Preparation method and application of magnetic montmorillonite modified sludge-based hydrothermal carbon

Abstract

The invention discloses a preparation method and application of magnetic montmorillonite modified sludge-based hydrothermal carbon, and belongs to the technical field of sludge carbonization. The method comprises the following steps: (1) mixing sludge, montmorillonite and ethylene glycol to obtain montmorillonite sludge dispersion liquid; (2) adding ferric trichloride, lauryl sodium sulfate and anhydrous sodium acetate into the montmorillonite sludge dispersion liquid to obtain montmorillonite sludge mixed liquid; (3) carrying out hydrothermal reaction on the montmorillonite sludge mixed solution, and cooling after the reaction is completed to obtain a hydrothermal product; and (4) respectively washing the hydrothermal product with deionized water and absolute ethyl alcohol, carrying out suction filtration, drying and grinding to obtain the magnetic montmorillonite modified sludge-based hydrothermal carbon. The montmorillonite modified sludge-based hydrothermal carbon is prepared by taking sludge as a raw material, modifying and dispersing the sludge in ethylene glycol through montmorillonite, then carrying out hydrothermal reaction, washing, carrying out suction filtration and drying, and the hydrothermal carbon has an excellent pore structure and adsorption performance and is particularly suitable for adsorbing and removing methylene blue in a water body.

Description

Technical Field

[0001] The invention relates to the technical field of sludge carbonization, and in particular to a preparation method and application of magnetic montmorillonite modified sludge-based hydrothermal carbon. Background Art

[0002] With the continuous acceleration of industrialization and urbanization, the amount of municipal sludge treatment has increased year by year. Sludge contains a large number of pathogens, organic pollutants, heavy metals and other harmful substances. If municipal sludge that has not been treated in a standardized manner is directly discharged, it will cause serious environmental pollution problems. At present, sludge treatment methods such as composting, incineration, and landfill will also have an impact on the environment and cause waste of resources. Therefore, in order to achieve economic benefits and alleviate environmental pressure, it is necessary to propose a sludge treatment method that meets all needs, is safe and efficient.

[0003] Methylene blue is a cationic dye and a water-soluble dye with high chroma. It is visible and stable in water at room temperature. Methylene blue is a representative harmful substance in printing and dyeing wastewater. Its molecular structure is complex and stable, and it is not easy to degrade. Direct discharge into rivers and lakes will pose a major threat to the ecological environment and human health. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method and application of magnetic montmorillonite modified sludge-based hydrothermal carbon.

[0005] The technical solution adopted by the present invention is:

[0006] A method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon comprises the following steps:

[0007] (1) mixing sludge, montmorillonite and ethylene glycol to obtain a montmorillonite sludge dispersion;

[0008] (2) adding ferric chloride, sodium lauryl sulfate and anhydrous sodium acetate to the montmorillonite sludge dispersion to obtain a montmorillonite sludge mixed solution;

[0009] (3) subjecting the montmorillonite sludge mixed solution to a hydrothermal reaction, and cooling the mixture after the reaction is completed to obtain a hydrothermal product;

[0010] (4) The hydrothermal product was washed with deionized water and anhydrous ethanol respectively, filtered, and then dried and ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0011] Preferably, in step (1), the mass ratio of montmorillonite to sludge is 1:1 to 1:7.

[0012] Preferably, in step (1), the mass fraction of montmorillonite and sludge in the montmorillonite sludge dispersion is 8% to 15%.

[0013] Preferably, in step (1), the sludge is mechanically dehydrated sludge from a sewage treatment plant, and the sludge has a moisture content of 75%-80%.

[0014] Preferably, in step (1) and step (2), stirring is required, and the stirring rate is controlled to be 600-800 r / min and the stirring time is 30-60 min.

[0015] Preferably, in step (2), the mass ratio of ferric chloride, sodium dodecyl sulfate and anhydrous sodium acetate is 1:0.5-2:0.5-2; the mass ratio of montmorillonite to ferric chloride is 1:0.5-2.

[0016] Preferably, in step (3), the hydrothermal reaction temperature is 180 to 220° C., and the hydrothermal reaction time is 8 to 10 hours.

[0017] Preferably, in step (3): the montmorillonite sludge mixed liquor is placed in a polytetrafluoroethylene-lined stainless steel reactor, the reactor is placed in an electric constant temperature forced air drying oven for hydroheating, the hydrothermal temperature is raised from room temperature to 220° C., and maintained at this temperature for 10 hours.

[0018] Preferably, in step (4): the hydrothermal product is washed three times with deionized water and anhydrous ethanol respectively to ensure that impurities can be completely washed away; after filtration, it is dried in an oven at a constant temperature of 80°C-95°C for 10-12 hours.

[0019] The magnetic montmorillonite-modified sludge-based hydrothermal carbon prepared by the above method is used to remove methylene blue from water.

[0020] The beneficial technical effects of the present invention are:

[0021] (1) The present invention uses sludge as a raw material, modifies and disperses it in ethylene glycol through montmorillonite, then performs a hydrothermal reaction, and then washes, filters, and dries to obtain montmorillonite-modified sludge-based hydrothermal carbon. The hydrothermal carbon has excellent pore structure and adsorption performance, and is particularly suitable for the adsorption and removal of methylene blue in water.

[0022] (2) The present invention uses sludge and montmorillonite as raw materials to produce hydrothermal charcoal, which can be used to remove methylene blue in water bodies, thereby achieving the effect of treating waste with waste, with significant economic and environmental benefits. Moreover, the present invention can obtain hydrothermal charcoal with excellent adsorption performance by dispersing and modifying montmorillonite in combination with a hydrothermal method. Compared with other treatment methods such as incineration and high-temperature pyrolysis, the required calorific value is low, the conditions are easy to achieve, and it is more energy-saving. Specifically, the reaction temperature of the hydrothermal method of the present invention is between 180 and 220°C, and the pyrolysis temperature must reach above 500 to 600°C. In addition, the present invention can directly use sludge with a high water content discharged from the factory, without the need to dry and grind the sludge in advance, and the energy-saving effect is obvious.

[0023] (3) Before the hydrothermal reaction, the present invention also adds ferric chloride, sodium dodecyl sulfate and the like in appropriate amounts and proportions, so that the hydrothermal carbon finally obtained can ensure a good adsorption effect, has magnetism, can be recycled, has strong practicality, and is convenient for market promotion and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic flow chart of the method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon. DETAILED DESCRIPTION

[0025] The present invention uses sludge as raw material, disperses and modifies montmorillonite, and generates hydrothermal carbon under hydrothermal conditions. The method is a new type of economical and environmentally friendly sludge treatment method. The obtained montmorillonite-modified sludge-based hydrothermal carbon can be used as a good adsorbent to adsorb organic pollutants such as methylene blue. Moreover, compared with other treatment methods such as incineration and high-temperature pyrolysis, hydrothermal carbonization of montmorillonite-modified sludge is an environmentally friendly sludge treatment method. The method requires a low calorific value and the conditions are easy to achieve. On the premise of ensuring that the magnetic montmorillonite-modified sludge-based hydrothermal carbon finally obtained has a good removal effect on methylene blue, it is more economical and energy-saving.

[0026] The present invention will be further described below in conjunction with specific embodiments:

[0027] Example 1

[0028] 0.5g of montmorillonite and 1.5g of sludge were placed in a beaker, and 18g of ethylene glycol was added. The mixture was stirred at a rate of 600r / min for 30min and mixed evenly to obtain a montmorillonite sludge dispersion. 0.5g of ferric chloride, 0.5g of sodium dodecyl sulfate and 0.5g of anhydrous sodium acetate were added to the montmorillonite sludge dispersion, and the mixture was stirred at a rate of 600r / min for 30min to obtain a montmorillonite sludge mixed solution. The montmorillonite sludge mixed solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an electric constant temperature blast drying oven for hydrothermal heating. The hydrothermal temperature was raised from room temperature (about 25°C) to 220°C, and maintained at this temperature for 10 hours to ensure sufficient hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was cooled to obtain a hydrothermal product. The hydrothermal product was washed three times with deionized water and anhydrous ethanol respectively to ensure that the impurities were completely washed and removed, then filtered, and then dried in an oven at 95°C for 12 hours, and then ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0029] Example 2

[0030] 0.5g of montmorillonite and 2.5g of sludge were placed in a beaker, and 27g of ethylene glycol was added. The mixture was stirred at a rate of 600r / min for 30min and mixed evenly to obtain a montmorillonite sludge dispersion. 0.5g of ferric chloride, 0.5g of sodium dodecyl sulfate and 0.5g of anhydrous sodium acetate were added to the montmorillonite sludge dispersion, and the mixture was stirred at a rate of 600r / min for 30min to obtain a montmorillonite sludge mixed solution. The montmorillonite sludge mixed solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an electric constant temperature blast drying oven for hydrothermal heating. The hydrothermal temperature was raised from room temperature (about 25°C) to 220°C, and maintained at this temperature for 10 hours to ensure sufficient hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was cooled to obtain a hydrothermal product. The hydrothermal product was washed three times with deionized water and anhydrous ethanol respectively to ensure that the impurities were completely washed and removed, then filtered, and then dried in an oven at 95°C for 12 hours, and then ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0031] Example 3

[0032] 0.5g of montmorillonite and 3.5g of sludge were placed in a beaker, and 36g of ethylene glycol was added. The mixture was stirred at a rate of 600r / min for 30min and mixed evenly to obtain a montmorillonite sludge dispersion. 0.5g of ferric chloride, 0.5g of sodium dodecyl sulfate and 0.5g of anhydrous sodium acetate were added to the montmorillonite sludge dispersion, and the mixture was stirred at a rate of 600r / min for 30min to obtain a montmorillonite sludge mixed solution. The montmorillonite sludge mixed solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an electric constant temperature blast drying oven for hydrothermal heating. The hydrothermal temperature was raised from room temperature (about 25°C) to 220°C, and maintained at this temperature for 10 hours to ensure sufficient hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was cooled to obtain a hydrothermal product. The hydrothermal product was washed three times with deionized water and anhydrous ethanol respectively to ensure that the impurities were completely washed and removed, then filtered, and then dried in an oven at 95°C for 12 hours, and then ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0033] Example 4

[0034] 0.5g of montmorillonite and 0.5g of sludge were placed in a beaker, and 10g of ethylene glycol was added. The mixture was stirred at a rate of 600r / min for 30min and mixed evenly to obtain a montmorillonite sludge dispersion. 0.5g of ferric chloride, 0.5g of sodium dodecyl sulfate and 0.5g of anhydrous sodium acetate were added to the montmorillonite sludge dispersion, and the mixture was stirred at a rate of 600r / min for 30min to obtain a montmorillonite sludge mixed solution. The montmorillonite sludge mixed solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an electric constant temperature blast drying oven for hydrothermal heating. The hydrothermal temperature was raised from room temperature (about 25°C) to 200°C, and maintained at this temperature for 10 hours to ensure sufficient hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was cooled to obtain a hydrothermal product. The hydrothermal product was washed three times with deionized water and anhydrous ethanol respectively to ensure that the impurities were completely washed and removed, then filtered, and then dried in an oven at 95°C for 12 hours, and then ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0035] Example 5

[0036] 0.5g of montmorillonite and 1g of sludge were placed in a beaker, and 9g of ethylene glycol was added. The mixture was stirred at a rate of 800r / min for 50min and mixed evenly to obtain a montmorillonite sludge dispersion. 1g of ferric chloride, 1g of sodium dodecyl sulfate and 1g of anhydrous sodium acetate were added to the montmorillonite sludge dispersion, and stirred at a rate of 600r / min for 30min to obtain a montmorillonite sludge mixed solution. The montmorillonite sludge mixed solution was placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor was placed in an electric constant temperature blast drying oven for hydrothermal heating. The hydrothermal temperature was raised from room temperature (about 25°C) to 180°C, and maintained at this temperature for 8 hours to ensure sufficient hydrothermal reaction. After the hydrothermal reaction was completed, the mixture was cooled to obtain a hydrothermal product. The hydrothermal product was washed three times with deionized water and anhydrous ethanol respectively to ensure that the impurities were completely washed and removed, then filtered, and then dried in an oven at 95°C for 12 hours, and then ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

[0037] The magnetic montmorillonite-modified sludge-based hydrothermal carbon prepared in the embodiment of the present invention was tested for magnetic properties and adsorption properties, as follows:

[0038] (1) Magnetic test:

[0039] The magnetic montmorillonite-modified sludge-based hydrothermal charcoal prepared in Example 1 of the present invention was placed in a beaker, and then a magnet was placed on the outer wall area of ​​one side of the beaker. It can be seen that the hydrothermal charcoal moved toward the magnet and adhered to the inner wall of the glass beaker, thereby verifying that the hydrothermal charcoal prepared in the present invention has magnetism.

[0040] (2) Adsorption performance test:

[0041] Prepare 100 mg / L methylene blue solution, take 50 ml and put it into conical flask No. 1, conical flask No. 2, conical flask No. 3 and conical flask No. 4 respectively, add the magnetic montmorillonite modified sludge-based hydrothermal charcoal prepared in Example 1 into conical flask No. 1, add the magnetic montmorillonite modified sludge-based hydrothermal charcoal prepared in Example 2 into conical flask No. 2, and add the magnetic montmorillonite modified sludge-based hydrothermal charcoal prepared in Example 3 into conical flask No. 3. No hydrothermal charcoal is added to conical flask No. 4. Shake the conical flask in a water bath at 25°C at a speed of 150r / min for two hours, then filter the solution in the conical flask and put it into colorimetric tube No. 1, colorimetric tube No. 2, colorimetric tube No. 3 and colorimetric tube No. 4 respectively. It was observed that the 100 mg / L methylene blue aqueous solution itself was a dark blue opaque solution, which turned into light blue after adsorption by the hydrothermal carbon prepared in Example 2, and also turned into light blue after adsorption by the hydrothermal carbon prepared in Example 3, but the color was lighter. After adsorption by the hydrothermal carbon prepared in Example 1, the solution was almost colorless and transparent.

[0042] In addition, the removal effect of methylene blue (MB) on the magnetic montmorillonite-modified sludge-based hydrothermal carbons prepared in Examples 1 to 3 was measured and compared with high-temperature dried sludge + coconut shell raw materials. The results are shown in Table 1 below.

[0043] Table 1

[0044]

[0045] It can be seen from Table 1 that the hydrothermal carbon prepared by the method of the present invention has a good adsorption effect on the methylene blue solution, and the adsorption rate can reach more than 90%, especially the hydrothermal carbon prepared in Example 1, the adsorption efficiency is as high as 97.25%, and the adsorption performance is excellent. Moreover, the reaction temperature of the method of the present invention is only 220°C, which is significantly lower than that of high-temperature pyrolysis of 600°C or 700°C, and there is no need to dry and grind the sludge in advance, which is more energy-saving.

[0046] The parts not mentioned in the above methods can be realized by adopting or drawing on existing technologies.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon, characterized in that The following steps are involved: (1) mixing sludge, montmorillonite and ethylene glycol to obtain a montmorillonite sludge dispersion; (2) adding ferric chloride, sodium lauryl sulfate and anhydrous sodium acetate to the montmorillonite sludge dispersion to obtain a montmorillonite sludge mixed solution; (3) subjecting the montmorillonite sludge mixed solution to a hydrothermal reaction, and cooling the mixture after the reaction is completed to obtain a hydrothermal product; (4) The hydrothermal product was washed with deionized water and anhydrous ethanol respectively, filtered, and then dried and ground to obtain magnetic montmorillonite-modified sludge-based hydrothermal carbon.

2. The method for preparing a magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (1), the mass ratio of montmorillonite to sludge is 1:1 to 1:

7.

3. The method for preparing a magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (1), the mass fraction of montmorillonite and sludge in the montmorillonite sludge dispersion is 8% to 15%.

4. The method for preparing a magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (1), the sludge is mechanically dehydrated sludge from a sewage treatment plant, and the moisture content of the sludge is 75%-80%.

5. The method for preparing a magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (1) and step (2), stirring is required, and the stirring rate is controlled to be 600-800 r / min and the stirring time is 30-60 min.

6. The method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (2), the mass ratio of ferric chloride, sodium dodecyl sulfate and anhydrous sodium acetate is 1:0.5-2:0.5-2; the mass ratio of montmorillonite to ferric chloride is 1:0.5-2.

7. The method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (3), the hydrothermal reaction temperature is 180 to 220° C., and the hydrothermal reaction time is 8 to 10 hours.

8. The method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (3): the montmorillonite sludge mixed liquid is placed in a polytetrafluoroethylene-lined stainless steel reactor, and the reactor is placed in an electric constant temperature forced air drying oven for hydroheating, the hydrothermal temperature is raised from room temperature to 220° C., and maintained at this temperature for 10 hours.

9. The method for preparing magnetic montmorillonite-modified sludge-based hydrothermal carbon according to claim 1, characterized in that: In step (4): the hydrothermal product is washed three times with deionized water and anhydrous ethanol respectively to ensure that impurities can be completely washed away; after filtration, it is dried in an oven at a constant temperature of 80°C-95°C for 10-12 hours.

10. Use of the magnetic montmorillonite-modified sludge-based hydrothermal carbon prepared by any method of claims 1 to 9 in removing methylene blue from water.

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