Iron modified coconut shell biochar as well as preparation method and application thereof
By preparing iron-modified coconut shell biochar, using its iron-loaded properties, the problem of poor dehydration effect in the prior art was solved, and efficient dehydration and low moisture content of the sludge were achieved.
Patent Information
- Application Number
- CN202510674440.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-23
- Publication Date
- 2025-07-11
AI Technical Summary
The prior art lacks efficient sludge conditioning agents, and it is difficult to promote the improvement of the dehydration effect of sludge by simply using skeleton materials.
Iron-modified coconut shell biochar is used to prepare iron-loaded biochar by pyrolysis, pickling and iron chloride treatment. Combining its physical and chemical characteristics, it serves as a skeleton support and chemical conditioning agent to improve the dehydration performance of the sludge.
During the dehydration process of sludge, iron-modified coconut biochar enhances the flocculation effect, improves the sludge filtration capacity and mechanical strength, and reduces the sludge moisture content.
Smart Images
Figure CN120285952A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of sludge treatment, and particularly relates to an iron-modified coconut shell biochar, a preparation method thereof, and an application thereof. Background Art
[0002] With the acceleration of the urbanization process in China, the improvement of sewage treatment facilities, and the rapid growth of sewage treatment capacity, the amount of sludge generated has increased sharply. Research shows that improving the porosity of the filter cake and reducing its compressibility are the keys to achieving deep sludge dewatering. Based on this understanding, researchers have proposed a technical idea of using physical conditioning agents to construct a framework. Such solid filter aid materials improve the sludge dewatering performance through physical actions. Their main function is to reduce the compressibility of the sludge, enhance the mechanical strength and water permeability of the filter cake during the compression process. Therefore, they are also called skeleton filter aids or skeleton construction materials.
[0003] However, it has been found in actual engineering applications that simply using skeleton materials to condition sludge is difficult to promote the improvement of sludge dewatering effect. Further research has found that modifying the skeleton materials can endow them with multiple chemical properties, enabling them to not only play a physical support function but also have the role of a chemical conditioner. This multifunctional property with both physical and chemical dual effects is expected to achieve efficient conditioning of sludge by means of the synergistic effect of the modified skeleton materials. Summary of the Invention
[0004] In order to solve the above technical problems, the object of the present invention is to provide an iron-modified coconut shell biochar, a preparation method thereof, and an application thereof to solve the problem of the lack of efficient sludge conditioners in the prior art.
[0005] The technical solution for the present invention to solve the above technical problems is as follows: A preparation method of an iron-modified coconut shell biochar is provided, including the following steps: (1) Pyrolyzing and carbonizing coconut shell powder, and after cooling, grinding, sieving, washing, and drying in sequence to obtain raw coconut shell biochar; (2) Immersing the raw coconut shell biochar obtained in step (1) in a hydrochloric acid solution, stirring, washing, and suction filtering to obtain a precipitate; (3) Immersing the precipitate obtained in step (2) in a ferric chloride solution, stirring, ultrasonicating, washing, suction filtering, drying, and sieving to obtain the iron-modified coconut shell biochar.
[0006] Based on the above technical solution, the present invention can be further improved as follows: Further, in step (1), the coconut shell powder is obtained by the following method: washing, drying, and crushing the coconut shell to obtain coconut shell powder.
[0007] Further, drying is carried out at 100 - 110 °C.
[0008] Further, in step (1), pyrolytic carbonization is carried out under a nitrogen atmosphere.
[0009] Further, in step (1), pyrolytic carbonization is carried out at 700 - 900 °C for 50 - 80 min.
[0010] Further, in step (1), the heating rate during pyrolytic carbonization is 8 - 12 °C / min.
[0011] Further, in step (1), the heating rate during pyrolytic carbonization is 10 °C / min.
[0012] Further, in step (1), it is sieved through an 80 - mesh sieve and a 100 - mesh sieve in sequence.
[0013] Further, in step (1), the particle size of the original coconut shell biochar is 0.15 - 0.178 μm.
[0014] Further, in step (2), the concentration of the hydrochloric acid solution is 1 - 1.5 mol / L.
[0015] The beneficial effect of adopting the above - mentioned further technical solution is that pickling is to remove surface impurities.
[0016] Further, in step (2), the mass - to - volume ratio of the original coconut shell biochar to the hydrochloric acid solution is 1 g: 45 - 55 mL.
[0017] Further, in step (2), the mass - to - volume ratio of the original coconut shell biochar to the hydrochloric acid solution is 1 g: 50 mL.
[0018] Further, in step (2), the stirring time is 10 - 15 h.
[0019] Further, in step (2), the stirring time is 12 h.
[0020] Further, in step (2), deionized water is used for washing.
[0021] Further, in step (3), the concentration of the ferric chloride solution is 2 - 3 mol / L.
[0022] Further, in step (3), the mass - to - volume ratio of the precipitate to the ferric chloride solution is 1 g: 90 - 110 mL.
[0023] Further, in step (3), the mass - to - volume ratio of the precipitate to the ferric chloride solution is 1 g: 100 mL.
[0024] Further, in step (3), the stirring time is 1.5 - 2.5 h.
[0025] Further, in step (3), the stirring time is 2 h.
[0026] Furthermore, in step (3), the ferric chloride solution is prepared by the following method: Dissolve ferric chloride hexahydrate in deionized water to obtain a ferric chloride solution.
[0027] Furthermore, in step (3), perform ultrasonic treatment for 0.4 - 0.6 h under the condition of 30 - 40 °C.
[0028] Furthermore, in step (3), perform ultrasonic treatment for 0.5 h under the condition of 35 °C.
[0029] Furthermore, in step (3), wash with deionized water until neutral.
[0030] Furthermore, in step (3), dry at 100 - 110 °C for 20 - 25 h.
[0031] Furthermore, in step (3), dry at 105 °C for 24 h.
[0032] Furthermore, in step (3), pass through an 80 - mesh sieve and a 100 - mesh sieve in sequence.
[0033] Furthermore, in step (3), the particle size of the iron - modified coconut shell biochar is 0.15 - 0.178 μm.
[0034] The present invention also provides the iron - modified coconut shell biochar prepared by the above method.
[0035] The present invention also provides the application of the above iron - modified coconut shell biochar in sludge dewatering.
[0036] The present invention has the following beneficial effects: 1. Aiming at the problem that biochar alone is difficult to improve the sludge dewatering performance, the present invention uses ferric chloride to modify coconut shell biochar, load iron on the coconut shell charcoal, so that it plays a role of the skeleton support of biochar and has the function of a certain chemical conditioner during the sludge dewatering process, thereby improving the sludge dewatering performance.
[0037] 2. The iron - modified coconut shell biochar of the present invention plays a certain flocculation role during the sludge conditioning process, increasing the sludge floc particle size. At the same time, it can also improve the compressibility of the sludge, so that the sludge cake can still maintain permeability under a large mechanical pressure, which helps to improve the sludge filtration ability.
[0038] 3. The iron - modified coconut shell biochar conditioning sludge dewatering proposed by the present invention has achieved better results in reducing the sludge moisture content compared with the direct dewatering of the original sludge and the sludge dewatering conditioned by the original coconut shell biochar. Description of the Drawings
[0039] Figure 1 It is the elemental content diagram of the EDS characterization of the original coconut shell charcoal biochar in Comparative Example 1; Figure 2 Element content diagram of EDS characterization of iron-modified coconut shell biochar in Example 1; Figure 3 Mapping diagram of the original coconut shell biochar in Comparative Example 1; Figure 4 Mapping diagram of iron-modified coconut shell biochar in Example 1. Detailed implementation manners
[0040] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention. For those conditions not specified in the examples, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.
[0041] Example 1: An iron-modified coconut shell biochar, and its preparation method includes the following steps: (1) Clean the raw coconut shells, dry them in an oven at 105°C, crush them to obtain coconut shell powder, spread it flat in a porcelain boat and place it in a tube furnace. After introducing nitrogen, raise the temperature in the tube furnace to 800°C at a rate of 10°C / min, keep it warm for 60 min for pyrolytic carbonization, continue to cool it to room temperature in nitrogen, then take out the cooled sample for grinding, pass through an 80-mesh sieve and a 100-mesh sieve in sequence, wash off the surface ash with deionized water and then dry it to constant weight to obtain the original coconut shell biochar (particle size is 0.15 - 0.178 μm, CSB); (2) Immerse 10 g of the original coconut shell biochar prepared in step (1) in 500 mL of hydrochloric acid solution (concentration is 1 mol / L), continuously stir it with a magnetic stirrer at room temperature for 12 h, wash the solution with deionized water until it is neutral and then vacuum filter it to obtain a precipitate; (3) Immerse 1 g of the precipitate prepared in step (2) in 100 mL of ferric chloride solution (concentration is 3 mol / L), stir it with a magnetic stirrer at room temperature for 2 h, then place it in an ultrasonic cleaner at 35°C for ultrasonic treatment for 0.5 h, wash the solution with deionized water until it is neutral and then vacuum filter it, take the solid precipitate, dry it in an oven at 105°C for 24 h, pass through an 80-mesh sieve and a 100-mesh sieve in sequence to obtain the iron-modified coconut shell biochar (particle size is 0.15 - 0.178 μm, MCSB-FeCl3).
[0042] Example 2: An iron-modified coconut shell biochar, and its preparation method includes the following steps: (1) Clean the raw coconut shells, dry them in an oven at 100 °C, crush them to obtain coconut shell powder, spread it evenly in a porcelain boat and place it in a tubular furnace. After introducing nitrogen, raise the temperature in the tubular furnace to 700 °C at a rate of 8 °C / min, keep it warm for 80 min for pyrolysis carbonization. Then continue to cool it to room temperature in nitrogen, take out the cooled sample and grind it. Pass it through an 80-mesh sieve and a 100-mesh sieve in sequence, wash off the surface ash with deionized water and then dry it to constant weight to obtain the original coconut shell biochar (particle size 0.15 - 0.178 μm, CSB); (2) Immerse 10 g of the original coconut shell biochar prepared in step (1) in 450 mL of hydrochloric acid solution (concentration 1.5 mol / L), and continuously stir it with a magnetic stirrer at room temperature for 10 h. Rinse the solution with deionized water until it is neutral and then vacuum filter it to obtain a precipitate; (3) Immerse 1 g of the precipitate prepared in step (2) in 90 mL of ferric chloride solution (concentration 2 mol / L), stir it with a magnetic stirrer at room temperature for 1.5 h, then place it in an ultrasonic cleaner at 30 °C and ultrasonicate for 0.6 h. Rinse the solution with deionized water until it is neutral and then vacuum filter it. Take the solid precipitate, dry it in an oven at 100 °C for 20 h, pass it through an 80-mesh sieve and a 100-mesh sieve in sequence to obtain iron-modified coconut shell biochar (particle size 0.15 - 0.178 μm, MCSB-FeCl3).
[0043] Example 3: An iron-modified coconut shell biochar, and its preparation method includes the following steps: (1) Clean the raw coconut shells, dry them in an oven at 110 °C, crush them to obtain coconut shell powder, spread it evenly in a porcelain boat and place it in a tubular furnace. After introducing nitrogen, raise the temperature in the tubular furnace to 900 °C at a rate of 12 °C / min, keep it warm for 50 min for pyrolysis carbonization. Then continue to cool it to room temperature in nitrogen, take out the cooled sample and grind it. Pass it through an 80-mesh sieve and a 100-mesh sieve in sequence, wash off the surface ash with deionized water and then dry it to constant weight to obtain the original coconut shell biochar (particle size 0.15 - 0.178 μm, CSB); (2) Immerse 10 g of the original coconut shell biochar prepared in step (1) in 550 mL of hydrochloric acid solution (concentration 1.2 mol / L), and continuously stir it with a magnetic stirrer at room temperature for 15 h. Rinse the solution with deionized water until it is neutral and then vacuum filter it to obtain a precipitate; (3) Soak 1 g of the precipitate obtained in step (2) in 110 mL of ferric chloride solution (concentration: 2.5 mol / L), stir it with a magnetic stirrer for 2.5 h at room temperature, then place it in an ultrasonic cleaner at 40 °C and ultrasonicate for 0.4 h. Rinse the solution with deionized water until neutral, then perform vacuum filtration. Take the solid precipitate, dry it in an oven at 110 °C for 20 h, and pass it through an 80-mesh sieve and a 100-mesh sieve in sequence to obtain iron-modified coconut shell biochar (particle size: 0.15 - 0.178 μm, MCSB-FeCl3).
[0044] Comparative Example 1: A kind of original coconut shell biochar (CSB), its preparation method includes the following steps: Do not include steps (2)-(3), and the rest is the same as in Example 1.
[0045] Test Example I. Respectively perform X-ray photoelectron spectroscopy (EDS) detection on the iron-modified coconut shell biochar prepared in Example 1 and the original coconut shell biochar prepared in Comparative Example 1. The results are shown in Figure 1-2 .
[0046] It can be seen from Figure 1-2 that the contents of C and Fe elements are relatively the highest. Among them, the mass fraction of Fe element on the surface of ferric chloride-modified coconut shell biochar is 25.39%, while the mass fraction of Fe element on the surface of the original coconut shell biochar is only 0.3%, and the former is 84.63 times that of the latter.
[0047] II. Respectively perform elemental surface distribution analysis detection on the iron-modified coconut shell biochar prepared in Example 1 and the original coconut shell biochar prepared in Comparative Example 1. The results are shown in Figure 3-4 .
[0048] It can be seen from Figure 3-4 that a large amount of Fe element is distributed on the surface of ferric chloride-modified coconut shell biochar.
[0049] III. Performance Detection 1. The iron-modified coconut shell biochar (MCSB-FeCl3) prepared in Example 1 of the present invention is applied to sludge dewatering, and the sludge moisture content is measured according to "Test Methods for Sludge from Municipal Wastewater Treatment Plants" (CJ / T 221-2023). Weigh a certain amount of mashed and homogenized sludge with an evaporating dish that has been weighed to a constant weight of m1, and accurately weigh this sample to 0.001 g, denoted as m. Place the evaporating dish containing the sample in an oven at 103 - 105 °C and dry it for 2 h, take it out, place it in a desiccator and cool it to room temperature, then weigh it. Repeat this process several times until the weight is constant, denoted as m2.
[0050] Calculation:
[0051] In the formula: m: The value of the mass of the sludge sample taken, unit: gram (g); m1: The value of the mass of the evaporating dish after constant weight, unit: gram (g); m2: The value of the mass of the sludge sample after constant weight plus the mass of the evaporating dish after constant weight, unit: gram (g).
[0052] Specific example: Application Example 1: (1) Take 200 g of excess sludge with a moisture content of 98.6 ± 0.2% and place it in a 250 mL beaker. Turn on the stirrer, add MCSB-FeCl3 equivalent to 20% of the dry sludge mass to the sludge mixture, and stir with the stirrer to fully mix the sludge mixture and the rice husk biochar evenly; (2) Pour the conditioned sludge mixture into a Buchner funnel for sludge suction filtration and dehydration. Set the vacuum pump to 0.03 MPa. Stop suction filtration when the sludge cake cracks. Collect the suction-filtered sludge cake for subsequent experiments; (3) Take 30 g of the suction-filtered sludge cake, wrap it with filter cloth, and put it into a dehydration device for pressure filtration and dehydration. The pressure filtration pressure is 0.058 MPa. Start timing after reaching the set pressure. Set the pressure filtration time to 30 min. Stop pressure filtration when the timing ends, and the sludge dehydration is completed. The moisture content of the dehydrated sludge cake is 72.08%.
[0053] Application Example 2: In step (1), add MCSB-FeCl3 equivalent to 40% of the dry sludge mass to the sludge mixture, and the rest is the same as Application Example 1.
[0054] The moisture content of the dehydrated sludge cake is 68.52%.
[0055] 2. Dehydrate the sludge without adding biochar, and apply the original coconut shell biochar (CSB) prepared in the comparative example to sludge dehydration. Specific examples are given for comparison with this application: Comparative Application Example 1: In step (1), no MCSB-FeCl3 is added, and the rest is the same as Application Example 1.
[0056] The moisture content of the dehydrated sludge cake is 77.32%.
[0057] Comparative Application Example 2: In step (1), no MCSB-FeCl3 is added, and the added CSB is the one prepared in Comparative Example 1. The rest is the same as Application Example 1.
[0058] The moisture content of the dehydrated sludge cake is 77.04%.
[0059] Table 1 Performance Detection Comparison
[0060] The iron-modified coconut shell biochar conditioning for sludge dewatering proposed by the present invention has achieved better results in reducing the moisture content of sludge compared with direct dewatering of the original sludge and dewatering of sludge conditioned with the original coconut shell biochar.
[0061] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A preparation method of iron-modified coconut shell biochar, characterized in that, It includes the following steps: (1) Pyrolytic carbonize the coconut shell powder. After cooling, grind, sieve, wash and dry it in sequence to obtain the original coconut shell biochar; (2) Immerse the original coconut shell biochar obtained in step (1) in hydrochloric acid solution, stir, wash, filter by suction to obtain the precipitate; (3) Immerse the precipitate obtained in step (2) in ferric chloride solution, stir, perform ultrasonic treatment, wash, filter by suction, dry, sieve to obtain the iron-modified coconut shell biochar.
2. The preparation method of the iron-modified coconut shell biochar according to claim 1, characterized in that In step (1), the coconut shell powder is obtained by the following method: wash, dry and crush the coconut shell to obtain the coconut shell powder.
3. The preparation method of the iron-modified coconut shell biochar according to claim 1, characterized in that, In step (1), pyrolytic carbonization is carried out under the N2 atmosphere.
4. The preparation method of the iron-modified coconut shell biochar according to claim 1, wherein, In step (1), pyrolytic carbonization is carried out at 700 - 900 °C for 50 - 80 min.
5. The preparation method of the iron-modified coconut shell biochar according to claim 1, characterized in that, In step (1), the particle size of the original coconut shell biochar is 0.15 - 0.178 μm.
6. The preparation method of the iron-modified coconut shell biochar according to claim 1, characterized in that, In step (2), the concentration of the hydrochloric acid solution is 1 - 1.5 mol / L.
7. The preparation method of the iron-modified coconut shell biochar according to claim 1, characterized in that In step (3), the concentration of the ferric chloride solution is 2 - 3 mol / L.
8. The preparation method of the iron-modified coconut shell biochar according to claim 1, wherein, In step (3), ultrasonic treatment is carried out at 30 - 40 °C for 0.4 - 0.6 h.
9. The iron-modified coconut shell biochar prepared by the preparation method of the iron-modified coconut shell biochar according to any one of claims 1 - 8.
10. The application of the iron-modified coconut shell biochar according to claim 9 in sludge dewatering.