CN114534741B - Attapulgite/manganese dioxide/ferroferric oxide nanocomposite and preparation method and application thereof - Google Patents

Abstract

The invention discloses an attapulgite/manganese dioxide/ferroferric oxide nanocomposite and a preparation method and application thereof. The natural attapulgite which is cheap and easy to obtain is used as a carrier of the nano composite material, and can prevent the agglomeration of manganese dioxide particles, thereby improving the catalytic activity. The addition of the ferroferric oxide particles allows the nanocomposite to be rapidly separated from the solution by a magnetic recovery technique that is simple to operate. The prepared nanocomposite has the advantages of high catalytic efficiency, wide pH application range, easy recovery, recycling, simple preparation process, low cost and the like, and has wide application prospect in the aspect of treating organic pollutants.

Description

Attapulgite/manganese dioxide/ferric oxide nanocomposite and preparation method thereof and application

Technical field

The invention relates to the technical field of nanomaterials, and specifically relates to attapulgite/manganese dioxide/ferric oxide nanocomposite materials, their preparation methods and their application in degrading organic pollutants.

Background technique

With the vigorous development of textile, papermaking, leather, medical, animal husbandry and other industries, a large number of organic pollutants are produced, making water pollution more serious. Organic wastewater contains a large number of organic pollutants (such as methylene blue, methyl orange, acid red, phenol, antibiotics, etc.). It has the characteristics of large color, strong biological toxicity, and refractory degradation. It affects the photosynthesis of aquatic plants and seriously harms the health of aquatic plants. ecological environment and human health. Therefore, the treatment of organic wastewater has become an urgent water environment problem that needs to be solved.

In recent years, advanced oxidation technologies (such as Fenton or Fenton-like technology, photocatalytic oxidation, etc.) have received increasing attention due to their excellent degradation performance of organic pollutants. Compared with the traditional oxidant H ₂ O ₂ , the Fenton-like reaction in which persulfate (PMS) or persulfate (PS) participates can oxidize target pollutants more thoroughly and is applicable to a wide pH range. Among them, there are many ways to activate PMS, such as heating, ultraviolet light irradiation, transition metal oxides, etc. Currently, transition metal catalysts, such as CuO, CeO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ and MnO ₂ as PMS catalysts, have attracted much attention due to their advantages such as low energy consumption, low cost, and good reactivity. Among these transition metal catalysts, manganese dioxide has higher cost performance, better catalytic activity and lower toxicity, and is one of the most suitable catalysts for practical applications. Wu Guangrui (2018) et al. synthesized linear MnO ₂ and used it to activate PMS to degrade Rhodamine B, and achieved 91% of Rhodamine B degradation within 20 minutes. Luo Moufu (2015) studied the fibrous catalyst α-MnO ₂ /PMS heterogeneous catalytic degradation system and found that the degradation efficiency of phenol reached 100% within 10 minutes. However, manganese dioxide nanoparticles are prone to agglomeration, resulting in a significant reduction in their specific surface area, available active sites, and catalytic activity. In order to maintain the excellent catalytic activity of manganese dioxide, manganese dioxide needs to be supported on a stable carrier.

Natural attapulgite (also known as palygorskite) is a chain-layered nanorod-shaped clay mineral containing magnesium aluminosilicates (crystal diameter 40 nm). It has a unique rod-shaped crystal structure, large specific surface area, and developed nanopores. Features. It has been reported that attapulgite with excellent dispersion functions as a low-cost, environmentally friendly catalyst or catalyst support to prevent the agglomeration of manganese dioxide particles. Li et al. (2013) prepared attapulgite-supported Ce _1-x Mn _x O ₂ mesogenic oxide, and the catalytic degradation rate of methyl orange could reach 98%. However, shortcomings such as difficulty in recycling and separation limit the practical engineering application of nanocatalysts. Many studies have proven that the magnetic material ferroferric oxide can solve these problems. In addition, ferric oxide is also widely used as an adsorbent or catalyst to remove organic pollutants, heavy metals, dyes, etc.

Therefore, the present invention uses attapulgite as raw material, adds potassium permanganate, divalent manganese ion reducing agent, and ferric oxide, and uses a hydrothermal method to prepare attapulgite/manganese dioxide/ferric oxide nanocomposite material. It solves the problem of poor catalytic degradation of organic pollutants by a single attapulgite or metal oxide, and provides a new material and method for the treatment of organic pollutants.

Contents of the invention

The technical problem to be solved by the present invention is to provide an attapulgite/manganese dioxide/ferric oxide nanocomposite material and a preparation method thereof, which solves the problem of poor catalytic degradation of organic pollutants by a single attapulgite or metal oxide. Difficult recycling problem.

In order to solve the problems existing in the above technology, the technical solution of the present invention is:

A method for preparing attapulgite/manganese dioxide/ferric oxide nanocomposite, including the following steps: (1) Weigh a certain amount of ferrous sulfate heptahydrate, dissolve it in water, and then add polyethylene Pyrrolidone, stir and heat, then add sodium hydroxide solution with a concentration of 3 mol/L to 5 mol/L to the solution. After it forms a blue-green precipitate, continue heating and stirring. Stop heating after the blue-green precipitate turns black. And cool to room temperature, centrifuge, wash and dry to obtain ferric oxide powder;

(2) Use attapulgite as raw material, add potassium permanganate, divalent manganese ion reducing agent and ferric oxide powder obtained in step (1), add pure water, oscillate in a water bath oscillator, ultrasonic, and centrifuge , washed, dried, and ground to more than 200 mesh to obtain attapulgite/manganese dioxide/ferric oxide nanocomposite.

Further, in step (1), the heating temperature is 70-80°C, and the heating and stirring time is continued for 1.5-2 h.

Further, in step (2), the dosage of potassium permanganate is 40-60% of the mass of attapulgite.

Further, in step (2), the amount of divalent manganese ion reducing agent is 0.0319~0.0390 mol/L.

Further, in step (2), the mass ratio of ferroferric oxide powder to attapulgite is 1:3.3 to 1:5.

Further, in step (2), the water bath and drying conditions are: shake in a water bath oscillator at 20-25°C and 200-250 rpm for 5-6 hours, wash and centrifuge the obtained product, and place it in an oven at 50 Dry at ~60°C for 12-24 hours.

Further, in step (2), the attapulgite is attapulgite powder with a particle size of 200 to 320 mesh, that is, 75 to 45 μm.

Further, in step (2), the divalent manganese ion reducing agent is manganese sulfate or manganese chloride.

A kind of attapulgite/manganese dioxide/ferric oxide nanocomposite material. The attapulgite exhibits a nanorod-like structure, and the ferric oxide nanoparticles and manganese dioxide particles are attached to the surface of the attapulgite.

Further, the application of attapulgite/manganese dioxide/iron tetroxide nanocomposites in the degradation of organic wastewater.

Compared with the prior art, the present invention has the following beneficial effects:

1. As a carrier of nanocomposite materials, attapulgite can prevent the agglomeration of manganese dioxide particles, make manganese dioxide better dispersed, have a larger specific surface area, and have more active sites on the surface of the material, thereby improving catalytic activity. The addition of ferroferric oxide particles allows the nanocomposite to be quickly separated from the solution through simple magnetic recovery technology. Secondly, ferric oxide can also be used as a cocatalyst for manganese dioxide to improve its catalytic performance.

2. The attapulgite/manganese dioxide/ferric oxide nanocomposite material is prepared by hydrothermal method, which solves the problem of poor catalytic degradation of organic pollutants by single attapulgite or metal oxide.

3. The attapulgite/manganese dioxide/iron oxide nanocomposite material is prepared by hydrothermal method, which has the characteristics of high degradation efficiency of organic pollutants, wide pH range, easy recovery, recyclability, simple preparation process and low cost. It has broad application prospects in treating organic wastewater.

Description of the drawings

Figure 1 (a) and (b) are SEM photos of attapulgite and the attapulgite/manganese dioxide/ferroferrite nanocomposite prepared in the present invention respectively.

Figure 2 is the decolorization rate curve of acidic red (GR), carmine, Congo red, and methyl orange dye wastewater by the attapulgite/manganese dioxide/ferric oxide nanocomposite prepared in the present invention.

Figure 3 is a phenol degradation efficiency curve of attapulgite/manganese dioxide/ferric oxide nanocomposite prepared in the present invention.

Figure 4 shows the recycling and decolorization efficiency of acidic scarlet (GR) dye wastewater by the attapulgite/manganese dioxide/ferric oxide nanocomposite prepared in the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

(1) Weigh 0.278 g of ferrous sulfate heptahydrate and dissolve it in 100 mL of water, then add 1 g of polyvinylpyrrolidone (PVP), stir and heat to 80°C, and then add 3 mol/L to the solution of sodium hydroxide solution. After it forms a blue-green precipitate, continue heating and stirring for 2 hours until the precipitate in the solution changes from blue-green to black. Stop heating and cool to room temperature. Centrifuge to obtain the lower precipitate. After washing and drying , obtain iron ferric oxide powder, which is sealed and stored for later use.

(2) Add 3 g of attapulgite powder into a 150 mL ground-mouth conical flask, add 1.5 g of potassium permanganate, and 0.6 g of manganese sulfate monohydrate (in this example, the divalent manganese ion reducing agent is manganese sulfate , specifically manganese sulfate monohydrate, of course the divalent manganese ion reducing agent can also be manganese chloride, specifically manganese chloride tetrahydrate) and 0.8 g of ferric tetroxide powder obtained in step (1), add 100 mL pure water , oscillate in a water bath oscillator at 20°C and 200 rpm for 5 hours, ultrasonic, centrifuge, and wash. The product is placed in an oven, dried at 60°C for 12 hours, and ground to more than 200 mesh to obtain attapulgite/dioxide. Manganese/ferric oxide nanocomposites.

Select 50 mL each of 200 mg/L acidic scarlet (GR), carmine red, Congo red, and methyl orange dye wastewater and add it to a 100 mL centrifuge tube, and add 2 mL of PMS solution with a concentration of 30 mmol/L. Adjust the pH of the solution to 5, then add 0.05 g of the nanocomposite material of the present invention, oscillate in a constant temperature water bath oscillator at 25°C and 250 rpm for 6 hours, take samples at a predetermined time, and filter through a 0.45 μm microporous filter membrane after precipitation. The filtrate was used to determine the concentration of acidic scarlet (GR), carmine, Congo red, and methyl orange dye wastewater using spectrophotometry. The decolorization rates of acidic red (GR), carmine, Congo red, and methyl orange dye wastewater by the nanocomposite material of Example 1 are 100%, 99.67%, 92.99%, and 95.45% respectively.

In addition, a more preferred proportioning plan is that the dosage of potassium permanganate is 40-60% of the mass of attapulgite, the dosage of manganese sulfate monohydrate is 18-22% of the mass of attapulgite, and the dosage of manganese sulfate monohydrate is 18-22% of the mass of attapulgite. The concentration is 0.0319~0.0390mol/L.

Example 2

(1) Weigh 0.278 g of ferrous sulfate heptahydrate and dissolve it in 100 mL of water, then add 1 g of polyvinylpyrrolidone (PVP), stir and heat to 70°C, and then add 4 mol/L to the solution of sodium hydroxide solution. After it forms a blue-green precipitate, continue heating and stirring for 2 hours until the precipitate in the solution changes from blue-green to black. Stop heating and cool to room temperature. Centrifuge to obtain the lower precipitate. After washing and drying , obtain Fe3O4 powder. Sealed and stored for later use.

(2) Add 3 g of attapulgite powder to a 150 mL ground-mouth conical flask, add 1.2 g of potassium permanganate, 0.54 g of manganese sulfate monohydrate and 0.6 g of ferric tetroxide powder obtained in step (1), and add 100 mL of pure water was shaken in a water bath oscillator at 20°C and 200rpm for 6 hours. After centrifugation and washing, the obtained product was placed in an oven and dried at 50°C for 12 hours, and ground to more than 200 mesh to obtain attapulgite/bis Manganese oxide/ferric oxide nanocomposites. Select 50 mL each of 200 mg/L acidic scarlet (GR), carmine red, Congo red, and methyl orange dye wastewater and add it to a 100 mL centrifuge tube, and add 2 mL of PMS solution with a concentration of 30 mmol/L. Adjust the pH of the solution to 5, then add 0.05 g of the nanocomposite material of the present invention, oscillate in a constant temperature water bath oscillator at 25°C and 250 rpm for 6 hours, take samples at a predetermined time, and filter through a 0.45 μm microporous filter membrane after precipitation. The filtrate was used to determine the concentration of acidic scarlet (GR), carmine, Congo red, and methyl orange dye wastewater using spectrophotometry. The decolorization rates of the nanocomposite material in Example 2 for acidic red (GR), carmine, Congo red, and methyl orange dye wastewater are 99.59%, 99.16%, 92.41%, and 96.15% respectively.

Example 3

(1) Weigh 0.278 g of ferrous sulfate heptahydrate and dissolve it in 100 mL of water, then add 1 g of polyvinylpyrrolidone (PVP), stir and heat to 80°C, and then add 5 mol/L to the solution of sodium hydroxide solution. After it forms a blue-green precipitate, continue heating and stirring for 2 hours until the precipitate in the solution changes from blue-green to black. Stop heating and cool to room temperature. Centrifuge to obtain the lower precipitate. After washing and drying , obtain Fe3O4 powder. Sealed and stored for later use.

(2) Add 3 g of attapulgite powder into a 150 mL ground-mouth conical flask, add 1.8 g of potassium permanganate, 0.66 g of manganese sulfate monohydrate and 0.9 g of ferric tetroxide powder obtained in step (1), and add 100 mL of pure water was shaken in a water bath oscillator at 20°C and 200rpm for 5 hours. After centrifugation and washing, the obtained product was placed in an oven and dried at 60°C for 24 hours, and ground to more than 200 mesh to obtain attapulgite/bis Manganese oxide/iron oxide composite material.

Select 50 mL each of 200 mg/L acidic scarlet (GR), carmine, Congo red, and methyl orange dye wastewater, add 2 mL of PMS solution with a concentration of 30 mmol/L, adjust the solution pH=5, and then Add 0.05 g of the nanocomposite material of the present invention, oscillate in a constant temperature water bath oscillator at 25°C and 250 rpm for 6 hours, take samples at a predetermined time, and after precipitation, measure the filtrate filtered by a 0.45 μm microporous filter using spectrophotometry. Concentration of acidic scarlet (GR), carmine, Congo red, and methyl orange dye wastewater. The decolorization rates of the nanocomposite material in Example 3 for acidic red (GR), carmine, Congo red, and methyl orange dye wastewater are 99.66%, 99.95%, 93.94%, and 94.70% respectively.

Because the natural attapulgite powder appears white, the color of the attapulgite/manganese dioxide/ferric oxide nanocomposite material prepared by the present invention has changed significantly compared with the attapulgite powder, and the color of the obtained nanocomposite material is black. Figure 1 (a) and (b) are SEM photos of attapulgite and the attapulgite/manganese dioxide/ferroferrite nanocomposite prepared in the present invention respectively. It can be seen from the electron microscope photo (a) that natural attapulgite has a nanorod-like structure and a smooth surface without any load. It can be seen from the electron microscope photo (b) that manganese dioxide particles and ferric oxide particles are attached to the surface of attapulgite. Ferric oxide can solve the problem of difficult recovery of attapulgite in heterogeneous systems and improve its catalytic degradation of organic pollutants. As a carrier of nanocomposite materials, attapulgite improves the dispersion of manganese dioxide, prevents the agglomeration of manganese dioxide particles, and maintains the stability of the overall structure.

The catalytic degradation performance and recycling performance of attapulgite/manganese dioxide/ferric oxide composite materials for organic pollutants such as dyes and phenol were tested respectively.

1. Catalytic decolorization performance of dye wastewater

Figure 2 is the decolorization efficiency curve of acidic red (GR), carmine, Congo red, and methyl orange dye wastewater by the attapulgite/manganese dioxide/ferric oxide nanocomposite (Example 1) prepared by the present invention. As can be seen from Figure 2, the material's degradation of acidic scarlet (GR), carmine, and methyl orange dye wastewater reaches equilibrium in 4 hours, and the degradation of Congo red dye wastewater reaches equilibrium in 6 hours. The decolorization rates of acidic red (GR), carmine, Congo red, and methyl orange dye wastewater by this nanocomposite can reach 100%, 99.67%, 92.99%, and 95.45% respectively. This result shows that the prepared attapulgite/manganese dioxide/ferric oxide composite material can achieve efficient decolorization of dyes.

In the existing technology, Huang et al. (2020) prepared nanorod α-MnO ₂ loaded palygorskite through hydrothermal method, and activated PMS to degrade rhodamine B. The results show that under optimal conditions (catalyst dosage 0.10 g/L, PMS = 0.10g/L, pH (5.5 ± 0.1), temperature 20 °C), 20 mg/L rhodamine B can react within 180 minutes. Almost completely degraded. Lu Yanxia et al. (2020) used magnetic CuFe ₂ O ₄ /palygorskite (CuFe ₂ O ₄ /Pal) to activate PMS to degrade rhodamine B. Under the optimal reaction conditions (the initial concentration of rhodamine B solution was 10 mg/L, The PMS concentration is 0.1 g/L, the initial pH value is 3, and the CuFe ₂ O ₄ /Pal dosage is 0.3 g/L). After 120 minutes of reaction, the rhodamine B degradation efficiency is 99.99%. Li Yancheng et al. (2021) used a two-step hydrothermal method to prepare a MnO ₂ /CoFe ₂ O ₄ magnetic composite catalyst. The results showed that the dosage of the MnO ₂ /CoFe ₂ O ₄ composite material was 0.3 g/L and the PMS concentration was 1.25 mmol/L, pH 3, the decolorization rate of the acidic red 3R solution with an initial concentration of 50 mg/L after reaction for 10 minutes was 93.5%. Compared with the above materials, the composite material prepared by the present invention has the advantages of wide pH application range and good decolorization effect.

2. Degradation performance of phenol

Select 60 mL of 10 mg/L phenol solution, add 1 mL of PMS solution with a concentration of 40 mmol/L, adjust the pH of the solution to 5, and then add 0.05 g of the nanocomposite material of the present invention at 25 ° C and 250 rpm. Shake in a constant-temperature water bath oscillator for 5 h, take samples at predetermined times, and after precipitation, measure the phenol concentration of the filtrate filtered through a 0.45 μm microporous membrane using spectrophotometry. Figure 3 is the phenol degradation efficiency curve of the attapulgite/manganese dioxide/ferric oxide nanocomposite (Example 1) prepared by the present invention. As can be seen from Figure 3, the nanocomposite catalyzed the degradation of phenol by PMS, reaching equilibrium in 2 h, and the degradation efficiency could reach 97.89%. This result shows that the prepared attapulgite/manganese dioxide/ferric oxide nanocomposite can be used as a PMS catalyst to achieve efficient removal of phenol.

3. Recycling performance of nanocomposites

Take 50 mL of acidic scarlet (GR) dye wastewater with a concentration of 200 mg/L, add 2 mL of PMS solution with a concentration of 30 mmol/L, adjust the pH=5, and then add the nanocomposite material of the present invention, at 25 ° C and 250 rpm Shake in a constant-temperature water bath oscillator for 6 hours. After precipitation, filter with a 0.45 μm microporous filter. The filtrate is used to measure the concentration of acidic scarlet (GR) dye wastewater using spectrophotometry. After magnetic separation (collecting attapulgite/manganese dioxide/ferric oxide nanocomposite, washing and drying), it is again used to catalyze the degradation of acidic scarlet (GR) dye wastewater. Figure 4 shows the cyclic decolorization efficiency of acidic scarlet (GR) dye wastewater by the attapulgite/manganese dioxide/ferric oxide nanocomposite prepared in the present invention (Example 1). As can be seen from Figure 4, the decolorization rate of acidic scarlet (GR) dye wastewater after catalytic degradation of acidic scarlet (GR) dye wastewater for 5 times by nanocomposite circulation was 90.74%. This result shows that the attapulgite/manganese dioxide/ferric oxide nanocomposite material obtained by the present invention has good recycling performance.

Pan Liang et al. (2020) prepared a Fe ₃ O ₄ /RGO magnetic composite material as a catalyst to degrade methyl orange. After 5 cycles of the catalyst, a methyl orange removal efficiency of 70.2% was obtained. Shi Zhou et al. (2017) successfully prepared the magnetic ternary material CoFeNi-LDH through chemical co-precipitation method and activated PMS to degrade the azo dye Congo red. After three cycles of regeneration, the catalyst has a decolorization rate of Congo red of 88%. Compared with the above materials, the present invention has good reusability and is easy to recycle.

The above are only preferred embodiments of the present invention and do not limit the technical scope of the present invention in any way. Therefore, any changes or modifications made in accordance with the claims and description of the present invention shall be covered by the patent of the present invention. within the range.

Claims (7)

1. The application of attapulgite/manganese dioxide/ferric oxide nanocomposite material in degrading organic pollutants, which is characterized by: a preparation method of the attapulgite/manganese dioxide/ferric oxide nanocomposite material It includes the following steps: (1) Weigh a certain amount of ferrous sulfate heptahydrate, dissolve it in water, then add polyvinylpyrrolidone, stir and heat, and then add a concentration of 3 mol/L to 5 mol/L to the solution. After the sodium hydroxide solution forms a blue-green precipitate, continue heating and stirring. After the blue-green precipitate turns black, stop heating and cool to room temperature. Centrifuge, wash, and dry to obtain ferric oxide powder; (2) Use attapulgite as raw material, add potassium permanganate, divalent manganese ion reducing agent and ferroferric oxide powder obtained in step (1), add pure water, oscillate in a water bath oscillator, ultrasonic, centrifuge, and clean. Dry and grind to more than 200 mesh to obtain attapulgite/manganese dioxide/ferric oxide nanocomposite material; wherein: the dosage of potassium permanganate is 40-60% of the mass of attapulgite, and the attapulgite powder and attapulgite are The mass ratio of rodstone is 1:3.3~1:5. 2. The application according to claim 1, characterized in that in step (1), the heating temperature is 70-80°C, and the heating and stirring time is continued for 1.5-2 h. 3. The application according to claim 1, characterized in that in step (2), the concentration of the divalent manganese ion reducing agent is 0.0319~0.0390 mol/L. 4. The application according to claim 1, characterized in that: in step (2), the water bath and drying conditions are: oscillating in a water bath oscillator at 20 to 25°C and 200 to 250 rpm for 5 to 6 hours. , ultrasonic, centrifuged, washed, placed in an oven and dried at 50-60°C for 12-24 hours. 5. The application according to claim 1, characterized in that in step (2), attapulgite is attapulgite powder with a particle size of 200 to 320 mesh. 6. The application according to claim 1, characterized in that in step (2), the divalent manganese ion reducing agent is manganese sulfate or manganese chloride. 7. The application according to claim 1, characterized in that attapulgite exhibits a nanorod-like structure, and Fe3O4 nanoparticles and manganese dioxide particles are attached to the surface of attapulgite.