 mL / min and exhaust air for 10 min. Then raise the temperature of the pyrolysis furnace to 900℃ at a rate of 15℃ / min and keep it constant for 1 h to obtain the pyrolysis product.

[0043] Experimental Example 1

[0044] The specific steps for degrading organic wastewater using the photo-Fenton-like catalyst synthesized in Example 1 are as follows:

[0045] Using 50 mL of 20 mg / L Rhodamine B as the degradation target, with a catalyst dosage of 0.05 g, the mixture was ultrasonically stirred for 5 min until homogeneous, then magnetically stirred. All systems required 30 min of shaking to reach adsorption equilibrium before adding PMS for catalytic experiments. PMS was added at 0.5 g under simulated sunlight (xenon lamp) conditions. Three parallel samples (adsorption samples) were taken at t = 0 min, 20 min, and 30 min, and their absorbance was measured to determine if equilibrium had been reached. Once equilibrium was reached, PMS was added, and three parallel samples (catalytic samples) were taken at t = 2 min, 4 min, 6 min, 8 min, 10 min, and 15 min after illumination. 1 mL of methanol was added to the sampling tube 30 s before sampling to quench the catalytic reaction. The sampling volume was 1 mL per sample, filtered through a 0.45 μm filter membrane, and the absorbance was measured immediately. Specific results are as follows: Figure 1As shown, compared with orange peel biochar alone, when the mass ratio of orange peel to steel slag is 1:3, the activation performance of the composite catalyst for persulfate is significantly improved. After 10 min of reaction, the degradation rate of Rhodamine B increased from 19.25% to 65.12%. However, when the mass ratio of orange peel to steel slag is 1:1, the degradation rate of Rhodamine B increases to 97.58% after 10 min of reaction. Further increasing the amount of orange peel added does not significantly improve the activation performance of persulfate. In summary, the composite catalyst exhibits the best catalytic degradation performance for Rhodamine B when the mass ratio of orange peel to steel slag is 1:1. This is likely because when the mass ratio of steel slag to orange peel is equal, the rapid heating of the steel slag effectively ensures uniform heating of the orange peel and protects the orange peel biochar, preventing excessive loss as CO2 and other gases. This results in the formation of a steel slag / biochar composite. Under light irradiation, photogenerated electrons from the metal oxides (such as iron oxides and other semiconductors) in the steel slag can be rapidly transferred to the biochar (due to its excellent electron conductivity), achieving photogenerated electrons (which can... The separation of photogenerated electrons and holes effectively enhances the synergistic activation performance of the composite catalyst for persulfate. However, when the amount of orange peel is too small, the biochar production is too low, resulting in insufficient biochar content in the composite catalyst, making it difficult to achieve the separation of photogenerated electrons and holes, thus reducing the activation performance of persulfate. Conversely, if the amount of orange peel is too large, the content of steel slag in the catalyst is too low, resulting in insufficient content of metal oxides such as Fe, Mn, and Al, making it difficult to effectively exert the semiconductor effect, leading to a significant decrease in the activation performance of the composite catalyst for persulfate. In summary, the mass ratio of orange peel to steel slag should be within a reasonable range (1:1 to 1:3). A mass ratio that is too high or too low will result in poor photodegradation of Rhodamine B by the composite catalyst.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. Application of a photo-Fenton-like catalyst in the degradation of printing and dyeing wastewater by photo-activated persulfate, wherein: The photo-Fenton-like catalyst is prepared by the following method: (1) Biomass raw materials are cleaned with deionized water, dried, crushed, and sieved to obtain biomass powder for use, and the biomass raw materials are agricultural and forestry wastes, including orange peel, pomelo peel, straw, and tree leaves; (2) Steel slag is crushed and sieved to obtain steel slag powder for use; (3) The biomass powder and the steel slag powder are mixed at a mass ratio of 1:1-3, and then high-temperature co-pyrolysis treatment is performed, the co-pyrolysis uses a tubular furnace, and N2 is introduced, the flow rate of N2 is 10-50 mL / min, the exhaust air time is 10-30 min, the co-pyrolysis temperature is 600-900℃, and the co-pyrolysis time is 1-3 h, to obtain a pyrolysis product; (4) The pyrolysis product is cleaned, dried, ground, and sieved to obtain a photo-Fenton-like catalyst.

2. The application according to claim 1, wherein: In step (1), the drying temperature is 40-105℃, the drying time is 4-12 h, and the sieving is performed on a 60-200 mesh sieve.

3. The application according to claim 1, wherein: In step (2), the sieving is performed on a 60-200 mesh sieve.

4. The application according to claim 1, wherein: In step (3), the optimal co-pyrolysis temperature is 800℃.

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