Magnetically modified rice husk biochar as well as preparation method and application thereof
By impregnating sodium lignin sulfonate and nanoscale iron tetraoxide in rice husk biochar, magnetically modified rice husk biochar with efficient adsorption and catalytic degradation is solved, and the problems of low adsorption rate and difficulty in separation in the prior art are achieved efficiently remove methyl orange in printing and dyeing wastewater.
Patent Information
- Application Number
- CN202510214832.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2025-06-17
AI Technical Summary
The existing rice husk biochar has low adsorption rate and difficulty in separating methyl orange in printing and dyeing wastewater, which cannot effectively solve the problem of environmental pollution.
By impregnating sodium lignin sulfonate into rice husk biochar and pyrolyzed at high temperature, a rich microporous structure was formed; at the same time, nano-scale iron tetroxide was loaded on the surface of lignin modified biochar by co-precipitation method to increase adsorption points and catalytic activity.
The adsorption rate of rice husk biochar to methyl orange is significantly improved, and it is quickly separated and recovered by magnets, reducing the processing energy consumption and achieving efficient adsorption and catalytic degradation effects.
Smart Images
Figure CN120155162A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of adsorption materials, and particularly relates to a magnetic modified rice husk biochar, a preparation method thereof and an application thereof. Background Art
[0002] Methyl orange (MO) is a common and typical acidic anionic monoazo dye, which has the characteristics of high toxicity and difficult degradation, and is generally present in printing and dyeing wastewater. If the printing and dyeing wastewater containing MO is not properly treated, it will remain in the environment for a long time, bringing great harm to the growth of animals and plants and human health. Therefore, great attention should be paid to the pollution problem of MO, and effective pollution remediation technologies should be studied.
[0003] The adsorption method is simple to operate and has good economic benefits, and is the most commonly used method for removing dyes in water. As a typical biomass resource, the biochar produced by direct pyrolysis of rice husk can be used for the adsorption of fuels in printing and dyeing wastewater. It has low production cost and stable structure, but its adsorption capacity is limited, the adsorption rate is low and the separation is difficult; therefore, it is necessary to develop a new type of adsorption material with a higher adsorption rate and easy separation. Summary of the Invention
[0004] The purpose of the present invention is to provide a magnetic modified rice husk biochar, a preparation method thereof and an application thereof, so as to solve the problems in the background art.
[0005] The purpose of the present invention can be achieved by the following technical solutions:
[0006] A preparation method of a magnetic modified rice husk biochar, comprising the following steps:
[0007] Step S1, adding sodium lignosulfonate to deionized water, stirring and dissolving, then adding rice husk biochar, stirring and impregnating at 25°C for 24 h, drying and then transferring it into a tubular furnace, and thermally decomposing at a constant temperature of 600°C for 2 h to obtain lignin modified biochar; by the impregnation method, an appropriate amount of lignin is impregnated into the primary pores of the rice husk biochar, and by occupying the larger pores, more micropores are created after pyrolysis to improve the adsorption rate;
[0008] Step S2: Place ultrapure water in a three-necked flask, stir while introducing nitrogen at room temperature to exhaust the air in the flask, then add lignin-modified biochar and stir to mix. Next, add ferric chloride hexahydrate and ferrous sulfate heptahydrate, and stir in a water bath until completely dissolved. Then, slowly and evenly add concentrated ammonia water, stir and react for 120 min under nitrogen protection. After the reaction, separate the solid with a magnet and vacuum dry at 80 °C for 24 h to obtain magnetically modified rice husk biochar. Adding an alkali to the iron salt solution provides an alkaline environment to generate nanoscale magnetite particles. By using the co-precipitation method to load nanoscale magnetite on the surface of lignin-modified biochar, it can not only prevent the aggregation of nanoscale magnetite, increase the surface adsorption sites and specific surface area of biochar, and improve its adsorption capacity for pollutants, but also increase the redox active sites on the biochar surface and improve its catalytic degradation performance for organic matter.
[0009] Further, the dosage ratio of sodium lignosulfonate, rice husk biochar, and deionized water is 1 g: 2 - 4 g: 100 mL. When the amount of sodium lignosulfonate is lower than that in this application, it can only fill some of the primary pores of rice husk biochar and cannot create smaller pores after pyrolysis, thus unable to play a role in modulating the pore size of biochar. When the amount of sodium lignosulfonate is higher than that in this application, it will not only enter the primary pores of rice husk biochar but also agglomerate and cover the outer surface of rice husk biochar, blocking the original pores and reducing the specific surface area of lignin-modified biochar, thereby affecting the adsorption rate of the final product.
[0010] Further, the rice husk biochar is prepared through the following steps:
[0011] Wash the rice husk raw material with clean water, place it in an oven at 80 °C and dry for 24 h, then crush and sieve it, and then transfer it to a tube furnace. Heat it to 600 °C under nitrogen protection and hold for 2 h to obtain rice husk biochar. Using rice husk as the raw material can realize the resource utilization of agricultural waste and reduce incineration pollution. There are no toxic reagents added during the preparation process, and the product can efficiently treat printing and dyeing wastewater, solving the problem of secondary pollution of traditional adsorbents, with significant environmental and social benefits.
[0012] Further, the pore size of the sieve is 50 - 70 mesh.
[0013] Further, the heating rate is 8 - 10 °C / min. Using gradient heating can ensure the stability of the pore structure of the raw material during carbonization.
[0014] Further, the drying treatment is to first evaporate the water in a water bath at 90 - 95 °C and then dry in an oven at 80 °C for 12 h. The two-stage drying of water bath evaporation and low-temperature drying can effectively avoid the collapse of the pore structure caused by sudden high-temperature changes.
[0015] Furthermore, the dosage ratio of the ultrapure water, lignin-modified biochar, ferric chloride hexahydrate, ferrous sulfate heptahydrate, and concentrated ammonia water is 300 mL: 3 - 4 g: 5.4 g: 2.8 g: 30 mL. Generally speaking, increasing the content of iron oxide (magnetite) can provide more active adsorption sites, which is conducive to enhancing the adsorption capacity. However, limited by the specific surface area and pore structure of the biochar, an excessive loading amount often causes the agglomeration of iron oxide and the blockage of biochar pores, reducing the dispersion and accessibility of adsorption sites, and instead decreasing the adsorption rate of the biochar. In the present invention, the loading amount of magnetite in the magnetic modified rice husk biochar is controlled to be approximately 30%.
[0016] Furthermore, the volume fraction of the concentrated ammonia water is 25%.
[0017] A magnetic modified rice husk biochar is prepared by the above preparation method. The magnetic modified biochar has an extremely high specific surface area and a rich pore structure, which endows it with a strong adsorption capacity.
[0018] An application of the magnetic modified rice husk biochar in the adsorption treatment of methyl orange in printing and dyeing wastewater. Methyl orange molecules form electrostatic interactions or combine through hydrogen bonds, ionic bonds, π-π interactions, etc. on the effective adsorption sites on the surface of the magnetic modified biochar, thereby adsorbing methyl orange molecules in the printing and dyeing wastewater.
[0019] The beneficial effects of the present invention:
[0020] By precisely controlling the dosage ratio of lignin and rice husk biochar, the present invention enables sodium lignosulfonate to impregnate and fill the primary pores of the rice husk biochar, and then form a rich microporous structure through high-temperature pyrolysis, modulating the pore size of the rice husk biochar. At the same time, it can avoid the blockage of pores by excessive lignin, significantly improving the adsorption rate of the rice husk biochar for methyl orange. Through the specific ratio of lignin-modified biochar and iron salt, the present invention uses the coprecipitation method to achieve the uniform dispersion of nanoscale magnetite on the surface of the lignin-modified biochar. It can not only effectively prevent the agglomeration of nanoscale magnetite, but also form rich redox active adsorption sites on the surface of the lignin-modified biochar, which can catalyze the degradation of organic substances such as methyl orange, realizing the adsorption-catalysis synergistic effect, and further improving the adsorption performance of the lignin-modified biochar for methyl orange. In addition, the prepared magnetic modified rice husk biochar can be quickly separated and recovered by a magnet, reducing the energy consumption of traditional centrifugation or filtration and improving the treatment efficiency.
[0021] Through the multi-scale structure design and functional modification, the present invention breaks through the bottleneck of low adsorption rate and difficult recovery of traditional biochar, and has the characteristics of high-efficiency adsorption, catalytic degradation, and magnetic separation, providing an innovative solution for the treatment of printing and dyeing wastewater. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The present invention will be further described below with reference to the accompanying drawings.
[0023] Figure 1 It is a physical picture of the magnetically modified rice husk biochar prepared in Example 2 of the present invention. Specific Embodiments
[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.
[0025] Example 1
[0026] This example provides a magnetically modified rice husk biochar, which is prepared by the following steps:
[0027] Step S1: After washing the rice husk raw material with clean water, place it in an oven at 80 °C for 24 h of drying, then pulverize it and pass through a 50-mesh sieve, and then transfer it to a tubular furnace. Under the protection of nitrogen, heat it to 600 °C at a heating rate of 8 °C / min and hold for 2 h to obtain rice husk biochar;
[0028] Step S2: Add 1 g of sodium lignosulfonate to 100 mL of deionized water and stir to dissolve it, then add 2 g of rice husk biochar, stir and impregnate at 25 °C for 24 h. First, evaporate the water in a water bath at 90 °C, and then dry it in an oven at 80 °C for 12 h. Transfer it to a tubular furnace and pyrolyze it at a constant temperature of 600 °C for 2 h to obtain lignin-modified biochar;
[0029] Step S3: Place 300 mL of ultrapure water in a three-necked flask, while stirring at room temperature, introduce nitrogen to exhaust the air in the flask, then add 3 g of lignin-modified biochar and stir to mix. Then add 5.4 g of ferric chloride hexahydrate and 2.8 g of ferrous sulfate heptahydrate, stir in a water bath until completely dissolved, and then slowly dropwise add 30 mL of concentrated ammonia water with a volume fraction of 25%. Stir and react under the protection of nitrogen for 120 min. After the reaction, separate the solid with a magnet and vacuum dry it at 80 °C for 24 h to obtain magnetically modified rice husk biochar.
[0030] Example 2
[0031] This example provides a magnetically modified rice husk biochar, which is prepared by the following steps:
[0032] Step S1: After washing the rice husk raw material with clean water, place it in an oven at 80 °C for 24 h of drying, then pulverize it and pass through a 60-mesh sieve, and then transfer it to a tubular furnace. Under the protection of nitrogen, heat it to 600 °C at a heating rate of 10 °C / min and hold for 2 h to obtain rice husk biochar;
[0033] Step S2: Add 1 g of sodium lignosulfonate to 100 mL of deionized water, stir to dissolve, then add 3 g of rice husk biochar, stir and impregnate at 25 °C for 24 h. First, evaporate the water in a water bath at 92 °C, then dry in an oven at 80 °C for 12 h, transfer to a tubular furnace and pyrolyze at a constant temperature of 600 °C for 2 h to obtain lignin-modified biochar;
[0034] Step S3: Place 300 mL of ultrapure water in a three-necked flask, while stirring at room temperature, introduce nitrogen to exhaust the air in the flask, then add 3.5 g of lignin-modified biochar and stir to mix. Then add 5.4 g of ferric chloride hexahydrate and 2.8 g of ferrous sulfate heptahydrate, stir in a water bath until completely dissolved, then slowly dropwise add 30 mL of concentrated ammonia water with a volume fraction of 25%, stir and react for 120 min under nitrogen protection. After the reaction, separate the solid with a magnet and dry in vacuo at 80 °C for 24 h to obtain magnetically modified rice husk biochar. As Figure 1 shown is the physical display of the magnetically modified rice husk biochar prepared in this example.
[0035] Example 3
[0036] This example provides a magnetically modified rice husk biochar, which is prepared by the following steps:
[0037] Step S1: Wash the rice husk raw material with clean water, place it in an oven at 80 °C and dry for 24 h, then pulverize and pass through a 70-mesh sieve, and then transfer to a tubular furnace. Under nitrogen protection, heat to 600 °C at a heating rate of 9 °C / min and hold for 2 h to obtain rice husk biochar;
[0038] Step S2: Add 1 g of sodium lignosulfonate to 100 mL of deionized water, stir to dissolve, then add 4 g of rice husk biochar, stir and impregnate at 25 °C for 24 h. First, evaporate the water in a water bath at 95 °C, then dry in an oven at 80 °C for 12 h, transfer to a tubular furnace and pyrolyze at a constant temperature of 600 °C for 2 h to obtain lignin-modified biochar;
[0039] Step S3: Place 300 mL of ultrapure water in a three-necked flask, while stirring at room temperature, introduce nitrogen to exhaust the air in the flask, then add 4 g of lignin-modified biochar and stir to mix. Then add 5.4 g of ferric chloride hexahydrate and 2.8 g of ferrous sulfate heptahydrate, stir in a water bath until completely dissolved, then slowly dropwise add 30 mL of concentrated ammonia water with a volume fraction of 25%, stir and react for 120 min under nitrogen protection. After the reaction, separate the solid with a magnet and dry in vacuo at 80 °C for 24 h to obtain magnetically modified rice husk biochar.
[0040] Comparative Example 1
[0041] In this comparative example, compared with Example 2, the difference lies in that in step S2, the dosage of rice husk biochar is replaced from 3 g to 1 g, and the dosages of other raw materials and the steps are the same.
[0042] Comparative Example 2
[0043] In this comparative example, compared with Example 2, the difference lies in that in step S2, the dosage of rice husk biochar is replaced from 3 g to 5 g, and the dosages of other raw materials and the steps are the same.
[0044] Comparative Example 3
[0045] In this comparative example, compared with Example 2, the difference lies in that in step S2, “first evaporate the water in a water bath at 95 °C, and then dry in an oven at 80 °C for 12 h” is replaced by “directly dry to constant weight in an oven at 90 °C”, and the dosages of other raw materials and the steps are the same.
[0046] Comparative Example 4
[0047] In this comparative example, compared with Example 2, the difference lies in that in step S3, the dosage of lignin-modified biochar is replaced from 3.5 g to 2 g, and the dosages of other raw materials and the steps are the same.
[0048] Comparative Example 5
[0049] In this comparative example, compared with Example 2, the difference lies in that in step S3, the dosage of lignin-modified biochar is replaced from 3.5 g to 5 g, and the dosages of other raw materials and the steps are the same.
[0050] Comparative Example 6
[0051] In this comparative example, compared with Example 2, the difference lies in that the operation of step S3 is not carried out, and the lignin-modified biochar is directly used as the final adsorption material.
[0052] Perform performance tests on the magnetically modified rice husk biochar prepared in Examples 1 - 3 and Comparative Examples 1 - 6. Add the magnetically modified rice husk biochar to a 50 mL methyl orange solution with an initial concentration C0 of 40 mg / L and a pH of 4 at a dosage of 4 g / L, and the reaction treatment time is 150 min. Then record the remaining concentration C e , and then calculate the adsorption rate η of the magnetically modified rice husk biochar according to the following formula:
[0053]
[0054] The results are shown in Table 1:
[0055] Table 1
[0056] Group <![CDATA[C0 (mg / L)]]> <![CDATA[C e (mg / L)]]> η(%) Example 1 40 7.75 80.63 Example 2 40 7.14 82.15 Example 3 40 7.59 81.03 Comparative Example 1 40 14.18 64.55 Comparative Example 2 40 14.76 63.10 Comparative Example 3 40 8.61 78.48 Comparative Example 4 40 10.30 74.25 Comparative Example 5 40 10.48 73.80 Comparative Example 6 40 12.21 69.48
[0057] As can be seen from the data in Table 1, the magnetically modified rice husk biochar prepared in Examples 1-3 has a higher adsorption rate for methyl orange. By controlling the dosage ratio of sodium lignosulfonate to rice husk biochar and the dosage ratio of lignin-modified biochar to iron salt, magnetically modified rice husk biochar with better adsorption performance can be obtained. At the same time, by cooperating with the drying treatment method, the structure stability of the magnetically modified rice husk biochar can be ensured, so as to obtain an adsorption material with better adsorption performance.
[0058] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.
[0059] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for preparing magnetically modified rice husk biochar, characterized in that: The following steps are involved: Step S1, adding sodium lignin sulfonate into deionized water and stirring to dissolve, then adding rice husk biochar and stirring to impregnate, after drying, transferring into a tubular furnace, and pyrolyzing at a constant temperature of 600° C. to obtain lignin modified biochar; Step S2, placing ultrapure water in a three-necked flask, introducing nitrogen while stirring at room temperature, then adding lignin-modified biochar and stirring to mix, then adding ferric chloride hexahydrate and ferrous sulfate heptahydrate and stirring in a water bath until completely dissolved, then dropping concentrated ammonia water, stirring to react under nitrogen protection, separating the solid with a magnet after the reaction is completed, and vacuum drying to obtain magnetically modified rice husk biochar.
2. The method for preparing magnetically modified rice husk biochar according to claim 1, characterized in that: The dosage ratio of the sodium lignin sulfonate, rice husk biochar and deionized water is 1g:2-4g:100mL.
3. The method for preparing magnetically modified rice husk biochar according to claim 1, characterized in that: The rice husk biochar is prepared by the following steps: The rice husk raw material was washed with clean water and dried, then crushed and sieved, and then transferred into a tubular furnace, heated to 600°C under nitrogen protection and kept warm for 2 hours to obtain rice husk biochar.
4. The method for preparing magnetically modified rice husk biochar according to claim 3, characterized in that: The pore size of the sieve is 50-70 mesh.
5. The method for preparing magnetically modified rice husk biochar according to claim 3, characterized in that: The heating rate is 8-10°C / min.
6. The method for preparing magnetically modified rice husk biochar according to claim 1, characterized in that: The drying process is to first evaporate the water in a water bath at 90-95° C., and then dry in an oven at 80° C. for 12 hours.
7. The method for preparing magnetically modified rice husk biochar according to claim 1, characterized in that: The usage ratio of the ultrapure water, lignin-modified biochar, ferric chloride hexahydrate, ferrous sulfate heptahydrate and concentrated ammonia water is 300 mL: 3-4 g: 5.4 g: 2.8 g: 30 mL.
8. The method for preparing magnetically modified rice husk biochar according to claim 1, characterized in that: The volume fraction of the concentrated ammonia water is 25%.
9. A magnetically modified rice husk biochar, characterized in that: Prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the magnetically modified rice husk biochar according to claim 9 in the adsorption treatment of methyl orange in printing and dyeing wastewater.